[Federal Register Volume 64, Number 69 (Monday, April 12, 1999)]
[Notices]
[Pages 17690-17695]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-9036]
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NUCLEAR REGULATORY COMMISSION
Draft Guidance on the Benchmark Dose Modeling for the
Radiological Criteria for License Termination of Uranium Recovery
Facilities
AGENCY: Nuclear Regulatory Commission.
ACTION: Notice of availability; opportunity for comment.
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SUMMARY: The U.S. Nuclear Regulatory Commission (NRC) is soliciting
comments on draft guidance for the radium benchmark dose approach,
associated with the final rule, ``Radiological Criteria for License
[[Page 17691]]
Termination of Uranium Recovery Facilities,'' that is in this
publication. The guidance will be incorporated into the NRC final
Standard Review Plan (SRP) for the Review of Reclamation Plans for Mill
Tailings Sites and the SRP for In-Situ Leach Uranium Extraction License
Applications. Public comments should be submitted within sixty (60)
days of publication of this Notice.
SUPPLEMENTARY INFORMATION:
Background
In 10 CFR 40.4, uranium milling is defined as any activity
resulting in byproduct material. 1 Therefore, Part 40,
Appendix A, applies to in situ leach (ISL), heap leach, and ion-
exchange facilities (i.e., uranium recovery (UR) facilities) that
produce byproduct material, as well as to conventional uranium and
thorium mills. The draft guidance only addresses UR facilities because
there are no currently licensed or planned thorium mills.
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\1\ Byproduct material means the tailings or waste produced by
the extraction or concentration of uranium or thorium from any ore
processed primarily for its source material content, including
discrete surface wastes resulting from uranium solution extraction
processes.
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Decommissioning of ISLs and mills are similar in that the type of
soil and building contamination is the same, consisting mainly of
residual radium (Ra-226) and uranium (U-nat). The applicable cleanup
standards for soil radium in Criterion 6(6) address the main
contaminant at uranium mills in the large areas (hundreds of acres)
where windblown contamination from the tailings pile has occurred, and
at ISLs in holding/settling ponds and process solution spills. In other
mill and ISL site areas proximate to locations where radium
contamination exists (e.g., under the mill or process building or in a
yellowcake storage area), uranium would be the radionuclide of concern.
Thorium (Th-230, the parent of Ra-226) would be the radionuclide of
concern at some mill raffinate evaporation ponds.
Because Part 40, Appendix A, provides only decommissioning soil
radium 2 and ground-water protection criteria, Criterion 6
(6) was amended to address criteria for residual radionuclides, other
than radium in soil, for decommissioning of lands and structures at UR
facilities. The final rule, ``Radiological Criteria for License
Termination of Uranium Recovery Facilities,'' added a paragraph after
the radium in soil criteria in Criterion 6(6), to read:
\2\ The concentration of radium, as a result of byproduct
material, averaged over areas of 100 square meters, should not
exceed the background level by more than 5 pCi/g (0.19 Bq/g) in the
first 15 cm (6 inches) of soil, and 15 pCi/g (0.56 Bq/g) for every
subsequent 15 cm (6 inch) layer.
Byproduct material containing concentrations of radionuclides
other than radium in soil, and surface activity on remaining
structures, must not result in a total effective dose equivalent
(TEDE) exceeding the dose from cleanup of radium contaminated soil
to the above standard (benchmark dose), and must be at levels which
are as low as is reasonably achievable.
If more than one residual radionuclide is present in the same
100-square-meter area, the sum of the ratios for each radionuclide,
of concentration present to the concentration limit, will not exceed
``1'' (unity). A calculation of the peak potential annual TEDE
within 1000 years to the average member of the critical group that
would result from applying the radium standard (not including radon)
on the site, must be submitted for approval. If the benchmark dose,
before application of ALARA, exceeds 100 mrem/yr, the staff will
consult the Commission before approving the decommissioning plan.
This requirement for dose criteria does not apply to sites that have
decommissioning plans for soil and structures approved before the
effective date of this rule.
The final rule, ``Radiological Criteria for License Termination of
Uranium Recovery Facilities,'' requires the use of the soil radium
standard to develop a site-specific dose benchmark for the cleanup of
residual radionuclides, other than radium, at UR sites. The radium
benchmark approach ensures that the dose limit across the UR site will
be equal for all radionuclides (other than radon).
The NRC-licensed sites subject to the new rule currently include
four uranium mills (one operating, others in stand-by status), seven in
situ leach (ISL) facilities, and any new UR facility licensed by NRC
after promulgation of the rule (two ISL license applications are under
review at NRC, also in the Agreement States, several ISLs in Texas
could be affected by the rule). These sites are located in semi-arid
(7-15 inches (18-39 cm) of precipitation), high evapo-transpiration,
sparsely populated (1-5 people per sq. mile (0.4-3 per sq. km)) areas
of New Mexico, Utah, Wyoming, and Nebraska. The land use around these
facilities is predominately mining and ranching, and the potable water
aquifer is usually 100-200 feet deep. Also, many of the sites have
natural (in situ) uranium and/or radium deposits or mine pits that
create a wide range of radium, thorium and uranium background values.
Because of these unique properties and the specific regulations in 10
CFR Part 40, Appendix A, the UR facilities are exempt from the
decommissioning criteria in Part 20 Subpart E, as specified in Section
20.1401(a).
The benchmark dose applies to surface cleanup (buildings or the top
15 cm (6 inches) of soil) of radionuclides other than radium and it is
the estimated dose resulting from cleanup of areas to 5 pCi/g (0.19 Bq/
g) Ra-226 at that site. For the small areas requiring the use of the
radium subsurface soil standard, the estimated dose resulting from 15
pCi/g (0.56 Bq/g) Ra-226 at that site and for those areas, would be
used. The same concept of regulation (using a Ra-228 benchmark dose)
would be applicable to thorium mills, if any are licensed in the
future.
The draft guidance on dose modeling and implementation of the
radium benchmark approach was developed in conjunction with the final
rule and the SRPs under development for uranium mill site reclamation
and ISL licensing. The draft SRPs have already been published for
comment as NUREG-1569 (NRC, 1997) and NUREG-1620 (NRC, 1999). After
review of the comments received on the draft guidance, the final
benchmark dose guidance will be incorporated into the final SRPs for UR
facilities.
Draft Guidance: Standard Review Plan--Chapter 6
6.0 Decommissioning Plan for Soil and Buildings--The Radium
Benchmark Dose Approach
A mill reclamation plan, required for licensing or license renewal,
generally focuses on the tailings disposal cell and contains only brief
mention of anticipated decommissioning activities. The licensee submits
a detailed mill or ISL decommissioning plan and a soil cleanup/
verification plan for NRC approval at least six months before
decommissioning is to begin. The general requirements for a
decommissioning plan, and the remediation and verification of soil Ra-
226 contamination cleanup are addressed in Chapter 5 of the Standard
Review Plan (SRP). This chapter discusses the evaluation of the radium
benchmark dose approach for the cleanup of thorium and uranium,
specifically dose modeling and its application to site cleanup
activities that should be addressed in the decommissioning plan.
This chapter applies to those uranium recovery (UR) facilities
licensed by the NRC and subject to the new requirements for cleanup of
contaminated soil and buildings under 10 CFR Part 40, Appendix A,
Criterion 6(6) (as amended in 1999). The facilities that did not have
an approved
[[Page 17692]]
decommissioning plan at the time the rule became final are required to
reduce residual radioactivity, i.e., byproduct material, as defined by
Part 40, to levels based on the potential dose, excluding radon,
resulting from the application of the radium (Ra-226) standard at the
site. This is referred to as the radium benchmark dose approach.
This chapter would also apply to any future thorium processing
facilities and uranium heap leach operations, because Part 40 defines
uranium milling as any activity resulting in byproduct material. This
chapter also applies to any revised decommissioning plan submitted for
NRC review and approval, after the final rule is effective. However, if
a subject licensee can demonstrate that no contaminated buildings will
remain, and that soil thorium or total uranium levels are not
discernable from background, radium benchmark dose modeling is not
required. Other aspects of decommissioning are addressed in Chapter 5
of this SRP.
In order for NRC staff to evaluate the radium benchmark dose
modeling and the implementation of the modeling results, as proposed in
the building and soil decommissioning plan, an understanding of the
site conditions and site operations is essential. The required site
information should be provided by the licensee, or relevant portions of
previously submitted documents (e.g., environmental assessments,
license renewal, reclamation plan, and characterization report) should
be summarized and referenced. The information should include: (1)
processes used at the facility; (2) type and location of possible
contamination; (3) geologic and climatic data; and (4) surrounding land
use information (also see Section 3 of Inspection Procedure 87654).
6.1 Radium Benchmark Dose Modeling
6.1.1 Areas of Review
In implementing the radium benchmark approach, the licensee
calculates the peak potential dose for the site resulting from the 5
pCi/g (0.19 Bq/g) concentration of radium in the surface (top 15 cm (6
inches)) soil. The dose from the 15 pCi/g (0.56 Bq/g) subsurface radium
limit would be calculated for any area that may require subsurface
cleanup. The dose modeling review involves examination of the computer
code or other calculations employed for the dose estimates, the code or
calculation input values and assumptions, and the modeling results
(data presentation).
6.1.2 Review Procedures
The radium benchmark dose modeling review consists of ascertaining
that an acceptable dose modeling computer code or other type of
calculation has been used; that input parameter values appropriate
(reasonable considering long-term conditions and representative of the
application) for the site have been used in the modeling; that a
realistic (overly conservative is not acceptable as it would result in
higher allowable levels of uranium or thorium which would not be ALARA)
dose estimate is provided; and that the data presentation is clear and
complete.
6.1.3 Acceptance Criteria
The radium benchmark dose modeling results will be acceptable if
the dose assessment (modeling) meets the following criteria:
(1) Dose Modeling Codes and Calculations
The assumptions are considered reasonable for the site analysis and
the calculations employed are adequate. Reference to documentation
concerning the code or calculations is provided (for example, the
RESRAD Handbook and Manual (Argonne, 1993a and b)).
The RESRAD code developed by the U.S. Department of Energy (version
5.82, 1998) (see website www.ead.anl.gov/resrad/html), may be
acceptable for dose calculations because, while the RESRAD ground-water
calculations have limitations, this does not impact the UR sites that
have deep aquifers (ground-water exposure pathway is insignificant).
The DandD code developed by the NRC (version 1.0, August 1998, see
website ftp://nwerftp.nwer.sandia.gov/nrc/DandD/; also see the website
at http://techconf.llnl.gov/radcri/dose-top.html) provides conservative
default values, but does not allow for modeling subsurface soil
contamination, and does not allow calculation of source removal due to
soil erosion. Neither the RESRAD nor the DandD code would be adequate
to model the dose from off-site contamination, but codes such as GenII
would be considered.
If the code or calculation's assumptions are not acceptable for
site conditions, adjustments have been made in the input to adequately
modify these assumptions.
The RESRAD code assumes a circular contaminated zone. The shape
factor (external gamma, screen R017) must be adjusted for a non-
circular-shaped area.
The code or calculation provides an annual dose (total effective
dose equivalent (TEDE)) estimate (mrem/yr).
The DandD code provides the annual dose, but RESRAD calculates the
highest instantaneous dose. However, RESRAD results are acceptable for
long-lived radionuclides that do not move rapidly out of surface soils.
(2) Input Parameter Values
The code/calculation input data are appropriate for the site and
represent current or long-term conditions, whichever is more applicable
to the time of maximum dose. When code default values are used, they
are justified as appropriate (representative) for the site. Excessive
conservatism (i.e., upper bound value) is not used as this would result
in a higher dose and thus higher levels of uranium and thorium would be
allowed to remain on site.
Previously approved MILDOS code input parameter values may not be
appropriate, because derived operational doses in the restricted area
may be an order of magnitude higher than acceptable doses for areas to
be released for unrestricted use.
Site-specific input values are demonstrated to be average values of
an adequate sample size. Confidence limits are provided for important
parameters so that the level of uncertainty can be estimated for that
input value. Alteration of input values considers that some values are
inter-related (see draft NUREG-1549, Appendix C) (NRC, 1998a) and
relevant parameters are modified accordingly. The preponderance of
important parameter values are based on site measurements and not
conservative estimates. One or more models consider the annual average
range of parameter values likely to occur within the next 200-year time
period, for important parameters that can reasonably be estimated. Some
other considerations for the input parameter values are as follows:
a. Exposure Pathways and Scenarios for the Critical Group
The scenario(s) chosen to model the potential dose to the average
member of the critical group\3\ from residual radionuclides at the site
reflects reasonable probable future land use. The licensee has
considered ranching, mining, home-based business, light industry, and
residential farmer scenarios, and has justified the scenarios modeled.
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\3\ As defined in 10 CFR Part 20, ``the group of individuals
reasonably expected to receive the greatest exposure to residual
radioactivity for any applicable set of circumstances.''
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Based on one or more of these projected (within 200 years is
reasonably foreseeable) land uses to define the critical group(s), the
licensee
[[Page 17693]]
has determined and justified what exposure pathways are probable for
potential exposure of the critical group to residual radionuclides at
the site.
Dairies are not likely to be established in the area of former UR
facilities, and even if some milk cows were to graze in contaminated
areas, the milk would probably be sent for processing (thus diluted),
and not be consumed at the site. Therefore, milk consumption is not a
likely ingestion exposure pathway. Also, a pond in the contaminated
area providing a significant quantity of fish in the resident's diet is
not likely, so the aquatic exposure pathway may not have to be modeled.
However, the external gamma, plant ingestion, and inhalation pathways
are likely to be important.
The radon pathway is excluded from the benchmark dose calculation
as defined in Criterion 6(6) of Appendix A, to 10 CFR Part 40. This
also reflects the approach in the main decommissioning rule
(radiological criteria for license termination, Part 20 subpart E).
b. Source Term
If the RESRAD code is used, the input includes Pb-210 at the same
input value as for Ra-226. The other radium progeny are automatically
included in the code calculations. The chemical form of the
contamination in the environment is considered in determining input
values related to transport, or inhalation class (solubility in the
lung) for dose conversion factors.
c. Time Periods
The time periods for calculation of the dose from soil Ra-226
include the 1000-year time frame. The calculated maximum annual dose
and the year of occurrence is provided in the results.
d. Cover and Contaminated Zone
A cover depth of zero is used in the surface contamination model
and a depth of at least 15 cm (6 inches) for the subsurface model. The
values for area and depth of contamination are derived from site
characterization data. The erosion rate value for the contaminated zone
is less than the RESRAD default value because in regions drier than
normal, the erosion rate is less, as discussed in the RESRAD Data
Collection Handbook (Argonne, 1993a), and the value is justified. The
soil properties are based on site data (sandy loam or sandy silty loam
are typical for UR sites) and other input parameters are based on this
demonstration of site soil type (see RESRAD Handbook pages, 23, 29, 77,
and 105).
The evapo-transpiration coefficient for the semi-arid UR sites is
between 0.6 and 0.99. The precipitation value is based on annual values
averaged over at least 20 years, obtained from the site or a nearby
meteorological station.
The irrigation rate value may be zero, or less than a code's
default value, if supported by data on county or regional irrigation
practices (e.g., irrigation water is obtained from a river not a well).
The runoff coefficient value is based on the site's soil type, expected
land use, and morphology of the region.
e. Saturated Zone
The dry bulk density, porosity, ``b'' parameter, and hydraulic
conductivity values are based on local soil properties. The hydraulic
gradient for an unconfined aquifer is approximately the slope of the
water table. For a confined aquifer, it represents the difference in
potentiometric surfaces over a unit distance.
If the RESRAD code is used, the nondispersion model parameter is
chosen for areas greater than 1000 sq. meters (screen R014), and the
well pump rate is based on irrigation, stock, or drinking water well
pump rates in the area.
f. Uncontaminated and Unsaturated Strata
The thickness value represents the typical distance from the soil
contamination to the saturated zone. Since the upper aquifer at UR
sites is often of poor quality and quantity, the depth of the most
shallow well used for irrigation or stock water in the region is chosen
for the unsaturated zone thickness. A value of 18 meters (60 feet) is
typical for most sites and 15 meters (50 feet) for the Nebraska site,
but regional data are provided for justification. The density,
porosity, and ``b'' parameter values are similar to those for the
saturated zone or any changes are justified.
g. Distribution Coefficients and Leach Rates
The distribution coefficient (Kd) is based on the site's soil
physical and chemical characteristics. The leach rate value of zero in
the RESRAD code is acceptable as it allows calculation of the value. If
a value greater than zero is provided, justification for the value is
also provided.
h. Inhalation
An average inhalation rate value of approximately 8,395
m3/yr is used for the activity assumed for the rancher or
farmer scenario (based on Draft Letter Report, Sandia, 1998a). The mass
loading for inhalation (air dust loading factor) value is justified
based on the average level of airborne dust in the local region for
similar activities as assumed in the model.
i. External Gamma
The shielding factor for gamma is in the range of 0.33 to 0.55 (PG-
8-08, NRC 1994; DandD code screening default value), based mainly on
the type (foundation, materials) of the house likely to be built on the
site.
The time fractions for indoor and outdoor occupancy are similar to
default values in RESRAD and draft guidance developed for the main
decommissioning rule (NUREG/CR-5512, Volume 3, NRC, 1996b). For
example, the staff would consider fraction values approximating 0.7
indoors and 0.15 outdoors for a resident working at home, and 0.5
outdoors and 0.25 indoors for the farmer scenario.
The site specific wind speed value is based on adequate site data
(the average annual wind speed for the UR sites varies from 7 to 13 mph
(3.1 to 5.5 meters/sec)). The maximum and annual average wind speed are
also considered when justifying/evaluating proposed erosion rates.
j. Ingestion
Average consumption values (g/yr) for the various types of foods
are based on average values as discussed in NUREG 5512, Volume 3, or
the Sandia Draft Letter Reports (1998a and b), or are otherwise
justified. Livestock ingestion parameters are default values, or are
otherwise justified.
For sites with over 25 acres of contamination, the fraction of diet
from the contaminated area is assumed to be 0.25 for the farmer
scenario (Sandia 1998a), or is otherwise justified based on current or
anticipated regional consumption practices for home-grown food. Because
of the low level of precipitation in the UR facilities regions,
extensive gardens or dense animal grazing are not likely, so the
percentage of the diet from contaminated areas is likely to be lower
than the code default value.
Note that the default plant mass loading factor in the DandD code
can reasonably be reduced to 1 percent (Sandia, Draft Report, 1998c).
The depth of roots is an important parameter for UR licensees using the
RESRAD code. The value is justified based on the type of crops likely
to be grown on the site in the future. For vegetable gardens, a value
of 0.3 is more appropriate than the RESRAD default value of 0.9 meters
that is reasonable for alfalfa or a similar deep-rooted plant.
[[Page 17694]]
(3) Presentation of Modeling Results
The radium benchmark dose modeling section of the decommissioning
plan includes the code or calculation results as the maximum annual
dose (TEDE) in mrem/yr, the year that this dose would occur, and the
major exposure pathways by percentage of total dose. The modeling
section also includes discussion of the likelihood of the various land
use scenarios (reflecting the probable critical groups) modeled, and
provides the variations in dose (dose distribution) created by changing
key parameter values to reflect the range of dose values that are
likely to occur on the site. The section also contains the results of a
sensitivity analysis (RESRAD code can provide a sensitivity analysis
via the graphics function) to identify the important parameters for
each scenario.
Note: As indicated in Criterion 6(6), if a licensee submits a
radium benchmark dose result that is 100 mrem/yr or higher, the
staff will consult with the Commission before approving the
decommissioning plan based on this value.
6.1.4 Evaluation Findings
If the staff review, as described in this section, results in the
acceptance of the radium benchmark dose modeling, the following
conclusions may be presented in the technical evaluation report (TER).
The staff has completed its review of the site benchmark dose
modeling for the ________________ uranium recovery facility. This
review included an evaluation using the review procedures in the Title
II SRP (NRC, 1999), Section 6.1.2, and the acceptance criteria outlined
in SRP Section 6.1.3.
The applicant has provided an acceptable radium benchmark dose
model and staff evaluation determines that: (1) the computer code or
set of calculations used to model the benchmark dose is appropriate for
the site; (2) input parameter values used in each model are site-
specific or reasonably estimates; (3) the dose modeling information
includes adequate estimates of dose uncertainty.
6.2 Implementation of the Benchmark Dose
6.2.1 Areas of Review
The results of the radium benchmark dose calculations are used to
establish a surface and subsurface soil dose limit for residual
radionuclides other than radium, as well as a limit for surface
activity on structures that will remain after decommissioning. The
staff reviews the licensee's conversion of the benchmark dose limit to
soil concentration (pCi/g) or surface activity levels (dpm/100 cm \2\)
as a first step to provide cleanup levels. Alternatively, the licensee
can derive the estimated dose from the uranium or thorium contamination
(as discussed in Section 6.1.3) and compare this to the radium
benchmark dose.
The cleanup levels adequately consider the ALARA principle and the
unity rule to demonstrate that the Part 40.42 (k) requirements (the
premises are suitable for release and reasonable effort has been made
to eliminate residual radioactive contamination) can be met.
6.2.2 Review Procedures
The decommissioning plan section on cleanup criteria will be
evaluated for appropriate conversion of the radium standard benchmark
dose to cleanup limits for soil uranium and thorium and/or surface
activity concentration. The plan will also be examined to ensure
reasonable application of the ALARA principle to the cleanup guideline
values.
6.2.3 Acceptance Criteria
(1) The soil concentration limit is derived from the site radium
dose estimate. The modeling performed to estimate mrem/year per pCi/g
of Th-230 and/or U-nat follows the criteria listed in Section 6.1.3. In
addition, the U-nat source term is represented as percent activity by
49.14% U-238, 49.14% U-234, and 0.71% U-235, or is based on analyses of
the ore processed. For a soil uranium criterion, the chemical toxicity
is considered in deriving a soil concentration limit if soluble forms
of uranium are present.
Detailed justification for the inhalation pathway parameters is
provided, such as the determination of the chemical form in the
environment, to support the inhalation class.
The derived Th-230 soil limit will not cause any 100 square meter
(m \2\) area to exceed the Ra-226 limit at 1000 years (i.e., current
concentrations of 14 pCi/g Th-230 surface and 43 pCi/g subsurface, if
Ra-226 is at approximately background levels).
(2) In conjunction with the activity limit, the ALARA principle is
considered in setting cleanup levels (derived concentration guideline
levels). The ALARA guidance in draft Regulatory Guide 4006 is
considered.
In recent practice at mill sites, ALARA is implemented by removing
at least two more inches (5 cm) of soil than is estimated to achieve
the radium standard. (reduce any possible excess or borderline
contamination). At mills, it is generally cheaper to remove more soil
than to do sampling and testing that may indicate failure and require
additional soil removal plus additional testing.
(3) The unity rule is applied to the cleanup if more than one
residual radionuclide is present in a soil verification grid (100 m
\2\). This means that the sum of the ratios for each radionuclide of
the concentration present/concentration limit may not exceed ``1''
(i.e., unity).
(4) The subsurface soil standard, if it is to be used, is applied
to small areas of deep excavation where at least 15 cm (6 inches) of
compacted clean fill is to be placed on the surface.
(5) The surface activity limit for remaining structures is
appropriately derived using an approved code or calculation.
If the DandD code is used, data is provided to support that 10% or
less of the activity is removable; otherwise the resuspension factor is
scaled to reflect the site-specific removable fraction. Note that this
code assumes that the contamination is only on the floor, which can be
overly conservative. If the RESRAD-Build code is used, the modeled
distribution of contamination on walls vs. floor is justified.
6.2.4 Evaluation Findings
If the staff review, as described in this section, results in the
acceptance of the application of the radium benchmark dose modeling to
the site cleanup criteria, the following conclusions may be presented
in the technical evaluation report.
The staff has completed its review of the proposed implementation
of the benchmark dose modeling results for the ________________ uranium
recovery facility. This review included an evaluation using the review
procedures in the Title II SRP, Section 6.2.2, and the acceptance
criteria outlined in SRP Section 6.2.3.
The licensee has provided an acceptable implementation of the
benchmark dose modeling results to the proposed site cleanup activities
and staff evaluation determines that: (1) The cleanup criteria will
allow the licensee to meet Part 40.42(k) and Part 40, Appendix A,
criterion 6(6) requirements; (2) the soil and structures of the
decommissioned site will permit termination of the license because
public health and the environment will not be adversely affected by any
residual radionuclides.
6.3 References
Argonne National Laboratory (for the U.S. Department of Energy),
``Data Collection Handbook to Support Modeling the Impacts of
Radioactive Material in Soil,'' ANL/EAIS-8, April 1993a.
[[Page 17695]]
Argonne National Laboratory (for the U.S. Department of Energy),
``Manual for Implementing Residual Radioactive Material Guidelines
Using RESRAD, Version 5.0,'' ANL/EAD/LD-2, September 1993b.
Sandia National Laboratories, ``Review of Parameter Data for the
NUREG-5512 Residential Farmer Scenario and Probability Distributions
for the DandD Parameter Analysis,'' Draft Letter Report, January 30,
1998a.
Sandia National Laboratories, ``Review of Parameter Data for the
NUREG-5512 Building Occupancy Scenario and Probability Distributions
for the DandD Parameter Analysis,'' Draft Letter Report, January 30,
1998b.
Sandia National Laboratories, ``Comparison of the Models and
Assumptions Used in the DandD 1.0, RESRAD 5.61, and RESRAD-Build
Computer Codes with Respect to the Residential Farmer and Industrial
Occupant Scenarios Provided in NUREG/CR5512.'' Draft Report, October
15, 1998c.
U. S. Nuclear Regulatory Commission, ``Residual Radioactive
Contamination from Decommissioning,'' NUREG/CR-5512, PNL-7994, Vol.
1, 1992.
U.S. Nuclear Regulatory Commission, Office of Nuclear Material
Safety and Safeguards, Division of Waste Management, Policy and
Guidance Directive PG-8-08, ``Scenarios for Assessing Potential
Doses Associated with Residual Radioactivity,'' May 1994.
U. S. Nuclear Regulatory Commission, ``Residual Radioactive
Contamination from Decommissioning--User's Manual,'' NUREG/CR-5512,
Vol. 2, October 1996a.
U. S. Nuclear Regulatory Commission, ``Residual Radioactive
Contamination from Decommissioning--Parameter Analysis,'' (DRAFT FOR
REVIEW), NUREG/CR-5512, Vol. 3, April 1996b.
U.S. Nuclear Regulatory Commission, Office of Nuclear Material
Safety and Safeguards, ``Draft Standard Review Plan for In Situ
Leach Uranium Extraction License Applications,'' NUREG-1569, October
1997.
U.S. Nuclear Regulatory Commission, ``Decision Methods for Dose
Assessment to Comply With Radiological Criteria for License
Termination,'' Draft NUREG-1549, July 1998a.
U.S. Nuclear Regulatory Commission, Draft Regulatory Guide-4006,
``Demonstrating Compliance With the Radiological Criteria for
License Termination,'' August 1998b.
U.S. Nuclear Regulatory Commission, Office of Nuclear Material
Safety and Safeguards, ``Draft Standard Review Plan for the Review
of a Reclamation Plan for Mill Tailings Sites Under Title II of the
Uranium Mill Tailings Radiation Control Act,'' NUREG-1620, January
1999.
Notice of Opportunity To Provide Comments
The Commission hereby provides notice of opportunity for public
comment on the draft guidance addressing the radium benchmark approach
for decommissioning UR facilities. Written comments should be sent,
within sixty (60) days from the date of publication of this Federal
Register Notice (FRN), to the Chief, Rule and Directives Branch, U.S.
Nuclear Regulatory Commission, Washington, DC 20555-0001. Comments may
also be provided electronically on the NRC Uranium Recovery Branch
website and the final rule FRN may also be viewed (http://www.nrc.gov/
NRC/NMSS/URANIUM/guidance.htm).
FOR FURTHER INFORMATION CONTACT: Ms. Elaine S. Brummett, Uranium
Recovery and Low-Level Waste Branch, Mail Stop T7-J9, Division of Waste
Management, Office of Nuclear Material Safety and Safeguards, U.S.
Nuclear Regulatory Commission, Washington, D.C. 20555-0001. Telephone
301/415-6606.
Dated at Rockville, Maryland, this 1st day of April 1999.
For the Nuclear Regulatory Commission.
N. King Stablein,
Acting Chief, Uranium Recovery and Low-Level Waste Branch, Division of
Waste Management, Office of Nuclear Material Safety and Safeguards.
[FR Doc. 99-9036 Filed 4-9-99; 8:45 am]
BILLING CODE 7590-01-P
