L-20-223, License Amendment Request to Correct Non-conservative Technical Specification 3.7.4, Atmospheric Dump Valves (Advs)
| ML20288A444 | |
| Person / Time | |
|---|---|
| Site: | Beaver Valley |
| Issue date: | 10/13/2020 |
| From: | Penfield R Energy Harbor Nuclear Corp |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| L-20-223 | |
| Download: ML20288A444 (22) | |
Text
energy Energy Harbor Nuclear C01p.
harbor Beaver Valley Power Station P. 0. Box 4 Shippingport, PA I 5077 Rod L. Penfield 724-682-5234 Site Vice President, Beaver Valley Nuclear October 13, 2020 L-20-223 10 CFR 50.36(b)
ATTN: Document Control Desk U.S. Nuclear Regulatory Commission Washington , DC 20555-0001
SUBJECT:
Beaver Valley Power Station, Unit Nos. 1 and 2 Docket No. 50-334, License No. DPR-66 Docket No. 50-412, License No. NPF-73 License Amendment Request to Correct Non-conservative Technical Specification 3.7.4, "Atmospheric Dump Valves (ADVs)"
Pursuant to 10 CFR 50.36(b), Energy Harbor Nuclear Corp. is submitting a request to amend the Renewed Operating Licenses numbered DPR-66 and NPF-73 for the Beaver Valley Power Station (BVPS) , Unit Nos. 1 and 2, respectively. The proposed change corrects non-conservative Technical Specification 3.7.4 by increasing the number of required operable BVPS Unit No. 1 atmospheric dump valve lines from three to four to ensure equipment operability requirements are consistent with plant operation and safety analyses. This issue is tracked in the Energy Harbor Nuclear Corp. corrective action program, with compensatory actions completed , and an administrative control implemented until the license is amended.
An evaluation of the proposed change is enclosed. NRC staff approval is requested by October 29, 2021, and the amendment would be implemented within 30 days of approval.
This letter contains no new regulatory commitments. If there are any questions or if additional information is required, please contact Mr. Phil H. Lashley, Manager - Fleet Licensing , at (330) 696-7208.
I declare under penalty of perjury that the foregoing is true and correct. Executed on October_, 13 2020.
U7i!J Rod L. Penfield r
Beaver Valley Power Station, Unit Nos. 1 and 2 L-20-223 Page 2
Enclosure:
Evaluation of the Proposed Change cc: NRC Region I Administrator NRC Resident Inspector NRC Project Manager Director BRP/DEP Site BRP/DEP Representative
Evaluation of the Proposed Change Page 1 of 10
Subject:
License Amendment Request to Correct Non-conservative Technical Specification 3.7.4, Atmospheric Dump Valves (ADVs) 1.0
SUMMARY
DESCRIPTION 2.0 DETAILED DESCRIPTION 2.1 System Design and Operation 2.2 Current Technical Specification Requirements 2.3 Reason for the Proposed Change 2.4 Description of the Proposed Change
3.0 TECHNICAL EVALUATION
4.0 REGULATORY EVALUATION
4.1 Applicable Regulatory Requirements/Criteria 4.2 Precedent 4.3 No Significant Hazards Consideration Analysis 4.4 Conclusions
5.0 ENVIRONMENTAL CONSIDERATION
ATTACHMENTS:
- 1. Technical Specification Page Markups
- 2. Technical Specification Bases Page Markups (for information only)
Evaluation of the Proposed Change Beaver Valley Power Station, Unit Nos. 1 and 2 Page 2 of 10 1.0
SUMMARY
DESCRIPTION This evaluation supports a request to amend Operating Licenses DPR-66 for Beaver Valley Power Station Unit No. 1 (BVPS-1) and NPF-73 for Beaver Valley Power Station Unit No. 2 (BVPS-2).
The proposed amendment would change Technical Specification (TS) 3.7.4, Atmospheric Dump Valves (ADVs) limiting condition for operation (LCO) to be more restrictive by requiring four OPERABLE ADV lines for BVPS-1 instead of three. A corresponding change to a surveillance requirement is also proposed. As TS 3.7.4 is common to both BVPS-1 and BVPS-2, the changes to BVPS-1 that affect BVPS-2 are administrative in nature.
On March 30, 2017, an administrative control to require four OPERABLE ADV lines for BVPS-1 instead of three as currently required in TS 3.7.4 was implemented to address a non-conservatism in a vendor methodology communicated in Westinghouse Electric Company LLC (Westinghouse) Nuclear Safety Advisory Letter (NSAL) NSAL-07-11, Decay Heat Assumption in Steam Generator Tube Rupture Margin-to-Overfill Analysis Methodology. To resolve this issue, an industry Pressurized Water Reactor Owners Group project concluded a plant-specific evaluation of sensitivities to certain analysis input parameters would be necessary. The subsequent evaluation of the BVPS-1 steam generator tube rupture (SGTR) margin-to-overfill analysis identified that plant modifications were required to increase the heat removal capacity of the main steam system during a potential SGTR. The modifications were completed during a recent refueling outage, which installed manual isolation valves for each steam generator (SG) to a common residual heat release valve (RHRV) atmospheric dump line. These modifications enable the use of the RHRV in response to a potential SGTR, which provides increased heat removal capacity to mitigate the event. Emergency operating procedures have been updated to use this RHRV ADV line (the fourth OPERABLE ADV line) in response to a SGTR.
The current LCO 3.7.4 for BVPS-1 is non-conservative. Plant modifications and emergency operating procedure updates ensure BVPS-1 system operation in accordance with the SGTR analysis that credits the RHRV ADV line for mitigation of a potential SGTR. Therefore, the BVPS-1 RHRV ADV line satisfies Criterion 3 of 10 CFR 50.36(c)(2)(ii), and the proposed amendment is required to provide a TS limiting condition for operation that ensures compliance with the BVPS-1 design and licensing bases. provides the existing technical specification pages marked to show the proposed changes. Attachment 2 provides the existing technical specification bases pages annotated to show the proposed changes and is provided for information only.
Evaluation of the Proposed Change Beaver Valley Power Station, Unit Nos. 1 and 2 Page 3 of 10 2.0 DETAILED DESCRIPTION 2.1 System Design and Operation Various operator actions and plant equipment required to mitigate a potential SGTR are described in Section 3. One of the sequenced steps to address a SGTR uses the main steam system to remove heat and cooldown the primary coolant system as quickly as possible. Assuming a loss of offsite power, and therefore the unavailability of the main condenser to remove heat, the ADV lines on the intact SGs are credited to remove heat by dumping steam to the atmosphere as described below.
Section 10.3.1, Main Steam System, of the BVPS-1 Updated Final Safety Analysis Report (UFSAR) describes the main steam system. BVPS-1 is designed with three SGs, with each SG discharging into a main steam line. Each main steam line contains five ASME Code safety valves and one ADV. Each ADV has a capacity of 319,900 pounds (lb) per hour (hr) at a main steam inlet pressure of 1035 pounds per square inch gage (psig). These three ADV lines are required to be OPERABLE in the current technical specifications.
The RHRV is described in Section 10.3.1.2, Description, of the UFSAR. Each of the three main steam lines contains a line with a check valve that feeds a common header with a normally-open, manually-closed block valve and then a normally-closed, power-operated, RHRV. The RHRV has a capacity of 204,500 lb/hr when relieving from two SGs at a main steam inlet pressure of 1035 psig.
2.2 Current Technical Specification Requirements The current requirements for Technical Specification 3.7.4 that pertains to BVPS-1 is that three ADV lines shall be OPERABLE in Modes 1, 2, and 3, and Mode 4 when the SG is relied upon for heat removal.
Surveillance Requirements (SRs) 3.7.4.1 and 3.7.4.2 verify one complete cycle of each ADV and one complete cycle of each ADV block valve, respectively, with surveillance frequencies in accordance with the Surveillance Frequency Control Program.
2.3 Reason for the Proposed Change It was identified that the required main steam system heat removal capacity specified in the technical specifications to mitigate a potential steam generator tube rupture was not as conservative as previously understood.
The proposed change corrects the non-conservative minimum required OPERABLE ADV lines to the minimum number of lines that are currently assumed in the safety analyses and would allow Energy Harbor Nuclear Corp. to remove the administrative controls currently applied.
Evaluation of the Proposed Change Beaver Valley Power Station, Unit Nos. 1 and 2 Page 4 of 10 2.4 Description of the Proposed Change The proposed change would add a fourth BVPS-1 atmospheric dump valve line associated with the residual heat release valve to Technical Specification LCO 3.7.4.
LCO 3.7.4 would be changed from:
For Unit 1, three ADV lines shall be OPERABLE, For Unit 2, four ADV lines shall be OPERABLE.
To:
Four ADV lines shall be OPERABLE.
The note in SR 3.7.4.3 that states: Only applicable to Unit 2, would be removed.
SR 3.7.4.3 would be changed from the following (underline added to show the text to be deleted):
Verify one complete cycle of each individual steam generator isolation valve associated with the Unit 2 Residual Heat Release Valve ADV line.
To:
Verify one complete cycle of each individual steam generator isolation valve associated with the Residual Heat Release Valve ADV line.
3.0 TECHNICAL EVALUATION
The Applicable Safety Analyses and Background sections of the annotated changes to TS Bases 3.7.4 (Attachment 2) indicate that the only function of the ADVs required by the safety analyses is the ability to cool down the plant to residual heat removal system entry conditions following a design basis accident accompanied by a loss of offsite power. The Applicable Safety Analyses section further explains the limiting cooldown scenario for the ADVs is the SGTR accident.
The SGTR accident is described in Section 14.2.4, Steam Generator Tube Rupture, of the BVPS-1 UFSAR. Section 14.2.4.2.2 explains that during a SGTR, primary reactor coolant with elevated iodine concentrations (due to a pre-accident or a concurrent iodine spike) is transferred through a severed (ruptured) tube into the main steam secondary side. Prior to the reactor trip, activity is released to the environment through the condenser air ejector. It is conservatively assumed that after the reactor trip, airborne activity is released to the environment through secondary side steam from the main steam safety valves and the ADVs due to a loss of offsite power or failure of the condenser dump system. Airborne activity is also released through the intact SGs due to an assumed maximum allowable primary-to-secondary leakage (with the iodine
Evaluation of the Proposed Change Beaver Valley Power Station, Unit Nos. 1 and 2 Page 5 of 10 spike). Steam released through the intact SGs continues until the initiation of shutdown cooling (with the residual heat removal system) 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> after the accident.
In UFSAR Section 14.2.4.2.1, the thermal hydraulic model described for the SGTR analysis (the operational response analysis) includes simulator-based operator action times, addresses single failure considerations, and includes margin for steam generator overfill. The operational response analysis confirms that the assumptions in the licensing basis SGTR analysis remain conservative with respect to providing reactor coolant mass transfer data that is conservative for use in the environmental consequence analysis.
A SGTR accident with reactor coolant break flow from the primary side to the secondary side is mitigated by limiting the release of radioactive effluents from the ruptured SG, terminating primary-to-secondary break flow to prevent SG overfill, and restoring reactor coolant inventory to ensure adequate core cooling and plant pressure control. The time to terminate break flow is dependent upon control room operator action times and plant design. If the reactor coolant break flow cannot be terminated in a timely manner, reactor coolant may fill the ruptured SG main steam line and be released from a safety valve. Once reactor coolant passes through a safety valve, that valve is conservatively assumed to fail open, resulting in an uncontrolled depressurization of the ruptured SG with continued break flow and atmospheric releases until cold shutdown conditions are achieved. The SGTR margin to overfill accident analysis confirms reactor coolant will not pass through the safety valves.
The SGTR margin to overfill analysis includes the following conservative single failure considerations:
Failure of one intact SG ADV (including the RHRV ADV line) to open when cooldown is initiated from the main control room. This reduces the steam release rate, increasing the time required for cooldown, and results in increased reactor coolant break flow.
Failure of the instrument air supply system to the intact SG ADVs requiring local operation of the valves for cooldown. The increased time for local manual operation of the valves required for isolation and cooldown is included in the analysis and results in increased reactor coolant break flow from the primary side to the secondary side.
Failure of the auxiliary feedwater isolation valve to close on demand. This failure requires additional time for operators to terminate auxiliary feedwater flow to the ruptured SG.
The limiting single failure in the revised SGTR margin to overfill analysis addressing the NSAL-07-11 non-conservatism is the failure of the instrument air system. Additional heat removal capacity of the main steam system was required to mitigate this potential single failure, and it was necessary to credit the BVPS-1 RHRV ADV line.
Evaluation of the Proposed Change Beaver Valley Power Station, Unit Nos. 1 and 2 Page 6 of 10 The BVPS-1 RHRV ADV line is qualified to mitigate the SGTR accident. As described in Section 10.3.1.1, Design Basis, of the BVPS-1 UFSAR, the main steam system, including piping from the main steam lines to the decay heat release control valve, has been designed, fabricated, welded, inspected, and accepted in accordance with the American National Standards Institute (ANSI) B31.1-1967, Code for Pressure Piping, including addenda through June 30, 1971. The main steam system is designed for 1,100 psig and 560 degrees Fahrenheit. Steam piping from the main steam lines to the decay heat release control valve is designed as Seismic Category I (UFSAR Appendix B). The piping from the main steam headers up to the RHRV is Piping Class II (Q2).
The piping is nominally three inches in diameter from the main steam headers to nominal three-inch diameter Class 600 check valves. The three new normally-open, manually-closed isolation valves are nominally three-inch diameter, Class 600 gate valves. The common header to the RHRV is nominally four inches in diameter. The normally-open isolation valve is a nominal four-inch diameter, Class 600 valve, and the normally-closed RHRV is a nominal six-inch diameter, Class 600 globe valve. The piping from the RHRV to the environment is nominally four inches in diameter.
The licensing basis dose analysis is not affected and remains bounding. The limiting single failure considered in the current dose analysis is a failed-open ADV on the ruptured SG. The failed-open ADV results in ruptured SG releases directly to the environment, and increased flashed break flow, which are the dominant dose contributors. The RHRV ADV line would be used to enhance cooldown in a scenario assuming the limiting single failure is the instrument air system. For a limiting single failure of the instrument air system that would credit the RHRV ADV line, additional intact SG releases through the RHRV ADV line are judged to have negligible dose impact compared to the dose from the release through the failed-open ADV associated with the ruptured SG. Thus, the SGTR accident dose analysis is not affected by use of the RHRV ADV line.
The Applicable Safety Analyses section of the TS Bases indicates that the BVPS-1 RHRV is not used to mitigate a potential SGTR accident because it cannot be isolated from the ruptured SG. With the addition of the three new normally-open, manually-closed RHRV ADV line isolation valves 1MS-523, -524, and -525 to each SG, the RHRV can now be isolated from a ruptured SG. With the completed modifications and changes to the operating procedures, the RHRV is now used to mitigate a SGTR accident.
The BVPS-1 valves associated with the RHRV ADV line would be subject to SRs 3.7.4.1, 3.7.4.2, and 3.7.4.3 with surveillance frequencies specified in accordance with the Surveillance Frequency Control Program. These valves and current test frequencies are as follows:
Normally-closed, power-operated RHRV HCV-1MS-104 is tested per SR 3.7.4.1 at cold shutdown, but at least once every refueling outage in accordance with a valve cold shutdown justification allowed by ASME OM Code, Paragraph ISTC-3521(c).
Evaluation of the Proposed Change Beaver Valley Power Station, Unit Nos. 1 and 2 Page 7 of 10 Normally-open, manually-closed block valve 1MS-26 is tested per SR 3.7.4.2 once every two years in accordance with ASME OM Code, Paragraph ISTC-3540.
Recently-added, normally-open, manually-closed SG isolation valves 1MS-523,
-524, and -525 are tested per SR 3.7.4.3 once every two years in accordance with ASME OM Code, Paragraph ISTC-3540.
4.0 REGULATORY EVALUATION
4.1 Applicable Regulatory Requirements/Criteria 10 CFR 50, Appendix A, General Design Criteria for Nuclear Power Plants General Design Criteria (GDC) 2, 4, 34, and 57 of 10 CFR Part 50, Appendix A, define requirements that would continue to be met following implementation of the proposed technical specification change to require operability of a fourth BVPS-1 ADV line.
The BVPS-1 construction permit was issued in June of 1970, before the GDC were published as Appendix A to 10 CFR 50 in February of 1971 and amended in July of 1971. Appendix 1A of the BVPS-1 Updated Final Safety Analysis Report (UFSAR) provides a discussion of the degree of conformance with the 1971 GDC. In Appendix 1A of the BVPS-1 UFSAR, it is noted that the BVPS-1 design conforms with the intent of GDCs 2, 4, 34, and 57.
GDC 2, Design bases for protection against natural phenomena, requires that the safety-related portion of the main steam system be capable of withstanding the effects of natural phenomena such as earthquakes, tornadoes, hurricanes, and floods.
GDC 4, Environmental and dynamic effects design bases, requires that the safety-related portion of the main steam system be capable of withstanding the effects of missiles, pipe whip, and discharging fluids associated with equipment failures from events outside of the nuclear power unit.
GDC 34, Residual heat removal, requires that suitable redundancy be provided to assure that for onsite electrical power system operation (assuming offsite power is not available), and for offsite electrical power system operation (assuming onsite power is not available), main steam system safety function can be accomplished, assuming a single failure.
GDC 57, Closed system isolation valves, requires that main steam system containment isolation valves be located outside of containment and as close to containment as practical, and be either locked closed, automatic, or capable of remote manual operation. Simple check valves may not be used as the automatic isolation valve.
Evaluation of the Proposed Change Beaver Valley Power Station, Unit Nos. 1 and 2 Page 8 of 10 4.2 Precedent The NRC staff issued Amendment No. 251 to Facility Operating License No. DPR-64 for the Indian Point Nuclear Generating Unit No. 3 on April 15, 2013 (Accession No. ML13088A2014). Amendment No. 251 changed the non-conservative LCO 3.7.4 to require four operable ADVs (one for each of their four steam generators) instead of three to mitigate a SGTR in the supplemental analysis to the licensing basis. BVPS-1 contains three steam generators with one ADV for each steam generator, in addition to a common residual heat release valve atmospheric dump line with isolation valves to all three steam generators. Energy Harbor Nuclear Corp. is requesting a change to TS 3.7.4 to require four operable ADV lines for BVPS-1 instead of the three that are currently required to mitigate a SGTR in the supplemental analysis to the licensing basis.
4.3 No Significant Hazards Consideration Analysis Pursuant to 10 CFR 50.36(b), Energy Harbor Nuclear Corp. is submitting a request for amendment to the Renewed Operating Licenses DPR-66 and NPF-73 for the Beaver Valley Power Station, Unit Nos. 1 (BVPS-1) and 2 (BVPS-2), respectively. The amendment would revise Technical Specification (TS) 3.7.4, Atmospheric Dump Valves (ADVs) to require four OPERABLE ADV lines for BVPS-1 instead of the three that are currently required. As TS 3.7.4 is common to both BVPS-1 and BVPS-2, the changes to BVPS-1 TSs that affect BVPS-2 are administrative in nature.
The current BVPS-1 limiting condition for operation for TS 3.7.4 is non-conservative.
Plant modifications and emergency operating procedure updates allow system operation in accordance with the BVPS-1 steam generator tube rupture analysis that credits the fourth ADV line for mitigation of a potential SGTR. Therefore, the BVPS-1 fourth ADV line satisfies Criterion 3 of 10 CFR 50.36(c)(2)(ii), and the proposed amendment is required to provide a TS limiting condition for operation that ensures compliance with the BVPS-1 design and licensing bases.
Energy Harbor Nuclear Corp. has evaluated whether or not a significant hazards consideration is involved with the proposed amendment 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 amendment increases the number of BVPS-1 ADV lines required to be OPERABLE from three to four. ADV lines are used to cooldown the unit to residual heat removal system entry conditions when the condenser is unavailable, by passing steam from the secondary side of the unit to the environment.
Evaluation of the Proposed Change Beaver Valley Power Station, Unit Nos. 1 and 2 Page 9 of 10 Increasing the number of required ADV lines to mitigate a potential SGTR accident does not affect the probability of the accident initiator - a ruptured steam generator tube.
The limiting dose accident potentially involving the ADV lines is the SGTR, where primary reactor coolant would transfer through a ruptured steam generator tube, into the secondary side of the unit, and then potentially be released to the environment through the ADV line. However, the existing accident analysis already assumes failure of an ADV line valve to close for this scenario, and allows an unmitigated release of radioactive steam from the ruptured steam generator to the environment. Additional steam releases through the fourth ADV line could result in increased environmental releases through the intact steam generators, however, this increase is judged to be insignificant compared to the direct release through the failed-open ADV line.
Therefore, the proposed amendment 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 amendment to increase the number of BVPS-1 ADV lines required to be OPERABLE from three to four does not change any failure mechanism, malfunction, or accident initiator from those already postulated that involve the existing ADV lines.
Therefore, the proposed amendment 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 amendment to increase the number of BVPS-1 ADV lines required to be OPERABLE from three to four increases the margin of safety presently required in the technical specifications. The margin of safety is related to the ability of the ADV lines to release steam and cool down the unit, and also be capable of isolation to limit potential radioactive releases from a SGTR.
Requiring an additional ADV line ensures adequate cooldown capability assumed within the analyses. Additional steam releases through the fourth ADV line could result in increased environmental releases through the intact steam generators, however, this increase is judged to be insignificant compared to the direct
Evaluation of the Proposed Change Beaver Valley Power Station, Unit Nos. 1 and 2 Page 10 of 10 release through the failed-open ADV line from a ruptured steam generator assumed in the analyses.
Therefore, the proposed amendment does not involve a significant reduction in a margin of safety.
Based on the above, Energy Harbor Nuclear Corp. 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 Conclusions In conclusion, based on the considerations discussed above, (1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, (2) such activities will be conducted in compliance with the 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.
Attachment 1 Technical Specification Page Markups (2 pages follow)
ADVs 3.7.4 3.7 PLANT SYSTEMS 3.7.4 Atmospheric Dump Valves (ADVs)
LCO 3.7.4 For Unit 1, three ADV lines shall be OPERABLE, For Unit 2, fFour ADV lines shall be OPERABLE.
APPLICABILITY: MODES 1, 2, and 3, MODE 4 when steam generator is relied upon for heat removal.
ACTIONS CONDITION REQUIRED ACTION COMPLETION TIME A. One required ADV line A.1 Restore required ADV line 7 days inoperable. to OPERABLE status.
B. Two or more required ADV B.1 Restore all but one ADV 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> lines inoperable. line to OPERABLE status.
C. Required Action and C.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 /> associated Completion Time not met. AND C.2 Be in MODE 4 without 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> reliance upon steam generator for heat removal.
SURVEILLANCE REQUIREMENTS SURVEILLANCE FREQUENCY SR 3.7.4.1 Verify one complete cycle of each ADV. In accordance with the Surveillance Frequency Control Program SR 3.7.4.2 Verify one complete cycle of each ADV block valve. In accordance with the Surveillance Frequency Control Program Beaver Valley Units 1 and 2 3.7.4 - 1 Amendments 292 / 179
ADVs 3.7.4 SURVEILLANCE REQUIREMENTS (continued)
SURVEILLANCE FREQUENCY SR 3.7.4.3 --------------------------------------------------------------------------
- NOTE -
Only applicable to Unit 2.
Verify one complete cycle of each individual steam In accordance generator isolation valve associated with the Unit 2 with the Residual Heat Release Valve ADV line. Surveillance Frequency Control Program Beaver Valley Units 1 and 2 3.7.4 - 2 Amendments 292 / 179
Attachment 2 Technical Specification Bases Page Markups (for information only)
(6 pages follow)
FOR INFORMATION ONLY ADVs B 3.7.4 B 3.7 PLANT SYSTEMS B 3.7.4 Atmospheric Dump Valves (ADVs)
BASES BACKGROUND The ADV lines required OPERABLE include the three atmospheric relief valves (one per steam generator (SG)) and the associated block (isolation) valves and for Unit 2 only, one residual heat release valve and its block valve and individual SG isolation valves. The Unit 2 residual heat release valve and all its associated isolation valves are counted as one of the required ADV lines for Unit 2. As discussed in the UFSAR, Section 10.3 (Ref. 1), the atmospheric relief valves and the residual heat release valve provide a method of removing core decay heat and cooling the unit to Residual Heat Removal (RHR) System entry conditions should the preferred heat sink via the condenser steam dump valves not be available.
Each ADV line has a block valve. The block valves are normally open manual valves. The block valves can be used for isolating an ADV line if necessary. However, due to time constraints in the safety analysisanalyses, the ADV block valves must remain open for an ADV line to be considered OPERABLE. In addition to the block valve described above, the Unit 2 residual heat release valve has three normally open isolation valves (one for each SG). The individual SG isolation valves are used to isolate a faulted SG so the Unit 2 residual heat release valve can be used for accident mitigation. In order for the Unit 2 residual heat release valve ADV line to be OPERABLE, the individual SG isolation valves must be maintained open with the capability of being manually closed.
The Unit 1 ADVs are DC powered air operated valves utilizing a non-safety related air system. The Unit 1 ADVs can normally be operated from the control room. However, in order to meet the assumptions of the operational response assessmentanalysis used to evaluate single failure concerns, the Unit 1 ADVs (including the residual heat release valve) must be capable of being operated locally as well as from the control room in order to be considered OPERABLE.
The Unit 2 ADVs have an electro-hydraulic operator that can be operated from the control room. Each Unit 2 atmospheric relief valve is powered by the same emergency AC train power. The Unit 2 residual heat release valve is powered by the other emergency AC train. In order to meet the assumptions of the applicable safety analysis, the Unit 2 ADVs (including the residual heat release valve) must be capable of being operated locally as well as from the control room in order to be considered OPERABLE.
Beaver Valley Units 1 and 2 B 3.7.4 - 1 Revision 0- I
FOR INFORMATION ONLY ADVs B 3.7.4 BASES BACKGROUND (continued)
The ADVs have a non-safety related automatic pressure control capability. However, the only function of the ADVs required by the safety analyses (and this Technical Specification) is the ability to cool down the plant following a Design Basis Accident (DBA).
APPLICABLE In the accident analysis analyses presented in the UFSAR SAFETY (Ref. 2), the ADVs may be used by the operator to cool down the unit to ANALYSES RHR entry conditions for accidents accompanied by a loss of offsite power.
The design bases of the ADVs are established by the capability to cool the unit to RHR System entry conditions. For the recovery from a design basis steam generator tube rupture (SGTR) accident, the operator is required to perform a limited cooldown to establish adequate subcooling as a necessary step to terminate the primary to secondary break flow into the faulted steam generator. The time required to terminate the primary to secondary break flow for the design basis SGTR accident is more critical than the time required to cool down to RHR System entry conditions for this event and for other Design Basis Accidents (DBAs).
Thus, the SGTR is the limiting event for the ADVs.
For Unit 1, three four ADVs with associated flow paths and isolation valves are required OPERABLE. Due to the design of the Unit 1 residual heat release valve, it can not be isolated from a SG with a ruptured tube.
Therefore, the Unit 1 residual heat release valve is not used to mitigate a SGTR due to the dose requirements of the accident analysis. The requirement for three four OPERABLE ADV lines provides assurance that a single active failure of one ADV line or a single active failure of the instrument air supply will not prevent the mitigation of a SGTR accident.
The Unit 1 operational response analysis assessment used to evaluate the single failures described above also assumes that one ADV is lost to the faulted SG. In the case where the instrument air supply is available and an active failure of one of the remaining ADVs is assumed, the operational response analysis assessment assumes the remaining ADVs is are operated from the control room to successfully mitigate the SGTR accident. In the case where the active failure is a loss of instrument air, and ADV operation is delayed, the operational assessmentanalysis assumes the two three remaining ADVs are operated by local manual control to successfully mitigate the SGTR accident. Therefore, the Unit 1 ADVs must be capable of both remote and local manual operation to be considered OPERABLE. The Unit 1 operational assessmentanalysis does not include a specific time to manually unblock an ADV. Therefore, the Unit 1 ADV block valves must remain open for the ADV lines to be considered OPERABLE. The Unit 1 analysis does account for the time it takes to manually isolate the faulted SG from the Unit 1 residual heat release valve so that the ADV line can be used to meet the Beaver Valley Units 1 and 2 B 3.7.4 - 2 Revision 0
FOR INFORMATION ONLY ADVs B 3.7.4 BASES APPLICABLE SAFETY ANALYSES (continued) analysis requirements. Therefore, the individual normally open SG isolation valves associated with the Unit 1 residual heat release valve must also be maintained open with the capability of being manually closed for the Unit 1 residual heat release valve ADV line to be OPERABLE.
For Unit 2, four ADVs with associated flow paths and isolation valves are required OPERABLE to satisfy the SGTR accident analysis assumptions of a single active failure and loss of offsite power. Requiring four Unit 2 ADVs OPERABLE assures that two ADVs will remain OPERABLE for the SGTR analysis overfill case (i.e., one ADV lost to the faulted SG and one ADV lost to a single active failure). Additionally, requiring four Unit 2 ADVs OPERABLE assures that three ADVs will remain OPERABLE for the SGTR radiological dose case. The radiological dose case includes the loss of one ADV as a single active failure (i.e., the ADV on the faulted SG fails open).
The Unit 2 SGTR analysis requires that two ADVs (overfill case) or three ADVs (bounding dose case) remain OPERABLE to mitigate the accident within the assumed time frame. All other radiological dose cases only require two ADVs, since a longer cooldown does not have as great an impact on SGTR doses as a failed open ADV on the faulted SG.
Furthermore, in order to assure the SGTR accident can be mitigated within the Unit 2 analysis requirements, the ADVs must be capable of both remote and local manual operation. In addition, the Unit 2 safety analysis does not include additional time to manually unisolate a blocked ADV. Therefore, an ADV line with a closed block valve is considered inoperable. The Unit 2 safety analysis does account for the time it takes to manually isolate the faulted SG from the Unit 2 residual heat release valve so that the ADV line can be used to meet the accident analysis requirements. Therefore, the individual normally open SG isolation valves associated with the Unit 2 residual heat release valve must also be maintained open with the capability of being manually closed for the Unit 2 residual heat release valve ADV line to be OPERABLE.
The ADVs are equipped with block valves in the event an ADV spuriously fails to open or fails to close during use. The ADVs, as well as the RHRV, at each unit may pass some amount of steam leakage, since the SGTR radiological analyses for BVPS-1 and BVPS-2 include a steam flow margin factor. Such leakage may pass through the Main Steam Safety Valves, as well. TS 3.7.1 OPERABILITY of the MSSVs is not affected, since these valves are not discussed or credited in SGTR accident mitigation. Any observed steam leakage would have to be measurable on the installed Main Steam Flow System instruments (above instrument accuracy) to be considered significant.
The ADVs satisfy Criterion 3 of 10 CFR 50.36(c)(2)(ii).
Beaver Valley Units 1 and 2 B 3.7.4 - 3 Revision 9
FOR INFORMATION ONLY ADVs B 3.7.4 BASES LCO The LCO requires three Unit 1 ADV lines and four Unit 2 ADV lines to be OPERABLE. The ADV lines required OPERABLE include the three atmospheric relief valves (one per SG) and the associated block (isolation) valves and for Unit 2 only, one residual heat release valve and its block valve and individual SG isolation valves. The Unit 2 residual heat release valve and all its associated isolation valves are counted as one ADV line for Unit 2. The number of ADV lines required OPERABLE is consistent with each Units design and the safety analyses requirements described above.
An OPERABLE ADV line is capable of providing controlled relief of the main steam flow and capable of fully opening and closing. In order to be OPERABLE, the ADVs (including the Unit 2 residual heat release valve) must be capable of remote manual and local manual operation. Also, the block valve associated with each ADV line must be open for the line to be considered OPERABLE. In addition to the above requirements, the three individual SG isolation valves associated with the Unit 2 residual heat release valve must be open and capable of being manually closed for the residual heat release valve ADV line to be considered OPERABLE.
The block valves associated with each ADV line must be OPERABLE to isolate a failed open ADV line. In addition, the three individual SG isolation valves associated with the Unit 2 residual heat release valve ADV line must be OPERABLE to enable a faulted SG to be isolated from the residual heat release valve ADV line.
Failure to meet the LCO could result in the inability to cool the unit under the limiting accident conditions within the time limit assumed in the applicable safety analyses described above.
APPLICABILITY In MODES 1, 2, and 3, and in MODE 4, when steam generator is being relied upon for heat removal, the ADVs are required to be OPERABLE.
In MODE 5 or 6, an SGTR is not a credible event.
ACTIONS A.1 With one required ADV line inoperable, action must be taken to restore OPERABLE status within 7 days. The 7 day Completion Time allows for the redundant capability afforded by the remaining OPERABLE ADV lines, a nonsafety grade backup in the condenser steam dump valves, and MSSVs.
Beaver Valley Units 1 and 2 B 3.7.4 - 4 Revision 9
FOR INFORMATION ONLY ADVs B 3.7.4 BASES ACTIONS (continued)
B.1 With two or more ADV lines inoperable, action must be taken to restore all but one ADV line to OPERABLE status. Since the block valves or isolation valves can be closed to isolate an ADV, some repairs may be possible with the unit at power. The 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> Completion Time is reasonable to repair inoperable ADV lines, based on the availability of the condenser steam dump valves and MSSVs, and the low probability of an event occurring during this period that would require the ADV lines.
C.1 and C.2 If the ADV lines cannot be restored to OPERABLE status within the associated Completion Time, the unit must be placed in a MODE in which the LCO does not apply. To achieve this status, the unit must be placed in at least MODE 3 within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />, and in MODE 4, without reliance upon steam generator for heat removal, within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. In this condition, the unit utilizes RHR for cooling. Therefore, operation may continue with one or more ADV lines inoperable because the RCS cooling function required to mitigate a SGTR event would be accomplished by the RHR System.
The allowed Completion Times are reasonable, based on operating experience, to reach the required unit conditions from full power conditions in an orderly manner and without challenging unit systems.
SURVEILLANCE SR 3.7.4.1 REQUIREMENTS To perform a controlled cooldown of the RCS, the ADVs must be able to be opened and throttled through their full range. This SR ensures that the ADVs are tested through a full control cycle at least once per fuel cycle.
The requirement to stroke the valve through the full range of operation may be accomplished by remote manual control. In addition, this Surveillance must also verify the capability to locally operate each ADV.
The verification of local operation does not require that the ADV be stroked through the full range of travel (i.e., if the valve is stroked full open and closed by remote manual operation, the capability to operate the ADV locally may be verified by observing valve stem movement). The ADVs must be capable of both remote and local manual operation in order to be considered OPERABLE. Performance of inservice testing or use of an ADV during a unit cooldown may satisfy this requirement. The Surveillance Frequency is controlled under the Surveillance Frequency Control Program.
Beaver Valley Units 1 and 2 B 3.7.4 - 5 Revision -29 I
FOR INFORMATION ONLY ADVs B 3.7.4 BASES SURVEILLANCE REQUIREMENTS (continued)
SR 3.7.4.2 The function of the block valve is to isolate a failed open ADV. Cycling the block valve closed and open demonstrates its capability to perform this function. Performance of maintenance or other testing that results in cycling these valves including the use of the block valve during unit cooldown may satisfy this requirement. The Surveillance Frequency is controlled under the Surveillance Frequency Control Program.
SR 3.7.4.3 The function of the individual SG isolation valves associated with the Unit 2 residual heat release valve is to isolate the residual heat release valve from a SG with a ruptured tube. Isolating the SG with a ruptured tube minimizes the resulting dose when the residual heat release valve is used for SGTR accident mitigation. Cycling these isolation valves closed and open demonstrates the capability to perform this function.
Performance of maintenance or other testing that results in cycling these valves, including the use of the isolation valve during unit cooldown may satisfy this requirement. The Surveillance Frequency is controlled under the Surveillance Frequency Control Program.
The Surveillance is modified by a Note that states the Surveillance is only applicable to Unit 2. The Note is necessary because the corresponding Unit 1 residual heat release valve is not required OPERABLE by LCO 3.7.4. Only the Unit 2 residual heat release valve is required OPERABLE by LCO 3.7.4. This is because Unit 2 requires the additional relief capacity provided by this valve for accident mitigation and the Unit 2 residual heat release valve has individual SG isolation valves that allow it to be isolated from a faulted SG so it can be used for accident mitigation.
REFERENCES 1. UFSAR, Section 10.3.
Beaver Valley Units 1 and 2 B 3.7.4 - 6 Revision 29