SBK-L-15036, Response to Request for Additional Information for License Amendment Request 11-04, Changes to Technical Specifications for New Fuel Vault

Response to Request for Additional Information for License Amendment Request 11-04, Changes to Technical Specifications for New Fuel Vault

ML15065A029
Person / Time
Site:	Seabrook
Issue date:	02/25/2015
From:	Dean Curtland NextEra Energy Seabrook
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
SBK-L-15036, TAC ME7946, TAC ME8688
Download: ML15065A029 (7)

Text

NExTera ENERGY G February 25, 2015 10 CFR 50.90 SBK-L-15036 Docket No. 50-443 U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555-0001 Seabrook Station Response to Request for Additional Information for License Amendment Request 11-04, Changes to Technical Specifications for New Fuel Vault

References:

1. Seabrook Station License Amendment Request 11-04, "Changes to the Technical Specifications for New and Spent Fuel Storage," SBK-L- 11245, January 30, 2012 (ML12038A036).

2. NRC letter to Seabrook Station, "Seabrook Station, Unit No. I.- Supplemental Information Needed for Acceptance of Requested Licensing Action Regarding License Amendment Request 11-04, Change to Technical Specifications for New and Spent Fuel Storage (TAC No. ME7946)," March 30, 2012 (ML120730270).

3. Seabrook letter to NRC, "Supplement to LAR 11-04, Changes to the Technical Specifications for New and Spent Fuel Storage," SBK-L- 12099, May 10, 2012 (ML12136A126).

4. NRC letter to Seabrook Station, "Seabrook Station, Unit No. 1 - Acceptance Letter Regarding License Amendment Request 11-04, Changes to Technical Specifications for New and Spent Fuel Storage (TAC No. ME8688)," June 19, 2012.

5. NRC letter to Seabrook Station, "Seabrook Station, Unit No. 1 - Request for Additional Information Regarding License Amendment Request 11-04, Changes to Technical Specifications for New and Spent Fuel Storage (TAC No. ME8688)," July 24, 2012 (ML12192A232).

6. Seabrook letter to NRC, "Response to Request for Additional Information Regarding License Amendment Request 11-04, Changes to Technical Specifications for New and Spent Fuel Storage," SBK-L- 12199, September 20, 2012 (ML12271A276).

NeBfa NextEra Energy Seabrook, LLG, P.O. Box 300, Lafayette Road, Seabrook, NHl 03874

U.S. Nuclear Regulatory Commission SBK-L-15036/Page 2

7. NRC letter to Seabrook Station, "Seabrook Station, Unit No. 1 - Request for Additional Information Regarding License Amendment Request 11-04, Changes to Technical Specifications for New and Spent Fuel Storage (TAC No. ME8688)," December 5, 2012 (ML12270A423).

8. Seabrook letter to NRC, "Response to December 2012 Request for Additional Information Regarding License Amendment Request 11-04, Changes to Technical Specifications for New and Spent Fuel Storage," SBK-L- 13061, March 27, 2013 (ML13099A022).

9. Seabrook letter to NRC, "Request for Review and Approval of License Amendment Request (LAR) 11-04, Changes to Technical Specifications for New and Spent Fuel Storage, in Two Parts," SBK-L- 13224, December 20, 2013(ML13360A645).

10. NRC letter to Seabrook Station, "Seabrook Station, Unit No. I - Request for Additional Information for License Amendment Request 11-04, Changes to Technical Specifications for Spent Fuel Storage (TAC No. ME8688)," January 8, 2014.

11. NRC letter to Seabrook Station, "Seabrook Station, Unit No. I - Request for Additional Information for License Amendment Request 11-04, Changes to Technical Specifications for New Fuel Vault (TAC No. MF3283)," January 8, 2014 (ML13268A468).

12. Seabrook letter to NRC, "Response to Request for Additional Information for License Amendment Request 11-04, Changes to Technical Specifications for Spent Fuel Storage,"

SBK-L-14018, January 29, 2014 (ML14035A218).

13. Seabrook letter to NRC, "Response to Request for Additional Information for License Amendment Request 11-04, Changes to Technical Specifications for New Fuel Vault,"

SBK-L-14053, March 13, 2014 (ML14078A057).

14. NRC letter to Seabrook Station, "Seabrook Station, Unit No. 1 - Issuance of Amendment Regarding License Amendment Request Regarding Fuel Storage Changes (TAC No.

ME8688)," September 3, 2014 (ML14184A795).

15. NRC letter to Seabrook Station, "Seabrook Station, Unit No. 1 - Request for Additional Information for License Amendment Request 11-04, Changes to Technical Specifications for New Fuel Vault (TAC No. MF3283)," October 20, 2014 (ML14276A207).

In Reference 1, NextEra Energy Seabrook, LLC (NextEra) submitted License Amendment Request (LAR) 11-04 to the Technical Specifications (TS) for Seabrook Station. The proposed change would revise the TS for new and spent fuel storage as the result of new criticality analyses for the new fuel vault and the spent fuel pool.

In Reference 2, the NRC requested supplemental information to support acceptance of the LAR 11-04. NextEra supplied the information requested in Reference 3. In Reference 4, the NRC accepted LAR 11-04 for review.

In Reference 5, the NRC transmitted their first Request for Additional information on LAR 11-

04. NextEra supplied the information requested in Reference 6.

U.S. Nuclear Regulatory Commission SBK-L-15036/Page 3 In Reference 7, the NRC transmitted their second Request for Additional information on LAR 11-04. NextEra supplied the information requested in Reference 8.

In Reference 9, NextEra requested that the spent fuel storage and new fuel vault segments of LAR 11-04 be treated separately, so that approval of the spent fuel storage segment would not be delayed by the remaining unresolved issues in the new fuel vault segment.

In Reference 10, the NRC transmitted their third Request for Additional information on LAR 11-04 with questions on the spent fuel storage segment. Separately in Reference 11, the NRC transmitted their fourth Request for Additional information on LAR 11-04 with questions on the new fuel vault segment. NextEra supplied the information requested for the spent fuel pool in Reference 12, and for the new fuel vault in Reference 13.

In Reference 14, the NRC issued License Amendment 142 for spent fuel storage.

In Reference 15, the NRC transmitted their fifth Request for Additional information on LAR 11-04 with questions on the new fuel vault segment. The responses to that RAI are provided below in the enclosure to this letter. This response does not modify the changes to the TS as previously proposed and does not alter the conclusion in Reference 1 that the changes do not present a significant hazards consideration.

This letter contains no regulatory commitments.

Should you have any questions regarding this letter, please contact Mr. Michael Ossing, Licensing Manager, at (603) 773-7512.

I declare under penalty of perjury that the foregoing is true and correct.

Executed on February Z5' , 2015.

Sincerely, NextEra Energy Seabrook, LLC Dean Curtland Site Vice President Enclosure

U.S. Nuclear Regulatory Commission SBK-L-15036/Page 4 cc: D. Dorman, NRC Region I Administrator J. Lamb, NRC Project Manager, Project Directorate 1-2 P. Cataldo, NRC Senior Resident Inspector Mr. Perry Plummer Director Homeland Security and Emergency Management New Hampshire Department of Safety Division of Homeland Security and Emergency Management Bureau of Emergency Management 33 Hazen Drive Concord, NH 03305 John Giarrusso, Jr., Nuclear Preparedness Manager The Commonwealth of Massachusetts

-Emergency Management Agency 400 Worcester Road Framingham, MA 01702-5399

ENCLOSURE Response to Request for Additional Information (RAI) for License Amendment Request 11-04, Changes to Technical Specifications for New Fuel Vault

Response to Request for Additional Information (RAI) for License Amendment Request 11-04, Changes to Technical Specifications for New Fuel Vault NRC Question 1. Was there a basis for the 0.4 weight percent hydrogen used as the lower limit in the NFV concrete?

Response

The Seabrook New Fuel Vault (NFV) concrete was constructed with a 3000 psi concrete mixture, consisting of ASTM C 150, Type II Portland cement with a maximum water to cement ratio of 0.50. The course aggregate of the Seabrook NFV concrete is composed of particles of meta-igneous and meta-quartzite rock, while the fine aggregate is primarily made up with quartz with lesser amounts of feldspar, micaceous minerals, chelt, granite, and sand-sized particles of the coarse aggregate. In addition, no fly ash is found in the Seabrook NFV concrete. That concrete composition has a Hydrogen content of 1.0 weight percent. This information on the Seabrook NFV concrete was noted in a previous RAI response (Reference 1.1).

The concrete composition used in the Seabrook NFV criticality analysis is based on Hanford Dry concrete, with 0.4 weight percent Hydrogen. Sensitivity analyses performed and documented in the aforementioned previous RAI response noted that the NFV's reactivity for the optimum moderation case increased when decreasing the Hydrogen content, with negligible impacts for other isotopes or for all isotopes for the fully flooded case. Therefore, the Hanford Dry composition was used in the model as it had a considerably lower Hydrogen content, thus bounding the reactivity calculated with the actual concrete composition.

Reference 1.1 Seabrook letter to NRC, "Response to December 2012 Request for Additional Information Regarding License Amendment Request 11-04, Changes to Technical Specifications for New and Spent Fuel Storage," SBK-L-13061, March 27, 2013.

NRC Question 2. Can the hydrogen content drop over time in the NFV concrete?

Response

Hydrogen is present in concrete in the form of water and hydrogenous reaction products from the chemical reaction between water and cement. The hydrogen content of concrete decreases from the time of placement due to evaporative losses. However, concrete with a hydrogen content of 1.0% could not experience losses that would reduce the hydrogen content to below 0.4%.

Water is present in hydrated cement paste as follows (Reference 2.1):

• Chemically Combined Water - This water is an integral part of the microstructure of cement hydration products and is not lost on drying. For typical portland cement, the chemical reaction resulting in hydration of the cement requires about 1 part (by weight) water for every 4 parts cement (Reference 2.2).

" Interlayer Water - This water is strongly hydrogen bound between layers of hydration products. This water is lost only on strong drying to 11 percent relative humidity.

" Adsorbed Water - This water is close to the solid surface of hydration products and is held to the surface by hydrogen bonding. A major portion of the adsorbed water may be lost when hydrated cement paste is dried to 30 percent relative humidity.

" Capillar Water - This water occupies voids that are larger than about 50 angstroms (50x 10- ° m or 5 nm), and is essentially free from the attractive forces associated with hydration products. Evaporation of capillary water starts to occur when ambient relative humidity is less than 100 percent.

As discussed in the response to question 1, the concrete mix from the NFV has a maximum water-to-cement ratio of 0.5 (i.e., 2 parts water for every 4 parts cement). Because hydration of cement requires about 1 part water for every 4 parts cement, half of the original water content of the NFV concrete is chemically combined in the hydration products and cannot be lost by drying.

Given an original hydrogen content of 1.0%, the hydrogen content associated with chemically bound water is 0.5%. This hydrogen content exceeds the 0.4% hydrogen used in the criticality analyses.

The actual hydrogen content in the concrete will include more than only the chemically bound hydrogen because the interlayer water, adsorbed water, and a portion of the original capillary water will remain in the concrete. The atmospheric conditions at Seabrook Station are sufficiently humid to limit evaporative losses. The National Oceanic and Atmospheric Administration (NOAA) tracks weather data at its monitoring station in Concord, New Hampshire (Reference 2.3). Data for average relative humidity from 1965 to 2012 show an average daily high of 80% and an average daily low of 53%. The least humid month (April) has an average daily low humidity of 44%, which would be the minimum humidity present in the concrete pores. Atmospheric humidity is not low enough to cause evaporation of interlayer water and adsorbed water.

References 2.1 Mehta, P. and Monteiro, P., "Concrete: Microstructure, Properties, and Materials," Fourth Edition. McGraw-Hill Education, 2014.

2.2 Powers, T., "A Discussion of Cement Hydration in Relation to the Curing of Concrete,"

Proceedings of the Highway Research Board, Volume 27, 1947.

2.3 "Comparative Climatic Data For the United States Through 2012," National Oceanic and Atmospheric Administration. Retrieved on February 19, 2015 from website http://wwwl .ncdc.noaa.gov/pub/data/ccd-data/CCD-2012.pdf