Experiences on radioactivity handling for mercury target system in MLF/J-PARC

Kai, Tetsuya; Kasugai, Yoshimi; Oi, Motoki; Kogawa, Hiroyuki; Haga, Katsuhiro; Kinoshita, Hidetaka; Seki, Masakazu; Harada, Masahide

Progress in Nuclear Science and Technology (Internet), 4, p.380 - 383, 2014/04

https://doi.org/10.15669/pnst.4.380

Neutrons are produced by an intense proton beam (1 MW) irradiation on a mercury target in the Material and Life science experimental Facility of J-PARC. The proton beam irradiation produces various kinds of radioactivity via the spallation reaction of mercury. Design of radioactivity treatment was carried out based on estimation by using particle transport calculation codes NMTC/JAM, MCNP/4C and an induced radioactivity calculation code DCHAIN-SP 2001. This presentation shows how the estimation being utilized in design of a mercury circulation system and an off-gas processing system as specific examples. In addition the authors report some knowledge mainly about behavior of xenon and tritium obtained in operation. This presentation includes important lessons about treatment of spallation products. Thus the lessons are expected to be fully utilized in discussions of future accelerator driven neutron sources and transmutation systems using liquid metal as target material.

Result of study on storage plan for irradiated components generated at MLF in J-PARC

Kinoshita, Hidetaka; Wakui, Takashi; Matsui, Hiroki; Maekawa, Fujio; Kasugai, Yoshimi; Haga, Katsuhiro; Teshigawara, Makoto; Meigo, Shinichiro; Seki, Masakazu; Sakamoto, Shinichi; et al.

JAEA-Technology 2011-040, 154 Pages, 2012/03

JAEA-Technology-2011-040.pdf:8.08MB

In the MLF, relatively high level irradiated components will be generated. Therefore, these components can not be kept in standard facilities. For the irradiated components at the MLF, the storage plan using the facilities in the Nuclear Science Research Institute has been studied, but the concrete plan is not decided yet. In this report, outline of the components, prehistory of the studying for storage, schedule of the component generation and status of the possible facility, which is a hot laboratory, are described. Resulting from the comparison between the generation schedule and the plan of the hot laboratory, the difference is very large. Present status of the hot laboratory and the cost estimation of the modification to use for storage of the MLF components were studied. Using the hot laboratory seems not to have advantage from the view point of cost and modification method. Therefore, the study on a new storage facility construction will be started as soon as possible.

Influence of Great East Japan Earthquake on neutron target station in J-PARC

Sakai, Kenji; Futakawa, Masatoshi; Takada, Hiroshi; Sakamoto, Shinichi; Maekawa, Fujio; Kinoshita, Hidetaka; Seki, Masakazu; Haga, Katsuhiro; Kogawa, Hiroyuki; Wakui, Takashi; et al.

Proceedings of 20th Meeting of the International Collaboration on Advanced Neutron Sources (ICANS-20) (USB Flash Drive), 6 Pages, 2012/03

This report investigates behaviors and damages of each component in a neutron target station of the MLF at the J-PARC at the time of the Great East Japan Earthquake (GEJE). At the date of the GEJE, in the MLF, strong quakes were detected at several instruments, an external power supply were lost, all of the circulation systems were shut down automatically, and a hydrogen gas was released as planned. Leakage of activation liquids and gases did not occur. While, the quakes made gaps between shield blocks and ruptured external pipe lines for air and water by subsidence. But significant damages on the components of the target station were not found though a loss of compressed air supply affected lock systems with air cylinders and pneumatic operation values. These results substantiated a validity of safety design on the target station for emergency accidents.

Editing of the environmental report; Environmental concerning activity at JAERI and JNC in the first half fiscal year of 2005

Narita, Osamu; Iwata, Noboru; Isobe, Yoshihiro; Seki, Masakazu; Kadosaka, Hidetake; Ninomiya, Kazushige; Sato, Osamu

JAEA-Technology 2006-037, 102 Pages, 2006/06

JAEA-Technology-2006-037.pdf:7.67MB

We edited and published the Environmental Report according to the law on Promotion of the Environmental Concerning Activity by means of the Publish of Environmental Concerning Data. The report included the environmental concerning activity at the Japan Atomic Energy Research Institute (JAERI) and the Japan Nuclear Fuel Cycle Development Institute (JNC) in the first half year of 2005. This report is the first one which is regulated and obligated by the law. We have made much effort for gathering the data and gained a lot of experience on editing the report. We hope this paper is useful not only for the back data of our environmental report, but also for the organization which is planning to publish the similar environmental report.

Development of high intensity deuteron ion source for fusion intense neutron source

Kinsho, Michikazu; Sugimoto, Masayoshi; Seki, Masakazu; Oguri, Hidetomo; Okumura, Yoshikazu

Review of Scientific Instruments, 71(2), p.963 - 965, 2000/02

https://doi.org/10.1063/1.1150359

no abstracts in English

ITER/TBM neutronics experiments at FNS, 1; Experiment

Ochiai, Kentaro; Sato, Satoshi; Takakura, Kosuke; Yamauchi, Michinori*; Kutsukake, Chuzo; Tanaka, Shigeru; Abe, Yuichi; Seki, Masakazu; Kawabe, Masaru*; Konno, Chikara; et al.

no journal, , 

The test blanket module (TBM), water cooled pebble bed type, which is to be installed in ITER has been designed in JAEA. The TBM is made up of water cooling system with a kind of low activation ferrite, beryllium as neutron breeder, Li enriched LiTiO or LiO pebble as tritium breeding material. To evaluate the nuclear properties, we have carried out some DT neutronics experiments with TBM mock up assemblies in the Fusion Neutronics Source (FNS) and one of the TBM nuclear properties, the tritium production rate (TPR), in the LiTiO layer has been clarified by means of a liquid scintillation counter method with LiCO pellets or LiO pebbles.

Handling of off-gas produced in the mercury target of spallation neutron source in J-PARC

Kai, Tetsuya; Seki, Masakazu; Ueno, Hideki; Kinoshita, Hidetaka; Otsu, Kiichi; Teshigawara, Makoto; Kogawa, Hiroyuki; Kasugai, Yoshimi

no journal, , 

Various radioactive nuclei are produced in the mercury circulation system of J-PARC spallation neutron source. It is required to minimize release of such volatile radioactivity as tritium (half-life of 12 years) and xenon-127 (half-life of 36 days) during works opening the mercury system to the atmosphere to replace a mercury target chamber, etc. Although a depuration process by helium-gas flushing is carried out to the mercury system, a disposal of large amount of produced gas would be an issue. Thus a test was performed to remove xenon-127 from the disposal gas. As a result the concentration of xenon-127 was successfully reduced down to one-hundredth after a 6-hour operation of a charcoal trap cooled by liquid-nitrogen. In addition desorption of xenon-127 was confirmed by heating the charcoal trap to 100 degree in Celsius. These test indicated that xenon-127 in off-gas can be well removed by using the cooled charcoal trap.

Development of Experimental Data Analysis Software (EDAS)

Wakasa, Arimitsu; Namekawa, Masakazu; Urano, Hajime; Hayashi, Nobuhiko; Ide, Shunsuke; Ozeki, Takahisa

no journal, , 

no abstracts in English

The Current state of off-gas processing system at MLF

Masuda, Shiho; Kai, Tetsuya; Harada, Masahide; Kinoshita, Hidetaka; Seki, Masakazu; Takagi, Motonori; Kasugai, Yoshimi; Haga, Katsuhiro

no journal, , 

Mercury is used as a target material for spallation neutron source at J-PARC. It is assumed that most of gaseous nuclides (tritium, noble gases and mercury vapor) among spallation products accumulate in the cover gas (helium) of the surge tank in the Mercury Circulation System (MCS). In the mercury target vessel replacement which is carried out every year, cover gas is transferred to the off-gas processing system before deinstallation of the vessel. It became clear from the previous operation that a certain amount of tritium and noble gases remain absorbed on the inner wall of the MCS. It is necessary to suppress release of these nuclides to the hot cell during vessel replacement. Therefore, the MCS was purged by helium several times to reduce the radioactivity concentration in the system. As a result, the purge was effective for the reduction of noble gas, but not for tritium. Therefore, at the time of replacement, air is drawn into the off-gas processing system via the MCS using a vacuum pump, thereby forming a air flow toward the inside (air-flow control) of the MCS at the opening to suppress the release of tritium out of the system. In this report, we will introduce the role of the off-gas processing system in mercury target vessel replacement and describe the efficacy to suppress the noble gas and tritium release, and future plan of system improvement.