SEP-24-02 02:09 PM WEnTHER-COMMAND 708 Z55 0478 P.02 LL L - - Murray and Trettel Inc. Certified Consulting Meteorologists CP&L, a Progress Energy Company Attn: Mr. Paul Snead P.O. Box 1551 411 Fayetteville Street Mall Raleigh, NC 27602 September 23, 2002 Dear Paul: Murray and Trettel has prepared a draft of an update of the meteorological portion of the FSAR for the H.B. Robinson Nuclear plant for your review. Murray and Trettel has provided updated information for both the ontite data and the National Weather Service data that was included in the previous report. The following is a brief synopsis of a comparison of the current FSAR and the draft update. A review of the general climate of the region produced little change from the previous report. Minor variations did exist, however these would likely have no impact on the plant. Some of the minor variations included the fact that length of the growing season had been reduced by one day. Also, the average date of the last spring occurrence of a 24 degree Fahrenheit temperature was one day earlier and the average date of the first fall occurrence of 24 degrees was three days later. Again, very consistent with the earlier report. The average number of thunderstorm days per year had decreased by one or two days per year. The average number of fog days had also decreased by one day per year. Using new 30 year normals (1971 through 2000) from the same National Weather Service sites that were utilized in the previous report, the following was found when the old FSAR meteorological information was compared to the new: 1. Temperatures were slightly higher (less than 1 degree Fahrenheit). 2. Slightly higher annual precipitation (approximately 1 inch per year). 3. Dew points showed little change. 4. Relative humidities were very similar in the new report as compared to the old. 414 West Frontage Road Northfield, Illinoli 60093 Phones: 847 446 7800 Chicago: 773 273 5600
LL L - - Murray and Trettel Inc. Certified Consulting Meteorologists
CP&L, a Progress Energy Company Attn: Mr. Paul Snead P.O. Box 1551 411 Fayetteville Street Mall Raleigh, NC 27602
September 23, 2002
Dear Paul:
Murray and Trettel has prepared a draft of an update of the meteorological portion of the FSAR for the H.B. Robinson Nuclear plant for your review. Murray and Trettel has provided updated information for both the ontite data and the National Weather Service data that was included in the previous report. The following is a brief synopsis of a comparison of the current FSAR and the draft update.
A review of the general climate of the region produced little change from the previous report. Minor variations did exist, however these would likely have no impact on the plant. Some of the minor variations included the fact that length of the growing season had been reduced by one day. Also, the average date of the last spring occurrence of a 24 degree Fahrenheit temperature was one day earlier and the average date of the first fall occurrence of 24 degrees was three days later. Again, very consistent with the earlier report.
The average number of thunderstorm days per year had decreased by one or two days per year. The average number of fog days had also decreased by one day per year.
Using new 30 year normals (1971 through 2000) from the same National Weather Service sites that were utilized in the previous report, the following was found when the old FSAR meteorological information was compared to the new:
1. Temperatures were slightly higher (less than 1 degree Fahrenheit).
2. Slightly higher annual precipitation (approximately 1 inch per year).
3. Dew points showed little change.
4. Relative humidities were very similar in the new report as compared to the old.
5. The parameter that did have, in some cases, significant differences between the old data and the new was extreme precipitation events (this was not found to be true at the plant site). Maximum 24 hour rainfall at RaleighDurham and Charlotte had increased slightly (by less than 1/4 inch at both locations. The maximum monthly precipitation had increased by nearly 9 inches at Raleigh and by less than 3/4 of an inch at Columbia. The maximum 24 hour and monthly snowfall had also increased significantly at Raleigh. The monthly maximum snowfall at Raleigh increased from 17.2 inches to 25.8 inches (in January, 2000) and the 24 hour maximum snowfall at Raleigh increased from 10.4 to 17.9 inches of snow in January, 2000.
The hurricane data was updated through 2001. No major impacts on the plant site occurred with the addition of 12 years of hurricane data.
The average annual wind speed at the National Weather Service sites showed little change from the previous report. Charlotte decreased by only .1 mile per hour from 7.5 to 7.4 miles per hour. Columbia showed the same change from 6.9 to 6.8 miles per hour.
The Florence, South Carolina joint frequency tables of wind speed, wind direction and stability were updated to include the six year period of 1991 through 1996. The percentage of occurrence of each stability category was very similar as compared to the previous report which utilized data from the years 1960 to 1964. The only appreciable difference was an increase in percent occurrence of the D stability category. This same increase was also evident in the onsite data for the same period. The D stability category percentage increased from 40 to 46%. The onsite data showed a 7% increase in the frequency of the D stability category.
The earlier FSAR :report stated that stable and extremely stable conditions occur more frequently onsite than they do at Florence. The more recent data does not- support this statement. The -stable and extremely stable frequencies at the two sites (H.B. Robinson and Florence) are very similar.
The onsite data indicated an increase of approximately 1 degree Fahrenheit of the mean temperature. The mean maximum and minimum temperatures also showed an increase of approximately one degree. The onsite dew point increased by 2.2 degrees Fahrenheit.
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SEP-24-02 02:10 PM WEATHER-COMMRHD
Page 3
The onsite average wind speed decreased from 6.2 to 4.7 miles per hour. Differing time periods, averaging methods, and instrumentation account, in part for the lower onsite wind speed value.
The onsite six year precipitation average was more than 5 inches per year greater than the six year period utilized in the previous report (1976 through 1981). The previous study incorporated three relatively very dry years (1977, 1980 and 1981) in the six year average. None of the 1 hour, 6 hour, 12 hour or 24 hour precipitation events had occurred onsite that were greater than those included on the previous report.
The previous joint frequency tables utilized onsite data from 1976 through 1981. The new stability joint frequency tables use data from 1991 through 1996. Stability categories B, C, E, F and G frequencies were very similar when comparing the two time periods. Stability category A occurred approximately 6 1/2 percent less frequently from 1991 through 1996 as compared to 1976 to 1981. Stability category D showed an increase in frequency of roughly 7 percent. This shift from unstable to neutral was also evident in the Florence data. The Florence data also covered the years 1991 through 1996.
The wind tables indicate the same bimodal northeast/southwest wind directions indicated in the previous study.
The dominant and least common wind directions for each stability category were reviewed and a comparison between the old data and the new was performed. The comparison was performed for both the 11 meter and the 61 meter wind sensor heights. For almost every stability category at each height, the most common and least common wind directions were almost identical when the old tables were compared to the new. The only differences moved the most common or least conmon wind directions for a particular stability category by only one wind direction compass point (the joint frequency tables utilize 16 compass points).
Murray and Treettel was not asked to update the Chi/Q tables at the end of the- FSAR. We have-however provided an updated table to replace table 2.3.4-1 which provides stability distribution by season. This table is based upon the 1991 through 1996 onsite data utilized in preparing the FSAR update draft.
Meteorologists at Murray and Trettel have compared the data between the existing FSAR and the draft update version. Although minor variations exist, the meteorologists feel that the data provided with the draft update is consistent with the current version and that no major discrepancies exist.
[ lIII Mu irry nrid Trollol Inc. Certiflod Ctisulling M,,ooroloc;rsir
708 5X5 0478 P. 04
SEP-24-02 02:10 PM WEATHER-COMMAND 708 5z5 0478 t" II
Page 4
If you have any questions concerning the draft or this review,
please call Mark Carroll at 847-446-7800, extension 130.
Sincerely,
Mark T. Carroll Director - Environmental Applications Division
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j, N,
CP&L, a Progress Energy Company Attn: Mr. Paul Snead P.O. Box 1551 [ 411 Fayetteville Street Mall Raleigh, NC 27602
September 23, 2002
Dear Paul:
Murray and Trettel has prepared a draft of an update of the meteorological portion of the FSAR for the H.B. Robinson Nuclear plant for your review. Murray and Trettel has provided updated information for both the onsite data and the National Weather Service data that was included in the previous report. The following is a brief synopsis of a comparison of the current FSAR and the draft update.
A review of the general climate of the region produced little change from the previous report. Minor variations did exist, however these would likely have no impact on the plant. Some of the minor variations included the fact that length of the growing season had been reduced by one day. Also, the average date of the last spring occurrence of a 24 degree Fahrenheit temperature was one day earlier and the average date of the first fall occurrence of 24 degrees was three days later. Again, very consistent with the earlier report.
The average number of thunderstorm days per year had decreased by one or two days per year. The average number of fog days had also decreased by one day per year.
Using new 30 year normals (1971 through 2000) from the same National Weather Service sites that were utilized in the previous report, the following was found when the old FSAR meteorologicalinformation was compared to the new:
1. Temperatures were slightly higher (less than 1 degree Fahrenheit).
2. Slightly higher annual precipitation (approximately 1 inch per year).
3. Dew points showed little change. r
4. Relative humidities were very similar in the new report as compared to the old.
Page 2
'�
1
5. The parameter that did have, in some cases, significant differences between the old data and the new was extreme precipitation events (this was not found to be true at I the plant site). Maximum 24 hour rainfall at Raleigh- i Durham and Charlotte had increased slightly (by less thant 1/4 inch at both locations. The maximum monthly precipitation had increased by nearly 9 inches at Raleigh! and by less than 3/4 of an inch at Columbia. The maximuml 24 hour and monthly snowfall had also increased significantly at Raleigh. The monthly maximum snowfall at Raleigh increased from 17.2 inches to 25.B inches (in January, 2000) and the 24 hour maximum snowfall at Raleigh increased from 10.4 to 17.9 inches of snow in January, 2000.
The hurricane data was updated through 2001. No major impacts on the plant site occurred with the addition of 12 years of hurricane data.
The average annual wind speed at the National Weather Service sites showed little change from the previous report. Charlotte decreased by only .1 mile per hour from 7.5 to 7.4 miles per hour. Columbia showed the same change from 6.9 to 6.8 miles per hour.
The Florence, South Carolina joint frequency tables of wind speed, wind direction and stability were updated to include the six year period of 1991 through 1996. The percentage of occurrence of each stability category was very similar as compared to the previous report which utilized data from the years 1960 to 1964. The only appreciable difference was an increase in percent occurrence of the D stability category,.f"ThŽs same increase was also evident in the onsite data for the same period. The D stability category percentage increased from 40 to 46%. The onsite data showed a 7% increase in the frequency of the D stability category.
The earlier FSAR report stated that stable and extremely stable conditions occur more frequently onsite than they do at Florence. The more recent data does no support this statement. The stable and extremely stable frequencies at the tvRT sites (H.B. Robinson and Florence) are very similar.
The onsite data indicated an increase of approximately 1 degree Fahrenheit of the mean temperature. The mean maximum and minimum temperatures also showed an increase of approximately one degree. The onsite dew point increased by 2.2 degrees Fahrenheit. The slight increase in temperature and dew point is consistent with many theories on climate change.
r-
Page 3
The onsite average wind speed decreased from 6.2 to 4.7 miles per
i.:'. ru
hour. Differing time periods, averaging methods, and instrumentation account, in part for the lower onsite wind speed value.
The onsite six year precipitation average was more than 5 inches per year greater than the six year period utilized in the previous, report (1976 through 1981). The previous study incorporated threerelatively very dry years (1977, 1980 and 1981) in the six year average. None of the 1 hour, 6 hour, 12 hour or 24 hour precipitation events had occurred onsite that were greater than those included on the previous report.
The previous joint frequency tables utilized onsite data from 1976t, through 1981. The new stability joint frequency tables use data from 1991 through 1996. Stability categories B, C, E, F and G frequencies were very similar when comparing the two time periods. Stability category A occurred approximately 6 1/2 percent less frequently from 1991 through 1996 as compared to 1976 to 1981. Stability category D showed an increase in frequency of roughly 7 percent. This shift from unstable to neutral was also evident in the Florence data. The Florence data also covered the years 1991 through 1996.
The wind tables indicate the same bimodal northeast/southwest wind directions indicated in the previous study.
The dominant and least common wind directions for each stability category were reviewed and a comparison'between the old data and the new was performed. The comparison was performed for both the 11 meter and the 61 meter wind sensor heights. For almost every stability category at each height, the most common and least common wind directions were almost identical when the old tables were compared to the new. The only differences moved the most common or least common wind directions for a particular stability category by only one wind direction compass point (the joint frequency tables utilize 16 compass points).
Murray and Trettel was not asked to update the Chi/Q tables at the end of the FSAR. We have however provided an updated table to replace table 2.3.4-1 which-provides stability distribution by season. This table iB-based upon the 1991 through 1996 onsite data utilized in preparing the FSAR update draft.
Meteorologists at Murray and Tre tel have cofijpared the data between the existing FSAR and the draft update version. Although minor variations exist, the meteorologists feel that the data provided with the draft update is consistent with the current version and that no major discrepancies exist.
Page 4
If you have any questions concerning the draft or this review, please call Mark Carroll at 847-446-7800, extension 130.
Sincerely,
X ~ p'
Mark T. Carroll Director - Environmental Applications Division
I .• . ,' e..&.•
HER 2 UPDATED FSAR • ,
2.3 METEOROLOGY 2.3.1 REGIONAL CLIMATOLOGY 2.3.1.1 General Climate
The H. B. Robinson site lies in the transition zone delineating the Piedmont and Coastal Plain of South Carolina. The climatology of South Carolina largely depends on elevation above sea level and distance from the Atlantic Ocean and the Appalachian Mountain chain. At an elevation of about 225 feet above mean sea level and a distance of about 160 miles from the Appalachian Mountains the site has a temperate climatic regime. Stations representing the regional climatology their locations with respect to the site area, and their elevations above mean sea level are presented in Table 2.3.1-1.
Long summers are prevalent with warm weather usually lasting from May into September. In summer the Bermuda high is the greatest single weather factor influencing the area. This permanent high more or less blocks the entry of cold fronts so that many stall before reaching central South Carolina. Also, the southwestern flow around the off shore Bermuda high pressure supplies moisture for the many summer thunderstorms. There are relatively few breaks in the heat during the midsummer. The typical summer has about six days with temperatures of 100OF or more. Thundershower activity usually shows a decided increase during June, decreasing about the first of September. Summer is the rainiest season of the year contributing about 33 percent of the annual total. The summer rains are largely in the form of local thundershowers. About once or twice a year affects of a passing tropical storm are felt in the form of strong winds and heavy rains. The incidence of these storms is greatest in September, although they represent a possible threat from midsummer to late fall. Damage from tropical storms is usually minor in the HBR area.
Fall is the most pleasant time of the year. Rainfall during the late fall is at an annual minimum, while the sunshine is at a relative maximum. About 20 percent of the annual rainfall is recorded during the fall. Winters are mild with the cold weather usually lasting from late November to mid-March. However, only about one-third of the days in this period have minimum temperatures below freezing. The winter weather around the HBR site is largely made up of polar air outbreaks that reach this area in a much modified form. On rare occasions in winter, Arctic air masses push southward as far as central South Carolina and cause some of the coldest temperatures.'Disruption of activities from snowfall is unusual; in fact, more than three days of sustained snow cover is rare. A day or more with snowfall is probable during nine out of eleven winters. A day with more than one inch of snowfall is likely to occur in one out of five winters. The average winter has five days with temperatures of 20°F or below. Temperatures below 10OF are rare; occurrences average about one per four winters. There are two to five cold waves during the winter. The winter rainfall is about 22 percent of the annual total.
Spring is the most changeable season of the year. The temperature varies from an occasional cold snap in March to generally warm and pleasant in May. While tornadoes are infrequent, they occur most often in the spring. Hailstorms are not frequent, with the annual incidence at a maximum in spring and early summer. The spring rainfall represents 25 percent of the annual total.
2.3.1-1
H-BR 2 UPDATED FSAR
The average date of the last spring freeze is March 31, and the average date of the first fall freeze is November 3, or a growing period of 217 days. Temperatures of 32°F or below have occurred as late as April 24 and as early as October 4. The average date of the last spring occurrence of 24°F is February 24, while the average date of the first fall occurrence of 24°F is November 29. More than 1,530 hours below 45°F per winter are probable once in ten years, while more than 930 hours may occur nine out of ten winters.
2.3.1.2 Regional Meteorological Conditions for Desigrn and Operating Bases
2.3.1.2.1 Tornadoes
The H. B. Robinson site lies within the defined Type I region for
classification of tornadoes, according to the WASH 1300 document (Reference 2.3.1--1). The region I has defined associated tornado characteristics as follows:
Maximum Windspeed: 360 mph Rotational Windspeed: 290 mph Translational Speed 70 mph maximum, 5 mph minimum Radius of Maximum Rotational Speed: 150 feet Pressure Drop 30 psi Rate of Pressure Drop 2.0 psi/second
Calculations of the ornado strike probability is accomplished by the following equation:
P,= n WaA) (I)
Where:2
Pe = Probability that a tornado will strike a particular location during a one-year interval.
n = Average number of tornadoes per year, e q ual to 2.69 for the HBR site area (Reference 2.3.1-h2).
a = Average individual tornado area, equal to 2.82 square miles for the HBR site area (Reference 2.3.1-2).
A = Total area of concern (e.g., 1t square with 35W 30o mid/latitude)
equal to 3891.15 square miles.
Using these parameters, P is equal to .001950 or stated conversely, a return
period of 513 years. Consequently, one would expect a tornado strike every 513 years. Since the H. B. Robinson lake is very narrow in comparison to the length, this body of water would most likely be incapable of sustaining waterspouts; therefore, they need not be considered.
2.3.1.2.2 Thunderstorms
Charlotte, Raleigh-Durham and Columbia have a mean total of 40, 44, and 52 thunderstorm days per years respectively (References 2.3.1-3 through 2.3.1-5).
2.3.1-2
HBR 2 UPDATED FSAR
The distribution by month is presented in Table 2.3.1-2. July has the most thunderstorms; these occur mainly in the afternoon and evening and most frequently they are the scattered, air-mass type. This provides variable precipitation patterns; on the average, there is one thunderstorm every third day in July. Thunderstorms which occur in the autumn through spring period are usually the result of frontal activity, rather than the result of the convective heating process that prevails during the summer months.
2.3.1.2.3 Lightning
Three kinds of lightning occur in thunderstorms: cloud-to-cloud, in-cloud, and cloud-to-ground. Although cloud-to-cloud and in-cloud strokes outnumber cloudto-ground strokes by about two to one (Reference 2.3.1-6), cloud-to-ground strokes present the only hazard to nuclear power plant safety. Table 2.3.1-3 presents the annual and seasonal frequencies of cloud-to-ground flashes for Charlotte, Raleigh-Durham, and Columbia (latitude variations excluded). These frequencies are calculated with a technique outlined by Marshall (Reference 2.3.1-7) by using the following equation:
N = (0.1 + 0.35 sin 0 )(0.40 ± 0.20) (2) E
Where:
N = Number of flashes to earth per thunderstorm day per square E kilometer.
0 = Geographical latitude of the HBR site equal to 340 24.2'.
Using the conservative estimate of 0.40 + 0.20 (equaling to 0.60) in the above equation, the site area N equals to 0.179 flashes per thunderstorm day per square kilometer. E
2.3.1.2.4 Hail ... ,,
Hail is an indication of strong vertical velocities that occur in severe thunderstorms. Storms reaching hail severity stage are mostly associated with strong frontal zones during late spring to late summer. These storms are infrequent to the plant site area.
2.3.1.2.5 Ice Storms (freezing rain)
The United States Weather Service defines glaze as ". . homogeneous, transparent ice layers which are built upon horizontal, as well as on vertical surfaces either from supercooled rain or drizzle, or from rain or drizzle when the surfaces are at a temperature of 32 0 F or lower". Although glaze may occur at air temperatures far below 32 0 F, the majority of ice storms occur with air temperature between 25 0 F and 32 0 F. Ice storms at the HBR site are caused primarily by polar front waves. Below-freezing temperatures seldom last in this area more than a few hours after ice storms. Consequently, the mean duration of ice on utility wires during the period 1928-1937 was 19 hours. The greatest radial thickness on utility wires observed during the nine winters of the period between 1928 and 1937 was .74 inches (Reference 2.3.1-8)
2.3.1-3
HBR 2 U UPDATED FSA t! 2.3.1.2.6 Hurricanes{i
Sustained hurricane force winds (>74 mph) have never been recorded by the Columbia Weather Service, although they have been observed in coastal areas of the state. Hurricanes usually deteriorate rapidly as they move onshore because of increased frictional drag and a loss of the energy source (water through release of latent heat of evaporation and condensation). Once onshore, the increased frictional effects have a tendency to turn the winds inward towards the hurricane's center; this yields greater vertical velocities which arecapable of producing intense rainfall. Since the HBR site lies approximately 90 miles from the nearest coastline, the major effect on the HBR area due to hurricanes is usually heavy precipitation. A list of hurricanes that have affected the HBR area are listed in Table 2.3.1-4. The maximum 24-hour precipitation of 7.66 in. at the Columbia Weather Service was the result of a hurricane in August 1949 (Reference 2.3.1-5). As would be expected, the intensities of wind and precipitation produced by hurricanes at the plant site are generally no greater than those produced by severe thunderstorms in the area, but may affect a larger area and last for longer time periods. The bestfit track of Hurricane Hugo passed within 40 miles of the plant site in September, 1989. Even though Hugo was the most damaging (in terms of dollars) hurricane ever to affect South Carolina, no weather stations within 50 miles of the plant site reported sustained hurricane force winds associated~with Hugo.
2.3.1.2.7 Extreme Winds
Using a Fisher Tippett Type II extreme value distribution, Thom (Reference 2.3.1-9) has calculated and plotted the annual extreme-mile 30 ft. level, 100year mean recurrence interval winds for the United States. From this publication, the HBR site extreme-mile 100-year recurrence period wind speed is 100 mph.
The extreme-mile wind is defined as the on-mile passage of wind with the highest speed. This includes all meteorological phenomena except tornadoes, which are dealt with separately. The extreme-mile wind does not reflect gustiness occurring during a short time interval. As an adjustment, Huss (Reference 2.3.1-10) suggests that a gust factor of 1.3 be applied to the 30 ft. level extreme-mile wind. Therefore, an instantaneous gust of 130 mph would be expected to occur at the 30 ft. level once within a 100-year period.
The observed one-minute fastest-mile windspeed recorded at the Columbia Weather Service is a 60 mph wind from the West in March 1954, at RaleighDurham a 73 mph wind from the west-northwest in October 1954, and at Charlotte a 59 mph wind from the southwest in July 1962. The 130 mph extreme-mile Thom value is 116 percent higher than the highest observed one-minute fastest-mile speed at Columbia and therefore, can be used as a very conservative value in additional analysis.
Observed one-minute fastest-mile wind speeds at Columbia, Raleigh-Durham, and Charlotte associated with Hurricane Hugo did not exceed previously stated extremes. However, the highest one-minute fastest-mile wind speed reported within a 50 mph radius of the plant site associated with Hurricane Hugo was 87 mph at Shaw Air Force Base (Sumter, SC).
Mg
2.3.1-4 ~
HBR2
I .
UPDATED FSAR 2.3.1.2.8 Precipitation Extremes
Table 2.3.1-5 lists precipitation extremes along with other parameter extremes for the National Weather Service Stations at Columbia, SC, Charlotte, NC, and Raleigh-Durham, NC (References 2.3.1-5, 2.3.1-3, and 2.3.1-4). The maximum monthly precipitation total observed from these stations was 21.79 in. at Raleigh in September 1999. The maximum 24-hour precipitation recorded was 7.66 in. at Columbia in August 1949. However, both the monthly and 24-hour extreme values from Columbia were exceeded at cooperative stations located in the plant site area in October, 1990. The remnants of Tropical Storm Klaus and Marco along with a stalled frontal zone located in the Appalachian mountains combined to produce a recordbreaking rainfall event in October, 1990, in central and northwestern South Carolina. Some of the higher monthly precipitation totals for October, 1990, were the 18.63 in. total recorded at Pageland, SC (located about 30 mi. northwest of the plant site) and the 16.93 in. total observed at Camden, SC (located about 30 mi. west-southwest of the plant site). In many locations oriented in a north-south axis located about 25 mi. west of the plant site between 8 and 10 inches of rain fell during the 24 hour period
ending at 8:00 a.m. EDT on October 11, 1990 (Reference 2.3.1-16). Conversely, the minimum monthly precipitation recorded was a trace at Columbia in October, 1963. The maximum monthly snowfall was a 25.9 in. total which fell in Raleigh during January 2000. The maximum 24-hour snowfall total was 17.9 in. which fell in Raleigh in January, 2000.
!
2.3.l-4a
UPDATED FSAR N The site area on ground snow load, 100-year mean recurrence interval is 12 lbs. per sq. ft. (Reference 2.3.1-11) . The minimum design roof snow load is determined by multiplying the on-ground snow load-of 12 lbs. per sq. ft. by the basic snow load coefficient of 0.8. This gives a value of 9.6 lbs. per sq. ft. as the 100-year recurrence interval roof snow load. Additionally, the 48-hour probable maximum winter precipitation occurs in December and is approximately 21.6 in. (water equivalent) using a 200 sq. ml. reference area (Reference 2.3.1-12). The month of December averages only 0.3 in. of snowfall; therefore, it is very improbable that the probable maximum winter precipitation would fall in the form of snow.
2.3.1.2.9 Atmospheric Conditions
The extent of vertical mixing is a major factor in determining atmospheric diffusion characteristics. As a rule, mixing depths are characterized by a diurnal cycle of a nighttime minimum and a daytime maximum. The nighttime minimum is the result of surface radiational cooling which produces stable conditions, frequently coupled with low level temperature inversions or isothermal layers.
The mid-afternoon maximum is attributable to surface heating which produces instability and convective overturning through a larger portion of the atmosphere. Mean mixing depths also show a seasonal cycle of a winter season minimum and a summer season maximum. Holzworth has shown this (Reference 2.3.1-13) by listing monthly mean maximum mixing depths. Table 2.3.1-6 lists these results for Greensboro, NC (nearest data point to the plant site). The lowest mean maximum mixing depth occurs in January (390 m), and the greatest mean maximum depth occurs in June (1790 m).
Low level temperature inversions also inhibit vertical mixing. Hosler (Reference 2.3.1-14) has compiled frequencies based on the percent of total hours of occurrence of an inversion or isothermal layer based below 500 ft. The frequency of low level temperature inversions for Greensboro are presented in Table 2.3.1-7. The summer season averages inversions about 33 percent of all hours. Comparatively, the winter season averages inversions approximately 43 percent of all hours.
Cases of high air pollution potential occur during periods. of-stagnating anticyclones which exhibit-low surface winds, no precipitation, and shallow mixing depths that result from a subsidence inversion. These conditions occur most frequently at the plant site during the fall months, particularly October. According to Kopsh1_ver (Reference 2.3.1-15), about 32 cases of autumnal atmospheric stagnation that lasted four days or more occurred during the 35-year period from 1936 to 1970. A total of four cases that lasted seven days or more were recorded during the same 35-year period.
2.3.1-5
Amendment No. 10
HBR 2 UPDATED FSAR
TABLE 2.3.1-1
STATIONS REFERENCED FOR REGIONAL CLIMATOLOGY AND LOCAL METEOROLOGY
2.3.•1-6
STATION ELEVATION DISTANCE DIRECTION CLIMATOLOGICAL (FT.) FROM FROM REGION
NUMBER OF CLOUD-TO-GROUND FLASHES BY SEASON (PER SQ. KM.)
SEASON CHARLOTTE, NC RALEIGH-DURHAM, COLUMBIAr SC KNC
Winter .36 .18 .54 (D,JF) Spring 2.00 2.19 2.15 (M,A,M) Summer 4.55 4.74 5.73 (J,J,A) Fall .91 1.10 1.07
(SO,N) Annual 7.65 8.38 9.49
41 G .
2.3.1-8
I
r r r r
Able 31 Aug 1952 NE 30 1.22 3.52 Barbara 13 Aug 1953 NNE 20 0.10 0.25 Carol 30 Aug 1954 N18 Trace Trace Edna 10 Sept 1954 NNE 16 Trace 0.10 Hazel 15 Oct 1954 WNW 50 1.55 4.04 Connie 11 Aug 1955 NNE 23 0.10 0.24
12 Aug 1955 NNE 29 0.08 0.08 Diane 16 Aug 1955 NE 29 0.50 1.00
17 Aug 1955 NW 20 0.15 0.28 lone 25 Sept 1955 N 13 0.50 1.00
26 Sept 1955 NE 15 0.03 0.04 Flossy 26 Sept 1955 NNW 25 0.42 0.96 Helene 27 Sept 1958 N 22 0.00 0.00 Gracie 29 Sept 1959 ESE 38 0.61 4.89
30 Sept 1959 S 25 0.03 0.14 Brenda 28 July 1960 SE 16 0.75 1.26 Donna 11 Sept 1960 N 20 0.20 0.75 Esther 19 Sept 1961 NE 9 Trace Trace Alma 27 Aug 1962 NNE 14 0.09 0.21 Ella 19 Oct 1962 NNE 20 0.00 0.00 Ginny 20 Oct 1963 N 21 0.00 0.00 Cleo 29 Aug 1964 NNE 21 0.61 4.20
30 Aug 1964 ESE 20 0.14 0.61 Dora 12 Sept 1964 NNE 23 0.74 2.83
13 Sept 1964 N 21 0.14 0.40 Gladys 22 Sept 1964 NNW 14 0.00 0.00 Hilda 4 Oct 1964 NNE 18 0.53 1.27
5 Oct 1964 N 22 0.63 2.56 Isabell 15 Oct 1964 NE 16 0.35 4.09
16 Oct 1964 N 20 0.56 2.02 Alma 9 June 1964 ESE 21 0.17 0.56
10 June 1964 S 23 0.51 1.76 Doria 9 Sept 1967 NW 21 0.58 1.64 Gladys 19 Oct 1968 SW 17 0.80 2.60 Doria 16 Aug 1971 ENE 13 1.41 3.59
17 Aug 1971 ENE 21 0.39 2.05 Ginger 30 Sept 1971 N 17 0.02 0.04
1 Oct 1971 WNW 12 0.03 0.05 Agnes 19 June 1972 E 24 0.35 1.00
20 June 1972 ESE 20 1.08 2.32 Eloise 26 Sept 1975 NNW 13 0.00 0.00 Belle 8 Aug 1976 E 12 Trace Trace David 4 Sept 1979 ENE 29 0.45 3.95
5 Sept 1979 ENE 24 0.33 1.35 Dennis 19 Aug 1981 NNE 17 0.03 0.04
20 Aug 1981 NNE 10 0.02 0.03 Isidore 29 Sept 1984 NE 14 0.03 0.06
30 Sept 1984 ENE 14 0.27 0.47 Bob 25 July 1985 SSW 16 0.41 0.80 Kate 22 Nov 1985 N 20 0.51 1.98 Hugo 21 Sept 1989 NNE 30 0.21 0.96
22 Sept 1989 WNW 48 0.96 2.20
ADENDWENT NO. 10 2.3.1-9
TABLE 2.3.1-4 CONTINUED FROM PREVIOUS PAGE
STORM DATE MAXIMUM WINDS MAXIMUM 24-HOUR (mph) PRECIPITATION PRECIPITATION
(IN/HR) (IN)
GORDON 11 NOV 1994 E 21 0.29 0.66
ALLISON 5 JUN 1995 NE 26 0.32 2.88 6 JUN 1995 NW 28 0.89 2.64
Maximum Monthly 16.0 19.3 in. 25.8 Snowfall (2/73) (3/60) (1/00) (Inches) - (1947-01) (1940-01) (1945-01)
Maximum 24-Hour 15.7 12.1 in. 17.9 Snowfall (2/73) (1/88) (1/00) (Inches) (1947-01) (1940-01) (1945-01)
L ,
f
Amendment No. 10
2.3.1-10
HBR2 UPDATED FSAR
TABLE 1.3.1-6
MEAN MONTHLY MAXIMUM MIXING DEPTHS (METERS ABOVE SURFACE) *
MONTH DEPTH
JANUARY 390
FEBRUARY 650
MARCH 1130
APRIL 1180
MAY 1530
JUNE 1790
JULY 1490
AUGUST 1420
SEPTEMRtEIj - 1370
OCTOBER 1020
NOVEMBER 840
DECEMBER 580
-DATA FROM GREENSBORO, NC (NEAREST DATA POINT TO THE PLANT SITE)
'j i
2 .3. 1-11
HBR 2
UPDATED FSAR
TABLE 2.3.1-7
FREQUENCY OF INVERSIONS BASED BELOW 500 FEET
Percent Frequency of Inversions Occurrence at
Specific Times and All Times
SEASON 0300 GMT 1500 GMT 0000 GMT 1200 GMT ALL TIMES
WINTER 73 1i 58 72 43
SPRING 70 3 13 66 32
SUMMER 78 1 11 6 33
FALL 74 4 52 74 40
Note: 1. 0300 and 1500 GMT observations for the period 6/55-5/57
2. 0000 and 1200 GMT observations for the period 6/57-5/59
ye~
2.3.1-12
HBR 2
UPDATED FSAR
2.3.2 LOCAL METEOROLOGY
2.3.2.1 Normal and Extreme Values of Meteorological Parameters
The local meteorology is based upon HBR onsite data collected from January 1, 1991 through December 31, 1996 unless otherwise noted and offsite data from Charlotte, NC, Greensboro, NC, Raleigh-Durham, NC, Florence, SC, and Columbia, SC. Normal and mean data are based on the 1971-2000 recording period.
2.3.2.1.1 Wind
Wind direction and speed distributions are essential parameters for determining site characteristic diffusion climatology. Onsite joint frequency distributions of direction and speed by stability class and a summary of all winds, as outlined by Regulatory Guide 1.23 (Reference 2.3.2-1), for the period January 1991 through December 1996 are given by Tables 2.3.3-5 and 2.3.3-6. Annual wind roses for Florence (Reference 2.3.2-2), arq illustrated by Figure 2.3.2-1.
The Florence, South Carolina (1991-1996) joint frequency distribution of wind direction and speed by Pasquill stability classes is given in Table 2.3.2-1. Pasquill stability classes were determined by the STAR method. Stability classes F and G were combined into F stability. Observations of wind speeds less than 3 knots were directionally distributed according to the frequency of occurrence of speeds from 3 to 6 knots in each direction category.
Despite differing techniques used to determine atmospheric stability (delta temperature method for onsite data and the STAR method for Florence data), the onsite joint wind frequencies for the HBR site (Tables 2.3.3-5 and 2.3.3-6) compare favorably to those compiled for Florence. Neutral (D) and slightly stable (E) stability classes occur more frequently at both stations. Stable (F) and extremely stable (G) stability classes occur approximately 20% of the time at both sites.
The characteristic northeast-southwest bimodal frequency distribution is evident and is depicted by the wind rose given in Figure 2.3.2-1. Average wind speeds from the area off site stations are rather uniform, ranging from 7.4 mph at Charlotte, and Raleigh, NC, to 6.8 mph at Columbia, SC.
The onsite lower level (approximately 11 meters) mean wind speed based on 1991lil9_6 data is 4.7 mph. This onsite value is about 30 percent lower than the 6.8 mph value observed at the Columbia Weather Service. Differing time periods, averaging methods, and instrumentation account, in part, for the lower onsite wind speed value.
1, 0
.. rA ~ .~ ~,Amendmerrt No. 10
" "4 l
HBR 2 UPDATED FSAR
The maximum site area one-minute average wind from the National Weather Service stations was 60 mph from the west recorded at Columbia, SC in March 1954 (Reference 2.3.2-3) . A complete list of hurricanes affecting the site area, the amount of precipitation, and fastest-mile wind associated with each is given by Table 2.3.1-4.
2.3.2.1.2 Temperature
Monthly and annual summaries of climatological normal maximum, minimum, and average temperatures for Raleigh-Durham (Reference 2.3.2-4), Charlotte (Reference 2.3.2-5), and Columbia (Reference 2.3.2-3) are given in Tables 2.3.2-2 through 2.3.2-4. Monthly and annual onsite mean temperature data for January 1991 through December 1996 is presented in Table 2.3.2-5. The mean maximum and minimum temperature data from the onsite meteorological station is shown in Table 2.3.2-6 and Table 2.3.2-7, respectively. The site area diurnal temperature range spans from about 20OF in the winter and summer seasons to around 25OF in the transitional autumn and spring months (Reference 2.3.2-6). The lowest temperature recorded was -9 0 F in January 1985 in Raleigh-Durham and the highest recorded temperature was 107 0 F at Columbia in June 1954 and repeated in August 1983.
2.3.2.1.3 Water Vapor
Mean monthly and annual dewpoint temperatures and corresponding absolute humidity values for Raleigh-Durham, Charlotte, and Columbia are given in Table 2.3.2-8 (Reference 2.3.2-6). Monthly and annual onsite dewpoint temperatures for the period January 1991 through December 1996 are given in Table 2.3.2-9. The onsite average dewpoint of 50.2 0 F compares well to the 52 0 F average dewpoint observed at Columbia, SC. Onsite winter and summer dewpoint temperatures are slightly lower.
Diurnal variations of relative humidity for Charlotte, Columbia. and Raleigh-Durham are given in Tables 2.3.2-10 through 2.3.2-12 respectively for local standard times of 1:00 a.m., 7:00 a.m., 1:00 p.m., and 7:00 p.m. (Reference 2 3.2-5, 2.3.2-3 and 2.3.2-4) . The 7:00 a.m. and 1:00 p.m. times correspond to the general maximum and minimum respective values of the diurnal relative humidity cycle, with 1:00 a.m. and 7:00 p.m. providing approximate midrange values. The late summer to early fall maximum of early morning (7:00 a.m.) relative humidity values also results in the same seasonal maximum of radiational fog frequency. I
2.3.2.1.4 Precipitation
Precipitation is rather uniformly distributed on an annual basis in the site region. Onsite precipitation totals are summarized in Table 2.3.213. climatologically, August has a tendency to be the wettest month, April the driest, but the variance is small such that the region does not posses a "wet" and "dry" season. The extreme rainfall rates summary for the onsite facility for the January 1976 through December 1996 period in shown in Table 2.3.2-14. The onsite extreme rainfall rates for all time periods are included in the table. with a maximum 24-hour precipitation total of 5.83 in. ending on October 11, 1990, resulting from the combination of the Sre~mnan-ts-of T rQica! Sat~orm _Lu~ncqL.M~rco. "' '
51 ,,
Amendment No. 10
"'3I I:~
3 21- 2
.1 ý . I
HBR2 UPDATED FSAR
2.3.2.1.5 Fog
For the period 1948-2001, heavy fog (visibility < 1/4 mile) occurred at Columbia on an average of 26 days per year, with the fall and winter months showing the greater number of days of nearly 3 per month (Reference 2.3.2-3). The most common type of fog occurring in the HBRarea is ground fog as a result of nighttime radiational cooling. For this purposes fog may be defined as a stratus cloud occurring at the surface with its top at the base of the radiationally induced temperature inversion. Ordinarily ground fog occurs more frequently in the early morning hours near sunrise when the daily minimum surface temperature is reached. It is usually shallow and disappears shortly after sunrise (Reference 2.3.2-7). Seasonally, the greater frequencies of occurrence are the fall and winter as a result of the combination of relatively moist air at the surface due to summer vegetation and the increasingly longer nights in the early fall. Also, the continental anticyclone which develops in late summer results in low surface winds, especially near sunrise, to give a consistently high frequency of fog occurrences during August and September; however, the fog persists for only about five hours. Strong nightly radiational cooling coupled with a predominance of anticyclonic circulation, which results in marked stability in the lower atmosphere, produces the greater fog frequencies.
2.3.2.1.6 Atmospheric Stability
Table 2.3.2-15 gives average onsite frequencies of Pasquill Stability categories for the 1991-1996 period. Temporal variations of frequencies within the individual stability classes are small. Almost 62 percent of all hours fall into either neutral (D) or slightly stable (E) stability categories. Nearly 10 percent of all hours fall into the extremely stable (G) stability category. Extremely unstable (A), moderately unstable (B),
and slightly unstable (C) stability categories combined occur only approximately 18 percent of the total hours.
2.3.2.1.7 Monthly Mixing Heights
Mixing height data is presented in Section 2.3.1.2.9.
''($ !V A 14)VP.
2.3.2-3
TABLE 2.3.2-1 WIND DISTRIBUTION BY PASQUILL STABILITY CLASSES (STAR PROGRAM)
ANNUAL RELATIVE FREQUENCY DISTRIBUTION STATION = 723106 Florence SC 1991-1996 STABILITY CLASS A
SPEED(KTS) 0-3 4-6 7-10 11-16
.000242
000363
000504
000222
.000363
.000222
.000342
000363
000665
000262
000463
000302
.000262
000222
DIRECTION
N
NNE
NE
ENE
E
ESE
SE
SSE
S
SSW
SW
WSW
W
WNW
NW
NNW
TOTAL
.000000 .000000
000000 .000000
000000 .000000
000000 .000000
000000 .000000
000000 .000000
000000 .000000
000000 .000000
000000 .000000
.000000 .000000
000000 .000000
000000 .000000
.000000 000000
.000000 000000
.000000 .000000
.000000 000000
.000000 .000000
GREATER 17-21 THAN21
.000000 000000
.000000 .000000
.000000 .000000
.000000 000000
.000000 000000
.000000 .000000
.000000 .000000
.000000 .000000
.000000 000000
.000000 000000
000000 000000
.000000 .000000
.000000 000000
.000000 .000000
.000000 .000000
.000000 .000000
.000000 .000000
RELATIVE FREQUENCY OF OCCURRENCE OF A STABILITY = .006526
RELATIVE FREQUENCY OFCALMS DISTRIBUTED ABOVE WITH A STABILITY = .001027
�ThP
2.3 2-4
.000069
.000068
.000118
.000065
000068
000041
.000112
.000068
000172
000049
000110
000080
000073
000041
000060 000322
00005f 000161
001249 005277
TOTAL
.000311
.000430
.000621
.000287
.000430
.000263
.000454
.000430
.000837
.000311
.000574
.000382
.000335
000263
000382
000215
TABLE 2.3.2-1 CONTINUED
RELATIVE FREQUENCY DISTRIBUTION STATION = 723106 Florence SC 1991-1996
STABILITY CLASS B
SPEED(KTS)DIRECTION 0-3 4-6
N 000472 .002095
NNE .000440 .001793
NE .000754 .001813
ENE .000540 .001692
E .000604 .001450
ESE 000392 .001349
SE 000350 .001168
SSE .000430 .001088
S 000637 .002377
SSW .000500 .001732
SW 000469 .001853
WSW 000421 .001410
W .000393 .001571
WNW .000236 .000947
NW .000229 .001088
NNW 000242 .001410
TOTAL 007110 .024834
7-10 11-16 17-21
000926 .000000 .000000
.001047 .000000 .000000
.001208 .000000 .000000
.000826 .000000 000000
.001047 000000 .000000
.000544 000000 .000000
.000524 000000 .000000
.000564 000000 .000000
.001349 000000 .000000
.000806 .000000 .000000
.001571 000000 .000000
.001430 000000 .000000
.001047 000000 .000000
.000544 000000 .000000
.000584 000000 .000000
.000705 .000000 .000000
.014723 000000 000000
RELATIVE FREQUENCY OF OCCURRENCE OF B STABILITY = 046667
RELATIVE FREQUENCY OF CALMS DISTRIBUTED ABOVE WITH B STABILITY = .003122
m.. . . .. . ... "
M,6
232-5
ANNUAL
GREATER THAN 21
.000000
.000000
.000000
.000000
.000000
.000000
.000000
.000000
.000000
.000000
.000000
.000000
000000
000000
.000000
000000
.000000
TOTAL
.003494
.003280
.003776
.003058
003101
.002285
.002042
002082
004363
.003038
003893
.003260
.003012
.001727
.001901
.002357
TABLE 2.3.2-1 CONTINUED
ANNUAL RELATIVE FREQUENCY DISTRIBUTION STATION = 723106 Florence SC 1991-1996 STABILITY CLASS C
DIRECTION 0-3
N .000468
NNE .000339
NE .000326
ENE 000202
E .000301
ESE 000271
SE .000291
SSE .000228
S .000518
SSW .000265
SW .000274
WSW .000378
W .000258
WNW .000224
NW .000134
NNW 000176
TOTAL 004653
SPEED(KTS) GREATER 4-6 7-10 11-16 17-21 THAN21
.003283 .006365 000645 .000000 .000000
002598 .006264 000725 000040 .000000
.002739 .006989 000987 000020 .000000
.002135 .005035 000645 000020 .000000
.002014 004129 000383 000000 .000000
.002216 001974 000101 000020 .000000
.001853 002236 000161 .000000 .000000
.001873 002276 000121 .000000 .000000
.003726 005619 000504 .000000 .000000
002457 .005720 .000463 000040 .000000
.002598 006848 000987 000040 .000000
002880 006405 001289 000040 .000000
.002014 005458 000403 000081 .000000
.001148 002578 000242 000000 .000000
.001410 002417 000161 000000 .000000
.001410 .003484 000201 000020 .000000
036354 073797 008016 000322 000000
RELATIVE FREQUENCY OF OCCURRENCE OF C STABILITY = 123142
RELATIVE FREQUENCY OF CALMS DISTRIBUTED ABOVE WITH C STABILITY = 002477
[A
3 2-6
TOTAL
.010760
009966
011061
.008036
006827
.004581
004540
.004498
.010367
008946
010748
010992
008214
.004192
.004121
.005292
TABLE 2.3.2-1 CONTINUED
ANNUAL RELATIVE FREQUENCY DISTRIBUTION STATION = 723106 Florence SC 1991-1996 STABILITY CLASS D
SPEED(KTS) GREATER DIRECTION 0-3 4-6 7-10 11-16 17-21 THAN 21 TOTAL
N .001416 .010272 .020363 .012487 000504 .000081 .045122
NNE .001429 .008882 .021692 012568 000685 000081 045337
NE 001334 .009043 .021349 013776 000705 000000 046208
ENE 001169 .007613 .012669 005921 000201 000060 .027634
E 001377 .007231 .010352 003082 000121 .000020 .022183
ESE .000879 .005478 .007795 002699 000060 000101 .017012
SE .000880 .005237 .009084 004552 000141 000040 .019934
HBR Average Frequency of Pasquill Stablility Categories Percent by Month - (1991-1996)
(F)
Month A B C D E F G
January 1.6 2.9 4.4 44.0 26.1 7.9 13.0
February 4.0 4.7 5.2 35.7 27.3 11.0 12.1
March 8.7 4.6 5.1 35.4 25.9 8.6 11.8
April 14.9 6.4 6.1 30.0 23.4 9.3 9.9
May 14.6 7.0 7.2 33.7 21.0 9.0 7.4
June 11.2 7.4 8.0 37.0 25.1 8.2 3.1
July 11.6 6.1 7.5 34.5 30.4 7.8 2.1
August 4.3 5.4 7.8 39.1 28.3 9.8 5.4
September 8.4 4.6 6.8 37.0 24.5 10.9 7.7
October 6.5 3.8 4.8 32.2 22.7 11.9 18.1
November 1.9 3.0 3.6 35.1 28.7 11.6 16.2
December 2.0 2.7 3.9 39.9 26.6 11.1 13.8
1991-1996 7.5 4.9 5.9 36.2 25.8 9.7 10.0
ný ,~I 4 pq
2.3.2-24
LLBR 2
UPDATED FSAR :"".'
2.3.3 Onsite Meteorological Measurements Program
2.3.3.a History. Collections of HBR onsite meteorological data began in April, 1974. The original equipment was a Westinghouse Environmental Monitoring System. This system convertef sensor outputs to a proportional number of discrete pulses that were electronically integrated and-recorded on magnetic tape in 15-minute averaging periods. Also, Esterline Angus Twin Strip Chart Recorders were used in conjunction with the Westinghouse System for providing an analog record of the wind direction and speed parameters.
In 1987, a micro-computer based sensor-system was installed to replace the Westinghouse system. This micro-computer system collected electronic signals rep resenting the meteorological parameters and converted them to engineering units. The software for this system was developed internally by the CP&L meteorological staff; therefore, to ensure that the methodology employed by the micro-computer system was consistent with the Westinghouse system, both meteorological data collection systems were operated simultaneously for at least 18 months and provided conclusive proof that major differences did not exist between the systems. Data comparisons between the micro-computer system and the Westinghouse system showed no significant differences between the data. Therefore, in September of 1992. the meteorological historical database was converted from the Westinghouse system to the micro-computer system. This microcomputer system had the capacity to store up to four days of historical fifteen-minute averaged data.
In February of 1993, the Esterline Angus Twin Strip Chart Recorders were replaced with a hybrid recorder that provides trend traces and hard copy printouts of fifteenminute averaged data. Whereas the Esterline recorders provided analog traces for only the wind speeds and wind directions, the hybrid recorder collects data tor wind speeds, wind directions, ambient air temperature, differential temperatures, and dew point temperature. The stored fifteen-minute averaged data can be retrieved remotely, via modem. In addition, the hybrid recorder has a memory card that allows storage of over 30 days of retrievable data.
In 2000, the micro-computer based system was replaced with a new data acquisition system consisting of new data logging equipment to be used in conjunction with new wind sensors, new temperature sensors and aspirated shields, a new relative humidity sensor to repla8E the old dew point sensor (dew point is calculated by the data logger), a new rain gauge, and -a new barometric pressure sensor. The existing solar radiation sensor and recorder were re.--used.
2.3.3.1 Onsite Operational Program
The meteorological tower is located about 0.53 miles north of the Containment Building. The base of the tower is at the plant grade level of about 225 feet above mean sea level. An environmentally controlled- shelter, which houses recording A instruments, data collection devices, and remote data access equipment, is located near the tower, perpendicular to the prevailing wind flow to minimize air trajectory deviations.
The guyed, open-latticed tower supports upper and lower levels of instrumentation. The upper level instrumentation includes a wind sensor (for wind direction, ývind speed, and wind variance) and redundant temperature
2.3.3-1
HIBR 2 UPDATED FSAR
sensors used in the differential temperature monitoring. The lower level instrumentation includes a wind sensor, redundant temperature sensors for the differential temperature monitoring, and the ambient temperature measurement, and a relative humidity sensor. The wind sensors are mounted on 12-foot booms oriented perpendicular to the general NE-SW prevailing wind flow to minimize tower shadow effects. The temperature sensors and the relative humidity sensor are housed in aspirated shields mounted on 8-foot booms. The other meteorological parameters monitored by the system (not located on the tower) are solar radiation, barometric pressure, and precipitation. These sensors are located near ground level, near or at the equipment shelter. Operational sensor elevations are displayed in Table 2.3.3-3. Component sensor accuracies (used for release assessment) are outlined in Table 2.3.3-4.
The data logger acquires data from the sensors and converts the signals to engineering units. Fifteen-minute averaged data is stored within the data logger and the converted signals can be acquired, via modem, by plant computer systems and offsite contract meteorologist, as well as other systems or locations, as required. The new data logger also sends specific converted signals to the recorder as analog input signals. The data logger information can also be displayed locally using a computer.
The HBR 2 ERFIS computer system accesses the data logging system every 15minutes to acquire the latest 15-minute averaged data. This in ormation is stored in the ERFIS system and displayed on demand from any ERFIS terminal(such as in the Control Room).
The recorder also provides local display of the meteorological parameters sent to it from the data logger. The trend charts are changed as required. They are used as backup data to provide checks on the system and provide consistency of data. A communication port allows remote retrieval of data via standard telephone lines to an approved contractor.
'AZ
.MINOS JrI to
2.3.3-1a
HBR 2 UPDATED FSAR
2.3.3.2 Data Reduction
A host computer located with an approved contractor retrieves the meteorological data from the HBR data logging system on a daily basis (except weekends and holidays). The recorder is accessed by contractor as needed to verify or obtain the meteorological data. The data logging system data is reviewed for potential immediate data problems by the approved contractor. Then the data logging system data is rigorously checked for consistency and checked against National Weather Service data. Erroneous data is then discarded prior to insertion into the historical data base. The edited 15-minute averaged data is then stored on magnetic history media and appended to the master database. Available computer outputs include:
1. Monthly data summaries listing maximum temperature, minimum temperature, average temperature, barometric pressure, precipitation, solar radiation, and lower level dewpoint temperature as a daily average and monthly average.
2. Hourly totals of precipitation, hourly averages of barometric pressure, ambient temperature, differential temperature, lower level dewpoint, upper and lower level wind direction and wind speed, upper and lower level wind direction variance (sigma theta), Pasquill stability classes (as outlined in Regulatory Guide 1.23 [Safety Guide 23]) computed from the average of the two delta temperature systems, and accumulated solar radiation (langleys/minute).
3. The 15-minute averages of both upper level and lower level wind direction, speed, andf-ianc'e ksigma theta), barometric pressure, and accumulated solar radiation.
4. Joint wind frequency distributions by direction (as outlined in Regulatory Guide 1.23 [Safety Guide 23]) for both upper and lower levels, showing average wind speeds and number of unrecovered data hours.
SF -?ý
2.3.3-2
A-95
BR 2
UPDATED FSAR
2.3.3.3 Maintenance and Calibration
An onsite maintenance and calibration program was initiated in January 1976' Regulatory Guide 1.23 (Safety Guide 23) data recovery requirements are met by performing scheduled calibrations carried out in accordance with Robinson Emergency Plan requirements such that:
1. Wind systems are changed and replaced with National Institute of Science and Technology (NIST) traceable calibrated sensors.
2. Ambient and differential temperature systems are changed and replaced with NIST traceable calibrated systems.
3. Other onsite meteorological sensor system equipment is calibrated or its calibration is verified.
A further enhancement of data recovery is achieved by operating twin, redundant delta temperature systems simultaneously. Comparison of the two systems on a real time basis gives us the capabilities to detect discrepancies in either system, usually within 24 hours (except weekends and holidays).
2.3.3.4 Onsite Data
Onsite joint wind percentage frequency distributions (compiled per Regulatory Guide 1.23 [Safety Guide 23]) for both upper and lower sensor efevations for the period January 1991 through December 1996 is presented in Tables 2.3.3-5 and 2.3.3-6. Data recovery percentages for this period are 96.8 percent for the lower level and 97.2 percent for the upper level.
All onsite joint wind frequency distributions were compiled by using the delta temperature stability classifications, as outlined by Regulatory Guide 1.23 (Safety Guide 23).
Average onsite wind speeds for the total six-year period at the lower and upper levels are 4.7 mph and 8.9 mph, respectively. Representation of the data to long term, area, climatological averages are discussedin Sections 2.3.1 and 2.3.2.
2.3.3.3
II
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TABLE 2.3.3-1
Refer to Table 2.3.3-4
- W����flEWZ -1I
2.3.3-4
Zia
.1
HBR 2
UPDATED FSAR
TABLE 2.3.3-2
Deleted
,~ V
2.3.3-5
HIBR 2
UPDATED FSAR
Deleted
H it VN.2. f
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2.3.3-5a-
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2.3.3-6
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UPDATED FSAR
Deleted
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HBR 2 UPDATED FSAR
TABLE 2.3.3-3
OPERATIONAL SENSOR ELEVATIONS
SENSORS APPROXIMATE OPERATIONAL ELEVATIONS ABOVE TOWER BASE (METERS)
WIND 11.0 AND 62.0 RELATIVE HUMIDITY 10.0
SOLAR RADIATION 1.5 DIFFERENTIAL TEMPERATURE 10.0-61.0
PRECIPITATION 1.5 BAROMETRIC PRESSURE 1.5 AMBIENT TEMPERATURE 10.0
:Al >05
2i
2.3.3-7
Revision No. 17
HBR 2 UPDATED FSAR
TABLE 2.3.3-4
COMPONENT ACCURACY
I,.
.1.
ISt N'--
,-'4*j � � V - V -
2.3.3-8
WIND SPEED (SENSOR) 0-100 mph + 0.4 mph
WIND DIRECTION, 0 TO 360 + 3 DEGREES
DIFFERENTIAL TEMPERATURE SYSTEM + 0.270 F OVER AMBIENT TEMPERATURE RANGE FROM -50 TO +30 0 F
AMBIENT TEMPERATURE SYSTEM + 0.270 F
DATA LOGGER LINEARITY: + 0.001% (-400 TO +60 0 C) BASIC ABSOLUTE ACCURACY + 0.005% (-400 TO +60 0 C) BASIC RATIOMETRIC ACCURACY: + 0.01% (+100 TO +30 0 C)
Stability based on 61-11m. Differential Temperature Table 2.3.4-1
Percent by Season - (1991-1996) (Pasquill Class)
SW
0.000
0.096
0.409
0.497
0.090
0.000
0.000
WSW
0.000
0.129
0.432
0.362
0.047
0.000
0.000
W
0.000
0.162
0.440
0.090
0.008
0.000
0.000
/"
Unstable Neutral
Spring 20.0 33.7 46.3 Summer 26.9 35.0 38.0 Fall 17.5 36.1 46.4 Winter 8.7 39.7 51.6 Annual 18.2 36.2 45.6
~, "_ _ •I I#
~f
Stable
2 3 4-3
HBR 2 UPDATED FSAR
REFERENCE SECTION 2.3
2.3.1-1 Regulatory Guide 1.76 "Design Basis Tornado for Nuclear Power Plants", April 1974
2.3.1-2 "Technical Basis for Interim Regional Tornado Criteria", WASH - 1300, U.S. Atomic Energy Commission, Office of Regulation, May 1974
2.3.1-3 Charlotte, North Carolina 2001 "Local Climatological Data, Annual Summary with comparative Data", National Oceanic and Atmospheric Administration, National Climatic Center, Asheville, North Carolina
2.3.1-4 Raleigh - Durham, North Carolina, 2001 "Local Climatological Data, Annual Summary with Comparative Data". National Oceanic and Atmospheric Administration, National Climatic Center, Asheville, North Carolina.
2.3.1-5 Columbia, South Carolina, 2001 "Local Climatological Data, Annual Summary with Comparative Data", National Oceanic and Atmospheric Administration, National Climatic Center, Asheville, North Carolina.
2.3.1-6 Byers, H.R., "General Meteorology", McGraw-Hill, Inc., New York, new York, 1974
2.3.1-7 Marshall, J. Lawrence, "Lightning Protection", John Wiley & Sons, 1973
2.3.1-8 Bennett, I., "Glaze - It's Meteorology and Climatology, Geographical Distribution and Economic Effect", Headquarters quartermaster Research and Engineering Command, U.S. Army, Natick, Mass. Technical Report EP-105, 1959
2.3.1-9 Thom, H.C.S., "New Distribution of Extreme Mile Winds in the United States", ASCE Environmental Engineering Conference, Dallas, Texas, February 1967
2.3.1-10 Hoss, P.O., "Relation Between Gusts and Average Wind Speeds", Report No. 140, David Gucerhien Airship Institute, Akron, Ohio, 1946
2.3.1-11 ANSI A58.1 "Building Code Requirements for Minimum Design Loads in Buildings and Other Structures", American National Standards Institute, 1972
2.3.1-12 Seasonal Variation of the Probable Maximum Precipitation East of the 105th Meridian for Areas From 0 to 1000 Square Miles and Duration's of 6, 12, 24, and 48 Hours", Hydrometeorological Report No. 33, U.S. Department of Commerce, U.s. Department of Army Corps of engineers, Washington, DC, April 1956.
A i.
Amendment No. 102.3R-1
HBR 2 UPDATED FSAR
2.3.1-13 Holzworth, G.I., "estimates of Mean Maximum Mixing Depths in the Contiguous United States", U.S. Weather Bureau Research Station, Cincinnati, Ohio, May 1964 2.3.1-14 Hosler, C.R., "Low-Level Inversion Frequency in the Contiguous United States," Monthly Weather Review, Vol. 83, September 1961, Pages 319332 2.3.1-15 Korshover, Julius, "Climatology of Stagnating anticyclones East of The Rocky Mountains, 1936-1970, NOAA Technical Memorandum ERL ARL 34, U.S. Department of Commerce, National Oceanic and Atmospheric Administration, October 1971 2.3.1-16 "Climatological Data, South Carolina," October 1990, Volume 93, Number 10, National Oceanic and Atmospheric Administration, National Climatic Data Center, Asheville, N.C. 2.3.2-1 Regulatory Guide 1.23, "Onsite Meteorological Programs", February 17, 1972 2.3.2-2 "Wind Distributions by Pasquill Stability Classes (Star Program), Florence, South Carolina, 1991-1996 U.S. Department of Commerce. 2.3.2-3 Columbia South Carolina, 2001 "Local Climatological Data, Annual Summary with Comparative Data," National Oceanic and Atmospheric Administration, National Climatic Center, Asheville, North Carolina. 2.3.2-4 Raleigh-Durham, North Carolina, 2001, "Local Climatological Data, Annual Summary with Comparative Data," National Oceanic and Atmospheric Administration, National Climatic Center, Asheville, North Carolina. 2.3.2-5 Charlotte, North Carolina, 2001, "Local Climatological Data Annual Summary with Comparative Data, " National Oceanic and Atmospheric Administration, National Climatic Center, Asheville, North Carolina 2.3.2-6 U.S. Department of Commerce, Environmental Data Service, "Climatic Atlas of the United States,' June 1969 2.3.2-7 Byers, H.R., "General meteorology", McGraw-Hill, Inc. New York, New York, 1974, Pages 277-279 2.3.4-1 Holland, J.Z., "A Meteorological Survey of the Oak Ridge Area," U.S. Weather Bureau, Oak Ridge, Tennessee, November 1954 2.3.4-1 Slade, D.H., "Dispersion Estimates from Pollutant Releases of a Few Seconds to 8 Hours in Duration", Technical Note 2-ARL-2 ESSA Commerce, Washington, DC, August 1965
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