HTGR Knowledge Base

Conference Article: Fission product plate-out measurement of Oarai helium gas loop OGL-1

Tsuyuzaki, N.; Sasajima, H.; Endo, Y.; Itami, H. (Department of JMTR Project, Japan Atomic Energy Research Institute, Oarai Research Establishment (Japan)); Matsumoto, M. (Nuclear Engineering Co., Omika-cho, Hitachi-shi (Japan))

Abstract

Fission Products (FP), released from the UO₂ fuel kernels, circulate in the primary circuits of the VHTR reactor and deposit on the surface of circulation components during operation. An in-pile helium gas loop OGL-1 which simulates the VHTR coolant condition is installed in the JMTR reactor. The distribution of the FP plate-out had been measured by a non-destructive method using germanium detectors. The reactor coolant removes the FP from the reactor core and deposits ¹³⁷Cs at temperature area of 400 deg. C and ¹³¹I at 300 deg. C. In the case when the OGL-1 fuel was replaced to a new specimen which has lower FP release ratio, it was found that the deposited nuclide of ¹³⁷Cs constantly removes from the inner surface of high-temperature pipes of 600 deg. C and redeposits to the temperature area of 400 deg. C. Furthermore, this non-destructive method is possible to measure the short half-life noble gas nuclides which a conventional gas sampling method fails to measure. The experiment of dust filter installed in the OGL-1 primary circuit has been continued to study plate-out mechanism. Results have been used for verification of the plate-out analysis code and the design of the experimental VHTR components.

view the full text of this article (8 pages, format: PDF, size= 296kB)

key words: Gas Cooled Reactor, Nuclear Technology

Reference:: Specialists' meeting on fission product release and transport in gas-cooled reactors Berkeley (United Kingdom) 22-25 Oct 1985; International Atomic Energy Agency, International Working Group on Gas-Cooled Reactors, Vienna (Austria); IWGGCR--13, pp:363-370