Fuel bundles removed from a leaking coolant channel at unit 1 of India's Kakrapar NPP in Gujurat state are intact and undamaged, Nuclear Power Corporation of India Ltd (NPCIL) said. The affected channel has been isolated and the of heavy water coolant leak has been stopped. The leak prompted the automatic shutdown of the India-designed 220MWe pressurised heavy water reactor on 11 March. In an update on its website NPCIL said cooling is being maintained in all the remaining channels and the reactor remains in safe shutdown. On 16 March, India's Atomic Energy Regulatory Board announced that the coolant channel responsible for the leak had been identified, although at that time some coolant was still leaking. The AERB said the incident has provisionally been rated as Level 1 - an "anomaly" - on the International Atomic Energy Agency's seven-level International Nuclear and Radiological Event Scale (INES). Kakrapar 1 began commercial operation in May 1993.
Kakrapar 1's core contains 306 coolant channels made of zirconium-niobium alloy, each holding 12 bundles of uranium fuel. "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". NPCIL said no increase in radioactivity or radiation levels has been observed in the plant or in the surrounding area since the incident occurred.
