Slide 1 Atomic Structure & Radiation Gary M. Sandquist, PhD, CHP, PE 2011 Training Session Community Environmental Monitoring Program CEMP.

Slide 1

Atomic Structure & Radiation

Gary M. Sandquist, PhD, CHP, PE

2011 Training Session

Community Environmental Monitoring Program CEMP

Slide 2

CEMP Training OutlineCEMP Training Outline

Basic Atomic Structure Introduction to Radioactivity Radiation Sources Biological Effects Radiation Risks Radiation Limits

Slide 3

CEMP Training OutlineCEMP Training Outline

Personnel Monitoring ALARA Program Radiation Posting & Control Radiation Work Permits Radiological Emergencies

Slide 4

CEMP Training OutlineCEMP Training Outline

Radioactive Waste Minimization

Radiation Contamination Control

Practical Exercise

Slide 5

IsotopesIsotopes

ISOTOPES:

Atoms with same number protons (same atomic number) but different number of neutrons in nucleus

(Mass number different but not atomic #)

238U versus 235U – atomic # = 92

Chemistry of isotopes identical!

238U same chemistry as 235U

Slide 6

Stable & Unstable AtomsStable & Unstable Atoms

Only certain combinations of neutrons & protons are stable nuclei.

Too many or too few neutrons for same number of protons then nucleus has excess energy & is unstable.

Unstable atoms become more stable by reducing excess energy through release of radiation.

Unstable nuclei known as radioactive atoms.

Slide 7

Radiation Symbol - RadioactivityRadiation Symbol - Radioactivity

Slide 8

Alpha Particles ( He4 )Alpha Particles ( He4 )

PHYSICAL CHARACTERISTICS

Large mass

2 protons, 2 neutrons no electrons

Positive charge +2

Highly charged particle emitted from nucleus of atom.

Positive charge +2 causes alpha particle (+) to strip electrons (-) from nearby atoms as it passes through material, thus ionizing these atoms.

SHIELDING Stopped by

outer layer of skin, few centimeters of airor one sheet of paper.

BIOLOGICAL HAZARD No external

radiation hazard. Internally deposits large

amount of energy in small volume of body

Slide 9

Beta Particles ( e-1 or e+1 )Beta Particles ( e-1 or e+1 )

PHYSICAL CHARACTERISTICS

Small mass emitted from nucleus of atom with electrical charge of -1.

Cause ionization by displacing electrons from their orbits.

Same as electron.

Ionization caused by repulsive force between beta particle (-) & electron (-);

RANGE Limited penetrating ability

(< 10 feet in air) because of negative charge.

SHIELDING Most beta particles

shielded by plastic, glass, metal foil, safety glasses

BIOLOGICAL HAZARD An internal hazard due to

short range.

Hazardous to skin & eyes.

Slide 10

Gamma/X Rays (or x )Gamma/X Rays (or x )

PHYSICAL CHARACTERISTICS

Electromagnetic wave or photon with no electrical charge.

Gamma rays similar to x rays, but from nucleus.

Gamma/x ray radiation ionizes by direct reaction with orbital electrons.

Energy of gamma/x ray radiation transmitted directly to target.

RANGE Gamma/x rays have no

charge or mass Very penetrating Range in air - few hundred

feet.

SHIELDING Best shielded by dense

materials (concrete, lead or steel).

BIOLOGICAL HAZARD Produces radiation

exposure to whole body.

Slide 11

Activity UnitsDisintegrations Per Unit Time

Activity UnitsDisintegrations Per Unit Time

Traditional (US) unit is Curie

1 Ci = 3.7 x 1010 dps (dis/sec)

1 Ci = 2.22 x 1012 dpm (dis/min)

1 Ci = 1 x 1012 pCi

1 Ci = 37 GBq International unit is Becquerel

1 Bq = 1 dps = 2.70 x 10-11 Ci

1 GBq = 0.0270 Ci

Slide 12

Radiation Dose UnitsRadiation Dose Units

rad = 100 ergs/gram of absorber -(Gray) mrad = 1/1000th of rad rem = rad x Quality Factor -(Sievert) Quality Factors

alpha = 20

beta = 1

gamma = 1

neutron ~ 10(avg) varies 2 to 20

Slide 13

Radioactive Half-lifeRadioactive Half-life

Time for 1/2 of radioactive atoms to decay

to something else

Example: 1 Ci X-365 has half life of 1 yr:

How much after 2 yrs, 10 yrs, 20 yrs?

X(1 yr) = X(0) x (1/2)n with n=2

So activity X(2 yr) = X(0) x (1/2)2 =1/4 X(0)

X(10 yr) = X(0) x (1/2)10 ~ 1/1000 X(0)

X(20 yr) = X(0) x (1/2)20 ~ 1/million X(0)

Slide 14

Natural Sources (2006 NCRP)Natural Sources (2006 NCRP)

Cosmic radiation ~ 5% Terrestrial radiation ~ 3% Internal radiation ~ 5% Radon / Thoron ~ 37 %

Slide 15

Man-Made SourcesMan-Made Sources

Medical radiation ~ 48% Nuclear weapon tests < 0.1% Consumer products ~ 2% All energy production & research

< 0.1% or < 0.5 mrem Industrial uses < 0.1% Fukushima < 1 foot elevation

Slide 16

Medical RadiationMedical Radiation

X-rays - medical (CT’s, etc) & dental

Radioactive material for diagnosis 131I, 99Tc, 32P, 3H, 14C

Radioactive material for therapy 60Co, 137Cs, 226Ra, neutrons

Annual dose ~298 mrem ~48% total

Slide 17

620 mremTotal average US

rad exposure(NCRP report 160 - 2006)

Prior US level - 360mrem

Average Total Annual DoseAverage Total Annual Dose

Slide 18

Radiation DamageRadiation Damage

Direct Effects:

Ionization can break chemical bonds

Indirect Effects:

Ionized water results in radicals H+ or HO- or H2O2

These radicals cause chemical damage

Location of damage important:

Cell Nucleus or Cytoplasm

Slide 19

Possible Effects on CellsPossible Effects on Cells

No damage evident

Damage repaired & cell normal

Damage not repaired & cell functions abnormally

Cell dies

Slide 20

Cell SensitivityCell Sensitivity

Cells have different rad sensitivity Most sensitive: Cells actively

dividing (e.g., stem & blood cells) Moderate sensitive: Less specialized

cells Least sensitive: Specialized cells or

less actively dividing (nerve, brain, bone, muscle cells, skin )

Slide 21

Dose Rate EffectsDose Rate Effects

Acute: Large dose over short time

10-25 rem slight blood changes

300-500 rad hematopoetic syndrome

500-1000 rad GI syndrome

>1000 rad CNS syndrome Chronic: Low dose rate over long

time e.g., Background radiation

Slide 22

Factors for Biological DamageFactors for Biological Damage

Total dose (how much) Dose rate (how fast) Type of radiation

(alpha, beta, gamma, neutron) Area exposed

(total body, internal, hands, etc.) Cell sensitivity Individual person sensitivity

Slide 23

Risk From ExposureRisk From Exposure

No observed increase of risk at occupational exposures

Risk factor: 4 x 10- 4 latent health effects per rem (LNT model)

Cancer formation latency time > 10 yr More solid tumor formation

at old age

Slide 24

Perspective of RiskEstimated Loss of Life Expectancy during lifetime

Perspective of RiskEstimated Loss of Life Expectancy during lifetime

Health Risks

20 cigarettes/day 6 years

15% overweight 2 years

Consuming alcohol 1 year

All Accidents 1 year

Motor vehicle 207 days

Home accident 74 days

Drowning 24 days

Natural hazards 7 days

Medical radiation 15 days

620 mrem/y for 47 y 31 days

(US Background dose)

1 rem/y for 47 y 50 days

Industrial Accidents

All industries 60 days

Agriculture 320 days

Construction 227 days

Mining 167 days

Transportation 160 days

Government 60 days

Manufacturing 40 days

Trade 27 days

Services 27 days

Nuclear Plant 27 days

Slide 25

DOE & USNRC Occupational Dose Limits

DOE & USNRC Occupational Dose Limits

Whole Body 5 rem per yr

Lens of Eyes 15 rem per yr

Extremities 50 rem per yr

Skin 50 rem per yr

Organ or Tissue 50 rem per yr

Unborn Child 0.5 rem pregnancy

(US Background 0.62 rem per yr)

Slide 26

Declared Pregnant Worker(Embryo / Fetus)

Declared Pregnant Worker(Embryo / Fetus)

Policy: Female radiation worker encouraged to voluntarily notify supervisor (written) if pregnant.

Employer must provide agreeable work with limited (~no rad) exposure @ no loss of pay or promotional opportunity

Further occupational rad exposure unlikely during pregnancy.

Slide 27

Occupational Dose Equivalent Limits

Occupational Dose Equivalent Limits

General Public

100 mrem/yr Any Occupational Worker

(unmonitored)

100 mrem/yr Radiation Worker (monitored)

5,000 mrem/yr = 5 rem/yr

Slide 28

External & Internal Radiation Dose Reduction

External & Internal Radiation Dose Reduction

Use shielding if possible Minimize time in radiation field Maximize distance to rad source Dose ~ Source x time / (distance)2

Slide 29

ALARAALARA

As Low As Reasonably Achievable (called ALARA by regulators)

Radiation protection program manage exposures (individual & collective to workforce & public) as low as social, technical, economic, practical, public policy permit.

ALARA not dose limit but a process “maintain dose levels “As Low As Reasonably Achievable.”

Slide 30

ALARA Management PolicyALARA Management Policy

Radiation exposure maintained As Low As Reasonably Achievable, considers social & economic needs.

Radiation exposure to workers controlled to ensure radiation exposures well below regulatory limits.

No occupational radiation exposure allowed without expected benefits (health, economic, social, etc.).

Slide 31

Radiological Control Responsibilities

Radiological Control Responsibilities

Provide technical & programmatic control over radiation & radioactive materials

Provide Health Physics (HP) personnel & monitoring equipment

Issue Radiation Work Permits (RWPs) Maintain dosimetry program Maintain training program

Slide 32

Radiation Posting RequirementsRadiation Posting Requirements

Areas controlled for radiological purposes designated with magenta (or black) standard three-bladed radiological warning symbol on yellow background

Yellow & magenta ropes, tapes, chains, or other barriers used to denote & control boundaries.

Slide 33

Radiological AreasRadiological Areas

Radiological Buffer Area Radiation Area High Radiation Area Very High Radiation Area Contamination Area High Contamination Area Fixed Contamination Area Soil Contamination Area Airborne Radioactivity Area

Slide 34

Area with radiation dose rates > 5 mrem/hr but < 100 mrem/hr

Entry requirements:

Rad Worker I or II Training

Worker signature on RWP

Required Dosimetry

Requirements in work area Don’t loiter Practice ALARA

Radiation AreaRadiation Area

Slide 35

Radiation dose rate > 100 mrem/hr & < 500 rad/hr.

Entry requirements

Radiological Worker II Training

Worker’s signature on job-specific RWP

Requirements for work in area

Personnel & supplemental dosimeters

Survey meters or dose rate indicating device

Access points secured by control devices, locks, etc.

High Radiation AreaHigh Radiation Area

Slide 36

Area where radiation dose rates > 500 rad/hr

Entry requirements:

Radiological Worker II Training

Worker signs job-specific RWP

Requirements for work in area:

Personnel & supplemental dosimeters

Survey meters or dose rate indicating device

Access points secured by control devices, locks, etc.

Very High Radiation AreaVery High Radiation Area

Slide 37

Area where surface has removable contamination > given limits

Entry Requirements:Radiological Training II

Worker signs RWP

Requirements for work in area: Personnel dosimeter if necessary

Minimize dust generation

Respiratory protection if necessary

Contamination AreaContamination Area

Slide 38

Area where surface has removable contamination >10 times limits.Entry Requirements:Radiological Training IIWorker signs RWPRequirements for work in area:Personnel dosimeter if necessaryMinimize dust generationRespiratory protection if necessary

High Contamination AreaHigh Contamination Area

Slide 39

Area where surface soil contaminated above limits

Entry Requirements:Radiological Training IIWorker signs RWP

Requirements for work in area:Personnel dosimeter if necessaryMinimize dust generationMinimize earth disturbanceRespiratory protection if necessary

Soil Contamination Area Soil Contamination Area

Slide 40

Area where surface soil contaminated above limits.Entry Requirements:Radiological Training IIWorker signs RWPRequirements for work in area:Personnel dosimeter if neededMinimize dust generationMinimize earth disturbanceRespiratory protection

Airborne Contamination Area Airborne Contamination Area

Slide 41

Requirements for ExitingRequirements for Exiting

Exit at step-off pad provides “barrier” between contaminated & clean areas to prevent spread of contamination. Remove protective clothing

Perform whole body survey. If contaminated: stay in area, notify Radiological Control personnel, minimize cross-contamination.

After exiting & monitoring self, wash hands before eating, drinking, chewing, applying make-up, etc.

Slide 42

Radioactive Material AreaRadioactive Material Area

Entry requirements into Rad Materials Area if whole body dose rate > 5 mrem/hour or contamination > specified limits

Same for entry into Radiation Area or Contamination Area

Depends on radiological hazard present.

Slide 43

Hot Spot IdentificationHot Spot Identification

Hot spots - Source of radiation or rad material in area, equipment or piping

Rad levels at such spots typically higher than surrounding area

Avoid hot spots if possible

Slide 44

Control of Radioactive SpillsControl of Radioactive Spills

Stop or secure spill source Warn others in area Isolate spill if possible Minimize exposure &

contamination Secure unfiltered ventilation Requirements for exiting

- Site specific monitoring

- Monitor per posted instructions before entry to clean area

Notify Rad Control personnel

Changing rad conditions. Actions don’t create rad

problems for others. Be alert for activities that

change rad conditions

Slide 45

Radiation Work PermitsRadiation Work Permits

Rad Work Permit used to control routine or repetitive activities such as inspections in areas with stable radiological conditions.

Valid for up to one calendar year. Job-Specific Radiation Work Permit

control non-routine operations in areas with changing radiological conditions.

Valid only for duration of job.

Slide 46

Emergency Dose LimitsEmergency Dose Limits

Protecting property if 5 rem not practical 10 rem

Lifesaving or protection of small population if dose limit not practical:

25 rem Lifesaving or protection of large population

(volunteer basis for person aware of risk) > 25 rem

Slide 47

Segregation Rad MaterialsSegregation Rad Materials

Place rad waste only in Rad Waste receptacles

Don’t put non-rad waste or reusable rad material in Rad Waste containers

Segregate compactable material from non-compactable material

Minimize mixed waste generation

Use good housekeeping techniques

Slide 48

Personnel Protective ClothingPersonnel Protective Clothing

Protective Clothing used to enter areas with rad levels above specified limits to prevent skin contamination

Clothing depends on work area, rad conditions, job, etc.

Full protective clothing includes

coveralls

cotton glove liners & gloves

hood

shoe covers & rubber overshoes.

Slide 49

DecontaminationDecontamination

Decontamination - removal of rad materials from locations not wanted

Personnel decon usually done using mild soap & lukewarm water.

Material decon- removal of radioactive material from tools, equipment, floors & other surfaces

Slide 50

- Thank you for your participation -

Community Environmental Monitoring Program

CEMP

END of TrainingANY QUESTIONS?