ML23257A232

SNC Presentation - Pre-Submittal Meeting on September 28, 2023 - Proposed Vogtle 3 and 4 TS 3.7.6 LAR

ML23257A232
Person / Time
Site:	Vogtle
Issue date:	09/28/2023
From:	Southern Nuclear Company
To:	Office of Nuclear Reactor Regulation
References
EPID L-2023-LRQ-0004
Download: ML23257A232 (24)

Text

SNC Vogtle 3&4 Pre-Submittal Meeting License Amendment Request: Revise Technical Specification 3.7.6 to Provide Main Control Room Emergency Habitability System (VES) Operational Flexibility (LAR 23-009)

September 28, 2023

Meeting Purpose (LAR 23-009)

• The purpose is to discuss a proposed revision to the Combined License (COL) Appendix A, Technical Specifications (TS),

Surveillance Requirement (SR) 3.7.6.5 to refer to the American National Standards Institute (ANSI) / Compressed Gas Association (CGA) Commodity Specification for Air, G-7.1, Grade E, for the requirements for acceptable air quality in the VES air storage tanks.

• In addition, proposed clarifying changes to TS 3.7.6 Condition E to provide a more specific description of the inoperable condition and associated Action; and to SR 3.7.6.8 to more specifically identify the surveillance as a functional test will be discussed.

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Meeting Agenda (LAR 23-009)

• This meeting will cover the following topics for each license amendment request:

- Reason for Proposed Change

- Proposed License Amendment Request

- Technical Specification Mark-up

- Evaluation

- Precedent (if applicable) 3

Proposed Changes to TS Surveillance Requirement (SR) 3.7.6.5 (LAR 23-009)

Proposed Changes to TS Surveillance Requirement (SR) 3.7.6.5 (LAR 23-009)

• Reason for Proposed Change

- TS SR 3.7.6.5, which requires that SNC Verify the air quality of the air storage tanks meets the requirements of Appendix C, Table C-1 of ASHRAE Standard 62 with a pressure dew point of 40°F at 3400 psig every 92 days.

- American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc.

(ASHRAE) Standard 62 was not written to specify the air quality for compressed air inside air storage tanks. In addition, sampling and analysis for some of the pollutants identified in ASHRAE Standard 62 Table C-1 requires highly specialized equipment to measure the levels listed in the table with some samples needing to be sent to offsite laboratories to be analyzed.

- SNC has determined testing to this ASHRAE standard is overly burdensome, and that sufficient air quality can be achieved by a single federally recognized standard without negatively impacting safety.

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Proposed Changes to TS Surveillance Requirement (SR) 3.7.6.5 (LAR 23-009)

• Proposed License Amendment Request

- Proposed changes to SR 3.7.6.5 would revise the referenced standard for the testing requirements for VES storage tanks air quality testing from ASHRAE Standard 62-1989 to the American National Standards Institute (ANSI) / Compressed Gas Association (CGA) Commodity Specification for Air, G-7.1, Grade E.

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Proposed Changes to TS Surveillance Requirement (SR) 3.7.6.5 (LAR 23-009)

• Technical Specification Mark-up

- Propose Revision to SR 3.7.6.5 SURVEILLANCE FREQUENCY SR 3.7.6.5 Verify the air quality of the air storage tanks meets the requirements of 92 days Grade E of ANSI / CGA G-7.1 Appendix C, Table C-1 of ASHRAE Standard 62 with a pressure dew point of 40°F at 3400 psig.

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Proposed Changes to TS Surveillance Requirement (SR) 3.7.6.5 (LAR 23-009)

• Evaluation

- NUREG-700 Human-System Interface Design Review Guidelines, control room ventilation should be provided to keep gases, vapors, dust, and fumes within the permissible exposure limits specified by 29 CFR Part 1910.

- The OSHA standard 29 CFR 1910.134(i) states that Compressed breathing air shall meet at least the requirements for Grade D breathing air described in ANSI/CGA Commodity Specification G-7.1-1989.

- The minimum air grade quality per the VES design specification is Grade E which meets or exceeds the requirement of CGA Grade D.

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Proposed Changes to TS Surveillance Requirement (SR) 3.7.6.5 (LAR 23-009)

• Evaluation Limiting ANSI/CGA G-7.1 Grade E ANSI/CGA G-7.1 Grade D ASHRAE 62 Table C-1 (Note 2)

Characteristics

% Oxygen by Volume 20-22 19.5-23.5 Not Specified Carbon Dioxide < 1000 ppm < 1000 ppm Not Specified Carbon Monoxide < 10 ppm < 10 ppm <50 ppm Particulates <5 mg/cm^3 <5 mg/cm^3 <150 mg/m^3 Hydrocarbons < 25 ppm Not Specified Not Specified Odor Lack of noticeable odor Lack of noticeable odor Not Specified Moisture Content Note 1 Note 1 Not Specified Note 1: Both Grade D and Grade E specify a dew point not to exceed -65 °F (24 ppm v/v) or 10 degrees Fahrenheit lower than the coldest temperature expected in the area is required.

Note 2: Other contaminates listed in Table C-1 are guidelines limits for indoor air quality and ventilation for commercial and industrial buildings and are not directly comparible to CGA standard ratings.

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Proposed Changes to TS Surveillance Requirement (SR) 3.7.6.5 (LAR 23-009)

• Evaluation

- The high-pressure compressed and instrument air system (CAS) includes an inlet filter, high-pressure compressor, discharge check valve, and air purifier/dryer that provides Grade E air quality standard to the VES storage tanks.

- As added protection, the VES filtration air handler unit provides similar design features as those provided by air-purifying respirators which would provide a redundant means of minimizing the presence of potential pollutants in the tanks.

- In conclusion, the proposed standard exceeds the employee breathing air quality requirements of 29 CFR 1910.134 for atmosphere-supplying respirators.

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Proposed Changes to TS Surveillance Requirement (SR) 3.7.6.5 (LAR 23-009)

• Precedent

- This request is consistent with the staff review the NuScale control room habitability system design and its ability to provide a safe control room environment from which actions can be taken to operate the nuclear power unit safely under normal conditions and to maintain it in a safe condition under accident conditions, including Loss-of-Coolant Accidents (LOCAs) [ML20205L406].

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Proposed Changes to TS 3.7.6 Condition E (LAR 23-009)

Proposed Changes to TS 3.7.6 Condition E (LAR 23-009)

• Reason for Proposed Change

- TS 3.7.6 Condition E, Main Control Room Emergency Habitability System (VES),

requires action to be taken to restore the VES to OPERABLE status within 7 days when one bank of VES air tanks is determined to be inoperable. While in this condition, the stored amount of compressed air in the remaining OPERABLE VES air tanks must be verified to be to be greater than 245,680 scf within 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> and every 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> thereafter. Condition E also requires verification of the availability of the VBS MCRE ancillary fans and supporting equipment within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.

- TS 3.7.6 Condition E does not clearly convey the intent to confirm the equivalent volume of three banks of compressed air (> 245,680 scf of compressed air) is available whenever the total compressed air storage volume is determined to be 327,574 scf. There are no specific operability criteria for "bank" or individual "tanks" to be declared inoperable as expressed in this condition.

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Proposed Changes to TS 3.7.6 Condition E (LAR 23-009)

• Proposed License Amendment Request

- The proposed change would modify TS 3.7.6 Condition E to replace the condition description of One bank of VES air tanks inoperable with Compressed air storage tanks contain 327,574 scf of compressed air.

Required Action E.1 will be also clarified to replace "OPERABLE tanks" with "compressed air storage tanks."

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Proposed Changes to TS 3.7.6 Condition E (LAR 23-009)

• Technical Specification Mark-up

- Proposed Revision to TS 3.7.6 Condition E D.3 Restore MCRE boundary 90 days to OPERABLE status.

E. Compressed air storage E.1 Verify that the OPERABLE 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> tanks contain 327,574 compressed air storage scf of compressed air. tanks contain > 245,680 scf AND One bank of VES air of compressed air.

tanks inoperable. Once per 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> thereafter AND E.2 Verify VBS MCRE ancillary 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> fans and supporting equipment are available.

AND E.3 Restore VES to 7 days OPERABLE status.

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Proposed Changes to TS 3.7.6 Condition E (LAR 23-009)

• Evaluation

- The VES includes 32 compressed air storage tanks arranged in four banks of eight tanks each. Each bank provides at least 81,893.5 scf of compressed air to support the minimum required 327,574 scf for 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> of breathable air the main control room envelope. The key CONDITION for operability for the condition is when the total tank volume falls below the minimum required tank volume, not One bank of VES air tanks inoperable as describe in the TS.

- The remaining tank volume in this condition must be maintained greater than 245,680 scf of compressed air (i.e., the equivalent of three banks available) to supply air to the MCRE for 54 hours6.25e-4 days <br />0.015 hours <br />8.928571e-5 weeks <br />2.0547e-5 months <br /> (75% of the required 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />).

- Dose calculations have verified that the MCR dose limits will remain within the requirements of GDC 19 if 75 percent of the VES breathable compressed air capacity is available and compensatory measures are put in place (i.e., using the ancillary fans).

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Proposed Changes to TS SR 3.7.6.8 (LAR 23-009)

Proposed Changes to TS SR 3.7.6.8 (LAR 23-009)

• Reason for Proposed Change

- TS SR 3.7.6.8 requires verification every 24 months that each VES pressure relief damper is OPERABLE. This SR is used in combination with verification of the operability of the VES pressure relief isolation valves per SR 3.7.6.7 to ensure that adequate vent area is available to mitigate MCRE over-pressurization.

- TS SR 3.7.6.8 does not specifically identify the surveillance test for the VES pressure relief valves. The ambiguous requirement to verify the OPERABILITY of each VES pressure relief damper does not sufficiently identify the required method for performing this verification.

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Proposed Changes to TS SR 3.7.6.8 (LAR 23-009)

• Proposed License Amendment Request

- The proposed change would modify TS SR 3.7.6.8 to replace "Verify each VES pressure relief damper is OPERABLE" with "Perform a functional test of each VES pressure relief damper."

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Proposed Changes to TS SR 3.7.6.8 (LAR 23-009)

• Technical Specification Mark-up

- Proposed Revision to TS SR 3.7.6.8 SR 3.7.6.5 Perform a functional test of each VES pressure relief damper.Verify 92 days each VES pressure relief damper is OPERABLE.

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Proposed Changes to TS SR 3.7.6.8 (LAR 23-009)

• Evaluation

- The primary function of the safety-related gravity/relief dampers is to control pressure in the MCRE. The gravity/relief dampers self-adjust to provide the necessary relief airflow rate out of the MCRE to maintain the MCRE pressure within a minimum value with respect to surrounding areas and a maximum value to prevent MCRE over-pressurization.

- Performance tests are conducted every 24 months to confirm that the relief dampers can satisfy these design functions. However, the surveillance description as written does not clearly align to these performance or OPERABILITY test. This is a clarification change only.

There is no impact to any surveillance test or procedures.

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Schedule Schedule (LAR 23-009)

• Schedule

- Submit LAR - 4th Quarter 2023.

- Request approval - 1 year from acceptance 23

Questions?