CBRN event in India on Fri 11th March 2016

On March 11, 2016, at 0852 hrs, Kakrapar-1 experienced an event of leak from a pressure tube. Following the event, reactor underwent automatic shutdown and all the safety systems provided in design for core cooling and containment isolation functioned as intended. There was no fuel failure due to the event.

Following the event, at 0910 hrs, plant emergency was declared as per an established procedure. This was terminated after safely defueling and isolating the leaky pressure tube from primary coolant system on March 21, 2016. During the course of plant emergency, environmental survey within the site as well as in the off-site domain up to 30 km was carried out. No increase in air borne activity or radiation level was observed. There was no radiological impact on plant workers, public and environment due to the event. The event was categorised as ‘Small LOCA’.

Root cause analysis of the event revealed that Kakrapar-1 had operated with an unlisted impurity (ethylene) in carbon dioxide gas which is used in leak detection system of pressure tubes. This led to corrosion on the outer surface of all the pressure tubes in the reactor and leak from the affected pressure tube.

The event is rated at level 2 on INES.