Central Electricity Regulatory Commission (CERC), in its order dated April 22, 2022, has allowed Nuclear Power Corporation of India Ltd (NPCIL) to draw start-up power from the grid under the Deviation Settlement Mechanism (DSM).
The concession is with respect to NPCIL’s Rajasthan Atomic Power Plant– Unit 7 (RAPP-7), which is taking shape at Rawatbhata in Chhitorgarh district of Rajasthan.
RAPP-7, which involves a 700-mw indigenously-made pressurized heavy water reactor (PWHR), started drawing start-up power from the grid (for commissioning operations) from March 17, 2020 with the original permission expiring on June 16, 2021. Subsequently, CERC granted extension in time limit to June 30, 2022, through its order dated June 6, 2021.
It may be noted that the overall project also envisages another similar unit, RAPP-8.
NPCIL has sought a further extension as it foresees delays in the commissioning of RAPP-7, for a variety of reasons. In its petition, NPCIL said that the second and third COVID waves adversely impacted the project commissioning schedule.
NPCIL also said that RAPP-7 will be equipped with several first-of-a-kind systems. As per guidelines of Atomic Energy Regulatory Board (AERB), all first-of-a-kind systems have to be proven to meet their system design intent, by way of mock-up and analysis. This has added to the delay in construction and subsequent commissioning activities, NPCIL said.
In its petition, NPCIL also said that there has been delay in supply of critical equipment, more so because the PHWR is completely indigenously designed and manufactured. The Central PSU also observed that there are limited qualified vendors in India for manufacturing of nuclear grade reactor equipment and components.
Current Status
As far as the power evacuation infrastructure is concerned, the 400kV switchyard has been charged and all 400kV lines are in service. The start-up transformer (220V/6.6kV) is in service and station auxiliary electrical system buses have been commissioned. Generator transformer-unit transformer back-charging through 400kV switchyard is scheduled in May 2022. Besides this, several activities related to nuclear power generation are underway.
After completion of all activities towards project commissioning, it is expected that the first “criticality” of RAPP-7 will take place by April 2023, followed by first synchronization by June 2023. [Criticality is the process of commencement of sustained nuclear chain reaction for generating nuclear power in a controlled manner.]
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Extension granted
In its order, CERC said that it was of the view that non-availability of start-up power would hamper the progress of commissioning activities and result in further delay in synchronization of RAPP-7. Accordingly, extension of time for drawl of start-up power from the grid till the synchronization of RAPP-7 or June 30, 2023, whichever is earlier, has been granted.
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