Techno-economic studies going on whether to rehabilitate it
The first reactor at the Rajasthan Atomic Power Station, the RAPS-1 at Rawatbhatta, near Kota, has been shut down permanently since October 2004. The natural uranium fuel has been taken out of the reactor, and the heavy water, which acted as both coolant and moderator, drained from it. The 100 MWe reactor has not been decommissioned though.
The reactor has had a chequered history since it started generating commercial electricity in December 1973.
The Government of India has appointed a committee to go into the techno-economic feasibility of reviving the reactor or the methodology of decommissioning it, entombment and so on. A former Chairman of the Atomic Energy Commission said, “It is an investment decision. It needs re-tubing. That is, its coolant channels have to be replaced en masse. So it is [a] question of deciding whether the investment is worth it.” A top official of the Bhabha Atomic Research Centre (BARC), Trombay, asserted, “The reactor has not been decommissioned. We can revive it any time we want.”
RAPS-1, built with Canadian assistance, is a CANDU (Canada-deuterium-uranium) type, similar to the Douglas Point Generating Station in Canada. RAPS-1 became the prototype for the country's indigenous Pressurised Heavy Water Reactors (PHWRs), which use natural uranium as fuel, and heavy water as both coolant and moderator. When India conducted its peaceful nuclear experiment on May 18, 1974 at Pokhran, Rajasthan, the construction of the second unit at RAPS had just got under way. But within four days of India's experiment, Canada suspended assistance for RAPS-2 and the heavy water plant that was under construction nearby. India took up the challenge and completed the construction of RAPS-2 on its own. Both RAPS-1 and 2 are under safeguards.
RAPS-1 had been plagued by a series of problems, especially from 1981 when a leak developed in one of the end-shields, which are a radiation-shield at the two ends of the reactor vessel. The unit was shut down in February 1994 when the nickel gasket of a device called over pressure relief device gave way, resulting in heavy water leaking out. Though the reactor was written off as inoperable, it was started up in March 1997 after the leak was plugged with a sealant called indium. Again, the reactor's end-shields gave way about three years later.
“Since the reactor was shut down in October 2004, techno-economic studies are going on whether to rehabilitate it or not,” said a Department of Atomic Energy (DAE) official. “Since the unit is under safeguards, the natural uranium and heavy water that have been removed from it can be used only in another reactor that is also under safeguards,” he added.
If a decision is taken to decommission the reactor, the unit will be dismantled, all the equipment decontaminated and the radiation field around it will be allowed to come down over a period of time. The DAE official declined to hazard a guess how long it will take for the radiation field to come down to a reasonable level. Highly radioactive components will be buried in deep geological repositories.
RAPS-1 belongs to the Government of India, while the other 19 operating reactors in the country belong to the Nuclear Power Corporation of India Limited (NPCIL). The installed capacity of these 20 reactors is 4,780 MWe.
Keywords: Rajasthan Atomic Power Station