Units of radiation (radioactivity)

Takahashi, Fumiaki

Genshiryoku No Ima To Ashita, p.109 - 111, 2019/03

The Atomic Energy Society of Japan has planned to publish a document for public, entitled "Current and tomorrow of atomic energy, -Experiences from the accident at the Tokyo Electronic Power Company Fukushima Dai-ichi NPPs-". The documents give us basics and usages of radiations, in addition to nuclear power plants and the accident at TEPCO Fukushima Dai-ichi NPPs. This manuscript explains physical quantities (e.g., absorbed dose), protection quantities and operational quantities that are used for radiation measurement and protection. The unit of radioactivity is also explained, because radioactivity is measured for work places in a radiation facility for internal exposure protection. In addition, radiation dose constants that relate radiation dose to the activity are also introduced, as useful radiation units for radiation protection.

Annual report on the present state and activities of the Radiation Protection Department, Nuclear Fuel Cycle Engineering Laboratories in fiscal 2009

Radiation Protection Department

JAEA-Review 2015-003, 187 Pages, 2015/03

JAEA-Review-2015-003.pdf:18.34MB

This annual report summarizes the various activities on radiation control at the nuclear fuel cycle facilities in Nuclear Fuel Cycle Engineering Laboratories, which were undertaken by the Radiation Protection Department in fiscal 2009. In the Laboratories, the Tokai Reprocessing Plant (TRP), MOX fuel fabrication facilities, the Chemical Processing Facility (CPF), and various other radioisotopes and uranium research laboratories have been operated. The Radiation Protection Department is responsible for the radiation control in and around the facilities, including personnel monitoring, workplace monitoring, consultation on radiological work planning and evaluation, monitoring of gaseous and liquid waste effluents, environmental monitoring, radiological standards, maintenance of radiation monitoring instruments, quality management, and the related research. In fiscal 2009, the results of radiological monitoring showed the situation to be normal, and no radiological incident or accident occurred. The maximum annual effective dose to radiation workers was 9.7 mSv and the mean annual effective dose was 0.2 mSv. Individual doses were kept within the annual dose limit specified in the safety regulations. The estimated effective dose caused by gaseous and liquid effluents from the TRP to imaginary members of the public around the Laboratories was 1.810 mSv. The environmental monitoring and effluent control were performed appropriately in compliance with safety regulation and standards. As for the quality management activities, the inspection by the government, the internal audit, and the maintenance to revise the documents have been continued in accordance with the quality management system which had been introduced to safety regulation since fiscal 2004.

Operation, test, research and development of the High Temperature Engineering Test Reactor (HTTR) (FY1999-2001)

Department of HTTR Project

JAERI-Review 2003-013, 98 Pages, 2003/05

JAERI-Review-2003-013.pdf:4.98MB

The HTTR (High Temperature Engineering Test Reactor) with the thermal power of 30 MW and the reactor outlet coolant temperature of 850/950C is the first high temperature gas-cooled reactor (HTGR) in Japan, which uses coated-particle fuel, graphite for core components, and helium gas for primary coolant. The HTTR, which locates at the south-west area of 5000 m in the Oarai Research Establishment, had been constructed since 1991 before accomplishing the first criticality on November 10, 1998. Rise to power tests of the HTTR started in September, 1999 and the rated thermal power of 30 MW and the reactor outlet coolant temperature of 850C was attained in December 2001. JAERI received the certificate of pre-operation test, that is, the commissioning license for the HTTR in March 2002. This report summarizes operation, tests, maintenance, radiation control, and construction of components and facilities for the HTTR as well as R&Ds on HTGRs from FY1999 to 2001.

Radiation control of the large tokamak device (JT-60) facility

Akiyama, Isamu

Hoeikyo Nyusu, (29), p.8 - 9, 2001/10

http://www.irm.or.jp/news29.pdf

no abstracts in English

Radiation control on wastes recovery work in wastes storage pit

Ito, Yasuhisa; Noda, Kimio; ;

JNC TN8410 2001-018, 67 Pages, 2001/04

JNC-TN8410-2001-018.pdf:2.96MB

There are waste storage pits where non-radioactive wastes generated from plutonium fuel facilities were stored in JNC Tokai Works. But radioactive wastes were found in one of the pit during wastes arrangement works. Therefore we set the pit temporary controlled area and recovered wastes from it. This report describes the radiation control technique of recovery work in detail.

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.

Improvement of the technique for stack monitoring based on behavior analysis of natural radio-nuclides; The technique for reducing the value of the exhaust monitor's background

Izaki, Kenji; Noda, Kimio; ; Kashimuta, Yoshio*

JNC TN8410 2001-005, 30 Pages, 2001/01

JNC-TN8410-2001-005.pdf:0.62MB

Stack monitoring is the most important work in radiation control works. Exhaust monitors used for stack monitoring have the background (which is the counts by natural radio-nuclides) on normal condition, and the values of the background vary with the facilities. Therefore, if the value of background is high, it is difficult to estimate rapidly the radioactive concentration in the exhaust. In order to estimate rapidly the radioactive concentration in exhaust, we analyzed the behavior of natural radioactivity in the facilities and examine the technique fo reducing the value of the background. As a result of the examination, we found that it is possible to estimate rapidly if we change over the monitoring point to immediately after the HEPA filters on the exhaust duct. In this reports, the analyzed results of behavior of natural radio-nuclides in the facilities and the technique for reducing the values of the background are described. To reduce the value of the background has a major effect on not only rapidly estimating the radioactive density in the exhaust but also finding the unusual things on stack monitoring.

Demonstration study on shielding safety analysis code (VII)

Sawamura, Sadashi*

JNC TJ8400 2000-053, 41 Pages, 2000/02

JNC-TJ8400-2000-053.pdf:1.6MB

Dose evaluation for direct radiation and skyshine from nuclear fuel facilities is one of the environment evaluation items. This evaluation is carried out by using some shielding calculation codes. Because of extremely few benchmark data of skyshine, the calculation has to be performed very conservatively. Therefore, the benchmark data of skyshine and the well-investigated code for skyshine would be necessary to carry out the rational evaluation of nuclear facilities. The purpose of this study is to obtain the benchmark data of skyshine and to investigate the calculation code for skyshine. In this fiscal year, the followings are investigated; (1)To improve the detection sensitivity of pulsed neutron measurement, two neutron detectors and some electronic circuits are added to the system constructed last year. (2)To estimate the neutron dose at the distant point from the facility instead of the commercialized rem-counter, a He detector with paraffin moderator is equipped to the system. (3)Using the new detection system, the skyshine of neutrons from 45Mev LINAC facility was measured in the distance up to 300m. The results show that the time structure of pulsed neutrons almost disappears at the further points than 150m. (4)In the distance from 90m to 300m ordinal total counting method without gate pulse are applied to detect the neutrons. (5)The experimental results of space dependency up to 300m is fitted fairly well by the Gui's response function.

None

JNC TN1400 99-016, 171 Pages, 1999/08

JNC-TN1400-99-016.pdf:8.97MB

no abstracts in English

None

; ; Shimizu, Kazuhiko; Miyahara, Kaname; ; Hasegawa, Hiroshi; Iwasa, Kengo

JNC TN1400 99-008, 656 Pages, 1999/04

JNC-TN1400-99-008.pdf:34.68MB

None