ML20246F203
| ML20246F203 | |
| Person / Time | |
|---|---|
| Site: | Comanche Peak  |
| Issue date: | 08/23/1989 |
| From: | William Cahill TEXAS UTILITIES ELECTRIC CO. (TU ELECTRIC) |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| CP-88-40, TXX-89562, NUDOCS 8908300203 | |
| Download: ML20246F203 (2) | |
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.Ref. # 10CFR50.55(e) 7UELECTRIC.
August 23, 1989
,.,g Executive Vke President U. S. Nuclear Regulatory Commission Attn: Document Control Desk l
Washington,'D. C.
20555
SUBJECT:
COMANCHE PEAK STEAM ELFCTRIC STATION (CPSES)
-DOCKET,N05. 50-445 AND 50-446 NPSI' SWAY STRUTS SDAR: CP-88-40 (FINAL REPORT)
-REF:
- 1) NRC Notice of Violation (NOV) 445/8912-V-03, NRC letter dated March 24, 1989, R. F. Warnick to W. J. Cahill, Jr.
Gentlemen:
On ' January 3,1989, TU Electric notified the NRC, via interim report logged
.TXX-88856, of a deficiency involving NPS Inaustries, Inc. (NPSI) sway strut design. The last report on this issue was logged TXX-89091, dated
. February 24, 1989. After further evaluation, this deficiency has been determined to be reportable under the provisions of 10CFR50.55(e). The required information follows.
DESCRIPTION The NPSI design deficiency concerns the sway strut swing angle, defined as the angle created by a strut type pipe support when the pipe moves from the cold position to the hot' position. Originally, two Unit 1 pipe supports were identified as not having the required degree of swing angle freedom.
- However, subsequent field measurements demonstrated that the as-installed condition of one of the two supports satisfied the specification requirements.
Engineering calculations based upon actual field measurements indicate that the available degree of freedom of the other support is less than the specification requirements, but satisfies the as-built requirement for that support.
Although these two examples were determined to be acceptable, additional examples of swing angle interferences were subsequently identified among the pipe support concerns in NOV 445/8912-V-03 (Reference 1).
Consequently, NPSI was requested to evaluate the NPSI sway strut specified degree of swing angle-freedom at CPSES.
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August 23, 1989 Page 2 of 2 A walkdown~ of NPSI type SRF sway struts was performed as part'of a larger effort to identify potential pipe support discrepancies, including those identified as' discrepant in NOVs 445/8912-V-03 and 445/8906-V-02. During the walkdown, observations related to swing angle interferences were recorded.
The observations have been documented by a Corrective Action Request and a Project Technical Report which provide further details of the cause and extent of the condition, as well as the results of the NPSI requirements. The scope of SDAR CP-88-40 is limited to NPSI sway struts (SRF type struts sizes 06, 08, 12,-and 14) which, due to NPSI design error, have the potential for swing angle interference. The other items identified in the walkdown are i cessed separately in SDAR CP-89-011. " Pipe Support Deficiencies."
SAFETY SIGNIFICANCE NPSI has issued a Report of Defect under 20CFR21 indicating that an
'" unfavorable accumulation of tolerances" could result in failure to allow the full swing angle for_certain SRF type struts.
NPSI sway struts are used to support safety-related system piping.
Strut swing angle interference. could potentially impose unevaluated loads on' this piping and the supporting hardware.
Based on the findings at CPSES, the ability of the safety-related systems to perform their intended safety function is indeterminate and the safety of plant operations could potentially be adversely affected.
Hence, this issue is reportable under the provisions of 10CFR50.55(e).
[0RRECTIVE ACTION The appropriate installation specification and procedure have been revised to provide specific criteria to assure that the required swing angle freedom is provided. NPSI struts irstalled at CPSES, including the SRF types (sizes 06, 08, 12 and 14), are being reinspected and reworked as necessary to ensure compliance with the revised installation and inspection criteria.
The above corrective action for Units 1 and 2 will be completed prior to the respective fuel load dates.
Sincerely, W
'Q William J. Cahi 1. Jr.
SEC/vid c - Mr. R. D. Martin, Region IV Resident Inspectors, CPSES (3)