JPN-96-034, Informs NRC of Util Decision to Reclassify Recirculation Pump mini-purge Sys as Essential Sys & of Plans to Modify Containment Isolation Design for Sys to Configuration Similar to Original Plant Design
| ML20115H260 | |
| Person / Time | |
|---|---|
| Site: | FitzPatrick  |
| Issue date: | 07/18/1996 |
| From: | William Cahill POWER AUTHORITY OF THE STATE OF NEW YORK (NEW YORK |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| RTR-NUREG-0737, RTR-NUREG-737, TASK-2.E.4.2, TASK-TM JPN-96-034, JPN-96-34, NUDOCS 9607230009 | |
| Download: ML20115H260 (6) | |
Text
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123 Main Street Whde Plains. New York 10601 914 681-6840 914 267-3309 (rAX)
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July 18,1996 JPN-96-034 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Mail Station P1-137 Washington, DC 20555
Subject:
James A. FitzPMrick Nuclear Power Plant Docket No. 50-333 Change in Commitment to NUREG-0737, item II.E.4.2 Containment isolation Dependahlhty
References:
See below.
Dear Sir:
The purpose of this letter is to inform the NRC of the Authority's decision to reclassify the recirculation pump mini-purge system as an " essential" system, and of the plans to modify the containment isolation design for this system to a configuration similar to the original plant design. The Authority modified the original design based on the containment isolation dependability review requested in NUREG-0737. TMI Lessons Leamed (Reference 1).
In response to NUREG-0737, item II.E.4.2 (References 2 and 3), the Authority defined i
the recirculation pump mini-purge lines as a "non-essential" system, and proposed to l
replace the outboard containment isolation valves (simple check valves) with an automatic solenoid operated valve with diverse actuation signals (the inboard l
containment isolation valves remain simple check valves). This modification was intended to meet NUREG-0737, item II.E.4.2, Position 3, which states that all non-essential systems shall be automatic &lly isolated by the containment isolation signal.
NRC acceptance of the Authority's implementation of NUREG-0737, item II.E.4.2, is documented in References 4 and 5 (while these references approved the proposed modification, the text does not correctly describe which check valves were to be replaced with solenoid operated valves).
The Authority has re-evaluated the classification of this system, and has determined that h
the recirculation pump mini-purge lines are an " essential" system. This is based 9
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4 on the necessity to maintain seal cooling to the recirculation pump seals. The original General Electric (GE) design of simple check valves provided control rod drive (CRD) water to the recirculation pumps whenever the CRD system is operating. The Authority plans to restore the containment isolation design for the recirculation mini-purge line to the original GE design by replacing the outboard automatic solenoid operated valves with simple check valves. The Authority has completed a 10CFR 50.59 evaluation and has determined this check valve design conforms to NUREG-0737, item II.E.4.2 acceptance criteria, and meets the intent of General Design Criteria 55 on some other defined basis as described in Attachment 1.
Any questions regarding this letter may be addressed to Mr. A. Zaremba, Licensing Manager, at (315) 349-6365.
Very truly yours, William J. Cahill, Jr.
Chief Nuclear Officer Attachments: as stated
References:
1.
NRC Letter, D. G. Eisenhut to All Licensees of Operating Plants, dated October 31,1980 2.
NYPA Letter, J. P. Bayne to T.A. Ippolito (JPN-82-5), " Containment isolation Dependability, NUREG-0737, item ll.E.4.2," dated January 7,1982
- 3.
NYPA Letter, J. C. Brons to NRC, " Proposed Changes to the Technical Specifications Regarding Containment isolation Valves (JPTS-86-017)," dated December 19,1986 4.
NRC Letter, D. E. Lebarge to J. C. Brons, " Containment isolation Dependability, NUREG-0737, item II.E.4.2, Positions 1 through 4, for the James A. FitzPatrick Nuclear Power Plant," dated February 14,1991 5.
NRC Letter, H.1. Abelson to J. C. Brons, Amendment 108 to Facility Operating License DPR-59, dated April 3,1987 cc: Next page l
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cc:
Regional Administrator U.S. Nuclear Regulatory Commission 475 Allendale Road i
King of Prussia, PA 19406 Office of the Resident inspector U.S. Nuclear Regulatory Commission i
P. O. Box 136 j
Lycoming, NY 130'<3 i
Ms. Karen Cottor.
Acting Project Directorate I-1 l
Division of Reactor Projects 1/11 U.S. Nuclear Regulatory Commission Washington, DC 20555 i
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) to JPN-96-033 Delermination_of Recirculation Pump Mini-Purge as an EssentiaLSy. stem and Justification that the ProposesLDesign Meets the intent of GDD_55 on "some other Defined Basis" PURPOSE The Authority plans to replace the outboard containment isolation solenoid operated valves (02-SOV-001 and -002) with simple check valves on the mini-purge lines to each of the two recirculation pumps. The reason for this replacement is that the use of automatic isolation valves in these particular lines is not advisable since it may result in damage to the recirculation pump seals whenever the valves isolate with the recirculation pumps operating. In addition, the solencid valves have demonstrated an inconsistent local leak rate test (LLRT) performance while the simple check valves have demonstrated an acceptable LLRT performance history.
REVIEW AND ANALYSIS The control rod hydraulic (CRD) system supplies water to the recirculation system for purging of the pump seals. This water cleans and cools the seal area to ensure proper operation during normal plant conditions. Continued recirculation pump seal purge prevents premature aging and possible damage to the pump seals from high temperature. Failure of the seals may result in unacceptable primcry coolant system leakage. Automatic isolation of these essential lines is not a desirable practice.
Automatic isolation of these essential lines may result from valid or invalid primary containmerit isolation signals, loss of power, valve failure, and system testing. The original GE design of simple check valves provided CRD water to the seats whenever the CRD system is operating. This isolation arrangement is similar to the arrangements at other BWR plants.
Since the Authority classified the recirculation pump mini-purge system as a "non-essential" system and modified the valves in response to NUREG 0737, item II.E.4.2, this particular application of automatic isolation valves has proven to be an inadequate design resulting in poor local leakage rate testing history for the valves, and accelerated recirculation pump seal degradation due in part to loss of recirculation seal cooling water events.
Essential systems include those systems that could aid in mitigating the consequences of a postulated accident. The Authority has determined that the recirculation pump mini-purge line is required for proper seal operation necessary to maintaining primary system integrity, and is considered an " essential" supply to the reactor coolant recirculation seals from the CRD system. The check valves assure a more reliable flow of coolant to the seals during a plant containment isolation condition. The following additional facts support the basis that check valves in this particular application is a more desirable 1
, to JPN-96-034 approach and meets the intent of GDC 55 on "some other defined basis,"
a.
The proposed design of the recirculation pump mini-purge lines,3/4 inch lines with two 3/4 inch simple check valves in series with a reducing orifice, is similar in size to a typical instrument line. The containment isolation feature planned for the mini-purge lines is more conservative than the criteria specified for instrument lines in ANS-56.2, section 3.6.2.
b.
The evaluation of the CRD system containment isolation valves for NUREG- 0737, item II.E.4.2, (Reference 2), determined:
"The primary function of the CRD System is to shut down the reactor upon receipt of a signal from the Reactor Protection System. However, the CRD system has the capability... to provide cooling water to the reactor vessel. Based on this established capability, automatic isolation of the CRD system is undesirable and it has been designated as essential." The source of water supplied to the recirculation pump mini-purge lines is the CRD system.
c.
The recirculation pump mini-purge system piping meets seismic Category I design requirements, and the system is continually pressurized to reactor pressure, therefore, system integrity is demonstrated during normal plant eperation.
d.
The inboard isolation piston check valves, similar to the check valves planned for the outboard isolation valves, have experienced a much better local leak rate test (LLRT) performance history, compared to the current j
solenoid valves. Based on historical LLRT test data, the check valves are j
expected to provide a 50 percent increase in satisfactory LLRT tests in i
the outside containment location. Furthermore, the new piston check valves will continue to be subject to Type C leak testing.
CONCLUSION Operation of the 3/4 inch recirculation pump seal purge line is desirable during recirculation pump operation, including conditions when containment isolation is required. The use of automatic power operated isolation valves on this system represents an inappropriate design. Accordingly, the design will be modified to use two simple check valves in series, thereby enhancing the reliability of the seal purge function. In addition, the new check valve design (same model and size) has had good success at satisfactoril/ passing LLRT testing in the inboard location (same line).
Replacing the poor LLRT performing solenoid valve with this check valve in the outboard location improves coruainment isolation dependability.
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. to JPN-96-034 The Authority concludes that the benefits gained by providing simple check valves as originally designed will enhance system operation since the check valves provide a more reliable flow of coolant to the seals in a plant condition requiring containment isolation.
Since availability of the recirculation pump mini-purge weier is necessary to protect the l
seals, the Authority has reclassified the system as " essential", and plans to retum the l
system isolation valves back to simple check valves as originally designed. The change l
l is a more desirable approach and meets the intent of GDC 55 on another defined basis.
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REFERENCES l
1.
NRC Letter, D. G. Eisenhut to All Ucensees of Operating Plants, dated October 31,1980 l
2.
NYPA Letter, J. P. Bayne to T.A. Ippolito (JPN-82-5), " Containment isolation Dependability, NUREG-0737, item II.E.4.2," dated January 7,1982 l
l 3.
NYPA Letter, J. C. Brons to NRC, " Proposed Changes to the Technical Specifications Regarding Containment Isolation Valves (JPTS-86-017)," dated j
l December 19,1986 i
4.
NRC Letter, D. E. Lebarge to J. C. Brons, " Containment ! solation Dependability, i
NUREG-0737, item ll.E.4.2, Positions 1 through 4, for the James A. FitzPatrick Nuclear Power Plant," dated February 14,1991 j
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5.
NRC Letter, H.1. Abelson to J. C. Brons, Amendment 108 to Facility Operating i
License DPR-59, dated April 3,1987 i
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