The ORR reactor operated at an average power level of 29.7 MW for 90 percent of the time during April, May, and June of 1976. Twenty-five fuel elements were declared spent (52.3 percent average burnup) during the quarter, while twenty-five new elements were placed in service. Two shim-rod elements were retired from service at an average burnup of 62.5 percent. The reactor was shut down on thirteen occasions, four of which were unscheduled. One end-of-cycle shutdown accounted for 61.1 percent of the total downtime. The remaining downtime was used principally for refueling and experiment work. Maintenance activities, both mechanical and instrument, were essentially routine in nature. A special test completed during the quarter was the visual inspection of the poolside facility. Operating data are presented.

The ORR operated at an average power level of 27.8 MW for 72.6% of the time during April, May, and June of 1978. The reactor was shut down on fifteen occasions, two of which were unscheduled. Reactor downtime needed for refueling, maintenance and checks was higher than normal due to beam-hole-plug maintenance, with the reactor remaining available for operation 82.4% of the time. Maintenance activities, both mechanical and instrument, were essentially routine in nature. Special tests or measurements completed during the quarter included gamma flux (heating) measurements made in core positions E-7, E-5, E-3, and C-7 using lattice configurations as indicated in figure Nos. 5, 6, 7, 8, 9, and 10.

The ORR operated at an average power level of 29.9 Mw for 82.8 percent of the time during January, February, and March of 1976. Two fuel elements were declared spent (58.8 percent average burnup) during the quarter, while twenty-eight new elements were placed in service. Four shim-rod elements were retired from service at an average burnup of 64.4 percent. The reactor was shutdown on nine occasions, one of which was unscheduled. Two end-of-cycle shutdowns accounted for 92.1 percent of the total downtime. The remaining downtime was used principally for refueling and experiment work. Maintenance activities, both mechanical and instrument, were essentially routine in nature. Special tests or measurements completed during the quarter were three calorimeter gamma heating runs made in CP-E5 during the end of Cycle 129 shutdown.

The ORR operated at an average power level of 29.8 Mw for 50.9 percent of the time during July, August, and September of 1976. One fuel element was declared spent (62.4 percent burnup) during the quarter, while five new elements were placed in service. Two shim-rod elements were retired from service at an average burnup of 69.0 percent. The reactor was shut down on twelve occasions, all of which were scheduled. Reactor downtime needed for refueling, maintenance and checks was quite low, with the reactor remaining available for operation 95.5 percent of the time. Maintenance activities, both mechanical and instrument were essentially routine in nature. In-service inspections completed during the quarter included: (1) inspection of the decay tank strainer on 9-21-76, and (2) inspection of the reactor primary heat exchanger No. 3, secondary side, on 9-24-76.

The ORR operated at an average power level of 29.8 MW for 90.7% of the time during April, May, and June 1981. The reactor was shut down on eight occasions, one of which was unscheduled. Reactor downtime needed for refueling, maintenance, and checks was normal, with the reactor remaining available for operation 91.6% of the time. Maintenance activities, both mechanical and instrument, were essentially routine in nature. In-service inspection completed during the quarter is described.

The ORR operated at an average power level of 29.9 MW for 83.3% of the time during this period. The reactor was shut down on five occasions, one of which was unscheduled. Reactor downtime needed for refueling and checks was normal. The reactor remained available for operation 93.4% of the time. Maintenance activities, both mechanical and instrument, were essentially routine in nature. Special tests completed during the quarter included results of flux measurements in the HFED experiment, cycles 167-D and 168-A, and results of reactivity worth measurements of MFE-4A Hf core sleeve as installed in core position E-3. In-service inspection completed during the quarter included the internal and external inspection of the pool heat exchanger.