Wir schaffen Wissen heute für morgen Paul Scherrer Institut Recent Highlights from the Nuclear Engineering R&D at PSI

Transcription

1 Wir schaffen Wissen heute für morgen Paul Scherrer Institut Martin A. Zimmermann Recent Highlights from the Nuclear Engineering R&D at PSI NES Strategy for PAB

2 Energy Strategy 2050 In 2011, the Federal Council and Parliament decided that Switzerland is to withdraw from the use of nuclear energy on a step-by-step basis. The existing five nuclear power plants are to be decommissioned when they reach the end of their safe service life, and will not be replaced by new ones. As a result of this decision and various other profound changes that have been observed for a number of years, in particular in the international energy arena, the Swiss energy system will require successive restructuring in the period up to In view of this, the Federal Council has developed a long-term energy policy ("Energy Strategy 2050") based on the revised energy perspectives. It has produced an initial package of measures aimed at securing the country's energy supply over the long term. Swiss Federal Office of Energy, May 29,

3 Electricity Generation in CH (2013) Hydro Rivers Nuclear Power Plants Hydro Dams

4 Nuclear Energy in Switzerland NPP Type At grid Thermal Power Net Elect. Power Capacity Beznau I PWR since [MW] 365 [MWe] 88.9 % Beznau II PWR since [MW] 365 [MWe] 88.4 % Mühleberg BWR [MW] 373 [MWe] 88.5 % Gösgen PWR since [MW] 1010 [MWe] 91.4 % Leibstadt BWR since [MW] 1220 [MWe] 85.9 % 4

5 NES Mission: Maintain Nuclear Competence Waste Management Multiscale reactive transport of radio-isotopes Safety of deep geological repository New Technologies Safety Understanding relevant phenomena Normal Operation Severe Accidents Materials performance (barrier integrity) Reduced risk - Reduced waste 5

6 EPFL/ETHZ/PSI Nuclear Master Program The nuclear engineering master program is in place since 2008 The number of enrolled students is reasonably stable over the years In 2014, more students than ever before (17) are enrolled Of these students, 4 have an EPFL/ETHZ bachelor (in 2013: 1, in 2012: 5) Applications received Students admitted Students enrolled Of the 12 students who just finished, (at least) 3 pursue a PhD at PSI, and 2 have already found a job in Switzerland (KKL, Nagra) 6

7 Best estimate plus uncertainty analysis Plant Systems Validation of TRACE Code with Uncertainty Analysis for IBLOCA Accidents (OECD/NREA ROSA) State-of-the-art analysis technique Provides much more insights than bounding (conservative) analysis 7

8 Nuclear Data in Reactor Safety Analyses 8

9 Evaluated Nuclear Reaction Data and Libraries A Complex Route From Basic Nuclear Data (ND) to Evaluated Data Libraries for Reactor Applications Continuous Evolution of Evaluated ND Libraries Continuous Assessment for Reactor Analyses Predictions of PWR Critical Boron Concentration From A. Trkov. Status and Perspective of Nuclear Data Production, Evaluation and Validation. Nuclear Engineering and Technology,

10 Recent Trend ND Libraries WITH Uncertainties Uncertainties in Reaction Cross-Sections Reactor Inherent Safety Characteristics Development of Statistical Sampling Methods to Propagate Uncertainties in Reactor Simulation Codes Uncertainties in Fission Yields Decay Heat in Pools and Casks Criticality Safety for Fuel Storage and Transport Uncertainties in Decay Constants Uncertainties in Reactivity from Evolution of Nuclide Compositions for Geological Disposal 10

11 Post Irradiation Analysis of fuel rods

12 Evolution of fuel microstructure Does Cr 2 O 3 -doped UO 2 fuel behave differently from standard UO 2 during irradiation (in terms of FGR, PCI)? Evolution of microstructure needs to be tracked Similar behaviour has been found for both types of fuel. LNM 12

13 Link to SLS Fuel from NPP to Hotlab Hotlab necessary for preparation of active micro-samples, using a Focused Ion Beam (FIB) SLS 13

14 Safety of geological repositories micro-analysis, lab and field experiments modeling 14

15 Verification of the bottom up approach Collaboration between LES and the Hungarian Academy of Science financed by «Schweizer Erweiterungsbeitrag» to the EU (1.8 MioCHF) Opalinus Clay - Sorption measurements of radionuclides on Opalinus Clay and Boda Clay (different mineralogy & porewater composition) - In house sorption models developed on clay minerals - Blind predictions with the bottom up approach which assumes clay minerals as important sinks for radionuclides Boda Clay Th sorption on Boda Clay Ni/Zn sorption on Boda Clay Zn XAS measurements on Boda Clay PRECIPITATION SORPTION Model developed for Opalinus Clay is accurate for other clay formations ( bottom up approach works) Wet chemistry and XAS explain uptake behaviour of radionuclides in argillaceous rock formations The model provide reliable scientific basis for sorption data used in the safety analysis Osán J., Kéri A., Breitner D., Fábián M., Dähn R., Simon R., and Török S. (2014) Microscale analysis of metal uptake by argillaceous rocks using positive matrix factorization of microscopic X-ray fluorescence elemental maps. Spectrochimica Acta Part B: Atomic Spectroscopy 91,

16 Molten Salt Reactor (MSR, Gen-IV) Fluid Fuel reactor (e.g. MSR) is a substantially different reactor concept compared to the ones already studied in NES Requires rethinking of approach to nuclear safety Design component Platform for education (MSc and PhD projeccts) Fast, thermal, as well as intermediate spectrum possible Good system to explore «reduced risk, reduced waste» (Thorium) Contributions from all NES labs possible (multi-disciplinarity) Kernel of expertise already available Good prospects for cooperation (far from commercial) 16

17 Hybrid spectrum core (Th-cycle): Low leakage flux trap idea 1 Flux distribution 1. Equilibrium cycle: k eff = Critical share for initial fuel: A) 233 U: 10.91% of Ac B) LWR Pu: 25.1% of Ac 2 3 not-moderated Graphite moderated ZrH moderated 2. Equilibrium cycle: k eff = Critical share for initial fuel: A) 233 U: 5.72% of Ac B) LWR Pu : 25.5% of Ac 3. Equilibrium cycle: k eff = Critical share for initial fuel: A) 233 U: 2.15% of Ac B) LWR Pu : 3.40% of Ac Main conclusions: Graphite does not provide strong reduction of the fluence on the core wall, ZrH does. ZrH is applicable for the initial, but not for the equilibrium cycle. Krepel, J. at. al., HYBRID SPECTRUM MOLTEN SALT REACTOR. Physor 2014 Kyoto 17

18 Summary NES maintains the competence in Light Water Reactor technology at an internationally competitive level, emphasizing safety relevant topics. NES clusters its R&D activities around Safety (of operating reactors) Scientific Support to Waste Management New Technologies (monitoring state-of-the-art): GIF, Molten Salt Reactor And supports Nuclear Education with embedded Post Docs PhD s Contributes to Nuclear Engineering Masters (and other educational initiatives) 18