Information Notice No. 82-30: Loss of Thermal Sleeves in Reactor Coolant System Piping at Certain Westinghouse Pwr Power Plants
SSINS No.: 6835
NUCLEAR REGULATORY COMMISSION
OFFICE OF INSPECTION AND ENFORCEMENT
WASHINGTON, D. C. 20555
July 26, 1982
Information Notice No. 82-30: LOSS OF THERMAL SLEEVES IN REACTOR
COOLANT SYSTEM PIPING AT CERTAIN
WESTINGHOUSE PWR POWER PLANTS
All nuclear power reactor facilities holding an operating license (OL) or
construction permit (CP) and applicants for operating license (NTOL).
This information notice is to provide further notification regarding the
continuance of thermal sleeve failures in both pressurized and boiling water
reactor (PWR and BWR) plants. The potential safety significance of this
problem is still under review by the Nuclear Regulatory Commission (NRC)
staff. If NRC evaluation so indicates, further licensee action may be
requested. In the interim, the staff expects licensees to review the
information herein for applicability to their facilities. No specific action
or response is required at this time.
Description of Circumstances:
Past operating experience has identified fatigue failure problems associated
with nozzle-thermal sleeve assemblies in piping systems of both BWR and PWR
plant designs. (1) Similar fatigue failure problems have occurred more
recently in certain PWR plants designed by Babcock & Wilcox and are
described in Information Notice No. 82-09, dated March 31, 1982.
On June 9, 1982, NRC was notified by Portland General Electric (PGE) that a
steel sheet about 7" x 15" x 1/8" thick, with torn edges, was discovered in
the bottom plenum of the Trojan reactor vessel during an underwater
television inspection of in-reactor fuel conditions. Further inspection
revealed another metal piece lodged between the lower core plate and core
support plate. The pieces appeared to be parts of thermal sleeves initially
installed in the safety injection accumulator piping nozzle connections to
the reactor coolant system (RCS) cold leg piping. Radiography and ultrasonic
examination further confirmed the 10-inch thermal sleeves were missing from
all four safety injection (SI) piping nozzle connections.
The thermal sleeves consist of straight cylindrical sections. Two retainer
welds about 5/8- to 3/4-inch in length, located 180 apart, attach the
sleeve to the SI nozzle inlet. Four nozzle button welds and a raised,
integral machined ring on the thermal sleeve provide axial alignment of the
sleeve at the nozzle-to-RCS interface.
(1)NEDO-21821, 1978; NEDO-9693, 1980; WCAP-7477, 1980; NUREG-0691, 1980.
July 26, 1982
Page 2 of 2
Based on the above results, the nozzle-thermal sleeve assemblies of similar
design were examined with the following results. A crack indication was
found in one of the two retainer welds of the 14-inch sleeve in the
pressurizer surge line, to RCS hot leg connection. A slight indication was
found in a retainer weld on one of the two 3-inch thermal sleeves in the
normal and alternate charging lines.
Plans are being developed by PGE for recovery of the thermal sleeve
components from the vessel and analysis of the failure mechanism. PG and
Westinghouse are currently evaluating the need for replacement sleeves that
have failed or those that may be removed because of potential failure.
Duke Power Company also notified NRC that a radiography examination and
underwater camera inspection on July 4 and 5, 1982, respectively, indicated
the thermal sleeve in one of the four SI accumulator piping nozzles to RCS
cool leg piping (i.e., Loop B) in McGuire Unit 1 was missing. Radiography
confirmed the sleeves in Loops A, C, and D, as well as the pressurizer surge
line to RCS hot leg piping, to be in place. However, conditions of all th.e
retainer welds in the affected systems remain to be established.
Westinghouse has notified its PWR customers of affected operating and
nonoperating plants with regard to the thermal sleeve problem. For the
operating plants, Westinghouse has recommended that (1) the loose parts
monitoring system be fully operational and (2) a nondestructive examination
be performed to assess thermal sleeve conditions of affected systems at the
next extended plant outage. Implementation of these measures would appear
prudent until this matter can be fully resolved.
If you have any questions regarding this matter, please contact the Regional
Administrator of the appropriate NRC Regional Office, or this office.
Edward L. Jordan, Director
Division of Engineering and
Office of Inspection and Enforcement
Technical Contact: W. J. Collins
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