ML19339A266
| ML19339A266 | |
| Person / Time | |
|---|---|
| Site: | Pennsylvania State University |
| Issue date: | 10/14/1980 |
| From: | Cunningham R PENNSYLVANIA STATE UNIV., UNIVERSITY PARK, PA |
| To: | John Miller Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8011030478 | |
| Download: ML19339A266 (3) | |
Text
THE PENNSYLVANIA STATE UNIVERSITY 207 OLD MAIN DUILDING UNIVER$!TY PARK. PENNSYLVANIA 16802 Vk P=idesc lor Area Cde 814 R...usk .ed Gr.duw St.Ji.. 865 4332 14 October 1980 Mr. James R. Miller Standardization and Special Projects Branch Division of Licensing Nuclear Regulatory Commission Washington, D.C. 20555
Subject:
Request for Exemption of a Criticality Monitoring System Docket No.: 50-5 NRC License: R-2
Dear Mr. Miller:
Section 70.24, " Criticality Accident Requirements," of 10 CFR, Part 70, " Domestic Licensing of Special Nuclear Material" requires that licensees who possess special nuclear materials (SNM) in a quantity exceeding 700 gs of contained uranium-235, shall maintain- in each area in which such licensed SNM is stored a monitoring systen meeting specified requirements. Penn State has 802 gs of U-235 in eight (8) partial MIR-type highly enriched fuel elements stored in a special pit of the Breazeale Nuclear Reactor facility. No other SNM is stored in this area.
The purpose of this letter is to request exemption from the requirements of the monitoring system because even the remote possibility of flooding of these fuel elements with water in any configuration will not permit attaining criticality.
The MTR fuel elements are stored in the fuel storage pit located in the northeast corner of the reactor bay area under the floor. The pit is 10' deep, 6' wide and 10' long. The floor and the four (4) walls are constructed of concrete with three (3) of the walls being earth backed.
The fourth wall is backed up to Room #14 within the reactor facility. Two separate racks constructed of plywood are used for storing the MTR fuel elements in the pit. The two racks are held apart by 2" x 4" wood planks aligned along the two walls. Each fuel rack has fourteen (14) 6" x Sh" openings 32" high. Only one rack is partially filled with the eight (8)
MTR fuel elements. The entrance to this pit is through the reactor bay floor. A false plywood floor covers a reinforced steel plate trap door 3' x 9' hinged on one side with a chain and lock securing the other side of the trap door.
OM s
I' 0 8H 0304/73
Mr. James R. Miller Standardization and Special Projects Branch Division of Licensing page 2 Considerable experimental and calculated evidence exists on the criticality requireme ts of MTR-type fuel. In general, measurements byBreazeale,etal.(p}haveshownthatalight-watermoderatedand reflected close packed critical array of Penn State MTR fuel elements requires in excess of 2.5 kg U-235 to attain criticality. This is consistent with the Weinberg, et al.(2) calculations and measurements.
< Studies show( that it is impossible to attain criticality with U-235 in water moderated-reflected spherical assemblies with less than approxi-mately 850 gs U-235 assuming no structural materials in the core. Hence,
- even under assumed worst accident conditions, these fuel elements cannot go critical.
i j For these reasons, we respectfully request exemption from the requirements of the monitoring system as specified in 70.24 of 10 CFR Part 70.
Sincepely yours,
/
, u R. Cunningham i
Vice President for Research and Graduate Studies I
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.i REFERENCES
- 1. Breazeale, W. M., Cochran, R. G., Misenta, R., Geisler, , and Sjoborg, W. , " Low Power Experi:nents with The Pennsylvania State University Reactor," UYO-7895 Contract No. AT-(40-1)-2009 USAEC, '
Septe:nber 1956.
- 2. Weinberg, A. M., Cole, T. E., and Mann, M. M., "The Materials Testing Reactor and Rclated Research Reactors," Proceedings of the International Conference on the Peaceful Uses of Atomic Energy, Vol. 2, p. 402, August 1956.
- 3. Braser, R. I.', King, L. D. P., and Mills, C. 3., " Application of Low Critical Mass Studies to Reactor Design," Nuclear Applications, Vol. 6, p. 266, April 1969.
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