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THE
ORCBS > Radiation
Safety
> Radiation
Safety Manual
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 Area
Restrictions
All rooms or areas
in which licensed quantities of radioactive materials are used or
stored must be posted with a "Caution Radioactive Material"
sign, an "NRC Licensing and Regulation Information Bulletin"
sign, and a "Notice To Workers" sign. Door signs must include
the principal investigator's name and phone number, and where he or
she can be reached in the event of an emergency. Postings can be obtained
from the ORCBS.
The following
chart definitions are set forth in the federal law for area restrictions.
DEFINITION
OF AREA RESTRICTIONS
10
CFR 20.1003
- Unrestricted
Area
- An area,
access to which is neither controlled nor restricted by the licensee.
- Restricted
Area
- An area,
access to which is limited by the licensee for the purpose of
protecting individuals against undue risks from exposure to radiation
and radioactive materials. A restricted area does not include
areas used as residential quarters, but separate rooms in a residential
building may be used as a restricted area.
- Controlled
Area
- An area,
outside of a restricted area but inside of the site boundary,
access to which can be limited by the licensee for any reason.
- Radiation
Area
- An area,
accessible to individuals, in which radiation levels could result
in an individual receiving a dose equivalent in excess of 5 mrem
in 1 hour at 30 centimeters from the radiation source or from
any surface that the radiation penetrates.
- High Radiation
Area
- An area,
accessible to individuals, in which radiation levels could result
in an individual receiving a dose equivalent in excess of 100
mrem in 1 hour at 30 centimeters from the radiation source or
from any surface that the radiation penetrates.
-
- Very High
Radiation Area
- An area,
accessible to individuals, in which radiation levels could result
in an individual receiving an absorbed dose in excess of 500 rads*
in 1 hour at 1 meter from a radiation source or from any surface
that the radiation penetrates.
*The exposure
rates for Very High Radiation Areas are in rads, rather than rems,
because potentially life threatening exposures could result in areas
with these fluxes of radiation.
At Michigan
State University, most of the radiation use areas on campus are
managed as restricted areas. Most radiation use areas are open
to the public, and may have both radiation workers and other individuals
present often or all of the time. Members of the public are permitted
to be present, as long they are escorted by a trained worker while
in the restricted area or have been trained in radiation safety
to work independently. Principal investigator training accomplishes
training requirements for workers frequenting the laboratory but
not handling radioactive materials.
Within the restricted
area, it is imperative that strict surveillance be maintained to
assure that significant exposure levels are not present, whether
in the form of contamination, airborne levels of radiation or external
exposure levels. For this reason, unrestricted area limits for contamination,
exposures and/or releases are to be adhered to at all times, rather
than restricted area limits. We have been using the unrestricted
area limits for several years at Michigan State University as a
part of our ALARA program management.
Another very
important requirement for restricted areas is the security of radioactive
materials. It is the responsibility of all workers frequenting a
restricted area to maintain security. This is discussed in the section
on security of radioactive materials.
Other radiation
area restriction categories (radiation area, high radiation area,
etc.) exist only in a few specific locations, which are typically
not accessible to the general public. In the event of emergency
or other unusual situations, any of the restricted areas may be
restricted to a more secure level to protect against radiation or
any other hazard which may be present. If this were to occur, the
area(s) would be clearly marked and posted with warning signs or
barriers.
Warning signs
and labels are available from the ORCBS. Indiscriminate use
of warning signs and/or labeling of non-radioactive materials with
"Radioactive" stickers or labels is prohibited.
Labeling
Requirements
Radiation
Safety Manual Table of Contents
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