"JOYO" Start-up test report; Measurements of low power reactor noise (NT-62)

Sanda, Toshio*; not registered; not registered; not registered; not registered; Yamamoto, Hisashi*

As a part of the dynamics tests in the experimental fast reactor "JOYO", reactor noise measurements were carried out. This report describes the experimental results performed during the low power test. In the experiment, two He neutron detectors were inserted in the core and two kinds of zero-power reactor noise techniques, i.e., the band-pass filter method and porality correlation method, were applied to determine reactor kinetic parameters. Major results are as follows. (1)Measurements of prompt-neutron decay constant (/) The agreement between measured results obtained by both techniques was in good. The measured value (1.7310s) agreed well too with the calculated value (1.77 10s). (2)Measurements of subcriticality Though the band-pass filter technique could not be applied PNC SN94180-68 beyond of the subcriticality of one dollar, the porality correlation technique could be applied in the range from zero to six dollars. In this range, the results obtained by the techniques agreed with those by other methods within 10%. The effectiveness of the porality correlation technique in FBR was confirmed. (3)Measurements of absolute power level The absolute power level obtained by the reactor noise method agreed with that by the nuclear power calculation tests within 10%.