NEU Abbreviated
Study Guide

Half-Life is the term in which half of the atoms of a particular radioactive substance decay to another nuclear form, or element.

Alpha Particles (a) are Helium Nuclei emitted from the nucleus of an unstable atom.

In an atom prior to Beta Minus Decay, there will be excess neutrons in the atoms nucleus.

Quality Factor is used to convert Absorbed Dose (RAD) to Biological Effect (REM).

Neutrons can cause ionization indirectly by knocking charged particles out of the nucleus.

REM is a unit of measurement; Dose Equivalent resulting from any type of radiation exposure.

The type of gas used would affect the sensitivity of an ion chamber detector because some gases ionize more easily than others.

The function of the Photo Cathode in a Photo-multiplier Tube is to release electrons when it is struck by light emitted from scintillation.

Ionization is the general process of producing Ions by the passage of high energy particles.

MDC is the smallest number of sample counts that are statistically greater than the background counts and are a result of radioactivity in the sample.

Materials with a low Atomic Number (such as water, plastic, and paraffin) are used in making neutron shields because their atomic size allow for greater transfer of the neutrons energy per collision.

A designed method of removal for insoluble corrosion products would be filters.

A Breathing Zone Air sample is an air sample drawn from a point or series of points within the workers immediate work area.  It also provides an acceptable estimate of a workers exposure to airborne contamination.

Individual dosimeter placement could be described as an error associated with relating a dosimeter reading to an actual dose.

CDE is the dose equivalent from Internal exposure to an individual organ or tissue, as calculated over a 50 year period after the exposure.

TODE limits for adults per 10CFR20 is 50 REM per year.

Occupied work areas surveys should be performed on a daily routine basis.

The purpose of the chi-squared test is to ensure that the instrument's results lie within a normal Gaussian Distribution.

Most of the dose received by man-made sources of radiation is due to medical applications of radiation and radioactive materials.

The energy absorbed by one gram of air exposed to one Roentgen of gamma rays is 87 ergs.

After 8 half-lives 0.4% of the original activity remains.

General area dose rates should be recorded as the highest dose rate between the head and knee.

Charged particles interact with matter by Excitation and Ionization.

In soft tissue, fast neutrons lose 80% to 90% of their energy by interacting with hydrogen.

Attempting to remove contamination prior to maintenance is the most desirable method to provide radiological protection during maintenance on a highly contaminated component.

Know how Beta exposure is determined in a Beta-Gamma Radiation field using film Dosimetry. (The Beta dose is evaluated by subtracting the closed window film reading from the open window film reading.)

When removing radioactive contamination from the skin, your best choice would be a mild soap and warm water.

The difference between X-rays and gamma photons of the same energy is their origins.

According to the ICRP "ALI" stands for Annual Limit on Intake.

Tools or equipment are transferred from a contaminated area sealed in clear plastic bags.

Proportional counters operate at higher voltages than ionization chambers. (RIPLGC)

The primary mechanisms whereby charged particles lose energy in transversing materials are ionization and excitation affecting the electronic structure of the material atoms.

The major internal pathway for radionuclides is ingestion.

A single quanta of electromagnetic energy is called a photon.

A Neutron has no charge.

The last choice of engineering controls would be to use a respirator.

Isotopes are defined as atoms with the same atomic number but different atomic weight.

Gamma photons originate in the nucleus of the atom.

To convert centimeters into inches, 2.54 cm = 1 inch.

Nuclear radiation refers to the emanation of the energetic particles and/or the electromagnetic wave from the nucleus of the atom.

Stellite contains a high percentage of cobalt which is highly radioactive via neutron bombardment.

Linear Attenuation Coefficient: A fraction decreases of energy through absorption of material inverse of mean free path.

Pulse height determines which source it is.  Alpha pulses are the highest.

The Dead Time for GM detectors is the period in which a second pulse will not be detected.

Semi Conductor Detection System - the middle section composed of germanium and lithium mixture.  Pure germanium is on one side of the mixture and pure lithium on the other side.  When a gamma enters the center region of the crystal it undergoes an interaction that frees an electron from one of the atoms in the crystal.  When this happens, a vacancy, or hole is left in the inner electron shell around the nucleus.

After undergoing Compton Scattering, a gamma photon is deflected off at an angle with reduced energy.

Pair Production is when a high energy photon enters the vicinity of an atoms nucleus, the photon energy is converted into an electron-positron pair.  (1.022MeV.)

Shallow dose equivalent applies to the external exposure of the skin or an extremity and is taken as a dose equivalent at a tissue depth of 0.007cm averaged over an area of 1 cm².

The Noble Gases Xenon and Krypton are breathed in and then breathed out. (What goes in comes back out.)

REM Dose = RAD Dose x Quality Factor. Gamma = 1, Beta = 1, Thermal Neutron = 2 to 3, Fast Neutron = 10, Alpha = 20.

Swipes/smears in a loose surface contamination survey should be kept separate from one another to avoid cross contamination.

The four emergency classifications of an accident at a nuclear power plant are as follows, in descending order: General Emergency, Site Area Emergency, Alert, Unusual Event.

The Roentgen is a measure of Exposure of air to gamma and x-rays.

A child is more radiosensitive than an adult because a child's cells are multiplying more rapidly.

The nucleus carries a positive charge.  Protons and Neutrons are collectively known as "Nucleons".  The diameter of the nucleus is relatively small compared to the diameter of the atom.  Electrons carry a negative charge. Electrons, protons, and neutrons ARE NOT all about the same size.

If the skin is accidentally broken when working with a radioactive substance, immediately wash the wound under running water.

Removal of hazardous materials should be attempted prior to considering the use of respiratory protection.

Radiation initiates destruction of human tissue through the ionization process.

The highest to lowest relative penetration of 1 MeV Alpha, Beta, and Gamma rays is: Gamma, Beta, Alpha.

The basic principals of protection against external radiation hazards are Time, Distance, and Shielding. (ALARA)

Fast Neutrons are the most severe external radiation hazard.

H-1 (Hydrogen) has the most effect on the thermalization of fast neutrons as far as biological chemicals.

fission products are the most abundant source of radiation during power operation.

Kr-85, Sr-90, and  Xe-133 are fissions products.

Fe-59, Mn-59, Mn-54, Cr-51, and Co-58 are activated corrosion products in light water reactors.

A leak or venting of primary coolant, a steam leak in a BWR, or breaching a contaminated system are all examples of potential sources of radioactive airborne contamination.

Ionizing radiation interacts with the orbital electrons of an atom and creates two particles of opposite charge called ion pairs.

The chief difference between fast and slow neutrons is their (kinetic) energy.

The RAD is used as a unit of measurement for the energy deposited by any radiation in any material.

The secondary radiation produced when beta particles are stopped by shielding is Bremsstrahlung.

Alpha Gamma interactions are not a source of fission products in plant systems.

You don't check the desiccant for a initial check on instruments prior to use, or the beat shield calibration.

ALARA paint is not a source of loose surface contamination.

Air showers are not a method of controlling exposure to airborne radioactivity.

The degasifier is a method of removal for noble gasses from the reactor coolant system.

Finger rings don't have a need for neutron sensitivity. (They don't read neutrons.)

The instrument used for the best tissue equivalent dose rate is the ion chamber.

300 mg/cm² is the thickness assumed to cover the human eye.

The range of beta particles in air depends on the energy of the particle.

The range of 1Mev beta particle in air is about 10 ft. (12ft actual per Mev)

The interaction between alpha particles and atoms is most through columbic. (electrostatic)

Using the assumption that 2" of lead equals one tenth thickness, the amount of shielding required to reduce a Cs-137 gamma beam of 100 mr/hr intensity to 1 mr/hr would be 4". (1/100)

The center region is the part of the semiconductor crystal that is sensitive to ionizing radiation.

An ion chamber produces output based on the ions produced in the wall of the chamber.

The mathematical symbol for less than is: <

There are 30.4 centimeters in one foot.

Neutron detectors are easy to design because there are a large number of materials with large cross sections for absorption.

Linear attenuation coefficient is the name that describes the number of interactions per unit length.

Beta decay process: During radioactive decay, a nucleus emits an electrically charged particle equal in mass to an electron.

X-rays come from electrons changing energy levels.

Pair production is when a high energy photon (more than 1.022 Mev) enters the vicinity of an atom's nucleus, the photon energy is converted into an electron-positron pair.

After an inelastic scattering process, the excited nucleus will emit a gamma photon.

A proportional counter system can tell the difference between alpha and beta radiation because the size of the pulse caused by the alpha interaction will be much higher than the pulse caused by the beta interaction.

When a gamma ray is detected by a semi-conductor crystal a flow of free electrons is initiated toward the positive end of the crystal.

A negative pressure full-face respirator has a protection factor of 50.

A valid reason for performing radiation surveys is when shipping or receiving radioactive material.

One of the checks for a survey instrument prior to use is a calibration expiration date.

The principal that explains the operation of most radiation detection instruments in the radiation causes ionization in the detector which is converted into a meter reading.

Exhalation is an elimination route for internal contamination.

The atom is the smallest part of an element that can be separated by chemical reaction.

The access route into a contaminated area is normally across a step off pad.

A contamination survey requires the following steps be preformed in this order:
Get smears and a map, pre number smears and the map, dress properly and enter the area, pick survey spots on floor walls and equipment, drag smear in a 'S' pattern of 18 inches, fold smear and record data.

The operation of a negative pressure air purifying respirator is as follows.  During inhalation, air space inside the face plate is at a lower pressure than outside air, as worker exhales, positive pressure in mask opens exhalation valve.

Humidity will affect the ability of a sorbent to absorb iodine in an air purifying respirator.  So will breathing rate.

Radioactive decay is an elimination method for internal contamination.

The following is a method to assess beta dose in a TLD, shielding is designed into TLD to allow beta to be distinguished from gamma.

You would exercise 'Stop work authority' if the job coverage CAM trending up and the last two pipe fitters have facial contamination on their exit frisk.

ALARA concept is, follow the ALARA program determining if all administrative, engineering, operational and radiological controls and procedures are in place and being followed.

The mathematical expression which expresses the relationship between the radioactive decay constant and the half-life of an isotope is, T 1/2 = 0.693/ Decay constant.

A Proton is an elementary particle that is identical with the nucleus of a Hydrogen atom and carries a positive charge.

C0-60: The element is Cobalt, with 60 nucleons, 27 protons, 33 neutrons.

Atomic radiation refers to electromagnetic waves emitted from the electron shell.

The decay process emitting an alpha particle can be described as when a positively charged particle with a mass equal to a Helium nucleus is emitted from a nucleus during radioactive decay.

A beta particle can be either a positively or negatively charged electron.

The operation of a gas filled detector is radiation ionizes the fill gas releasing electrons that are attracted to the positively charged anode and measured by the electrical circuitry.

In the ionization chamber, the detector output is approximately equal to the amount of primary ionization produced in the gas.

The main advantage of using a proportional counter is it is able to differentiate between different types of radiation.

For a semiconductor material to detect radiation, the voltage applied to the detector must be large enough to separate the positive charges from the negative charges to form a depletion region.

Unless some type of quenching gas is used, a Geiger-Mueller detector will retrigger its avalanche because of electrons released while the positive ions interact with the outer wall.

To determine shielding, build up factors is not a valid reason to perform a radiation survey.

Temperature inversion is not a source of radioactive contamination.

A face shield is not a method of controlling airborne radioactivity.

Evaporators are a design method for removal of corrosion products from the reactor coolant system.

The following are all potential sources of airborne radioactive contamination: opening contaminated tanks, radioactive spills, and removing/replacing HEPA filters.

To determine the airborne concentration of radioactivity to which individuals may be exposed, we would take a breathing zone air sample.

An atmosphere that poses an immediate threat of severe exposure to contaminants which are likely to have adverse cumulative or delayed effects on health, is an IDLH atmosphere.

In a positive pressure air purifying respirator, contaminated air passes through the filter by means of a blower driven by a battery.

Air sampling is a monitoring method for assessing internal exposure.

When a worker reports to the control point with lost dosimetry, you would not issue stop work authority.

The ratio of intensity measured by the detector (intensity of the primary beam and scatter radiation) to the calculated actual intensity is the buildup factor,

If you shield a beta source with a higher atomic number shielding material, you will create more X-rays. (Bremsstrahlung).

Atomic number is the number of protons.

Shielding material with a high atomic number attenuates radiation more effectively than a lower atomic number material because, more electrons are available for interactions.

The nucleus contains 99.9% of the mass of the atom and about 10-10 of the volume.

Radiation is not measured directly, but is measured instead by its effect on the detector walls or the material within the detector.

When compared to ion chambers, proportional counters and fission chambers, the Geiger-Mueller detectors are the most sensitive to low level gamma fields.

In a Geiger-Mueller detector, the photomultiplier tube converts and amplifies the electrons freed by ionization in the scintillation crystal to a larger light output.

Noble gasses may be removed from reactor coolant through the degasification process, or through degasifier.

Alpha air samples should be taken with a membrane filter.

Sloughing is not an elimination route for internal contamination.

X-radiation is when electromagnetic ionizing radiation emitted by an orbital electron as it moves from the L shell to the K shell.

A 2000 MW thermal PWR might be expected to produce 640 MW of electrical power. (2000 x .32 = 640)

The following are the latent effects of radiation exposure: Life shortening, Genetic mutations, Leukemia, but Leukopemia is not.

After an inelastic scattering process the excited nucleus will emit a gamma photon.

Radioactivity is the process by which the nucleus of unstable nuclides disintegrates with the resulting emission of nuclear radiation.

The critical organ for I-131 is the thyroid.

Chronic radiation exposures are those involving continuous or repeated exposures over a relatively long time interval.

Release of noble gases in light water power reactors is limited through the decay lines or tanks.

Gamma photons originate in the nucleus of an atom.

Inner pair of gloves is the last thing you remove when undressing.

Acute radiation exposures are involving relatively large doses in a short time.

Becquerel discovered radiation.

A GM detector is more sensitive but not more accurate.

Somatic effects refer to the individual that received the exposure.

A whole body counter is for measuring internal gamma emitters.

The primary responsibility for control of a workers exposure lies with the worker.

95Am-241 has 95 protons and 146 neutrons.

38Sr-90 decays by emission to Y. You would add 1 to the number of protons, so the scientific nomenclature of the daughter is 39Y-90

The number of orbital electrons is equal to the number of protons in electrically neutral atoms.

The electron has a negative electrostatic charge, and is equal in charge intensity to the proton. It's mass is 1/1838 that of a proton.

Atomic mass number is the sum of the number of protons and neutrons in the nucleus.

One atomic mass unit (AMU) is equal to 1/12 the mass of a carbon-12 nucleus.

Isotopic abundance is the amount of the isotope (percentage) present in a normal natural mixture of the element.

The purpose of any radiation protection program is the subsequent protection and dose assessment of plant personnel from the collective radiation, both atomic and nuclear in origin.

The unit for energy in nuclear reactions is the electron volt (ev), which is the amount of energy gained by an electron when accelerated through a potential difference of one volt.1 Mev is 1 x106 ev.

An atom of a Carbon-12 has six protons, and six neutrons .If a Carbon-12 atom and an alpha particle were fused together, and Oxygen-16 isotope would result.

A beta particle is an electron (1/1838 mass of a proton) emitted from the nucleus of a radioactive isotope.

The decay constant and the half-life are constants for a given radionuclide.

The effective half-life formula is Teff = (TR x TB) / (TR + TB).The result will always be shorter than the shortest half-life.

X-ray radiation refers to electromagnetic waves associated with electronic energy transition.

During photoelectric effect, a gamma photon gives up all of its energy to orbital electrons.

The photon (gamma) interaction where a portion of the photons kinetic energy is transferred to an atom's orbital electron is called Compton scattering.

The minimum energy photon in theory for a pair production is 1.022 Mev, however, this type of interaction in not observed for photons having energies less than about 2.5 Mev.

Elastic scattering slows down neutrons because it causes a neutron to lose kinetic energy without exciting the target nucleus.

Internal contamination is a problem for two reasons: It increases the probability of damage to vital organs and it may be retained by the body for long periods of time.

Collection of body excrements is a method of assessing internal contamination.

In-vivo or whole body counting, determines the amount of a radionuclide deposited in an individual by liquid or solid crystal scintillation detectors.

Three sources of reactor coolant radioactivity would be fuel cladding impurities, system corrosion, and impurity introduction.

Activation products are a source of radioactive contamination.

fission products area major factor in power plant radiation source production.

Uranium fuel cladding is more likely source of fission products in reactor coolant systems than alpha and gamma interaction, plutonium-239 in a fuel rod/pin, or tritium in a high neutron flux environment.

Particulates may be removed from reactor coolant through filtration and ion-exchange in the purification system.

In an air purifying respirator, the contaminant is captured in a fibrous medium, usually fiberglass, sometimes cellulose, and mechanically filtered out of breathing air.

The positive pressure air purifying respirator has specifically designed filters called sorbents which through a process called absorption allow the sorbent to absorb iodine.

A positive pressure air purifying respirator has a protection factor of 1000.

A negative pressure full face respirator has a protection factor of 50.

In a gas filled detector, radiation ionizes the fill gas releasing electrons that are attracted to the positively charged anode and measured by the electrical circuitry.

A good thermal neutron absorber used in the portable detectors is cadmium.

The neutron interaction used in portable survey instrumentation is neutron capture with the emission of a charged particle.

In general, scintillation detectors are more sensitive then gas-filled detectors and are often used for counting measurements in laboratories.

Scintillation detectors are more sensitive then gas-filled detectors for gamma radiation because they contain material with a higher density for gamma's to interact.

In Germanium crystal detectors, the flow of free electrons towards the positive electrode and the apparent movement of holes toward the negative electrode create a current flow in the circuit.

Minimum detectable activity (MDA) is the minimum activity present in a sample that may be detected by a particular instrument.

A TLD characteristic that applies to the method used to asses a radworker's dose from beta radiation is shielding designed into TLD that allows beta dose to be determined by computation.

Beta shielding is better accomplished by aluminum than lead due to the production of Bremsstrahlung radiation.

The actual decrease in the intensity of a beam of gamma rays passing through a wall is less than the theoretical decrease because some gamma interactions result in other gamma rays of lower energy being given off, this is called buildup.

An RWP is designed to specify radiation safety and control requirements in areas where a significant exposure to personnel is possible. It also provides an exposure recording system and a system for recording sources, job types and functions where personnel exposures occur.

Valid reasons to perform a radiological survey are: provide information for RWP's, give current radiological data, and document compliance with regulations.

Any contamination greater than one thousand disintegrations per minute per 100 square centimeters would be expressed as >1000dpm/100cm2

The following checks are made on a survey instrument prior to use: check the instrument for date calibrated, proper battery condition, and a response check.

An ion chamber survey instrument is used to ascertain the amount of exposure personnel would receive as it accounts for all the ionization events occurring.

For airborne particulate sampling, some type of physical filter such as paper, fiberglass, or cellulose is used. Particulate filters should not have a high saturation factor.

Airborne samples of vapors are collected on activated charcoal, silica gel cartridges, or cryogenic traps.

Breathing zone air samples are the preferred method for sampling the workers exposure to airborne contamination.

When compared to opening a waste gas tank with a negative pressure purge on the tank, cleanup of radioactive sludge oil spill with an absorbent, and pumping a containment sump, removal of HEPA filters from a ventilation unit has the greatest potential for creating an airborne activity area.

Minute by minute update on exposure is not an error or problem in relating TLD readings to the actual dose received by the body.

The shielding half value thickness for 1 Mev gamma of: lead is 0.5 inches, concrete is 4 inches, and water is 8 inches.

The shielding tenth value thickness for 1 Mev gamma of: lead is 1.5 inches, concrete is 12 inches, and water is 24 inches.

The shielding half value thickness for 6 Mev gamma of: lead is 0.7 inches, steel/iron is 1.3 inches, concrete is 8 inches, and water is 16 inches.

The shielding tenth value thickness for 6 Mev gamma of: lead is 2 inches, steel/iron is 4 inches, concrete is 24 inches, and water is 48 inches.

For lines and equipment containing reactor water, or primary steam with hold-up times of less than five minutes, you would use 6 Mev gamma 1/10 shielding ( lead 2", water 48")

After an inelastic scattering process, the excited nucleus will emit a gamma photon.

The new 10 CFR 20 is based on ICRP #26.

A TLD's disadvantage is that it is expensive to use.

CAM's are susceptible to dust loading of the filter media.

You have to monitor individuals at 10% of the federal limits.

Letdown filters is how you remove corrosion products from reactor coolant system.

Charcoal filters or silver Zellite filters are used to sample for iodine. Silver Zellite are expensive and will absorb water or humidity.

Incorrect volumes are the most common source of air sample errors.

A Curie is 3.7E10 dps or 2.22E12 dpm.

Bremsstrahlung radiation is originated by a high energy beta particle as it accelerates near a heavy nucleus. (wording changed from decelerates, as when I last took the test, they changed the wording to accelerates)

Ionizing radiation interacts with the orbital electrons of an atom and creates two particles of opposite charge, these particles are called ion pairs.

In the Geiger-Mueller detector the output pulse is approximately independent of the type and energy of the radiation entering the detector.

Dose limit for the extremities as per 10 CFR 20 is 50 rem/yr.

A radiation area is posted at 5 mr/hr @ 30 cm.

An individual must be supplied with a personnel monitoring device if entering the restricted area and will receive or is likely to receive an exposure in excess of 10% of the limit.

Rem/mRem is the unit of measure for internal exposure.

It is important to add moderating materials to shield for a fast neutron source since the absorption cross section for most elements increases as the velocity or energy of the neutron decreases.

A neutron is absorbed and a gamma is released, is the best description of the method of inelastic scattering pertaining to neutrons.

A 7 Mev Alpha particle travels in air 2 inches.

Linear attenuation coefficient describes the number of interactions per unit length.

When entering a high radiation area, you need personnel monitoring devices.

A major change in dose limits between the old and revised 1- CFR 20 is that the old limits are based on calendar quarter time period and the revised limits are based on an annual time period.

The revised 10 CFR 20 specifies that radiation levels be measured at 30 cm.

The annual PSE limit for TEDE is 5 Rem.

The NRC must be notified prior to any PSE.

DDE, deep dose equivalent, is dose to the whole body from 'external' radiation exposure.

WF, weighting factor, is the equivalent whole body exposure from exposure of all organs due to radioactive material intake.

CEDE equates risk from organ to risk from whole body dose.

TEDE, total effective dose equivalent, is the sum of all internal and external dose.

Paraffin is used to attenuate fast neutrons.

Surface medium for scintillators, alpha is zinc sulfide, beta is anthracene, and gamma is sodium iodine thallium.

A minor will be allowed 10% of an adults limit per year.

Black lettering is now ok for Radiation signs.