Radiolytic gases, recombination

Work on the development of a catalyst for use in thorium oxide slurries to recombine the radiolytic ga.ses has been carried out as a part of the Homogeneous Reactor Project at the Oak Ridge National Laboratory [152]. More recently, Westinghouse (Pennsylvania Advanced Reactor Project) undertook similar studies. The experimental approach at both laboratories has been similar, and the results are in reasonable agreement. While sufficient data have been obtained to assure that a catalyst can be u.sed in both thorium and thorium-uranium oxide slurries for complete internal radiolytic-gas recombination, specific conditions for the most efficient catalyst preparation and use have not as yet been established. 

Radiolytic gas recombination CUSO4 (internal) flame and catalytic re-... 

Radiolytic-gas recombination Low-pressure sj stem platinized alumina catalyst High-pressure system CUSO4 in solution... 

In-pile studies. Radiolytic-gas production and recombination rates were determined in the ORNL Graphite Reactor using a slurry of Th02 containing approximately 2.8% uranium which w as approximately 93% enriched in The mixed oxide was prepared by coprecipitation... 

By u.se of rocking in-pile autoclaves, tests at negligible flow velocities have been made at neutron fluxes approaching 10 to evaluate corrosion rates and rates of production and recombination of radiolytic gas. 

Scram. A more rapid shutdown, equivalent to an emergency scram in a solid-fuel system, is the "dump. In this. situation the reactor is kept circulating for 2 min to permit recombination of the radiolytic gas in. solution during which time the steam valves are closed to reduce power output. Then the pres.sure in excess of the vapor pressure of the core and blanket is vented to make pressure balancing between core and blanket easier, and the dump valves are opened, permitting the rapid emptying of the core and blanket vessels so that the reactor is. shut down within minutes. This type of shutdown is only resorted to in case of emergencies such as excessive pressures or evidence of a leak of radioactive. solution from the reactor. 

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