ML19221A245
| ML19221A245 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 04/20/1979 |
| From: | Eisenhower E COMMERCE, DEPT. OF |
| To: | Cohen L NRC OFFICE OF INSPECTION & ENFORCEMENT (IE) |
| Shared Package | |
| ML19221A244 | List: |
| References | |
| NUDOCS 7905210062 | |
| Download: ML19221A245 (1) | |
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h UrJITED GTATES DCP/1HTMCTJT OF COMMERCE I_C '
rJational Bureau of Standards
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wasn ngton, O C. 20234 20 April 1979
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Dr. Lawrence K. Cohen DS i
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Division of Fuel Facility j
and Materials Safety Inspection i
office of Inshection and Enforcement U.S. Nuclear Regulatory Cc.nnission Wa shington, 'O. C-'~ 20555 Dear Dr. Cohen. C In response to your request, NBS exposed a number of thermolo:inescence dosimeters to radiation under specified conditions.
This letter des-cri -s the important characteristics of the radiation fields used to expose the dosimeters provided by you on April 6.
Two distinct procedures were employed, and they are described separately.
Photon Exposure
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The photen r.urce was 179 mci of xenon-133 gas seated to a glass ampoule.
T: e dasimeters were exposed for one hour at a distance of 11 inches (28 cm) from the center of the source.
The calculated value of the exposure was 104 milliroentgens, taking into account absorption of the 81-kcV ganr.a rays and 30-kev x rays by the arpoule walls and 28 cm of air.
The measured value of expo.sure rate at the point of exposure was 107 mR/h. using ionization char.ter instruments.
The estimated ruximum uncertainty in the calculated and treasured values of total exposure is :15 percent.
During exposure, the dosimeters were attached to a nnminal 2" x 4" x 6" block of wocd to simulate field conditions.
The folicwing dosimeters were e:, posed under the conditions described
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- Source or Type of Identification Exposed Manufacturer User Material Numbers 2
RMC Metropolitan CaSO (Tm) 450077 Edison powder 460258 1
Teiedyne Metropolitan CaS0;(Dy)
TM-9G1 Edison 1
Harshaw BRH LfF 177 1
Harshaw EPA -
CaF (Dy) 29
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RT*C (red)
NRC L i 8 0, 2 %
Ca50 (Tm) 4,6,7 5
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3 FoiC (greeiij NRC Li28,07
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Ca50,(Tm) 15,58.60
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-2 These exposed dosimoters were returned to you on April 7 for subseq' Eent~
evaluation by the users.
At the sare time, those dosimeters which
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served as controls were also returned to you.
Pho_ ten and Geta-Radiation Exposure The radiation source was 7.6 millicuries of xenon-133 contained in a scaled hollow glass sphere with an internal radius of 10.8 cm and a contained volume. of,5,290 milliliters.
The length of exposure was 7.42 hcurs, and_the dosimeters were located on the icwcr inside surface of the_ spher'e.
The xenon gas was added to the air contained at room
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temperatur,e and Atrespheric pressure.
The dosimeters were irradiated in the plastic containers used for deployment in field locations.
Upon termination of the irradiation, it was observed that xenon gas had permeated the plastic containers.
No circulation or mechanical mixing of the ccntained xenon and air was provided during irradiation.
At this time we are unable to provide a quantitative characterization, within acceptable limits of uncertainty, of the radiation field at the point of irr adiation.
There is some possibility that an acceptabir quantification may be obtained within several weeks, based on a thorough cvaluation of the response of lithium fluoride chips which werc
. 3 irradiated simul taneously with the dos imeters.
The following dosimeters were irradiated within the sphere:
Number Source or Type of Identification Exposed Ma nu fa c turer
_ User Ma terial Numbers 2
RMC Metropolitan Ca SO. (Tm) 460102 Edison powder 460219 1
Teledyne 1
Harshaw. - -
Metropolitan Edison Ca SO. (Dy)
TM-4G1 BRH LiF 190
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Harshaw
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,CaF (Dy) 409 2
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RMC (red)
Li 8,07 2
5,8,9,10
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CaSO.(Tm)
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RMC (green)
NRC Lf 8,0, 11,12,18,57 2
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Ca SO,(Tm)
These exposed dosimeters were returned to you on April 7 for subsequent evaluation by the users.
At the same time the folicwing dosimeters, which served as controls for both types of exposure, were also returned to you:
BRH (LiF) dosimeters numbered 175, 176, 192, and 193.
RMC (CaSO, powder) dosineters numbered 45C020, 460052, 460187,
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and 460202 e
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E'A (Harshaw) dosi:r.eter number 489 REC (green, NRC) dosir,eter number 59
. Teledyne -(fietropoli tan Edison) cosi;r.eter number TF.-1031
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1 We would like to make it clear that the services provided by NBS were..
i limited to escposure of the dosimeters to radiation fields as charac-i terized a'>ove, under the specific conditions described.
Since it was not requested, no eYaluation of the radiation dose absorbed by the dosimeters was provided by NBS.
Except as described above, no attempt was made to sirylate field conditions that.tay have existed as a result of the Three Mil wIsland reactor incident.
It should not be assumed therefore, that 'the dosimeter responses to the radiation exposure pro-vided by t;SS would be the same as the responses to radiation emitted during the incident.
Sincerely, J:%R%
Elmer H. Eisenhower Chief, Office of Radiation Measurrment
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