| 摘要 |
PURPOSE:To prevent the reference water in a reference head from boiling under reduced pressure and bumping by providing a heat insulator over the external circumferential surface of a reference water head pipe, and providing a porous material over the internal circumferential surface. CONSTITUTION:A reference water head pipe 2 has a condenser tank 4 at the upper part. This condenser tank 4 communicates with a vapor phase part of a nuclear reactor pressure vessel higher than the water level of filtered water through a condensed vapor pipe 5 to hold the water level of the reference water head invariably constant. Further, a communication pipe 3 is provided to the lower part of this reference water head pipe 2, which communicates with a differential pressure detector. The external circumferential surface of this reference water head pipe 2 is covered with a heat insulator 8 such as perlite and the internal circumferential surface is covered with a porous material 9, such as ceramic, which is capable of containing foam. |
