spent fuel characterization to - nucleus.iaea.org · kazalo spent fuel characterization to support...

Kazalo

Spent Fuel Characterization to Support NPP Krško Dry Storage

Campaign

Assist. prof. dr. Marjan Kromar

Jožef Stefan Institute

Slovenia

Technical Meeting on Spent Fuel Characterization for Management of Spent

Fuel in the Back End of the Fuel Cycle

IAEA, Vienna, November 12 - 14, 2019

../Documents and Settings/Tomaz/My Documents/Tecaji/TJE-Teorija/Ventili/pomoc

Technical Meeting on Spent Fuel Characterization for Management of Spent Fuel in the Back End of the Fuel Cycle Vienna, November 12 - 14, 2019

2/15Content

• Introduction

• NPP Krško

• Fuel characterization - work done at the JSI

• Conclusion


3/15Introduction

• Jožef Stefan Institute (JSI) performs scientific researchrelated to all fuel cycle stages. It is the largest scientificinstitution in Slovenia covering the nuclear field andoperating TRIGA Mark II research reactor. Beside basicresearch we provide technical support to our only NPP –Krško.

• NPP Krško intends to transfer some of its spent fuelcurrently stored in the spent fuel pool to the dry storagecasks. The motivation is to build a storage facility thatdoes not require any active systems.

• Contract has been signed with the Holtec International,however the project is somewhat in delay due tounexpected administration procedures needed for theconstruction permit of the dry storage building.


4/15Introduction

• For the successful campaign a well donecharacterization of the spent fuel is needed.

• Some observables can be determined by the Non-Destructive Analysis (NDA) methods. However, sincesuch measurements take considerable time, it isimpractical to measure the entire fuel inventory.

• Calculations are thus required for full characterization ofthe spent nuclear fuel inventory.

• NPP Krško does not plan to do any NDA.


5/15NPP Krško

• The Krško plant is a 2-loop Westinghouse PWR thatbegan electricity production in 1981.

• The start-up core had a rated thermal capacity of 1,876MWt, and a 626 MWe gross electric power. Currently,the thermal rating is 1,994 MWt with 727 MWe grosselectric power.

• Original lifetime till 2023, currently planned extensionuntil 2043.

• The core consists of 121 fuel assemblies.

• Each assembly has 235 fuel rods arranged in a 16×16array. The remaining 21 positions contain guide tubesand are intended for control rods, neutron source andin-core instrumentation. Currently - STD fuel withVANTAGE+ features.

• Only 3 NPPs in the world use the same fuel type.


6/15NPP Krško

• The core features 33 Reactivity Control ClusterAssemblies (RCCA) arranged in 6 banks.

A A

SA D SA

C C

SA B SA

A SB SB A

D B C B D

A SB SB A

SA B SA

C C

SA D SA

A A


7/15NPP Krško

A typical NPP Krško power distribution at BOC


8/15Fuel characterization

• JSI is involved in several international initiativesregarding spent fuel characterization:

▪ EURAD - European Joint Programme on RadioactiveWaste Management: WP8 - Spent Fuelcharacterization and evolution until disposal

▪ Blind Test Benchmark organized by the SwedishNuclear Fuel and Waste Management Company(SKB)

▪ Cooperation with EC Joint Research Centre Geel andBelgian Nuclear Research Centre (SCK.CEN)

▪ IAEA initiative ?



• NPP Krško support activities:

▪ to produce verified procedures to determine decayheat, activity, photon and neutron source term ofspent nuclear fuel including realistic uncertainties

▪ to produce application for the fast determination ofthe source terms for more than 1300 NPP Krško fuelassemblies

▪ to develop cask loading strategy based on theconstraints provided by the NPP Krško



• Tools used:▪ Serpent2 - stochastic neutron transport code

▪ SCALE - deterministic codes:▪ TRITON/NEWT▪ ORIGEN/ORIGAMI

• Data needed:▪ JSI supports NPP Krško fuel management - perform

independent nuclear design calculations to verifyresults of the fuel vendor with the in-house codesystem CORD-2

▪ Results available for all 30 cycles of plant operation

▪ Rudimentary fuel data – “as built“ materialcomposition, burnup, operating history, etc. storedalso at NPP Krško under their data managementsystem


11/15Fuel characterization - performed analyses

• Influence of the fuel operational history and materialcomposition (fuel burnup, enrichment, temperature,moderator temperature (density), soluble boronconcentration, average power, and burnable absorbers)on the source term has been analyzed:

▪ M. Kromar, B. Kurinčič, “Determination of the NPP KrškoSpent Fuel Activity,” Proceedings, 24th InternationalConference Nuclear Energy for New Europe - NENE 2015,Portorož, Slovenia, September 14-17, Ljubljana: NuclearSociety of Slovenia, 2015.

▪ M. Kromar, B. Kurinčič, "Determination of the NPP Krškospent fuel decay heat," AIP conference proceedings :Thermophysics 2017, 22nd International Meeting ofThermophysics 2017, Terchova, 12-14 September 2017,(AIP conference proceedings, 1866), American Institute ofPhysics, pp. 050005-1, 2017.

▪ M. Kromar, B. Kurinčič, "Assessment of the photon andneutron source term for the NPP Krško spent fuel",Nuclear option for CO2 free energy generation :Proceedings, 12th International Conference of the CroatianNuclear Society, Zadar, June 3-6 2018, Zagreb, CroatianNuclear Society, 2018.



• Effects of boundary conditions:

▪ A. Hernandez-Solis et al., “Boundary Condition ModelingEffect on the Spent Fuel Characterization and Final DecayHeat Prediction From a PWR Assembly,“ PHYSOR 2020:Transition to a Scalable Nuclear Future Cambridge, UnitedKingdom, March 29th - April 2nd, 2020, Proceedings (to bepublished).

• Comparison of Serpent2 and TRITON/NEWT

▪ M. Kromar, B. Kurinčič, “Determination of the NPP Krškospent fuel characteristics with the Serpent and SCALE codesystems,” Proceedings of the International ConferenceNuclear Energy for New Europe, Portorož, Slovenia,September 9 ̶ 12, 2019 (to be published).



• Fast determination of the source terms:

▪ J. Malec, M. Kromar, “Development of FuelCharacterization Tool Based on Library Interpolation,“PHYSOR 2020: Transition to a Scalable Nuclear FutureCambridge, United Kingdom, March 29th - April 2nd, 2020,Proceedings (to be published).


14/15Conclusion

• JSI performs scientific research and provides support tothe NPP Krško dry storage campaign

• R&D work on the spent fuel characterization runs on 2tracks:

▪ Sensitivity analysis to reduce uncertainties

▪ Development of tools for the fast determination ofthe source terms based on available databases ableto generate also data for the cask optimizationprocess

• Several analyses have already been performed

• Work still in progress


15/15

Thank you!

Questions?