Radiation Worker Training

Rad Training Filtrol

Radiation Worker Training

Site Remediation

Birmingham Steel

May 2000


Course Outline

Talk About 1 - Radiation Fundamentals and Biological Effects

Talk About 2 - Personnel Exposure Limits

Talk About 3 - Personnel Survey


Course Outline

Talk About 5 - Contamination and Decontamination

Talk About 6 - Posting and Labeling


Caution

Contamination Area

Anti-C Anti-C

Radiation Fundamentals


Sources of RadiationThere are two main sources of ionizing radiation:

Natural Background

Man Made Sources


Natural Background RadiationSources : Average

Dose

Cosmic - from the sun and outer space 28 mrem/yr

Terrestrial - from the earth's crust 28 mrem/yr

Radon - from the soil, (decay of uranium) 200 mrem/yr

Internal - from sources in the body 39 mrem/yr


Man-made Radiation SourcesSources : Average

Dose

Medical radiation 54 mrem/yr

Consumer products 10 mrem/yr

Industrial uses < 3 mrem/yr

Atmospheric testing of nuclear weapons < 1 mrem/yr


Average Annual ExposureThe total from all sources, natural and man made is

approximately 360 mrem/yr.


p+

proton neutron

electron

nucleus

e

n0

The Atom


Charge of the AtomThe number of electrons and protons determines the

overall electrical charge of the atom.

p

p

n

n

e

p

p

n

n

e

e

p

p

n

ne e

e

Ion+1 Charge

NeutralIon

-1 Charge

Ion = Atom with a positive or negative charge

+

+

+

+

+

+

- -

-

-

- -


IonizationIonization is the process of removing electrons from a

neutral atom.ejected electron (negative ion)

incomingionizing

radiation

remaining atom (positive ion)

The positively charged atom and the negatively charged electron are called an ion pair.

-

-

-

-

-

-

+6


Ionizing RadiationIonizing radiation is radiation which carries enough

energy to cause ionization in the atoms with which it interacts.

n

(Alpha Particle)

(Beta Particle)

(Gamma Ray)

(Neutron Particle)


Non-Ionizing Radiation

Radiation that doesn't have the amount of energy needed to

ionize an atom with which it interacts, is called "non-ionizing radiation".

Examples of non-ionizing radiation are radar waves, microwaves and visible light.


RadioactivityRadioactivity is unstable (or radioactive) atoms trying to

become stable by emitting radiation.


Radioactive MaterialRadioactive material is any material containing unstable

radioactive atoms that emit radiation.


Radioactive ContaminationRadioactive contamination is radioactive material in an

unwanted place.

Radiation is a type of energy and contamination is a material.

It is important to note that exposure to radiation does not result in contamination of the worker.


Radioactive DecayRadioactive decay is the process of radioactive atoms

releasing radiation over a period of time becoming stable (non-radioactive). (Also known as dis-integration.)

Large Unstable Nucleus

p

p

n

n

e-

n

p

p

n

n

p

p

n

n

p

p

n

n

n

np

p p

p

n

p

p

n

pp

p

n

n

p

p

n

n

p

np

nn

n

pn

+

+


Half LifeRadioactive half-life is the time it takes for one half of the radioactive

atoms present in a radioactive sample to decay.

After seven half-lives the activity of a radioactive sample will be less than 1% of the original activity.

Radioactive half - life of U-239 is 23.5 minutes.

Radioactive half - life of U-238 is 4,510,000,000 years.

0102030405060708090

100

1 2 3 4 5 6 7 8

% of atoms

that are

radioactive

# of half lives


Four Types of Ionizing Radiation

p

p

n

n

Alpha Particles

Beta Particles

Gamma Rays

Neutron Particlese-

n

The four basic types of ionizing radiation of concern in the nuclear industry are:

+2+

+


Alpha Particlesp

p

n

n

+2

Characteristics:

Very massive, composed of two protons, two neutrons and no electrons. (Positive charge of plus two)

Penetrating Power - Very low. Average range in air is about one to two inches.

Shielding - Alpha particles are stopped by a sheet of paper, or the dead layer (outer layer) of skin.

Biological hazard - Alpha particles are considered an internal radiation hazard.


Beta Particlese-

Characteristics:

Very small, negatively charged particle.

Penetrating Power - Low. Range in air of several feet and a range of a few millimeters in tissue.

Shielding - Most beta particles are stopped by plastic, glass, metal foil, or safety glasses.

Biological hazard - Internal, skin and eye.

-


Gamma Rays

Characteristics :

Gamma () radiation has no charge and no mass. Consists of electromagnetic waves or photons.

Penetrating Power - High . Very long range.

Shielding - Shielded by very dense materials, such as lead, concrete or steel.

Biological hazard - External or whole body.


rem (Roentgen Equivalent Man)

Unit for measuring dose equivalence.

Most commonly used unit.

Pertains to man - refers to the amount of biological damage produced by radiation.

Takes into account the energy absorbed (dose) and the biological effect on the body due to the different types of radiation.


Conversion of rem and millirem

1 rem = 1000 millirem (mrem)

0.1 rem = millirem?

5000 millirem = _______ rem?

rem x 1000 = mremmillirem 1000 = rem .

.


Dose Rate

Dose is the amount of radiation you receive.

Dose Rate is the rate at which you receive the dose

Dose rate = dose/time

mrem/hr, rad/hr, R/hr


Contamination/Radioactivity

Disintegrations per minute (dpm) - describes the number of atoms disintegrating each minute in a radioactive source.

Radioactivity is measured in the number of disintegrations radioactive material undergoes in a certain period of time.

– One Curie = 2,200,000 000,000 (2.2 x 1012) dpm

– One microCurie = 2.22 x 106 dpm

– One picoCurie = 2.22 dpm


Effects of Radiation on CellsRadiation causes damage to cells is by ionizing the

atoms in the cells.

Ionizing radiation may cause damage directly to the nucleus or any other part of the cell.

The interaction may cause physical damage, chemical damage, or both to occur to the cell.


Cell SensitivityRadiation damage to cells depends on how sensitive the

cells are to radiation.

Cells that are actively dividing are more sensitive to environmental factors such as ionizing radiation.

– Examples: blood forming cells, intestinal lining, hair follicles, embryo/fetus.

Cells which divide at a less rapid pace or are more specialized are not as sensitive to damage by ionizing

radiation.

– Examples: brain cells or muscle cells


Possible Effects of Radiation on Cells

Cells are not damaged

Cells repair the damage and operate normally

Cells are damaged and operate abnormally

Cells die as a result of the damage


Acute and Chronic Radiation DosePotential biological effects of radiation depend on several

factors.

How much and how fast a radiation dose is received are

two of them.

Radiation doses can be grouped into two categories:

Acute dose

Chronic dose.


Acute DosesAcute doses are large doses of radiation received in a short

period of time.

The body can't repair or replace cells fast enough from an acute dose and physical effects such as reduced blood count and hair loss may occur.

Death can occur if the exposure is high enough.


Chronic Radiation Dose

Chronic radiation dose is typically a small amount of radiation received over a long period of time.

Typical examples of a chronic dose are:

The dose we receive from natural background.

The dose we receive from occupational exposure.


Chronic vs. Acute DosesThe body is better equipped to tolerate a chronic dose than

an acute dose.

With chronic doses the body has time to repair damage.

With chronic doses the body also has time to replace dead cells.

Even sophisticated analysis of the blood does not reveal any biological effects from chronic doses.

Acute doses may overwhelm the cells repair mechanisms.


Somatic Effects

Somatic effects are effects that occur in the exposed individual.

An example of a somatic effect is cancer.


Factors Affecting Biological DamageTotal dose

Dose rate (how fast)

Type of radiation

Area of the body exposed

Cell sensitivity

Individual sensitivity


Prenatal Radiation Exposure

Embryo/fetal cells are rapidly dividing which makes them sensitive to any environmental factors such as ionizing radiation.


Potential Prenatal Hazards Some children who were exposed while in the

womb to the radiation from the atomic bomb were born with low birth weights and mental retardation.

It has been suggested, but not proven, that exposures to the unborn may also increase the chance of childhood cancer.

Only when doses exceed 15,000 mrem has there been significant increase in risk.


Hazards from Uranium, Thorium

and Decay Products• Radiation Exposure

– Lung

– Long-term retention in lung

– Bone

– Uptake through lung or ingestion

– Deposit on surfaces of bone

– Whole body gamma exposure

• Chemical Toxicity– Heavy metal, similar to lead

– Kidney


THORIUM-232

1.4E+10 y5.75 y 6.13 hr

RADIUM-228 ACTINIUM-228 * THORIUM-228

1.91 y

RADIUM-224 *

3.62 d

RADON-220

55.6 s

POLONIUM-216

0.15 s10.6 hr 60.5 m

LEAD-212 * BISMUTH-212 POLONIUM-212

60.5 m3.1 m

3E-7 s

THALLIUM-208 *

Thorium decay chain.

LEAD-208 (STABLE)

SHORT HALF-LIFE THORON DECAY

PRODUCTS

NOTE: Vertical Direction Represents Alpha Decay, Horizontal Direction Indicates Beta Decay. Times Shown are Half-Lives. Only the Primary Decay Mode is Shown. * Also Gamma Emitters, the Gamma Emissions from the Other Isotopes are Insignificant


Estimated Days Lost Due to Daily ActivitiesAvg. Days

HEALTH RISK Lost

Unmarried male 3500Cigarette smoking 2250Unmarried female 1600Coal miner 110025% overweight 777Alcohol (U.S. average) 365Construction worker 227Driving a motor vehicle 207100 mrem/yr for 70 yrs 10Coffee 6


Estimated Loss of Life Expectancy From

Industrial Hazards Avg. DaysIndustry Lost

Mining/Quarrying 328Construction 302Agriculture 277Radiation dose of 5 rem/yr. for 50 yrs. 250Transportation/Utilities 164All industry 74Government 55Service 47Manufacturing 43Trade 30Radiation accidents (deaths from exposure) <1


Caution

Contamination Area

Anti-C Anti-C

Regulatory Basis

Personnel Exposure Limits


Basis of NRC and State LimitsEnvironmental Protection Agency

National Council on Radiation Protection and Measurements (NCRP)

International Commission on Radiological Protection (ICRP)

ALARA - As Low As Reasonably Achievable


Dose Limits

Whole Body 5 rem/yr.

Extremities 50 rem/yr.

Skin & organs 50 rem/yr.

Lens of the eye 15 rem/yr

Pregnant Woman 0.5 rem/term

Visitors and 0.1 rem/yr. Public


Caution

Contamination Area

Anti-C Anti-C

Site Remediation

Personnel Survey


PERSONNEL SURVEY

Detection/measurement of radiations emitted by radioactive materials to ensure:

Personnel are not inadvertently contaminatedContamination is not spreadRemember hands, face, & feet


OPERATIONAL USE

Routine operationBattery check Background check


MODEL 3 SURVEY METER AND MODEL 44-9 G-M DETECTOR


POCKET DOSIMETER


Caution

Contamination Area

Anti-C Anti-C

Site Remediation

Contamination and Decontamination


Types of ContaminationRemovable contamination - contamination that can

readily be removed from surfaces and could be inhaled or ingested.

Fixed contamination - contamination that cannot be readily removed from surfaces.

Airborne contamination - contamination suspended in air. (breathable air zone)


Sources of ContaminationPoor housekeeping in contaminated areas.

Sloppy work practices, such as cross-contamination of tools, equipment or workers

Leaks or tears in radiological containers; such as barrels, plastic bags or boxes.

Excessive motion or movement in areas of higher contamination.

Airborne contamination depositing on surfaces


Indicators of PossibleArea Contamination

Leaks, spills, standing water

Dusty, hazy air

Damaged containers

Unexplained personnel contaminations at restricted area exits

Higher than normal background on personnel survey instruments


Methods to Prevent Contamination

Preventative Maintenance

Establish adequate work controls before starting jobs.

Good housekeeping and cleaning up after jobs

Prompt corrective action for leaks and defective equipment

Administrative Controls (RWP’s, procedure reviews, access controls, etc.)


Contamination Monitoring EquipmentContamination monitoring equipment is used to detect

radioactive contamination on personnel.

Hand Held Friskers


Personnel Protective MeasuresWhen engineering methods are not adequate then

personnel protective measure will be used such as:

Protective clothing

Respiratory equipment

Anti-C

Anti-C


Protective Clothing

The degree of clothing required is dependent on :

Contamination levels in the area

Type and form of contamination

The work being performed

Potential for increased levels of contamination

Area of the body at risk

Competing hazards, ie., heat stress, asbestos, etc.


Proper Use of Protective Clothing Inspect all protective clothing prior to use.

Minimize the wearing of watches, rings, jewelry, etc.

Supplemental dosimeters should be worn outside the coveralls for ease of reading.

Don protective clothing prior to entering the contaminated area, then proceed directly to the work area.

Avoid getting coveralls wet.

Contact Radiation Protection personnel if clothing becomes ripped, torn or damaged.


DecontaminationDecontamination is the removal of radioactive materials from locations

where they are not wanted. If the presence of transferable contamination is found, decontamination is a valuable means of control.

This is not always possible due to:

Economical conditions

Radiological conditions


Decontamination

Decontamination is the removal of radioactive materials from locations where they are not wanted. This does not result in the disappearance of radioactive material but involves the transfer of the radioactive materials to another location.

» Material Decontamination

» Personnel Decontamination


Personnel Decontamination

Radiation Protection personnel must be notified immediately in the event of personnel contamination.

Personnel decontamination will be done under the direction of Radiation Protection personnel.

The normal decontamination technique for skin is washing with mild soap and luke warm water.


Caution

Contamination Area

Anti-C Anti-C

Site Remediation

Posting and Labeling


Areas are designated with a magenta (or black) standard three-bladed radiological warning symbol on a yellow background.

Yellow and magenta ropes, tapes, chains, or other barriers are used to denote the boundaries.

Barriers are clearly visible from every side.

Entrance points have signs stating the entry requirements

Radiological Posting Requirements


Radiation AreaAn area where radiation dose rates are > 5 mrem/hr but

< 100 mrem/hr.

The postings/signs will indicate:

"CAUTION, RADIATION AREA"

"TLD Required for Entry" Caution

Radiation AreaTLD

Required for Entry


Contamination AreaAn area where contamination levels are higher the

removable contamination limits.The posting/signs will indicate:

"CONTAMINATION AREA"Caution

Contamination Area


Radioactive Materials AreaAn area that is established to indicate areas where

radioactive materials are used, handled or stored.

The postings/signs will indicate the following:

"CAUTION, RADIOACTIVE MATERIALS AREA"

Caution

Radioactive Materials Area


§20.1904 Labeling containers.(a) The licensee shall ensure that each container of licensed material bears a durable, clearly visible label bearing the radiation symbol and the words "CAUTION, RADIOACTIVE MATERIAL" or "DANGER, RADIOACTIVE MATERIAL." The label must also provide sufficient information (such as the radionuclide(s) present, an estimate of the quantity of radioactivity, the date for which the activity is estimated, radiation levels, kinds of materials, and mass enrichment) to permit individuals handling or using the containers, or working in the vicinity of the containers, to take precautions to avoid or minimize exposures.

(b) Each licensee shall, prior to removal or disposal of empty uncontaminated containers to unrestricted areas, remove or deface the radioactive material label or otherwise clearly indicate that the container no longer contains radioactive materials.


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