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U.S. Department of Energy, Environmental Protection
Agency, Nuclear Regulatory Commission and Department of Defense. (December
1997). Multi-Agency Radiation Survey and Site Investigation Manual (MARSSIM).
NUREG-1575. EPA 402-R-97-016. U.S. DOE, EPA, NRC and DOD, Washington, DC.
Chapter 1: Introduction
The final copy of this publication has now been issued. http://www.epa.gov/radiation/marssim/.
Print copies are available from the Government Printing Office for $51.00,
stock number 052-020-00639-3.
The comments and quotes below are from the draft version.
Chapter 2: Overview of the Radiation Survey and Site Investigation Process
"The primary objective of the EPA, NRC, and DOE regulations is to ensure
that human health and the environment are protected from radioactive contamination
at sites that are to be released to the public. As such, they contain a
specific limit, called the release criterion, that pertains to the
annual radiation dose to 'any reasonably maximally
exposed member of the public' (EPA) or to 'the average member of the critical
[population] group' (NRC)." (pg. 1-1).
"As illustrated in Figure 1.1, the demonstration of compliance is comprised
of three interrelated parts:
I. Translate: translating the cleanup/release criterion (e.g.,
mSv/y or mrem/y) into a corresponding derived contaminant concentration
level (e.g., Bq/kg or pCi/g in soil) through the use of environmental
II. Measure: Acquiring scientifically sound and legally defensible site-specific
data on the levels and distribution of residual contamination by employing
suitable field and/or laboratory measurement techniques.
Decide: Determining that the data obtained from sampling does support
the assertion that the site meets the release criterion, within an acceptable
degree of uncertainty, through application of a statistically-based decision
rule." (pg. 1-1, 1-3).
"Because of the large variability in the types of radiation sites, it
is impossible to provide criteria that apply to every situation." (pg.
"There are several areas beyond the scope of MARSSIM. These areas include
translation of dose or risk standards into radionuclide specific concentrations,
or demonstrating compliance with ground water or surface water regulations.
... Other contaminated media (e.g., sub-surface soil, building materials,
ground water, etc.) and the release of contaminated components and equipment
are also not addressed by MARSSIM." (pg. 1-4).
Chapter 3: Historical Site Assessment
"The process described in MARSSIM begins with the premise that a release
criterion has already been provided in terms of a measurement quantity.
"A release criterion is a regulatory limit expressed in terms
of dose (mSv/y or mrem/y) or risk (cancer incidence or cancer mortality).
The terms release limit or cleanup standard have also been used to describe
this term. A release criterion is typically based on total or committed
effective dose equivalent (TEDE or CEDE) and generally cannot be measured
directly. Exposure pathway modeling is used to calculate a radionuclide-specific
predicted concentration or surface area concentration of specific nuclides
that could result in a dose (TEDE or CEDE) equal to the release criterion.
In this manual such a concentration is termed the
guideline level (DCGL). Exposure pathway modeling is an analysis of
various exposure pathways and scenarios used to convert dose into concentration.
In many cases DCGLs can be obtained from responsible regulatory agency
guidance based on default modeling input parameters, while other users
may elect to take into account site-specific parameters to determine DCGLs.
In general, the units for the DCGL are the same as the units for measurements
performed to demonstrate compliance (e.g., Bq/kg or pCi/g, Bq/m2
or dpm/100 cm2, etc.). This allows direct comparisons between
the survey results and the DCGL." (pg. 2-2).
"If the residual radioactivity is evenly distributed over a large area,
MARSSIM looks at the average activity over the entire area. The DCGLW(the
DCGL used for the statistical tests, Section 2.5) is derived based on an
average concentration over a large area." (pg. 2-3).
"Decommissioning is the process of removing a site safely from
service, reducing residual radioactivity through remediation to a level
that permits release of the property, and termination of the license
or other authorization for site operation." (pg. 2-3).
"Areas that have no reasonable potential for residual contamination
are classified as non-impacted areas. These areas have no radiological
impact from site operations and are typically identified early in decommissioning.
Areas with some potential for residual contamination are classified as
areas." (pg. 2-4).
"Impacted areas are further divided into one of three classifications:"
"Class 1 Areas: Areas that have, or had, a potential for radioactive
contamination (based on site operating history) or known contamination
(based on previous radiation surveys) above the DCGLW." (pg.
"Class 2 Areas: Areas that have, or had, a potential for radioactive
contamination or known contamination, but are not expected to exceed the
DCGLW." (pg. 2-5).
"Class 3 Areas: Any impacted areas that are not expected to contain
any residual radioactivity, or are expected to contain levels of residual
radioactivity at a very small fraction of the DCGLW, based on
site operating history and previous radiation surveys." (pg. 2-5).
"The characterization survey is the most comprehensive of all the survey
types and generated the most data. It includes preparing a reference
grid, systematic as well as judgment measurements, and
different media (e.g., surface soils, interior and exterior surfaces
of buildings). The decision as to which media will be surveyed is a site-specific
decision addressed throughout the Radiation Survey and Site Investigation
Process." (pg. 2-24).
"As previously stated, GCGLs are assumed to be developed with the assumption
of a relatively uniform distribution of contamination. Some variability
in the measurements is expected. This variability is primarily due to a
random spatial distribution of contamination and uncertainties in the measurement
process. The arithmetic mean of the measurements taken from such a distribution
would represent the parameter of interest for demonstrating compliance."
Chapter 4: Preliminary Survey Considerations
"Historical Site Assessment (HSA) is the first step in the Radiation
Survey and Site Investigation Process. The HSA is a detailed investigation
to collect existing information (from the start of site activities related
to radionuclides) for the site and its surroundings. The necessity for
and amount of effort associated with an HSA depends on the type of site,
the site's regulatory framework, and availability of documented information."
"The initial classification of the site involves developing a conceptual
model based on the existing information collected during the preliminary
investigation. Conceptual models describe a site or facility and its environs,
and present hypotheses regarding the radionuclides for known and potential
residual contamination (EPA 1987b, 1987c)." (pg. 3-3).
"An efficient HSA gathers information sufficient to identify the radionuclides
used at the site --- including their chemical and physical form. The first
step in evaluating HSA data is to estimate the potential for residual contamination
by these radionuclides." (pg. 3-11).
"Information gathered during the HSA should be used to provide an initial
classification of the site areas as impacted or non-impacted." (pg. 3-12).
"The next step in evaluating the data gathered during the HSA is to
identify potentially contaminated media at the site." (pg. 3-12).
Chapter 5: Survey Planning and Design
"Conducting radiological surveys in support of decommissioning serves
to answer several basic questions, including:
Is there residual radioactive contamination present from previous uses?
What is the character (qualitative and quantitative) of the residual
Is the average residual activity level below the established derived
concentration guideline level?
Are there small localized areas of residual activity in excess of the
investigation level?" (pg. 4-1).
"The decommissioning process assures that residual radioactivity will
not result in individuals being exposed to unacceptable levels of radiation
and/or radioactive materials. Regulatory agencies establish radiation dose
standards based on risk considerations and scientific data relating dose
to risk. Residual levels of radioactive material that correspond to allowable
radiation dose standards are calculated (derived) by analysis of various
pathways and scenarios (direct radiation, inhalation, ingestion,
through which exposures could occur. These derived levels, known as derived
concentration guideline levels (DCGLs), are presented in terms of surface
or volume activity concentrations. DCGLs refer to average levels of radiation
or radioactivity above appropriate background levels. DCGLs applicable
to building or other structural and miscellaneous surfaces are expressed
in units of activity per surface area (typically Bq/m2 or dpm/100
cm2). When applied to soil and induced activity from neutron
irradiation DCGLs are expressed in units of activity per unit of mass (typically
Bq/kg or pCi/g)." (pg. 4-1).
"The DCGLW, based on pathway modeling, is the uniform residual
radioactivity concentration level within a survey unit that corresponds
to the release criterion (e.g., regulatory limit in terms of dose
or risk). (pg. 4-3).
"Identification of radionuclide contaminants at the site is generally
performed through laboratory analyses, such as alpha and gamma spectrometry.
... This information is essential in establishing the DCGLs for the site.
DCGLs provide the basis for essentially all aspects of designing, implementing,
and evaluating the final status survey. The DCGLs discussed in this manual
are limited to structure surfaces and soil contamination; the user should
consult the responsible regulatory agency if it is necessary to establish
DCGLs for other environmental media (e.g., groundwater, and other
water pathways). (pg. 4-3).
"For sites with multiple contaminants, it may be possible to measure
just one of the contaminants and still demonstrate compliance for all of
the contaminants present." (pg. 4-4).
"Typically, each radionuclide DCGL corresponds to the release criterion
(e.g., regulatory limit in terms of dose or risk). However, in the
presence of multiple radionuclides the DCGLs for each radionuclide would
in sum total result in the release criterion being exceeded by these DCGLs.
In this case, the individual DCGLs need to be adjusted to account for the
presence of multiple radionuclides contributing to the total dose. One
method for adjusting the DCGLs is to modify the assumptions made during
exposure pathway modeling to account for multiple radionuclides. A second
method is to use the unity rule to adjust the individual DCGLs." (pg. 4-6).
Chapter 6: Field Measurement Methods and Instrumentation
"Radiological characterization surveys may be performed to satisfy a
number of specific objectives. Examples of characterization survey objectives
include: 1) determining the nature and extent of radiological contamination;
2) evaluating remediation alternatives (e.g., unrestricted use,
restricted use, onsite disposal, off-site disposal, etc.); 3) input
to pathway analysis/dose assessment models for determining site-specific
DCGLs (Bq/kg, Bq/m2); 4) estimating the occupational and public
health and safety impacts during decommissioning; 5) evaluating remediation
technologies; 6) input to final status survey design..." (pg. 5-7).
"Contamination release and migration pathways, as well as areas that
are potentially affected and are likely to contain residual contamination,
should be identified." (pg. 5-8).
"In planning for potential use of characterization survey data as part
of the final status survey, the characterization data must be of sufficient
quality and quantity, including location information, for that use (see
Section 5.5)." (pg. 5-9).
"Characterization survey activities often involve the detailed assessment
of various types of building and environmental media ... The HSA data should
be used to identify the potentially contaminated media on-site ... Selection
of survey instrumentation and analytical techniques are typically based
on a knowledge of the appropriate DCGLs --- because any remediation decisions
are made based on the level of the residual contamination as compared to
the DCGL." (pg. 5-9).
"Sample locations should be referenced to reference system coordinates
(see Section 4.8.5), if appropriate, or prominent site features. A typical
reference system spacing for open land areas is 10 meters. This spacing
is chosen to facilitate determining survey unit locations and evaluating
areas of elevated radioactivity." (pg. 5-11).
"Survey data are converted to the same units as those in which DCGLs
are expressed (Section 6.2.7). Identification of potential radionuclide
contaminants at the site is performed through laboratory and in situ
analyses. Appropriate regulatory DCGLs for the site are selected and the
data compared to DCGLs." (pg. 5-14).
"For characterization data that are used to help guide remediation efforts,
the survey data are used to identify locations and general extent of residual
activity. The survey results are compared with DCGLs, and surfaces/environmental
media are differentiated as exceeding DCGLs, not exceeding DCGLs, or not
contaminated, depending on the measurements results relative to the DCGL
value. Direct measurements indicating areas of elevated activity are further
evaluated and the need for additional measurements/samples is determined."
"Documentation of the site characterization survey should provide a
complete and unambiguous record of the radiological status of the site.
In addition, sufficient information to characterize the extent of contamination,
including all possible affected environmental media, should be provided
in the report. This report should also provide sufficient information to
support reasonable decontamination approaches or alternatives." (pg. 5-14).
"The effectiveness of decontamination efforts in reducing residual radioactivity
to acceptable levels is monitored as the decontamination is in progress
by a remedial action support survey. This type of survey guides the cleanup
in a real-time mode." (pg. 5-17).
"The objective of the remedial action support survey is to detect the
presence of residual activity, at or below the DCGL criteria. Although
the presence of small areas of elevated radioactivity may satisfy the elevated
measurement criteria, it may be more efficient to design the remedial
action support survey to identify residual radioactivity at the DCGLW
(and to remediate small areas of elevated activity that may potentially
satisfy the release criteria). Survey instrumentation and techniques are
therefore selected based on the detection capabilities for the known or
suspected contaminants and DCGLs to be achieved." (pg. 5-17).
"There will be radionuclides and media which cannot be evaluated at
the DCGLW using field monitoring techniques. For these cases,
it may be feasible to collect and analyze samples by methods which are
quicker and less costly than radionuclide-specific laboratory procedures.
Field laboratories and screening techniques may be options to more expensive
analyses." (pg. 5-17).
"Remedial action support surveys may not be feasible for surfaces contaminated
with very low energy beta emitters or for soils or media contaminated with
pure alpha emitters." (pg. 5-19).
"The objective of final status surveys is typically to demonstrate that
residual radioactivity levels meet the release criterion." (pg. 5-14).
Chapter 7: Sampling and Preparation for Laboratory Measurements
"There are certain radionuclides which will be essentially impossible
to measure at the DCGLs in situ using current state-of-the-art instrumentation
and techniques because of the types, energies, and abundances of their
radiations. Examples of such radionuclides include very low energy, pure
beta emitters such as 3H and 63Ni [90Sr,
and low-energy photon emitters such as 55Fe and 125I.
Pure alpha emitters dispersed in soil or covered with some absorbing layer
will not be detectable because alpha radiation will not penetrate through
the media or covering to reach the detector." (pg. 6-1).
"Scanning surveys are performed to locate radiation anomalies indicating
residual gross activity that may require further investigation or action.
In other words, scanning is used to locate small areas of elevated activity
that exceed the investigation level. ... sampling on the commonly used
grid spacing may have a low probability of identifying such small areas.
For this reason scanning surveys are typically performed before direct
measurements or sampling." (pg. 6-3).
"DCGLs for residual activity are typically stated in units of net activity
(i.e., above the level occurring in background)." (pg. 6-6).
"... levels of direct radiation (exposure rates) and some naturally
occurring (uranium and thorium decay series, 40K) or man-made
(137Cs, 238-240Pu) radionuclides are typically present
in the environment at levels that are easily quantifiable and may have
background levels that are significant relative to the DCGLs (Wallo, et
al. 1994). As background levels approach, or even exceed, the DCGLs,
the number of measurements estimated to demonstrate compliance using the
statistical tests may increase." (pg. 6-7).
"As with laboratory-based gamma spectrometry, in situ gamma spectrometry
provides the means to discriminate among various radionuclides on the basis
of characteristic gamma and x-ray energies and thus constitutes a nuclide-specific
measurement." (pg. 6-7).
"Traditionally, gamma-ray spectrometry performed in the field for low-level
contamination was limited to relatively strong gamma emitters. Recent availability
of large high-efficiency germanium detectors means that in some cases rather
low intensity gamma emitters can be measured -- i.e., those with
emission intensities of a fraction to a few percent. ... Using arrays of
detectors to increase sensitivity, even highly attenuated low-energy emitters
such as 241Am (60 keV) are measurable (Reiman 1994). Using other
types of detectors, such as large area proportional counters, it is also
possible to measure the x-rays associated with certain alpha emitters,
such as 238Pu, 239Pu, and 240Pu. Photon
spectrometry is not possible for pure beta emitters such as 90SR."
"Radation survey data are usually obtained in units, such as the number
of counts per unit time, that have no intrinsic meaning relative to DCGLs.
For comparison of survey data to DCGLs, the survey data from field and
laboratory measurements should be converted to DCGL units." (pg. 6-9).
Chapter 8: Interpretation of Survey Results
"Liquid scintillation is the preferred method for counting low-energy
beta-emitters (e.g., 3H, 14C, and
and is excellent for counting high energy beta (e.g.,
and low-energy photon-emitters (e.g., 55Fe and 125I)."
"It is prudent to subject at least a representative number of soil or
sediment samples to gamma spectral analysis, even if no gamma emitters
are expected, as a check on the reliability of the identification of potential
contaminants. Either solid-state germanium detectors or sodium iodide scintillation
detectors may be used. However, the solid-state detector has an advantage
because of its ability to resolve multiple gamma photopeaks that may differ
from each other by as little as 0.5 to 1 keV." (pg. 7-20).
"Spectra should also be reviewed for gamma-photopeaks not previously
identified as principal facility contaminants of concern." (pg. 7-20).
"Radionuclides emitting primarily alpha particles are best analyzed
by wet chemistry separation followed by counting to determine amounts of
specific alpha energies present." (pg. 7-21).
"Analysis of soil/sediment samples for most pure beta radionuclides,
such as 90Sr, 99Tc, and 63Ni generally
involves wet chemistry separation, followed by counting using liquid scintillation
or beta proportional instruments." (pg. 7-21).
"Radiological survey data are usually obtained in units, such as the
number of counts per unit time, that have no intrinsic meaning relative
to DCGLs. For comparison of survey data to DCGLs, the survey data from
field and laboratory measurements should be converted to DCGL units." (pg.
"Note that some individual survey unit measurements may exceed the DCGLW
even when the survey unit as a whole meets the release criterion. In fact,
a survey unit that averages close to the DCGLW might have almost
half of its individual measurements greater than the DCGLW.
Such a survey unit may still meet the release criterion." (pg. 8-13 - 8-14).
"The assumption is that the survey unit measurements are independent
random samples from a symmetric distribution." (pg. 8-14).
"Unusually high readings should be flagged and measurements that exceed
the larger of either 3 standard deviations above the mean
of the survey unit or the DCGLW, should be investigated
further." (pg. 8-24).
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