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Page 1 of 17 DSAR-2.5 Site and Environs Meteorology Rev 2 Safety Classification:
Usage Level:
Safety Information Change No.:
EC 70091 Reason for Change:
Remove EOF and TSC from DSAR Preparer:
J. Carlson Fort Calhoun Station
DSAR-2.5 Information Use Page 2 of 17 Meteorology Rev. 2 Table of Contents 2.5 Meteorology............................................................................................................. 4 2.5.1 General Climate........................................................................................ 4 2.5.2 Local Meteorology.................................................................................... 4 2.5.2.1 Wind Direction and Speeds......................................................... 4 2.5.2.2 Precipitation................................................................................. 4 2.5.2.3 Temperatures.............................................................................. 5 2.5.2.4 Relative Humidity........................................................................ 5 2.5.2.5 Thunderstorms............................................................................ 5 2.5.2.6 Atmospheric Stability................................................................... 5 2.5.2.7 Topographical Description and Its Influence on Site Meteorology6 2.5.2.8 Tornadoes................................................................................... 6 2.5.3 Meteorological Monitoring Program.......................................................... 7 2.5.3.1 Preoperational and Initial Monitoring Program............................ 7 2.5.3.2 Permanent Meteorological Monitoring Program.......................... 7 2.5.4 Accident Diffusion Estimates.................................................................... 8 2.5.5 Design Basis Accident Atmospheric Dispersion Factors (/Q)................. 8
DSAR-2.5 Information Use Page 3 of 17 Meteorology Rev. 2 List of Tables Table 2.5 Climatological Normals, Comparison of North Omaha NWS with Fort Calhoun Station
........................................................................................................................................ 10 Table 2.5 Maximum Recorded and Mean Wind Speeds (MPH)....................................... 11 Table 2.5 Normal and Extreme Precipitation Amounts (Inches)....................................... 12 Table 2.5 Normal and Extreme (Maximum) Snow and Ice Pellet Amounts (Inches)........ 13 Table 2.5 Normal and Extreme Temperatures (F).......................................................... 14 Table 2.5 Monthly and Annual Temperature Normals (°F)............................................... 15 Table 2.5 Comparative Relative Humidity Values for Eppley Airfield (1964-1990), North Omaha (N.O.) (1984-1990), and Fort Calhoun (1969-1975)....................................................... 16 Table 2.5 Mean Number of Days with Heavy Fog (Visibility 1/4 Mile or Less).................. 17 Table 2.5 Mean Number of Days with Thunderstorms..................................................... 17
DSAR-2.5 Information Use Page 4 of 17 Meteorology Rev. 2 2.5 Meteorology 2.5.1 General Climate The general climate is classified as continental, i.e., hotter in summer and colder in winter than in lands near the ocean. Nebraska is located midway between two distinctive climatic zones, the humid east and the dry west(4). Thus, cyclic weather conditions representative of either zone, or combinations of both occur. Changes in weather result from the invasion of large masses of air with dissimilar properties.
These air masses tend to get their characteristics from either the warm and humid south-southeast, the warm and dry southwest, the cool and dry north-northwest, or the cold continental polar air of the north(6). The region is also affected by many storms or cyclones (areas of low pressure) which travel across the country, generally from west to east. Thus, periodic and rapid changes in the weather are normal, especially in the winter(3).
2.5.2 Local Meteorology Data from proximal long-term National Weather Service (NWS) Stations have been used to supplement the existing Fort Calhoun Station data in formulating the description of the local meteorology.
2.5.2.1 Wind Direction and Speeds A comparison of the climatological normals for the North Omaha NWS and five years of data from the Fort Calhoun Station has been archived in Table 2.5-1. The elevation of the North Omaha NWS wind sensor was 20 feet above ground during the five-year period, while the elevation of the Fort Calhoun wind sensor was 10 meters above ground. Further discussion on the on-site data for wind direction and speed is presented below in Section 2.5.2.6.
The mean and maximum wind speeds recorded at Eppley Airfield and the North Omaha NWS for each month of the year are archived in Table 2.5-2.
2.5.2.2 Precipitation Monthly and annual normal and extreme precipitation amounts for Eppley Airfield and the North Omaha NWS are archived in Table 2.5-3.
Average monthly precipitation follows a seasonal trend, reaching a maximum in May and a minimum in January. The mean number of days with measurable precipitation varies between a 12-day maximum in May to a 5-day minimum in November. The normals and extremes for amounts of snow and ice pellets (including sleet) for Eppley Airfield and the North Omaha NWS are archived in Table 2.5-4.
DSAR-2.5 Information Use Page 5 of 17 Meteorology Rev. 2 2.5.2.3 Temperatures The monthly temperatures at Eppley Airfield and the North Omaha NWS for the period 1961 through 1990 are archived in Table 2.5-5.
This table also shows the record high and record low temperatures recorded at both locations through 1990. Annual extremes have been received at other locations in the Omaha vicinity as follows: a record high of 114°F in July, 1936, and a record low of -32°F in January, 1885(4).
Monthly and annual temperature normals for Eppley Airfield, North Omaha NWS and Blair are archived in Table 2.5-6(4). These show close agreement.
2.5.2.4 Relative Humidity The average relative humidity values for Eppley Airfield, the North Omaha NWS, and the Fort Calhoun Station for four times of the day are archived in Table 2.5-7. The mean number of days with heavy fog (visibility 3 mile or less) at Eppley Airfield and the North Omaha NWS are archived in Table 2.5-8.
2.5.2.5 Thunderstorms The mean number of days with thunderstorms at Eppley Airfield and the North Omaha NWS are archived in Table 2.5-9. A maximum frequency of approximately 9.5 thunderstorms occur during the month of June.
This decreases to a minimum of approximately 0.1 thunderstorms during the month of January.
2.5.2.6 Atmospheric Stability Wind direction and speed data are presented in relative frequency distribution (in percent) by stability classes. The data covers the periods of January 1, 1994, through December 31, 1998, and are contained in FC06806.46
DSAR-2.5 Information Use Page 6 of 17 Meteorology Rev. 2 2.5.2.7 Topographical Description and Its Influence on Site Meteorology The terrain in the vicinity of Fort Calhoun Station is generally flat from the north, northeast, east and southeast sectors, with an elevation of approximately 1000 feet above mean sea level (msl), for a radius of at least 10 miles. This terrain is generally the flood plain of the Missouri River. Terrain in the remaining sectors, south-southeast through west-northwest, show much greater relief from the low lying bluffs, cut by numerous ravines, with elevations of about 1300 feet above msl.
These bluffs extend along the western bank of the Missouri River, which runs generally from the northwest to the southeast, and come within about one mile of the Fort Calhoun Station in the south through west-southwest sectors.
Two unusual effects in the site meteorology are: 1) under very light westerly wind flow there is a possibility of weak drainage flow off the bluffs to the west toward the river, and 2) there will possibly be a slowing down of weak winds as air flows across the river from east to west and meets the rising terrain to the west. However, neither of these effects are regarded as significant in their influence on site meteorology and should not, under most synoptic weather types, severely skew the strong measures of covariation (+0.75 to +1.00) which exist between the site and other meteorological stations.
2.5.2.8 Tornadoes DSAR, Appendix G, Criterion 2, Performance Standards requires the facility to be designed so that the plant can be safely maintained in a safe defueled condition during a tornado.
The physical design parameters of tornado protection systems are such that designated SSCs are able to maintain their necessary capabilities in the event of a Design Basis Tornado (DBT). Amendment 272(37) revised the DBT and associated tornado missiles for Fort Calhoun Station (FCS) to that defined in Regulatory Guide (RG) 1.76, Revision 1(38). This ensures that designated SSCs are adequately protected from the DBT and associated tornado missiles.
Tornado Missiles The physical properties and velocities of tornado generated missiles are described in Regulatory Guide 1.76, Revision 1.
DSAR-2.5 Information Use Page 7 of 17 Meteorology Rev. 2 2.5.3 Meteorological Monitoring Program 2.5.3.1 Preoperational and Initial Monitoring Program The preoperational meteorological program was designed to measure the parameters needed to evaluate the dispersion characteristics of the plant site for the evaluation of the consequences of routine operations and of hypothetical accidental releases of radionuclides to the atmosphere. The on-site data acquisition program was begun in June, 1967, by Omaha Public Power District at the Fort Calhoun Station site. Initially, a climatological station was instrumented with standard-type Weather Bureau quality instruments for recording temperature (thermograph), relative humidity (hygrothermograph),
precipitation (rain gauge), barometric pressure (barograph), and wind.
The wind system, a Meteorology Research, Inc. (MRI) mechanical weather station (MWS), was installed atop a 40-foot fold tower at a location adjacent to the Missouri River and slightly south-southeast of the reactor centerline. This tower was operable, producing valid data, until June, 1977.
2.5.3.2 Permanent Meteorological Monitoring Program The Fort Calhoun Station has a permanent 110M meteorological tower with appropriate meteorological measurements system. Real-time and historical data is available from the plant computer system (ERFCS).
This data can be accessed and displayed in the control room.
Additional transmittal of meteorological data on or off-site may be by radio, telephone, computer, or by calling the control room.
In accordance with NUREG-0654, (28) NUREG-0696, (29) and GL 82-33, (30, 32) the weather tower provides data for those meteorological variables specified in the 1st Proposed Revision 1 of RG 1.23. Calculation FC06247 (34) was completed for Modification MR-FC-89-057, (35) which replaced the existing meteorological monitoring system with a microprocessor based data acquisition system. The weather tower meets the intent of Safety Guide 23 with exceptions for instrument accuracy and remote interrogation.
Representative backup wind speed and direction data can be obtained from Offutt Airforce Base or through the National Weather Service, Valley location with data taken at the Blair Municipal Airport.
DSAR-2.5 Information Use Page 8 of 17 Meteorology Rev. 2 2.5.4 Accident Diffusion Estimates Accidents could result in releases of radioactivity from several possible releasing points (i.e., auxiliary building venting, radwaste processing venting etc.) of plant structures. Atmospheric dispersion factors (/Q) based on site meteorological data are calculated in FC0680747 for various downwind distances for time periods of 1, 8, 16, 72 and 624 hours0.00722 days <br />0.173 hours <br />0.00103 weeks <br />2.37432e-4 months <br />, corresponding to sequential release, presumed to occur during periods of 0 to 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />, 0 to 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />, 8 to 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, 1 to 4 days, and 4 to 30 days as prescribed by Regulatory Guide 1.4.(9) 2.5.5 Design Basis Accident Atmospheric Dispersion Factors (/Q)
Site Boundary Atmospheric Dispersion Factors For implementation of the Alternative Source Term (AST) to be used in all design basis site boundary and control room dose analyses, normalized atmospheric dispersion (/Q) values were calculated under FC0680848 and submitted to the USNRC for the FCS Exclusion Area Boundary (EAB) and Low Population Zone (LPZ)(16). Site boundary atmospheric dispersion factors were reassessed in the year 2001 for post accident gaseous releases from the containment wall, auxiliary building stack, auxiliary building fresh air intake, main steam safety valve (MSSV)/atmospheric dump valve (ADV) stacks,and radwaste processing building ventilation discharge nozzle, room 81 pressure relief domes, the condenser evacuation discharge, and the turbine discharge point of the turbine driven auxiliary feedwater pump. Also control room atmospheric dispersion factors were calculated in support of AST. Further details about AST are found in DSAR Section 14.1.
The site boundary and control room atmospheric dispersion factors calculated and detailed in the DSAR shall be used for all future design basis post accident gaseous release analyses. The applicable methodology is identified in US Nuclear Regulatory Commission Regulatory Guide (RG) 1.145.
DSAR-2.5 Information Use Page 9 of 17 Meteorology Rev. 2 The RG 1.145 methodology for ground level sources is as follows and is documented in Reference 16:
/Q1 = {(u)[()(y(z) + (A/2)]}-1
/Q2 = [(u)(3)(y)(z)]-1
/Q3 = [(u)()(y)(z)]-1 where:
y
=
(M)(y); with M representing the meander factor in RG 1.145
/Q
=
the relative concentration (sec/m3) y, z =
horizontal and vertical dispersion coefficients, respectively, based on stability class and horizontal downwind distance (m) u
=
wind speed at the 10-meter elevation (m/sec)
A
=
cross sectional building area (m2)
Reference 16 discusses comparison of the calculated /Q values.
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Table 2.5 Climatological Normals, Comparison of North Omaha NWS with Fort Calhoun Station WIND DIRECTION (PERCENT)
WIND SPEED (MPH)
Wind Direction North Omaha NWS (1985-1989)
Fort Calhoun (1985-1989)
North Omaha NWS (1985-1989)
Fort Calhoun (1985-1989)
NNE 3.8 2.6 8.2 4.9 NE 3.3 2.4 6.9 4.6 ENE 3.2 2.4 6.5 4.5 E
3.1 3.1 6.7 5.0 ESE 5.4 5.7 6.8 5.4 SE 7.1 9.0 7.8 6.8 SSE 10.0 10.2 9.9 8.9 S
10.8 10.1 10.4 9.5 SSW 9.1 7.2 9.5 9.3 SW 4.3 3.7 8.5 7.5 WSW 2.4 3.0 7.2 5.5 W
3.9 4.5 7.7 4.4 WNW 5.3 7.6 10.1 4.6 NW 8.6 10.7 12.9 6.6 NNW 6.8 9.4 12.8 6.5 N
13.0 5.5 8.0 5.9 Missing 2.9 2.9 Average 8.7 6.3 NOTE: The wind speeds at the North Omaha NWS were recorded 20 feet above ground level, and the wind speeds at Fort Calhoun Station were recorded at 10 meters, above ground level. Data obtained from the Local Climatological Data; see References 4 and 5.
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Table 2.5 Maximum Recorded and Mean Wind Speeds (MPH)
EPPLEY AIRFIELD NORTH OMAHA NWS Period Fastest Wind Speed (1949-1990)
Direction (Degrees)
Year Mean (1936-1990)
Fastest Wind Speed (1979-1990)
Direction (Degrees)
Year Mean (1985-1990)
January 57 NW 1938 10.9 41 NW 1978 10.4 February 57 NW 1947 11.1 38 NW 1978 9.6 March 73 NW 1950 12.3 38 NW 1982 10.9 April 65 NW 1937 12.7 46 NW 1982 10.6 May 73 NW 1936 10.9 34 N
1983 8.9 June 72 N
1942 10.1 34 NW 1983 8.4 July 109 N
1936 8.9 46 NW 1980 7.5 August 66 N
1944 8.9 39 NW 1980 7.7 Septembe r
47 E
1948 9.5 35 NW 1980 8.4 October 62 NW 1966 9.8 34 NW 1979 8.9 November 56 NW 1951 10.9 38 NW 1982 9.9 December 52 NW 1938 10.7 37 NW 1981 9.9 Year 109 N
1936 10.6 46 NW 1982 9.3 NOTE: The wind speeds at Eppley Airfield were recorded at 70 feet above ground level (agl) until 1974; 20 feet agl since that time. The wind speeds at the North Omaha NWS were recorded at 20 feet agl. Data obtained from the Local Climatological Data; see References 4 and 5.
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Table 2.5 Normal and Extreme Precipitation Amounts (Inches)
EPPLEY AIRFIELD (1936-1990)
NORTH OMAHA (1954-1990)
Period Monthly Normal Monthly Maximum Year Monthly Minimum Year 24-Hour Maximum (1942-1990)
Year Monthly Normal Monthly Maximum Year Monthly Minimum Year 24-Hour Maximum (1977-1990)
Year January 0.77 3.70 1949 Trace 1986 1.52 1967 0.70 1.85 1975 Trace 1986 0.95 1982 February 0.91 2.97 1965 0.09 1981 2.24 1954 0.95 2.86 1965 0.09 1968 0.64 1978 March 1.91 5.96 1973 0.12 1956 1.45 1990 2.00 5.27 1983 0.06 1956 2.04 1982 April 2.94 6.45 1951 0.23 1936 2.56 1938 2.74 7.12 1984 0.15 1962 2.59 1986 May 4.33 10.33 1959 0.56 1948 4.16 1987 4.26 9.09 1959 0.55 1989 3.10 1987 June 4.08 10.81 1947 1.03 1972 3.48 1942 4.21 8.16 1984 0.95 1972 2.77 1988 July 3.62 9.60 1958 0.39 1983 3.37 1958 3.50 9.77 1958 0.29 1975 3.72 1977 August 4.10 10.16 1982 0.61 1984 5.27 1987 4.19 11.77 1960 0.63 1971 3.74 1987 September 3.50 13.75 1965 0.41 1953 6.47 1965 3.36 14.10 1965 0.96 1990 2.77 1989 October 2.09 4.99 1961 Trace 1952 3.13 1968 2.11 5.34 1986 0.06 1958 2.61 1986 November 1.32 4.70 1983 0.03 1976 2.53 1948 1.16 5.11 1983 0.03 1989 2.16 1983 December 0.77 5.42 1984 Trace 1943 3.03 1984 0.76 4.45 1984 0.02 1958 3.10 1984 Year 30.34 13.75 1965 Trace 1986 6.47 1965 29.94 14.10 1965 Trace 1986 3.74 1987 NOTE: Data obtained from the Local Climatological Data; see References 4 and 5.
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Table 2.5 Normal and Extreme (Maximum) Snow and Ice Pellet Amounts (Inches)
EPPLEY AIRFIELD (1936-1990)
NORTH OMAHA (1954-1990)
Period Normal Monthly Maximum Year 24-Hour Maximum (1942-1990)
Year Normal Monthly Maximum Year 24-Hour Maximum (1976-1990)
Year January 7.3 25.7 1936 13.1 1949 7.0 21.5 1975 6.0 1979 February 6.8 25.4 1965 18.3 1965 6.7 23.2 1965 10.0 1978 March 6.6 27.2 1948 13.0 1948 7.2 23.3 1960 13.3 1987 April 0.8 8.6 1945 8.6 1945 1.2 10.3 1983 4.8 1979 May 0.1 2.0 1945 2.0 1945 Trace 0.7 1967 0.0 June Trace Trace 1990 Trace 1990 0.0 0.0 0.0 July 0.0 0.0 0.0 0.0 0.0 0.0 August 0.0 0.0 0.0 0.0 0.0 0.0 September Trace Trace 1985 Trace 1985 Trace 0.3 1985 0.3 1985 October 0.3 7.2 1941 7.2 1941 0.4 5.2 1980 5.2 1980 November 2.5 12.0 1957 8.7 1957 3.2 13.9 1957 8.5 1983 December 5.7 19.9 1969 10.2 1969 5.5 19.3 1969 7.5 1984 Year 30.0 27.2 1948 18.3 1965 31.3 23.3 March 1960 13.3 March 1987 NOTE: Data obtained from the Local Climatological Data: see References 4 and 5.
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Table 2.5 Normal and Extreme Temperatures (F)
EPPLEY AIRFIELD NORTH OMAHA (1961-1990)
(1936-1990)
(1961-1990)
(1954-1990)
Period Daily Maximum Daily Minimum Monthly Normal Record High Year Record Low Year Daily Maximum Daily Minimum Monthly Normal Record High Year Record Low Year January 31.1 12.7 21.9 69.0 1944
-23.0 1982 29.3 11.1 20.2 66 1981
-22 1982 February 35.8 17.1 26.5 78.0 1972
-21.0 1981 34.3 16.0 25.1 76 1972
-20 1981 March 47.5 27.8 37.7 89.0 1986
-16.0 1948 46.4 26.9 36.7 88 1986
-16 1960 April 62.4 41.1 51.8 97.0 1989 5.0 1975 60.2 38.6 49.4 96 1989 7
1975 May 73.0 52.2 62.6 99.0 1939 27.0 1980 70.6 50.0 60.3 100 1967 25 1967 June 82.5 61.9 72.2 105.0 1953 38.0 1983 81.6 60.9 71.3 104 1988 41 1956 July 87.7 67.1 77.4 114.0 1936 44.0 1972 85.9 66.0 76.0 107 1974 44 1971 August 85.2 64.9 75.1 110.0 1936 43.0 1967 83.8 63.8 73.8 106 1983 44 1986 September 76.9 55.6 66.3 104.0 1939 25.0 1984 74.9 54.3 64.6 103 1955 28 1984 October 65.5 43.7 54.6 96.0 1938 13.0 1972 64.0 42.7 53.4 93 1975 16 1972 November 48.6 29.6 39.1 80.0 1980
-9.0 1964 47.4 28.7 38.1 79 1980
-11 1964 December 35.6 18.4 27.0 72.0 1939
-23.0 1989 33.8 16.4 25.1 66 1976
-25 1989 Year 61.0 41.0 51.0 114.0 1936
-23.0 1989 59.3 39.6 49.5 107 1974
-25 1989 NOTES: 1. Data obtained from the Local Climatological Data; see References 4 and 5.
- 2. At the time of containment design/construction the lowest recorded temperature at Eppley Airfield was -22.0°F (January 1974).
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Table 2.5 Monthly and Annual Temperature Normals (°F)
Period Eppley Airfield (1936-1990)
North Omaha NWS (1954-1990)
Blair (1941-1970)
January 20.2 18.7 20.8 February 27.2 25.3 26.0 March 37.3 35.2 35.2 April 52.2 50.4 50.9 May 63.3 61.7 61.5 June 73.0 71.2 70.8 July 77.7 75.7 75.5 August 75.2 73.5 73.9 September 65.8 64.4 64.3 October 54.5 53.6 54.8 November 39.5 38.0 38.7 December 27.2 25.7 26.6 Year 51.1 49.5 49.9 NOTE: Data obtained from references 4 and 5.
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Table 2.5 Comparative Relative Humidity Values for Eppley Airfield (1964-1990), North Omaha (N.O.) (1984-1990), and Fort Calhoun (1969-1975) 0000*
0600*
1200*
1800*
24 Hour Average Period Eppley N.O.
Ft.
Calhoun Eppley N.O.
Ft.
Calhoun Eppley N.O.
Ft.
Calhoun Eppley N.O.
Ft.
Calhoun Eppley N.O.
Ft.
Calhoun January 75 70 82 78 74 83 65 60 71 66 60 76 70 66 78 February 76 71 82 79 75 84 63 61 70 63 62 72 70 67 77 March 72 69 80 78 77 84 57 57 66 54 54 65 65 64 74 April 68 65 72 77 75 80 52 51 59 48 46 54 62 60 66 May 72 69 75 80 78 83 54 54 61 51 51 54 64 63 68 June 75 68 75 82 77 83 55 54 59 52 50 52 66 62 67 July 78 75 77 84 83 83 57 60 60 55 57 56 69 69 69 August 80 79 82 86 87 88 59 62 65 58 61 58 71 72 75 September 81 77 82 87 84 88 59 60 65 59 60 60 72 70 74 October 76 69 79 82 78 87 55 55 65 56 56 63 67 65 74 November 76 72 85 81 77 88 62 61 72 65 64 77 71 69 80 December 78 73 84 80 76 87 67 66 74 71 69 80 74 71 81 Year 76 71 80 81 78 85 59 58 66 58 58 64 69 66 74
- Local Standard Time NOTE: Data obtained from the Local Climatological Data; see References 4 and 5. Fort Calhoun data obtained from PSAR and archived meteorological data files.
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Table 2.5 Mean Number of Days with Heavy Fog (Visibility 1/4 Mile or Less)
Table 2.5 Mean Number of Days with Thunderstorms Period Eppley Airfield (1935-1990)
North Omaha NWS (1975-1990)
Period Eppley Airfield (1935-1990)
North Omaha NWS (1975-1990)
January 1.8 1.2 January 0.1 0.1 February 1.9 2.1 February 0.4 0.4 March 1.4 2.5 March 1.5 1.9 April 0.5 0.6 April 3.8 3.4 May 0.8 0.8 May 7.4 7.7 June 0.4 0.6 June 9.4 9.5 July 0.5 0.3 July 8.2 8.8 August 1.5 1.1 August 7.8 8.1 September 1.4 0.9 September 5.3 6.0 October 1.5 1.1 October 2.4 2.3 November 1.6 1.9 November 0.8 0.7 December 2.1 2.7 December 0.2 0.2 Year 15.4 15.8 Year 47.2 49.0