Environmental Monitoring Programs and Equipment

Question 1

What are the purposes of environmental monitoring?

Answer 1

1. Measure and/or reconstruct (estimate) human population doses
2. Determine radiological impact of a facility
3. Detect and quantify accidental off-site radionuclide releases
4. Meet specific license requirements
5. Obtain pathway data to refine models
6. Study air and water mixing patterns

Question 2

Define

Pathway

(Environmental Monitoring)

Answer 2

Any route that radioactivity can follow in passing from a licensed facility to a person in the general population.

Question 3

Define

Critical pathway

(Environmental Monitoring)

Answer 3

The route taken by a critical nuclide from point of release to body entry.

Question 4

Compare and Contrast

Preoperational vs. and Postoperational Monitoring Programs

Answer 4

Preoperational Monitoring Program

• Put in place prior to the use of radioactivity at the site, and typically run for one year.
• Comprehensiveness ⇒ Determines a baseline analysis of environmental radioactivity over any possible areas of concern.

Postoperational Monitoring Program

• Sensitivity ⇒ Corresponds to a concentration of 1% to 10% of the applicable limits set for by federal or state radiation protection standards.
• Selectivity ⇒ Ability to select the radionuclide out of background.

Question 5

Define

Critical nuclide

(Environmental Monitoring)

Answer 5

Those nuclei which cause the largest dose contribution to the actual population at risk near the facility.

Question 6

What are the objectives of a preoperational monitoring program?

Answer 6

1. Locate radiation anomalies
2. Document ambient levels
3. Identify critical nuclides and pathways
4. Document seasonal meteorology patterns

Question 7

What questions are to be answered by a preoperational monitoring program?

Answer 7

1. What radioisotopes should be measured?
2. Where should the samplers be located?
3. How often should a sample be collected?
4. Which equation is used to calculate population dose?

Question 8

What is this plume pattern?

Answer 8

Looping

Question 9

What is this plume pattern?

Answer 9

Coning

Question 10

What is this plume pattern?

Answer 10

Fanning

Question 11

What is this plume pattern?

Answer 11

Lofting

Question 12

What is this plume pattern?

Answer 12

Fumigation

Question 13

What are two practical techniques to overcome radon interference in environmental alpha monitors?

Answer 13

1. Introduce a delay time between sample collection and counting to account for the short half-life of radon and its daughters.
2. Use a detector such as a surface barrier diodide which have excellent energy resolution. Then use a single channel pulse height analyzer to eliminate the interference of the alphas particular to radon.

Question 14

What questions need to be addressed in setting up a program to monitor the environmental levels of radioactivity?

Answer 14

1. Which isotopes?
2. Collection frequency?
3. Sampling location?
4. Sample preparation?
5. Sampling medium?
6. Counting equipment?
7. Sample size?
8. Calculational model?

Question 15

How are environmental levels of external gamma radiation (“direct radiation”) measured?

Answer 15

• Using thermoluminescent dosimeters.
• Calcium fluoride and calcium sulphate TLDs are commonly used which can measure doses below 1 mrem per month.

Question 16

What is a good TLD for environemental monitoring that represents human tissue?

Answer 16

• Use a carbon-doped aluminum oxide (Al₂O₃:C) phosphor which has an effective atomic number of 10.2. This is much closer to 7.5 than calcium phosphors.
• It has maximum fading of 10% in three months at extreme environmental temperatures, with no fading at room temperature for up to 9 months.
• Minimum detectable dose is 0.1 mrem.

Question 17

How do you measure real time “direct exposure” gamma radiation?

Answer 17

• Use a pressurized ion chamber.
• Fill gas is pressurized to 600 psi with argon gas.
• The extra loading of gas molecules makes the chamber more sensitive.
• It can then detect a gamma ray background of as little as 1 mrem per year.
• This is good for plume detection.

Question 18

What are some techniques and examples for monitoring airborne particulates?

Answer 18

• Sedimentation (Flypaper)
• Inertial Separation (Cascade Impactor)
• Filtration (High Volume Sampler)
• Electrostasis (Precipitator)

Question 19

What are two factors to consider in operating a filter sampler?

Answer 19

1. The accumulation of nonradioactive material on the filter element as time passes (dust loading). Problem in dusty environments.
2. Change in efficiency of a filter matrix as the airflow velocity changes.

Question 20

Graph

Collection Efficiency vs. Incoming Particle Velocity

(in reference to Air Filter Sampler for Environmental Monitoring)

Answer 20

Question 21

Define

Stack sampling

Answer 21

• Sampling of particulates in a moving air stream.
• A stack is a vent pipe or duct carrying a stream of air molecules and particulates, possibly for release into the enviornment.
• If the particulates can possibly be radioactive their concentration must be measured before release.

Question 22

Why would a stack monitor have a logarithmic readout?

Answer 22

• To allow coverage of levels from below background to disaster concentrations without range switching.
• A 30-day strip chart recorder gives a continuious record and makes it possible to calculate the amount of radioactivity released during any kind of evolution.

Question 23

What are three considerations for a stack sampling?

Answer 23

1. Type of nozzle
2. The placement of the nozzle in the air stream
3. The transport of the particulates to your collection point.

Question 24

What design criteria must the nozzle meet?

(in reference to Stack Sampling)

Answer 24

• The nozzle must be designed to meet the conditions of isokinetic sampling.
• These conditions are met if the velocity of the air steam entering the nozzle is exactly equal to the velocity in the duct at the sampling point.

Question 25

_Define_ Adsorption vs. Absorption

Answer 25

* _Adsorption_ is the process in which atoms, ions, or molecules from a substance (it could be gas, liquid or dissolved solid) adhere to a surface of the adsorbent. * _Absorption_ is the process in which a fluid is dissolved by a liquid or a solid (absorbent).

Question 26

What are some air sampling techniques for gases and examples?

Answer 26

* Continuous Flow (Stack Monitor) * Grab Sample (Lucas Cell) * Adsorption (Charcoal Canister) * Condensation (Tritium Monitor)

Question 27

How is a DAC value generated?

Answer 27

DAC (μCi mL^-1) = ALI (μCi) ÷ 2.4 x 10⁹ mL * 2.4 x 10⁹ mL is derived from the total volume of air (2,400 m³) breathed during a 2000 hour work year.

Question 28

_Define_ Derived Air Concentration (DAC)

Answer 28

* If the air concentration is exactly equal to the DAC for one year, a worker will just reach the legal intake of radioactivity, one ALI, on December 31st. * A worker not receiving any other radiation doses except by inhalation would be allowed a cumulative exposure of 2,000 DAC-hours in one working year.

Question 29

What is an inexpensive method for screening houses for radon levels?

Answer 29

* A charcoal canister (3" in diameter and 1" high). * A hole in the lid is covered by a "diffusion barrier" to increase the average sampling time, and holds about 25 grams of activated charcoal. * Over the course of several days' exposure, radon gas diffuses into the canister and adsorbs onto the charcoal. * At the end of the exposure period, the canister is resealed and mailed back to an analytical lab for counting.

Question 30

What are the alpha emissions from the ²²²Rn decay chain?

Answer 30

²²²Rn → ²¹⁸Po ²¹⁸Po → ²¹⁴Pb // ²¹⁴Pb → ²¹⁴Bi → ²¹⁴Po (beta decay) ²¹⁴Po → ²¹⁰Pb // ²¹⁰Pb → ²¹⁰Bi → ²¹⁰Po (beta decay) ²¹⁰Po → ²⁰⁶Pb (stable)

Question 31

_Define_ Working level

Answer 31

* Any combination of short-lived radon daughters in one liter of air that will result in the emission of 1.3 x 10⁵ MeV of potential alpha energy. * If radon gas was present at a concentration of 100 pCi L^-1, and if the daughter products were all in equilibrium, then the decay through the first 4 daughters would release exactly 1.3 x 10⁵ MeV of alpha particle energy. * The DAC for Rn-222 is 1/3 the working level.

Question 32

How does an electret chamber work when measuring for radon?

Answer 32

* An electret is a material that can hold a permanent electrostatic charge. * A teflon disk holds a charge through both humidity and temperature changes. * Radon diffuses into a chamber containing the electret and the ionization caused by the radon gas decays and cancels some of the electrostatic charge on the positively charged electret. * The surface voltage of the electret is measured before and after radon exposure. * The voltage drop reveals the average radon concentration. * Can be reused (cost is low) and insensitive to humidity and temperature.

Question 33

_NRC Regulatory Guide 1.97_ What 3 levels of radioiondine monitoring are required?

Answer 33

1. Reactor plant ⇒ The inplant air must be sampled during normal operations. 2. Environmental ⇒ The environs outside the plant must be sampled periodicially. 3. Accident monitoring ⇒ The plant must have special high range instruments available for post-accident monitoring.

Question 34

How is routine monitoring accomplished for radioiodine?

Answer 34

* Sucking air through a collection medium with a high or low volume sampler. * The collection medium is activated charcoal or silver impregnated zeolite. * Charcoal cartidges are several times cheaper.

Question 35

_NRC Regulatory Guide 1.97_ Monitoring equipment must be able to detect radioiodine in what range?

Answer 35

10^-9 to 10^-3 µCi cm^-3

Question 36

How do you accomplish tritium air sampling?

Answer 36

* Suck ambient air through an ioniziation chamber. * Due to the very low energy of the tritium betas, a very sensitive electrometer circuit must be used to detect the tiny current produced inside the chamber by tritium decays.

Question 37

Which is a higher concern: tritiated water vapor or tritium gas?

Answer 37

* Tritiated water vapor * Tritiated water vapor can be absorbed easily through the skin while tritium gas produces no skin dose from the extremely weak betas emitted.

Question 38

What are two problems encountered in water sampling?

Answer 38

1. If the water has a high silt level (it's muddy), then the clay in the silt will act as an ion exchange medium and trap radioactivity when the water is passed through a filter to remove the silt. Dealt with by providing two results, filtered and non-filtered. 2. Need to assure that water sample is a representative sample that exists through a large body of water. Due to variations (e.g., temperature, depth), this can be addresssed by collection of multiple sample points.

Question 39

_Safe Drinking Water Act of 1974 (EPA)_ What are MCLs for alpha emitters?

Answer 39

* Uranium ⇒ 30 μg L^-1 * ²²⁶Ra / ²²⁸Ra ⇒ 5 pCi L^-1 * Adjusted gross alpha activity ⇒ 15 pCi L^-1 // Excluding radon and U

Question 40

_Safe Drinking Water Act of 1974 (EPA)_ What are MCLs for beta/gamma emitters?

Answer 40

Established by limiting the annual effective dose equivalent to 4 mrem yr^-1 for the total body or any single organ.

Question 41

Why is milk sampled for radioactivity for environmental monitoring?

Answer 41

* Grass is an excellent collection medium for the fallout of fission products. * Radioactivity can be seen after the grass is processed and fission products are passed to the milk.

Question 42

_Define_ Working level month

Answer 42

* An exposure to 1 working level for 170 hours. * 2,000 working hours per year over 12 months per year equals 170 hours per month.

Question 43

What is the occupational limit for radon exposure in the United States?

Answer 43

* 4 WLM year^-1 * One working level-month produces about one rem CEDE.

Question 44

_Describe_ Unattached fraction

Answer 44

* Used by the EPA to estimate the amount of actual radon progeny present. * Also called the "equilibrium factor" * Typical value ⇒ 0.5

Question 45

Radon gas can be found in which naturally occurring decay chains?

Answer 45

All of them * Actinium (Rn-219) * Thorium (Rn-220) * Uranium (Rn-222)

Question 46

Where do radon daughters inhaled during uranium mining normally deposit?

Answer 46

The lungs

Question 47

What is the suggested action level for Radon concentrations in homes?

Answer 47

4 pCi L^-1

Question 48

What report is titled BEIR VI 1999?

Answer 48

"The Health Effects of Exposure to Indoor Radon"

Question 49

Is the oxygen effect significant with radon exposure? Why or why not?

Answer 49

* The effect is not significant for radon exposure because alpha radiation released from radon is high-LET radiation. * The oxygen effect describes the enhanced biological damage that occurs in the cells when dissolved oxygen is present as a result of the formation of long-lived free radicals. * This is more significant in low-LET radiation events as they are likely to produce more free-radicals.

Question 50

What is the best estimate for absorbed dose to the lungs from exposure to radon progeny?

Answer 50

500 mrad WLM^-1

Question 51

List two important radon and radon progeny aerosol properties.

Answer 51

1. Radon is a chemically inert gas, so it is primarily exhaled when taken into the lungs while breathing. 2. Progeny exist as solid aerosol particles comprised of ions, atoms, and atoms attached to condensation nuclei. This affects their diffusion and deposition on various surfaces of respiratory tract when inhaled.

Question 52

List three important physiological characteristics of the respiratory tract.

Answer 52

1. Thickness of mucous sheet. 2. Action of the cilia on the flow of the mucous sheet in clearing particles. 3. Thickness and mass of critical target tissue (e.g., basal cells of the bronchial epithelium).

Question 53

What is a grab sample? Give an example of a grab measurement for both radon and radon progeny.

Answer 53

Measurements of a radon sample are taken over a relatively short period of time. * Radon ⇒ Concentration in air is collected in a ZnS(Ag) scintillation cell. * Radon progeny ⇒ Determined by 3 separate counts of a 5-minute air filter sample (short half-life).

Question 54

What is an integrated radon sample? Give an example of an integrated measurement for both radon and radon progeny.

Answer 54

Integrated measurements are proportional to the integrated exposure from radon and radon progeny. * Radon ⇒ Exposure is determined by the measurement of alpha tracks in a plastic detector. * Radon progeny ⇒ From integrated TLD response from radiation emitted by progeny collected on a filter paper in a continuous air sampler.

Question 55

What is a continuous radon sample? Give an example of a continuous sample for both radon and radon progeny.

Answer 55

A continuous measurement is related to the instantaneous concentrations, or the short-term average concentrations over an extended monitoring period. * Radon ⇒ Concentration of sampled air that continuously passes through a ZnS(Ag) scintillation cell. * Radon progeny ⇒ Alpha counts of a filter in a constant air particulate monitor.

Question 56

List three reasons apparent releases may end up considerably less than expected

Answer 56

* Condensation of radionuclide and subsequent chemical reactions on surfaces including duct work and the stack itself. * Building ventilation is likely to be filtered. * Chemical reaction with radionuclide with constituents in the air and formation of particles that settle to surfaces especially if the mean residence time is long.

Question 57

_Assume a release through a pipe to the bottom and in the middle of a wide, shallow, straight river_ What is the effect on liquid radioactivity concentration if the temperature of the discharge is increase?

Answer 57

Centerline concentration is expected to increase as the temperature of the discharge is increased because the density of the discharged water is less.

Question 58

_Assume a release through a pipe to the bottom and in the middle of a wide, shallow, straight river_ What is the effect on liquid radioactivity concentration from an increased velocity of the discharge?

Answer 58

If release rate Q (Ci sec^-1) increases with increased velocity of discharge, assuming the released concentration does not change, the concentration everywhere in the river will increase.

Question 59

_Assume a release through a pipe to the bottom and in the middle of a wide, shallow, straight river_ What is the effect on the liquid radioactivity concentration from an increase in the river current?

Answer 59

If the river current F (m³ sec^-1) increases, then average concentration C in the river will decrease.

Question 60

_Assume a release through a pipe to the bottom and in the middle of a wide, shallow, straight river_ What effect does time have on the concentration of radioactive material in the sediment on the river bottom?

Answer 60

As time (t) increases, the activity concentration C(t) in sediment on the river bottom will decrease with depth in the sediment if the activity release rate Q and sedimentation rate do not change with time.

Question 61

List five ways to improve the dose estimate for off-site individuals exposed to airborne concentrations of ²³⁹Pu.

Answer 61

* Determine particle size distribution and AMAD of collected ²³⁹Pu aerosol particles on the filter. * Correct for the actual AMAD. * Correcting the calculated respiratory tract deposition for the actual AMAD. * Determine the inhalation compound classes for ²³⁹Pu aerosol particles and take into account when revising. * Collecting and analyzing deposited plutonium aerosol particles at various downwind locations and take this information into account for number 1-4.

Question 62

List five ways to reduce the potential long term dose to individuals from brush fires or other high re-suspension events.

Answer 62

* Defoliation agents ⇒ Limit the amount of brush on top of contaminated lands. * Fire breaks ⇒ Separates contaminated from clean land areas that have a significant amount of brush/fire potential. * Decontamination ⇒ Remove contamination from areas where the potential exists for a re-suspension of radioactive materials. * Shelter-in-Place ⇒ Early warning of individuals in downwind locations to shelter themselves and close ventilation (if appropriate for exposure levels). * Evacuation ⇒ Early warning of individuals in downwind locations to evacuate area (if appropriate for exposure levels).

Question 63

List four sources of uncertainty in the application of the results from epidemiological studies of populations of underground miners to health effects in the general population.

Answer 63

* Miners were heavy smokers and their data may overestimate the risk to non-smokers (especially if radon & smoke act synergistically) * Miners may have been exposed to other carcinogens (e.g., diesel smoke) not normally present in the home * The unattached radon progeny cause most of the dose to the bronchial epithelium. The fraction of progeny unattached to condensation nuclei and other aerosol particles in a mine differ from that in a home. * The breathing pattern of miners differs from that of occupants of homes.

Question 64

List four sources of uncertainty when using the respiratory tract as applied to risk estimates from radon exposures

Answer 64

* Unattached fraction ⇒ Fraction of radon progeny unattached to condensation nuclei and other aerosol particles can greatly alter the deposition and dose to the critical bronchial epithelium tissue. * Mucous sheet ⇒ Thickness can greatly influence the dose to the underlying basal cells. Consequently, thickness varies from smoker to non-smoker and the degree of any respiratory disease present. * Breathing pattern ⇒ The deposition of radon progeny in various regions of the respiratory tract can vary with breathing pattern (e.g., nose vs. mouth breathing). * Clearance rate ⇒ The clearance rate of deposited radon progeny aerosols may vary considerably from individual to individual or default values to those in dosimetric model.

Question 65

List four methods to reduce the radon entry into a home or building

Answer 65

* Seal cracks in foundation. * Ventilate crawl spaces with outdoor air. * Maintain a positive pressure in the basement relative to that of soil/gas (use outdoor air for combustion of fuel). * Strip high levels of radon from well water or absorb radon on charcoal filters before well water is used in the house.

Question 66

What is the reduction in concentration ("transfer factor") of radon in water (pCi L^-1) to the indoor air concentration (pCi L^-1)?

Answer 66

10000 : 1

Question 67

_Define_ Derived Concentration Guidance Level

Answer 67

* Action level based on a specific release criterion, exposure pathway, and measurement * A predicted or measured concentration of a contaminant that would cause a dose or risk equal to the release criterion for a specific exposure pathway * DCGLs are based on possible exposure pathways, therefore the planned use or reuse of structures does affect the determination of DCGLs

Question 68

List four factors that must be considered in converting field instrument reading to a specific DCGL

Answer 68

* Detector background counting rate * Scanning speed and geometry * Detector intrinsic gamma detection efficiency * The effect of photon absorption and scatter in soils

Question 69

Describe five pathways by which radioactivity in soil can contribute to human dose.

Answer 69

* Direct terrestrial exposure to penetrating radiations. * Transfer of radioactivity from soil to water and subsequent ingestion of water. * Transfer of radioactivity to air by evaporation, emanation, or other physical airborne entrainment, with subsequent inhalation of radioactive aerosols. * Absorption of radioactivity from soil by plants and subsequent ingestion. * Transfer of radioactivity to grazing livestock and subsequent ingestion of milk and other animal byproducts.

Question 70

What are two parameters that are important to know when conducting a dose assessment from contaminated soil?

Answer 70

* Specific activity of the soil, which determines the mass of suspended soil per unit volume of air that is required to reach a given airborne concentration. * AMAD and geometric standard deviation of the suspended soil particles, which influence their respiration, deposition, and clearance from compartments within the respiratory tract.

Question 71

What does trace A represent?

Answer 71

A short term “puff” release of a long-lived radionuclide with no additional releases during the sampling period.

Question 72

What does trace C represent?

Answer 72

The presence of an exponentially increasing concentration of a long-lived radionuclide.

Question 73

What does trace D represent?

Answer 73

The presence of a nuclide with a half-life of approximately 20 minutes.

Question 74

List 3 potential sources of radon in a home

Answer 74

* Radon in soil gas from an open sump * Unfinished basement, radon in soil gas enters through various pathways (e.g., cracks in the floor) * Radon in well water escapes into air when water is used in the home

Question 75

List two radon remediation techniques for an open sump in a home’s basement

Answer 75

* Fill and cap sump hole if not needed * Cap sump and connect pipe to cap that fans to outside the house ⇒ This maintains a negative pressure in the sump and under the basement floor

Question 76

List two radon remediation techniques for soil gas emanating from an unfinished basement

Answer 76

* Seal all pathways with plastic sealant * Put in a subfloor suction system to create a negative pressure

Question 77

List two radon remediation techniques for well water

Answer 77

* Use aeration system on water intake line, which will strip radon from water * Place activated charcoal in intake line to absorb radon

Question 78

_Define_ Unattached fraction

Answer 78

The fraction of any given radon progeny unattached to condensation nuclei in the air and existing as free atoms or ions, which have a much higher diffusion coefficient than the attached species.

Question 79

The figure represents the variation of mean dose to the tracheobronchial region of the lung with percent unattached fraction. Explain the reason for the increase in dose with the percent increase in unattached fraction.

Answer 79

* These free atoms and ions quickly diffuse and deposit on walls of the tracheobronchi where they decay and deliver most of the dose. * The activity of the inhaled air that deposits by diffusion deposition on the bronchial epithelium is essentially independent of breathing rate. * Therefore, for a fixed unattached fraction, the total dose is directly proportional to the total radon progeny exposure in WLM.

Question 80

_Define_ Isokinetic sampling

Answer 80

* Vent, stack, or duct is used to assure that a representative sample of contaminant aerosols is collected. * This is achieved when the velocity of air entering the sample probe (v_S) is the same as the velocity of the exhaust gases (v_E) at the sampling location in the exhaust.

Question 81

When do anisokinetic conditions exist?

Answer 81

When the velocity of air entering the sample probe (v_S) does not equal the velocity of the exhaust gases (v_E) v_S ≠ v_E

Question 82

What effect do sampling conditions (i.e., v_S compared to v_E) have on the size of collected sample particles?

Answer 82

* v_S \> v_E ⇒ The sample will have a deficit of larger particles. * v_S \< v_E ⇒ The sample will have an excess of larger particles.

Question 83

List five factors that lead to sample line losses.

Answer 83

* Diffusion deposition ⇒ Particles diffuse and deposit on the walls of the sampling system. * Chemical reaction ⇒ Contaminant aerosols (e.g., radioiodine) react chemically with walls. * Piping bends ⇒ Impaction of particles at bends in the sampling lines. * Condensation ⇒ Contaminants condense on walls. * Electrostatic attraction ⇒ Contaminant ions are electrically attracted to charged wall surfaces.

Question 84

If copper tubing is used for the sampling line in an air-sampling system, what effect would radioiodine have on the system?

Answer 84

Radioiodine would react chemically with copper.

Question 85

What additional information would you request in order to confirm a release scenario and reduce the uncertainty in the release estimate?

Answer 85

Request stack monitoring data for * Analyses of stack filter samples * Stack gas exhaust flow rate

Question 86

List five tasks that should be routinely perform to assure the quality of a counting system

Answer 86

* Electronics ⇒ Check integrity of all electronics prior to use * χ2 test with a standard ⇒ in a fixed position to evaluate counter operation. * χ2 test without a standard ⇒ Placed in a pre-determined specific position for each count to determine the extra Poisson variance associated with the sample changer. * Background count of a blank ⇒ Conduct before each sample count and plot on a control chart. * Standard source check ⇒ Confirms counting efficiency and plot of counting data on a control chart.

Question 87

Describe one type of hand-held instrument routinely used for detection of uranium contamination on personnel as they leave contaminated areas. Include advantages and disadvantages

Answer 87

Thin window (2 mg cm^-2) pancake type GM detector and rate meter. _Advantage_ * Low cost * Durability * Sensitive to the α/β radiation associated with the decay of uranium & progeny _Disadvantage_ * Relatively high background * Window can easily be punctured/damaged * Lack of α/β/γ discrimination prevents use when checking for α-emitting contamination in external radiation fields.

Question 88

List two important Rn/Rn progeny aerosol properties

Answer 88

* Radon is a chemically inert gas, so it is primarily exhaled when taken into the lungs while breathing. * Progeny exist as solid aerosol particles comprised of ions, atoms, and atoms attached to condensation nuclei. These properties affect their diffusion and deposition on various surfaces of the respiratory tract when inhaled.

Question 89

List three important physiological characteristics of the respiratory tract

Answer 89

* Mucous sheet ⇒ Thickness of mucous sheet * Cilia ⇒ Affects the flow of particles on the mucous sheet in clearing particles. * Critical target tissue ⇒ Thickness and mass of critical target tissue (e.g., basal cells of the bronchial epithelium)

Question 90

# _Define and State an Example_ Grab sample

Answer 90

A measurement of a sample taken over a short period of time. _Examples_ * Radon concentration in air collected in a ZnS(Ag) scintillation cell. * Short-lived radon progeny concentration from 3 counts of a 5-minute air sample.

Question 91

# _Define and State an Example_ Integrated sample

Answer 91

A measurement proportional to the integrated exposure _Examples_ * Radon exposure from alpha tracks in a plastic detector exposed over a period of time. * Radon progeny exposure from integrated TLD response to radiation emitted by radon progeny collected on filter paper in a continuous air sampler

Question 92

# _Define and State an Example_ Continuous sample

Answer 92

A measurement that can be related to the instantaneous concentration (short term average concentration) over an extended monitoring period _Examples_ * Radon concentration of sampled air that continuously passes through a ZnS(Ag) scintillation cell * Radon progeny from alpha counts of a filter in a constant air particulate monitor