TXX-6733, Interim Deficiency Rept CP-87-66 Re Hand Tightened Bolts in Structural Steel Connections W/Inadequately Spoiled Threads. Initially Reported on 870824.Design Change Authorization 46624 Issued.Next Rept Will Be Submitted by 880329
| ML20235G963 | |
| Person / Time | |
|---|---|
| Site: | Comanche Peak  |
| Issue date: | 09/25/1987 |
| From: | Council W TEXAS UTILITIES ELECTRIC CO. (TU ELECTRIC) |
| To: | NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM) |
| References | |
| CP-87-66, TXX-6733, NUDOCS 8709300312 | |
| Download: ML20235G963 (2) | |
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Log # TXX-6733 L
4 File # 10110 E
903.8 1UELECTRIC William G. Counsil Executive Vwe Prnskk,st U. S. Nuclear Regulatory Commission Attention:
Document Control Desk Washington, D. C. 20555
SUBJECT:
COMANCHE PEAK STEAM ELECTRIC STATION (CPSES)
DOCKET NOS. 50-445 AND 50-446 STRUCTURAL BOLTING IN TENSION SDAR:
CP-87-66 (INTERIM REPORT)
Gentlemen:
On August 24, 1987, we verbally notified your Mr. H. S. Phillips of a deficiency involving hand tightened bolts in structural steel connections with inadequately spoiled threads.
The initial written report was due on September 23, 1987. On September 23 1987, we verbally requested and received an extension from your Mr. R. F. Warnick until September 30, 1987.
This is an interim report of a potentially reportable item under the provisions of 10CFR50.55(e).
This deficiency was discovered during third-party investigations and addressed in Corrective Action Request CAR-73X.
For various sliding connections, structural design drawings specify hand tight bolts with jam nut or spoiled threads.
The jam nut or spoiled threads are intended to restrain the nut from backing off.
However, CAR-73X has identified five connections where hand tight nuts were installed as specified with spoiled threads but tho bolt threads nearest the nut were left intact and the nuts could have backed off several turns before being restrained by the spoiled threads.
The deficient connections could possibly transmit load through axial tension in the bolt.
Should the nut back off, the connection i
could fail to perform as intended.
Our evaluation of this issue includes revision of Specification 2323-55-168, I
" Structural Steel / Miscellaneous Steel (Category I & 11)," to include installation instructions and inspection criteria for hand tight bolts.
A backfit validation will then be performed for all applicable connections to the revised installation instructions and inspection criteria.
Any deficient connections that are identified will be documented on Nonconformance Reports and will be reworked to conform to the revised requirements of Specification l
2323-SS-16B.
The results of this backfit validation are required to determine the impact of this issue upnn the safety of plant operations.
G709300312 070925 PDR ADOCK 05000445 l
5 PDR h Ohve Street LB 81 Dallas. Teus 75201 Q
e TXX-6733 September 25, 1987 Page 2 of 2 Currently, Design Change Authorization (DCA) 46624 has been issued to add installation instructions and inspection criteria to Specification 2323 168.
To date, 285 connections involving hand tightened bolts which could be subjected _to tensile loads have been identified in Unit 1 and DCA 48517 has been issued to perform backfit validation of these connections.
Determination of the population of affected Unit 2 connections is currently being performed.
Our next report on this issue will be submitted no later than March 29, 1988.
Very truly yours, 44 a W. G. Counsil CBC:tgj j
c-Mr. R. D. Martin, Region IV Resident Inspectors, CPSES (3)
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