Fission product release experiments, design

Abstract. A water-cooled plant is described, with a rating of 500,000 kW from 200 tons of metal, and a potential output somewhat higher. The design allows for ready exchange of the metal without releasing pile gas or fission products, and provides a thickness of matenal at corrosion points which should be easily ample for a lifetime of 100 days according to the results of corrosion experiments. 

The primary objective of the BD-1 test is to obtain representative data on the release, transport, plateout, and liftoff of condensible fission products in an in>pile test loop under nominally "clean" conditions. These data will then be used to validate that the design methods used to predict fission product transport in the MHTGR have the required predictive accuracies. Typically, these transport codes contain multiple component models which are derived from differential single effects tests performed in the laboratory or in-pile experiments. The purpose of these in-pile loop tests is not to provide fundamental data from which transport models may be derived but rather to provide integral test data to assess the validity of these integral computer codes. 

Most proposed MSR designs call for the use of enriched lithium-7 and/or beryllium such as in the 70.7%T ,iF-17%BeF2-12%ThF4-0.3%UF4 fuel salt of the 1970s MSBR program. This carrier salt is often termed FLiBe. The presence of either Li or Be leads to significant production of tritium, on par with production levels in heavy water reactors such as CANada Deuterium Uranium (CANDU). For example in the 1970s, the 1000 MWe MSBR projected 2420 curies per day (ORNL 4541,1971), 98.3% from lithium and beryllium, and the remainder of 0.4% from fluorine and 1.2% from ternary fissions. For comparison, CANDU operations typically experience a tritium release rate of less than 24 curies per day (CNSC INFO-0793,2009). 

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