Indian nuclear plants are safe: NPCIL

Last Updated: Wednesday, April 13, 2011 - 22:17

New Delhi: Even while maintaining that
India`s atomic plants are capable of handling extended power
loss scenario witnessed during Japan`s nuclear crisis, NPCIL
on Wednesday announced additional safety measures at all nuclear
power plants.



The state-run Nuclear Power Corporation of India Limited
(NPCIL) came out with the additional measures after an
internal safety assessment of all nuclear reactors by four
taskforces it had appointed for the purpose in the wake of the
Fukushima nuclear accident in Japan triggered by earthquake
and tsunami.
The results of the study were thoroughly reviewed and
discussed by experts and the top management at NPCIL today.



The studies have indicated that capabilities exist in all
Indian nuclear plants to handle severe natural events, NPCIL
Chairman and Managing Director Shreyans Kumar Jain said.



He said the taskforces have come out with recommendations
with a view to enhancing the safety levels and build further
defence.



"NPCIL proposes to take up implementation of the
recommendations of its task forces immediately with requisite
approvals from Atomic Energy Regulatory Board, wherever
applicable," Jain said.



The NPCIL task forces` recommendations include
incorporation of automatic reactor shutdown initiation on
sensing seismic activity and increasing passive power source
capacity for monitoring and control purposes, for longer
durations.



They also suggested making provisions for hook up
arrangements for adding cooling water inventory through
external sources to all reactor cooling systems, and mobile
diesel driven pumping units and augmentation of water
inventory and arrangement for transfer of water from the
nearby sources, if required.



The task forces suggested incorporating additional shore
protection measures at Madras Atomic Power Station, and
Tarapur Atomic Power Station, which are located in the coastal
regions.



They also recommended additional hook up points for
making up water to spent fuel pools at Tarapur Atomic Power
Station units 1 and 2, Rajasthan Atomic Power Station units 1
and 2, and Madras Atomic Power Station units 1 and 2.



The task force for the Tarapur Atomic Power Station
(TAPS) has recommended advance alert mechanism for tsunami and
also to inert the primary containment of the two Boiling Water
Reactors with nitrogen.



"The seismic capability of the structures has been found
adequate for the seismic zone in which it is located," it
said.
It found that the plant was safe for the maximum height
of tsunami that can be generated by a quake triggered by the
Makran fault, which is located 900 km away near Karachi.



It said additional shore protection measures were also
being undertaken which will absorb considerable energy from
the tsunami waves.



"Water sources existing at the site in the form of
emergency condenser, suppression pool and underground storage
tank is adequate to cater to the cooling requirements for
extended periods of more than 10 days," the task force said.



The task force for the Rajasthan Atomic Power Station
(RAPS) considered the scenario of possible flooding due to a
break in the upstream Gandhi Sagar dam.



It found that on-site power will be available in such a
scenario.



RAPS-1, built with Canadian assistance, is a
Canada-deuterium-uranium (CANDU) type. It became the prototype
for the country`s indigenous Pressurised Heavy Water Reactors
(PHWRs). India completed the RAPS-2 on its own after Canada
suspended its assistance following India`s 1974 nuclear test.



"A separate, Station Black Out Diesel generator is
provided at a height of about three meters above flood level.
Water resources available in several tanks at a higher
elevation is adequate for the safety systems," the task force
found.



At the Madras Atomic Power Station (MAPS), the task force
said that the finished floor levels of the buildings were
higher than the maximum flood level postulated.
It noted taht MAPS had already handled the Indian Ocean
Tsunami in December 2004 successfully and core cooling was
maintained without any interruption.



Additional measures in the form of tsunami bunds have
been constructed along the shore which will further reduce the
intensity of tsunami, it said adding that a tsunami alert
system was also available at this station.



"One of the diesel generators and two diesel driven fire
fighting pumps are located at a height of about three meters
from the flood level. The reservoirs at site which are at a
higher elevation and at a considerable distance from the coast
and the water contained in the various tanks and suppression
pool will cater to the requirements for more than 10 days," it
said.



The task force for all the standardized PHWR type of
reactors, found that the seismic design was adequate to cater
to all seismic events that can occur in the seismic zone in
which the plants are located.



"There is also a margin of 1 to 4 meters above flood
level postulated for the respective sites. The water inventory
at these sites will also suffice for meeting the requirements
for a period of more than 10 days and in some cases upto even
30 days. The spent fuel pool water inventory is also assessed
to be adequate for more than 10 days," it found.



Standardised PHWRs are located at Narora (two units),
Kaiga (four units), Kakrapar (two units) and Tarapur (two
units).



Narora-1 had faced the extended black out scenario had
during the turbine fire in 1993.



The event was successfully handled to maintain adequate
core cooling, it said.



The events at Three Mile Island in the US, and Chernobyl
in Ukraine, had brought out many learning points which were
studied and incorporated in Indian reactors.
Jain said the Atomic Energy Regulatory Board has also
constituted a high level specialist committee to study the
implications of the accident at Fukushima and examine the need
for enhancing the safety of Indian nuclear power plants.



The committee will also be submitting its report and
NPCIL is committed to incorporate all the recommendations made
by the committee, Jain said.



PTI



First Published: Wednesday, April 13, 2011 - 22:17

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