ML20245B831
| ML20245B831 | |
| Person / Time | |
|---|---|
| Site: | Idaho State University |
| Issue date: | 04/14/1989 |
| From: | Adam Wilson IDAHO STATE UNIV., POCATELLO, ID |
| To: | Michaels T Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8904260304 | |
| Download: ML20245B831 (4) | |
Text
{{#Wiki_filter:e f> T# h I I r,; l ' idaho State University + Pocatello, ideho KQMCMG I College of Engineering . Box 8060 - April 14, 989 1
- G08) 236-2902 4
Mr. Theodore Michaels Standardization and:Special F Projects' Branch. ~ Division' of. Licensing U.S.-Nuclear Regulatory Commission Washington,.D.C..20555 REF: Docket No. 50-284
Dear Mr.' Michaels:
I.am supplying.the clarification needed for my previous letter of February..15,.1989. The~ data for the radiation levels provided.as an enclosure with theLFebruary 15 letter were all taken with the' reactor operating at-a power ~ level of'five (5) watts and with the shield doors on Ltop.of.the reactor closed. The graphite thermal column was in . place during the measurements since that is the column which is used with the1 neutron radiography experiment. I have provided a revised copy of the enclosure.with the power. level indicated 'above the; table of dose rates. I would appreciate it if you would substitute this diagram and table for the one sent on February 15. In order to predict what the dose rates would be in the various
- 1ocations at ten (10) watts, the values in the table were simply
' doubled. It is apparent that the dose rate would exceed 100 mrem /hr only in those areas already designated as high radiation areas. Therefore, the remaining areas need only be designated as radiation areas which is consistent with our present practice. We.have subsequently made measurements in the high radiation area on top of the reactor to evaluate the effect of the movable ' shield doors'over the thermal column area. These readings were taken when the reactor was at a power level of five tenths (0.5) watts with'the graphite thermal column in place. Readings were 'taken with the shield doors open and with them closed to assess the value of the doors. Readings are shown on the second enclo-sure sheet entitled " Shield Door Evaluation." 1 8904260304 890414 IC PDR ADOCK 050002840 P-PNU )h.g g g O ISU is An Equal Opportunity Employer
7-- Mr. Theodore Michaels April 14, 1989 Page 2 It is apparent that closing the shield doors reduces the radia- ' tion levels in the high radiation area on top of the reactor sig-nificantly. Even more important, however, is the reduction in dose rate within the rest of the laboratory. Since the dose rates in these areas are quite low when the reactor is operating at 0.5 watts, it is difficult to get accurate data for the actual reductions. The bottom line on the Shield Door Evaluation table shows values at the console and should be typical of the rest of the lab. The shield doors reduce the radiation level by approxi-mately a factor of two. This reduction is felt to be signifi-cant at a power level of 5.0 watts and is part of our ALARA pro-gram to reduce exposure. If you have further questions regarding our request for changes in the Technical Specifications, please let me know. Sincerely, Albert E. Wilson Reacto.' Administrator AEW:lk encls
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,+ b SHIELD DOOR EVALUATION J NOTE: The following radings were taken with the reactor.at a power level of 0.5 watts and with the graphite thermal column in place. Whole body, (WB), readings were taken one meter above the surface indicated. Contact, (C), readings were taken with meter placed on surface indicated. All readings are in mrem /hr. e Doors Open Doors Closed Location of Reading Gamma Neutron Gamma -Neutron Top. of Stairs (WB) 2.5 1.0 0.7 0.3 Walkway So. of Doors (WB) 10.0 5.0 1.8 1.0 Above Thermal Column (WB) 22.0 16.0 2.0 1.0 Top of Thermal Col. (C) 85.0 140.0 14.0 7.0 On shield doors (C) Operator Position * (WB) 0.3-0.2 0.1 0.1
- All readings except operator position are in the designated high radiation area.
Operator position is the normal operator loca-tion at the operating console. = - - - _ -}}