"During testing of thousands of valves installed in the plant, the performances of four valves of a particular type were found deficient," the Atomic Energy Regulatory Board said in a statement here this evening.
It, however, did not specify the exact nature of the deficiency in the valves at the Kudankulam Nuclear Power Plant's Unit-1 being built with Russian help.
The Nuclear Power Corporation of India is replacing the valve components as a corrective measure and their performance will also be reviewed by the regulatory officials.
Elaborating on the multi-level tests which are carried out, AERB, the sector regulator, said a Quality Assurance Programme is adhered to.
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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."
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.