NL-16-0655, Response to Request for Additional Information on Secondary Containment Drawdown Time Technical Specifications Amendment Request

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Response to Request for Additional Information on Secondary Containment Drawdown Time Technical Specifications Amendment Request
ML16130A681
Person / Time
Site: Hatch  Southern Nuclear icon.png
Issue date: 05/09/2016
From: Pierce C
Southern Co, Southern Nuclear Operating Co
To:
Document Control Desk, Office of Nuclear Reactor Regulation
References
NL-16-0655
Download: ML16130A681 (4)
v • d • e


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 SOUTHERN * \

Fax 205.992.7601 NUCLEAR A SOUTHERN COMPANY MAY 0 9 2016 Docket Nos.: 50-321 NL-16-0655 50-366 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D. C. 20555-0001 Edwin I. Hatch Nuclear Plant Unit 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, and as supplemented by letter dated March 16, 2016, Southern Nuclear Operating Company (SNC) submitted a license amendment request for the Edwin I. Hatch Nuclear Plant (HNP), Units 1 and 2.

The proposed amendment would revise 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 (RAJ). The enclosure to this letter provides SNC's response to the April 15, 2016 RAI.

Please note that the remaining SNC response to the NRC RAJ dated February 18, 2016 will be provided to NRC no later than May 18, 2016.

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-16-0655 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.

Respectfully submitted,

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

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Enclosure:

Response to Request for Additional Information cc: Southern Nuclear Operating Company Mr. S. E. Kuczynski, Chairman, President & CEO Mr. D. G. Bast, 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 Regulatorv 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 Unit 1 and 2 Response to Request for Additional Information on Secondary Containment Drawdown Time Technical Specifications Amendment Request Enclosure Response to Request for Additional Information

Enclosure to NL-16-0655 Response to Request for Additional Information

RAI-10

In the response to RAI-7 of the March 16, 2016, supplement, SNC states:

This reduction was justified by noting that wind speeds of greater than 24 mph are not frequent, based on Plant Hatch meteorological conditions. At this wind speed, exfiltration would occur at 0.12 inches of water vacuum.

a) Please provide further detail as to what "exfiltration would occur at 0.12 inches of water vacuum" means. Does it mean that the exfiltration would not occur at 0.125 inches of water vacuum?

b) Please provide the basis for the required 0.12 inches of water vacuum with 24 mph wind speed in the form of a one-page summary of the test or analysis.

SNC Response:

a) The effect of wind blowing on a side of a building will result in positive pressure on that side; this is referred to as the windward side of the building. The opposite side of the building, the leeward side, will be at a negative pressure. The original design consideration of a 35 mph wind will result in a pressure of -0.25 inches of water (wg) on the leeward side.

So, by maintaining a pressure of -0.25 wg inside the building, the differential pressure between the inside of the building and the leeward side of the building will be zero. Consequently, there will be no infiltration or exfiltration to or from the building.

The required pressure with a 24 mph wind speed is determined by the square of the ratio of the 24 and 35 mph wind speeds. Therefore, for a wind speed of 24 mph, the pressure at the leeward side of the building will be:

[(24 mph/35 mph) 2 x (-0.25 inches wg)] =-0.12 inches wg.

This means that if the building is maintained at a pressure which is more negative than -0.12 inches wg there will be no exfiltration from the building, but there will be infiltration, which is acceptable. Hence, if the building is maintained at -0.125 inches wg, corresponding to the 24 mph wind, there will be no exfiltration.

b) As described in the above response to a., the required pressure with a 24 mph wind speed is determined by the square of the ratio of the 24 and 35 mph wind speeds. As described in the RAI response of March 16, 2016, the 24 mph wind speed was used in the original submittal (which reduced the Technical Specification required vacuum from 0.25 inches wg to 0.20 inches wg) because wind speeds in excess of 24 mph are rare at HNP.

E-1

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 SOUTHERN * \

Fax 205.992.7601 NUCLEAR A SOUTHERN COMPANY MAY 0 9 2016 Docket Nos.: 50-321 NL-16-0655 50-366 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D. C. 20555-0001 Edwin I. Hatch Nuclear Plant Unit 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, and as supplemented by letter dated March 16, 2016, Southern Nuclear Operating Company (SNC) submitted a license amendment request for the Edwin I. Hatch Nuclear Plant (HNP), Units 1 and 2.

The proposed amendment would revise 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 (RAJ). The enclosure to this letter provides SNC's response to the April 15, 2016 RAI.

Please note that the remaining SNC response to the NRC RAJ dated February 18, 2016 will be provided to NRC no later than May 18, 2016.

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-16-0655 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.

Respectfully submitted,

~ f{. fJp_

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

q 1?- day ot--'M....:......I.-~---\oo---'

6 2016.

My commission expires: /0

  • 8*do t1

Enclosure:

Response to Request for Additional Information cc: Southern Nuclear Operating Company Mr. S. E. Kuczynski, Chairman, President & CEO Mr. D. G. Bast, 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 Regulatorv 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 Unit 1 and 2 Response to Request for Additional Information on Secondary Containment Drawdown Time Technical Specifications Amendment Request Enclosure Response to Request for Additional Information

Enclosure to NL-16-0655 Response to Request for Additional Information

RAI-10

In the response to RAI-7 of the March 16, 2016, supplement, SNC states:

This reduction was justified by noting that wind speeds of greater than 24 mph are not frequent, based on Plant Hatch meteorological conditions. At this wind speed, exfiltration would occur at 0.12 inches of water vacuum.

a) Please provide further detail as to what "exfiltration would occur at 0.12 inches of water vacuum" means. Does it mean that the exfiltration would not occur at 0.125 inches of water vacuum?

b) Please provide the basis for the required 0.12 inches of water vacuum with 24 mph wind speed in the form of a one-page summary of the test or analysis.

SNC Response:

a) The effect of wind blowing on a side of a building will result in positive pressure on that side; this is referred to as the windward side of the building. The opposite side of the building, the leeward side, will be at a negative pressure. The original design consideration of a 35 mph wind will result in a pressure of -0.25 inches of water (wg) on the leeward side.

So, by maintaining a pressure of -0.25 wg inside the building, the differential pressure between the inside of the building and the leeward side of the building will be zero. Consequently, there will be no infiltration or exfiltration to or from the building.

The required pressure with a 24 mph wind speed is determined by the square of the ratio of the 24 and 35 mph wind speeds. Therefore, for a wind speed of 24 mph, the pressure at the leeward side of the building will be:

[(24 mph/35 mph) 2 x (-0.25 inches wg)] =-0.12 inches wg.

This means that if the building is maintained at a pressure which is more negative than -0.12 inches wg there will be no exfiltration from the building, but there will be infiltration, which is acceptable. Hence, if the building is maintained at -0.125 inches wg, corresponding to the 24 mph wind, there will be no exfiltration.

b) As described in the above response to a., the required pressure with a 24 mph wind speed is determined by the square of the ratio of the 24 and 35 mph wind speeds. As described in the RAI response of March 16, 2016, the 24 mph wind speed was used in the original submittal (which reduced the Technical Specification required vacuum from 0.25 inches wg to 0.20 inches wg) because wind speeds in excess of 24 mph are rare at HNP.

E-1

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