However, the exposure was well under the standards and did not cause any harm to workers, Director C P Jamb said.
The incident took place on July 19 when the maintenance work was underway.
"During the maintenance, the leakage occurred and the workers were exposed to tritium radiation. But, this was not beyond set standards. So, this was not harmful.
"The workers are working normally," the Director said.
"The dose of the tritium workers were exposed to was between 10 and 25 per cent of the annual limit. So, there is no need to panic," he said.
In a similar incident last month, 38 workers were exposed to tritium during maintenance of another unit but only two of them received radiation doses equivalent to the annual permissible limit.
"Such minor leakages happen but none of them causes worry or cast negative impact because it is well under the limits.
"We take utmost care for safety," Jamb said.
