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Thorium reactors and fuels

Thorium is an alternative material for nuclear fuel. It can be converted into fissile U-233 by a neutron capture reaction. Thorium is more abundant than uranium, but it needs to be supported in the beginning by some fissile material. We are investigating possible fuel cycles with thorium in various reactor types. Such potential fuels exhibit different neutronic and thermomechanic characteristics and also the spent fuel characteristics are distinct from the uranium fuel.

Nuclear data preparation

Evaluated nuclear data are freely available from various data centres around the globe. The format of these evaluated is different from what is requested by calculation codes. We are utilizing processing codes to prepare reliable continuous and groupwise data for calculation codes.

Spent fuel characterization

Spent nuclear fuel is source of neutron and gamma radiation. It also produces heat due to presence of unstable nuclides. A reliable determination of the spent fuel characteristics is essential for all manipulations with the irradiated fuel. We are developing the best practices for these calculations and analysing sources of uncertainties in the process.

Neutron detection

Radiation detection

Neutron activation analysis

Fuel thermomechanical properties

Reactor core thermohydraulic

Accident tolerant fuel

Accident Tolerant Fuels (ATF) are defined as nuclear fuels for currently operated Light Water Reactors that can tolerate a severe accident in the reactor core for a longer time period than the current fuel system while maintaining or improving the fuel performance during normal operations and operational transients. There are many concepts under development all around the world, Department of Nuclear Reactors works on advanced cladding concepts such as multicomponent cladding, SiC/SiC or advanced steels with the focus on VVER reactors. In cooperation with UJP Praha, Faculty of Mechanical Engineering, CEITEC, other departments from the Faculty of Nuclear Sciences and Physical Engineering and other institutes, the Department develops, tests and mature materials that satisfy ATF requirements and can be potentially deployed in commercial reactors in the near future. The ATF team cooperates also with international commercial organizations such as Westinghouse Electric Company or TVEL and is involved in the joint ATF activities organized by OECD/NEA or IAEA.

Experimental neutron physics

Experimental reactor physics

Temperature feedback

Hardware and Software for nuclear reactors

The activity deals with computer based systems for I&C of nuclear facilities. Quality and reliability of computer based systems depends on the quality hardware and software of systems. Requirements for the hardware (IAEA, IEC and IEEE documents) are studied, a special attention is paid to the problematic of proper memory contents and possible change in semiconductor memories because of gamma and neutron radiation. The software quality assurance is also investigated - software requirements, software design, coding, verification, integration of hardware and software and validation. In the part of coding, C language restrictions for the use in I&C of nuclear facilities are studied according to NRC and MISRA documents. Big attention is also paid to validation. A system for validation of reactor I&C components was developed and used for validation of components for VR-1, LVR-15 and TRIGA MARK II reactors. The validation system is based on pulse, function and current generators controlled with the computer and use GBIB or USB interfaces. These generators simulate signals from neutron chambers and generate proper reactor power courses. Then response of validated components is evaluated by the computer. Also safety signals of safety relays are checked by multimeters with GPIB or USB interfaces. The software for the validation system was developed in the graphical oriented tool Agilent Visual Engineering Interface. Also a system for the simulation of the complete VR-1 reactor operation for non-active tests was developed.

Mössbauer effect