ML20073A058
| ML20073A058 | |
| Person / Time | |
|---|---|
| Site: | Mcguire, Catawba, McGuire  |
| Issue date: | 09/08/1994 |
| From: | Tuckman M DUKE POWER CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| Shared Package | |
| ML20073A061 | List: |
| References | |
| NUDOCS 9409200102 | |
| Download: ML20073A058 (4) | |
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DukeIswerCompany M S Tinua P.0 B u 1006 Senior Vice President
, Owlotte, NC28201LM6 NuclearGeneration (70D3822200 office (IOD3824360Tu DUKEPOWER September 8, 1994 U. S. Nuclear Regulatory Commission Washington, D.
C.
20555 Attention: Document Control Desk
Subject:
McGuire Nuclear Station Docket Numbers 50-369 and -370 Catawba Nuclear Station Docket Numbers 50-413 and -414 Proposed Technical Specification Changes to Relocate Specific Boron concentration Values to the Core Operating Limits Report; Supplemental Information By letter dated May 24, 1994, Duke Power Company submitted proposed Technical Specification changes for McGuire and Catawba Nuclear c
-Stetions which would relocate values of required boron concentrations from Technical Specifications to the Core Operating Limits Report.
NRC review of the proposed changes has indicated that additional information is required to complete their review.
Accordingly, attached is the requested information.
Attachment I contains a description of the methodology used to determine spent fuel pool and refueling canal boron concentrations.
Attachment II contains corrected Technical Specification mark-ups.
If you require additional information, please call Scott Gewehr at
'(704) 382-7581.
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S. Nuclear Regulatory Commission Septmber 8, 1994 j
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Mr. V. Nerses, Project Manager Office of Nuclear Reactor Regulation U.
S.
Nuclear Regulatory Commission Mail Stop 14H25, OWFN Washington, D.
C.
20555 Mr.
R.
E. Martin, Froject Manager Office of Nuclear Reactor Regulation U.
S.
Nuclear Regulatory Commission Mail Stop 14H25, OWFN Washington, D.
C.
20555 Mr.
S.
D.
Ebneter, Regional Administrator U.S.
Nuclear Regulatory Commission - Region II 101 Marietta Street, NW - Suite 2900 Atlanta, Georgia 30323 G.
F. Maxwell Senior Resident Inspector McGuiru Nuclear Station R. J.
Freudenberger Senior Resident Inspector Catawba Nuclear Station l
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fi ATTACIIMENT 1 In conversations with Jie NRC staff reganling the Reference I submittal, questions have arisen as to the approved metinfology utilized by Duke Power for detennining the spent fuel pool and refueling canal minimum hmm concentrations. The purpose of this letter is to funher clarify the connection between spent fuel pool and refueling canal minimum boron concentrations and the methodology given in DPC-NE-2010A (Reference 2).
In a January 13,1993 submittal (Reference 3), Duke Power requested, among other things, that the hmm concentration limits for the refueling water storage tank (RWST) and cold leg accumulators (CLAs) be moved from the Technical Specifications to the Core Operating Limits Repons (COLR) for the McGuire and Catawba Nuclear Stations. The NRC subsequently approved these requests via issuance of References 4 and 5.
During reload analyses, the limiting calculation for detennining the RWST and CLA minimum hmm concentrations involves the post-LOCA subcriticality evale. lion. During a large break LOCA event, borated water contributions fmm the reactor coolant system, RWST, CLAs, ECCS piping and the ice condenser are mixed together in the reactor building sump. The hmm concentration of this mixed solution should be high enough to ensure core subcriticality once the sump recirculation phase of the event is initiated. Currently, no credit is taken for control rod insertion to guarantee subcriticality during this evaluation. Duke Power utilizes the methodology presented in DPC-NE-2010A to detennine the all-rods-out critical boron concentrations for comparison to the boron concentration of the mixed sump solution. If the hmm concentration of the mixed sump solution is greater than the all-mds-out critical hmm concentration, core suberiticality is guaranteed.
l With the transition ta longer cycle lengths (i.e., more reactive cores), the RWST and CLA minimum bomn concentrations are required to increase in onler to satisfy the post-LOCA subcriticality evaluation. During refueling operations, the refueling canal is filled with borated water frum the RWST. During fuel transfer, the borated water in the refueling canal can mix with the borated water in the spent fuel pool. After the mfueling outage, the refueling canal is drained, with the borated water being retumed to the RWST. Thus, it is desirable to have the minimum hmm concentrations for the RWST, mfueling canal and spent fuel pool the same in order to prevent a dilution in the RWST bomn concentration once the RWST is mfdled. Duke Power has adopted this approach in onler to.eclude a possible Technical Specilication violation on minimum RWST hmm concentration.
It shoukt also be emphasized that the minimum hmm concentration detennined for the RWST will be greater than that required to ensure adequate subcriticality margin in the refueling canal and spent fuel pool. In general, soluble boron is not cmdited for spent fuel storage criticality calculations. Ilased on Technical Specification 3.9.1 for McGuire and Catawba, the Nmm concentration of the water volume having direct access to the tractor vessel during refueling operations must h greater than that required to maintain a core K of 0.95 or less, or greater than er the ininimum hmm concentration of the RWST. since RWST water fills the refueling canal. 'Ihe boron concentration required to keep the core Kdt less than or equal to 0.95 during refueling operations is calculated utilizing the metinlology given in Reference 2. During mioad analyses, it has tren found that the ininimum RWST bonm concentration detemlined to satisfy the post-LOCA 1
i suberiticality evaluation is more limiting (i.e., larger) than that requimd to keep the com K less m
than or equal to 0.95 during refueling operations (Mode 6).
References 1.
Letter from M, S. Tuckman (Duke) to USNRC,"McGuin: Nuclear Station, Docket Nmnbers 50-369 and -370, Catawba Nuclear Station, Docket Numbers 50-413 and -414, Proposed Technical Specification Changes to Relocate Specific Boron Concentration Values to the Core Operating Limits Repo 1," May 24,1994.
2.
DPC-NE-2010A, " Nuclear Physics Methodology for Reload Design," June,1985.
3.
Letter from M. S. Tuckman (Duke) to USNRC, " Catawba Nuclear Station, Docket Nos. 50-413 aml 50-414, McGuire Nuclear Station Docket Nos. 50-369 and 50-370, Tecimical Specification Amendment, Relocation of Cycle-Specific Parameter Limits," January 13, 1993.
4.
Letter hum Robert E. Martin (NRC) to D. L. Rehn (Duke). " Issuance of Amendments -
Catawba Nuclear Station, Units 1 and 2, Cycle Specific Parameters to the Core Operating Limits Report (TAC Nos. M85472 and M85473)," March 25,1994.
5.
Letter form Victor Nerses (NRC) to T. C. McMeekin (Duke), " Issuance of Amendments -
McGuire Nuclear Station, Units 1 and 2,(TAC Nos. M85474 and M85475)," May 31,1994.
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4 ATTACHMENT iia Technical Specification Markups McGuire I