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==2.0 REGULATORY EVALUATION== | ==2.0 REGULATORY EVALUATION== | ||
In Title 10 of the Code of Federal Regulations (10 CFR), Section 50.36, "Technical specifications," the NRC established its regulatory requirements related to the content of TSs. Pursuant to 1 O CFR 50.36(c), TSs are required to include items in the following five specific categories related to station operation: | In Title 10 of the Code of Federal Regulations (10 CFR), Section 50.36, "Technical specifications," the NRC established its regulatory requirements related to the content of TSs. Pursuant to 1 O CFR 50.36(c), TSs are required to include items in the following five specific categories related to station operation: | ||
(1) safety limits, limiting safety system settings, and limiting control settings; (2) limiting conditions for operation (LCOs); (3) SRs; (4) design features; and (5) administrative controls. | (1) safety limits, limiting safety system settings, and limiting control settings; (2) limiting conditions for operation (LCOs); (3) SRs; (4) design features; and (5) administrative controls. | ||
Enclosure 2 In 10 CFR 50.36(c)(3), it states that, "surveillance requirements are requirements related to test, calibration, or inspection to assure that the necessary quality of systems and components is maintained, that facility operation will be within safety limits, and that the limiting conditions for operation will be met." The MPS3 pressurizer PORV block valves are the subject of LCOs and SRs in TS 3/4.4.4, "Relief Valves." At the present time, the pressurizer PORV block valve test specified in SR 4.4.4.2, is required to be performed at the frequency specified in the Surveillance Frequency Control Program unless the pressurizer PORV block valve is closed for reasons other than excessive PORV seat leakage (i.e., Actions b. or c. of TS 3.4.4). The TS Task Force (TSTF) Traveler No. 284 (TSTF-284), Revision 3, provides guidance for the extension of the range of circumstances under which the quarterly testing of the pressurizer PORV block valve is not required in order to meet the Actions specified in TS 3.4.4. In response to the DNC LAR, the NRC staff considered whether this aspect of TSTF-284, Revision 3, may be applied to MPS3. The NRC staff also considered relevant information in the MPS3 Updated Final Safety Analysis Report (UFSAR) and TSs. In NUREG-1431, Revision 4, Standard Technical Specifications (STS) for Westinghouse Plants, and NUREG-1432, Revision 4, STS for Combustion Engineering Plants, licensees are excluded from performing the pressurizer PORV block valve surveillance specified in STS SR 3.4.11.1 when the block valve is closed in accordance with any of the actions of STS TS 3.4.11. In 10 CFR 50.46a, and as explained in NUREG-0737, it is required that each nuclear power reactor be provided with high point vents for the reactor coolant system, for the reactor vessel head, and for other systems required to maintain adequate core cooling if the accumulation of noncondensible gases would cause the loss of function of these systems. The criteria for acceptable venting systems include that high point vents must be remotely operated from the control room. The purpose of such systems is to vent noncondensible gases from the RCS which may inhibit core cooling during natural circulation. | Enclosure 2 In 10 CFR 50.36(c)(3), it states that, "surveillance requirements are requirements related to test, calibration, or inspection to assure that the necessary quality of systems and components is maintained, that facility operation will be within safety limits, and that the limiting conditions for operation will be met." The MPS3 pressurizer PORV block valves are the subject of LCOs and SRs in TS 3/4.4.4, "Relief Valves." At the present time, the pressurizer PORV block valve test specified in SR 4.4.4.2, is required to be performed at the frequency specified in the Surveillance Frequency Control Program unless the pressurizer PORV block valve is closed for reasons other than excessive PORV seat leakage (i.e., Actions b. or c. of TS 3.4.4). The TS Task Force (TSTF) Traveler No. 284 (TSTF-284), Revision 3, provides guidance for the extension of the range of circumstances under which the quarterly testing of the pressurizer PORV block valve is not required in order to meet the Actions specified in TS 3.4.4. In response to the DNC LAR, the NRC staff considered whether this aspect of TSTF-284, Revision 3, may be applied to MPS3. The NRC staff also considered relevant information in the MPS3 Updated Final Safety Analysis Report (UFSAR) and TSs. In NUREG-1431, Revision 4, Standard Technical Specifications (STS) for Westinghouse Plants, and NUREG-1432, Revision 4, STS for Combustion Engineering Plants, licensees are excluded from performing the pressurizer PORV block valve surveillance specified in STS SR 3.4.11.1 when the block valve is closed in accordance with any of the actions of STS TS 3.4.11. In 10 CFR 50.46a, and as explained in NUREG-0737, it is required that each nuclear power reactor be provided with high point vents for the reactor coolant system, for the reactor vessel head, and for other systems required to maintain adequate core cooling if the accumulation of noncondensible gases would cause the loss of function of these systems. The criteria for acceptable venting systems include that high point vents must be remotely operated from the control room. The purpose of such systems is to vent noncondensible gases from the RCS which may inhibit core cooling during natural circulation. | ||
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1 The failure position of the pressurizer PORV is closed. The pressurizer is equipped with two PORVs, each of which has a block valve to be closed in the event that excessive PORV seat leakage is detected. | 1 The failure position of the pressurizer PORV is closed. The pressurizer is equipped with two PORVs, each of which has a block valve to be closed in the event that excessive PORV seat leakage is detected. | ||
The pressurizer PORVs are not required to open in order to prevent the overpressurization of the RCS. The three pressurizer safety valves, by themselves, are sized to relieve enough steam to prevent an overpressurization of the RCS. Therefore, a loss of pressurizer PORV automatic control (or the closing of the associated block valves) and the subsequent failure of 1 See MPS3 UFSAR Section 5.2.2.11, "RCS Pressure Control during Low Temperature Operation." the PORVs to open will result in higher reactor coolant pressures, but will not cause any overpressurization event. The opening of the pressurizer PORV is a conservative assumption for the departure from nucleate boiling limited transients by tending to keep the primary system pressure down. As discussed in MPS3 UFSAR Section 5.4.7.2.3.5, "Safety Grade Cold Shutdown," depressurization to achieve cold shutdown would be accomplished by the pressurizer PORVs if pressurizer spray is unavailable or not effective. | The pressurizer PORVs are not required to open in order to prevent the overpressurization of the RCS. The three pressurizer safety valves, by themselves, are sized to relieve enough steam to prevent an overpressurization of the RCS. Therefore, a loss of pressurizer PORV automatic control (or the closing of the associated block valves) and the subsequent failure of 1 See MPS3 UFSAR Section 5.2.2.11, "RCS Pressure Control during Low Temperature Operation." the PORVs to open will result in higher reactor coolant pressures, but will not cause any overpressurization event. The opening of the pressurizer PORV is a conservative assumption for the departure from nucleate boiling limited transients by tending to keep the primary system pressure down. As discussed in MPS3 UFSAR Section 5.4.7.2.3.5, "Safety Grade Cold Shutdown," depressurization to achieve cold shutdown would be accomplished by the pressurizer PORVs if pressurizer spray is unavailable or not effective. | ||
However, as indicated in the LAR, not performing the surveillance on the block valve does not significantly reduce the assurance that the block valve is capable of opening to allow operation of the pressurizer PORV. 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 amendment does not significantly reduce the confidence that the block valves can be opened in order to permit automatic or manual actuation of the pressurizer PORVs to depressurize the RCS. The current SR 4.4.4.2 requires that the pressurizer PORV block valves be subjected to an operability test, with a frequency as specified in the Surveillance Frequency Control Program, by operating each valve through one complete cycle of full travel unless (1) one block valve has been closed for reasons of PORV inoperability due to causes other than excessive seat leakage (i.e., ACTION b. of TS 3.4.4) or (2) both block valves have been closed for reasons of PORV inoperability due to causes other than excessive seat leakage (i.e., ACTION c. of TS 3.4.4). The licensee's proposed change to SR 4.4.4.2 would expand the range of conditions under which periodic operability testing of block valves for the pressurizer PORVs would be unnecessary to include any situation where a block valve is closed due to any Action in TS 3.4.4, which would include cases in which the pressurizer PORV block valve has been closed due to excessive seat leakage. As noted in Attachment 1 to the licensee's LAR, when a pressurizer PORV block valve has been closed due to excessive seat leakage, and the block valve is subsequently reopened, momentary opening of the PORV has been noted. This observed PORV behavior is consistent with the Westinghouse Bases for STS SR 3.4.11.1, in TSTF-284, Revision 3, which the licensee states in the LAR as: "Opening the block valve in this condition | However, as indicated in the LAR, not performing the surveillance on the block valve does not significantly reduce the assurance that the block valve is capable of opening to allow operation of the pressurizer PORV. 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 amendment does not significantly reduce the confidence that the block valves can be opened in order to permit automatic or manual actuation of the pressurizer PORVs to depressurize the RCS. The current SR 4.4.4.2 requires that the pressurizer PORV block valves be subjected to an operability test, with a frequency as specified in the Surveillance Frequency Control Program, by operating each valve through one complete cycle of full travel unless (1) one block valve has been closed for reasons of PORV inoperability due to causes other than excessive seat leakage (i.e., ACTION b. of TS 3.4.4) or (2) both block valves have been closed for reasons of PORV inoperability due to causes other than excessive seat leakage (i.e., ACTION c. of TS 3.4.4). The licensee's proposed change to SR 4.4.4.2 would expand the range of conditions under which periodic operability testing of block valves for the pressurizer PORVs would be unnecessary to include any situation where a block valve is closed due to any Action in TS 3.4.4, which would include cases in which the pressurizer PORV block valve has been closed due to excessive seat leakage. As noted in Attachment 1 to the licensee's LAR, when a pressurizer PORV block valve has been closed due to excessive seat leakage, and the block valve is subsequently reopened, momentary opening of the PORV has been noted. This observed PORV behavior is consistent with the Westinghouse Bases for STS SR 3.4.11.1, in TSTF-284, Revision 3, which the licensee states in the LAR as: "Opening the block valve in this condition | ||
[the block valve having been closed due to in inoperable PORV] increases the risk of an unisolable leak from the RCS since the PORV is already inoperable." Momentary opening of the pressurizer PORV could be a precursor to an unisolable leak in the RCS should the block valve fail to close. 3.2 Component Description As described in Attachment 1 to the LAR, MPS3 has two pressurizer PORVs. The pressurizer PORVs are solenoid-operated relief valves which are operated automatically or by remote manual control. The pressurizer PORVs and pressurizer steam bubble function to relieve RCS pressure during all design transients. | [the block valve having been closed due to in inoperable PORV] increases the risk of an unisolable leak from the RCS since the PORV is already inoperable." Momentary opening of the pressurizer PORV could be a precursor to an unisolable leak in the RCS should the block valve fail to close. 3.2 Component Description As described in Attachment 1 to the LAR, MPS3 has two pressurizer PORVs. The pressurizer PORVs are solenoid-operated relief valves which are operated automatically or by remote manual control. The pressurizer PORVs and pressurizer steam bubble function to relieve RCS pressure during all design transients. | ||
Operation of the pressurizer PORVs minimizes the undesirable opening of the spring-loaded pressurizer code safety valves. The pressurizer PORVs are also used for cold overpressure protection when any RCS cold leg temperature is at or below 226 degrees Fahrenheit | Operation of the pressurizer PORVs minimizes the undesirable opening of the spring-loaded pressurizer code safety valves. The pressurizer PORVs are also used for cold overpressure protection when any RCS cold leg temperature is at or below 226 degrees Fahrenheit | ||
(°F). MPS3 TS 3.4.9.3, which applies to the use of the pressurizer PORVs for cold overpressure protection, would not be affected by the 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 operated from the control room. A stuck-open pressurizer PORV is, in effect, a small break loss-of-coolant accident (SBLOCA). | (°F). MPS3 TS 3.4.9.3, which applies to the use of the pressurizer PORVs for cold overpressure protection, would not be affected by the 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 operated from the control room. A stuck-open pressurizer 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. | 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 pressurizer 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. 3.3 Operability of Pressurizer PORV and Block Valves As presented by the licensee on pages 2 and 3 of 7 of Attachment 1 to the LAR, the operability of the pressurizer PORVs and block valves is determined on the basis of their capability to perform the following functions: | The pressurizer 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. 3.3 Operability of Pressurizer PORV and Block Valves As presented by the licensee on pages 2 and 3 of 7 of Attachment 1 to the LAR, the operability of the pressurizer 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 during an inadvertent emergency core cooling system (ECCS) or chemical and volume control system (CVCS) injection event or during a feed line break event. 2. Provide for RCS depressurization during safety grade cold shutdown. | : 1. Control RCS pressure below the setting of the pressurizer code safety valves during an inadvertent emergency core cooling system (ECCS) or chemical and volume control system (CVCS) injection event or during a feed line break event. 2. Provide for RCS depressurization during safety grade cold shutdown. | ||
: 3. Provide manual control of the block valve to: 1) isolate a stuck-open PORV, 2) isolate an inoperable PORV, 3) unblock a PORV, which was inoperable for excessive seat leakage, to allow the PORV to be used for control of RCS pressure and, 4) isolate a PORV in support of certain fire events. With one or both pressurizer PORVs inoperable, but able to automatically and manually open and close, either the PORV(s) must be restored, or the flow path(s) isolated within one hour. For this condition, the block valve(s) would be closed with power maintained to the associated block valve(s), since removal of power would render the block valve(s) inoperable. | : 3. Provide manual control of the block valve to: 1) isolate a stuck-open PORV, 2) isolate an inoperable PORV, 3) unblock a PORV, which was inoperable for excessive seat leakage, to allow the PORV to be used for control of RCS pressure and, 4) isolate a PORV in support of certain fire events. With one or both pressurizer PORVs inoperable, but able to automatically and manually open and close, either the PORV(s) must be restored, or the flow path(s) isolated within one hour. For this condition, the block valve(s) would be closed with power maintained to the associated block valve(s), since removal of power would render the block valve(s) inoperable. | ||
Pressurizer PORV inoperability due to seat leakage does not prevent automatic or manual PORV use and does not create the possibility for a SBLOCA. For these reasons, the block valve may be closed; however, requiring power to be maintained to the valve allows quick access to the PORV for pressure control. Operation of the plant may continue with the pressurizer PORV(s) in this condition until the next refueling outage so that maintenance can be performed on the PORV(s) to address the degraded condition. | Pressurizer PORV inoperability due to seat leakage does not prevent automatic or manual PORV use and does not create the possibility for a SBLOCA. For these reasons, the block valve may be closed; however, requiring power to be maintained to the valve allows quick access to the PORV for pressure control. Operation of the plant may continue with the pressurizer PORV(s) in this condition until the next refueling outage so that maintenance can be performed on the PORV(s) to address the degraded condition. | ||
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==Enclosures:== | ==Enclosures:== | ||
Sincerely, IRA AChereskin For/ Richard V. Guzman, Senior Project Manager Plant Licensing Branch 1-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation | Sincerely, IRA AChereskin For/ Richard V. Guzman, Senior Project Manager Plant Licensing Branch 1-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation | ||
: 1. Amendment No. 264 to NPF-49 2. Safety Evaluation cc w/encls: Distribution via Listserv DISTRIBUTION: | : 1. Amendment No. 264 to NPF-49 2. Safety Evaluation cc w/encls: Distribution via Listserv DISTRIBUTION: | ||
PUBLIC LPLl-1 R/F RidsAcrsAcnw_MailCTR Resource RidsNrrDorlDpr Resource ADAMS Accession No.: ML 15225A010 OFFICE NRR/DORL/LPLl-1 | PUBLIC LPLl-1 R/F RidsAcrsAcnw_MailCTR Resource RidsNrrDorlDpr Resource ADAMS Accession No.: ML 15225A010 OFFICE NRR/DORL/LPLl-1 |
Revision as of 18:43, 27 April 2019
ML15225A010 | |
Person / Time | |
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Site: | Millstone ![]() |
Issue date: | 08/28/2015 |
From: | Guzman R V Plant Licensing Branch 1 |
To: | Heacock D A Dominion Nuclear Connecticut |
Guzman R V | |
References | |
TAC MF5092 | |
Download: ML15225A010 (14) | |
Text
UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 Mr. David A Heacock President and Chief Nuclear Officer Dominion Nuclear Innsbrook Technical Center 5000 Dominion Boulevard Glen Allen, VA 23060-6711 August 28, 2015
SUBJECT:
MILLSTONE POWER STATION, UNIT NO. 3 -ISSUANCE OF AMENDMENT RE: SURVEILLANCE REQUIREMENT 4.4.4.2, REACTOR COOLANT SYSTEM RELIEF VALVES (TAC NO. MF5092)
Dear Mr. Heacock:
The U.S. Nuclear Regulatory Commission (Commission) has issued the enclosed Amendment No. 264 to Renewed Facility Operating License No. NPF-49 for the Millstone Power Station, Unit No. 3. This amendment is in response to your application dated October 14, 2014, as supplemented by letter dated August 27, 2015. The amendment revises surveillance requirement (SR) 4.4.4.2 to remove the requirement to perform the surveillance for a pressurizer power-operated relief valve block valve that is being maintained closed in accordance with TS 3.4.4 Action a. A copy of the related Safety Evaluation is also enclosed.
Notice of Issuance will be included in the Commission's biweekly Federal Register notice. Docket No. 50-423
Enclosures:
- 1. Amendment No. 264 to NPF-49 2. Safety Evaluation cc w/encls: Distribution via Listserv Sincerely, Richard V. Guzman, Senior Project Manager Plant Licensing Branch 1-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 DOMINION NUCLEAR CONNECTICUT.
INC. DOCKET NO. 50-423 MILLSTONE POWER STATION, UNIT NO. 3 AMENDMENT TO RENEWED FACILITY OPERATING LICENSE Amendment No. 264 Renewed License No NPF-49 1. The Nuclear Regulatory Commission (the Commission) has found that: A. The application for amendment by Dominion Nuclear Connecticut, Inc. (DNC) dated October 14, 2014, as supplemented by letter dated August 27, 2015, complies with the standards and requirements of the Atomic Energy Act of 1954, as amended (the Act), and the Commission's rules and regulations set forth in 10 CFR Chapter I; B. The facility will operate in conformity with the application, the provisions of the Act, and the rules and regulations of the Commission; C. There is reasonable assurance: (i) that the activities authorized by this amendment can be conducted without endangering the health and safety of the public, and (ii) that such activities will be conducted in compliance with the Commission's regulations; D. The issuance of this amendment will not be inimical to the common defense and security or to the health and safety of the public; and E. The issuance of this amendment is in accordance with 1 O CFR Part 51 of the Commission's regulations and all applicable requirements have been satisfied.
Enclosure 1 2. Accordingly, the license is amended by changes to the Technical Specifications as indicated in the attachment to this license amendment, and paragraph 2.C.(2) of Renewed Facility Operating License No. NPF-49 is hereby amended to read as follows: (2) Technical Specifications The Technical Specifications contained in Appendix A, revised through Amendment No. 264 and the Environmental Protection Plan contained in Appendix B, both of which are attached hereto are hereby incorporated into the license. DNC shall operate the facility in accordance with the Technical Specifications and the Environmental Protection Plan. 3. This license amendment is effective as of the date of issuance, and shall be implemented within 60 days of issuance.
Attachment:
Changes to the License and Technical Specifications Date of Issuance:
August 28, 2015 FOR THE NUCLEAR REGULATORY COMMISSION Benjamin Beasley, Chief Plant Licensing Branch 1-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation ATTACHMENT TO LICENSE AMENDMENT NO. 264 RENEWED FACILITY OPERATING LICENSE NO. NPF-49 DOCKET NO. 50-423 Replace the following page of the Renewed Facility Operating License with the attached revised page. The revised page is identified by amendment number and contains marginal lines indicating the areas of change. Remove 4 4 Replace the following page of the Appendix A Technical Specifications with the attached revised page. The revised page is identified by amendment number and contains marginal lines indicating the areas of change. Remove 3/4 4-13 3/4 4-13 (2) Technical Specifications The Technical Specifications contained in Appendix A, revised through Amendment No. 264 and the Environmental Protection Plan contained in Appendix B, both of which are attached hereto are hereby incorporated into the license. DNC shall operate the facility in accordance with the Technical Specifications and the Environmental Protection Plan. (3) DNC shall not take any action that would cause Dominion Resources, Inc. (ORI) or its parent companies to void, cancel, or diminish DNC's Commitment to have sufficient funds available to fund an extended plant shutdown as represented in the application for approval of the transfer of the licenses for MPS Unit No. 3. (4) Immediately after the transfer of interests in MPS Unit No. 3 to DNC, the amount in the decommissioning trust fund for MPS Unit No. 3 must, with respect to the interest in MPS Unit No. 3, that DNC would then hold, be at a level no less than the formula amount under 10 CFR 50. 75. (5) The decommissioning trust agreement for MPS Unit No. 3 at the time the transfer of the unit to DNC is effected and thereafter is subject to the following: (a) The decommissioning trust agreement must be in a form
- acceptable to the NRC. (b) With respect to the decommissioning trust fund, investments in the securities or other obligations of Dominion Resources, Inc. or its affiliates or subsidiaries, successors, or assigns are prohibited.
Except for investments tied to market indexes or other non-nuclear-sector mutual funds, investments in any entity owning one or more nuclear power plants are prohibited. (c) The decommissioning trust agreement for MPS Unit No. 3 must provide that no disbursements or payments from the trust, other than for ordinary administrative expenses, shall be made by the trustee until the trustee has first given the Director of the Office of Nuclear Reactor Regulation 30 days prior written notice of payment. The decommissioning trust agreement shall further contain a provision that no disbursements or payments from the trust shall be made if the trustee receives prior written notice of objection from the NRC. (d) The decommissioning trust agreement must provide that the agreement cannot be amended in any material respect without 30 days prior written notification to the Director of the Office of Nuclear Reactor Regulation.
Renewed License No. NPF-49 Amendment No. 264 REACTOR COOLANT SYSTEM RELIEF VALVES SURVEILLANCE REQUIREMENTS 4.4.4. l In addition to the requirements of Specification 4.0.5, each PORV shall be demonstrated OPERABLE by: a. Performance of a CHANNEL CALIBRATION at the frequency specified in the Surveillance Frequency Control Program; and b. Operating the valve through one complete cycle of full travel during MODES 3 or 4 at the frequency specified in the Surveillance Frequency Control Program; and c. Performance of an ANALOG CHANNEL OPERATIONAL TEST on the PORV high pressurizer pressure actuation channels, but excluding valve operation, at the frequency specified in the Surveillance Frequency Control Program; and d. Verify the PORV high pressure automatic opening function is enabled at the frequency specified in the Surveillance Frequency Control Program. 4.4.4.2 Each block valve shall be demonstrated OPERABLE at the frequency specified in the Surveillance Frequency Control Program by operating the valve through one complete cycle of full travel unless the block valve is closed in order to meet the ACTION requirements of Specification
3.4.4. MILLSTONE
-UNIT 3 3/4 4-13 Amendment No. 8-8, .f.3.3., +6+, U-9,+/-58 264 UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO. 264 TO RENEWED FACILITY OPERATING LICENSE NO. NPF-49 DOMINION NUCLEAR CONNECTICUT.
INC. DOCKET NO. 50-423 MILLSTONE POWER STATION. UNIT NO. 3
1.0 INTRODUCTION
By letter dated October 14, 2014 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML 14294A454), as supplemented by letter dated August 27, 2015 (ADAMS Accession No. ML 15240A146), Dominion Nuclear Connecticut, Inc. (DNC, the licensee) submitted to the U.S. Nuclear Regulatory Commission (NRC, the Commission) a license amendment request (LAR) for changes to the Millstone Power Station, Unit No. 3 (MPS3), Technical Specifications (TSs). The proposed amendment would revise surveillance requirement (SR) 4.4.4.2 to remove the requirement to perform the surveillance for a pressurizer power-operated relief valve (PORV) block valve that is being maintained closed in accordance with TS 3.4.4 Action a. Instead, the proposed amendment would revise SR 4.4.4.2 to expand the range of conditions under which testing of block valves specified in the Surveillance Frequency Control Program for the pressurizer PORVs would be unnecessary.
The supplemental letter dated August 27, 2015, provided additional information that clarified the application, did not expand the scope of the application as originally noticed, and did not change the U.S. Nuclear Regulatory Commission (NRC) staff's original proposed no significant hazards consideration determination as published in the Federal Register (FR) on April 28, 2015 (80 FR 23601 ).
2.0 REGULATORY EVALUATION
In Title 10 of the Code of Federal Regulations (10 CFR), Section 50.36, "Technical specifications," the NRC established its regulatory requirements related to the content of TSs. Pursuant to 1 O CFR 50.36(c), TSs are required to include items in the following five specific categories related to station operation:
(1) safety limits, limiting safety system settings, and limiting control settings; (2) limiting conditions for operation (LCOs); (3) SRs; (4) design features; and (5) administrative controls.
Enclosure 2 In 10 CFR 50.36(c)(3), it states that, "surveillance requirements are requirements related to test, calibration, or inspection to assure that the necessary quality of systems and components is maintained, that facility operation will be within safety limits, and that the limiting conditions for operation will be met." The MPS3 pressurizer PORV block valves are the subject of LCOs and SRs in TS 3/4.4.4, "Relief Valves." At the present time, the pressurizer PORV block valve test specified in SR 4.4.4.2, is required to be performed at the frequency specified in the Surveillance Frequency Control Program unless the pressurizer PORV block valve is closed for reasons other than excessive PORV seat leakage (i.e., Actions b. or c. of TS 3.4.4). The TS Task Force (TSTF) Traveler No. 284 (TSTF-284), Revision 3, provides guidance for the extension of the range of circumstances under which the quarterly testing of the pressurizer PORV block valve is not required in order to meet the Actions specified in TS 3.4.4. In response to the DNC LAR, the NRC staff considered whether this aspect of TSTF-284, Revision 3, may be applied to MPS3. The NRC staff also considered relevant information in the MPS3 Updated Final Safety Analysis Report (UFSAR) and TSs. In NUREG-1431, Revision 4, Standard Technical Specifications (STS) for Westinghouse Plants, and NUREG-1432, Revision 4, STS for Combustion Engineering Plants, licensees are excluded from performing the pressurizer PORV block valve surveillance specified in STS SR 3.4.11.1 when the block valve is closed in accordance with any of the actions of STS TS 3.4.11. In 10 CFR 50.46a, and as explained in NUREG-0737, it is required that each nuclear power reactor be provided with high point vents for the reactor coolant system, for the reactor vessel head, and for other systems required to maintain adequate core cooling if the accumulation of noncondensible gases would cause the loss of function of these systems. The criteria for acceptable venting systems include that high point vents must be remotely operated from the control room. The purpose of such systems is to vent noncondensible gases from the RCS which may inhibit core cooling during natural circulation.
3.0 TECHNICAL
EVALUATION
3.1 Background
The pressurizer PORVs are described in MPS3 UFSAR Section 5.4.13, "Safety and Relief Valves," and, among other things, they prevent actuation of the fixed reactor high pressure trip for all design transients up to and including the design step load decreases with steam dump and also limit the opening of the spring loaded pressurizer safety valves. The pressurizer PORVs also protect against an overpressurization event during low temperature operation.
1 The failure position of the pressurizer PORV is closed. The pressurizer is equipped with two PORVs, each of which has a block valve to be closed in the event that excessive PORV seat leakage is detected.
The pressurizer PORVs are not required to open in order to prevent the overpressurization of the RCS. The three pressurizer safety valves, by themselves, are sized to relieve enough steam to prevent an overpressurization of the RCS. Therefore, a loss of pressurizer PORV automatic control (or the closing of the associated block valves) and the subsequent failure of 1 See MPS3 UFSAR Section 5.2.2.11, "RCS Pressure Control during Low Temperature Operation." the PORVs to open will result in higher reactor coolant pressures, but will not cause any overpressurization event. The opening of the pressurizer PORV is a conservative assumption for the departure from nucleate boiling limited transients by tending to keep the primary system pressure down. As discussed in MPS3 UFSAR Section 5.4.7.2.3.5, "Safety Grade Cold Shutdown," depressurization to achieve cold shutdown would be accomplished by the pressurizer PORVs if pressurizer spray is unavailable or not effective.
However, as indicated in the LAR, not performing the surveillance on the block valve does not significantly reduce the assurance that the block valve is capable of opening to allow operation of the pressurizer PORV. 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 amendment does not significantly reduce the confidence that the block valves can be opened in order to permit automatic or manual actuation of the pressurizer PORVs to depressurize the RCS. The current SR 4.4.4.2 requires that the pressurizer PORV block valves be subjected to an operability test, with a frequency as specified in the Surveillance Frequency Control Program, by operating each valve through one complete cycle of full travel unless (1) one block valve has been closed for reasons of PORV inoperability due to causes other than excessive seat leakage (i.e., ACTION b. of TS 3.4.4) or (2) both block valves have been closed for reasons of PORV inoperability due to causes other than excessive seat leakage (i.e., ACTION c. of TS 3.4.4). The licensee's proposed change to SR 4.4.4.2 would expand the range of conditions under which periodic operability testing of block valves for the pressurizer PORVs would be unnecessary to include any situation where a block valve is closed due to any Action in TS 3.4.4, which would include cases in which the pressurizer PORV block valve has been closed due to excessive seat leakage. As noted in Attachment 1 to the licensee's LAR, when a pressurizer PORV block valve has been closed due to excessive seat leakage, and the block valve is subsequently reopened, momentary opening of the PORV has been noted. This observed PORV behavior is consistent with the Westinghouse Bases for STS SR 3.4.11.1, in TSTF-284, Revision 3, which the licensee states in the LAR as: "Opening the block valve in this condition
[the block valve having been closed due to in inoperable PORV] increases the risk of an unisolable leak from the RCS since the PORV is already inoperable." Momentary opening of the pressurizer PORV could be a precursor to an unisolable leak in the RCS should the block valve fail to close. 3.2 Component Description As described in Attachment 1 to the LAR, MPS3 has two pressurizer PORVs. The pressurizer PORVs are solenoid-operated relief valves which are operated automatically or by remote manual control. The pressurizer PORVs and pressurizer steam bubble function to relieve RCS pressure during all design transients.
Operation of the pressurizer PORVs minimizes the undesirable opening of the spring-loaded pressurizer code safety valves. The pressurizer PORVs are also used for cold overpressure protection when any RCS cold leg temperature is at or below 226 degrees Fahrenheit
(°F). MPS3 TS 3.4.9.3, which applies to the use of the pressurizer PORVs for cold overpressure protection, would not be affected by the 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 operated from the control room. A stuck-open pressurizer 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 pressurizer 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. 3.3 Operability of Pressurizer PORV and Block Valves As presented by the licensee on pages 2 and 3 of 7 of Attachment 1 to the LAR, the operability of the pressurizer 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 during an inadvertent emergency core cooling system (ECCS) or chemical and volume control system (CVCS) injection event or during a feed line break event. 2. Provide for RCS depressurization during safety grade cold shutdown.
- 3. Provide manual control of the block valve to: 1) isolate a stuck-open PORV, 2) isolate an inoperable PORV, 3) unblock a PORV, which was inoperable for excessive seat leakage, to allow the PORV to be used for control of RCS pressure and, 4) isolate a PORV in support of certain fire events. With one or both pressurizer PORVs inoperable, but able to automatically and manually open and close, either the PORV(s) must be restored, or the flow path(s) isolated within one hour. For this condition, the block valve(s) would be closed with power maintained to the associated block valve(s), since removal of power would render the block valve(s) inoperable.
Pressurizer PORV inoperability due to seat leakage does not prevent automatic or manual PORV use and does not create the possibility for a SBLOCA. For these reasons, the block valve may be closed; however, requiring power to be maintained to the valve allows quick access to the PORV for pressure control. Operation of the plant may continue with the pressurizer PORV(s) in this condition until the next refueling outage so that maintenance can be performed on the PORV(s) to address the degraded condition.
With one pressurizer PORV inoperable due to causes other than excessive seat leakage, 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 pressurizer 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 pressurizer PORV is inoperable due to causes other than excessive seat leakage, it is necessary to either restore at least one PORV 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. Finally, the licensee notes that SR 4.4.4.2 has existed in the MPS3 TSs since their original issuance in January 1986. This SR was revised by MPS3 License Amendment No. 258, 2 which relocated its surveillance frequency to the Surveillance Frequency Control Program. 3.4 Licensee's Proposed Changes In Section 2 of Attachment 1 to the LAR, the licensee proposed to revise SR 4.4.4.2 to replace the specific exceptions to TS 3.4.4 Actions b or c with a statement that a pressurizer PORV block valve closed in accordance with any of the applicable actions of TS 3.4.4 would be excluded from the surveillance specified by SR 4.4.4.2. Specifically, the proposed change to the MPS3 SR 4.4.4.2 is as follows: (deleted text is in strike-through and added text is in italics and bold) Each block valve shall be demonstrated OPERABLE at the frequency specified in the Surveillance Frequency Control Program by operating the valve through one complete cycle of full travel unless the block valve is closed with power removed in order to meet the ACTION requirements of ACTION b. or c. in Specification 3.4.4. A mark-up of the proposed TS page is provided in Attachment 2 to the LAR. Attachment 3 to the LAR contains a mark-up of the associated TS Bases, which are similar to the Westinghouse STS Bases for the block valve surveillance, and were provided by the licensee for information only. In a supplemental letter dated August 27, 2015, DNC submitted a correction to the Attachment 3 mark-up TS Bases. Specifically, the word "Operating" in the last sentence of the proposed TS Bases paragraph was changed to "Opening" which is consistent with the Westinghouse STS Bases for SR 3.4.11.1 in NUREG-1431.
In its supplement, the licensee provided a copy of the new TS Bases page with the revised wording for information only. 3.5 NRC Staff Evaluation of the Proposed Changes In reviewing the licensee's LAR, the NRC staff evaluated its consistency with TSTF-284, Revision 3, and the NUREG-1431, Revision 4, and NUREG-1432, Revision 4, STSs, as well as 2 See Amendment No. 258 issued February 25, 2014 (ADAMS Accession No. ML 14023A748). similar previously-approved LARs and their associated safety evaluations.
3 The NRC staff determined that the proposed change to the MPS3 pressurizer PORV block valve SR is consistent with the pressurizer PORV block valve SR contained in NUREG-1431, Revision 4, for Westinghouse plants, and NUREG-1432, Revision 4, for Combustion Engineering plants. The NRC staff also determined that the modified TS Bases section provided in Attachment 3 to the LAR is consistent with TSTF-284, Revision 3. The NRC staff considers the testing of the pressurizer PORV block valve to be unnecessary if the block valve has been closed due to an inoperable PORV. The additional assurance of block valve operability, gained from the surveillance test, is outweighed by the risk associated with the potential for an unisolable leak in the RCS. Accordingly, the NRC staff finds that the provision of TSTF-284, Revision 3, extending the range of circumstances under which the surveillance testing of the pressurizer PORV block valve is not required to any of the Actions closing the block valve, is acceptable.
Therefore, the NRC staff concludes that the licensee's request to remove the surveillance testing under the specific conditions of the revised PORV block valve SR 4.4.4.2 of TS 3/4.4.4 is acceptable.
3.6 Technical
Evaluation Conclusion The NRC staff has reviewed the licensee's proposed changes to TS 3/4.4.4, "Reactor Coolant System Relief Valves," for MPS3. The NRC staff concludes that the proposed changes are in accordance with the regulatory requirements listed in Section 2.0 of this safety evaluation and are consistent with supporting the current licensing basis.
4.0 STATE CONSULTATION
In accordance with the Commission's regulations, the Connecticut State official was notified on August 3, 2015, of the proposed issuance of the amendment.
The State official had no comments.
5.0 ENVIRONMENTAL
CONSIDERATION The amendment changes a requirement with respect to the installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20 or changes the SRs. The NRC staff has determined that the amendment involves no significant increase in the amounts, and no significant change in the types, of any effluents that may be released offsite, and that there is no significant increase in individual or cumulative occupational radiation exposure.
The Commission has previously issued a proposed finding that the amendment involves no significant hazards consideration, and there has been no public comment on such finding published in the Federal Register (FR) on April 28, 2015 (80 FR 23601 ). Accordingly, the amendment meets the eligibility criteria for categorical exclusion set forth in 1 O CFR 51.22(c)(9).
Pursuant to 10 CFR 51.22(b), no environmental impact statement or 3 South Texas Project LAR dated September 30, 2004 (ML042800229) and subsequent Amendment No. 153 dated October 21, 2004 (ML042800363);
Millstone Power Station, Unit 2, LAR dated December 17, 2012(ML12362A012) and subsequent Amendment No. 314 dated March 26, 2013(ML13057A525). environmental assessment need be prepared in connection with the issuance of the amendment.
6.0 CONCLUSION
The Commission has concluded, based on the considerations discussed above that: (1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner; (2) there is reasonable assurance that 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. Principal Contributor:
D. Palmrose Date: August 28, 2015 August 28, 2015 Mr. David A. Heacock President and Chief Nuclear Officer Dominion Nuclear Innsbrook Technical Center 5000 Dominion Boulevard Glen Allen, VA 23060-6711
SUBJECT:
MILLSTONE POWER STATION, UNIT NO. 3 -ISSUANCE OF AMENDMENT RE: SURVEILLANCE REQUIREMENT 4.4.4.2, REACTOR COOLANT SYSTEM RELIEF VALVES (TAC NO. MF5092)
Dear Mr. Heacock:
The U.S. Nuclear Regulatory Commission (Commission) has issued the enclosed Amendment No. 264 to Renewed Facility Operating License No. NPF-49 for the Millstone Power Station, Unit No. 3. This amendment is in response to your application dated October 14, 2014, as supplemented by letter dated August 27, 2015. The amendment revises surveillance requirement (SR) 4.4.4.2 to remove the requirement to perform the surveillance for a pressurizer power-operated relief valve block valve that is being maintained closed in accordance with TS 3.4.4 Action a. A copy of the related Safety Evaluation is also enclosed.
Notice of Issuance will be included in the Commission's biweekly Federal Register notice. Docket No. 50-423
Enclosures:
Sincerely, IRA AChereskin For/ Richard V. Guzman, Senior Project Manager Plant Licensing Branch 1-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation
- 1. Amendment No. 264 to NPF-49 2. Safety Evaluation cc w/encls: Distribution via Listserv DISTRIBUTION:
PUBLIC LPLl-1 R/F RidsAcrsAcnw_MailCTR Resource RidsNrrDorlDpr Resource ADAMS Accession No.: ML 15225A010 OFFICE NRR/DORL/LPLl-1
/PM NAME RGuzman DATE 8/13/15 OFFICE OGC NAME JWachutka DATE 8/17/15 RidsNrrDorllpl1-1 Resource RidsNrrDssStsb Resource RidsNrrLAKGoldstein Resource RidsNrrPMMillstone Resource RidsNrrDssSrxb Resource RidsRgn1 MailCenter Resource DPalmrose, NRR/DSS/SRXB RGrover, NRR/DSS/STSB
- SE memo dated June 17 2015 NRR/DORL/LPLl-1/LA NRR/DSS/SRXB/BC NRR/DSS/STSB/BC KGoldstein CJackson*
RElliott 8/14/15 6/17/15 8/25/15 NRR/DORL/LPLl-1
/BC NRR/DORL/LPLl-1
/PM BBeasley RGuzman (AChereskin for) 8/28/15 8/28/15 OFFICIAL RECORD COPY