ML13114A162
| ML13114A162 | |
| Person / Time | |
|---|---|
| Site: | Peach Bottom  |
| Issue date: | 04/23/2013 |
| From: | David Helker Exelon Generation Co |
| To: | Office of Nuclear Reactor Regulation, Document Control Desk |
| References | |
| Download: ML13114A162 (5) | |
Text
10 CFR 50.90 April 23, 2013 U.S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, D.C. 20555-0001 Peach Bottom Atomic Power Station, Units 2 and 3 Renewed Facility Operating License Nos. DPR-44 and DPR-56 NRC Docket Nos. 50-277 and 50-278
Subject:
Response to Request for Additional Information-Revision of Normal Heat Sink Technical Specification to Remove the 24-Hour Average Temperature Limit With No Change to the Peak Maximum Temperature
References:
- 1) Letter from M. Jesse (Exelon Generation Company, LLC) to U.S. Nuclear Regulatory Commission, "Revision of Normal Heat Sink Technical Specification to Remove the 24-Hour Average Temperature Limit With No Change to the Peak Maximum Temperature," dated July 18, 2012
- 2) E-mail from R. Ennis (U.S. Nuclear Regulatory Commission) toT.
Loomis (Exelon Generation Company, LLC), "Draft RAJ-Peach Bottom Normal Heat Sink Operability Requirements (TACs ME9085 & 86},"
dated November 5, 2012
- 3) Letter from M. Jesse (Exelon Generation Company, LLC) to U.S.
Nuclear Regulatory Commission, "Response to Request for Additional Information - Revision of Normal Heat Sink Technical Specification to Remove the 24-Hour Average Temperature Limit With No Change to the Peak Maximum Temperature," dated January 17, 2013
- 4) E-mail from R. Ennis (U.S. Nuclear Regulatory Commission) toT.
Loomis (Exelon Generation Company, LLC}, "Draft RAJ-Peach Bottom Normal Heat Sink Operability Requirements (TACs ME9085 & 86),..
dated March 8, 2013 In the Reference 1 letter, Exelon Generation Company, LLC (EGC) requested a proposed change to modify the Technical Specifications {TSs). The proposed change revises the Peach Bottom Atomic Power Station (PBAPS), Units 2 and 3, TS Section 3.7.2, "Emergency Service Water (ESW) System and Normal Heat Sink,.. to change the requirements for determining the operability of the Normal Heat Sink (NHS). Specifically, this change is proposing to revise TS Section 3. 7.2 to remove the maximum 24-hour average temperature of 90°F with no change to the peak maximum NHS temperature of 92°F.
U.S. Nuclear Regulatory Commission Response to Request for Additional Information Revision of Normal Heat Sink Technical Specification April 23, 2013 Page 2 In the Reference 2 e-mail, the U.S. Nuclear Regulatory Commission Staff requested additional information. Attachment 3 was our response. The U.S. Nuclear Regulatory Commission Staff has requested additional information in Reference 4. Attached is our response to this request.
Exelon has reviewed the information supporting a finding of no significant hazards consideration and the environmental consideration provided to the U.S. Nuclear Regulatory Commission in Reference 1. The additional information provided in this submittal does not affect the bases for concluding that the proposed license amendment does not involve a significant hazards consideration. In addition, the additional information provided in this submittal does not affect the bases for concluding that neither an environmental impact statement nor an environmental assessment needs to be prepared in connection with the proposed amendment.
There are no regulatory commitments contained in this submittal.
Should you have any questions concerning this letter, please contact Tom Loomis at (610) 765-5510.
I declare under penalty of perjury that the foregoing is true and correct. Executed on the 23rd day of April 2013.
Respectfully, David P. Helker Manager, Licensing & Regulatory Affairs Exelon Generation Company, LLC
Attachment:
Response to Request for Additional Information cc:
USNRC Region I, Regional Administrator USNRC Senior Resident Inspector, PBAPS USNRC Senior Project Manager, PBAPS R. R. Janati, Commonwealth of Pennsylvania S. T. Gray, State of Maryland
Attachment Response to Request for Additional Information
Response to Request for Additional Information Question:
Attachment Page 1 1. The proposed amendment would delete the LCO actions associated with verifying the NHS water temperature on an hourly basis when the temperature approaches the operability limit.
As currently proposed, assuming no changes to the Surveillance Frequency Control Program, the NHS water temperature would be verified only once per 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. Due to temperature variations over this time period, this 24-hour surveillance frequency may not be sufficient to provide reasonable assurance that design basis assumptions will be met.
Request Please provide additional justification to provide assurance that the frequency of surveillance is sufficient to assure that design basis assumptions will continue to be met.
Response
The 24-hour surveillance frequency is implemented by ST-0-098-01 N-2(3), "Daily Surveillance Log Mode 1, 2, or 3," which assures Technical Specification {TS) surveillance compliance.
Supplementing the TS surveillance procedure is routine test RT-0-288-800-2, "River Temperature and Flow Monitoring," which requires the NHS intake temperature to be recorded at 4-hour intervals when the previous day's average intake temperature is 47°F or above. In addition, during times of extreme hot weather, a Hot Weather Alert will be issued, in which case OP-AA-108-107-1001, "Station Response to Grid Capacity Conditions," would direct Operations to "augment their normally executed set of rounds with additional checks for those temperature sensitive areas or components... OP-AA-108-107-1001 would direct Operations to monitor NHS temperature more frequently as required to ensure the TS I design basis assumptions will be met.
Question:
- 2. In order to ensure that the plant is maintained within the bounds of various analyses, instrument uncertainties and other uncertainties need to be accounted for in the TS limit, plant procedures or in the analyses. It is not clear that instrument uncertainties and other potential uncertainties have been taken into consideration.
Request Please provide additional justification to provide assurance that instrument uncertainties and other potential uncertainties have been accounted for to assure that design basis assumptions will continue to be met.
Response
There are six instruments per unit (TE-2280 A-F for Unit 2 and TE-3280 A-F for Unit 3) which measure the Normal Heat Sink (NHS) temperature. Each temperature element has an accuracy of+/- 0.28°F. The six values are averaged and the resultant output (computer point C148 for Unit 2 and C448 for Unit 3) is used to determine the NHS temperature. Averaging the six instruments increases the accuracy of the temperature reading, which along with margin in the design analysis (discussed below), provides assurance that design basis assumptions will be met.
Response to Request for Additional Information Attachment Page2 The analyses which use the NHS temperature utilize design basis values for inputs. The inputs of the calculations are the Technical Specification limits (e.g., highest suppression pool temperature), which provide the worst possible scenario of the plant. Other non-TS inputs include Residual Heat Removal (RHR) heat exchanger fouling. The worst design basis fouling factor is utilized in the analyses. These analyses assume that all of the inputs are at their worst case value. The results of the analyses have margin for the parameter evaluated. For example, the maximum torus temperature for RHR pump Net Positive Suction Head (NPSH) has margin with all input parameters at their Technical Specification limit (i.e., NHS temperature and initial temperature of the suppression pool) and design basis limit (i.e., RHR heat exchanger fouling factor).