ML20134K365
| ML20134K365 | |
| Person / Time | |
|---|---|
| Site: | Cooper  |
| Issue date: | 02/10/1997 |
| From: | Horn G NEBRASKA PUBLIC POWER DISTRICT |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| Shared Package | |
| ML20134K368 | List: |
| References | |
| NLS970001, NUDOCS 9702130263 | |
| Download: ML20134K365 (7) | |
Text
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P.O. BOX JKA 68321 Nebraska Public Power District TMJ"
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NLS970001 February 10,1997 U.S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, D.C. 20555-0001
Subject:
Proposed Change to CNS Technical Specifications Implementation of BWR Thermal Hydraulic Stability Solution Cooper Nuclear Station NRC Docket No. 50-298, License No. DPR-46
References:
- 1. NEDO-31960 and NEDO-31960, Supplement 1, BWR Owner's Group Long-Term Stability Solutions Licensing Methodology.
- 2. Generic Letter 94-02, dated July 11,1994,"Long-Term Solutions and Upgrade ofInterim Operating Recommendations for Thermal hydraulic Instabilities in Boiling Water Reactors."
- 3. Letter to USNRC from G. R. Horn (Nebraska Public Power District), dated September 9,1994, " Generic Letter 94-02."
Gentlemen:
In accordance with the provisions of 10 CFR 50.4 and 50.90, the Nebraska Public Power District (District) hereby submits a request for an amendment to license DPR-46 to change the Cooper Nuclear Station (CNS) Technical Specifications. The proposed change provides the requirements for avoidance and protection from thermal hydraulic instabilities to be consistent with Reference (1).
Attachment I contains the bases for the changes, the no significant hazard consideration j
determination, and the CNS Technical Specifications pages revised by this change. This proposed change has been reviewed by the necessary safety review committees and incorporates all g
amendments to the CNS Facility Operating License through Amendment 175 issued April 29,
/
1996.
In response to NRC Generic Letter 94-02 (Reference 2), the District by a letter (Reference 3) committed to install the Long-Term Solution Stability System (LTSSS) Option III features at 9702130263 970210 DR ADOCK 05000298 PDR
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o NLS970001 February 10,1997 Page 2 of 4 CNS by June 1,1997, and to have it operational by December 1,1997 following acceptance f
testing. Since then, evaluations have been performed by General Electric (GE), and they have l
conclusively demonstrated that the " Regional Exclusion with Flow-Biased APRM Neutron Flux Scram" Stability Solution Option I-D of Reference (1) is applicable to the Cycle 18 as-loaded-core of CNS, in compliance with General Design Criteria 12. Enclosed with this submittal is the plant specific licensing topical report, GENE-A13-00395-01, Application of the " Regional Exclusion with Flow-Biased APRM Neutron Flux Scram" Stability Solution (Option I-D) to the Cooper Nuclear Station. The report presents an Exclusion Region for CNS which identifies plant conditions that may lead to an instability. Following are the conclusions drawn in the report:
(1)
The Exclusion Region Analysis confirms that the core-wide reactor instability is the predominate mode, and that regional mode oscillations are not expected to i
occur for CNS.
(2)
A statistically based Detect and Suppress Analysis demonstrates that the APRM Flow-Biased Neutron Flux trip provides protection to the Safety Limit Minimum Critical Power Ratio (SLMCPR) in the event of a core-wide mode of thermal-hydraulic /neutronic oscillation at CNS.
(3)
An on-line stability predictor and administrative controls are necessary to provide a high degree of assurance that fuel thermal limits cannot be approached.
In light of the above conclusions, the District has re-evaluated its original commitment to install LTSSS Option 111 features. Based on the conclusion provided in the enclosed GE report, the District by this letter is proposing LTSSS Option I-D at CNS instead of Option III as follows:
(1)
An Exclusion Region in the Power / flow operating map will be implemented.
(2)
The ability of the APRM flow-biased flux trip to detect and suppress the most probable mode of power oscillations (core-wide mode) before the SLMCPR is reached has been demonstrated using the statistical methodology described in NEDO-32465.
(3)
An on-line stability predictor will be installed and made operable with the necessary administrative controls at CNS.
i The District is hereby submitting the required Technical Specification change request to implement the above mentioned actions under LTSSS Option I-D by December 1,1997. The District requests that this Technical Specification change request be approved on or before November 1,1997. This date will allow sufficient time of at least 30 days for licensed operator
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l NLS970001 February 10,1997 Page 3 of 4 l
training and the revision of station procedures prior to the amendment effective date of December 1,1997.
i By copy of this letter and its attachment, the appropriate State of Nebraska oflicial is being l
l notified in accordance with 10CFR50.91(b)(1). Copies to the NRC Region IV Oflice and the l
CNS Resident Inspector are also being provided in accordance with 10CFR50.4(b)(2).
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Should you have any questions or require any additional information regarding this submittal, please contact Jim Pelletier at (402) 825-5646.
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. I >rn Se ice-President of Energy Supply j
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Attachment i
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cc: Regional Administrator USNRC - Region IV l
Senior Project Manager USNRC - NRR Project Directorate IV-1 Senior Resident Inspector l
USNRC i
NPG Distribution l
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NLS970001 February 10,1997 Page 4 of 4 STATE OF NEBRASKA) l
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NEMAHA COUNTY
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G. R. Horn, being first duly sworn, deposes and says that he is an authorized representative of the Nebraska Public Power District, a public corporation and political subdivision of the State of l
Nebraska; that he is duly authorized to submit this request on behalf of Nebraska Public Power District; and that the statements contained herein are true to the best of his knowledge and belief.
4-
. 'R. Horn Senio ice-President of Energy Supply
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subscribed in my presence and sworn to before me this /0+* day of -7h
,1997.
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GEllERALll0TARf4tateof 4drasta liARY FRANCES ARMSTRONG lir Comm. Eg.Jan.11,1998 l
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- Attachment 1 l
to NLS970001 l:
Page 1 of 5 i
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COOPER NUCLEAR STATION TECHNICAL SPECIFICATIONS IMPLEMENTATION OF BWR THERMAL HYDRAULIC STABILITY SOLUTION r
Revised Panes 17 98b (deleted) 212a 98 98c (deleted) 214a i
98a (deleted) 103 234 l
1.0 Bases for Changes i
Section 2.1. A 1.a Bases l
The Bases to the APRM Flux Scram Trip Setting was changed to reflect the fact that the APRM flow-biased flux scram provides protection to the Safety Limit MCPR in the event of a thermal-hydraulic instability.
Sections 3.3.F.2. 3.3.F.3.a. 3.3.F.3 b. 4 3.F 1. 4.3.F.2. Figure 3.3.1 and Anolicable Bases
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These sections deal with core plate dP, APRM and LPRM neutron flux noise levels associated.
with single and two recirculation loop operations. The measures described in these sections had been adopted as interim actions, required until long-term stability solutions became available and were implemented. As this change would implement the BWROG Long-Term Stability Solution Option I-D for CNS, these specifications are no longer necessary and therefore, they have been deleted.
Section 3.3.F.3 Bases This section, which deals with no recirculation loops in operation, has been added to ensure that operation close to a region where thennal-hydraulic instabilities can happen, does not occur. The completion time of 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />, is based on operating experience of a reasonable time to reach the Hot Shutdown condition, in an orderly manner and without challenging plant systems.
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Attachment I to NLS970001 Page 2 of 5 Section 311,D and Applicable Bases The section on Thermal-hydraulic Stability has been changed to reflect the actions required to implement the BWROG Long-Term Stability Solution Option I-D. This specification prohibits intentional entry into the Stability Exclusion Region and requires immediately exiting the Region, ifit is entered.
S.getion 6 5.1.G Bases Changes have been made to this section to ensure the Core Operating Limits Reports, COLR, can be updated with data necessary for the current cycle. A power / flow map has been added to the list ofitems required for the COLR, because this map contains the definition of the Stability Exclusion Region, which may vary from cycle to cycle. Additionally, the core flow MCPR adjustment factor, Kr, has been deleted since it does not exist due to the ARTS /ELLLA modification.
2.0 Significant Hazards Determination 10 CFR 50.91 (a) (1) requires that licensee requests for operating license amendments be accompanied by an evaluation of significant hazards posed by the issuance of an amendment.
This evaluation is performed with respect to the criteria given in 10 CFR 50.92 (c).
1 This proposed change to Cooper Nuclear Station (CNS) Technical Specifications provides the requirements for avoidance and protection from thermal hydraulic instabilities.
2.1 The proposed amendment does not involve a significant increase in the probability or j
consequences of an accident previously evaluated. In fact, it does not result in an increase in the probability or consequences of any previously evaluated accidents. The implementation of BWROG Long-Term Stability Solution Option I-D at CNS does not modify the assumptions contained in the existing accident analysis. The use of an exclusion region and the operator actions required to avoid and minimize operation inside the region do not increase the possibility of an accident. Conditions of operation outside of the exclusion region are within the analytical envelope of the existing safety analysis. The operator action requirement to exit the exclusion region upon entry minimizes the possibility of an oscillation occurring. The actions to drive control rods and/or to increase recirculation flow to exit the region are maneuvers within the envelope of normal plant evolutions. The flow-biased scram has been analyzed and will provide automatic fuel protection in the event of an instability. Thus, each l
proposed Technical Specification requirement provides defense for protection from an instability event within the existing assumptions of the accident analysis.
2.2 As stated above, the proposed Technical Specification requirements either mandate operation
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within the envelope of existing plant operating conditions or force specific operating maneuvers within those carried out in normal operation. Since operation of the plant with all of the proposed requirements is within the existing' operating basis, an unanalyzed accident will not be created through implementation of the proposed change.
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2.3 Each of the proposed requirements for plant thermal-hydraulic stability provides a means for j
fuel protection. The combination of avoiding possible unstable conditions and the automatic L
flow-biased reactor scram provides an in depth means for fuel protection. Therefore, the j
L individual or combination of means to avoid and suppress an instability supplements the l
l margin of safety.
3.0 Conclusion i
The District has evaluated the proposed changes described above against the criteria of 10
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CFR 50.92 in accordance with the requirements of 10 CFR 50.91 (a) (1). This evaluation has -
determined that the proposed change to Technical Specifications will not (1) involve a significant increase in the probability or consequences of an accident previously evaluated, (2) create the possibility for a new or different kind of accident from any accident previously evaluated, or (3) create a significant reduction in the margin of safety. Therefore, the District i
requests NRC approval of this proposed change.
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