ML20100P133
| ML20100P133 | |
| Person / Time | |
|---|---|
| Site: | Harris  |
| Issue date: | 10/22/1984 |
| From: | Miklos J, Plato P MICHIGAN, UNIV. OF, ANN ARBOR, MI |
| To: | |
| References | |
| RTR-NUREG-CR-2891 OL-B-002, OL-B-2, NUDOCS 8412140025 | |
| Download: ML20100P133 (4) | |
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Personnel Dosimetry Services 1
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Final Report of Test #3 1
i Prepared by P. Plato, J. Miklos
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A.45 Testing for consistance is of necessity limited to categories I through j
i V.
Categories VI through VIII are not readily amenable to consistency testing 1
Lacause the difference in the evaluation process for different types of i
ra ff ation makes it difficult to devise a fair test procedure. It is desirable to have consistency evaluations performed on the data for each complete test I
period in categories I through V, and to provide the processor with the results
. of this evaluation. When a trend or other sign of lack of consutancy is notice.' in a processor's test parameters for successive tests, it is important that the reasons for such behavior be detensined, since lack of consistency may fore.;hadow futum failure of perfornance tests.
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Choice of Tolerance Level, L 9
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The values chosen for the tolerance level represent a compromise between j
the reconne.dations of international authorities in the field of radiation protection a ;d radiation measurements, and the limitations dictated by avail-able measurement techniques. In ICRU Report No. 20 (E20] and NCRP Report No. 57 (E41]. a 30% limit is recommended for the uncertainty in the maximum dose equivalent in the vicinity of the maximum permissible levels, while an uncertainty of as much as a factor of three is considered acceptable for maximum
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In ICRP Report No.12 (E42],
dose equivalents suller by an order of magnitude.
on the other hand, a limit of 50% is reconnended in the vicinity of naximum permissible levels under field conditions, when* errors, caused by unknown irra-i diation geometry or ambient conditions are taken into account. For dose inter 9retations at accident levels, a tolerance level of 20% is reconnended in NCRP Report 57. In this standard, a fixed irradiation geometry and laboratory ambient conditions are saecified for the test irradiations. Because of limita-tions in measo'rement technique, the tolerance level is set at 0.5 (50%) for 1
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all but the accident categories and the high-energy photon categories, where it is set at 0.3 (37.)., Larger tolerance levels for dose equivalents well below the maximum permissible dose equivalent were considered and in fact had been incorporated in the first version of this standard. Subsequent tc, the experience gained in the pilot-testing program referred to in the Foreword, this feature was deleted since for the tests specified in thi, l
standard (calling for irradiation in relatively straightforward radiation fields under ideal laboratory conditions and evaluation of perfonnanca from l
average errors obtained over a large ra se of dose equivalents) rela <ation I
of the tolerance levels was found to be unnecessary.
I D4. Sources of Uncertainty Not Included in the Performance Evalua:icn I
This standard does not include provisions for testing a supplier's performance under the various possible conditions of practical use of the personnel dosimeters. Among the common source; of uncertainty.1ot included are:
I (1) Dependence of dosimeter response on radiation energy for a given type of radiation and geometry of radiation incidence.
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(2) Dependence of dosimeter response on angle of radir. tion incidence for l
different types of radiation and different radiation enerfsies.
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i (3)Dependenceofresponseonambienttemperature,includingstorage l
temperature before, during, and after irradiations, up to the time of i
processing or readout.
(4) Dependence of response on ambient humidity, including storage l
humidity, before, during, and after irradiation, up to the time of processing l
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or readout.
i (5) Time intervals between dosimeter issue, irradiation, and processing I
or readout.
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l A.47 (6) Dependence of response on visible and ultraviolet light prior to, during, and after irradiation, up to the time of processtng or readout.
f (7) Position of the badge on the human body relative to the point of maximum irradiation on the body surface, and relattve to the location of the i
organs of interest.
J (8) A possible bias in the performance on an open test, that is, a test j
t carried out with the knowledge of the processor, introduced by the processor's awarenes's of being tested.
The extent to which any one of these factors may contribute to a given l
interpretation of dosimeter response yarfes widely, depending on dosimeter i
design, processing and readout techniques. It is suggested that the testing 1
laboratory be in a position to evaluate the supplied dosimeter designs for the influence on interpretation of dosimeter response.cf any of these and other 4
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factors (such as, e.g., in the case of albedo-neutron dosimeters, dose equivalent assignment based on source-to-phantom surface distances as compared to assignment based on the distance betwen the source and the orfgin of the l
bulk of the thermal and/or eptthermal neutron albedo). Methods for carrying 1
out some of the required test procedures may be found in the literature [E43].
i Secause of the magnitude of the potential errors associated with angular dependence of dosimeter response, consideration was given to incorporating into the standard perfomance requirements related to response characteristics of test dosimeters as a function of angle of radiation incidence for different rt.itation energfes and types of radf ation. However, an adequate data base for the angular dependence of the response of the different types of personnel i
desineters irradiated on a phantom was not available. Therefore, it was l
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