ML20205P497
| ML20205P497 | |
| Person / Time | |
|---|---|
| Site: | Palo Verde  |
| Issue date: | 05/07/1986 |
| From: | Van Brunt E ARIZONA PUBLIC SERVICE CO. (FORMERLY ARIZONA NUCLEAR |
| To: | Kirsch D NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| References | |
| REF-PT21-86, REF-PT21-86-176-000 ANPP-36515-EEVB, DER-86-16, PT21-86-176, PT21-86-176-000, NUDOCS 8605210434 | |
| Download: ML20205P497 (5) | |
Text
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Arizona Nuclear Power Project
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P o. BOX 52034 e PHOENIX, ARIZONA 85072-M regio,yyu':
May 7, 1986 ANPP-36515/EEVB/LAS/DRL-92.11 U. S. Nuclear Regulatory Commission Region V 1450 Maria Lane - Suite 210 Walnut Creek, California 94596-5368 Attention:
Mr. D. F. Kirsch, Acting Director Division of Reactor Safety and Projects Palo Verde Nuclear Generating Station (PVNGS)
Units 1, 2, 3 Docket Nos. 50-528, 529, 530
Subject:
Final Report - DER 86-16 A 50.55(e) and 10CFR21 Condition Relating to Electrical Conduit Support Evaluation File: 86-006-216; 86-056-026; D.4.33.2
Reference:
(A) Telephone Conversation Between A. Hon and D. R. Larkin on April 8, 1986.
(Initial Reportability - DER 86-16)
Dear Sir:
Attached, is our final written report of the Deficiency under 10CFR50.55(e) referenced above. The 10CFR21 evaluation is also included.
Very truly yours, AR A LLC E. E. Van Brunt, Jr.
Executive Vice President Project Director EEVBJr/DRL/1df Idf/001/FE86-16 Attachments cc: See Page 2 8605210434 860507 PDR ADOCK 05000528 S
PDR g\\
5 3.27
4 DER 86 Final' Report Mr. D. F. Kirsch Acting Director i
ANPP-36515-EEVB/LAS/DRL-92.11 May 7, 1986-Page 2 cc:
J. M. Taylor, Director i
j Office of Inspection and Enforcement
.U. S. Nuclear Regulatory Commission Washington, D. C. 20555 A. C. Gehr (4141)
R. P. Zimmerman (6295)
Records Center Institute of Nuclear Power Operations 1100 Circle 75 Parkway - Suite 1500 Atlanta, Gergia '30339 i
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Idf/009/ FORM-7
O FINAL REPORT - DER 86-16 DEFICIENCY EVALUATION 50.55(e)
ARIZONA NUCLEAR POWER PROJECT (ANPP)
PVNGS UNITS 1, 2, 3 I.
Description of Deficiency During installation of Unit 3 electrical conduit s6pports, Field Change Request (FCR) 91832-E was issued to allow an alternate mounting arrangement for detail 23 on Revision 6 of electrical conduit support Drawing 13-E-ZAC-075. During the routine engineering review of this FCR, it was discovered that no calculation existed for alternate detail 23 of the same drawing. Alternate detail 23 was first approved for use by FCR 25,304-E, which was subsequently issued as Drawing Change Notice (DCN) No. 26 to Drawing 13-E-ZAC-075 in October of 1981. The Bechtel engineer who reviewed this FCR/DCN interpreted it to be similar in con-figuration to FCR 23,557-E, which already had a calculation prepared supporting it and, therefore, concluded that no additional calculations were required.
Further investigations revealed that notes restricting the use of alternate detail 23, which appeared on Revision 4 of Drawing 13-E-ZAC-075, were removed per DCN No. 29, which was incorporated on Revision 5.
Following these discoveries, cal-culations were performed to determine the adequacy of alternate detail 23 assuming unrestricted use throughout Category I buildings. The results of these calcu-lations indicated that the support member would be overstressed when subjected to maximum seismic loads in combination with the maximum allowable parameters of the detail.
During subsequent reviews, it was also discovered that detail 28 on Drawing 13-E-ZAC-078 did not accurately reflect the requirements of the engineering calculations. A critical stiffener plate required by the calculations was not shown on the drawing. Without this stiffener plate, a detail 28 installation subjected to the maximum seismic loading in combination with the maximum allowable parameters of the detail would result in the support member being overstressed.
EVALUATION In both alternate detail 23 and detail 28, the conduit supports are attached to the lower flange of structural steel members in a manner which introduces a torsional load that induces localized bending in the web of the structural steel member. The amount of localized bending which occurs is dependent on the magni-tude of the load carried by the support and on the location within the plant, which will determine the seismic load factor.
To identify and evaluate alternate detail 23 and detail 28 installations, a walk-down inspection for all levels of the Category I buildings in Units 1, 2 and 3 was performed. In addition, any conduit support installation which appeared to be similar to alternate detail 23 or detail 23, or a variation of the basic configuration of'these details which might also result in localized bending in the web of the supportin8 member, was also noted in the walkdown and evaluated based on as-built conditions.
The results of the walkdown indicate that all alternate detail 23 and detail 28 installations inspected meet engineering acceptance criteria given the actual locations and existing loading conditions.
Of the supports in Units 1, 2 and 3 which were judged to be similar to, or vari-ations of, alternate detail 23 and detail 28, two were found in the Unit 1 Control Idf/001/FR8616a1
Final Report - DER 86-16 Page Two Building, at elevation 140', which would produce overstressed conditions in the web of the supporting steel member during SSE conditions. These were identified in EER 86-ZJ-008 as support numbers 5 and 9, and were dispositioned to add bracing to eliminate the overstress condition. Both of these supp<rts had been approved for use by Bechtel Engineering Calculations 13-CC-ZS-009 and 13-CC-ZS-013. Review of these calculations indicates that the localized torsional effects were not adequately addressed and, thus, the overstress condition was overlooked. Con-sideration of localized torsional effects is normally included in engineering calculations for electrical raceway supports. The 100 percent walkdown inspec-tion of Units 1, 2 and 3 and the identification of only two cases where the loca-lized torsional effects were not adequately addressed, confirms that these are isolated cases.
Failure of the subject conduit supports and any subsequent damage to associated conduits, lE cables and circuits would only affect portions of the display for the Safety Parameter Display System (SPDS) and the Safety Equipment Status System (SESS). The displays for SPDS and SESS are not safety-related and, therefore, would not be required for the safe operation or shutdown of the plant. Position indication for affected valves / dampers and displays for the SESS and SPDS are still available in the main control room on each valve / damper handswitch.
The root cause of failure to adequately address localized torsional effects for these two cases was an oversight on the part of the engineer and checker respon-sible for the calculation. The root cause for lack of engineering calculations for alternate detail 23 has been identified as a failure of the engineer and checker, responsible for review and approval of FCR 25,304-E, to properly differ-entiate betwcen the configuration and application of alternate detail 23 and that of FCR 23,557-E.
Review of available information concerning detail 28 indicates the root cause for failure to include the critical stiffener plate, required by the calculation, was an oversight on the part of the engineer and checker responsible for the drawing. A 10 percent random sampling of all conduit support details was reviewed to determine if the requirements of the engineering calculations were accurately reflected in the drawing details. The findings of this investigation failed to indicate any other cases similar to detail 28 and, therefore, this also was con-cluded to be an isolated case.
II.
Analysis of Safety Implications Based on the above evaluation, the existing condition is considered not reportable under the requirements of 10CFRSO.55(e), since, if it was to remain uncorrected it would not adversely affect the safe operation of the plant. This condition is also considered not reportable under the requirements of 10CFR Part 21 since it does not represent a substantial safety hazard.
1 III. Corrective Action
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The following corrective action has been completed:
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A 100 percent walkdown of Category I buildings, in each unit, was Idf/001/FR8616a2
9 Final Report - DER 86-16 Page Three performed to identify an'd evaluate alternate detail 23 and detail 28 instal-lations.' Two supports similar to detail 28 were identified in Unit 1 (Control Building elevation 140') which would.become overstressed during an SSE event.
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These supports have been identified in EER 86-ZJ-008 and will be reworked to provide additional bracing to eliminate the overstress condition.
2.
A complete review of quality class 'Q' electrical conduit support drawings to verify that a calculation exists for each detail. No.other detail was found which did not have a supporting calculation.
3.
A 10 percent sample of quality. class 'Q' electrical conduit support details was reviewed to verify that the requirements of the engineering calculations have been accurately reflected in the. details presented in the drawings.
Results of this review indicate that all details reviewed fully and accur-ately reflect the requirements of the calculation.
4.
A 10 percent sample of quality class 'Q' electrical cable tray support details was reviewed to verify the existance of calculations for each detail.
Of the details reviewed, no other detail was found which does not.have a supporting calculation.
5.
Drawing Change Notices have been issued against Drawings 13-E-ZAC-075 and 078 to require prior case-by-case engineering approval of all future instal-lations using alternate detail.23 and detail 28.
REFERENCES (A) Letter B/ANPP-E-149526, MOC 427727, March 24, 1986 (B) Letter B/ANPP-E-149527, MOC 427728, March 24, 1986 (C) Letter B/ANPP-E-149545, MOC 427750, March 25, 1986 (D) Letter B/ANPP-E-149703, MOC 428418,~ March 27, 1986 (E) Letter B/ANPP-E-149871, MOC 428867, April 01,1986 (F) EER No. 86-ZJ-003 o
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