Russian scientists are considering the future use of isotope-modified nitride nuclear fuel for its reactors.

According to materials posted on the procurement site of state nuclear corporation Rosatom on 5 February, the specialists at the AA Bochvar Research Institute of Inorganic Materials (VNIINM,  part of fuel company TVEL) are undertaking a preliminary project for the selection of promising methods for concentrating the nitrogen-15 isotope for production isotope-modified nitride nuclear fuel.

A pre-project is a completed research project aimed at justifying the implementation of a qualitatively new development.

In recent years, Rosatom has begun the practical development of the technologies necessary to implement a closed nuclear fuel cycle (NFC) and a two-component nuclear energy system based on thermal and fast neutron reactors in Russia.

Due to the increase in recycling of nuclear fuel, nuclear energy will be significantly expanded, and it will also be possible to reduce the amount of radioactive waste by "burning" dangerous radionuclides.

For fast neutron reactors in Russia, within the framework of the  Proryv (Breakthrough) project a mixed uranium-plutonium nitride (SNUP) fuel based on nitrides – chemical compounds of uranium and plutonium with nitrogen  – has been developed and is being successfully tested experimentally.

SNUP fuel has a number of advantages both in terms of energy efficiency and in terms of safety. However, the use of natural isotopic composition in nuclear reactors of nitride fuel, in which the nitrogen-14 isotope fraction is 99.6%, poses environmental risks associated with the production of significant quantities of radioactive  carbon-14, which has a half-life of about 5700 years.

The only way to eliminate the risks is to use isotope-modified nitride fuel, in which the nitrogen of the natural isotopic composition is replaced by the nitrogen-15 isotope (its share in natural nitrogen is about 0.4%). For the practical feasibility of implementing the technology for creating such fuel, it is necessary to develop methods for the production of the nitrogen-15 isotope, ensuring the production of the required amount at an acceptable cost.

In accordance with the terms of reference, VNIINM specialists will “carry out a large preliminary assessment of the economic effect of replacing nitrogen of a natural isotopic composition with enriched nitrogen-15 in the low-energy fuel of the BR-1200 reactor and based on this assessment form boundary conditions for the limit price of enriched nitrogen-15 ".

The BR-1200 reactor is a fast neutron nuclear reactor with lead liquid metal coolant developed as part of the Breakthrough project. Russian scientists have prepared a technical proposal for the BR-1200 but its realisation will depend on the results of the demonstration Brest-OD-300 lead cooled fast reactor being built as part of the Proryv project.

Also, VNIINM specialists need to carry out a comparative technical and economic analysis of the known methods for producing nitrogen-15, and then offer either a number of methods suitable for solving the problem of producing this isotope in the required volume or a search for new methods that can give a satisfactory solution to the problem. Work must be completed by April of this year. The customer of the work is Rosatom's Proryv project.