ML19199A558
| ML19199A558 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 08/13/1976 |
| From: | Markee E Office of Nuclear Reactor Regulation |
| To: | Farrell C Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 7905040097 | |
| Download: ML19199A558 (1) | |
Text
h DISTRI3UTION:
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_fv a w C. Ferrell, Accident Analysis Branch, DSE
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METEOROLOGICAL DATA Below are the relative concentrations (I/Q) for various time periods for use in your evaluation of short-tem accidental releases from Three Mile Island - Unit 2.
Data inputted into these dispersion estinates were collected onsite from October 7, 1972 through October 6, 1973 and November 8, 1974 through Nove=ber77, 1975. A ground level release with a building vake factor, cA, of 1000m2 was assu=ed.
We have modified the dispersion model leseribed in Regulatory Guide 1.4 to include credit for lateral plume meander during stable at=os-pheric conditions (Pasquill types E, F, and G) accompanied by light
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vind speeds (i.e. less than 2.5 nph) with no building vAhe miring under these light vind, stable atmospheric conditions. The dispersion model also considered the exclusion distance as a function of direction from the plant, the at=ospheric diffusion conditions when the vind is blowing in a specific direction, at.d the fraction of time tne vind can be expected to blow in any direction.
To acco.odate uncertaintics resulting from less than 80% data recovery, a 20% uncertainty factor was incorporated in the staff's dispersion es timates. The 1M eing relative concentration (I/Q) for the 0-2 hour ti=e period collowing an accidental release, equivalent to that expected to be exceeded no more than 5% of the H = at the exclusion distance, was calculated to be 1.1 x 10-3 sec/=3, including the 20% uncertainty factor. This value occurred in both the northeast and east-northeast cirections from the plant at site boundary distances of i30 and 610
- neters, respectively. The relative concentrations, including the uncertainty factor, at the outer boundary of the icv population zonde distance (3213 =eters) for the various time periods folleving an accident 11 release to the at=osphere are:
Time Period I/O sec/=3 0-8 hours 1.1 x 10-4 8-24 hours 6.7 x 10-5 1-4 djrys 2.5 x 10-5 4-30 days 6.0 x 1g-6 E$rlE.Markee,Jr., Leader ly'-r L
_j Hydrology-Peteorology Branch g
L Division of Site Safeyy and e g - e.,, i.
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DISTRIBUTION:
CENTRAL FILES
- R RDG AUG 13 G76 DS RDG DG RDG C. Fe all, Accident Analysis Branch, DSE METEORfF ~ICAL DAIA Selow are t e relative concentration (I/Q) for various tine periods for use in y ur evaluation of shart-tern accidental releases from Three Mile Is nd - Cuit 2.
Data inputted into these dispersion estimates were ollected onsite from October 7, 1972 througn October 6, 1973 and Nove:nbe 8, 1974 through Nove=ber 7, 1975. A ground level release with a but ing vake factor, cA, of 1000n' vas assuced.
We have ::radified th dispersion model described in Regulatory Guide 1.4 to include credit 'or lateral plume scander during stable at=os-pheric conditions (Pasq types E, P, and G) acco=panied by light vind speeds (i.e. less tr n 2.5 moh) with no building wake mixin; under 'd:ese light vind, st. le atmospheric conditiona. The discersion model also considered the ex usion distz.nce as a function of direction from the plant, the at:nospher.
diffusion conditions when the wind la blowing in a specific direct n, and the fraction of time the vind can be expected to blev in a.
direction.
from less than 80% data recovery To accommodate uncertainties result a
a 20: uncertainty factor was incorpor ed in the staff's dispersion estimates. The li=if ting relative conc ration (X/Q) for the 0-2 hour time period exceeded no more than 5% of t e cine at the exclusion distance, was calculated to be 1.1 x 10-3
.cfn3, including the 20%
'mcertainty factor. This value occurred in th the northeast and east-northeast directions frue, the plant at si e boundary distances of 630 and 610 noters, respectively. The relative oncentrations, including the uncertainty factor, at the outea bo 7dary of the low population zone distance (3218 meters) for the var us ti.:e periods an accidental release to the atmosphere are:
Time Period I/Q sec/m3 0-8 hours 1.1 x 104 B-24 hours 6.7 x 10-5 1-4 days 2.5 x 10-5 days 6.0 x 10-*
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. Earl H. !!arkee, Jr., Leader Hydrology-Meteorology Branch Division of Site Safety and Environmental Analysis DSE:HMS DSE:HMB o -,ci.g:
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