ML113040362
| ML113040362 | |
| Person / Time | |
|---|---|
| Site: | Kewaunee  |
| Issue date: | 10/31/2011 |
| From: | Price J Dominion Energy Kewaunee |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| 11-598, TAC ME6288 | |
| Download: ML113040362 (9) | |
Text
Dominion Energy Kewaunee, Inc.
5000 Dominion Boulevard, Glen Allen, VA 23060 October 31, 2011 U. S. Nuclear Regulatory Commission Serial No.11-598 Attention: Document Control Desk L1C/JG/RO Washington, DC 20555 Docket No. 50-305 License No. DPR-43 DOMINION ENERGY KEWAUNEE, INC.
KEWAUNEE POWER STATION LICENSE AMENDMENT REQUEST 252, OPERATION OF SERVICE WATER FLOW TO COMPONENT COOLING HEAT EXCHANGERS RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION (TAC ME6288)
By application dated May 9,2011 (reference 1), as supplemented by a letter dated June 30, 2011 (reference 2), Dominion Energy Kewaunee, Inc. (DEK), requested an amendment to Facility Operating License Number DPR-43 for Kewaunee Power Station (KPS). The proposed amendment would revise the KPS current licensing basis (CLB) regarding the manner in which service water is supplied to the component cooling heat exchangers by the main return valves and the bypass flow control valves.
Subsequently, the Nuclear Regulatory Commission (NRC) transmitted a request for additional information (RAI) regarding the proposed amendment (reference 3). The RAI questions and associated DEK responses are provided in Attachment 1 to this letter.
This response has no impact on any other aspect of License Amendment Request 252.
If you have any questions or require additional information, please contact Mr. Jack Gadzala at 920-388-8604.
Sincerely,
Serial No.11-598 License Amendment Request 252 Page 2 of 3 COMMONWEALTH OF VIRGINIA COUNTY OF HENRICO The foregoing document was acknowledged before me, in and for the County and Commonwealth aforesaid, today by J. Alan Price, who is Vice President - Nuclear Engineering of Dominion Energy Kewaunee, Inc. He has affirmed before me that he is duly authorized to execute and file the foregoing document in behalf of that Company, and that the statements in the document are true to the best of his knowledge and belief.
Acknowledged before me this 3) S-l-day of ()CtD=tIt...=..;( ,2011.
My Commission Expires: _---'....L..,,;W=;...L.:::2D:.....=--"\!.....:S=- _
Ginger Lynn ~utherfcrd NOTARY PUBLIC COmmonwealth of Virginia Reg. # 310847 Ldl~~~
My Commission ExpIres 4/30/2015
Attachment:
- 1. Response to Request for Additional Information
References:
- 1. Letter from J. Alan Price (DEK) to Document Control Desk (NRC), "License Amendment Request 252, Operation of Service Water Flow to Component Cooling Heat Exchangers," dated May 9,2011.
- 2. Letter from J. Alan Price (DEK) to Document Control Desk (NRC), "License Amendment Request 252, Operation of Service Water Flow to Component Cooling Heat Exchangers," dated June 30, 2011.
- 3. Email from Karl D. Feintuch (NRC) to Jack Gadzala (DEK), "ME6288 -
Kewaunee Amendment Request Re: service water flow to component cooling heat exchangers - Request for Additional Information (RAI)," dated September 15, 2011.
Serial No.11-598 License Amendment Request 252 Page 3 of 3 cc: Regional Administrator, Region III U. S. Nuclear Regulatory Commission 2443 Warrenville Road Suite 210 Lisle, IL 60532-4352 Mr. K. D. Feintuch Project Manager U.S. Nuclear Regulatory Commission One White Flint North, Mail Stop 08-H4A 11555 Rockville Pike Rockville, MD 20852-2738 NRC Senior Resident Inspector Kewaunee Power Station Public Service Commission of Wisconsin Electric Division P.O. Box 7854 Madison, WI 53707
ATTACHMENT 1 RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION:
LICENSE AMENDMENT REQUEST 252 OPERATION OF SERVICE WATER FLOW TO COMPONENT COOLING HEAT EXCHANGERS KEWAUNEE POWER STATION DOMINION ENERGY KEWAUNEE, INC.
Serial No.11-598 Attachment 1 Page 1 of 5 RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION:
LICENSE AMENDMENT REQUEST 252 OPERATION OF SERVICE WATER FLOW TO COMPONENT COOLING HEAT EXCHANGERS By application dated May 9, 2011 (reference 1), as supplemented by a letter dated June 30, 2011 (reference 2), Dominion Energy Kewaunee, Inc. (DEK), requested an amendment to Facility Operating License Number DPR-43 for Kewaunee Power Station (KPS). The proposed amendment would revise the KPS current licensing basis (CLB) regarding the manner in which service water is supplied to the component cooling heat exchangers by the main return valves and the bypass flow control valves.
Subsequently, the Nuclear Regulatory Commission (NRC) transmitted a request for additional information (RAI) regarding the proposed amendment (reference 3). The RAI questions and associated DEK responses are provided below.
NRC Question RAI-1 (from SBPB)
Table 1 of the licensee's letter dated June 30, 2011, states that during the post accident injection phase, approximately 1200 gallons per minute (gpm) flow through each of the bypass valves SW 1306 A and B. SW 1306 A and Bare 4 inch throttle valves in the 4 inch bypass lines around the 10 inch component cooling heat exchanger SW discharge*
valves. The Nuclear Regulatory Commission's staff notes that 1200 gpm flow through a 4 inch pipe has a flow velocity greater than 30 ft/sec. From Figure 9.6-2 of the KPS USAR, the 4 inch bypass valves appear to be globe valves, which could have a seat diameter that is typically 0.75 (or less) of the size of the pipe diameter (approximately 0.57 flow area) and could result in a calculated flow velocity through the valve of approximately 50 ft/sec. 30-50 ft/sec flow velocities seem excessive for a 4 inch pipe and valve. Possible effects of excessive flow could be excessive vibration, cavitation, and valve seat/disc erosion and/or choke flow.
(1) Discuss the validity of the large flow velocities through the 4 inch bypass pipe and valves as stated above and in your letter dated June 30, 2011.
(2) Discuss whether excessive vibration and cavitation occur and whether that is acceptable and why.
(3) Is choke flow possible through the 4 inch valves under these circumstances?
And if so:
(a) What is the actual flow rate? and (b) Is it satisfactory for LOCA mitigation?
Serial No.11-598 Attachment 1 Page 2 of 5
Response
Calculated flow velocity through service water (SW) valves SW-1306A and SW-1306B is approximately 33 ft/sec at 1300 gpm flow. However, such a flow velocity is not excessive as justified below.
SW-1306A and 1306B are 4-inch, full ported, Fisher "EZ" globe valves.
KPS Calculation C11344, Rev 0, "2001 SW System Flow Test," documents the results of service water (SW) testing performed in 2001. Data Sheet 15 documented a test arrangement with service water flow through valves SW-1306A and SW-1306B at greater than 1300 gpm. The flow rates from C11344 are not the flow rates at the initial post-accident injection phase. They are test flow rates that provide information at flow rates greater 1300 gpm through SW-1306A and SW-1306B. During this test no excessive vibration or noise was identified from SW-1306A or SW-1306B.
The subject SW flow rates through SW-1306A and SW-1306B are short duration, only occurring during the initial post-accident injection phase.
The SW flow rates listed in Table 1 of the letter dated June 30, 2011 (Reference 2), are derived from Calculation 01-042, Case 4 (Reference 8), for valve SW-1306A, and Calculation 01-042, Case 5 (Reference 9) for SW-1306B. These flow rates are as follows.
- SW-1306A 1120 gpm
- SW-1306B 1223 gpm The SW flow model indicates the following inlet pressures for these valves. The inlet pressures are based on 1120 and 1223 gpm. A conservatively high flow rate of 1300 gpm (higher flow is more conservative since it causes a higher valve L1P) was used to determine the outlet pressures.
Valve Inlet Pressure Outlet Pressure SW-1306A 66 psia @ 1120 gpm 19.3 psia @1300 gpm SW-1306B 78 psia @ 1223 gpm 31.3 psia @ 1300 gpm
Serial No.11-598 Attachment 1 Page 3 of 5 The outlet pressure was calculated using the following formulas (Reference 5).
SW-1306A Q gpm = 7.9 xCv [(Pinlet - Poutletj)/Pdensity ]1/2 1300 = 7.9 x 190 x [(66 psia - Poutlet )/62.22Ib/ft 3 ]1/2 Poutlet= 19.3 psia Therefore, LiP= 46.7 psid across valve SW-1306A (i.e., LiP = 66 psia -19.3 psia)
SW-1306B Q gpm = 7.9 x Cv [(Pinlet - Poutletj)/Pdensity ]1/2 1300 = 7.9 x 190 x [(78 psia - Poutlet )/62.22 Ib/ft 3 ]1/2 Poutlet= 31.3 psia Therefore, LiP= 46.7 psid across valve SW-1306B (i.e., LiP = 78 psia - 31.3 psia)
Cavitation Flow Analysis The pressure drop across the valve at which cavitation can begin is determined by the following (Reference 4).
LiP cavitation = Kc X [Pinlet - Pinlet vapor pressure]
K c [cavitation coefficient] for valves SW-1306A1B is 0.79 (per Fisher Valve).
Pinletvaporpressure (at 150°F) = 3.7184 (150°F vapor pressure was used to conservatively bound temperature)
SW-1306A LiP cavitation = 0.79 x [66 - 3.7184] = 49.2 psid Therefore, for SW-1306A: LiPpost-accident (46.7 psid) < LiPcavitation (49.2 psid)
SW-1306B LiP cavitation = 0.79 x [78 - 3.7184] = 58.7 psid Therefore, for SW-1306B: LiPpost-accident (46.7 psid) < LiPcavitation (58.7 psid)
Serial No.11-598 Attachment 1 Page 4 of 5 Cavitation does not occur if LlP across the valve is less than LlPcavitation. As shown above, the 'differential pressure (LlP) across valves SW-1306A and SW-1306B under post-accident conditions (LlPpost-accident = 46.7 psid) using a conservatively high bounding flow rate of 1300 gpm, is less than the minimum differential pressure required for cavitation to begin (LlPcavitation) of 49.2 psid for SW-1306A and 58.7 psid for SW-1306B.
Therefore, based on the evaluation, cavitation at the outlet of these valves is not expected to occur.
Choked Flow Analysis The following equation determines the maximum allowable pressure drop that is effective in producing flow, thereby not resulting in choked flow (References 4 and 5).
LlP choked flow =Km X [Pinlet - (rc X Pinlet vapor pressure)]
rc = 0.94 Per Fisher Valve, Km [recovery coefficient] for Valves SW-1306A/B is 0.79 SW-1306A LlP choked flow =0.79 X [66 - (0.94 X 3.7184)] =49.4 psid > SW-1306A LlP of 46.7 psid SW-1306B LlP choked flow = 0.79 X [78 - (0.94 X 3.7184)] = 58.9 psid > SW-1306B LlP of 46.7 psid As shown above, the differential pressure (LlP) across valves SW-1306A and SW-1306B under initial post-accident conditions (46.7 psid) is less than the minimum differential pressure required for choked flow to begin (LlP choked flow) of 49.4 psid for SW-1306A and 58.9 psid for SW-1306B.
Therefore, based on the evaluation above choked flow will not occur. Consequently, the valve design supports the calculated post-accident flow rates. Also, with no choked flow or cavitation present, significant vibration is not expected to occur.
In summary:
(1) The validity of the large flow velocities through the 4-inch bypass pipe and valves, as stated in the letter dated June 30, 2011, is bounded by the above evaluation.
(2) Neither excessive vibration nor cavitation will occur as a result of the bounding flow of 1300 gpm; therefore, this condition is acceptable.
Serial No.11-598 Attachment 1 Page 5 of 5 (3) No choked flow will occur through the 4-inch valves under these circumstances; therefore, this condition does not adversely impact LOCA mitigation and is acceptable.
NRC Question RAI-2 (from IHPB)
Please describe any changes to the safety parameter display system resulting from the proposed LAR.
Response
No changes to the safety parameter display system result from the proposed LAR.
References
- 1. Letter from J. Alan Price (DEK) to Document Control Desk (NRC), "License Amendment Request 252, Operation of Service Water Flow to Component Cooling Heat Exchangers," dated May 9, 2011.
- 2. Letter from J. Alan Price (DEK) to Document Control Desk (NRC), "License Amendment Request 252, Operation of Service Water Flow to Component Cooling Heat Exchangers," dated June 30,2011.
- 3. Email from Karl D. Feintuch (NRC) to Jack Gadzala (DEK), "ME6288 -
Kewaunee Amendment Request Re: service water flow to component cooling heat exchangers - Request for Additional Information (RAI)," dated September 15, 20111.
- 4. Fisher Control Valve Handbook, Second Edition, Fourth Printing, pages 66-68.
- 5. Flow of Fluids through Valves, Fittings, and Pipe; Crane, Equation 3-16.
- 6. Cameron Hydraulic Data, Fifteenth Edition, First Printing.
- 7. Drawing 43B6343 Rev. A3 (Kewaunee Drawing XK-95965-2), showing valve port size to be 4.0 inch diameter, SW-1306A1B, Fisher Valve
- 8. Calculation 01-042, Rev. F, Attachment E, Case 4, Initial Post Accident (Train A),
documenting pressure upstream of SW-1306A as 66 psia, node AQA.
- 9. Calculation 01-042, Rev. F, Attachment F, Case 5, Initial Post Accident (Train B),
documenting pressure upstream of SW-1306B as 78 psia, node BOC.