ML20046D409
| ML20046D409 | |
| Person / Time | |
|---|---|
| Site: | Nine Mile Point  |
| Issue date: | 08/05/1993 |
| From: | Sylvia B NIAGARA MOHAWK POWER CORP. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NMP2L-1399, NUDOCS 9308190209 | |
| Download: ML20046D409 (8) | |
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i M V NIAGARA RUMOHAWK NIAGARA MOHAWK POWER CORPORATION /N!NE MILE POINT, PO. BOX 63, LYCOMING, NY 13093/ TELEPHONE (315) 349-2882 B. Ralph Sylvia i
Executive %ce President Nuclear August 5,1993 NMP2L 1399 U.S. Nuclear Regulatory Commission Attn: Document Control Desk l
Washington, D.C. 20555 I
RE:
Nine Mile Point Unit 2 Docket No. 50-410 i
NPF-69 l
Gentlemen:
1 The purpose of this letter is to request enforcement discretion to provide relief from the requirements of Nine Mile Point Unit 2 Technical Specification Limiting Condition for Operation (LCO) 3.6.3, i
Primary Containment Isolation Valves, ACTION a.2 for Hydrogen Recombiner System inboard 4
valves 2HCS*MOV 4A,B and 6A,B..This ACTION states that with one or more of the primary containment isolation valves inoperable, maintain at least one isolation valve OPERABLE in each affected penetration that is open and within 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> isolate each affected penetration by the use of at least one deactivated automatic valve secured in the isolated position or be in at least hot shutdown within the next 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />.
At 1615 hours0.0187 days <br />0.449 hours <br />0.00267 weeks <br />6.145075e-4 months <br /> on August 4,1993, valves 2HCS*MOV 4A,B and 6A,B were declarad inoperable, l
requiring entry into LCO 3.6.3, ACTION a.2. The appropriate valves to fulfill the operability i
requirements for this action are 2HCS*MOV 1 A,B and 3A,B. As a result of a Niagara Mohawk l
audit of the 10CFR50 Appendix J program, it was determined that inboard isolation valves 2HCS*MOV 4A,B and 6A,B were tested in the reverse direction instead of between the seats, which i
is the appropriate test method for these valves.
These inboerd isolation valves, which are located inside primary containment, cannot be leak tested as required during power operation, and deactivating the outboard OPERABLE valves in accordance with ACTION a.2 would render the hydrogen recombiners inoperable. Niagara Mohawk is evaluating a design change which will permit restoration of containment integrity based on the operable outboard valves and the closed system features of the Hydrogen Recombiner System.
Enforcement discretion is therefore requested to allow continued operation until an Emergency i
Technical Specification amendment request can be submitted and reviewed by the Nuclear Regulatory Commission or until the above evaluation can be completed. Therefore, Niagara Mohawk Power Corporation i3 requesting written approval of the enforcement discretion which was granted at 2204 p.m. on August 4,1993.
The following are included in the Attachment to this letter:
l 1).
A discussion of11' squirements for which the enforcement discretion is requested.
2)
A discussion of the circumttances surrounding the situation including the need for prompt
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action, and a description of why the situation could not have been avoided.
3)
Discussion of compensatory actions.
9308190209 930805 T
PDR ADOCK 05000410 h 90 j
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4)
A preliminary evaluation of the safety signincance and potential consequences of the proposed request.
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5)
A discussion justifying the duration of the request.
6)
' Die basis for the conclusion that the request does not involve a significant hazards consideration.
7)
The basis for the conclusion that the request does not involve irreversible environmental consequences.
The Nine Mile Point Unit 2 Station Operations Review Committee (SORC) has reviewed and approved the contents of this request for enforcement discretion.
Very truly yours, fks lA B. Ralph Sylvia Exec. Vice President - Nuclear MGM/Imc xc:
Regional Administrator, Region I Mr. W. L. Schmidt, Senior Resident Inspector Mr. R. A. Capra, Project Directorate No.1-1, NRR 3
Mr. J. E. Menning, Project Manager, NRR Mr. L. E. Nicholson, Chief, Reactor Projects, Section IB
-l Ms. Donna Ross Division of Policy Analysis and Planning i
New York State Energy Of6ce Agency Building 2 Empire State Plaza l
Albany, NY 12223 Records Management i
4 l
UNITED STATES OF AMERICA NUCLEAR REGULATORY COMM!SSION In the Matter of
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Niagara Mohawk Power Corporation
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Docket No. 50-410
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Nine Mile Point Nuclear Station Unit No. 2
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B. Ralph Sylvia, being duly sworn, states that he is Executive Vice President-Nuclear of Niagara Mohawk Power Corporation; that he is authorized on the part of said Corporation to sign and file with the Nuclear Regulatory Commission the documents attached bereto; and that all such documents are true and correct to the best of his knowledge, information, and belief.
NIAGARA MOHAWK POWER CORPORATION By
[d/M Il B. Ralph' Sylvia /
Executive Vice President-Nuclear Subscribed and sworn to before rne on I
this[1t day of M
,1993.
~I. 0 NOTA Y'PUBLIC
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ATTACHMENT P
1)
A DISCUSSION OF TIIE REQUIREMENTS FOR WHICH THE ENFORCEMENT DISCRETION IS REQUESTED l
i The proposed enforcement discretion would permit continued operation with inoperable inboard containment isolation valves on penetrations with closed, but not deactivated, OPERABLE outboard automatic isolation valves. With a primary containment valve inoperable, Action a.2 of Limiting Condition for Operation (LCO).
3.6.3 requires maintaining one isolation valve OPERABLE in each affected penetration and isolating each affected penetration within 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> by at least one deactivated automatic valve secured in the isolated position or being in at least hot shutdown within the next 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />. Containment isolation valves 2HCS*MOV4A&B and MOV6A&B were declared inoperable at 1615 hours0.0187 days <br />0.449 hours <br />0.00267 weeks <br />6.145075e-4 months <br /> on August 4,1993. The enforcement discretion is requested for Action a.2 as it applies to deactivating the closed OPERABLE automatic isolation valves on the same penetrations, 2HCS*MOVI A&B and 3A&B. The requested duration of this enforcement discretion -
is from 2204 hours0.0255 days <br />0.612 hours <br />0.00364 weeks <br />8.38622e-4 months <br />, August 4,1993, until such time as an emergency technical l
e specification change can be processed or until a change to the design basis for the affected penetrations can be properly evaluated and approved.
2)
A DISCUSSION OF THE CIRCUMSTANCES SURROUNDING THE SITUATION INCLUDING THE NEED FOR PROMPT ACTION, AND A i
DESCRII'rION OF WHY THE SITUATION COULD NOT HAVE BEEN -
AVOIDED Nine Mile Point Unit 2 was originally designed and constructed using globe valves for rentainment isolation on the hydrogen recombiner suction and discharge lines (Penetrations Z-55A&B, Z-56A&B and Z-57A&B). In a letter dated December 7, 1984, Niagara Mohawk provided justification to the Commission for reverse direction i
testing of the inboard containment isolation. valves in the hydrogen recombiner systems. Reverse testing of these valves is discussed in Section 6.2.6 of SSER 3, dated July 1986. Table 6.6 in SSER 3 lists valves 2HCS*MOV4A&B, MOV5A&B
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and MOV6A&B as globe valves and provides the justification that LLRT pressure 2
will tend to unseat the valve while LOCA pressure will tend to seat the valves (Note 2 1
on Table 6.6). In October of 1986,2HCS*MOV4A&B and MOV6A&B were changed from globe valves to flexible wedge gate valves. The design change l
correctly noted that the testing methodology should be changed from that described in Note 2 (in the reverse direction under the seat) to the methodology described in Note 1 of SER Table 6.6 (pressurize through the test connection between the seats).
Preoperational testing was successfully conducted after the modification by pressurizing between the seats. However, during subsequent periodic tests the Appendix J surveillance procedure incorrectly tested the valves by pressurizing between the two isolation valves in each penetration. This testing methodology results in a nonconservative test for the flexible wedge gate valves.
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In November and December of 1992, an audit of Niagara Mohawk's 10 CFR 50 Appendix J program was conducted by an outside consultant. The audit identified a range of issues requiring evaluation and/or corrective action. One of the audit items questioned the current testing methodology for 2HCS*MOV4A, MOV4B, MOV6A and MOV6B. Niagara Mohawk performed a preliminary review of the audit items when they were received from the contractor and determined that no immediate action was required. However, upon final review of the audit item on the recombiner
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valves, Niagara Mohawk determined the test method currently specified for the four l
recombiner valves was incorrect. Since the valves are located inside containment and testing during power operation is not practical, the valves were declared inoperable and Action a.2 of LCO 3.6.3 was entered at 1615 hours0.0187 days <br />0.449 hours <br />0.00267 weeks <br />6.145075e-4 months <br /> on August 4,1993.
Action a.2 of Limiting Condition for Operation 3.6.3 requires maintaining one isolation valve OPERABLE in each affected penetration and isolating each affected penetration within 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> by at least one deactivated automatic valve secured in the isolated position or being in at least hot shutdown within the next 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />.
Deactivating normally closed outboard isolation valves 2HCS*MOVIA&B and MOV3A&B would render the hydrogen recombiners inoperable. Therefore, upon declaring the valves inoperable, Niagara Mohawk initiated several actions in an attempt to avoid a forced shutdown. An evaluation of the feasibility of restoring the hydrogen recombiners post-LOCA with deactivated isolation valves was initiated.
Engineering also began evaluating a design change that would revise the design basis for the penetrations in question from two automatic valves in series to one automatic isolation valve and a closed system outside primary containment. This change would restore contair ment integrity by taking credit for closed systems outside of containment and one OPERABLE containment isolation valve in each penetration.
However, neither evaluation was completed in time and the shutdown requirements of LCO 3.6.3, Action a, were entered, and an unusual event declared, at 2015 hours0.0233 days <br />0.56 hours <br />0.00333 weeks <br />7.667075e-4 months <br /> on August 4,1993.
3)
DISCUSSION OF COMPENSATORY ACTIONS Isolation valves 2HCS*MOVI A&B and 3A&B are normally closed and administrative controls will be established to maintain them in that position. The control switches for the subject isolation valves, 2HCS*MOVI A&B and 3A&B, are spring return to i
normal. Therefore, they have no pull-to-lock position. As an alternative compensatory measure, Niagara Mohawk will place hold out tags on the control switches in the control room to prevent inadvertent opening of the valves. To assure adequate administrative control of the valves, procedure changes have been made to the system operating instruction regarding the clearing of hold out tags. Shift operators were briefed by the Operations Manager on these compensatory actions prior to exiting the shutdown LCO and subsequent shifts have been or will be briefed prior to assuming shift duties. In addition, the content of the Operations Manager's briefings will be incorporated into written Shift Supervisor's instructions. Guidance has been provided to the operators to instruct them to verify the valves remain closed post-LOCA until such time as the hydrogen recombiners are placed in service.
i Finally, the leak testing methodology and test results for isolation valves 2HVA*MOVI A&B and 3A&B were reviewed to assure adequate isolation capability.
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A PRELLMINARY EVALUATION OF THE SAFETY SIGNIFICANCE AND POTENTIAL CONSEQUENCES OF THE PROPOSED REQUEST Penetrations Z-55A&B and Z-56A&B are designed in accordance with GDC 56 with two automatic isolation valves. Section 6.2.4 of NUREG 0800 discusses the acceptability of a single isolation valve for systems that are closed outside of containment. NMP2 Updated Safety Analysis Report Section 6.2.5.2 discusses the design of the hydrogen recombiner system as it pertains to the closed loop design i
addressed in Section 6.2.4 of NUREG 0800. The USAR states that the system is considered an extension of containment and meets the following criteria of Standard Review Plan 6.2.4 for closed loop systems:
1)
Containment atmosphere does not directly communicate with the environment following a LOCA 2)
The system is designed in accordance with Quality Group B standards (i.e.,
Class 2) 3)
The system meets Category I design requirements 4)
The system is designed to primary containment pressure 5)
The system is designed for protection against pipe whip, missiles, and jet l
forces 6)
The system is tested for leakage The integrity of the closed system is assured by the leak testing required by Surveillance Requirement (SR) 4.6.6.1.c. The SR requires that the recombiner system be included in the containment integrated leak rate test or the system be tested separately at Pa and its leak rate test added to the integrated test results. This assures testing is accomplished at least once every 40i10 months. In addition, the system is leak tested to the same criteria when system integrity is breached for maintenance or testing. Tnermocouples on both systems were recently calibrated and consequently j
leakage testing for both recombiner systems was performed. The most recent testing was completed on July 4,1993 and July 15, 1993, for Divisions I and II, respectively, and the measured leakage was 0.257 SCFH and 0.651 SCFH, i
respectively. These results compare favorably with the overall containment leakage of 251 SCFH, or.305La, determined during the most recent integrated leak test completed on January 1,1991. The test results demonstrate that containment leakage will continue to be maintained as a small fraction of the design limit, I a. Therefore,
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primary containment integrity is assured since the outboard containment isolation valve is OPERABLE and the recombiner system is a closed system outside containment.
Although four of the isolation valves on the recombiner system are inoperable, they do not impact the operability of the recombiner systems. The inoperability applies only to their containment function. They still retain their ability to open and establish a post-LOCA flow path for the recombir.ers. Thus, the valves are still " OPERABLE" 0042120 0 Page 3 of 5
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for the purpose of supporting the hydrogen recombiners. Consequently, the safety
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related functions of containment and the hydrogen recombiners following a design basis LOCA are minimally affected and any adverse consequences associated with the proposed request are negligible.
5)
A DISCUSSION JUSTIFYING TIIE DURATION OF TIIE REQUEST Niagara Mohawk is requesting that this enforcement discretion be granted from 2204 hours0.0255 days <br />0.612 hours <br />0.00364 weeks <br />8.38622e-4 months <br />, August 4,1993, until such time as an emergency technical specification change can be processed or until such time as a change to the design basis for the affected penetrations can be properly evaluated and approved. During this period of time, Niagara Mohawk will continue its evaluation of design alternatives and expedite preparation and review of an emergency technical specification change request. We will submit the request for an emergency technical specification change within three working days after receiving written approval of this request for enforcement
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discretion. Niagara Mohawk is aggressively pursuing completion of its evaluation and anticipates completion of the evaluation prior to submittal of an emergency technical specification change request. Should Niagara Mohawk complete its design evaluation and resolve the issue through that mechanism, we will notify the Staffin writing and submit a summary of the design evaluation.
6)
TIIE BASIS FOR TIIE CONCLUSION TIIAT TIIE REQUEST DOES NOT l
INVOLVE A SIGNIFICANT IIAZARDS CONSIDERATION The operation of Nine Mile Point Unit 2, in accordance with the proposed enforcement discretion, will not involve a significant increase in the probability or l
consequences of an accident previously evaluated.
4 The proposed enforcement discretion does not involve a signincant increase in the probability or consequences of an accident previously evaluated. The probability of i
an accident previously evaluated will not significantly increase since the inoperability 3
of the containment isolation system is not an initiating event or precursor to any previously evaluated accident. SRP 6.2.4 states that one automatic isolation valve in combination with a closed system outside containment provides an acceptable alternative to the requirements of GDC 56. Containment integrity is assured since the recombiner systems are leak tested and designed as closed systems outside comainment and the outboard isolation valves on the subject penetrations remain OPERABLE. In addition, the availability of the hydrogen recombiners is not adversely impacted since the ability of the isolation valves to open is not adversely impacted. Therefore, the consequences of an accident previously evaluated will not signiGcantly increase.
The operation of Nine Mile Point Unit 2, in accordance with the proposed enforcement discretion, will not create the possibility of a new or different kind of accident from any previously evaluated.
i The proposed enforcement discretion does not create the possibility of a new or different kind of accident from any accident previously evaluated since operability of 004212G0 Page 4 of 5 i
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>a-the hydrogen recombiners is maintained such that hydrogen recombiners will be started in a time frame consistent with the USAR accident analyses.
The operation of Nine Mile Point Unit 2, in accordance with the proposed enforcement discretion, will not involve a significant reduction is a margin of safety.
Reliance on a closed system outside containment, in conjunction with one OPERABLE automatic isolation valve, provides adequate assurance of containment integrity. This alternative results in no significant reduction in containment reliability. The availability of the hydrogen recombiners in assured since the ability of the containment isolation valves to open is not adversely impacted by this enforcement discretion. Therefore, there is no significant reduction in margin of safety.
7)
TIIE BASIS FOR TIIE CONCLUSION TIIAT TIIE REQUEST DOES NOT INVOLVE IRREVERSIBLE ENVIRONMENTAL CONSEQUENCES l
This request involves enforcement discretion from the action requirements for an inoperable containment isolation valve. This change involves no significant increase in the amounts or types of any effluents that may be released offsite, and there is no significant increase in individual or cumulative occupational radiation exposure. The
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requested temporary enforcement discretion does not physically modify the plant, increase the plant's licensed power level or involve irreversible environmental consequences.
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