ML20237A983

Informs That Jr Hiller Will Be Submitting Full,Final Rept, Which Will Indicate Whether Reportable Defect Exists,Per 10CFR21 Rept.Testing & Determination Is Expected to Be Completed within Next 60 Days

ML20237A983
Person / Time
Site:	Duane Arnold
Issue date:	07/17/1998
From:	Hiller J AFFILIATION NOT ASSIGNED
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
REF-PT21-98 NUDOCS 9808170284
Download: ML20237A983 (1)

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RALPH A. HILLER COMPANY 4 6005 ENTERPRISE DRIVE Expont PA 15632 Iff $$*$$1$$$

July 17,1998 Document Control Desk United States Nuclear Regulatory Commission  !

Washington, DC 20555 i

Reference:

Hiller Document 98-NRC-002 l

Dear Sir:

Per the applicable requirements of Title 10, Chapter 1, Part 21 of the Code of Federal Regulations, as the responsible officer for the Ralph A. Hiller Company I advised the Nuclear Regulatory Commission of a possible defect in a letter dated May 19,1998 (Attachment A).

As required by 10CFR21, I will be submitting a full, final report, which will indicate whether a reportable defect exists or not. However, at this time we do not have sufficient data to make that determination. We are currently proceeding with physical testing which we feel is required to accurately assess the situation. I expect the testing to be complete and the determination to be completed within the next sixty (60) days.

Should you have any questions, you can reach me at (724) 325-1200, or fax me at (724) 733-1825.

- Thank you for your attention to this matter. ,;

Yours truly, RALPH A. HILLER COMPANY y- , j Cf ows&

J!,Ra olph Hiller , ,,

l ' thief Executive Officer .T1

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Attachments: (A) Hiller Document 98-NRC-001 JRH/klj cc: File i

9908170284 990717 ADOCK O ,,

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RALPH A. HILLER COMPANY 6005 ENrenPmst DmyE EXPORT.PA 15632 E.7$l$*$$:l$$$

May 18,1998 Document Control Desk United States Nuclear Regulatory Commission Washington, DC 20555

Reference:

Hiller Document 98-NRC-001

Dear Sir,

Per the applicable requirements of Title 10, Chapter 1, Part 21 of the Code of Federal Regulations, it is my responsibility as the responsible officer for the Ralph A. Hiller Company to advise the Nuclear Regulatory Commission of the attached "Possible Defect".

' As required by 10CFR21, I will be submitting a full, final report, which will indicate if a reportable defect exist or not.

Should you have any questions, you can reach me at (724) 325-1200, or fax me at (724) 733-1825.

Thank you for your attention in this matter.

Yours tru I L

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[KRandolph Hiller (AC d w' Chief Executive Officer L Attachments: (1) " Notice of Possible Defect per 10CFR21" cc: file I b ihrP h m -

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RALPH A. HILLER COMPANY l Goo 5 ENTgnemst omvt ExponT. PA 15632 I frLE. 412 325-1200 FA x. 412 733-te25 l

Attachment 1 " Notice of Possible Defect ner 10CFR21" i

Background

i The Ralph A. Hiller Company of Export PA is a supplier of safety related components to Nuclear Power i Plant.; with a Quality Assurance Program per the requirements of Title 10, Chapter 1, Part 21 of the Code  ;

l of Federal Regulations. A significant portion of these components has been valve actuators.

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Description of Event

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1 IES Utilities Inc., Duane Amold has reported that a Model SA A101 Main Steam Isolation Valve "A" j (MSIV) Actuator showed evidence ofintemalleakage, in both directions past the pneumatic piston. The l l actuator was returned to the Hiller Company's production facility for evaluation. Evaluation verified the l excessive leakage and discovered a fracture of the pneumatic piston. The crack consisted of a cross l

sectional (through) crack in the web and reinforcement ribs at the center hub involving a 2: 180' on the hub area circumference.

Engineering Background The Model SA-A101 MSIV Actuator is a Basic Component, which has been classified as safety related. It consists of a 20" diameter bore pneumatic cylinder in tandem with a 5" diameter bore hydraulic cylinder.

The failure (safety) mode is the rod extended (valve closed) position. This position is achieved via an l external spring pack and is assisted by the pneumatic portion. The hydraulic cylinder is designed for speed i

control. This family of actuator is used as the MSIV Actuator at many other plants.

i The actuators designed by the Hiller Company for safety related applications are designed per the guidelines of ANSI B93.10. 'Ihe piston material is designed to be ASTM A48 cast iron with a tensile yield strength of 35,000 PSI. This material was chosen for its excellent compressive strength, good tensile strength, good machinability, and excellent resistance to gauling characteristics and is extensively used for

. pneumatic industry applications. However, the material does not have good bending strength.

When the Model SA-A101 MSIV Actuator s were purchased in 1989/90 by Duane .^ rnold, the production verification of the pistons for safety related service were programmatically required to be dimensionally l

checked, assembled, the correct assembly was verified and finally a leak test was required. Our records indicate each of these verifications was successfully performed.

Investigation l

The failed piston was tested to verify the material and failure mode. The failure was found to be caused by l bending stresses due to impact. The material was found to be cast iron with a tensile yield strength of 27,500 PSI. No inclusions were found which would initiate this type of fracture. No other indications of

- damage were found in the remainder of the actuator that could cause leakage.

Inspection of other MSIV Model SA-A101 MSIV Actuators, which have been in service at Duane Amold, found another with a similar, less severe crack, actuator "B". This actuator,"B", had been in service on the same Main Steam Line at the plant. The piston web was cracked in the same area, however the crack did not propagate through the pan and no leakage was detected. As part of IES's maintenance plan, both l.

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f Acmaators "6" & "B" had been refurbished and postproduction tested a second time approximately two years ago with no leakage.

Review of the exact nature of these failures indicated that the safety function of the actuator would not have been prevented, even if tr.e fracture had been catastrophic and the piston had become loose Crom the piston rod. The piston failed safety and would not have prevented the safety mode from occurring, produced by

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compressed air and springs Further testing on actuator "B" indicated that normal cycling of the actuator did not continue to propagate the failure.

Discussions with the owner, IES Utilities Inc and the plant designer, General Electric, indicate that operationally there is a standard test, which could create a pressure anomaly through the line. Discussions with the valve manufacturer, Edwards Valves, concluded this type of event could cause the valve to force the Actuator's piston rod into the Actuator (retract). The initiating event is still under investigation. The 4 hydraulic control system is not designed to mitigate shock waves that produce excessive internal hydraulic )

pressures. The excessive energy could cause damage of the pneumatic piston and/or the hydraulic control I assembly. The original specification did not require that the Actuator to be designed for this type of event j and there has not been a similar reported failure of a piston on any actuator designed by the Hiller '

Company.

Plan The Ralph A. Hiller Company is cuTently working to determine the cause and extent of the problem. This work requires a more thorough engineering review of the function of the MSIV Actuator in the plant and the stresses this could create in the piston. Per the applicable portions of the Ralph A. Hiller Company's Quality Assurance Program and 10CFR21 the findings of this investigation along with any recommendations will be reported to the Nuclear Regulatory Commission.

Sum nary There has been a crack found in two pistons, of two of the MSIV Actuators, in service at a single Nuclear Power Plant. A loss of function of the actuator did not occur. 'Ihese actuators were on the same Main Steam Line and it has been tietermined that the leaking piston would not have prevented the safe function of the basic component. At this point in time, the situation is being reviewed to determine if this failure could pose a " substantial safety hazard" to the particular, or any other Nuclear Power Plant.

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