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JAEA Reports

Development of temperature measurement technology for control rod using melt wire in High Temperature engineering Test Reactor (HTTR)

Hamamoto, Shimpei; Sawahata, Hiroaki; Suzuki, Hisashi; Ishii, Toshiaki; Yanagida, Yoshinori

JAEA-Technology 2017-012, 20 Pages, 2017/06

JAEA-Technology-2017-012.pdf:7.9MB

A melt wire was installed at the tip of the control rod in order to measure the temperature of High Temperature engineering Test Reactor (HTTR). After experience with reactor scram from the state of reactor power 100%, the melt wire was taken out from the control rod and appearance has been observed visually. In this study, an exclusive device for taking out the melt wire was prepared. The take-out device functions as expected, and the melt wire was safely and reliably taken out using a remote manipulator. And because the visual observation of the melt wire was clearly carried out, we were successful in developing the control rod temperature measurement technology. It was confirmed that the melt wires with a melting point of 505$$^{circ}$$C or less were melted, and the melt wires with a melting point of 651$$^{circ}$$C or more were not melted. Therefore, it was found that the highest arrival temperature of tip of the control rods where the melt wires are installed reaches within the range of 505 to 651$$^{circ}$$C. And it was found that the control rod temperature at the time of reactor scram does not exceed the using temperature criteria (900$$^{circ}$$C) of Alloy 800H of the control rod sleeve.

JAEA Reports

Development of transportation container for neutron startup source of High Temperature Engineering Test Reactor (HTTR)

Shimazaki, Yosuke; Sawahata, Hiroaki; Yanagida, Yoshinori; Shinohara, Masanori; Kawamoto, Taiki; Takada, Shoji

JAEA-Technology 2016-038, 36 Pages, 2017/02

JAEA-Technology-2016-038.pdf:8.75MB

The High Temperature Engineering Test Reactor (HTTR) has three neutron startup sources (NSs) in the reactor core, each of which consists of $$^{252}$$Cf with 3.7GBq The NSs are exchanged at the interval of approximately 7 years. The NS holders including NSs are transported from the dealer's hot cell to the reactor facility of HTTR using a transportation container. The loading work of NS holders to the Control Rod guide blocks is subsequently carried out in the fuel handling machine maintenance pit of HTTR. Following technical issues were extracted from the experiences in the past two exchange works of NSs to develop a safety handling procedure; (1) The reduction and prevention of radiation exposure of workers. (2) The exclusion of falling of NS holder. Then, a new transportation container special to the NSs of HTTR was developed to solve the technical issues while keeping the cost as low as that for overhaul of conventional container and satisfying the regulation of A type transportation package.

Journal Articles

Improvement of neutron startup source handling work by developing new transportation container for High-Temperature engineering Test Reactor (HTTR)

Shimazaki, Yosuke; Sawahata, Hiroaki; Shinohara, Masanori; Yanagida, Yoshinori; Kawamoto, Taiki; Takada, Shoji

Journal of Nuclear Science and Technology, 54(2), p.260 - 266, 2017/02

 Times Cited Count:0 Percentile:100(Nuclear Science & Technology)

The High-Temperature engineering Test Reactor (HTTR) has three neutron startup sources (NSs) in the reactor core, each of which consists of $$^{252}$$Cf with 3.7 GBq and is contained in a small capsule, installed in NS holder and subsequently in a control guide block (CR block). The NSs are exchanged at the interval of approximately 7 years. The NS holders are transported from the dealer's hot cell to the reactor facility of HTTR using a transportation container. The loading work of NS holders to the CR blocks is subsequently carried out in the fuel handling machine maintenance pit of HTTR. Technical issues, which are the reduction and prevention of radiation exposure of workers and the exclusion of falling of NS holder, were extracted from the experiences in past two exchange works of NSs to develop a safety handling procedure. Then, a new transportation container special to the NSs of HTTR was developed to solve the technical issues while keeping the cost as low as that for overhaul of conventional container. As the results, the NS handling work using the new transportation container was safely accomplished by developing the new transportation container which can reduce the risks of radiation exposure dose of workers and exclude the falling of NS holder.

Journal Articles

Improvement of exchanging method of neutron startup source of high temperature engineering test reactor

Sawahata, Hiroaki; Shimazaki, Yosuke; Ishitsuka, Etsuo; Yamazaki, Kazunori; Yanagida, Yoshinori; Fujiwara, Yusuke; Takada, Shoji; Shinozaki, Masayuki; Hamamoto, Shimpei; Tochio, Daisuke

Proceedings of 24th International Conference on Nuclear Engineering (ICONE-24) (DVD-ROM), 8 Pages, 2016/06

In the HTTR, $$^{252}$$Cf is loaded in the reactor core as a neutron startup source and changed at frequency. In this exchange work, there were two technical issues; slightly higher radiation exposure of workers by neutron leakage and reliability of neutron source transportation container in handling. To reduce the radiation dose by neutron leakage, detail numerical evaluations using PHITS code were carried out, the effective shielding method for fuel handling machine was proposed. Easily removable polyethylene blocks and particles were used as the neutron shielding, and installed in the cooling paths of the fuel handling machine. As a result, the collective effective dose by neutron was reduced from about 700 man-microSv to about 300 man-microSv. As to the neutron source transportation container, the handling performance was improved and the handling work was safety accomplished by downsizing.

Oral presentation

Study on release and transport of aerial radioactive materials in reprocessing plant, 7; Hot test

Yamane, Yuichi; Amano, Yuki; Yanagida, Yoshinori; Kawasaki, Yasushi; Sato, Makoto; Hayasaka, Hiromi; Tashiro, Shinsuke; Abe, Hitoshi; Uchiyama, Gunzo; Ueda, Yoshinori*; et al.

no journal, , 

The release and transport characteristics of radioactive materials at a boiling accident of the high active liquid waste (HALW) in a reprocessing plant have been studied for improving experimental data of source terms of the boiling accident. This paper describes an experiment using a small test device having an electric furnace, in which 100 mL of the HALW was heated from room temperature to 300$$^{circ}$$C and the amount of materials released during heating was measured. The amount of materials as a function of its initial concentration in the HALW is reported.

Oral presentation

Development of new transportation container for neutron startup source of High Temperature Engineering Test Reactor

Shimazaki, Yosuke; Sawahata, Hiroaki; Yanagida, Yoshinori; Shinohara, Masanori; Kawamoto, Taiki; Takada, Shoji

no journal, , 

In High Temperature Engineering Test Reactor (HTTR), three neutron holders containing $$^{252}$$Cf with 3.7GBq for each are loaded in the graphite blocks and inserted into the reactor core as a neutron startup source (NS) which is changed at the interval of approximately 7 years. These neutron holders containing the neutron sources are transported from the dealer's hot cell to HTTR using the transportation container. The holders loading to the graphite block are carried out in the fuel handling machine maintenance pit of HTTR. Technical issues were recognized for the transportation container in the past two exchange works for the safety handling work of NS holder. On the other hand, it was required that an overhaul of the conventional transportation container or development of a new transportation container because the conventional transportation container was manufactured about twenty years ago. Therefore, the development of a new transportation container for NSs, which can solve these technical issues with low cost, was carried out.

Oral presentation

Improvement of neutron startup source (NS) handling work by developing a new transportation container for the NS of High Temperature Engineering Test Reactor (HTTR)

Shimazaki, Yosuke; Sawahata, Hiroaki; Yanagida, Yoshinori; Shinohara, Masanori; Kawamoto, Taiki; Takada, Shoji

no journal, , 

In High Temperature Engineering Test Reactor (HTTR), three neutron holders containing $$^{252}$$Cf with 3.7 GBq for each are loaded in the graphite blocks and inserted into the reactor core as a neutron startup source (NS) which is changed at the interval of approximately 7 years. These neutron holders containing the neutron sources are transported from the dealer's hot cell to HTTR using the transportation container. The holders loading to the graphite block are carried out in the fuel handling machine maintenance pit of HTTR. Technical issues were recognized for the transportation container in the past two exchange works for the safety handling work of NS holder. On the other hand, it was required that an overhaul of the conventional transportation container or development of a new transportation container because the conventional transportation container was manufactured about twenty years ago. Therefore, the development of a new transportation container for NSs, which can solve these technical issues with low cost, was carried out. Radiation exposure dose of workers was reduced. As the result, it was confirmed that the NS handling work was improved by new transportation container.

Oral presentation

Temperature measurement inside reactor vessel using melt wire in High Temperature Gas-cooled Reactor

Hamamoto, Shimpei; Sawahata, Hiroaki; Suzuki, Hisashi; Ishii, Toshiaki; Yanagida, Yoshinori

no journal, , 

no abstracts in English

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