TXX-6487, Interim Deficiency Rept CP-86-78 Re Structural Steel Bolting Connections W/Threads in Shear Plane in Unit 1 Cable Spreading Room.Initially Reported on 861107.Evaluation of Supports Continuing.Next Rept Expected by 871215
| ML20214U110 | |
| Person / Time | |
|---|---|
| Site: | Comanche Peak  |
| Issue date: | 06/04/1987 |
| From: | Counsil W, John Marshall TEXAS UTILITIES ELECTRIC CO. (TU ELECTRIC) |
| To: | NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM) |
| References | |
| CP-86-78, TXX-6487, NUDOCS 8706110054 | |
| Download: ML20214U110 (2) | |
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Log # TXX-6487
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Ref # 10CFR50.55(e) nlELECTRIC D j U,m, June 4, 1987 U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555
SUBJECT:
COMANCHE PEAK STEAM ELECTRIC STATION (CPSES)
DOCKETS NOS. 50-445 AND 50-446 STRUCTURAL STEEL BOLTING CONNECTIONS WITH THREADS IN THE SHEAR PLANE IN THE UNIT 1 CABLE SPREADING ROOM SDAR: CP-86-78 (INTERIM REPORT)
Gentlemen:
On November 7, 1986, we verbally notified your Mr. Tom Westerman of deviations in the structural steel bolting in the cable spreading room. This is an interim report of a potentially reportable item under the provisions of 10CFR50.55(e). Our latest interim report, logged TXX-6326, was submitted on l
March 9, 1987.
Specifically, specification 2323-SS-168,.Section 9.5, states that all field connections shall be made with high strength steel bolts in bearing type connections with threads excluded from the shear planes except where otherwise stated or shown on engineering drawings.
Instances of bolted connections with threads in the shaar plane which are not stated or shown on engineering drawings hrve been discovered in the Unit 1 Cable Spread Room.
As previous.y advised (TXX-6326) calculations have been completed which verify design adequacy of Unit 1 Cable Spread Room Framing. These calculations were prepared using the AISC Manual, 8th edition allowable bolt stresses and were found adequate. However, the FSAR commits to the use of AISC 7th edition in which bolt stress allowables are more conservative. An engineering review is in process to determine acceptability of the installation utilizing AISC 7th edition bolt stress allowables.
A review of the Design Change Authorization (DCA 32125, Rev. 0) allowing I
threads in the shear plane of Unit 2 Cable Spread Room Framing has been completed using the AISC 7th edition which found the allowable bolt stresses acceptable.
A review of 36 randomly selected sets of Units 1 and 2 Category I structural steel calculations revealed 3 sets to be inadequate when threads of high strength bolts were assumed to be in the shear plane (AISC 7th edition stress allowables). As a result, all Category I and II structural steel calculations involving high strength bolts / connections are being reviewed assuming bolts have threads in the shear plane.
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TXX-6487 June 4, 1987 Page 2 of 2 A review of calculations with bolt threads in the shear plane for equipment foundations has not resulted in the identification of an adverse condition.
Under the auspices of the equipment qualification program, the original calculations are being checked for Safe Shut-down Earthquake (SSE) using Operational Bases Earthquake (0BE) design stress allowables, which are conservative.
If attachments are determined to be inadequate, the bolts shall be replaced to eliminate threads from the shear plane using appropriate quality procedures and instructions for inspection and verification activities.
Evaluation of the effect of this issue on Cable Tray, Conduct, and HVAC Duct Supports is continuing and the design adequacy of these systems will be included in our next report.
Pipe Supports were evaluated and found to be acceptable. They are designed in accordance with procedure CPPP-7 and are not governed by specification 2323-SS-168, directly.
The determination of this issue relative to the affect on the safety of plant operations during its 40 year design life is scheduled to be completed by November 15, 1987.
Our next report will be submitted by December 15, 1987.
Very truly yours, bl,6.(_ovdWl W. G. Counsil By:
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/J. S. Marshall Supervisor, Generic Licensing DAR/dl c - R. D. Martin - Region IV CPSES Resident Inspector - 3 copies