The high-temperature-gas-cooled nuclear reactor (HTGR) utilizes the so-called tri-structural isotropic fuel, or TRISO-coated fuel, which is made of ceramic-coated grains of uranium dioxide. The very-high-temperature reactor (VHTR) is a type of the HTGR and is one of the most promising candidates for the fourth generation nuclear energy system (GEN-IV). The VHTR fuel needs to be designed to exhibit excellent safety performance up to burn-up of about 15 to 20 per cent fissions per initial metal atom (%FIMA), in view of economy of the resource.
Up to now, Nuclear Fuel Industry Co. (NFI) has fabricated the 2t-U of HTGR fuel, based on the technologies developed by Japan Atomic Energy Agency (JAEA). The highest quality in the world of this fuel has been shown during the operation of the High Temperature Engineering Test Reactor (HTTR) of JAEA, which uses this fuel. On the other hand, up to now the irradiation data up to high-burnup (target: 100 GWd/t or more) of the HTGR fuel, which is fabricated at the commercial scale and has the best qualitative characteristics in the world, has not been obtained.
The aim of this project is to carry out the irradiation test up to high burnup (target: 100 GWd/t) at about 1573 K (target) and to obtain the irradiation data on a state of the irradiated above-mentioned HTGR fuel, fabricated by NFI. Also assessment will be made relatively potential use of the fuel in the Kazakhstan High Temperature Gas Cooled Reactor (KHTR), which is planned to be constructed in Kazakhstan on a base of the best technology in the world< developed by JAEA and NFI. The irradiation test will be carried out in INP NNC RK, where both needed persons (the researchers and technicians familiar with material irradiation tests) and needed facilities are available.
The aims of this project are the following:
- Construction of special irradiation devices.
- Irradiation of samples of the fuel fabricated at NFI, study of gas release out of them and assessment of the fuel adequacy to KHTR.
Task 1 will be carried out in the 1st and the 2nd year of this project. Task 2 will be carried out in the 2nd and the 3rd year. The task implementation covers the following:
- Design and fabrication of the device for estimation of concentration gaseous fission products (GFP).
- The WWR-K universal loop facility sweep-gas-loop systems will be adapted to measurement of the GFP concentration by means of the above mentioned device.
- The fuel samples will be fabricated by Nuclear Fuel Industry Co. (NFI) on a base of the HTGR technology and supplied to Kazakhstan.
- Special irradiation device will be developed and fabricated.
- Fuel samples will be irradiated at 1573 K (target), up to a high burnup (target: 100 GWd/t).
- The irradiation parameters (temperature, neutron flux, etc.) and FP gas concentration data will be monitored in course of irradiation.
INP NNC RK will have a great preference in future irradiation tests of the HTGR fuel because in this project INP will develop and fabricate special irradiation device, the system for evaluation of FP concentration as well as acquire useful experience.
For Kazakhstan, a device for evaluation of GFP concentration is an essential component of the technology of fuel fabrication for KHTR, which is planned to be constructed in Kazakhstan, as well as for entrance to the world market of the VHTR fuel. Besides, technology of development of a device for evaluation of GFP concentration and irradiation test will allow:
- Provide weapon scientists and specialists from Kazakhstan with possibility for reorientation of their abilities to peace activities;
- Encourage reintegration of Kazakhstan’s scientists to international scientific society;
- Support applied researches and development of civil technologies, especially, in the area of environment protection, energy production and nuclear safety.
