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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.

JAEA Reports

Subcriticality measurement by Mihalczo method (II)

Hazama, Taira

PNC TN9410 97-093, 67 Pages, 1997/10

PNC-TN9410-97-093.pdf:1.63MB

Subcriticality measurement by Mihalczo method was investigated varying Cf source intensity and neutron background level. It is found that Cf source intensity must be chosen carefully when neutron background level is too high to be ignored compared to Cf source intensity. Under current measurement accuracy, the statistic error becomes double when the ratio of neutron background occupies 90% of all neutron sources in the system. On the other hand, under low neutron background level, Cf source intensity does not have any effect on the accuracy and error of measured keffs. Also investigated was the detector position dependence of meaured keffs. The detector fields of view for localy positioned detector was utilized to correct the dependence. When corrected, the measured keffs showed little dependence on detector position, which verified the validity of the correction method.

JAEA Reports