Biological Effects Of Radiation

Question 1

Define Roentgen R

Answer 1

Measure of the ionization produced in air by X-ray or gamma radiation.
1R=1 electrostatic unit of charge (ESU) in 1 cc of dry air at STP.

Question 2

Define RAD

Answer 2

Radiation Absorbed Dose
Measure of the absorbed dose of any ionizing radiation in terms of energy per unit mass.
1 RAD=100 eggs per gram material.

Question 3

Define REM

Answer 3

Roentgen Equivalent Man
Dose equivalent
REM=RAD x Quality factor.
SI unit for dose is Sievert.
1 Sv=100 REM

Question 4

Examples of Quality Factors

Answer 4

Alpha-20
Fast Neutron-10
Proton-10
Slow Neutron-2
Beta/Gamma-1

Question 5

Calculate doses/dose rates for varying radiation fields

Answer 5

Dose equivalent=absorbed dose x quality factor.
Dose=dose rate x time.

Question 6

Calculate dose rate from gamma energy from a point source

Answer 6

R/hr=(6•C•E)/d^2

C=activity in Curies
E=gamma energy in MeV
d=distance from source in FEET.

Question 7

Point source distance calculation

Answer 7

I1d1^2=I2d2^2

Question 8

Line source distance calculation.

Answer 8

If <3 x length-> direct relationship
I1d1=I2d2

If >3 x length-> acts like point source
I1d1^2=I2d2^2

Question 9

Plane source distance calculations

Answer 9

If <3 x SHORTEST side-> no change in dose rate.

If >3 x SHORTEST side but < 3 x longest side -> line source

If >3 x LONGEST side-> point source

Question 10

Half Value Thicknesses (HVT) for various materials

Answer 10

Lead-.05”
Steel-1.0”
Concrete-3.5”
Water-7.0”

Question 11

Calculate dose rate using HVT/TVT

Answer 11

I=Io(1/2)^N or I=Io•2^-N

N=X (thickness)/HVT

I=Io(1/10)^N or I=Io•10^-N

N=X (thickness)/TVT

Question 12

Tenth Thickness Values for various materials

Answer 12

Lead-1.5”
Steel-3.0”
Concrete-12”
Water-24”

Question 13

Types of radiation that are an INTERNAL dose hazard

Answer 13

Alpha
Beta

Question 14

Types of radiation that are an EXTERNAL dose hazard

Answer 14

Gamma
Neutron

Question 15

Describe Direct Cellular Damage

Answer 15

Radiation interacts with an important molecule (DNA) causing a change or break in the molecule. Could result in a mutated cell as it reproduces.

Question 16

Describe Indirect Cellular Damage

Answer 16

Radiation interacts with molecule in the cytoplasm of the cell which results in the formation of ions or radicals which could react with important molecules of the cell resulting in permanent damage.

Question 17

Rank tissues by Radiosensitivity.

Answer 17

Lymphoid
Immature Blood Cells
Gastro Intestinal Cells
Gonads
Skin
Blood Vessels
Liver and Adrenal Cells
Bone
Muscle
Nerve Cells

Question 18

4 Stages of Radiation Syndrome

Answer 18

1: Radiation Illness
2: Apparent Recovery
3: True Illness
4: Death or Recovery

Question 19

Define LD50

Answer 19

Lethal dose 50%
The dose at which 50% of people exposed will die within 30 days WITHOUT medical treatment
400 REM

Question 20

Define LD100

Answer 20

Dose at which 100% of people exposed will die within 30 days WITHOUT medical treatment.
600 REM

Question 21

How is Tritium produced?

Answer 21

Ternary Fission. Higher than any other source, however it is contained in the FUEL ROD.
From neutron absorption of B10->primary source in RCS.
Li6(7) neutron absorption in RCS. Less likely than B10 production.

Question 22

Where is Tritium likely to be found?

Answer 22

Containment- place with largest coolant inventory.
<3.5 microCi per gram in RCS should preclude requirement for PPE.
SFP/Refueling Water- Boron is also in these areas and can absorb neutrons to produce Tritium.

Question 23

Protective actions to reduce effects of Tritium.

Answer 23

Engineering Controls-eliminate source (purge air space, release liquid/dilute).
PPE- respirators (if airborne)
Waterproof clothing (if waterborne)