WIR SCHAFFEN WISSEN – HEUTE FÜR MORGEN
Welcome to the 11th Meeting of the European MELCOR and MACCS User Group (EMUG)
11
thEMUG Meeting, 04/04/2019, FHNW Brugg
Andreas Pautz :: Division Head Nuclear Energy and Safety (NES) :: PSI
Where You are Today
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Where You are Today
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~10 min.
To PSI: ~10 km
Königsfelden Monastery
Roman Amphitheater 500 m
Brugg‐Windisch University of Applied Sciences
Context of 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)
National context: Nuclear Power in Switzerland
Swiss Electricity Mix 2017
National context: Nuclear Power in Switzerland
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]
X
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)
National context: Nuclear Power in Switzerland
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)
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synchrotron light source
neutron source energy research solar concentrator
muon source
proton therapy proton accelerator
SwissFEL nanotechnology
radio chemistry radio pharmacy
biology material sciences
Basel Germany Aarau/Bern Zürich
PSI west
PSI east hotlab
particle physics
Mission of PSI
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Matter and materials
Energy and environment
Human health
Large research facilities
Swiss and foreign users from academia and industry
Development Construction
Operation
Knowledge &
expertise
Education
Technology transfer more that 2400 external
users/year (39 beamports)
Budget
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Particle Physics 8 %
Nuclear Energy and Safety
14 % Materials Research
34 %
Energy and Environment 20 %
Life Sciences 24 %
Distribution to main research areas (first‐ and third‐party funding)
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
The Nuclear Energy and Safety Division
Long‐Term Intermediate Dry Storage Outline of the Swiss waste disposal concept
Activation studies of reactor components
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)
The Nuclear Energy and Safety Division: Hot Lab
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 2ndand 3rdparty funding (57%)
Groups Groups
Experimental Thermal Hydraulics
Experimental Thermal Hydraulics
System Behavior
System Behavior
Severe Accidents
Severe Accidents Core Behavior Core Behavior
Research Programs Research Programs
LRT Landscape Organization
• 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
Severe Accident
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• 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
Pool Scrubbing
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Pool Scrubbing - FCVS
• Iodine retention tests in mini‐VEFITA facility
• Effect of flow regime
• Effect of iodine concentration in the injection zone
1.2 1.4 1.6 1.8 2.0 2.2 2.4 2.6 2.8
10 50 100 500
1000 churn turbulent
DF (‐)
Residence time (s)
bubbly
Fukushima Daiichi activities #1
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• OECD/NEA BSAF‐2 project
• PSI analysis Unit 3 with MELCOR 2.1
Fukushima Daiichi activities #2
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• Unit 3 with MELCOR 2.1
• The major fraction of the core as debris or molten
50% in the reactor pressure vessel
50% in the containment
No molten core‐concrete interaction due to water in the containment
• Hydrogen generation
1200 kg hydrogen generated
500 kg in Unit 3 before the explosion
• Fission product release to the environment
96% of the noble gases
0.12% of Cs‐137
0.33% of I‐131
Location Fraction [% i.i]
Cs‐137 I‐131
Released from fuel 91 80
In the reactor pressure vessel 13 0.009 In the water in the suppression pool 56 59 In the water in the drywell 9.5 10 In the water in the auxiliary building 11 11 Released to the atmosphere 0.1 0.2
Fukushima Daiichi activities #4
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• 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
Cladding oxidation
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• PSI air oxidation model => add the effect of nitriding
Pre‐oxidation
Nitriding
Re‐oxidation
Advanced reactors – HTR #1
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• 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)
Advanced reactors – HTR #2
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• 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
Uncertainties in geometry
Decay heat and power distribution differ between the two simulations Sequence MELCOR [C] INET [C]
DLOFC 1457 1492
PLOFC 1165 1134
Advanced reactors – MSR #1
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• 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
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