ML20202G697
| ML20202G697 | |
| Person / Time | |
|---|---|
| Site: | 05000128 |
| Issue date: | 07/11/1986 |
| From: | Feltz D, Richardson H TEXAS A&M UNIV., COLLEGE STATION, TX |
| To: | Harold Denton Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML20202G702 | List: |
| References | |
| NUDOCS 8607160067 | |
| Download: ML20202G697 (3) | |
Text
TEXAS ENGINEERING EXPERIM ENT STATION THE TEXAS A&M UNIVERSITY SYSTEM
[
COLLEGE STATION, TEXAS 77843-3575 11 July 1986 M
J NUaEA E"
Mr. Harold Denton, Director 5751 Nuclear Reactor Regulation
% PWR-B/SSPD U.S. Nuclear Regulatory Commission Washington, D.C.
20555
Reference:
License R-83, Docket No. 50-128
Dear Mr. Denton:
Submitted herewith is a request for a license amendment for the Texas A&M University Nuclear Science Center Reactor (NSCR), License R-83 to increase the total controlled inventory of iodine isotopes 131 through 135 in a fueled experi-ment from 1.5 curies to 10 curies.
In support of this request, the following infonnation and evaluations are submitted for review:
1.
A draft of proposed wording change of Technical Specification 3.6.2(b).
2.
Results of calculation of inventories of the isotopes I-131 through I-135 utilizing the ORIGEN code based on irradiation of one gram of U-235 at a flux of 1 x 10 'h/cm /sec for a period of 40 hours4.62963e-4 days <br />0.0111 hours <br />6.613757e-5 weeks <br />1.522e-5 months <br />.
This data establishes 2
the fractional content of each of the iodine isotopes.
3.
Results of a calculation of doses to the thyroid of a person at the site boundary for a period of 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> as calculated using the techniques specified in ICRP2 (existing 10CFR20) and in ICRP26 and 30 (proposed 10CFR20) and by the MIRD Committee of the Society of Nuclear Medicine. A release of a total of 1 curie of the isotopes I-131 through I-135 is assumed.
4.
Results of a calculation of the maximum iodine release to the building that would result in an exposure of 0.5 rem to a person who stays on the boundary for 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br />.
5.
Results of a calculation of the stack concentrations present and a com-parison to the yearly averaged limits on stack releases to insure that the yearly averaged boundary concentrations do not exceed ti.ose limits allowed by 10CFR20 (both existing and proposed limits are analyzed). Again a re-lease to the building of I curie is assumed.
6.
Copy of present Technical Specification 3.6.2 and 3.6.3 which pertain to the control of fueled experiments in the NSCR.
The assumptions employed in the above evaluations are as follows:
. Total inventory of isotopes I-131 througn I-135 in a fueled experiment is 10 curies.
8607160067 860711 PDR ADOCK 05000128 P
PDR pkO REStAHGH AND DEVELOPMENT FOR MANKIND
'I
4 Fueled experiments are assumed to be encapsulated or to be filtered to control.
fission product effluents.
1 Worse cases where effluents are released to the reactor building rather than released to the reactor pool water are evaluated.
l Filtering of the' experiment is 90% efficient with only 10% release to the building in case-of failure to control the experiment. This would result in 1
a 1 curie release to the building. This is based on the allowed assumptions for failure of such experiments as stated in Technical Specification 3.6.3 (see attachment).
Person remains at site boundary for 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br />.
i Thyroid mass = 20 grams (Reference Man).
3 Breathing rate = 1.25 m /hr.
The free volume of the NSC confinement building is 180,000 ft' (5.097 x 10' liters).
Dispersion factor from stack to boundary is set at 200 (as opposed to best value of 1000).
No decay of isotopes is assumed during periods of release.
Calculations of dose utilizing ICRP30 do not include the contribution for I-132m.
Iodine in the tnyroid is assumed to be retained in the thyroid with a biological half-life of 80 days (ICRP30, Part 3d). Radiological half-lives are obtained from accepted reference tables.
Biological data is obtained from ICRP2, ICRP26/30, MIRD as applicable.
i Equations used for dose estimation are those cited in the above documents.
When comparisons are made, the values quoted are for the most limiting isotopic form.
Data is presented for both existing and proposed 10CFR20 limits.
The exhaust system of the confinement building is assumed to remain in operation with no additional filtering of the building exhaust air.
An accepted 50% " plate out" within the reactor building is not applied, thus, the results are conservative.
1 1
4
Evaluations performed indicate that in the event of failure of a fueled experiment having a total inventory of 10 curies of activity for the iodine isotopes 131 through 135 in which the effluent fission products are controlled by encapsulation or filtering, the exposure dose at the exclusion area boundary will be less than the allowed limits of the present and proposed changes to 10CFR20.
-It should be noted that these evaluations are very conservative as indicated by the listed assumptions.
If additional information is needed or if additional evaluations are required please contact Donald E. Feltz, Director of the Nuclear Science Center at (409) 845-7551.
Your attention to this request will be greatly appreciated and we are appre-hensive that an approval can be obtained by the end of August 1986 or very soon thereafter.
Respectfully Submitted,
[
k k.$'O "+b n } Q, Donald E. Feltz, Director H. H. Richardson, Vice/Cha5cellor, Nuclear Science Center Dean of Engineering and Director, Texas Engineering Experiment Station cc: Hal Bernard, USNRC, Washington Darwin Hunter, USNRC, Region IV Feenan Jennings, Reactor Safety Board, TAMU Lee Peddicord, Nuclear Engineering Dept, TAMU Enclosures I
1 l
1 s
i i
i
)
Proposed License Amendment Nuclear Science Center Reactor Proposed Change to Technical Specifications for License R-83 Technical Specification 3.6.2 - Material Specifications As Reads 3.6.2(b)
Each fueled experiment shall be controlled such that the total inventory of iodine isotopes 131 through 135 in the experiment is no greater than 1.5 curies.
Revised to Read 3.6.2(b) i Each fueled experiment shall be controlled such that the total inventory of i
iodine isotopes 131 through 135 in the experiment is no greater than 10 curies.
As Reads: Bases for 3.6.2(b)
The 1.5 curie limitation on iodine 131 through 135 assures that in the event of j
f ailure of a fueled experiment leading to a-total release of the iodine, the exposure dose at the exclusion area boundary.will be less than that allowed by j
10CFR20 for an unrestricted area.
l Revised to Read:
Bases for 3.6.2(b)
The 10 curie limitation on iodine 131 through 135 assures that in the event of t
f ailure of. a fueled experiment, leading to a total release of the iodine, the J
exposure dose at the exclusion area boundary will be-less than that allowed by 10CFR20 for an unrestricted area.
h E.
8
Iodine Production From Irradiation of One Gram of U-235 in a Flux of 1011 2
n/cm /sec In order to evaluate iodine inventories of fueled experiments, calculations were performed using ORIGEN which is recognized by the U.S.N.R.C. for isotopic inventory calculations. For conservatism it was assumed that the one gram of U-235 was irradiated continuously at a flux of 1011/cm -sec for a period of up 2
n to 40 hours4.62963e-4 days <br />0.0111 hours <br />6.613757e-5 weeks <br />1.522e-5 months <br />. Supplementary results are provided for times of 4, 8, 12, 16, 20, 24, 28, 32, and 36 hour4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> irradiations.
The ORIGEN output indicates for the isotopes I-131 through I-135 that an inventory of 0.2999 Ci/gm U-235 would exist af ter 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />, rising to a level of 0.588 Ci/gm U-235 after 40 hours4.62963e-4 days <br />0.0111 hours <br />6.613757e-5 weeks <br />1.522e-5 months <br /> continuous exposure.
Iodine Activity Levels Nuclide 4 hr. (Ci/gm) 40 hr. (Ci/qm)
I-131 8.5 x 10 "
0.0159 I-132 2.11 x 10-8 0.0342 I-133 0.020 0.1453 I-134 0.215 0.216 I-135 0.062 0.177 Sum 0.299 0.5884 These results are used to establish the relative amounts of each isotope for a specified inventory amount.
q Calculation of Dose at Site Boundary Upon Failure of a Fueled Experiment Resulting in a 10% Release to the Reactor Building From a Total Iodine Inventory of 10 Curies From ORIGEN calculations for a 1 curie release the following relative amounts of each isotope would be released to the reactor building.
Isotope Amount ( Ci)
I-131 0.0265 I-132 0.067 I-133 0.2517 I-134 0.36 I-135 0.295 1.0002 Following dispersement in the building the following concentrations would be released from the stack.
Isotope Stack Concentration (uCi/1) 1-131 5.20 x 10-8 I-132 1.31 x 10-2 I-133 4.94 x 10-2 I-134 7.63 x 10 2 I-135 5.79 x 10 2 I
1 Hour Dose (rads) at Boundary Isotope ICRP2 ICRP26/30 MIRD I-131 5 x 10
5.67 x 10
5.67 x 10
I-132 4.75 x 10
8.0 x 10 5.15 x 10~"
-5
-2
-8
-2 I-133 1.3 x 10 9.08 x 10 1.3 x 10 I-134 1.25 x 10 '
7.0 x 10
~
~5 I-135 4.83 x 10
1.83 x 10
O.025 0.017 0.019
==
Conclusion:==
The most conservative dose is much less than the annual accepted l
public exposure of 0.5 rem.
j l
Calculation of Maximum Iodine Release to the Building Resulting in 0.5 Rem to a Person At the Site Boundary for 1 Hour From the previous evaluation for the " worse case" ICRP2 the following stack concentrations could be released for 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br />.
Isotope Hourly Avg. Stack Concentration (uCi/1)
I-131 0.104 I-132 0.263 I-133 0.988 I-134 1.413 I-135 1.158 For a stack flow rate of 5,000 cfm (8.5 x 10 1/hr) the release for 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> becomes:
Isotope Total 1 Hour Release (Ci) 1-131 0.824 I-132 2.235 I-133 8.389 I-134 12.007 I-135 9.840 33.355 Ci Maximum Release to the Building l
i
r Comparison of Stack Concentration for 1 Curie Release to Yearly Averaged Limits Existing 10CFR20 Limits Yearly Average Calculated Isotope Boundary Limit Stack Limit Stack Concentration (p Ci/ml)
(p Ci/ml)
(uCi/ml)
I-131 1x10Ilo 2 x 10-8 5.9 x 10-8 I-132 3 x 10 8 6 x 10-7 1.5 x 10-8
>I-133 4 x 10 10 8 x 10-8 5.7 x 10-e I-134 6 x 10 '
12 x 10-7 7.98 x 10-e I-135 1 x 10 '
2 x 10-7 6.6 x 10 8 Proposed 10CFR20 Limits Yearly Average Calculated Isotope Boundary Limit Stack Limit Stack Concentration
( pCi/ml)
(Ci/ml)
(pCi/ml)
I-131 2 x 10-18 4 x 10-8 5.9 x 10-8 I-132 2 x 10 8 4 x 10-8 1.5 x 10 8 I-133 1 x 10 '
2 x 10 7
- 5. 7 x 10 - 8 I-134 6 x 10 8 12 x 10-8 7.98 x 10-8 I-135 7 x 10-7 14 x 10-5 6.6 x 10 e
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