ML19341A602
| ML19341A602 | |
| Person / Time | |
|---|---|
| Issue date: | 09/30/1980 |
| From: | Birchard G, Odonnell E, Robbins G NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS), NRC OFFICE OF NUCLEAR REGULATORY RESEARCH (RES), NRC OFFICE OF STANDARDS DEVELOPMENT |
| To: | NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS) |
| References | |
| REF-WM-7 NUDOCS 8101270260 | |
| Download: ML19341A602 (67) | |
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TRIP REPORT REVIEW 0F DOE / NATIONAL LABORATORY GE0 CHEMICAL RETARDATION PROGRAMS G
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' Office of Nuclear Material Safety 1
and Safeguards George Birchard Office of Nuclear Regulatory Research
. Edward O'Donnell Office of Standards Development 4
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i FOREWORD During the weeks of June 9 and June 23, 1980, NRC representatives visited five national laboratories to meet with researchers who are conducting investigations on geochemical retardation.
Laboratories visited were:
Argonne National Laboratory, Oak Ridge National Laboratory, Los Alamos Scientific Laboratory, Lawrence Berkeley Laboratory, and Pacific Northwest Laboratory.
An additional meeting was held on June 17, 1980, with U.S. Geological Survey Reston radiohydrol-ogy staff to obtain information on USGS retardation efforts.
Geochemical retardation is an important consideration in the development of a repository for high-level radioactive waste and the objectives of the visits werei (1) to obtain technical input for regulatory guidance on geochemical retardation; (2) to assess the state-of-the-art; (3) to observe experimental procedures and f
facilities; and (4) to obtain insights that would help formulate NRC research and technical support.
The primary purpose of the trip was to discuss with researchers their experimental work on geochemical retardation.
Of particular interest was identification of methods used and the sensitivity and reliability of experimental results. 'Also l
important was the opportunity for making firsthand observations of laboratory experimental facilities associated with geochemical retardation studies.
Other.
major objectives included:
obtaining the views of researchers on the state-of-the-art; obtaining information-helpful in formulating NRC research and-technical support; understanding the nature of the DOE geochemical retardation program l
(what labs are doing what, what progress has been made, and what future directions l
i.
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1 are being pursued); what field methods are available or are being developed to characterize sites; what level of effort is required to characterize sites; and establishing direct contacts between the NRC staff and researchers.
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ACKNOWLEDGMENTS The authors of the trip report would like to thank all those researchers we visited for their time, ideas, and openness.
We extend special appreciation to Dr. R. Jeff Serne, WRIT Program Manager, PNL, for coordinating the laboratory meetings. Also, particular appreciation is extended to Mr. -Carl Newton, Department of Energy Headquarters, Germantown, who expedited the administrative aspects of our visit.
iii
SUMMARY
AND OBSERVATIONS General Geochemical retardation, in addition to low groundwater flux, is one of the J
most critical processes involved in inhibiting radionuclide migration from a repository.
For this reason, the NRC staff has been following the Department of Energy (D0E) programs (particularly the Waste / Rock Interaction Technology Program or WRIT) that are devoted to characterizing retardation processes.
Much of the past work on geochemical retardation has not been rigorous, and the results'are highly uncertain.
Many factors influence retardation processes, and, to sufficiently understand all of them will require an enormous amount of well-coordinated research. The success or failure of geochemical retardation programs to establish credible data and methods (directly applicable to the evaluation of a repository site) will have a great impact on the licensing process.
The program must achieve general agreement among the scientific community on:
(1) what constitutes a suffu.ient program to characterize retardation properties of a site; (2) proper experimental procedures; (3) the applicability of laboratory data for field estimates of retardation; and l
(4) the levels of accuracy and confidence required in site determinations of radionuclide migration. Without general agreement on these points, ongoing and future research may not be producing results which are useful. More importantly, little credit may be given to.the geochemical retardation of a.
site during licensing without technical consensus.
l Significant progress has been made.in the measurement and understan'ing of the d
geochemistry of sorption and retardation of radionuclides by geological materials.
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The efforts of the past few years have been reoriented to focus on the scientific basis of this area of study.
In addition, researchers are focusing on anticipated repository conditions.
For example, many early experiments were conducted in an oxidizing environment.
However, the waste package will probably be subjected to reducing conditions after s epository closure and therefore many experiments are now being conducted to reflect migration under these conditions.
Researchers j
both in and out of the national laboratories are working to improve experimental protocol and to develop scientifically sound and relevant data.
These efforts are encouraged by the authors.
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Specific Observations The following are areas which we feel are of vital importance to the success of the DOE / National Laboratory effort to assess retardation:
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1.
The National Labs are using batch tests, column tests, and axial' migration-I tests to make laboratory Kd measurements.
These methods should be rigorously I
compared to ensure consistency of results.
Each of the laboratories has different procedures for batch and column tests.
Rigorous comparison of these procedures is needed so that improper or unacceptable procedures.
can be eliminated.
The accepted procedures should then be standardized.
In addition, the appropriate description of conditions for individual i
measurements must accompany the data so that the user community will i
i understand their limitations.
A plan should be adopted to identify-a l
tractable measurement strategy and to define acceptable techniques.
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2.
Several different technical approaches for characterizing retardation are being studied.
These include approaches that are either field oriented or laboratory oriented and a combination of both.
Considering the state-of-the-art, it is not possible to determine which technique is most appropriate.
It is important to verify that laboratory studies are applicable to the field, and to verify that the state-of-the-art with regard to retardation mechanisms is far enough advanced to allow extrapolation of laboratory results to the field.
Since field testing is extremely expensive thorcugh definition of the test and cutput, along with extensive coordination prior to the initiation of such a test, will be required.
3.
A plan needs to be adopted for quality control to standardize test results among laboratories.
It should incorpor.4te experimental guidelines, a program for evaluation of precision and accuracy of methods and an inter-laboratory comparison program.
This plan for standardization should respond to and encourage advances in the identification of reactions and mechanisms that are involved in a Kd measurement.- Research needs to be directed towards separating the geochemical variables in Kd experiments so that the results will be described for the proper set of variables.
For example. Kd measurements need to be made below the limits of the
. solubility of the radionuclide being analyzed.
Precipitation and ion-exchange mechanisms should not be combined in a Kd measurement.
The amount of geochemical research that will be required for licensing purposes, t
if geochemical retardation is to receive.due credit, is enormous, and the time vi
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is short.
The national program on geochemical retardation is in an embryonic stage and at present very diffuse.
Because of the comolexity of the geochemical issues, a management system analogous to that recently adopted by the Office of Nuclear Waste Isolation (ONWI) for waste forms (Materials-Characterization Steering Committee, Materials Review Board, Materials Characterization Center, and the Independent Measurement Standards Lab) may be the appropriate mechanism for achieving effective management and program direction.
The charters of the four waste form management organizations appear to show that their objectives and functions may be directly applicable to the needs of the' geochemical retardation program.
Both waste form and retardation programs need to identify, characterize, and develop a theoretical basis for the geochemical mechanisms and conditions which will impact waste containment and isolation. Although a few of the considerations and measurements will be exclusively waste form or site specific, the majority apply to both.
In addition, both efforts will a'
require an evaluation of geochemical mechanisms under varying physical and chemical conditions.
An objective of any such management structure should be i
to see that a consensus.will be achieved on the numerous complex geochemical 1
issuus, by providing a-verifiable technical basis.
The resolution of the issues by developing a rigorous technical basis, will ensure that the geologic L
site will receive due credit for radionuclide retardation during the licensing process.
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The following observations were also made:
4.
The effort to establish a data bank of Kd values is making significant progress.
Attention needs to be directed at assuring that the data storcd is accompanied by references to the method by which data was obtained, the precision and accuracy of the data, and appropriate warnings to the potential limitations of its use in analytical models. WRIT has made a significant contribution in this area.
They have been reviewing and documenting Kd data from their own work and that published by others to assure that the data is meaningful and was rigorously determined.
The Kd data bank should allow researchers to be able to determine the caveats in the application of that data.
However, the data stored will continue.
to be of questionable value until the types of issues raised in point 3 above are resolved.
5.
Even if the Kd data are properly measured in the laboratory, assumptions made in transport models using those data may be inappropriate.
For example, understanding solubility limits and particulate migration may be more important for modeling actinide behavior than Kd measurements.
The geochemical portions of risk assessment models need to be critically reviewed and improved by geochemists.
The models should be tested by comparison with geologic systems so that their relevance to long term-repository behavior can be established.
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6.
Tests to measure dist'ibution coefficients on crushed, powdered, and sieved rock represent a significant portion of the effort to establish Kd values.
Because the degree of sorption of radionuclides on the surface of crushed and powdered rock can be significantly different from the sorption on the face of a fracture, the application of these data to situations where fracture flow of groundwater is the dominant mechanism
-needs demonstration to confirm the applicability of data.
7.
Given the need for' relevant data of high quality in the licensing process, it is imperative that researchers understand that process and what is-required to meet regulatory standards as it relates to their ress:rch.
8.
An understanding of the chemistry involved in the study of geochemical retardation is still fairly elementary.
As.the mechanisms of sorption reaction and chemical interdependence are better understood, the complexity of the experiments will be increased.
There is a need to establish an understanding of the hierarchy of mechanisms and the conditions under which these factors are important.
At the same time, the complex chemical systems which will be found in the repository environment need more attention.
This will require a systematic approach to bounding problem.
This should include (but not be limited to):
- 1) selecting nuclides which require investigation; 2) detailing the chemistry an'd interactions of species in the repository which will interact with.these nuclides; and 3) assessing interactions.and retardation under near-field conditions.
ix
9.
Since the study of geochemical retardation is essential for. understanding HLW isolation, an increased peer review is recommended.
The findings should be widely circulated and the number of publications in professional journals should be increased.
The lack of proper peer review may greatly impede the progress of the program.
10.
The following areas appear to require additional technical efforts:
a.
The solubility of the actinides under anticipated conditions; b.
Improving thermodynamic data for actinides; c.
Actinide polymer migration; d.
The definition of source term species; e.
The effects of competing ions on sorption; f.
The meaning and applicability of laboratory data on Eh to the natural environment; g.
Surface retardation coefficients of fractured material; h.
Kd measurements for micas;
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Studies to determine if the kinetics of retardation processes are-important; j.
Long-term processes that may affect retardation; k.
Irreversible reactilns that may affect retardation; 1.
The characterizatioli of ambient and post closure repository geochemical conditions; m.
Near field assessments of retardation associated with waste / rock interactions at high temperature; x
n.
Whether or not organic substances in deep groundwater are important; o.
The development of field testing and representative sample collection techniques; p.
Natural analogue studies, such as Oklo, with emphasis on transferring information to assessing a repository; q.
Improved chemical models which incorporate other retardation mechanisms in addition to sorption; and r.
Interfacing geochemical data and models with risk assessment models.
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TABLE OF CONTENTS Page F0RWARD...............................................
i 1
ACKNOWLEDGMENTS........................................................
if
SUMMARY
AND OBSERVATIONS...............................................
iii 4
1-
- 1. 0 BACKGROUND........................................................
1 2
2.0' REVIEW 0F ONG0ING EFFORTS TO ASSESS GE0 CHEMICAL' RETARDATION.......
1 2.1 Argonne National Laborato ry.......................................
2 2.2 Oak Ridge National Laboratory.....................................
9-
- 2. 3 USGS Meeting......................................................
17
- 2. 4 Los Al amos Scienti fic Laborato ry..................................
21 i-2.5 Lawrence Berkel ey Laborato ry......................................
28 i
_ 2. 6 Pa c i f i c No r thwe s t Lab o ra to ry......................................
31 4
k' 1
4 i
l APPENDIX A List of Participants...............................
.A-1 4
l-APPENDIX B Agenda Handouts....................................
LB-1 4
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1
- 1. 0 BACKGROUND 1.1 Formulation of Guidance on Geochemical Retardation Geochemical retardation, as used here, refers to the collective geochemical processes which control radionuclide migration.
Retarding geochemical processes 1
include:
ion adsorption-desorption, absorption, ion exchange, ion filtration, acid-base reactions, solution precipitation reactions, oxidation-reduction reactions. The net positive effect of these processes is to reduce the source a
term of-radionuclides through solubility limitations, to reduce concentrations of nuclides along pathways, and to restrict radionuclide movement.
Character-istics used to describe retardation processes include solubility (Ksp), retarda-tion factors (Rf or Kf), and sorption coefficients (Kd, Ka, Rd).
Geochemical retardation, in addition to low groundwater flux, is one of the most critical processes involved in inhibiting radionuclide migration from a repository.
For this reason, the NRC staff has been closely following the Department of Energy (DOE) programs (particularly the Waste / Rock Interaction Technology Program or WRIT) that are devoted to characterizing retardation processes.
2.0 REVIEW 0F ONG0ING EFFORTS TO ASSESS GE0 CHEMICAL RETARDATION Each of the visits described below, were conducted as follows:
(1) An initial presentation was given by Gary Robbins on the purpose and scope of the visit (see Appendix B for an outline of the presentation).
It focused on how regui -
tory guidance on geochemical retardation fits into the broader regulatory framework and the major technical questions the NRC staff was seeking to answer by the visit; (2) Following the initial presentation by the NRC, research scientists gave presentations covering information within the scope of the meeting-(see Appendix B for ;gendas prepared by laboratories);
2 (3) Walk-throughs of laboratory facilities being used to assess retardation were conducted and discussions continued; and (4) Short wrap-up sessions were held.
Lists of participants at the meetings are included in Appendix A.
Copies of this document may be obtained from Don Alexander, High-Level Waste Technical Development Branch, NMSS, FTS 427-4177.
Salient points of information follow:
2.1 Argonne National Laboratory (ANL)
Dates:
June 10-11, 1980
Participants:
See Enclosure 1.
Organization Visited:
Chemical Division, Chemical Engineering Division.
Chemical Division I.
Overall Objectives and Approaches:
The main thrust of the ANL effort is to obtain retardation properties that are representative with respect to the far-field.
In this regard, dynamic sorption experiments are being conducted on whole rock columns rather than crushed rocks or mineral separates. A major objective is the comparison of laboratory results with field results.
Work is also being conducted on the diffusion of rrjionuclides through clays applicable to sea bed disposal and the performance of engineered barriers.
ANL also generates a number of tracers through cyclotron production for the-WRIT program. Major funding is through the WRIT and Sea Bed programs.
3 II. -Technical Studies:
1.
Nuclides:
Efforts are devoted primarily to the actinides (Pu, Am, Np).
They are also concerned with long-lived fission products (Tc, I).
2.
Materials: Whole rock column work requires the use of relatively permeable rocks.
These include permeable basalts and rocks from the WIPP site.
Solutions include pre-equilibrated aqueous phases and salt brine.
The sea bed work includes clays from deep sea cores.
3.
Processes: Work is concentrating on retardation.in.dyramic systems, diffusion in sea bed clays, effects of radiation on oxidatien state, and the solubility of actinides.
Emphasis is on far-field conditions, such as low temperature conditions.
t 4.
Sites:
Techniques applicable to any site are being developed.
However, some work is directly applicable to WIPP.
Also a study described in detail below is being initiated in conjunction with LASL and Sandia on fracture flow through welded tuff at the Nevada Test Site.
III. Major Points:
1.
Actinide chemistry in near neutral or. basic solutions is not well known.
Studies to date, however, reveal,that actinide retardation is primarily due to solubility. ~Thus, past Kd work 1
J
4 on the actinides may over estimate adsorption processes because of actinide precipitation.
The solubility of actinides such as plutonium is dependent on the valence state.
Pu(I ) is about 10X less soluble than Pu(III) and 250X less than Pu(YI).
2.
Considerable effort is being devoted to assessing the extent to which alpha radiation may affect the oxidation state of the actinides.
Work to date has found that at high concentrations (applicable if actinides are concentrated on particulates, mineral surfaces or as polymers), the oxidation state will increase.
Apparently radiation first causes the decomposition of water.
Hydroxyl groups can then oxidize actinides.
Reduced forms of Pu at high concentration are being encapsulated ano the rate of radiation induced oxidation is being observed.
Such experiments could then be used to extrapolate to lower concentrations and field conditions to determine the rate of oxidation and to assess if it may be significant in mobilizing the actinides.
3.
Past efforts at ANL have been devoted to modeling surface repositories (LASL liquid waste disposal sites in tuff) and the release of Pu and Am.
Assessments.of concentration profiles with depth were simulated and reasonable' agreements obtained with field observations.
This. effort exemplifies the way laboratory and field efforts can be correlated and laboratory efforts scaled up.
5 4.
Work using Cs on tuff has been conducted to assess why substantial differences have been reported between desorption-adsorption Kds (absorption Kds being generally higher).
One postulate is that the reaction is not completely reversible. Work at ANL, however, indicates this theory may not be accurate.
Differences between adsorption and desorption may be the result of experimental 4
i error in that final solution chemistry has not been fully taken into account.
l 5.
Work on Kds of Am and Pu using basalt reveals-that even at extremely low initial concentrations, precipitation occurs.
For example, the solubility _of Am in solutions studied.is on
-12 the order of 1x10 molar.
Thus, Kd values are not representing adsorption or ion exchange but rather solubility. -Values for 3
the actinides in'the literature are generally reported as 10 4
or 10 ; but since solubility limits are often unaccounted for, these may be too high.
Under more controlled conditions, it i
appears that Kd values are on the order of 10 to 100.
6.
Work on the diffusion of actinides in oceanic clays'and silts as well as on clays'potentially useful for backfill'at WIPP_is in progress. A static system is employed to study diffusion.
It consists of sealing clays in'a tube, which_is; half spiked!
with a tracer.
Diffusion coefficients are calculated by measuring the concentration gradient profile and through the'use of a diffusion model.
Experiments with Am and-Pu reveal no diffusion
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6 up to a year into the experiment.
Upper bound calculations of
-10 2
diffusion coefficients are on the order of 10 cm /s for Pu
-5 and Am, 1x10 for I and 1x10-6 2
cm /s for Na.
Measurements of concentration profiles are obtained by gamma and X ray counting of scraped samples on filter paper or slicing frozen thin sections.
7.
Nevada Test Site (NTS) Field Test.
A joint Argonne/LASL/Sandia field test is in the planning stages.
The objectivas are to assess whether laboratory results can be extrapolated up to a scale of meters to tens of meters and to develop techniques for site characterization.
The program is for a duration of 3 years, starting in June 1980 at a total budget of 4.5 million dollars.
Between June and August 1980, an experimental plan will be presented to ONWI for review.
The experiment will take place in NTS G-tunnel, in the welded tuff saturated zone, and will consist of locating and using a horizontal fracture as a chromatographic plane.
The fracture will be sealed off and tracers injected.
Subsequently, the fracture will be cored out and analyzed.
Costs appear to be mostly for equipment drilling, and cleaning up radionuclides.
Following the experiment, all radioactivity is required to be removed.
Horizontal cracks are sought to reduce the effect of gravity on flow.
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7 Chemical Engineering Division I.
Overall Objectives and Approaches:
In parallel with the Chemical Division effort, the goal in the Chemical Engineering Division is to be representative.
Emphasis is on kinetics of retardation reactions and experimentally simulating viable scenarios.
Work is primarily funded through the Basic Energy Program. Work on'WIPP is being funded to assess fracture sealing in salt.
II.
Technical Studies:
1.
Nuclides: Work has addressed Cs because of its relatively simple behavior.
2.
Materials: Adsorption in clays is being' studied in column experiments.
4 3.
Processes: Work is concentrating on the kinetics of sorption processes in context of flow rates, high temperature (up to 200*C) effects, simulating repository environments from leaching to nuclide migration through the far-field.
4.
Sites:
The retardation work is generic.
III. Major Points:
1.
' Previous column work using different column elution' velocities has revealed that kinetics of adsorption reactions and dispersion may produce a fast moving chromatographic front ahead of the i
.u
8 average chromatographic peak predicted using simple and ideal chromatographic theory.
Thus, performance analysis may underesti-mate the initial arrival time of radionuclides and early-on concentrations of radionuclides.
2.
It is thought that different elements may have different reaction rates.
Thus, even if one element behaves ideally, others might not.
It is expected that in the field, due to kinetics, equili-brium may not be achieved.
3.
Efforts are under way to relate experimentally determined column Kd values with batch Kd values.
Relationships are being developed that relate the time of batch experiments to flow rate in a column, e.g.,the fractional way to equilibrium vs. Kds for different flow rates.
Batch Kd values may be an upper bound.
4.
In rsal solutions competing ion effects, such as Rb competing with Cs for exchange sites, may be very significant.
These effects have not been quantified.
5.
As part of the effort to perform representative tests, efforts are underway to develop an experimental facility which will model leach and transport scenarios from a repository.
The experimental set-up will consist of a closed system containing a waste form, engineered barrier and rock column on a single line.
The system will permit a host of_ scenarios to be modeled
)
9 including control of input solutions, temperatures and gradients, pressures, flow rates, waste forms (which will leach at represen-tative rates resulting in representative initial solution concentrations), and effectiveness of engineered barriers and host rocks (solid columns or fractured) to retard migration.
Future efforts are devoted to the further development of the system, narrowing bounding scenarios, and defining parameters to test.
2.2 Oak Ridge National Laboratory Dates:
June 12, 13, 1980
Participants:
See Enclosure 1.
Organization Visited:
Environmental Sciences Division, Chemistry Division, Actinide Chemistry Division Environmental Sciences Division I.
Overall Objectives and Approaches:
Major program efforts at the Environmental Sciences Division are outside of the WRIT program.
Efforts mainly entail assessing radionuclide biogeo-chemistry and environmental chemittry through studies of contamination, biological uptake and assessing the speciation of transuranics from shallow land burial sites. WRIT program efforts have included research on soil thin layer chromatograms as an alternative method to batch Kd tests. With respect to a repository, research on actinide and transuranic speciation in the environment, and technetium reduction, is particularly important.
10 II.
Technical Studies:
1.
Nuclides:
Efforts are concentrating on the behavior of Tc, U, Pu, and Np under environmental conditions.
b 2.
Materials:. Experiments primarily deal with aqueous solution chemistry.
3.
Processes:
The major efforts in this program related to retarda-tion entail assessing speciation, oxidization-reduction reactions, and the effectiveness of substances at reducing Tc.
4.
Sites:
Studies are generic.
III. Major Points:
1.
Efforts to date indicate that the ferrous ion is.a powerful reductant which will control the reduction of technetium from the +7 state to the +4 state, making technetium highly insoluble.
Work is underway to assess the effects sulfides have on ferrous l
ion concentration and in turn on technetium solubility.
2.
With respect-to actinide. chemistry under environmental conditions,.
a good deal of fundamental aqueous chemistry is still needed.
Actinide chemistry under environmental conditions appears complex and experimentally difficult to control. :For example, the uranium system is highly sensitive to carbonate complexing, thus making' solubility measurements difficult.
Neptunium-
11 appears strongly complexed by phosphate.
Pu sorption experiments using batch techniques have resulted in an order of magnitude variation in replicate determinations.
This is believed to be due to the lack of rigorous experimental control of tracer species.
It appears experiments have been performed using Pu(IV) tracers under conditions where Pu(V) is stable resulting in mixed Pu species which behave differently.
Experiments indicate that during the initial phases, Pu(IV) is converted to Pu(V).
Discrepancies are also being found between thermodynamic predictions of species and measured species.
Pu also appears sensitive to carbonate complexing.
3.
Eh is a critical parameter with regard to actinide speciation.
However experimental methods to control Eh and measure Eh are majorproblems.
Many experiments in the past using N ' N, and 2
2 low 0 Partial pressure or vacuum conditions to generate reduced 2
conditions may not truly create reduced environments.
Solutions must have an electromotive couple with reducing agents to actually be reducing agents to substances in solution.
Also, considerable uncertainty exists in measuring and calculating the Eh.
There are questions as to whether an electrode is measuring more than its immediate environment or reactions on its surface.
Environmental Sciences Division is using multiple methods (Eh sensitive dyes, electrodes, and calculations) to assess consistency among predictions and measurements.
12 Chemical Division I.
Overall Objectives and Approaches:
The Chemistry Division is the division primarily focusing on geochemical retardation. Major support is through the WRIT program.
Related work is also being conducted through an enhanced oil recovery program.
In contrast to the whole rock dynamic approach of Argonne, the ORNL approach consists of the systemmatic study of retardation properties of classes of minerals under a wide range of environmental conditions.
The major objective of this approach is to assess whether the retardation capacity of a rock is equivalent to the weighted sum of retardation capacities of its mineral components.
Most of the research is being done using the batch method, although they have conducted some closed system column and axial filter experiments.
II.
Technical Studies 1.
Nuclides:
Adsorption experiments are being conducted that focus on mechanisms so that nuclides with simple, understandable behavior are being stressed, such as Sr, Cs, Eu (as an analogue for Am), I, and Tc.
2.
Materials:
Emphasis is on the sorption of clays including montmorillonite, kaolinite, illite, attapulgite, and oxides and hydrous oxides including alumina, gibbsite, hematite.
Low capacity sorbents, silica and Zr0, are also being studied as 2
controls.
A number of rocks are also under consideration.
These include anhydrite, dolomite, shale, granite, basalt,.and
13 limestone.
Aqueous phases being studied range in composition from.01 to 5 molar Nacl and CaCl, and have ph values from 2
5 to 10.
l 3.
Processes:
Processes being studied include:
(1) whether the retardation properties of mixtures of minerals can be predicted from individual mineral properties; (2) the relation between exchange capacity and retardation coefficient; (3) sorption as I
a function of ph; (4) sorption as a function of oxidation state, complexing agents, surface area, temperature, etc.
1 a
4.
Sites:
Efforts are generic.
l III. Major Points:
l 1.
Both retardation experiments and autoradiographs indicate retardation is dominated by minor mineral components including
'the clays, oxides, and hydrous oxides.
2.
The work at ORNL emphasizes the study of mechanisms and exemplifies the enormous number of measurements necessary to systemmatically i
and rigorously define retardation properties of relatively simple systems.
3.
With respect to verifying methods, work at-ORNL using differeni I
. techniques, such as batch testing, column tests and an axial l
14 filter method, for simple systems results in approximate agreement among these methods.
4.
With respect to developing alternative techniques for measuring retardation, ORNL has developed an axial filter method.
The method consists of introducing a tracer into an apparatus containing a mineral slurry which is agitated by a spinning filter.
Results to date appear to agree with batch tests.
5.
ORNL has devoted significant effort to the determination of Kd values as a function of pH.
Work to date indicates adsorption of cations (Cs, Sr) increases with increasing pH and anions decrease with increasing pH.
Kd values for cations from pH 5 to 9 may increase over several orders of magnitude.
6.
Another area emphasized is.the det9rmination of whether effective sorption coefficients of mineral mixtures can be predicted from retardation properties -of individual' minerals by weight %.
Such a prediction appears critical in terms of extrapolating laboratory results to the field and to real rocks.~ For Sr using mixtures of montimorillonite and illite, linear relation-i ships are obtained on plots of.Kd.vs. % montimorillonite/ illite..
i For Sr'using Zr0 and'SiO2. mixtures, linear relationships are 2
l also obtained but are more scattered. Work using mixtures of i
tracers (Cs, Sr) and minerals have alsoLresulted in~ linear l
relat.ionships. Work using Sr and illite / alumina mixtures, l
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7.
ORNL plans to concentrate more on solution chemistry and in particular, they plan to investigate electrochemical methods as a means to control valence states.
Eh is recognized as a critical parameter.
However, they also recognize the difficulties in controlling Eh, measuring it and interpreting such measurements.
It was stressed that using reduced oxygen conditions does not necessarily produce reducing conditions.
Future efforts are also anticipated to explore the kinetics of reactions as well as using a closed system to control Eh and pH.
Actinide Chemistry Division I.
Overall Objectives and Approaches:
Complimenting the Chemistry Division effort, the Actinide Chemistry Division is developing autoradiography techniques.
II.
Technical Studies:
1.
Nuclides:
The autoradiography work deals with the actinides, Am, Np, U, Pu.
2.
Materials:
The autoradiography technique that has been developed has been tested using granite from Climax Stock at the Nevada Test Site.
16 3.
Processes:
The present technique permits qualitative determinations of which minerals are dominating adsorption.
The technique is very useful in verifying chemical Kd tests.
4.
Sites: Generic.
III. Major Points:
1.
The autoradiography technique developed consists of a polished section of rock which is dipped into a solution spiked with radionuclides.
Subsequently, an autoradiograph is made by exposing sensitive film to the thin section.
The technique developed has the capability to control environmental conditions, such as Eh.
2.
Autoradiographs of the Climax Granite indicate that the clays, oxides, and micas dominate sorption.
3.
Efforts are underway to develop a position sensitive detector to quantitatively assess the amount of materials adsorbed.
4.
Observations of actinide sorption on Climax Granite show that under anoxic conditions, sorption is very preferential 1
on the clays, oxides, and micas.
Under aerobic conditions, there appears to be a loss of preferential sorption.
i i
17 4
5.
As a note, the Actinide Chemistry Division is workirg on a number of activities related to waste disposal inc'uding:
l radiation damage to clays, developing synthetic actinide minerals (potential waste forms) and leach tests.
2.3 U.S. Geological Survey (USGS)
Date: June 17, 1980
Participants:
See Enclosure 1.
Organization Visited:
Radiohydrology Branch, Reston, Virginia I.
Overall Objectives and Approaches:
The meeting with the USGS was held to obtain views on the state of the art of geochemical retardation.
Also, information was sought on how USGS retardation programs, as cited in the DOE /USGS Earth Science Technical I
Plan, relate to the WRIT program.
The Earth Science Technical Plan outlines two USGS geochemical programs.
The first being conducted in Reston, deals with redox reactions involving the actinides.
The second, out of the Denver office, deals with the geochemistry I
of the transuranics.
Both efforts are funded by the USGS and are outside the WRIT program.
II.
Major Points:
1.
The redox program currently entails an assessment.of the chemical literature dealing with Eh.
Major topics being explored include:
~
18 a.
Can a redox potential be defined for systems in disequili-brium? At oresent, it is not clear if it can.
b.
Because of disequilibrium conditions in the field, it is not clear what Eh measurements mean, c.
Assessments of redox potential require assessing the interactions of specific' species in solution rather than taking simple Eh measurements.
d.
There appears to be little information on Eh at elevated temperatures.
2.
The actinide chemistry work is being conducted by Jesse Clevelands USGS Denver.
This effort entails assessing the migration of actinides at Maxey Flats and Rocky Flats, and deriving basic chemical information primarily on plutonium in the natural environment.
Preliminary results indicate plutonium may migrate as a colloid and in ionic form.
3.
Concerning the state of the art, the following comments were mcde:
a.
Approaches to Retardation Characterization -- In contrast to the ORNL building block approach and sonewhat more in parallel with ANL, it was suggested that retardation characterization begin with in-situ tracer tests, then
l q
19 4
4 proceed to laboratory investigations using real rocks and groundwater to develop a detailed understanding of mechanisms.
In terms of practicality, it may not be possible to understand all the actual processes in combination that contribute to 1
l retardation.
Field testing, particularly fracture testing, 3
may be the means to obtain more representative retardation a
parameters. With respect to nuclides to be studied, it q
was suggested that 10 CFR Part 60 be considered.
r'o r.
a.v. ample, short-lived nuclides, given the waste package t
criteria, would only be released under a. failure scenario; e
and as such, retardation parameters should be determined I
simulatirg such failure conditions.
i 4
a b.
In-Situ Testing -
In situ testing is considered critical.
i It was stressed that there is a need to develop and run experiments in-situ at specific sites.
It appears there-has been little development concerning just what should be done at a specific site, what tests should be performed,.
and equipment developed.
Also, there is a need to develop methoos to avoid, drilling contamination.
In terms of in--
situ testing,-a question was rc' sed as to whether the NRC would permit the'use of radionuclides at a site.
Could such use compromise the licensability of a site? 'It was i
suggested.that stable; isotopes and stable chemical analogues be used if this was a problem.
t f
}
l L.
i i
20 c.
Standarization -- The'need to develop standards for retarda-l tion experiments was stressed.
This would involve the development of standard solutions and rn ks, as well.as a lot of work on interlaboratory comparisons.
)
d.
Bounding Techniques -- Several ideas were expressed in l
terms of bounding retardation parameters.
Kd determin-ations could be made on a wide range of materials under a wide range of conditions to develop a "world wide" distri-bution.
Then, the lower Kd limits could'be used.
Another approach could entail concentrating efforts on a few-l representative-sites and choosing the lowest values deter-mined.
Another method is to draw upon natural analogues such as Oklo and manmade analogues such as low-level. sites
'which would represent worst case conditions, e.
. future Technical Needs -- There was a general view that-l progress' in the national program is being made.
Particular i
areas include programmatic improvements, an increased
-concern for' rigor, and increased geochemical _ perspective a'id increased concern for interlaboratory comparisons.
l l
1 Several' areas were found to need addition'al effort..Those were:
competing ion effects and surface sorption work (as-opposed.to mass sorption). 3In regard to chemical models
-for. predicting chemical changes; a problem was noted that l-l
(
r
g I
I i
1 21 l
{
different models will predict very different results, q
With respect to the influences of organics on retardation, i
agricultural literature contains a wealth of information.
t
]
However, organics may not be a problem because of their very low concentrations in deep groundwater.
l 2.4 Los Alamos Scientific Laboratory (LASL) 1 Dates: June 23-24, 1980 t
Participants:
See Enclosure 1.
Organizations:
Chemistry and Nuclear Chemistry Division I.
Overall Objectives and Approaches:
l Retardation e'.-forts at LASL focus on five areas.
They are primarily l
devoted to Nevada Test Site repository site investigations funded through j
the DOE Nevada Operations Office.
Retardation efforts also include t
j studies of radionuclide migration related to nuclear weapon.s testing, t
Waste Rock Interaction Technology,(WRIT) generic work (which is a small i
part of_the LASL program), the LASL/Argonne/Sandia fracture test and studies of Oklo for the Office of Nuclear Waste Isolation. Work on-granite and argillite is fur.ded by WRIT.
Past. WRIT work also included-input.to the Hainesville salt dome modeling study.
The general LASL approach is a' scaling one. ~ Work is directed at scaling l-laboratory batch tests.to column-tests to fractured a'nd solid rock column j
tests using large rock blocks to in-situ field tests..The major objective is to identify'and understand the processes that govern retardation.
i J
.m.
22 II.
Technical Studies:
1.
Nuclides:
LASL is studying both fission products and actinides.
Efforts are concentrating on Sr, Cs, Ba (as an analogue for radium), Ce, Eu, Tc, U, Pu, and Am.
2.
Materials: Although LASL is giving major emphasis to tuff because its investigations are focused on the Nevada Test Site, it is also being funded by WRIT to investigate granite and argillite. Actual groundwater is being used in these studies.
3.
Processes: A wide range of processes and mechanisms are being studied by LASL.
They include:
release mechanisms and leaching, retardation as a function of water chemistry, colloid formation, pH, redox potential, speciation, kinetics, mineralogy, competing ion effects, solubility, temperature, etc. Work is also concerned with diffusion iato grains.
4.
Sites:
Emphasis is on NTS.
LASL-has also been working at Stripa in conducting fracture injection tests as part of a two year project. -Natural analogue studies are also being conducted at Oklo and in Canada.
III. Major Points:
1.
Research is being cc.qducted on uranium leaching from fuel pellets. Work to date has revealed that inert gas environments do not induce reducing conditions.
Under such conditions, uranium concentrations are very high.
Addition of palladium
23 black, a reducing agent, causes several orders of magnitude reduction in concentration.
00 ppears to have a negative 2
solubility temperature coefficient. Wit'i respect to leaching, fuel pellets appear to dissolve congruently for most nuclides.
However, abnormally high concentrations of Cs have been detected outside of fuel pellets along grain boundaries.. Future fuel pellet leaching experiments include investigating low partial pressure 0 conditions, pH 6-9, elevated temperature, assessing 2
the effects of radiation and the rate of diffusion of Cs in U0 '
2 2.
With respect to actinide chemistry, the' need for determining the solubility of actinides under environmental conditions was stressed.
There has been in the last few years a realization of the complexity of actinide behavior under. repository conditions.
It was noted that the interlaboratory round robin study to -
compare Kd determinations revealed differences for Pu on the:
order of s'everal orders of magnitude.
It was pointed out that-faulty blank corrections appear to have been made.
Corrections using blanks (no solid phase) results in over correction for wall adsorption.. With rock present,.the. rock dominates as-the~
sorbing phase because of_its surface area.
A'dditionalifactors that may'be.important in' deriving actinide Kd values ~ include using new tubing because scratched surfaces introduce. increased surface area, and filtering..Itappears.somefiltersmayactl
~
24 as strong ad:orbers of actinides.
Additionally, the actinides may form positive, negative or neutral polymers.
Filtering batch Kd solutions appears to reveal that Pu and Am are in polymer form and still pr'.sent in solution after centrifuging several times.
Further work is being pursued on the migration of actinide polymers and colloids.
3.
LASL has developed a microautoradiography technique.
The technique is capable of detecting alpha radiation tracks.
It not only has the utility of autoradiography but the capability of detecting polymers.
Work thus far indicates minerals dominating sorption are clays, zeolites, glasses, and altered feldspars.
The formation of Np, Pu, and Am polymers in Kd experiments have been observed.
Future efforts involve using microautoradiography on core material used in a Xd experiment.
4.
As a note, Nevada Test Site site characterization has proceeded to a point where a 4" outer diameter hole has been drilled to 6,000 feet at Yucca Mountain.
5.
In terms of Kd measurements, atrary to other approaches which radionuclide assay solutions alone, LASL assays both the solid -
and solution.
This technique avoids blank correction problems.
Additionally, it can be used as an internal check on solution only assays.
J 25 i
I I
f 6.
Batch Kd studies conducted generally have reproducibility of about 20%. Major effects noted in batch experiments include:
sorption appears to increase slowly with time (this may be due to the continuous grinding of samples as they are agitated);
desorption coefficients are generally highor then sorption coefficir;ts for Sr and Cs but the reverse for Pu and Am; temper 6 cure dependence is a function of element and rock type (for some elements Kd increases with temperature, for others it remains the same or decreases); redox conditions are important for U and Tc; sorption decreases with ionic strength for Cs, Sr, and Ba, but increases for Ce and Eu (this may be due to colloid formation).
t 7.
Column studies (crushed rock) are being conducted msing'Sr, Cs, Ba, Ce, Eu and Tc with pretree+ad water having pH v& lues between 7.5 and 8.8 at flow rates of 1 to 50' meters / year.
Tritium and iodine are used to measure water velocity.
Column experiments-are conducted so that there is upward flow.
Measurements using Cs and Sr made-at different flow rates appear not to be influenced by kinetics.
This is in contrast to the ANL work. The difference I
may be due to how tracers are introduced. -ANL uses a continuous feed while LASL uses an injection slug feed. ;However, the l
column experiments do exhibit some peculiarity.
Although Sr l
and Ba exhibit normal ^ peak behavior, Cs elution amounts to a constant concentration-dribbling (no peak is observed)
I
b 26 Ceiparisons have been made between latch Kd and r.clumn experi-l ments. Agreements are on the order of 2 to 3 for Sr.
- However, for Cs, determinations only agree when the Kd is low.
i 8.
Whole rock and fracture column experiments are under development using granite and tuff.
Column experiments will~be conducted at anticipated confining pressures (1,000 psi) and driving 1
pressures of 30 psi and up to several thousand psi for tuff and granite.
Because of the general low permeability of the tuff 2
and granite, difficulties have arisen in_ developing good' seals.
j Also, difficulties arise in controlling flow rate along fractures.
I 9.
Field testing has been ongoing since 1974 on radionuclide migration from the Cambric shot cavity using pump tests to-create hydraulic gradients and to leach radionuclides. The Cambric shot took place in 1965 and was a.75 kiloton explosion.
I It resulted in a_10 meter radius cavity at-300 meters depth.
The work relates-to repository development in several ways.
Techniques are being used to isolate boreholes at varying i
i
' depths to collect' samples Transport models are'being used to predict migration.
Laboratory batch tests are being conducted I
. in conjunction with pump tests to help verify laboratory results.
Work to date indicates most radionuclides'have been contained in the fused zone.. Sophisticated hydrologic modeling of tritium migration doesn't agree'with observed migration.
Insteac, a-v
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e.- s y
e a
+n y
m ye g.
- n me g~
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27 simple radial flow model gives better results.
Kd values calculated from pump tests, in general, are high.
10.
The LASL/Sandia/Argonne field test (see tection 2.1), and its objectives were reviewed.
Some additiona? notes here:
LASL has recommended NRC participate in the Jul/ program review meetings.
11.
Complimenting the laboratory and NTS field work, studies of Oklo as a natural analogue to a repository are ongoing.
Present efforts have involved collecting core samples traversing one of the reactor zones.
Geochemical analysis emphasizes the migration of Tc and Ru.
O and Po migration are also being studied as a means of detecting flow oaths.
Results indicate Tc fractionated from Ru within one millit., years af ter the reactor stopped (this implies early migration of Tc).
The relative tendency to fractionate from U as determined at Oklo has the following trend in increasing order:
Rare earth elements < Ru < Tc < Mo.
Future wo'rk entails analysis of additional samples, a mass balance assessment to ascertain what nuclides and what quantities have migrated and a determination of the Oklo flow paths.
Another' analogue investigation has been initiated on a uranium ore body at Key Lake, Saskatchewan.
28 2.5 Lawrence Berkeley Laboratory Date:
June 25, 1980
Participants:
See Enclosure 1.
Organizations:
Geosciences Division, Molecular Materials Research Division I.
Overall Objectives and Approaches:
Individual researchers at LBL are working on a number of projects related to repository development.
Efforts related to retardation encompass Rockwell Hanford basalt investigations, environmental geochemistry studies supported through DOE Basic Energy Sciences Program, 0WNI funded studies on groundwater dating and actinide chemistry, and WRIT program sorption studies.
With respect to retardation two main objectives are stressed.
These are:
under-standing sorption processes and developing a capability to predict 1
and model near-field retardation.
II.
Technical Studies:
1.
WRIT Studies:
The WRIT program at LBL consists of two parts:
batch testing is being conducted primarily on clays assessing mechanisms of sorption as a function of such variables as pH, ionic strength, tracer concentrations, etc.
In regard to assaying solids, a major question was raised regarding whether such measurements are accurate
'given the inability to remove all the solution from the.
solid.
Complementing the batch tests, a computer checical model (a modified version of MINEQL) incorporating surface sorption reactions has been developed to predict Kd values.
m
~
29 l
2.
Hanford Geochemical Studies:
i a.
Geochemical studies related to the Hanford site I
entail characterizing the Hanford basalt, its major and accessory minerals as well as those lining or i
filling fractures in the basalt.
Chemical models are also being used to predict near field reactions over the long term.
Reactions being studied include dissolutioning, precipitation and formation of secondary minerals.
Simulations have been conducted on the j
formation of minerals in fractures to predict what chemical reactions might occur along fractures and what secondary minerals might form.
b.
A chemical transport model, applicable to the near I
field and engineered barriers, is being developed.
l The objective is to incorporate into a transport model geochemical reactions such as sorption, precipita-tion, dissolutioning, speciation, temperature, and kinetics.
The model-is in the process of being, programmed.
It' presently considers sorption and speciation and represents coupling of new work with l
models developed for the geothermal program.
In l
l conjunction with the model work, thermodynamic data pertaining to ion exchange reactions is being tabulated.
Data'is being collected on both radioactive elements I
30
]
and stable daaghter products formea.
The stable elements may influence exchange chemistry.
3.
Irreversible Reactions:
As part of the DOE Basic Energy Sciences program, studies of chemical transport in natural systems are being conducted.
Theoretical studies are being conducted on irreversible sorption reactions.
Consideration is being given to developing equations to treat nonequilibrium reactions using kinetic rate laws and diffusion laws.
4.
Uranium Disequilibrium:
Studies of uranium disequilibrium using ultra-sensitive mass spectrometry are being conducted as a means of dating groundwater, assessing aquifer pathway processes, and assessing whether fracture systems are connectad.
Equipment at LBL permit high resolution, raasurement 9. small sample quantities, and is capable of measuring nanegram quantities or uranium or less.
This capability has potential with respect to deep hole remote sampling and in-situ small sample collection.
Deep hole samplers are under development.
5.
Actinide Chemistry:
The actinide chemistry program _is supported through the ONWI technology assessment'prograr..
The program objective is to determine actinide. thermodynamic
e 31 data at near neutral pH conditions.
Techniques to be used include electrochemical methods and Raman spectrometry.
Work is concentrating on Pu, Np, U, and Am.
As stressed at the other labs, actinide chemistry at near neutral pH is poorly known.
Existing thermodynamic data are highly uncertain and inconsistent.
Thus far, efforts have entailed obtaining equipment and formulating analytical methods.
2.6 Pacific Northwest Laboratory Dates: June 26-27, 1980
Participants:
See Enclosure 1.
Organizations: WRIT program task leaders and PNL researchers, BWIP task leaders and researchers.
The meeting at PNL focused on three areas:
(1) PNL retardation studies supported by WRIT and BWIP, (2) BWIP Rockwell Hanford retardation work, and (3) programmatic aspects of the WRIT program.
PNL Retardation Studies I.
Overall Objectives and Approaches:
Retardation research at PNL stresses the study of adsorption mechanisms, the influence of laboratory technique.c on results, and actinide chemistry.
The basic approach is one of systcmmatic laboratory study of mechanisms as a means of extrapolating to repository environments. Generic work is being supported by the WR1T program.
Retardation studies on basalt are being funded through GWIP.
32 II.
Technical Studies:
1.
Nuclides:
Nuclides under study include Am, Pu, Np, Ra, U, I, l
Tc, Sr, and Cs.
2.
Materials:
Solid phases being studied include crushed granite, BWIP basalt, clays, and zeolites.
Aqueous phases are simulated groundwaters.
Both batch tests and crushed column work is ongoing.
4 3.
Processes:
Processes being studied inc.ude the hydraulics of column flow, solubility of actinides, retardation mechanisms at ambient and elevated temperatures.
4.
Sites: - PNL researchers are conducting support work for BWIP.
1 III. Major Points:
1.
Work on the hydraulics of column flow is being conducted to study whether there is a change in effective porosity as flow rate changes.
This is being explored to determine if changes i
in Kd values corresponding to elution rates is real.
The work is exploring an alternative to the kinetic hypothesis.
This effort is also part of an effort to compare batch and column Kd tests.
33 2.
Experiments are being performed to determine actinide solubility as a function of Eh and pH.
Findings to date indicate the i
actinides are very solubility limited at low Eh, 3.
Work at PNL, as elsewhere, has come to reveal the importance of j
low Eh.
However, producing reduced conditions in the laboratory has been troublesome. Work using inert grses had been thought i
to produce reduced conditions but has proven otherwise.
Inert atmospheric conditions are being referred to as anaerobic implying low oxygen partial pressure but not necessarily reducing conditions.
Consideration is being given to ways of more definitely controlling, measuring, and calculating Eh'.
These include:
use of electrodes, gas mixtures, Eh based on sulfite and sulfate ratios, using Mg/Fe oxide solid solutions which'are very Eh dependent.
pH controls include carb')nated/ bicarbonate, and NBS standard buffers.
In terms of actually simulating 0 2
fugacity conditions anticipated at depth over the long term, it was noted that equipment limitations do not permit it.
4.
A computerized Kd data retrieval system is being developed (see ).
The capabilities of the system include data tabulation and management, graphics, and statistical capabilities.
l l
The statistical capability may be useful in assessing the validity of data.
Tha data base collected thus far is being transferred to a mure versatile DOE data management system.
i Additionally, the WRIT program is contributing funding and data t
l
[
.]
4 34 I
to set up an international data base with Europe.
Data in the present PNL system has not received rigorous QA auditing, although this is anticipated.
I 1
5.
PNL efforts for BWIP entail defining Kd values using batch J
tests at low and high temperatures.
Isotopes being studied.
include Ra, U, I, Tc, Sr, and Cs.
Materials include zeolites, I
and clays.
High temperature (150-300* C) experiments are being t
t conducted on basalt, clays, and zeolites with respect to Pu and 4
Am.
6.
Future efforts entail large column tests, fracture flow tests, comparing nuclide sorption.from waste form leachate with synthetic solutions.
Work with fractures thus far have been difficult due to fractures closing under pressure.
i BWIP Retardation' Program I.
Overall Objectives and Approaches:
Enclosure'7 contains an outline of the BWIP retardation program.
The overall objective is to define the retardation properties for BWIP site' investigations.
Efforts also include near field interactions and develop-ment of engineered barriers..The general approach taken is to concentrate on laboratory testing under simulated and well controlled conditions as a means to derive data that can be extrapolated to the field.
-,. - ~,. -,. - -. _ - -.
35 II.
Technical Studies i
1.
Nuclides:
Nuclides identified for study were I, Sr, Tc, Pd, Sn, Pb, Ra, Th, U and Np.
As described below, nuclides chosen have been based on " bounding" scenario analyses, t
2.
Materials:
Studies using batch testing are being conducted on basalt and associated primary and secondary minerals.
3.
Processes: Work is concentrating on retardation as a function of environmental variables, particularly high ten.peratures.
i 1
4.
Sites:
BWIP.
f III. Major Pcints 1.
Nuclides chosen for study have been chosen on the basis of one dimensional advection-dispersion calculations considering several " bounding" scenarios.
2.
Conditions chosen for study are based on a repository having the following characteristics:
1 Km depth, ambient temperature of 65*C, pressure at 300-400 bars, Eh of
.33 volts, pH of 10.1 (based on silicic. acid).
The Eh value is assumed controlled by pyrite / groundwater equilibrium.
Near field temperatures being assumed range up to 250-350*C at a thermal loading of 100-Kw/ acre.
The oxygen fugacity is assumed to be close to the Ni-N10 buffer.
j 36 3.
Closed system high temperature experiments are being performed to assess changes to the chemistry of groundwater in response to the thermal loading.
Of interest are results which indicate a depression of the pH from 10.1 to 4, then a subsequent rise to 6.5.
The depression of the pH is postulated as being due to precipitation of clay minerals from solution which consumes hydroxyls. The subsequent rise to 6.5 is thought to be due to the heated water reacting with glass in the basalt.
Other high I
temperature work on U solubil:ty anticipated indicates at 150 C the solubility is in the ppb range.
4.
Consideration is being given to developing waste packages and engineered barriers that control the Eh and pH.
Consideration is being given to graphite and copper as Eh buffers and aluminum j
phosphate as a pH buffer.
Waste packaging designs are taking-into account chemical stability and retardation under reducing conditions.
Several reports cited describing the BWIP approach are RHO-BWI-LD23 and RH0-BWI-ST7.
l l
S.
In terms of field testing, the utility of leach. tests in the field was questioned.
Skepticism was expressed regarding whether such tests.(conducted under atmospheric: conditions) truly simulate long-term conditions and whether disturbin'g the environment in conducting such tests. invalidates them.
The BWIP waste emplacement tests that are ongoing are not aimed at l
geochemistr; but thermomechanics and emplacement procedures.
l l
l
37 WRIT PROGRAM I.
Background
The WRIT program is basically two years old.
Its original goal was to conduct far field sorption experiments.
In terms of Kd values the program emphasized quantity not rigorous quality, in that values were needed for modeling studies.
It became apparent that experiments were being conducted under conditions having questionable relevance and that there were experi-mental difficulties.
Also, there was a realization that environmental factors affecting retardation are important.
In the past the emphasis was on salt and engineered barriers.
Therefore, a rigorous approach to studying retardation factors was not emphasized.
II.
Present Program Objectives l
Emphasis in the program has changed in several ways.
Focus in being placed on studies of factors that affect retardation with the objective being the development of multivariate capability to extrapolate results l
l to field conditions.
In this regard more rigorous compilations of Kd 1
values are being prepared for transport model tests.
Focus in the 1
l program is also being given to:
gathering scientifically supportable l
data, defining a hierarchy of properties that affect retardation, simulating real world conditions, comparing and resolving differences between various Kd techniques, rigorous site specific data generation, l
determining which techniques are most applicable to a given situation, and chemical model development as subroutines for transport analysis.
l
3 38 Future Program Objectives Future efforts on the technical level are expanding into investigations of the near field and backfill materials.
In this regard, it was noted that next year the Hainesville Dome AEGIS Modeling Study will be expanded to consider the near field.
A program reorganization is taking place to consider studies directed at meeting the NRC draft technical regulation.
It was recognized that the NRC regulation is in draft form and that specifics may change.
Summary of Major Areas of Progress 1.
There has been a realization of problem areas in the way experiments were conducted.
There has been a significant effort to standarize and improve experimental methods.
2.
Many Kd tests are underway to improve the understanding of mechanisms and a hierarchy of just what factors are important in retarding nuclides is being developed.
3.
For many elements, solubility as a retarding mechanism has emerged as the major mechanism involved in inhibiting migration.
This is particularly true of the actinides and greater effort is being made to determine their solubility.
4.
Redox conditions have emerged as being of critical importance and
.this requires further investigation.
_ _.. ~ - ~ __
__m._,
_ _. _ ~ _.... _ _ _. _
i l
39 I
5.
With respect to sorption, efforts to date reveal some elements i
(e.g., Sr) follow ideal behavior and some do not (e.g., actinides).
Confidence was expressed that the technology should be able to bound i
l Kd values within a factor of ten.
Batch Kd values appear to represent l
upper bounds. Additional work is needed to assess fracture flow' I
adsorption.
i T
d 1
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8
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e j
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1 1.
u
o APPENDIX A PARTICIPANTS AT USNRC/ DOE / NATIONAL LABORATORY MEETINGS GE0 CHEMICAL RETARDATION
A-1 USNRC/00E HEADQUARTERS ORGANIZATIONAL MEETING:
May 26, 1980
Participants:
Gary Robbins, USNRC Carl Newton, DOE (Main contact for meetings)
Warren Eister, DOE Thomas Longo, DOE Carl Cooley, DOE
A-2 USNRC/ARGONNE NATIONAL LABORATORY MEETING: June 10, 11, 1980
Participants:
June 10, 1980 Gary Robbins, USNRC George Birchard, USNRC Gary Marshall, DOE, Chicago
- Sherman Fried, Argonne, Chemistry Division Kenneth Nash, Argonne, Chemistry Division John Hines, Argonne, Chemistry Division Paul Rickert, Argonne, Chemistry Division Felix Schreiner, Argonne, Chemistry Division Arnold Friedman, Argonne Chemistry Division
Participants:
June 11, 1980 Gary Robbins, USNRC George Birchard, USNRC Paul Rickert, Argonne, Chemistry Division
- Martin Seitz, Argonne, Chemical Engineering Division Rex Couture, Argonne, Chemical Engineering Division
- Contacts for meetings
A-3 USNRC/0ak Ridge National Laboratory Meeting:
June 12, 13, 1980
Participants:
J e 12, 1980 Gary Robbins, U3NRC George Birchard, USNRC
Participants:
June 12, 13, 1980 Gary Robbins, USNRC George Birchard, USNRC James Johnson, Jr., ORNL, Chemistry Division Donald Palmer, ORNL, Chemistry Division
- Robert Meyer, ORNL, Chemistry Division Robert Mesmer, ORNL, Chemistry Division G. David O'Kelley, Actinide Chemistry Division R. L. Hahn, Actinide Chemistry Division
- Contacts for meetings
A-4 USNRC/USGS MEETING (RESTON):
June 17, 1980
Participants:
Gary Robbins, USNRC Donald Alexander, USNRC Edward O'Donnell, USNRC George Birchard, USNRC Isaac Winograd, USGS, Radiohydrology Robert Schneider, USGS, Radiohydrology Don Thorstenson, USGS, Radiohydrology
- Contact for meeting
j A-5 l
USNRC/LOS ALAMOS SCIENTIFIC LABORATORY MEETING: June 23, 24, 1980
}
Participants:
Gary Robbins, USNRC George Birchard, USNRC i
Edward O'Donnell, USNRC
- Bruce. Erdal,- LASL 4
Kurt Wolfsberg, LASL j
William Daniels, LASL l
Allan Ogard, LASL David Curtis, LASL 1
Darlene Hoffman, LASL l
Elizabeth. Vine, LASL Daniel Fortney, Sandia, Albuquerque Craig Fredrickson, WIPP Project i
l l
l f
~
i
- Contact.for meeting i
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A-6 USNRC/ LAWRENCE BERKELEY LABORATORY MEETING: ' June 25, 1980
Participants:
Gary Robbins,-USNRC George Birc'ard, USNRC h
Edward O'Donnell, USNRC
- John Apps, LBL, Geosciences Larry Benson, LBL, Geosciences P. Lichtner, LBL-Len Lainie, DOE, San Francisco C. Carnahan, LBL M. Michel, LBL R. Silva, LBL, A. Yee, LBL N. Edelstein, LBL
- 1. Bucher, LBL
- Contact for meeting-e
A USNRC/ PACIFIC NORTHWES~l LABORATORY MEETING: June 26, 27, 1980
Participants:
Gary Robbins, USNRC George Birchard,'USNRC Edward O'Donnell, USNRC Mel Shupe, DOE, Richland-
- R. Jeff Serne, PNL Max Kreiter, PNL Patricia Salter, RHO (BWIP)
Wayne Ross, PNL G. Scott Barney, RHO-(BWIP)
Bernie Wood, RHO (BWIP)
Lloyd Ames, PNL Don Rai, PNL Robert Strickert, PNL I
John Relyea, ?NL Alan Baldwin, PNL Gregory Petry, PNL l
l
- Contact for. meeting-i f
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APPENDIX B l
AGENDA HANDOUTS l
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B-1 AY"'
UNCLASS'INiEb bhLpERM tm JUN 2 41 9 19 Department of Energy 005391 Washington, D.C. 20545 MSG. NR.
(commc.nier use o<e ir Communications Center Germantown, Maryland THIS COVER SHEET IS FOR THE TRANSMITTAL OF UNCLASSlFIED MESSAGES ONLY XEROX 200 TELECOPIER FTS 233-3870 USE BLACK FELT COMMERCIAL 301-363-3870 TIP PEN ONLY l REMOVE ALL STAPLES l
-m VERIFICATION FTS 233-3486 COMMERCIAL 301-353-3486 DATE June 2, 1980 TO:
Gary Robbins Nuclear Regulatorv % nission 427-4177 fum.
Location Toimphone Nr.
I FROM:
Carl Newton NE-30 Gtn 353-4851 Name Locanon 427 4298 (rapid fax)
I ****'* N'-
FAGe:C.is,M2 bt[3M VRC rennte copier)
THIS TRANSMITTAL CONSISTS OF 3
c i WANT ORIGINAL BACK:
YES X
i NO NAME EXT.:
f For Pw.kup)
OR MAIL STOF B-107 m try MAiu THIS MESSAGE CONTAINS ONLY UNCLASSIFIED INFORMATION: O ili-1 O
OSIGNATURE UNCLASSIFIED ONLY
,......,.,...,, _....... - ~. - -
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o B-2 NRC REVIEW OF NATIONAL LABORATORY GE0 CHEMICAL RETARDATION EFFORTS Purpose of Visit To gather input for the development of regulatory guidance on Geo-chemical Retardation.
Background
(1) DOE charged with repository development (2) EPA charged with developing overall radiological standards (3) NRC charged with implementing the EPA standard through:
a.
Development of 10 CFR Part 60 L. procedural part LL. technical part b.
Licensing review.
L.
Regulatory guide - defines acceptable procedures and methods to meet requirements.
LL. Licensing review (plans) - defines review procedures Outline of Guidance (1) Three parts a.
text b.
guidance c.
review plan Questions to be Answered by Visit (1) What techniges are being used to measure retardation?
(2) What nuclides are being investigated?
(3) To what extent are results sensitive to procedures?
(4) What environmental conditions are being studies? How are they simulated and monitored? How well are environmental !nfluences understood?
(5) How will tecnniques and results be used?
(6) What. level of confidence can be placed on laboratory results?
(7) How does the work at the lab fit into the National program?
Fit into a specific site assessment?
1 l
B-3
)
Questions to be Answered by Visit (cont.)
i (8) What is necessary to characterize the retardation properties at a site?
(9) What field tests are being conducted? Planned? What field techniques are available?
(10) What future work is anticipated?
(11) Specific laboratory questions e
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a
g_4 SCHEDULE OF NRC REVIEW Tuesday, June 10, 1980 - M-Wing Conference Room - Building 200 10:00 - 10:40 Basic Energy Science Program - S. Fried 10:40 - 11:20 Auto Oxidation and Reduction of Actinides - K. Nash 11:20 - 12:00 Modeling of Surface Repositories and Isotope Preparation - J. Hines 12:00 - 1:00 Lunch, Dining Roan B 1:20 - 2:00 Waste Repository Isolation Technology Program - P. Rickert 2:00 - 2:40 Migration of Ocean Sediments - F. Schreiner 2:40 - 3:10 NTS Field Test Experiment - A. Friedman 3:15 -
Visit the labors.cories Wednesday, June 11, 1980 - Room Y102 - Building 205 8:30 -
Leach Migration Experiments - M. Seitz
B-5 i
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Visit to LBL of Mr. Gary Robbins. Division of Waste Management, NRC, Dr. George Birchard, Of fice of Nuclear Regulatory Research, NRC, and Mr. Ed O'Donnell, Office of Standards Development, NRC June 25, 1980 Schedule of Meetings Tir:
Contact Place 9:00 J. A. Apps, 96-1140C Group Leader, Geosciences
( c, - 1,
I*'
Overview of Waste Isolation Geochemistry Projects at LBL 9:45 L. V. Benson 90-1140G P. C. Lichener Project on Basalt Waste Interactions.
(RHO) 11:15 C. L. Carnahan 90-1140F Chemical Transport in Natural Systems.
(OBES) 12:00 Lunch 1:00 M.C. Michel 70-177A 3'U/
U Disequilibria in groundwaters.
(ONWI) 1:45 R. J. Silva 70A-2275 A. Yee WRIT program 2:45 N.M. Edelstein 70A-1149 l
J. Bucher S. Browne l
Actinide chemistry (ONWI) 3:15 Tour of Lab facilities 70A l
e Project Number t'
- 8%'z D eMtoIf a B-6
%*)* Vwd:AbPinb imemal D.unbut on Pacdic Northwest Laboratories
}j ghupe gj y73g il Kreiter GS Barney June 19,1980 AL Platt LL Ames Ca'e W R:ss WL Kuhn R Nelsen DJ Bradley 7
Distribution JF Relyea RJ Jarrett n7 0 Rai RA Walter
om R. J. Serne RG Strickert Vb Subject JUNE 26-27 VISIT BY NRC PERSONNEL-Since my June 4 memo, Gary Robbins of NRC has fir ned up his plans and re-quested seme rearrangement in the schedule, (As you may recall, NRC re-quested access to DOE. labs via headquarters prior to drafting preliminary regulation. guidelines pertaining to sorption.)
The following is NRC's desired agenda:
June 26 Geneva Recm, PSL Bldg,, 3000 Area 1:00 - 1:30 Introduction of NRC's visit - Gary Rchbins, NRC 1:30 - 2:30 Overview cf Serptien Experiments - WRIT J. F, Relyea,
- PNL, To include:
types of measwements being performed, sensitivity of Kd.to geclogic ard chemical parameters, how do we control variables pH, Eh, etc, Sumary of what parameters are important (scrt of like icentification of mechanisms), how do we compensate for uncertainties such as time extrapolatten, unknown re;:ository conditions. d 2:30 - 3:30 Overview of Sorption Experiments - BWIP: Scott Barney (RHO) or Bernie Wood (RHO) or Lleyd Ames (FNL).
Same tcpic as above 3:30 - 5:00 Lab tour of WRIT and PNL su kontracted BWI? Sorption Experiments (concentrate on 3720 building).
Lead by Relyea and Ames (?)
June 27 Seattle Room, Math Bldg., 3000 Area O
.E 30 - 10:00 Closed meeting with NRC, WRIT staff, and NWT?O to discuss NRC observations en WRIT subc:ntractors and total program adequacy - Gary Robbins (NRC) leads, 10:00 - 12:00 Continuation of WRIT-BWI? technical aspects and future direction including-ties to field tests.
Led by R. J.
Serne, J. ?, Relyea (WRIT), and G. 5, Barney and B. Wood (BWIP) 12:00 - 1:00 Lunch in N:rthwest Room - Gary Robbins, Ed O'Ccnneli, George Brichard (NRC); R. J. Serne, J. F. Reiyea, Fregram Office Persen, R. G. Strickert, D. Pai (PN'.); G. S. Barney, B. Wood (RHO),
1:00 - 2:00 Wrap up - cuesticn: and answers,. Led _by R. J. Serne (?NL)-
anc G. R:bbins (NRC).
2:00 NRC-representatives leave f:r airport, RJS/hm-M
....o,-e:io,o m
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