The ‘First Approach to Criticality’ in the second reactor of Kudankulam Nuclear Power Project commenced at 7.52 p.m. on Friday and the reactor is expected to attain criticality within the next 48 hours.
Sources at the KKNPP said the First Approach to Criticality (FAC) started with withdrawal of control rods from the reactor, which would be followed by boron dilution within the next four hours and it would lead to the criticality of the reactor.
After the control rods are gradually lifted to increase neutron concentration inside the core, where 163 bundles of enriched uranium fuel have been kept, dilution of boron solution would start to facilitate early chain reaction. Once the boron dilution is started, it would allow neutron concentration to go up and kick-start nuclear fission – the chain reaction that will generate the heat required for producing water vapour which, in turn, would operate the turbine.
Though Atomic Energy Regulatory Board (AERB) had given its final nod for criticality through the permission it had forwarded to KKNPP administration on June 27, work on the ‘first approach to criticality’ cannot be started as all safety measures incorporated in the reactor and its smooth functioning have to be inspected by the experts of Ministry of Environment, Forest and Climate Change, as mandated by the Supreme Court.
When the apex court heard the case that challenged the construction of nuclear reactors at Kudankulam, it mandated on May 6, 2013 that 17 recommendations of the AERB and 15 guidelines pertaining to environmental safety should be followed scrupulously.
The Supreme Court also prescribed that the safety measures integrated in the reactor should be inspected by the experts of Ministry of Environment, Forest and Climate Change and Tamil Nadu Pollution Control Board and submit their reports to the Registrar General of Supreme Court prior to criticality.
Consequently, Joint Chief Environmental Engineer of the TNPCB, Madurai, Manoharan reviewed the safety measures in the second reactor on June 22 and 23 and has submitted his report on the same to his higher-ups to be formally forwarded to the Supreme Court.
On their part, 8-member team from Ministry of Environment, Forest and Climate Change inspected the second reactor on July 1 and 2 and submitted its report to the apex court.
Subsequently, the KKNPP has been given the green signal for commencing the First Approach to Criticality.
