ML12362A012

License Amendment Request to Revise Surveillance Requirement 4.4.3.2 Reactor Coolant System Relief Valves

ML12362A012
Person / Time
Site:	Millstone
Issue date:	12/17/2012
From:	Price J Dominion, Dominion Nuclear Connecticut
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
12-756
Download: ML12362A012 (15)

Text

Dominion Nuclear Connecticut, Inc.'5000 Dominion Boulevard, Glen Allen, VA 23060 o i or Web Address: www.dom.com December 17, 2012 U.S. Nuclear Regulatory Commission Serial No.12-756 Attention:

Document Control Desk NSSL/MLC RO Washington, DC 20555 Docket No. 50-336 License No. DPR-65 DOMINION NUCLEAR CONNECTICUT, INC.MILLSTONE POWER STATION UNIT 2 LICENSE AMENDMENT REQUEST TO REVISE SURVEILLANCE REQUIREMENT 4.4.3.2. REACTOR COOLANT SYSTEM RELIEF VALVES In accordance with the provisions of 10 CFR 50.90, Dominion Nuclear Connecticut, Inc. (DNC) is submitting a license amendment request to revise Technical Specification (TS) 3/4.4.3, Reactor Coolant System Relief Valves, for Millstone Power Station Unit 2 (MPS2). The proposed change would revise Surveillance Requirement (SR) 4.4.3.2 to remove the requirement to perform the quarterly surveillance for a pressurizer power-operated relief valve (PORV) block valve that is being maintained closed in accordance with TS 3.4.3 Action a. The proposed change is consistent with the requirements of the standard Technical Specifications for Combustion Engineering plants (NUREG-1432).

Attachment 1 to this letter describes the proposed changes and provides justification for the changes. Attachments 2 and 3 provide the marked-up TS and TS Bases pages, respectively.

The marked-up TS Bases pages are provided for information only. The changes to the affected TS Bases pages will be incorporated in accordance with the TS Bases Control Program when this amendment request is approved.The proposed amendment does not involve a Significant Hazards Consideration under the standards set forth in 10 CFR 50.92. The Facility Safety Review Committee has reviewed and concurred with the determinations herein.Issuance of this amendment is requested by December 18, 2013, with the amendment to be implemented within 60 days.In accordance with 10 CFR 50.91(b), a copy of this license amendment request is being provided to the State of Connecticut.

Serial No: 12-756 Docket No. 50-336 SR 4.4.3.2, RCS Relief Valves Page 2 of 3 Should you have any questions in regard to this submittal, please contact Wanda Craft at (804) 273-4687.Sincerely, J.A rice Vice President

-Nuclear Engineering 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 Nuclear Connecticut, Inc. He has affirmed before me that he is duly authorized to execute and file the foregoing document on 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 [7-thday , 2012.My Commission Expires: 11cCer 6 I ,Qc/," N o t a r y P u b l i c -------.. .: .....l CRAIG D SLY* ,I ~Notary Public "i' ; .Commonwealth of Virginia I Reg. # 7518653 My Commission Expires December 31, 20+/-.Attachments:

1. Evaluation of Proposed License Amendment 2. Marked-Up Technical Specification Page 3. Marked-Up Technical Specification Bases Page Commitments made in this letter: None Serial No: 12-756 Docket No. 50-336 SR 4.4.3.2, RCS Relief Valves Page 3 of 3 cc: U.S. Nuclear Regulatory Commission Region I 2100 Renaissance Blvd, Suite 100 King of Prussia, PA 19406-2713 James S. Kim NRC Project Manager U.S. Nuclear Regulatory Commission One White Flint North Mail Stop 08 C2A 11555 Rockville Pike 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.12-756 Docket No. 50-336 ATTACHMENT 1 EVALUATION OF PROPOSED LICENSE AMENDMENT J DOMINION NUCLEAR CONNECTICUT, INC.MILLSTONE POWER STATION UNIT 2 Serial No.12-756 Docket No. 50-336 SR 4.4.3.2, RCS Relief Valves Attachment 1, Page 1 of 7 EVALUATION OF PROPOSED LICENSE AMENDMENT

1.0 INTRODUCTION

In accordance with the provisions of 10 CFR 50.90, Dominion Nuclear Connecticut, Inc., (DNC) is submitting a license amendment request to revise Technical Specification (TS)3/4.4.3, Reactor Coolant System Relief Valves, for Millstone Power Station Unit 2 (MPS2). The proposed change would revise Surveillance Requirement (SR) 4.4.3.2 to remove the requirement to perform the quarterly surveillance for a pressurizer power-operated relief valve (PORV) block valve that is being maintained closed in accordance with TS 3.4.3 Action a. The proposed change is consistent with the requirements of the standard Technical Specifications for Combustion Engineering (CE) plants (NUREG-1432).On December 11, 2012 at 1421 hours0.0164 days <br />0.395 hours <br />0.00235 weeks <br />5.406905e-4 months <br />, MPS2 entered TS 3.4.3 Action a when the 'B'PORV block valve (2-RC-405) was closed due to seat leakage on the 'B' PORV (2-RC-404).

2.0 PROPOSED CHANGE

S DNC proposes to revise SR 4.4.3.2 to replace the specific exceptions to TS 3.4.3 Actions b or c with a statement that a pressurizer PORV block valve closed in accordance with any of the applicable actions of TS 3.4.3 would be excluded from the quarterly surveillance specified by SR 4.4.3.2.The proposed change to the MPS2 TSs is shown below: Proposed Change to SR 4.4.3.2 (Deleted text is struck-through and added text is italicized and bold)Each block valve shall be demonstrated OPERABLE once per 92 days by operating the valve through one complete cycle of full travel. This demonstration is not required if a PORV block valve is closed and power removed to meet. in accordance with the ACTIONS of Specification 3.4.3 bOFr--.A mark-up of the proposed TS page is provided in Attachment

2. Attachment 3 contains associated TS Bases mark-ups.

These TS Bases mark-ups are similar to the CE standard TSs Bases for the block valve surveillance and are provided for information only.

Serial No.12-756 Docket No. 50-336 SR 4.4.3.2, RCS Relief Valves Attachment 1, Page 2 of 7

3.0 BACKGROUND

MPS2 has two pressurizer PORVs. The PORVs are pilot-assisted, solenoid-operated relief valves which respond to a signal from a pressure-sensing system or to manual control. Plant operators use the PORVs to depressurize the reactor coolant system (RCS) in response to certain plant transients if pressurizer spray is not available.

The PORVs are also used for low temperature overpressure protection (LTOP) when the RCS is cooled down to or below 275 0 F. TS 3.4.9.3 applies to the use of the PORVs for LTOP and is not affected by this proposed change.Normally-open, motor-operated block valves are located between the pressurizer and the PORVs. Plant operators use the block valves to isolate the PORVs in case of excessive leakage or a stuck-open PORV. The block valves can be manually closed from the control room. A stuck-open PORV is, in effect, a small break loss-of-coolant accident (SBLOCA).

As such, closing the block valve terminates the RCS depressurization and coolant inventory loss. The series arrangement of the PORVs and their block valves permits performing surveillances on the block valves during power operation.

The PORVs, block valves, and associated controls are powered from vital buses that normally receive power from offsite power sources. They are also capable of being powered from emergency power sources in the event of a loss-of-offsite power.The operability of the PORVs and block valves is determined on the basis of their capability to perform the following functions:

1. Control RCS pressure below the setting of the pressurizer code safety valves.2. Maintain the integrity of the RCS pressure boundary.

This is a function that is related to controlling identified leakage and ensuring the ability to detect unidentified RCS pressure boundary leakage.3. Provide manual control of the block valve to: 1) unblock an isolated PORV to allow it to be used for manual control of RCS pressure, 2) isolate a PORV with excessive seat leakage and, 3) isolate a stuck-open PORV.4. Vent non-condensible gases from the pressurizer during post accident conditions.

With one or both PORVs inoperable and capable of being manually cycled, either the PORV(s) must be restored, or the flow path(s) isolated within one hour. The block valve(s) should be closed, but the power must be maintained to the associated block valve(s), since removal of power would render the block valve(s) inoperable.

PORV inoperability may be due to seat leakage, instrumentation problems, automatic control problems, or other causes that do not prevent manual use and do not create a possibility Serial No.12-756 Docket No. 50-336 SR 4.4.3.2, RCS Relief Valves Attachment 1, Page 3 of 7 for a SBLOCA. Although the PORV(s) may be designated inoperable, it may be able to be manually opened and closed and in this manner can be used to perform its function.Operation of the plant may continue with the PORV(s) in this inoperable condition for a limited period of time not to exceed the next refueling outage, so that maintenance can be performed on the PORV(s) to eliminate the degraded condition.

The PORVs should normally be available for automatic mitigation of overpressure events when the plant is at power.The PORV is accessible for pressure control when power is maintained to the closed block valve.With one PORV inoperable and not capable of being manually cycled, it is necessary to either restore the PORV to operable status within the allowed outage time of one hour or isolate the flow path by closing and removing the power to the associated block valve.The PORV must be restored to operable status within the following 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> or cooldown to MODE 4 is required.If more than one PORV is inoperable and not capable of being manually cycled, it is necessary to either restore at least one valve within the allowed outage time of one hour or isolate the flow paths by closing and removing the power to the associated block valves and cooldown the RCS to MODE 4.4.0 TECHNICAL ANALYSIS The pressurizer PORVs are designed to actuate at the high RCS pressure trip setpoint.They are designed to fail to the closed position on a loss of power. The pressurizer PORVs are not required to open to prevent overpressurization of the RCS. The pressurizer safety valves, by themselves, are sized to relieve enough steam to prevent overpressurization of the primary system. Therefore, a loss of pressurizer PORV automatic control and the subsequent failure of the PORVs to open may result in higher RCS pressures, but will not cause overpressurization of the RCS.With one PORV inoperable due to excessive seat leakage, TS 3.4.3 allows continued operation of the unit provided the associated block valve is closed with power maintained to the block valve. Although inoperable due to excessive seat leakage, the PORV remains capable of being manually operated.When a PORV block valve has been closed due to PORV seat leakage, and the block valve is subsequently reopened, momentary opening of the PORV has been noted. The Combustion Engineering Bases for SR 3.4.11.1 in NUREG-1432 states, "Opening the block valve in this condition

[the block valve having been closed due to an inoperable PORV] increases the risk of an unisolable leak from the RCS since the PORV is already inoperable." Momentary opening of the PORV could be a precursor to an unisolable leak in the RCS should the block valve fail to close.

Serial No.12-756 Docket No. 50-336 SR 4.4.3.2, RCS Relief Valves Attachment 1, Page 4 of 7 The requirement to open the block valve in this condition represents an unnecessary challenge to the integrity of the RCS pressure boundary and increases the potential for further degradation to the PORV.Not performing the surveillance on the PORV block valve is not significant to assuring the block valve is capable of opening to allow operation of the PORV. The block valves have been shown to be reliable by operating experience and are also subject to the testing requirements of the motor-operated valve testing program.The proposed changes are consistent with CE standard TSs and willeliminate the requirement to challenge the integrity of the PORV and the RCS pressure boundary.5.0 REGULATORY ANALYSIS 5.1 No Significant Hazards Consideration The NRC has provided standards for determining whether a significant hazards consideration exists as stated in 10 CFR 50.92(c).

A proposed arnendment to an operating license for a facility involves no significant hazards consideration if operation of the facility in accordance with a proposed amendment would not: 1) involve a significant increase in the probability or consequences of an accident previously evaluated; or 2)create the possibility of a new or different kind of accident from any accident previously evaluated; or 3) involve a significant reduction in a margin of safety. DNC has evaluated whether or not a significant hazards consideration (SHC) is involved with the proposed change. A discussion of these standards as they relate to this change request is provided below.Criterion 1 Will operation of the facility in accordance with the proposed change involve a significant increase in the probability or consequences of an accident previously evaluated?

Response:

No.The block valve for the pressurizer PORV is not a potential accident initiator.

Therefore, not requiring a surveillance of the block valve while it is being used to isolate its associated PORV will not increase the probability of an accident previously evaluated.

Not requiring the surveillance of the block valve may slightly reduce the probability of a loss of coolant accident from a stuck open PORV since it will eliminate the challenge to the PORV from the pressure transient that results from cycling the block valve.The PORVs or the PORV block valves are not credited in the MPS2 Final Safety Analysis Report (FSAR), Chapter 14, "Safety Analysis," for event mitigation.

If pressurizer spray is not available or is not effective, either one of the two pressurizer Serial No.12-756 Docket No. 50-336 SR 4.4.3.2, RCS Relief Valves Attachment.1, Page 5*of 7 PORVs may be manually actuated to depressurize the RCS in response to certain transients.

Not performing the surveillance on the block valve is not relevant to the primary system for depressurizing the RCS (pressurizer spray). The block valves have been demonstrated by operating experience to be reliable and are also subject to the motor-operated valve testing program. Consequently, the proposed change does not significantly reduce the confidence that the block valve can be opened to permit manual actuation of the PORV to depressurize the RCS.Therefore, the proposed change does not involve a significant increase in the probability or consequences of an accident previously evaluated.

Criterion 2 Will operation of the facility in accordance with this proposed change create the possibility of a new or different kind of accident from any accident previously evaluated?

Response:

No.The proposed change only affects the performance of the surveillance test for the block valve and does not involve any physical alteration of plant equipment or introduce any operating configurations not previously evaluated.

The pressurizer PORV block valves provide isolation for a postulated stuck-open or leaking PORV. Isolation is satisfied with the block valve closed in accordance with SR 4.4.3.2. PORV block valve closure is not credited in FSAR Chapter 14 for inadvertent opening of the PORV event mitigation.

Therefore, the proposed changes do not create the possibility of a new-or different kind of accident from any previously evaluated.

Criterion 3 Will operation of the facility in accordance with this proposed change involve a significant reduction in the margin of safety?Response:

No.Margin of safety is related to the confidence in the ability of the fission product barriers to perform their design functions during and following an accident.

These barriers include the fuel cladding, the reactor coolant system, and the containment system. These barriers are not significantly affected by the changes proposed herein. The margin of safety is established through the design of the plant structures, systems, and components, the parameters within which the plant is operated, and the establishment of setpoints for the actuation.

of equipment relied upon to respond to an event, and thereby protect the fission product barriers.

The proposed change to the surveillance requirement for the pressurizer PORV block valve does not affect the assumptions in any accident analysis.

Serial No.12-756 Docket No. 50-336 SR 4.4.3.2, RCS Relief Valves Attachment 1, Page 6 of 7 Therefore, the proposed change does not involve a significant reduction in a margin of safety.Conclusion Based on the above, DNC concludes that the proposed changes do not represent a significant hazards consideration under the standards set forth in 10 CFR 50.92(c).5.2 Applicable Regulatory Requirements/Criteria Title 10 of the Code of Federal Regulations (10 CFR), Section 50.36(c)(3), states that,"Surveillance requirements

[SRs] are requirements relating to test, calibration, or inspection to assure that the necessary quality of systems and components is maintained..." Currently, the quarterly (92-day) PORV block valve surveillance, SR 4.4.3.2, is required to be performed unless one or both block valves are closed due to an inoperable PORV(s) that is not capable of being manually cycled (Actions b or c of TS 3.4.3).NUREG-1432, Revision 4.0, Standard Technical Specifications for Combustion Engineering Plants, excludes licensees from performing the quarterly block valve surveillance specified in SR 3.4.11.1 when a pressurizer PORV block valve is closed in accordance with any of the applicable actions of TS 3.4.11.NUREG 0737, Section ll.B.1 and 10 CFR 50.46a requires that each applicant and licensee shall install RCS and reactor vessel head high point vents remotely operated from the control room to vent noncondensible gases from the RCS which may inhibit core cooling during natural circulation.

6.0 ENVIRONMENTAL CONSIDERATION DNC has determined that the proposed amendment would change a requirement with respect to installation or use of a facility component located within the restricted area, as defined by 10 CFR 20, or an inspection or surveillance requirement.

DNC has evaluated the proposed amendment and has determined that it does not involve (i) a significant hazards consideration, (ii) a significant change in the types or significant increase in the amounts of any effluent that may be released offsite, or (iii) a significant increase in individual or cumulative occupational radiation exposure.

Accordingly, the proposed amendment meets the eligibility criterion for categorical exclusion set forth in 10 CFR 51.22(c)(9).

Therefore, pursuant to 10 CFR 51.22(b), no environmental impact statement or environmental assessment need to be prepared in connection with the proposed amendment.

Serial No.12-756 Docket No. 50-336 SR 4.4.3.2, RCS Relief Valves Attachment 1, Page 7 of 7

7.0 CONCLUSION

Based on the considerations discussed above, (1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, (2) such activities will be conducted in compliance with the Commission's regulations, and (3) the issuance of the amendment will not be inimical to the common defense and security or to the health and safety of the public.8.0 PRECEDENTS The proposed change to SR 4.4.3.2 is similar to the license amendment request submitted by South Texas Project (STP) Nuclear Operating Company on September 30, 2004 for STP Units 1 and 2. This request was approved by the NRC on October 21, 2004 (ADAMS Accession No. ML042800363).

The change to the STP PORV block valve SR was based on NUREG-1431 and TSTF-284, Rev. 3, as it applied to Westinghouse plants. The change to the STP PORV block valve SR was consistent with the PORV block valve SR contained in NUREG-1432 for CE plants. The Bases sections in NUREG-1431 and 1432 were also modified by TSTF-284, Rev 3 to provide the bases for not cycling block valves that have been closed to comply with action statements.

9.0 REFERENCES

9.1 Technical Specification Task Force Traveler TSTF-284-A, Add "Met vs. Perform" to Specification 1.4, Frequency, Revision 3.9.2 NUREG-1432, Revision 4.0, Standard Technical Specifications, Combustion Engineering Plants, Volume 1, Specifications.

9.3 NUREG-1431, Standard Technical Specifications, Westinghouse Plants, Revision 4.0, Volume 1, Specifications.

Serial No.12-756 Docket No. 50-336 ATTACHMENT 2 MARKED-UP TECHNICAL SPECIFICATION PAGE DOMINION NUCLEAR CONNECTICUT, INC.MILLSTONE POWER STATION UNIT 2 REACTOR COOLANT SYSTEM SURVEILLANCE REQUIREMENTS 4.4.3.1 In addition to the requirements of Specification 4.0.5, each PORV shall be demonstrated OPERABLE: a. Once per 31 days by performance of a CHANNEL FUNCTIONAL TEST, excluding valve operation, and b. Once per 18 months by performance of a CHANNEL CALIBRATION.

c. Once per 18 months by operating the PORV through one complete cycle of full travel at conditions representative of MODES 3 or 4.4.4.3.2 Each block valve shall be demonstrated OPERABLE once per 92 days by operating the valve through one complete cycle of full travel. This demonstration is not required if a PORV block valve is closed and pcwer rcmc,,'cd tc me, ct Specification 3.4.3 b @I-e.t+lin accordance with the ACTIONS of I Amendment No. 66, 68, 85, 3Q MILLSTONE

-UNIT 2 3/4 4-3a Serial No.12-756 Docket No. 50-336 ATTACHMENT 3 MARKED-UP TECHNICAL SPECIFICATION BASES PAGE (FOR INFORMATION ONLY)DOMINION NUCLEAR CONNECTICUT, INC.MILLSTONE POWER STATION UNIT 2 For Information Only 05 MP2 009 3/4.4 REACTOR COOLANT SYSTEM BASES stuck open PORV at a time that the block valve is inoperable.

This may be accomplished by various methods. These methods include, but are not limited to, placing the NORMAL/ISOLATE switch at the associated Bottle Up Panel in the "ISOLATE" position or pulling the control power fuses for the associated PORV control circuit.Although the block valve may be designated inoperable, it may be able to be manually opened and closed and in this manner can be used to perform its function.

Block valve inoperability may be due to seat leakage, instrumentation problems, or other causes that do not prevent manual use and do not create a possibility for a small break LOCA. This condition is only intended to permit operation of the plant for a limited period of time. The block valve should normally be available to allow PORV operation for automatic mitigation of overpressure events. The block valves must be returned to OPERABLE status prior to entering MODE 3 after a refueling outage.If more than one PORV is inoperable and not capable of being manually cycled, it is necessary to either restore at least one valve within the completion time of 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> or isolate the flow path by closing and removing the power to the associated block valve and cooldown the RCS to MODE 4.SURVEILLANCE REQUIREMENT 4.4.3.1 .c requires operating each PORV through one complete cycle of full travel at conditions representative of MODES 3 or 4. This is normally performed in MODE 3 or 4 as the unit is descending in power to commence a refueling outage.This test will normally be a static test, whereby a PORV will be exposed to MODE 3 or 4 temperatures, the block valve closed, and the PORV tested to verify it strokes through one complete cycle of full travel. PORV cycling demonstrates its function.

The Frequency of 18 months is based on a typical refueling cycle and industry accepted practice.

SURVEILLANCE REQUIREMENT 4.4.3.1.c is consistent with the NRC staff position outlined in Generic Letter 90-06, which requires that the 18-month PORV stroke test be performed at conditions representative of MODE 3 or 4. Testing in the manner described is also consistent with the guidance in NUREG 1482, "Guidelines for Inservice Testing at Nuclear Power Plants," Section 4.2.10, that describes the PORVs function during reactor startup and shutdown to protect the reactor vessel and coolant system from low-temperature overpressurization conditions, and indicates they should be exercised before system conditions warrant vessel protection.

If post maintenance retest is warranted, the affected valve(s) will be stroked under ambient conditions while in Mode 5, 6, or defueled.

The actual stroke time in the open and close direction will be measured, recorded and compared to the test results obtained during pre-installation testing to assess acceptability of the affected valve(s).SURVEILLANCE REQUIREMENT 4.4.3.2 verifies that a block valve(s) can be closed if necessary.

This SURVEILLANCE REQUIREMENT is not required to be performed with the block valve(s) closed in accordance with the ACTIONS of TS 3.4.3. Opening the block valves(s) in this condition increases the risk of an unisolable leak from the RCS since the PORV(s) is already inoperable.

MILLSTONE

-UNIT 2 B 3/4 4-2a Amendment No. 22, 3-7, 5-2, 66, 9-7, 4-8-, 24--, 264-,