Problems with valves in the first unit at the Koodankulam Nuclear Power Project (KNPP) has delayed the synchronisation of the unit with the grid, officials said.
The Nuclear Power Corporation of India Ltd (NPCIL), India's atomic power plant operator, is setting up two 1,000 MW Russian reactors at Koodankulam in Tirunelveli district, around 650 km from here.
After several years of delay, the first 1,000 MW Russian-made reactor at KNPP and India's 21st reactor began its nuclear fission process July 13.
The 1,000 MW first unit is expected to be synchronised with the grid in 15-days time, they said.
A senior official of the Atomic Energy Regulatory Board (AERB) told IANS: "The performance of some parts can be checked only when the power generation is increased to certain levels."
"While we have issued clearance for the first unit to generate 50 percent power tests have to be done simultaneously and corrective action are taken."
He said the systems will be checked while increasing the power levels.
"Till the unit gets stabilised at a certain level, power generation will be increased and decreased," he said.
"Two valves inside the condenser in the first unit seems to have got stuck and they were later set right.
"NPCIL officials had to go to the root cause of the problem so that it does not occur again which in turn has taken time," a source told IANS.
The NPCIL started its work at the KNPP's first unit, soon after receiving AERB's clearance, so as to connect the unit to the grid when it generates 400 MW power.
KNPP site director R.S. Sundar earlier said the first unit would be connected to the grid by the end of August, generating 500 MW. But that did not happen perhaps due to the condenser valve problem.
After necessary regulatory clearances, power generation will be increased gradually to 50 percent, 75 percent, 90 percent and finally 100 percent.
NPCIL officials were not available for comment on the valve problem and the delay in connecting the first unit of KNPP to the grid.
KNPP is India's first pressurised water reactor belonging to the light water reactor category.
An industry source said the valves were not in use for a very long time owing to the project delays and hence they would have caused problems.
"Even in the case of thermal power plants, there will be teething problems with various components. It will take some time for the plant to stablise.
"The one advantage thermal plant has over nuclear plants is that components can be changed immediately whereas in the case of the latter, detailed studies are made and regulatory approvals have to be obtained," an official of a power plant manufacturing company told IANS.