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Health Physics Funda

Health Physics Funda

Rod Reed, Ph.D., C

Rod Reed, Ph.D., C

Senior Health Physicis

Senior Health Physicis

US Nuclear Regulatory Comm

US Nuclear Regulatory Comm

Technical Training Cent

Technical Training Cent

Chattanooga, Tennesse

Chattanooga, Tennesse

(423) 855 (423) 855-6513

rpr1@nrc.gov 1@nrc.gov

September 6, 2007 September 6, 2007

U.S.NR

UNITED STATES NUCLEAR REGULATORY COM

Protecting People and the Enviro

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Atomic Structu

Atomic Structu

3⁄4 Atomic Structure Atomic Structure

3⁄4 Protons (p) Protons (p)3⁄4 Neutrons ( Neutrons (η)3⁄4 Electrons (e) Electrons (e)
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Isotopes of the Elemen

Isotopes of the Eleme
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Radioactivity and Ra

Radioactivity and R

3⁄4 Types of Radiation Types of Radiation

3⁄4 Particle emission ( Particle emission (α, β-, β+)3⁄4 Photon emission ( Photon emission (γ, x-ray)
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Radiation Penetra
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Activity
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0.001 gm 1 gm 6

Amount in grams of Amount in grams of each isotope equaling each isotope equaling one curie one curie of activity of activity

27

60Co

226Ra 88

238U92

Mass vs Activit

Mass vs Activit

210Po · 0.00022 gm 0.00022 gm
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Ionizing Radiati

Ionizing Radiati

Half Life Half Life

3⁄4 amount of time for half of the ac

amount of time for half of the ac

3⁄4 half life is unique to each radion

half life is unique to each radion

3⁄4 N-16 is 7 seconds (BWRs) 16 is 7 seconds (BWRs)

3⁄4 Co-60 is 5.3 years 60 is 5.3 years3⁄4 Cs-137 is 30.17 years 137 is 30.17 years3⁄4 Po-210 is 138 days 210 is 138 days
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Radiation Units
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SI vs Special Un

SI vs Special Un

SI Unit SI Unit Special Special 

Unit

Conve

Conve

Gray Rad 1 Gy = 

1 Gy = 

Sievert Sievert Rem 1 Sv = 1

1 Sv = 1

Becquerel Becquerel Curie 1 Ci = 3.7 

1 Ci = 3.7 

1 rem = 1,000 millirem (m

1 rem = 1,000 millirem (m

1 Curie = 1,000 millicuries 

1 Curie = 1,000 millicuries 
Yucca Mtn Yucca Mtn

Regio

Regio

TTC 

Region IV Region IV

* 1 μR = 1/1,000,000 R R = 1/1,000,000 R

1 milliroentgen (mR)= 1,000 1 milliroentgen (mR)= 1,000 μR

*
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Medical Procedu

Medical Procedu

Procedure Procedure Dose (m

Dose (m

X-Rays

Abdomen Abdomen 40

Chest 6

Pelvis 60

Dental 3

Mammography Mammography 40

CT (full body) CT (full body) 130

Nuclear Medicine Nuclear Medicine 400
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Annual Background R

Annual Background R

Dose to Average US 

Dose to Average US 

~28 mrem

~39 mrem

Natural Background Natural Background

vs

Artificial Background Artificial Background
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External Radiation Do

External Radiation Do

Gamma, beta or neutron radiation Gamma, beta or neutron radiation emitted by radioactive material emitted by radioactive material outside outside the body exposing the skin, the body exposing the skin, lens of the eye, extremities & the lens of the eye, extremities & the whole body (i.e. internal organs) whole body (i.e. internal organs)
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Internal Radiation Dos

Internal Radiation Dos

Alpha, beta or gamma radiation Alpha, beta or gamma radiation emitted by radioactive material emitted by radioactive material inside the body exposing the body exposing 

internal organs such as: internal organs such as:

thyroid thyroid

bone

RAM is inhaled RAM is inhaled or swallowed or swallowed
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KI Effectiveness v

KI Effectiveness v

Time of Administra

Time of Administra

KI can reducethyroid dose thyroid dosein an emergency in an emergencyinvolving radio involving radioactive iodine active iodine
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The Cell The Cell
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Low-level Radiation 

level Radiation 

(most exposure

(most exposure

3⁄4 Cancer – proven at higher dose

proven at higher dose

(e.g. > 10 rad acute); assumed t

(e.g. > 10 rad acute); assumed t

lower doses, with no threshold lower doses, with no threshold

3⁄4 Genetic effects Genetic effects - occur in mice a

occur in mice 

assumed to occur in humans bu

assumed to occur in humans bu

proven
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Can Radiation Exp

Can Radiation Exp

Cause This? Cause This?
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Low-Level Effects Level Effects - 

3⁄4 Natural cancer rate = 20% or 1 in 

Natural cancer rate = 20% or 1 in 

out of every 10,000 people) out of every 10,000 people)

3⁄4 Radiation risk of cancer (hypoth

Radiation risk of cancer (hypoth

0.04% or 4 in 10,000 per rem 0.04% or 4 in 10,000 per rem

3⁄4 Thus, 1 rem might increase tota

Thus, 1 rem might increase tota

to an exposed person to 20.04% to an exposed person to 20.04%
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High Levels of Rad

High Levels of Rad

(occur rarely) (occur rarely)

Acute Radiation Syndromes: Acute Radiation Syndromes:3⁄4 100 rad 100 rad - hematopoietic (blood) hematopoietic (blood)3⁄4 500 rad 500 rad – gastrointestinal (GI) gastrointestinal (GI)3⁄4 2,000 rad 2,000 rad - central nervous system (C

central nervous system (C

3⁄4 LD50/60 - lethal dose to 50% of people w

lethal dose to 50% of people 

approximately 400 rad (whole body ex

approximately 400 rad (whole body ex
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NRC Occupation

NRC Occupation

Dose Limits Dose Limits

Whole Body (TEDE) Whole Body (TEDE) 5,000 mrem

5,000 mrem

Any Organ (TODE) Any Organ (TODE) 50,000 mrem

50,000 mrem

Skin (SDE) Skin (SDE) 50,000 mrem

50,000 mrem

Extremity (SDE) Extremity (SDE) 50,000 mrem

50,000 mrem

Lens of Eye (LDE) Lens of Eye (LDE) 15,000 mrem

15,000 mrem

Embryo/Fetus of DPW Embryo/Fetus of DPW 500 mrem

500 mrem

Member of the Public Member of the Public 100 mrem

100 mrem

Note: 1,000 mrem = 1 rem
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THE EN

THE EN