North Star QRA Update - Chlorine and VCM plant (Rafnes) Report for: Wood - Direktoratet for samfunnssikkerhet og ...

 
North Star QRA Update - Chlorine and VCM plant (Rafnes) Report for: Wood - Direktoratet for samfunnssikkerhet og ...
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    North Star QRA Update
    Chlorine and VCM plant (Rafnes)

    Report for:
    Wood

Report no: PRJ11090011 Rev: Final
Date: 11 January 2019
North Star QRA Update - Chlorine and VCM plant (Rafnes) Report for: Wood - Direktoratet for samfunnssikkerhet og ...
North Star QRA Update - Chlorine and VCM plant (Rafnes) Report for: Wood - Direktoratet for samfunnssikkerhet og ...
Document history
 Revision       Date           Description/changes                Changes made by

 Draft          30.11.2018     First issue of report              Andrea Risan / Ingebjørg Valkvæ / Stian Jensen

 Final          11.01.2019     Comments from client               Andrea Risan / Ingebjørg Valkvæ
                               incorporated

Executive summary
Lloyds Register (LR) has been engaged by Wood and INOVYN Norge to conduct an update of the quantitative
risk assessment (QRA) of the Chlorine and VCM plant at the Rafnes Industrial Site (Grenland, Norway) to
accommodate any changes in the risk picture due to the North Star project. The North Star project includes
implementation of several modifications to the facility which will increase the total production capacity with
around 10 %.

The QRA update is conducted by using the existing risk model of the facility and adding the events potentially
caused by the planned modifications. A similar approach as applied in the existing QRA is applied in the risk
assessment of the North Star modifications. In that manner the risk level before and after the modification can
be compared. The risk acceptance criteria proposed by DSB are applied in the study. Hence, the focus in the
study is directed towards major accident events that may cause fatal exposure outside of the boundary of the
facility.

The main conclusion of the study is that the North Star project only contributes with a modest risk increase to
third parties, and that the main risk drivers remain unchanged after the update. It is still toxic releases of chlorine
and HCl that dominates the risk picture, in addition to BLEVE events in the VCM storage area. The calculated risk
picture is shown in the below figure.

Report no: PRJ11090011 Rev: Final                                                                                 Page ii
Date: 11 January 2019                                                                              ©Lloyd’s Register 2019
North Star QRA Update - Chlorine and VCM plant (Rafnes) Report for: Wood - Direktoratet for samfunnssikkerhet og ...
Glossary/abbreviations
ALARP                         As Low As Reasonably Practicable

AT                            The Norwegian Labour Inspection Authority (Arbeidstilsynet). A
                              governmental agency under the Ministry of Labour, focused on occupational
                              safety and health

BLEVE                         Boiling Liquid Expanding Vapour Explosion

CFD                           Computational Fluid Dynamics

DSB                           Norwegian Directorate for civil protection (Direktoratet for
                              Samfunnssikkerhet og Beredskap)

EDC                           Ethylene DiChloride, 1,2-dichloroethane

ESD                           Emergency Shut Down

EX                            Ex-equipment or explosive protected equipment, both electric and
                              mechanical.

FTM                           Forslag Til Modifikasjoner

Hazardous substances          Flammable, reactive, pressurised and explosive substances

HAZID                         Hazard Identification

Report no: PRJ11090011 Rev: Final                                                                               Page iii
Date: 11 January 2019                                                                            ©Lloyd’s Register 2019
North Star QRA Update - Chlorine and VCM plant (Rafnes) Report for: Wood - Direktoratet for samfunnssikkerhet og ...
HCl                           Hydrogen Chloride

HTDC                          High Temperature Direct Chlorination

IR                            Individual Risk

LFL                           Lower Flammability Limit

LNF                           Landbruk-, Natur- og Friluftsområde

LOC                           Loss Of Containment

OHCL                          Oxy HydroChlorination

PSD                           Process Shut Down

QRA                           Quantitative Risk Analysis

RAC                           Risk Acceptance Criteria

Safeti                        Safeti QRA software tool - A user-friendly, industry standard method for
                              carrying out Quantitative Risk Assessments (QRA) of onshore process,
                              chemical and petrochemical facilities. Developed by DNV-GL.

Third party (3rd person)      People outside the production plant that may be affected by its activities.

                              (2nd person: People that are not directly related to the operation of the
                              plant, but benefit from being close to the plant

                              1st person: People who are directly involved in the operations of the plant,
                              i.e. the employees at the plant)

VCM                           Vinyl Chloride Monomer

Report no: PRJ11090011 Rev: Final                                                                                Page iv
Date: 11 January 2019                                                                             ©Lloyd’s Register 2019
North Star QRA Update - Chlorine and VCM plant (Rafnes) Report for: Wood - Direktoratet for samfunnssikkerhet og ...
Table of contents                                                                 Page

1      Introduction                                                                     1
       1.1    Background                                                                1
       1.2    Objective                                                                 1
       1.3    Scope of work                                                             1
       1.4    Presumptions and limitations                                              1
              1.4.1       Presumptions                                                  1
              1.4.2       Limitations                                                   1
       1.5    Regulations and standards                                                 2
2      Framework                                                                        2
       2.1    Methodology                                                               2
       2.2    Assumptions and input data                                                4
       2.3    Acceptance criteria                                                       4
3      System description                                                               5
       3.1    General description                                                       5
       3.2    Process description                                                       5
              3.2.1       Chlorine – INOVYN scope                                       5
              3.2.2       VCM – Wood scope                                              6
       3.3    North Star project                                                        7
              3.3.1       VCM plant modifications                                       7
              3.3.2       Safety measures for the new HTDC module                       8
              3.3.3       Water curtain in the HTDC module                              8
              3.3.4       Chlorine plant modifications                                  9
       3.4    Safety measures                                                           9
              3.4.1       Pressure monitoring and shutdown                              9
              3.4.2       Chlorine absorption system                                    9
              3.4.3       Gas detection and emergency shutdown                          9
              3.4.4       Fire proofing of storage spheres                              9
              3.4.5       Emergency preparedness                                        9
4      Selection of hazardous events                                                    9
       4.1    Existing QRA                                                              9
       4.2    Scenarios for the new HTDC module                                       11
       4.3    Scenarios for the new OHCL reactor                                      12
       4.4    Risk screening of other North Star modifications                        12
5      Frequency analysis                                                             14
6      Consequence analysis                                                           15
       6.1    Event tree                                                              15
       6.2    Fatality criteria                                                       16
       6.3    Consequence modelling                                                   16
7      Risk picture and risk evaluation                                               18
       7.1    Total risk picture                                                      18

Report no: PRJ11090011 Rev: Final                                                  Page v
Date: 11 January 2019                                               ©Lloyd’s Register 2019
North Star QRA Update - Chlorine and VCM plant (Rafnes) Report for: Wood - Direktoratet for samfunnssikkerhet og ...
7.2    Risk from the chlorine plant                                19
       7.3    Risk from the VCM plant                                     21
       7.4    Individual risk at nearest resident                         24
8      Uncertainties                                                      26
9      Potential conservatism in the QRA                                  26
       9.1    Release durations and transient effects                     26
       9.2    Terrain effects                                             27
       9.3    Release modelling                                           27
       9.4    Event frequencies                                           27
       9.5    BLEVE                                                       27
       9.6    Flash fire envelope                                         27
10     Conclusion and recommendations                                     28
       10.1 Recommendations                                               28
       10.2 Conclusions                                                   28
11     References                                                         29

Appendix A – Assumptions and input data
Appendix B – Risk screening workshop – VCM plants
Appendix C – Risk screening workshop – Chlorine plant

Report no: PRJ11090011 Rev: Final                                      Page vi
Date: 11 January 2019                                   ©Lloyd’s Register 2019
North Star QRA Update - Chlorine and VCM plant (Rafnes) Report for: Wood - Direktoratet for samfunnssikkerhet og ...
1        Introduction
1.1      Background
         Lloyd’s Register (LR) has been engaged by Wood and INOVYN Norge to carry out an update of the
         quantitative risk assessment (QRA) for INOVYN’ s Chlorine and Vinyl Chloride Monomer (VCM) plant at
         the Rafnes Industrial Site (Rafnes) conducted in 2015 (Ref. /1/).
         The North Star project introduces several modifications to the Chlorine and VCM plant in order to
         increase the production capacity of the plant. The modifications include:
         •    Installation of a new High Temperature Direct Chlorination (HTDC) module
         •    Replacing the existing Oxy HydroChlorination (OHCL) reactor with a new one
         •    Several other modifications to process vessels and equipment in the VCM plant to allow for the
              increased capacity
         •    Installation of a new electrolyser in the chlorine plant
         •    Replacement of the hydrogen compressor, chlorine compressor and chlorine cooler.
         INOVYN Norge is classified as a so called major accident facility according to “Storulykkeforskriften”
         (Ref. /9/). Hence, the facility is required by regulations to minimize the risk for major accidents. The QRA
         can be seen as part of the effort to reach this objective.

1.2      Objective
         The objective of the QRA update is to investigate the impact of the North Star project on the existing
         risk picture at INOVYN’s facility at Rafnes. The modifications will be assessed and included in the existing
         QRA of the facility. Potential risk drivers will be identified, and it will be evaluated if the project
         introduces significant change in the risk for third parties. The proposed risk acceptance criteria by DSB
         (Ref. /2/) are applied in the risk assessment.

1.3      Scope of work
         The scope of work involves using the risk model developed in the existing QRA of INOVYN’s facility at
         Rafnes as a starting point. The risk model is implemented using the Safeti software. Events introduced
         by the North Star project will be handled in a similar manner as in the existing QRA by using, e.g., the
         same event frequency references, fatality criteria and overall assumptions as a basis. The focus in the
         QRA is to address major accidental events that may influence the extent of risk zones (“hensynssoner”
         in Norwegian) around the facility.

1.4      Presumptions and limitations
1.4.1 Presumptions
         The following presumptions apply to the study:
         1. Normal operation including regular shut down and maintenance and start up activities are the base
            of the QRA.
         2. If risk reducing measures are disengaged during operation, it is a prerequisite that compensating
            measures are implemented so that the barrier’s function is kept. If compensating measures are not
            taken, the QRA is not valid.
1.4.2 Limitations
         The following limitations apply to the study:
         1.   Events while ship is at sea or mooring are not included
         2.   The ships on-board systems (tanks, pumps, piping) are not included

Report no: PRJ11090011 Rev: Final                                                                                Page 1
Date: 11 January 2019                                                                             ©Lloyd’s Register 2019
North Star QRA Update - Chlorine and VCM plant (Rafnes) Report for: Wood - Direktoratet for samfunnssikkerhet og ...
3.   The tunnel with export pipelines to Herøya is not included. A separate risk assessment for the
              tunnel has been conducted, Ref. /3/
         4.   Escalation effects have not been quantified. An escalation is defined as an initial event on the site,
              e.g. a fire that impairs other equipment containing flammable or toxic material on the same site.
              Thereby leading to a larger fire or more severe toxic effects. One exception is the inclusion of
              Boiling Liquid Expanding Vapour Explosion (BLEVE) events in the QRA. A BLEVE can be considered
              as an escalated event, since a prerequisite for such a scenario to occur is long exposure time to
              relatively high heat loads, i.e. fire exposure.
         5.   Domino effects, e.g. events where fire and explosion triggers new release scenarios (or other
              effects) from equipment in adjacent facilities, have not been calculated specifically. Domino effects
              are discussed in the risk analysis from 1991 and 1998 (Ref. /4/ and /5/) and in the report "Vurdering
              av dominoeffekter mellom fabrikkanleggene på Borealis AS, Noretyl AS og Hydro Polymers AS i
              forbindelse oppdatering av Sikkerhetsrapporten for Hydro Polymers og Noretyl", Ref. /6/.

1.5      Regulations and standards
         The most central regulations related to health, safety and the environment (HSE) for the onshore
         chemical process industry which come under the supervisory authority of the DSB and AT are found in
         the HSE regulations and the working environment regulations.
         The following relevant regulations apply for INOVYN Norge and set the premise for the current risk
         assessment:
         •    DSB: "Forskrift om håndtering av brannfarlig, reaksjonsfarlig og trykksatt stoff samt utstyr og
              anlegg som benyttes ved håndteringen (forskrift om håndtering av farlig stoff) ", FOR-2009-06-08-
              602, 8. juni 2009, Ref. /7/.
         •    DSB Temaveileder ”Sikkerheten rundt anlegg som håndterer brannfarlige, reaksjonsfarlige,
              trykksatte og eksplosjonsfarlige stoffer: Kriterier for akseptabel risiko”, May 2013, Ref. /8/.
         •    Storulykkeforskriften FOR-2005-06-17-672, Council Directive 96/82/EC of 9 December 1996 on the
              control of major-accident hazards involving dangerous substances, Ref. /9/.
         Also note, that since the QRA was established, DSB has introduced a new guideline for conducting
         QRAs, i.e. “Retningslinjer for kvantitative risikovurderinger for anlegg som håndterer farlig stoff” (Ref.
         /10/). Those new guidelines are not adopted at the present stage.

2        Framework
2.1      Methodology
         The overall methodology used in the QRA is illustrated in Figure 2.1.

Report no: PRJ11090011 Rev: Final                                                                                 Page 2
Date: 11 January 2019                                                                              ©Lloyd’s Register 2019
North Star QRA Update - Chlorine and VCM plant (Rafnes) Report for: Wood - Direktoratet for samfunnssikkerhet og ...
Figure 2.1 - QRA methodology

         The building blocks of the study are briefly discussed below.
         1.   Risk acceptance criteria
         The acceptance criteria are used to evaluate the risk and aid in decisions regarding need for risk
         reducing measures. The acceptance criteria applicable for this project are presented in Chapter 2.3.
         2.   System definition
         A presentation of the system included in the scope of the QRA and its limitations are presented in
         Chapter 3.
         3.   Hazard identification
         A hazard identification (HAZID) workshop was performed at Rafnes during the previous QRA update in
         2015 and was used to define relevant scenarios for the QRA.
         A risk screening workshop identifying the possible hazards related to the modifications of the North Star
         project was performed at Rafnes in October 2018. The results from the risk screening workshop are
         summarized in Chapter 4 and documented in Appendix B and C.
         4.   Frequency analysis
         The frequency analysis is performed to select and define a set of scenarios that represent the risk posed
         by the Chlorine and VCM plant. The frequency analysis is described in Chapter 5.
         5.   Consequence analysis
         The possible consequences from each scenario from the frequency analysis are simulated using the
         software Safeti. The consequence analysis is described in Chapter 6.
         6.   QRA results – Risk picture and risk evaluation
         The risk picture is the result of the frequency analysis and the consequence analysis. The resulting risk
         picture for the Chlorine and VCM plant is presented in Chapter 7. The risk is evaluated by comparing
         the resulting risk picture with the applied RAC.
         7.   Risk-reducing measures
         Risk-reducing measures are recommended in order to meet the acceptance criteria or to further reduce
         the risk in line with ALARP. Recommendations are given in Chapter 10.

Report no: PRJ11090011 Rev: Final                                                                                Page 3
Date: 11 January 2019                                                                             ©Lloyd’s Register 2019
2.2      Assumptions and input data
         All assumptions made in the study are presented in the assumption sheets in Appendix A together with
         any data used for the study including wind data, population data and vulnerabilities.

2.3      Acceptance criteria
         This study applies the Risk Acceptance Criteria (RAC) proposed by Norwegian authority DSB (Ref. /8/) in
         their guidance document regarding RAC for facilities storing and handling hazardous substances. The
         RAC are based on the individual risk contours calculated for the facility, and defines a number of zones
         for special consideration. The RAC are presented in Table 2-1 and Figure 2.2.
         Table 2-1 - Acceptance criteria, defined zones for consideration
          Zone for                  Acceptance criteria          Provisions for the zone (accepted
          consideration                                          object and activities in the zone)
          Inner zone                IR is higher than 1E-5 per   Primarily within the facility’s property
                                    year                         limits, extension into LNF-areas may be
                                                                 allowed.
          Intermediate zone         IR is in between 1E-5 and    Public roads, railway, quays are accepted
                                    1E-6 per year                and also industries and offices.
                                                                 No permanent housing is permitted,
                                                                 though some scattered housing may be
                                                                 permissible under certain circumstances
          Outer zone                IR is in between 1E-6 and    Housing, public facilities, shops, smaller
                                    1E-7 per year                overnight accommodations and other
                                                                 usage for the general public accepted
          Outside outer zone        IR is lower than 1E-7 per    Schools, hospitals, shopping centres,
                                    year                         hotels, large venues etc. should be
                                                                 outside the outer zone

         Figure 2.2 - Illustration of safety zones around a plant with marked iso-contours that defines
         the zones (Ref. /8/)

Report no: PRJ11090011 Rev: Final                                                                                Page 4
Date: 11 January 2019                                                                             ©Lloyd’s Register 2019
3        System description
3.1      General description
         The INOVYN Norge production plant for vinyl chloride monomer, VCM, is located at Rafnes industry
         facility in Bamble community in Norway. Figure 3.1 show an overview of the Rafnes industrial site and
         the surrounding areas of the Chlorine and VCM plants. The closest residential area, Herre, is located
         west of the chlorine plant. The closest house is approximately 400 m from the fence around the
         chlorine plant. Highway 353 marks the property boundary towards west. The road is at a higher
         elevation than the plant and there is also a ridge between the plant and the road. There is also a smaller
         road that goes alongside the plant fence before it connects to the highway again. This road is public,
         but can be blocked in case of an emergency.

         Figure 3.1 – Overview of the Chlorine/VCM plant and the surrounding areas
         Located southeast on the Rafnes industrial site and neighbouring the VCM plant is Noretyl AS ethylene
         plant. A polyethylene plant owned by INOVYN Bamble AS lies further to the southeast, at the
         Rønningen industrial site (not shown in Figure 3.1).
         This report presents the risk introduced from the North Star project associated with the Chlorine and
         VCM plant.

3.2      Process description
3.2.1 Chlorine – INOVYN scope
         There are two almost identical production lines (Chlorine 1 and 2) with membrane electrolysers for
         production of chlorine. Chlorine is produced on the anode side and hydrogen and caustic soda on
         cathode side. The moist chlorine gas is cooled, filtered and dried with sulphuric acid before being
         compressed to approx. 5.5 bar(g) and sent to the VCM plant. The chlorine gas from both line 1 and 2 is
         delivered in a single 250 mm header.

Report no: PRJ11090011 Rev: Final                                                                              Page 5
Date: 11 January 2019                                                                           ©Lloyd’s Register 2019
The hydrogen gas is cooled, filtered, dried and compressed and sent to the VCM plant and to the
         neighbouring industry Noretyl to be used as raw material or fuel gas.
         The caustic soda is concentrated to 50 % using evaporation and then stored. The caustic soda is
         exported by trucks and shipped by boats to several customers.
         The chlorine plant is divided into the following areas:
         •    Water purification
         •    Brine
         •    Cell room
         •    Caustic soda
         •    Hydrogen
         •    Lean brine dechlorination
         •    Emergency scrubber/recovery chlorine
         •    Chlorine.

3.2.2 VCM – Wood scope
         VCM is produced from the intermediate substance Ethylene DiChloride (EDC). EDC is produced in two
         separate processes in the VCM plant. The first process is by direct chlorination, using ethylene gas from
         Noretyl and chlorine gas from the chlorine plant. The second is by oxychlorination, using hydrogen
         chloride, hydrogen gas, ethylene gas and air. The EDC from the direct chlorination and oxychlorination
         is purified (distilled to remove light and heavy bi products) and intermediately stored before being sent
         to the cracking furnaces.
         VCM is produced by cracking EDC to VCM and Hydrogen Chloride (HCl) at a temperature of approx.
         500 °C and 20 bar(g) pressure. The gas out of the cracking furnaces still holds a large amount of EDC
         and a number of steps are needed to separate VCM, HCl and EDC from the raw gas. The EDC is
         condensed by cooling and HCl stripped off by reducing the pressure. Finally a distillation process
         removes the last traces of HCl and EDC and by-products from VCM. The pure VCM is stored as liquid in
         pressurized spherical tanks before being offloaded by ship or pumped through piping under the
         Frierfjord to INOVYN Norge PVC plant at Herøya.
         Utility systems include steam and condensate system, cooling water system, waste water treatment,
         incinerators for vented gases and fuel gas system.
         The VCM plant is divided into process area, tank farm, control centre, flare and quay. Production, as
         well as sewage treatment and combustion of bi-products, takes place in the process area. The process
         area is further divided into a number of plant areas as listed below:
         •    1100 - Oxychlorination
         •    1200 - EDC-recovery
         •    1300 - EDC purification
         •    1400 - Cracking
         •    1500 - VCM-purification
         •    1600 - Direct chlorination
         •    1700 - HCl-unit
         •    1800-1900 - Waste water treatment
         •    1800 - Incinerator
         •    2700 - EDC/VCM/by-product storage
         •    3000 - Jetty 2.

Report no: PRJ11090011 Rev: Final                                                                              Page 6
Date: 11 January 2019                                                                           ©Lloyd’s Register 2019
3.3      North Star project
         The North Star project introduces several modifications to increase the capacity of the Chlorine and
         VCM plant. The modifications are designed to increase the overall production rate of the plant with
         around 10 %.

3.3.1 VCM plant modifications
         The main modifications to the VCM plant are installation of a new HTDC module and an OHCL reactor:
         •    The HTDC module is a new module at INOVYN and will operate in parallel to the existing LTDC
              module. It is expected to have a footprint of approximately 28 m x 8 m with three levels. The
              module is relatively congested with process equipment and reactors. A process flow diagram of the
              new HTDC module located in the VCM plant is shown in Figure 3.2
         •    The OHCL reactor will replace an existing reactor. The flow throughput and the volume of the
              reactor will be increased. The existing reactor will be put out of operation and work as a spare
              reactor.
         In addition, several minor modifications, or FTMs (“Forslag Til Modifikasjoner”), will be made to allow
         for the increased production capacity. Details of the scope of these modifications can be found in
         Appendix B. Figure 3-3 illustrates the locations of the North Star modifications in the VCM plant.

         Figure 3.2 – Process flow diagram (PFD) of HTDC module

Report no: PRJ11090011 Rev: Final                                                                                Page 7
Date: 11 January 2019                                                                            ©Lloyd’s Register 2019
Figure 3-3 – VCM plant – Location of FTMs. The yellow box (left) is the location of the new
         HTDC module, and the orange box (right) is the location of the OHCl reactor

3.3.2 Safety measures for the new HTDC module
         The North Star modifications include installation of gas detection systems in the new HTDC module. The
         following gas detection systems will be installed:
         •    EX detectors for explosive gas detection
         •    Chlorine gas detectors (point detectors)
         •    Sniffing detectors for detection of toxic gas releases (low concentrations).
         Further, there will be replacement of the existing flame arrestor and fire water monitor for the HTDC
         module. Fire water monitor X1032/12 shall be replaced by a new remotely controlled fire water monitor
         (X1032/16). Fire water monitor X1032/10 will be moved to ensure better coverage of the HTDC area in
         addition to the originally covered process areas.
3.3.3 Water curtain in the HTDC module
         There is a discussion in the North Star project regarding the possible implementation of a water curtain
         between the HTDC module and the vessels in area 1600. The main purpose of such a water curtain
         would be to reduce the likelihood of escalation from an accidental event in the HTDC module to the
         wash tanks in area 1600.
         In general, water curtains are used to protect personnel from high heat radiation levels during, e.g.
         escape or other special events such as an ignited flare during a blow down situation. For protection of
         vessel containing hazardous substances, it is probably more optimal to apply a deluge system. Fire water
         can then be applied over the tanks to enhance the cooling effect.
         The HTDC module is already covered be two remotely controlled fire monitors. One of which has a
         direct line of sight to the abovementioned vessels. This is likely to be sufficient. However, to further
         quantify the benefit of a deluge system, in addition to fire monitor, one could establish:
         •    The consequence of vessel ruptures.
         •    The probability, or frequency, of fires that may lead to loss of containment of hazardous substances
              in the 1600 area.

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Date: 11 January 2019                                                                              ©Lloyd’s Register 2019
If INOVYN has a criteria for an unacceptable escalation this can be applied in the decision making, when
         the consequence and likelihood of vessel rupture (escalation) has been established.
         If the consequence of a vessel rupture is low, i.e., if it does not significantly increase the severity of the
         event, a deluge system is unlikely to be in the ALARP range of measures. A similar argument can be
         made if the frequency of fires that may cause an escalation is low.
         The above discussion assumes that there is no BLEVE potential in area 1600. The matter should be
         assessed in more detail if that is not the case.
3.3.4 Chlorine plant modifications
         The modifications to the chlorine plant are:
         •    Installation of a new electrolyser
         •    Increased capacity of the chlorine compressor, hydrogen compressor and chlorine cooler.
         Details of the scope of these modifications can be found in Appendix C.

3.4      Safety measures
3.4.1 Pressure monitoring and shutdown
         The pressure is monitored in the chlorine header and many other places in the process. Detected very
         low pressures, e.g. in case of a larger leak, lead to automatic shutdown.
3.4.2 Chlorine absorption system
         In an event of leak or failure in the chlorine plant the production in the cells are stopped and the
         emergency absorption system is started. The chlorine gas is absorbed in sodium chloride, producing
         sodium hypochlorite. A low pressure is created with ejectors and the produced chlorine gas is sucked
         through the absorption system.
3.4.3 Gas detection and emergency shutdown
         Chlorine gas detectors are located both indoors in the chlorine plant and outdoors in the chlorine and
         VCM plant. There is no automatic shutdown but an operator will directly suit up in gas protection gear
         and look for the leak.
         There is also VCM gas detectors located in the process area and around pumps in the storage area. The
         detectors are very sensitive and detect at ppm level. No automatic shutdown and procedures are the
         same as for chlorine.
3.4.4 Fire proofing of storage spheres
         The VCM storage spheres are fitted with fire detection and deluge in order to minimize risk of
         escalation and possible BLEVE event in the storage area.
3.4.5 Emergency preparedness
         At Rafnes and Rønningen there is a common emergency preparedness plan and organisation. Norward
         is a company providing services within industrial emergency preparedness and they are localized in the
         fire station at Rafnes. They provide their services to the plants on Rafnes and Rønningen.

4        Selection of hazardous events
         This section selects the units or process segments that may cause hazardous events that can influence
         the risk picture around the facility.

4.1      Existing QRA
         The events included in the present study are based on evaluations made in the previous QRA update in
         2015, Ref. /1/. The general assumptions regarding each subsystem are presented in Table 4.1.

Report no: PRJ11090011 Rev: Final                                                                                   Page 9
Date: 11 January 2019                                                                                ©Lloyd’s Register 2019
Table 4.1 – General assumptions regarding scenario selection, ref. /1/
          Part of plant             Scenarios included in    General assumption
                                    the QRA
          Chlorine plant
          Water purification        No scenarios             No (or limited) hazardous substances
          Brine                     No scenarios             No (or limited) hazardous substances
          Cell room                 Cl2 header in the cell   Leaks from individual cells and anolyte/
                                    room is considered       catolyte solutions are not considered to pose
                                                             a threat outside the cell room
                                                             Leak of H2 is assumed to give fire in the cell
                                                             room with only local effects. Domino effects
                                                             towards Cl2 system is considered negligible
          Caustic soda              No scenarios             Leaks of NaOH solution is assumed to give
                                                             only local effects
          Hydrogen                  H2 header to VCM is      Leaks of H2 from compressors etc. are
                                    considered               assumed to give only local effects.
                                                             Domino effects towards Cl2 system is
                                                             considered negligible
          Lean brine                No scenarios             Small amounts of Cl2, low pressures vacuum-
          dechlorination                                     0.2 bar(g) and leaks are assumed to give only
                                                             local effects.
                                                             Leaks of anolyte solution is assumed to give
                                                             only local effects
          Emergency                 If pumps P3704, P3706    Pumps are connected to emergency power.
          scrubber/recovery         stops while production   Small amounts of Cl2, low pressures vacuum-
          chlorine                  trips                    0.2 bar(g) and leaks are assumed to give only
                                                             local effects
          Chlorine                  All leak points of Cl2   Leak of H2SO4 is assumed to give only local
                                    gas are considered       effects.
                                                             No liquid Cl2 at any point assumed
          VCM plant
          1100                      Leaks of C2H4 is         Leak of EDC (C2H4Cl2) is assumed to give only
          oxychlorination           considered               local effects and no scenarios for EDC (incl.
                                    Leaks of HCl is          reactor V1101/V1106 (OHCL)) are included in
                                    considered               the calculations
                                    Leaks of H2 is
                                    considered
                                    NH3-tank considered
          1200 EDC-recovery         No scenarios             Leak of EDC and by-products are assumed to
                                                             give only local effects
          1300 EDC                  No scenarios             Leak of EDC and by-products are assumed to
          purification                                       give only local effects

Report no: PRJ11090011 Rev: Final                                                                               Page 10
Date: 11 January 2019                                                                             ©Lloyd’s Register 2019
Part of plant             Scenarios included in    General assumption
                                    the QRA
          1400 cracking             Fuel gas considered      Release from crackers will be above auto
                                    No scenarios for         ignition and a jet flame with local effects is
                                    EDC/VCM/HCl              assumed for all releases.
                                    according to comments    Gaseous release from top system with HCl,
                                                             VCM and EDC assumed to only give local
                                                             effects.
                                                             EDC is the main component in bottom
                                                             system and refluxes and the same
                                                             consequences as 100 % EDC (only local
                                                             effects) are assumed
          1500 VCM-                 All liquid leaks         Leaks of EDC are assumed to only give local
          purification              considered (except for   effects.
                                    liquid in C1502 and      Gaseous releases of HCl/VCM/EDC mixtures
                                    EDC return)              are assumed to give only local effects
                                    Gaseous releases of
                                    pure HCl are
                                    considered
          1600 direct               Leaks of C2H4 is         Leaks of EDC are assumed to only give local
          chlorination              considered               effects and no scenarios for EDC (incl.
                                    Leaks of Cl2 is          reactors V1601A/B (LTDC) and V1651
                                    considered               (HTDC)) are included in the calculations

          1700 HCl-unit             Fuel gas considered      Leaks of chlorinated waste, fuel gas, HCl and
                                                             NaOH solutions are assumed to give only
                                                             local effects
          1800-1900 waste           No scenarios             No (or limited) hazardous substances
          water treatment
          1800 incinerator          Fuel gas considered      Pressure in vents etc. is assumed to be
                                                             ~ atmospheric and leaks are assumed to give
                                                             only local effects
          2700 EDC/VCM/by-          VCM storage              Leak of EDC and by-products are assumed to
          product storage           considered (liquid       give only local effects
                                    releases)
          3000 Jetty 2              Loading/unloading of     The total annual time of operation for VCM
                                    VCM considered (liquid   loading arms are 115 hour per year
                                    releases)

4.2      Scenarios for the new HTDC module
         All streams downstream the HTDC reactor consists of mainly EDC and some nitrogen. As stated in Table
         4.1, leaks of EDC in area 1600 (Direct chlorination) are assumed to only give local effects and no
         scenarios for EDC are included in the risk evaluation. Neither is Nitrogen a hazardous substance in the
         context of the QRA. Hence, only leak from the feed lines of ethylene and chlorine, upstream the HTDC
         reactor (including process tie-ins), are evaluated as additional hazardous events in the update of the risk
         analysis for the VCM plant.

Report no: PRJ11090011 Rev: Final                                                                               Page 11
Date: 11 January 2019                                                                             ©Lloyd’s Register 2019
4.3      Scenarios for the new OHCL reactor
         The existing OHCL reactor (V1101) will be replaced by a new reactor (V1106) to allow for increased
         capacity. As stated in Table 4.1, leaks of EDC in area 1100 (Oxychlorination) are assumed to only give
         local effects and no scenarios for EDC, including the OHCL reactor V1101/V1106, are included in the
         calculations. Hence, replacement of the reactor itself does not cause any additional hazardous events.
         The ethylene and chlorine streams towards the existing OHCL reactor are already included in the risk
         model, however, process tie-ins to the new reactor will create additional leak potential and are
         therefore also evaluated in the update of the risk analysis for the VCM plant.

4.4      Risk screening of other North Star modifications
         A risk screening workshop was held at Rafnes to evaluate the potential risk contribution of each FTM in
         the context of the QRA. Representatives from Wood, INOVYN and LR were present at the workshop. In
         addition, two representatives from Bilfinger participated in the site walk through of the chlorine plant.
         The workshop participants are listed in Table 4.2.
         Table 4.2 – Participant list for the risk screening workshop
          Name                             Company
          Kjetil Kristoffersen             Wood
          Roger M. Pettersen               INOVYN
          Øystein Palmgren                 INOVYN
          Stian Jensen                     LR
          Andrea Risan                     LR
          Ingebjørg Valkvæ                 LR

         Table 4.3 summarises the FTMs and their relevance to the QRA. A detailed evaluation of the FTMs and
         their risk contributions is documented in Appendix B and C.
         Table 4.3 – Summary of risk evaluation of FTMs for the Chlorine and VCM plant
          FTM           Area        Scope description                      Medium           Inclusion in
          No.                                                                               QRA?
          VCM plant
          FTM 01        1100        Replacement of line 400-RP 1069 to     EDC gas                 No
                                    DN500
          FTM 02        1100        V1105 modifications                    HCl gas                Yes
          FTM 03        1100        H1104 replacement                      HCl gas,               Yes
                                                                           condensate
                                                                           and steam
          FTM 04        1100        Increase oxygen feed to OHCL with      Condensate,             No
                                    new heat exchanger H1151               steam, N2,
                                                                           enriched air
                                                                           and LOX
          FTM 05        1100        OHCL reactor cooling loop              Boiler feed             No
                                                                           water
          FTM 06        1000, 51    New IPS line to Chlorine plant         Steam                   No
          FTM 07        1300        P1305A/B/S replacement                 EDC gas                 No

Report no: PRJ11090011 Rev: Final                                                                             Page 12
Date: 11 January 2019                                                                           ©Lloyd’s Register 2019
FTM           Area        Scope description                   Medium        Inclusion in
          No.                                                                         QRA?
          FTM 08        Several     Replacement of several control      Fuel gas,           No
                                    valves                              NaOH,
                                                                        Ethylene,
                                                                        Crude EDC
                                                                        liquid, EDC
                                                                        liquid,
                                                                        EDC/VCM/HCl
                                                                        condensate,
                                                                        VCM liquid

          FTM 09        1100        V1102 Modification of demister      Steam               No
          FTM 11        1400        Replacement of RP4015, RP4057       EDC gas,            No
                                    and RP4124                          VCM, HCl
          FTM 12        1400        New P1404S                          EDC liquid          No
          FTM 13        1400        New H1405C and new V1407 (new       EDC/VCM/HCl         No
                                    balcony on str. 6)                  condensate
                                                                        and cooling
                                                                        water

          FTM 14        1400        Replacement of H1403                EDC/VCM/HCl         No
                                                                        gas
          FTM 16        2700        Replacement of RP5081               EDC liquid          No
          FTM 17        1500        Replacement of valves on C1501      EDC/VCM             No
                                                                        liquid,
                                                                        EDC/VCM
                                                                        gas, steam,
                                                                        condensate

          FTM 18        1500        DBB on C1502                        EDC/VCM gas        Yes
                                                                        and liquid

          FTM 19        1500        New H1541 with access platform      EDC/VCM 2-         Yes
                                                                        phase

          FTM 20        1500        Replacement of H1551 and increase   EDC, EDC            No
                                    diameter on RP5056 and RP5190       liquid
          FTM 21        1500        Install by-pass of H1512            EDC liquid          No
          FTM 22        1500        Replacement of H1510                Cooling            Yes
                                                                        water, VCM
                                                                        liquid

          FTM 23        2700        Existing FTM (M50913-06)            EDC                 No
                                    Replacement of P2752
          FTM 29        2700,1300   New impeller P1507                  EDC                 No
          FTM 31                    Utility tie-ins                     Various            Yes
          FTM 32                    Process tie-ins                     Various            Yes
          FTM 33        1800        Vent gas scrubber ANH               Nitrogen            No
          FTM 34        1650        Analyser house modifications        N/A                 No
          FTM 35                    Underground piping                  H2O                 No

Report no: PRJ11090011 Rev: Final                                                                      Page 13
Date: 11 January 2019                                                                    ©Lloyd’s Register 2019
FTM           Area            Scope description                         Medium              Inclusion in
          No.                                                                                         QRA?
          FTM 36        1600            Pipe rack HTDC bridge                     N/A                         No
          FTM 37                        Fire and gas                              N/A                         Yes
          FTM 38        1600,1800       New flame arrestor for HTDC               Nitrogen,                   No
                                                                                  oxygen,
                                                                                  ethylene
          FTM 39        Fire water      New fire water monitor                    H2O                         Yes
                        system
          FTM 40        1100            Tie-in of new OHCL reactor and            HCl, C2H4,                  Yes
                                        required modifications due to             EDC, Air
                                        preservation of existing reactor
          FTM 41                        New HPN vessel for emergency              Nitrogen                    No
                                        purging
          Chlorine plant
          FTM 262       Cell room       Installation of new electrolyser          Brine, H2, Cl2,             Yes
                                                                                  NaOH
          FTM 361       Chlorine        Increased capacity on chlorine cooler     Cl2 gas                     Yes
          FTM 366       Chlorine        Increased capacity on chlorine            Cl2 gas                     Yes
                                        compressor
          FTM 421       Hydrogen        Increased capacity on hydrogen            H2                          Yes
                                        compressor

5        Frequency analysis
         Three leak scenarios (small leak, major leak and rupture) are typically defined for each segment, vessel,
         specific equipment and transport pipe. Table 5.1 below presents the method to calculate leak
         frequencies and representative equipment hole sizes for the different parts of the plant.
         Note that calculated leak frequencies are presented in Appendix A. The different areas where the
         selected hazardous events are located are presented in Figure 5.1.
         Table 5.1 – Method for calculating leak frequencies
          Part of plant            Method                                                   Reference
          Chlorine plant –         Leak frequencies and representative hole sizes           ULF (Ref. /11/)
          process                  are calculated using the LRC spreadsheet tool            Offshore QRA –
          segments                 ULF (Utregning av Lekkasje Frekvenser).                  Standardised
                                   The frequencies are based on Offshore statistics         Hydrocarbon Leak
                                                                                            Frequencies (Ref. /12/)
          Chlorine plant –         The scenarios and frequencies are calculated             HES-HB-002 (Ref. /13/)
          Vessels and              using the Hydro Handbook
          specific
          equipment
          VCM plant –              Leak frequencies and representative hole sizes           ULF (Ref. /11/)
          process                  are calculated using the LRC spreadsheet tool            Offshore QRA –
          segments                 ULF (Utregning av Lekkasje Frekvenser).                  Standardised
                                   The frequencies are based on Offshore statistics         Hydrocarbon Leak
                                                                                            Frequencies (Ref. /12/)

Report no: PRJ11090011 Rev: Final                                                                                       Page 14
Date: 11 January 2019                                                                                     ©Lloyd’s Register 2019
Part of plant         Method                                               Reference
          VCM plant -           The scenarios and frequencies are calculated         HES-HB-002 (Ref. /13/)
          Vessels and           using the Hydro Handbook.
          specific              Loading arm frequencies are adjusted for
          equipment             estimated annual time of operation
          Transport piping      The scenarios and frequencies are calculated         HES-HB-002 (Ref. /13/)
                                using the Hydro Handbook

         Figure 5.1 – Illustration of location of hazardous events in QRA

6        Consequence analysis
         Consequence modelling and risk calculations are performed using the software Safeti 8.11.

6.1      Event tree
         The event tree in Figure 6.1 illustrates the different outcomes a release of a hazardous substance may
         lead to. The outcome is a set of end events such as, e.g., fireball, jet fire or dispersion of toxic gases.
         Parameters and assumptions for the probability for each branch in the event tree are documented in
         Appendix A.
         A BLEVE is an escalated event caused by an initial jet- or pool fire. If a pressurized vessel with liquefied
         gas is exposed to heat radiation it can lead to a BLEVE event with consequence of both a large fireball
         and explosion pressure from the expanding vapour. A BLEVE event may occur in the storage area for
         VCM if the deluge system fails on demand and no other cooling is applied during a severe fire in the
         area.

Report no: PRJ11090011 Rev: Final                                                                                 Page 15
Date: 11 January 2019                                                                               ©Lloyd’s Register 2019
For INOVYN’s facility, the dimensioning events for the risk zones (cf. Figure 2.2) are dispersion of toxic
         gases (such as chlorine, ammonia and HCl) and fire exposure of VCM storage tanks leading to a BLEVE.
         This is further detailed in the subsequent section.

         Figure 6.1 – Event tree

6.2      Fatality criteria
         The TNO probit functions are used as fatality criteria. These are inherent in the Safeti software.
         The process involves several toxic chemicals, where the most severe are listed in Table 6.1. The table
         offers acute exposure guideline levels (AEGL) for life threatening health effects or death, as proposed by
         US EPA (https://www.epa.gov/aegl). It can be seen that fairly low concentrations may cause fatal
         consequences.
         Table 6.1 – AEGL for airborne chemicals used in INOVYN’s process at Rafnes
          Chemical            AEGL 3 (10 min            AEGL 3 (30 min              AEGL 3 (60 min
                              exposure limit) [ppm]     exposure limit) [ppm]       exposure limit) [ppm]
          Chlorine (Cl2)      50                        28                          20
          Hydrogen            620                       210                         100
          chloride (HCl)
          Ammonia (NH3)       2700                      1600                        1100

6.3      Consequence modelling
         Consequences for the outcomes in the event tree are calculated with Safeti. Two examples of
         consequence computations are given below. The first example addresses a toxic release event and the
         second example is a consequence computation of a BLEVE event.
         Figure 6.2 shows downwind distances to different levels of toxic lethality given a rupture of the
         piping/process equipment on the high pressure side of chlorine compressor #1 for wind conditions 2
         m/s wind and Pasquille stability class F. The chlorine gas cloud with concentration corresponding to a
         toxic lethality of 1 extends approximately 180 m downwind of the rupture location. A toxic lethality of
         0.001 may occur up to 1.2 km downwind of the rupture.

Report no: PRJ11090011 Rev: Final                                                                               Page 16
Date: 11 January 2019                                                                             ©Lloyd’s Register 2019
Figure 6.3 shows ellipses of lethality levels for a BLEVE event in the VCM storage area for wind
         conditions 2 m/s wind and Pasquille stability class F. Note that the consequence of BLEVE event is not
         sensitive to the wind speed. A lethality of 1 (100 % probability of fatality) occurs in a circle around the
         BLEVE event with a radius of approximately 400 m. The lethality is reduced to 0.01 in a circle with a
         radius of approximately 1.1 km.

         Figure 6.2 – Toxic lethality footprint for a rupture of the piping/process equipment on the high
         pressure side of chlorine compressor 1 for wind conditions 2 m/s wind and Pasquille stability
         class F

         Figure 6.3 – Lethality ellipses for a BLEVE fireball event in the VCM storage area for wind
         conditions 2 m/s wind and Pasquille stability class F

Report no: PRJ11090011 Rev: Final                                                                               Page 17
Date: 11 January 2019                                                                             ©Lloyd’s Register 2019
7        Risk picture and risk evaluation
         The results from the QRA are presented as Location Specific Individual Risk (LSIR) contours, or simply risk
         contours, which allow comparison with the risk zones stipulated by DSB in "Tema 13" (Ref. /8/) as
         shown in Section 2.3.
         The definition of LSIR is expressed as the frequency at which an individual may be expected to sustain a
         given level of harm from the realization of specific hazards. It is usually taken to be the risk of fatality,
         and normally expressed as risk per year. Individual risk is the risk experienced by a single individual in a
         given time period and reflects the severity of hazards and the amount of time the individual is exposed.
         When calculating the risk, it is assumed that an individual is present at a particular location 24 hours per
         day, and 365 days per year.
         Vulnerability of humans regarding exposure to toxic releases and from impact of heat loads are used to
         calculate the lethality from each branch in the event tree. To calculate the individual risk, all the
         resulting consequences are added for a given point and constitute the combined effect of the
         frequencies for loss of containment, atmospheric conditions, wind direction, and ignition probability.
         The resulting risk contours for the facility including the North Star contribution are shown in the
         subsections below.

7.1      Total risk picture
         The combined risk contours for the chlorine and VCM plant are shown in Figure 7.1. The black lines
         represent each contour when the North Star modifications are included. An immediate observation is
         that the North Star project does not increase the risk for third parties considerably.
         A few observations can be made when comparing the calculated risk to the RAC:
         1.   The RAC suggests that only the facility itself should be exposed to a risk of 1E-5 per year, with a
              possible exception for LNF areas. As seen in the figure, Noretyl’s premises and a part of what is
              denoted other industry lie within the contour of 1E-05 per year. One could argue that Noretyl and
              INOVYN is the same company with an integrated production. Then it would probably be acceptable
              that the 1E-5 per year contour expands into the Noretyl area. It is also noted that a public road is
              located within the risk contour of 1E-05 per year. DSB’s RAC suggests that public roads should be
              exposed to a risk below 1E-5 per year
         2.   Parts of the nearest residential area are located within the contour of 1E-06 per year. Permanent
              housing should primarily be located in the outer risk zone, but scattered houses may be acceptable
              under certain circumstances
         3.   The nearest vulnerable object, a school, is located outside the 1E-07 per year risk contour.

         The North Star modifications do not cause any changes to the risk picture with respect to the
         acceptance criteria.

Report no: PRJ11090011 Rev: Final                                                                                Page 18
Date: 11 January 2019                                                                              ©Lloyd’s Register 2019
Figure 7.1 – Combined risk contours for the VCM and chlorine plant. The black lines represent
         each contour when the North Star modifications are included. The grey areas in the figure
         mainly indicate LNF areas

7.2      Risk from the chlorine plant
         The risk contribution from events in the chlorine plant, including transport piping of chlorine and
         hydrogen to the VCM plant, is shown in Figure 7.2.
         The main contributors to the risk from the chlorine plant are leaks from piping/process equipment on
         the high-pressure side of chlorine compressor 1 and 2 (KLOR1-003 and KLOR2-003). The consequences
         of these events are larger than for leaks from low-pressure piping/equipment. These segments also have
         higher leak frequencies than e.g. the chlorine transport pipe to the VCM plant. The contributions from
         one of the segments are visualized in Figure 7.3.
         The chlorine plant modifications have been included in the risk model by assuming an overall increased
         mass flow rate of 10 %. This increase is the cause of the delta risk due to the North Star modifications.
         However, the delta risk is close to negligible.

Report no: PRJ11090011 Rev: Final                                                                              Page 19
Date: 11 January 2019                                                                           ©Lloyd’s Register 2019
Figure 7.2 – Risk contribution from the chlorine plant

         Figure 7.3 – Risk contribution from the segment after the chlorine compressor #1, Klor1-003.

Report no: PRJ11090011 Rev: Final                                                                    Page 20
Date: 11 January 2019                                                                  ©Lloyd’s Register 2019
7.3      Risk from the VCM plant
         The risk contribution from events in the VCM plant is shown in Figure 7.4. Here, as in the figures above,
         the black risk contours elucidate the increase in risk due to the North Star project. Again, the North Star
         contribution is modest. There are several events that contribute to the risk picture of the VCM plant.
         However, the main contributors to the risk are:
         •    BLEVE in the VCM storage area (the risk contribution is shown in Figure 7.5)
         •    Leaks from the HCl column V1501containing liquid HCl (the risk contribution is shown in Figure
              7.6)
         •    Leaks from piping/process equipment with Cl and HCl, e.g.:
              o     The chlorine feed to the LTDC and HTDC modules (1600-Cl-017, 1600-Cl-HTDC). The risk is
                    shown in Figure 7.7.
              o     The HCl feed to C1501 (1500-HCL-011). The risk is shown in Figure 7.8.
         By comparing the below figures, it can be seen that BLEVE events has the longest reach in terms of
         exposure of adjacent land areas. As was calculated in the consequence section above (Section 6.3) the
         analysed BLEVE can cause a fatal exposure up to 1.1 km away from the VCM vessels.
         Except for BLEVE events, toxic releases dominate the risk picture for the VCM plant. Releases of VCM,
         ethylene and EDC that ignites and leads to pool-, jet- or flash fires are less critical to the risk for third
         parties.
         As an example of events that are not dimensioning for the risk zones, the risk associated with the vessel
         containing liquid ammonia (NH3), vessel V1012, is shown in Figure 7.9.
         The main driver of the delta risk is the 10 % increase in overall mass flow rate. The additional feed lines
         of ethylene and chlorine to the new HTDC module and the additional leak points on existing segments
         do not contribute significantly to an increase in the overall risk.

         Figure 7.4 – Risk contribution from the VCM plant

Report no: PRJ11090011 Rev: Final                                                                                  Page 21
Date: 11 January 2019                                                                                ©Lloyd’s Register 2019
Figure 7.5 – Risk contribution from BLEVE events in the VCM storage area

         Figure 7.6 – Risk contribution from major releases from the HCl column V1501. Release of
         liquid HCl

Report no: PRJ11090011 Rev: Final                                                                   Page 22
Date: 11 January 2019                                                                 ©Lloyd’s Register 2019
Figure 7.7 – Risk posed by the chlorine feed to the LTDC and HTDC modules

         Figure 7.8 – Risk posed by the HCl feed line to the LTDC and HTDC modules. Release of HCl in
         liquid phase

Report no: PRJ11090011 Rev: Final                                                                   Page 23
Date: 11 January 2019                                                                 ©Lloyd’s Register 2019
Figure 7.9 – Risk contribution from the liquid ammonia vessel V1012

7.4      Individual risk at nearest resident
         To further substantiate the discussion above, individual risk due to both the VCM and chlorine plants is
         measured at two points located at the nearest residential houses as shown in Figure 7.10.

         Figure 7.10 – Locations of the nearest residential houses

Report no: PRJ11090011 Rev: Final                                                                            Page 24
Date: 11 January 2019                                                                          ©Lloyd’s Register 2019
The total individual risk at the northernmost of the two locations is 2.88E-06 per year with the North
         Star project modifications included. The total risk before including the North Star modifications was
         2.58E-06. Hence, the North Star modifications cause an increase in the total risk at this point of
         approximately 12 %. Table 7.1 present the largest contributors to the risk at this point before and after
         including the North Star modifications. The main risk drivers in this point are the chlorine piping
         segments. The modifications do not change the main risk drivers.
         Table 7.1 – Risk contribution at resident location#1 before and after the North Star
         modifications are included
          Model name                Description                                      Risk              Risk
                                                                                 contribution     contribution
                                                                                   before          after North
                                                                                  North Star           Star
          Chlorine KLOR1-003        Rupture of piping/process equipment on           36 %             35 %
          RU                        high-pressure side of chlorine compressor
                                    1
          Chlorine KLOR2-003        Rupture of piping/process equipment on           36 %             35 %
          RU                        high-pressure side of chlorine compressor
                                    2
          Chlorine KLOR1-001        Rupture of piping/process equipment on            6%               7%
          RU                        chlorine header from cell room 1
          Chlorine KLOR1-002        Rupture of piping/process equipment               6%               6%
          RU                        between chlorine dryer and compressor 1
          Chlorine KLOR2-001        Rupture of piping/process equipment on            4%               4%
          RU                        chlorine header from cell room 2
          Chlorine KLOR2-002        Rupture of piping/process equipment               3%               4%
          RU                        between chlorine dryer and compressor 2

         The total individual risk at resident location #2 is 7.09E10-7 per year with the North Star project
         modifications included. The total risk before including the North Star modifications was 6.87E-07.
         Hence, the North Star modifications cause an increase in the total risk at this point of approximately 3
         %. Table 7.2 present the largest contributors to the risk at nearest resident 2 before and after including
         the North Star modifications. The main risk driver in this point is a BLEVE event in the VCM storage area.
         When the mass flow rate in the piping/process equipment segments is increased due to the North Star
         modifications, the contribution to the total risk from the HCl column (V1501) becomes negligible
         compared to other segments.

         Table 7.2 – Risk contribution at resident location #2 before and after the North Star
         modifications are included
          Model name                Description                                      Risk              Risk
                                                                                 contribution     contribution
                                                                                   before          after North
                                                                                  North Star           Star
          BLEVE fireball VCM        BLEVE in the VCM storage area                    70 %             68 %
          Chlorine KLOR1-003        Rupture of piping/process equipment on            7%               8%
          RU                        high-pressure side of chlorine compressor
                                    1
          Chlorine KLOR2-003        Rupture of piping/process equipment on            7%               8%
          RU                        high-pressure side of chlorine compressor
                                    2

Report no: PRJ11090011 Rev: Final                                                                             Page 25
Date: 11 January 2019                                                                           ©Lloyd’s Register 2019
Model name                Description                                       Risk               Risk
                                                                                  contribution      contribution
                                                                                    before           after North
                                                                                   North Star            Star
          1500-HCl-011 RU           Rupture of HCl feed to C1501                       5%                7%
          V1501 RU                  Rupture of HCl column V1501                        4%               ~0 %
          1600-Cl-017 RU            Rupture of the chlorine feed to the LTDC           2%                4%
                                    module

8        Uncertainties
         When performing a QRA of a complex industry facility, such as the chlorine and VCM plant at Rafnes, a
         number of uncertainties need to be handled. Three categories of uncertainties are discussed to present
         the major uncertainties of this study:
         1.   Uncertainties in parameters and data used as input and modelling assessments, e.g. duration of
              process leaks.
         2.   Uncertainties in modelling tools
         3.   Uncertainties related to hazards that are not included in the QRA – this could be hazards
              deliberately excluded or hazards that are not identified.
         There is uncertainty in the use of generic leak scenarios and frequencies. The QRA cannot predict events
         that will happen in the plant. The uncertainties are controlled by using a large statistical basis for the
         generic data.
         The applied modelling tool is a semi-empirical tool, and uses simplified mathematical equations
         representing experience of natural phenomena. The modelling tool is verified against large scale tests of
         releases of chemical substances. One example of uncertainty is that topography cannot be specifically
         modelled.
         Leaks from EDC and mixtures with EDC as the main medium are excluded due to the assumption that
         release and possible ignition will only give local effects, i.e. within the plant boundary. A few test
         releases of EDC have been modelled, albeit not reported, and the gas dispersion distances have been
         found minimal. There is, however, a significant uncertainty regarding escalation and if a local fire in an
         EDC release can cause equipment failure and release of e.g. HCl or VCM.

9        Potential conservatism in the QRA
         This section addresses potential conservatism embedded in the QRA. Note, however, that there are
         factors that may not be conservative, such as the exclusion of events with EDC.

9.1      Release durations and transient effects
         In general, for process leaks the durations are fixed to either 3 min or 10 min depending on the event.
         Also, the release rate is fixed for the duration of the event. For ruptures and large leaks, this can
         potentially be conservative. It is typically such events that contribute to the risk contours defining the
         risk zones. Hence, it could be worthwhile to investigate if transient effects introduce conservatism.
         In order to do so, additional information (or assessment) is needed regarding process segmentation
         volumes, flow rates, detection time, initiation of emergency or process shutdown, isolation of segments,
         time for closing ESD/PSD valves etc.

Report no: PRJ11090011 Rev: Final                                                                               Page 26
Date: 11 January 2019                                                                             ©Lloyd’s Register 2019
9.2      Terrain effects
         Terrain effects, other than surface roughness, are not captured by the study. The terrain could
         potentially provide shielding for some adjacent areas for some of the accidental events (see Figure 9-1).
         Chlorine, for example, is a relatively heavy gas compared to air. Hence, it could be expected to follow
         the terrain in dispersion scenarios. On the other hand, chlorine is toxic at low concentrations (~50 ppm)
         and the terrain may not be that influential once the chlorine is diluted in air. Terrain effects can be
         addressed by, e.g., executing CFD simulations of a selected set of scenarios. In addition, the parameter
         value for surface roughness applied in the risk model is probably set in a conservative manner.

         Figure 9.1 – Risk contours plotted on the terrain around INOVYN’s facility to illustrate the
         topography in the area

9.3      Release modelling
         The jet direction follows the wind direction in Safeti. This implies that the probability of jet to face the
         wind is not included. A jet facing headwind is likely to result in shorter hazard distances. In addition, all
         releases are modelled as free, i.e., as non-obstructed jets. In reality, some jets will be pointed
         downwards or into process equipment or other obstacles. This will reduce the momentum of the jet,
         leading to shorter hazard distances.

9.4      Event frequencies
         One could consider adapting the event frequencies for the facility, if INOVYN has historic data over
         accidental events.

9.5      BLEVE
         A major risk driver for the VCM plant is BLEVE events with the VCM storage tanks; cf. Figure 7.5 in
         Section 7.3. The BLEVE frequency is based on the fire frequency in the relevant area and a probability of
         failure on demand of the deluge system (see Appendix A). However, fire water can also be supplied by
         fire trucks and other means, which has not been credited. Also, the durations of the initial fires may be
         too short to cause a BLEVE. Hence, the BLEVE event frequency might be conservative, and could be
         investigated further in subsequent studies.

9.6      Flash fire envelope
         The main risk drivers are not flash fires. Still, there is some conservatism in the model with respect to
         how flash fire risks are modelled. The lethality range of a flash fire is linked to the extent of the 50%LFL
         cloud size. With the new QRA guidelines (Ref. /10/), this would typically be reduced to 100%LFL.

Report no: PRJ11090011 Rev: Final                                                                                Page 27
Date: 11 January 2019                                                                              ©Lloyd’s Register 2019
10       Conclusion and recommendations
10.1 Recommendations
         It is recommended to address potential conservatism in the risk model in the next revision of the QRA.
         Section 9 above lists some aspects to investigate in that respect. Following such an update one can look
         into potential risk reducing measures. For example, avoiding a BLEVE event is obviously important, and if
         there is a potential to reduce the risk of such an event, this could be addressed in the update. Risk
         reducing measures regarding toxic releases could also be discussed.
         One new process module, the HTDC module, is installed as part of the North Star project. A measure to
         potentially reduce the probability of escalation from an accident in this module has been briefly
         discussed in this report, i.e. the cooling effect of fire water. If INOVYN is uncomfortable with this
         assessment, more detail studies can be executed to quantify the escalation potential.
         For completeness, the recommendations from the existing QRA are included. These are:
         •    It is recommended to further develop and maintain systems and procedures to ensure fast detection
              and minimisation of duration of a release in case of an accidental scenario involving chlorine gas
         •    Emergency preparedness and quick notification (alarm) to the public to move indoors and close all
              doors and windows are essential to avoid severe 3rd party injuries, in case of a large toxic release
         •    INOVYN needs to make sure that the risk from the Chlorine and VCM plant are ALARP, As Low As
              Reasonably Practicable.

10.2 Conclusions
         Overall, the North Star project does not contribute with a significant risk increase compared to the
         existing risk picture at INOVYN’s facility at Rafnes. The main risk drivers remain unchanged from the
         existing QRA. Hence, toxic releases and BLEVE events in the VCM storage area dominate the risk picture
         and are dimensioning for the risk contours that will define the risk zones around the facility.
         When comparing the calculated total risk picture for the chlorine and VCM plant at Rafnes against the
         DSB suggested RAC (Ref. /8/), the following are noted:
         •    Public roads and neighbouring industries are within the 1E-5 per year risk contour
         •    Parts of the neighbouring residential area are within the 1E-6 per year risk contour. However,
              scattered houses may be permitted within the 1E-6 per year risk curve under certain circumstances.
         The North Star modifications do not cause any changes to the risk picture with respect to the suggested
         RAC.

Report no: PRJ11090011 Rev: Final                                                                              Page 28
Date: 11 January 2019                                                                            ©Lloyd’s Register 2019
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