ML19220C074
| ML19220C074 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 08/12/1976 |
| From: | Hulman L Office of Nuclear Reactor Regulation |
| To: | Vassallo D Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 7904280176 | |
| Download: ML19220C074 (7) | |
Text
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AUG 121976 D. Vassallo, Chief Light "Jater Raactors Branch f 4 HIVISED SAPETT EVALUATION REPOEr INPUT - FEIT.OROLOGY PLANT NAME: Bree-Mile Island Nuclaar Station - Unit 2 LICENSING STAGE: CL DOCKET NUMBER: C56320)
MILESTONE NO.: 1632 RESPONSIBLE BRJNCH: LWR-4 REQUESTED COMPLETION DATE: July 22, 1976 APPLICANTS RESPONSE DATE NECESSARY M R NEIT ACTION PLMCTED ON PROJECT: N/A DESCRIPTION OF HESPONSE: None REVIEW STATUS: Meteorology Section (EMB) - Completa Ecclosed is reviaed Safety Evaluation Esport input to Sections 2.3.3 through 2.3.6.
Please insert these sections in place of the infor-nation sabmitted with our September 5,1975 ne:norandu:n and delete the reference to Regulatory Guide 1.42, "Interia Licensing Policy On As Low As Practicable for Gaseous Radinicdine Ralaanes from Light Watar-Cooled Reactors - Revision 1."
This revision is the result of a r==n=1 sis of the data to include an additional full year period 7
of onsita mateorological data and also to include meander considerations.
Data recovery was less than 80% during each of the thraa years provided.
To accon=odate resulting uncertainties, a 20% uncertainty factor, based in part on a senef atical analysis by Woodard (Nnr. Tame Technology, April 1975), was incorporated in the staff's atmospheric disperaion astisates. The applican-has stated that recently improved instrumentation and naintenance capability will provide reasonable assurance that the data recovery from the coneinning onsits metsowingical program vill be at least 90%. Any additional onsite notec.rological data meeting the re - e einns and intent of degulatory Culla 1.23, "Onsite Meteorological Prograus," provided by tht applicant vill be evaluated by the staff to verify and to provide a basis for reconsideration of the encartainty factor.
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AUG 121976 D. Vassallo, Chief Light Water Reactors Bran 74 REVISED SAFETY EVALUATION T INPUT - YS"iOROLOGY PLANT NAME: Three-Mile Island Nu ear Station - Unit 2 LICZNSING STAGE: OL DOCKET NUMBER: 50-320 MILESTONE No.: 24-32 RESPONSI3LE BRANCH: LWR-4 REQUESTED COMPLETION DATE: July 22, 1976 APPLICANTS RESPONSE DATE NECESSARY FOR NEXT ACTION PLANNED ON PROJECT: N/A DESCRIPTION OF RESPONSE: None REVIEW STATUS: Meteorology Section (HMB) - Complet Enclosed is Revised safety Evaluation Report input to S tion 2.3.3 through 2.3.6.
Please insert enese sections in place of e infor-nation submitted with our September 5,1975 memorandum and elete the reference to Regulatory Guide 1.42, "Interin Licensing P icy On As Low As Practicable for Gaseous Radioiodine Releases from 'ight-Water-Cooled Reactors - Revision 1,"
This revision is the res of a reanalysis of the data to include an additional full year pe od of onsite meteorological data and also to include meander considera ons.
Data recovery sr.s less than 80% during each of the three years provic d.
To accos:modate resulting uncertainties, a 20% uncertainty factor, basec.
in part on a statistical analysis by Woodard (Nuclear Technology, April 1975), was incorporated in the staff's atrnspheric dispersion estiaates. The applienr:t :us indicated that good data recovery (at least 90%) is expected in the near future when a nav meteorological tower bcco:nes operational. Any additional onsite t:eteorological data meeting the recoumendstions and intent of Regulatory Guide 1.23, "Onsite Meteorological Programs," provided by the applicant vill be evaluated by the staff to verify and to provide a basis for reconsideration of the uncertainty factor.
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- a. vasaano AUG 121975 This input was prepared by L. Andrews, J. Fairobent, and E. H. Markee, Jr.,
Hydrology-Meteorology Branch, DSE.
Original Signed by L. G. Hulman Levis G. Ftuimrt, Chief Hyc'rology-Meteorology Branch Division of Site Safety and Environ:nental Analysis
Enclosure:
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O METROPOLITAN EDISON COMPA'iY THREE-MILE ISIxtD NUCLEAR STATION - UNIT 2 DOCKET NL"d3ER 50-320 REVISED SAFETY EVALUATION REPORT INPL7 2.3.3 casite Meteorological Measurements, Program The onsite meteorological measurements program has been cc= pared with the reco==endations and intent of Regulatory Guide 1.23.
We concluded that the metecrological =easurements program has produced data which, in turn, have been sarized to provide an adequate meteorological description of the site and its vicinity for the purpose of =aking atmospheric diffusion esti=ates for accidental and routine airborne releases of radioactive effluents from the proposed nuclear plant.
Meteorological data collection began onsite in May 1967 with the inscallation of a 100-ft high, instrumented mase about 1500-ft south of the Unit 2 contaic=ent structure. Wind speed and direction were measured at the 100-f t level on this mast.
In October 1970, this mast was relocated to a position approxi::ately 1750-ft southeast of the Unit 2 containment. Wind speed and direction continued to be measured at the 100-f t level on this =ast until it was deactivated in June,1972.
At the same time that the 100-ft =ast was moved from its original position in October 1970, another 150-f t high meteorological tower, erected on the northern end of Three-Mile Island, became operational.
Located 2200-f t north of the Unit 2 containment building, this tower is currently in operation at the site. Wind speed and direction are
=easured at the 100- and 150-f t levels, ambient air temperature at the 25-f t level, relative hu=1dity at the 150-f t level, and vertical te=per-ature difference between the 25-and 150-f t levels and between the 50- and 150-ft levels on this tower. In addition, horizontal and vertical wind fluctuations are measured at the 100-ft level.
In October 1971, the vertical te=perature gradient measuring system was replaced and upgraded.
The present wind speed and direction measuring instru=ent installed at the 150-f t level does not meet the instrument specifications reco= mended in Regulatory Guide 1.23.
Because of the limited space available on the island and the numerous structures associated with plant facilities, the location of the lowest wind sensors are not at the 10 meter above ground level as recocnended in Regulatory Guide 1.23.
Instead, the 100-f t level of these sensors places them at a height 10 metern (33-ft) above nearby trees which reach heights of about 70-ft.
This placement does meet the intent of Regulatory Guide 1.23.
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86 260 The applicant has provided joint frequency distributions of wind speed and direction by at=ospheric stability (defined by vertical te=perature gradient) for three one-year periods:
1.
April 1, 1971 through March 31, 1972 2.
October 7, 1972 through October 6, 1973 3.
November 8, 1974 through November 7, 1975 Wind speed and direction were measured at the 100-foot level and the wind speeds were reduced to represent conditions at the 33-foot level by use of a power law for wind profiles. At=ospheric stability was defined by the vertical te=perature gradient between the 50-foot and 100-foot levels. Data recovery for the period April 1, 1971 through March 31,1972 was 79%, with most of the missing data frem the month of April; data recovery for the period October 7,1972 through October 6,1973 was 79%, with most of the missing record from the month of September 1973; and data recovery for the period November 8, 1974 through November 7,1975 was 78%, with numerous 7-day outages throughout the year.
We have also formed a composite joint frequency distribution by com-bining the October 7,1972 through October 6,1973 data with the November 8, 1974 through November 7,1975 data. The April 1,1971 through March 31, 1972 data were excluded because the vertical temperature gradient measuring system was replaced and upgraded midway through the data collection period (October 1971).
Me have calculated relative concentration values using each set of data.
We consider the ce=posite joint frequency distribution ecmbining the October 7,1972 through October 6,1973 data with the November 8,1974 through November 7,1975 to be the best data available at this time; therefore, we have used these data as bases for the calculations of the relative concentration values presented in Section 2.3.4.
2.3.4 Short-Ters (Accident) Diffusion Estimates In the evaluation of short-term (0-2 hours at the exclusion distance and 0-8 hours at the LPZ distance) accidental releases from buildings and vents, a ground level release with a building wake factor, cA, of 100022 was assumed for all winds greater than 2.5 miles per hour and winds less than 2.5 miles per hour when the atsosphere was unstable or neutral (Paaquill A, B, C, and D). The applicant previously conducted a limited series of atmospheric tracer tests at distances about 100 meters from the source during stable atmospheric conditions acccmpanied by light wind speeds. The results of these tests have since been corroborated by similar tests conducted in Idaho, Louisinna, and Tennessee at distances at or beyond the TMI exclusion distance.
Therefore, we have modified the dispersion =odel described in Regulatory
.m Guide 1.4 to include credit for lateral pluse =eander during stable 86 261
O at=ospheric conditions (Pasquill types E, F and G) acce=panied by light wind speeds (i.e. less than 2.5 =ph) with no building wake mixing under these light wind, stable atmospheric conditions. The dispersion model also considered the 2xclusion distance as a function of direction from the plant, the atmospheric diffusion conditions when the wind fa blowing in a specific direction, and the fraction of ti=e the wind can be expected to blow in any direction. This model is a deviation from our usual standard review plan analysis (Section 2.3.4 ),
but is considered to incorporate a = ore realiscic assessment of close-in diffusion conditions as reflected in tests at this site and others.
To acce=modate uncertainties resulting fres less than 80% data recovery, a 20% uncertainty factor, based in part on a statistical analysis by Woodard, was incorporated in the staff's dispersion estimates.
Our review of other sites indicates the uncertainty factor is substantially greater than changes in typical diffusion conditions that might be suspected fres year to year variations. The liniting relative concentration (X/Q) for the 0-2 hour ti=e period follcwing an accidental release, equivalent to that expected to be exceeded no more than 5% of the time at the exclusion distance, was calculated to be 1.1 x 10-3 sec/m3, including the 20* uncertainty factor. This value occurred in both the northeast and east-northeast directions frc= the plant at site boundary distances of 630 and 610 meters, respectively.
The relative concentrations, including the uncertainty factor, at the outer boundary of the icw population =ene distance (3218 meters) for the various ti=e periods following an accidental release to the acnosphere are:
Time Period X/0 sec/m3 0-8 hours 1.1 x 10-4 8-24 hours 6.7 x 10-5 1-4 days 2.5 x 10-5 4-30 days 6.0 x 10-6 2.3.5 Long-Ters (Routine) Diffusion Estimates Reasonable estimates of average at=ospheric diffusion condit+ns have been made by us from the applicant's =eteorological data and appropriate diffusion models as described in NOAA Technical Memorandum ERL ARL-42.
Including the uncertainty factor, the highest offsite annual average relative concentration of 1.2 x 10-5 sec/m3 for vent releases occurs at the site boundary east of the proposed reactor cc= plex.
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-4 2.3.6 Conclusions The ensite meteorological measurenents program will continue in operation during the lifeti=e of the plant to provide sufficient =eteorological data for esti=ating radiation doses to the public as a result of routine or accidental releases of radioactivity to the atnesphere, and for initiating protective =easures to protect the health and safety of dhe public. The applicant has stated that recently i= proved instru-
=entation and maintenance capability will provide reasonable assurance that the data recovery from the continuing onsite meteorological program will be at least 90%. We will review these proposals and report our conclusions in a supplenent to this report.
The limiting relative concentration values calculated at the exclusion distances using each set of data (excluding the April 1,1971 through March 1972 period) vary by only about 10%. Because of the persistent poor data recovery (80%) and extended periods of missing data, we require the applicant to submit a year of onsite meteorological data, with data recovery of at least 90%, as soon as such data are available. We vill use these data to confirm that the relative concen-tration values presented herein are reasonably conservative.
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ADDITIONAL BIBLICCRAPHY - SECTICN 2.3.4 Sagendorf, J.
F.,
1974: A Program for Evaluating Atnospheric Dis-persion from a Nuclear Pcver Station. NOAA Technical Mc=orandum ERL ARL-42.
Air Resources Laboratory, NOAA, Idaho Falls, Idaho.
Van der Hoven, I.,
1976: A Survey of Field Measure =ents of Acnos-pheric Dif fusion Under Lcw-Wind-Speed Inversion Conditions. Nuclear Safety, 2(17) :
223-230 (March-April 1976).
Woodard, K.,1974: Sensitivity of Atnosphetic Diffusion Estimates to Meteorological Data Recovery and Accuracy. Nuclear Technology, (25):
635-639 (April 1975).
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