Analysis of GE BWR blowdown heat transfer program, test 4906 (AEC Standard Problem Four). Key phase report

Standard Problem Four is the analysis of test number 4906 in the General Electric Boiling Water Reactor Blowdown Heat Transfer Program. This analysis is intended to be a realistic prediction of test 4906. The corresponding safety analysis was not attempted. The computer code used for this analysis was the RELAP4 code with the appropriate changes to provide a more realistic prediction of the experimental results. It was concluded that these calculations display the general features expected from a BWR recirculation loop break although several peculiarities are present. First of all, the system pressure initially falls as expected but then increases somewhat prior to the uncovering of the jet pumps. The second unusual feature is that the calculated pin temperatures remain unexpectedly low