MARLAP, MARSSIM and RETSREMP: How is All of this
Related…or NOT?
Robert Litman, Ph.D.
Eric L. Darois, MS, CHP
Radiation Safety & Control Services, Inc.
Stratham, NH
www.radsafety.com
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RETS-REMP
• Two separate programs required of Nuclear Power
Plants for assessment of dose to the public based on
modeling assumptions of uptake and measurements of
activity concentration and rate of release from the plants.
• Related documents for these programs:
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Technical Requirements Manual/Technical Specifications
RG 4.15
RG 1.21
10CFR50
10CFR20
others
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Program Objectives?
Exactly what is it that we want to measure?
1. Difference between background concentration and
concentration of radionuclides released in the
respective medium
2. Proximity of radionuclide concentration released to
the limit specified in 10CFR20 and 10CFR50
3. An administrative limit established by an omniscient
executive director
4. None of the above
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Old Terms
• Precision
– How close to the “true value” the
measurement is
• Accuracy
– How reproducible the measurement is
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Measurement Quality Objectives
(MQOs)
• What are MQOs?
• Are they necessary?
• Do they apply to the RETS or REMP
Programs?
• Is there a rational approach to how the
MQOs are established?
• Does any one verify that the MQOs have
been achieved (and how does one go
about doing that)?
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MARSSIM
• The Multi-Agency Radiation Survey and Site
Investigation Manual (NUREG-1575, EPA 402R-97-016)
– A guidance document
– Provides information on planning, conducting,
evaluating and documenting Final Status Surveys
(FSS) in support of decommissioning.
– Provides a consistent approach to the FSS
radiological issues and encourages effective use of
resources.
– Focuses on field sampling methodologies to support
the FSS activities
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The MARSSIM Process
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Originally written for planning for the decommissioning or closure of facilities
contaminated with radioactive materials.
Historical Site Assessment (10CFR50.75(g)
Facility Characterization
Facility Classification (1,2,3, Non-Impacted)
Survey Areas and Survey Units
Final Status Survey Design (DQOs)
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Data Quality Objectives
Derived Concentration Guideline Levels
Sampling Density
Scanning Methods and Density Elevated Measurement Comparison
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Data Review and Interpretation – Data Quality Assessment (DQAs)
Non-Parametric Statistical Tests – Survey Unit Passes or Fails
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Use of DQO and DQA process can apply to RETS-REMP
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MARSSIM
• Provides significant information regarding
the planning of the location and numbers
of samples to be taken for environmental
monitoring.
• Applicable to REMP program?
• What about looking forward to
decommissioning?
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MARLAP
Multi-agency Radiological Laboratory Analytical
Protocols Manual (NUREG 1576, EPA 402-B001C)
– A guidance document
– Two parts, three volumes
– Provides a structured approach to project planning
(Part I)
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Identifying MQOs
Identifying a project plan team and responsibilities
Selecting a laboratory to perform analyses
Selecting a method for the radiochemical analyses
Data verification and validation method
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MARLAP (continued)
– Provides a significant amount of technical
information on (Part II):
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Sample Preparation
Sample Digestion
Radiochemical Separations
Nuclear Counting Techniques
Laboratory Quality Control
A rational approach to data evaluation
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MARLAP (continued)
• What are the individual data components
that are inputs to your dose calculations
for RETS or REMP?
• Can the guidance in MARLAP be applied
to these?
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Data Trends
• How do you know the data are valid?
• Are there written acceptance criteria for
results?
• How are the data evaluated?
• Should RETS or REMP data be trended?
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Uncertainty
• How do you define it?
• Is it a necessary parameter?
• Can it (should it) be used for data
evaluation?
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MARLAP - Principals
The central principal of the
MARLAP is:
Required Method Uncertainty1
Or…
How well do you really need to know
what you are measuring?
1Same
concept as used in MARSSIM
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MARLAP - Uncertainty
The required method uncertainty is based
on:
• the ‘important range’ of your data1 defined
by:
– An upper bound called the Action Level
– A lower bound called the discrimination level
AND
1Referred
to as the ‘Gray Region
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MARLAP - Uncertainty
• The acceptable error rate for that data to
fall either above the Action Level (AL) or
below the Discrimination Level (DL)
The required method uncertainty is defined
as:
uMR = [AL –DL]/(sum of error rates)
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MARLAP - Uncertainty
• When the acceptable error rate for a Type
I and a Type II error on an individual
sample are held at 5%, The equation
reduces to:
uMR = [AL – DL]/(1.645 +1.645)
= [Gray Region]/3.29
This is frequently identified as Δ/3.
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Uncertainty and the Action Level
Relatively large uncertainty can be tolerated:
Δ

Either more accuracy or more samples are needed:
Δ

The closer the mean of the distribution of analytical results is to the action level, the
smaller the uncertainty needs to be to distinguish the mean from the action level.
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Uncertainty and the Action Level
Some observations regarding uMR:
• As the gray region decreases the uMR
value decreases (at the same error rate)
• As the acceptable error rate decreases the
uMR value decreases for the same gray
region
• If your sample value is at the action level,
there is a 50% chance that the ‘true value’
is above the action level
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An Example
Your WL discharge limit is 5x10-6 μCi/ml for 137Cs (otherwise the tank will
need to be reprocessed). Your Site Director says he wants to be 99.9% sure
that your measurement will show that the tank is less than this value. What
is the maximum value that the tank can have to prove this?
Gray Region = [5x10-6 – zero]
uMR = 5x10-6/(2x3.09) = 8.1x10-7
In order to prove that the tank is not above the AL, with 99.9% surety the
value cannot exceed [AL – 3.090x8.1x10-7] = 2.5x10-6 μCi/ml
For the same example change the gray
region to [5x10-6- 2x10-6] and the “do not
exceed” value becomes 3.5x10-6 μCi/ml.
Values for α or βerror rates
Rate
Value
0.001
3.090
0.01
2.326
0.025
1.960
0.05
1.645
0.10
0.20
0.30
0.50
1.282
0.842
0.524
0.000
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REMP Data Evaluation
You have received your latest report form
the contract laboratory for offsite well
analysis (closest DW supply). All
analytical radionuclide values required by
your REMP program are reported as “nondetects”, except for 59Fe which is reported
as 45 pCi/L. Your reporting limit is 400
pCi/L and your ‘required detection limit’ is
30 pCi/L.
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REMP Data Evaluation
What do you do?
1. No investigative action as the value is below
the reporting level
2. Notify the NRC that a potential release has
occurred as you are above the required
detection limit
3. Have the laboratory reanalyze the sample
and hope for a value less than the required
detection limit.
4. Something else….
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REMP Data Evaluation
Trending of REMP data and qualifying each radionuclide
result provides historical evidence of normal variation in
measurements at the background levels.
The record of qualifiers and of QC data agreement also
provides information about the consistency of the results.
Both provide factual information to defend decisions about
detectability of data and to what population the data
most likely belongs.
Information on how to incorporate these into your program
is found in the MARLAP.
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Questions ?
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