| 摘要 |
PURPOSE:To prevent leakage from occurring at a valve seat of a water-steam two-phase boundary valve, by removing a plastically deformed part of the valve seat by heating the valve seat before fitting the valve into a plant. CONSTITUTION:A shut-off valve 10 provided in a residual heat recovering (RHR) system comprises a stem 14 inserted in a body 15 and a valve body 17 provided at a lower end part of the stem 14. In normal operation of a boiling water reactor, the valve body 17 makes contact with the valve seat 16, thereby preventing water B and steam A from making contact with each other. In a manufacturing step of the valve 10, a valve seat part of the valve 10 is heated to apply a heat load under the same condition as that in the operation of the plant. Then, the part is subjected to sliding machining, thereby removing the plastically deformed part. Accordingly, the thermal strain generated at a part subjected to a heat load in the succeeding use of the valve is made very little. |
