Mumbai: India's nuclear regulator ordered replacement of four defective valves of the system that cools the reactor of Kudankulam nuclear power plant after the problem was detected during ongoing pre-commissioning tests.

The defect in the components of the four valves--there are thousands of such devices in a nuclear reactor--was found during pre-commissioning tests early this year, officials said. "During testing of thousands of valves installed in the plant, the performances of four valves of a particular type were found deficient," R Bhattacharya, Secretary, Atomic Energy Regulatory  Board (AERB) said in a statement on Friday evening.

Officials said that the valves were in the Emergency Core Cooling System (ECCS) that removes heat from a nuclear reactor under extreme components. On finding the defective valves, the Nuclear Power Corporation of India Limited (NPCIL) had procured replacements through its Russian collaborators.

"These valves are requiring larger efforts to get corrected," another official said but added that this was not an unprecedented development. AERB Chairman S S Bajaj said the new components have been procured and were being assembled.

"Once assembled, the entire systems would be put through a series of tests. Subsequent clearances will be granted by AERB only after a satisfactory review," Bhattacharya said. Elaborating on the multi-level tests which are carried out, he said a Quality Assurance Programme is adhered to.

The programme "requires formulation of detailed quality assurance plans specifying the sequence of activities and identifying the quality control points at which physical inspection/verifications are performed by the Quality Assurance Groups of  contractors/manufacturers as well as independently by NPCIL.

It added that the AERB had cleared for an "initial fuel loading" at the plant as part of the commissioning activities and that "satisfactory demonstrations of functional capability are a  prerequisite for considering the plant suitable for operating phase."

Seeking to assuage concerns, AERB explained that the purpose of commissioning is to establish the achievement of design objectives and meeting the safety requirements. A thorough performance testing is carried out and the tests conducted during the commissioning process give the necessary data on performance of various components and systems.

The People's Movement Against Nuclear Energy (PMANE) has complained to Tamil Nadu Chief Minister J Jayalalithaa that KNPP has been constructed with substandard equipment and parts supplied by a Russian company.

(Agencies)

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