Fuel bundles removed from a leaking coolant channel at Kakrapar unit 1 are intact and undamaged, Nuclear Power Corporation of India Ltd (NPCIL).
In its second public statement since a leak of heavy water coolant prompted the automatic shutdown of the 220 MWe pressurized heavy water reactor on 11 March, the company said that the affected channel had been isolated and defueled. Cooling is being maintained in all the remaining channels and the reactor remains in a safe shutdown state.
On 16 March, India’s Atomic Energy Regulatory Board (AERB) announced that the coolant channel responsible for the leak had been identified, although at that time some leakage of coolant was still occurring. NPCIL said that the leak has now been “arrested”.
Kakrapar 1’s core contains 306 coolant channels made of zirconium-niobium alloy, each holding 12 bundles of uranium fuel. The fuel is cooled by a flow of heavy water under high pressure – the primary coolant – which generates steam in a secondary circuit to drive the electricity-generating turbines.
“The investigation will now be carried out to find the cause of the failure,” NPCIL said. It intends to restart the unit after completion of the investigation, inspection of relevant components and implementation of corrective actions, which will require clearance from the AERB. It said that lessons and recommendations emerging from the investigation would be “suitably incorporated”.
No increase in radioactivity or radiation levels has been observed in the plant or in the surrounding area since the incident occurred, NPCIL said.