Experimental results of the operational transient (OPTRAN) tests 1-1 and 1-2 in the Power Burst Facility

Operational transients occur occasionally in light water reactors when minor malfunctions of certain system components affect the reactor core. Potential effects of such malfunctions include a loss of the secondary heat sink, an increase in system pressure, and, in boiling water reactors (BWR), void collapse and a brief increase in reactor power. This report presents the results of the operational transient Tests OPTRAN 1-1 and OPTRAN 1-2, including a comparison of the data with posttest calculations and the postirradiation examination results. The OPTRAN 1-1 tests simulated operational transients with reactor scram. Four progressively higher and broader power transients at a constant coolant flow rate were performed. The first transient simulated a BWR-5 turbine trip without steam bypass, with fuel rods operating near BWR-6 core average rod powers. The second transient simulated a generator load rejection without steam bypass, with fuel rods operating near core average powers. The last two transients were performed at higher core average peak rod powers than safety analyses predict to be possible in commercial reactors to define failure threshold margins. Test OPTRAN 1-2 was performed to evaluate the probability and extent of fuel rod damage for the most severe BWR anticipated transient without scram (ATWS) thatmore » results in boiling transition, a main steam line isolation valve closure transient without scram. Two sets of two fuel rods were tested. In each set, an unirradiated fuel rod was used to heat the coolant to typical BWR conditions for each previously irradiated fuel rod. Following an extensive fuel conditioning period of operation, a single power transient was performed that simulated the power history and coolant conditions calculated for a main steam line isolation valve closure ATWS. Microfiche data are included in the back.« less