ML111820365
| ML111820365 | |
| Person / Time | |
|---|---|
| Site: | Kewaunee  |
| Issue date: | 06/30/2011 |
| From: | Price J Dominion, Dominion Energy Kewaunee |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| 11-108A | |
| Download: ML111820365 (15) | |
Text
Dominion Energy Kewaunee, Inc.
5000 Dominion Boulevard, Glen Allen, VA 23060 June 30, 2011 U. S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, DC 20555 Serial No. 11-1 08A L1C/JG/RO 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 By application dated May 9, 2011 (reference 1), 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 two requests for additional information (RAI) regarding the proposed amendment (references 2 and 3).
The RAI questions and associated DEK responses are provided in Attachment 1 to this letter.
DEK requests approval of the proposed amendment by June 30, 2012.
DEK will implement the amendment within 60 days after approval.
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, ice ident - Nuclear Engineering
Serial No. 11-1 08A 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.
':/ /7f Acknowledged before me this.:;?(} :=- day of_-..l...-4-..t..£l.LL.!~=-__' 2011.
My Commission Expires: ~_"""""'''I---=-'''---'=..Io.r....L--+-
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Notary Public VICKI l. HULL Notary Public Commonw.alth of Virginia 140542 My Commission Explrts May 31. 2014
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.
Email from Karl D. Feintuch (NRC) to Jack Gadzala (DEK) and Thomas Breene (DEK), "ME6288 - License Amendment request reo service water flow to component heat exchangers - acceptance review status and need to supplement information",
dated June 8, 2011.
3.
Email from Karl D. Feintuch (NRC) to Jack Gadzala (DEK) and George Lapinsky (NRC), "ME6288 Acceptance Review - needed supplementation - IHPB input", dated June 14, 2011.
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 Serial No. 11-1 08A License Amendment Request 252 Page 3 of 3
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. 11-108A
.Attachment 1 Page 1 of 11 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), 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 two requests for additional information (RAI) regarding the proposed amendment (references 2 and 3).
The RAI questions and associated DEK responses are provided below.
NRC Question SBPB-1 The NRC staff considers that a more detailed discussion regarding the adequacy of flow through the 4-inch lines during SI is required.
Before SI initiation, SW flow to the CC heat exchangers is controlled by variable positioning of the 4-inch SW bypass valves. At SI initiation, the licensee is proposing that the SI signal fully open the 4-inch bypass valves instead of the 10-inch discharge valves.
However, the licensee has given no basis in the LAR that they have analytically determined that SW flow through the 4-inch valves to the CC heat exchangers is sufficient, although the CC heat load changes at SI initiation in that the SI, RHR and containment spray pumps, which require CC cooling, all start.
The NRC staff notes that flow through a 4-inch line is less than 20% of the flow through a 10-inch line.
The licensee has given no indication that they have performed a heat transfer and flow analysis of the CC system to verify that the reduced flow of SW through the CC heat exchanger is adequate during SI.
No analysis is referenced in the LAR, just a statement that flow is adequate.
Serial No. 11-1 OBA Page 2 of 11
Response
Background As discussed in the submittal (reference 1), the facility design prior to implementation of the subject design change (OCR 3163) provided for automatically opening the 10-inch service water (SW) system valves (SW 1300 AlB), located on the discharge of the component cooling (CC) heat exchangers (HX), to ensure adequate SW flow to the CC heat exchangers upon the initiation of a safety injection (Sl) signal for safety injection and containment sump recirculation cooling.
Of note, is that these 10-inch valves contained a position limiter, such that upon receipt of an Sl signal, the valves would automatically open to only the throttled setting, which was less than 50% of full open.
Thus, the previous design only resulted in restricted flow thru these 1O-inch valves upon automatic opening (the valves' throttle settings were based on calculated SW flow values needed to remove the heat loads).
The original facility design was based on automatic opening of the 10-inch SW valves to their throttled position to accomplish two accident mitigating functions.
First, the flow was credited with automatically providing cooling during the initial post-accident (injection) phase. Second, the flow was credited with providing the cooling needed during the long term post-accident (containment sump recirculation) phase.
During normal operation (Le., prior to SI initiation), SW flow to the CC heat exchangers is controlled by variable positioning of the 4-inch SW bypass valves (SW-1306 A/B) as needed to control CC temperature.
Plant Modification OCR 3163 changed the controls affecting the SW system components and how the SW system responds to an SI signal.
The design was changed by OCR 3163 to provide the following two functions.
- 1) Provide a safety-related function to automatically open the 4-inch SW bypass valves fully (instead of automatically opening the 10-inch SW valves to the throttled setting) upon initiation of the SI signal to provide sufficient flow to the CC heat exchangers to cool components operating during the injection phase of the postulated accident; and,
- 2) Provide for the manual opening of the 10-inch discharge valves (SW-1300AlB) at the onset of containment sump recirculation to provide any additional SW flow to the CC heat exchangers that may be needed to cool the containment sump (SW-1306 AlB valves full open and SW-1300AlB valves throttled open).
Plant modification OCR 3163 resulted in the 4-inch valves being capable of providing the first credited safety-related function (automatically provide cooling flow during SI).
Serial No. 11-1 OBA Page 3 of 11 This modification (DCR 3163) was evaluated and determined to be appropriate for implementation. The evaluation assessed the adequacy of cooling capabilities of the affected SSCs in accomplishing the first function above, determining the resulting cooling capability to be acceptable.
The change in the second function (listed above) was subsequently determined to require prior NRC approval per 10 CFR 50.59 (i.e., changing the automatic opening of the 10-inch valves for long term post-accident cooling to a manual action). This change was initially determined to be acceptable because the process for aligning from the injection phase to the recirculation phase (as described in the licensing basis) had been, and remains, a manually achieved function. This change added another manual step to the process. Time critical analyses were conducted on operators to verify that the new action could be completed within the necessary time frame.
Approval of the change to the method of controlling the second function is being requested in LAR 252. Since the cooling capacity of the SW system 10-inch supply remained essentially unchanged, the magnitude of the achievable cooling water flow was not specifically addressed in the originally submitted amendment request. The proposed amendment focused upon the timeliness of achieving the needed SW flow when the 10-inch SW supply is controlled manually.
The calculations to demonstrate the adequacy of the flow provided via the 4-inch lines were not included with LAR 252 because the flow controlled by the 4-inch valves was not within the scope of the change considered to require prior regulatory approval.
However, to facilitate NRC acceptance review, the following summary of technical information is being provided to explain how flow thru the 4-inch SW bypass lines during the injection phase of the initial postulated accident response is adequate.
Technical Justification for SW Cooling Capability; Initial Post-accident Injection Phase SW system flow capabilities have been analyzed and are documented in calculations.
These analyses are used to support the evaluation of the affected SSCs in accomplishing their post-accident credited safety functions.
The SW system analyses support the technical bases to justify that the 4-inch bypass valves provide sufficient SW flow to the CC heat exchangers in the initial post-accident injection phase response, independent of the 10-inch valves. The SW system analyses also demonstrate that SW flow is sufficient to accommodate CC heat load during the long term post-accident phase (containment sump recirculation post-accident phase).
A summary of the relevant technical information from the SW system analyses is provided below.
Serial No. 11-1 DBA Page 4 of 11 Table 1 Component Cooling Heat Exchanger Service Water Flow During Injection Phase and Containment Sump Recirculation Phase Predicted Initial Post-accident Reference Predicted Long Term Post-accident Reference Injection Phase SW Flow Calculation 01-042 Recirculation Phase SW Flow Calculation 01-042 (SW1306 NB open and rev. F (SW1306 NB open and rev. F SW1300 NB closed)
SW1300 NB throttled open)
SW Train A 1120 gpm Case 4 2389 gpm Case 7 CC Heat Attachment E Attachment I Exchanger 1A page 4 of 14 Page 4 of 14 SWTrain B 1223 gpm Case 5 3607 gpm Case 8 CC Heat Attachment F Attachment M Exchanger 1B page 4 of 14 Page 4 of 14 SW Trains A & B 1121 gpm 11222 gpm Case 6 2392 gpm I 2289 gpm Case 9 CC Heat Attachment G Attachment N Exchangers pages 5 and 7 pages 5 and 7 1A/1B (Note: Table 1 flow values are rounded to the nearest gallon per minute (gpm).)
Containment Sump Recirculation Phase Component Cooling (CG) Heat Exchanger (HX) Heat Removal The minimum required CC HX SW flow to remove the heat load during the long term post-accident containment sump recirculation phase is 2,000 gpm (Reference LOCA Containment Integrity Analysis described in USAR 14.3.5). The predicted CC HX SW flow is
> 2000 gpm (see Table 1 above). Thus, based on the SW analyses, the predicted CC HX SW flow is sufficient to remove heat from the CC heat loads during long term post-accident sump recirculation phase.
Containment Sump Recirculation Phase versus Injection Phase: CC HX Heat Load During the containment sump recirculation phase, RHR heat exchangers are the largest heat loads on the CC system.
The total analyzed heat input into the CC system from the RHR heat exchangers and other CC heat loads at the initiation of containment sump recirculation, with full recirculation flow established, is approximately 42 E6 STU/hr (34 E6 STU/hr RHR HX heat load plus an estimated 8 E6 STU/hr from other CC heat loads) (Reference LOCA Containment Integrity Analysis described in USAR 14.3.5).
Serial No. 11-108A Page 5 of 11 Subtracting the RHR HX heat load, CC heat loads are relatively similar during both injection phase and recirculation phase.
During the injection phase, the total CC heat load is conservatively assumed to be bounded by 10 E6, hence an estimated value of <10 E6 BTU/hr is being used in this explanation).
Containment Sump Recirculation Phase versus Injection Phase: CC HX SW Flow Rate During the containment sump recirculation phase, a minimum CC HX SW flow of 2,000 gpm is required (to remove the approximate 42 E6 BTU/hr heat load).
During the injection phase, the heat load is less than one-fourth the amount produced during the recirculation phase, whereas the CC HX SW flow rate exceeds 1,000 gpm (see Table 1 above) for cooling this significantly reduced heat load (estimated to be < 10 E6 BTU/hr).
Based on the ratio of cooling water flow rate for a given heat load, the ratio of SW flow per MBTU/hr heat load (cooling ratio) is significantly larger during the injection phase than that during the containment sump recirculation phase (see Table 2 below).
The SW flow rate during the containment sump recirculation phase was determined to be sufficient to provide required cooling, as documented in the LOCA containment integrity analysis described in USAR 14.3.5.
Since the cooling ratio is larger during the injection phase (provided by SW flow through the full open 4-inch SW-1306A1B valves to the associated CCW heat exchanger), this supports the conclusion that SW flow during the injection phase is also sufficient to provide required cooling.
Therefore, based on the available CCW HX SW flow predicted in the SW analyses. coupled with the reduced heat load during the injection phase (as compared with the heat load during containment sump recirculation), the SW flow to CCW HX is judged to be sufficient to remove heat from the CCW heat loads during the injection phase of a postulated accident.
Table 2 Heat Removal Capability Comparison - Injection Phase versus Containment Sump Recirculation Phase flow/heat load (ratio):
CC HX SW flow rate (gpm) 1 CC HX SW Flow Rate Nominal CC HX Heat Load CC HX heat load (BTU/hr
- E6)
Injection Phase Predicted minimum flow
<10 E6 BTU/hr 1000/10 =100
>1,000 gpm Containment Sump Minimum Required:
42 E6 BTU/hr (at initiation of 2000/42 = 48 (rounded)
Recirculation Phase 2,000 gpm containment sump recirculation)
Serial No. 11-108A Page 6 of 11 Normal Operation versus Injection Phase: CC HX Heat Load and CC HX SW Flow Rate A comparison of the CC HX flow rates and heat loads between normal operation and the injection phase also demonstrates the adequacy of SW flow to the CC heat exchangers during the injection phase. The typical normal operation CC heat load is estimated to be approximately 15 E6 BTU/hr.
Additional heat loads are placed on the CC system during the injection phase of a postulated accident from the operation of emergency core cooling system (ECCS) pumps. However, these additional heat loads are relatively minor. This loading is from the seal coolers of the various ECCS pumps, which include the internal containment spray (ICS) pumps, the residual heat removal (RHR) pumps, and the safety injection (SI) pumps. Although these ECCS pump seal coolers are cooled by CC water, the overall CC heat load during the injection phase will be less than the typical normal operation CC heat load due to automatic isolation of nonessential heat loads.
Upon receipt of a safety injection signal, nonessential heat loads (e.g., the significant heat load of the letdown heat exchanger with its estimated heat load of -10 E6 BTU/hr) are automatically isolated. The CC heat loads that are added following Sl actuation are small in comparison to that of the letdown heat exchanger. The result is a net reduction of CC heat load during the injection phase of the postulated accident.
During normal operation, the 4-inch SW-1306A/B valves are operated in the throttled position, providing SW flow to the CC heat exchanger. This throttled flow is sufficient to remove CC heat loads that are generated during normal plant operation. Upon initiation of an SI signal, the SW-1306A/B valves move to the full open position resulting in a CC HX SW flow rate of greater than 1,000 gpm (see Table 1 above). As a result, significant SW flow is provided to the CC heat exchanger to cool the reduced CC heat load during the post-accident injection phase.
Thus, with an SI signal causing the 4-inch SW valves to fully open, coupled with a reduction in CC heat loads due to isolation of nonessential components, sufficient SW flow is provided to the CC HXs to rembve CC system heat loads during the injection phase of a postulated accident.
Serial No. 11-1 OBA Page 7 of 11 NRC Question IHPB-1 Please identify any other operator manual actions in addition to the one action identified in the LAR that will be added, deleted, or changed to support the proposed license amendment.
Response
No additional operator manual actions, beyond the one action identified in the LAR, are added, deleted, or changed.
NRC Question IHPB-2 What cues are provided to personnel that manual action(s) is/are required?
Response
Step 9 of Procedure ES-1.3, "Transfer to Containment Sump Recirculation", directs operators to establish component cooling (CC) flow to residual heat removal (RHR) heat exchangers (HX).
Step 9.a directs ensuring both CC pumps running.
Step 9.b directs opening both component cooling heat exchanger outlet valves (SW-1300A for HX A; SW-1300B for HX B). Step 9.c directs opening both CC to RHR HX valves.
NRC Question IHPB-3 What cues are provided to personnel that the proposed action(s) is/are no longer required?
Response
Containment sump recirculation is a long term action. As such, the need for operation in this configuration would be evaluated and determined by operations management in accordance with applicable emergency and recovery procedures.
NRC Question IHPB-4 Question IHPB-4 was subsequently withdrawn by the NRC reviewer.
Serial No. 11-1 08A Page 8 of 11 NRC Question IHPB-5 Please describe any changes to operating procedures needed to support the proposed license amendment.
Response
Step 9 of Procedure ES-1.3, "Transfer to Containment Sump Recirculation", directs operators to establish component cooling flow to RHR heat exchangers.
Step 9.b was revised to direct operators to open both component cooling heat exchanger outlet valves (SW-1300A for HX A; SW-1300B for HX B).
The response to NRC Question IHPB-2 contains additional information regarding this topic.
NRC Question IHPB-6 Please describe any changes to controls or displays (including annunciators and alarms) needed to support the proposed license amendment.
Response
Annunciator light panels for the 4-inch SW bypass valves (SW-1306A and SW-1306B) being open were added to the safety injection active status panel.
NRC Question IHPB-7 Please describe any changes to training and the simulator needed to support the proposed license amendment.
Response
Licensed operator training was revised for the operations crews to incorporate the amended procedure for transitioning to the containment sump recirculation phase. The response to Question IHPB-9 contains additional information related to this training.
Plant modification OCR 3163 was implemented in the simulator under Simulator Work Order SWO 00-019 to conform the simulator to the control room.
This included modification of the modeling of SW-1300A(B) and SW-1306A(B) with respect to SI signal inputs. The SI active status panel windows 0404 (SW1306A AND CC6A OPEN) and 0408 (SW1306B AND CC6B OPEN) match the control room as verified by the latest Simulator Fidelity Report.
Serial No. 11-1 OBA Page 9 of 11 NRC Question IHPB-8 Please describe any changes to staffing or qualification needed to support the proposed license amendment.
Response
No changes to staffing or qualification are needed to support the proposed license amendment. The response to NRC Questions IHPB-7 and IHPB-11 contains additional information regarding this topic.
NRC Question IHPB-9 What has been or will be done to assure that any new or changed human actions can be done within the time limits of the relevant scenario(s)?
Response
In 2007, operator baseline data was obtained for all six of the operations crews in performing the procedure to transition from the injection phase to the containment sump recirculation phase of emergency core cooling.
The requisite time period covered the performance of activities from the point when the refueling water storage tank (RWST) dropped to 37% until the residual heat removal (RHR) pump was running at 1500 gpm flow rate.
The performance of these Procedure ES-1.3 time critical operator actions was completed in an average time of 15 minutes.
Recently performed time validations remain consistent with this baseline data.
The licensed operator requalification (LOR) simulator dynamic annual and cycle exams have resulted in no failures related to meeting the time requirements for this task.
Acceptable results were also obtained for the time critical portion of the annual job performance measures (JPMs)that were conducted on the licensed operators, with no failures related to the time element.
NRC Question IHPB-10 If applicable precedents exist, has an operating experience review been done?
Response
No applicable precedent was identified for this change.
Serial No. 11-1 OBA Page 10 of 11 NRC Question IHPB-11 Please describe any increase in operator work load that will occur with the proposed licensed amendment.
Response
All affected activities are controlled by operators remotely from the control room.
The control room is a mild environment.
The control switches for valves SW-1300A and SW-1300B are readily accessible to operators at the main control boards.
The effort needed to actuate these switches differs little from the effort needed to manually align affected ECCS valves for containment sump recirculation, which was procedurally controlled prior to the modification and continues to be procedurally controlled after the modification.
In summary, there was no significant change in operator work load associated with this modification.
NRC Question IHPB-12 Please provide engineering procedures related to the human factors design of the proposed license amendment.
Response
The change was assessed by the control room design review committee and considered sufficiently simple such that no human factors evaluation was needed for this change.
The control switches for valves SW-1300A and SW-1300B remained the same (only the name plate was changed to remove the center position "AUTO" identifier). The response to NRC Question IHPB-11 contains additional information regarding this topic.
NRC Question IHPB-13 Describe the process used to verify and validate the ability of your operators to accomplish the tasks required for the proposed LAR. In lieu of a description, you may provide the relevant procedure(s).
Response
Procedures GNP-05.16.05, "Process Control for Emergency Operating Procedures and EOP Background Documents", and GNP-05.16.06, "Validation of Time Dependant Operator Actions", are the processes used to verify and validate the ability of operators to accomplish time critical actions.
The validation process is applicable to all
Serial No. 11-1 08A Page 11 of 11 procedures for which operator actions are assumed to occur as described in plant design documents.
Validation of time dependant operator actions is performed by performing procedures and directives to ensure that time dependent operator actions can be accomplished within the time frame identified.
Validation may be performed in the control room simulator, by walking through the procedure, or by means of a table top evaluation.
Procedure GNP-05.16.,06 contains a listing of time critical operator actions. Many of the assumed action times use conservative assumptions to provide margin to design basis limits.
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.
Email from Karl D. Feintuch (NRC) to Jack Gadzala (DEK) and Thomas Breene (DEK), "ME6288 - License Amendment request reo service water flow to component heat exchangers - acceptance review status and need to supplement information",
dated June 8, 2011.
3.
Email from Karl D. Feintuch (NRC) to Jack Gadzala (DEK) and George Lapinsky (NRC), "ME6288 Acceptance Review - needed supplementation - IHPB input", dated June 14, 2011.