Studies on total beta measurements at Fukushima Daiichi Nuclear Power Station of Tokyo Electric Power Company with egs5

Total beta measurements at Fukushima Daiichi Nuclear Power Station of Tokyo Electric Power Company (TEPCO) were studied using the egs5 Monte Carlo code. Number of β-rays from various calibration sources emitted to 2π direction, β-ray counts rates by the low background gas-flow counter (LBC) were calculated for calibration sources and imitation sources. Detector efficiencies obtained using these calculated values were compared with measured ones by TEPCO. Total beta values for imitation sources were compared between measurement and calculation to study dependence for radionuclide to get detector response, for imitation source radionuclides and the thickness of LBC wall. Self absorption effects inside source were also studied using measured count rates from KCl. (author)