| 摘要 |
<p>In order to reduce the time required for refueling a nuclear reactor, the studs utilized for securing the head of the reactor pressure vessel are provided with modified breechblock threads at their lower ends, and also at their upper ends. After being detensioned, the studs are rotated 60 DEG for disengagement from corresponding threads in a flange at the top of the pressure vessel and are lifted out of the stud holes when the head is removed. The studs are tensioned and detensioned by a plurality of portable hydraulic stud tensioning devices or tensioners which are attached to the upper ends of the studs by the modified breechblock threads at the upper ends of the studs. The tensioners are carried by a separate hoist system mounted on the closure head for the vessel.</p> |
