CNL-20-087, Non-Voluntary Application to Modify Watts Bar Nuclear Plant Unit 1 and Unit 2 Technical Specifications Surveillance Requirement 3.6.15.4, Shield Building, (WBN-TS-20-017)
| ML20350B764 | |
| Person / Time | |
|---|---|
| Site: | Watts Bar  |
| Issue date: | 12/15/2020 |
| From: | Polickoski J Tennessee Valley Authority |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| CNL-20-087, WBN-TS-20-017 | |
| Download: ML20350B764 (25) | |
Text
Tennessee Valley Authority, 1101 Market Street, Chattanooga, Tennessee 37402 CNL-20-087 December 15, 2020 10 CFR 50.90 ATTN: Document Control Desk U.S. Nuclear Regulatory Commission Washington, D.C. 20555-0001 Watts Bar Nuclear Plant, Units 1 and 2 Facility Operating License Nos. NPF-90 and NPF-96 NRC Docket Nos. 50-390 and 50-391
Subject:
Non-Voluntary Application to Modify Watts Bar Nuclear Plant Unit 1 and Unit 2 Technical Specifications Surveillance Requirement 3.6.15.4, Shield Building," (WBN-TS-20-017)
In accordance with the provisions of Title 10 of the Code of Federal Regulations (10 CFR)
Part 50.90, "Application for amendment of license, construction permit, or early site permit,"
Tennessee Valley Authority (TVA) is submitting a non-voluntary request for an amendment to the Technical Specifications (TS) for the Watts Bar Nuclear Plant (WBN), Units 1 and 2.
As discussed in the enclosure to this license amendment request (LAR), TVA has determined that the current WBN Units 1 and 2 TS Surveillance Requirement (SR) 3.6.15.4, Shield Building, requirement to maintain an inleakage of 250 cfm at -0.61 inches water gauge (in. w.g.) is nonconservative with respect to the WBN accident analysis. Therefore, the LAR revises WBN Units 1 and 2 SR 3.6.15.4 to resolve this non-conservatism and align the SR with the Westinghouse Standard TS (NUREG-1431, Revision 4).
The enclosure provides a description of the proposed changes, technical evaluation of the proposed changes, regulatory evaluation, and a discussion of environmental considerations. to the enclosure provides a history of WBN Units 1 and 2 SR 3.6.15.4.
Attachments 2 and 3 to the enclosure provide the existing WBN Units 1 and 2 TS marked-up to show the proposed changes. Attachments 4 and 5 to the enclosure provide the existing WBN Units 1 and 2 TS pages retyped to show the proposed changes. Attachments 6 and 7 to the enclosure provide the existing WBN Units 1 and 2 TS Bases pages marked-up to show the proposed changes. Changes to the existing TS Bases are provided for information only and will be implemented under the TS Bases Control Program.
U.S. Nuclear Regulatory Commission CNL-20-087 Page 2 December 15, 2020 As discussed above, this LAR is required to correct a nonconservative SR. Currently plant operations are administratively controlled as described in NRC Regulatory Guide (RG) 1.239, Licensee Actions to Address Nonconservative Technical Specifications.
In accordance with the guidance in RG 1.239, this LAR is required to resolve a nonconservative SR and is not a voluntary request from a licensee to change its licensing basis. The issue related to the nonconservative SR has been entered into the TVA corrective action program and the applicable surveillance instructions have been revised to resolve the non-conservatism.
TVA determined that there are no significant hazards considerations associated with the proposed change and that the TS change qualifies for a categorical exclusion from environmental review pursuant to the provisions of 10 CFR 51.22(c)(9). In accordance with 10 CFR 50.91(b)(1), TVA is sending a copy of this letter and the enclosure to the Tennessee Department of Environment and Conservation.
TVA requests NRC approval of the proposed license amendment within one year from the date of this submittal and implementation within 30 days from the date of approval.
There are no new regulatory commitments associated with this submittal. Please address any questions regarding this submittal to Kimberly D. Hulvey, Senior Manager, Fleet Licensing, at 423-751-3275.
I declare under penalty of perjury that the foregoing is true and correct. Executed on this 15th day of December 2020.
Respectfully, James T. Polickoski Director, Nuclear Regulatory Affairs
Enclosure:
Evaluation of Proposed Change cc (Enclosure):
NRC Regional Administrator - Region II NRC Senior Resident Inspector - Watts Bar Nuclear Plant NRC Project Manager - Watts Bar Nuclear Plant Director, Division of Radiological Health - Tennessee State Department of Environment and Conservation
Enclosure CNL-20-087 E1 of 9 Evaluation of Proposed Change
Subject:
Application to Modify Watts Bar Nuclear Plant (WBN) Unit 1 and Unit 2 Technical Specifications 3.6.15, Shield Building," (WBN-TS-19-10)
CONTENTS 1.0 Summary Description...................................................................................................... 2 2.0 Detailed Description........................................................................................................ 2 2.1 Background.................................................................................................................. 2 2.2 Description of the Proposed Changes.......................................................................... 2 2.3 Reason for the Proposed Changes.............................................................................. 3 3.0 Technical Evaluation....................................................................................................... 3 3.1 System Description...................................................................................................... 3 3.1.1 Shield Building...................................................................................................... 3 3.1.2 Containment......................................................................................................... 4 3.1.3 EGTS.................................................................................................................... 4 3.2 Technical Analysis....................................................................................................... 5 3.2.1 Proposed Change to SR 3.6.15.4......................................................................... 5 3.2.2 Proposed Deletion of the Inleakage Flow Requirement in SR 3.6.15.4................. 5 4.0 Regulatory Evaluation..................................................................................................... 6 4.1 Applicable Regulatory Requirements/Criteria............................................................... 6 4.2 Precedent.................................................................................................................... 7 4.3 Significant Hazards Consideration............................................................................... 7 4.4 Conclusions................................................................................................................. 8 5.0 Environmental Consideration........................................................................................... 8 6.0 Reference........................................................................................................................ 9 ATTACHMENTS
- 2. Proposed TS Changes Mark-Ups for WBN Unit 1
- 3. Proposed TS Changes Mark-Ups for WBN Unit 2
- 4. Proposed TS Changes (Final Typed) for WBN Unit 1
- 5. Proposed TS Changes (Final Typed) for WBN Unit 2
- 6. Proposed TS Bases Page Changes (Mark-Ups) for WBN Unit 1(For Information Only)
- 7. Proposed TS Bases Page Changes (Mark-Ups) for WBN Unit 2 (For Information Only)
Enclosure CNL-20-087 E2 of 9 1.0
SUMMARY
DESCRIPTION Pursuant to Title 10 of the Code of Federal Regulations (10 CFR) 50.90, Application for amendment of license, construction permit, or early site permit, Tennessee Valley Authority (TVA) is requesting a non-voluntary license amendment to amend the Facility Operating Licenses (OLs) NPF-90 and NPF-96 for the Watts Bar Nuclear Plant (WBN),
Units 1 and 2, respectively. The proposed license amendment revises WBN Units 1 and 2 Technical Specification (TS) Surveillance Requirement (SR) 3.6.15.4, "Shield Building," to resolve a non-conservatism and align the SR with the Westinghouse Standard TS (STS) in NUREG-1431, Revision 4.
Currently plant operations are administratively controlled as described in Nuclear Regulatory Commission (NRC) Regulatory Guide (RG) 1.239, Licensee Actions to Address Nonconservative Technical Specifications. In accordance with the guidance in RG 1.239, this license amendment request (LAR) is required to resolve a nonconservative SR and is not a voluntary request from a licensee to change its licensing basis. The issue related to the nonconservative SR has been entered into the TVA corrective action program and the applicable surveillance instructions have been revised to resolve the non-conservatism.
2.0 DETAILED DESCRIPTION
2.1 BACKGROUND
TVA has determined that the current WBN Units 1 and 2 SR 3.6.15.4 requirement to maintain an inleakage of 250 cubic feet per minute (cfm) at an annulus pressure equal to or more negative than -0.61 inches water gauge (in. w.g.) is nonconservative with respect to the WBN accident analysis for a loss of coolant accident (LOCA).
Specifically, WBN Units 1 and 2 TS 3.6.15 Bases states Maintaining shield building operability ensures that the release of radioactive material from the containment atmosphere is restricted to those leakage paths and associated leakage rates assumed in the accident analyses. The WBN accident analysis assumes the Emergency Gas Treatment System (EGTS) maintains the Shield Building at -1.45 in. w.g. with an inleakage of 250 cfm. The SR allows an inleakage of 250 cfm at -0.61 in. w.g., but would correspond to an inleakage greater than 250 cfm at -1.45 in. w.g. Therefore, the current SR 3.6.15.4 has the potential to allow conditions that are not bounded by the accident analysis. Based on a review of the past three years performances of the associated surveillance instructions for SR 3.6.15.4, the inleakage did not exceed 250 cfm when corrected to -1.45 in. w.g. Therefore, the operability of the Shield Building has been and is currently maintained.
to this enclosure provides a history of WBN Units 1 and 2 SR 3.6.15.4.
2.2 DESCRIPTION
OF THE PROPOSED CHANGES WBN Units 1 and 2 SR 3.6.15.4 currently states:
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.
Enclosure CNL-20-087 E3 of 9 The proposed change revises WBN Units 1 and 2 SR 3.6.15.4 as follows:
Verify the Shield Building can be maintained at an annulus pressure equal to or more negative than -0.63 inch water gauge at elevation 783 with respect to the atmosphere by one Emergency Gas Treatment System train with final flow 3600 and 4400 cfm within 20 seconds from the initiation after a start signal.
Attachments 2 and 3 to the enclosure provide the existing WBN Units 1 and 2 TS marked-up to show the proposed changes. Attachments 4 and 5 to the enclosure provide the existing WBN Units 1 and 2 TS pages retyped to show the proposed changes. Attachments 6 and 7 to the enclosure provide the existing WBN Units 1 and 2 TS Bases pages marked-up to show the proposed changes. Changes to the existing TS Bases are provided for information only and will be implemented under the TS Bases Control Program.
2.3 REASON FOR THE PROPOSED CHANGES The reason for the proposed license amendment is as follows:
- 1. Resolve the non-conservatism in WBN Units 1 and 2 SR 3.6.15.4 as discussed in Section 2.1 of this enclosure.
- 2. Align SR 3.6.15.4 with Westinghouse STS SR 3.6.8.4, Shield Building (Dual and Ice Condenser), in NUREG 1431, Revision 4. STS SR 3.6.8.4 is applicable to WBN in that the WBN containment design includes an ice condenser and a separate reinforced concrete Shield Building that surrounds the steel containment vessel. The WBN Shield Building also ensures proper operation of the EGTS and limits the radioactive leakage from the containment to those paths and leakage rates assumed in the accident analysis.
3.0 TECHNICAL EVALUATION
3.1 SYSTEM DESCRIPTION A description of the relevant systems and structures is presented below as background for evaluation of the proposed changes.
3.1.1 Shield Building The Shield Building is a reinforced concrete cylinder structure surrounding the steel containment structure. An annulus space exists between the steel containment vessel and the inside of the Shield Building. The Shield Building is supported by a circular base slab and covered at the top with a spherical dome. It is designed to provide the following:
- 1. radiation shielding from accident conditions
- 2. radiation shielding from parts of the Reactor Coolant System (RCS) during operation
- 3. protection of the steel containment vessel from adverse atmospheric conditions and external missiles propelled by tornado winds The Shield Building for each unit is located adjacent to the Auxiliary Building.
Enclosure CNL-20-087 E4 of 9 3.1.2 Containment The containment is a low-leakage, freestanding steel pressure vessel surrounded by the reinforced concrete Shield Building. Containment piping penetration assemblies provide for the passage of process, service, sampling, and instrumentation pipelines into the containment vessel while maintaining containment integrity.
The inner steel containment and its penetrations establish the boundary of the containment, limiting the leakage of fission product radioactivity from the containment to the environment. The design basis for the containment is that the containment must withstand the pressures and temperatures of the limiting design basis accident (DBA) without exceeding the design leakage rates.
3.1.3 Emergency Gas Treatment System The EGTS establishes a negative pressure in the annulus between the Shield Building and the steel containment vessel. Filters in the system control the release of radioactive contaminants to the environment.
The design bases for the EGTS are:
- 1. 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
- 2. to reduce the concentration of radioactive nuclides in the 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 (LPZ) dose below the 10 CFR 100 values
- 3. to withstand the safe shutdown earthquake
- 4. to provide for initial and periodic testing of the system capability to function as designed The negative pressure control setpoint chosen for post-accident operation is low enough that leakage across the boundary is into the annulus from both the primary containment and areas adjacent to the Shield Building. Appropriate selection of the annulus negative pressure level also overcomes the pressure differentials produced by wind and temperature effects.
The EGTS consists of two separate and redundant trains. Each train includes a heater, a prefilter, moisture separators, a high efficiency particulate air (HEPA) filter, an activated charcoal adsorber section for removal of radioiodines, and a fan. Ductwork, valves, dampers, and instrumentation also form part of the system. The moisture separators function to reduce the moisture content of the airstream. A second bank of HEPA filters follows the adsorber section to collect carbon fines and provide backup in case of failure of the main HEPA filter bank. The system initiates and maintains a negative air pressure in the Shield Building by means of filtered exhaust ventilation of the Shield Building following receipt of a safety injection signal.
Enclosure CNL-20-087 E5 of 9
3.2 TECHNICAL ANALYSIS
3.2.1 Proposed Change to SR 3.6.15.4 As previously noted in Section 2.0 to this enclosure, the proposed change to WBN Units 1 and 2 SR 3.6.15.4 resolves a non-conservatism and aligns the SR with the Westinghouse STS in NUREG-1431, Revision 4. The proposed changes to SR 3.6.15.4 eliminate this non-conservatism by revising the annulus pressure requirement and replacing the inleakage requirement with a time requirement. Further justification for the change to the annulus pressure requirement is provided below and the justification for the deletion of the inleakage flow requirement is provided in Section 3.2.2 to this enclosure. The EGTS flow requirement remains the same.
As noted in NUREG-1431, Revision 4, Westinghouse STS SR 3.6.8, Shield Building (Dual and Ice Condenser), the values for the annulus pressure requirement and the time requirement for drawing down the Shield Building to a negative pressure following a start signal are bracketed, meaning they are plant-specific values. The annulus pressure used is the value that ensures a negative pressure at all elevations. As stated in Branch Technical Position (BTP) 6-3, a positive pressure with regard to secondary containment structures is defined as any pressure greater than -0.25 in. w.g., to conservatively account for wind loads and the uncertainty in pressure measurements.
Also, Information Notice (IN) 88-76 documents a phenomenon where the pressure inside the secondary containment is not maintained at higher elevations due to temperature induced differential pressure effects. WBN pressure sensors for the Shield Building are located at elevation 783 while the upper elevation of the Shield Building is at elevation 879.04. As noted in the American Society of Heating, Refrigerating and Air-Conditioning (ASHRAE) Handbook of Fundamentals, the differential pressure caused by stack effect inside of the Shield Building must also be considered, based on the instrument elevation. The current annulus pressure value that considers these effects (i.e., -0.61 in. w.g.) was found to be in error.
As noted in TVA letter to NRC, CNL-19-077 (Reference 1), Section 3.2.1, TVA determined that a calculated value of -0.63 inch w.g. at the elevation of the pressure sensors ensures the pressure at any elevation in the annulus is equal to or more negative than -0.25 inch w.g. Therefore, TVA has revised the value of -0.61 in. w.g.
to -0.63 in. w.g in SR 3.6.15.4.
The proposed time requirement for the EGTS of 20 seconds after a start signal ensures that the Shield Building can be rapidly drawn down to a negative pressure at all elevations in the Shield Building and ensures that no significant quantity of radioactive material leaks from the Shield Building prior to developing the negative pressure. This value is not directly used in the safety analysis, but is a surrogate to demonstrate the integrity of the Shield Building is maintained.
3.2.2 Proposed Deletion of the Inleakage Flow Requirement in SR 3.6.15.4 The proposed change deletes the inleakage requirement of 250 cfm in SR 3.6.15.4.
As noted in Attachment 1 to this enclosure, this parameter originated in Revision 0 to the STS; however, this parameter is no longer included in any SR in Revision 4 of STS. The proposed change further aligns WBN Units 1 and 2 SR 3.6.15.4 with the STS 3.6.8.4.
TVA plans to retain this inleakage requirement in the applicable design output
Enclosure CNL-20-087 E6 of 9 documents supporting the safety analysis and the surveillance instructions for SR 3.6.15.4. Any future change to this value would be reviewed under 10 CFR 50.59 to determine if prior NRC approval is required.
4.0 REGULATORY EVALUATION
4.1 APPLICABLE REGULATORY REQUIREMENTS/CRITERIA General Design Criteria WBN Units 1 and 2 were designed to meet the intent of the "Proposed General Design Criteria for Nuclear Power Plant Construction Permits" published in July 1967. The WBN construction permit was issued in January 1973. The WBN dual-unit Updated Final Safety Analysis (UFSAR), however, addresses the NRC General Design Criteria (GDC) published as Appendix A to 10 CFR 50 in July 1971, including Criterion 4 as amended October 27, 1987. Each relevant criterion listed below is followed by a discussion of the design features and procedures that meet the intent of the criteria.
GDC 16 - Containment Design Reactor containment and associated systems shall be provided to establish an essentially leak-tight barrier against the uncontrolled release of radioactivity to the environment and to assure that the containment design conditions important to safety are not exceeded for as long as postulated accident conditions require.
Compliance with GDC 16 is described in UFSAR Section 3.1.2.2.
GDC 19 - Control Room 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 a safe condition under accident conditions, including loss-of-coolant accidents. 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 controls 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.
Compliance with GDC 19 is described in UFSAR Section 3.1.2.2.
GDC 60 - Control of Releases of Radioactive Materials to the Environment The nuclear power unit design include means to control suitably the release of radioactive materials in gaseous and liquid effluents and to handle radioactive solid wastes produced during normal reactor operation, including anticipated operational occurrences.
Compliance with GDC 60 is described in UFSAR Section 3.1.2.6.
Enclosure CNL-20-087 E7 of 9 4.2 PRECEDENT There are no applicable regulatory precedents regarding the changes proposed in this license amendment request. However, the proposed change to WBN Units 1 and SR 3.6.15.4 is consistent with the Westinghouse STS in NUREG-1431, Revision 4.
4.3 SIGNIFICANT HAZARDS CONSIDERATION Tennessee Valley Authority (TVA) is requesting an amendment to Facility Operating Licenses NPF-90 and NPF-96 for the Watts Bar Nuclear Plant (WBN), Units 1 and 2, respectively. The proposed amendment revises existing WBN Units 1 and 2 Technical Specification (TS) Surveillance Requirement (SR) 3.6.15.4, Shield Building. The current WBN Units 1 and 2 SR 3.6.15.4 requirement to maintain an inleakage of 250 cubic feet per minute (cfm) at -0.61 inches water gauge (in. w.g.) is nonconservative with respect to the WBN accident analysis. Therefore, the proposed amendment revises WBN Units 1 and 2 SR 3.6.15.4 to resolve this non-conservatism and align the SR with the Westinghouse Standard TS (NUREG-1431, Revision 4).
TVA has evaluated whether or not a significant hazards consideration is involved with the proposed amendment(s) by focusing on the three standards set forth in 10 CFR 50.92, Issuance of Amendment, as discussed below.
- 1. Does the proposed amendment involve a significant increase in the probability or consequences of an accident previously evaluated?
Response: No.
The proposed changes do not require physical changes to plant systems, structures, or components. The Shield Building is a passive accident mitigating feature. As such, the Shield Building is not associated with a potential accident-initiating mechanism. The revised plant-specific value for the Shield Building Annulus differential pressure requirement and addition of the time requirement provided in SR 3.6.15.4 ensures the Shield Building can be rapidly drawn down to a negative pressure and ensures no significant release of radioactivity before achieving the negative pressure. These changes did not require a revision to the safety analyses.
Therefore, the changes do not affect accident or transient initiation or consequences.
Based on the above, it is concluded that the proposed change does not involve a significant increase in the probability or consequences of an accident previously evaluated.
- 2. Does the proposed amendment create the possibility of a new or different kind of accident from any accident previously evaluated?
Response: No.
The proposed changes do not introduce new or different accidents to be postulated and subsequently evaluated, and no changes are being made to the plant that would introduce any new accident causal mechanisms. This license amendment request does not affect any plant systems that are potential accident initiators; nor does it have any significantly adverse effect on any accident mitigating systems.
Enclosure CNL-20-087 E8 of 9 Based on the above, it is concluded that the proposed change does not create the possibility of a new or different kind of accident from any previously evaluated.
- 3. Does the proposed amendment involve a significant reduction in a margin of safety?
Response: No.
The proposed changes do not alter the permanent plant design, nor does it change the assumptions contained in the safety analyses. Margin of safety is related to the ability of the fission product barriers to perform their design functions during and following accident conditions. These barriers include the fuel cladding, the reactor coolant system, and the containment system. The performance of these barriers is not degraded by the proposed change. The proposed change in the annulus pressure requirement ensures the Shield Building can be maintained at a negative pressure with respect to the surrounding environments. The proposed time requirement ensures that the Shield Building can be rapidly drawn down to a negative pressure at all elevations in the Shield Building and ensures that no significant quantity of radioactive material leaks from the Shield Building prior to developing the negative pressure. The proposed change does not require a change to the safety analysis.
Therefore, the proposed change does not involve a significant reduction in a margin of safety.
Based on the above, TVA concludes that the proposed amendment does not involve a significant hazards consideration under the standards set forth in 10 CFR 50.92(c), and, accordingly, a finding of no significant hazards consideration is justified.
4.4 CONCLUSION
S 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 Commissions 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.
5.0 ENVIRONMENTAL CONSIDERATION
A review 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 in 10 CFR 20, or would change an inspection or surveillance requirement. However, the proposed amendment does not involve (i) a significant hazards consideration, (ii) a significant change in the types or significant increase in the amounts of any effluents 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 be prepared in connection with the proposed amendment.
Enclosure CNL-20-087 E9 of 9 6.0 REFERENCE
- 1. TVA letter to NRC, CNL-19-077, Application to Modify Watts Bar Nuclear Plant (WBN) Unit 1 and Unit 2 Technical Specifications 3.6.15, Shield Building, (WBN-TS-19-10), dated December 6, 2019 (ML19340B773)
Enclosure CNL-20-087 Att 1-1 of 2 History of WBN Units 1 and 2 SR 3.6.15.4 A document review of the historical development and evolution of the WBN TS, prior to issuance of WBN Unit 1 Operating License, provided the following historical basis regarding the current WBN Units 1 and 2 SR 3.6.15.4.
NRC transmitted the final draft TS for WBN Unit 1 on February 15, 1985 (Reference 1). The NRC transmittal letter stated:
These Technical Specifications were developed utilizing the Westinghouse Standard Technical Specifications (W-STS), Revision 4, as a basis. They reflect plant-specific design requirements, new regulatory requirements issued since the development of the W-STS Revision 4, and operating experience from other recently licensed W plants.
On April 17, 1990 (Reference 2), TVA issued the proposed draft TS for WBN Unit 1 based on the Restructured Standard Technical Specifications (RSTS). It should be noted that the RSTS formed the basis for and evolved into NUREG-1431. Current SR 3.6.15.4 was initially based on RTS SR 3.6.5.5 for the Emergency Gas Treatment System (EGTS) as follows:
Demonstrate each EGTS train produces a pressure equal to or more negative than
[-0.5] inches water gauge in the annulus relative to the Mechanical Equipment Room El. 772 within [ ] minute after a start signal with an inleakage of [500] cfm.
Subsequently, on August 27, 1992, TVA revised and updated the draft TS (Reference 3) to be in accordance with the latest draft of NUREG-1431, Standard Technical Specifications -
Westinghouse Plants, Revision 0. EGTS SR 3.6.5.5 was renumbered as SR 3.6.9.4 as follows:
Verify each EGTS train produces an annulus pressure equal to or more negative than
- 0.5 inch water gauge with respect to the El. 772 mechanical equipment-room with an inleakage of 250 cfm at a system flow of 4000 + 10% cfm.
In September 1992, NUREG-1431, Revision 0, was published. New STS 3.6.19, Shield Building (Dual and Ice Condenser), SR 3.6.19.4 stated:
Verify each Shield Building Air Cleanup System train with final flow [ ] cfm produces a pressure equal to or more negative than [-0.5] inch water gauge in the annulus within
[22] seconds after a start signal.
On April 2, 1993 (Reference 4), NRC transmitted the proof and review version of the WBN Unit 1 TS for TVAs review and comment. SR 3.6.9.4 for the EGTS revised as follows, Verify each EGTS train flow rate is 3600 and < 4400 cfm. New SR 3.6.15.4 was created as follows:
Verify each Emergency Gas Treatment System train with final flow 3600 and 4400 cfm produces an annulus pressure equal to or more negative than -0.5 inch water gauge with respect to EL. 772 mechanical equipment room and with an inleakage of 250 cfm within [TDB] seconds after a start signal.
Enclosure CNL-20-087 Att 1-2 of 2 The WBN Unit 1 operating license was issued on February 7, 1996 (Reference 5). The time requirement in SR 3.6.15.4 was moved to SR 3.6.9.4 for the EGTS. SR 3.6.9.4 was revised as follows:
Verify each EGTS train flow rate is 3600 and 4400 cfm within 20 seconds from the initiation of a Containment Isolation Phase A signal.
SR 3.6.15.4 was revised as follows:
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.
This is the current verbiage for SRs 3.6.9.4 and 3.6.15.4. The WBN Unit 2 OL was issued on October 22, 2015 (Reference 6) and mirrored the WBN Unit 1 TS.
STS SR 3.6.8.4, Shield Building (Dual and Ice Condenser), in NUREG-1431, Revision 4 states:
Verify the shield building can be maintained at a pressure equal to or more negative than [-0.5] inch water gauge in the annulus by one Shield Building Air Cleanup System train with final flow [ ] cfm within [22] seconds after a start signal.
REFERENCES
- 1. NRC letter to TVA, Final Draft Technical Specifications for the Watts Bar Nuclear Plant, Unit 1, dated February 15, 1985 (ML073511912)
- 2. TVA letter to NRC, Watts Bar Nuclear Plant (WBN) Unit 1 - Proposed Technical Specifications (TS), dated April 17, 1990 (ML073520334 and ML073610028)
- 3. TVA letter to NRC, Watts Bar Nuclear Plant (WBN) Unit 1 - Proposed Technical Specifications (TS), dated August 27, 1992 (ML073600872 and ML073200281)
- 4. NRC letter to TVA, Watts Bar Unit 1 - Proof and Review Version of Technical Specification (TAC M76742), dated April 2, 1993 (ML073230276)
- 5. NRC letter to TVA, Issuance of Facility Operating License No. NPF-90, Watts Bar Nuclear Plant, Unit 1 (TAC M94025), dated February 7, 1996 (ML080290360 and ML073460319)
- 6. NRC letter to TVA, Issuance of Facility Operating License No. NPF-96, Watts Bar Nuclear Plant Unit 2, dated October 22, 2015 (ML15251A587)
Enclosure CNL-20-087 Proposed TS Changes (Mark-Ups) for WBN Unit 1
Shield Building 3.6.15 Watts Bar-Unit 1 3.6-41 Amendment 132, 139, XXX 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.
In accordance with the Surveillance Frequency Control Program 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 the Shield Building can be maintained at an each Emergency Gas Treatment System train with final flow 3600 and 4400 cfm produces an annulus pressure equal to or more negative than --
00.613 inch water gauge at elevation 783 with respect to the atmosphere and with an inleakage of 250 cfmby one Emergency Gas Treatment System train with final flow 3600 and 4400 cfm within 20 seconds after a start signal.
In accordance with the Surveillance Frequency Control Program
Enclosure CNL-20-087 Proposed TS Changes (Mark-Ups) for WBN Unit 2
Shield Building 3.6.15 Watts Bar - Unit 2 3.6-36 Amendment 36, 45, XX 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.
In accordance with the Surveillance Frequency Control Program 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 the Shield Building can be maintained ateach Emergency Gas Treatment System train with final flow 3600 cfm and 4400 cfm produces an annulus pressure equal to or more negative than - 0.613 inch water gauge at elevation 783 with respect to the atmosphere by one Emergency Gas Treatment System train with final flow 3600 and 4400 cfm within 20 seconds after a start signal.and with an inleakage of 250 cfm.
In accordance with the Surveillance Frequency Control Program
Enclosure CNL-20-087 Proposed TS Changes (Final Typed) for WBN Unit 1
Shield Building 3.6.15 Watts Bar-Unit 1 3.6-41 Amendment 132, 139, XXX 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.
In accordance with the Surveillance Frequency Control Program 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 the Shield Building can be maintained at an annulus pressure equal to or more negative than
-0.63 inch water gauge at elevation 783 with respect to the atmosphere by one Emergency Gas Treatment System train with final flow 3600 and 4400 cfm within 20 seconds after a start signal.
In accordance with the Surveillance Frequency Control Program
Enclosure CNL-20-087 Proposed TS Changes (Final Typed) for WBN Unit 2
Shield Building 3.6.15 Watts Bar - Unit 2 3.6-36 Amendment 36, 45, XX 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.
In accordance with the Surveillance Frequency Control Program 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 the Shield Building can be maintained at an annulus pressure equal to or more negative than - 0.63 inch water gauge at elevation 783 with respect to the atmosphere by one Emergency Gas Treatment System train with final flow 3600 and 4400 cfm within 20 seconds after a start signal.
In accordance with the Surveillance Frequency Control Program
Enclosure CNL-20-087 Proposed TS Bases Changes (Mark-Ups) for WBN Unit 1 (For Information Only)
Shield Building B 3.6.15 BASES Watts Bar-Unit 1 B 3.6-77 Revision 15, 29, 101, 129, 162 Amendment 132, XXX SURVEILLANCE SR 3.6.15.3 REQUIREMENTS (continued)
This SR would give advance indication of gross deterioration of the concrete structural integrity of the shield building. The Frequency of this SR is the same as that of SR 3.6.1.1. The verification is done during shutdown.
SR 3.6.15.4 The EGTS produces a negative pressure to prevent leakage from the building.
This Surveillance verifies that the shield building can be rapidly drawn down toThe EGTS is required to maintain a pressure equal to or more negative than
-0.50 inches of water gauge ("wg) in the annulus at an elevation equivalent to the top of the Auxiliary Building. This test is used to ensure shield building boundary integrity. At elevations higher than the Auxiliary Building, the EGTS is required to maintain a pressure equal to or more negative than -0.25 "wg. The low pressure sense line for the pressure controller is located in the annulus at elevation 783. By verifying that the annulus pressure is equal to or more negative than -0.613 "wg at elevation 783, the annulus pressurization requirements stated above are met. The ability of an EGTS train with final flow 3600 and 4400 cfm, within 20 seconds after a start signal, to produce the required negative pressure during the test operation provides assurance that the building is adequately sealed. The time limit ensures that no significant quantity of radioactive material leaks from the Shield Building prior to developing the negative pressure. Upon failure to meet this SR, the leak tightness of the shield building must be immediately assessed to determine the impact on the OPERABILITY of the shield building. The negative pressure prevents leakage from the building, since outside air will be drawn in by the low pressure at a maximum rate 250 cfm. The Surveillance Frequency is controlled under the Surveillance Frequency Control Program.
REFERENCES 1.
DELETED 2.
Watts Bar Drawing 1-47W605-242, "Electrical Tech Spec Compliance Tables."
3.
DCN 52216-A, Elimination of A-AUTO STANDBY Hand Switch Position for EGTS Pressure Control Loops.
4.
WBN UFSAR Section 6.2.3.2.2, Emergency Gas Treatment System (EGTS).
5.
WBN UFSAR Section 9.4.6, Reactor Building Purge Ventilating System (RBPVS).
Enclosure CNL-20-087 Proposed TS Bases Changes (Mark-Ups) for WBN Unit 2 (For Information Only)
Shield Building B 3.6.15 BASES Watts Bar - Unit 2 B 3.6-91 Revision 4, 34 Amendment 36, XX SURVEILLANCE REQUIREMENTS (continued)
SR 3.6.15.4 The EGTS produces a negative pressure to prevent leakage from the building. This Surveillance verifies that the shield building can be rapidly drawn down toThe EGTS is required to maintain a pressure equal to or more negative than -0.50 inches water gauge (" wg) in the annulus at an elevation equivalent to the top of the Auxiliary Building. This test is used to ensure shield building boundary integrity. At elevations higher than the Auxiliary Building, the EGTS is required to maintain a pressure equal to or more negative than -0.25" wg. The low pressure sense line for the pressure controller is located in the annulus at elevation 783. By verifying that the annulus pressure is equal to or more negative than -0.613" wg at elevation 783, the annulus pressurization requirements stated above are met. The ability of an EGTS train with final flow 3600 cfm and 4400 cfm, within 20 seconds after a start signal, to produce the required negative pressure during the test operation provides assurance that the building is adequately sealed. The time limit ensures that no significant quantity of radioactive material leaks from the Shield Building prior to developing the negative pressure. Upon failure to meet this SR, the leak tightness of the shield building must be immediately assessed to determine the impact on the OPERABILITY of the shield building. The negative pressure prevents leakage from the building, since outside air will be drawn in by the low pressure at a maximum rate 250 cfm. The Surveillance Frequency is controlled under the Surveillance Frequency Control Program.
REFERENCES
- 1.
- 2.
- 3.
Deleted.
WBN UFSAR Section 6.2.3.2.2, Emergency Gas Treatment System (EGTS).
WBN UFSAR Section 9.4.6, Reactor Building Purge Ventilating System (RBPVS).