ML20261H598

Response to Request for Additional Information for License Amendment Request to Revise Technical Specification Table 3.3-11, Accident Monitoring Instrumentation

ML20261H598
Person / Time
Site:	Millstone
Issue date:	09/17/2020
From:	Mark D. Sartain Dominion Energy Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
20-310
Download: ML20261H598 (20)

Text

Dominion Energy Nuclear Connecticut, Inc.

5000 Dominion Boulevard, Glen Allen, VA 23060 Dominion DominionEnorgy.com Energy September 17, 2020 U.S. Nuclear Regulatory Commission Serial No.20-310 Attention: Document Control Desk NRA/SS. \

RO Washington, DC 20555 Docket No. 50-336 License No. DPR-65 DOMINION ENERGY NUCLEAR CONNECTICUT, INC.

MILLSTONE POWER STATION UNIT 2 RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION FOR LICENSE AMENDMENT REQUEST TO REVISE TECHNICAL SPECIFICATION TABLE 3.3-11, ACCIDENT MONITORING INSTRUMENTATION By letter dated March 3, 2020 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML20065K976), Dominion Energy Nuclear Connecticut, Inc. (DENC) submitted a license amendment request (LAR) for the Millstone Power Station, Unit No. 2 (MPS2). The proposed license amendment would revise Action 3 in Technical Specification Table 3.3-11, "Accident Monitoring Instrumentation," for monitoring power operated relief valve (PORV) and pressurizer safety valve (PSV) valve position when any of the three valve position monitoring indications (i.e., Instruments 4, 5 and 6) become inoperable.

In an email dated August 3, 2020, the Nuclear Regulatory Commission (NRC) issued a draft request for additional information (RAI) related to the proposed changes to Action 3 in TS Table 3.3-11. On August 13, 2020, the NRC staff conducted a conference call with DENC staff to clarify the request. DENC agreed to respond to the RAI by September 18, 2020. In an email dated August 18, 2020, the NRC transmitted the final version of the RAI (ADAMS Accession No. ML20231A717). provides DENC's response to the RAI. Attachment 2 contains a revised marked-up TS page, and Attachment 3 contains a revised marked-up TS Bases page (For Information Only).

Serial No: 20-310 Docket No. 50-336 Page 2 of 3 Should you have any questions regarding this submittal, please contact Shayan Sinha at (804) 273-4687.

Mark D. Sartain Vice President - Nuclear Engineering & Fleet Support COMMONWEALTH OF VIRGINIA COUNTY OF HENRICO The foregoing document was acknowledged before me, in and for the County and Commonwealth aforesaid, today by Mark D. Sartain, who is Vice President - Nuclear Engineering and Fleet Support of Dominion Energy Nuclear Connecticut, 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 _j_l_~ay of ~~be,2020.

My Commission Expires: Ou v..bf ~ l, Z..o 2. ~

Com yComml Attachments:

1. Response to Request for Additional Information for License Amendment Request to Revise Technical Specification Table 3.3-11, Accident Monitoring Instrumentation

2. Revised Marked-Up Technical Specifications Page

3. Revised Marked-Up Technical Specification Bases Page (For Information Only)

Commitments made in this letter: None

Serial No: 20-310 Docket No. 50-336 Page 3 of 3 cc: U.S. Nuclear Regulatory Commission Region I 2100 Renaissance Blvd, Suite 100 King of Prussia, PA 19406-2713 R. V. Guzman Senior Project Manager - Millstone Power Station U.S. Nuclear Regulatory Commission One White Flint North 11555 Rockville Pike Mail Stop 08 C2 Rockville, MD 20852-2738 NRC Senior Resident Inspector Millstone Power Station Director, Radiation Division Department of Energy and Environmental Protection 79 Elm Street Hartford, CT 06106-5127

Serial No.20-310 Docket No. 50-336 ATTACHMENT 1 RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION FOR LICENSE AMENDMENT REQUEST TO REVISE TECHNICAL SPECIFICATION TABLE 3.3-11, ACCIDENT MONITORING INSTRUMENTATION DOMINION ENERGY NUCLEAR CONNECTICUT, INC.

MILLSTONE POWER STATION UNIT 2

Serial No.20-310 Docket No. 50-336 Attachment 1, Page 1 of 9 By letter dated March 3, 2020 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML20065K976), Dominion Energy Nuclear Connecticut, Inc.

(DENC, the licensee) submitted a license amendment request (LAR) for the Millstone Power Station, Unit No. 2 (MPS2). The proposed license amendment would revise Action 3 in Technical Specification (TS) Table 3.3-11, "Accident Monitoring Instrumentation," for monitoring power operated relief valve (PORV) and pressurizer safety valve (PSV) valve position when any of the three valve position monitoring indications (i.e., Instruments 4, 5 and 6) become inoperable.

In an email dated August 3, 2020, the Nuclear Regulatory Commission (NRC) issued a draft request for additional information (RAI) related to the proposed changes to Action 3 in TS Table 3.3-11. On August 13, 2020, the NRC staff conducted a conference call with DENC staff to clarify the request. DENC agreed to respond to the RAI by September 18, 2020. In an email dated August 18, 2020, the NRC transmitted the final version of the RAI (ADAMS Accession No. ML20231A717).

Background

When valve position indications for Instrument 4 power-operated relief valves (PORVs),

Instrument 5 PORV block valves, or Instrument 6 pressurizer safety valves (PSVs) are inoperable, MPS2 TS Table 3.3-11, Action 3 currently requires control room operators to obtain quench tank temperature, level and pressure information, and monitor discharge pipe temperature once per shift to determine valve position. Action 3 currently requires that all of the identified parameters must be monitored once per shift. The licensee requested to revise Action 3 in Table 3.3-11 to address what the licensee considers as "unnecessary restrictions" for monitoring valve position when any of the three valve position monitoring indications (i.e., Instruments 4, 5 and 6) become inoperable. The licensee proposes the following INSERT to Action 3:

With the number of OPERABLE accident monitoring instrumentation channels less than the required Minimum Channels OPERABLE in Table 3.3-11 and one or more of the above mentioned quench tank parameters or discharge pipe temperatures unavailable, either restore the inoperable accident monitoring instrumentation channel to OPERABLE status within 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br />, or prepare and submit .a Special Report to the Commission pursuant to Specification 6.9.2 within the next 10 days outlining the cause of the ma/function, the plans for restoring the accident monitoring instrumentation channel to OPERABLE status, and any alternate methods in effect for determining if there is a loss of coolant through an inadvertently open valve during the interim.

Regulatory Basis The regulation at 10 CFR 50, Appendix A, General Design Criteria (GOG) 13, Instrumentation and control, requires, in part, that instrumentation shall be provided to monitor variables and systems over their anticipated ranges for normal operation, for anticipated operational occurrences, and for accident conditions as appropriate to assure adequate safety.

Serial No.20-310 Docket No. 50-336 Attachment 1, Page 2 of 9 Generic Letter 80-90 incorporated into one document (NUREG-0737) all TMl-related items approved for implementation by the Commission. Item 11.0.3 of NUREG-0737 requires that reactor coolant system relief and safety valves shall be provided with a positive indication in the control room derived from a reliable *valve position detection device or a reliable indication of flow in the discharge pipe.

Regulatory Guide 1.97, Revision 2, Table 2 specifies that the purpose for monitoring the variable "Primary System Safety Relief Valve Positions (including PORV and code valves) or Flow Through or Pressure in Relief Valve Lines" is to provide operational status and to monitor for loss of coolant.

Request for Additional Information The application does not provide sufficient details for the staff to adequately assess how alternate methods as described can be sufficient to serve as a reliable method to provide position indication in the control room, derived from a reliable valve-position detection device or a reliable indication of flow in the discharge pipe. Based on the proposed wording, it appears that any combination, including all, of the direct parameters could be unavailable and the plant could continue operating indefinitely in this condition. The application provides general examples of alternative, indirect means to diagnose whether there is loss of coolant through a PORV or PSV, so that restorative or mitigative actions can be taken. However, the examples do not appear to be actual alternative means that the licensee is committing to follow using developed procedures accounting for the possible combinations of available direct or indirect parameters. In addition, a technical basis is needed to demonstrate that potential alternative methods and operator diagnostics will be reliable in promptly identifying loss of coolant, consistent with the current actions in Action 3. The following information is needed to verify compliance with the requirements of 10 CFR 50 Appendix A, GOG 13 and NUREG-0737 and conformance with RG 1.97.

RA/ 1 The proposed TS Action 3 appears to allow continued operation for an unspecified interim period with any combination, including all, of the direct parameters being unavailable, with a TS 6.9.2 Special Report submitted to NRG to describe the "alternate method in effect for determining if there is a loss of coolant through an inadvertently open valve." Please confirm if the intent of the TS is to continue plant operations in all possible combinations indefinitely (e.g., for the remainder of the operating cycle and beyond), including potential conditions in which all direct parameters are unavailable. Discuss how the requirements are met in these potential conditions, specifically those in NUREG-0737, Position 11.0.3, to provide positive indication in the control room derived from a reliable valve-position detection device or a reliable indication of flow in the discharge pipe.

Serial No.20-310 Docket No. 50-336 Attachment 1, Page 3 of 9 DENC Response to RAI 1 Attachment 2 of this RAI response letter contains revised marked-up TS pages. This revision adds a requirement to restore the accident monitoring instrumentation channel to OPERABLE status by the end of the next scheduled refueling outage, if the option initiate an alternate method is used. The revision also explains that the option to restore the inoperable accident monitoring instrumentation channel to OPERABLE status within 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> would apply "if repairs are feasible without shutting down." Additionally, the revision makes formatting changes to enhance readability and clarity.

With the revisions in Attachment 2, the proposed TS actions will not allow plant operations in all possible combinations to continue indefinitely, as the accident monitoring instrumentation channel must be restored to OPERABLE status by the end of the next scheduled refueling outage.

The reliability of the direct parameters in detecting gross PORV/PSV leakage is described in Section 3.2 of the LAR submittal, dated March 3, 2020. If a PORV or PSV is opened, one or more of the following alarms would be expected in the control room within seconds:

• High PORV discharge pipe temperature (setpoint at 165 °F)

• High PSV discharge pipe temperature (setpoint at 155 °F)

• High quench tank level (setpoint at 55%)

• High quench tank pressure (setpoint at 10 psig)

• High quench tank temperature (setpoint at 120 °F)

High alarms received on any available discharge pipe temperature indicators would provide clear indication of which PORV or PSV is open. If quench tank parameters are available but discharge pipe temperature readings are not, high alarms for quench tank level, pressure or temperature would indicate that either a PORV or PSV is likely open. If it is determined that a PORV is inadvertently opened or it is unclear whether a PORV or PSV is open, the operator would take action to isolate the PORV and PORV block valve from the control room. If successful closure of a PORV or PORV block valve cannot be confirmed because the position indication was already inoperable, isolation can be recognized by observation of an indicated reduction in available discharge pipe temperature, quench tank parameters, or other expected changes in plant parameters.

Therefore, receipt of alarms from any available direct parameter channels and the corresponding procedural actions can reliably diagnose gross leakage through an inadvertently open PORV or PSV flow path. If a PSV is inadvertently opened or a PORV flow path is inadvertently opened and cannot be isolated, emergency operating procedure (EOP) 2532, Loss of Coolant Accident, would be entered.

Through observation of other normally monitored reactor coolant system (RCS) parameters in the control room, the position of a PORV or PSV can also be reasonably ascertained without any direct parameters. If any of these valves were open, pressurizer pressure would fall significantly, and pressurizer level would rise above 100%. This

Serial No.20-310 Docket No. 50-336 Attachment 1, Page 4 of 9 response is not typical of other events that would result in loss of RCS integrity. During other postulated loss of RCS integrity events, pressurizer level falls or the pressurizer compl<;:ltely empties. If Pressurizer pressure is being maintained with normal pressurizer heater input, all the subject valves must be closed. Containment sump level rise would also be a normal indication of a loss of coolant accident (LOCA) event, whereas during an inadvertently open PSV or PORV event, the containment sump level would be unchanged until the quench tank rupture disk has failed. This would provide reliable indication to the MPS2 operators that gross leakage through an inadvertently open PORV or PSV is causing the reduction of pressurizer pressure. MPS2 operators are trained on these monitoring strategies as part of Initial License Training (ILT) and Licensed Operator Requalification (LOR).

It is noted that during the modes where MPS2 Limiting Condition for Operation (LCO) 3.3.3.8, "Accident Monitoring," is applicable for PORV and PSV valve position (MODES 1, 2, and 3), other MPS2 LCOs would provide operability requirements for the instruments that would typically be utilized as indirect parameters. For example, LCO 3.3.2.1, "Engineered Safety Feature Actuation System Instrumentation," requires a minimum of 3 pressurizer pressure channels to be operable, and reduction of operable channels below this limit would place the unit in LCO 3.0.3. Pressurizer level must remain OPERABLE with readouts displayed external to the control room in MODES 1, 2, and 3 (per LCO 3.3.3.5, "Remote Shutdown Instrumentation") and extended inoperability (7 days or greater) would require the unit to be placed in hot shutdown. The containment sump level monitoring system must remain OPERABLE in MODES 1, 2, 3 and 4 (per LCO 3.4.6, "Leakage Detection Systems), and if the system becomes inoperable, RCS water inventory balances must be performed every 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> or the plant must be placed in cold shutdown.

RA/2 The proposed change could allow MPS2 to enter revised Action 3 without any quench tank parameters and only discharge pipe temperature measurements as the only remaining direct parameter. Justify that this potential condition (i.e., the availability of only the discharge pipe temperature indication) would provide a reliable indication of valve position or flow in the discharge pipe. In the response, please address the following:

• The normal operating temperature ranges for the discharge pipe temperatures compared to anticipated temperatures with allowable amounts of seat leakage and with an open valve.

• Impact of containment ambient temperature on discharge pipe temperatures when containment is at its hottest (i.e. during the summer at 100% power) and the ability to timely detect an open valve.

• How operators distinguish between temperature increases in the discharge piping due to allowable seat leakage and other factors versus an open valve.

• Existing operator actions that are taken when the discharge pipe temperature for one of the valves is rising, prior to, and when reaching, the alarm setpoint. What changes, if any, are there based on the proposed LAR?

Serial No.20-310 Docket No. 50-336 Attachment 1, Page 5 of 9 DENC Response to RAI 2 Allowable Seat Leakage Effects During periods with no active leakage, the temperature of the PSV discharge lines typically ranges between 90-110 °F. A review of historical PSV trends shows that the 'A' PSV typically indicates approximately 10 °F hotter than the temperature indicated on the

'B' PSV. During periods with no active leakage, the temperature on the PORV discharge lines typically ranges between 90-115 °F.

There is no operating experience at MPS2 for seat leakage of the PSVs, however based on actual PORV seat leakage history, the valve discharge line (or tailpipe) temperature associated with minor valve seat leakage generally results in temperatures approximately 10 °F higher than the ambient condition tailpipe temperature. The typical leakage rate associated with initial PORV seat leakage is 0.001 gpm. As observed in historic plant trends, this elevated tailpipe temperature usually increases about 2 °F per day for the typical leakage rate, as steam cutting further degrades the valve seat and stabilizes at approximately 230 °F. As the valve seat is degraded the leakage rate increases at approximately 0.001 gpm/day. During plant operation with a leaking PORV, the Operational Decision Making (ODM) process is utilized to outline specific criteria that require the MPS2 Operators to take action to potentially isolate a leaking PORV. Based on current procedural requirements, this action would be initiated at a quantified leakage rate of 0.14 gpm, allowing sufficient margin to the PORV self-actuation setpoint of 0.28 gpm.

The ARPs applicable to either the PSV or PORV would direct investigation if the valve tailpipe temperatures increased above the alarm setpoint (165 °F for PORV discharge temperature, 155 °F for PSV discharge temperature). In addition, monitoring and trending of the RCS parameters, coupled with daily review of identified RCS leakage, would identify a change in system performance that would direct investigation into the cause of the performance changes.

It should be noted that based upon the piping arrangement in the plant, leakage from the

'B' PORV has the potential to impact the temperature element of the 'B' PSV. This condition is typically validated by isolating the 'B' PORV flowpath (closing its associated PORV block isolation valve) and observing the impact to the 'B' PSV tailpipe temperature.

Containment Ambient Temperature Effects During the peak summer months, containment ambient temperature ranges from 105-110

°F. During the winter months, containment ambient temperature ranges from 95-100 °F.

A review of tailpipe temperature history showed that during the winter months, the PSV tailpipe temperatures ranged between 95 and 105 °F. Over this same period, the PORV tailpipe temperatures typically ranged between 90-110 °F. During the peak summer

Serial No.20-310 Docket No. 50-336 Attachment 1, Page 6 of 9 months when containment temperature was at its highest, the PSV tailpipe temperatures remained within the range of 100 to 110 °F. Over this same period, the PORV tailpipe temperatures typically ranged between 95-120 °F.

Based on these trends, MPS2 Operations can expect peak summer temperatures to result in an increase of approximately 5 °F to the observed PSV and PORV tailpipe temperatures. With the position indication functions for the PORVs and PSVs out of service, this minor deviation in valve tailpipe temperature associated with containment ambient temperature will not challenge the operator's ability to identify gross leakage through an inadvertently open PORV or PSV.

Differentiating Open PORV or PSV from Other Factors The PORV tailpipe temperature associated with seat leakage is dependent on leakage rate, and typically increases gradually as the seat is impacted by steam cutting. As discussed previously, the tailpipe temperature is usually elevated approximately 10 °F when the initial leakage is identified and would stabilize at approximately 230 °F. In the event of an open PORV or PSV, tailpipe temperatures would rapidly rise in excess of 260

°F, coincident with a rapid and significant drop in RCS pressure and a rise in pressurizer level. This same response would be expected in any of the modes where MPS2 TS 3.3.3.8 is applicable (MODES 1, 2, and 3), due to the elevated temperature in the pressurizer steam space.

Operator Actions for Rising Discharge Temperature The MPS2 ARPs for high PORV or PSV discharge temperature alarms instruct the Operators to check available quench tank and position indications for the associated valve. The discharge temperatures would then be monitored for potential instrument error or other unexpected conditions. As previously described, flow in the PORV discharge lines could impact PSV discharge line temperature readings. The ARPs for both high PSV and PORV discharge temperature alarms contain steps to confirm the potential for flow in the PORV discharge line by observing the effects of isolating the PORV and PORV block valves. If these steps determine that the PSV is open or the PORV is open and not capable of being manually cycled, emergency operating procedure (EOP) 2532, Loss of Coolant Accident, would be entered.

The operator actions were not modified as part of the LAR. The same steps would be taken if these alarms are received while an alternate method for detecting gross valve leakage is being utilized (per the proposed TS Required Action).

RA/3 The LAR (Attachment 1, bottom of Page 6 of 11) states, "Since multiple, independent instruments are available to the operator to provide indication of an inadvertently opened PORV or PSV, Joss of one or more of these instruments would not preclude the operator from correctly diagnosing the condition." Discuss what is meant by "independent" as used here to describe the direct parameters. For example, are there any shared power supplies, annunciator equipment, or other single point failure vulnerabilities associated

Serial No.20-310 Docket No. 50-336 Attachment 1, Page 7 of 9 with the PORV, PORV block and PSV position indication equipment and any of the direct parameters?

DENC Response to RAI 3 Power circuitry for the PORV, PORV block and PSV position indication channels, and the direct parameters can be grouped as shown below:

• 120 Volt (V) AC Vital Instrument Panel VA10, Circuit 1 powers the PSV position indicators (ZS-201 & ZS-202) and the associated annunciators.

• 125 V DC Vital Instrument Panel DV10, Circuit 4 powers 'A' PORV (M22-RC-402R/G) Open/Close (GREEN/RED) indication light and associated annunciator

• Vital Motor Control Center (MCC) B51 powers 'A' PORV Block (M22-RC-403R/G)

Open/Close (GREEN/RED) indication light (there is no associated annunciator).

• 125 V DC Vital Instrument Panel DV20, Circuit 4 powers 'B' PORV (M22-RC-404R/G) Open/Close (GREEN/RED) indication light and associated annunciator.

• Vital MCC B61 powers 'B' PORV Block (M22-RC-405R/G) Open/Close (GREEN/RED) indication light (there is no associated annunciator).

• 120 V Regulated AC Instrument Panel VR11, Circuit 67 powers the quench tank pressure and quench tank level instruments (PT-116 & LT-116, respectively). The associated annunciators can be powered by either VR11, Circuit 47 or VR21, Circuit 47.

• 120 V Regulated AC Instrument Panel VR11, Circuit 51 powers the PSV discharge pipe temperature instruments (TE-107 & TE-108), and 'A' PORV (2-RC-402) discharge pipe temperature instrument (TE-106). The associated annunciators can be powered by either VR11, Circuit 47 or VR21, Circuit 47.

• 120 V Regulated AC Instrument Panel VR21, Circuit 51 powers the 'B' PORV (2-RC-404) discharge pipe temperature instrument (TE-114). The associated annunciators can be powered by either VR21, Circuit 47 or VR21, Circuit 47.

• Quench tank temperature sensor (TE-116) must be powered using both VR11 Circuits 51 and 67. The associated annunciators can be powered by either VR11, Circuit 47 or VR21, Circuit 47.

The information above confirms that the loss of any single power circuit would not cause the PORV/PSV position indication and annunciators, PORV block valve position indication, and all direct parameters to be lost. It is noted that the circuits for each of the direct parameter instruments can be powered by more than one AC bus.

Several of the direct parameters are powered through panel VR11. An uninterruptible power supply (UPS) was installed in 2010 for VR11, as well as for VR21. With this design change, the VR11 panel can be powered through Vital 480 V Bus MCC B51 or B52, as well as Non-Vital 480 V Bus MCC B32. VR11 and VR21 have been reliable since the design changes, with the only recorded losses of these panels occurring when the systems were being manipulated during outages or placed in modified maintenance configurations.

Serial No.20-310 Docket No. 50-336 Attachment 1, Page 8 of 9 RA/4 The proposed Action 3 would allow the reduction in operability requirements for direct parameter measurements, and thus, a reduction in defense-in-depth in identifying an open valve when the primary accident monitoring position indication is inoperable. The NRG staff is evaluating whether there will still be reasonable assurance in the positive indication in the control room of a reliable indication of flow in the discharge pipe. Provide a discussion regarding the reliability in determining PORV or PSV status when a reduced number of direct parameter instruments is available (i.e., loss of any quench tank temperature, level, and pressure, and discharge pipe temperatures) and for a total loss of all direct parameters, as allowed for in the proposed Action 3. Describe the surveillance or maintenance that is normally performed for these direct parameter instruments.

Describe the proposed actions that will be taken to restore any of the direct parameters, once the proposed TS revision goes into effect.

DENC Response to RAI 4 Reliability in determining gross leakage through an inadvertently open PORV or PSV when a reduced number of direct parameter instruments are available, and no direct parameters are available, is discussed in the response to the RAI 1 question.

The direct parameter instruments are regularly calibrated, at a frequency determined in accordance with the MPS2 Maintenance Strategy (ER-AA-PRS-1010, "Preventive Maintenance Task Basis and Maintenance Strategy). The current calibration frequency for the PORV and PSV discharge line temperature instruments, and quench tank temperature instrument is every 3 years. The current calibration frequency for the quench tank level and pressure instruments is every 4 refueling outages.

The historical trending data from DENC's PAMS system was reviewed for the direct parameters, and the review concluded that these channels have a high degree of reliability. The UPS installation described in the response to RAI 3, has been successful in improving the reliability of the VR11 or VR21 panels. Since these design changes, concurrent failure of two or more of these instruments has not been observed, except during the outage and maintenance activities that affected the VR11 and VR21 panels, as noted in the RAI 3 response.

The LAR submittal, dated March 3, 2020, includes the statement below in Attachment 1, Section 3.2 (specifically in the second paragraph of the "Conclusions" subsection):

"As noted in the proposed TS Bases revision, once an alternate method is established, the applicable information is obtained once per shift."

Based on this wording in LAR Attachment 1 and the corresponding TS Bases wording in LAR Attachment 3, any readings related to the established alternate method will be surveilled during each shift.

Serial No.20-310 Docket No. 50-336 Attachment 1, Page 9 of 9 DENC must enter a condition report (CR) in the Corrective Action Program whenever any of the direct parameters becomes unavailable. Actions to restore unavailable channels is developed as part of the work order associated with the CR. With the revisions in Attachment 2 of this RAI response, the proposed TS actions will also require the accident monitoring instrumentation channel to be restored to OPERABLE status by the end of the next scheduled refueling outage.

RA/5 While in proposed Action 3, clarify if there are procedures to address the various combinations of available direct and indirect parameters for verifying positive indication in the control room derived from a reliable valve-position detection device or a reliable indication of flow in the discharge pipe. With the current and proposed Action 3, readings are taken once per shift of the direct parameters. Is there a continued or modified requirement to obtain these readings when one or more of the direct parameters are unavailable?

DENC Response to RAI 5 Various existing MPS2 procedures include general steps to confirm whether a PORV or PSV is open, if plant conditions respond unexpectedly (for example, if the pressurizer pressure control system is not operating properly). The procedures do not state that the valve position confirmation should only be performed using valve position indication and direct parameters. If the direct parameters are not available, then the operator would use any available indirect parameters. As noted in the response to RAI 1, MPS2 operators are trained on monitoring strategies using both direct and indirect parameters as part of ILT and LOR.

The RAI 4 response cites LAR Attachment 1 wording and the corresponding TS Bases wording in LAR Attachment 3 related to obtaining information applicable to the established alternate method. As referenced in these LAR sections, DENC intends to retain the requirement to obtain any readings related to the established alternate method during each shift.

Serial No.20-310 Docket No. 50-336 ATT AC HM ENT 2 REVISED MARKED-UP TECHNICAL SPECIFICATIONS PAGE DOMINION ENERGY NUCLEAR CONNECTICUT, INC.

MILLSTONE POWER STATION UNIT 2

Serial No.20-310 Docket No. 50-336 Attachment 2, Page 1 of 3 For Information Only TABLE3.3-11 ACCIDENT MONITORING INSTRUMENTATION Minimum Total No. ChaI111els

, Instrument of Channels OPERABLE ACTION i

>-l

~ssurizer Water Level 2 iv 2. Auxiliary Feedwater Flow Rate 2/S.G 1/S.G.

3. RCS Subcooled/Superheat Monitor 2 2

4. PORV Position Indicator I/valve 1/valve 3 w 5. PORV Block Valve Position I/valve I/valve 3

~ Indicator wI w 6. Safety Valve Position Indicator I/valve I/valve 3 Iv

7. Containment Pressure (Wide Range) 2 4

8. Containment Water Level (Nan-ow Range) I 7##

9. Containment Water Level (Wide Range) 2 4

10. Core Exit TI1ennocouples 4CETs/core quadrant 2CETs in any 5 of2 core quadrants

~

g 11. Main Steam Line Radiation Monitor 3 3 6 f 12. Reactor Vessel Coolant Level 2* I* 8 a

~---------

.

• Achannel is ei~1t (8) sensors in aprobe. Acham1el is OPERABLE if four (4) or more sensors, two (2) or more in the upper four

,~ and two (2) or more in the lower four, are OPERABLE.

-~ ## Refer to ACTION statement in Technical Specification 3.4.6.1.

~}

• ~~

Serial No.20-310 Docket No. 50-336 Attachment 2, Page 2 of 3 M11j1 '.i!Q, '.i!Q15 TABLE 3.3-11 (Continued)

ACTION STATEMENTS ACTION 1 - With the number of OPERABLE channels less than the MINIMUM CHANNELS OPERABLE requirements of Table 3.3-11, either restore the inoperable channel(s) to OPERABLE status within 30 days or be in HOT STANDBY within the next 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />.

ACTION 2 - With the number of channels OPERABLE less than the MINIMUM CHANNELS OPERABLE, determine the subcooling margin once per 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />.

INSERT ACTION 3 - With any individual valve position indicator inoperable, btain quench tank temperature, level and pressure infonnation, and moni r discharge pipe temperature once per shift to detennine valve position. 1is ACTION is not required if the PORV block valve is closed with power removed in accordance with Specification 3.4.3.b or 3.4.3.c. .-f-'

ACTION 4 - a. With the number of OPERABLE accident monitoring instrumentation channels less than the total number of channels shown in Table 3.3-11, restore the inoperable channel(s) to OPERABLE status within 7 days, or submit a special report to the Commission pursuant to Specification 6.9.2 within the next 10 days outlining the cause of the malfunction, the plans for restoring the channel(s) to OPERABLE status, and any alternate methods in

~ ttffect for estiniating the applicable parameter during the interim.

b. With the number of OPERABLE accident monitoring instrumentation channels less than the MINIMUM CHANNELS OPERABLE requirements of Table 3.3-11, restore the inoperable channel(s) to OPERABLE status within 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br />, or submit a special report to the Commission pursuant to Specification 6.9.2 within the next 10 days outlining the cause of the malfunction, the plans for restoring the channel(s) to OPERABLE status, and any alternate methods in ttffect for estimating the applicable parameter during th, inte,im. ~

• MILLSTONE - UNIT 2 3/4 3-33 Amendment No. HG,~. :Wt-,~

Serial No.20-310 Docket No. 50-336 Attachment 2, Page 3 of 3 TS Table 3.3-11 INSERT (Changes from TS INSERT in the LAR Submittal, dated March 3, 2020, are shown in bold font; text additions are underlined, and text deletions are struck through)

With the number of OPERABLE accident monitoring instrumentation channels less than the required Minimum Channels OPERABLE in Table 3.3-11 and one or more of the above mentioned quench tank parameters or discharge pipe temperatures unavailable, either restore the inoperable accident monitoring instrumentation channel to OPERABLE status within 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> if repairs are feasible without shutting down or~

1) Initiate an alternate method for determining if there is loss of coolant through an inadvertently open valve: and

2) Prepare and submit a Special Report to the Commission pursuant to Specification 6.9.2 within the next 10 days outlining the actions taken, the cause of the malfunction, the plans for restoring the accident monitoring instrumentation channel to OPERABLE status; and any alternate methods in effect for determining if there is loss of coolant through an inadvertently open valve during the interim.

3) Restore the accident monitoring instrumentation channel to OPERABLE status by the end of the next scheduled refueling outage.

Serial No.20-310 Docket No. 50-336 ATTACHMENT 3 REVISED MARKED-UP TECHNICAL SPECIFICATIONS BASES PAGE {FOR INFORMATION ONLY)

DOMINION ENERGY NUCLEAR CONNECTICUT, INC.

MILLSTONE POWER STATION UNIT 2

Serial No.20-310 Docket No. 50-336 Attachment 3, Page 1 of 2 For Information Only November 3, 1995 INSTRUMENTATION BASES 3/4.3.3.6 DELETED 3/4.3.3.7 DELETED 3/4.3.3.8 ACCIDENT MONITORING INSTRUMENTATION 111e OPERABILITY of the accident monitoring i.nstnunentation ensures that sufficient information is available on selected plant parameters to monitor and assess these variables during t

and following an accident. This capability is consistent with the recommendations of NUREG-0578, "TMI-2 Lessons Learned Task Force Status Report and Short-Tenn Recommendations".

MILLSTONE - UNIT 2 B 3/43-4 Amendment No.~. 49-, 66, WG, ~ .

191

Serial No.20-310 Docket No. 50-336 Attachment 3, Page 2 of 2 TS Bases 3/4.3.3.8 INSERT Text additions to TS Bases INSERT from the LAR Submittal, dated March 3, 2020, are shown in bold, underlined font)

If a PORV Position Indicator, PORV Block Valve Position Indicator or Safety Valve Position Indicator becomes inoperable, an alternate method can be used for determining if there is loss of reactor coolant through an inadvertently open valve.

Direct parameters (such as quench tank temperature, level and pressure or discharge pipe temperature) can be used to determine if a gross leakage of the reactor coolant is present through an inadvertently opened valve. Primary system and containment instrumentation parameters may also be used to identify a loss of inventory and diagnose whether the source of a leak is through a PORV or Safety Valve flow path. Once an alternate method is established, the applicable information is obtained once per shift. Use of an alternate method requires a special report (pursuant to TS 6.9.2) to be submitted within the next 10 days, if position indication is not restored to OPERABLE status within 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br />. The purpose of the special report is to notify the Commission of the inoperability and describe alternate methods in effect. The special report would also outline the cause of the malfunction and plans for restoring the affected position indicators to operable status. If an alternate method is initiated, OPERABILITY of the accident monitoring instrumentation channel must be restored by the end of the next scheduled refueling outage.