Welcome to the 11th Meeting of the European MELCOR and MACCS User Group (EMUG) - 11th EMUG Meeting, 04/04/2019, FHNW Brugg - Paul Scherrer Institut
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WIR SCHAFFEN WISSEN – HEUTE FÜR MORGEN Andreas Pautz :: Division Head Nuclear Energy and Safety (NES) :: PSI Welcome to the 11th Meeting of the European MELCOR and MACCS User Group (EMUG) 11th EMUG Meeting, 04/04/2019, FHNW Brugg
Where You are Today
Page 2
Where You are Today
To PSI: ~10 km
Brugg‐Windisch
~10 min.
University of Königsfelden
Applied Sciences Monastery
Roman Amphitheater
500 m
Page 3
Context of Nuclear Power in Switzerland
National context: Nuclear Power in Switzerland
No new builds of Nuclear Power Plants in Switzerland (due to acceptance
of the «Energy Strategy 2050» on May 21, 2017)
No legal lifetime limit on operating NPP, as long as they are safe (rejection
of the «Nuclear Phase‐out Initiative» on November 27, 2016)
Swiss Electricity Mix 2017
National context: Nuclear Power in Switzerland
X
NPP Type Shut down 50 yrs 60 yrs Net Elect. Power
Beznau I PWR 2019 2029 365 [MWe]
Beznau II PWR 2021 2031 365 [MWe]
Mühleberg BWR 2019 ‐ ‐ 373 [MWe]
Gösgen PWR 2029 2039 1010 [MWe]
Leibstadt BWR 2034 2044 1220 [MWe]
National context: Nuclear Power in Switzerland No reprocessing or export of nuclear waste, but an advanced “sectoral plan” for deep geological disposal in Switzerland («Swiss Federal Nuclear Act», Art.9) Research on Nuclear Safety has to be continued, and future technologies to be monitored («Swiss Federal Nuclear Act», Art. 74a) The Potential Swiss Siting Regions for High Level Waste The Molten Salt Reactor Concept
Sectoral plan for the Deep Geological Repository ‐ Switzerland has identified three sites (out of six candidate sites) that are suitable for a deep geological disposal in opalinus clay ‐ The so‐called sectoral plan determines the roadmap of scientific investigations, and political decisions that will eventually lead to the selection of one site ‐ This process is expected to last until 2029; the disposal of HLW is not expected before 2060, for LILW before 2050.
The Paul Scherrer Institute: (Very) brief Overview
Aerial View of the Paul Scherrer Institut (PSI)
Basel Germany Aarau/Bern Zürich
material sciences nanotechnology
radio chemistry hotlab
PSI east
radio pharmacy
biology SwissFEL
solar concentrator energy research
particle physics neutron source
proton accelerator
muon source
proton therapy
PSI west
synchrotron light source
Page 10Mission of PSI
Knowledge &
Matter and Energy and Human health Development expertise
materials environment Construction
Operation
Education
Large research
facilities
Technology
transfer
Swiss and foreign users more that 2400 external
from academia and industry users/year (39 beamports)
Page 11Budget
Distribution to main research areas (first‐ and third‐party funding)
Materials Research
34 %
Particle Physics
8%
Nuclear Energy
Life Sciences and Safety
24 % 14 %
Energy and
Environment
20 %
Page 12The Nuclear Energy and Safety Division
NES provides the scientific foundation for the safe operation of nuclear
facilities in Switzerland:
Support in licensing and oversight for the Swiss Nuclear Regulator ENSI in its role
as TSO (Technical Safety Organization)
NES has the mandate of “Technology Monitoring” of Gen‐III/Gen‐IV reactor
developments (Membership GIF: Generation‐IV International Forum)
Research programs in support of Long‐Term Operation (LTO) and behavior of
(enhanced) fuels of the Swiss NPP
Center of excellence for geochemistry of deep geological waste disposal systems,
and R&D contributions to the 3rd stage of the Sectoral Plan
NES is strongly involved in the education and training of the next generation of
nuclear engineers and scientists
Activation studies of reactor components Outline of the Swiss waste disposal concept Long‐Term Intermediate Dry StorageThe Nuclear Energy and Safety Division: Hot Lab
With the Hot Laboratory, PSI maintains the capability of handling and
fostering investigations of highly radioactive materials:
The only facility in Switzerland (and one of the very few in Europe) that can
handle highly‐radioactive waste and spent reactor fuel
Important demand from Swiss NPP, in particular for Post‐Irradiation
Examination (PIE)
Highly relevant for PSI, in particular for waste treatment and target inspection
Unique analytical capabilities in combination with PSI’s Large‐Scale Facilities
Deliver of Fuel Rods to Hot Cell Hot Lab Shielded FIB Microsample Preparation Imaging at the Swiss Light Source (SLS)Organization of Energy Research at PSI
216 NES staff (210 FTE), as of January 2019
120 scientists/technicians with permanent positions,
40 PhD students, 25 Postdocs
Annual Expenditures (Budget 2019): 35.0 Mio. CHF
(27.9 Mio. Salary, 7.1 Mio. operating expenses.)
Annual Revenues (Budget 2019): 15.3 Mio. CHF
«Erstmittel» (43%), 19.7 Mio CHF 2nd and 3rd party
funding (57%)LRT Landscape Organization
Research Programs Groups
Experimental
Thermal Hydraulics
Core Behavior
System
Behavior
Severe
AccidentsSevere Accident
• Recent Severe Accident Research Topics
Pool scrubbing
Filtered containment venting systems (FCVS)
Iodine transport
Hydrodynamics
Fukushima Daiichi activities
Cladding oxidation during air ingress – effect of nitrogen
Severe accident analysis for advanced reactors
Page 17Pool Scrubbing
• Industrial scale experiments of FCVS
Third party qualification tests in industrial scale
Thermal‐hydraulic characterization of 1:1 size venturi
• Small‐scale parametric tests
Iodine (I2) and CH3I retention
Simultaneous measurement of mass transfer and
hydrodynamics
• Lab‐scale tests
Iodine mass transfer
CH3I and effect of additives
• Model development
Improved representation of the hydrodynamics
Page 18Pool Scrubbing - FCVS
• Iodine retention tests in mini‐VEFITA facility
• Effect of flow regime
• Effect of iodine concentration in the injection zone
1000
churn turbulent bubbly
500
DF (‐)
100
50
10
1.2 1.4 1.6 1.8 2.0 2.2 2.4 2.6 2.8
Residence time (s)Fukushima Daiichi activities #1
• OECD/NEA BSAF‐2 project
• PSI analysis Unit 3 with MELCOR 2.1
Page 20Fukushima Daiichi activities #2
• Unit 3 with MELCOR 2.1
• The major fraction of the core as debris or
molten Fraction [% i.i]
50% in the reactor pressure vessel Location
50% in the containment Cs‐137 I‐131
No molten core‐concrete interaction due to Released from fuel 91 80
water in the containment In the reactor pressure vessel 13 0.009
• Hydrogen generation In the water in the suppression pool 56 59
1200 kg hydrogen generated In the water in the drywell 9.5 10
500 kg in Unit 3 before the explosion In the water in the auxiliary building 11 11
• Fission product release to the environment Released to the atmosphere 0.1 0.2
96% of the noble gases
0.12% of Cs‐137
0.33% of I‐131
Page 21Fukushima Daiichi activities #4
• BSAF finished
Special session at NURETH 2019
• TCOFF
Thermo‐dynamic modelling
PSI In‐house code GEMS coupling with MELCOR
• ARC‐F
Refined sequence analysis
Focus on separate phenomena
• Pre‐ADES
Preparation for debris sampling and analysis
PSI Hotlab
Page 22Cladding oxidation
• PSI air oxidation model => add the effect of nitriding
Pre‐oxidation
Nitriding
Re‐oxidation
Page 23Advanced reactors – HTR #1
• MELCOR2.2 to simulate HTR‐PM, 250 MWth
• Pebble‐bed reactor with one‐zone cylindrical core
• Simulation of:
Pressurized Loss of Forced Cooling (PLOFC)
Depressurized Loss of Forced Cooling (DLOFC)
• Comparison with INET analysis using THERMIX (Zheng et al., ANE2009)
Page 24Advanced reactors – HTR #2
• Simulation of Pressurized/Depressurized Loss of Forced Cooling (P/DLOFC)
• Zheng: P/DLOFC in HTR‐PM using a THERMIX code:
Thermohydraulics steady state and transient code for pebble bed reactor primary circuit, including a
neutron point kinetics and graphite corrosion models
• Peak fuel temperature
Sequence MELCOR [C] INET [C]
DLOFC 1457 1492
PLOFC 1165 1134
Uncertainties in geometry
Decay heat and power distribution
differ between the two simulations
Page 25Advanced reactors – MSR #1
• Molten salt reactor (MSR)
Existing severe accident codes have only limited (or no) applicability to MSR
=> Needed: Chemical and physical properties of the salts and their decomposition products
in the relevant temperature and pressure range
• Preliminary simulations using MELCOR2.1
Heat‐up of the core, release of salts and fission products
→ behavior of released species
Simple geometry with natural convective flow
Initially, CsI and LiF added to the atmosphere as vapor
Vapor pressure and molecular weight of LiF added to MELCOR
For vapor diffusivity default values
Page 26Have a great meeting!
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