| 摘要 |
<p>PURPOSE:To improve residual stress while providing temp. difference to wall of a mother tube in thickness direction, by bringing cooling water existing between the mother tube and a thermal sleeve into nuclear boiling state while heating the mother tube at the position separated to the rear, further heating the mother tube. CONSTITUTION:The mother tube 4 made of austenitic stainless steel is attached to a reactor pressure vessel 1 at a weld joint 8 through a nozzle 2. Under the state of cooling water existence in a tubular hollow part 6 between the tube 4 and the thermal sleeve 5 in the inner part, at the position separated to the rear from a safe end 3 of base part of the sleeve 5, the tube 4 surface is heated by a heating means 9. In this way, stagnant water in the part 6 is made to nuclear boiling state. Under the state, the tube 4 surface at the position surrounding the sleeve 5 is heated by the other heating means 7. In this way, a large temp. difference in the tube 4 wall thickness direction is provided to cause thermal stress exceeding yield point and residual stress is improved.</p> |
