MONJU Primary prototype pump test

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In-sodium test was carried out for MONJU primary prototype pump, having a new hydrostatic bearing and convection suppressing fin. The test parameters were sodium level in the pump and flow of the seal gas. The test results are summarized as follows. (1)The pump operated satisfactorily on each condition of low sodium level with and without seal gas and normal sodium level without seal gas. This shows the pump has the soundness even in the cases of primary piping broken and the seal gas stopped. (2)It was obtained from the low sodium level test that each time of radial temperature difference for both inner and outer casings was its maximum and stable respectively. (3)It was approved that the maximum radial temperature differences for both inner and outer casings were increased with the time passing and sodium level falling, and also approved that the time which the temperature differences became their maximum were short with sodium level falling. (4)Maximum displacement of outer casing was smaller than the approved value at the lowest sodium level test, so it seems there is no problem on the real pump operation. (5)The test showed that convection suppressing fin was useful why the displacement of the casings were suppressed, because the times of the maximum radial temperature differences of the casings were late and displacement of outer casing was increased slowly. (6)It was approved that the pony motor of the pump was stopped and started again satisfactorily at the lowest sodium level.