TIRUNELVELI: The much awaited Unit-2 (Reactor-2) of Kudankulam Nuclear Power Project (KKNPP) attained criticality at 8.56 pm on Sunday, the officials declared here.
The 163 uranium assemblies in the Unit -2 (Reactor -2) of KKNPP had been loaded in the Reactor 2 (Unit-2) on May, 2016. The uranium loading process took 8 days. Follwing which, tests including the containment leak test, reactor pressure vessel, piping line and system equipments, hydro test and steam generation test were conducted.
The tests results were submitted to Atomic Energy Regulatory Board (AERB) for clearance.
Atomic Energy Regulatory Board gave the clearance for conducting First Approach to Criticality (FAC) in the end of June. Tamil Nadu Pollution Control Board also gave its clearance.
Since the clearance of the Ministry of Environment and Forests was only left, a team from from Ministry of Environment and Forests visited the nuclear plant on July 1 and 2 , inspecting the unit-2.
Sources said then Ministery of Environment and Forest clearance submitted its affidavit at the apex court on July 8.
The same day late evening, the criticallity process ( First Approach to Criticality) started at 7.52 pm in Unit-2 of the nuclear plant.
It had to take around 48 hours for the Unit-2 to attain criticality. Slowly the Reactor -2 is nearing criticality which was supervised by NPCIL, Russian experts and AERB.
Boron (a neutron absorber) in used in the form of boric acid solution in the primary coolant to keep the nucelar reactor in a sub-critical state before attaining criticiality. The process of approach to criticality involved gradual dilution of Boron. It allows neutrons in the nuclear fuel matrix to multiply till a controlled self sustaining nuclear fission reaction attained in the reactor.
NPCIL officials said that Criticality means starting of controlled self sustaining fission chain reaction (neutron chain reaction). The ground break of the Unit-2 of KKNPP had been conducted in 2001 and the pour of concrete was done the next year.
After around 15 years, the Unit-2 has attaining criticality for the first time.
As 562. 50 MWe power generated from Unit-1 of KKNPP is being alloted to Tamil Nadu, it is expected that the same amount of power to be allotted to the home state from Unit-2.
Of the twin VVER reactors each 1000 MWe electricity generation capacity at KKNPP in Tirunelveli district, being implemented in technical collaboration with Russian Federation, Unit-1 is generating its second cycle of power production.
In 2013, AERB had granted clearance for ‘First Approach to Criticality” (FAC) of Unit-1 of KKNPP, started the FAC on July 11, 2013.
Then with in 48 hours, the plant attained criticality (start of controlled self sustaining fission chain reaction for the first time) on July 13, 2013.
The Unit-1 was synchronized to the Southern Grid on October 22, 2013.
Following which, the Unit-1 achieved power generation of 1000 MWe for the first time on June7, 2014. Then, KKNPP Unit-1 was declared commercial operation from midnight on 31st December, 2014.
Unit-1, was shut down on 24 June last year for Annual Maintenance and Refueling Outage.
Thought the officials said that the Annual Maintenance and Refueling Outage would take a period of 60 days, power generation was not started for more than 7 months.
Finally, 2nd cycle of power generation was started at the end of January this year.
S K Sharma, chairman and managing director of Nuclear Power Corporation of India Limited (NPCIL) also present here on Sunday.