NL-16-0660, Response to Request for Additional Information on Secondary Containment Drawdown Time Technical Specification Amendment Request

Response to Request for Additional Information on Secondary Containment Drawdown Time Technical Specification Amendment Request

ML16137A793
Person / Time
Site:	Hatch
Issue date:	05/16/2016
From:	Pierce C Southern Nuclear Operating Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
NL-16-0660
Download: ML16137A793 (5)

Text

Charles R. Pierce Southern Nuclear Regulatory Affairs Director Operating Company, Inc.

40 Inverness Center Parkway Post Office Box 1295 Birmingham, AL 35242 Tel 205.992.7872 SOUTHER , \

Fax 205.992.7601 NUCLEAR A SOUTHERN COMPANY MAY 1 6 2016 Docket Nos.: 50-321 NL-16-0660 50-366 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D. C. 20555-0001 Edwin I. Hatch Nuclear Plant Units 1 and 2 Response to Request for Additional Information on Secondary Containment Drawdown Time Technical Specifications Amendment Request Ladies and Gentlemen:

By letter dated October 15, 2015, Southern Nuclear Operating Company (SNC) submitted *a license amendment request for Edwin I. Hatch Nuclear Plant (HNP)

Units 1 and 2. The proposed amendment would revise the Unit 1 and 2 HNP Technical Specifications Surveillance Requirement (SA) 3.6.4.1.3 to increase the allowable time for the Standby Gas Treatment System (SGTS) to draw down the secondary containment to the required negative pressure from 2 minutes to 10 minutes.

By letters dated February 18, 2016 and April 15, 2016, the Nuclear Regulatory Commission (NRC) issued requests for additional information (RAis). SNC partially responded to the February 18, 2016 RAI on March 16, 2016 and responded to the April15, 2016 RAI on May 9, 2016.

RAI question #1 from the original February 18, 2016 RAI, dealing with Main Control Room ingress and egress doses, was deferred until 90 days from the date of the RAI. The enclosure to this letter responds to that question, thus completing the response to the February 18,2016 RAI.

This letter contains no NRC commitments.

If you have any questions, please contact Ken McElroy at (205) 992-7369.

U.S. Nuclear Regulatory Commission NL-16-0660 Page2 Mr. C.R. Pierce states he is Regulatory Affairs Director of Southern Nuclear Operating Company, is authorized to execute this oath on behalf of Southern Nuclear Operating Company and, to the best of his knowledge and belief, the facts set forth in this letter are true.

ResCcU/iu~

C. R. Pierce Regulatory Affairs Director CRP/OCV/

d before me this I' I& day ot...L.J11

__ A_,_y_ _ __,, 2016.

D My commission expires: /0 ~!1 ~ 2 oI -1

Enclosures:

Response to Request for Additional Information cc: Southern Nuclear Operating Company Mr. S. E. Kuczynski, Chairman, President & CEO Mr. D. G. Bost, Executive Vice President & Chief Nuclear Officer Mr. D. R. Vineyard, Vice President- Hatch Mr. M. D. Meier, Vice President- Regulatory Affairs Mr. D. R. Madison, Vice President- Fleet Operations Mr. B. J. Adams, Vice President- Engineering Mr. G. L. Johnson, Regulatory Affairs Manager- Hatch RType: CHA02.004 U. S. Nuclear Regulatory Commission Ms. C. Haney, Regional Administrator Mr. M. D. Orenak, NRR Project Manager- Hatch Mr. D. H. Hardage, Senior Resident Inspector- Hatch State of Georgia Mr. J. H. Turner, Director- Environmental Protection Division

Edwin I. Hatch Nuclear Plant Units 1 and 2 Enclosure Response to Request for Additional Information

Enclosure to NL-16-0660 Response to Request for Additional Information NRC Question The NRC approved use of a full-scope Alternate Source Term pursuant to Title 10 of the Code of Federal Regulations (1 0 CFR) 50.67 at HNP on August 28, 2008, (ADAMS Accession No. ML081770075). Section 50.67(b)(2)(iii) of 10 CFR states that the NRC may issue the amendment only if the applicant's analysis demonstrates with reasonable assurance that:

Adequate radiation protection is provided to permit access to and occupancy of the control room under accident conditions without personnel receiving radiation exposures in excess of 0.05 Sv (5 rem) total effective dose equivalent (TEDE) for the duration of the accident.

To meet 10 CFR 50.67, the radiation dose for accessing the control room must be evaluated from the site boundary to the control room for both ingress and egress for the duration of the accident. The submittal is missing a discussion and/or calculation that accounts for the control room personnel radiation exposure received upon ingress/egress from the site boundary to the turbine building for the duration of the accident. Please provide an analysis of the radiation dose received from accessing the control room in sufficient detail that will enable the NRC staff to be able to perform an independent calculation.

SNC Response A summary of the requested ingress/egress dose calculation (site boundary to turbine building) is provided below. The quantitative dose estimate is < 0.1 REM and bounded by conservatisms in the current AST ingress/egress dose contribution from the turbine building to the main control room. The inputs and assumptions documented below should allow the NRC staff to perform an independent calculation.

It is postulated that the control room operator will exit the plant at 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> post-accident and thereafter make one round trip daily for ingress/egress between the site boundary and the turbine building. During these trips, the operator will be exposed to the following potential sources:

• Direct radiation shine from the reactor building

• Direct radiation shine from the turbine building

• Activity from the reactor and turbine buildings released at ground level

• Activity from the reactor building released through the plant stack To facilitate the dose assessment, the ingress/egress pathway is divided into three legs:

• Site boundary to the parking lot -The driving time is estimated to be 5 minutes.

• Parking lot to the security building - The walking time is estimated to be 6 minutes.

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Enclosure to NL-16-0660 Response to Request for Additional Information

• Security building to the service building annex, which is the entrance to the turbine building - The walking time is estimated to be 4 minutes.

Although the wall thicknesses of the reactor and turbine buildings vary, it is conservatively assumed that all walls have a uniform concrete thickness of 1 foot, 6 inches. The minimum distance from the reactor building to the trip legs ranges from 300 feet (security building) to 1200 feet (parking lot). The minimum distance from the turbine building ranges from 100 feet (security building) to 1000 feet (parking lot). A point-kernel computer program is used to calculate the time-dependent shine dose rate for each leg of the trip and is multiplied by the transit time to yield the shine dose over the duration of the accident.

For the activity releases, the average atmospheric dispersion factors from each ground level and elevated release point to each leg of the trip are calculated for time periods of 24 to 96 and 96 to 720 hours0.00833 days <br />0.2 hours <br />0.00119 weeks <br />2.7396e-4 months <br /> using the ARCON96 computer program. These dispersion factors are then used with the activity released from the reactor and turbine buildings to the environment during each time period and trip transit times to calculate inhalation and immersion doses during each leg of the trip. The operator breathing rate is assumed to be at the maximum value of 3.5E-4 m3/sec for the entire duration of the accident in calculating the inhalation doses.

The resulting doses are as follows:

Site Ingress/Egress Dose (rem TEDE Reactor Turbine Ground Building Building Level Elevated Trip Leg Shine Shine Release Release Total Site Boundary to Parking Lot 3.79E-4 1.3BE-5 1.70E-3 6.17E-4 2.71E-3 Parking Lot to Security Building 3.22E-3 1.31E-4 1.9BE-2 6.05E-4 2.3BE-2 Security Building to Service Building 3.40E-3 1.42E-4 4.07E-2 3.61 E-4 4.46E-2 Annex Total 7.01 E-3 2.86E-4 6.22E-2 1.58E-3 7.11E-2 The previously calculated control operator doses are as follows:

• Control room air- 3.58 rem TEDE

• Ingress/egress through turbine building -1.30 rem TEDE

• Turbine building shine into control room - 0.0059 rem TEDE

• Other external sources- 0.03 rem TEDE

• Total- 4.9 rem TEDE Based on operator walking speed and distance, the transit time for ingress/egress through the turbine building was estimated to be 1.2 minutes per trip. For conservatism, this was rounded up to 2 minutes in calculating the turbine building ingress/egress dose of 1.30 rem TED E. The dose based on a transit time of 1.2 minutes would be as follows:

(1.30 rem TEDE)(1.2/2.0) = 0.78 rem TEDE Hence, the conservatism in the previous turbine building ingress/egress dose was 0.52 rem TEDE (1.30- 0.78). Compared to this, the site ingress/egress dose of 0.0711 rem TEDE is negligible and the previously calculated control room dose of 4.9 rem remains bounding.

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Charles R. Pierce Southern Nuclear Regulatory Affairs Director Operating Company, Inc.

40 Inverness Center Parkway Post Office Box 1295 Birmingham, AL 35242 Tel 205.992.7872 SOUTHER , \

Fax 205.992.7601 NUCLEAR A SOUTHERN COMPANY MAY 1 6 2016 Docket Nos.: 50-321 NL-16-0660 50-366 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D. C. 20555-0001 Edwin I. Hatch Nuclear Plant Units 1 and 2 Response to Request for Additional Information on Secondary Containment Drawdown Time Technical Specifications Amendment Request Ladies and Gentlemen:

By letter dated October 15, 2015, Southern Nuclear Operating Company (SNC) submitted *a license amendment request for Edwin I. Hatch Nuclear Plant (HNP)

Units 1 and 2. The proposed amendment would revise the Unit 1 and 2 HNP Technical Specifications Surveillance Requirement (SA) 3.6.4.1.3 to increase the allowable time for the Standby Gas Treatment System (SGTS) to draw down the secondary containment to the required negative pressure from 2 minutes to 10 minutes.

By letters dated February 18, 2016 and April 15, 2016, the Nuclear Regulatory Commission (NRC) issued requests for additional information (RAis). SNC partially responded to the February 18, 2016 RAI on March 16, 2016 and responded to the April15, 2016 RAI on May 9, 2016.

RAI question #1 from the original February 18, 2016 RAI, dealing with Main Control Room ingress and egress doses, was deferred until 90 days from the date of the RAI. The enclosure to this letter responds to that question, thus completing the response to the February 18,2016 RAI.

This letter contains no NRC commitments.

If you have any questions, please contact Ken McElroy at (205) 992-7369.

U.S. Nuclear Regulatory Commission NL-16-0660 Page2 Mr. C.R. Pierce states he is Regulatory Affairs Director of Southern Nuclear Operating Company, is authorized to execute this oath on behalf of Southern Nuclear Operating Company and, to the best of his knowledge and belief, the facts set forth in this letter are true.

ResCcU/iu~

C. R. Pierce Regulatory Affairs Director CRP/OCV/

d before me this I' I& day ot...L.J11

__ A_,_y_ _ __,, 2016.

D My commission expires: /0 ~!1 ~ 2 oI -1

Enclosures:

Response to Request for Additional Information cc: Southern Nuclear Operating Company Mr. S. E. Kuczynski, Chairman, President & CEO Mr. D. G. Bost, Executive Vice President & Chief Nuclear Officer Mr. D. R. Vineyard, Vice President- Hatch Mr. M. D. Meier, Vice President- Regulatory Affairs Mr. D. R. Madison, Vice President- Fleet Operations Mr. B. J. Adams, Vice President- Engineering Mr. G. L. Johnson, Regulatory Affairs Manager- Hatch RType: CHA02.004 U. S. Nuclear Regulatory Commission Ms. C. Haney, Regional Administrator Mr. M. D. Orenak, NRR Project Manager- Hatch Mr. D. H. Hardage, Senior Resident Inspector- Hatch State of Georgia Mr. J. H. Turner, Director- Environmental Protection Division

Edwin I. Hatch Nuclear Plant Units 1 and 2 Enclosure Response to Request for Additional Information

Enclosure to NL-16-0660 Response to Request for Additional Information NRC Question The NRC approved use of a full-scope Alternate Source Term pursuant to Title 10 of the Code of Federal Regulations (1 0 CFR) 50.67 at HNP on August 28, 2008, (ADAMS Accession No. ML081770075). Section 50.67(b)(2)(iii) of 10 CFR states that the NRC may issue the amendment only if the applicant's analysis demonstrates with reasonable assurance that:

Adequate radiation protection is provided to permit access to and occupancy of the control room under accident conditions without personnel receiving radiation exposures in excess of 0.05 Sv (5 rem) total effective dose equivalent (TEDE) for the duration of the accident.

To meet 10 CFR 50.67, the radiation dose for accessing the control room must be evaluated from the site boundary to the control room for both ingress and egress for the duration of the accident. The submittal is missing a discussion and/or calculation that accounts for the control room personnel radiation exposure received upon ingress/egress from the site boundary to the turbine building for the duration of the accident. Please provide an analysis of the radiation dose received from accessing the control room in sufficient detail that will enable the NRC staff to be able to perform an independent calculation.

SNC Response A summary of the requested ingress/egress dose calculation (site boundary to turbine building) is provided below. The quantitative dose estimate is < 0.1 REM and bounded by conservatisms in the current AST ingress/egress dose contribution from the turbine building to the main control room. The inputs and assumptions documented below should allow the NRC staff to perform an independent calculation.

It is postulated that the control room operator will exit the plant at 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> post-accident and thereafter make one round trip daily for ingress/egress between the site boundary and the turbine building. During these trips, the operator will be exposed to the following potential sources:

• Direct radiation shine from the reactor building

• Direct radiation shine from the turbine building

• Activity from the reactor and turbine buildings released at ground level

• Activity from the reactor building released through the plant stack To facilitate the dose assessment, the ingress/egress pathway is divided into three legs:

• Site boundary to the parking lot -The driving time is estimated to be 5 minutes.

• Parking lot to the security building - The walking time is estimated to be 6 minutes.

E-1

Enclosure to NL-16-0660 Response to Request for Additional Information

• Security building to the service building annex, which is the entrance to the turbine building - The walking time is estimated to be 4 minutes.

Although the wall thicknesses of the reactor and turbine buildings vary, it is conservatively assumed that all walls have a uniform concrete thickness of 1 foot, 6 inches. The minimum distance from the reactor building to the trip legs ranges from 300 feet (security building) to 1200 feet (parking lot). The minimum distance from the turbine building ranges from 100 feet (security building) to 1000 feet (parking lot). A point-kernel computer program is used to calculate the time-dependent shine dose rate for each leg of the trip and is multiplied by the transit time to yield the shine dose over the duration of the accident.

For the activity releases, the average atmospheric dispersion factors from each ground level and elevated release point to each leg of the trip are calculated for time periods of 24 to 96 and 96 to 720 hours0.00833 days <br />0.2 hours <br />0.00119 weeks <br />2.7396e-4 months <br /> using the ARCON96 computer program. These dispersion factors are then used with the activity released from the reactor and turbine buildings to the environment during each time period and trip transit times to calculate inhalation and immersion doses during each leg of the trip. The operator breathing rate is assumed to be at the maximum value of 3.5E-4 m3/sec for the entire duration of the accident in calculating the inhalation doses.

The resulting doses are as follows:

Site Ingress/Egress Dose (rem TEDE Reactor Turbine Ground Building Building Level Elevated Trip Leg Shine Shine Release Release Total Site Boundary to Parking Lot 3.79E-4 1.3BE-5 1.70E-3 6.17E-4 2.71E-3 Parking Lot to Security Building 3.22E-3 1.31E-4 1.9BE-2 6.05E-4 2.3BE-2 Security Building to Service Building 3.40E-3 1.42E-4 4.07E-2 3.61 E-4 4.46E-2 Annex Total 7.01 E-3 2.86E-4 6.22E-2 1.58E-3 7.11E-2 The previously calculated control operator doses are as follows:

• Control room air- 3.58 rem TEDE

• Ingress/egress through turbine building -1.30 rem TEDE

• Turbine building shine into control room - 0.0059 rem TEDE

• Other external sources- 0.03 rem TEDE

• Total- 4.9 rem TEDE Based on operator walking speed and distance, the transit time for ingress/egress through the turbine building was estimated to be 1.2 minutes per trip. For conservatism, this was rounded up to 2 minutes in calculating the turbine building ingress/egress dose of 1.30 rem TED E. The dose based on a transit time of 1.2 minutes would be as follows:

(1.30 rem TEDE)(1.2/2.0) = 0.78 rem TEDE Hence, the conservatism in the previous turbine building ingress/egress dose was 0.52 rem TEDE (1.30- 0.78). Compared to this, the site ingress/egress dose of 0.0711 rem TEDE is negligible and the previously calculated control room dose of 4.9 rem remains bounding.

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