ND-18-1277, Revision to Request for License Amendment and Exemption: Power Operated Relief Valve (PORV) Noise Mitigation (LAR-18-021R1)

Revision to Request for License Amendment and Exemption: Power Operated Relief Valve (PORV) Noise Mitigation (LAR-18-021R1)

ML18284A447
Person / Time
Site:	Vogtle
Issue date:	10/11/2018
From:	Whitley B Southern Nuclear Operating Co
To:	Document Control Desk, Office of New Reactors
References
LAR-18-021R1, ND-18-1277
Download: ML18284A447 (28)

Text

B. H. Whitley Southern Nuclear Director Operating Company, Inc.

Regulatory Affairs 3535 Colonnade Parkway Birmingham, AL 35243 Tel 205.992.7079 October 11, 2018 Docket Nos.: 52-025 ND-18-1277 52-026 10 CFR 50.90 10 CFR 52.63 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Southern Nuclear Operating Company Vogtle Electric Generating Plant Units 3 and 4 Revision to Request for License Amendment and Exemption:

Power Operated Relief Valve (PORV) Noise Mitigation (LAR-18-021R1)

Ladies and Gentlemen:

In accordance with 10 CFR 50.90, Southern Nuclear Operating Company (SNC) submitted license amendment request (LAR)-18-021 for the combined licenses (COLs) for Vogtle Electric Generating Plant (VEGP) Units 3 and 4 (License Numbers NPF-91 and NPF-92, respectively) by SNC letter ND-18-1037, dated August 10, 2018 [ADAMS Accession Number ML18222A599]

to depart from Tier 2 information in Updated Final Safety Analysis Report (UFSAR)

Figure 10.3.2-1 (Sheets 1 and 2) and Tables 3.9-16, 6.2.3-1, and 10.3.3-1 by relocating the power operated relief valve (PORV) branch lines upstream of the branch lines to the main steam safety valves and changing the PORV block valves from gate valves to globe valves. The requested amendment also involves related changes to plant-specific Tier 1 Figure 2.2.4-1 (Sheets 1 and 2), with corresponding changes to the associated COL Appendix C information.

In the August 30, 2018 public call (meeting minutes available under ADAMS Accession No. ML18243A492), NRC Staff discussed additional information needed to complete their technical review of SNC LAR-18-021. SNC agreed to submit additional information to the NRC Staff for the technical review of LAR-18-021. This submittal provides that additional information.

Enclosures 1 through 4 were provided with the original LAR-18-021, SNC letter ND-18-1037. To provide additional information for the NRC Staff to complete their technical review, Enclosures 5 and 6 replace Enclosures 1 and 2, respectively. Revision bars in the right-hand margin indicate the differences between Enclosures 1 and 5 and Enclosures 2 and 6. This LAR revision affects the significant hazards consideration as indicated by the revision bars. This submittal does not affect Enclosures 3 and 4 provided in ND-18-1037.

This letter contains no regulatory commitments. This letter has been reviewed and determined not to contain security-related information.

U.S. Nuclear Regulatory Commission ND-18-1277 Page 2 of 4 SNC maintains the requested NRC staff approval of the license amendment by February 5, 2019, to support completion of Inspections, Tests, Analyses , and Acceptance Criteria (ITAAC}

activities associated with main steam piping in the auxiliary building. SNC expects to implement this proposed amendment within 30 days of approval of the requested changes.

SNC expects to submit a preliminary amendment request (PAR} by October 18, 2018 to support installation of main steam piping in the auxiliary building.

In accordance with 10 CFR 50.91, SNC is notifying the State of Georgia of this LAR by transmitting a copy of this letter and its enclosures to the designated State Official.

Should you have any questions. please contact Mr. Adam Quarles at (205} 992-7031 .

I declare under penalty of perjury that the foregoing is true and correct. Executed on the 11th of October 2018.

Respectfully submitted, Brian H. Whitley Director, Regulatory Affairs Southern Nuclear Operating Company

Enclosures:

1} through 4} Previously submitted with the original LAR, LAR-18-021

5) Vogtle Electric Generating Plant (VEGP) Units 3 and 4 - Revision to Request for License Amendment: Power Operated Relief Valve (PORV) Noise Mitigation (LAR-18-021 R1)

6) Vogtle Electric Generating Plant (VEGP) Units 3 and 4 - Revision to Exemption Request: Power Operated Relief Valve (PORV)

Noise Mitigation (LAR-18-021 R 1)

U.S. Nuclear Regulatory Commission ND-18-1277 Page 3 of 4 cc:

Southern Nuclear Operating Company / Georgia Power Company Mr. S. E. Kuczynski (w/o enclosures)

Mr. D. G. Bost (w/o enclosures)

Mr. M. D. Meier (w/o enclosures)

Mr. D. H. Jones (w/o enclosures)

Mr. J. B. Klecha Mr. G. Chick Mr. D. L. McKinney (w/o enclosures)

Mr. T. W. Yelverton (w/o enclosures)

Mr. B. H. Whitley Ms. C. A. Gayheart Mr. C. R. Pierce Ms. A. G. Aughtman Mr. D. L. Fulton Mr. M. J. Yox Mr. C. T. Defnall Mr. J. Tupik Mr. W. A. Sparkman Ms. A. C. Chamberlain Ms. A. L. Pugh Ms. P. Reister Ms. K. Roberts Ms. P. Ridgway Document Services RTYPE: VND.LI.L00 File AR.01.02.06 Nuclear Regulatory Commission Mr. W. Jones (w/o enclosures)

Ms. J. Dixon-Herrity Mr. C. Patel Ms. J. M. Heisserer Mr. B. Kemker Mr. G. Khouri Ms. S. Temple Mr. F. Brown Mr. C. J. Even Mr. A. Lerch Mr. S. Walker State of Georgia Mr. R. Dunn Oglethorpe Power Corporation Mr. M. W. Price Ms. A. Whaley

U.S. Nuclear Regulatory Commission ND-18-1277 Page 4 of 4 Municipal Electric Authority of Georgia Mr. J. E. Fuller Mr. S. M. Jackson Dalton Utilities Mr. T. Bundros Westinghouse Electric Company, LLC Mr. L. Oriani (w/o enclosures)

Mr. C. Churchman (w/o enclosures)

Mr. M. Corletti Mr. M. L. Clyde Ms. L. Iller Mr. D. Hawkins Mr. J. Coward Other Mr. S. W. Kline, Bechtel Power Corporation Ms. L. A. Matis, Tetra Tech NUS, Inc.

Dr. W. R. Jacobs, Jr., Ph.D., GDS Associates, Inc.

Mr. S. Roetger, Georgia Public Service Commission Ms. S. W. Kernizan, Georgia Public Service Commission Mr. K. C. Greene, Troutman Sanders Mr. S. Blanton, Balch Bingham NDDocumentinBox@duke-energy.com, Duke Energy Mr. S. Franzone, Florida Power & Light

Southern Nuclear Operating Company ND-18-1277 Enclosure 5 Vogtle Electric Generating Plant (VEGP) Units 3 and 4 Revision to Request for License Amendment:

Power Operated Relief Valve (PORV) Noise Mitigation (LAR-18-021R1)

(This Enclosure consists of 15 pages, including this cover page.)

ND-18-1277 Revision to Request for License Amendment: Power Operated Relief Valve (PORV) Noise Mitigation (LAR-18-021R1)

Table of Contents

1.

SUMMARY

DESCRIPTION

2. DETAILED DESCRIPTION AND TECHNICAL EVALUATION

3. TECHNICAL EVALUATION (Included in Section 2)

4. REGULATORY EVALUATION 4.1. Applicable Regulatory Requirements/Criteria 4.2. Precedent 4.3. Significant Hazards Consideration 4.4. Conclusions

5. ENVIRONMENTAL CONSIDERATIONS

6. REFERENCES Page 2 of 15

ND-18-1277 Revision to Request for License Amendment: Power Operated Relief Valve (PORV) Noise Mitigation (LAR-18-021R1)

Pursuant to 10 CFR 52.98(c) and in accordance with 10 CFR 50.90, Southern Nuclear Operating Company (SNC) hereby requests an amendment to Combined License (COL) Nos.

NPF-91 and NPF-92 for Vogtle Electric Generating Plant (VEGP) Units 3 and 4, respectively.

1.

SUMMARY

DESCRIPTION The proposed change would revise the COLs by relocating the power operated relief valve (PORV) branch lines upstream of the main steam safety valves in Inspections, Tests, Analyses, and Acceptance Criteria (ITAAC) Figure 2.2.4-1 (Sheets 1 and 2) of COL Appendix C. Additionally, the change involves changing the PORV block valves from gate valves to globe valves in the Updated Final Safety Analysis Report (UFSAR).

The requested amendment proposes changes to plant-specific Design Control Document (DCD) Tier 2 information in the UFSAR that involve changes to COL Appendix C, and corresponding changes to plant-specific Tier 1 information. This enclosure requests approval of the license amendment necessary to implement the COL Appendix C and UFSAR changes. Enclosure 2 requests the exemption necessary to implement the involved changes to the plant-specific Tier 1 information.

2. DETAILED DESCRIPTION AND TECHNICAL EVALUATION COL Appendix C Subsection 2.2.4 contains ITAAC for the steam generator system (SGS).

COL Appendix C Figure 2.2.4-1 (sheets 1 and 2) shows the SGS piping from the steam generators through the auxiliary building. This figure depicts the power operated relief valve (PORV) as located downstream of the main steam safety valves (MSSVs).

Design Function Related to Activity Power-Operated Relief Valves (PORV) (SGS-PL-V233A/B)

The PORVs perform the safety-related functions of steam generator isolation and steam generator relief isolation. During plant operations, the PORVs are automatically controlled by steam line pressure. The valves modulate open and exhaust to the atmosphere whenever the steam line pressure exceeds an operator established set point. When needed for plant cooldown, the PORVs are automatically controlled by steam line pressure with remote manual adjustment of the pressure set point from the control room or remote shutdown workstation. In order to cooldown the plant, the operator manually adjusts the pressure set point downward in discrete steps or takes manual control of the valve position.

Each PORV is installed in a branch line off the safety-related portion of the main steam line upstream of the main steam isolation valve (MSIV).

PORV Block Valves (SGS-PL-V027A/B)

The PORV block valves perform the safety-related functions of containment isolation, steam generator isolation, and steam generator relief isolation. The PORV block valves also provide the capability to isolate a leaking or stuck-open PORV. The PORV block valves are AP1000 Safety Class B and close automatically on a Low-2 steam line pressure signal generated in the Protection and Safety Monitoring System (PMS).

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ND-18-1277 Revision to Request for License Amendment: Power Operated Relief Valve (PORV) Noise Mitigation (LAR-18-021R1)

Each PORV block valve is located in the branch line upstream of the PORV. The upstream location allows maintenance of the PORV at power.

Containment Isolation The containment isolation system meets the design requirements set forth in General Design Criteria (GDC) 55, 56 and 57 of Appendix A to Title 10 of the Code of Federal Regulations (CFR) Part 50. A regulatory requirement common to all containment isolation valves governed by GDCs 55, 56, and 57 is isolation valves outside containment be located as close to the containment as practical. The intent of this design requirement is to minimize the probability that containment integrity could be compromised due to dynamic effects or natural events. UFSAR Table 6.2.3-1 lists the nominal length of pipe between each containment penetration and the containment isolation valve.

Reason for Activity During testing of the PORVs in operation at another facility, the noise level in the main control room (MCR) was approximately 85 dB(A) and the noise level at the PORVs was approximately 110 dB(A). The size and geometry of the PORV block valves cause a high flow velocity (~800 ft/sec) and Helmholtz resonance which results in an increase in noise level. Since the PORV block valves are located in rooms adjacent to the MCR, the sound from the PORV block valves is transmitted into the MCR. Changes to the PORV block valves are necessary in order to reduce the noise contribution to the MCR and improve human factors with the PORVs in operation.

Description of Activity To reduce noise contribution to the MCR from the PORV block valves, the PORV block valve size is proposed to be changed from 6-inch to 12-inch. The branch line that the PORV block valves are installed in is also proposed to be changed from 6 inches to 12 inches.

These changes reduce the flow velocity to less than 200 ft/sec and as a result the noise level is reduced. The Technical Specification (TS) Bases B 3.7.10 currently states that this branch line is 6 inches. TS 3.7.10 Actions and Surveillance Requirements are not associated with the size of the branch line. Since the specific size of the branch line is not important to TS 3.7.10, the bases is revised to remove the size of the branch line that the PORV is installed in.

Changes are proposed to the PORV block valves to change the valve type from a gate valve to a globe valve. The new valve incorporates a trim which forces the flow through a tortuous path to control the pressure and velocity, reducing the noise level when compared with a similar pressure drop for other valve designs. This valve design also mitigates the potential for a Helmholtz or standing wave source developing in the valve body or seat. The globe valve is qualified for the same environmental and pressure/temperature conditions. UFSAR Table 3.9-16, Table 10.3.3-1, and Figure 10.3.2-1 (Sheets 1 and 2) are proposed to be revised to change the PORV block valves from gate valves to globe valves.

Due to layout constraints with the proposed changes, the location of the branch line that the PORV block valves are installed in is moved upstream of the main steam safety valves (MSSVs) branch connections. UFSAR Table 6.2.3-1 is revised to change the pipe length Page 4 of 15

ND-18-1277 Revision to Request for License Amendment: Power Operated Relief Valve (PORV) Noise Mitigation (LAR-18-021R1) from each containment penetration to valves SGS-PL-V027A and SGS-PL-V027B to 26 feet. COL Appendix C (Plant-specific Tier 1) Figure 2.2.4-1 (Sheets 1 and 2) and UFSAR Figure 10.3.2-1 (Sheets 1 and 2) are revised to show the PORV branch line upstream of the MSSVs.

MCR noise levels will be verified as part of the AP1000 human factors engineering verification and validation program as described in UFSAR Subsection 18.11.

Proposed Licensing Basis Changes The proposed changes to COL Appendix C (and corresponding plant-specific Tier 1) and the UFSAR related to relocating the power operated relief valve (PORV) branch lines upstream of the main steam safety valves branch connections and changing the PORV block valves from gate valves to globe valves are as follows:

1. COL Appendix C (plant-specific Tier 1) Figure 2.2.4-1 (Sheets 1 and 2) are revised to move the PORV branch line upstream of the MSSVs.

2. UFSAR Table 3.9-16, Table 10.3.3-1, and Figure 10.3.2-1 (Sheets 1 and 2) are revised to change the Main Steam line PORV block valves (SGS-PL-V027A/B) from gate valves to globe valves.

3. UFSAR Table 6.2.3-1 is revised to change the pipe length from each containment penetration to valves SGS-PL-V027A and SGS-PL-V027B to 26 feet.

4. UFSAR Figure 10.3.2-1(Sheets 1 and 2) is revised to move the PORV branch line upstream of the MSSVs.

5. Technical Specifications Bases B 3.7.10 is revised to remove the size of the branch line that the PORV is installed in.

Technical Evaluation With the proposed changes, the PORV block valves are still able to perform the safety-related functions of containment isolation, steam generator isolation, and steam generator relief isolation. There is no change to the PORV block valves safety class or safety-related functions.

The relocation of the branch line that the PORV block valves are installed in allows the PORV block valves to be closer to the containment penetration and maintain compliance with GDC 57 for locating containment isolation valves as close to the containment as practical.

There is no impact to ITAAC 2.2.05.12 and ITAAC 2.7.01.14 because the tests measure background noise for the main control room emergency habitability system (VES) and nuclear island nonradioactive ventilation system (VBS), respectively. Noise from the PORVs is not considered to be background noise because PORV operation is not a frequent occurrence.

There is no impact to Chapter 15 evaluations. Changes to the PORV block valve and line size do not impact the mass releases to the atmosphere during a Steam Generator Tube Page 5 of 15

ND-18-1277 Revision to Request for License Amendment: Power Operated Relief Valve (PORV) Noise Mitigation (LAR-18-021R1)

Rupture accident. The mass release is limited by the PORV which is more restrictive than the PORV block valve and line size.

There is no impact to any assumed leakage through the PORV line. The existing 12-inch PORV has a design function to limit leakage through the PORV line. Increasing the PORV block valve to 12 inches will increase the leakage through the PORV block valve; however, it will be at the same leakage rate as the 12-inch PORV. Therefore, the leakage rate through the PORV line does not increase and there is no impact to radiation doses.

There is no impact to the assumptions or analysis in the completed safety analysis for radiation doses as a result of the change.

The piping analysis for the affected piping has been revised in accordance with the requirements of UFSAR Subsection 3.9.3.1.5. All stresses and interface loads remain acceptable and within the limits described in UFSAR Table 3.9-7. The piping support calculations have been revised using the load combinations shown in UFSAR Table 3.9-8, and the critical interaction ratio for each support is less than 1.0; therefore, a positive design margin exists. The proposed changes did not affect any of the piping packages listed in Table 3.9-20. There is no impact to the conclusions of the Pipe Rupture Hazard Analysis (PRHA) because the PORV line is Break Exclusion Zone (BEZ) piping. Revised calculations show that the proposed changes do not result in any new postulated break locations.

Updated analyses confirm that the integrity of the wall adjacent to the MCR is unaffected by a postulated main steam line break that causes the PORV line to impact the wall. The piping and components downstream of the PORV are nonsafety-related and are not affected by this activity.

The structural concrete floors and walls which make up the bounds of Rooms 12404 and 12406 were analyzed for the downstream impacts due to the proposed changes. The results conclude that the acceptance criteria of UFSAR Subsection 3.8.4.2, specifically ACI 349-01, are met. All applicable load combinations shown in UFSAR Table 3.8.4-2 were considered.

Critical sections defined in UFSAR Subsection 3.8.4.5.4 within the scope of analysis are L-line, elevation 117-6 to 135-3 and 11-line, elevation 117-6 to 135-3 between L-line and M-line. The analysis of L-line confirms that Tier 2* information depicted in UFSAR Table 3H.5-7 remains unchanged along with the typical reinforcement configuration presented in UFSAR Figure 3H.5-12. The review of 11-line confirms no impact to neither UFSAR Section 3H.5.1.4 nor Figure 3H.5-5. Therefore, all structural evaluations are within the bounds of the acceptance criteria and meet the licensing requirements imposed in UFSAR Chapter 3.

There is no change to the valve motor operator. The current motor operator is sufficient to operate the new 12-inch globe valve. Therefore, there is no impact to the class 1E dc and UPS system (IDS) battery sizing. There is no change to the valve stroke time; therefore, there is no impact to valve open/closure times.

The proposed changes do not result in a modification to, addition to, or removal of a structure, system, or component (SSC) such that a design function is adversely affected, have no impact on plant operating procedures or a method of control that adversely affects a design function, do not result in an adverse change to a method of evaluation or use of an Page 6 of 15

ND-18-1277 Revision to Request for License Amendment: Power Operated Relief Valve (PORV) Noise Mitigation (LAR-18-021R1) alternate method of evaluation, do not represent tests or experiments outside the reference bounds of the design basis, and do not alter the assumptions or results of the ex-vessel severe accident assessment.

The proposed changes do not revise any aspects of the plant that could have any adverse effect on safety and security, including the site emergency plan.

3. TECHNICAL EVALUATION The Technical Evaluation is included in Section 2.

4. REGULATORY EVALUATION 4.1 Applicable Regulatory Requirements/Criteria 10 CFR 52.98(c) requires NRC approval for any modification to, addition to, or deletion from the terms and conditions of a COL. These proposed changes involve a departure from COL Appendix C; therefore, this activity requires a proposed amendment to the COL.

10 CFR 52, Appendix D, VIII.A.4 states that exemptions from Tier 1 information are governed by the requirements in 10 CFR 52.63(b)(1) and 52.98(f). 10 CFR 52.63(b)(1) allows a licensee who references a design certification rule to request an exemption from Tier 1 information. 10 CFR 52.98(f) requires NRC approval for any modification to, addition to, or deletion from the terms and conditions of a COL. These proposed changes involve changes to figures in COL Appendix C, with corresponding changes to Tier 1 information in the associated plant-specific DCD. Therefore, NRC approval is required prior to making the proposed plant-specific changes in this license amendment request.

10 CFR 52, Appendix D, Section VIII.B.5.a allows a licensee who references Appendix D to depart from Tier 2 information, without prior NRC approval, unless the proposed departure involves a change to or departure from Tier 1 information, Tier 2*

information, or the Technical Specifications, or requires a license amendment under paragraphs B.5.b or B.5.c of Section VIII. As discussed above, the proposed changes to UFSAR Figure 10.3.2-1 (Sheets 1 and 2) and Table 6.2.3-1 involve changes to Tier 1 information. Therefore, an exemption request is submitted with this license amendment request.

10 CFR Part 50, Appendix A, General Design Criterion (GDC) 1, Quality standards and records, requires that structures, systems, and components important to safety shall be designed, fabricated, erected, and tested to quality standards commensurate with the importance of the safety functions to be performed. Where generally recognized codes and standards are used, they shall be identified and evaluated to determine their applicability, adequacy, and sufficiency and shall be supplemented or modified as necessary to assure a quality product in keeping with the required safety function. A quality assurance program shall be established and implemented in order to provide adequate assurance that these structures, systems, and components will satisfactorily perform their safety functions. Appropriate records of the design, Page 7 of 15

ND-18-1277 Revision to Request for License Amendment: Power Operated Relief Valve (PORV) Noise Mitigation (LAR-18-021R1) fabrication, erection, and testing of structures, systems, and components important to safety shall be maintained by or under the control of the nuclear power unit licensee throughout the life of the unit.

10 CFR Part 50, Appendix A, General Design Criterion (GDC) 55, Reactor coolant pressure boundary penetrating containment, requires that each line that is part of the reactor coolant pressure boundary and that penetrates primary reactor containment shall be provided with containment isolation valves as follows, unless it can be demonstrated that the containment isolation provisions for a specific class of lines, such as instrument lines, are acceptable on some other defined basis:

(1) One locked closed isolation valve inside and one locked closed isolation valve outside containment; or (2) One automatic isolation valve inside and one locked closed isolation valve outside containment; or (3) One locked closed isolation valve inside and one automatic isolation valve outside containment. A simple check valve may not be used as the automatic isolation valve outside containment; or (4) One automatic isolation valve inside and one automatic isolation valve outside containment. A simple check valve may not be used as the automatic isolation valve outside containment.

Isolation valves outside containment shall be located as close to containment as practical and upon loss of actuating power, automatic isolation valves shall be designed to take the position that provides greater safety.

Other appropriate requirements to minimize the probability or consequences of an accidental rupture of these lines or of lines connected to them shall be provided as necessary to assure adequate safety. Determination of the appropriateness of these requirements, such as higher quality in design, fabrication, and testing, additional provisions for inservice inspection, protection against more severe natural phenomena, and additional isolation valves and containment, shall include consideration of the population density, use characteristics, and physical characteristics of the site environs. The PORV block valves will continue to perform their design function of automatic containment isolation in their new locations. Additionally, relocating the branch lines for the PORV block valves to upstream of the branch connections for the MSSVs moves them closer to containment, consistent with GDC 55.

10 CFR Part 50, Appendix A, GDC 56, Primary containment isolation, requires that each line that connects directly to the containment atmosphere and penetrates primary reactor containment shall be provided with containment isolation valves as follows, unless it can be demonstrated that the containment isolation provisions for a specific class of lines, such as instrument lines, are acceptable on some other defined basis:

(1) One locked closed isolation valve inside and one locked closed isolation valve outside containment; or Page 8 of 15

ND-18-1277 Revision to Request for License Amendment: Power Operated Relief Valve (PORV) Noise Mitigation (LAR-18-021R1)

(2) One automatic isolation valve inside and one locked closed isolation valve outside containment; or (3) One locked closed isolation valve inside and one automatic isolation valve outside containment. A simple check valve may not be used as the automatic isolation valve outside containment; or (4) One automatic isolation valve inside and one automatic isolation valve outside containment. A simple check valve may not be used as the automatic isolation valve outside containment.

Isolation valves outside containment shall be located as close to the containment as practical and upon loss of actuating power, automatic isolation valves shall be designed to take the position that provides greater safety. The PORV block valves will continue to perform their design function of automatic containment isolation in their new locations. Additionally, relocating the branch lines for the PORV block valves to upstream of the branch connections for the MSSVs moves them closer to containment, consistent with GDC 56.

10 CFR Part 50, Appendix A, GDC 57, Closed system isolation valves, requires that each line that penetrates primary reactor containment and is neither part of the reactor coolant pressure boundary nor connected directly to the containment atmosphere shall have at least one containment isolation valve which shall be either automatic, or locked closed, or capable of remote manual operation. This valve shall be outside containment and located as close to the containment as practical. A simple check valve may not be used as the automatic isolation valve. The PORV block valves will continue to perform their design function of automatic containment isolation in their new locations. Additionally, relocating the branch lines for the PORV block valves to upstream of the branch connections for the MSSVs moves them closer to containment, consistent with GDC 57.

4.2 Precedent No precedent is identified.

4.3 Significant Hazards Consideration The requested amendment proposes a change to Updated Final Safety Analysis Report (UFSAR) Tier 2 information, which involves a change to Combined License (COL) Appendix C (and the corresponding plant-specific Design Control Document (DCD) Tier 1) information related to relocating the power operated relief valve (PORV) branch lines upstream of the main steam safety valves and changing the PORV block valves from gate valves to globe valves.

The requested amendment proposes changes to Tier 2 information in UFSAR Figure 10.3.2-1 (Sheets 1 and 2) and Tables 3.9-16, 6.2.3-1, and 10.3.3-1, which involve changes to Inspections, Tests, Analyses, and Acceptance Criteria (ITAAC)

Figure 2.2.4-1 (Sheets 1 and 2) of COL Appendix C (and corresponding changes to the plant-specific DCD Tier 1 information).

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ND-18-1277 Revision to Request for License Amendment: Power Operated Relief Valve (PORV) Noise Mitigation (LAR-18-021R1)

The change to the UFSAR proposes relocating the power operated relief valve (PORV) branch lines upstream of the branch lines to the main steam safety valves and changing the PORV block valves from gate valves to globe valves. The PORV block valves will continue to perform their design function of automatic containment isolation in their new locations. Additionally, relocating the branch lines for the PORV block valves to upstream of the branch connections for the MSSVs moves them closer to containment, consistent with GDC 55, 56, and 57.

An evaluation to determine whether or not a significant hazards consideration is involved with the proposed amendment was completed by focusing on the three standards set forth in 10 CFR 50.92, Issuance of amendment, as discussed below:

4.3.1 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 affect the operation or reliability of any system, structure or component (SSC) required to maintain a normal power operating condition or to mitigate anticipated transients without safety-related systems.

With the proposed changes, the PORV block valves are still able to perform the safety-related functions of containment isolation, steam generator isolation, and steam generator relief isolation. There is no change to the PORV block valves safety class or safety-related functions.

The relocation of the branch line in which the PORV block valves are installed in allows the PORV block valves to be closer to the containment penetration and maintain compliance with General Design Criterion (GDC) 57 for locating containment isolation valves as close to the containment as practical.

There is no impact to Chapter 15 evaluations. Changes to the PORV block valve and line size do not impact the mass releases to the atmosphere during a Steam Generator Tube Rupture accident. The mass release is limited by the PORV which is more restrictive than the PORV block valve and line size.

There is no impact to any assumed leakage through the PORV line. The existing 12-inch PORV has a design function to limit leakage through the PORV line. Increasing the PORV block valve to 12 inches will increase the leakage through the PORV block valve however it will be that same leakage rate as the 12-inch PORV. Therefore, the leakage rate through the PORV line does not increase and there is no impact to radiation doses.

There is no impact to the assumptions or analysis in the completed safety analysis for radiation doses as a result of the change.

There is no impact to the conclusions of the Pipe Rupture Hazard Analysis (PRHA) because the PORV line is Break Exclusion Zone (BEZ) piping. The proposed changes do not result in any new postulated break locations.

Updated analyses confirm that the integrity of the wall adjacent to the MCR is Page 10 of 15

ND-18-1277 Revision to Request for License Amendment: Power Operated Relief Valve (PORV) Noise Mitigation (LAR-18-021R1) unaffected by a postulated main steam line break that causes the PORV line to impact the wall.

There is no change to the valve motor operator. The current motor operator is sufficient to operate the new 12-inch globe valve. Therefore, there is no impact to the Class 1E dc and UPS System (IDS) battery sizing. There is no change to the valve stroke time, therefore there is no impact to valve open/closure times.

Therefore, the proposed amendment does not involve a significant increase in the probability or consequences of an accident previously evaluated.

4.3.2 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 affect the operation of systems or equipment that could initiate a new or different kind of accident, or alter any SSC such that a new accident initiator or initiating sequence of events is created. With the proposed changes, the PORV block valves are still able to perform the safety-related functions of containment isolation, steam generator isolation, and steam generator relief isolation. There is no change to the PORV block valves safety class or safety-related functions.

The relocation of the branch line in which the PORV block valves are installed in allows the PORV block valves to be closer to the containment penetration and maintain compliance with General Design Criterion (GDC) 57 for locating containment isolation valves as close to the containment as practical.

There is no impact to Chapter 15 evaluations. Changes to the PORV block valve and line size do not impact the mass releases to the atmosphere during a Steam Generator Tube Rupture accident. The mass release is limited by the PORV which is more restrictive than the PORV block valve and line size.

There is no impact to any assumed leakage through the PORV line. The existing 12-inch PORV has a design function to limit leakage through the PORV line. Increasing the PORV block valve to 12 inches will increase the leakage through the PORV block valve however it will be that same leakage rate as the 12-inch PORV. Therefore, the leakage rate through the PORV line does not increase and there is no impact to radiation doses.

There is no impact to the assumptions or analysis in the completed safety analysis for radiation doses as a result of the change.

There is no impact to the conclusions of the Pipe Rupture Hazard Analysis (PRHA) because the PORV line is Break Exclusion Zone (BEZ) piping. The proposed changes do not result in any new postulated break locations.

Updated analyses confirm that the integrity of the wall adjacent to the MCR is Page 11 of 15

ND-18-1277 Revision to Request for License Amendment: Power Operated Relief Valve (PORV) Noise Mitigation (LAR-18-021R1) unaffected by a postulated main steam line break that causes the PORV line to impact the wall.

There is no change to the valve motor operator. The current motor operator is sufficient to operate the new 12-inch globe valve. Therefore, there is no impact to the Class 1E dc and UPS System (IDS) battery sizing. There is no change to the valve stroke time, therefore there is no impact to valve open/closure times.

Therefore, the proposed amendment does not create the possibility of a new or different kind of accident from any accident previously evaluated.

4.3.3 Does the proposed amendment involve a significant reduction in a margin of safety?

Response: No.

The proposed changes do not affect existing safety margins. With the proposed changes, the PORV block valves are still able to perform the safety-related functions of containment isolation, steam generator isolation, and steam generator relief isolation. There is no change to the PORV block valves safety class or safety-related functions.

The relocation of the branch line in which the PORV block valves are installed in allows the PORV block valves to be closer to the containment penetration and maintain compliance with General Design Criterion (GDC) 57 for locating containment isolation valves as close to the containment as practical.

There is no impact to Chapter 15 evaluations. Changes to the PORV block valve and line size do not impact the mass releases to the atmosphere during a Steam Generator Tube Rupture accident. The mass release is limited by the PORV which is more restrictive than the PORV block valve and line size.

There is no impact to any assumed leakage through the PORV line. The existing 12-inch PORV has a design function to limit leakage through the PORV line. Increasing the PORV block valve to 12 inches will increase the leakage through the PORV block valve however it will be that same leakage rate as the 12-inch PORV. Therefore, the leakage rate through the PORV line does not increase and there is no impact to radiation doses.

There is no impact to the assumptions or analysis in the completed safety analysis for radiation doses as a result of the change.

The piping analysis for the affected piping has been revised in accordance with the requirements of the UFSAR. All stresses and interface loads remain acceptable and within the limits described in the UFSAR. The piping support calculations have been revised using the load combinations prescribed in the UFSAR, and the critical interaction ratio for each support is less than 1.0; therefore, a positive design margin exists. The proposed changes did not affect Page 12 of 15

ND-18-1277 Revision to Request for License Amendment: Power Operated Relief Valve (PORV) Noise Mitigation (LAR-18-021R1) any of the piping packages chosen (as listed in the UFSAR) to demonstrate piping design for piping design acceptance criteria closure. There is no impact to the conclusions of the Pipe Rupture Hazard Analysis (PRHA) because the PORV line is Break Exclusion Zone (BEZ) piping. The proposed changes do not result in any new postulated break locations. Updated analyses confirm that the integrity of the wall adjacent to the MCR is unaffected by a postulated main steam line break that causes the PORV line to impact the wall. The piping and components downstream of the PORV are nonsafety-related and are not affected by this activity.

The structural concrete floors and walls which make up the bounds of the affected rooms were analyzed for the downstream impacts due to the proposed changes. The results conclude that the applicable acceptance criteria of the UFSAR are met. All applicable load combinations shown in the UFSAR were considered. Critical sections defined in the UFSAR within the scope of analysis remain unchanged along with the typical reinforcement configuration presented in the UFSAR. Therefore, all structural evaluations are within the bounds of the acceptance criteria and meet the licensing requirements imposed in the UFSAR.

There is no change to the valve motor operator. The current motor operator is sufficient to operate the new 12-inch globe valve. Therefore, there is no impact to the Class 1E dc and UPS System (IDS) battery sizing. There is no change to the valve stroke time, therefore there is no impact to valve open/closure times.

Therefore, the proposed amendment does not involve a significant reduction in a margin of safety.

Based on the above, it is concluded 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 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. The above evaluations demonstrate that the requested changes can be accommodated without an increase in the probability or consequences of an accident previously evaluated, without creating the possibility of a new or different kind of accident from any accident previously evaluated, and without a significant reduction in a margin of safety. Having arrived at negative declarations with regard to the criteria of 10 CFR 50.92, this assessment determined that the requested change does not involve a Significant Hazards Consideration.

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ND-18-1277 Revision to Request for License Amendment: Power Operated Relief Valve (PORV) Noise Mitigation (LAR-18-021R1)

5. ENVIRONMENTAL CONSIDERATIONS Southern Nuclear Operating Company (SNC or Licensee) is requesting an amendment to Combined License (COL) Nos. NPF-91 and NPF-92 for Vogtle Electric Generating Plant (VEGP) Units 3 and 4, respectively. The requested amendment proposes a change to Updated Final Safety Analysis Report (UFSAR) Tier 2 information, which involves a change to COL Appendix C (and the corresponding plant-specific Design Control Document (DCD) Tier 1) information related to relocating the power operated relief valve (PORV) branch lines upstream of the main steam safety valves branch connections and changing the PORV block valves from gate valves to globe valves.

The requested amendment proposes changes to Tier 2 information in UFSAR Table 3.9-16, Table 10.3.3-1, and Figure 10.3.2-1 (Sheets 1 and 2), which involve changes to Inspections, Tests, Analyses, and Acceptance Criteria (ITAAC) Figure 2.2.4-1 (Sheets 1 and 2) of COL Appendix C, and corresponding changes to the plant-specific DCD Tier 1 information.

The change to the UFSAR proposes relocating the power operated relief valve (PORV) branch lines upstream of the branch lines to the main steam safety valves and changing the PORV block valves from gate valves to globe valves.

Sections 2 and 3 of this license amendment request provide the details of the proposed changes.

The Licensee has determined that the anticipated construction and operational effects of the proposed amendment meet the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9), in that:

(i) There is no significant hazards consideration.

As documented in Section 4.3, Significant Hazards Consideration, of this license amendment request, an evaluation was completed to determine whether or not a significant hazards consideration is involved by focusing on the three standards set forth in 10 CFR 50.92, Issuance of amendment. The Significant Hazards Consideration determined that (1) the requested amendment does not involve a significant increase in the probability or consequences of an accident previously evaluated; (2) the requested amendment does not create the possibility of a new or different kind of accident from any accident previously evaluated; and (3) the requested amendment does not involve a significant reduction in a margin of safety. Therefore, it is concluded that the requested 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.

(ii) There is no significant change in the types or significant increase in the amounts of any effluents that may be released offsite.

The proposed changes do not affect any aspect of plant construction or operation that introduces a change to any effluent types (for example effluents containing chemicals or biocides, sanitary system effluents, and other effluents), and do not affect any plant radiological or non-radiological effluent release quantities. There is no impact to any Page 14 of 15

ND-18-1277 Revision to Request for License Amendment: Power Operated Relief Valve (PORV) Noise Mitigation (LAR-18-021R1) assumed leakage through the PORV line. The existing 12-inch PORV has a design function to limit leakage through the PORV line. Increasing the PORV block valve to 12 inches will increase the leakage through the PORV block valve however it will be that same leakage rate as the 12-inch PORV. Therefore, the leakage rate through the PORV line does not increase and there is no impact to radiation doses. There is no impact to the assumptions or analysis in the completed safety analysis for radiation doses as a result of the change. Accordingly, there is no significant change in the types or significant increase in the amounts of any effluents that may be released offsite.

Therefore, it is concluded that the requested amendment does not involve a significant change in the types or a significant increase in the amounts of any effluents that may be released offsite.

(iii) There is no significant increase in individual or cumulative occupational radiation exposure.

The proposed changes do not affect walls, floors, or other structures that provide radiation shielding. There is no impact to any assumed leakage through the PORV line.

The existing 12-inch PORV has a design function to limit leakage through the PORV line. Increasing the PORV block valve to 12 inches will increase the leakage through the PORV block valve however it will be that same leakage rate as the 12-inch PORV.

Therefore, the leakage rate through the PORV line does not increase and there is no impact to radiation doses. There is no impact to the assumptions or analysis in the completed safety analysis for radiation doses as a result of the change. Accordingly, there is no significant change in the types or significant increase in the amounts of any effluents that may be released offsite. Furthermore, company and station policies maintain radiation exposure of personnel within limits defined by 10 CFR Part 20, "Standards for Protection Against Radiation." Administrative procedures and practices are implemented to maintain radiation exposure of personnel as low as is reasonably achievable. Therefore, it is concluded that the requested amendment does not involve a significant increase in individual or cumulative occupational radiation exposure.

Based on the above review of the requested amendment, it has been determined that anticipated construction and operational effects of the requested amendment do 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 requested amendment meets the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9). Therefore, pursuant to 10 CFR 51.22(b), an environmental impact statement or environmental assessment of the proposed amendment is not required.

6. REFERENCES None.

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Southern Nuclear Operating Company ND-18-1277 Enclosure 6 Vogtle Electric Generating Plant (VEGP) Units 3 and 4 Revision to Exemption Request:

Power Operated Relief Valve (PORV) Noise Mitigation (LAR-18-021R1)

(This Enclosure consists of 9 pages, including this cover page.)

ND-18-1277 Revision to Exemption Request: Power Operated Relief Valve (PORV) Noise Mitigation (LAR 18-021R1) 1.0 Purpose Southern Nuclear Operating Company (the Licensee) requests a permanent exemption from the provisions of 10 CFR 52, Appendix D, Section III.B, Design Certification Rule for the AP1000 Design, Scope and Contents, to allow a departure from elements of the certification information in Tier 1 of the generic AP1000 Design Control Document (DCD). The regulation, 10 CFR 52, Appendix D, Section III.B, requires an applicant or licensee referencing Appendix D to 10 CFR Part 52 to incorporate by reference and comply with the requirements of Appendix D, including certified information in DCD Tier 1. The Tier 1 information for which a plant-specific departure and exemption is being requested includes relocating the power operated relief valve (PORV) branch lines upstream of the branch lines to the main steam safety valves.

This request for exemption provides the technical and regulatory basis to demonstrate that 10 CFR 52.63, §52.7, and §50.12 requirements are met and will apply the requirements of 10 CFR 52, Appendix D, Section VIII.A.4 to allow departures from generic Tier 1 information due to a proposed change to Inspections, Tests, Analyses, and Acceptance Criteria (ITAAC) Figure 2.2.4-1 (Sheets 1 and 2) to depict relocation of the power operated relief valve (PORV) branch lines upstream of the branch lines to the main steam safety valves.

2.0 Background The Licensee is the holder of Combined License Nos. NPF-91 and NPF-92, which authorize construction and operation of two Westinghouse Electric Company AP1000 nuclear plants, named Vogtle Electric Generating Plant (VEGP) Units 3 and 4, respectively.

Design Function Related to Activity Power-Operated Relief Valves (PORV) (SGS-PL-V233A/B)

The PORVs perform the safety-related functions of steam generator isolation and steam generator relief isolation. During plant operations, the PORVs are automatically controlled by steam line pressure. The valves modulate open and exhaust to the atmosphere whenever the steam line pressure exceeds an operator established set point. When needed for plant cooldown, the PORVs are automatically controlled by steam line pressure with remote manual adjustment of the pressure set point from the control room or remote shutdown workstation. In order to cooldown the plant, the operator manually adjusts the pressure set point downward in discrete steps or takes manual control of the valve position.

Each PORV is installed in a branch line off the safety-related portion of the main steam line upstream of the main steam isolation valve (MSIV).

PORV Block Valves (SGS-PL-V027A/B)

The PORV block valves perform the safety-related functions of containment isolation, steam generator isolation, and steam generator relief isolation. The PORV block valves Page 2 of 9

ND-18-1277 Revision to Exemption Request: Power Operated Relief Valve (PORV) Noise Mitigation (LAR 18-021R1) also provide the capability to isolate a leaking or stuck-open PORV. The PORV block valves are AP1000 Safety Class B and close automatically on a Low-2 steam line pressure signal generated in the Protection and Safety Monitoring System (PMS).

Each PORV block valve is located in the branch line upstream of the PORV. The upstream location allows maintenance of the PORV at power.

Containment Isolation The containment isolation system meets the design requirements set forth in General Design Criteria (GDC) 55, 56 and 57 of Appendix A to Title 10 of the Code of Federal Regulations (CFR) Part 50. A regulatory requirement common to all containment isolation valves governed by GDCs 55, 56, and 57 is isolation valves outside containment be located as close to the containment as practical. The intent of this design requirement is to minimize the probability that containment integrity could be compromised due to dynamic effects or natural events. UFSAR Table 6.2.3-1 lists the nominal length of pipe between each containment penetration and the containment isolation valve.

Reason for Activity During testing of the PORVs in operation at another facility, the noise level in the main control room (MCR) was approximately 85 dB(A) and the noise level at the PORVs was approximately 110 dB(A). The size and geometry of the PORV block valves cause a high flow velocity (~800 ft/sec) and Helmholtz resonance which results in an increase in noise level. Since the PORV block valves are located in rooms adjacent to the MCR, the sound from the PORV block valves is transmitted into the MCR. Changes to the PORV block valves are necessary in order to reduce the noise contribution to the MCR and improve human factors with the PORVs in operation.

Description of Activity To reduce noise contribution to the MCR from the PORV block valves, the PORV block valve size is proposed to be changed from 6-inch to 12-inch. The branch line that the PORV block valves are installed in is also proposed to be changed from 6 inches to 12 inches. These changes reduce the flow velocity to less than 200 ft/sec and as a result the noise level is reduced.

Due to layout constraints with the proposed changes, the location of the branch line that the PORV block valves are installed in is moved upstream of the main steam safety valves (MSSVs) branch connections. Plant-specific Tier 1 ITAAC Figure 2.2.4-1 (Sheets 1 and 2) is revised to show the PORV branch line upstream of the MSSVs.

3.0 Technical Justification of Acceptability With the proposed changes, the PORV block valves are still able to perform the safety-related functions of containment isolation, steam generator isolation, and steam generator relief isolation. There is no change to the PORV block valves safety class or safety-related functions.

Page 3 of 9

ND-18-1277 Revision to Exemption Request: Power Operated Relief Valve (PORV) Noise Mitigation (LAR 18-021R1)

The relocation of the branch line that the PORV block valves are installed in allows the PORV block valves to be closer to the containment penetration and maintain compliance with GDC 57 for locating containment isolation valves as close to the containment as practical.

There is no impact to the assumptions or analysis in the completed safety analysis for radiation doses as a result of the change.

The piping analysis for the affected piping has been revised in accordance with the requirements of UFSAR Subsection 3.9.3.1.5. All stresses and interface loads remain acceptable and within the limits described in UFSAR Table 3.9-7. The piping support calculations have been revised using the load combinations shown in UFSAR Table 3.9-8, and the critical interaction ratio for each support is less than 1.0; therefore, a positive design margin exists. The proposed changes did not affect any of the piping packages listed in Table 3.9-20. There is no impact to the conclusions of the Pipe Rupture Hazard Analysis (PRHA) because the PORV line is Break Exclusion Zone (BEZ) piping.

Revised calculations show that the proposed changes do not result in any new postulated break locations. Updated analyses confirm that the integrity of the wall adjacent to the MCR is unaffected by a postulated main steam line break that causes the PORV line to impact the wall. The piping and components downstream of the PORV are nonsafety-related and are not affected by this activity.

The structural concrete floors and walls which make up the bounds of Rooms 12404 and 12406 were analyzed for the downstream impacts due to the proposed changes. The results conclude that the acceptance criteria of UFSAR Subsection 3.8.4.2, specifically ACI 349-01, are met. All applicable load combinations shown in UFSAR Table 3.8.4-2 were considered. Critical sections defined in UFSAR Subsection 3.8.4.5.4 within the scope of analysis are L-line, elevation 117-6 to 135-3 and 11-line, elevation 117-6 to 135-3 between L-line and M-line. The analysis of L-line confirms that Tier 2*

information depicted in UFSAR Table 3H.5-7 remains unchanged along with the typical reinforcement configuration presented in UFSAR Figure 3H.5-12. The review of 11-line confirms no impact to neither UFSAR Section 3H.5.1.4 nor Figure 3H.5-5. Therefore, all structural evaluations are within the bounds of the acceptance criteria and meet the licensing requirements imposed in UFSAR Chapter 3.

The proposed changes do not result in a modification to, addition to, or removal of a structure, system, or component (SSC) such that a design function is adversely affected, have no impact on plant operating procedures or a method of control that adversely affects a design function, do not result in an adverse change to a method of evaluation or use of an alternate method of evaluation, do not represent tests or experiments outside the reference bounds of the design basis, and do not alter the assumptions or results of the ex-vessel severe accident assessment.

Detailed technical justification supporting this request for exemption is provided in Section 3 of the associated License Amendment Request in Enclosure 1 of this letter.

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ND-18-1277 Revision to Exemption Request: Power Operated Relief Valve (PORV) Noise Mitigation (LAR 18-021R1) 4.0 Justification of Exemption 10 CFR Part 52, Appendix D, Section VIII.A.4 and 10 CFR 52.63(b)(1) govern the issuance of exemptions from elements of the certified design information for AP1000 nuclear power plants. Since SNC has identified changes to the Tier 1 information as discussed in Enclosure 1 of the accompanying License Amendment Request, an exemption from the certified design information in Tier 1 is needed.

10 CFR Part 52, Appendix D, and 10 CFR 50.12, §52.7, and §52.63 state that the NRC may grant exemptions from the requirements of the regulations provided six conditions are met: 1) the exemption is authorized by law [§50.12(a)(1)]; 2) the exemption will not present an undue risk to the health and safety of the public [§50.12(a)(1)]; 3) the exemption is consistent with the common defense and security [§50.12(a)(1)]; 4) special circumstances are present [§50.12(a)(2)]; 5) the special circumstances outweigh any decrease in safety that may result from the reduction in standardization caused by the exemption [§52.63(b)(1)]; and 6) the design change will not result in a significant decrease in the level of safety [Part 52, App. D, VIII.A.4].

The requested exemption satisfies the criteria for granting specific exemptions, as described below.

1. This exemption is authorized by law The NRC has authority under 10 CFR 52.63, §52.7, and §50.12 to grant exemptions from the requirements of NRC regulations. Specifically, 10 CFR 50.12 and §52.7 state that the NRC may grant exemptions from the requirements of 10 CFR Part 52 upon a proper showing. No law exists that would preclude the changes covered by this exemption request. Additionally, granting of the proposed exemption does not result in a violation of the Atomic Energy Act of 1954, as amended, or the Commissions regulations.

Accordingly, this requested exemption is authorized by law, as required by 10 CFR 50.12(a)(1).

2. This exemption will not present an undue risk to the health and safety of the public The proposed exemption from the requirements of 10 CFR 52, Appendix D, Section III.B would allow changes to elements of the plant-specific Tier 1 DCD to depart from the AP1000 certified (Tier 1) design information. The plant-specific DCD Tier 1 will continue to reflect the approved licensing basis for VEGP Units 3 and 4, and will maintain a consistent level of detail with that which is currently provided elsewhere in Tier 1 of the DCD. Therefore, the affected plant-specific DCD Tier 1 ITAAC will continue to serve its required purpose.

The proposed change to relocate the power operated relief valve (PORV) branch lines upstream of the branch lines to the main steam safety valves does not represent an adverse impact to the design functions provided by the steam generator system (SGS),

which will continue to protect the health and safety of the public by performing its safety Page 5 of 9

ND-18-1277 Revision to Exemption Request: Power Operated Relief Valve (PORV) Noise Mitigation (LAR 18-021R1) related function of containment isolation. The change does not introduce any new industrial, chemical, or radiological hazards that would represent a public health or safety risk, nor do they modify or remove any design or operational controls or safeguards intended to mitigate any existing on-site hazards. Furthermore, the proposed change would not allow for a new fission product release path, result in a new fission product barrier failure mode, or create a new sequence of events that would result in fuel cladding failures. Accordingly, this change does not present an undue risk from any existing or proposed equipment or systems.

Therefore, the requested exemption from 10 CFR 52, Appendix D, Section III.B would not present an undue risk to the health and safety of the public.

3. The exemption is consistent with the common defense and security The requested exemption from the requirements of 10 CFR 52, Appendix D, Section III.B would allow the licensee to depart from elements of the plant-specific DCD Tier 1 design information. The proposed exemption does not alter the design, function, or operation of any structures or plant equipment that are necessary to maintain a safe and secure status of the plant. The proposed exemption has no impact on plant security or safeguards procedures.

Therefore, the requested exemption is consistent with the common defense and security.

4. Special circumstances are present 10 CFR 50.12(a)(2) lists six special circumstances for which an exemption may be granted. Pursuant to the regulation, it is necessary for one of these special circumstances to be present in order for the NRC to consider granting an exemption request. The requested exemption meets the special circumstances of 10 CFR 50.12(a)(2)(ii). That subsection defines special circumstances as when Application of the regulation in the particular circumstances would not serve the underlying purpose of the rule or is not necessary to achieve the underlying purpose of the rule.

The rule under consideration in this request for exemption is 10 CFR 52, Appendix D, Section III.B, which requires that a licensee referencing the AP1000 Design Certification Rule (10 CFR Part 52, Appendix D) shall incorporate by reference and comply with the requirements of Appendix D, including Tier 1 information. The VEGP Units 3 and 4 COLs reference the AP1000 Design Certification Rule and incorporate by reference the requirements of 10 CFR Part 52, Appendix D, including Tier 1 information. The underlying purpose of Appendix D,Section III.B is to describe and define the scope and contents of the AP1000 design certification, and to require compliance with the design certification information in Appendix D.

The proposed exemption would relocate the power operated relief valve (PORV) branch lines upstream of the branch lines to the main steam safety valves.

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ND-18-1277 Revision to Exemption Request: Power Operated Relief Valve (PORV) Noise Mitigation (LAR 18-021R1)

The proposed exemption does not adversely affect the design function of the steam generator system, because the PORV block valves are still able to perform the safety-related functions of containment isolation, steam generator isolation, and steam generator relief isolation. There is no change to the PORV block valves safety class or safety-related functions. Additionally, the relocation of the branch line that the PORV block valves are installed in allows the PORV block valves to be closer to the containment penetration and maintain compliance with GDC 57 for locating containment isolation valves as close to the containment as practical Therefore, special circumstances are present, because application of the current generic certified design information in Tier 1 as required by 10 CFR Part 52, Appendix D, Section III.B, in the particular circumstances discussed in this request is not necessary to achieve the underlying purpose of the rule.

5. The special circumstances outweigh any decrease in safety that may result from the reduction in standardization caused by the exemption.

Based on the nature of the changes to the plant-specific Tier 1 information and the understanding that these changes support the design function of the supported equipment, it is expected that this exemption may be requested by other AP1000 licensees and applicants. However, a review of the reduction in standardization resulting from the departure from the standard DCD determined that even if other AP1000 licensees and applicants do not request this same departure, the special circumstances will continue to outweigh any decrease in safety from the reduction in standardization because the key design functions of the equipment associated with this request will continue to be maintained. Furthermore, the justification provided in the license amendment request and this exemption request and the associated mark-ups demonstrate that there is a limited change from the standard information provided in the generic AP1000 DCD, which is offset by the special circumstances identified above.

Therefore, the special circumstances associated with the requested exemption outweigh any decrease in safety that may result from the reduction in standardization caused by the exemption.

6. The design change will not result in a significant decrease in the level of safety.

The exemption revises the plant-specific DCD Tier 1 information to relocate the power operated relief valve (PORV) branch lines upstream of the branch lines to the main steam safety valves. With the proposed changes, the PORV block valves are still able to perform the safety-related functions of containment isolation, steam generator isolation, and steam generator relief isolation. There is no change to the PORV block valves safety class or safety-related functions. Additionally, the relocation of the branch line that the PORV block valves are installed in allows the PORV block valves to be closer to the containment penetration and maintain compliance with GDC 57 for locating containment isolation valves as close to the containment as practical. Because these functions continue to be met, there is no reduction in the level of safety.

Page 7 of 9

ND-18-1277 Revision to Exemption Request: Power Operated Relief Valve (PORV) Noise Mitigation (LAR 18-021R1) 5.0 Risk Assessment A risk assessment was not determined to be applicable to address the acceptability of this proposal.

6.0 Precedent Exemptions None 7.0 Environmental Consideration The Licensee requests a departure from elements of the certified information in Tier 1 of the generic AP1000 DCD. The Licensee has determined that the proposed departure would require a permanent exemption from the requirements of 10 CFR 52, Appendix D, Section III.B, Design Certification Rule for the AP1000 Design, Scope and Contents, with respect to installation or use of facility components located within the restricted area, as defined in 10 CFR Part 20, or which changes an inspection or a surveillance requirement; however, the Licensee evaluation of the proposed exemption has determined that the proposed exemption meets the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9).

Based on the above review of the proposed exemption, the Licensee has determined that the proposed activity 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 exemption meets the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9). Therefore, pursuant to 10 CFR 51.22(b), an environmental impact statement or environmental assessment of the proposed exemption is not required.

Specific details of the environmental considerations supporting this request for exemption are provided in Section 5 of the associated License Amendment Request provided in Enclosure 1 of this letter.

8.0 Conclusion The proposed changes to Tier 1 are necessary to relocate the power operated relief valve (PORV) branch lines upstream of the branch lines to the main steam safety valves.

The exemption request meets the requirements of 10 CFR 52.63, Finality of design certifications, 10 CFR 52.7, Specific exemptions, 10 CFR 50.12, Specific exemptions, and 10 CFR 52 Appendix D, Design Certification Rule for the AP1000. Specifically, the exemption request meets the criteria of 10 CFR 50.12(a)(1) in that the request is authorized by law, presents no undue risk to public health and safety, and is consistent with the common defense and security. Furthermore, approval of this request does not result in a significant decrease in the level of safety, satisfies the underlying purpose of the AP1000 Design Certification Rule, and does not present a significant decrease in safety as a result of a reduction in standardization.

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ND-18-1277 Revision to Exemption Request: Power Operated Relief Valve (PORV) Noise Mitigation (LAR 18-021R1) 9.0 References None.

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