Monitoring of I-131 release 94^th and 95^th core in the G.A. Siwabessy multipurpose reactor

The I-131 release provide radiological consequence toward the people and environment, therefore the I-131 release monitoring is required to be carried continuously. The monitoring of I-131 release has been carried out during reactor operation on 94^th and 95^th core, from September 2017 up to April 2018 by sampling the air from the stack, before it is released to the environment, by; then, counting the sample and calculating the rate of the release radioactivity. The sample analysis result; taken from 94^th core, it is obtained that the average rate of I-131 release radioactivity was 1.92 x 10² Bq / hour and the maximum rate of the release radioactivity was 1.36 x 10³ Bq / hr. Meanwhile, from the sample analysis result taken from 95^th core, it is obtained that, the average rate of I-131 release radioactivity was 1,045 x 10³ Bq / hr and the maximum rate of the release radioactivity was 2.02 x 10³ Bq / hr. Based on those analysis result, it can be figured out that; during the reactor operation on the 95^th core, there was an increase; which is fairly significant, in accordance with the I-131 release. This can be caused from the impurity of the U-235 and TeO₂ irradiation target capsules. Although there was an increase of I-131 release during the 95^th core, but it is still below the safety limit value according to the Nuclear Energy National Regulatory Chairman Regulation, number 7 of 2017, on the part of environmental radioactivity limits for I-131 release, which is limited to be not greater than 8.5 x 10⁴ Bq / hr. Therefore, a more intensive attention toward the capsule handling should be carried out frequently, so as, it will not be found the hazard effect of the stack release. (author)