Objectives Flashcards
Define the Roentgen unit of measurement
A measure of the ionization produced in air by X-ray or gamma radiation.
1R = amount of X-ray or gamma radiation producing 1 ESU in 1 cc of dry air at STP.
Define the RAD unit of measurement
RAD (Radiation Absorbed Dose) = a measure of the absorbed dose of any ionizing radiation in terms of energy absorbed per unit mass.
1 RAD = amount of radiation which deposits 100 ergs of energy per gram of material.
Define the REM unit of measurement
REM (Roentgen Equivalent Man) = the absorbed dose in RADs multiplied by the Quality Factor (QF).
REM has equal biological effects, so can be added to give overall risk estimate.
List the Quality Factors for each radiation source.
Alpha = 20 QF
Fast neutrons = 10 QF
Thermal (slow) neutrons = 2 QF
Beta = 1 QF
Gamma = 1 QF
Given a field in Roentgen or RAD per hour, determine the dose rate in REM/hr for the type(s) of radiation present in the field.
REM = RAD × QF
If multiple radiation types are present (alpha, gamma, etc) then plug each type into the equation and add all the products to get total dose.
Given the gamma energy emitted from a point source, determine the dose rate at a given distance from that source.
R/hour = (6CE)/d^2
C = activity source in Curies
E = gamma energy in MeV
d = distance from source in feet
This equation is for gamma activity only!
Mind the units! You may have to convert.
Given a list of shielding materials, order them by effectiveness in shielding gamma and neutron radiation.
Least to most effectiveness:
Water
Concrete
Steel
Lead
Classify the four types of radiation as an internal or external hazard.
Internal hazards (unable to penetrate skin so would have to be ingested):
Alpha particles
Beta particles
External hazards (do not have to be ingested to damage tissue):
Gamma
Neutron
Describe Direct Cellular Damage
Radiation interacts with an important molecule (DNA) causing a change or break in the molecule. Could result in a mutated cell.
Describe Indirect Cellular Damage
Radiation interacts within the cytoplasm of the cell forming ions or radicals (hydrogen peroxide) which could cause permanent damage.
Given a list of tissues, rank them in order of radiosensitivity.
From most sensitive to least:
- Lymphoid tissue
- Immature blood cells
- Gastro-intestinal cells
- Gonads
- Skin
- Blood vessels
- Liver & adrenal cells
- Bone
- Muscle
- Nerve cells
State the four stages of the radiation syndrome
- Radiation illness
- nausea, vomiting, diarrhea, hair loss - Apparent recovery
- you seem fine; no symptoms - True illness
- initial symptoms plus hemorrhage, sore throat - Death or recovery
- depends on magnitude of exposure
Define LD 50 and state its associated Rem value
LD 50 = Lethal Dose 50
The dose at which 50% of the people exposed would die within 30 days (with no medical treatment).
Approximately 400 Rem
Define LD 100 and state its associated Rem value
LD 100 = Lethal Dose 100
The dose at which 100% of the people exposed would die within 30 days (with no medical treatment).
Approximately 600 Rem
Describe the methods by which tritium is produced
In a fuel rod, tritium is produced by ternary fission, which is when you have three fission fragments from a fission reaction.
In the RCS water, tritium is produced by Boron-10 activation:
Boron-10 + neutron =
Helium atom + tritium.
The two remaining methods of producing tritium produce negligible amounts of tritium. They are:
Lithium reactions (similar to Boron-10 activation)
Deuterium reaction
