ML20216H073
| ML20216H073 | |
| Person / Time | |
|---|---|
| Site: | Cooper  |
| Issue date: | 04/15/1998 |
| From: | Swailes J NEBRASKA PUBLIC POWER DISTRICT |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| Shared Package | |
| ML20216H076 | List: |
| References | |
| NLS980037, NUDOCS 9804210035 | |
| Download: ML20216H073 (6) | |
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NLS980037 April 15,1998 U.S. Nuclear Regulatory Commission Attention: Dccument Control Desk Washington, D.C. 20555-0001 s"
Gentlemen:
Subject:
Proposed Change to CNS Technical Specifications Neutron Monitoring (NM), Flow Biased Rod Block Monitor Cooper Nuclear Station, NRC Docket 50-298, DPR-46
Reference:
- 1) Letter from G. R. Horn to USNRC, dated March 27,1997," Proposed Change to CNS Technical Specifications, Conversion to Improved Standard Technical Specifications" In accordance with the provisions of 10 CFR 50.4 and 50.90 the Nebraska Public Power District (the District) hereby submits a request for an amendment to License DPR-46 to change the Cooper Nuclear Station (CNS) Technical Specifications. The proposed change deletes the maximum of s 108% of rated power for the APRM Rod Block Trip Se'. ting in Technical Specification Sections 2.1.A.1.d and 3.2.C. This change is necessary since CNS is not licensed for core flows above 100% of rated flow and therefore a maximum APRM Rod Bic:k Trip Setting of 108% of rated power is not applicable to CNS.
In the Improved Technical Specification (ITS) submittal (Reference 1), this item is relocated to
,7 the Technical Requirements Manual (TRM). Approval of this proposed Technical Specification
. M-change could then be used to delete the maximum of 108% of rated power for the APRM Rod
,, Block Trip Setting from the TRM.
A1achment I contains the bases for the chance, the no significant hazard consideration deternination, and the CNS Technical Spt :Hcm. ion pages wvised by this change. This proposed change'bs been reviewed by the necessary.afay review committees and incorporates all amendmentMM CNS Facility Operating Lianse through Amendment 176 issued May 9,
- 1997, i s By copy of this letter an:] its attachment the appropriate State of Nebraska official is being 9804210035 98041S',
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NLS980037 Page 2 of 3 notified in accordance with 10 CFR 50.91 (b) (1). Copies to the NRC Region IV office and the CNS Resident Inspector are also being provided in accordance with 10 CFR 50.4 (b) (2).
l Should you have any questions or require any additional information regarding this submittal, please contact Bradford Houston at (402) 825-5819.
i Sincerel-
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J. H. Swailes Vice President of Nuclear Energy
/dm Attachment cc: Regional Administrator w/ attachment USNRC - Region IV l
Senior Project Manager w/ attachment USNRC - NRR Project Directorate IV-1 l
Senior Resident Inspector w/ attachment i
USNRC l
Environmental Health Division - Program. Manager w/ attachment
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Nebraska Department of Health NPG Distribution w/o attachment
NLS980037 Page 3 of 3 STATE OF NEBRASKA
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NEMAllA COUNTY
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M. F. Peckham, 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 Nebraska; that he is duly authorized to submit this correspondence on behalf of Nebraska Public Power District; and that the statements contained herein are true to the best of his knowledge and belief.
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li. F. Peckham l
Subscribed in my presence and sworn to before me this /fay of BAL /,,1998.
t GENERALNOTARMtate of Ndrada
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LUCI V. A. PATZEL
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NOTARY PlfBLIC i
Attachment I to NLS980037 Page1of3 COOPER NUCLEAR STATION i
TECEINICAL SPECIFICATIONS NEUTRON MONITORING SYSTEM ROD BLOCK MONITOR I
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P : vised Pages 8
j 61 i
1.0 Introduction l
This proposed change to Cooper Nuclear Station (CNS) Technical Specifications removes the maximum limit of s 108% of rated power for the Average Power l
Range Monitor (APRM) rod block trip setting. The APRM rod block function is flow biased to protect against a Minimum Critical Power Ratio (MCPR) less than the Safety Limit by preventing rod withdrawal at reduced core flows. The flow j
j biased trip setting provides substantial margin from fuel damage, assuming steady i
state operation at the trip setting, over the entire recirculation flow range. This change is required because CNS cannot comply with a verbatim interpretation of the existing Technical Specification which requires a maximum limit of s 108%
l of rated power for the APRM rod block setting.
2.0 Discussion The 108% of rated power limit was intended for those plants licensed to operate above 100% of core flow, so that a rod block would alert operators prior to a reactor scram being initiated. Since CNS is not licensed to operate above 100%
of core flow, there is no design requirement for the 108% rod block limit. The intent of the maximum of 108% of rated power rod block limit is therefore preserved wiih the core flow limited to 100% of rated flow. An additional safety factor is that General Electric (GE) developed the correlation for the Critical i
Power Ratio, as approved in the GE Standard Application for Reactor Fuel (GESART II NEDE-24011-P-A-US), with an uncertainty in the core flow of 2.5%. Thus, the Safety Limit MCPR is based on a core flow of 102.5%.
The requirement for a maximum of 108% of rated power was added in Technical Specification Amendment 151. A review of this amendment and the supporting documentation failed to reveal the reason for this addition. It is surmised, although not confirmed, that, since General Electric (GE) supplied the Technical Specification changes, CNS was supplied with the standard GE Technical Specification wording which also applied to those plants which were licensed to
to NLS980037 Page 2 of 3 core flows greater than 100% of rated flow. GE has stated, in a letter to CNS dated April 26,1995, that the maximum rod block limit of 108% of rated power was for those plants licensed for increased core flow (ICF) operation conditions.
CNS has not implemented ICF and therefore the maximum limit for the APRM rod block is not required.
3.0 Descriptien of Changes The following are the proposed changes that are requimd to bring CNS into verbatim compliance with the Technical Specifications.
Section 2.1.M (page 8)
The words "with a maximum of s 108% of rated power" are deleted.
Inbk12f(page 61)
The words "with a maximum of s 108% of rated power" are deleted l
4.0 Significant Ilazard Determination 10 CFR 50.91 (a) (1) requires that licensee requests for operating license l
amendments be accompanied by an evaluation of significant hazard posed by the issuance of an amendment. This evaluation is performed with respect to the j
criteria given in 10 CFR 50.92 (c).
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4.1 The proposed amendment does not involve a significant increase in the probability I
or consequences of an accident previously evaluated. The deletion of the 108% of rated power limit does not alter any of the accident precursors assumed in the CNS accident analysis. In addition, no credit is taken for the upper limit of 108%
l in the CNS accident analysis to mitigate the consequences of any accident. In 1
particular, the increased flow event is discussed in the Updated Safety Analysis l
l Report (USAR). There is no credit taken to mitigate the consequences of this i
event for the 108% of rated power rod block trip. The event is either terminated l
by a high flux scram or by planned operation, depending on the plant initial l
conditions. The worst initial conditions for this event, as stated in the USAR, is at about 47% of rated core flow and 65% of rated power and not at 100% of rated core flow and 100% of rated power. Thus the deletion of the maximum rod block trip setting of 108% from the CNS Technical Specifications does not involve a significant increase in the probability or consequences of an accident previously j
evaluated.
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Attach. ment 1 to NLS980037
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Page 3 of 3 4.2 The proposed change will not create the possibility of a new or different kind of accident than evaluated in the USAR. The proposed change does not result in any physical change to CNS structures, systems, or components, nor does it change the fit, form, or function of any equipment or components taken credit for in the accident analyses described in the USAR. Therefore, the deletion of the 108%
3 rated power rod block trip setting from the Technical Specifications does not create the possibility of a new or different kind of accident.
4.3 The proposed deletion of the 108% of rated power rod block trip setting from the CNS Technical Specifications will not reduce the margin of safety. This conclusion is based on the fact that the present licensing restriction to not exceed j
100% of core flow during normal power operation assures that the intent of the maximum 108% limit to alert the operator prior to a reactor scram is maintained.
Note that, as discussed above, the GE methodology for determination of Critical Power Ratio assumes a core flow of 102.5% wifi provides an additional degree of conservatism.
5.0 Conclusion The District has evaluated the propored changes described above against the criteria of 10 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 requests NRC approval of this proposed change.