NPCIL to revisit safety aspects of nuke plants

Mumbai: India`s top nuclear bodies on Sunday said they would revist all safety aspects of atomic plants in the country and analyse the nuclear crisis arising in Japan after the tsunami as it has offered new lessons to fine tune existing emergency preparedness.

"We will not jump to say that our power reactors will not suffer a similar kind of situation but we are planning to revisit all the safety aspects of our plants after doing a complete analysis of the Japanese incident and share the entire safety means with the public in a transparent way," chairman and Managing director of Nuclear Power Corporation of India S K Jain told PTI today.

This is a general practice adopted by World Association of Nuclear Operators (WANO) and NPCIL will closely work with the department of Atomic Energy and Atomic Energy Regulatory Board to revisit the safety aspects in an objective manner in the coming days, Jain said.

"Although the Fukushima incident is a rarest of sequence of combination of events, we will be doing a complete analysis of it as to what might have gone wrong and how," Chairman, Atomic Energy Commission Srikumar Banerjee said.

Japan today warned of another explosion at Fukushima plant as it battled hard to avert multiple meltdowns at two of its nuclear reactors damaged by the devastating tsunami triggered earthquake.

In the International Nuclear Event Scale, the Three Mile Island accident was at level 5, Chrnobyl was at level 7, where as the current Japanese incident is at level 4.

Jain said, out of the 20 operating Indian reactors, 18 are Pressurised Heavy Water Reactors, two are Boiling Water Reactors. The two reactors of 1000 MW of Russian VVER-1000 type under construction at Kudankulam in Tamil Nadu have Generation-3 plus designs.

Between BWR (Tarapur units 1 and 2 and the Japanese reactors at Fukushima Daiichi) and PHWR there is a big difference as the PHWR reactor has 100 to 200 tonne of cold moderator which surrounds all the coolant channels.Calendria is submerged in a cool water of canlendria vault (1000 tonnes).

There is a very big heat sink available in PHWRs and secondly, unlike the BWR, the PHWR is also cooled by naturally occurring siphon mechanism.Since the steam generator located at a higher elevation, directly injecting water from the firefighting system into the generator is also available as a supplement, he said.

Jain said, "The uniqueness of Indian system is that NPCIL has got centralized online monitoring system of all the power stations which are operating in Mumbai. We have all the emergency control centre where plants live parameters are online through satellite," he said.

"Parameters are available for various safety and reactor systems where safety experts can assemble within few minutes can do the entire parallel analysis and also in continuous contact with the stations,? he said.

"Design safety, safety analysis capacity are available as a back up of operating plants which is unique to India," Jain said adding ?it is a big strength.?

Inspite of all these, with open mind we will be revisiting the safety aspects and share them with the public, Jain stressed.

AERB Chairman, S S Bajaj said, "We do not allow any of the reactors to operate unless all the emergency plans in place. The operators (NPCIL) have to conduct an actual exercise before getting clearance for operation of the plant and also the exercises are repeated every two years".

Even in the rarest of rare scenario, there is enough time for emergency planning of evacuation. Citing the case of Japan, he said on Friday a high alert was given, on Saturday general emergency was declared and evacuation upto 3 km and the radioactive release happened after the emergency precautions were taken.

"Of course, after this incident, new lessons for all the nuclear community to improve and fine tune the existing emergency preparedness. We will review it in the light of the recent Japanese incident," Bajaj said.

Meanwhile, seismologists (earthquake specialists) here said, all Indian reactors are not on coast and the Indian coastline is more than 2000 km away from Sunda trench where mega earthquakes can occur.

"Hence, similarity analysis of reactor accidents/incidents between Japanese reactors which are few hundred kilometers away from mega subduction zones and Indian coastal reactors which are few thousand kilometers away from Sunda trench should be done objectively," they said.