Impact assessment for internal overflow in JRR-3

Tokunaga, Sho; Iguchi, Shintaro; Kawamura, Sho; Hirane, Nobuhiko

JAEA-Technology 2022-004, 74 Pages, 2023/02

JAEA-Technology-2022-004.pdf:2.46MB

In JRR-3, in response to the new regulatory standard for research reactors that is enforced December 2013, we submitted the application document of reactor installation license for the JRR-3 on September 2014, and acquired the permission on November 2018. Thereafter, we carried out impact assessment for internal overflow based on the design principles as described in the application document of reactor installation license for the JRR-3. There are two legal requirements for internal overflow. The first is to ensure that the necessary safety functions are not lost due to internal overflow that occur in the facility. The second is to prevent leakage of liquid containing radioactive materials outside the radiation controlled area in the event of an internal overflow. For these requirements, assuming each overflow source, it was confirmed that the necessary safety functions would not be lost and that liquid containing radioactive materials would not leak outside the controlled area. Regarding these assessments, design and construction plans were submitted in installments, and the approvals were obtained sequentially. This report shows the result that is impact assessment for internal overflow in JRR-3.

The Accident evaluation of JRR-3

Iguchi, Shintaro; Horiguchi, Hironori; Araki, Masaaki

no journal, , 

The intervention level on the practical use by which the principle measurement which are the spatial radiation dose rate and the density of the radioactive materials in the environment sample, etc. as the standard by which implementation of protective measure is judged is expressed in the possible price (OIL) is established by the atomic disaster countermeasures guideline an atomic regulatory committee set. The dose evaluation when changing the fuel damaged percentage conservatively about over the design basic accident of JRR-3 and the reactor core way way blockade accident, was put into effect and OIL1 and OIL2 were compared with the implementation standard of the protective measure by this publication. Just after flow pass of a fuel element was blocked up, radioactive materials are damaged, and are released from fuel to a cooling system, and an evaluation phenomenon and a done reactor core way way blockade accident are the accident released from exhaust equipment for emergency use to ambient surroundings via a shift to a nuclear reactor pool and a building. It didn't operate with the case when exhaust equipment for emergency use normally operated by evaluation, and the occasion which did the ground release was assumed. The dose rate by the nuclide released in the atmosphere from a nuclear reactor building and the dose rate by the nuclide floating in the nuclear reactor building were estimated about dose evaluation. The evaluation point was made a distance 329m spot from JRR-3 to the atomic scientific research place site boundary. It was confirmed that there are also no dose rates beyond the initialization value of OIL1 in the result and just after accident. It was confirmed that the dose rate falls and falls below the initialization value of OIL2 after 6 time course rapidly after an accident.