KAPS-1&2 consists of two Units of Pressurized Heavy Water Reactor of 220 MWe each. (Source: NPCL) KAPS-1&2 consists of two Units of Pressurized Heavy Water Reactor of 220 MWe each. (Source: NPCL)

ONE OF the two 220 MWe units at the Kakrapara Atomic Power Station (KAPS) in Gujarat had to be shut down at 9 am on Friday after leakage of heavy water from its coolant system. The Atomic Energy Regulatory Board (AERB) has sent a team of experts for an independent assessment of the situation.

An expert from the nuclear regulator, who reached the KAPS site early on Friday, is learnt to have reported that the leakage was restricted to the Primary Heat Transport (PHT) system of Unit 1 of the station in Vyara district, and that the “safety system of the reactor had worked as intended, including the backup cooling systems”.

There has not been “any abnormal release of radioactivity outside the plant or radiation exposure”, according to the regulator’s initial assessment.

For AERB, though, the worries could be compounded by the fact that this latest incident of a leak at KAPS, which has two indigenous PHWR units commissioned in the ‘90s, follows another recent leak at the 1,000-MWe Unit-1 of the Kudankulam Nuclear Power Project (KNPP).

The KNPP, the country’s first nuclear reactor unit built with Russian assistance, is learnt to have been briefly shut down to attend to a leak noticed in the conventional system of the station recently. The date of this leak could not be ascertained. The Russian VVER-1000 reactor unit is learnt to have been restarted after “necessary rectification” and the incident, officials said, had “no radiological safety implications” and therefore did not call for any safety and security audit.

No radiation leakage or increase in radioactive level, no offside emergency declared- D Rajendra Kumar,Collector pic.twitter.com/63J1gpWaws — ANI (@ANI_news) March 11, 2016

Prior to these two incidents, the only documented instance of a leak was four years ago, when there were two instances of tritium uptake (or exposure) of workers at the Rajasthan Atomic Power Station at Rawatbhata during maintenance work. While the first instance occurred in Unit-5 on June 23, 2012, the second instance took place in Unit-4 on July 19, 2012. Both the instances were localised to small areas and there was no release of radioactivity or radiation to the environment or public domain.

The Unit-5 episode occurred due to rise in tritium levels in a localised area of the containment building, following the opening of the moderator cover gas line where the welding jobs were performed. In the second instance, a localised leak of tritiated heavy water from the moderator pump seal led to tritium uptake of workers in the area.

In case of the latest leak at KAPS, a plant emergency was declared, signifying a heightened state of alert for the personnel and management. The AERB has asked the Nuclear Power Corporation of India Ltd — the state-owned atomic plant operator — to keep the unit “under shutdown state till the incident is fully investigated and corrective actions are taken”. Unit-2 of KAPS is already under shutdown since July 2015.

The KAPS employs around 350 people. “There is nothing to worry about as the radiation level inside and outside the plant and even in the neighbouring areas are normal. The condition is being constantly monitored,” KAPS site director L K Jain told The Indian Express.

“We will investigate the cause and type of failure, and how to get it back in action. Till that time, the plant will be shut down. We are in continuous touch with our corporate office… If required, we will send a formal proposal to our corporate office,” he said.

Meanwhile. Tapi District Collector Rajendra Kumar said “the reactor’s core cooling system was working” and asked residents not to create unnecessary scare or panic.

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