Leak at Rajasthan N-plant, two exposed

Two contract workers of the Rajasthan Atomic Power Station (RAPS) at Rawatbhatta were exposed to high level of radioactivity last week, following an accidental release of tritium vapour from a pipe. However, both are safe and resumed work within days.

When contacted by Deccan Herald, RAPS officials said the workers did not wear safety masks, violating the standard operating procedures. The leak was, however, contained within the reactor building.

This is the first instance of radioactive leak in 2012 reported to the Atomic Energy Regulatory Board.

The incident occurred on June 23 when RAPS-5 unit was shut down after two years, to carry out a safety modification.

Tritium vapours were released from one of the pipes exposing the two workers to high radioactive dose, much above the annual average level. “Though there were 38 people in the reactor building, in two cases radioactivity was higher than permissible limit. All are safe. There was no abnormal release of radioactivity to the environment,” said a Nuclear Power Corporation of India spokesperson.

Tritium is a component of heavy water used in nuclear power plants as coolant and moderator. Officials explained that for contract workers at RAPS, the annual upper limit of radioactivity dose is 15 milli Sievert whereas the duo received 22 milli Sievert.
The officials clarified that tritium does not stay in the body but quickly degrades and flushes out naturally within a week.

Ironically, one of the purposes of shutting down the RAPS-5 unit was to install a new pipeline for bringing in additional water in case of an emergency. It is one of the safety upgrades carried out in nuclear power plants following the Fukushima disaster. The shutting down was also part of a biennial maintenance drill.

“While other four units at RAPS are operating at full capacity, RAPS-5 will be synchronised on June 30 night for power production,” said a RAPS official. At present, India has 19 nuclear power plants with an installed capacity of 4,780 Mwe as the 20th unit, RAPS-1, is not operational. Two units of 700 Mwe each are under construction at RAPS and are scheduled to be completed by 2016.