ML21257A283
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CALVERT CLIFFS UFSAR 2.3-1 Rev. 47 2.3 METEOROLOGY 2.
3.1 INTRODUCTION
This section summarizes the meteorological studies that have been conducted since the start of the engineering and design of the CCNPP. The meteorological studies performed include work in the following main categories, listed in chronological order:
- a.
Preliminary Data Collection
- b.
Initial Site Weather Data Program
- c.
Special Vertical Wind Standard Deviation Tests
- d.
Land-Sea Wind Speed Investigation
- e.
Extended Onsite Penetration Wind Study
- f.
Calculation of Incident and Routine Long-Term Relative Concentrations 2.3.2 PRELIMINARY DATA COLLECTION Proximal long-term weather station data were used from the Patuxent NATC - PAX (now Patuxent Naval Air Station - NHK) for periods of record from 1955-1960, and 1949-1964.
In addition, meteorological data from Washington National Airport (DCA); Byrd Field, Richmond, VA, (RIC); and Annapolis, MD, (ANA) were used to evaluate the frequency of various weather parameters and certain meteorological extremes, respectively. See Regional Map, Figure 2.2-1. Also, statistical data for severe weather parameters were obtained from numerous official records issued by the Environmental Science Services Administration (ESSA), Department of Commerce, Asheville, NC.
The following weather information from the above sources was evaluated and related to the Calvert Cliffs Nuclear Plant Site: Tornadoes, Freezing Precipitation, Tropical Storms, Hurricanes, and Diffusion Conditions.
2.3.2.1 Tornadoes Five tornadoes were observed during the period 1953-1962 in the general vicinity of a single latitude-longitude square near the proposed plant site. The mean annual frequency was 0.5 tornadoes per year and the probability of a tornado striking a single point within a single latitude-longitude square near Calvert Cliffs, using a method originally derived by H.C.S. Thom of ESSA, was calculated to be 3.75x10-4. The recurrence frequency was calculated to be once about every 2,700 years.
2.3.2.2 Thunderstorms Thunderstorm day statistics indicate that about 40 thunderstorms per year can be expected in the area. Fifteen years of records at Patuxent showed 814 observations of thunderstorm activities. From these data one can calculate the average duration of a thunderstorm to be 1.356 hours0.00412 days <br />0.0989 hours <br />5.886243e-4 weeks <br />1.35458e-4 months <br /> for a point. A study of 10 years of records for transmission subtransmission feeders was conducted.
This study showed that transmission and subtransmission feeder losses were 4 minutes and 423 minutes, respectively, due to storms in a 10-year period. The subtransmission feeders covered an area of approximately 180 square miles.
2.3.2.3 Freezing Precipitation The Patuxent NATC records (1949-1964) list 910 hours0.0105 days <br />0.253 hours <br />0.0015 weeks <br />3.46255e-4 months <br /> of snow and 265 hours0.00307 days <br />0.0736 hours <br />4.381614e-4 weeks <br />1.008325e-4 months <br /> of frozen or freezing precipitation, other than snow, for a total of 1175 hours0.0136 days <br />0.326 hours <br />0.00194 weeks <br />4.470875e-4 months <br /> (or 70,500 minutes) in 15 years. Interpolating for a 10-year span yields 47,000 minutes. The outages due to snow and/or freezing precipitation were 182 minutes and 122 minutes in 10 years, for transmission and subtransmission feeders, respectively. It is interesting to note that 9 of 12 outages occurred during
CALVERT CLIFFS UFSAR 2.3-2 Rev. 47 a single snowstorm in March 1958. Certain design changes were made as a result of this storm and it is unlikely that outages of this magnitude would again occur.
2.3.2.4 Tropical Storms and Hurricanes Approximately one hurricane per year poses a threat to the area, and about one hurricane every 10 years produces a significant effect. Northeasters, or extratropical storms, also can influence the area in terms of flooding of low-lying land. The detrimental effects of northeasters are considerably less than those postulated for hurricanes in the site area.
2.3.2.5 Preliminary Diffusion Climatology The frequency of various Pasquill classes of diffusion was initially assessed through the use of the familiar Pasquill-Turner method. The proximal Patuxent NATC data were used for a five-year period of record, which yielded the following results:
Pasquill Condition Annual Percent Occurrence A and B 2.6 C
10.4 D (day) 35.0 D (night) 28.2 E
11.8 F
8.0 G
4.0 Since it is possible to take advantage of offshore waterways in considering a site boundary, it was considered reasonable to limit discussion interest and calculations to onshore winds at the Calvert Cliffs site.
The onshore wind directions, by sector, are as follows:
- a.
North
- b.
North-Northeast
- c.
Northeast
- d.
East-Northeast
- e.
East
- f.
East-Southeast The frequency of all winds from these directions was documented (over a five-year period) to be:
- a.
Patuxent NATC 23.0%
- b.
Washington National Airport 24.0%
- c.
Byrd Field, Richmond, VA 30.0%
- d.
Annapolis, MD 24.0%
Based on these total wind frequency samples, it was calculated that the frequency of inversion winds associated with onshore flow was as follows:
Pasquill Pasquill Station "E"
"F and G"
- a.
Patuxent NATC 2.04%
1.35%
- b.
Annapolis 1.97%
3.40%
CALVERT CLIFFS UFSAR 2.3-3 Rev. 47 In order to confirm the initial conclusions drawn above and to get a first approximation of typical Pasquill "F" conditions at the site, two additional station records were examined in detail. Five years of records from RIC and DCA were examined and a computer program was written to produce the frequency of winds equal to or less than X knots for the 0100 EST hour of the day when the cloud cover was equal to or less than.4 coverage. Values for wind speeds from 10 knots to calm were documented. The results indicated that the average Pasquill wind speed for RIC was 1.88 m/sec, while that for DCA was found to be 2.02 m/sec. The frequency of these conditions with onshore wind directions was found to be 2% at RIC and 3% at DCA. Since neither of these stations had as good exposure as would be anticipated for the Calvert Cliffs site due to the unrestricted fetch over the Chesapeake Bay, it was deemed conservative to select a wind speed of 1.5 m/sec as a typical onshore Pasquill "F" site condition.
In general, the sites low-level winds under a temperature inversion drain toward the Chesapeake Bay. It would not be possible for a ground-released effluent to get to the minimum site boundary under these conditions, and highly improbable that the ground release could get to the other inland boundaries due to terrain slope and other effects.
Wind persistence maxima for all wind sectors based on five-year record summaries at Annapolis, MD were as follows:
1 Sector 3 Sectors 5 Sectors 48 hrs 140 hrs 220 hrs Washington National, Byrd Field, and Patuxent showed less persistent winds MAXIMUM WIND PERSISTENCE FOR ONSHORE WINDS IN A SINGLE SECTOR (5 YEARS OF RECORD)
Station Pasquill Condition Maximum Persistence DCA 1-3 knots winds 6 hrs RIC 1-3 knots winds 6 hrs PAX "E" and "F" 12 hrs ANA "E" and "F" 12 hrs PAX All Speeds 27 hrs ANA All Speeds 37 hrs Onsite low-level diffusion measurements were made at two primarily coastal locations during the periods from September 14, 1967, through November 9, 1968 at site N1W; and November 9, 1967 and through November 9, 1968, at site S1W.
See Figure 2.3-1, Figure 2.3-2, and Table 2-10 for station locations and the description of meteorological instrumentation, respectively. In addition, temperature gradient approximations were made using two inland ground-level thermograph stations at the site at locations approximately 120 above mean sea level (MSL) and 40 MSL. These data also extended from November 9, 1967 to November 9, 1968.
The two coastal sites were selected initially because they:
- a.
offered good to excellent exposure to onshore winds; and
- b.
offered the only initial long-term exposure to winds unmodified by terrain and extensive tree cover.
CALVERT CLIFFS UFSAR 2.3-4 Rev. 47 The results of these onsite data comparison evaluations indicated the following:
- a.
Frequency of inversions derived from
- 1.
onsite data 31%
- 2.
long-term data 24%
- b.
Air drainage was toward the Bay under inversion conditions.
- c.
Average wind speed during inversion conditions was 2.6 MPS.
- d.
Standard deviation of horizontal wind direction () during worst, single-season wind sector inversion conditions averaged 6.6°.
- e.
When wind speed decreased, increased, in general.
- f.
For on/or along-shore winds, the average value of was 0.209 rad meters/sec.
- g.
/Q values at the 0.5% level of all conditions was 1.17x10-4 sec/m3 for the 1150 meter minimum site boundary.
2.3.3 SPECIAL VERTICAL WIND STANDARD DEVIATION TESTS 2.3.3.1 General Two sets of special diffusion tests were conducted at the Calvert Cliffs site. In both cases, both horizontal and vertical standard deviations of the wind conditions were measured.
2.3.3.2 Test Set 1 (October 17 to November 1, 1968)
In order to simulate actual reactor site location data, a standard anemometer was set up on a 40 bluff at Camp Conoy - just south of the reactor site. The anemometer permitted recording of wind direction and wind horizontal direction and its deviation. In addition, an e meter was installed to evaluate the vertical standard deviations during this period.
The wind sensors were about 10 above the cliff area and about 40 inland.
Results of e Test Set 1 were as follows:
Onshore Inversion Wind e Offshore Inversion Wind e "Neutral" Winds e Cases 16 122 157 e
13° 8° 14.3° Lowest e 1° 1° 1° Cases <5° 1
35 9
2.3.3.3 Test Set 2 (February 11 through 20, 1969)
A second set of readings was taken during this period at Station 2 (about 2000 from the coastline). The companion statistics for Test Set 2 were follows:
Onshore Inversion Wind e Offshore Inversion Wind e "Neutral" Winds e Cases 36 28 104 e
10° 13° 6° Lowest e 6° 2° 4° Cases <5° 0
5 1
These readings were also taken about 10 to 12 above the ground, but with an unobstructed trajectory from an onshore viewpoint.
CALVERT CLIFFS UFSAR 2.3-5 Rev. 47 2.3.3.4 Conclusions The sigma e values measured during these two test series both indicated that
- a.
Onshore inversion winds tend to produce near-neutral (Pasquill "D") e values.
- b.
Offshore inversion winds tend to produce lower standard deviations than onshore cases near the coast, but somewhat larger inland.
- c.
Only one case in the total showed e values as low as Pasquill "F".
2.3.4 LAND-SEA WIND SPEED INVESTIGATION There was some concern expressed that the wind speed for onshore flow at the Station 4 (S1W) site was not representative for inland locations because the anemometer was in an area that is subject to a "Venturi" effect when the wind direction is onshore. In order to explore this possibility, this study compared the wind speed and diffusion values at the Station 4 (S1W) site to those on a raft anchored about one mile offshore.
For approximately one month of data, the diffusion parameter () (STUB) was compared at each site where simultaneous onshore flow occurred at the sites. The average wind speeds at the two sites were also compared. Table 2-11 gives the results of the 256 simultaneous onshore winds and compares them to the classical Pasquill inversion classification values. The data indicated the following:
- a.
Only 1 observation of 256 at S1W gave value equivalent to Pasquill "F".
- b.
Wind speeds were generally lower at S1W than at the raft, but wind deviations were larger.
- c.
The only possible Venturi effect noted at S1W was when the wind was onshore and the speeds were 3 mph or less.
2.3.5 THE PENETRATION ONSHORE WIND STUDY The primary purpose of this extended meteorological investigation at the Calvert Cliffs site was to further refine the atmospheric dispersion parameters obtained from the initial site weather data program for use in the calculation of the relative concentration, /Q, at the site boundary nearest the reactor. Of secondary importance was to examine any anomalous flow features detected at the site and discuss its relevance to site diffusion characteristics.
Three inland meteorological stations were set up along with Station 4 (S1W). All four stations became active January 10, 1969 at the Calvert Cliffs site. In addition, temperature gradient systems were installed at Stations 2 and 4. See Figure 2.3-1 and Table 2-12 for station locations and instrumentation. A computer program was developed to analyze the wind flow across the site using the simultaneous wind observations from the four stations as input. The wind speed at each of the four stations was conservatively read to the lowest whole mph.
Standard techniques for evaluation of short-term releases (Pasquill "F", wind direction invariant, = 1 MPS), were compared with measured parameters to determine, within conservative limits, the proper values applicable to this specific location.
The low percent probability level of values was considered over the area collectively.
The procedure was to select only those hours when the wind at Station 1 (K) was blowing onshore and also where at least two of the stations a value of 0.200 existed.
Results for the one year extended study showed inversion conditions for 35% of the total observations, neutral conditions for 47%, and lapse for 17%, with 1% of the observations
CALVERT CLIFFS UFSAR 2.3-6 Rev. 47 missing. The winds showed a definite tendency to drain offshore during inversions; for the onshore winds, nearly 18% were in the neutral category, 9% in the unstable, and less than 4% in the stable category. The cumulative frequency distribution by wind speed category of on/or along-shore inversion winds for the four stations is given in Table 2-13 in terms of the total observations.
2.3.6 CALCULATION OF INCIDENT AND ROUTINE LONG-TERM RELATIVE CONCENTRATIONS Two types of relative concentration calculations are of interest at the Calvert Cliffs site.
The first are the 0-2 hour, 2-24 hour, and 1-30 day values which are used to determine the resulting radiation exposure from all of the postulated incidents. The second type is that pertinent to routine gaseous releases at the site.
2.3.6.1 Calculation of the Zero to Two-Hour Relative Concentration For the first two hours following a postulated "maximum hypothetical accident," the relative concentration is calculated by the Gifford wake model for a ground release:
=
1
+
where:
= relative concentration, seconds/m3
= average wind speed, meters/sec yz = standard deviations of the distributed material in the lateral and vertical directions, in meters c
= wake factor (dimensionless)
A
= cross-sectional area of structure from which material is presumed to be released, square meters From the data in Table 2-13 it was determined that 5% of the time the on/or along-shore winds at Station 1 had speeds of 3.2 MPS or less; the comparable speeds at the 5% level for Stations 2, 3, and 4 are 1.1 MPS, 1.7 MPS, and 2.1 MPS, respectively. The average of the four stations at the 5% level is 2.0 MPS. This shows that relatively strong flow is available for on/or along-shore inversion wind directions even at the 5% frequency level at the site.
The 0-2 hour relative concentration was evaluated at various frequency levels of the statistic STUB, the product of sigma theta and u-bar, using a very conservative technique. The technique was to select the average of the two lowest of the four simultaneous values of STUB observed for on/or along-shore winds, and to array these averages in the order of frequency of occurrence. Assuming that the wind speed was one meter per second, the corresponding values of were tabulated, and the corresponding values of for a distance of 1150 meters (the distance to the nearest site boundary) were selected. A wake factor of cA = 0.5x1640 M2 =
820 M2, and a z value of 24 meters were used. The relative concentrations are shown in Table 2-14 for the 1% through 10% frequency levels.
The value of z = 24 meters was selected as being compatible with the Pasquill "E" category for the 1% STUB level, using a wind speed of one meter per second.
The previously referred to measurements of e showed that a selection of Pasquill "E" for the vertical fluctuations was highly conservative.
CALVERT CLIFFS UFSAR 2.3-7 Rev. 47 A value for the 0-2 hour /Q of 1.3x10-4 sec/m3 was selected for the radiation exposure calculations in Chapter 14 resulting from the containment wall release pathway. Meteorological conditions resulting in this value or higher for the 0-2 hour relative concentration will occur less than 5% of the time. For releases from the plant vent stack, main steam gooseneck, and refueling water tank vent, a 0-2 hour /Q of 1.44x10-4 sec/m3 was calculated based on a zero cross-sectional area.
2.3.6.2 Calculation of the 2-24 Hour and 1-30 Day Average Relative Concentrations Average relative concentrations for periods of 10 hours1.157407e-4 days <br />0.00278 hours <br />1.653439e-5 weeks <br />3.805e-6 months <br />, 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />, and 29 days were calculated utilizing the onsite data acquired at Calvert Cliffs. No credit was taken for the wake factor of the plant structure and a minimum site boundary of 1150 meters was assumed in all 16 sectors.
The meteorological station with the lowest STUB value, Station 4 (S1W), was selected for this study. No Pasquill class with more diffusion than Pasquill "C" (slightly unstable) was considered and a ground-release accident model was assumed. As was done with the 0-2 hour /Q, the 2-24 hour and the 1-30 day values were also selected at the 5% frequency level. The resulting values were as follows:
Time Period 5% Probability Level /Q at 1150 meters (sec/m3) 2-24 hrs 9.10x10-6 1-30 days 2.70x10-6 The 5% values are shown as a function of distance on Figure 2.3-3 for all of the incident-related time periods.
2.3.6.3 Calculation of Routine Long-Term Concentrations The average annual relative concentrations, /Q which are applicable to routine venting or other routine operational gaseous effluent releases, have been determined for the final annual data record in accordance with the following equations:
(, ) = 2
()
(, ) 1
Where R =
0.01()
()
(,)
= relative concentration (sec meter-3); at a distance D (meters) from the effluent source; in direction sector i p
= Pasquill class (A through G) f(k)
= percent frequency wind blows toward sector i, within speed interval k, during Pasquill class condition p (k)
= Wind speed value representative of speed class interval, k, MPS z(p,D) = vertical dispersion coefficient, meters, for Pasquill class p, at distance D
B
= spread of wind sector, radians = /8, for 22-1/2° sectors.
CALVERT CLIFFS UFSAR 2.3-8 Rev. 47 These equations and resultant calculations are appropriate for evaluating ground releases over longer time intervals. They do not include a wake factor term.
The Isopleths of the average annual concentration, shown in Figure 2.3-4 were calculated using the wind data and T Pasquill class data of the final annual record. The maximum average on-shore relative concentration is 2.2x10-6 seconds meter-3 in the southeast sector at a distance of 1300 meters, which occurs as a result of the northwest winds and associated stability conditions. The site boundary in this direction is 2100 meters (Figure 1-1).
2.3.6.4 Average Annual Concentration at the Milk Samples Location Milk samples were obtained from a location 4.2 miles southwest of the reactor site, during the period December 23, 1971 through June 5, 1976. Since this time, no samples have been available in the area.
The model used in the above section has been applied to this location. The average annual /Q is 7.0x10-8 and occurs with a northeast wind.
2.3.6.5 Continuing Studies Additional studies were made to further refine the diffusion parameters. Included in these studies was an analysis of the data obtained at Station 2 (IS) between November 12, 1971 and November 11, 1972. This analysis showed that the diffusion characteristics specified in Section 2.3.6 are conservative.
Comparisons were made of T data from the 12 to 48 system installed on the pole at Station 2 (IS) and the T data from the "Sky Needle" 30 to 98 system also located at Station 2. The 12 to 48 system was continued in operation until September 1974.
A comparison study was made during the summer of 1974 to determine the correlation between meteorological data obtained from the "Sky Needle" 30 to 98 system at Station 2 and data obtained from the microwave tower system. The results of this study have been evaluated, and the remaining meteorological systems at Stations 2 and 4 were discontinued. The "Sky Needle" system was taken out-of-service August 14, 1975.
2.3.7 METEOROLOGICAL MEASUREMENT SYSTEMS In accordance with the requirements of NUREG-0654 and Generic Letter 82-33 (Supplement 1 to NUREG-0737), a meteorological tower (Figure 1-1) was installed to provide the essential parameters used in support of dose assessment calculations for emergency preparedness. The meteorological tower and instrumentation design meets the intent of Safety Guide 23, February 1972, and Regulatory Guide 1.97, Revision 3, for primary meteorological measurements systems.
The instrumentation on the meteorological tower is described in Table 2-12. Signals from the wind and temperature sensors are transmitted to the plant Control Room where T, Ws, Wd,, and rain water level can be continuously monitored by the operator. The meteorological tower, located at the end of Road B-1, has been operational since April 1982. Subsequently, the Technical Specifications were amended to designate the new meteorological system as the "primary" meteorological system as addressed in Regulatory Guide 1.23, Revision 1, and the old microwave tower became a backup system. The meteorological instrumentation on the old microwave tower was taken out-of-service in the fall of 1993. The current primary and backup meteorological
CALVERT CLIFFS UFSAR 2.3-9 Rev. 47 measurement systems are described in the Emergency Response Plan and its implementing procedures.
2.3.8 INVESTIGATION OF RELATIVE CONCENTRATION FREQUENCIES USING THERMAL STABILITY PARAMETERS During the investigation of the meteorological conditions at Calvert Cliffs, the almost universal acceptance of sigma theta to define diffusion qualities was questioned. This was in part due to the uncertainties of the sigma theta measurements in defining vertical plume growth. Also with winds at 2 to 3 mph or less, the measurement of sigma theta becomes difficult. Yet, in evaluations of the accident hazards, the periods of low wind speeds are the most critical. For these reasons the need for a Calvert Cliffs diffusion climate evaluation which does not depend upon sigma theta measurements was assessed.
2.3.8.1 The Requirement For Additional Meteorological Evaluation at Calvert Cliffs The Calvert Cliffs site analyses in Section 2.3.6 use sigma theta measurements to define horizontal plume growth only. The uncertainties of the relationships between these measurements and vertical plume growth do not, therefore, cloud the validity of these analyses. Further, the 5% worst weather conditions of most concern for the accident evaluations are those with on-shore winds at low speeds.
With on-shore directions conservatively defined to include nine 22-1/2° sectors, NW through SE clockwise, at Station 2 (IS) at 12 above grade, on-shore winds at 3 mph or less occur 12% of the time. This 12% frequency includes the unstable and neutral as well as the stable (winds have subsequently been measured at 33 above grade. At this elevation, on-shore winds of 3 mph or less occur less than 5% of the time.) It is unlikely, therefore, that the analysis based on sigma theta measurements are significantly biased by difficulties of measuring sigma theta at low wind speeds. Nevertheless, to remove the residual uncertainties in 1969 Baltimore Gas and Electric Company began to measure and record vertical temperature gradients near the ground for use in classifying site stability characteristics into inversion, neutral, and unstable conditions.
2.3.8.2 The Weather Data for the Independent Evaluation The vertical temperature gradient (T) was measured continuously between 12 and 50 above grade at Station 2 from 1969 through September 14, 1974.
Concurrently, an MRI 2040 wind instrument was installed at 33 above grade (as opposed to the prior wind instrumentation at 12 above grade) to measure wind speed and direction and values. Hourly averages of wind speed and direction, and one-an-hour 20 minute averages of were recorded. There were two sources of data available with the MRI 2040 wind instrument, sigma meter readings and wind range measurements. The data were compared and wind range measurements, divided by six to obtain, in accordance with the standard procedures, gave uniformly-lower values at the smaller readings. The range measured values were, therefore, used in this analysis because they provide more conservative estimates of the site diffusion quality.
CALVERT CLIFFS UFSAR 2.3-10 Rev. 47 Subsequent to the initiation of this program, it became an accepted practice to classify stability conditions into the standard Pasquill classes by the use of T values in accordance with the following table of values.
PASQUILL CLASS T° C/100 meters A
-1.9 B
-1.9 to -1.7 C
-1.7 to -1.5 D
-1.5 to -0.5 E
-0.5 to +1.5 F
+1.5 to +4.0 G
+4.0 To take advantage of this accepted practice, the validity, for Pasquill classification purposes, of the 12 to 50 T data has been investigated by a comparison with concurrently observed 12 to 97 data, as shown in Figure 2.3-5 and Table 2-15.
For the shallower layer, 2 to 3% more of the observations fell in the critical Pasquill E, F and G classes, and 2 to 3% less in classes B, C, and D.
Because the atmospheric layer upward from 30 above grade was becoming the standard layer for determination of thermal stability Pasquill classes, the validity of the 12 to 50 layer data was further investigated by a comparison with concurrently observed 30 to 97 Ts at Station 2, as shown in Figure 2.3-6. On this figure, the dashed line is the line showing equal lapse rates for both layers. It is apparent that the assignment of Pasquill classes using the 12 to 50 layer Ts is very conservative in comparison with the use of the standard layer based at 30 above grade.
Data observed at Station 2, from November 1969 through October 1970, were selected for the Primary Year of Record. There were gaps in this record caused by equipment malfunctions. To complete the record and eliminate a potential seasonal bias, 1971 data were added to it, thereby creating the Final Annual Record. These added data are limited to dates and hours of the day which coincide with the data gaps in the Primary Year of Record.
2.3.8.3 The Zero to Two-Hour Relative Concentration Determined by T and Parameters Relative concentrations for each hour of the final annual record have been calculated using the equations in Section 2.3.6.1 but with the uncertainties associated with measurements eliminated. y and z values were fixed by the Pasquill classes, as before. However, two sets of Pasquill Classes were defined; one set based upon the T measurements using the table in Section 2.3.8.2 and the other set using the measurements as recommended in Meteorology and Atomic Energy. All vertical dilution factors (z), plus those horizontal dilution factors (y) associated with wind speeds at 3 mph or less, were determined by the T Pasquill classes. The horizontal dilution factors (y) associated with winds greater than 3 mph were determined by the Pasquill Classes. On-shore and along shore wind directions were conservatively selected to include the nine sectors NW through SE, clockwise. The hourly relative concentration values occurring with these wind direction were ranked and placed in a cumulative frequency distribution in accordance with the accepted practice at coastal sites for evaluation of accident conditions as shown in Figure 2.3-7. The relative concentration which is exceeded only 5% of the time during the year is 1.3x10-4
CALVERT CLIFFS UFSAR 2.3-11 Rev. 47 seconds per cubic meter. In view of the very conservative nature of the 12 to 50 T data, as evidenced in Figure 2.3-6, and of the conservatism of the data as evidenced by a comparison with the concurrently observed sigma meter readings, this 5 percentile relative concentration value is conservative indeed.
It is concluded that, considering both the T and data observed at the Calvert Cliffs site, a relative concentration of 1.3x10-4 seconds per cubic meter is a very conservative value, and is appropriate for the 0-2 hour accident evaluations. This relative concentration is equivalent to a meteorological condition which may be defined as Pasquill E and a wind at 1.4 MPS.
Details of the concurrent values of wind speed and direction and T and Pasquill Classes for the Final Annual Record are presented in Figure 2.3-10, Sheets 1 through 14. The same data are presented in Figure 2.3-10, Sheets 13 through 28 except that the 1971 data observed after the Primary Year of Record have been omitted.
2.3.8.4 A Critique of the Data Record for the Independent Evaluation A calendar of data availability is presented in Table 2-30. It can be seen from this table that the Primary Year of Record, November 1969 through October 1970, provides the most complete 12-consecutive-month data record during the November 1969 through October 1971 period.
To fill in the data gaps which might be the cause of a seasonal bias in the Primary Year of Record, 1971 data coincident with the dates and times-of-day of the data gaps have been added in this Final Annual Record used in the analysis. A calendar of data in this Final Annual Record is presented in Figure 2.3-8, which shows the dates for which no data is available from November 1969 through October 1971. The sequence of overall data availability is presented in Figures 2.3-8 and 2.3-9.
The Final Annual Record data is quite complete with less than 10% missing observations; 8% occurring in consecutive-day lots, and 2% in periods of less than a day duration. The consecutive-day lots range from four to six days duration, occurring in January, April, August, and November. Because of the distribution of this missing data, it is very unlikely that it has contributed a seasonal or diurnal bias to the data record.
The data added to the Primary Year of Record to fill in its gaps, thereby producing the Final Annual Record, were added to ensure that a potential seasonal bias in the data record was eliminated. Data were added only to replace data lost because of equipment malfunctions, and they were only added to the extent that 1971 data, coincident with the dates and times-of-the-day of the equipment malfunction, were available. Although added data constitute 20% of the Final Annual Record, they could not create a bias in the record.
2.3.9 RECENT DATA COLLECTION The following sections summarize the meteorological studies that were conducted to obtain information for use in the design of the Diesel Generator Building for Diesel Generator 1A.
2.3.9.1 Strong Winds As illustrated in Reference 2, the average velocity for CCNPPs fastest mile of wind with a mean return period of 100 years is 100 mph. Reference 2 used
CALVERT CLIFFS UFSAR 2.3-12 Rev. 47 records of the fastest mile as published by the United States Weather Bureau from data obtained at airport stations.
2.3.9.2 Snow Storms Monthly snowfall depth data from the weather stations at Baltimore, Maryland (1958 to 1989) and the Patuxent River Naval Air Station, Lexington Park, Maryland (1976 to 1992) were used to estimate the 100-year ground snow pack level at the CCNPP site. Frequency analyses were performed on the monthly snowfall records for the months of December, January, February, March, and the combined snowfall total for the months of January and February. The snowfall total for the combined months of January and February, 59, was chosen to represent the 100-year snow pack on the ground.
2.3.10 REFERENCES
- 1.
Meteorology and Atomic Energy 1968, USAEC Division of Technical Information
- 2.
S. C. Hullister, The Engineering Interpretation of Weather Bureau Records for Wind Loading on Structures, Cornell University, Ithaca, NY
CALVERT CLIFFS UFSAR 2.3-13 Rev. 47 TABLE 2-10 FIRST YEAR ONSITE METEOROLOGICAL STATIONS AND INSTRUMENTATION CALVERT CLIFFS NUCLEAR POWER PLANT DESIGNATION LOCATION ELEVATION PERIOD INSTRUMENTATION Station 1(a)
"N1W" North N11,916 E10,403 100 MSL
+10 Mast 09/14/67-11/11/68 Packard Bell (Beckman-Whitley, Inc.) Model K-100 with Quick-D Vane Wind System 09/14/67-11/15/67 Cassella Thermograph 12/14/67-11/11/68 Standard US Weather Bureau Rain and Snow Gauge Station 4 "S1W" Conoy South N8,400 E1,060,000 90 MSL
+50 Mast 11/09/67 Use Discontinued, Date Unknown Packard Bell Electronics Corporation (Beckman-Whitley, Inc.) Model K-101 with Quick-D Vane Wind System Station UT1 Upper N10,000 E8,162 120 MSL
+4 Shelter 11/15/67 to 12/31/68 Cassella Thermograph installed in standard US Weather Bureau Cotton-Region type shelter Station LT1 Lower N8,642 E9,590 40 MSL
+4 Shelter 11/15/67 to 12/31/68 Same as Station UT1 Test Site Camp Conoy N7,600 E1,055,000 N7,625 E1,000,000 40 MSL
+12 Masts 60 MSL 10/17/68 11/01/68 Meteorology Research, Inc. (MRI) Mechanical Weather Station Model 1072 with rain gauge; (2) MRI vector vane Sigma Meter Model 1053 and (3) MRI Mechanical Weather Station Model 1071 (a)
Temporary Location
CALVERT CLIFFS UFSAR 2.3-14 Rev. 47 TABLE 2-11 RESULTS OF 256 SIMULTANEOUS ONSHORE WINDS IN RAFT STUDY AS COMPARED TO CLASSICAL PASQUILL INVERSION CLASS VALUES SITE PASQUILL CLASS AVG.
(rad m/sec)
Ave. (m/sec)
AVERAGE (degrees)
Raft 0.434 4.23 (9.5 mph) 7.2 Station 4 (S1W) 0.492 3.41 (7.6 mph) 8.3 Classical "F" 0.044 1.00 (2.2 mph) 2.5 Classical "E" 0.175 2.00 (4.5 mph) 5.0
CALVERT CLIFFS UFSAR 2.3-15 Rev. 47 TABLE 2-12 ONSITE METEOROLOGICAL SYSTEMS AND INSTRUMENTATION CALVERT CLIFFS NUCLEAR POWER PLANT DESIGNATION LOCATION ELEVATION PERIOD INSTRUMENTATION Microwave Tower N9,770 E8,809 75 MSL
+40 & 125 & 220 8/8/73 - Fall 1993 125 & 200 MRI 2040 Wind Diffusion System 8/8/73 - Fall 1993 40, 125 & 200 Weathermeasure Corporation Aspirated Radiation Shields with Rosemount Sensors (Temperature Gradient System) 8/23/73 - Fall 1993 125 Weathermeasure Corporation Dewpoint System Meteorological Towers
- a. Primary Tower N10,560 E7,710 110 MSL
+33 & 197 1982 - Current 1982 - Current 1982 - Fall 1995 197 & 33 Wind Sensors 197 & 33 Temperature Sensors 33 Dewpoint Sensor
- b. Backup Tower N10,422 E7,709 110 MSL
+33 1982 - Current 2005 - Current 2005 - Current 0 Rain Gauge 33 Wind Sensor 33 Temperature Sensor Station 1 "K" Knoll N10,895 E10,435 48 MSL
+12 Mast 1/3/69 to 11/4/70 Meteorology Research, Inc. (MRI)
Mechanical Weather Station, Model 1072 Wind System with Precipitation Gauge Station 2 "IS" Inner South N9,530 E8,720 48 MSL
+12 Mast 1/9/69 to 1/12/70 MRI Mechanical Weather Station, Model 1071 2/11/69 to 2/20/69 MRI Vector Vane Sigma Meter Model 1053 48 MSL
+12 & 49.5 5/15/69 to 9/4/74 Temperature Gradient System, Packard Bell Corp. (Beckman-Whitley) Model 327 Aspirated Radiation Shields 48 MSL
+12 Mast 6/1/69 to 8/7/69 MRI 2040 Wind Diffusion System 48 MSL
+33 8/7/69 to 5/15/71 MRI 2040 Wind Diffusion System
CALVERT CLIFFS UFSAR 2.3-16 Rev. 47 TABLE 2-12 ONSITE METEOROLOGICAL SYSTEMS AND INSTRUMENTATION CALVERT CLIFFS NUCLEAR POWER PLANT DESIGNATION LOCATION ELEVATION PERIOD INSTRUMENTATION 48 MSL
+33 & 97 5/15/71 - 8/14/75 9/29/71 - 8/14/75 7/17/71 - 8/14/75 MRI 2040 Wind Diffusion System Temperature Gradient System. Weathermeasure Corp. Aspirated Radiation Shields with Rosemount Sensors Beckman-Whitley Model WS-101 Quick Vane Wind System 3/13/72 - 1/11/74 Gill Anemometer Bivane Station 3 "BW" Boundary West N12,375 E6,735 115 MSL
+10 Mast 1/9/69 to 1/11/70 MRI Mechanical Weather Station Model 1071 Station 4 "S1W" Conoy South N8,500 E10,550 90 MSL
+50 Mast
+12 & 49 Mast 1/10/69 to 5/13/75 This station was shut down for reworking during the summer of 1971. It was reactiviated 9/1/71.
Beckman-Whitley Model WS101 Wind System Packard Bell (Beckman-Whitley) Model 327 Aspirated Radiation Shields
CALVERT CLIFFS UFSAR 2.3-17 Rev. 47 TABLE 2-13 CUMULATIVE FREQUENCY DISTRIBUTION, PERCENT OF TOTAL OBSERVATIONS, FOR ON/ALONG-SHORE INVERSION WINDS STATION SPEED CLASS 1
2 3
4 meters/sec (K)
(IS)
(BW)
(S1W) 0.01 - 0.50 0.30%
2.52%
1.40%
0.55%
0.51 - 1.00 0.82 4.92 2.92 1.54 1.01 - 2.00 2.46 7.66 6.11 4.91 2.01 - 3.00 4.28 9.66 7.94 8.53 3.01 - 4.00 5.78 10.67 8.55 11.01 4.01 - 5.00 7.44 11.23 8.68 12.59 5.01 - 6.00 8.01 11.36 8.71 13.02 6.01 - 8.00 8.57 11.37 8.71 14.14 8.01 -10.00 8.87 11.37 8.71 14.17 10.01 8.98 11.37 8.71 14.17 8291a 8386a 8399a 6743a a
Number of valid observations in each record.
CALVERT CLIFFS UFSAR 2.3-18 Rev. 47 TABLE 2-14 LOW-FREQUENCY /Q VALUES FOR ON-ALONG SHORE INVERSION WINDS AT CALVERT CLIFFS NUCLEAR STATION
% LEVEL OF OCCURRENCE STUB (radian-M/sec) y (M)(1150M) z (M)(1150M)
/Q (0-2 hrs)
(sec/m3) 1
.097 59 24 1.89x10-4 2
.130 66 24 1.72x10-4 3
.158 74 24 1.56x10-4 4
.185 83 24 1.41x10-4 5
.208 92 24 1.29x10-4 6
.228 103 24 1.17x10-4 7
.243 110 24 1.09x10-4 8
.258 116 24 1.045x10-4 9
.273 124 24 9.85x10-5 10
.287 133 24 9.20x10-5
CALVERT CLIFFS UFSAR 2.3-19 Rev. 47 TABLE 2-15 THE FREQUENCY OF CONCURRENTLY OBSERVED T VALUES FROM THE 50-12 FT AND 97-12 FT LEVELS ABOVE GRADE 97-12 ft 50-12 ft T T
0.5
-0.4
-0.3
-0.2
-0.1 0
+0.1 0.2 0.3 0.4 0.5 0.6 0.7
+0.8 0.9 0.9 924 52 41 61 46 68 20 39 20 10 7
9 3
1 15
-0.8 12 8
5 5
3 3
0 1
0 0
0 2
1 1
0
-0.7 11 4
6 4
3 0
1 0
1 0
1 0
1 0
1
-0.6 19 6
9 8
1 3
0 1
1 2
1 3
0 2
6
-0.5 16 12 9
9 2
16 2
0 0
0 0
0 2
2 2
-0.4 14 16 11 8
3 21 6
4 2
0 1
0 2
1 3
-0.3 6
12 11 13 5
34 8
3 2
0 0
0 0
1 1
-0.2 4
4 3
9 2
12 6
2 1
0 0
1 1
0 2
-0.1 4
2 5
9 4
9 2
3 1
1 0
0 0
0 2
0 4
3 4
1 3
9 3
4 2
0 0
0 0
0 4
+0.1 3
1 5
1 1
4 1
6 2
0 1
1 1
0 3
0.2 0
0 0
4 0
3 2
2 2
0 1
0 1
0 5
0.3 0
0 0
1 0
0 2
1 3
1 1
0 0
1 6
0.4 0
0 0
0 0
3 0
2 1
2 1
1 0
0 2
0.5 1
1 0
0 0
0 1
3 1
1 1
1 0
0 6
0.6 1
0 1
3 1
3 1
2 2
0 2
1 1
1 10 0.7 0
0 1
0 0
2 1
1 0
0 0
0 0
0 6
0.8 1
0 0
0 0
0 0
0 1
0 0
5 0
2 5
0.9 0
0 0
0 0
1 2
1 1
3 1
0 1
1 5
1.0 0
0 0
1 0
0 0
0 0
1 3
0 1
1 7
1.1 0
0 1
0 0
1 0
1 0
0 0
1 2
0 9
1.2 0
0 0
0 0
0 0
1 1
0 0
0 1
2 5
1.3 0
0 0
0 0
0 0
1 0
2 0
0 0
2 8
1.4 0
0 0
0 0
0 0
0 0
1 1
1 0
0 5
1.5 0
0 0
1 0
0 0
0 0
0 1
0 0
0 6
1.6 0
0 0
0 0
0 0
1 0
0 2
2 1
0 7
1.7 0
0 0
0 0
0 0
0 0
0 1
0 0
1 8
1.8 0
0 0
0 0
0 0
0 0
0 0
0 1
0 6
1.9 0
0 1
2 1
5 3
1 3
0 7
4 12 7
215 Observations were made between May 14, 1971 and September 29, 1971.
Tables 2-16 through 2-29 were deleted, see Figure 2.3-10.
CALVERT CLIFFS UFSAR 2.3-20 Rev. 47 TABLE 2-30 CALENDAR OF METEOROLOGICAL DATA AT STATION 2 FROM NOVEMBER 1969 THROUGH OCTOBER OF 1971 Number of Days with 12 or more hours of valid data.
PARAMETER NOV 69 DEC 69 JAN 70 FEB 70 MAR 70 APR 70 MAY 70 JUN 70 JUL 70 AUG 70 SEP 70 OCT 70 T
23 30 24 28 31 14 20 30 31 28 30 28 Wind Dir 27 31 31 28 31 30 31 26 31 27 8
0 Sigma Theta 27 31 31 28 31 30 31 26 31 27 8
0 Wind Speed 30 31 31 27 31 30 31 26 31 27 15 4
All 23 30 24 27 31 14 20 26 31 24 8
0 Running 12-Month Totals T
317 Wind Dir 301 Sigma Theta 301 Wind Speed 314 All 258 PARAMETER NOV 70 DEC 70 JAN 71 FEB 71 MAR 71 APR 71 MAY(a) 71 JUN 71 JUL 71 AUG 71 SEP 71 OCT 71 T
30 27 30 28 30 30 31 20 30 24 30 29 Wind Dir 14 14 26 28 20 19 28 20 26 25 30 29 Sigma Theta 14 14 26 28 20 19 28 20 26 25 30 29 Wind Speed 21 31 22 26 20 19 28 28 29 24 27 29 All 8
12 16 26 19 19 28 17 25 16 27 29 Running 12-Month Totals T
324 321 327 327 326 343 354 344 343 339 339 340 Wind Dir 288 271 266 266 255 244 241 235 230 228 250 279 Sigma Theta 288 271 266 266 255 244 241 235 230 228 250 279 Wind Speed 305 305 296 295 284 273 270 272 270 267 279 304 All 243 225 217 216 204 209 217 208 202 194 213 242 (a)
Much of the wind data from May through September 1971 was observed at 100 above grade.