Radiation Controls in the Workplace



				Radiation Controls in the Workplace

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RADIOLOGICAL CONTROL GROUP RESPONSIBILITIES

ASSIGNED RADIATION MONITORS

TYPES OF RADIOLOGICAL CONTROLS

VIEW EXAMPLE OF RWP

VIEW RWP DOSE TRACKING LOG

VIEW SURVEY MAP

YOUR RESPONSIBILITY REGARDING RADIOLOGICAL CONTROLS

ANSWERS TO UNIT 10 REVIEW QUESTIONS

10.1 RADIOLOGICAL CONTROL GROUP RESPONSIBILITIES

This organization implements the requirements for the Radiological Control program. These requirements are established in DOE Orders and regulations, TJNAF's Radiological Control Manual, and Site Radiological Control procedures.

Responsibilities of Radiological Control personnel:

Radiological Control Technicians provide a point of contact for the worker to obtain the most current radiological conditions in an area. They provide assistance when interpreting protective requirements or radiological information concerning a work assignment and they address radiological questions/concerns.

10.2 ASSIGNED RADIATION MONITORS

TJNAF accelerator operators and other designated individuals have received additional training in radiation safety and monitoring techniques. These persons are designated as "Assigned Radiation Monitors" or ARMs. Tasks ARMs perform that are of interest to radiological workers include:

Performing general surveys of the beam enclosure after beam operations

Surveying and assisting with disposition of equipment removed from the beam enclosure

Initial response to alarming radiation monitoring equipment or abnormal events

10.3 TYPES OF RADIOLOGICAL CONTROLS

Radiological controls can be grouped into two broad categories - engineered controls and administrative controls. Sometimes the two methodologies overlap in their implementation. Consider how the basic ALARA principles of time, distance, and shielding are implemented through each of these types of controls.

10.3.1 Engineered Controls

Engineered controls consist of equipment designed to protect personnel from a hazard by preventing access to enclosures, providing a warning of the hazard or a means to remove the hazard. These controls may be active or passive.

Examples of engineered controls used at TJNAF include:

Passive Engineered Controls __________________________	Active Engineered Controls __________________________
Installed shielding Walls, gates, or locked doors Labyrinths	Key controls Interlocked monitoring instruments Warning indicators or status displays Ventilation systems

Shielding

TJNAF's design incorporates heavy use of shielding. The earth overburden on the beam enclosure is an obvious example. Structures such as earth berms, and concrete walls are considered permanent shielding.

Temporary shielding (e.g. lead or concrete blocks) can only be installed when procedures are used. Once temporary shielding is installed, it cannot be removed or altered without proper authorization.

Temporary shielding will be marked or labeled with wording such as, "Temporary Shielding - Do Not Remove Without Permission from Radiological Control". This is an example of the combination of an engineered control (the shielding) and an administrative control (the labeling and tracking of these structures).

10.3.2 Administrative Controls

10.3.2.1 Configuration Controls

The above example of labeled shielding is known as a configuration control. Elements of the configuration control program include:

Labeling and inventory of controlled devices

Periodic inspections

Procedures for change and/or restoration of configuration

Testing to verify proper configuration

Other examples of structures and equipment to be maintained in a specific configuration:

Critical Safety Devices (certain beam monitors, beam stops, or magnets)

Safety interlocks and "crash" switches

Area Radiation Monitors and their detectors

Wiring, interconnects, computers and controllers for the above

10.3.2.2 Radiological Postings

Postings (signs, tags, labels) are used to alert personnel of an existing or potential radiological hazard and to aid them in minimizing exposures and preventing the spread of contamination. Radiological postings are the primary means of communicating radiological hazards to workers. All personnel are required to comply with these postings. Disregard for postings or other radiological instructions is grounds for disciplinary action.

CONTROLLED AREA

An area to which access is controlled in order to protect individuals from exposure to radiation and radioactive materials is known as a Controlled Area. It is a boundary area around other radiological areas. The TJNAF accelerator site (fenced in area bounded by locked or guarded access gates) has been designated as a Controlled Area. This means that within this area, you are likely to see postings for Radiological Areas, or radioactive material or possibly encounter slightly elevated levels of radiation. By design, a person who spends their entire work year only in the controlled area is not expected to receive enough radiation dose to require dosimetry (50 mrem).

Requirements to enter the Controlled Area are:

training in radiological controls (GERT, RWT, or ARM training) -or-

an escort who is trained at least to the GERT level

The security guard at the accelerator site access will check your identification badge to ensure you have had the appropriate training.

You may also find Controlled Areas in:

Locations within the Test Lab (Bldg 58)

Locations within the EEL Building (Bldg 90)

Designated Radioactive Material Storage Areas around the site

RADIOLOGICAL AREAS (or Radiologically Controlled Area)

Areas within the Controlled Area boundary are clearly posted to alert personnel to the presence of elevated radiation levels and/or radioactive materials. These areas are designated Radiological Areas. In these areas, radiation levels are high enough that personnel may receive more than 100 mrem in a year. Radiological Areas contain radiation levels that require personnel radiation monitoring (dosimetry) for entry. These areas are designated with postings containing the standard radiological warning symbols and colors together with yellow and magenta ropes, chains or other boundary indications.

Requirements for unescorted entry:

TLD badge
Radiation Worker Training
Signature on General Access Permit (In beam enclosure)

All Radiological Areas are identified by the following:

Signs that have the standard radiation symbol colored magenta (purple) or black on a yellow background.
In the absence of doors or other physical entry points, yellow and magenta rope, tape, chains or markings are used to designate the boundaries of posted areas.
All Radiological Area postings will contain the words "Radiologically Controlled Area", or "RCA".
Personnel dosimetry requirements will also be included on the posting.

Requirements for working in a Radiologically Controlled Area include:

Practice ALARA - minimize your time in the area
Do not eat, drink, or smoke in the RCA
Minimize waste production, and segregate waste according to posted instructions
Maintain visual and verbal communications with any escorted visitor
Obey all posted radiological instructions

Typical Locations of Radiological Areas at TJNAF:

Linac/Arc Service Buildings
Beam Enclosure (including experimental hall)
Operating end station roof
Areas within the EEL and Test Lab

When leaving a Radiological Area:

Make sure you have not left unnecessary waste items in the area

Check to make sure you have your dosimetry (read your SRPD, if one is worn)

Check for personnel contamination monitoring requirements - some areas may require a contamination check prior to leaving. If monitoring is required, follow the procedures discussed later in the handout.

Within a Radiologically Controlled Area, various other Radiological Area postings may exist. These areas are usually defined by specific levels of radiation or contamination which may exist within. The definitions and requirements for working in these areas follow.

RADIATION AREA - Areas where the whole body radiation dose rates (30 cm. from the source of radiation) are >5 mrem/hr but <100 mrem/hr. The postings/signs will include the words "CAUTION RADIATION AREA".

All of the precautions for working in RCA apply. Check the posting to determine if an RWP is necessary. Notify the RCG when performing activities which might change radiological conditions, such as moving radioactive materials within the radiation area, removing items from the area, or disassembling or modifying any activated component.

Know the radiation levels and where to position yourself to minimize your dose.

Only Radiation Workers are permitted in Radiation Areas - no visitors.

Requirements for working include: Don't loiter, practice keeping your exposure ALARA, read your dosimeter periodically; if unanticipated elevated radiation levels are indicated as identified by off-scale dosimeter, radiological alarms or other indicators, stop working, alert others working in the area, immediately exit the area and notify Radiological Control personnel.

Requirements for exiting: Read your SRPD or digital dosimeter. Complete the RWP timesheet entry if applicable.

Typical Locations of Radiation Areas at TJNAF:

Near activated beamline components in the tunnel/end station
Above unshielded service building penetrations
Labyrinths/shielded passages near the beam enclosure during beam operation

HIGH RADIATION AREA - Areas where whole body radiation dose rates are >100 mR/hr but less than 5000 mR/hr. The postings/signs will indicate: "CAUTION - HIGH RADIATION AREA" "TLD, Supplemental Dosimetry and RWP Required For Entry"

High Radiation Areas should remain locked and/or have physical barriers established. If the dose rate in the area exceeds 1 rem/hr, an approved physical access control must be in place. Physical access controls are used for High Ra diation Areas whenever possible. These physical controls include:

Locked doors with strictly controlled keys

Warning devices that inform personnel and supervisors that an entry is being made.

A device that causes the source of radiation to cease upon personnel entry or that prevents entry when the source is present.

Requirements for Entry are:

Level I or II Radiological worker Training.
An RWP is mandatory for High Radiation Areas.
SRPD's or digital dosimeters are required. Additional dosimetry may be required - always check the RWP carefully.
A pre-job briefing is required to enter High Radiation Areas.

Typical Locations of High Radiation Areas at TJNAF:

Near irradiated high power beam dumps
Near highly activated portions of beamline
End station beam dump cooling water buildings
Interlocked beam enclosure when beam is on
Near operating RF accelerator cavities

Hot Spot - A spot (usually small) where the dose rate on contact is greater than 100 mrem/hr and at least five times the whole body dose rate.

Typically, Hot Spots will be located on activated portions of beamline and beamline components. Never handle a Hot Spot without concurrence from RCG.

Summary of Radiation Worker I accessible areas

Location Dose Rate Criteria Posting

Controlled Area < 100 mrem/yr 'Controlled Area, Training or Escort Required for Entry'

Radiological Area
(or Radiologically Controlled Area)
> 0.05 mrem/hr
(>100 mrem/yr)
'Radiologically Controlled Area, (or 'RCA') Dosimetry Required for Entry'

Radiation Area 5 mrem/h - 100 mrem/h 'Caution Radiation Area, TLD Required'

High Radiation Area 0.1 rem/h - 5 rem/h 'Danger High Radiation Area, RWP Required'

Hot Spot > 0.1 rem/h on contact 'Caution Hot Spot'

RADIOACTIVE MATERIALS AREA - Areas where radioactive materials are stored or handled. The posting/signs will indicate: "CAUTION - RADIOACTIVE MATERIALS"

The Radioactive Material Area posting is usually accompanied by RCA designation. When working in areas such as the beam enclosure, items which you remove from a radioactive system or component must be surveyed and tagged.

Note: Installed beam line components and hardware are not normally tagged as radioactive material - Always get concurrence from the RCG prior to disassembling such equipment.

The presence of Radioactive Materials does not always signify a Radiological Area. Radiological Areas are posted based on the potential for radiation exposure above certain levels. However, in order to maintain control and accountability of radioactive materials, Controlled Areas are usually established for storing them. Removal of radioactive items from these areas requires Radiological Control approval. Sometimes radioactive materials are stored in non-controlled areas temporarily. This may be the case when exterior dose rates on an item are so low that it presents no significant radiological hazard and no need for personnel dosimetry for working in the area.

When these conditions are met, the container or radioactive item itself are considered the Controlled Area boundary, and the item must:

Be conspicuously labeled as Radioactive Material, and

Be posted with a Controlled Radioactive Material Tag, which identifies the custodian of the material, approved storage location, and its radiological properties.

Typical Locations of Radioactive Materials Areas at TJNAF:

Beam Enclosure
Areas within EEL and Test Lab
Designated Radioactive Material Storage Areas within the Site Controlled Area

The following radiological areas are areas that a Level I trained employee cannot enter.

Very High Radiation Area - The postings/signs will indicate: "GRAVE DANGER - VERY HIGH RADIATION AREA" "Special Controls Required for Entry"

Contamination Area - The posting/signs will indicate: "Contamination Area" "RWP Required for Entry"

Radiography Area - The posting will indicate "Radiation Area, Keep Out". Only the radiographic team and associated Radiological Control personnel are allowed entry to these areas.

Airborne Radioactivity Area - The posting will read "Caution, Airborne Radioactivity Area, RWP Required for Entry"

Review:

1) An area posted as a "Radiation Area" has dose rates between and mrem/hr.

2) Why is the beam enclosure posted as a Radioactive Materials Area?

3) If removing material from the beam enclosure, it must be monitored for radiation if:

it is part of the beamline
it was near a beam dump
it is made of steel
it was in the enclosure during beam operation

4) A "Radiation Area" will require a RWP.

5) When moving a component that is known to be radioactive from one location to another - even within the RCA - you should notify the RCG because:

6) List 3 requirements for entry to a High Radiation Area. , , .

7) Area designations such as Radiation Area and High Radiation Area are based on radiation dose rates measured from the source of radiation. This measurement is known as a dose rate.

8) Level I Radiological Workers may not enter areas posted as , , . (name three)

10.3.2.3 Administrative Procedures

RADIOLOGICAL WORK PERMITS (RWP)

RWPs are used to establish radiological controls for entry into areas controlled for radiological purposes. As a Level I trained radiological worker, you may be required to use an RWP. RWPs serve to:

Inform workers of area radiological conditions.
Inform workers of entry requirements and/or restrictions on work in the area.
Provide a means for dose tracking.

There are two basic types of Radiological Work Permits depending on the radiological conditions:

General Radiological Work Permit - used to control routine or repetitive activities such as tours and inspections in areas with historically stable radiological conditions. No destructive modification to radioactive materials or breaches of contaminated systems may be performed when using this type of permit. It is valid for up to one calendar year. A special example of such a permit is the General Access RWP required for any work in the beam enclosure. This RWP requires review and signature on the briefing sheet once per calendar year. You should check the continuation sheets (posted at access points) for updates to the RWP frequently.
Job Specific Radiological Work Permit - used to control non-routine operations or work in areas with changing radiological conditions. It is only valid for the duration of a particular job.

Note: RWPs may be required in addition to OSPs, RCOPs, etc. Always check for RWP requirements prior to beginning work in radiological areas.

Typical information found on Radiological Work Permits includes:

Description/location of work
Radiological conditions (This information may be determined from area radiological survey maps/diagrams or the radiological posting for that area).
Radiological monitoring requirements
Dosimetry requirements
Limiting radiological condition which may void the permit.
Special dose or contamination reduction considerations
Date of issue/expiration
Radiological control coverage requirements
"Stay-time" controls - assigned by the RCG to limit time in a particular area
Interface documents (OSPs etc.) and other unique identifying numbers
Authorizing signatures

When using a Radiological Work Permit YOUR SIGNATURE INDICATES THAT YOU HAVE READ THE RWP AND UNDERSTAND THE REQUIREMENTS IN IT. If you don't think that the RWP is correct or you don't understand any of the information, don't sign the permit and contact Radiological Control personnel or your supervisor. Workers must obey any instructions written on the permit. Never make substitutions for specified requirements.

Use blue or black ink to complete the RWP timesheet.

Make entries legible and complete.

Sign the timesheet - Do not print your name.

Correct any errors with one line through, initials and date.

RADIOLOGICAL SURVEY MAPS

Survey maps are an important tool to provide you with the locations of significant radiation levels and help you minimize your dose while working in the area. All RWPs will have associated survey maps included.

Information on the maps may include contact, whole body (readings at 30cm), and general area dose rates and contamination levels if applicable. Dose rates are usually given in mrem/hr.

Review the attached example survey map to become familiar with common notations used.

You should know:

The locations of low-dose areas
Where the highest radiation levels and Hot Spots are
The expected dose rates in your work area

RADIOLOGICAL CONTROL OPERATING PROCEDURES (RCOP)

Defines scope and limitations to a task or procedure

Typical Uses

Handling certain radioactive sources
Operation of radiation producing machines
Experimental setups or first-time activities to establish hold-points

10.3.2.4 Contamination Monitoring Procedures

Upon exiting some RCAs you may be required to monitor yourself - or "frisk" - for the presence of contamination. Appropriate instruments for this purpose will be staged at areas where there is a requirement for monitoring.

The purpose of using any type of contamination monitoring equipment is to detect and limit the spread of contamination.

USING A FRISKER

Friskers are beta-gamma detection instruments capable of measuring small amounts of radioactivity on surfaces. To be effective in this, the frisker probe must be held with the 'window' facing the surface to be monitored within 1/2" of the surface and moved very slowly covering the entire area. It should take about 2 -3 minutes for a proper "whole body" frisk.

"frisker"

To perform a whole body frisk:

Note: Do not touch or handle the frisker prior to checking your hands unless absolutely necessary.

Verify that the instrument is on, set to the lowest scale, and that background is being detected. Make sure you can hear the audible response.

Background must be below 300 cpm (counts per minute) - if possible survey in an area where the background is less than 100 cpm.

If equipped with a response switch, it should be in the "slow" position.

Monitor your hands carefully before picking the probe up.

Hold the probe within 1/2" of the surface and slowly scan all surfaces of your body, moving the probe no faster than one to two inches per second.

While surveying, you should watch the area being surveyed and listen carefully to the audible response for increase in the click rate. There is no need to watch the meter - the audible response is faster, and you should pay attention to where you are surveying.

Survey the body in a methodical manner - a typical order is:

head - check carefully around face, nose, mouth

neck, shoulders, arms

chest, abdomen

back, hips, seat of pants

legs - check knees carefully

feet - check soles of shoes carefully

Check your dosimetry and any personal items such as notebooks, pencils, pens.

Return the probe to the holder in a way that allows the next user to check hands without touching the probe.
Contamination is indicated by an increase in the count rate. When you hear an increase, pause for a moment over the area being surveyed. Continue to frisk if the count rate drops back down. If the count rate exceeds 100 cpm above background, contamination is indicated. Do not rely solely on the instrument's alarm function to alert you to potential contamination. 100 cpm relates to about 1000 dpm (disintegrations per minute) of contamination.

If contamination is indicated, remain in the area and notify the RCG immediately. Minimize potential cross-contamination of other items or people. While awaiting RCG personnel, continue to frisk to see if the contamination can be localized to a specific area.

10.4 YOUR RESPONSIBILITY REGARDING RADIOLOGICAL CONTROLS

It is each worker's responsibility to read and comply with all the information identified on radiological postings, signs and labels. Disregarding any of these postings or warnings can lead to unnecessary or excessive radiation exposure and/or personnel contamination. Never take it upon yourself to relocate or remove a radiological placard, label, sign, rope or other boundary.
If any type of material used to identify radiological hazards is found outside an area controlled for radiological purposes, it should be reported to Radiological Control personnel immediately.
It is important for everyone to try and minimize the amount of radioactive waste that is produced when working. Key methods for minimizing the amount of radioactive waste include:

Minimize the materials used for radiological work

Take only the tools and materials you need for the job into the Radiologically Controlled Area

Unpack equipment and tools in a 'clean' area to avoid bringing excess material into an RCA

Segregate radioactive waste from non radioactive waste - Special blue drums located inside the Beam Enclosure are to be used for disposal of items known or suspected of being radioactive. Only items that were brought into the accelerator enclosure as 'clean' and are known not to be radioactive should be put in the 'clean' trash containers. Do not put clean waste, packing material and other refuse in the blue drums.

Minimize the amount of mixed waste generated (mixed waste refers to materials that are classified as hazardous chemicals and are radioactive)

Use good housekeeping techniques

Review: 9) Radiological Work Permits are used to inform you of in an area, and to make you aware of for entry. They also serve as a mechanism, for dose .

10) The two general types of RWPs are and .

11) In the case of a job specific RWP, what two groups are involved in the initiation of the permit? and

12) Among the types of information found on an RWP are (name four): , , and

13) RWPs are always required in:

a Radiation Area

a Controlled Area

a High Radiation Area

all the above

14) Your signature on the RWP timesheet indicates that you have the RWP, and that you and will follow the in it.

15) Why is it particularly important that people follow RWP requirements closely?

So TJNAF won't be sued

Because there are potentially lethal conditions in RWP areas

Because failure to do so could cause major damage to accelerator components

Because RWPs are used where there are significant radiological hazards, and maintaining control over activities in the area is the only way to ensure that the hazard to personnel is minimized

16) You can help minimize generation of radioactive waste by which of the following?

take only the tools and materials you need into the beam enclosure

practice good housekeeping

unpack materials outside the beam enclosure and dispose of the packing material

don't place "clean" material in a radioactive waste container

all of the above

17) 100 cpm on a frisker relates to how much radioactive material?

about 100 mrem

about 100 dpm

about 1000 dpm

about 100 curies

18) Where can you get information that you need to be knowledgeable about the radiation levels in your work area?

Radiological survey maps

an RCG Technologist

Radiation Work Permits

All the above.

VIEW EXAMPLE OF RWP

VIEW RWP DOSE TRACKING LOG

VIEW SURVEY MAP

ANSWERS TO UNIT 10 REVIEW QUESTIONS

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10.1 RADIOLOGICAL CONTROL GROUP RESPONSIBILITIES

10.2 ASSIGNED RADIATION MONITORS

10.3 TYPES OF RADIOLOGICAL CONTROLS

10.4 YOUR RESPONSIBILITY REGARDING RADIOLOGICAL CONTROLS