**2.1.1 Direct effluent sampling**

Once the sampling location has been identified and qualified, attention to the sample system design is necessary. A typical stack effluent sampling system includes an in-line sample probe within the stack/vent, a sample transport line to the sample media (e.g., filter paper or cartridge), a rotameter, and vacuum gauge with feedback controls. The sample collection and transport are affected by the nozzle design, performance, and specific sampling use (e.g., particulates, gases/vapors). For reporting purposes, the bulk stream flow through the emission point is also required.

During the sampling process, losses – particle losses in particular – should be minimized. The most effective way to accomplish this is to limit the number of bends and horizontal sections of the sample line and to minimize the total sample line length. For harsh sampling environments such as those containing corrosive gases and vapors, construction material should be resistant to degradation. Because some loss is inevitable, required maintenance activities such as inspection, cleaning, and testing can help maintain effective operations.

The collection media is equally important to obtaining a valid sample. Sampler filters are usually adequate for collecting particulate radioactive air media (Fig. 2). Commercial particulate filters are made of glass fiber, acrylic copolymer, or other robust material and vary in size from 25 mm to 20 cm in diameter. Other potentially necessary specialized

ISO 10780:1994. The average resultant flow angle

should be less than 20 degrees.

The coefficient of variance (COV) should not exceed 20% over the center region of the stack that encompasses at least 2/3 of the stack cross-sectional area.

The COV should not exceed 20% over the center region of the stack that encompasses at least 2/3 of the stack cross-sectional area.

At no point on the measurement grid should the tracer gas

value by more than 30%.

concentration differ from the mean

The COV should not exceed 20% over the center region of the stack that encompasses at least 2/3 of the stack cross-sectional area.

**Characteristic Methodology Recommendations** 

Selection of points across a section based on the guidance in ISO 10780 for the center 2/3 of the area may be added to adequately

Selection of points across a section based on the guidance in ISO 10780 for the center 2/3 of the area of the stack or duct.

Additional points or area may be added to cover the region

Selection of points across a section based on the guidance in ISO 10780 for the entire cross-sectional

Selection of points across a section based on the guidance in ISO 10780. Additional points or area may be added to cover the region

Table 2. Summary of recommendations for a stack sampling location (ISO 2889:2010)

Once the sampling location has been identified and qualified, attention to the sample system design is necessary. A typical stack effluent sampling system includes an in-line sample probe within the stack/vent, a sample transport line to the sample media (e.g., filter paper or cartridge), a rotameter, and vacuum gauge with feedback controls. The sample collection and transport are affected by the nozzle design, performance, and specific sampling use (e.g., particulates, gases/vapors). For reporting purposes, the bulk stream flow through the

During the sampling process, losses – particle losses in particular – should be minimized. The most effective way to accomplish this is to limit the number of bends and horizontal sections of the sample line and to minimize the total sample line length. For harsh sampling environments such as those containing corrosive gases and vapors, construction material should be resistant to degradation. Because some loss is inevitable, required maintenance activities such as inspection, cleaning, and testing can help maintain effective operations. The collection media is equally important to obtaining a valid sample. Sampler filters are usually adequate for collecting particulate radioactive air media (Fig. 2). Commercial particulate filters are made of glass fiber, acrylic copolymer, or other robust material and vary in size from 25 mm to 20 cm in diameter. Other potentially necessary specialized

cover the region.

adequately.

adequately.

area.

Measurement to determine if flow in a stack or duct is

Velocity profile

Tracer gas concentration profiles

Maximum tracer gas concentration deviations

Aerosol particle concentration profile

**2.1.1 Direct effluent sampling** 

emission point is also required.

cyclonic

collection media include silica gel (Fig. 3) or molecular sieves for tritium collection, activated charcoal or silver zeolite cartridges for radioiodines, and bubblers for other gases. For collection media selection, detection criteria for the measurement of alpha, beta, and gamma radiation must also be established to meet lower limits of detection. The sample volume affects the criteria for detection limits, sample size, sampling frequency, and materials used.

Fig. 2. Fixed head radioactive air stack sampler with 47-mm diameter filter in place

Fig. 3. Silica gel columns in use for tritium sampling system; three columns are used for collecting water vapors, and then the dry gas goes through a catalyst to form the water vapor collected using the two columns (Barnett et al., 2004)

Concepts for Environmental Radioactive Air Sampling and Monitoring 269

The requirements of sampling at a well-mixed location apply equally to a stack CAM. However, additional maintenance, repair, and calibration are required for a CAM. Maintenance activities can include periodic checks of the system responses to inputs that generate alarms that verify normal operations. Repairs can include replacement of electronics, detectors, or other system components that wear out or become damaged. Finally, an annual calibration is required that covers all aspects of the CAM operations. Calibration activities would include background checks and measurements, source responses to reference standards of given radioisotopes, leak tests, electronics validations,

A CAM is particularly useful in laboratory work where releases are expected and can be observed and managed, either in normal or upset/accident conditions. For routine work, staff may observe a release to limit the overall activity or bound daily releases. In an upset condition, staff have a near real-time assessment of releases and potentially a second filter

The primary benefits of environmental surveillance for airborne radioactive material are that it identifies emissions from fugitive (and point) sources and provides detailed impacts to the public and the environment. When establishing a site monitoring program, utilization of a data quality objective (DQO) process is recommended, this determines the environmental monitoring needs for routine radiological air emissions to the atmosphere from the emissions/sources of the site in response to regulatory requirements. Assistance with preparing a DQO is available from *Guidance on Systematic Planning Using the Data Quality Objective Process* (EPA, 2006); additionally, the Pacific Northwest National Laboratory (PNNL) used the DQO process to establish three site monitoring locations

Besides a DQO, processes such as an implementation plan, sampling and analysis plan, a site environmental monitoring plan, and a data management plan complete a well-managed

Identifying and clearly stating the problem is the first step in the DQO process. This section discusses the background and scope, states the requirements, establishes the problem statement, and identifies the participants and schedule. Once the problem statement is firmly established, the goals of the DQO can be identified, usually a series of supportive

Assessing inputs and setting boundaries are the next steps in the DQO process. The inputs are used to answer the questions formulated from the goals; include information necessary to meet performance and acceptance criteria; and provide direction for the monitoring, sampling, and analysis methods. Additionally, the boundaries discuss the logistics of implementing the goals and objectives. To provide a viable monitoring program, all seven

questions and actions that specifically address the problem statement.

(Barnett et al., 2010). The development of the DQO includes the following aspects:

for future analysis to confirm releases and potential exposures.

**2.2 Airborne radioactive material environmental surveillance** 

and alarm responses.

1. Stating the problem 2. Establishing goals 3. Assessing inputs 4. Setting boundaries

monitoring program.

5. Establishing decision rules 6. Evaluating decision errors 7. Optimizing the results

aspects of a DQO must be considered.

Optimization of the sampling system is the final component of the program development. Balancing the effects and requirements along with a graded approach will generally result in an adequate sample. These considerations are also germane to environmental surveillance sample collection stations and equipment.

#### **2.1.2 Direct effluent monitoring**

As identified in the graded approach of Table 1, continuous air monitoring may be required at a point source for real-time analysis and feedback. A continuous air monitor (CAM) provides timeliness in assessing the release of radionuclides to the environment. Fig. 4 shows a combination particulate and gas CAM. While the system specifications require the user to balance the sensitivity, energy response, response time, and accuracy, the CAM should also have alarm capabilities with established thresholds to alert the user to significant releases (DOE, 1991).

Fig. 4. Combination continuous air monitor for particulates and gases

The requirements of sampling at a well-mixed location apply equally to a stack CAM. However, additional maintenance, repair, and calibration are required for a CAM. Maintenance activities can include periodic checks of the system responses to inputs that generate alarms that verify normal operations. Repairs can include replacement of electronics, detectors, or other system components that wear out or become damaged. Finally, an annual calibration is required that covers all aspects of the CAM operations. Calibration activities would include background checks and measurements, source responses to reference standards of given radioisotopes, leak tests, electronics validations, and alarm responses.

A CAM is particularly useful in laboratory work where releases are expected and can be observed and managed, either in normal or upset/accident conditions. For routine work, staff may observe a release to limit the overall activity or bound daily releases. In an upset condition, staff have a near real-time assessment of releases and potentially a second filter for future analysis to confirm releases and potential exposures.

### **2.2 Airborne radioactive material environmental surveillance**

The primary benefits of environmental surveillance for airborne radioactive material are that it identifies emissions from fugitive (and point) sources and provides detailed impacts to the public and the environment. When establishing a site monitoring program, utilization of a data quality objective (DQO) process is recommended, this determines the environmental monitoring needs for routine radiological air emissions to the atmosphere from the emissions/sources of the site in response to regulatory requirements. Assistance with preparing a DQO is available from *Guidance on Systematic Planning Using the Data Quality Objective Process* (EPA, 2006); additionally, the Pacific Northwest National Laboratory (PNNL) used the DQO process to establish three site monitoring locations (Barnett et al., 2010). The development of the DQO includes the following aspects:


268 Environmental Monitoring

Optimization of the sampling system is the final component of the program development. Balancing the effects and requirements along with a graded approach will generally result in an adequate sample. These considerations are also germane to environmental surveillance

As identified in the graded approach of Table 1, continuous air monitoring may be required at a point source for real-time analysis and feedback. A continuous air monitor (CAM) provides timeliness in assessing the release of radionuclides to the environment. Fig. 4 shows a combination particulate and gas CAM. While the system specifications require the user to balance the sensitivity, energy response, response time, and accuracy, the CAM should also have alarm capabilities with established thresholds to alert the user to

Fig. 4. Combination continuous air monitor for particulates and gases

sample collection stations and equipment.

**2.1.2 Direct effluent monitoring** 

significant releases (DOE, 1991).


Besides a DQO, processes such as an implementation plan, sampling and analysis plan, a site environmental monitoring plan, and a data management plan complete a well-managed monitoring program.

Identifying and clearly stating the problem is the first step in the DQO process. This section discusses the background and scope, states the requirements, establishes the problem statement, and identifies the participants and schedule. Once the problem statement is firmly established, the goals of the DQO can be identified, usually a series of supportive questions and actions that specifically address the problem statement.

Assessing inputs and setting boundaries are the next steps in the DQO process. The inputs are used to answer the questions formulated from the goals; include information necessary to meet performance and acceptance criteria; and provide direction for the monitoring, sampling, and analysis methods. Additionally, the boundaries discuss the logistics of implementing the goals and objectives. To provide a viable monitoring program, all seven aspects of a DQO must be considered.

Concepts for Environmental Radioactive Air Sampling and Monitoring 271

HTD radionuclides have a combination of properties that include a lengthy or very short half-life, low-energy (e.g., weak beta) emissions and detection difficulties, particularly with field instruments but also with laboratory instruments. HTD radionuclides include C-14, Fe-55, I-129, Ni-63, and Tc-99. In the environment, the assessment of HTD radionuclides relies on consideration of alternative approaches such as process knowledge, surrogate/ratio (scaling) measurements, and dose impacts. The overall importance of HTD radionuclides should not be underestimated because they may in fact make a significant

The HTD radionuclides are not easily detected because the radiation cannot penetrate outside of its sample matrix or the activity is too low and obscured by background, other radionuclides, or instrument noise. The costs to isolate and analyze for the HTD radionuclides may not be justified when the use of another more readily measurable radionuclide (e.g., Cs-137) can be used to scale the HTD radionuclide measurement. Establishing the scaling factor requires process knowledge about the other radioisotopes available for measurement and the relative quantities of the HTD radioisotopes to the known radioisotopes. Once these are determined, measurement of the HTD radionuclide

When facility emissions are very low (Potential Impact Category 4, Table 1), an administrative review of the releases to the environment may be used instead of the sampling and monitoring methods described above. This review may employ data logging of actual or estimated releases based on inventory. Emissions may also be conservatively

For gas emissions in particular, the use of data logging is practical and efficient. The facility tracks the known releases of radioactive materials to the environment, and this log becomes the official basis for reporting. In addition to data logging, tracking of a facility's radioactive material inventory can be used to estimate a calculated release (EPA, 1989). In this process, one determines the amount of radioactive material used for the period under consideration. Radioactive materials in sealed packages that remain unopened, and have not leaked during the period are not included. The amount used is multiplied by both a release fraction ([RF]; Table 3) and a decontamination factor ([DF]; Table 4 and Equation 1). If there is more than one abatement control device in series, then multiple DFs are applied. Therefore, it is

necessary to know the form of the radioactive material and any abatement controls.

Fig. 6. Air monitoring system schematic for radioactive particulates

**2.3 Considerations for assessing hard-to-detect radionuclides** 

contribution to the regulatory dose limit for the public or environment.

can proceed as a function of the better known and measured radioisotope.

**2.4 Estimating releases in lieu of analytical results** 

estimated when sampling or monitoring is inadequate.

In establishing and evaluating the decision rules and errors, goals and inputs are vital. The decision rules are the answers to questions posed during the goal-setting process, and they utilize the data inputs for the decisions that follow. Decision errors evaluate and discuss potentially incorrect decisions and determine the possible consequences.

The final step in setting up the monitoring program for a facility or site is optimization, which may include requirement compliance, using commercial off-the-shelf equipment, and implementing standard analytical methods. However, when optimized, the goal is to make the operations and systems work efficiently.

Commercial monitoring stations are readily available (Fig. 5), the weather-protected equipment is housed in a small metal portable or stationary cabinet consisting of a pump, flow totalizer, adjustable vacuum gauge, and other equipment and/or electronics as necessary (Fig. 6). The unit's power may be a hard-wired electrical outlet, batteries, or a renewal energy source such as an array of solar panels.

Depending on system and design needs, the filter/sample media may be either inside the monitoring cabinet or external to it. Basic filter papers (Fig. 2) can be fixed to a sample head on the exterior of the cabinet; cartridges (e.g., silver impregnated zeolite and/or activated carbon) can also be fixed to an exterior sample head. Other sample media such as the larger silica gel cartridges may need to be housed inside the cabinet.

Fig. 5. Environmental air monitoring station

In establishing and evaluating the decision rules and errors, goals and inputs are vital. The decision rules are the answers to questions posed during the goal-setting process, and they utilize the data inputs for the decisions that follow. Decision errors evaluate and discuss

The final step in setting up the monitoring program for a facility or site is optimization, which may include requirement compliance, using commercial off-the-shelf equipment, and implementing standard analytical methods. However, when optimized, the goal is to make

Commercial monitoring stations are readily available (Fig. 5), the weather-protected equipment is housed in a small metal portable or stationary cabinet consisting of a pump, flow totalizer, adjustable vacuum gauge, and other equipment and/or electronics as necessary (Fig. 6). The unit's power may be a hard-wired electrical outlet, batteries, or a

Depending on system and design needs, the filter/sample media may be either inside the monitoring cabinet or external to it. Basic filter papers (Fig. 2) can be fixed to a sample head on the exterior of the cabinet; cartridges (e.g., silver impregnated zeolite and/or activated carbon) can also be fixed to an exterior sample head. Other sample media such as the larger

potentially incorrect decisions and determine the possible consequences.

the operations and systems work efficiently.

Fig. 5. Environmental air monitoring station

renewal energy source such as an array of solar panels.

silica gel cartridges may need to be housed inside the cabinet.

Fig. 6. Air monitoring system schematic for radioactive particulates

#### **2.3 Considerations for assessing hard-to-detect radionuclides**

HTD radionuclides have a combination of properties that include a lengthy or very short half-life, low-energy (e.g., weak beta) emissions and detection difficulties, particularly with field instruments but also with laboratory instruments. HTD radionuclides include C-14, Fe-55, I-129, Ni-63, and Tc-99. In the environment, the assessment of HTD radionuclides relies on consideration of alternative approaches such as process knowledge, surrogate/ratio (scaling) measurements, and dose impacts. The overall importance of HTD radionuclides should not be underestimated because they may in fact make a significant contribution to the regulatory dose limit for the public or environment.

The HTD radionuclides are not easily detected because the radiation cannot penetrate outside of its sample matrix or the activity is too low and obscured by background, other radionuclides, or instrument noise. The costs to isolate and analyze for the HTD radionuclides may not be justified when the use of another more readily measurable radionuclide (e.g., Cs-137) can be used to scale the HTD radionuclide measurement. Establishing the scaling factor requires process knowledge about the other radioisotopes available for measurement and the relative quantities of the HTD radioisotopes to the known radioisotopes. Once these are determined, measurement of the HTD radionuclide can proceed as a function of the better known and measured radioisotope.

#### **2.4 Estimating releases in lieu of analytical results**

When facility emissions are very low (Potential Impact Category 4, Table 1), an administrative review of the releases to the environment may be used instead of the sampling and monitoring methods described above. This review may employ data logging of actual or estimated releases based on inventory. Emissions may also be conservatively estimated when sampling or monitoring is inadequate.

For gas emissions in particular, the use of data logging is practical and efficient. The facility tracks the known releases of radioactive materials to the environment, and this log becomes the official basis for reporting. In addition to data logging, tracking of a facility's radioactive material inventory can be used to estimate a calculated release (EPA, 1989). In this process, one determines the amount of radioactive material used for the period under consideration. Radioactive materials in sealed packages that remain unopened, and have not leaked during the period are not included. The amount used is multiplied by both a release fraction ([RF]; Table 3) and a decontamination factor ([DF]; Table 4 and Equation 1). If there is more than one abatement control device in series, then multiple DFs are applied. Therefore, it is necessary to know the form of the radioactive material and any abatement controls.

Concepts for Environmental Radioactive Air Sampling and Monitoring 273

data trending can be provided to interested stakeholders. Correction factors are often

Several different filter media are available for the collection of aerosol particles: materials include acrylic copolymers, glass fiber, cellulose, and quartz. While most filters are surface collectors and can readily be analyzed, the user should determine the need to dissolve the filter for composite analysis or further specific isotopic analyses. The range of filter flow rates vary, but for environmental applications, a flow rate between 28 and 85 L min-1 during the sample collection period is sufficient to collect an adequate sample for analysis. Finally,

Often, there is a need to monitor tritium, iodines, carbon-14, radon, and krypton, or other gases. Table 5 shows the various elements and types of extraction considerations used. Aspects to consider when monitoring for these special materials include the ability of the media to capture the sample adequately, chemical forms available for sampling, volume necessary to acquire the sample, and the respective efficiencies of the processes

**Element Sampling Method Analytical Method** 

Alpha track strips Alpha track

Iodines (e.g., I-131) Carbon Gamma spectrometry

Radon Activated carbon Gamma spectrometry

Table 5. Gas sampling methods and analytical processes

**3.2 Applying sample analysis correction factors** 

factors may be applied, including:

Bubblers Liquid scintillation

Bubblers Liquid scintillation

Activated carbon Gamma spectrometry Cryogenic condensing Liquid scintillation Compressed gas Gamma spectrometry

Useful resources for implementing environmental monitoring of gases include *Radioactive Air Sampling Methods* (Maiello & Hoover, 2010), *Sampling Airborne Radioactive Materials From the Stack and Ducts of Nuclear Facilities* (ISO, 2010), and *Test Methods for Measuring Radionuclide Emissions From Stationary Sources* (EPA, 2002b). These resources provide detailed information on the sampling methods, media, processes, and analytical approaches.

Once the quality status of the data is determined (e.g., valid, suspect, invalid, or validated after review), applicable correction factors can be applied to the reported data. Correction factors are applied so that results are not underreported and a conservative approach to emissions estimates is maintained. Depending on the sample method, a variety of correction

Activated carbon Gamma spectrometry

Carbon Extraction followed by liquid scintillation Activated carbon Extraction followed by liquid scintillation

Silica gel Extraction followed by liquid scintillation Molecular sieves Extraction followed by liquid scintillation

applied to the analytical data to prevent under reported measurements.

**3.1 Sample media selection** 

employed.

C-14

Tritium

Xenon

Argon, Krypton, and

the overall media efficiency must be considered.


Table 3. Release fractions for estimating radionuclide releases


Table 4. Typical decontamination factors for estimating radionuclide releases

$$\mathbf{A}\_{\text{Potentially Relensed}} = \mathbf{A}\_{\text{Inventory}} \cdot \mathbf{RF} \cdot \mathbf{\pi}(\mathbf{DF})\_{(0)} \text{ (Bq)}\tag{1}$$

Where:


For additional conservatism, one can assign the DF to 1. Also, the EPA (1989) requires that any nuclide heated above 100ºC, boils below 100ºC, or intentionally dispersed into the environment must have a RF of 1. Other assessment methods include non-destructive assessment, upstream of HEPA filter air concentration measurements, spill release fraction, and back calculation, which may also be used to derive potential radioactive air emissions from a stack (Barnett & Davis, 1996).

### **3. Criteria for sampling media and correction factors**

Sampling media criteria selection must be established. Once the media is selected and evaluated, various correction factors can be applied to the data. For particulate samples, selection of an appropriate filter (paper) is generally acceptable. Sampling for radioactive gases requires special treatment and typically includes the use of activated charcoal, silica gel, or another sampling mechanism based on the characteristics of the gas. Guidance

for the selection, optimization, and use of various sampling media are provided (ISO, 2010).

After sampling media selection, subsequent sample collection and analysis are required. In particular, criteria established during the standards based process or DQO process becomes the basis for the analytical laboratory providing results so that meaningful reporting and data trending can be provided to interested stakeholders. Correction factors are often applied to the analytical data to prevent under reported measurements.

### **3.1 Sample media selection**

272 Environmental Monitoring

**Material Form Release Fraction (RF)**  Gas 1 Liquids 10-3 Particulates 10-3 Solids 10-6

**Type of Radionucides Controlled** 

APotentially Released = AInventory \* RF \* π(DF)(i) (Bq) (1)

For additional conservatism, one can assign the DF to 1. Also, the EPA (1989) requires that any nuclide heated above 100ºC, boils below 100ºC, or intentionally dispersed into the environment must have a RF of 1. Other assessment methods include non-destructive assessment, upstream of HEPA filter air concentration measurements, spill release fraction, and back calculation, which may also be used to derive potential radioactive air emissions

Sampling media criteria selection must be established. Once the media is selected and evaluated, various correction factors can be applied to the data. For particulate samples, selection of an appropriate filter (paper) is generally acceptable. Sampling for radioactive gases requires special treatment and typically includes the use of activated charcoal, silica gel, or another sampling mechanism based on the characteristics of the gas. Guidance for the selection, optimization, and use of various sampling media are provided (ISO,

After sampling media selection, subsequent sample collection and analysis are required. In particular, criteria established during the standards based process or DQO process becomes the basis for the analytical laboratory providing results so that meaningful reporting and

**Decontamination Factor** 

**(DF)** 

Table 3. Release fractions for estimating radionuclide releases

**(i.e., form)** 

HEPA filter Particulates 0.01 Fabric filter Particulates 0.1 Activated carbon filters Iodine gas 0.1 Venturi scrubber Particulates 0.5 Packed bed scrubbers Gases 0.1 Electrostatic precipitators Particulates 0.05 Xenon traps Xenon gas 0.1

Table 4. Typical decontamination factors for estimating radionuclide releases

APotentially Released =calculated release in of given isotope in Becquerel AInventory =activity of given isotope in the facility in Becquerel

DF(i) =decontamination factor for each device used in series

**3. Criteria for sampling media and correction factors** 

RF =release fraction for material

from a stack (Barnett & Davis, 1996).

**Abatement Control** 

**Device** 

Where:

2010).

Several different filter media are available for the collection of aerosol particles: materials include acrylic copolymers, glass fiber, cellulose, and quartz. While most filters are surface collectors and can readily be analyzed, the user should determine the need to dissolve the filter for composite analysis or further specific isotopic analyses. The range of filter flow rates vary, but for environmental applications, a flow rate between 28 and 85 L min-1 during the sample collection period is sufficient to collect an adequate sample for analysis. Finally, the overall media efficiency must be considered.

Often, there is a need to monitor tritium, iodines, carbon-14, radon, and krypton, or other gases. Table 5 shows the various elements and types of extraction considerations used. Aspects to consider when monitoring for these special materials include the ability of the media to capture the sample adequately, chemical forms available for sampling, volume necessary to acquire the sample, and the respective efficiencies of the processes employed.


Table 5. Gas sampling methods and analytical processes

Useful resources for implementing environmental monitoring of gases include *Radioactive Air Sampling Methods* (Maiello & Hoover, 2010), *Sampling Airborne Radioactive Materials From the Stack and Ducts of Nuclear Facilities* (ISO, 2010), and *Test Methods for Measuring Radionuclide Emissions From Stationary Sources* (EPA, 2002b). These resources provide detailed information on the sampling methods, media, processes, and analytical approaches.

#### **3.2 Applying sample analysis correction factors**

Once the quality status of the data is determined (e.g., valid, suspect, invalid, or validated after review), applicable correction factors can be applied to the reported data. Correction factors are applied so that results are not underreported and a conservative approach to emissions estimates is maintained. Depending on the sample method, a variety of correction factors may be applied, including:

Concepts for Environmental Radioactive Air Sampling and Monitoring 275

The sample collection media efficiency is not to be confused with the total efficiency of the sample media; it is only the part associated with the media itself. Today's filters typically have an efficiency range between 0.8 and 0.9999 for particle sizes in the 0.1 to 10 µm range, depending on the application. Most manufacturers will state rated efficiency for a given range of particle sizes. Silica gel often has 100% retention for tritium sampling until the sample cartridge is fully loaded and breakthrough occurs. In some cases, the unknown

The calculation and reporting of the final result should include the appropriate correction

ATotal = ASample / π(E)(i) (Bq) (2)

All data results should be trended against established criteria to evaluate potential changes over time. The repeat measurements at a sampling location can be used to show a normal operating range with the expected statistical deviations. Data trending can also show increasing or decreasing emissions over various cycle times or events. When a data result falls outside of this normal trend, it can then be evaluated. Example causes can be associated with a sampling error (e.g., the wrong sample was reported, or there was a cross

In many areas, it is mandatory to provide complete and periodic reports to regulatory agencies or customers on the release of airborne radioactive material. The comprehensive report should allow for the discussion of error analysis and provide quantifiable impacts to the public and the environment. Exceeding a regulatory limit, compliance level, or permit condition requires an event notification to the appropriate regulatory agency. Compliance is a cooperative effort between the facility and the local community and regulatory agencies

An annual report on the emissions of radioactive material has several aspects to consider, and it may be required to include specific information based on applicable regulations or permits and be certified by a responsible individual. Results of reported emissions can then

A facility description will include historical background on the reporting site, detail the activities conducted resulting in releases of radioactive materials, and offer information on

factors as discussed above. The total activity of a sample is expressed in Equation 2.

E(i) =efficiency factors, including self-absorption, sampler, transport and media

contamination of the sample) or a change in the overall emissions characteristics.

and requires a fully implemented quality assurance (QA) program.

be converted to an off-site dose. Basic elements are identified below:

media efficiency requires evaluation or estimation.

ATotal =total activity on sample in Becquerel

ASample =sample activity in Becquerel

**4. Reporting and compliance** 

**4.1 Annual reporting** 

1. Facility description

5. Non-routine releases 6. Supplemental information

2. Emission point description 3. Emissions reporting

4. Input parameters and dose assessment

Where:


The radioactive decay factor accounts for the time between the midpoint of the sample collection period and the sample analysis time. In most cases, the radioactive decay factor can be set to 1 because time lapse between collection and analysis is much shorter than the half-lives of the radioisotopes of concern. For short-lived radioisotopes, a correction may be necessary and can vary according to the time and the specific half-life of the isotope.

Self-absorption factor corrects for the bias caused by the absorption of emitted radiation from the collected particles by dust/particulates and the filter media itself. For filters, this factor is dependent on the amount of material collected and is shown in Fig. 7. Other types of self-absorption factors may need to be calculated, for example, those associated with cartridges.

Fig. 7. Percent loss due to self-absorption versus mass loading1

The sampler efficiency factor accounts for biases caused by problems with the sampler operation. If the sampler operates without interruption during the sampling period, efficiency is 100% (or 1); however, when operation is incomplete or interrupted, the sampler efficiency factor is determined by the amount of time the sample was collected divided by the entire sample period. If the sampler efficiency factor is too low, an invalid sample may result. Computer models can be employed to calculate the transportation efficiency correction

factor; for example, DEPO has been used in stack monitoring to calculate line losses (McFarland et al., 2000). For environmental monitoring stations that do not have long or complicated transport lines, this factor is often set to 1 and not calculated.

<sup>1</sup> Adapted from Smith et al. (2011) for 47-mm filters when the percent loss is optimized and the exponential function is forced to near zero at very low mass loadings.

The sample collection media efficiency is not to be confused with the total efficiency of the sample media; it is only the part associated with the media itself. Today's filters typically have an efficiency range between 0.8 and 0.9999 for particle sizes in the 0.1 to 10 µm range, depending on the application. Most manufacturers will state rated efficiency for a given range of particle sizes. Silica gel often has 100% retention for tritium sampling until the sample cartridge is fully loaded and breakthrough occurs. In some cases, the unknown media efficiency requires evaluation or estimation.

The calculation and reporting of the final result should include the appropriate correction factors as discussed above. The total activity of a sample is expressed in Equation 2.

$$\mathbf{A}\_{\text{Total}} = \mathbf{A}\_{\text{Sample}} \Big/ \mathfrak{m}(\mathbf{E})\_{\text{(i)}} \text{(Bq)}\tag{2}$$

Where:

274 Environmental Monitoring

The radioactive decay factor accounts for the time between the midpoint of the sample collection period and the sample analysis time. In most cases, the radioactive decay factor can be set to 1 because time lapse between collection and analysis is much shorter than the half-lives of the radioisotopes of concern. For short-lived radioisotopes, a correction may be

Self-absorption factor corrects for the bias caused by the absorption of emitted radiation from the collected particles by dust/particulates and the filter media itself. For filters, this factor is dependent on the amount of material collected and is shown in Fig. 7. Other types of self-absorption factors may need to be calculated, for example, those associated with

The sampler efficiency factor accounts for biases caused by problems with the sampler operation. If the sampler operates without interruption during the sampling period, efficiency is 100% (or 1); however, when operation is incomplete or interrupted, the sampler efficiency factor is determined by the amount of time the sample was collected divided by the entire

Computer models can be employed to calculate the transportation efficiency correction factor; for example, DEPO has been used in stack monitoring to calculate line losses (McFarland et al., 2000). For environmental monitoring stations that do not have long or

sample period. If the sampler efficiency factor is too low, an invalid sample may result.

1 Adapted from Smith et al. (2011) for 47-mm filters when the percent loss is optimized and the

complicated transport lines, this factor is often set to 1 and not calculated.

necessary and can vary according to the time and the specific half-life of the isotope.

Fig. 7. Percent loss due to self-absorption versus mass loading1

exponential function is forced to near zero at very low mass loadings.

1. Radioactive decay factor 2. Self absorption (for filters)

5. Sample collector media efficiency

3. Sampler efficiency 4. Transport efficiency

cartridges.

ATotal =total activity on sample in Becquerel ASample =sample activity in Becquerel

E(i) =efficiency factors, including self-absorption, sampler, transport and media

All data results should be trended against established criteria to evaluate potential changes over time. The repeat measurements at a sampling location can be used to show a normal operating range with the expected statistical deviations. Data trending can also show increasing or decreasing emissions over various cycle times or events. When a data result falls outside of this normal trend, it can then be evaluated. Example causes can be associated with a sampling error (e.g., the wrong sample was reported, or there was a cross contamination of the sample) or a change in the overall emissions characteristics.
