The inspectors identified an unresolved item associated with a flaw identified in the safe end-to-nozzle
weld of the
Reactor Coolant System N2E Nozzle. In July 2015, the licensee submitted a proposed alternative to
ASME Code, HNP-ISI-ALT-15-01 (
ML15183A354), to install a full-structural
weld overlay on
reactor coolant nozzle N2E (
1B31-1RC-12-BR-E). This proposed alternative was approved by the NRC in December 2015 (
ML15349A973). The licensee implemented this proposed alternative during the February 2016 refueling outage (1R27). After removing all but 1/16 of the existing overlay, the licensee performed a
liquid penetrant examination and noted a pair of linear indications. Subsequently, the licensee determined that these indications were actually a single indication, and that it exceeded allowable size limitations according to
ASME Code. Upon further review, the licensee realized that these indications were potentially the result of growth of an inner-diameter, surface-connected
intergranular stress corrosion cracking (
IGSCC) flaw found in 1988. The licensee has repaired the flaw, installed the full-structural
weld overlay, and completed all required post-installation examinations. This is an unresolved item pending review of whether the licensee performed all required examinations of the
N2E nozzle between 1988 and 2016, and whether the flaw exceeded minimum wall limitations at some point during prior operation. The issue will be tracked as
URI 05000321/2016001-01,
Reactor Coolant System N2E
Weld Flaw.
