ML20149E055
| ML20149E055 | |
| Person / Time | |
|---|---|
| Site: | Comanche Peak  |
| Issue date: | 02/04/1988 |
| From: | Beck J TEXAS UTILITIES ELECTRIC CO. (TU ELECTRIC) |
| To: | NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM) |
| References | |
| CP-87-66, TXX-88173, NUDOCS 8802100197 | |
| Download: ML20149E055 (2) | |
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r7 Log # TXX-88173
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File # 10110
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903.8 Ref. # 10CFR50.55(e) filELECTRiC February 4, 1988 becutive hr President i
U. S. Nuclear Regulatory Commission Attn: 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 (FINAL REPORT)
Gentlemen:
On August 24, 1987, we verbally notified your Mr. H. S. Phillips of a deficiency involving structural bolting in tension. Our last interim report was logged TXX-6733, dated September 25, 1987. We are conservatively reporting this issue under the provisions of 10CFR50.55(e).
The required information follows.
DESCRIP110N OF DEFICIENCY This deficiency was discovered during third-party investigations and addressed I
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 the bolt threads nearest the nut were left intact and the nuts could have backed off several turns before beina restrained by the spoiled threads.
The deficient connections could possibly-transmit load through axial tension in the bolt.
Shoul<i the nut back off, the connection could fall to perform as designed.
The cause of this deficiency is the failure of the design drawings and specification to provide sufficient installation and inspection requirements to properly install hand tight nuts with spoiled threads.
This deficiency is limited to structural connections with hand tight nuts and spoiled threads, 8802100197 080204 PDR ADOCK 05000445 S
PDR j
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l 400 North Olive Street. LB 81 Dallas. Texas 13201 V
r-TXX-88173 February 4, 1988 Page 2 of 2 SAFETY IMPLICATIONS Failure to adequately spoil the threads for connections requc.'ing hand tightened bolts could result in failure of these connections to perform as designed.
This issue is conservatively deemed reportable under the provisions of 10CFR50.55(e) due to the extensive evaluation required to establish the adequacy of the connections with inadequately spoiled threads.
CORRECTIVE ACTION Our corrective action for this issue includes the revision of Specification 2323-55-168, "Structural Steel /Hiscellaneous Steel (Category I & II)," to include installation instructions and inspection criteria for hand tiaht bolts. A hardware validation for applicable connections is being performed in accordance with the revised installation instructions and inspection criteria.
Any deficient connections that are identified will be documented on Nonconformance Reports and will be reworked where necessary to conform to the revised requirements of Specification 2323-SS-168.
Implementation of these corrective actions will prevent recurrence of this deficiency.
Currently, Design Change Authorization (DCA) 50432 has been issued to add installation instructions and inspection criteria to Specification 2323-55-168. To date, 232 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 a hardware validation of these connections. Determination of the population of affected Unit 2 connections is currently being performed.
The Unit I completion schedule for the field validation of this issue will be commensurate with the schedule for the Post Construction Hardware Validation Program (PCHVP). Corrective actions for Unit 2 will be implemented prior to fuel loading for Unit 2.
Very truly yours, I
W. G. Counsil Ow.
JolyW.BecT<L By:
Vice President, Nuclear Engineering c-Mr. R. D. Martin, Region VI Rtsident inspectors, CPSES (3) i
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