PURPOSE: To suppress the formation of the rolling loop in a material arising from neutral irradiation and to decrease radiation embrittlement by starting a power increase operation right after confirmation that the material temp. rises up to a prescribed value.
CONSTITUTION: The vacuum increase of a condenser 7 is started by a vacuum pump and in succession, the pump is switched to an air extraction vessel for start-up to increase the degree of vacuum, With drawing of a control rod is then started by a control rod driving mechanism 4 to put a reactor into a critical state. Both circulation pumps 3 are thereafter run and the temp. of the reactor water is increased up to a suitable temp. above about 190°C and below the rated operating temp. by the generated Jouel heat. The temp. of the material in the reactor and the temp. of the pressure vessel are monitored 10 to monitor the rising rate of the material temp. so as not to exceed 55°C/h by the restriction of a thermal stress. The reactor power is increased up to the prescribed power by withdrawing the control rod and controlling the recirculation flow rate upon confirmation that the material temp. attains the range above about 190°C and below the rated operating temp. The rated operation is thus started.
SHIGENAKA NAOTO
SUZUKI KAZUMICHI
NISHIMURA EIICHI
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