| 摘要 |
Welding repairs are performed in an underwater environment adjacent the bottom head of the nuclear reactor vessel. To provide a dry welding environment, segments of a lower caisson are passed through the core plate holes and assembled along the interior surface of the bottom head. The assembled segments are held down by brackets and sealed to one another and to the bottom head by a water curable polymer. An upper caisson is passed through the core plate hole to sealingly engage the lower caisson. The caissons are pumped dry and welding equipment is passed through the caissons to effect weld repairs about the stub tube or along the bottom head cladding.
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