CALCULATING THE SPECIFIC ACTIVITIES OF VVER-440 DOSIMETERS WITH MAVRIC AND KENO
26th Symposium of AER on VVER Reactor Physics and Reactor Safety (2016, Helsinki, Finland)
Reactor physics experiments and code validation continues
Abstract
CALCULATING THE SPECIFIC ACTIVITIES OF VVER-440 DOSIMETERS WITH MAVRIC AND KENOAntti RätyVTT Technical Research Centre of Finland antti.raty@vtt.fiABSTRACTThe structural integrity of reactor pressure vessels (RVP) can be studied by irradiating specimens of RVP material at the reactor periphery and measuring the properties of these samples.The aim of this work is to calculate the neutron fluxes and corresponding reaction rates for certain dosimeter samples at Loviisa power plant. Dosimeter samples are irradiated inside Loviisa RVP at downcomer side relatively close to the core. The calculation model was built with Oak Ridge National Laboratories’ MAVRIC and KENO codes. All the bundles all pressure vessel internals were included in the model. Reactor upper and lower parts were omitted. MAVRIC is based on deterministic methods and enables an efficient variance reduction technique for fast and precise modelling with Monte Carlo code KENO.Public data on VVER-440 core and fuel was used to model the geometry and fuel bundles, but actual fuel enrichment, burnup and power density data were obtained from Fortum. Source spectrum was based on MAVRIC example spectrum for U-235 and Pu-239.Surveillance chains have been irradiated for several power cycles. Total activities for dosimeters were calculated by modelling the core for each of these cycles separately and summing up the activities taking into account decay time after each cycle. In the end, results were compared with measured values. 26th Symposium of AER on VVER Reactor Physics and Reactor Safety 15 10 – 14 October 2016, Helsinki, Finland
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