ML19282B932
| ML19282B932 | |
| Person / Time | |
|---|---|
| Site: | South Texas  |
| Issue date: | 02/26/1979 |
| From: | Parr O Office of Nuclear Reactor Regulation |
| To: | Eric Turner HOUSTON LIGHTING & POWER CO. |
| References | |
| NUDOCS 7903190056 | |
| Download: ML19282B932 (8) | |
Text
's.-
Th&
9 j
UNITED STATES g"
I'g NUCLEAR REGULATORY COMMISSION WAStilNGTON, D. C. 20555 e
"+9.....,o FEB 2 6 G79 Docket Nos. STN 50-498 and STN 50-499 Mr. E. A. Turner Vice President Houston Lighting and Power Company P. O. Box 1700 Houston, Texas 77001
Dear Mr. Turner:
SUBJECT:
REQUEST FOR ADDITIONAL INFORMATION FOR THE REVIEW 0F THE SOUTH TEXAS FINAL SAFETY ANALYSIS REPORT (FSAR)
As a result of our continuing review of the South Texas FSAR, we find that we need additional information to complete our evaluation. The specific information required is in the area of meteorology and is listed in the Enclosure.
To maintain our licensing review schedule for the South Texas FSAR, we will need responses to the enclosed request by May 21, 1979.
If you cannot meet this date, please inform us within seven days after receipt of this letter of the date you plan to submit your responses so that we may review our schedule for any necessary changes.
Please contact us if you desire any discussion or clarification of the enclosed request.
Sincerely, OL la. (L (Ilan D. Parr, Chief Light Water Reactors Branch No. 3 Division of Project Management
Enclosure:
As Stated cc w/ enclosure:
See next page 79031000Sb
I Mr. E. A. Turner FEB 2 61979 cc:
Mr. D. G. Barker Mr. Troy C. Webb Manager, South Texas Project Assistant Attorney Ceneral Houston Lighting and Power Company Environmental Protection Div.
P. O. Box 1700 P. O. Box 12548 Houston, Texas 77001 Capitol Station Austin, Texas 78711 Mr. M. L. Borchelt Central Power and Light Company Mr. R. Gordon Gooch, Esq.
P. O. Box 2121 Baker & Botts Corpus Christi, Texas 78403 1701 Pennsylvania Avenue, N.W.
Washington, D. C.
20006 Mr. R. L. Hancock City of Austin Director, Governcr's Budget Electric Utility Department and Planning Office P. O. Box 1088 Executive Office Building Austin, Texas 78767 411 W. 13th Street Austin, Texas 78701 Mr. J. B. Poston Assistant General Manager for Operations City Public Service Board P. O. Box 1771 San Antonio, Texas 78296 Mr. Jack R. Newman, Esq.
Lowenstein, Newman, Axelrad & Toll 1025 Connecticut Avenue, N. W.
Washington, D. C.
20036 Mr. Melbert Schwarz, Jr., Esq.
Baker & Botts One Shell Plaza Housten, Texas 77002 Mr. G. Hohmann Westinghouse Electric Corporation P. O. Box 355 Pittsburgh, Pennsylvania 15230 Mr. E. R. Schr.idt NUS Corporation NUS-4 Research Place Rockville, Maryland 20850 Mr. J. H. Pepin Brown & Root, Inc.
P. O. Box 3 Houston, Texas 77001 S
ENCLOSURE REQUEST FOR ADDITIOf1AL IflFORMATI0fl FOR THE REVIEW OF THE FSAR C09 THE SOUTH TEXAS PROJECT, UrlITS 1 A510 2
372-1 372.0 METEOROLOGY.
372.19 The response to Request No. 372.3 states that "The STP design basis (2.3) maximum and minimum outside ambient temperatures are 96*F and 29'F, respectively." Climatological dats presented in Tables 2.3-14 through 2.3-20 indicate an observed maximum temperature of 110*F at Victoria, witt. observed extreme maximum temperatures ranging from ICl*F to 105*F at other climatological stations in the area. Temperatures in excess of 90*F may be expected on an average of about 100 days each year. Similarly, an extreme minimum temperature of 8 F has been observed at Galveston, with observed extreme minimum temperatures ranging from 9'F to 13*F at other climatological stations in the area. Temperatures of 32 F or lower may be expected on an average of about 10 days each year.
Provide further justification of the selected design basis maximum and minimum ambient air temperatures considering that extreme temperatures observed in the area are significantly different than the selected design basis values. Also discuss the effects on safety-related systems and components resulting from persistent (e.g., on the order of several hours) temperatures significantly different than the selected design basis values.
372-2 372.20 The response to Request No. 372.18 does not clarify the inconsistency (2.3) in the FSAR concerning the bases for selection of a design wind velocity for the STP site. Section 2.3.1.2.1, Extreme Winds, and Table 2.3-3 clearly indicate that the " fastest-mile" wind speed at 30 feet above the ground with a 100-year recurrence interval is 125 mph for the STP site, and that this value multiplied by a gustiness factor of 1.3 results in "the highest instantaneous gust expected once in 100 years is 163 mph, based on a composite of Corpus Christi, Galveston, and Victoria data" (page 2.3-3).
This appears to be an appropriate basis for the selection of the design wind velocity identified in Section 3.3.1.
However, in Section 2.3.1.2.6, Tropical Stoms and Hurricanes, it is stated that an " examination was made of data in the site area which showed that 120 :ph was the maximum credible recorded sustained wind speed in the vicinity of tne site." Section 3.3.1 identifies a design wind velocity of 120 mph. Regulatory Guide 1.70, " Standard Format and Content of Safety Analysis Reports for Nuclear Power Plants,"
states that the design wind velocity should be based on the " fastest mile" wind speed with a return period of 100 years, not the
" maximum credible recorded sJstained wind speed." Clarify the discrepancy between the design wind velocity based on the discussion of extreme winds in Section 2.3.1.2.1 and the design wind velocity identified in Section 3.3.1 based on the statements in Section
- 2. 3.1. 2. 6. There may be some confusion between the definition of
" fastest mile" and " sustained" wind speeds.
372-3 372.21 The annual frequencies of occurrence of moderately stable and (2.3) extremely stable conditions (Pasquill types "F" and "G",
respectively) are very important in the determination of relative concentration (X/Q) values to be used in assessing the conse-quences of design basis accidents. A significant decrease (about 6%) in the annual frequency of extremely stable conditions at Victoria was observed for the period July 1973 through June 1977 (Table 2.3-12) compared to the annual frequency of these conditions observed for the period September 1953 through August 1958 (Table 2.3-11), particularly during the sumer and fall seasons.
Discuss possible explanations for this decrease in the occurrence of extremely stable conditions at Victoria, and discuss the sig-nificance of this decrease on the representativeness and conscr-vatism of the onsite data collected during the period July 1973 through September 1977.
372.22 A preliminary examination of onsite data for the period July 21, 1973 (2.3) through September 30, 1977, provided on magnetic tape, indicates an inordinate number of occurrences of mcderately unstable (Pasquill type "B") conditions defined by the vertical temperature gradient measured between the 10m and 30m levels. Although this interval of tempe ature gradient measurement is not the primary source of atmospheric stability infonnation, the distribution of atmospheric stability conditions defined for this interval should genera;1y resemble the distribution of stability conditions defined
- ^
372-4 372.22 by the measurement of vertical temperature gradient between the (2.3)
(Cont'd) 10m and 60m levels. Discuss the differences in the distribution of atmospheric stability conditions defined by these two intervals of measurement and indicate if problems with the data collection program are suspected.
372.23 Table 2.3-24 indicates 98.5% data recovery for joint frequency (2.3) distributions of wind speed and wind direction (measured at the 10m level) by atmospheric stability (defined by the measurement of vertical temperature gradient between the 10m and 50m levels) for the period July 21,1973 - July 20,1977. However, the data recovery for the vertical temperature gradient measurement was 97.4%. Data recovery for the joint frequency distributions cannot exceed 97.4% assuming all outages of wind speed and/or wind direction measurements occurred concurrently with the outages of temperature gradient measurement. The response to Request No. 372.13 states that
" data were not substituted from other levels to enhance data recovery." Explain how the data recovery estimates in Table 2.3-24 were determined.
372.24 During plant operation, the onsite meteorological tower should (2.3) provide measurements of wind speed, wind direction, and atmospheric stability for estimates of atmospheric dispersion conditions from the point of release to the exclusion area boundary and LPZ dis-tances during and following accidental and routine releases.
372-5 372.24 Meteorological measurements, particularly wind speed and vertical (2.3)
(Cont'd) temperature gradient, it the present tower location during winds from the south clockwise through south-southwest could be used to provide non-representative or misleading estimates of atmos-pheric dispersion, during and following accidental and routine releases, because of the long over-water fetch for airflow from these directions Discuss the representativeness of the locatien*cf the onsite meteorciogical tower for describing atmospheric dispers.'on conditions from the point of release to the exclusion area boundary and LPZ distances, with particular attention to measure-ments of wind speed and vertical temperature gradient when winds are from the south clockwise through south-southwest directions.
Indicate if the monitoring program identified in the response to Request No. 372.6 will be used to evaluate the representativeness of measuretaents at the current tower location.
372.25 The control room display of meteorological parameters will include (2.3) utilization of the Unit 1 and Unit 2 computers for CRT display or digital print-out. The response to Request No. 372.8 ind.' cates a significant reliance (32.7%) on the analog data recording system for the period January-September 1977.
Discuss the problems encountered in the digital data recording system :nd indicate if these difficulties would impair the reliability of the control room access to meteorological infonnation.
.