IE Circular No. 81-07, Control of Radioactively Contaminated Material
SSINS: 6830
Accession No.:
8103300375
IEC 81-07
UNITED STATES
NUCLEAR REGULATORY COMMISSION
OFFICE OF INSPECTION AND ENFORCEMENT
WASHINGTON, D.C. 20555
May 14, 1981
IE Circular No. 81-07: CONTROL OF RADIOACTIVELY CONTAMINATED MATERIAL
Description of Circumstances:
Information Notice No. 80-22 described events at nuclear power reactor
facilities regarding the release of radioactive contamination to
unrestricted areas by trash disposal and sale of scrap material. These
releases to unrestricted areas were caused in each case by a breakdown of
the contamination control program including inadequate survey techniques,
untrained personnel performing surveys, and inappropriate material release
limits.
The problems that were described in IE Information Notice No. 80-22 can be
corrected by implementing an effective contamination control program through
appropriate administrative controls and survey techniques. However, the
recurring problems associated with minute levels of contamination have
indicated that specific guidance is needed by NRC nuclear power reactor
licensees for evaluating potential radioactive contamination and determining
appropriate methods of control. This circular provides guidance on the
control of radioactive contamination. Because of the limitations of the
technical analysis supporting this guidance, this circular is applicable
only to nuclear power reactor facilities.
Discussion:
During routine operations, items (e.g., tools and equipment) and materials
(e.g., scrap material, paper products, and trash) have the potential of
becoming slightly contaminated. Analytical capabilities are available to
distinguish very low levels of radioactive contamination from the natural
background levels of radioactivity. However, these capabilities are often
very elaborate, costly, and time consuming making their use impractical (and
unnecessary) for routine operations. Therefore, guidance is needed to
establish operational detection levels below which the probability of any
remaining, undetected contamination is negligible and can be disregarded
when considering the practicality of detecting and controlling such
potential contamination and the associated negligible radiation doses to the
public. In other words, guidance is needed which will provide reasonable
assurance that contaminated materials are properly controlled and disposed
of while at the same time providing a practical method for the uncontrolled
release of materials from the restricted area. These levels and detection
capabilities must be set considering these factors: 1) the practicality of
conducting a contamination survey, 2) the potential of leaving minute levels
of contamination undetected; and, 3) the potential radiation doses to
individuals of the public resulting from potential release of any
undetected, uncontrolled contamination.
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IEC 81-07
May 14, 1981
Page 2 of 3
Studies performed by Sommers1 have concluded that for discrete particle
low-level contamination, about 5000 dpm of beta activity is the minimum
level of activity that can be routinely detected under a surface
contamination control program using direct survey methods. The indirect
method of contamination monitoring (smear survey) provides a method of
evaluating removable (loose, surface) contamination at levels below which
can be detected by the direct survey method. For smears of a 100cm2 area (a
de facto industry standard), the corresponding detection capability with a
thin window detector and a fixed sample geometry is on the order of 1000 dpm
(i.e. , 1000 dpm/100 cm2). Therefore, taking into consideration the
practicality of conducting surface contamination surveys; contamination
control limits should not be set below 5000 dpm/100 cm2 total and 1000 dpm/
100 cm2 removable. The ability to detect minute, discrete particle
contamination depends on the activity level, background, instrument time
constant, and survey scan speed. A copy of Sommers studies is attached which
provides useful guidance on establishing a contamination survey program.
Based on the studies of residual radioactivity limits for decommissioning
(NUREG-06132 and NUREG-07073), it can be concluded that surfaces uniformly
contaminated at levels of 5000 dpm/ 100cm2 (beta-gamma activity from nuclear
power reactors) would result in potential doses that total less than 5
mrem/yr. Therefore, it can be concluded that for the potentially undetected
contamination of discrete items and materials at levels below 5000
dpm/100cm2, the potential dose to any individual will be significantly less
than 5mrem/yr even if the accumulation of numerous items contaminated at
this level is considered.
Guidance:
Items and material should not be removed from the restricted area until they
have been surveyed or evaluated for potential radioactive contamination by a
qualified* individual. Personal effects (e.g., notebooks and flash lights)
which are hand carried need not be subjected to the qualified individual
survey or evaluation, but these items should be subjected to the same survey
requirements as the individual possessing the items. Contaminated or
radioactive items and materials must be controlled, contained, handled,
used, and transferred in accordance with applicable regulations.
The contamination monitoring using portable survey instruments or laboratory
measurements should be performed with instrumentation and techniques (survey
scanning speed, counting times, background radiation levels) necessary to
detect 5000 dpm/100 cm2 total and 1000 dpm/100 cm2 removable beta/gamma
contamination. Instruments should be calibrated with radiation sources
having consistent energy spectrum and instrument response with the
radionuclides being measured. If alpha contamination is suspected
appropriate surveys and/or laboratory measurements capable of detecting 100
dpm/100 cm2 fixed and 20 dpm/100 cm2 removable alpha activity should be
performed.
*A qualified individual is defined as a person meeting the radiation
protection technician qualifications of Regulatory Guide 1.8, Rev. 1, which
endorses ANSI N18.1, 1971.
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IEC 81-07
May 14, 1981
Page 3 of 3
In evaluating the radioactivity on inaccessible surfaces (e.g., pipes, drain
lines, and duct work), measurements at other appropriate access points may
be used for evaluating contamination provided the contamination levels at
the accessible locations can be demonstrated to be representative of the
potential contamination at the inaccessible surfaces. Otherwise, the
material should not be released for unrestricted use.
Draft ANSI Standard 13.124 provides useful guidance for evaluating
radioactive contamination and should be considered when establishing a
contamination control and radiation survey program.
No written response to this circular is required. If you have any questions
regarding this matter, please contact this office.
REFERENCES
1 Sommers, J. F., "Sensitivity of Portable Beta-Gamma Survey
Instruments," Nuclear Safety, Volume 16, No. 4, July-August 1975.
2 U.S. Nuclear Regulatory Commission, "Residual Radioactivity Limits for
Decommissioning, Draft Report," Office of Standards Development, USNRC
NUREG-0613, October 1979.
3 U.S. Nuclear Regulatory Commission, "A Methodology for Calculating
Residual Radioactivity Levels Following Decommissioning," USNRC
NUREG-0707, October 1980.
4 Draft ANSI Standard 13.12, "Control of Radioactive Surface
Contamination on Materials, Equipment, and Facilities to be Released
for Uncontrolled Use," American National Standards Institute, Inc., New
York, NY, August 1978.
Attachments:
1. Reference 1 (Sommers Study)
2. Recently issued IE Circulars
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Page Last Reviewed/Updated Tuesday, March 09, 2021