The ORR operated at an average power level of 27.9 MW for 88.9% of the time during January, February, and March of 1981. The reactor was shut down on seventeen occasions, seven of which were unscheduled. Reactor downtime needed for refueling, maintenance, and checks was normal, with the reactor remaining available for use 92.6% of the time. Maintenance activities, both mechanical and instrument, were essentially routine in nature with the exception of one Reactor Instrumentation and Controls Design Change Memo and one Mechanical Design Change Memo. Special tests or measurements completed during this quarter are reported in a summary entitled, ORR Reactivity and Flux Comparisons between a 280 g, 45 Weight Percent Enriched Texas Instrument Fuel Element and a 265 g Standard 93 Weight Percent Enriched Texas Instrument Fuel Element.

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 91.3% of the time during January, February, and March of 1980. The reactor was shut down on twelve occasions, six of which were unscheduled. Reactor downtime needed for refueling, maintenance and checks was normal, with the reactor remaining available for use 93.7% of the time. Maintenance activities, both mechanical and instrument, were essentially routine in nature with the exception of one Reactor Instrument and Controls Design Change Memo.

The ORR operated at an average power level of 28.7 MW for 73.4 percent of the time during January, February, and March of 1978. Eight new fuel elements were placed in service. The reactor was shut down on sixteen occasions, one of which was unscheduled. Reactor downtime needed for refueling, maintenance and checks was quite low, with the reactor remaining available for operation 88.9 percent of the time. Maintenance activities, both mechanical and instrument were essentially routine in nature. Special tests or measurements completed during the quarter included: (1) reactivity measurement of the Metals and Ceramics Division's (ORR-MFE-1) experiment in CP-C7; (2) flux mapping for core No. 143-B; and (3) calibration of all six shim rods on February 12, 1978 (Appendix A), and calibration of shim rods Nos. 2 through 6 on February 16, 1978.