Assessment of amount and concentration of tritium in HTTR-IS system based on tritium behavior during high-temperature continuous operation of HTTR

• Published in: Annals of nuclear energy Vol. 88; pp. 126 - 134
• Main Authors: Dipu, Arnoldus Lambertus, Ohashi, Hirofumi, Hamamoto, Shimpei, Sato, Hiroyuki, Nishihara, Tetsuo
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.02.2016
• Subjects: Assessments; Chemisorption; Helium; High temperature gas-cooled reactor; High temperature gas-cooled reactor hydrogen production system; HTTR; HTTR-IS system; Nuclear engineering; Nuclear power generation; Nuclear reactor components; Nuclear reactors; Tritium; HTTR; Tritium; High temperature gas-cooled reactor hydrogen production system; HTTR-IS system; High temperature gas-cooled reactor
• ISSN: 0306-4549; 1873-2100
• DOI: 10.1016/j.anucene.2015.10.028

[Display omitted] •Tritium concentration in secondary loop of HTTR was measured at 950°C.•Reasons for decrease in tritium concentration in primary helium gas are proposed.•Concentration and total quantity of tritium in HTTR-IS system are evaluated.•Result shows that hydrogen production plant can be classified as “non-nuclear facility”. The tritium concentration in the high temperature engineering test reactor (HTTR) was measured during high-temperature (950°C) continuous operation for 50days, which is the first measurement of tritium concentration in the secondary helium circuit during operation using the intermediate heat exchanger, to develop an assessment base for evaluating tritium behavior in the high temperature gas-cooled reactor hydrogen production system. The tritium concentration in the primary helium gas increased after startup and peaked at 1.6×10−1Bq/cm3 (STP) at 60% reactor power. Then, it decreased slightly over the course of the normal operation phase. This decrease could be attributed to the effect of tritium chemisorption on graphite. The tritium concentration in the secondary helium gas was slightly lower than that in the primary helium gas. The tritium concentration in the secondary helium gas peaked at 4.7×10−2Bq/cm3 (STP) during the power enhancement phase. Thereafter, it decreased gradually to 2.2×10−2Bq/cm3 (STP) at the end of the normal power operation phase. As assessed herein, the concentration and total quantity of tritium in the secondary helium cooling system of the HTTR-iodine sulfur (IS) system can be maintained below the regulatory limits, which implies that the hydrogen production plant can be exempt from the safety function of the nuclear facility.