JCO criticality accident termination operation

Kanamori, Masashi

JNC TN8440 2001-018, 50 Pages, 2001/12

JNC-TN8440-2001-018.pdf:1.31MB

On September 30 at around 10:35 AM, criticality accident occurred at the JCO's conversion building in Tokai-mura. Since criticality accident had not been anticipated, neither devices for termination of criticality accident nor neutron detectors were available. Immediately after the information of the accident, our emergency staff (Japan Nuclear cycle development institute staff) went to JCO site, to measure the intensity of neutrons and gammas. There were four main tasks, first one was to measure the radiation intensity, second one was to terminate the criticality accident, third one is to alert the residents surrounding the JCO site, fourth one is to evacuate the employees in the site. These tasks were successfully performed until October 1. This paper describes about how these operations were performed by the relevant staffs.

Biosphere modeling with climate changes for safety assessment of high-level radioactive waste geological isolation

Kato, Tomoko; ; Suzuki, Yuji*; ; Ishiguro, Katsuhiko; Ikeda, Takao*; Richard, L.*

JNC TN8400 2001-003, 128 Pages, 2001/03

JNC-TN8400-2001-003.pdf:6.09MB

In the safety assessment of a high-level radioactive waste (HLW) disposal system, it is required to estimate radiological impacts on future human beings arising from potential radionuclide releases from a deep repository into the surface environment. In order to estimate the impacts, a biosphere model is developed by reasonably assuming radionuclide migration processes in the surface environment and relevant human lifestyles. Releases from the repository might not occur for many thousands of years after disposal. Over such timescales, it is anticipated that the considerable climatic change, for example, induced by the next glaciation period expected to occur in around ten thousand years from now, will have a significant influence on the near surface environment and associated human lifestyles. In case of taking these evolution effects into account in modeling, it is reasonable to develop several alternative models on biosphere evolution systems consistent with possible future conditions affected by expected climatic changes. In this study, alternative biosphere models were developed taking effects of possible climatie change into account. In the modeling, different climatic states existing in the world from the present climate condition in Japan are utilized as an analogy. Estimation of net effects of the climatic change on biosphere system was made by comparing these alternative biosphere models with a constant biosphere model consistent with the present climatic state through flux to dose conversion factors derived from each one.

Sensitivity analysis on the effectiveness of iodine prophylaxis to reduce thyroid gland exposure in nuclear emergency

Matsunaga, Takeshi; Kobayashi, Kensuke

Proceedings of 10th International Congress of the International Radiation Protection Association (IRPA-10) (CD-ROM), 10 Pages, 2000/05

no abstracts in English

The second maintenance report at plutonium conversion development facility

; ; ; ; ; ;

JNC TN8440 2000-013, 179 Pages, 2000/04

JNC-TN8440-2000-013.pdf:10.31MB

The plutonium conversion development facility (PCDF) has been operated for 17 years and about 12 tons plutonium-uranium mixed oxide (MOX) powder has been converted since operation started in 1983. The first maintenance program for aging of apparatus was carried out from 1993 to 1994. The calcination-reduction fumace, liquid waste evaporator had been dismantled and renewed. The second maintenance program was carried out form 1998 to 1999. The microwave ovens, powder blender, ventilation control panel and so on were dismantled and renewed. Large volume radioactive wastes were generated during this maintenance such as the furnace, the filter casings and glove boxes. These wastes were too large to be packed into the waste container and these wastes were polluted by MOX powder unfixed on these surface. SO cutting and packing operation for these wastes and recovery of MOX powder from them were carried out. In this report, the method of this cutting and packing operation, the radioactive exposure to the operators in this operation, the estimation of nuclear material quantity migrated to filters, the evaluation of re-floating factor of radioactive material, etc. were discussed.

Report of radiation exposure control on the 12th periodic inspection at experimental fast reactor JOYO

; Kano, Yutaka; ; Shindo, Katsutoshi

JNC TN9410 2000-001, 20 Pages, 1999/12

JNC-TN9410-2000-001.pdf:1.84MB

The 12th periodic inspection had been executed at the experimental fast reactor JOYO from February 24,1998 to June 28,1999. This inspection had been extended about three months because it was addtion to the work for the safety countermeasure. The result of collective dose equivalent was 263.92 man*mSv, whereas, the expected collective dose equivalent was about 407 man*mSv in the whole period of this inspection. It was confirmed that this inspection was carried out with the suitable radiation protection programmes. In this report, provided in 12th periodic inspection, were described with taking the results of the past periodic inspections into consideration.

None

Okubo, Hiroo*

JNC TJ1400 99-007, 35 Pages, 1999/02

JNC-TJ1400-99-007.pdf:4.55MB

no abstracts in English

None

JNC TN1400 98-002, 29 Pages, 1998/11

JNC-TN1400-98-002.pdf:2.71MB

no abstracts in English

None

Tsujimura, Norio; Shinohara, Kunihiko; Momose, Takumaro

PNC TN8510 98-001, 13 Pages, 1998/07

PNC-TN8510-98-001.pdf:0.63MB

None

None

Tsujimura, Norio; Shinohara, Kunihiko; Momose, Takumaro

PNC TN8410 98-083, 20 Pages, 1998/05

PNC-TN8410-98-083.pdf:0.62MB

None

The Development of Radiation Hardened Microcomputer System; System Design

Ishibashi, Yuzo; Kuroda, Yoshikatsu*; Nakajima, Atsushi*

PNC TJ8216 98-003, 243 Pages, 1998/03

PNC-TJ8216-98-003.pdf:6.5MB

no abstracts in English