ML19310A351
| ML19310A351 | |
| Person / Time | |
|---|---|
| Site: | 05000141 |
| Issue date: | 06/03/1980 |
| From: | Finston R, Holmes J STANFORD UNIV., STANFORD, CA |
| To: | Erickson P Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8006110122 | |
| Download: ML19310A351 (4) | |
Text
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67 Encina $lall Stanford, Calif.94305 STANFORD l {
UNIVERSITY
^ "* "'3H"2 '
HEALTH PHYSICJ RoLAND A. FINSToN, Ph.D.
Director (497-4767) 3 June 1980 DIRECTOR OF NUCLEAR REACTOR REGULATION UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D. C.
20555 ATTN:P. ERICKSON REF: DOCKET #50-141 DEAR MR. Erickson:
This letter is written in response to telephone discussions be-tween you and Dr. Roland Finston of Starford on October 5,1978, Mr.
Cy. Block, you and myself on November 26, 1978, and a site visit by Mr. J. Richard Curtis of the Region V Office on January 31, 1979 The information is submitted in support of the University's application to terminate its Reactor Facility License No. R-60 and for release of the site for unrestricted use.
One of the questions which arose during your discussions with Dr. Finston was whether the " contamination" was surface or activation in the bui1 ding materials.
If the latter were the case the limits for contamination cited in the Regulatory Guide # 1.86 would not apply.
To resolve the problem the University arranged to have cores drilled in the floor of the reactor tank structure.
The cores were taken on January 31, 1979 with Mr. Curtis present.
Three 2 inch diameter cores were removed frem locations where the previous drillings were done.
Those earlier drillings provided data for our previous application.
The sites which were selected had given the highest and lowest activity measurements.
The lengths and weights of the cores drilled were as follows:
Core #6 = 12 inches, 1057 grams Core #4 = 12 inches, 1059 grams Core #3 = 24 inches, 1991 grams i
The cores were broken into sections using a hammer and chisel.
The samples were then placed into suitably labeled plastic containers. These
-800ex xo tgjL J
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page 2 were taken to a concrete testing laboratory where they were ground to a coarse mesh.
( A health physicist was present during the grinding op-eration to ensure that the samples were not mixed. )
The samples were then veighed.
By removing portions from the samples all weights were ad-justed to equal the weight of the minimum sample, i.e., 90 grams.
The samples were ana]yzed on a Nuclear Data, Model 4420 multichan-nel Spectrcneter using a GeLi detector.
The most inactive sample (#6-5)
Uns selected as a control for geometry.
That sample had no measureable induced activity; chly potassium-40 was present.
That sample was spiked using 0 5 milliliters of a Mixed Radionuclide Gamma-ray /120/43, plus 1 5 Reference Stan-dard, Radiochemical Centre, Code QCY.44, Solution # R9 milliters of distilled water ( used as wash.)
The sample was thorough-J ly mixed prior to counting.
The results of the analysis were used to prepare a geometry table for calculation of the activities in the re-maing samples.
All spectra were processed using the Nuclide Identi-fication software system which is part of the spectrometer.
The peak energies were checked manually and were found to be due to three
The following tables summarize the results:
I.D. #
Depth in Activity Inches picocuries / gram Co-60 Eu-152 as of 15 January 1979 3-1 0 -- 1 90 35.54 63 31 3-2 1 90 - 3 43 13 99 23 99 3-3 3.43 - 5.74 11.19 30.04 3-4 5 74 - 7.23 10.29 17.67 3-5 '
7.23 - 9 59 2 91 7.82 3-6 9 59 -11.65 3 49 6 46 3-7 11.65 -13.66 2.05 2.11 1
3-8 13 66 -15.68 1 40 1 36 3-9 15 68 -18.48 75
.83*
3-10 18.48 -20 70 53 48*
3-11 20.70 -22 94 3-12 22 94 -24.02
- 1arge error, not all peaks were present Sample #4 4-1 0
- 1 36 73 09 123 40
pags 3' Sample # 4 (continued)
I.D. #
Depth in Activity Inches picocuries / gram Co-60 Eu-152 as of 15 January 1979 4-2 1 36 - 3 0 45 80 81.23 4-3 30
- 4.88 28.46 63 39 4-4 4.88 - 6.08 17.68 38.82 4-5 6.08 - 7 54 40.0 60.0*
4-6 7.54 - 9 25 13 91 19 1 4-7 9 25 -10 37 5.69 11.2 4-8 10 37 -12.09 3 82
.694
- Peak peculiarit,", not all energies present Sample #6 6-1 0
- 2.05 75 59 6-2 2.05 - 5.23 36 6-3 5.23 - 7.76 44*
6-4 7 76 -10.29 6-5 10.29 -11 98
- peak peculiarity, not all energies present l
The potassium-40 activity in the samples ranged from 17 to 30 pico-curies per gram.
When plotted on semi-log graph paper ( log activity versus depth )
the data follows an exponential function, more-or-less, which is in-dicative of neutron activation of the materials.
The activities are also approximately the same order of magnitude as the natural K-40.
We believe that the levels found are so low that they do not con-stitute any significant health hazard.
We, therefore, propose that the sito be released from restrictions.
As noted in previous correspondence the University has no plans to remove the biological shield in the immediate future.
The site is part of the Stanford Campus and cannot be disposed of in accordance with the terms of the founding grant.
The building, a large barn-like structure is likely to be used for en-gincering and scientific research projects in the near future.
The reactor biological shield will remain secured to prevent physical ( non~-
page 4 radiological ) injuries due to tripping, getting cut, or bumping one's head.
Please inform us if you need any further information for you to finalize the termination.
Very truly yours, W
/
John A. Holmes Senior Health Physicist For the Board of Trustees of the T., eland Stanford Junior University h
Roland A. Finston, Ph.
D.,
Director, Health Physics and Biosafety cc. State of California Dept. of Health Services / Radiological Health Section
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