Rawatbhata nuclear power station reports another tritium leak

Yet another leak has been reported within a month at the Rajasthan Atomic Power Station (RAPS) at Rawatbhata near Kota, exposing workers to tritium radiation, and causing concern among the country’s nuclear energy watchers. The senior management at Rawatbhata, a site getting ready for India’s second-biggest Nuclear Fuel Complex (NFC) with a capacity of 500 tonnes a year, however, has dismissed the leak as a “routine’ matter.

Four maintenance workers were exposed to tritium radiation last Thursday (July 19), while repairing a faulty pipe in PHWR (pressurised heavy water reactor) Unit 4. The earlier incident, which took place on June 23, reportedly exposed more than 40 persons, working on a coolant at Unit 6, to tritium.

“There is no incident or accident. Everything is normal here,” said C.P. Jamb, Director-General of RAPS, talking to The Hindu on the phone on Tuesday. Dr. Jamb confirmed Thursday’s leak and said the workers were taken off duty immediately, and put under care. “There are no symptoms on the workers. The radiation was well within limits — only 10-25 per cent of the annually permissible limits,” he said.

“Such leaks are perhaps symptoms of a malady. This particular one needn’t be that serious, and could be termed a routine development, but such things are happening too often. India’s nuclear programme, as such, needs to be far more careful than what it is today,” said internationally-renowned physicist and Gandhian Surendra Gadekar, talking to this correspondent on the incident. A fortnight ago, Dr. Gadekar was at Rawatbhata to address a public hearing on NFC.

“If this leak could be termed routine, the previous one in which some 44 workers — most of whom were contract labourers — were affected, was more serious. Our fear is that such radiation exposures are happening fairly often in the plant, though the information usually isn’t revealed. The contract labourers are the worst sufferers,” Dr. Gadekar noted.

Dr. Jamb was of the view that the area — and for that matter, the country — should learn to live with these things. “We have to get used to it. We needn’t be unduly scared either. If not, we won’t be able to maintain such stations,” he noted. The media usually overreacted to such situations, he felt. “We take all the precautions while carrying out repairs on pipes and valves. At times, the workers remove their protective hoods and get exposed. Then, we take them off from that duty and put them elsewhere,” he said.

The NRC, or the U.S. Nuclear Regulatory Commission, website describes tritium as a “mildly” radioactive isotope of hydrogen. “Tritium emits a weak form of radiation, a low-energy beta particle similar to an electron. The tritium radiation doesn’t travel very far in air, and cannot penetrate the skin. Nuclear power plants routinely and safely release dilute concentrations of tritiated water,” it notes. Like normal hydrogen, tritium can bond with oxygen to form water. When this happens, the resultant water is radioactive.

“This is a heavy water-moderated reactor, with heavy water circulating in all the pipes. It happens at all the heavy water-moderated stations,” Dr. Jamb, asserted.

P. Sunderarajan reports from New Delhi:

Confirming the incident, spokesperson of the Nuclear Power Corporation of India, Nalinish Nagaich reiterated that “there is no cause for any alarm. The affected persons are continuing to carry out their assigned work as usual. Tritium is a beta emitter and once it enters the body, its removal starts, and the levels get reduced significantly within a week,” he added.

The incident occurred on July 19, when the moderator system pump in Unit 4 of the power station developed a leak while being normalised after some maintenance work.

A report on the incident published on the NPCIL website said: “During normalisation of the moderation system, a seal leak was noticed from one moderator pump. The pump was immediately stopped, isolated, and the leak was arrested.”