ML100610148

Preliminary RAIs for FSAR Section 2.3

ML100610148
Person / Time
Site:	Watts Bar
Issue date:	03/01/2010
From:	Joel Wiebe Watts Bar Special Projects Branch
To:	Mccarthy J Tennessee Valley Authority
Wiebe, Joel NRR/DORL/WBSP, 415-6606
References
Download: ML100610148 (3)

Text

FACSIMILE TRANSMITTAL TO: Joseph McCarthy Joel Wiebe, Sr. Project COMPANY: DATE: Tennessee Valley Authority 3/1/2010 FAX NUMBER: TOTAL NO. OF PAGES INC. COVER: (423) 365-3833 3 PHONE NUMBER: SENDER'S REFERENCE NUMBER: (423) 365-3251 D URGENT D FOR REVIEW D PLEASE COMMENT D PLEASE REPLY NOTES/COMMENTS:

For discussion

-Preliminary RAls for FSAR Section 2.3 REQUEST FOR ADDITIONAL WATTS BAR, UNIT FINAL SAFETY ANALSIS REPORT, AMENDMENT SECTION 2.3, DOCKET NO. Nuclear Regulatory Commission (NRC) staff noted that only some of the meteorological information in Amendment 94 appeared to be updated when compared with prior Watts Bar, Unit 2, Final Safety Analysis Report (FSAR) amendments.

Provide additional information regarding what criteria were used to determine which meteorological parameters and associated analyses should be updated. Please provide an assessment of the Watts Bar, Unit 2, design bases and safety structures, systems and components potentially impacted by meteorological phenomena and how they could be impacted.

Include a discussion to confirm that all relevant meteorological parameters and analyses were examined and updated, if appropriate.

This should include consideration of changes in the limiting values resulting from, 1) the addition of recently measured data to the compiled historic climate data base and, 2) resultant changes in locations that are found to be more limiting than those locations identified in prior FSAR amendments. In several cases, it appears that changes in tables were highlighted, but the text discussing the table or an analysis using the information in the table does not appear to have been revised. Provide additional information regarding what criteria were used to determine when the text should be revised, if a table had been revised. For example, NRC staff notes that the annual occurrence of fog at Oak Ridge, Tennessee (TN), as presented in Table 2.3-12 is considerably greater than suggested in the text of Section 2.3.2.2, which was not annotated with a change bar in the margin. In several cases, it appears that the period of record for extreme values has been changed to a more recent period, rather than appending the more recent period to the longer historic period cited in prior FSAR amendments.

Provide additional information regarding what criteria were used to determine which historic extreme weather data should be removed from consideration rather than using the entire historic period of record. In Section 2.3.1.3, the period of record of the single tornado occurrence in Rhea County in which Watts Bar, Unit 2, is located has been updated. However, it appears that the reference citation does not include the full period discussed in the text. Further, calculation of the probability that a tornado will strike the Watts Bar site is based on data of tornado occurrences between 1950 and 1986 in a 30 nautical mile radius area centered at the onsite meteorological tower and the track of the single tornado that is recorded to have occurred in Rhea County. Please provide additional information describing whether the analysis in Amendment 94 is limiting with respect to reported tornado occurrences subsequent to 1986 and areas neighboring Rhea County. Updated wind speed values for high winds in Section 2.3.1.3 refer to the fastest mile of wind, but data in the references cited in the Section 2.3.1.3 text are reported as 3-second gust wind speeds. Please discuss this apparent discrepancy.

How does the more recent data provided in Amendment 94 compare with the historic fastest mile wind speed data in prior FSAR amendments?

Enclosure

-2Section 2.3.2.2 states that the mean minima temperature for both Chattanooga and Dayton, TN, ranged from about 24° F to about 74° F for Dayton and 75° F for Chattanooga based upon data measured between 1971 -2000. How do values in Tables 2.3-2 and 2.3-3 support these estimates?

With regard to extreme minima temperature values recorded in the Watts Bar area, NRC staff noted that measurements made at three other National Oceanic and Atmospheric Administration (NOAA) Climate Division TN 1 locations, Knoxville, Sevierville, and Tazewell, TN, were reported as -24 ° F in NOAA "Climatography of the United States 1\10. 20," summaries.

This value is more limiting than the -15 ° F minima cited for Dayton in Table 2.3-2. Given that these locations are all within Climate Division TN 1, please describe why the use of the Dayton minima is acceptable although it has been exceeded at at least three other locations in the same climatic region as Dayton. Please note the following editorial clarifications and make changes as appropriate: It appears that the reference to "Decatur" in Section 2.3.2.2 should be to "Dayton," based on information provided in Table 2.3-2. The reference list and/or citations in the text may not have been properly updated in all cases. For example, the discussion of tornadoes in Section 2.3.1.3 stateS that data from 1916 -2008 were considered, but the latest date of the three listed references is 1989. Reference 13 regards climatic data at Dayton, TN, but the citation in Section 2.3.1.3 discusses Chattanooga and Knoxville, TN. In Table 2.3-1 the December, January and February thunderstorm day frequency values for Knoxville appear to be printed on a single line, with no entries on the lines for January and February.

Also, is the footnote reference to Knoxville, TN, data essentially the same as for the Chattanooga, TN, data, except for Knoxville? One or more of the values cited in Tables 2.3-5 and 2.3-6 appear to be different than values given in the cited references. The period of record for the data in Table 2.3-7 appears to be the 30 year normal for 1971 -2000 rather than 1979 -2008. What reference does the superscript "b" footnote? Table 2.3-12 provides two periods of record for each of three locations, a 30-year interval from 1979 -2008 and a second period of record of a specified number of years (e.g., 45 years). Provide additional information to explain how these two periods of record are correlated for each location when they appear to be of different durations.