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MTR-ETR Operating Experience

R. L. Doan

Nuclear Science and Engineering / Volume 12 / Number 1 / Pages 23-32

January 1962


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The MTR completed its ninth year of successful operation on March 31, 1961. During this period the reactor has been operating at design power, or better, approximately 70% of the time, for a total cumulative thermal energy production of 82,900 megawatt days. This represents an average of 768 Mw-days for each of its 108 months of operation. The operating power level, originally designed for 30 Mw thermal, was raised to 40 Mw in 1955. Although normally operating an a fully enriched uranium core, the MTR has also operated successfully for one fuel cycle on a 20% enriched core and a plutonium core. A total of 10,500 individual irradiations have been performed in the MTR under AEC sponsorship and 986 under commercial programs. The Engineering Test Reactor has been in successful operation at full design power of 175 Mw thermal for approximately three years, except for down-time occasioned by loop installations, experiment insertions and removals, and refueling. Total accumulated energy production to March 31, 1961, was 80,900 Mw-days. Installation of major in-core loops is continuing, but is expected to be essentially complete by the end of 1961. The down-time occasioned by such installations and the low-power tests required by some of them will hold the on-stream operating time for the ETR to about 50% during 1961. A total of 1215 individual irradiations have been performed in the ETR under AEC sponsorship and 21 under commercial programs. Roughly 41% of the $7,841,000 MTR-ETR program costs for FY 1960 were associated with the civilian reactors program, 40% with classified programs, and 3% with privately financed irradiations. The remaining 16% represents general research and development activities and radioisotope production. Approximately 700,000 C (curies) of radiocobalt have been produced in the MTR-ETR to date, mostly in the 20–50 C/gm range. Highest specific activity produced thus far is 308 C/gm. No serious reactor incident has been encountered to date in either the MTR or ETR, and there have been no serious overexposures of personnel to radiation. The basic operating philosophy places strong emphasis on safety of reactors and personnel. This philosophy is implemented by (1) a continuously functioning safeguard review board with power of veto over all reactor operations, (2) careful operator training and supervision, (3) firm instructions to all operators that the reactors are to be scrammed promptly whenever any of the instrumentation or circuitry indicates abnormal behavior, (4) prohibition against operating either reactor with any significant defects in control instrumentation, fuel elements or shim rods, and (5) strict limitations on permissible departures from standard operating parameters and procedures by reactor operators.

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