N-zone: Fuelling Change at Kudankulam Nuclear Plant

The Kudankulam Nuclear Power Plant (KKNPP) will be undergoing a significant shift. The two 1,000 MW units, which are currently operational, are being readied to take in next-generation nuclear fuel, which offers higher uranium capacity, fuel burn-up and enhanced operational safety, besides reducing the quantum of spent fuel or nuclear waste.

If things pan out as planned, the units will be operating on the advanced fuel variant from 2021, reliable sources in Department of Atomic Energy (DAE) told Express. The new nuclear fuel is called TVS-2M, developed by Russia’s TVEL Fuel Company, a subsidiary of Rosatom State Atomic Energy Corporation, which happens to be the technical consultant and main equipment supplier for the KKNPP.

In fact, during the 11th International Forum ATOMEXPO-2019 held in Moscow, Russia, in April this year, Rosatom officials had openly aired the requirement for change in fuel variant for Kudankulam reactors, to improve the technical and economic performance of the plant. The expo was attended by DAE Secretary Kamlesh Nilkanth Vyas.

Oleg Grigoriev, Senior Vice President for Commerce and International Business of TVEL (Rosatom), had said, “We are currently working with Indian colleagues on finalising the agreement for supplying nuclear fuel for units 3 and 4 of KKNPP. Our main work focuses on introducing new nuclear fuel TVS-2M for Kudankulam units that are operational. We are working very closely and productively on that. All works are on schedule. Simultaneously, we are working to make Kudankulam NPP-ready for the new nuclear fuel by 2021,” he had said.

Though e-mails sent to DAE Secretary and Rosatom officials did not yield response, DAE officials confirmed that introducing the new variant is on the cards. “Compared to UTVS fuel assemblies, TVS-2M, specifically designed for Kudankulam VVER-1000 type reactors, has a proven history of improving power plant operation, as well as the ability to reduce the amount of spent nuclear fuel. The TVS-2M also allows the option of shifting the operations from 12-month to an 18-month fuel cycle,” sources said.

Deal with Iran

Only recently, Atomic Energy Organisation of Iran and Nuclear Power Production and Development Company of Iran signed an agreement with Rosatom’s TVEL for nuclear fuel supply to the Bushehr nuclear power plant, which proposes to replace the UTVS fuel assemblies with the more advanced TVS-2M fuel design. The first supply of TVS-2M fuel assemblies to Iran is scheduled for 2020.

To a query, DAE sources said there was no need for any major structural changes in the plant’s design components for having new nuclear fuel, which would have mandated fresh approvals from Atomic Energy Regulatory Board (AERB).

Shift to advanced fuel assemblies will also reduce the amount of spent nuclear fuel, the storage of which is becoming a major cause of concern. The unit-1 of KKNPP has been operational from 2014 and unit-2 from 2016. The spent fuel or nuclear waste is currently kept within the power plant in what is called Spent Fuel Pool (SFP). Only now, Nuclear Power Corporation of India (NPCIL) has shown the intent to construct ‘Away from Reactor’ (AFR) spent fuel storage facility in Kudankulam and public hearing will be conducted by Tamil Nadu Pollution Board (TNPCB) on July 10.

However, there is still a long way to go before India’s first AFR becomes operational. Though Supreme Court has extended the deadline till April 30, 2022, NPCIL may miss the deadline once again, considering the fact there are several clearances that are yet to be obtained, including environment clearance from Union Environment Ministry, sitting clearance from AERB etc. NCPIL is already lagging behind, even going by the revised schedule, a copy of which is available with Express, submitted before the Supreme Court.

Concerns over storage space

The concern is there is no information on how much of storage space is available in the Spent Fuel Pool. As per official records, Refuelling cycle of KKNPP reactors is usually 12 months, with 300 Effective Full Power Days of power operation and around 60 days for Refuelling Shut Down (RSD) needed. Reactor core consists of 163 Fuel Assemblies (FA), out of which 48 or 49 FAs are discharged from core to Fuel Pool (FP) during RSD and are replaced by similar number of new FAs.

Spent Fuel Assemblies at KKNPP are stored in a fuel pool located inside the primary containment of the reactor building. The fuel pool is divided into two compartments for spent fuel storage and also has a separate compartment for loading of a cask for spent fuel and new fuel. The total capacity of fuel pool is 565 cells for spent fuel assemblies and 64 cells for sealed cans for storing defective fuel assemblies. This storage capacity of spent fuel pool is sufficient to store spent nuclear fuel generated up to 7 years of reactor operation and one complete core unloading. After 8 years of reactor operation, spent fuel from fuel pool will have to be removed and stored at AFR.

Ferenc Dalnoki-Veress, scientist-in-residence and adjunct faculty at James Martin Center for Nonproliferation Studies, told Express that spent fuel management is a worry worldwide and operating a nuclear reactor with AFR is like building a house without a toilet.
As per an RTI reply received by anti-Kudankulam activist G Soundarrajan, unit-1 of KKNPP had tripped 11 times since March 2016 and the unit-2 has tripped 19 times during the same period. The expert said: “This is very unusual for a new reactor to break down these many times. This should worry the Indian government.”

Panel aired worries

The Advisory Committees for Safety Review of various Projects (ACPSR), during its 126th meeting in 2011, said AFR for Kudankulam plant should be made operational before five years of power operation i.e by May 2018.

This was made on a sound argument that in a hypothetical scenario, if there is any leak in one of the two compartments of fuel pool after five years of operation, Kudankulam unit will not have sufficient storage capacity to carry out the repair work, in which case NPCIL will have to shut down the unit.

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Source:NIE

Image Courtesy:The Hindu

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