ML20077M334
| ML20077M334 | |
| Person / Time | |
|---|---|
| Site: | U.S. Geological Survey |
| Issue date: | 01/07/1970 |
| From: | Terri Mclaughlin INTERIOR, DEPT. OF, GEOLOGICAL SURVEY |
| To: | Skovholt D US ATOMIC ENERGY COMMISSION (AEC) |
| Shared Package | |
| ML20077M326 | List: |
| References | |
| NUDOCS 9108130302 | |
| Download: ML20077M334 (6) | |
Text
.
m aret, senn to:
t)NITED ST AT ES DEPAR1 MENT OF THE INTERIOR
( l.Ol OGIC AL. StWVL Y rt otR AL. ct NirR. ot NVE R COLOR AoO RO2 25 January 7, 1970 Mr. Donald J. Skovholt Director of Reactor Operations Division of Reactor Licensing li.S. Atomic F,nergy Commission Wcshington, D. C.
20545
Dear 'tr. Skovholt :
Based on our analysis included below request is hereby made for your constileration of the granting of a release from Title 10 Part 20 Cole of Feleral Regulations to the (f.S. Geological Survey TRIGA Reactor Faci li t y concern i ng t he ' amount s of airborne Argon-41 released freim the reactor exhaust.
Currently we are limited to releases of Naximum Permissible Concen-trations of Argon-41 for unrestricted arcas ( 4 x 10-e pCi/cc) as measured at the reactor exhaust stack.
Assuming a duty cycle for our normal exhaust system of 350 days / year, i
we calculate the allowable annual releast as:
4 3
f (350 days /yr)(1160 f[/ min)(1.44 x 10 min / day)(2.831 x 10 cc/ft )
3 l-(4 x 10-e pCi/cc) 5
= 6.6 x 10 uCi/ year (1)
It is cur contention that the exhaust stack and the surrounding area on th( roof of the Nuclear Science Building are, in fact, restricted areas. Access to and occupancy of these areas are controlled by the reactor staff. Appropriate personnel dosimetry standards and rules for protection against radiation are applied to all personnel working in these areas.
Accordingly, we contend the nearest point to the exhaust stack which could be occupied by a member of the gencral public is 23.65 feet away from this exhnust stack.
(Note Figure #1).
This spot is 39 feet removed from the nearest sidewalk where the general public would have occasion to inhabit. The anticipated occupancy by the general public to the closest poirt, point A on the figure, is optimistically estimated to be 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> per week while loading or unload-ing shipments at the next door receiving dock.
9108130302 910807 PDR ADOCK 05000274 P
PDR l
1 2
We estimate that we could release 141 times the MPC value of 4 x 10~"
pCi/cc as measured at the exhaust stack and the permissible concentra-tions of Argon-41 wi'll not be c> ceeded for any member of the general public. We based this estimate on a minimal dilution factor, calculated below, as the exhaust air leaves the stack and mixes with the atmosphere before reaching points of unrestricted access.
These calcul.it lisim are.
Given. Average Wind Speed 9.5 miles /hr or 13.9 ft/sec (From llazards Summary Report)
Exhaust Dimensions 7.5 inches x 7.8 inches (measured)
Exhaust Velocity = 2900 ft/ min (measured) 48.3 ft/sec Shortest Distance - source to area where general public could stand (See Figure #1)
.= 23.65 ft
References:
(1)
Dif fusion of Vented G.is Around Butidings James llalite ky Journal of Air Pollution Control Volume 12 - #2, 1962 (2)
Meteorology and Atomic Energy 1968 TID-24190 - Sec tion 5.5 pp. 221-255 Exhaust Specifications:
3 f.ze A2"> f c n A5 t c -w 6.406 (c'
<;ffective Diameter =
40t> Et' i;
.~
3 Note:
In selee' ing the valuen forit, 11,.ind M, t he model t v:s ts on Clinical Center and surroundings at the National Instituten of th:alth, Bethesda, Maryland, per formed by Halit sky (op. cit. #2, Sec tion 5-5.5.3 pp. 246-252) provided values which correlated against experimental determinations give minimum dilution factors.
With test data for combinations of D ind R plotted on a graph with D it was possible to select constants a and E that as the ordinate, allowed equation #4 to be plotted as parabola bounding the data from the Although there was considerabic scatter of the data abovo below. the absence of test points below the curve implied that at a
- curve, less than those given by the given separation distance no dilutions curve had been found and, therefore, the curves could be used con-servatively for desi gn purposes.
Also from these studies the suggested values of M were 1.5 for exhaust and intake on the same roof, 2.0 for exhaust and intake on wings on roof and intake in separated by an air space and 4.0 for exhaust a cavity near ground level.
For conservatism, the additional adjustment for emission-velocity ratio is not made in this calculation. The rat to for the Survey's exhaust stack to average wind speed is 3.47 (equation #3). The ratio of 2.22 is used in die model developed by Halitsky.
Using minimum dilution factors:
a = 3,16 k
6 = 0.1 l
Then: D = M [3.16 + (0.1)(37)]"
D = 47M Table III, page 78 (op. cit. #1) where for ground conditions Note:
with values of R similar to the value determined for the GSTR facility the value for M is 3 or greater. (BA, DA, CA).
In cases where the value for R is larger (llA and JA) the value for M is < 3 but the total dilution is large because n is large. Accordingly, we believe the selection of the value of 3 for the coefficient M is conservative.
M=3 The resulting diffusion factor is:
(6)
D = (3)(47) = 141 To determine the yearly release (total) which would not expose the general public to greater than MFC values for Argon-41, we apply this allowabic annual release (1).
dilution factor (6) times our present (7)
(6.6 x 10 uCL/ year)(141) = 93 curies / year 5
JL _-
4 We are requesting the release finm itPC at this time based na our expec ted L ut ure tilill r.at lou of I he (;STil f it 11i t y.
~
This is a re-evaluation of the t otal Argoi 41 releases to be expec ted from the GSTR facility. This evaluation dif f ers f rom the llazards Sungnary Analysis because more optimistic stimates on power levels irradiation facilities and frequency of utilization for the variius have been used.
It anno contiilers the la ility will be operated 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> / day, 6 days / week.
In ev.iluating our predicted releases of Argon-41, the following assumptions ate used.
1.
Pneumatic Systems Production = 4 x 10 nCi at saturation at 1,000 KW [11511) 3 (4 x 10" nCl)(2 sys ten,s)(300 us ines/ytar /sys tem) a.
at saturation l'E.
(4 x 10" nCl),(2 systens)(5,000 usages / year / system) h.
at 107 saturation (8)
= 4 x 10 uCi/ year 4 x 10"' aci/vear (9) x o
ec L.b5 x 10'" ec/ye g =
4 x 10 uCi/ year
= 1.21 x 10~1 Wi/sn (10) 6 3.156 x 10' sec/ year Case "b" seems the more likely node of operation.
2.
1.azy Sus in Production = 8.6 x 10 Ci at saturation at 1,000 KW [IlSR) 5 (8.6 x lo' aci)(300 days / year)(17, purging / day by sample removal) r
( '.1)
= 2.6 x 10' pCL/ year
- 1.,28 x 10_., uCi/cc (12) 2.6 x 10 nC L / yea r
=
1.65 x 10'" cc/ year 2.6 x 10" uCi/vear
.823 x 10~1 (Ci/cc (13)
=
3.156 x 10 sec/ year
o 5
3.
t'ent ra l - 11iimb l e -
Production =_9 x_107 uci at saturation at 1,000134 (calculation) when operated dry, A'_ dry tube will be used ~100 times / year with 10"4 purging per utilization.
(%)
= 9 x 10' nCi/ year 4
4 x 10 oci/ year
,, g.g, g g., g, f, c 1.bS x lui ' cc/ year.
}
.5 1
/ year 4
From Reactor Water Production, assuming saturation and equilibrium with air changes.
Operations for 300 days / year.
(0.0297 x-10-7 pCi/cc [HSR])(
)
(17)
=.024 x 10-7 uCi/cc
( 1 53 )
0.0005 x 10-3 uCL/sec [lI5R]
=
(0.0005 x 10-1 uti/sec)(3.156 x 107 sec/yr) ~ 1.6 x 10" uCi/ year (19)
Totaling items - 1, 2, 3, and 4, the avera;'e release rates and concen-trations ace:
pCi/cc uCi/sec
-1.
Pneumatic Systems 2.42-x-10-7 1.27 x 10-'
2.
Lazy Susan 1.58 x 10
.83 x 10-1
-7 3.
Central Thimble
,054 ;< 10
.029 x 10~1
-7 4
Water 024 :< 10
.0005 x 10-2
~7 4.1 x 1T7 uCi/cc
~.21 uCi/sec (20)
Therefore, we assume the averat;e release for 1 year's operation will be 4.1 x 10-7 pCL/cc with a release rate of 0.21 pCi/sec as measured at the exhaust stack.
-m.
6 Converting. this est imate to a yearly release,. we h ave:
1?
(4.1 x 10~7 pCL/cc)(1.65 x 10 cc/ year) or' 6.76 curies / year (21)
Comparing this value of 6.76 curies /ycar (21) to our determination of a yearly-release value which would not expose the general public to greater than MPC values for Argon-41, namely 93 curies / year (7),
we believe that maximum utilization of the C.STR with the existing irradiation ~ facilities will not endanger 'he health and safety of the general ~public. To add an additional factor of conservatism, we request a release of only 100 times the Maximum Permissible Concen-t ratier.s for Argon-41 in unrestricted areas:
(4 x 10'" pCi/ce)(100) = 4 x 10-" poi /cc (22)
This vnlue is 2 times the Title 10 Part 29 Code of Federal Regulations value for releases to restricted areas, f2 x 10"* nCi/ce)
Converting this value to a yearly release limit we have:
13 (4 x 10~" nCi/ce)(1.65 x 10 cc/ year) l66 curies /yeari (23) n We will, of course, continue to minimize the radioactive Argon-41 concentrations -in our exhaust systems by scheduling irradiations which can produce Argan or make available for purging Argon for times when the Argon inventory in minimal, ur when the expected purging will be minimal.
Thank you for your consideration of this matter.
If we can provide any additional information, we will be happy to do so.
Sincerely, Thad G. McLaughlin Reactor Administrator t.
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