NRC-99-0092, Documents Util Request for Enforcement Discretion with Respect to Requirements of TS 3/4.6.1.8 Re Drywell & Suppression Chamber Purge Sys

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Documents Util Request for Enforcement Discretion with Respect to Requirements of TS 3/4.6.1.8 Re Drywell & Suppression Chamber Purge Sys
ML20212H428
Person / Time
Site: Fermi DTE Energy icon.png
Issue date: 09/24/1999
From: Gipson D
DETROIT EDISON CO.
To:
NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML20212H433 List:
References
CON-NRC-99-0092 NUDOCS 9910010126
Download: ML20212H428 (7)
v • d • e


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Doug!;,s R. Gipson Senior Vice President, Nuclear Generation Fermi 2 -

l 6400 North Dixie liwy, New}v>rt, Michigan 481f,6 Tel: 734.586.5201 Fax: 734.f>86.4172 Detroit Edison September 24,1999 NRC-99-0092 U. S. Nuclear Regulatory Commission Attention: Document Control Desk Washington D C 20555

References:

1) Fermi 2 NRC Docket No. 50-341 NRC License No. NPF-43 l
2) NRC Administrative Letter 95-05, Revision 2," Revisions to l Staff Guidance for Implementing NRC Policy on Notices of Enforcement Discretion" i

Subject:

Reauest for Enforcement Discretion The purpose of this letter is to document Detroit Edison's request for Enforcement Discretion with respect to the requirements of Technical Specification (TS) 3/4.6.1.8, Drywell and Suppression Chamber Purge System. This request was made verbally and discussed with NRC personnel during conference telephone calls on September 23,1999.

l On September 22,1999 it was discovered that the Nitrogen Inerting Drywell Air i Purge Inlet Supply Valve, T4893F601, exceeded the allowable leakage rate specified by Technical Specification Surveillance Requirement 4.6.1.8.2. This enforcement l discretion request involves an extension of Technical Specification 3.6.1.8, Action i "b" requirements for an inoperable drywell and suppression chamber purge system supply and/or exhaust isolation valve. The extension would be from 0145 hours0.00168 days <br />0.0403 hours <br />2.397487e-4 weeks <br />5.51725e-5 months <br /> on September 24,1999, when this action would require the plant to be in Hot Shutdown, until an exigent change to the Technical Specifications (to be submitted by ,

. September 25,1999) is approved and implemented. The additional time is necessary

. to obtain an Exigent Technical Specification and thus avoid a plant shutdown. Based on the infonnation provided in the conference calls on September 23,1999 and as documented in the enclosure to this letter, verbal approval of the Detroit Edison request was granted.

9910010126 990924

'PDR ADOCK0500g1 P

A 1r17 Energy Company

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USNRC NRC-99-0092 Page 2 The information included in the enclosure to this letter is provided consistent with the guidance in Section E of the enclosure to Reference 2.

1 If there are any questions, please contact Mr. Norman K. Peterson at (734) 586-4258.

Sincerely, e

Enclosure Attachment

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cc: J. E. Dyer -

l A. J. Kugler A. Vegel M. V. Yudasz, Jr.

NRC Resident Office Region III l

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Enclosure to NRC-99-0092 Page1

. . I Reauest For Enforcement Discretion- AdditionalInformation l

1. The Technical Specification or other license conditions that will be violated. I Technical Specification Limiting Condition for Operation (LCO) 3.6.1.8, Action (b) requires that with a drywell and suppression chamber purge system supply and/or j exhaust isolation valve (s) with resilient material seals having a measured leakage rate exceeding the limit of Specification 4.6.1.8.2, restore the inoperable valve (s) to

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OPERABLE status within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> or be in at least HOT SHUTDOWN within the next i 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> and in COLD SHUTDOWN within the following 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, i

2. The circumstances surrounding the situation, including root causes, the need for )

prompt action and identification of any relevant historical events.  !

The Drywell Air Purge penetration (X-26) has three isolation valves that are tested concurrently. The Inboard Isolation Valve (T4803F601, Butterfly,24 inch, Neles-Jamesbury,24-8222EX MOD. A) and Outboard Isolation Valves (T4800F407, Butterfly,24 inch, Neles-Jamesbury,24-8922EX MOD. A, and T4800F408, Butterfly, 10 inch, Neles-Jamesbury, 10-8926EX MOD. A) comprise the penetration's isolation.

The piping configuration is such that the T4800F407 is open directly to secondary containment on one side. This configuration lends itself to a direct visual inspection of the valve seat. T4800F408 connects to the nitrogen supply system. During leak testing, boundary valves are used to isolate T4800F408 from the nitgen system. A vent valve between T4800F408 and the test boundary valves is used to depress :rize and vent the piping outboard from T4800F408.

On September 22,1999, a Local Leak Rate Test (LLRT) was performed for penetrntion X-26 as required by Surveillance Requirement 4.6.1.8.2. This test is performed by pressurizing between the inboard and outboard isolation valves and measuring the total leakage of the isolation valves. The penantion exceeded its Technical Specification limit ofless than 0.05 L,(14.87 Standaro Cubic Feet per Hour (SCFH)). The penetration leaked at a rate of 26.7 SCFH. E; sed on direct observation of the T4800F407 and observation of an open % inch vent connection outboard of the T4800F408, test personnel determined that the penetration failed its LLRT due to seat leakage throQ T4803F601. Subsequently, valve T4803F601 was stroked under light pressure in an attempt to clear the sealing surfaces of any debris. The LLRT was performed again, and the leakage from penetration X-26 increased to 82.85 SCFH.

Since the only evolution performed between the two LLRTs was the stroking of T4803F601, this subsequent LLRT further substantiated that the leakage is attributable to T4803F601. Visual and audio inspection (utili7ing Snoop to aid in leak detection) for leakage at the exposed side of T4800F407 and s the vent connection outboard of T4800F408 by a Level II VT Inspector during both tests on September 22,1999

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Enclosure to NRC-99-0092 Page 2 revealed insignificant leakage relative to the measured leakage rates. A Level III VT Inspector confirmed the initial visual inspection and confirmed that T4800F407 and T4800F408 were an insignificant contributor to the leakage during the second test. A 1 leak detection aid (Snoop) was utilized to aid in leak detection during both tests. Snoop was applied to the seal of T4800F407 and minor bubbling was observed; it was also used at the vent connection outboard of T4800F408 and no leakage was detected through this valve. This substantiated the assessment that the outboard isolation valves are tight.

Review of the LLRT and maintenance records does not indicate an adverse trend for this penetration. Results of previous tests indicate that the penetration leakage has been  ;

between approximately 0.6 SCFH and 1.75 SCFH since October of 1998 (four tests).

Failure of T4803F601 was not anticipated; and based on the magnitude of the leak and the change in leakage following valve stroke, the likely cause of the leakage is failure of the seal. The seal was replaced durit.g the Sixth Refueling Outage (autumn of 1998).

Based on the extremely good test results from the previous tests, it is highly unlikely that the cause of this test failure is attributable to any valve other than the T4803F601.

The overall primary containment leakage allowed by Technical Specification is 0.6 L,.

This equates to 178 SCFH. The known leakage from containment prior to September 22,1999 was 67.28 SCFH, leaving a margin of 110.72 SCFH. The leakage from penetration X-26 is 82.85 SCFH leaving a margin of 27.87 SCFH, when considering the T4803F601 as a single boundary valve (i.e., not crediting the outboard valves). The outboard valves will serve to significantly increase this margin, even though leakage .l was not quantifiable. I

3. The safety basis for the request, including an evaluation of the safety significance and potential consequences of the proposed course of action. This evaluation should include at least a qualitative risk assessment derived from the licensee's PRA.

The safety basis for this request is the action to isolate the affected penetration using outboard isolation valves T4800F407 and T4800F408. While leak rate testing for this penetration can not quantify the leakage of the outboard valves individually, the leakage rate through these isolation devices is believed to be well below the acceptance criteria, as discussed in the preceding section. The compensatory action to verify the penetration is isolated on a periodic basis supports the safety function of the valves to isolate following an accident. Reliability of the resilient seals in these valves and the other similar penetrations at Fermi 2 has been high, providing confidence that unexpected degradation is not occurring in these valves. ,

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2nclosure to NRC-99-0092 Page 3 The T4803F601 is not a risk significant component in the Level 1 Fermi 2 PSA. The T4803F601 is not an initiator of an event that leads to core damage and does not prevent a core damage event. The T4803F601 has no effect on core damage and is not modeled in the Level 1 Fermi 2 PSA.

The T4803F601 is a credited component of the Level 2 Fermi 2 PSA. The T4803F601 or the other in line isolation valves must close to isolate penetration X-26. The success criterion is that either inboard or outboard isolation valves in a line must close and remain closed for 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. With the penetration isolated by the outboard isolation valves, failure of the T4803F601 has no effect on the Level 2 PSA results and the success criteria for penetration X-26 is met. Therefore failure of the T4803F601 is not risk significant.

4. The basis for the licensee's conclusion that the noncompliance will not be of potential detriment to the public health and safety and that neither an unreviewed safety question nor a significant hazard consideration is involved.

Total combined primary containment leakage allowed by Technical Specification 3.6.1.2 b. is 0.60 L,or 178 SCFH. As discussed previously, the actual combined primary containment leakage, including T4803F601, is approximatelyl50 SCFH, taking no credit for the outboard isolation valves in this penetration.

In addition, with the penetration X-26 outboard valves closed, it is believed that leakage ;

for this penetration remains well within the 0.05 L, limit associated with this Technical l Specification. The proposed remedial actions are also similar to actions that would be required by Fermi 2 (proposed) Improved Technical Specifications for restoring the flow path leakage.

5. The basis for the licensee's conclusion that the noncompliance will not involve adverse consequences to the environment.

As discussed above, the proposal involves no significant hazard consideration. The proposal will not change the types or amounts of effluents that may be released offsite, nor increases individual or cumulative occupational radiation exposures, since the proposal essentiaily maintains the overall leakage of the penetration within the required limits.

6. Any proposed compensatory measure (s).

The T4800F407 and T4800F408 isolation valves are normally closed isolation valves that will be closed and deactivated assuring the valves remain closed until the

1 Enclosure to NRC-99-0092 Page 4 T4803F601 is repaired. They will be verified closed every 31 days. T4800F407 and .

T4800F408 will not be cycled until the plant is shutdown to repair the T4803F601. l Because the leakage through the outboard isolation valves cannot be individually quantified, a flanged cover will be installed over the opening of T4800F407 by September 28,1999 to provide an additional leakage barrier. This flange will remain in place until the plant is shutdown to correct the penetration leakage. Leak testing of this penetration will be performed at least every 45 days to verify that the 0.6 L, is not exceeded due to additional penetration leakage. This testing will niso qualitatively verify the integrity of the outboard isolation barriers (employing the visual and audio inspection techniques and Snoop similar to techniques used on September 22,1999, as described above).

7. The justification for the duration of the noncompliance.

The time requested will allow time to obtain an Exigent Technical Specification change.

Detroit Edison expects this amendment request will be submitted by September 25, 1999. The NRC approval of the Technical Specification Amendment may take as long as four weeks. The compensatory measures discussed above are being implemented.

The actions are equivalent to what will be approved in the Technical Specification Amendment.

8. A statement that the request has been approved by the facility organization that normally reviews safety issues (Plant Onsite Review Committee, or its equivalent).

1 This request has been reviewed and approved by the Fermi 2 On Site Review l Organization (OSRO).

9. The request must specifically address how one of the NOED criteria for i approc,riate plant conditions specified in Section B is satisfied.

Criterion 1 (a) of Section B is applicable to this request. This criterion states in part:

"1. For an operating plant, the NOED is intended to (a) avoid undesirable transients as a result of forcing compliance with the license condition and, thus l minimize potential safety consequences and operational risks..." i In this case, Fermi 2 is operating and unless this request is granted would be required to shutdown. Assuming a required plant shutdown carries the same risk as a given inadvertent scram, the shutdown activity increases core damage risk potential compared  ;

to continued plant operation with T4803F601 leaking. I l

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Enclosure to NRC-99-0092 Page 5 Thus, this situation meets a criterion given in Section B of the NRC Guidance for Issuance of Enforcement Discretion.

10. If a follow-up license amendment is required, the NOED request must include marked-up Technical Specification pages showing the proposed Technical Specification changes. The actuallicense amendment request must follow within 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br />.

Enclosure 1 includes a marked-up version of the current Technical Specification pages.

11. A statement that prior adoption 01 approved line-item improvements to the Technical Specifications or the Improved Technical Specifications would not have obviated the need for the NOED request.

Detroit Edison submitted Improved Technical Specifications in April 1998. The NRC is expected to approve the submittal in September 1999. However, Improved Technical Specifications does not fully obviate the need for this NOED request. l

12. Any other information the NRC staff deems necessary before making a decision to exercise enforcement discretion.

All NRC comments and requests for information have been incorporated into Items 1 through 11 above.

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