ML20055C752

Responds to NRC Bulletin 89-002, Potential Stress Corrosion Cracking of Internal Preloaded Bolting in Swing Check Valves & Justification for Alternate Insp Schedule for One Valve. No Anchor Darling Swing Check Valves Installed at Plant

ML20055C752
Person / Time
Site:	Davis Besse
Issue date:	06/14/1990
From:	Shelton D TOLEDO EDISON CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
1807, IEB-89-002, IEB-89-2, TAC-74247, NUDOCS 9006250051
Download: ML20055C752 (3)

Text

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DONALD C. SHELTON 1 vumnnn (419] $49 P300 Docket Number 50-346 l License Number NpF-3 Serial Number 1807 June 14, 1990-United States Nuclear Regulatory Commission Document Control Desk Vashington, D. C. 20555  ;

Subject:

Response to NRC Bulletin No. 89-02 Regarding Potential Stress Corrosion Cracking of Internal Preloaded Bolting in Swing Check Valves and Justification for Alternate Inspection Schedule for One Valve Gentlemen The subject bulletin requested licensecs to disassemble and inspect all

• safety-related Anchor Darling Model S350V sving check valves supplied with internal retaining block studs of ASTM specification A193 Grade B6 Type 410SS.

The bulletin also requested licensees to review the design of other safety-related check valves to determine if similar designs and material selection to the Anchor Darling Madel S350V are used.

Toledo Edison's review determined that there are no Anchor Darling sving check valves installed in safety related applications. However, the review identified twelve (12) Velan valves of similar design. These valves are installed in the Component cooling Vater, Containment Ventilation and Service '

Vater Systems. An original procurement document review and a query to the valve vendor could not determine whether the bolting in question has a hardness of less than Rc26. Therefore, for (11) of the twelve (12) valves, Toledo Edison replaced the existing bolting during the ongoing sixth refueling outage with A193 B6 410SS bolting of a known hardness of less than Rc26, or replaced with a vendor approved alternative material, or removed their internals if the valves' functions vere not required. Visual inspections of the retaining block bolts removed identified no cracking. Non-destructive examinations were not performed since Toledo Edison does not plan to re-use

-the bolting material.

9006250051 900614 r PDR ADOCK 05000346 0 PDC /

f \ 0 THE TOLEDO EDISON COMPANY EDISON PLAZA 300 MADISON AVENUE TOLEDO. OHIO 48652

l Dockat Nu ber 50-346 l License Number NPF-3 Serial Number 1807 Page 2 Replacement of the bolting material in one (1) remaining sving check valve vill not be accomplished during the sixth refueling outage as originally planned. The inspection of CC-91, Component Cooling Vater (CCV) Auxiliaries to CCV Train 2 Return Header Swing Check Valve, required a plant lineup and system drain which would significantly impact the current outage schedule.

Therefore, the valve CC-91 bolting replacement and inspection vill be performed during the seventh refueling outage.

Inspection of this valve during the sixth refueling outage was not considered critical, since a modification to improve the design of the disc anti-rotation device was implemented during the last refueling outage which resulted in the valve being completely disassembled and inspected. No evidence of bolting degradation was identified at that time. Valve CC-91 is a " Ring" hanger bracket design valve rather than the " Retaining Block" hanger design of the Anchor Darling valves. A failure of one of the three bolts securing the hanger bracket ring would not impair the functionality of the valve to the same degree as a bolting failure in a two bolt hanger retaining block design valve. The bolts in question are lockvired from the bolt head to the retraining ring, which would retain any loose bolt parts that could cause binding of valve disc and impair its function vere a bolt to fail. Inspection of four similar valves of this type did not reveal any evidence of bolting failures.

Additionally, CC-91 was satisfactorily tested during the sixth refueling outage for reverse flow per the In-Service-Test (IST) Program and vill  ;

continue to be reverse flow tested on a cold shutdown frequency in accordance L vith the IST program. This testing vill identify any problems with the safety function of the valve.

Based on the above, deferral of the CC-91 inspection to the seventh refueling outage is justified.

If you have any questions concerning this matter, please contact Mr. R. V. Schrauder, Manager - Nuclear Licensing, at (419) 249-2366.

Very truly yours, A Q EBS/ eld Enclosure cet P. M. Byron, DB-1 NRC Senior Resident Inspector A. B. Davis, Regional Administrator, NRC Region III T. V. Vambach, DB-1 NRC Senior Project Manager

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Docket Number 50-346

. Licens] Number NPF-3 Seri

1 Number 1807 i L * '

Enclosure Page 2 l

1 Response to NRC Bulletin No. 89-02 For j Davis-Besse Nuclear Power Station 1 Unit No. 1 This letter is submitted in conformance with Atomic Energy Act of 1954 Section 182a as amended and 10CFR50.54(f), in response to NRC Bulletin 89-02 ,

(Log No. 1-2123), " Stress Corrosion Cracking of High-Hardness Type 410 '

Stainless Steel Internal Preloaded Bolting in Anchor Darling Model 5350V Sving Check Valves or Valves of Similar Design."

I By: V D. C. Shelton, Vice President, Nuclear Svorn and subscribed before me this 14th day of June, 1990, f

C Utll Notary Putflic, State of Ohio EVELYN L DRESS NOTARY PUBUC, STATE OF OHIO lh 003E.306pc hy26 W4 I

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