ML20209D501
| ML20209D501 | |
| Person / Time | |
|---|---|
| Site: | Satsop |
| Issue date: | 10/31/1984 |
| From: | Muller D Office of Nuclear Reactor Regulation |
| To: | Novak T Office of Nuclear Reactor Regulation |
| References | |
| CON-WNP-1355 NUDOCS 8411140056 | |
| Download: ML20209D501 (12) | |
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-m ADRP RF Docket No.: 50-508 GCT 311984 MEHORANDUM FOR: Thomas H. Novak, Assistant Director for Licensing, DL FROM:
Daniel R. Muller, Assistant Director for Radiation Protection, DSI
SUBJECT:
METEOROLOGY SECTION INPUT TO DRAFT SER FOR WNP-3 Enclosed is the meteorology input (Section 2.3) to the Draft SER for the WNP-3 Generating Station. The only areas of concern are the extreme ambient temperatures considered in the design of safety-related auxiliary systems and components.
This evaluation was performed by J. Levine, and any questions should be directed to him at x29433.
Because of our heavy workload, the Effluent Treatment Systems Section input to tne draft SER will be provided when a schedule is provided for the draft SER.
Cr:ginal signed by DanielR. Muller ;
Daniel R. Muller, Assistant Director for Radiation Protection Division of Systems Integration l
Enclosure:
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WASHINGTON PUBLIC POWER SUPPLY SYSTEM, UNIT NO. 3 INPUT TO SER 9
2.3 Meteorology Evaluation of regional and local climatological information, including extremes of climate and severe weather occurrences which may affect the design and siting of a nuclear plant, is required to assure that the plant can be designed and operated within the requirements of Commission regulations.
Information concerning atmospheric diffusion characteristics of a nuclear power plant site is required for a determination that radioactive effluents from postulated accidental releases, as well as routine operational releases, are within Commission guidelines. Sections 2.3.1 through 2.3.5 have been prepared in accord-ance with the review procedures described in the Standard Review Plan (NUREG-0800), utilizing information presented in Section 2.3 of the FSAR, responses to requests for additional information, and generally available reference materials as described in the appropriate sections of the Standard Review Plan.
2.3.1 Regional Climatology The plant is located in southwest Washington on a ridge near the eastern shore of the Pacific Ocean and in a maritime type of climate.
Maritime air masses dominate the region year round. The mean annual 0
0 temperature in the area is about 10 C (50 F) ranging from about 2.9 C pm::c u m oc c Ga1.s
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f, (37.2 F) in January to about 17.6 C (63.6 F) in July. Annual precipitation in the area is about 1270 mm (50 inches).
l The movement of weather systems from the Pacific Ocean over the site maintains considerable cloudiness and nearly constant rainfall due to t
lifting of this moist air over the mountains in this area of Washington.
Severe weather phenomena which affect the site area include about 5 thunderstorms per year which can be expected on about 5 days each year.
Thunderstorms occur primarily in spring and sumer. Considering the small frequency of thunderstorms, the applicant has estimated the number of lightning strikes to the square kilometer containing the plant to be 1.1 per year. Hail does not usually occur with the thunderstorms and is not a significant phenomena.
Tornadoes are not comon in the region. For a two degree 2
latitude-longitude " square"j33127 square kilometers (12791 miles )
containing the site, 5 tornadoes were reported for the period 1954-1981.
Using an observed tornado path area of.088 square Km (.034 sq. mi.),
the computed probability of occurrence for a tornado at the plant site is about 4.9 x 10-7 per year. The' applicant has followed the recomendations of Regulatory Guide 1.76, " Design Basis Tornado for t
Nuclear Power Plants," for this region of the country. The applicant's design basis tornado for category I structures has a 107m/s (240 mph) rotational velocity with a translational velocity of 27m/s (60 mph), a
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total pressure drop of 2.25 psi and an average rate of pressure drop of 1.2 psi in 1 second. The tornado winds and total pressure drop are consistent with Regulatory Guide 1.76 for the site area.
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.O High wind speed occurrences in the area are usually associated with severe thunderstoms and intense extratropical cyclones. The highest
" fastest mile" wind speed reported at Olympia, WA was 27m/s (60 Inph) in November 1958. The applicant has selected an operating basis wind speed (defined as the " fastest mile" wind speed at a height of 9.lm (30 feet) i with a return period of 100 years) to be 46.9 m/s (105 mph) for consideration in plant design.
Since the ultimate heat sink for the plant is a dry cooling tower, meteorological conditions related to extreme temperature and wind speed are relevant to determination of the adequacy of the tower to perform its function for a 30 day period. A maximum hourly temperature of 0
U 38.6 C (101.5 F) was used for design of the plant ultimate heat sink, dry cooling towers. This temperature was statistically determined to be the 40 year maximum hourly average temperature by correlating short term site data with the same period at Elma, WA. Based upon this statistical analysis the maximum hourly average temperature in 40 years at Elma, WA of 40.6C (105 F) was converted to a maximum hourly average temperature onsite for the 40 year period of 38.6 C (101.5 C). This estimate of the long-term maximum temperature is reasonable and is therefore a conservative basis for the design of the dry cooling towers thereby satisfying the intent of Regulatory Guide 1.27 for 30 day cooling capability. Heavy snowfall is not common in the region; roof loads may accumulate due to a wintertime precipitation comprised primarily of a mixture of snow and rain. Maximum monthly snowfall observed at Olympia was 521 mm (20.5 inches) in January 1972 which was also the maximum snowfall in a 24-hour period.
Ice storms, which can plug drains and
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4 scuppers as well as disrupt offsite power, are relatively infrequent.
The estimate of the snowpack based on ANSI 58.1-1982, extrapolated from the 50-year return period in the standard to a 100-year return period, produces a weight of less than 15 psf. This snowpack weight, when added to the weight produced by the 48-hour probable maximum winter
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precipitation produces a load of less than the design snowload of 80 psf, which was utilized in the design combined snow and ice load of
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Category I structures. During the 5 year period 1960-1964, about 41 atmospheric stagnation cases defined as persisting for two days or longer totaling at least 164 days were reported in the area.
As discussed above, the staff has reviewed available information relative to the regional meteorological conditions of importance to the safe design and siting of this plant in accordance with the criteria contained in Section 2.3.1 of the Standard Review Flan. Based on this review, the staff concludes that the applicant has identified appropriate regional meteorological conditions for consideration in the design and siting of this plant. The applicant has met the requirements of 10 CFR Part 100.10 and 10 CFR Part 50, Appendix A, General Design Criterion 2.
Th'e design basis tornado characteristics selected by the applicant confc,rm to the position set forth in Regulatory Guide 1.76,
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and, therefore, meet the requirement of 10 CFR Part 50, Appendix A, I
General Design Criterion 4 to determine an acceptable design basis tornado for missile generation.
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2.3.2 Local Meteorology l
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Climatological data from Olympia, WA, and nearby climatological cooperative stations and available onsite data have been used to assess local meteorological characteristics of the plant site.
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Extreme temperatures of -22.2 C (-8 F) and 40.6 C (1.05 F) have been a
reported in the area. The applicant has considered a summer outdoor design temperature of 28.3 C (83 F) and a winter minimum temperature of 4.4 C (40 F) in the design of all heating, ventilation and air 0
conditioning (HVAC) systems to maintain a 23.9 C (75 F) control room area temperature during normal or accident conditions. Regional analyses in NUREG/CR-1390, " Probability Estimates of Temperature Extremes for the Contiguous United States" show that an ambient temperature of 35 C (95 F) will be exceeded for at least one hour every two years, on the average, and that an ambient temperature of about 42.2 C (108 F) will be exceeded at least one hour every 100 years, on U
the average. Also, an ambient temperature of less than -8.9 C (16 F) is expected to occur for at least one hour every two years, on the average, 0
and-an ambient temperature of less than -22 C (-8 F) is expected to occur for at least one hour every 100 years, on the average. Further justification of the adequacy of the ambient extreme temperatures l
considered by the applicant for the design of HVAC systems protecting safety-related auxiliary systems and components is required. This will l
be an open issue only if exceedence of extreme design temperatures for the HVAC system results in failure or malfunction of Category I auxiliary systems and components, which is being evaluated by the Auxiliary Systems Branch.
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Precipitation is observed throughout the year, ranging from over 203 mm (8 inches)'in December to less than 25 mm (1 inch) in July. Maximum and
~ inimum monthly amounts of precipitation observed at.0lympia have been m
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504 mm (19.8 inches) in January 1953 and 0 mm (0 inches) in August 1946, l
respectively. The maximum amount of precipitation in a 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> period at Olympia was 125 nm (4.93 inches) in February 1951.
Average annual precipitation at Olympia is about 1290 mm (51 inches) and onsite precipitation measurements for the 2 year period 1979-1981 presented by the applicant indicate annual precipitation of about 1600 mm (63 inches). These differences can be attributed to the different periods of record and primarily terrain differences between the two locations.
- Wind data taken from the 10 m level of the onsite meteorological tower for a 2 year period (October 1979 - September 1981), as summarized by the applicant, indicate prevailing winds from the southwest (20%) with a secondary peak frequency from the northeast (8.0%). The mean annual wind speed observed at the 10 m level of the onsite meteorological tower for the period 1979-1981 was about 1.6 m/sec (4 mph'), with calm conditions (defined as wind speeds less than the starting threshold of the anemometer) occurring almost 9.4% of the time.
Atmospheric stability assessments, based on vertical temperature difference measurer.ents for the 2 year period (1979-1981), have been summarized by the applicant for the 10 m (30 ft) - 60 m (197 ft) layer.
Unstable conditions (indicating rapid diffusion rates) do not occur very y---
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frequently. Neutral and stable conditions predominate and occur 99% of the time, reflecting the cloudy and rainy conditions existing in the j
region.
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As discussed above, the staff has reviewed available information relative to local meteorological conditions of importance to the safe design and siting of this plant in accordance with the criteria contained in Section 2.3.2 of the Standard Review Plan. The staff concludes that, with the exception of the design basis temperatures for HVAC systems, the applicant has identified and considered appropriate local meteorological conditions in the design and siting of this plant, and, therefore, meets the requirements of 10 CFR Part 100.10 and 10 CFR Part 50, Appendix A, General Design Criterion 2.
2.3.3 Onsite Meteorological Measurements Program The onsite pre-operational meteorological measurements program was initiated at the WNP-3 site in 1973 and ended in 1975. They re-commenced in 1979 and ended in 1981. Measurements were made on a tower extending 60 m (197 feet) above grade. The tower is located about 1207(3/4 mile) northwe'st of the plant structures. The following meteorological measurements were made on the tower: wind speed and direction at the 10 m, and 60 m levels; vertical temperature gradient between the 60 m and 10 m levels. Ambient temperature was measured at the 10 m level and dewpoint at the 60 m level.
Precipitation was measured at ground level near the tower.
A digital data acquisition system, backed up by analog strip charts, was used to record meteorological data. Daily checks and quarterly
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6 calibration were done on the equipment. The joint data recovery for l
wind speed, and wind direction at the 10 m level, and atmospheric stability (defined by the vertical temperature difference between the 60 m and 10 m levels for the 2 year period October 1979 - September 1981 presented in the FSAR was in excess of 95%.
The meteorological measurements system complies with the accuracy specifications in Regulatory Guide 1.23, "0nsite Meteorological Programs." The representativeness of the 2 year. period of onsite data to long term conditions was determined by comparisons of data from the site to measurements at Olympia and nearby locations. These comparisons indicate that reasonable estimates of atmospheric dispersion for accidental and routine releases of radioactive effluents can be made from the onsite data record.
The meteorological measurements and data collection program has been terminated after the decision to postpone or possibly cancel completion of units 3 and 5 was made by WPPSS.
If the project is resumed, the meteorological program on the 60 meter l
tower will be re-activated and will serve as the operational meteorological monitoring system as well as for emergency preparedness requirements. The meteorological measurements will be available in the control room as well as in the emergency operation facility (EOF) and r
technical support center (TSC).
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9 The meteorological program described above meets the criteria for meteorological measurements during plant operation and as part of the emergency response capability. Any meteorology measurement upgrades must be completed in accordance with the schedule of NUREG-0737, III.A.2, " Clarification of THI Action Plan Reguirements," and its supplement, and a post implementation staff review will be conducted.
The incorporation of current meteorological information into a real-time atmospheric dispersion model for dose assessments will also be considered as part of the upgraded capability.
The staff has reviewed the onsite meteorological measurements system in accordance with the criteria contained in Section 2.3.3 of the Standard Review Plan. The meteorological measurements program has provided data to represent onsite meteorological conditions as required in 10 CFR Part
'100.10.
The staff concludes that the historical site data provide a reasonable basis for making assessments of atmospheric dispersion conditions for estimating consequences of design basis accident and routine releases from the plant.
2.3.4 Short-Term (Accident) Diffusion Estimates To audit the applicant's assessments, the staff has performed an independent assessment of short-term (less than 30 days) accidental releases from buildings and vents using the direction-dependent atmospheric dispersion model described in Regulatory Guide 1.145,
" Atmospheric Dispersion Models for Potential Accident Consequence Assessments at Nuclear Power Pla'nts," with consideration of increased lateral dispersion during stable conditions accompanied by lcw wind
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10 speeds. Two years '(October 1979 - September 1981) of onsite data available to the staff on magnetic tape, which had 95% data recovery, were used for this evaluation. Wind speed and wind direction data were based on measurements at the 10 m level and atmospheric stability was defined by the vertical temperature gradient measured between the 60 m and 10 m levels. A ground-level release with a building wake factor, 2
cA, of 2133m was assumed. The relative concentration (X/Q) for the 0-2 hour time period was determined to be 4.1 x 10-4 sec/m at an exclusion 3
area boundary distance of 1311 m (.81 miles) in the south sector. The X/0 values for appropriate time periods at the outer boundary of the low population zone 4827 m (3 miles) are:
Time Period X/Q (sec/m )
0-8 hours 6.0 x 10-5 8-24 hours 4.0 x 10-5 1-4 days 1.6 x 10-5 4-30 days 4.3 x 10'0 The applicant has calculated a higher X/Q value for the 0-2 hour time period at the exclusion area and low population zone boundary than that calculated by the staff. These differences may be attributed to slightly different use of the models and the data by the staff and the applicant.
Based on the above staff and applicant evaluations performed in accordance with the criteria contained in Section 2.3.4 of the Standard Review Plan, the staff concludes that the applicant has conservatively
m jj considered atmospheric dispersion conditions at the exclusion area and low population zone boundaries for assessments of the consequences of radioactive releases for design basis accidents in accordance with the
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requirements of 10 CFR Part 100.11. The atmospheric dispersion estimates provided above which were independently calculated by the staff have been used by the staff in an independent assessment of the consequences of radioactive releases for design basis accidents.
2.3.5 Long-Term (Routine) Diffusion Estimates To audit the applicant's estimates, the staff performed an independent calculation of annual average relative concentration (X/Q) and relative deposition (D/Q) values.
Annual average relative concentration (X/Q) and relative deposition (D/Q) values at specific receptor points and in arrays to 80 Km (50 mi) for use in population dose assessment were based on the straight-line gaussian atmospheric dispersion model, described in Regulatory Guide 1.111, modified to reflect spatial and temporal variations in airflow as described in NUREG/CR 2919. Continuous and periodic releases through the plant vents were considered as ground level releases. The results of the evaluation were published in the DES.
The staff compared its long-term diffusion estimates with those provided by the applicant and determined the analyses were in general agreement.
The staff concludes that the applicant has considered representative atmospheric dispersion estimates for demonstrating compliance with the numerical guides for doses contained in 10 CFR Part 50, Appendix I.
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