| Budget Amount *help |
¥2,400,000 (Direct Cost: ¥2,400,000)
Fiscal Year 2000: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 1999: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 1998: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 1997: ¥600,000 (Direct Cost: ¥600,000)
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| Research Abstract |
This report is divided into three major sections : 1) monitoring the tritiated water (HTO) in order to assess the annual quantity discharged, 2) monitoring the HTO concentrations in the air within the containment building in order to get insight into the distribution and variations in the controlled area for radiation workers, and 3) monitoring the HTO concentrations in the exhaust from ^<41>Ar decay tanks of both the D_2O and CNS facilities set near the reactor core in order to assess the HTO production of major sources. The results obtained are as follows,
1. Based on the monitoring for a few years of tritium concentrations in the stack exhaust air and the effluent of waste water, it was found that the annual quantity discharged is at most 1 GBq in the
atmosphere and less tlnan 0.1 GBq in the aquatic drainage system.
2. Even after the renewal of distribution pipes, valves and tank for heavy water, which were likely points of HTO leakage, higher than concentrations ranging from ranging from 130 to 200 kBq/ml were found in the exhaust air from facilities (CNS and D_2O) adjacent to the reactor core. This was a cause of ingrowth in the HTO concentration in the containment building during venting cessation.
3. There may be two reasons why the tritium concentrations from the CNS and D_2O lines could be so high : 1) the leak of liquid deuterium and/or heavy water could exist, therefore expelling a large quantity of tritium, or 2) a higher concentration of tritium exists in the facilities that was produced by a nuclear reaction. That is, the ingrowth of HTO vapor during venting cessation in the containment building may be caused by the ^<14>N(n, T) ^<12>C reaction of the irradiation of nitrogen in air. The later reason was found most probable because the higher concentration in the two exhaust air corresponded to the thermal output of the reactor.
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