Thorium high-temperature reactor

The Arbeitsgemeinschaft Versuchsreaktor (AVR) and Thorium High-Temperature Reactor (THTR-300) were both helium-cooled reactors of the pebble-bed design [29,42,43]. The major design parameters of the AVR and THTR are shown in Table 10. Construction started on the AVR in 1961 and full power operation at 15MW(e) commenced in May 1967. The core of the AVR consisted of approximately 100,000 spherical pebble type fuel elements (see Section 5). The pebble bed was surrounded by a cylindrical graphite reflector and structural carbon... 

The LS-VHTR uses the same type of coated-particle graphite-matrix fuel that has been successfully used in high-temperature gas-cooled reactors such as the Peach Bottom Reactor, the Fort St. Viain Reactor (FSVR), the Arbeitsgemeinshaft Versuchsreaktor (AVR), and the Thorium High-Temperature Reactor (THTR). At this time, graphite-based fuels have been demonstrated to be compatible with only two coolants helium and fluoride salts. 

DECOMMISSIONING OF THE THORIUM HIGH TEMPERATURE REACTOR (THTR 300)... 

The prototype Thorium-High-Temperature-Reactor (THTR 300) was decommissioned using the option of safe enclosure. E)ecision was made in 1989 and safe enclosure was reached in February 1997, followed by up to thirty years of operation of the safe enclosed plant. 

Based upon a former development at the Forschungszentrum Julich (FZ Jiilich, Research Centre Julich), two high-temperature gas cooled and graphite moderated reactors (HTR) had been operated in Germany a) the 15 MWe AVR reactor from 1967 until 1988 in Julich, and b) the 300 MWe Thorium High Temperature Reactor (THTR 300) from 1985 until 1988 in Hamm-Uentrop. The status of their decommissioning has been reported in Session I of this conference. 

THTR-300 Thorium high-temperature reactor 300 MWe built in Germany... 

Nuclear Applications. Use of the nitrides of uranium-235 and thorium as fuels and breeders in high temperature reactors has been proposed (see Nuclearreactors). However, the compounds most frequently used for this purpose are the oxides and carbides. Nitrides could be useful in high... 

Mixtures of enriched uranium and thorium are preferably used in high-temperature reactors operating as thorium converters. This means that is produced according to reaction (11.5) and serves as nuclear fuel. The conversion factor, given by the ratio of produced by reaction (11.5) to the amount of nuclides used up by... 

MSR developments in Russia on the Molten Salt Actinide Recycler and Transmuter aim to be used as efficient burners of transuranic waste from spent UOX and MOX LWR fuel without any uranium and thorium support and also with it. Other advanced reactor concepts are being studied, which use the liquid salt technology as a primary coolant for fluoride salt-cooled high-temperature reactors, and coated particle fuels similar to high-temperature gas-cooled reactors. 

As interest in the high-temperature reactor revived at the end of 1955, a working party was set up at Harwell. The new design was also intended to exploit what was described as the thorium cycle, whereby thorium 232 is converted to uranium 233, which is a fissile isotope. Thorium is both cheap and abundant, and this was seen as another way of stretching out the amount of uranium used, since uranium was then thought to be in short supply. 

The metal is a source of nuclear power. There is probably more energy available for use from thorium in the minerals of the earth s crust than from both uranium and fossil fuels. Any sizable demand from thorium as a nuclear fuel is still several years in the future. Work has been done in developing thorium cycle converter-reactor systems. Several prototypes, including the HTGR (high-temperature gas-cooled reactor) and MSRE (molten salt converter reactor experiment), have operated. While the HTGR reactors are efficient, they are not expected to become important commercially for many years because of certain operating difficulties. 

Fluidized-bed CVD was developed in the late 1950s for a specific application the coating of nuclear-fuel particles for high temperature gas-cooled reactors. PI The particles are uranium-thorium carbide coated with pyrolytic carbon and silicon carbide for the purpose of containing the products of nuclear fission. The carbon is obtained from the decomposition of propane (C3H8) or propylene... 

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