FUEL DEFECT TEST-BORAX-IV

On March 11 and 12, 1958, the BORAX-IV reactor was operated at a power of 2.4 Mw, even though a large number of the fuel elements contained defects through the cladding. Subsequent investigation showed that 22 of the fuel elements in the reactor contained one or more ruptured rods. During operation, radiation fields in the vicinity of the turbine and condenser were high, but on shutdown all radiation levels decayed rapidly with a 30-min half life and after 12 hr all parts of the turbine and condenser showed only normal radiation levels of a few mr/hr. The effluent gases, the reactor steam, the condensate, and the reactor water were sampled during steady operation and analyzed for fission product gases and other fission products. An analysis of the data was made using information obtained from tests of defect ceramic fuel in EBWR, and an attempt was made to predict contamination levels throughout the system. Predicted levels agreed qualitatively with those found and in general the method led to high results. On the basis of these experiments it can be predicted that a boiling reactor, fueled with ceramic fuel, can operate for long periods of time with many defects through the cladding. Under these conditions, although activity levels may be hlgh during operation, no significant amount of long-lived contamination, other than fission gases which have stable daughters, will be released to the reactor surroundings. (auth