Frequent Questions: Radiation Regulations, Guidance and Compliance
View frequently asked questions and answers related to radiation regulations, guidance and compliance by topic.
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Compliance Software
Can I use models other than COMPLY, CAP-88 and AIRDOS-PC to demonstrate compliance with Subpart H and Subpart I?
COMPLY, CAP-88, and AIRDOS-PC have been tested and used throughout the country. However, if you’d like to use a different model to demonstrate compliance with Subpart H and Subpart I, you may do so.
Before using another model, you must obtain EPA approval; please Contact Us, and the Radiation Protection Division at the EPA will direct you to the appropriate contact, either in your region or at headquarters.
Where can I find information about demonstrating compliance with 40 CFR Part 61, Subpart H and I?
For more information about 40 CFR Part 61 Subparts H and I, please visit RADInfo National Emission Standards.
For more information about available assessment software, please visit Compliance Software for Radioactive Air Emissions.
If you still have questions about demonstrating compliance with 40 CFR Part 61, Subparts H and I, please Contact Us.
How should a facility demonstrate compliance for radionuclides not included in CAP88-PC?
To demonstrate compliance with any procedure not specified in the rule, you must obtain EPA approval. Contact Us for information about approval.
In unique situations, radiation releases contain radionuclides not included in CAP-88. In these cases, please contact the EPA regional office that serves your state, as they will be able to guide you through developing a proper compliance methodology. Please visit the Contact Us page for regional contact information.
For more information on CAP-88 and CAP-88 PC, please see Compliance Software for Radioactive Air Emissions.
How do I merge my population datasets from older versions of CAP-88 to CAP-88 Version 4?
The EPA recommends that you first try the Migration Utility that is a part of CAP 88-PC Version 4. When you first install Version 4, you must do two things: First, install the code, and, second, run the Migration Utility—the second step will create data folders for Version 4and transfer any Version 3 data to your updated CAP-88 software. If you have already installed Version 4, run the Migration Utility by going to the “Tools” drop down menu on the main screen.
For more information about troubleshooting the CAP-88 software, visit CAP-88 User Guide.
Is CAP-88 PC appropriate for estimating exposures from short-term or "accidental" releases?
CAP-88 is not an appropriate program for modeling short term or “accidental” releases for a few reasons. The software uses dose/risk conversion factors that rely on chronic, low-level exposure predictions and utilizes the Gaussian model, which is a long-term model that estimates average dispersals of radionuclides. Additionally, the software relies on weather data that utilizes annual averages, so a short-term release would not work.
Learn more about CAP-88 PC.
I’m having trouble with the CAP-88 software; who can I ask for help?
For questions and troubleshooting help with the CAP-88 software, please send an email to Brian Littleton of the U.S. Environmental Protection Agency at Littleton.Brian@EPA.gov.
For more information about CAP-88, please see CAP-88 PC.
MARSSIM General Questions
What guidance does MARSSIM provide on specific phases and aspects of site surveys?
MARSSIM is a document that details the complete radiation site survey and investigation process from designing and implementing surveys, to a final analysis of survey data so that a decision can be made. This ensures a high degree of certainty in determining whether a survey unit meets or exceeds a dose- or risk-based regulatory level.
More technical information and guidance on using MARSSIM for specific phases and aspects of site surveys can be found in the MARSSIM Manual and Resources.
For more information about the creation of MARSSIM, visit the Multi-Agency Radiation Survey and Site Investigation Manual (MARSSIM).
Does MARSSIM conflict with existing guidance?
MARSSIM is a technical best practices document. It was created to comprehensively address all phases of the survey process for surface soil and building surfaces to demonstrate compliance with dose-based or risk-based requirements. MARSSIM includes steps for planning and conducting surveys, evaluating them, and making decisions.
For more information about the creation of MARSSIM, visit the Multi-Agency Radiation Survey and Site Investigation Manual (MARSSIM).
Why is MARSSIM being updated?
- The MARSSIM revisions include updating the document to reflect the most current science, clarifying methods, and implementing lessons learned from more than 20 years of the document’s use in industry.
- The scientific ability to measure radiation and the type and number of radiation measurement methods have increased since MARSSIM was first issued in 1997.
- Over the past ten years, the MARSSIM Workgroup discussed ways to implement the most current scientific understanding of radiation site investigation and survey in revisions to the document.
- Updates to MARSSIM are intended to increase clarity and improve flexibility in providing a consistent approach for planning, performing, and assessing building surface and surface soil radiological surveys to meet established dose or risk-based release criteria, while concurrently encouraging an effective use of resources.
How can I contact MARSSIM workgroup members?
Four agencies currently meet as part of the MARSSIM Workgroup: The Department of Defense (DOD), the Department of Energy (DOE), the Nuclear Regulatory Commission (NRC), and the EPA. These agencies have the primary responsibility for managing radioactive materials in the United States.
To contact the MARSSIM Workgroup, please call or email Kathryn Snead, of the U.S. Environmental Protection Agency, at 202-343-9228, or snead.kathryn@epa.gov.
For more information, visit MARSSIM Workgroup Materials.
Am I required to use MARSSIM?
You are not required to use MARSSIM. However, it is a technical best practices document. Additionally, it has multi-agency consensus; the Department of Defense (DOD), the Department of Energy (DOE), the Nuclear Regulatory Commission (U.S.NRC), and the EPA all endorse the document. Many state regulatory programs have also adopted the use of MARSSIM for demonstrating dose-based, or risk-based, compliance.
For more information about MARSSIM, visit Multi-Agency Radiation Survey and Site Investigation Manual (MARSSIM).
How can I use MARSSIM?
One of the many benefits to using the MARSSIM system is its adaptability. It is used for final status surveys at many sites throughout the United States, but it can also be used to demonstrate compliance with dose-based or risk-based requirements for scoping, characterization, and remedial action surveys. The developers of MARSSIM intended to make the system flexible, and because of this, relied on a performance-based approach in conjunction with systematic planning and the Data Quality Objectives process. Together, these methods allow users to develop a tailored survey process rather than having to rigidly adhere to a single prescriptive method.
For more information about the creation of MARSSIM, visit the Multi-Agency Radiation Survey and Site Investigation Manual (MARSSIM).
What is the Multi-Agency Radiation Survey and Site Investigation Manual, and who uses it?
The Multi-Agency Radiation Survey and Site Investigation Manual, or MARSSIM, provides detailed guidance for planning, implementing, and evaluating environmental and facility radiological surveys that are conducted to demonstrate compliance with a dose- or risk-based regulation. It is used by federal agencies and states, site owners, contractors, and the public. MARSSIM was developed collaboratively by the Department of Defense (DOD), the Department of Energy (DOE), the United States Nuclear Regulatory Commission (NRC), and the EPA.
The MARSSIM process uses a performance-based approach that, generally, involves more planning and less re-work than other methods. It is efficient, practical, and easy to use in the field.
For more information about the development of MARSSIM, visit Multi-Agency Radiation Survey and Site Investigation Manual (MARSSIM).
How will the comments be integrated into the document after the public comment period for MARSSIM Revision 2?
- Public participation in the review process is important to ensure the document is robust and useful to people who plan, perform, and assess radiological surveys of sites.
- The MARSSIM Workgroup, comprised of experts from the Environmental Protection Agency (EPA), the Nuclear Regulatory Committee (NRC), the Department of Energy (DOE), and the Department of Defense (DoD), will review public comments and adjust document content where appropriate.
See the Proposed MARSSIM Revision 2.
What is the relationship between exposure pathway models and MARSSIM?
Exposure pathway models are used to obtain site-specific release criteria, such as the DCGL. This is outside the scope of MARSSIM; however, it is important that the assumptions used in developing the DCGL (such as size or depth of residual radioactive contamination) match the assumptions used in designing a survey under MARSSIM.
MARSSIM Technical Questions
What is the LBGR?
The LBGR (Lower Bound of the Grey Region) is a concentration. It is less than the DCGLW and is chosen to be easily distinguishable from the DCGLW. You apply a statistical test to the data to determine whether the true concentration in the survey unit is above the DCGLW or below the LBGR. You are more likely to make an inaccurate decision if the true concentration of the survey unit is between the LBGR and the DCGLW. Thus, it is called the "grey region" because in that case, the decision is usually neither "black" nor "white."
For more information on the MARSSIM process, visit Multi-Agency Radiation Survey and Site Investigation Manual (MARSSIM).
Why do I need an LBGR?
The LBGR is needed to calculate the number of data points, N, which is used to test whether the survey unit concentration is less than the DCGLW. In order to calculate the shift, there must be an LBGR value (shift = DCGLW – LBGR). The shift (or width of the gray region) is then used to calculate the relative shift, which is an intermediate step necessary to calculate N. The relative shift is expressed in multiples of standard deviations.
The gray region is a range of values for the parameter of interest for a survey unit in which the consequences of making a decision error are relatively minor. The upper bound of the gray region in MARSSIM is set equal to the DCGLW, and the lower bound of the gray region (LBGR) is a site-specific variable.
For more information on the MARSSIM process, visit Multi-Agency Radiation Survey and Site Investigation Manual (MARSSIM).
How does the DCGL affect the survey design?
The answer depends upon a number of factors. In the most general terms, with all other factors being equal, the number of measurements varies inversely with the DCGL.
In reality, a change in the DCGL reflects a change in the assumptions used to translate dose or risk into concentration. This could affect the survey design in several ways. For example, changing the area of radioactivity in the exposure pathway model would change the size of survey units specified in the survey design. In another example, changes in the depth of radioactive material assumed by the model would change the sample collection procedures and scan sensitivity required for the final status survey design. In these cases, it is difficult to predict what exact affect the DCGL will have on the survey design.
For more information on the MARSSIM process, visit Multi-Agency Radiation Survey and Site Investigation Manual (MARSSIM).
How do I choose the LBGR?
Choosing the LBGR is part of an iterative process used to determine the number of data points, N, needed. The LGBR can be set at a slightly conservative value for the median residual radioactivity concentration believed to be remaining in the survey unit. If the true, but unknown, concentration in the survey unit is in the grey region, there will be difficulty in determining if the survey unit concentration is less than the DCGLW. Take the following into account the following when choosing the LBGR:
- Variation of the concentrations in the survey unit (determined from prior surveys of the survey unit).
- Variation in the measurements due to instrumentation at the candidate values for the LBGR.
- Possibility a survey unit could fail even though its average concentration is, in fact, less that the DCGLW.
- Costs of measurements at the sensitivities needed to measure the candidate values for the LBGR.
Optimize the trade-offs between increased instrument sensitivity, costs, and the number of data points needed by setting the LBGR so the relative shift is greater than one and less than three if possible.
When no other information is available, MARSSIM suggests a default value for the LBGR equal to ½ the DCGLW. After this, begin the iterative process described above.
For more information on the MARSSIM process, visit Multi-Agency Radiation Survey and Site Investigation Manual (MARSSIM).
What is a scan MDC?
The concept of the scan MDC is especially important in MARSSIM. A scan MDC is an MDC calculated for an instrument that takes continuous or "scanning" measurements. A scanning instrument can often take more measurements more cheaply and in less time than a non-scanning instrument. However, it is important that the scan MDC obtained by the scanning procedures used will actually detect the required DCGL in the field.
If the scan MDC is adequate to detect the DCGLEMC, it can be used to greatly reduce or eliminate the possibility of missing an area of elevated concentration.
For more information on the MARSSIM process, visit Multi-Agency Radiation Survey and Site Investigation Manual (MARSSIM).
What value should I use for the LBGR, if there is no prior survey information?
When no other information is available, MARSSIM suggests a default value for the LBGR equal to ½ the DCGLW. After this, begin the iterative process described in "How do I choose the LBGR?"
For more information on the MARSSIM process, visit Multi-Agency Radiation Survey and Site Investigation Manual (MARSSIM).
What is the effect on the DCGLW when I decrease or increase the survey unit size?
Generally, more measurements than are necessary could be taken if the survey unit size is smaller than the modeled survey unit size. However, if the size is not significantly smaller, it is usually simpler to make the number of measurements calculated, rather than re-deriving a new DCGLW with new modeling. If the survey unit is larger than what was modeled, dividing the survey unit into sizes that conform to the model will address the difference. Alternatively, the DCGLW can be recalculated to conform with the larger survey unit size by inserting the larger survey unit size into the model. In either case, approval from the regulator is recommended before making changes to survey unit sizes.
For more information on the MARSSIM process, visit Multi-Agency Radiation Survey and Site Investigation Manual (MARSSIM).
Can I use a different size survey unit than the example in MARSSIM?
Yes. The survey unit size should correspond to the model assumptions used to establish the DCGLW for the survey unit. As always, it is important to document the rationale for the assumptions and to consult with your regulator.
For more information on the MARSSIM process, visit Multi-Agency Radiation Survey and Site Investigation Manual (MARSSIM).
Does MARSSIM allow double sampling?
MARSSIM discourages double sampling. The DQO process, which MARSSIM uses, explicitly sets objectives for both the Type II error rate and the retrospective power during the design process. Adequate initial sampling to achieve the desired power makes decisions based on the data more objective and defensible. It would be better to plan for data collection in two stages, and design the final status survey accordingly, than to perform double sampling.
If your regulator allows double sampling, it should be decided upon during the DQO process. You should both agree upon the number of samples allowed in the second set of samples, because the Type I error rate could be as much as double the error rate for a single set of samples.
Class 2 or Class 3 survey units are not appropriate for double sampling. Concentrations in these survey units should not exceed the DCGLW, and should always pass with the first set of samples. The need for a second set of samples in Class 2 or Class 3 survey units raises the issue of misclassification. Double sampling is also generally not appropriate for Class 1 survey units having confirmed areas of elevated activity, or "hot spots."
For more information on the MARSSIM process, visit Multi-Agency Radiation Survey and Site Investigation Manual (MARSSIM).
When should I choose a value for the LBGR?
The LBGR should be chosen to represent a conservative (slightly higher) estimate of the actual concentration of residual radioactive material in the survey unit at the time that the final status survey is being conducted. Choose a preliminary value of the LBGR before remediation and a final value of the LBGR as the Final Status Survey design is completed. There are a number of factors that determine the final value of the LBGR. In some cases, you may want to remediate to concentrations sufficiently below the DCGLW, so you can demonstrate the survey unit meets the release criterion.
For more information on the MARSSIM process, visit Multi-Agency Radiation Survey and Site Investigation Manual (MARSSIM).
What is a Derived Concentration Guideline Level (DCGL)?
The Derived Concentration Guideline Level (DCGL) is a radionuclide-specific surface or volume residual radioactivity level that is related to a concentration or dose- or risk-based criterion. The regulator usually determines this criterion.
For more information on the MARSSIM process, visit Multi-Agency Radiation Survey and Site Investigation Manual (MARSSIM).
What is the relationship between survey unit size and the establishment of the DCGLW?
If the DCGLW was derived by environmental pathway modeling, then as the survey unit size changes in the model, the DCGLW may change too. Several factors affect this relationship, including the radionuclides of concern, the potential exposure pathways, and the uncertainties inherent in the model. Therefore, when considering changing the survey unit size, it is best to work with an experienced environmental pathway modeler to fully account for all the complexities inherent at the site. These changes may or may not affect survey design. It is important to talk with a regulator to determine if the resulting changes have significant impact on the DCGLW previously agreed upon.
For more information on the MARSSIM process, visit Multi-Agency Radiation Survey and Site Investigation Manual (MARSSIM).
How can I obtain DCGLs?
Methods for deriving DCGLs are outside the scope of MARSSIM. Consult the appropriate regulatory agency personnel or documents for methods used to develop DCGL values.
For more information on the MARSSIM process, visit Multi-Agency Radiation Survey and Site Investigation Manual (MARSSIM).
How is the MDC calculated?
The MDC can be calculated for an instrument by considering the background counts during a typical measurement, total detection efficiency, conversion factors, and the probe area.
Variability in the calculated MDC reflects natural variability in the detection efficiency and conversion factors. This variability may or may not be significant. For the MDC to be applicable, the sample or field measurement conditions must match the conditions under which the background was measured.
For more information on the MARSSIM process, visit Multi-Agency Radiation Survey and Site Investigation Manual (MARSSIM).
What is the relative shift?
The relative shift expresses the width of the grey region, or shift, Δ, in terms of the number of standard deviations of the measurement data, σ, and is designated as (DCGLW - LBGR/σ) or Δ/σ. The degree of difficulty in distinguishing the LBGR from the DCGLW depends on the variability of the data as well as the size of the shift. The smaller the relative shift, the larger the number of samples. The number of samples increases rapidly with only small decreases in the value of the relative shift when the value of the relative shift is below one.
For more information on the MARSSIM process, visit Multi-Agency Radiation Survey and Site Investigation Manual (MARSSIM).
What sizes does MARSSIM recommend for survey units?
The survey unit sizes in MARSSIM are not intended to be prescriptive. However, MARSSIM does offer one possible set of survey unit sizes, primarily as an example. For Class 1 survey units, MARSSIM suggests survey unit sizes of 100 m2 for structures and 2,000 m2 for land areas. For Class 2 survey units, MARSSIM suggests survey unit sizes between 100 and 1,000 m2 for structures, and between 2,000 and 10,000 m2 for land areas. However, these survey unit sizes are not intended to be prescriptive. For Class 3 survey units, MARSSIM does not suggest a limit for either structure or land areas. Section 4.6 of MARSSIM Chapter 4: Preliminary Survey Considerations recommends limiting survey units based on classification, exposure pathway modeling assumptions, and site-specific conditions.
For more information on the MARSSIM process, visit Multi-Agency Radiation Survey and Site Investigation Manual (MARSSIM).
Why would I want to perform double sampling?
When the retrospective power of a set of samples is below the required design objectives, double sampling can raise it. Insufficient retrospective power can occur for a number of reasons, most commonly because:
- The spatial variability in residual radioactivity concentrations is larger than anticipated.
- Samples were lost, did not pass analytical QA/QC, or were otherwise unavailable for inclusion in the analysis.
If you are considering double sampling, consult with your regulator and a statistician for more information.
For more information on the MARSSIM process, visit Multi-Agency Radiation Survey and Site Investigation Manual (MARSSIM).
What is the major consequence of missing an elevated area?
Missing an elevated measurement area may cause release of a survey unit that exceeds the dose- or risk-based criteria.
For more information on the MARSSIM process, visit Multi-Agency Radiation Survey and Site Investigation Manual (MARSSIM).
What is the Minimum Detectable Concentration (MDC)?
The MDC is the net concentration that has a specified chance of being detected. It is an estimate of the detection capability of a measuring protocol and is calculated before measurements are taken.
The detection limit is the lowest net response level, in counts, that you expect to be seen with a fixed level of certainty, customarily 95%. The MDC is the detection limit expressed as an activity concentration. If the activity concentration in a sample is equal to the MDC, then there is a 95% chance that radioactive material in the sample will be detected.
For more information on the MARSSIM process, visit Multi-Agency Radiation Survey and Site Investigation Manual (MARSSIM).