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Conference Article: F.P. plate-out study using in-pile loop OGL-1

Baba, O. (Japan Atomic Energy Research Inst., Oarai, Ibaraki. Oarai Research Establishment)

Abstract

Fission product plate-out measurements are carried out using the in-pile loop OGL-1 installed in the JMTR in Japan. The primary circuit of OGL-1 is about 200 meters long including two regenerative heat exchangers, primary cooler, dust filter and gas circulator. F.P. measurement is done from the outside of the primary pipe by a pure Ge detector in lead shield with a collimator. The F.P. nuclide is identified by gamma energy and its amount calculated by count rate. 15 fixed measuring points are distributed along about 100 meters between the fuel irradiation specimen and gas circulator. The primary gas temperature during OGL-1 operation at each measuring point ranges from 700 to 300C. The F.P. plate-out measuring is done after the end of each operation of 500 hours. The sensitivity of this system is 10-4 to 10-5 muCi/cm2 for 20 hours counting time at one point. We have gathered plate-out data of I-131, Cs-137, Ag110m etc. of 6 operation cycles. These data are used for the verification of the plate-out analysis programme ''PLAIN'', which was made by JAERI based on the theory set up by Iniotakis. First fuel specimen was irradiated for 2 cycles and the second one was irradiated for 4 cycles. OGL-1 operation condition, such as gas flow rate, temperature etc., was changed in order to meet the irradiation requirement of each fuel.

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key words: computer calculations; diagrams; engineering; fission products; gamma detection; gamma spectrometers; htgr type reactors; in pile loops; jmtr reactor; monitoring; p codes; primary coolant circuits; radionuclide migration; computer codes; cooling systems; enriched uranium reactors; gas cooled reactors; graphite moderated reactors; irradiation reactors; materials testing reactors; measuring instruments; radiation detection; radioactive materials; reactor components; reactor cooling systems; reactor experimental facility; reactors; research and test reactors; research reactors; spectrometers; tank type reactors; test reactors; water cooled reactors; water moderated reactors
Reference:
Specialists meeting on coolant chemistry, plate-out and decontamination in gas-cooled reactors Juelich, Federal Republic of Germany 2-4 December 1980
International Atomic Energy Agency, Vienna (Austria)
IWGGCR--2, pp:44-49