ML20073A440

Responds to GL 94-02, Long Term Solutions & Upgrade of Interim Operating Recommendations for Thermal Hydraulic Instabilities on Boiling Water Reactors

ML20073A440
Person / Time
Site:	Peach Bottom, Limerick
Issue date:	09/09/1994
From:	Hunger G PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
GL-94-02, GL-94-2, GNL-94-02, GNL-94-2, NUDOCS 9409200265
Download: ML20073A440 (8)

Text

St: tion cup' ort Dipartmsnt GNL 94-02 x

PECO ENERGY

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Wayne, PA 19087 5691 September 9,1994 Docket Nos: 50-277 50-278 50-3'i2 50-353 License Nos. DPR-44 DPR-56 NPF-39 NPF-85 U. S. Nuclear flegulatory Commission Attention: Document Control Desk Washington, DC 20555

Subject:

Peach Bottom Atomic Power Station, Units 2 and 3 Limerick Generating Station, Units 1 and 2 Response to NRC Generic Letter 94-02, "Long Term Solutions and Upgrade of interim Operating Re'.:ommendations For Thermal Hydraulic Instabilities in Boiling Wrer Reactors."

References:

1)

Letter from A. Thadani (NRC) to L A. England (BWROG), " Acceptance for Referencing of Topical Reports NEDO-31960 and NEDO-31960 Supplement 1, BWR Owners' Group Long Term Stability Solutions Licensing Methodology"; July 12,1993 2)

Letter from L..A. England to M. J. Virgilio, "BWR Owners' Group Guidelines for Stabliity Interim Corrective Action"; June 6,1994 3)

Letter from L A. England to M. J. Virgilio, "BWR Owners' Group Improved Guidelines for Stablilty Interim Corrective Action"; April 4,1994

Dear Sirs:

The attachments to this letter provide PECO Energy Company's (PECO Energy) response to Generic Letter 94-02, "Long Term Solutions and Upgrade of Interim Operating Recommendations for Thermal Hydraulic Instabilities on Bolling Water Reactors," for Peach Bottom Atomic Power Station (PBAPS),

Units 2 and 3 and Limerick Generating Station (LGS), Units 1 and 2.

As requested in Generic Letter 94-02, this response is being submitted under oath or affirmation. If you have any questions regarding this response, please feel free to contact us.

Very truly yours, L/1. d. O G. A. Hunger, Jr. g Director - Ucensing Attachments cc:

T. T. Martin, Administrator, Region I, USNRC f

N. S. Perry, Resident inspector, LGS W. L Schmidt, Senior Resident inspector, PBAPS

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R. R. Janati, Commonwealth of Pennsylvania qi 9409200265 940909 PDR ADDCK 05000277 P

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'i D. M. Smith, being first duly swom, deposes and says:

t That he is Senior Vice President and Chief Nuclear Officer of PECO Energy Company; the l

Applicant herein; that he has read the attached response to Generic Letter 94-02 'or Peach Bottom

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Facility Operating Licenses DPR-44 and DPR-56, and Limerick Facility Operating Licensees NPF-39 and NPF-85, and knows the contents thereof; and that the statements and matters set forth therein are true i

and correct to the best of his knowledge, information and belief.

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i Senior Vice President and Chief Nuclear Officer i

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. Generic Letter 94-02 Docket Nos. 50-277 i

' Attachment 1 50-278 i

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50-352 I

50-353 Ucense Nos. DPR-44 DPR-56 NPF-39

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NPF-85 Egouested Actions i

Generic Letter (GL) 94-02, "Long Term Solutions and Upgrade of Interim Operating Recommendations i

For Thermal Hydraulic InstabHities in Bouing Water Reactors," requested Bouing Water Reactor (BWR) licensees to review their current procedures and training programs and modify them as appropriate to strengthen the administrative provisions intended to avoid power oscillations or to detect and suppress them if they occur prior to implementation of the long-term solutions. In doing this each licensee should:

1.

a) Ensure that procedural requirements exist for initiation of a manual scram under all operating condklons when all recirculation pumps trip (or there are no pumps operating) with the reactor in the run mode, and ensure that operators are aware of the potential for very large power oscillations and the potential for exceeding core thermal safety limits before automatic l

protection systems function following the trip of all recirculation pumps (the procedural i

manual scram is not necessary after long-term solutions are approved and implemented for j

indMdual plants); and l

b) Ensure that factors important to coru stabHity characteristics (e.g., radial and axial peaking,.

feedwater temperature and thermal hydraulic compatibuity of mixed fuel types) are controlled i

wkhin appropriate limits cuisistent with the core design, power / flow exclusion boundaries, and core monitoring capabHities of the reactor in question, and that these factors are controHed through procedures governing changes in reactor power, including startup and shutdown, particularly at low-flow operating conditions. Each licensee should review its procedures and determine if instabHity can be avoided by these procedures and if the l

procedures can be carried out using existing instrument information. If it is concluded that a near-term upgrade of core monitoring capability is called for to ease the burden on operators, determine the need to incorporate on-line stability monitoring or monitors for i

stabHity sensitive parameters and inform the NRC of the schedule and technical evaluation for i

such upgrades found to be necessary.

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AH licensees of BWRs are requested to develop and submit to the NRC a plan for long term I

stability corrective actions, Is.cluding design specifications for any hardware modifications or additions to facNitate manual or automatic protective response needed to ensure that the plant is in compliance with General Design Criteria (GDC) 10 and 12. An acceptable plan could provide for implementing one of the long-term stablity solution options proposed by the BWR Owners' l

Group (BWROG) and approved by the NRC. The plan should include a description of the action proposed and a schedule of any submittal requiring plant specific design review and approval by the NRC and an installation schedule. The plan should also address the need for near-term and long-term technical specification modifications.

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. Generic Lett] 9442 Docket Nos. 50-277

' Attachment 1 50-278 50-352 50-353 Ucense Nos. DPR-44 DPR-56 NPF49 NPF-85 Interim Corrective Actions (ICA)

Resoonse 1g PECO Energy, at both LGS and PBAPS, has implemented the Interim Corrective Actions (ICA) specified in NRC Bulletin 88-07, Supplement 1, ' Power Oscillations in Boiling Water Reactors." These actions included a review of station procedures that ensured requirements existed to initiate a manual scram under the conditions described in Requested Action Ia, and a review of training material that ensured that operators were made aware of potentia; power oscillations and the potential to exceed core thermal l

safoty limits under the conditions described in Requested Action ia.

Resoonse 1b In addition to implementing the actions referenced in Response ta, PECO Energy has supported the BWROG effort to develop irnproved guidelines for the ICA to better address startup and low power maneuvering conditions. A copy of the improved BWROG Guidelines, dated June 6,1994, for stability ICA was reviewed by the NRC.

It should be noted that the BWROG guidelines are consistent with and more conservative than the ICA which were previously implemented as a result of NRC Bulletin 88-07, Supplement 1. The regions defined in the 1988 BWROG ICA (and included in the NRC Bulletin 88-07, Supplement 1) were based on stability tests and events known at the time. Subsequent work identified a sensitivity to reactor power shape and/or feedwater temperature conditions. Because of this, the BWROG included an expanded stability region and power distribution control definition in their June 6,1994 guidelines. These changes provide a higher degree of protection against unacceptable power oscillations.

PECO Energy is currently reviewing the ICA developed by the BWROG and will complete implementation at both LGS and PBAPS by January 31,1995. To simplify plant operations and provide additional conservatism to the ICA, the Controlled Entry Region lil, proposed in the Jul 6,1994 BWROG guidelines, will be treated as part of the Exit Region 11. When Power Distribuuon Controls (PDC),

consistent with Appendix B of the June 6,1994 BWROG guidelines are implemented, the Exit Region 11 may be amended to include a Controlled Entry region.

During transition to the Long-Term Solution (LTS), revisions to the ICA will be considered. Specifically, ICA curves defining plant specific exclusion and restricted operating regions on the power / flow map may be established consistent with the methodology described in NEDO-32339, " Reactor Stability Long-Term Solution: Enhanced Option I-A." If such a revision to the ICA is pursued, it will include PDC in the restricted region, as defined by Appendix B of the June 6,1994 BWROG guidelines (i.e., Core Average Bolling Boundary greater than or equal to 4.0 feet). PECO Energy will ensure that the NRC receives written notification in accordance with the conditions of GL 94-02, should any changes to the ICA changes be implemented.

Because the ICA guidelines are intended for use only until the LT3 can be implemented, changes to the Technical Specifications (TS) will not be pursued at this time. The LTS will require changes to the TS and these changes will be submitted in accordance with the schedule in Enclosure 2.

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. Generic Letter 94-02 Docket Nos. 50-277

" Attachment 1 50-278 50-352 50-353 License Nos. DPR-44 DPR-56 NPF-39 NPF-85 Lona Term Sdutions Besoonse 2 The NRC requirement for long term stability solutions to ensure compliance with GDC 10 and 12 was originally presented in NRC Bulletin 8847, Supplement 1 (December 30,1988). The Bulletin acknowledged that the NRC was working with the BWROG to develop generic approaches to resolve the reactor stabHity issue. These efforts led to the solution concepts and supporting methodology described in NEDO41960, "BWR Owners' Group Long-Term Stability Solutions Licensing Methodology" and NEDO-32339, " Reactor Stability Long Term Solution: Enhanced Option I-A."

For both PBAPS and LGS, PECO Energy has elected to proceed with the Enhanced Option I-A, as described in NEDO-32339, " Reactor Stability Long Term Solution: Enhanced Option I-A." This solution introduces new plant hardware and software to ensure that reactor coupled neutronic/ thermal-hydraulic instabilities wHI not result in fuel thermal limit violations during reasonably limiting anticipated operating conditions. PECO Energy is participating with other utilities and GE Nuclear Energy, under a BWROG program, to conduct initial application activities and to develop the design of the modification. Generic recommendations for TS changes are provided as part of this BWROG program. Plant specific versions of these TS changes will be incorporated as part of the Enhanced Option i A modification.

Implementation of the long term stability solution plan is contingent upon NRC acceptance of the BWROG methodology (NEDO-32339) and the PECO Energy hardware and software submittals.

The schedule for completion of the joint design and licensing activities is provided in Enclosure 1. Plans for plant specific actMties are indicated in Enclosure 2. These schedules were based on an NRC review period of six months for plant specific submittals.

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l ENCLOSURE 1 ENHANCED OPTION 1-A STABluTY PROGRAM DESIGN AND UCENSING ACTIVITIES NRC/BWROG MILESTONES Letter on Enhanced Option 1-A, NEDO-32339, 4/11/94 (actual)

NRC issues Safety Evaluation Report on NEDO-32339, Supplement 1 Oct.1994 BWROG issues Enhanced Option I-A Hardware topical report 1st O 1995 NRC issues Enhanced Option I-A SER May 1995 Enhanced Option I-A first plant implemented 1st O 1996 Enhanced Option I-A implemented at all plants 1998 i

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ENCLOSURE 2 ENHANCED OPTION 1-A STABILITY PROGRAM PBAPS UNIQUE ACTIVITIES NRC/PBAPS MILESTONES Unit 2 1)_nRJ n

Implement improved ICAs Based on BWROG Recommendations 1/31/95 1/31/95 Submit Technical Specification Change 10/1997 10/1998 Implement BWROG Enhanced Option 1-A 30/1997 30/1990 Page 1 of 2

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l, ENCLOSURE 2 ENHANCED OPTION 1-A STABluTY PROGRAM LGS UNIQUE ACTIVITIES NRC/ LGS MILESTONES i

Unn1 Unit 2 implement improved ICAs Based on BWROG Recommendations 1/31/95 1/31/95 Submit Technical Specification Change

. 3 O/1996 3 O /1997~

f implement BWROG Enhanced Option I-A 1 0/1997 10/1998 l

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