New fuel technologies would raise efficiency of VVER units like Kudankulam in India 

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TVEL, the fuel arm of the Russian state atomic energy corporation Rosatom, is developing a series of new fuel technologies that could also help increase the efficiency of the operating units at India’s Kudankulam Nuclear Power Plant (KNPP), according to an expert.  
 

At a conference on nuclear fuels held earlier this month in Hyderabad, India, TVEL’s Senior Vice-President (R&D), Alexander Ugryumov, made a presentation on new Russian technologies, including new materials and models of nuclear fuel, solutions for higher uranium enrichment, as well as the closed nuclear fuel cycle and the new prospect this opens for NPPs.  

Rosatom is the equipment supplier and technical consultant for the KNPP, India’s largest nuclear plant operated by the state-run Nuclear Power Corporation of India Ltd (NPCIL). Rosatom is similarly collaborating in the construction of four more units at Kudankulam – 3, 4, 5 and 6 – of 1,000 MW capacity each. Units 1 and 2 started commercial operations in 2014 and 2016, respectively.  

Earlier this year, TVEL started supplying the more advanced TVS-2M fuel to Kudankulam, instead of the previously supplied UTVS model.  The new TVS-2M nuclear fuel enables an elongation of the fuel cycle from 12 to 18 months for the KNPP’s operating VVER-1000 reactor units 1 and 2, enhancing their performance and economic efficiency.  

Ugryumov noted that introduction of nuclear fuel with enrichment over the 5 percent level will enable operations of VVER-1000 reactors in longer 24-month fuel cycles. Extending the fuel cycle means that a power plant may stop reactors for refueling less frequently, thereby generating more electricity per year.   

Besides, longer fuel cycles imply fewer purchases of fresh fuel assemblies, as well as less offloading of irradiated fuel bundles and, therefore, less expenditure on handling of spent fuel.   

Ugryumov also said that using fuel with uranium enrichment over 5 percent may decrease the amount of annually replaced fuel bundles which would lead to significant economic benefits over the course of the power unit’s lifecycle.  

In his presentation, Ugryumov elaborated on the development of Advanced Technology Fuel (ATF), with new cladding materials that enhance its safety. The Russian ATF program includes the development and testing of new materials involving both the cladding and the fuel matrix.   

Under an ongoing lead test rod program being carried out in a VVER-1000 reactor at the Rostov NPP, several fuel assemblies containing ATF fuel rods with innovative claddings made of chromium-nickel alloy, as well as zirconium alloy with chromium coating, are undergoing irradiation.   

Besides, experimental fuel rods with four different combinations of fuel composition and cladding materials are undergoing the fourth cycle of testing in the MIR research reactor at the Research Institute of Atomic Reactors in Dimitrovgrad. In addition, testing of VVER and pressurised water reactor (PWR) fuel rods with new uranium-silicide fuel has started this year in the MIR reactor. 

Other major developments include the ongoing work on fast neutron reactors, and on closed nuclear fuel cycle technologies, which are based on fabrication of fresh uranium-plutonium fuel from reprocessed irradiated fuel.  

Ugryumov explained that the technologies of fast reactors and nuclear recycling would enable Rosatom to offer its customers a new integrated product described as the “Balanced Nuclear Fuel Cycle”.   

This Rosatom strategy would solve several highly important tasks. First, this would exponentially boost the feedstock for nuclear power plants. Second, this would enable recycling of spent nuclear fuel instead of storage. Moreover, as part of the nuclear fuel cycle this would allow utilising the accumulated ground stocks of depleted uranium hexafluoride and plutonium for production of fresh fuel.   

TVEL has already started construction of a 300 MW nuclear power unit equipped with the BREST-OD-300 fast neutron reactor at the Siberian Chemical Combine in Seversk.   

Both the fuel fabrication and the reactor units form part of the Pilot Demonstration Energy Complex (PDEC) being built at the Siberian Chemical Plant by TVEL. The PDEC is underway as part of the strategic “Proryv” (‘Breakthrough’ in Russian) project. It will include three linked facilities, making up a closed nuclear fuel cycle at one site — the fuel fabrication/re-fabrication unit, the 300 MW nuclear power plant with the fast neutron BREST-OD-300 reactor, and the unit for spent fuel reprocessing.  

According to TVEL, “after reprocessing, the irradiated fuel from the reactor will be sent for refabrication (that is, reproduction into fresh fuel), thereby giving this system the means to gradually become practically autonomous and independent of external resources supplies”.   

The nuclear power industry’s resource base will practically become inexhaustible thanks to the infinite reprocessing of nuclear fuel. At the same time, future generations will be spared the problem of accumulating spent nuclear fuel.  

TVEL announced last year it has developed a fuel rod design based on nitride uranium-plutonium (MNUP) fuel for the BREST-OD-300 fast neutron reactor,    

The world’s most powerful fast neutron reactor called the BN-800, currently operating at unit 4 of the Beloyarsk NPP in Russia, was loaded last year with the first serial batch of MOX fuel made of depleted uranium and plutonium oxides. The BN-800 fast neutron reactor is designed to use MOX fuel as one of the stages in the development of a closed nuclear fuel cycle.  

According to TVEL “distinct from traditional nuclear fuel with enriched uranium, MOX fuel pellets are based on the mix of nuclear fuel cycle derivatives, such as oxide of plutonium bred in commercial reactors, and oxide of depleted uranium which is derived by defluorination of depleted uranium hexafluoride (UF6)”.  

Rosatom is currently also developing the fifth-generation model of a uranium-plutonium fuel assembly named TVS-5, which would enable a fully automated unmanned fabrication of fuel with plutonium and its handling at nuclear power plants.  

Ugryumov concluded his presentation by saying that Rosatom is ready to provide foreign customers with a full range of solutions, including the processing of spent nuclear fuel in Russia, as well as manufacture and supply of uranium-plutonium fuel for common thermal neutrons reactors like light water units of the VVER type.