Radiation Wk2

8/4/2019 Radiation Wk2

1/27

Radiation Safety

and Radiation Applications


2/27

What is Radiation? Natural and man-

made

Studied for over 100years

Particles and Rays

Different effects for

different radiations Not all radiation is

harmful


3/27

What kinds of radiation are there? Alpha Particlesa

Helium nucleus

Beta Particlesb An energetic electron emitted from the nucleus

X-Rays

Light wave emitted from the electrons in an atom Gamma Raysg

Light wave emitted from the nucleus


4/27

Two general categories of

ionizing radiation:

PARTICLES

alpha

neutron

beta

PHOTONS

X-ray

gamma ray

102-5


5/27

This is theelectromagneticSpectrum

Ionizing forms ofelectromagnetic include

Gamma Rays

X-rays UV forms the cusp but

is non-ionizing

Non ionizing are notaddress in this module

Electromagnetic Radiation Spectrum

10^21

10^20

10^1910^18

10^17

10^16

10^15

10^14

10^1310^12

10^11

10^10

10^9

10^8

10^710^6

10^5

10^4

10^3

10^2

10^1Frequency (Hz)

Radio Waves

Micro Waves

Infrared Rays

Visible Light

Ultraviolet Rays

X-rays

Gamma Rays


6/27

Summary of Types of Radiation

Alpha particles Stopped with paper Only a danger if internalized

Beta particles Stopped with cardboard or Plexiglas Can be a danger to skin or if internalized

Gamma rays

Stopped with increasingly dense material Mostly an irradiation hazard

Neutrons Stopped by water

Irradiation and activation hazard


7/27

How do we measure exposure? Geiger-Mueller Tube

Demo

Ionization Chambers

TLD for personnelexposures


8/27

Where can radiation be found? Nuclear Reactors

Power plants

Nuclear Waste

Nature

Naturally occurring

Fallout from atmospherictesting

Homes Radon

Building Materials


9/27

Nuclear Reactors Power plants

Palo Verde

Waste

Spent fuel

Low-level waste


10/27

Radiation in the environment Natural

Uranium and

Thorium in the soil Radon gas

Fallout

Atmospheric testing

CTBT in effect 1963


11/27

Medical Exposures Doses vary tremendously based on type of treatment

US Average: 53 mrem/yr

Examples: Chest x-ray (~20 mrem)

Dental x-ray (hundreds of mrem)

CAT Scan (50-5000 mrem)

Cardiac Catherization (~10 rem)

Radiotherapy (~200 rem each)

Nuclear Medicine (2000mrem/target organ


12/27

Weapons Dose depends on many factors

Size of bomb

Type of bomb Location

Weather

Time

Dirty Bombs


13/27

Internal Sources Our body tissues 39 mrem/yr

Carbon-14

Potassium-40

Radium-226

Diet

Water

Food

Brazil nuts No Salt

Whiskey

Milk

Salad Oil


14/27

Consumer Products US Average 11 mrem/yr

Products include:

Orange fiesta ware

Ceramics

Porcelains

Luminous dials Smoke Detectors

Lantern Mantles


15/27

Good Radiation vs. Bad Radiation

In the publics eye, there are two types of

radiation

Good radiation benefits humans any medicalexposure is goodradiation

Bad radiation is detrimental to humans anyindustrial/commercial exposure is badradiation; many even include natural exposure inthis category


16/27

Radiation Exposure Normally receive

300 mrem per year

Same as 30 chest x-rays

Workers allowed upto 5000 mrem/year

Public exposuremust be less than500 mrem/year


17/27

Measurement of Dose


18/27

Stands for As Low As ReasonablyAchievable

Requirement for all facilities andpersonnel

ALARA can be achieved via

Training/knowledge

Protection methods


19/27

Protection Against Radiation

Time Distance

Shielding


20/27


21/27

Inverse square law

Source: 100 mrem/hr @1 foot

2 feet

25 mrem/hr 10 feet

1 mrem/hr


22/27

100mrem/hr

1/2 Thickness

Shield

50 mrem/hr

SHIELD

One Half

Value Layer

MINIMIZE DOSE


23/27


24/27

Low Alarm(Vehicle Present)

Vehicle just leaving

Exceeded an alarm threshold

Examples of alarm settings:

Low Alarm: 0.5uR/hr-50uR/hr

High Alarm: 50uR/hr-150uR/hr

Danger: All detectors above 150uR/hr


25/27

Truck Detectors


26/27


27/27

Conclusions Radiation

Can be detected

High level effects known

Low Level effects still debated

Annual Exposure

300 mrem/year

Varies widely

Radiation Wk2

Documents