Transition of radioactive materials in the "evaporation and dryness due to the loss of cooling functions" at reprocessing plant; Restraint effect of coexisting nitrite ion in simulated high level liquid waste on releasing volatile ruthenium

Yoshida, Ryoichiro; Amano, Yuki; Yoshida, Naoki; Abe, Hitoshi

no journal, , 

no abstracts in English

Influence of artificial radionuclide deposited on a monitoring post on measured value of ambient dose rate

Hiraoka, Hirokazu; Hokama, Tomonori; Munakata, Masahiro

no journal, , 

Neighboring inhabitants of nuclear facilities must evacuate according to an ambient dose rate at a nuclear accident. The evacuation is judged by the measured value by monitoring posts (MPs). However, if the measured value increase by artificial radionuclide deposited to MP, it is considered that the dose rate of the surrounding environment is overestimated. The purpose of this research is to evaluate exactly the dose rate even if the radionuclide deposit to the MP, in order to adequately evacuate inhabitants. Just a MP and horizontal ground was simulated. To calculate ambient dose rates from the roof surface of MP and ground surface, Monte Carlo calculation was done. And, it was obtained that the ratio which the dose rate from the roof account for sum of two these dose rates. According to the result, the ratio was 44%. It suggested that the radionuclide could increase the measured value. However, because simulated system was simple, it is considered that the ratio was overestimated.

Advancement of structural integrity assessment of nuclear reactor components

Yamaguchi, Yoshihito; Lu, K.; Mano, Akihiro; Takamizawa, Hisashi; Katsuyama, Jinya; Li, Y.

no journal, , 

no abstracts in English

Research outline of the criticality safety research group

Gunji, Satoshi; Watanabe, Tomoaki; Tonoike, Kotaro; Araki, Shohei

no journal, , 

The criticality safety research group had been conducted research using deterministic methods to ensure the criticality safety. However, the retrieval work of fuel debris in the Fukushima Dai-ichi Nuclear Power Station cannot be evaluated by the conventional criticality management methods, therefore it is necessary to develop a risk-informed control method. To solve these research issues, we are making a critical risk basic database that covers the possible composition and properties of fuel debris. Its validity will be confirmed by a critical experiment by modified STACY critical assembly. We are also building a database that can manage the risk of the impact of exposure to critical events. We are developing a new calculation model to evaluate fuel debris. And post irradiation examinations have been conducted to accurately measure the burnup.

Research on seismic evaluation methods using 3D FE model of reactor building

Choi, B.

no journal, , 

no abstracts in English

Consequence analysis of a postulated nuclear excursion in BWR spent fuel pool using 1/ spectrum model of randomization

Simanullang, I.; Yamane, Yuichi; Kikuchi, Takeo; Tonoike, Kotaro

no journal, ,