1Nuclear Energy Division EGPRANS Meeting, Nice, May 2 2011

EXPERT GROUP ON REACTOR PHYSICS AND

ADVANCED NUCLEAR SYSTEMS

"Sodium Fast Reactor core Feed-back and Transient

response (SFR-FT) Task Force”

Review of Mandate and Planning of SFR Benchmark

F Varaine (CEA, France)

2Nuclear Energy Division EGPRANS Meeting, Nice, May 2 2011

Introduction

•This SFR benchmark was a jointly CEA and ANL proposal

•It was proposed at the beginning of 2010 in the WPRS framework

WPRS

Expert Group on Reactor Physics and Advanced

Nuclear Systems

Expert Group on Reactor Fuel Performance

Expert Group on Radiation

Transport and Shielding

Expert Group on Uncertainty Analysis in Modelling

3Nuclear Energy Division EGPRANS Meeting, Nice, May 2 2011

WPRS Mandate : reminder

Main objective : the proposed SFR-FT Expert Group would work towards a shared analysis of the feedback and transient behaviour of next generation SFR concepts.

Under the proposed mandate, this new WPRS expert group will perform a comparative analysis of the safety characteristics of different fuels types as metal, oxide, nitride and carbide cores.

To achieve these goals, two complementary items are proposed :– State of Art :

• review on core behaviour as function of fuel type and thermal power level

– Dedicated benchmarks in order to : • share the analysis, • agree on methodology• give possible recommandations to improve safety design

• Scope of studies to be performed : rules of the game– Sodium Fast Reactor– U/Pu fuel cycle– Thermal power : medium and large core size– No moderator material, no heterogeneous core.

4Nuclear Energy Division EGPRANS Meeting, Nice, May 2 2011

WPRS Mandate : task description

Proposed milestones : a step by step study

– Compile a “state of the art” report: review past and recent studies performed in the framework of sodium fast reactor and build a bibliographic repository which would stress core transient behaviours as a function of fuel characteristics (oxide, carbide, nitride and metal).

– Perform a parametric study based on two different core sizes: large size core (3600 MW thermal) and medium size core (1000-1500 MW thermal). For both cores sizes three types of fuel are proposed: oxide, carbide and metal. This comparative study is aiming at indentifying the advantages and drawbacks for each concept based on nominal performances and global safety parameters:

– Taking account of the results obtained in the previous step, transient calculations will be carried out on a few selected cases for the principal unprotected transients (UTOP, ULOF, ULOHS) and the core behaviours characterised using a matrix classification.

– Synthesis of the whole work into a final report including recommendations to improve safety and future work toward severe accidents and minor actinides management.

5Nuclear Energy Division EGPRANS Meeting, Nice, May 2 2011

Large core image : oxide and carbide fueled cores

3 600 MWThSelf-breeder cores

6Nuclear Energy Division EGPRANS Meeting, Nice, May 2 2011

Medium core image : oxide and metal fueled cores

1 000 MWThBurner cores

7Nuclear Energy Division EGPRANS Meeting, Nice, May 2 2011

Cores description

• For all cores, the benchmark document provide concentration description corresponding to equilibrium beginning of cycle configuration :

– Each initial Pu content is described by an averaged representative sub-assembly with 5 axial concentrations sets corresponding to local depleted zones

– Fission products isotopes are replaced by a representative lumped isotope (according to relevant absorption level) in order to have a generic description in terms of calculation tools.

• Geometric and medium descriptions enable both homogeneous and heterogeneous sub-assembly modelling suitable for deterministic or Monte-Carlo codes.

8Nuclear Energy Division EGPRANS Meeting, Nice, May 2 2011

Work to be performed

Characterization of end of cycle state : core depletion

• K effective

• Sodium void effect

• Doppler constant

• Effective delayed neutron fraction

• Masse balance for Heavy Nuclei

9Nuclear Energy Division EGPRANS Meeting, Nice, May 2 2011

SFR Benchmark schedule

– T0 : may 2011

• Initiate expert group activities

• Provide core data for neutronic calculation

– T0+ 6 months ; december 2011

• Presentation of neutronic evaluations

• Discussion and agreement on feedback coefficient to be calculated and associated methods, definition on corresponding evaluation grid

– T0+ 12 months : June 2012

• Presentation of Feedback Coefficient results

• Discussion and agreement on transients to be calculated and definition on corresponding evaluation grid

– T0+ 18 months : December 2012

• Presentation and discussion of transient results

• Discussion on final report

– T0+ 24 months : June 2013

• Final report and recommendation for further activities

10Nuclear Energy Division EGPRANS Meeting, Nice, May 2 2011

SFR Benchmark : who does what ?

– T0 : may 2011 (done)• Initiate expert group activities : OECD + SFR Benchmark participants• Provide core data for neutronic calculation : OECD (provided by CEA and ANL)• the official list of participants must be built by OECD (done ?)

– T0+ 6 months ; december 2011• Presentation of neutronic evaluations : SFR Benchmark participants / who

compiles data and performs comparisons ?• Discussion and agreement on feedback coefficient to be calculated and associated

methods, definition on corresponding evaluation grid SFR Benchmark participants

– T0+ 12 months : June 2012• Presentation of Feedback Coefficient results : SFR Benchmark participants /

who compiles data and performs comparisons ?• Discussion and agreement on transients to be calculated and definition on

corresponding evaluation grid

– T0+ 18 months : December 2012• Presentation and discussion of transient results SFR Benchmark participants

• Discussion on final report SFR Benchmark participants

– T0+ 24 months : June 2013

• Final report and recommendation for further activities SFR Benchmark participants