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High Burn-up of Fuel in LWRs


Foundation for Achievement of High Burn-up (20-30% HM) of Ceramic Fuel in LWR-type Reactors and for Upgrading the Fuel Proliferation Resistance

Tech Area / Field

  • FIR-NSS/Nuclear Safety and Safeguarding/Fission Reactors
  • ENV-RWT/Radioactive Waste Treatment/Environment
  • FIR-FUC/Fuel Cycle/Fission Reactors

8 Project completed

Registration date

Completion date

Senior Project Manager
Svetlova A V

Leading Institute
MIFI, Russia, Moscow


  • International Atomic Energy Agency, Austria, Vienna\nTokyo Institute of Technology, Japan, Tokyo

Project summary

The purpose of the project is the development and analysis of the ways to realize technologies for forming the fuel nuclide composition of LWR-type power reactors with high burn-up (20% HM and over) of ceramic fuel and with protection of fissile materials against uncontrolled usage outside the nuclear energy system.

The subject of the project is an analytical neutronic foundation which should be followed by experimental and technological foundation for possibility to achieve ultra-high burn-up of ceramic fuel due to keeping the high multiplying properties of the fuel under the reactor operation for a long time.

On its subject-matter, the project proposed is an extension of current studies being performed under the collaboration agreement between Moscow State Engineering Physics Institute (MEPhI, Russia) and Tokyo Institute of Technology (TIT, Japan), Research Laboratory for Nuclear Reactors, head of the studies – Professor Masaki Saito.

The collaboration between these two higher education institutes of Russia and Japan develops successfully from 1993. Presently, the MEPhI-TIT collaboration is being conducted on theme “Study on Ultra-Long Life Cores Loaded with Transuranium Fuels”. Conceptual development of such reactor cores could allow to reduce substantially the scope of nuclear fuel management and to upgrade protection of nuclear materials against uncontrolled proliferation outside of civilian nuclear power industry.

The subject-matter of the project will allow to extend joint studies on analysis of fuel compositions based on mixed Th-U-Pu and Pa-Th-U fuels. The proposals on such an extension of studies are welcomed by Japanese side (TIT, Professor M.Saito).

The analysis of fuel composition effects on multiplying properties of the reactor lattices fuelled with 238U-237Np-Pu mixture or 232Th-231Pa-233U mixture will enable us to identify the spectrum of the fuel compositions which are able to maintain high multiplying properties till high or ultra-high fuel burn-ups. It is supposed that fissile materials are isotopically diluted with highly radioactive nuclides (239Pu is mixed with 238Pu, 233U – with 232U). Due to such an isotopic “denaturing”, it might be declared about high enough degree of fissile material proliferation protection in proposed nuclear fuel cycles.

The participation of specialists from MEPhI and other nuclear power institutes is planned in proposed project. The project will allow to re-orient the efforts of experts from MEPhI and scientists from the State Research Center “Institute of Physics and Power Engineering” (Obninsk), previously involved in nuclear weapon research and development, to applied problems of eliminating the radiowastes produced in nuclear fuel cycles and for useful utilization of weapons-grade plutonium.

The following scientific and technical tasks will be solved under the project:

1. Elaboration of requirements to fuel nuclide composition from viewpoint of its compliance with non-proliferation criteria as well as reactivity maintenance up to high fuel burn-up.

2. Development and verification of mathematical model and computer code package (basing on the SCALE 4.3 code) for calculation of multiplying properties and nuclide composition of fuel element lattices with correct accounting for fission products effect under ultra-high fuel burn-up.

3. Determining the range of acceptable and optimal compositions of LWR lattices which are able to maintain multiplying properties under high fuel burn-up for the fuel based on 238U-237Np-Pu mixture, for the fuel based on 232Th-231Pa-233U mixture as well as for cross fuel cycle with joint usage of nuclides from Th-U fuel cycle and from U-Pu fuel cycle.

4. Feasibility and acceptability validation for proposed fuel cycle with high fuel burn-up (neutronic parameters of reactor safety, radiation safety of fuel management, radiation stability of fuel elements and so on) including utilization of DUPIC-technology for fuel re-fabrication.

5. Determination of conditions for generation of such nuclide compositions (237Np-238Pu-239Pu and 231Pa-232U-233U) in fuel of nuclear power facilities with various neutron spectra which are able to meet both non-proliferation criteria and reactivity maintenance requirements.

6. Investigation of hybrid systems (hybrid blankets of fusion facilities and accelerator-driven systems) to find the schemes of nuclear fuel cycle where involvement of the hybrid facilities appears to be reasonable.

The final product of the project will be scientifically validated principles of forming the nuclear fuel cycle based on VVER-type reactors with high and ultra-high fuel burn-up (up to 20% HM) and with inherent protection against unauthorized proliferation. In its turn, this allows to reduce the scope of procedures with spent fuel (by a factor over than 5), to reduce the scale of radiochemical enterprises (by a factor over than 5), to centralize (including international centralization) fissile materials management with additional upgrade of their proliferation protection.

The project will be finished by issue of reporting documentation containing results of the studies, recommendations and list of publications.