Information Notice 2021-02, Recent Issues Associated with Monitoring Occupational Exposure to Radiation from Licensed and Unlicensed Radiation Sources
| ML21152A239 | |
| Person / Time | |
|---|---|
| Issue date: | 08/04/2021 |
| From: | Chris Miller, Kevin Williams Office of Nuclear Material Safety and Safeguards, Office of Nuclear Reactor Regulation |
| To: | |
| Benney B | |
| References | |
| IN-21-002 | |
| Download: ML21152A239 (7) | |
ML21152A239 UNITED STATES
NUCLEAR REGULATORY COMMISSION
OFFICE OF NUCLEAR MATERIAL SAFETY AND SAFEGUARDS
WASHINGTON, DC 20555-0001
August 4, 2021
NRC INFORMATION NOTICE 2021-02: RECENT ISSUES ASSOCIATED WITH
MONITORING OCCUPATIONAL EXPOSURE
TO RADIATION FROM LICENSED AND
UNLICENSED RADIATION SOURCES
ADDRESSEES
All U.S. Nuclear Regulatory Commission (NRC) materials licensees. All Radiation Control
Program Directors and State Liaison Officers.
PURPOSE
The NRC is issuing this information notice (IN) to inform addressees of recent issues
associated with monitoring occupational exposure to radiation from licensed and unlicensed
radiation sources under the licensees control. The NRC expects that recipients will review
the information for applicability to their facilities and consider actions, as appropriate, to
avoid similar problems. Any suggestions contained in the IN are not new NRC
requirements; therefore, no specific action or written response is required. The NRC is
providing this IN to the Agreement States for their information and for distribution to their
licensees as appropriate.
DESCRIPTION OF CIRCUMSTANCES
From August 2018 to October 2020, the NRC identified issues at seven NRC medical-use
licensees involving compliance issues associated with monitoring individuals occupational
exposure to radiation from licensed and unlicensed radiation sources that were under the
control of the licensees. The issues were associated with occupational radiation exposures
received by interventional radiology (IR) physicians who were involved in the conduct of
NRC-licensed activities under the provisions of 10 CFR 35.1000, Other medical uses of
byproduct material or radiation from byproduct material. Although the issues described in
this IN were identified at NRC medical-use licensees, the information provided is applicable
to all NRC licensees where occupational radiation exposures from licensed and unlicensed
radiation sources can occur.
Monitoring Exposure to Unlicensed Radiation Sources Under Licensee Control
The IR physicians performed activities involving the administration of yttrium-90
microspheres, which is an NRC-licensed radioactive byproduct material. Additionally, the IR
physicians were exposed to unlicensed radiation sources. Unlicensed radiation sources are
not licensed by the NRC and include radiation from certain radiation-producing devices, such as fluoroscopy equipment and other x-ray-generating devices. Although not licensed
by the NRC, these sources of radiation may be subject to registration with state regulatory
agencies. Specifically, at the seven NRC medical-use licensees, IR physicians used fluoroscopic
(x-ray) guidance to place an intraarterial microcatheter to the targeted delivery area for the
yttrium-90 microspheres. The IR physicians who administered the yttrium-90 microspheres
also performed numerous other IR procedures using fluoroscopic guidance that did not
involve the use of NRC-licensed radiation sources.
During NRC inspections at the medical-use licensees, the NRC identified several issues, including licensees understanding of the NRC regulatory requirement in
10 CFR 20.1502(a). This regulation requires that each licensee monitor exposure to
radiation and radioactive material at levels sufficient to demonstrate compliance with the
occupational dose limits specified in 10 CFR Part 20, Standards for protection against
radiation. In accordance with 10 CFR 20.1502, Conditions requiring individual monitoring
of external and internal occupational dose, requires monitoring of exposure to licensed and
unlicensed radiation sources under the control of the licensee:
As a minimum, each licensee shall monitor occupational exposure to radiation
from licensed and unlicensed radiation sources under the control of the licensee
and shall supply and require the use of individual monitoring devices by
(1) Adults likely to receive, in 1 year from sources external to the body, a dose in
excess of 10 percent of the limits in 10 CFR 20.1201(a); (2) Minors likely to
receive, in 1 year, from radiation sources external to the body, a deep dose
equivalent in excess of 0.1 rem (1 mSv), a lens dose equivalent in excess of
0.15 rem (1.5 mSv), or a shallow dose equivalent to the skin or to the extremities
in excess of 0.5 rem (5 mSv); (3) Declared pregnant women likely to receive
during the entire pregnancy, from radiation sources external to the body, a deep
dose equivalent in excess of 0.1 rem (1 mSv); and (4) Individuals entering a high
or very high radiation area.
The NRC observed that some IR physicians wore assigned individual monitoring devices
(personnel dosimeters) inconsistently. For example, some IR physicians wore the assigned
personnel dosimeter only during yttrium-90 procedures, but not during IR procedures that
did not involve yttrium-90, under the misunderstanding that their exposure to unlicensed
x-ray sources was not required to be monitored. The inspectors also observed that some IR
physicians did not wear assigned personnel dosimeters at all when working with either
licensed or unlicensed radiation sources.
In accordance with 10 CFR 20.1101(a), licensees are required to develop, document, and
implement radiation protection programs commensurate with the scope and extent of
licensed activities and sufficient to ensure compliance with the provisions of 10 CFR Part 20,
Standards for protection against radiation. NRC inspectors found that licensees radiation
protection programs, specifically their policies and procedures for occupational dosimetry
programs, often did not have provisions to address 10 CFR 20.1201(f) and 10 CFR 20.2104, Determination of prior occupational dose. As a result, licensees did not account for
occupational radiation exposure received by individuals either: (1) concurrently while
employed at other facilities, including other NRC-licensed facilities, Agreement
State-licensed facilities, or unlicensed facilities, or (2) during the same calendar year, prior to
the individual performing licensed activities under the licensees control. Consequently, licensees were not cognizant of the total radiation dose received by those individuals and
whether this additional occupational dose would result in any radiation doses in excess of
the NRCs regulatory limits. Improper Use and Implementation of Dosimetry Approaches
The NRC found that the proper use of personnel dosimeters varied significantly among IR
physicians. In some cases, IR physicians wore their personnel dosimeter improperly, which
included not wearing the personnel dosimeter in the assigned location in accordance with
licensees policies (e.g., collar vs. waist, or above lead shielding vs. under lead shielding).
At one licensee, personnel dosimeters not being worn were stored improperly in a radiation
area. Several IR physicians did not exchange assigned personnel dosimeters at the
indicated frequency or often wore them significantly beyond the monitoring period indicated
on the dosimeter.
Dosimetry vendors often offer single- and double-dosimeter approaches with correction
factors to take nonuniform radiation exposures into account, such as those occupational
exposures received when wearing a lead apron during the performance of IR procedures.
Some licensees did not establish policies or procedures to address the dosimetry approach
used.
As a result, licensees inconsistently applied correction factors, which most often occurred
with double-dosimeter approaches. Double-dosimeter approaches typically rely on one
dosimeter to be worn at the collar outside of the lead, and one dosimeter to be worn at the
waist under the lead. Licensees that used a double-dosimeter approach often did not have
policies and procedures that addressed issues that would reasonably be expected to arise
from this dosimetry approach. For example, licensees did not have policies or procedures
for actions to be taken if one or both assigned personnel dosimeters were not turned in for
processing at the end of the assigned wear period. Licensees policies often did not
address actions to be taken if the personnel dosimeters were not worn at the assigned
location, such as if the waist dosimeter were worn at the collar outside of the lead. The NRC
observed that when this occurred, the licensee-assigned radiation exposures were often
higher, and in some cases grossly higher, than those that would have been expected for the
individual IR physician caseload.
Radiation Safety Programs: Training and Oversight
The NRC also identified various deficiencies regarding licensees implementation and
oversight of their radiation safety programs. These included deficiencies in licensees
radiation safety program content and implementation and their training programs.
Licensees also did not implement corrective actions to address identified personnel
dosimetry issues.
In the area of licensees radiation safety program content and implementation, the
inspectors found that licensees did not comply with 10 CFR 20.1101(a), which requires that
licensees develop, document, and implement radiation protection programs that are
commensurate with the scope and extent of licensed activities and sufficient to assure
compliance with 10 CFR Part 20. For several of the medical-use licensees involved in these
cases, the NRC found that the licensees radiation safety policies and procedures did not
adequately describe their personnel dosimetry program or to require the use of individual
monitoring devices.
In some cases, through routine audit and oversight activities, licensees or their third-party
auditors identified issues with individuals not wearing, or improperly wearing, their assigned
personnel dosimeters. However, when issues were identified, licensees either did not investigate these matters and implement corrective actions, or the corrective actions that
they implemented were not sufficient to correct the issues and prevent recurrence.
Although the NRC found most licensees policies and procedures for occupational dosimetry
programs to have established thresholds to identify unusually high radiation exposures, the
licensees did not to establish mechanisms to identify occupational radiation exposure values
that were unusually lower than expected, or where no results were reported. For example, several IR physicians performed over 100 IR procedures a month, but their monthly
personnel dosimeter reading was less than 1 millirem. It is unlikely that the performance of
over 100 IR procedures in 1 month would result in little to no measurable radiation dose.
These licensees did not have mechanisms to identify or flag these unusually low dosimeter
readings for further review or investigation.
Some licensees performed routine reviews of dosimeter results and identified unusually high
radiation exposures for IR physicians. However, in many cases, the licensees did not
investigate the cause of these excessively high or anomalous dosimeter readings. In some
cases, the licensees investigations consisted of a written warning to the IR physicians, but
the licensees did not actually investigate or attempt to understand the causes of the high or
anomalous dosimeter readings. In one case, a licensee observed high dosimeter results for
an IR physician and investigated the matter. The licensee determined that the IR physician
was wearing the assigned dosimeter correctly, while the other IR physicians with lower
dosimeter results were not wearing their assigned dosimeters correctly. However, the
licensee took no corrective actions to address the noncompliant dosimeter use by the other
IR physicians.
Licensees also did not provide adequate instruction to individuals in accordance with
10 CFR 19.12, Instruction to workers. In all cases, the NRC found that the licensees
provided the IR physicians with personnel dosimeters, but the IR physicians rarely received
instruction or training in the licensees policies and procedures for dosimeter use. NRC
inspectors observed that some licensees assumed that IR physicians would already
possess such knowledge, based on their education and credentials, and that licensee- specific training was not required or necessary. Some licensees simply did not include IR
physicians in licensee training programs. This was observed to be more prevalent when the
IR physicians were contracted individuals or independent radiology providers rather than
licensee employees.
DISCUSSION
The NRC regulates the possession and use of radioactive byproduct material, special
nuclear material, and source material. Licensed radiation sources are byproduct material, special nuclear material, and source material that are (1) authorized by a specific license
issued by the NRC or (2) authorized under a general license as specified in the NRC
regulations. Unlicensed radiation sources are those radiation sources that are not licensed
by the NRC under a specific or general license. Unlicensed sources include radiation from
certain radiation-producing devices, such as fluoroscopy equipment and other x-ray- generating devices. These unlicensed sources of radiation may be subject to registration
with state regulatory agencies.
Although the NRC identified the issues described in this IN at its medical-use licensees,
10 CFR 20.1501(a) is applicable to all NRC licensees where occupational radiation
exposures from licensed and unlicensed radiation sources can occur. For example, some industrial radiography licensees use radiographic exposure devices with NRC-licensed
byproduct material radioactive sources, such as cobalt-60 and iridium-192, and also use
radiographic exposure devices that employ x-ray-generating sources, which are not licensed
by the NRC. If occupationally exposed individuals, such as industrial radiographers, use
byproduct material radioactive sources and x-ray-generating sources under the control of
the licensee, the licensee is required to monitor the occupational radiation exposures to
these individuals from both of these radiation sources.
In accordance with 10 CFR 20.1502(a), licensees are to supply and require the use of
individual monitoring devices for the specified categories of occupationally exposed
individuals. It is only through the proper use of these individual monitoring devices that
licensees can evaluate radiation doses to determine compliance with the NRCs
occupational dose limits.
The NRC identified compliance issues associated with the licensees occupational radiation
monitoring programs resulted in escalated enforcement action against several licensees and
required extensive licensee actions to correct the deficiencies. The licensees efforts
included significant revisions to licensees radiation safety programs, procedures and
policies, training programs, and oversight practices. Further, licensees corrective actions
included complex evaluations of radiation exposure data to determine radiation dose
estimates. Many of the licensees had to make radiation dose estimates for multiple IR
physicians for occupational radiation exposures that occurred over several years for
licensed and unlicensed radiation sources under the control of the licensees. Although
licensees radiation dose estimates resulted in no individual exceeding the NRCs
occupational dose limits specified in 10 CFR Part 20, several individuals closely approached
those limits.
The NRC expects that licensees will develop, implement, and maintain radiation protection
programs, including programs for monitoring occupational radiation exposures, that are
commensurate with the scope and extent of their activities, in accordance with
10 CFR 20.1101(a). NRC inspectors have found that effective licensee radiation protection
programs include policies and procedures associated with monitoring occupational radiation
exposures. NRC inspectors found that comprehensive and effective policies and
procedures for monitoring occupational radiation exposures included provisions to address:
(1) criteria for occupational monitoring at the licensees facility; (2) prior or concurrent
occupational radiation exposures to licensed and unlicensed radiation sources;
(3) responsibilities for individuals to properly wear dosimeters; (4) licensee-specified
dosimeter wear locations; (5) expectations for turning in dosimeters for processing at the
end of assigned wear periods; (6) lost or missing dosimeters; (7) proper storage of
dosimeters when not in use; (8) prompt evaluation of dosimeter results; (9) criteria to
evaluate or investigate unusually low or high dosimeter results; and (10) periodic reviews
and oversight of licensee dosimetry programs. Because dosimetry approaches and
programs vary widely, it is important for individuals to receive licensee-specific training on
the policies and procedures that pertain to dosimeter use.
In accordance with 10 CFR 20.1101(c), licensees shall periodically (at least annually) review
the radiation safety program content and implementation. Effective auditing and radiation
safety program reviews may allow licensees to promptly identify compliance issues
associated with occupational monitoring programs and take actions to correct any identified
deficiencies and prevent recurrence. Licensees with effective auditing programs typically
use a combination of auditing techniques, including records review and direct observation of occupationally exposed individuals. For records reviews, licensees may find it beneficial to
compare dosimeter results data with information or data related to individuals licensed
activities (i.e., radioisotopes used, quantity used, frequency of use) and unlicensed activities
(i.e., characteristics of specific x-ray-generating devices used, duration of use, frequency of
use). Some licensees have found that such comparisons can be accomplished through
automated data collection systems that can flag discrepant data or be set to flag or identify
values that meet certain thresholds established by the licensee. For direct observation, licensees may elect to perform periodic spot-checks of occupationally exposed individuals
during licensed and unlicensed activities to determine whether dosimeters are being worn
properly. If licensee evaluations determine that occupational radiation doses exceed the
limits in 10 CFR Part 20, licensees are required report to the NRC in accordance with
10 CFR 20.2203, Reports of exposures, radiation levels, and concentrations of radioactive
material exceeding the constraints or limits.
CONTACT
This IN requires no specific action or written response. If you have any questions about the
information in this notice, please notify the technical contact listed below or the appropriate
regional office.
/RA/
/RA/
Christopher G. Miller, Director
Division of Reactor Oversight
Office of Nuclear Reactor Regulation
Kevin Williams, Director
Division of Materials Safety, Security, State, and Tribal Programs
Office of Nuclear Material Safety
and Safeguards
Technical Contact:
Janine F. Katanic, PhD, CHP, NRC Region IV
(817) 200-1151
E-mail: Janine.Katanic@nrc.gov
EPIDS No. L-2021-GEN-0006 OFFICE
Author
QTE
Authors BC
NRR/DRO/IOEB/PM
NRR/DRO/LA
NAME
JFKatanic/RA/
JDougherty /RA/
LRoldanOtero/RA/
JPeralta
BBenney
IBetts
DATE
6/8/21
6/3/21
6/2/21
6/16/21
6/22/21
06/21/21 OFFICE
NRR/DANU/NPUF/BC
NRR/DRO/IOEB/BC
NMSS/MSST/D
NRR/DRO/D
NAME
JBorromeo
LRegner
KWilliams
KMorgan- Butler for
CMiller
DATE
6/22/21
7/22/21
7/29/21
8/04/21