Status of BWR vessel and internals inspection in the U.S.A

Concerns over the potential cracking of low alloy steel pressure vessel and its internal attachment welds made of Inconel material have presented U.S. BWR plants with significant challenges in inspecting hard-to-access vessel seam welds and internal components. Inspection access studies are being performed to determine inspection coverage and to define inspection hardware needs. A number of older BWR plants have begun to inspect their vessel seam welds from the interior wall of the vessel and through the cladding. Technologies under development are expected to enable U.S. BWR plants to access all important vessel seam welds, including those in the beltline region. Research efforts to establish degradation susceptibility and inspection priority of BWR internals are ongoing and rules for their inservice inspections are under development. (author)