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ES&H
Manual Radiation Control Supplement |
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Chapter 2 – Radiological Standards |
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Exposure to
ionizing
radiation, however small the amount, is presumed to involve some risk. To minimize radiation dose to personnel,
engineered and administrative controls are employed at Jefferson Lab. Physical design features are the primary
means by which unnecessary radiation exposures are prevented. Although all facilities have been designed
and constructed to minimize exposure, administrative controls are used as
supplemental measures to control radiation exposure. For these controls to be effective,
individual workers must understand and exercise their responsibilities in the
radiation protection program.
211
Administrative
Control Level
The following administrative limits have been established at Jefferson Lab for exposure to ionizing radiation:
211-01)
The Jefferson Lab Administrative Control Level (Action Level) is 1 rem per calendar year (whole body). No person shall be allowed to go above the Action
Level without the prior approval of the Jefferson Lab
Director. If an exposure exceeding the
Action Level occurs in the absence of prior planning and approval, the Notable
Event process will be employed to investigate the cause of the condition and
implement any needed corrective actions.
211-02)
An Administrative Control Level of 20 percent of the relevant
limit in 10 CFR 835 is established for dose to individual organs or
tissues. The approval and event
investigation requirements above apply to these limits also.
211-03)
Approval by the Program Secretarial Official or designee should be
obtained prior to allowing a radiological worker to exceed 2 rem (whole body).
211-04)
To maintain positive control of radiological worker exposure, an exposure alert system
is in effect at Jefferson Lab. When a radiological
worker’s annual radiation dose approaches or
exceeds 250 mrem (Jefferson Lab Alert Level), the worker and his/her supervisor shall be notified that
his/her exposure is at or has exceeded the
Jefferson Lab design goal. The worker
should then consult with his/her supervisor and with the Radiation
Control Department (RCD) to ensure that
supervisor and worker are doing as much as possible to minimize exposure to radiation and adhere
to the As
Low as Reasonably Achievable (ALARA) process.
211-05)
The Alert
Level for members of the general public, including employees who are not radiological workers, is 10 mrem. This dose
may be determined by either estimation or measurement. Exposures
shall be kept below the limits in Table 2-1A and maintained as low as reasonably achievable [§835.1003(a)].
Table 2-1A Occupational Limits and Administrative Control Levels (total effective dose)a, b
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|
Radiological
Workers |
General
Employees (total) |
|
Annual
Limit |
5 rem (50 mSv) |
100 mrem (1 mSv) |
|
Action Level |
1 rem (10 mSv) |
50 mrem (0.50 mSv) |
|
Jefferson
Lab Design Goals (Alert
Level) |
250 mrem (2.5 mSv) |
10 mrem (0.1 mSv) |
|
a Except
for planned special exposure conducted consistent with 10 CFR 835.204 and
emergency exposures authorized in accordance with 10 CFR 835.1302, the
occupational dose received by employees shall be controlled such that the
limits in the table are not exceeded in a year. b See 10
CFR 835.2 for definitions of dosimetric terms not defined in this manual. |
||
211-06)
All occupational doses received during the current year, except
doses resulting from planned special exposures conducted in compliance with 10
CFR 835.204 and emergency exposures authorized in accordance with 10 CFR
835.1302, shall be included when demonstrating compliance with 10 CFR 835.202(a)
and 835.207 [§835.202(b)]. Annual organ/extremity equivalent
dose limits are presented in Table 2-1B.
211-07)
Doses from background, therapeutic, and diagnostic medical radiation
and participation as a subject in medical research programs shall not be
included in dose records or in the assessment of compliance with the
occupational dose limits [§835.202(c)].
211-08)
For
the purpose of monitoring
individual exposures to internal radiation,
internal dose evaluation programs (including routine bioassay
programs) shall be conducted for radiological workers
who, under typical conditions, are likely to receive 100 mrem (0.001 sievert)
or more committed effective
dose, and/or 5 rem
(0.05 sievert) or more committed equivalent
dose to any organ or tissue, from all occupational radionuclide intakes in
a year.
211-09)
The
total effective
dose during a year is determined by summing
the effective
dose from external exposures
and the committed effective
dose from intakes during the year [§835.203(a)].
211-010) Equivalent dose
to the whole
body may be used as effective dose in evaluating
external exposures.
Determination of the effective dose shall be made using the radiation
and tissue weighting factor values provided in 10
CFR 835.2 . [§835.203(b)] For the case of uniform external irradiation
of the whole body, a tissue weighting factor equal to 1 may be used in
determination of the effective dose.
211-011) Any method used for internal and
external monitoring
shall be adequate to demonstrate compliance with limits for radiological
workers, declared pregnant radiological workers,
minors, and members of the general public.
Table 2-1B Annual Organ/Extremity Equivalent Dose Limits & Levels
|
Type of Exposurea |
Annual Limit |
Action Level |
Alert Level |
|
Equivalent dose to lens of
eye |
15
rem |
3 rem |
1 rem |
|
The sum of the equivalent
dose to the skin or any extremity (hands and arms below the elbows; feet and
legs below the knees) for external exposures and the committed equivalent
dose to the skin or to any extremity. |
50
rem |
10
rem |
2.5
rem |
|
The sum of the equivalent
dose to the whole body for external exposures and the committed equivalent
dose to any organ or tissue other than the skin or the lens of eye, |
50
rem |
10
rem |
2.5
rem |
|
a See 10 CFR 835.202
for definitions; see 10 CFR 835.205
for determination of non-uniform dose to the skin. |
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212
Radiological Worker Dose Limits for Routine Occupational Exposure
A radiological worker is any individual whose job assignment
involves operation of radiation producing devices or working with radioactive
materials, or who is likely to be routinely occupationally exposed above 0.1
rem (100 mrem) per year total effective dose.
The following limits have been established at Jefferson Lab for
occupational exposure to ionizing radiation:
212-01)
The annual exposure limits for radiological workers are found in
Tables 2-1A and 2-1B.
Occupational radiation exposure of Jefferson Lab radiological workers
resulting from DOE activities (other than planned
special exposures and emergency exposure situations indicated below),
shall be controlled so the annual limits listed in Tables 2-1A and 2-1B are not exceeded [§835.202(a), §835.1003(a)]].
212-02)
Occupational doses received as a
result of the following activities (which are excluded from the regulation) and
radioactive material transportation shall be included to the extent practicable
in determining compliance with occupational dose limits:
a)
Activities
conducted under the authority of the Deputy Directors for Naval Reactors as
described in Pub. L. 98-525 and 106-65;
b)
Activities
that are regulated through a license by the Nuclear Regulatory Commission or a
State under an Agreement with the Nuclear Regulatory Commission, including
activities certified by the Nuclear Regulatory Commission under section 1701 of
the Atomic Energy Act;
c)
Activities
conducted under the Nuclear Explosives and Weapons Surety Program relating to
the prevention of accidental or unauthorized nuclear detonations;
d)
DOE
activities conducted outside the U.S. on territory under the jurisdiction of a
foreign government to the extent governed by occupational radiation protection
requirements agreed to between the U.S. and the cognizant government; and
e)
Radioactive
material transportation not performed by DOE or a DOE contractor.
212-03)
A radiological worker whose
occupational exposure has exceeded the numerical value of the applicable limits
specified in Tables 2-1A and 2-1B (as a result of an authorized emergency exposure) may be permitted to return
to work in radiological areas during the current year, provided that all of the
following conditions are met [§835.1301(a)]:
a)
Approval is first obtained from
the contractor management and the Head of the responsible DOE field
organization;
b)
The individual receives counseling
from radiological protection and medical personnel regarding the consequences
of receiving additional occupational exposure during the year;
c)
The doses
exceeding the limits specified in Tables 2-1A and 2-1B have been recorded in the
individual’s occupational dose record [§835.1301(b)]; and
d)
The affected employee
agrees to return to radiological
work.
The table in Appendix 2A contains Guidelines for Control of
Emergency Exposures.
212-04)
When the conditions under which a
dose was received in excess of limits specified in Tables 2-1A and 2-1B (except
those doses received in accordance with provisions for planned special
exposures) have been eliminated, Jefferson Lab management will notify the
Jefferson Lab DOE Site Office Manager or designee [§835.1301(c)].
212-05)
Operations at Jefferson Lab that
use or produce ionizing
radiation or radioactive material, and which have been
suspended after an emergency or accidental exposure in excess of the limits specified in Tables 2-1A and 2-1B, will be
resumed only with the approval of the appropriate DOE authority, as indicated
in the DOE-approved Jefferson Lab Occurrence Reporting and Processing System
(as described in Chapter 5300 Occurrence Reporting to Department of Energy
(DOE) of the ES&H Manual) [§835.1301(d)].
212-06)
Jefferson Lab does not anticipate
rescue or recovery actions resulting in exposures in excess of
applicable regulations. However, Jefferson Lab will minimize the risk
of injury to those individuals involved in rescue and recovery operations [§835.1302(a)]. Jefferson
Lab management will weigh actual and potential risks to rescue and recovery
individuals against the benefits to be gained [§835.1302(b)]. Volunteers will perform any rescue actions at
Jefferson Lab that might involve substantial personal risk [§835.1302(c)]. Any
individual authorized to perform emergency
actions likely to result in occupational doses exceeding the limits for
radiological workers in Table 2-1A or 2-1B shall be
trained in accordance with §835.901(b) and be briefed beforehand of the known or anticipated hazards to
which the individual will be subjected [§835.1302(d)].
213
Planned
Special Exposures
for Radiological Workers
213-01)
A planned special exposure may be authorized for a radiological worker to receive doses (in addition to and
accounted for separately from the doses received
under the limits specified in Tables 2-1A and 2-1B), provided that the
following conditions are satisfied:
a) The planned special exposure is considered only in an exceptional situation when alternatives
that might prevent a radiological worker from exceeding
the limits in Tables 2-1A and 2-1B are
unavailable or impractical [§835.204(a)(1)].
b) The Jefferson Lab RCM and
Laboratory Director (and employer, if the employer is not Jefferson Lab)
specifically request the planned special exposure and submit the request in
writing for approval by the DOE [§835.204(a)(2)].
c) Joint written approval from the
appropriate DOE Headquarters program office and the Secretarial Officer
responsible for Environment, Safety and Health is received [[§835.204(a)(3)].
213-02)
Prior to requesting an individual
to participate in an authorized planned
special exposure, the individual’s dose from all previous planned special exposures and all doses in excess of
occupational dose limits shall be determined [§835.204(b)].
213-03)
An individual shall not receive a
planned
special exposure that, in addition to the doses determined
in 213-02, would result in a dose exceeding the following:
a) In a year, the numerical values of the applicable dose limits established in Table 2-1A and 2-1B [§835.204(c)(1)] or
b) Over the individual's lifetime,
five times the numerical values of the dose limits established in Table
2-1A
and 2-1B [§835.204(c)(2)].
213-04)
Prior to a planned special exposure, written consent shall be obtained from each individual involved
[§835.204(d)]. Each such written consent shall include:
a) The estimated doses and associated potential risks and specific radiological conditions and other hazards which might be involved in performing the task [§835.204(d)(2)],
b) The
purpose of the planned operations and procedures to be used [§835.204(d)(1)], and
c) Instructions
on the measures to be taken to keep the dose ALARA considering other risks that may be present [§835.204(d)(3)].
213-05)
Records of the conduct of a planned special exposure shall be maintained and a written report submitted within 30
days after the planned special exposure to the
approving organizations identified in 213-01 [§835.204(e)].
213-06)
The dose from planned
special exposures is not to be considered in controlling
future occupational dose of the individual under
Tables 2-1A and 2-1B, but is to be included in records and
reports required by 10 CFR 835 [§835.204(f)].
214
Dose
Limits to Minors
No individual under the age of 18 shall be allowed into a Radiologically
Controlled Area (RCA) without the permission of his/her
parent or guardian, the Jefferson Lab Director, and the RCM. The annual dose
limit to any minor occupationally exposed to radiation and/or radioactive
materials from Jefferson Lab activities is 100 mrem
(1mSv) total effective dose, and 10% of the occupational dose limits specified in Table
2-1B [§835.207]. The administrative
control levels for non-radiological workers in Table 2-1A shall be applied to
occupationally exposed minors.
Monitoring requirements for occupationally exposed minors are specified
in Chapter 5 of this manual.
215
Dose Limit for Visitors
and Members of the General Population
215-01)
The total
effective dose limit for members of the public exposed to radiation and/or
radioactive material during access to a controlled area is 100 mrem (1 mSv) in
a year [§835.208]. The administrative control levels for non-radiological
workers in Table 2-1A are applicable to members of the public; however,
specific actions triggered by approaching or exceeding the values listed are to
be tailored appropriately, considering the context of the exposure
scenario. For instance, if a member of
the public were to receive an effective dose of 10 mrem, the individual and
their escort/sponsor would be informed that the dose had reached the design
goal, and every reasonable effort would be made to prevent further exposure. Monitoring requirements for members of the
public entering a controlled area are specified in Chapter 5 of this manual.
215-02)
The total
effective dose limit for members of the public offsite, from all routine DOE
activities, is 100 mrem in a year. The
ALARA process shall be used to reduce doses to the public as far below this
limit as is reasonably achievable.
Jefferson Lab’s Environmental Radiological Protection Program, including
activities related to DOE environmental protection Orders, is described in the
Environmental Radiological Protection Program Plan.
215-03)
In keeping with the limits and
reporting requirements for exposures to members of the public in DOE Order458.1,
Jefferson Lab has established an Action Level for total effective dose where,
under plausible exposure conditions, a person at the site boundary could
receive 10 mrem in a year. Further, the
design goal for such exposures is very conservatively established at 10 mrem in
a year, under conditions of continuous exposure (8760 hours).
216
Embryo/Fetus
Dose
Limits
A Declared pregnant worker is a
woman who has voluntarily declared to her employer, in writing, her pregnancy
for the purpose of being subject to the occupational dose limits to the
embryo/fetus as provided below. This
declaration may be revoked, in writing, at any time by the declared pregnant
worker.
216-01)
The declaration of pregnancy
shall include an estimated date of conception, and may be completed prior to
conception by a woman who is planning a pregnancy. After a female radiological worker declares pregnancy, she should receive counseling concerning
prenatal radiation exposure by the Radiation Control Manager (or designee) and
Occupational Medicine.
216-02)
Declared pregnant workers who are
Jefferson Lab employees will be provided the option of a mutually agreeable
assignment of work tasks, without loss of pay or promotional opportunity, such
that further occupational radiation exposure to the declared pregnant
worker is unlikely. Radiological workers
not employed by Jefferson Lab should also be provided this option.
216-03)
The equivalent dose limit
for the embryo/fetus from the period of conception to birth, as a result of
occupational exposure of a declared pregnant worker, is 0.5 rem (5 mSv) [§835.206(a)]. Substantial variation
above a uniform exposure rate that would satisfy the
0.5 rem limit shall be avoided [§835.206(b)].
216-04)
The dose to the embryo/fetus from
radiation external to the mother is taken as the equivalent dose to the whole
body to the mother’s abdomen or torso.
216-05)
An internal dose
evaluation program, including a routine bioassay
program, shall be conducted for declared pregnant workers likely to receive an
intake resulting in an equivalent dose to the embryo/fetus in excess of 10% of the limit stated above.
216-06)
If the dose to the embryo/fetus is determined to have already exceeded 0.5 rem (5 mSv) when a worker declares her pregnancy, the declared
pregnant worker shall not be assigned to tasks where additional occupational radiation exposure is likely during the
remainder of the gestation
period [§835.206(c)].
Certain
situations require lower individualized exposure
control levels. In addition to
considering recommendations from the RCM and medical officials, the Jefferson
Lab Director should obtain advice from professionals in other disciplines, such
as human resources and legal counsel, in establishing Special Control
Levels. The Jefferson Lab Director may
wish to establish these Special Control Levels with the advice of the RCM, the
Occupational Medicine Physician, and the Jefferson Lab Radiation Review
Panel. Planned Special Exposures carry additional legal notification requirements as indicated in
Article 213.
217-01)
A Special Control Level for
annual occupational exposure shall be established for each person with a lifetime
occupational dose exceeding N rem, where N is the age of the person in years. The Special Control Level will not exceed 1 rem and should allow the person’s lifetime occupational dose to approach N rem as additional
occupational exposure is received.
217-02)
Although background, therapeutic
and diagnostic medical exposures are not included in either personnel radiation dose records or assessment of dose against the
limits of Tables 2-1A and 2-1B, Special Control Levels taking these exposures into account may
be established as agreed upon by management and the individual.
217-03)
Notification to the RCD should be
made if any Radiological Worker has been medically administered
a long-lived radionuclide. The RCD shall make a determination if any Special Control Levels should
be applied.
217-04)
A Special Control Level shall be
established for any individual for whom formal records of
previous exposure during the year have not been
obtained. This Special Control Level is
normally 0.1 rem.
217-05)
A Special Control Level shall be
established for any radiological
worker whose previous recorded
or estimated exposure for the year is greater than 1
rem.
Establishment and approval of this Special Control Level shall be
consistent with the ALARA principle and Article 211.
Jefferson
Lab maintains appropriate methods of control thatprevent the inadvertent transfer
of removable
contamination to locations outside of radiological
areas under normal
operating conditions.
These methods ensure that contamination is controlled in a manner
commensurate with the physical and chemical characteristics of the contaminant,
the radionuclides present, and the fixed and removable contamination levels. Control of
radioactive contamination is achieved by using engineered and administrative controls to
contain contamination at the source, reducing existing areas of
contamination, and to the extent feasible, promptly
decontaminating areas that become contaminated.
221
Personnel Contamination Control
221-01)
Personnel exiting Contamination
Areas, High
Contamination Areas, or Airborne
Radioactivity Areas shall be monitored, as appropriate, for contamination
as required by Article
338. Personnel
monitoring is normally not required when exiting areas posted for airborne
radioactivity when the posting is based solely on the presence of gaseous
activation products, but is appropriate when posting is required due to
airborne particulates.
221-02)
Monitoring for contamination should be performed using monitoring equipment that is sensitive enough to detect total contamination
to the levels specified in Appendix 2B
Contamination Control Limits.
221-03)
Personnel found with contamination on their skin or personal clothing,
other than gases or natural background radioactivity, should be promptly decontaminated as described in Article
541.
222
Contamination Control Levels
222-01)
A surface shall be considered contaminated if either
the removable or total surface radioactivity is detected above the levels in Appendix 2B. If an area cannot be
decontaminated promptly, then it shall be posted as specified in Article 234.
222-02)
In this document, a potentially contaminated
item/area is defined as an item that has been used or stored in a radiological area that is known or suspected to contain unconfined radioactive
material; or as an item or area suspected to be
contaminated, based on experience or process knowledge.
222-03)
Surfaces exceeding the
values of Appendix 2B for total
contamination may be covered with a fixative coating to prevent the spread of
contamination. However, reasonable
efforts should be made to decontaminate an area before a coating is
applied. A fixative coating, other than
that used for a temporary work condition, shall not be applied without the
approval of the RadCon Manager.
222-04)
Volume-activated materials that
are not contaminated on the surface are not subject to contamination controls.
222-05)
In accordance with the exemption
granted June 8, 1998, Jefferson Lab uses a special limit of 30,000 dpm/100 cm2
for Be-7 in lieu of the 10
CFR 835 Appendix D limits for beta-gamma emitters (see Appendix 2B of this
manual). Be-7 is produced in air and
water exposed to high energy beams and can build up on surfaces and in systems
in beam enclosures. The Jefferson Lab
exemption involves the following conditions:
a)
The exemption applies to posting
and controls used in controlled areas only.
Release of materials from controlled areas must comply with other
applicable requirements. In general, this
involves meeting the release criteria in O458.1. For nuclides of concern at Jefferson Lab, the
limits for unrestricted release are the same as those in 10 CFR 835, Appendix
D. Therefore, with the exception of
Be-7, the contamination control values used to identify contamination areas are
the same as those for unrestricted release.
Technical basis documents and written procedures provide specific
requirements and protocols for release surveys that are consistent with the
exemption requirements.
b)
The
exemption requires that areas historically known to contain Be-7 above the
Appendix D values be identified, and posted, marked or labeled to warn workers
not to enter without appropriate authorization.
The processes that result in production and buildup of Be-7 on/in
components and systems are well understood.
Historically, locations that have been affected are electrical rack
spaces and electronic components, air handling equipment, and various cooling
water systems within beam enclosures.
Typically, levels only exceed Appendix D values where there is
significant beam loss, such as in experimental halls A and C. However, the potential for buildup of Be-7
exists to some degree in any beam enclosure, and the equipment for which there
is significant potential for such buildup is marked accordingly. In addition, administrative procedures, such
as the General Access Radiation Work Permit identify this condition and
reinforce the required work authorizations.
Written procedures address survey and posting requirements consistent
with the exemption.
223
Airborne Radioactivity
Control Levels
223-01) Personnel should not be exposed unnecessarily to airborne radioactivity. Use of engineered and administrative controls to reduce the potential for internal exposure should be evaluated before allowing personnel, with or without respiratory protection, to enter areas with airborne radioactivity.
223-02)
The Derived Air
Concentration (DAC) values given in Appendices
A and C of 10 CFR 835 shall be used to control occupational exposures to
airborne radioactive material [§835.209(a)]. Occupied areas with
airborne concentrations of radioactivity that are
greater than, or potentially greater than 1 DAC, or where an individual without
respiratory protection could exceed 12 DAC-hours per
week, shall be posted as specified in Article 234. For most radionuclides,
air containing a DAC results in a committed effective dose of approximately 100 mrem if
inhaled for 40 hours in one work week.
223-03)
The estimation of internal
dose shall be based on bioassay data rather than air concentration values unless bioassay data are:
a)
unavailable,
b)
inadequate, or
c)
internal
dose estimates based on representative air concentration
values are demonstrated to be as or more accurate than bioassay data [§835.209(b)].
231-01)
Radiological
posting shall be used to alert personnel to the presence of radiation and radioactive
materials and to aid them in minimizing exposures and preventing the spread of contamination. Signs required by 10 CFR 835 shall be clearly
and conspicuously posted and may include radiological protection instructions [§835.601(b)]. Signs shall
contain the standard radiation symbol (trefoil) in
magenta or black on a yellow background [§835.601(a)]. Lettering shall be magenta or black. Standardized signs, as described in written
procedures, should be used where practicable.
231-02)
Radiological
postings should be displayed only to signify actual or
potential radiological conditions. Signs
used for training should be clearly marked, such as “For Training Purposes
Only.”
231-03)
Posted areas should be as small
as practicable for efficiency. Postings
should be maintained in a legible condition and updated based upon the results
of the most recent surveys. If more than
one radiological condition (such as contamination and high radiation)
exists in the same area, each condition shall be identified.
231-04)
In areas of ongoing work
activities, the dose rate or range of dose rates should be
available at the work area. Entrance
points to areas of ongoing radiological work should
state basic entry requirements.
231-05)
Rope, tape, chain, and similar
barriers used to designate the boundaries of posted areas should be yellow and
magenta in color. Radiological barriers
should be employed in a manner commensurate with the radiological hazards in
the area. Barriers should be clearly
visible from all directions and at various elevations. Radiological boundaries may be defined by
natural physical boundaries such as the walls of a room or container. Barriers should clearly denote the scope and
extent of the area, and not contain gaps that would allow inadvertent
entry. These barriers shall be set up
such that they do not impede the intended use of emergency
exits or evacuation routes. Where
appropriate for access/egress considerations, boundaries may be established by
use of designations such as prominent painted lines or use of a series of
posted stanchions that are visible from all directions of approach.
231-06)
Posting of doors should be such
that the postings remain visible whether doors are open or closed. A radiological posting that
signifies the presence of an intermittent radiological condition should include
a statement specifying when the radiation is
present, such as “CAUTION: RADIATION AREA WHEN MAGENTA BEACON IS ON.”
231-07)
The posting and labeling
requirements in 10 CFR 835 may be modified to reflect the special
considerations of DOE activities conducted at private residences or
businesses. Modifications (to posting
requirements) made by Jefferson Lab will provide the same level of protection
to individuals as the existing provisions [§835.601(c)].
A Controlled Area is any area to which access is managed to protect individuals
from exposure to radiation and/or radioactive material. Individuals who enter only Controlled
Areas without entering Radiological Areas or Radioactive
Material Areas are not expected to receive a total effective
equivalent dose of more than 100 mrem (1mSv) in a year [§835.602(a)]. Each access
point to a Controlled Area shall be posted,
identifying it as a Controlled Area, whenever
Radiological Areas or Radioactive Material Areas are present [§835.602(a)], and should be posted wherever there is a source of
radiation that produces a Radiologically Controlled Area (defined below). Signs used for Controlled Areas only may be
selected by Jefferson Lab to avoid conflict with local security requirements [§835.602(b)]. For access
controls and training requirements, see Article
331.
233
Posting Radiologically
Controlled Areas (RCAs)
233-01)
Jefferson Lab has defined RCAs such
that any person who works in such an area for one year might receive a whole
body dose in excess of 100 mrem annual exposure from all pathways
(excluding natural background and medical exposures). RCAs are typically posted based on the dose
rate 30 cm from a surface emitting radiation (“whole body” dose rate). When this dose rate exceeds 0.05 mrem/h, the
condition above is assumed to be met. RCAs shall be posted following standard signage formatting used at
Jefferson Lab; the posting may contain additional information concerning entry
requirements and/or the radiological conditions within. Within RCAs,
occupational exposure is controlled by establishing
regulated Radiological Areas: Radiation
Areas, High
Radiation Areas, etc.
This graded approach increases access requirements on the basis of the
increasing potential for radiation exposure.
233-02)
RCAs shall be designated on the basis of estimated or measured radiation dose rate or on account of levels of
surface or airborne contamination above specified limits. As a general practice, RCAs should be posted
whenever a radiological area exists to act as a “buffer zone” around radiological
areas, as described above. RCA postings
may be contiguous with radiological area boundaries, but only when it is
impractical to create an RCA boundary at some point beyond the extent of the
radiological area. Subject to the level
of supervision and approval by the RCM, relaxation of radiologically
controlled area definition in terms of dose rates may be permitted on grounds of infrequent or brief
occupancy or transient radiation conditions.
233-03)
Persons who are not Radiation Workers needing access
to RCAs must be escorted by staff having Radiation Worker I training.
234
Posting Radiological
Areas
Each access point to radiological areas shall be posted with conspicuous signs bearing the wording
provided in this section. The
requirement for an RWP should be included either on or in conjunction with each
posting, as applicable.
234-01)
Radiation Area
The words “CAUTION, RADIATION AREA” shall be posted at each radiation
area [§835.603(a)] defined as
follows: Any area, accessible to individuals,
in which radiation levels could result in an individual receiving an equivalent
dose to the whole body in excess of 0.005 rem (0.05 mSv) in 1 hour at 30
centimeters from the source or from any surface that the radiation penetrates.
234-02)
High Radiation Area
The words
“CAUTION, HIGH RADIATION AREA” or “DANGER, HIGH RADIATION AREA” shall be posted
at each high
radiation area [§835.603(b)]
defined as: Any area accessible to
individuals, in which radiation levels could result in an individual receiving
an equivalent dose to the whole body in excess of 0.1 rem (0.001 Sv) in 1 hour
at 30 centimeters from the radiation source or from any surface that the
radiation penetrates.
234-03)
Very High Radiation Area
The words “GRAVE DANGER, VERY
HIGH RADIATION AREA” shall be posted at each very high radiation area [§835.603(c)] defined as: Any area, accessible to individuals, in which radiation levels
could result in an individual receiving an absorbed dose in excess of 500 rads
(5 grays) in one hour at 1 meter from a radiation source or from any surface
that the radiation penetrates.
234-04)
Posting
Contamination,
High Contamination and Airborne Radioactivity
Areas
a)
The words “CAUTION, CONTAMINATION
AREA”, “CAUTION, HIGH CONTAMINATION AREA” or “DANGER, HIGH CONTAMINATION AREA”,
respectively, shall be posted at any area accessible to individuals where
removable surface contamination values exceed or are likely to exceed the
applicable removable surface contamination values in Appendix 2B [§835.603(e),(f)]. Areas accessible to individuals shall be
posted to alert personnel to contamination in
accordance with Article 231.
b)
The words “CAUTION, AIRBORNE
RADIOACTIVITY AREA” or “DANGER, AIRBORNE RADIOACTIVITY AREA” shall be posted at
any accessible area in which the concentration of airborne radioactivity above natural background, exceeds or is likely to exceed the DAC
value listed in 10 CFR 835, Appendices A or C; or an individual present in the area without respiratory
protection could receive an intake exceeding 12 DAC-hours
in a week [§835.603(d)].
235
Posting
Radioactive Material Areas
235-01)
Accessible areas in which items
or containers of radioactive
materials exist and the total activity of radioactive
material exceeds the applicable values in 10
CFR 835, Appendix E shall be posted “CAUTION, RADIOACTIVE MATERIAL(S)” [§835.603(g)]. The posting
shall meet the requirements in Article 231.
235-02)
Radioactive
Material Areas shall be located within Controlled
Areas.
235-03)
The definition of radioactive material and the requirements for labeling radioactive material are contained in Chapter 4.
Contact readings should be used to
determine the presence of hot spots. Hot spots are
defined as spots where the dose rate on contact is
greater than 100 mrem/hr and at least five times the
dose rate at 30 cm.
Posting of hot spots is not required in areas
requiring a job-specific Radiological Work
Permit (RWP) or radiological briefing for entry.
237
Exceptions to
Posting Radiological Areas and Radioactive
Material Areas
237-01)
Radiological
Areas and Radioactive Material Areas may be excepted from
the posting requirements of Articles 234 and 235 for periods of less than 8 continuous hours when placed under
continuous observation and control of an individual knowledgeable of, and
empowered to implement, required access and exposure
control measures [§835.604(a)].
237-02)
Areas may be excepted from the radioactive material area posting requirements of Article 235 when:
a)
Posted in
accordance with Article 234-01 through -04; or
b) Each item or container of radioactive material is labeled in accordance with Article 412, such that individuals entering the area are made aware of the hazard; or
c)
The radioactive material of concern consists solely of structures or installed components
that have been activated (i.e., such as by being exposed to neutron radiation or particles produced in an accelerator) [§835.604(b)].
237-03)
Areas containing only packages
that have been received from radioactive
material transportation labeled and in non-degraded
condition need not be posted in accordance with Article 234 or 235 until the packages are monitored in accordance with Article
432-04 [§835.604(c)].
Table 2-3 Criteria
for Posting Radiological
Areas
|
Area |
Posting
Criteria |
Postinga |
|
Radiation Area |
> 5 mrem in one hour (at 30 cm) |
“CAUTION,
RADIATION AREA” |
|
High Radiation Area |
> 100 mrem in one hour (at 30 cm) |
“DANGER,
HIGH RADIATION AREA” or “CAUTION, HIGH RADIATION AREA” |
|
Very High Radiation Area |
> 500 rad in one hour (at 1 m) |
“GRAVE DANGER, VERY
HIGH RADIATION AREA” |
|
Contamination
Area |
Levels (dpm/100 cm2) > 1 time but < 100
times Appendix
2B values |
“CAUTION, CONTAMINATION AREA” |
|
High
Contamination Area |
Levels (dpm/100 cm2) > 100 times Appendix 2B values |
“DANGER, HIGH CONTAMINATION AREA” |
|
Airborne
Radioactivity Area |
Concentrations (µCi/ml) > DAC value
listed in 10 CFR 835 Appendices A or C, or
an area in which a person without respiratory protection could receive an
intake exceeding 12 DAC-hrs in a week |
“CAUTION, AIRBORNE RADIOACTIVITY
AREA” or “DANGER, AIRBORNE RADIOACTIVITY AREA” |
|
a Appropriate access requirements should be
included on the posting. |
||
Exclusion Areas are locations that are locked and
interlocked to prevent personnel access while an accelerator is operating. A fully enclosed and interlocked area is not
considered to be accessible [DOE
G 420.2-1]. Beam
enclosure areas that are configured with a certified Personnel Safety
System (PSS) are Exclusion Areas when the beam or high power RF is operable
[§835.502(c)]. Signs and/or clearly labeled lights
reflecting current interlock or beam status shall be provided at all
accelerator enclosure entry doors. Beam
enclosures, test facilities, shielded caves, etc., that are not fully enclosed,
or not protected by a certified PSS are not Exclusion Areas, and shall be
posted in accordance with the requirements for posting Radiological Areas.
|
|
ISSUING
AUTHORITY |
CHAPTER
AUTHOR |
APPROVAL
DATE |
REVIEW
REQUIRED DATE |
REV. |
|
|
|
RadCon Dept |
07/01/10 |
07/01/13 |
4.1 |
|