Selected examples on multiphysics researches at KFKI AEKI
20th Symposium of AER on VVER Reactor Physics and Reactor Safety (2010, Hanasaari, Espoo, Finland)
Reactor physics experiment and code validation
Abstract
Nowadays, t here is a tenden cy to u se best estimate p lus uncertainty m ethods in th e
field of nucle ar energy . This implies th e application of b est estimate code sy stems and the
determination of the corresponding uncertainties. For the latter one an OECD bench mark was
set up. Th e object ive of t he O ECD/NEA Uncert ainty Analysis in Bes t-Estimate Modeling
(UAM) L WR ben chmark is to deter mine the un certainties o f t he coupled reactor
physics/thermal hy draulics LWR cal culations at all s tages. In th is pa per th e AEKI
participation i n Phase I w ill be pres ented. Th is Ph ase is d ealing with the e valuation of the
uncertainties of the neutronic calculations starting from the pin cell spectral calculations up to
the stand-alone neutronics core simulations.
1. INTRODUCTION
The following phases and tasks are defined in the benchmark 1:
Phase I (Neutronics Phase)
? Exercise I-1: ?Cell Ph ysics? focused on t he d erivation of th e multi-group
microscopic cross-section libraries and their uncertainties
? Exercise I-2: ?Lattice Ph ysics? focused o n th e d erivation of the few group alone perfor mance (kinet ics data, space- time
macroscopic crosssection libraries and their uncertainties
? Exercise I-3: ?Core Physics? focused on the core steady state stand-alone neutronics
calculations and their uncertainties
Phase II (Core Phase)
? Exercise II-1: Fuel thermal properties relevant to transient performance
? Exer cise II-2: Neut ron kinetics stand
dependence treatment, etc.)
? Exercise II-3: Thermal-hydraulic fuel bundle performance
Phase III (System Phase)
? E xercise III-1: Coupled neutronics/thermal-hydraulics core pe rformance (coupled
steady state, coupled depletion, and coupled core transient with boundary conditions)
? Exercise III-2: Thermal-hydraulics system performance
The benchmark was started 4 y ears ago, and almost all participants are still dealing with the
exercises of Phase I (and mostly with Exercise I-1 and Exercise I-2). The main reason of that
is the complexity and the non trivia lity of t his Phase: e.g. there are a lot of ta sks relating to