[en] In case of a single phase gas cooled reactor (GCR), the DNBR is not of concern. Integrity of the other components such as the pressure vessel, the pipes, the pump, and the steam generator are considered the same as a fossil power plant as well as a LWR. Nuclear graphite blocks in GCR are known to have much higher resistance to thermal transients than metallic alloys so that its integrity is considered maintained. It is also known that the thermal shock resistance of TRISO fuel particle is very high so that the load follow capability of a HTGR is excellent. However, we were not able to find a quantitative analysis on the thermal shock resistance of TRISO particle. There are numerous computer models to describe TRISO fuel performance during a steady state irradiation such as COPA. Since those are lacking the short time transient calculation capabilities, we have developed a new computer model and used it to simulate the stress behavior of a TRISO particle during transient including extreme one as well as load follow operation in this study. TRISO is strongly resistant against thermal transient. Thus there should be no practical limit on fuel for the load following operation. Further calculations shows that, additional graphite layer of few milli-meter is sufficient to ensure the thermal resistance under extreme quench

[en] Research and development programs from 1945 to the present on coated-particle fuels are reviewed. 11 references. (U.S.)

[en] Description of method and handling of fluidized beds with variable velocity of gas. Special use for coating fuel particles of reactors. (J.K.)

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[en] Development of processes by Exxon Nuclear Company, Inc. for fabricating spherical particle nuclear fuel (sphere-pac) during October 1979 through March 1980 is reported. The program surveyed available technology to develop an initial flowsheet as a design basis for process development. An 0.1 ton/day pilot plant was built to develop and demonstrate the fabrication of sphere-pac fuel. Process and equipment efforts have been directed towards the demonstration of processes and equipment necessary to fabricate sphere-pac fuel on a commercial scale

[en] The coated particle for the PYCASSO program is composed of zirconia kernel with a diameter of 0.5 mm and a PyC(pyrolytic carbon) coating layer with a thickness of 0.1 mm to produce physical data of PyC layer under the neutron irradiation in a reactor. TR126(1.06 g/cm³), TR127(1.76 g/cm³), TR131(1.95 g/cm³) and TR133(2.07 g/cm³) samples were prepared to analyze the effect of the variation of PyC layer density. The optical anisotropy factor(OPTAF) of PyC layer was measured by analyzing the polarization characteristics of the reflected light on the surface of a sample by using a photometer composed of a polarization microscope, data processor, a light source and a detector. The OPTAF of PyC layer for the samples ranged from 1.04 to 1.05. The OPTAF could be transformed into BAF(Bacon anisotropy factor) in the range of 1.14 to 1.16

No abstract available

[en] The fuel body of a fuel element consists of fuel particles coated with pyrolytic carbon arranged between walls constructed as screens. The screens are formed as cones, double cones or as corrugated pipes and move between the pipe walls of the cylindrical fuel element from one side to the other and back. The particles are held in their position by graphite-felt, graphite fabric or felt or fabric made of SiO₂. This stable geometric configuration guarantees that during operation changes of the power distribution in the reactor and reactivity jumps can be avoided. In research reactors even the emergency cooling becomes easier to be carried out. (orig.)

No abstract available