NPC seeks renewal of licence for Tarapur nuclear plant

The Tarapur Atomic Power Station, the country’s largest nuclear plant, has applied to the Atomic Energy Regulatory Board (AERB) for renewal of its licence, days after the Fukushima plant in Japan suffered a major damage following a devastating earthquake, leading to radiation leaks.

The five-year operational licence of the Tarapur plant, being operated by Nuclear Power Corporation (NPC) since 1969 on boiling water reactors (BWR), expires on March 31. In India, nuclear plants are required to seek a fresh licence from AERB after every five years.

The two plants share a similarity: Both units 1 and 2 of the Tarapur plant and unit 1 of Fukushima are operated on BWR supplied by GE.

“Tarapur has a three-tier safety programme which is reviewed by an in-house team, corporate-level team and AERB which again has got a two-tier review. The Tarapur station, which comprises unit I (160 Mw), II (160 Mw), III (540 Mw) and IV (440 Mw), has a well-defined emergency plan for fire, earthquake, floods and tsunami. The plant is conducting a radiation emergency exercise (plant, site and offsite) routinely to check responses of various agencies,” Tarapur station director R K Gargey told Business Standard.

He said the Tarapur station is located not far from the Arabian Sea, which is less prone to a tsunami and also a less seismic zone, the Fukushima plant is located in a high seismic zone.

Gargey also said no severe natural calamity had ever occurred in the vicinity of the Tarapur plant. Even the killer earthquakes in Latur, Maharashtra, in 1993 and Bhuj, Gujarat, in 2001, had little effect on it.

According to Gargey, after the Three Mile Island (TMI) accident in 1979 in the US, the NPC had installed an additional battery bank capable of powering for 12 hours at Tarapur. Further, it has added a 100 per cent start-up transformer to enhance the off-site power reliability.

In the aftermath of the Chernobyl nuclear disaster in 1986, NPC had revised all operating procedures at the Tarapur station, added a hydrogen-monitoring system and launched full scope inspection of primary containment.
 

MEASURING VOLATILITY Differences between Tarapur I&2 units and Fukushima unit 1
	Tarapur -1&2	Fukushimi - 1
Location of station batteries	2 x 100% battery banks are located 40 feet above the highest tide level  and can supply power for 12 hours	Assumed to be at lower elevation
Decay Heat Removal	Passive heat removal system, no external power needed and can cool the reactor  for 8 hours without any make-up water	Steam driven circulation system having active components.
Containment	Pressure suppression chamber having large volume of free space to accommodate huge quantity of vapour and gases	Less volume compared to Tarapur-1&2
Earthquake	Located in less seismic zone	Highly seismic zone
Tsunami	Located on the bank of Arabian Sea less prone to tsunami	Highly sensitive zone to tsunami

Moreover, Gargey said, NPC at the Tarapur station had carried out various safety upgrades like unit-wise segregation of electrical distribution and control and power cables, and unit-wise segregation of a reactor shutdown cooling system.

NPC has also opened a supplementary control room for all the four units, installed an independent fuel pool cooling system and carried out improvement of the redundancy of power supply to engineered safeguard equipment.

Gargey said the Tarapur station had not impacted the environment, marine ecology and horticulture. Representatives from the Maharashtra Pollution Control Board carry out routine checks for compliance towards this.