ML20133L001

Final Part 21 & Deficiency Rept DER 85-20 Re Cooper Energy Svcs Broken Diesel Generator Rocker Arm.Initially Reported on 850528.Rocker Arm Replaced.Tappet Clearances Will Be Adjusted at 18-month Intervals

ML20133L001
Person / Time
Site:	Palo Verde
Issue date:	09/30/1985
From:	Van Brunt E ARIZONA PUBLIC SERVICE CO. (FORMERLY ARIZONA NUCLEAR
To:	Kirsch D NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V)
References
REF-PT21-85, REF-PT21-85-440-000 ANPP-33604-TDS, DER-85-20, PT21-85-440, PT21-85-440-000, NUDOCS 8510220474
Download: ML20133L001 (6)

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Arizona Nuclear Power Project l P.O. BOX 52034

• PHOENIX, ARIZONA 85072-2034 -3 R,' 1: 22 September 30, 1985 TClC4 VI4p ANPP-33604 -TDS/TPS U. S. Nuclear Regulatory Comission 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

Subject:

Final Report - DER 85-20 A 50.55(e) Reportable Condition Relating to Broken Diesel Cenerator Rocker Arm File: 85-019-026; D.4.33.2

Reference:

A) Telephone. conversation between R. C. Sorensen and P. J. Coffin on May 28, 1985.

B) ANPP-32907, dated June 26, 1985 (Interim Report)

C) ANPP-33358, dated September 9, 1985 (Time Extension)

Dear Sir:

Attached is our final written report of the Reportable Deficiency under 10CFR50.55(e), referenced above. The 10CFR21 Evaluation is also included with this report. '

Very truly ours i

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. D O llA.

E. E. Van Brunt, Jr.

l Executive Vice President Project Director EEVB/TPS/pik Attachment cc: See Page Two l

' B510220474 850930 PDR ADOCK 05000528

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1. Mr. D. F. Kircch DRR 85-20 ANPP-33604-TDS/TPS  ;

September 30, 1985 cc: Richard DeYoung, Director Office of Inspection and Enforcement U. S. Nuclear Regulatory Commission Washington, D. C. 20555

3. C. Haynes D. B. Karner W. E. Ide D. B. Fasnacht A. C. Rogers L. A. Souza T. D. Shriver D. E. Fowler C. N. Russo J. R. Bynum J. M. Allen D. Canady A. C. Gehr C. A. Hierzer W. C.. Bingham R. L. Patterson R. W. Welcher H. D. Foster D. R. Hawkinson R. P. Zimmerman M. L. Clyde B. T. Parker T. J. Bloom D. N. Stover J. D. Houchen J. E. Kirby l

l Records Center Institute of Nuclear Power Operations 1100 circle 75 Parkway, Suite 1500 Atlanta, Georgia 30339 I

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FINAL REPORT - DER 85-20 DEFICIENCY EVALUATION 50.55(e)

ARIZONA. NUCLEAR POWER PROJECT (ANPP)

PVNCS UNITS 1, 2, 3

1. Description of Deficiency A broken rocker arm assembly was discovered on the right bank intake valves for the number five cylinder on Unit 2 Emergency Diesel Generator, (D/C) Train B. This condition was identified during investigation to determine the source of a sharp metalic noise coming from the rocker cover assembly when the diesel received a stop signal and was coasting down.

i The D/C is tag no. 2MDCBH01 supplied by Cooper Energy Services (CES).

EVALUATION The diesel generator (D/C) provides emergency power'to equipment required for safe plant shutdown in the event of loss of preferred power. Two D/C sets (Train A and Train B) are provided per plant.

The intake rocker arm is an internal component of the dicaci engine responsible for opening and closing the intake valves for its respective cylinder. This is accomplished as follows:

One end of a push rod has a roller attached to it which rides on a <

can of the rotating can shaft. As the high spot on the can (the i lobe) rotates around to the push rod, the push rod rises in its guide. The other end of the push rod rests in a seat in the rocker arm (See Figure 1). The rising action forces the inlet valves seated opposite the push rod down to the open position. As the lobe passes, the push rod comes down and the valves return to the closed position.

The investigation disclosed that the rocker arm on the #5 cylinder on the right bank was split open along the entire length of the arm. NCE MC-2695 documents this finding. Continued use of the D/C with the damaged rocker arm would have initially affected performance in that the intake and exhaust valves for that cylinder would not have operated.

With further use, the rocker arm may have split in two and jammed nearby components causing more extensive damage to the push rod, valves, and piston in that cylinder.

The damaged rocker arm was returned to CES for metallurgical analysis to determine the cause of failure. The resulting CES Report (Reference 2)

. stated the following:

(1) ~A scuffed area on the sperical push rod seat indicates that the push rod was loose and impacting on the side of the seat rather than sliding smoothly in the seat.

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Mr. D. F. Kircch DER 85-20

.Page Two (2) The ' details of the properties found in the rocker are are reported on the Data Sheet in Reference 2 and no gross  ;

casting defects were found in the fracture surface which confirms that the rocker arm was cast to the C-B Specifica-

- tion M-40N.

(3) A tensile test bar machined from the seat area had a tensile l strength of 41,000 psi. This value exceeds the requirements for a separately cast test bar even without factoring in the effect of section thickness.

This concludes that the design and fabrication of the rocker arm was satisfactory. The root cause of the failure of the rocker arm was due

, to improper adjustment of the push rod clearances. This caused the push rod to hammer against the push rod seat eventually breaking the rocker 1

arm. The failure is mechanical and is considered an isolated occurrence since, per Reference 2 and 3, the material and casting were not. found to be deficient and proper tappet adjustment will preclude recurrence.

Project records show that no clearance adjustments were made to the push l rods after the D/G was delivered to the jobsite.

i 7.I . Analysis of Safety Laplications Continued use of the D/C with the damaged rocker arm would have at '

least affected system performance by reducing the number of operable combustion cylinders from 20 to 19. In the worst case, the piston could have been damaged causing damage to the engine rendering the system inoperable, i

Based on the above, this condition is evaluated as reportable under the requirements of 10CFR50.55(e), since if this condition were to re-main uncorrected it would represent a significant safety condition.

This project also has evaluated this condition as' reportable under 10CFR21.21(b)(3). This report addresses the reporting requirements of i

the regulation with the exception of subpart (vi), regarding the number and location of such components supplied to other facilities.

III. Corrective Action The broken rocker are was replaced with a new rocker are under Start-up Work Authorization No. 16632. To preclude future failures, tappet clearances will be adjusted at eighteen month intervals.as required by Diesel Generator Engine Inspection Procedure No. 31ST-9DC01. Section 11 of the CES ' Instruction Manual (Document M018-388) details the procedure for valve tappet adjustment. The above= test procedure will be performed i on the Unit 2 and 3 D/C prior to entry into Mode 6 as required'by the j Technical Specification. Unit I was inspected under 31ST-9DG01 prior to 1 1

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Mr. D. F. Kirsch ,

DER 85-20 Page Three entry into Mode 6 and will be reinspected at the next regularly scheduled interval.

REFERENG (1) NCE MG-2695 (2) a s Laboratory Report #763, Bechtel log M018-524 (3) M S Letter No. 506 e

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