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The aim of this study is to obtain by Monte Carlo method the high energy photon flux due to neutron capture in the internals and vessel layers of the experimental reactor LR-0 located in REZ, Czech Republic, and loaded with VVER-1000 fuel. The calclated neutron, photon and photon to neutron flux ratio are compared with experimental measurements performed with a multi-parameter stilbene detector. The results show clear underestimation of photon flux in downcomer and some overestimation at vessel surface and 1/4 thickness but a good fitting for deeper points in vessel.

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Plant life management needs a reliable estimation of radiation field parameters, including their uncertainty, to avoid the use of conservative approaches. The particular objectives of the REDOS project [1] are the improvements of the RPV monitoring, the improvement of the neutron-gamma calculation methodologies through the LR-0 engineering benchmarks for WWER-1000 and WWER-440, and the accurate determination of radiation field parameters in the vicinity and over the thickness of the RPV. This paper is mainly devoted to the comparison and analysis of the experimental and calculated LR-0 data. The LR-0 benchmark data consist of neutron spectra (WWER-440 Mock-ups) and neutron + photon spectra (WWER-1000 Mock-up) in several points from the barrel simulator to the outer surface of RPV and evaluated integral fluxes, space-energy indices, like the spectral indices and attenuation factors in measuring points.

Abstract. In order to increase the storage capacity of the East Spent Fuel Pool at the Cofrentes NPP, located in Valencia province, Spain, the existing storage stainless steel racks were replaced by a new design of compact borated stainless steel racks allowing a 65% increase in fuel storing capacity. Calculation of the activation of the used racks was successfully performed with the use of MCNP4B code. Additionally the dose rate at contact with a row of racks in standing position and behind a wall of shielding material has been calculated using MCNP4B code as well. These results allowed a preliminary definition of the burnker required for the storage of racks. Recently the activity in the racks has been recalculated with SEACAB system which combines the mesh tally of MCNP codes with the activation code ACAB, applying the rigorous two-step method (R2S) developed at home, benchmarked with FNG irradiation experiments and usually applied in fusion calculations for ITER project.