ML20070E496
| ML20070E496 | |
| Person / Time | |
|---|---|
| Site: | Peach Bottom  |
| Issue date: | 07/06/1994 |
| From: | Hunger G PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NUDOCS 9407150157 | |
| Download: ML20070E496 (4) | |
Text
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t Station Support Department 10CFR50.90 4
-7 PECO ENERGY
,72%=L 965 ChesteFarook Ekiuward Wayne, F% 19087-Sf 91 July 6,1994 i
Docket No. 50-277 License No. DPR-44 U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555 i
Subject:
Peach Bottom Atomic Power Station, Unit 2 l
Response to Request for AdditionalInformation Regarding Technical Specifications Change Request 93-02 (ASD RAI-1) l i
Dear Sir:
[
Attached is our response to your request for additional information regarding 1
Technical Specifications Change Request No. 93-02, dated April 6,1994, concerning the implementation of the end-of-cycle Minimum Critical Power Ratio Recirculation Pump Trip (MCPR-RPT) at Peach Bottom Atomic Power Station (PBAPS), Unit 2. In order to aid in our tracking of these RAIs, we will be numbering the responses in sequential order.
If you have any questions, please contact us.
Very truly yours, j
h.
4 j
G. A. Ilunger, Jr., Director i
Licensing e
Attachment ec:
T. T. Martin, Administrator, Region I, USNRC f
W. L Schmidt, USNRC Senior Resident Inspector, PBAPS
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j R. R. Janati, Commonwealth of Pennsylvania l
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9407150157 940706 PDR -ADOCK 05000277 P
PDR i
. COMMONWEALTII OF PENNSYLVANIA ss.
COUNTY OF CHESTER W. II. Smith, III, being first duly sworn, deposes and says:
That he is Vice President of PECO Energy Company; the Applicant herein; that i
he has read the enclosed response to the NRC request for additional information concerning Technical Specifications Change Request (Number 93-02) for Peach Bottom Facility Operating License DPR-44, and knows the contents thereof; and that the statements and matters set forth therein are true and correct to the best of his knowledge, information and belief.
p
'y Vice President 1
i Subscribed and sworn to b
before me this day of c
e 1994.
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Notary Public ruaw ses Erica A Santon.tbtary PtfAc My En July 995
Docket No. 50-277 License No. DPR-44 RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION (ASD RAI-1)
PEACH HO'ITOM ATOMIC POWER STATION, UNIT 2 Ouestion I "In NEDC-32165P, Rev. 2, page 5 states the RPT response time varies between 175 msee to 225 msec. However, Table 1 shows a response time of between 200 msee to 250 msec. Why the difference, and what value is used in the analysis? Is the value used in the analysis a conservative plant specific value?'
Brinnnic The transient analysis included in NEDC-32165P, Revision 2,"End-of-Cycle Recirculation Pump Trip Analysis for Peach Bottom Atomic Power Station Units 2 and 3" did not consider either the rerate power level or installation of the Adjustable Speed Drives (ASD) since it was not clear when the Recirculation Pump Trip (RPT) feature would be installed in relation to the rerate and ASD modifications. The intent of NEDC-32165P, Revision 2, was to show that installation of an RPT function would benefit Peach Bottom Atomic Power Station (PBAPS), Units 2 and 3 and justify its installation. Since the ASD and RPT equipment design had not been finalized, a nominal delay time of 175 milliseconds was used for the transient analysis. The 175 milliseconds is a typical value for a BWR/4, such as Limerick Generating Station, Units 1 and 2. Utilizing the 175 millisecond response delay shows the benefit of the recirculation pump trip, as well as providing a Minimum Critical Power Ratio (MCPR) result that can be referenced to previous transient analyses that incorporate the recirculation pump trip feature (i.e., the analyses for Limerick Generating Station, Units 1 and 2). After the transient analysis was performed but prior to the issuance of the report, it was determined that the actual RPT delay time at PBAPS, Units 2 and 3 would be greater than 175 milliseconds. In addition,it was determined that the RPT breaker opening time varies with the frequency of the power supplied through the breaker to the pump motor. This is the basis for the statement on Page 5 of the NEDC-32165P, Revision 2, and for the response times provided in Table 1.
Since the issuance of NEDC-32165P, Revision 2, transient analyses have been performed which incorporate the characteristics of the ASD and RPT equipment at the rerate power condition. Conservative values for the RPT times were used in these analyses to determine the RPT benefit at various core flows. The RPT times ranged from 233 milliseconds, at 81% core flow and rerated power, to 214 milliseconds, at 110% core flow and rerated power. These analyses verify that the recirculation pump trip feature provides substantial MCPR benefit for pressurization transients.
l J
Docket No. 50-277 License No. DPR-44 Ouestion 2 "In Table 4, define the following: Opt. A, Opt. B, and Uncorr. as used in the table."
Resnonse Descriotion of Uncorrected ACPR (Critical Power Ratiol Ontion A. and Option B Limin Uncorrected ACPR The Minimum Critical Power Ratio (MCPR) Operating Limit is determined by analyzing the limiting transients (i.e., lead Rejection With No Bypass) utilizing NRC approved methods (e.g., GESTAR II). For each limiting transient, a
^
baseline ACPR is calculated. The calculated ACPR does not include consideration of uncertanties and is referred to as the " uncorrected ACPR." The approved methodology considers uncertainties in determining the MCPR such that there is a high confidence (95% probability with 95% confidence) that the M'PR Safety Limit will not be violated. Generic statistical adjustment factors (SA) are developed to arrive at the 95/95 confidence level.
Option B The Option B MCPR Operating Limit is developed by taking the analyzed ACPR, i
also referred to as the " uncorrected ACPR," modifying it by the statistical adjustment factor (resulting in a " corrected ACPR") and adding that to the MCPR Safety Limit. The Option B analysis takes credit for actual scram speeds at the plant. The determination of the Option B MCPR Operating Limit can be represented as follows:
Option B MCPR Operating Limit = Uncorrected ACPR + SAF + MCPR Safety Limit Option A The Option A MCPR Operating Limit considers scram speed at the Technical Specification limits. Generic scram speed adjustment factors (SSAFs) have been developed to arrive at the Option A limit. The determination of the Option A i
MCPR Operating Limit is represented as follows:
Option A MCPR Operating Limit = Option B MCPR Operating Limit + SSAF 2
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