RADIATION SAFETY EXAM REVIEW
Q&A
Radioactivity - Answer-Spontaneous process characteristic of atoms with unstable
nuclei in which the nucleus releases energy either as a particle with kinetic energy or as
electromagnetic energy
Parent Isotope - Answer-Original isotope prior to radioactive decay
Daughter Isotope - Answer-Isotope after the transformation
Radioactive Decay - Answer-Disintegration rate = decay rate = rate of radioactive decay
Used to indicate the "radioactivity" or the "activity"
Curie (Ci) - Answer--Unit of activity
-Amount of radioactive material having a disintegration rate of 3.70 X 10^10
disintegrations per second (dps)
-No information on the TYPE of radiation emitted during the radioactive decay
Becquerel (Bq) - Answer-SI unit of activity
1 Bq = 1 dps
Nuclear Regulatory Commission (NRC) - Answer-Uses curie to denote activity levels
Half-Life - Answer-Corresponds to the time necessary for one half of the radioactive
atoms of a sample to decay
Fraction remaining = (1/2)^n
Radionuclide - Answer-Unstable nuclide; any specific combination of neutrons and
protons comprise a nuclide
3H - Answer-12.3 years
14C - Answer-5700 years
32P - Answer-14.3 days
35S - Answer-88 Days
125I - Answer-60 days
4 Types of Radioactive Decay - Answer-1) Alpha Decay
, 2) Beta Decay
3) Electron Capture
4) Isomeric Transition
Alpha Decay - Answer--Generally limited to isotopes of heavy elements
-A charged alpha particle, consisting of 2 protons and 2 neutrons, is ejected from the
nucleus with high KE (~4 MeV)
-Stopped by a few microns of tissue
-After emission of an alpha particle, the daughter atom may be in an excited level
-Resulting transition to the ground state is generally accompanied by emission of a
gamma ray
Gamma Ray - Answer-A photon of EM energy that is emitted from the nucleus of an
excited atom
Isotopes - Answer-Same atomic number (Z), different mass numbers (A)
Beta Decay - Answer--Emission of an electron from the nucleus
-Electron can be negatively charged (beta particle--ordinary electron) OR a positively
charged positron
Simple Beta-Decay - Answer--Daughter nucleus is at the ground state after the decay
-Only particle emitted is a beta particle
-14C, 3H tritium, 32P, 35S
Excited Isomeric State - Answer-Subsequent emission from the nucleus of a photon of
EM radiation= gamma ray
Electron Capture - Answer-Unstable nucleus of certain isotopes can convert a proton to
a neutron (an orbital electron is captured while passing through the nucleus of these
unstable nuclei and the electron combines with a nuclear proton to yield a neutron)
Rearrangement of orbital electrons is generally accompanied by the emission of
characteristic x-rays
If the decay leaves daughter at an excited level gamma rays are likely to be emitted in
subsequent transitions
51Cr, 125I
Isomeric transition - Answer-Excited levels and ground state level of a radionuclide only
differ in nuclear energy content
Various energy levels are called nuclear "isomers" and the transitions between them are
isomeric transitions
Q&A
Radioactivity - Answer-Spontaneous process characteristic of atoms with unstable
nuclei in which the nucleus releases energy either as a particle with kinetic energy or as
electromagnetic energy
Parent Isotope - Answer-Original isotope prior to radioactive decay
Daughter Isotope - Answer-Isotope after the transformation
Radioactive Decay - Answer-Disintegration rate = decay rate = rate of radioactive decay
Used to indicate the "radioactivity" or the "activity"
Curie (Ci) - Answer--Unit of activity
-Amount of radioactive material having a disintegration rate of 3.70 X 10^10
disintegrations per second (dps)
-No information on the TYPE of radiation emitted during the radioactive decay
Becquerel (Bq) - Answer-SI unit of activity
1 Bq = 1 dps
Nuclear Regulatory Commission (NRC) - Answer-Uses curie to denote activity levels
Half-Life - Answer-Corresponds to the time necessary for one half of the radioactive
atoms of a sample to decay
Fraction remaining = (1/2)^n
Radionuclide - Answer-Unstable nuclide; any specific combination of neutrons and
protons comprise a nuclide
3H - Answer-12.3 years
14C - Answer-5700 years
32P - Answer-14.3 days
35S - Answer-88 Days
125I - Answer-60 days
4 Types of Radioactive Decay - Answer-1) Alpha Decay
, 2) Beta Decay
3) Electron Capture
4) Isomeric Transition
Alpha Decay - Answer--Generally limited to isotopes of heavy elements
-A charged alpha particle, consisting of 2 protons and 2 neutrons, is ejected from the
nucleus with high KE (~4 MeV)
-Stopped by a few microns of tissue
-After emission of an alpha particle, the daughter atom may be in an excited level
-Resulting transition to the ground state is generally accompanied by emission of a
gamma ray
Gamma Ray - Answer-A photon of EM energy that is emitted from the nucleus of an
excited atom
Isotopes - Answer-Same atomic number (Z), different mass numbers (A)
Beta Decay - Answer--Emission of an electron from the nucleus
-Electron can be negatively charged (beta particle--ordinary electron) OR a positively
charged positron
Simple Beta-Decay - Answer--Daughter nucleus is at the ground state after the decay
-Only particle emitted is a beta particle
-14C, 3H tritium, 32P, 35S
Excited Isomeric State - Answer-Subsequent emission from the nucleus of a photon of
EM radiation= gamma ray
Electron Capture - Answer-Unstable nucleus of certain isotopes can convert a proton to
a neutron (an orbital electron is captured while passing through the nucleus of these
unstable nuclei and the electron combines with a nuclear proton to yield a neutron)
Rearrangement of orbital electrons is generally accompanied by the emission of
characteristic x-rays
If the decay leaves daughter at an excited level gamma rays are likely to be emitted in
subsequent transitions
51Cr, 125I
Isomeric transition - Answer-Excited levels and ground state level of a radionuclide only
differ in nuclear energy content
Various energy levels are called nuclear "isomers" and the transitions between them are
isomeric transitions
