ML20215F025
| ML20215F025 | |
| Person / Time | |
|---|---|
| Site: | Palo Verde  |
| Issue date: | 09/29/1986 |
| From: | Haynes J ARIZONA PUBLIC SERVICE CO. (FORMERLY ARIZONA NUCLEAR |
| To: | Kirsch D, Kirsch F NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| References | |
| REF-PT21-86, REF-PT21-86-357-000 ANPP-38458-JGH, DER-86-27, PT21-86-357, PT21-86-357-000, NUDOCS 8610160054 | |
| Download: ML20215F025 (4) | |
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RECEgygg Arizona Nuclear Power Projedt" UCI -I fit l2: 4 f P.O. BOX 52034 e PHOEND ARIZONA 85072-2034 September 29, N[hd@ VMS ANPP-38458-JGII/LAS /DRL-92.11 U. S. Etclear Regulatory Commission Region V 1450 Maria Lane - Suite 210 Walnut Creek, CA 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 Repi rt - DER 86-27 A 50.55(e) and 10CFR21 Reportable Condition Relating to An Air Starting Valve Seat Insert Problem on Diesel Generators File: 86-006-216; D.4.33.2
Reference:
(A) Telephone Conversation between R. C. Sorenson and D.R. Larkin on August 29, 1986.
(Initial Notification -
Dear Sir:
Attached, is our final written report of the Reportable Deficiency under 10CFR50.55(e) referenced abovn. The 10CFR21 evaluation is also included.
Very truly yours, Wk J. G. Ilaynes Vice President Nuclear Production JGil/DRL:kp Attachments cc: See Page 2
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s DER ~86 Final Report Mr.'D. F. Kirsch Acting Director Page Two September 29, 1986 ANPP-38458-JGH/LAS/DRL-92.11 cc:
J. M. Taylor 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, Georgia 30339 i
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FINAL' REPORT - DER 86-27 DEFICIENCY EVALUATION 50.55(e)
ARIZONA NUCLEAR POWER PROJECT PVNGS UNITS 1, 2, 3 I
'I.
Description of Deficiency On August 12, 1986 ' Cooper Energy Services (CES) informed the Project of a potential problem with two emergency diesel generator engines at - PVNGS based on an occurrence at Niagara Mohawk's Nine Mile Point facility.
A problem could occur with the air starting valve inserts in the following engines:
engine 1M-DGB-H01, power head -SN-8L3010 and ' engine 3M-DGA-H01, power head SN-G11801. ' CES has identified the above power heads as having copper plated counter-bores. at the air starting valve inserts.
The copper plating was used on these power heads to achieve the proper press fit between the counter-bore and the valve insert. At elevated operating temperatures, the copper plating may fail due to compressive yield.
_ hen W
this happens, the air valve insert could loosen and slide down. In the counter-bore.
Evaluation At Nine Mile Point, two attempted starts on one emergency diesel engine
. were aborted - when the engine failed _ to crank in response to a start command. ' Ten successful starts were also recorded during this test period. The causes for the unsuccessful starts were loosening of the air valve insert and improper air start engine timing.
The problem was corrected by replacing the power head that had the loose air valve insert and adjusting the air start timing to the manufacturer's specifications.
Cooper Energy ' Services informed the Project of a potential for a loose air valve insert in two engines supplied to ANPP.
CES did not recommend immediate removal of the affected heads.
However, CES did recommend that ANPP conduct a test to determine the integrity of the starting air valve insert. The procedure includes cranking the engine without starting and determining the temperature rise at the starting air header adjacent to the head.
A rapid temperature rise due to compression pressure would indicate a loose air valve insert. ANPP reviewed the procedure with the Cooper site field engineer who stated that the engine integrity could be determined during normal operation.
The test was run with no abnormal temperature rise at the affected cylinder.
The test results were relayed
~
to the Cooper site representative. The final determination was that the air insert valve on Unit i had not moved.
CES recommends that the head should be replaced during the next available outage.
Root Cause
~
The root cause of this deficiency is attributed to the choice of plating _
material used on the power heads.
A significant difference in the coefficients of expansion between cast iron and plated copper exists.
CES has changed its plating procedure to use iron rather than copper.
,g*a e-Units 1 and 2 Operation According to CES, as described above, power head SN-8L3010 on diesel engine IM-DGB-H01 behaved normally and gave no indication of having a loose air valve insert.
The condition is documented in Unit 1 by EER 86-DG-098.
No deficiency exists in Unit 2.
Transportability CES indicates that this problem has been traced through their manufacturing records.
The deficiency is applicable only to the two cylinder heads previously identified (one in Unit 1,
IM-DGB-H01,
- SN-8L3010, and one in Unit 3, 3M-DGA-H01, SN-0M1801).
Safety Assessment Upon a start signal, the diesel engine air starting distributor meters compressed air to the cylinder's air start valves.
The pressurized air against the pistons causes the engine to roll over thus starting the engine.
Slippage of the air starting valve seat insert may block the flow of pressurized air as indicated by CES at the Nine Mile Point facility. Our. testing (witnessed by the vendor) gives no indication that our valve insert has moved.
CES noted that if the valve insert has not yet slipped they do not expect the insert to move in the future.
- Also, at Nine Mile Point the air starter system was not timed correctly, which aggravated their start problem.
Our air start timing has been verified to be correct.
II.
Analysis of Safety Implications Based on the above evaluation, it is concluded that the condition is Reportable under 10CFR50.55(e) and 10CFR21, since if left uncorrected and the air valve insert were to move as in the case at Nine Mile Point, a substantial safety hazard could result.
III. Corrective Action Unit 3 The CES identified cylinder head has been replaced with a spare from the warehouse.
The identified cylinder head will be reworked by CES to remove the copper plating or be replaced, i
Unit 1 Although no problem presently exists in Unit 1, as verified by testing, ANPP believes that as a prudent measure, the CES identified cylinder head will be replaced during a future outage under Work Order No. 169452, 3
4
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