ML13002A049

Miillstone Power Station, Units 2 & 3, Response to Request for Additional Information Regarding Relief Request RR-04-09 and IR-3-15, Use of Alternative Pressure/Flow Testing Requirements for Service Water System Supply Piping

ML13002A049
Person / Time
Site:	Millstone
Issue date:	12/20/2012
From:	Hartz L Dominion Nuclear Connecticut
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
12-606
Download: ML13002A049 (16)

Text

Dominion Nuclear Connecticut, Inc. * *Dmiio 5000 Dominion Boulevard, Glen Allen, VA 23060 .Om iliOW Web Address: www.dom.com December 20, 2012 U.S. Nuclear Regulatory Commission Serial No.12-606 Attention: Document Control Desk NLOSNVDC RO Washington, DC 20555 Docket Nos. 50-336 50-423 License Nos. DPR-65 NPF-49 DOMINION NUCLEAR CONNECTICUT. INC.

MILLSTONE POWER STATION UNITS 2 AND 3 RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION REGARDING RELIEF REQUESTS RR-04-09 AND IR-3-15. USE OF ALTERNATIVE PRESSURE/FLOW TESTING REQUIREMENTS FOR SERVICE WATER SYSTEM SUPPLY PIPING By letter dated July 5, 2012, Dominion Nuclear Connecticut, Inc. (DNC) requested relief for Millstone Power Station Units 2 and 3 from certain examination and testing requirements of Section XI of the 2004 edition of the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code. Specifically, DNC requested approval of alternative methods for performing the leakage testing as required by ASME Section XI, Table IWD-2500-1 and IWD-5220 for the piping segments of the service water system located in the confined space of the intake structure bays. By letter dated September 13, 2012, the Nuclear Regulatory Commission (NRC) transmitted a request for additional information (RAI) related to the relief requests. DNC agreed to respond to the RAI by November 9, 2012. Due to outage-related resource demands, the due date for response was extended to December 21, 2012. provides DNC's response to the NRC RAIs for Relief Request RR-04-09 and Attachment 2 provides DNC's response to the RAIs for Relief Request IR-3-15.

If you have any questions regarding this submittal, please contact Wanda Craft at (804) 273-4687.

Sincerely, Leslie N. Hartz 7 Vice President - NuclearSupport Services

Serial No.12-606 RR-04-09 and IR-3-15 Response to RAI Page 2 of 2 Attachments:

1. Relief Request RR-04-09, Response to Request for Additional Information Regarding Use of Alternative Pressure/Flow Testing Requirements for Service Water System Supply Piping .,

2. Relief Request IR-3-15, Response to Request for Additional Information Regarding Use of Alternative Pressure/Flow Testing Requirements for Service Water System Supply Piping Commitments made in this letter: None cc: U.S. Nuclear Regulatory Commission Region I 2100 Renaissance Blvd.

Suite 100 King of Prussia, PA 19406-2713 J. S. Kim Project Manager - Millstone Power Station U.S. Nuclear Regulatory Commission One White Flint North 11555 Rockville Pike Mail Stop 08 C2A Rockville, MD 20852-2738 NRC Senior Resident Inspector Millstone Power Station

Serial No.12-606 Docket No. 50-336 ATTACHMENT I RELIEF REQUEST RR-04-09 RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION REGARDING USE OF ALTERNATIVE PRESSURE/FLOW TESTING REQUIREMENTS FOR SERVICE WATER SYSTEM SUPPLY PIPING MILLSTONE POWER STATION UNIT 2 DOMINION NUCLEAR CONNECTICUT, INC.

Serial No.12-606 Docket No. 50-336 RR-04-09 Response to RAI Attachment 1, Page 1 of 6 By letter dated July 5, 2012, Dominion Nuclear Connecticut, Inc. (DNC) requested relief for Millstone Power Station Unit 2 (MPS2) and Unit 3 (MPS3) from certain examination and testing requirements of Section Xl of the 2004 edition of the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code. Specifically, DNC requested approval of alternative methods for performing the leakage testing as required by ASME Section Xl, Table IWD-2500-1 and IWD-5220 for the piping segments of the service water system located in the confined space of the intake structure bays. By letter dated September 13, 2012, the Nuclear Regulatory Commission (NRC) transmitted a request for additional information (RAI) related to the relief requests. This attachment provides DNC's response to MPS2 relief request RR-04-09.

Unit 2 - Relief Request RR-04-09 RAI U2-1:

Section 1 of the relief request specifies the affected component as pipe segments inside the intake structure bays. Piping and Instrumentation Diagram (P&ID) 25203-26008 Sheet 2 and piping isometric drawings 25203-20150 sheets 679 and 1010 identify the affected piping segments. (1) Confirm that the three service water pumps discharge to the header, 24"-JGD-1, which is divided into two 24"-KE-1 pipe segments which are labeled as Train A and Train B, (2) Are there any boltedjoints or valves in the affected pipe segments? (3) Section 4 discusses the upgrade of the affected pipe segments.

Discuss whether the upgrade was implemented as a result of degradationor preemptive mitigation measures. Discuss any degradationsince the upgrade, (4) Provide the pipe wall thickness and operating temperature and pressure, and (5) Confirm that other than the pipe segments covered under the relief request, the requiredvisual examination will be performed on the remainingportion of 24"-JGD-1and 24"KE-1 when conducting the system leakage test in accordance with the ASME Code, Section Xl, IWD-5000.

DNC Response

1) The three service water pumps discharge to the header 24"-JGD-1 that is divided into "A" and "B" trains and transition into the downstream 24"-KE-1 pipe segments.

2) There are seven bolted flange connections associated with the "A" train and four bolted flange connections associated with the "B" train of the affected pipe segments. There are no valves present within the affected pipe segments.

3) Upgrade of the piping to austenitic stainless steel (AL6XN) was implemented as a result of preemptive mitigation measures. There has been no degradation observed in the affected pipe segments since the upgrade.

Serial No.12-606 Docket No. 50-336 RR-04-09 Response to RAI Attachment 1, Page 2 of 6

4) The nominal wall thickness of the 24"-JGD-1 piping is 0.375 inches. The nominal wall thickness of the 24"-KE-1 piping is 0.410 inches. The normal operating pressure is 45 psig. The normal operating temperature range is 33°F - 75°F.

5) Other than the pipe segments covered under this relief request and the buried piping covered under the previously approved Relief Request RR-04-05, the code-required visual examination will be performed on the remaining portions of 24"-JGD-1 and 24"-KE-1 when conducting the system leakage test in accordance with ASME Code Section Xl, IWD-5000.

RAI U2-2:

Section 4 (lastparagraphon page 2) of the relief request states that in orderto perform visual examination of the affected piping during the system leakage testing, each intake bay needs to be taken out of service along with the associatedservice water system pump, circulating water pumps, screen wash pumps and traveling debris screens. (1)

Explain why the intake structure bays and subject pumps and traveling screens have to be taken out of service and what effect removal of the pump from service has on plant safety, (2) Discuss how performing the visual examination on the affected piping per the ASME Code, IWD-5000 would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety, and (3) Explain why the use of a system leakage test would not provide a compensating increase in the level of safety over the use of an unimpairedflow test DNC Response 1 & 2) Personnel entry into the confined space of the intake bays with equipment operational is considered a personnel safety hazard; therefore, equipment is required to be removed from service and tagged out prior to entry. Additionally, due to the physical configuration of the intake structure, two of the bays require draining to erect the scaffolding needed to access these bays. Draining the bays also requires equipment to be taken out of service to preclude damage to the service water pumps that could occur with the bays drained. Unavailability of safety-related service water pumps puts the station at a greater operational risk since it removes the availability of redundant equipment, introducing a reduction in the safety margin of the plant. Performing the code-required visual examination would require equipment to be taken out of service for an extended period of time while the bays are being drained and scaffolding erected for inspection. Placing the plant in a condition where safety-related service water is out of service for an extended period of time, resulting in increased operational risk, is considered a hardship without a compensating increase in the level of quality and safety.

Serial No.12-606 Docket No. 50-336 RR-04-09 Response to RAI Attachment 1, Page 3 of 6

3) The proposed alternative to test the subject piping segments in conjunction with the quarterly testing of the service water pumps would detect any significant through-wall leakage present in the subject line. That, combined with the periodic internal visual inspection of the piping, provides reasonable assurance of operational readiness and structural integrity. The system leakage test, as required by the ASME Code, requires plant equipment to be taken out of service for an extended period of time, which results in greater operational risk.

Therefore, performance of the system leakage test does not provide a compensating increase in the level of safety when compared to performing the proposed unimpaired flow test.

RAI U2-3:

Section 5.1 of the relief request states that as an alternative to the requirements of the ASME Code, Section Xl, IWD-5220, the licensee will perform periodic flow testing in accordance with Inservice Test (IST) Program surveillance procedures. These surveillance procedures require flow to be measured, recorded and compared to establishedacceptance criteria to provide the assurancethat flow is not impairedduring operation. (1) Confirm that the periodic flow testing is quarterly, (2) Discuss in detail how the flow testing is performed (e.g., where are the measurement instruments located, when is the measurement taken during the test evolution, parameters to be measured, the minimum leak rate that can be detected, how the leakage location is identified, whether the flow rate of 10,300 gpm is the minimum acceptable flow rate, and the accuracy of the instruments), (3) Discuss whether the fluid flow rate will be maintained constant during the flow test. Discuss whether the service water system pumps are centrifugal (with variable speed) or positive displacement (with constant speed). If a leak occurs in the piping system and the centrifugalpumps would increase the flow rate to compensate for the flow loss in order to achieve 10,300 gpm, discuss how the leakage would be detected by the instrumentation.

DNC Response

1) Periodic flow testing is performed quarterly as required by IST Program test surveillance procedures.

2) Flow testing is performed in conjunction with quarterly testing of the service water pumps. During testing of a service water pump, flow is measured using a single flow instrument, located in the Turbine Building, for measurement of total flow. If the flow instrument is not available or does not meet accuracy requirements, the flow is measured using a combined total flow measurement from four heat exchanger flow instruments. During performance of the test, the flow is set to 10,500 gpm nominal (10,300 gpm minimum acceptable flow rate), stabilized, and observed for 2 minutes.

Then, pump vibrations are measured, and pump discharge and suction pressures

Serial No.12-606 Docket No. 50-336 RR-04-09 Response to RAI Attachment 1, Page 4 of 6 are measured and used to determine differential pressure. The flow instruments, in combination, measure within 2% of total flow. This is an accuracy of roughly 200 gpm. If a test is performed and there is 200 gpm leakage or more (unmonitored flow since the flow meters are downstream of the intake structure), this would be observed as reduced, indicated, differential pressure across the service water pump that would be entered into the Corrective Action Program (CAP) and investigated to determine the cause. Operators are in the vicinity of the pumps during the testing.

Any significant flow from leakage will likely be audible to the operators during the testing. Instruments used for differential pressure are also accurate within 2%.

3) Flow rate is required to be held constant for two minutes before readings are taken.

During that time, conditions are observed by the operators and any out-of-ordinary conditions are noted. The pumps are centrifugal and performance follows a typical centrifugal pump curve. If a leak occurs, as indicated above, this would be unmonitored flow and would be observed as reduced differential pressure across the service water pump that would be entered into the CAP and investigated to determine the cause.

RAI U2-4:

The system leakage testing requires coolant flowing through the entire length of service water piping system. However, the relief request applies only to the pipe segments inside the intake bays. (1) If a leakage occurs during a flow test, discuss how the location and amount of leakage is determined without a visual examination of the affected pipe segments. A leakage occurred in the pipe segments not covered by the relief request does not imply that the pipe segment covered by the relief request does not have a leak because a large leak in the pipe segments that is not covered by the relief request may mask the small leak in the affected pipe segment that is covered by the relief request, (2) A flow reduction could be caused by factors other than pipe cracks (e.g., a pump or valve malfunction, valve opening, leaking bolt joints or valves, or foreign object obstruction). Discuss how to determine whether the decreased flow rate is caused by a crack in the affected pipe segments or by other means if the affected pipe segments cannot be examined, and (3) Discuss how the subject piping system is monitored for potentialleakage during normal operation (e.g., alarms in the control room panel? If the flow rate is reduced, what is the set point that will actuate the alarm?).

DNC Response 1&2) Flow testing is performed in conjunction with quarterly testing of the service water pumps. If the pump failed to meet the acceptance criteria during the flow test, the pump would be declared inoperable and entered into the CAP. There are several contributors that could cause the pumps to fail to meet the acceptance criteria.

Investigation to determine the cause of the flow reduction would be identified as part of the CAP plan for this condition. Further corrective actions such as

Serial No.12-606 Docket No. 50-336 RR-04-09 Response to RAI Attachment 1, Page 5 of 6 maintenance of the pump, system walkdowns, etc. would be initiated as required to restore the pump and/or system to operable status. Leakage identified during system walkdowns of accessible piping and components not covered in this request would be evaluated and repaired, as required. If during the investigation, it is suspected that there may be leakage occurring from the subject piping, the necessary actions would be taken to gain access to this normally inaccessible piping for visual inspection, as required.

3) There are no indication alarms in the control room to monitor for reduced flow; however, during normal operation the total service header flow indication for each train is available to be viewed real-time from the plant process computer.

Additionally, the intake structure is walked down daily (once each shift) during plant equipment operator rounds. Any significant flow from leakage will likely be audible to the operators during these rounds.

RAI U2-5:

Section 5.2 (4 th paragraph on page 3) of the relief request states that during IST surveillances, if the minimum flows are not achieved, the pump(s) would be declared inoperable and a condition report initiated in accordance with the Millstone Power Station Corrective Action Program, with further corrective actions, as required, to restore the pump(s) and/or system to an operable status. Section 5.2 further states that the flow rate is specified as 10,300 gallons per minute (gpm). (1) Confirm that when the flow rate is less than 10,300 gpm, the pump will be consideredinoperable and taken out of service, and the service water piping including affected pipe segment will be inspected for leakage.

DNC Response If the flow rate does not meet the minimum acceptance criteria of 10,300 gpm, the service water pump will be declared inoperable and taken out of service as required by the flow test surveillance procedures. This will be entered into the CAP for further investigation and corrective actions. If during the investigation it is suspected that there may be leakage occurring from the subject piping, the necessary actions would be taken to gain access to this normally inaccessible piping for visual inspection, as required.

RAI U2-6:

Section 5.2 (5 th paragraph on page 3) of the relief request states that internal visual inspection is performed on the subject pipe segments periodically during plant refueling outages. (1) Discuss whether the inside surface of the entire length of the Train A and Train B pipe (24"-JGD-1 and 24"-KE-1) is visually inspected during each plant refueling

Serial No.12-606 Docket No. 50-336 RR-04-09 Response to RAI Attachment 1, Page 6 of 6 outage, including the pipe segments covered by the relief request, (2) Discuss how the internal visual inspection is conducted, including the method and acceptance criteria, and (3) Based on discussion in Section 5.2, it appears that Train A and Train B were inspected every other refueling outages (approximate every 3 years), not every refueling outage. Discuss whether this inspection frequency is adequate to ensure the structuralintegrity of the subject pipe segments.

DNC Response

1) The entire inside surface of both 24"-JGD-1 and 24"-KE-1 for each train are visually inspected on an alternating basis each refueling outage. Therefore, each train is inspected every other refueling outage.

2) The internal visual inspection is performed remotely using a robotic crawler unit fitted with a high resolution pan and tilt camera. Any identified conditions such as erosion, corrosion, macrofouling, biofouling, or other degraded piping/liner material condition are evaluated by Engineering for acceptance or corrective actions as required.

3) The internal visual inspection of the subject piping is conducted every other refueling outage. Based on the history of the inspection results, the inspection frequency has been determined to be adequate to ensure structural integrity of the subject piping.

This frequency is consistent with that which would be required for the ASME Code leakage test.

Serial No.12-606 Docket No. 50-423 ATTACHMENT 2 RELIEF REQUEST IR-3-15 RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION REGARDING USE OF ALTERNATIVE PRESSURE/FLOW TESTING REQUIREMENTS FOR SERVICE WATER SYSTEM SUPPLY PIPING MILLSTONE POWER STATION UNIT 3 DOMINION NUCLEAR CONNECTICUT, INC.

Serial No.12-606 Docket No. 50-423 IR-3-15 Response to RAI Attachment 2, Page 1 of 6 By letter dated July 5, 2012, Dominion Nuclear Connecticut, Inc. (DNC) requested relief for Millstone Power Station Unit 2 (MPS2) and Unit 3 (MPS3) from certain examination and testing requirements of Section Xl of the 2004 edition of the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code. Specifically, DNC requested approval of alternative methods for performing the leakage testing as required by ASME Section Xl, Table IWD-2500-1 and IWD-5220 for the piping segments of the service water system located in the confined space of the intake structure bays. By letter dated September 13, 2012, the Nuclear Regulatory Commission (NRC) transmitted a request for additional information (RAI) related to the relief requests. This attachment provides DNC's response to MPS3 relief request IR-3-15.

Unit 3 - Relief Request IR-3-15 RAI U3-1:

Section 1 of the relief request specifies the affected components as "B" Train 30-inch service water system supply piping located in the intake structure bays. However, Section 4 of the relief request describes a pipe segment that runs vertically through the floor of the "B" service water system pump cubicle, travels horizontally through five intake bays, passes through the accessible area of the intake structure chlorine room, and continues underground to the auxiliary building. (1) Clarify why the pipe segment inside the intake structure chlorine room is covered in the relief request if the pipe is accessible for inspection, (2) Discuss the configuration of the pipe segments (e.g.,

whether the inside surface of the subject piping contains lining and coating on outside surface of the pipe as discussed in Relief Request RR-04-09). Are there any bolted joints or valves in the subject pipe segments? (3) Discuss the condition of the subject pipe segments (i.e., any current and previous degradations, upgrades and repairs), (4)

Provide the pipe wall thickness and operating temperature and pressure, and (5) Confirm that other than the pipe segments covered under the relief request, the required visual examination will be performed on the remaining portion of line 3-SWP-030-3-3 when conducting the system leakage test in accordance with the ASME Code, Section X1, IWD-5000.

DNC Response

1) The piping inside the chlorine room is accessible for examination and is not part of this request. This accessible piping was only discussed in the request to provide additional information on the location of the subject piping in relationship to other portions of the service water system.

2) There is no coating or lining on the inside or outside surface of the subject piping.

The material is SB-127 (Monel) which is a highly corrosion resistant material and well suited for this environment. There are no bolted joints or valves in this subject piping segment.

Serial No.12-606 Docket No. 50-423 IR-3-15 Response to RAI Attachment 2, Page 2 of 6

3) There has been no significant degradation, repairs or upgrades to the piping. Minor internal pitting was observed in the early 1990s due to mussel growth issues which were resolved during that timeframe. This pitting has not progressed any further since that time.

4) The nominal wall thickness is 0.375 inches. The normal operating pressure is 44 psig. The normal operating temperature range is 33 0 F - 75 0 F.

5) Other than the pipe segments covered under the relief request, the required visual examination will be performed on the remaining portion of line 3-SWP-030-3-3 when conducting the system leakage test in accordance with the ASME Code, Section Xl, IWD-5000.

RAI U3-2:

Section 4 (4th paragraphon page 2) of the relief request states that in order to perform visual examination of the subject piping during the system leakage testing, each intake bay needs to be taken out of service along with associatedservice water system pump, circulating water pumps, screen wash pumps and traveling debris screens. (1) Explain why the intake bays and subject pumps and traveling screens have to be taken out of service and what effect of these removal on the plant safety, (2) Discuss how performing the visual examination of the subject piping per the ASME Code, IWD-5000 would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety, and (3) Explain why the use of a system leakage test would not provide a compensatingincrease in the level of safety over the use of an unimpairedflow test.

DNC Response 1 & 2) Personnel entry into the confined space of the intake bays with equipment operational is considered a personnel safety hazard; therefore, equipment is required to be removed from service and tagged out prior to entry. Additionally, due to the physical configuration of the intake structure, each of the five bays requires draining to erect the scaffolding needed to access these bays. Draining the bays also requires equipment to be taken out of service to preclude damage to the service water pumps that could occur with the bays drained. Unavailability of safety-related service water pumps puts the station at a greater operational risk since it removes the availability of redundant equipment, introducing a reduction in the safety margin of the plant. Performing the code-required visual examination would require equipment to be taken out of service for an extended period of time while the bays are being drained and scaffolding erected for inspection. Placing the plant in a condition where safety-related service water is out of service for an extended period of time, resulting in increased operational risk, is considered a hardship without a compensating increase in the level of quality and safety.

Serial No.12-606 Docket No. 50-423 IR-3-15 Response to RAI Attachment 2, Page 3 of 6

3) The proposed alternative to test the subject piping segments, in conjunction with the quarterly testing of the service water pumps, would detect any significant through wall leakage if present in the subject line. That, combined with the periodic internal visual inspection of the piping, provides a reasonable assurance of operational readiness and structural integrity. The system leakage test, as required by the ASME Code, requires plant equipment to be taken out of service for an extended period of time, which results in greater operational risk.

Therefore, performance of the system leakage test does not provide a compensating increase in the level of safety when compared to performing the proposed unimpaired flow test.

RAI U3-3:

Section 5.1 (last paragraph on page 2) of the relief request states that periodic flow testing will be performed in accordance with inservice test program surveillance procedures. (1) Confirm that the periodic flow testing is quarterly, and (2) Discuss in detail how the flow testing is performed (e.g., where are the measurement instruments located, when is the measurement taken during the test evolution, parameters measured, the minimum leak rate that can be detected, how the leakage location is identified. Whether 8820 gpm is the minimum acceptable flow rate, and the accuracy of the instruments).

DNC Response

1) Periodic flow testing is performed quarterly for each service water pump as required by IST Program test surveillance procedures. Both the "B" and "D" pumps provide flow to the subject piping of the "B" train header; therefore, this line is subject to two flow tests quarterly.

Flow testing is performed in conjunction with quarterly testing of the service water pumps. Testing is performed by throttling flow through one of two heat exchangers to obtain the reference flow conditions of 8820 to 9180 gpm. Total flow is measured based on the sum of several branch line flow indicators (depending on the heat exchangers in service). Flow is throttled until the reference conditions are reached and then stabilized for two minutes. Flow and pump discharge pressure are recorded. Suction pressure is calculated based on water height in the pump bay.

Pressure is measured at the pump discharge. A total flow indicator is not installed.

Flow in the downstream branch lines is summed to determine the total flow. Because flow is throttled to a repeatable reference value, a specific leak rate is not available.

If the flow rate cannot be achieved or the associated differential pressure at reference conditions is not achieved, the pump test would be considered unsatisfactory. The corrective action program (CAP) would be used to determine the cause of the deviation. The minimum acceptable flow rate is 8820 gpm. Accuracy of the analog

Serial No.12-606 Docket No. 50-423 IR-3-15 Response to RAI Attachment 2, Page 4 of 6 flow and pressure indicators is within +/- 2% of full scale. Digital flow instruments are within 2% of reading.

RAI U3-4:

The system leakage testing requires coolant flowing through the entire length of service water piping system. However, the relief request applies only to the pipe segments inside the intake bays. (1) If a leakage occurs during a flow test, discuss how the location and amount of leakage is determined without a visual examination of the affected pipe segments. A leakage occurred in the pipe segments not covered by the relief request does not imply that the pipe segment covered by the relief request does not have a leak because a large leak in the pipe segments that is not covered by the relief request may mask the small leak in the affected pipe segment that is covered by the relief request, (2) A flow reduction could be caused by factors other than pipe cracks (e.g., a pump or valve malfunction, leaking bolt joints or valves, or foreign object obstruction). Discuss how to determine whether the decreased flow rate is caused by a crack in the affected pipe segments or by other means if the affected pipe segments cannot be examined, and (3) Discuss how the subject piping system is monitored for potential leakage during normal operation (e.g., alarms in the control room panel? If the flow rate is reduced, what is the set point that will actuate the alarm?).

DNC Response 1 & 2) Flow testing is performed in conjunction with quarterly testing of the service water pumps. If the pump failed to meet the acceptance criteria during the flow test, the pump would be declared inoperable and entered into the CAP. There are several contributors that may cause the pumps to fail to meet the acceptance criteria. Investigation to determine the cause of the flow reduction would be identified as part of the CAP plan for this condition. Further corrective actions such as maintenance of the pump, system walkdowns, etc. would be initiated as required to restore the pump and/or system to operable status. Leakage identified during system walkdowns of accessible piping and components not covered in this request would be evaluated and repaired as required. If during the investigation it is suspected that there may be leakage occurring from the subject piping, the necessary actions would be taken to gain access to this normally inaccessible piping for visual inspection, as required.

3) There are no indication alarms in the control room to monitor for reduced flow; however, during normal operation local flow indicators are monitored weekly and trended by Engineering. Any significant decrease in flow would be observed and evaluated. Additionally, the intake structure is walked down daily (once each shift) during plant equipment operator rounds. Any significant flow from leakage of the subject piping will likely be audible to the operator during these rounds.

Serial No.12-606 Docket No. 50-423 IR-3-15 Response to RAI Attachment 2, Page 5 of 6 RAI U3-5:

Section 5.2 of the relief request states that during /ST surveillances,if the minimum flows are not achieved, the pump(s) would be declared inoperable and a condition report initiatedin accordance with the Millstone Power Station Corrective Action Program, with further corrective actions, as required, to restore the pump(s) and/or system to an operable status. Section 5.2 further states that the flow rate is specified as 8,820 gallons per minute (gpm). Confirm that when the flow rate is less than 8,820 gpm, the pump will be considered inoperable and taken out of service, and the service waterpiping including affected pipe segment will be inspected for leakage.

DNC Response If the flow rate does not meet the minimum acceptance criteria of 8,820 gpm, the pump will be declared inoperable and taken out of service as required by the flow test surveillance procedures. This condition will be entered into the CAP for further investigation and corrective actions. If during the investigation it is suspected that there may be leakage occurring from the subject piping, the necessary actions would be taken to gain access to this normally inaccessible piping for visual inspection, as required.

RAI U3-6:

Section 5.2 (3rd paragraphon page 3) of the relief request states that internal visual inspection is periodicallyperformed on the subject pipe segments during plant refueling outages. (1) Discuss whether the inside surface of the entire length of line 3-SWP-030-3-3 is visually inspected, including the pipe segments covered by this relief request, (2)

Discuss how the internal visual inspection is conducted, including the method and acceptance criteria, and (3) Discuss how often the internal visual inspection is performed for the affected pipe segments and whether the inspection frequency is adequate to ensure the structuralintegrity of the affected pipe segments.

DNC Response

1) The entire inside surface of 3-SWP-030-3-3 is visually inspected, including the pipe segments covered by this relief request.

2) The internal visual inspection is performed remotely using a robotic crawler unit fitted with a high resolution pan and tilt camera. Any identified conditions such as erosion, corrosion, macrofouling, biofouling, or other degraded piping material condition are evaluated by Engineering for acceptance or corrective actions as required.

Serial No.12-606 Docket No. 50-423 IR-3-15 Response to RAI Attachment 2, Page 6 of 6

3) The internal visual inspection of the subject piping is conducted every other refueling outage. The inspection frequency has been determined to be adequate to ensure structural integrity of the subject piping based on the history of the inspection results.

This frequency is also consistent with that which would be required for the ASME Code leakage test.