India has decided to arm all its nuclear reactors with automatic shutdown mechanisms that will be triggered at earthquakes much lower in intensity than what they currently work at.
The dramatic new plan is a part of the recommendations of an internal review by the Nuclear Power Corporation of India Limited, which runs the country’s nuclear reactors, in the aftermath of the Fukushima crisis.
“The recommendations, which we have decided to implement, include in-building automatic shutdown in all reactors, triggered at seismic activity significantly lower than what the reactor is designed to take,” NPCIL executive director N Nagaich told Hindustan Times on Thursday. “Safety is our prime concern.”
The Atomic Energy Regulatory Board — the country’s regulator for the sector — is conducting its own review and its recommendations will also be incorporated, Nagaich said.
At present, only four — at Narora and Kakrapar — of India’s 20 operating nuclear reactors automatically shutdown at seismic activity beyond their safe shutdown earthquake (SSE) — the earth shaking limit for which the particular reactor is designed, Nagaich said. The rest have monitors that sense seismic activity and trigger alarms, but need to be shut down manually once the SSE is reached, he said.
Reactors under construction at Rawatbhata, Kakrapar and Banswara were being designed with this facility even prior to the Japan quake.
All reactors will also start the process of shutting down at seismic activity much lower than the SSE – at which alarms for shutting down are presently triggered.
The NPCIL will provide additional back up power facilities — like batteries — that do not require a power line for all reactors, and will retrofit them to allow portable cooling water supplies to be hooked on.
One of the biggest problems the Japanese faced at Fukushima was the absence of such hook-up options, which hindered attempts at using portable, external power and water supplies once the in-built mechanisms collapsed following the quake and tsunami.
The NPCIL will also introduce additional sea shore protection measures at the Tarapur and Kalpakkam plants to protect them from tsunamis.
After the 2004 tsunami, a bund was built to screen the Kalpakkam plan from the direct impact of tsunami waves.