ML071280126

Request for Additional Information the Revision of the Licensing and Design Basis with a Full Scope Implementation of an Alternative Source Term

ML071280126
Person / Time
Site:	Hatch
Issue date:	05/30/2007
From:	Martin R NRC/NRR/ADRO/DORL/LPLII-1
To:	Madison D Southern Nuclear Operating Co
Martin R, NRR/DORL, 415-1493
References
TAC MD2934, TAC MD2935
Download: ML071280126 (5)

Text

May 30, 2007 Mr. Dennis R. Madison Vice President - Hatch Edwin I. Hatch Nuclear Plant 11028 Hatch Parkway North Baxley, GA 31513

SUBJECT:

EDWIN I. HATCH NUCLEAR PLANT, UNIT NOS. 1 AND 2 (HNP) - REQUEST FOR ADDITIONAL INFORMATION (RAI) REGARDING ALTERNATE SOURCE TERM APPLICATION (TAC NOS. MD2934 AND MD2935)

Dear Mr. Madison:

By letter to the U.S. Nuclear Regulatory Commission dated August 29, 2006, Southern Nuclear Operating Company, Inc., proposed to revise the HNP, licensing and design basis with a full scope implementation of an alternative source term. We have reviewed your application and have identified a need for additional information on the meteorology of the site as set forth in the Enclosure.

We discussed this issue with your staff on May 29, 2007. Your staff indicated that it plans to submit a response to this issue within sixty (60) days of receipt of this letter.

Sincerely,

/RA/

Robert E. Martin, Senior Project Manager Plant Licensing Branch II-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-321 and 50-366

Enclosure:

RAI cc w/encl: See next page

- ML071280126 *transmitted by email dated OFFICE NRR/LPL2-1/PM NRR/LPL2-1/LA NRR/SCVB/BC NRR/LPL2-1/BC NAME RMartin:nc MOBrien MHart by email EMarinos DATE 05/30/07 05/14/07 05/7/07* 05/30/07 REQUEST FOR ADDITIONAL INFORMATION CONCERNING IMPLEMENTATION OF AN ALTERNATIVE SOURCE TERM FOR EDWIN I. HATCH NUCLEAR PLANT, UNIT NOS. 1 AND 2 (HNP)

1. The Nuclear Regulatory Commission (NRC) staff estimated the following distribution of atmospheric stability in the 1996 through 1998 hourly meteorological data files provided as Enclosure 3 to the November 6, 2006, submittal letter:

Stability A B C D E F G Category Frequency Occurrence 19.9% 3.7% 3.5% 16.5% 29.1% 13.2% 14.1%

The frequency of category D appears to be considerably lower, and categories A, F and G higher, than generally observed for other sites with a 50-meter (m) temperature difference ( -T) interval. This distribution appears to be more similar to measurements made from a smaller -T interval or possibly a temperature sensor less than 10-m above the ground. Please confirm that the category distributions are estimated from -T measurements between the 60-m and 10-m levels and, if so, describe how the data were converted to represent measurements of C/100 meters. If these data are -T measurements made between the 60-m and 10-m levels, what factors contribute to the relatively low occurrence of category D and moderately frequent occurrences of the A, F and G stability category meteorological conditions at the HNP site?

2. Wind speeds measured at the 10-m level from 1996 through 1998 appear to be lighter than generally reported for other sites, than would be estimated by exponential extrapolation of the 60-m measurements to the 10-m level, and in comparison to the early 1970's data presented in Table 2.3-14 of the HNP Final Safety Analysis Report.

NRC staff estimated the 5-percentile 1996 through 1998 10-m measured wind speed to be about 0.4 meters/second (m/s) while extrapolation of the 1996 through 1998 60-m winds result in a 5-percentile 10-m wind speed estimate slightly less than 1 m/s.

Further, the extrapolated 1970's data suggests a 10-m 5-percentile wind speed of approximately 0.7 m/s. Both the 1 m/s and 0.7 m/s estimates are more similar to the 5-percentile 10-m wind speeds reported at other sites. Do you agree that the 5-percentile 1996 through 1998 10-m wind speed measured at HNP was about 0.4 m/s?

If so, what factors contributed to these light winds?

3. Figures 4 and 5 of Enclosure 1 to the November 6, 2006, submittal provide wind roses of the 1996 through 1998 meteorological measurements. Calm winds are listed as having a frequency of occurrence of 0.95% at the 10-m level and 2.05% at the 60-m level. Are calms in this figure defined as winds less than one knot (nautical mile per hour) as suggested by the figure legends? If so, please confirm these estimates.

Based upon the 1996 through 1998 hourly data, NRC staff estimated a frequency of approximately 10% for winds less than one knot at the10-m level and 1% for winds at the 60-m level.

4. Do the control room atmospheric dispersion factors (/Q values) listed in the response to NRC Question 1 of Enclosure 1 of the November 6, 2006, submittal include consideration of /Q values applicable to the main steamline break accident (MSLB) and Enclosure

scenarios involving a loss of offsite power and other single failure? Which /Q values were used to model unfiltered inleakage into the control room and what is the basis for their use?

5. Please justify use of the 10-m and 60-m meteorological data to calculate the control room /Q values for postulated releases from the 101.7-m stack rather than meteorological data measured at the 10-m and 100-m levels. Regulatory Guide (RG) 1.194, "Atmospheric Relative Concentrations for Control Room Radiological Habitability Assessments at Nuclear Power Plants," and NRC Regulatory Issue Summary 2006-04, "Experience with Implementation of Alternative Source Terms," recommend that if wind measurements are available at more than two elevations, the data at the height closest to the release height should be used when running the ARCON96 computer code.

6. NRC staff notes that there are no 0-0.5 hour5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> fumigation /Q values explicitly given for postulated releases from the Hatch stack to the exclusion area boundary (EAB) and low population zone (LPZ). RG 1.183, "Alternative Radiological Source Terms for Evaluating Design Basis Accidents at Nuclear Power Reactors," states that fumigation should be considered where applicable for the EAB and LPZ. For the EAB, the assumed fumigation period should be timed to be included in the worst 2-hour exposure period. Do the elevated release 0-2 hour EAB and LPZ /Q values include fumigation?

If not, why is fumigation considered inapplicable?

Edwin I. Hatch Nuclear Plant, Units 1 & 2 cc:

Laurence Bergen P.O. Box 1295 Oglethorpe Power Corporation Birmingham, AL 35201-1295 2100 E. Exchange Place P.O. Box 1349 General Manager Tucker, GA 30085-1349 Edwin I. Hatch Nuclear Plant Southern Nuclear Operating Company, Inc.

Mr. R. D. Baker U.S. Highway 1 North Manager - Licensing P.O. Box 2010 Southern Nuclear Operating Company, Inc. Baxley, GA 31515 P.O. Box 1295 Birmingham, AL 35201-1295 Mr. K. Rosanski Resident Manager Resident Inspector Oglethorpe Power Corporation Plant Hatch Edwin I. Hatch Nuclear Plant 11030 Hatch Parkway N. P.O. Box 2010 Baxley, GA 31531 Baxley, GA 31515 Harold Reheis, Director Department of Natural Resources 205 Butler Street, SE., Suite 1252 Atlanta, GA 30334 Steven M. Jackson Senior Engineer - Power Supply Municipal Electric Authority of Georgia 1470 Riveredge Parkway, NW Atlanta, GA 30328-4684 Mr. Reece McAlister Executive Secretary Georgia Public Service Commission 244 Washington St., SW Atlanta, GA 30334 Arthur H. Domby, Esq.

Troutman Sanders Nations Bank Plaza 600 Peachtree St, NE, Suite 5200 Atlanta, GA 30308-2216 Chairman Appling County Commissioners County Courthouse Baxley, GA 31513 Mr. Jeffrey T. Gasser Executive Vice President Southern Nuclear Operating Company, Inc.