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Journal Articles

Topics from radiation safety design of J-PARC

Nakashima, Hiroshi

JAEA-Conf 2020-001, p.69 - 74, 2020/12

J-PARC (Japan Proton Accelerator Research Complex) is a high-energy proton accelerator complex of the world's highest beam power. Because of its very high beam power and its high energy as well as the large-scale accelerator complex, we encountered some very difficult problems on radiation safety design. Various examinations and countermeasures were considered in order to overcome the difficulty. This paper introduces some of them. In addition, some new knowledge obtained during 10 years after completion are described.

Journal Articles

Estimating internal dose coefficients of short-lived radionuclides in accordance with ICRP 2007 Recommendations

Manabe, Kentaro; Sato, Kaoru; Takahashi, Fumiaki

Journal of Nuclear Science and Technology, 56(5), p.385 - 393, 2019/05

https://doi.org/10.1080/00223131.2019.1585988

Times Cited Count：3 Percentile：31.36(Nuclear Science & Technology)

At high energy accelerator facilities, various radionuclides are produced by nuclear reactions of high energy particles with structure and/or ambient air of the facilities. Consequently, the radionuclides are potential sources of internal exposure for works of the facilities. However, the International Commission on Radiological Protection (ICRP) do not provide dose coefficients, which are committed effective doses per intake, for the short-lived radionuclides whose half-lives are shorter than 10 minutes in accordance with the ICRP 2007 Recommendations. Then, we estimated the dose coefficients for inhalation and ingestion of these short-lived radionuclides in accordance with the ICRP 2007 Recommendations. In addition, we compared the dose coefficients with those in accordance with the ICRP 1990 Recommendations. As a result, a decreasing tendency was shown in the dose coefficients for inhalation cases; an increasing tendency was observed in those for ingestion cases. It was found that these changes in dose coefficients were mainly caused by the revision of the dose calculation procedures, alimentary tract models. The result of this study will be useful for planning of radiation protection at the high energy facilities.

Journal Articles

Evaluation of mean time between accidental interruptions for accelerator klystron systems based on the reliability engineering method

Takei, Hayanori; Furukawa, Kazuro*; Yano, Yoshiharu*; Ogawa, Yujiro*

Journal of Nuclear Science and Technology, 55(9), p.996 - 1008, 2018/09

https://doi.org/10.1080/00223131.2018.1467285

Times Cited Count：2 Percentile：20.74(Nuclear Science & Technology)

Experiences with existing high-power proton accelerators indicate that frequent beam trips are inevitable. One of the reasons for such frequent beam trips is the accidental interruption to protect accelerators against fatal failures. Generally, the failure frequency for the general machinery can be evaluated based on a reliability database for its components. On the other hand, the beam-trip frequency for the accidental interruption was not evaluated based on the reliability database because it has not yet been established. A principal reason for the lack of this reliability database is the inconsistency of data collection and analysis methods among laboratories. For example, there are at least three methods to estimate Mean Time Between accidental Interruptions (MTBI) for klystron systems. In the present study, the MTBI of the klystron systems of an electron/positron injector linac at the High Energy Accelerator Research Organization (KEK) was evaluated based on the reliability engineering method, in order to build the reliability database using the unified data collection and analysis method. As the result, the mean values of the MTBI by the traditional three methods were evaluated as 30.9, 32.0, and 50.4 hours. On the other hand, that by the reliability engineering method was evaluated as 57.3 hours, i.e., more than 1.14 times of the traditional results. Although these results are obviously different from traditional results, it appears that the present estimation based on the reliability engineering method is suitable for the MTBI of accelerator components as typified by the klystron system.

Journal Articles