Recent FRAPCON and FRAPTRAN activity at VTT Users group meeting V. Tulkki VTT Technical Research Centre of Finland

Recent FRAPCON & FRAPTRAN use at VTT Statistical studies OECD/NEA benchmark on uncertainty analysis of best estimate modelling of light water reactors Support to STUK EPR LBLOCA Halden LOCA experiment simulations FRAPTRAN-GENFLO bundle simulations Changing the date: View – Slide Master – change the date on the slide master uppermost

Statistical studies FRAPCON used for a statistical study on input interactions Sobol’ variance decomposition used in analysis Provides information on higher order interactions Downside: ~106 FRAPCON runs Traditional first-order ranking methods commonly used in sensitivity analysis not always sufficient due to complex interactions Discussed in OECD/NEA UAM workshops and Halden uncertainty workshop this fall ”The importance of input interactions in the uncertainty and sensitivity analysis of the nuclear fuel behavior”, T. Ikonen and V. Tulkki, submitted to Nuclear Engineering and Design Work continues with FRAPTRAN analysis

LBLOCA Comparative analysis for STUK on number of failed rods during EPR LBLOCA Regulatory requirement <10% For reference / information to STUK, not part of official process System code APROS used for 59 global simulations of plant state 59x1000 FRAPTRAN/GENFLO subchannel analysis used with local variations Results extended to whole core with neural networks -> fraction of failed rods Work in progress

Use of FRAPTRAN for benchmarking our FINIX fuel module Study on impact of variation of heating power for future Halden LOCA test Also, simulation of the effect of spacer grid simulation Should be implementable in the FEA model Extension of FRAPTRAN/GENFLO hot channel mode to bundle model with several concurrent FRAPTRAN simulations Coupling of FRAPCON to Serpent 2 MC reactor physics code via universal multiphysics interface Use of FRAPTRAN for benchmarking our FINIX fuel module FINIX initialization from FRAPCON restart FRAPTRAN to be used in IAEA CRP FUMAC and possibly OECD RIA phase II benchmark

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