NL-13-0322, Response to NRC Request for Additional Information, Revision of Technical, Specification 3.7.9 Ultimate Heat Sink
| ML13059A502 | |
| Person / Time | |
|---|---|
| Site: | Vogtle  |
| Issue date: | 02/27/2013 |
| From: | Pierce C Southern Nuclear Operating Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| NL-13-0322 | |
| Download: ML13059A502 (7) | |
Text
Charles R. Pierce Southern Nuclear Regulatory Affairs Director Operating Company, Inc.
40 Inverness Center Parkway Post Office Box 1295 Birmingham. Alabama 35201 Tel 205.992.7872 Fax 205992.7601 February 27, 2013 SOUTHERN'\\
COMPANY Docket Nos.: 50-424 NL-13-0322 50-425 U. S. Nuclear Regulatory Commission ATIN: Document Control Desk Washington, D. C. 20555-0001 Vogtle Electric Generating Plant - Units 1 and 2 Response to NRC Request for Additional Information, Revision of Technical Specification 3.7.9 Ultimate Heat Sink Ladies and Gentlemen:
By letter dated September 1, 2011 (Agencywide Documents Access and Management System (ADAMS) Accession Number ML112450171), Southern Nuclear Operating Company (SNC) submitted a license amendment request for revision of Technical Specification (TS) 3.7.9 "Ultimate Heat Sink (UHS),"
Subsequently, by letter dated January 11, 2012 (ADAMS Accession Number ML11355A007), the NRC submitted a Request for Additional Information (RAI) to enable completion of the review. The SNC responses to that RAI were provided in a series of letters dated February 10, 2012, April 30, 2012, and December 18, 2012.
By letter dated January 28, 2013, the NRC submitted another RAI to enable completion of the review. The enclosure of this letter provides the response to that RAI.
This letter contains no NRC commitments. If you have any questions, please contact Ken McElroy at (205) 992-7369.
U. S. Nuclear Regulatory Commission NL-13-0322 Page 2 Mr. Chuck Pierce states he is Regulatory Affairs Director of Southern Nuclear Operating Company, is authorized to execute this oath on behalf of Southern Nuclear Operating Company and, to the best of his knowledge and belief, the facts set forth in this letter are true.
to and subscribed before me this ~7 l:J"day of ~~, 2013.
My commission expires: //-;< -/ 3 Respectfully submitted, CI{ ~
C. R. Pierce Regulatory Affairs Director CRP/CLNllac
Enclosure:
Response to Request for Additional Information cc:
Southern Nuclear Operating Company Mr. S. E. Kuczynski, Chairman, President &CEO Mr. D. G. Bost, Executive Vice President & Chief Nuclear Officer Mr. T. E. Tynan, Vice President - Vogtle Mr. B. L. Ivey, Vice President - Regulatory Affairs Mr. B. J. Adams, Vice President - Fleet Operations RType: CVC7000 U. S. Nuclear Regulatory Commission Mr. V. M. McCree, Regional Administrator Mr. R. E. Martin, NRR Senior Project Manager - Vogtle Mr. L. M. Cain, Senior Resident Inspector - Vogtle State of Georgia Mr. J. H. Turner, Environmental Director Protection Division
Vogtle Electric Generating Plant Units 1 and 2 to NRC Request for Additional Information, Revision of Technical Specification 3.1.9 Ultimate Heat Sink Enclosure Response to Request Information
Enclosure to NL-13-0322 Response to Request for Additional Information
RAI-1
Calculation X4C1202V70, Version 3, uses 97 degrees Fahrenheit (OF) as the design basis temperature for the cooling tower basins. The Updated Final Safety Analysis Report (UFSAR) states that 95°F is the maximum design temperature.
Acknowledging the exception on Page 9.2-22 of the UFSAR where basin temperature remains above 95°F for periods of 20 or 35 hours4.050926e-4 days <br />0.00972 hours <br />5.787037e-5 weeks <br />1.33175e-5 months <br /> considering only residual heat removal operation, calculation X4C1202V70 Version 3, allows basin temperature to exceed 95°F for up to 54 hours6.25e-4 days <br />0.015 hours <br />8.928571e-5 weeks <br />2.0547e-5 months <br />.
- a. What are the effects of other loads cooled by nuclear service cooling water if 95°F is exceeded for such a long period of time?
- b. Can the diesel generators operate satisfactorily with cooling water above 95°F for that many hours?
- c. Does the diesel generator vendor support SNC's answer?
SNC Response To RAI-1a:
It has been determined that the Nuclear Service Cooling Water (NSCW) temperature above 95°F for the duration per the referenced calculation will not have a significant adverse effect on the equipment that is cooled by the NSCW.
This conclusion is based on a Request for Engineering Review (RER) completed in July of 2012 to evaluate the impact of a peak NSCW basin temperature of 99.5°F during a Loss of Offsite Power (LOSP). The RER was performed in response to a condition that reported insufficient documentation to support the FSAR Section 9.2.5.2.4. The FSAR states that the peak basin temperature during three-fan cooldown operation will exceed the nominal basin design maximum temperature of 95°F, reaching approximately 9rF for Unit 1 and 98 OF for Unit 2 after residual heat removal (RHR) initiation following an LOSP event.
The RER evaluated NSCW cooled equipment operating during an LOSP and the effect the temperature increase would have on operation of this equipment. The equipment included in the scope of this RER was based on equipment aligned per Abnormal Operating Procedure 18017 -C, "Abnormal Grid Disturbances/Loss of Grid" and the specific design basis calculation that determines NSCW LOSP heat loads. The RER concluded that increasing the NSCW basin temperature from 95°F to 99.5°F would not have a significant adverse effect on the equipment operating during an LOSP. This steady state evaluation was conducted at the peak temperature of 99.5°F with one train in operation. Specific heat exchanger evaluations were performed in the RER to determine the temperature rise across the heat exchanger and/or the effective area of the specific heat exchanger required. The specific heat exchangers evaluated in the RER were the engineered safety features (ESF) chillers, NSCW pump motor coolers, component cooling water (CCW) pump motor coolers, diesel generator jacket water coolers, containment coolers, reactor cavity coolers, piping penetration area room coolers, the auxiliary component cooling water (ACCW) heat exchangers, the ACCW pump motor coolers, centrifugal charging pump lube oil coolers, centrifugal charging pump motor air coolers, CCW heat exchanger, spent fuel pool (SFP) heat exchanger, RHR heat exchanger, residual heat pump motor air coolers, letdown heat exchangers, and the seal water heat exchangers (some Page 1 of 4
Nl-13-0322 to Request for Additional of components were in support which are discussed later in this a). For some equipment, a comparison was made to the maximum vendor recommended NSCW temperature to the postulated NSCW supply. The evaluation was performed at 99.5°F because that is temperature the NSCW will during a 130 percent load with 3 fans in operation, as determined by an existing analysis that the sensitivity of heat load increases on the cooling tower fan performance. This 130 percent heat load and resulting 99.5°F supply is a bounding case for the statements made in Section 9.2.5.2.4 as well as the calculation X4C1202V70, Version 3, which basis for the License Amendment (lAR). This temperature was for continuous operation the temperature criteria for each component cooled by the In case, the NSCW supply in either meeting the vendor's temperature criteria or the resulting outlet temperature was to be acceptable.
of the RER an was also Westinghouse for the equipment of nuclear steam supply system and/or Westinghouse supplied as charging pump RHR heat exchanger, exchanger, etc. Westinghouse modeled the components with the Ultimate Heat (UHS) temperature profile for 130 lOSP heat load with the temperature of 99.5°F using RCOOl computer code. Westinghouse concludes in their evaluation equipment supplied by Westinghouse that is in service following an is designed for a NSCW normal cooling water supply temperature of 105°F and a maximum temperature of 150°F for 4 Westinghouse restates the NSCW temperature acceptance criteria concludes that all acceptance criteria can with the increased NSCW profile. Furthermore, Westinghouse demonstrates that the RHR can meet the acceptance criterion to cooldown the reactor coolant system to within 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> RHRCOOl model that it is possible to align RHR at 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> after reactor with a single train of cooldown the RCS to 200°F within reactor shutdown.
It is noted that the evaluation of bounds the analysis conducted calculation X4C1202V70 Version which limits the peak basin temperature This was completed where control requirements of NQA-1-1994 were invoked for associated engineering in conjunction with this response.
generator can operate ~!:Itt~tl:li,..,.t('\\
with cooling water above the duration determined in Version 3. The diesel generator are directly exiting the ACCW Based on the heat exchanger discussed above in new exit temperature of water being supplied to jacket water,..,.('\\;... IQlrc:!
To be conservative, included an additional 2
4
to NL-13-0322 to Request for Additional Information heat gain the cooling water yields a cooling water inlet temperature to of 1 The diesel generator water continuous maximum cooling water temperature of 1 while in the piping system.
jacket water are designed for a at 1500 gpm per the jacket water heat exchanger specifications. Since the cooling water inlet temperature to the diesel generator jacket water coolers is less than this specified maximum and the required flow rate is by approximately 200 gpm, the generators would not be adversely by the increased cooling water SNC Response To RAI - 1 c:
n"'I*~tr"'l" vendor has not been for input on the supply of jacket water sheet clearly Of"ii"o~ the maximum cooling water This is greater than supply as a result of evaluation that considers a peak NSCW temperature at 99.5°F.
it was decided that this information was sufficient in making the without direct vendor input.
this evaluation the analysis conducted per calculation X4C1202V70 Version 3, which peak basin temperature to X4C1202V70, Version 3, not the first 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> after a of offsite power (LOSP). However, when a occurs and causes a the fan loss occurs immediately at which time cooling towers have from diesel generators of about 17 million British thermal units per hour (M BTUlhr), containment cooling about 1 M BTU/hr and spent fuel pool at about 24 M BTU/hr. Calculation 202V70, Version 3, does not include the loss and heat loads from 0 to 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />.
explain why SNC not account the first 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> values for the new 3.7.9-1.
Calculation X4C1205V03, "Verification of NSCW Constant Heat Loads Cooldown Heat Loads",
constant heat loads minimum required cooling water flow rates all equipment cooled by This calculation shows that NSCW Heat Load at time 0 into the event is 92.7 x 106 Btulhr including diesel generator loads. The heat load decreases during first 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> as ACCW loads are removed from followed by a total heat to 257.82 x 106 Btu/hr beginning at time t== 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />, due to sensible heat. Existing ACCW load design calculations show an 80 percent reduction in ACCW heat from normal operations to no load at hot shutdown with an LOSP. This ACCW is greater than the generator added at thus, a net decrease in heat load is by the NSCW during the first four hours a LOSP event.
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Enclosure to NL-13-0322 Response to Request for Additional Information This reduction in heat load during first four hours of an LOSP event is in the analysis to in the RAI 1 a that basin and heat load with 3 fans in operation.
analysis evaluates the sensitivity of load percent) on the cooling tower fan periormance.
of this analysis, the NSCW basin temperature profiles as a function of hours after shutdown these starting at 0 all show a reduction in basin temperature during the 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> of thus, confirming a net reduction in NSCW heat load during the first 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> of an LOSP from normal power operation.
Therefore, on the net in the total NSCW and the of the temperature during first 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> of an design analysis, it was determined the calculation not need to consider the first 4 after an LOSP.
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