NRC-94-0089, Responds to GL 94-02, Long Term Solutions & Upgrade of Interim Operating Recommendations for Thermal-Hydraulic Instabilities in Bwrs

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Responds to GL 94-02, Long Term Solutions & Upgrade of Interim Operating Recommendations for Thermal-Hydraulic Instabilities in Bwrs
ML20072U770
Person / Time
Site: Fermi DTE Energy icon.png
Issue date: 09/08/1994
From: Gipson D
DETROIT EDISON CO.
To:
NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
CON-NRC-94-0089, CON-NRC-94-89 GL-94-02, GL-94-2, NUDOCS 9409190014
Download: ML20072U770 (8)


Text

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i Douglas R. Gipson Senior Vice President Nuclear Generahon DOITOil r.mn 6400 horth Duie Hghway

{f Newport. Michgan 48166 (313) 586-S249 i

September 8, 1994 NRC-94-0089 U. S. Nuclear Regulatory Commission Attn.: Document Control Desk Washington, D. C. 20555

References:

1) Fermi 2 NRC Docket No. 50-341 NRC License No. NPF-43
2) NRC Generic Letter 94-02, "Long-Term Solutions and Upgrade of Interim Operating Recommendations for Thermal-Hydraulic Instabilities in Boiling Water Reactors", dated July 11, 1994.

Subject:

Detroit Edison Response to NRC Generic Letter 94-02 This letter provides Detroit Edison's response to Generic Letter 94-02, which required a response within 60 days of the date of the Generic Letter. This generic letter was issued to request that each addressee (1) take the appropriate actions to augment its respective procedures and training for preventing or responding to thermal-hydraulic instabilities in its reactors, and (2) submit to the NRC a plan describing the long-term stability solution option it has selected and the implementation schedule it proposes for the modification of plant protection systems.

Detroit Edison's response to each of the above items is provided in the Enclosure to this letter. This response includes the following commitments:

(1) Procedure changes and initial training will be completed as described in the enclosure to implement the BWROG guidelines prior to startup from the current outage.

(2) Plant modifications will be made to provide early detection of instability and to initiate the appropriate mitigating action.

The long term solution designated as BWROG Option III has been selected by Detroit Edison. Contingent upon NRC approval of the generic and plant specific licensing submittals discussed in the Enclosure, the new system will be installed during RF05 to operate for one cycle in the " indicate only" mode, followed by ap),1vation of the automatic stability trip in RF06.

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USNRC September 8, 1994 NRC-94-0089 l

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.If you have any questions, please contact Mr. Girija S. Shukla at-l (313) 586-4270.

Sincerely,

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-Enclosure cc:

.T.'G. Colburn C.

Lehmann (BWROG)

H. C. Pfefferlen (BWROG)-

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Phillips J. B. Martin K.

McElroyL(BWROG).

M. P. Phillips T. J. Rausch (BWROG)

K. R. Riemer a

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USNRC-September 8,'1994 NRC-94-0089-.

Page 3 i '

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. I, DOUGLAS R.' GIPSON, do hereby affirm-that.the forego ng i

statements are based on facts and circumstances which are true and accurate to'the best of my knowledge and belief.

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1 DOUGLAS R. GIPSON Senior Vice President' On this day of t h L,M 994 before me--

l personally appeared Douglas R. 'Gipton, being first duly sworn and says that he executed the foregoing as his ' free act and deed.

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Notary Public r

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i a0 EMLA A ARMUTA MARYPUBUCSTATE OF MIOSCAN MONROE CDUNTY MY COMMI9SION EXP. NoV. 20.1995 i

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Enclosure to NRC-94-0089 Page 1 DETROIT EDISON RESPONSE TO GENERIC LETTER 94-02 (Long-Tern Solutions and Upgrade of Interim Operating Recommendations for Thermal-Hydraulic Instabilities in Boiling Water Reactors)

Detroit Edison Response to NRC Requested Action 1, Upgrade of o

Interim Operating Recommendations in Procedures and Training:

i

Background

Detroit Edison has implemented and. incorporated in Fermi 2 procedures the Interim Corrective Actions (ICAs) specified in NRC Bulletin 88-07, Supplement 1.

In addition, Detroit Edison has supported the BWR Owners' Group'(BWROG) effort to develop

. improved guidelines for the ICAs to better address startup and low power maneuvering conditions.

.A copy of.the improved.BWR Owners' Group Guidelines for Stability Interim Corrective Action dated June 6, 1994 has already been provided to the NRC by the i

BWROG.

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The improved Guidelines.are consistent with, but more restrictive than, the ICAs which were previously implemented and incorporated into Fermi 2 Technical Specifications as a result of NRC Bulletin.

88-07, Supplement 1.

The original regions were defined in the 1988 BWROG'ICAs and were included in NRC Bulletin 88-07, Supplement 1, based:on stability tests and events known at the time. Subsequent work identified a sensitivity to reactor power shape and/or feedwater temperature conditions. To respond to this new information, the improved Guidelines incorporate an expanded stability region and power distribution control i

definition to strengthen the oscillation prevention feature.

This, in conjunction with the detection and suppression provisions of the improved Guidelines, provides a higher degree of protection against unacceptable power oscillations.

- Action Planned Detroit Edison plans to modify, where necessary, its operating procedures and training programs such that they are consistent with or more conservative than the BWROG Guidelines. At Fermi 2, the Controlled Entry Region will be' treated as part of the Exit Region and power distribution controls will not be implemented.

The Fermi 2 procedure changes and initial training will be implemented prior to startup from the current outage for cycle 5.

Training for the current licensed operator requalification class, reactor engineers, and STAS has been completed. Training program material for the next initial licensed operator class will be revised by July 28, 1995.

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Enclosure to NRC-94-0089 Page 2 No modification of the Fermi 2 Technical Specifications are planned because the plant operating procedures and operator training modifications necessary to implement the ICAs are intended for use only until the stability long-term solution is implemented, and can be accommodated within the current applicable Technical Specifications. However, a Technical Specification Clarification has been issued to further clarify the relationship between the existing Fermi 2 Technical Specifications and the BWROG guidelines.

Detroit Edison Response to NRC Requested Action 2, Long-Tern o

Solution, Selection and Implementation:

Background:

The NRC requirement for stability long-term corrective actions to ensure compliance with General Design Criteria 10 and 12 of 10 CFR 50 was originally presented in NRC Bulletin 88-07, Supplement 1.

The Bulletin acknowledged that the NRC was working with the BWROG to develop generic approaches for resolution of this issue. The resulting BWROG effort has led to the solution concepts and supporting methodology described in NED0-31960 and NEDO-31960, Supplement 1, "BWR Owners' Group Long-Term Stability Solutions Licensing Methodology." The NRC has preliminarily accepted the BWROG developed solution concepts and supporting methodology.

Action Planned:

Based on the technical progress that has been made on the BWROG stability program and the degree of NRC acceptance of various solution concepts, plans have been formulated for implementing a stability long-term solution. Detroit Edison has elected to proceed with a solution designated as BWROG Option III (NED0-31960) which introduces new plant hardware / software to provide early detection of coupled neutronic/ thermal-hydraulic instabilities and to initiate an appropriate mitigating action. To complete this activity, Detroit Edison is participating with other utilities under a BWROG program to finalize the supporting Option III methodology, and has contracted with GE to develop the hardware / software design and deliver the final product.

Recommendations for associated Tecnnical Specification changes will be provided as part of the BWROG methodology program.

These changes will be submitted for Fermi 2 as appropriate.

The new hardware will implement the Option III methodology as an integrated part of an advanced digital power range neutron monitoring (PRNM) upgrade using GE NUMAC equipment. This

Enclosure to NRC-94-0089 Page 3 integrated implementation approach will provide a better overall solution for the stability trip function since the LPRM signal processing will be improved and the risk of creating new problems at the stability trip hardware /PRNM interface will be eliminated.

This integrated implementation approach will also improve overall PRNM performance. To provide better overall APRM averages, improved immunity to individual detector transients, and more operational flexibility, as well as reduced risk of surveillance induced trips, Fermi 2 has also elected to implement an improved 4-channel APRM system with 2-out-of-4 PRNM trip logic into the Reactor Protection System.

Implementation of the stability long-term solution plan is contingent upon NRC acceptance of the planned BWROG submittal on methodology and the Fermi 2/GE generic submittal on the implementing hardware and software design. The schedule for completion of the generic design and licensing activities is provided in Table 1.

Plans for Fermi 2 specific activities are provided in Table 2.

Assuming the joint development activities and NRC acceptance is completed as scheduled, it is Detroit Edison's objective to have the PRNM upgrade with the l

1 Option III trip in the " indicate only" mode installed at Fermi 2 during RF05 Fermi 2 will be developing specific plans to monitor and evaluate the Option III trip performance for one cycle prior to activation of the automatic trip. Subject to successful identification and implementation of any required modifications, Detroit Edison's objective is to have the automatic stability trip operational after RF06, which is currently scheduled for the fall of 1997 i

NRC-94-0089 Tables Page1 i

TABLE 1 GENERIC DESIGN & LICENSING ACTIVITIES (OPTION III PLUS PRNM UPGRADE) 1993 NRC approval of BWROG Long-Term Stability Solutions Licensing Methodology, NEDO-31690 and NEDO-39610, Supplement 1.

1993 Initiate NUMAC PRNM equipment design work (GE).

2Q94 Deliver first NUMAC PRNM (without stability trip), non-US BWR (GE).

2Q94 Initiate design work to incorporate Option III into NUMAC PRNM architecture (GE).

3Q94 Select lead plant for NUMAC PRNM w/ Option III i

3Q94 Meet with NRC to review overall licensing plan and review key issues (GE and Utilities).

4Q94 Meet with 'NRC to review technicalissues and resolution status.

IQ95 Submit Generic Topical Report, NUMAC PRNM w/ Option III/ alternate (2 out of 4) trip logic (hardware / software implementation and generic issues)

(GE).

1Q95 Submit BWROG Detect & Suppress Topical Report (BWROG) l 2Q95 Lead plant system design complete 1

2Q95 Lead plant hardware fabrication complete 3Q95 NRC approval (SER) of Generic NUMAC PRNM Topical Repon 3Q95 Fabricate and test NUMAC PRNM with Option III & 2-out-of-4 trip logic prototype (GE) 4Q95 NRC approval (SER) of BWROG Detect & Suppress Topical Report 4Q95 Option III ready for installation at lead plant l

1 NRC-94-0089 Tables Page 2 TABLE 2 FERMI 2 SPECIFIC ACTIVITIES (OPTION III PLUS PRNM UPGRADE)

)

3Q95 Submit Technical Specification Change for NUMAC PRNM Upgrade (and improved 4-channel APRM with 2 out of 4 trip logic) lQ96 NRC approval SER of Technical Specification Change submittal for PRNM Upgrade (prior to refueling outage scheduled to start 3/96) i IQ96 Confirm schedule for implementation i

IQ96 Hardware Fabrication Complete & Factory Acceptance Test Complete l

2Q96 Install PRNM upgrade (and improved 4-channel APRM with 2 out of 4 trip logic) and Option III (with stability trip disabled) j l

3Q96 Submit Technical Specification Change for Option III (stability) functions in NUMAC PRNM j

3Q97 NRC SER of Technical Specification Change submittal for Option III (stability) functions. (Prior to refueling outage scheduled to start 9/97) 4Q97 Activate Stability Trip Function, for Cycle 7.

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