ML20245E413
| ML20245E413 | |
| Person / Time | |
|---|---|
| Site: | Watts Bar  |
| Issue date: | 12/08/2020 |
| From: | Michael Wentzel Plant Licensing Branch II |
| To: | Jim Barstow Tennessee Valley Authority |
| Wentzel M | |
| References | |
| EPID L-2019-LLA-0272 | |
| Download: ML20245E413 (22) | |
Text
December 8, 2020 Mr. James Barstow Vice President, Nuclear Regulatory Affairs and Support Services Tennessee Valley Authority 1101 Market Street, LP 4A-C Chattanooga, TN 37402-2801
SUBJECT:
WATTS BAR NUCLEAR PLANT, UNITS 1 AND 2 - ISSUANCE OF AMENDMENT NOS. 139 AND 45 REGARDING REVISIONS TO TECHNICAL SPECIFICATION 3.6.15, SHIELD BUILDING" (EPID L-2019-LLA-0272)
Dear Mr. Barstow:
The U.S. Nuclear Regulatory Commission (Commission) has issued the enclosed Amendment No. 139 to Facility Operating License No. NPF-90 and Amendment No. 45 to Facility Operating License No. NPF-96 for the Watts Bar Nuclear Plant, Units 1 and 2, respectively. These amendments are in response to your application dated December 6, 2019.
The amendments revise Technical Specification 3.6.15 by deleting existing Condition B and revise the acceptance criteria for annulus pressure in Surveillance Requirement 3.6.15.1.
A copy of our related safety evaluation is also enclosed. Notice of issuance will be included in the Commissions monthly Federal Register notice.
Sincerely,
/RA/
Michael J. Wentzel, Project Manager Plant Licensing Branch II-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-390 and 50-391
Enclosures:
- 1. Amendment No. 139 to NPF-90
- 2. Amendment No. 45 to NPF-96
- 3. Safety Evaluation cc: Listserv
TENNESSEE VALLEY AUTHORITY DOCKET NO. 50-390 WATTS BAR NUCLEAR PLANT, UNIT 1 AMENDMENT TO FACILITY OPERATING LICENSE Amendment No. 139 License No. NPF-90
- 1.
The U.S. Nuclear Regulatory Commission (the Commission) has found that:
A.
The application for amendment by Tennessee Valley Authority (TVA, the licensee) dated December 6, 2019, complies with the standards and requirements of the Atomic Energy Act of 1954, as amended (the Act), and the Commissions 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 Commissions 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 10 CFR Part 51 of the Commissions regulations and all applicable requirements have been satisfied.
- 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 Facility Operating License No. NPF-90 is hereby amended to read as follows:
(2)
Technical Specifications and Environmental Protection Plan The Technical Specifications contained in Appendix A as revised through Amendment No. 139 and the Environmental Protection Plan contained in Appendix B, both of which are attached hereto, are hereby incorporated into this license. TVA 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 its issuance and shall be implemented within 30 days.
FOR THE NUCLEAR REGULATORY COMMISSION Undine Shoop, Chief Plant Licensing Branch II-2 Division of operating Reactor Licensing Office of Nuclear Reactor Regulation
Attachment:
Changes to the Operating License and Technical Specifications Date of Issuance: December 8, 2020 Undine S.
Shoop Digitally signed by Undine S. Shoop Date: 2020.12.08 09:42:25 -05'00'
ATTACHMENT TO AMENDMENT NO. 139 WATTS BAR NUCLEAR PLANT, UNIT 1 FACILITY OPERATING LICENSE NO. NPF-90 DOCKET NO. 50-390 Replace page 3 of Facility Operating License No. NPF-90 with the attached revised page 3.
Replace the following pages of the Appendix A Technical Specifications with the attached pages. The revised pages are identified by amendment number and contain vertical lines indicating the area of change.
Remove Pages Insert Pages 3.6-40 3.6-40 3.6-41 3.6-41 Facility License No. NPF-90 Amendment No. 139 (4)
TVA, pursuant to the Act and 10 CFR Parts 30, 40 and 70, to receive, possess, and use in amounts as required, any byproduct, source or special nuclear material without restriction to chemical or physical form, for sample analysis, instrument calibration, or other activity associated with radioactive apparatus or components; and (5)
TVA, pursuant to the Act and 10 CFR Parts 30, 40 and 70, to possess, but not separate, such byproduct and special nuclear materials as may be produced by the operation of the facility.
C.
This license shall be deemed to contain and is subject to the conditions specified in the Commissions regulations set forth in 10 CFR Chapter I and is subject to all applicable provisions of the Act and to the rules, regulations, and orders of the Commission now or hereafter in effect, and is subject to the additional conditions specified or incorporated below.
(1)
Maximum Power Level TVA is authorized to operate the facility at reactor core power levels not in excess of 3459 megawatts thermal.
(2)
Technical Specifications and Environmental Protection Plan The Technical Specifications contained in Appendix A as revised through Amendment No. 139 and the Environmental Protection Plan contained in Appendix B, both of which are attached hereto, are hereby incorporated into this license. TVA shall operate the facility in accordance with the Technical Specifications and the Environmental Protection Plan.
(3)
Safety Parameter Display System (SPDS) (Section 18.2 of SER Supplements 5 and 15)
Prior to startup following the first refueling outage, TVA shall accomplish the necessary activities, provide acceptable responses, and implement all proposed corrective actions related to having the Watts Bar Unit 1 SPDS operational.
(4)
Vehicle Bomb Control Program (Section 13.6.9 of SSER 20)
During the period of the exemption granted in paragraph 2.D.(3) of this license, in implementing the power ascension phase of the approved initial test program, TVA shall not exceed 50% power until the requirements of 10 CFR 73.55(c)(7) and (8) are fully implemented. TVA shall submit a letter under oath or affirmation when the requirements of 73.55(c)(7) and (8) have been fully implemented.
Shield Building 3.6.15 Watts Bar-Unit 1 3.6-40 Amendment 59, 139 3.6 CONTAINMENT SYSTEMS 3.6.15 Shield Building LCO 3.6.15 The Shield Building shall be OPERABLE.
APPLICABILITY:
MODES 1, 2, 3, and 4.
ACTIONS CONDITION REQUIRED ACTION COMPLETION TIME A.
A.1 Restore Shield Building to OPERABLE status.
24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> B.
Required Action and associated Completion Time not met.
B.1 Be in MODE 3.
AND B.2 Be in MODE 5.
6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> 36 hours
Shield Building 3.6.15 Watts Bar-Unit 1 3.6-41 Amendment 132, 139 SURVEILLANCE REQUIREMENTS SURVEILLANCE FREQUENCY SR 3.6.15.1 Verify annulus negative pressure is equal to or more negative than -1 inches water gauge with respect to the atmosphere.
In accordance with the Surveillance Frequency Control Program SR 3.6.15.2 Verify the door in each access opening is closed, except when the access opening is being used for normal transient entry and exit.
SR 3.6.15.3 Verify shield building structural integrity by performing a visual inspection of the exposed interior and exterior surfaces of the Shield Building.
During shutdown for SR 3.6.1.1 Type A tests SR 3.6.15.4 Verify each Emergency Gas Treatment System train with final flow 3600 and 4400 cfm produces an annulus pressure equal to or more negative than
-0.61 inch water gauge at elevation 783 with respect to the atmosphere and with an inleakage of 250 cfm.
In accordance with the Surveillance Frequency Control Program In accordance with the Surveillance Frequency Control Program
TENNESSEE VALLEY AUTHORITY DOCKET NO. 50-391 WATTS BAR NUCLEAR PLANT, UNIT 2 AMENDMENT TO FACILITY OPERATING LICENSE Amendment No. 45 License No. NPF-96
- 1.
The U.S. Nuclear Regulatory Commission (the Commission) has found that:
A.
The application for amendment by Tennessee Valley Authority (TVA, the licensee) dated December 6, 2019, complies with the standards and requirements of the Atomic Energy Act of 1954, as amended (the Act), and the Commissions 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 Commissions 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 10 CFR Part 51 of the Commissions regulations and all applicable requirements have been satisfied.
- 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 Facility Operating License No. NPF-96 is hereby amended to read as follows:
(2)
Technical Specifications and Environmental Protection Plan The Technical Specifications contained in Appendix A as revised through Amendment No. 45 and the Environmental Protection Plan contained in Appendix B, both of which are attached hereto, are hereby incorporated into this license. TVA 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 its issuance and shall be implemented within 30 days.
FOR THE NUCLEAR REGULATORY COMMISSION Undine Shoop, Chief Plant Licensing Branch II-2 Division of operating Reactor Licensing Office of Nuclear Reactor Regulation
Attachment:
Changes to the Operating License and Technical Specifications Date of Issuance: December 8, 2020 Undine S.
Shoop Digitally signed by Undine S. Shoop Date: 2020.12.08 09:43:23 -05'00'
ATTACHMENT TO AMENDMENT NO. 45 WATTS BAR NUCLEAR PLANT, UNIT 2 FACILITY OPERATING LICENSE NO. NPF-96 DOCKET NO. 50-391 Replace page 3 of Facility Operating License No. NPF-96 with the attached revised page 3.
Replace the following pages of the Appendix A Technical Specifications with the attached pages. The revised pages are identified by amendment number and contain vertical lines indicating the area of change.
Remove Pages Insert Pages 3.6-35 3.6-35 3.6-36 3.6-36 Unit 2 Facility Operating License No. NPF-96 Amendment No. 45 C.
The license shall be deemed to contain and is subject to the conditions specified in the Commissions regulations set forth in 10 CFR Chapter I and is subject to all applicable provisions of the Act, and to the rules, regulations, and orders of the Commission now or hereafter in effect, and is subject to the additional conditions specified or incorporated below.
(1)
Maximum Power Level TVA is authorized to operate the facility at reactor core power levels not in excess of 3411 megawatts thermal.
(2)
Technical Specifications and Environmental Protection Plan The Technical Specifications contained in Appendix A as revised through Amendment No. 45 and the Environmental Protection Plan contained in Appendix B, both of which are attached hereto, are hereby incorporated into this license. TVA shall operate the facility in accordance with the Technical Specifications and the Environmental Protection Plan.
(3)
TVA shall implement permanent modifications to prevent overtopping of the embankments of the Fort Loudon Dam due to the Probable Maximum Flood by June 30, 2018.
(4)
PAD4TCD may be used to establish core operating limits until the WBN Unit 2 steam generators are replaced with steam generators equivalent to the existing steam generators at WBN Unit 1.
(5)
By December 31, 2019, the licensee shall report to the NRC that the actions to resolve the issues identified in Bulletin 2012-01, Design Vulnerability in Electrical Power System, have been implemented.
(6)
The licensee shall maintain in effect the provisions of the physical security plan, security personnel training and qualification plan, and safeguards contingency plan, and all amendments made pursuant to the authority of 10 CFR 50.90 and 50.54(p).
(7)
TVA shall fully implement and maintain in effect all provisions of the Commission approved cyber security plan (CSP), including changes made pursuant to the authority of 10 CFR 50.90 and 10 CFR 50.54(p). The TVA approved CSP was discussed in NUREG-0847, Supplement 28, as amended by changes approved in License Amendment No. 7.
(8)
TVA shall implement and maintain in effect all provisions of the approved fire protection program as described in the Fire Protection Report for the facility, as described in NUREG-0847, Supplement 29, subject to the following provision:
Shield Building 3.6.15 Watts Bar - Unit 2 3.6-35 Amendment 45 A
3.6 CONTAINMENT SYSTEMS 3.6.15 Shield Building LCO 3.6.15 The shield building shall be OPERABLE.
APPLICABILITY:
MODES 1, 2, 3, and 4.
ACTIONS CONDITION REQUIRED ACTION COMPLETION TIME A. Shield building inoperable.
A.1 Restore shield building to OPERABLE status.
24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> B. Required Action and associated Completion Time not met.
B.1 Be in MODE 3.
6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> AND B.2 Be in MODE 5.
36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />
Shield Building 3.6.15 Watts Bar - Unit 2 3.6-36 Amendment 36, 45 A
SURVEILLANCE REQUIREMENTS SURVEILLANCE FREQUENCY SR 3.6.15.1 Verify annulus negative pressure is equal to or more negative than -1 inches water gauge with respect to the atmosphere.
In accordance with the Surveillance Frequency Control Program SR 3.6.15.2 Verify the door in each access opening is closed, except when the access opening is being used for normal transient entry and exit.
SR 3.6.15.3 Verify shield building structural integrity by performing a visual inspection of the exposed interior and exterior surfaces of the Shield Building.
During shutdown for SR 3.6.1.1 Type A tests SR 3.6.15.4 Verify each Emergency Gas Treatment System train with final flow 3600 cfm and 4400 cfm produces an annulus pressure equal to or more negative than - 0.61 inch water gauge at elevation 783 with respect to the atmosphere and with an inleakage of 250 cfm.
In accordance with the Surveillance Frequency Control Program In accordance with the Surveillance Frequency Control Program
SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NOS. 139 AND 45 TO FACILITY OPERATING LICENSE NOS. NPF-90 AND NPF-96 TENNESSEE VALLEY AUTHORITY WATTS BAR NUCLEAR PLANT, UNITS 1 AND 2 DOCKET NOS. 50-390 AND 50-391
1.0 INTRODUCTION
By letter dated December 6, 2019 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML19340B773), the Tennessee Valley Authority (the licensee),
submitted a request for changes to the Watts Bar Nuclear Plant (Watts Bar), Units 1 and 2, Technical Specifications (TSs). The requested changes would revise TS 3.6.15, Shield Building, by deleting existing Condition B and would revise the acceptance criteria for annulus pressure in Surveillance Requirement (SR) 3.6.15.1.
2.0 REGULATORY EVALUATION
2.1
System Description
The following description of affected systems is summarized from Chapters 3 and 6 of the Watts Bar, Units 1 and 2, Updated Final Safety Analysis Report (ADAMS Accession Nos. ML19176A159 and ML19336A067, respectively).
2.1.1 Shield Building The Shield Building is located adjacent to, but physically separated from, the Auxiliary and Valve Room Buildings, and is a reinforced concrete cylinder supported by a circular base slab and covered at the top with a spherical dome. It surrounds the steel containment structure and is designed to:
provide radiation shielding during accident conditions, provide radiation shielding from parts of the reactor coolant system during operation, and protect the steel containment vessel from adverse atmospheric conditions and external missiles propelled by tornado winds.
2.1.2 Containment The steel containment vessel is a low-leakage, freestanding steel structure. It consists of a cylindrical wall, a hemispherical dome, and a bottom liner plate encased in concrete.
The containment vessel includes access openings and penetrations and is designed to limit the leakage of radioactive materials from the containment structure under the pressure and temperature conditions that would result from the largest credible energy release following a loss-of-coolant accident (LOCA) to below the limits specified in Part 100, Reactor Site Criteria, of Title 10 to the Code of Federal Regulations (10 CFR). This includes the calculated energy from metal-water or other chemical reactions that could occur as a consequence of failure of any single active component in any emergency cooling system.
2.1.3 Emergency Gas Treatment System The emergency gas treatment system (EGTS) provides ventilation control and atmospheric cleanup inside the annulus between the Shield Building and the Primary Containment Building.
The EGTS has two subsystems: the annulus vacuum control subsystem and the air cleanup subsystem. The annulus vacuum control subsystem is a fan and duct network used to establish and keep a negative pressure level within the annular space between the primary and secondary containment structures. This subsystem is utilized during normal operations in which containment integrity is required. During emergencies in which containment isolation is required, this subsystem is isolated and shut down. The air cleanup subsystem is a redundant, shared-airflow network having the capability to perform two functions for the affected reactor secondary containment during a LOCA. One function is to keep the secondary containment annulus air volume below atmospheric pressure. The second function is to remove airborne particulates and vapors that may contain radioactive nuclides from air drawn from the annulus.
The EGTS is designed to:
keep the air pressure within each Shield Building annulus below atmospheric pressure at all times in which the integrity of that particular containment is required, reduce the concentration of radioactive nuclides in annulus air that is released to the environs during a LOCA in either reactor unit to levels sufficiently low to keep the site boundary and low population zone dose rates below the 10 CFR Part 100 values, withstand the safe shutdown earthquake, and provide for initial and periodic testing of the system capability to function as designed.
2.2 Description of Proposed Changes The licensee proposed to revise Watts Bar, Units 1 and 2, TS 3.6.15, as follows (additions shown underlined, deletions shown in stricken text):
Deletion of Condition B CONDITION REQUIRED ACTION COMPLETION TIME A. Shield Building inoperable.
A.1 Restore shield building to OPERABLE status.
24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> B. ----------------NOTE----------------
Annulus pressure requirement is not applicable during venting operations, required annulus entries, or Auxiliary Building Isolations not exceeding 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> in duration or while Penetration 1-EQH-271-0010 or 1-EQH-271-0011 in the Shield Building dome is open until annulus pressure is restored.*
Annulus pressure not within limits.
B.1 Restore annulus pressure within limits 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> CB. Required Action and associated Completion Time not met.
CB.1 Be in MODE 3.
AND CB.2 Be in MODE 5.
6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> 36 hours
- 1. The combined opening time of Penetrations 1-EQ-H-271-0010 or 1-EQH-271-0011 is limited to a total time of five hours a day, six days a week during Cycle 7 operation.
- 2. Penetrations 1-EQH-271-0010 or 1-EQH-271-0011 in the Shield Building Dome may not be opened if in Action Conditions LCO 3.6.9A or 3.8.1B.
- 3. Upon opening Penetration 1-EQH-271-0010 or 1-EQH-271-0011 In the Shield Building Dome, both EGTS control loops shall be placed in the A-Auto Stand-by position and returned to normal position following closure of penetration.
The above wording of the NOTE and the associated footnote is from the Watts Bar, Unit 1 TS.
The wording of the Watts Bar, Unit 2 TS imposes a similar limitation on the annulus pressure requirement without mentioning specific penetrations and without a corresponding footnote and would be deleted as a part of the licensees proposed changes.
Revision to SR 3.6.15.1 SURVEILLANCE FREQUENCY SR3.6.15.1 Verify annulus negative pressure is equal to or more negative than -51 inches water gauge with respect to the atmosphere.
12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> 2.3 Applicable Regulatory Requirements and Guidance Section 50.36, Technical specifications, of 10 CFR establishes the regulatory requirements related to the content of TSs. Section 50.36(a)(1) requires an application for an operating license to include proposed TSs. A summary statement of the bases or reasons for such specifications, other than those covering administrative controls, shall also be included in the application, but shall not become part of the TSs.
Pursuant to 10 CFR 50.36, TSs for operating reactors are required, in part, to include items in the following five specific categories: (1) safety limits, limiting safety system settings, and limiting control settings; (2) limiting conditions for operation (LCOs); (3) Surveillance Requirements; (4) design features; and (5) administrative controls.
Section 50.36(c)(2) of 10 CFR states that LCOs are the lowest functional capability or performance levels of equipment required for safe operation of the facility, and when an LCO is not met, the licensee shall shut down the reactor or follow any remedial action permitted by the TSs until the condition can be met.
Section 50.36(c)(3) of 10 CFR states that SRs are requirements relating 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 LCOs will be met.
Appendix A, General Design Criteria (GDC) for Nuclear Power Plants, to 10 CFR Part 50 establishes the minimum requirements for the principal design criteria for water-cooled nuclear power plants. The following GDC is applicable for this review:
GDC 19, Control Room, requires, in part, that a control room shall be provided from which actions can be taken to operate the nuclear power unit safely under normal conditions and to maintain it in safe condition under accident conditions, including a loss-of-coolant accident. Adequate radiation protection shall be provided to permit access and occupancy of the control room under accident conditions without personnel receiving radiation exposures in excess of five rem whole body, or its equivalent to any part of the body, for the duration of the accident. Equipment at appropriate locations outside the control room shall be provided (1) with a design capability for prompt hot shutdown of the reactor, including necessary instrumentation and control to maintain the unit in a safe condition during hot shutdown, and (2) with a potential capability for subsequent cold shutdown of the reactor through the use of suitable procedures.
Section 100.11, Determination of exclusion area, low population zone, and population center distance, of 10 CFR establishes, in part, acceptance criteria for evaluating radiological accident consequences.
NUREG-1431, Revision 4, Standard Technical Specifications [STS] - Westinghouse Plants, (ADAMS Accession No. ML12100A222), describes an acceptable way for licensees to satisfy the requirements contained in 10 CFR 50.36.
3.0 TECHNICAL EVALUATION
The NRC staff evaluated the licensees application to determine if the proposed changes are consistent with the guidance, regulations, and plant-specific design and licensing basis information discussed in Section 2.3 of this safety evaluation.
3.1 Revision to SR 3.6.15.1 The licensee is required by SR 3.6.15.1 to verify annulus negative pressure is equal to or more negative than -5 inches water gauge with respect to the atmosphere every 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />. The licensee has proposed to revise the negative pressure value in the requirement from -5 inches water gauge to -1 inch water gauge.
Table 3.2.1-1 of the license amendment request indicates that the current large break LOCA (LBLOCA) analysis of record for Watts Bar, Units 1 and 2, as documented in Section 15.5.3 of the Watts Bar, Units 1 and 2, Updated Final Safety Analysis Report (ADAMS Accession No. ML19176A135), assumes the annulus is initially at atmospheric conditions. It also states that the current value of -5 inch water gauge in SR 3.6.15.1 is the same as that used in the original analysis of offsite and control room doses due to a LBLOCA for Watts Bar, Unit 1. The NRC staff confirmed that Chapter 15 states that the dose analysis conservatively assumes the annulus is at atmospheric pressure at event initiation. The license amendment request also includes summary information on parameters and radiological consequences for the current LBLOCA analysis of record. The initial annulus pressure value used in these analyses is atmospheric. However, a negative pressure in the annulus region prior to the initiation of the EGTS system minimizes the possibility that radioactive material will bypass the filtering function of the EGTS in the event of leakage from the steel containment vessel into the annulus (e.g.,
from leaking penetrations). Therefore, during normal operations the annulus is kept at a negative pressure with respect to the atmosphere surrounding the shield building because doing so ensures that radioactive material from the primary containment atmosphere is restricted to leakage paths and leakage rates assumed in the safety analysis used to calculate offsite and control room LOCA doses.
The licensee has proposed a new negative pressure value of -1 inch water gauge with respect to the atmosphere for SR 3.6.15.1. Branch Technical Position 6-3, Revision 3, Determination of Bypass Leakage Paths in Dual Containment Plants, (ADAMS Accession No. ML070740004),
states that a positive pressure with regard to secondary containment structures is defined as any pressure greater than -0.25 inch water gauge, which conservatively accounts for wind loads and the uncertainty in pressure measurements. In addition to measurement uncertainties, annulus pressure may also vary with elevation due to temperature-induced differences in the pressure gradients inside and outside the secondary containment, as described in Information Notice No. 88-76, Recent Discovery of a Phenomenon not Previously Considered in the Design of Secondary Containment Pressure Control, (ADAMS Accession No. ML031150101).
The Watts Bar, Units 1 and 2, Shield Building pressure sensors are located at an elevation of 783 feet, while the upper elevation of the Shield Building is 879.04 feet. The differential pressure caused by stack effect inside of the Shield Building must also be considered, based on the instrument elevation. Based on these considerations, the licensee determined that a measured value of -0.63 inch water gauge at the elevation of the pressure sensors will ensure that the pressure at any elevation in the annulus will be equal to or more negative than -0.25 inch water gauge The ability to maintain the annulus at the required negative pressure of at least -0.63 inches water gauge at or above an elevation of 783 feet ensures that the annulus negative pressure is at least -0.25 inches water gauge everywhere in the annulus. The new TS value will continue to maintain the annulus at a negative pressure (i.e., below -0.25 inches water gauge) and therefore the assumptions about the initial annulus pressure used in the LBLOCA dose calculation will continue to be conservative and the licensees proposed annulus pressure change will not adversely impact the dose analyses.
The acceptance criteria for radiological accident consequence analyses are divided into doses impacting the public at the exclusion area boundary and low population zone, as defined in 10 CFR 100.11, and those impacting the operators in the control room, as defined in the GDC 19. The dose consequence values from the licensees LBLOCA analyses are included in Tables 3.2.1-9 and 3.2.1-10 of the license amendment request, for Watts Bar, Units 1 and 2, respectively. For both units, the current licensing basis LBLOCA analyses continue to meet the NRCs acceptance criteria after implementation of this change. Therefore, the plant will continue to comply with the requirements of 10 CFR 100.11 and GDC 19. As a result, the NRC staff finds that the proposed change to the TS 3.6.15.1 shield building annulus differential pressure requirement to -1 inch water gauge with respect to the atmosphere satisfies the requirement of 10 CFR 50.36(c)(3) and is, therefore, acceptable.
3.2 Deletion of TS 3.6.15, Condition B Condition B of TS 3.6.15 requires an eight-hour completion time for required actions if the annulus pressure requirement in SR 3.6.15.1 is not met. Further, the Note associated with Condition B states:
Annulus pressure requirement is not applicable during ventilating operations, required annulus entries, or Auxiliary Building isolations not exceeding 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> in duration, or while Penetration 1-EQH-271-0010 or 1-EQH-271-0011in the Shield Building dome is open until annulus pressure is restored.*
- 1.
The combined opening time of Penetrations 1-EQH-271-0010 or 1-EQH-271-0011 is limited to a total time of five hours a day, six days a week during Cycle 7 operation.
- 2.
Penetrations 1-EQH-271-0010 or 1-EQH-271-0011 in the Shield Building Dome may not be opened if in Action Conditions LCO 3.6.9A or 3.8.1B.
- 3.
Upon opening Penetration 1-EQH-271-0010 or 1-EQH-271-0011 in the Shield Building Dome, both EGTS control loops shall be placed in the A-Auto Stand-by position and returned to normal position following closure of penetration.
The Note allows for a one-hour window in which the annulus pressure requirements defined in SR 3.6.15.1 do not need to be met during ventilating and required annulus entries. Deletion of the note would remove the exception, and therefore the licensee would be required to restore annulus pressure to the SR 3.6.15.1 requirement, even during ventilating and required annulus entries.
To determine the effect of routine activities on normal annulus pressure, the licensee collected and reviewed the annulus differential pressure for readings during a 12-month period for Watts Bar, Units 1 and 2, and found that the routine activities did not result in annulus differential pressure being equal to or less negative than the -1 inch water gauge proposed for SR 3.6.15.1.
The routine annulus entries during normal operation in the 12-month period caused the Watts Bar, Unit 1, annulus differential pressure to drop to a level no less negative than -5.45 inch water gauge, and the Watts Bar, Unit 2, annulus differential pressure to drop to a level no less negative than -4.0 inch water gauge Also, footnotes 1, 2, and 3 associated with Watts Bar, Unit 1 TS 3.6.15, Condition B are specific to Cycle 7 operation and are no longer applicable.
In the license amendment request, the licensee observed that the 8-hour completion time associated with the current annulus pressure requirement in TS 3.6.15, Condition B is overly conservative when compared to the 24-hour completion time associated with the Condition A requirement to restore shield building operability, which would have a more significant impact on the ability to maintain the appropriate level of negative pressure in the annulus region.
Therefore, the licensee concludes that since Condition A to TS 3.6.15 is adequate for ensuring shield building operability Condition B is overly conservative and can be deleted.
The Watts Bar shield buildings meet the criteria for LCOs described in the requirements at 10 CFR 50.36(c)(2). NUREG-1431, STS3.6.8 describes an acceptable approach to defining LCOs for shield buildings. This STS does not include a condition that references annulus pressure. Instead, the STS requires the shield building operability to be verified, in part, by periodic checks of annulus pressure. Per the STS, if the surveillance requirement is not met, the shield building would be declared inoperable with a 24-hour completion time to restore the shield building to operable status (i.e. restore the annulus pressure within the appropriate limit).
The licensees proposed change would make the Watts Bar, Units 1 and 2, TSs consistent with the STS. Further, because the licensee has collected data showing that annulus pressure during entries made over a 12-month period has remained more negative than -1 inch water gauge, which is the proposed revised limit for TS 3.6.15 (discussed in Section 3.1), there is no site-specific need for the exception that was provided by Condition B. Therefore, the NRC staff finds that the licensee will continue to meet the requirements of 10 CFR 50.36(c)(2) after the proposed change. As a result, the NRC staff finds the proposed deletion of TS 3.6.15, Condition B and the resulting re-designation of Condition C to Condition B acceptable.
4.0 STATE CONSULTATION
In accordance with the Commissions regulations, the Tennessee State official was notified of the proposed issuance of the amendment on September 1, 2020. The State official had no comments.
5.0 ENVIRONMENTAL CONSIDERATION
The amendments change a requirement with respect to installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20 and change SRs.
The NRC staff has determined that the amendments involve 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 previously issued a proposed finding that the amendments involve no significant hazards consideration, published in the Federal Register (FR) on February 25, 2020 (85 FR 10734), and there has been no public comment on such finding.
Accordingly, the amendments meet the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9). Pursuant to 10 CFR 51.22(b), no environmental impact statement or environmental assessment need be prepared in connection with the issuance of the amendments.
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.
7.0 REFERENCES
Principal Contributors:
D. Garmon A. Stubbs Date: December 8, 2020
- by e-mail OFFICE NRR/DORL/LPL2-2/PM NRR/DORL/LPL2-2/LA NRR/DSS/SCPB/BC*
NAME MWentzel BAbeywickrama BWittick DATE 09/14/2020 09/09/2020 05/01/2020 OFFICE NRR/DRA/ARCB/BC*
NRR/DSS/STSB/BC*
NAME KHsueh VCusumano STurk DATE 08/19/2020 09/15/2020 10/01/2020 OFFICE NRR/DORL/LPL2-2/BC*
NRR/DORL/LPL2-2/PM NAME UShoop MWentzel DATE 12/08/2020 12/8/2020