Actinide and brine chemistry in salt repositories: Updates from ABC Salt (V)

1. Actinide and Brine Chemistry in a Salt
Repository: Updates from ABC Salt (V)
Donald Reed (LANL)
Marcus Altmaier (KIT–INE
Middelburg, The Netherlands
September 5-7, 2017
LA-UR 17-27994

2. Overview
 Venue, Participation, and Overview of Workshop Sessions
 Key Results of Various Sessions
 WIPP and International Updates
 Salt Research Project Updates
 Microbial Effects
 Corrosion and Sorption
 Modeling and Solubility Studies
 Temperature Effects
 Actinide Redox and Solubility
 Special Topic Sessions: Solubility studies and Actinide Redox
 Overlap and Connectivity with Geotechnical Issues
 Summary and Announcement of ABC Salt (VI)
2

3. MCM Eleganté Lodge and Suites
March 26-28, 2017
Convention Center, Ruidoso NM, USA
Ruidoso Convention Center
Venue

4. Total Participants: 36
 ~ 28 Researchers/Staff
 8 students or postdocs
Attendance from 5 Countries (but mainly USA and Germany)
 USA (26), Germany (7), France, Switzerland and UK
Institutional Involvement
 WIPP: DOE-CBFO, Los Alamos, Sandia
 German Labs: KIT/INE, HZDR and GRS
 Regulatory/Agency: EPA, NEA, NWRB, RWM
 Universities and others: FSU, ND, FIU, Freiberg, CEMRC/NMSU,
AF-Consult
Workshop Participation

5. Overview of ABC Salt (V) Workshop
Sunday
PM
Welcome from WIPP
International Program Updates
Monday
AM/PM
Project-Specific Updates (Salt Repository Research)
Microbial Effects Studies
Corrosion and Sorption
Poster Session – all topics
Tuesday
AM/PM
Modeling and Solubility Studies (Discussion: Solubility
Experiments)
Temperature Effects
Redox and Actinide Chemistry (Discussion: Redox
Chemistry)
Overview of Sessions

6. WIPP/International Updates
 WIPP-Specific Updates
 Shipments were resumed on January 4
 Full recovery process continues (currently estimated to be ~ 2021)
 Progress on recertification was statused – this was predicted/expected –
this has since been received (July 19, 2017)
 Monitoring program continues to show compliance
 German Updates (Bernhard Kienzler)
 RWM (UK) high ionic strength research needs (Amy Shelton)
6
WIPP status and
one possible
disposal space
increment
New Unfiltered
Exhaust Shaft
Main point: This has been a
tough few years, but progress
in key and essential areas
continues

7. New Mexico State University
Historical Radiation levels in the WIPP Underground Air
Station A
Station B
Station A,
before filtration
Station B, at post-
filtration outlet
Historical data – WIPP Underground
Air (from Punam Thakur, CEMRC)

8. Offsite monitoring data
Punam Thakur (CEMRC)
8
On site and Off Site Monitoring Stations
New Mexico State University
CEMRC Air sampling sites
16 sq mile boundary
• Onsite detection: 115 µBq/m3 of 241Am; 81.4 µBq/m3
• No off-site hi-volume sampler detections were positively
attributable to the WIPP release event.

9. Microbial Effects
 Updates from both the WIPP project and HZDR (German)
research were given.
 Key results:
 We are seeing null results (no GG) under anoxic WIPP-specific
conditions (this is consistent with prior results in the project)
 No viable microorganisms have been identified under anaeorobic
conditions – this places the likely time of greatest microbial effects
during the early repository times that are likely suboxic and lower I
 High sorption and bioassociation is being observed over a range of pH
and brine compositions with various microorganisms (bacteria >>
archaea)
Status: Good progress is being made in this area. Remaining issues are in
the areas of 1) defining microbial contributions to the source term
and 2) a better understanding of the initial suboxic unsaturated
time period
9

10. Relationship between water
activity, Brine composition, and
likely microbial activity (J. Swanson)
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11. Repository phases and microbial issues to
be considered for salt-based repositories.
(Swanson et al, LAUR 16-28895)
11

12. Corrosion and Sorption
Sorption
 Collaborative work between FIU and Los Alamos were
presented on sorption (H. Emerson and T. Dietrich).
 Not a high priority for the WIPP project as to far-field
interactions (small potential contribution to overall release)
 Potential contributions that affect the actinide source term
are important and being investigated (but we do not fully
account for sorption in the source term).
Corrosion
 INE (B. Kienzler) presented a summary of 10 year corrosion
data in salt (these are largely consistent as to mass loss data)
 New KORSO Project (Corrosion and sorption processes onto
steel surfaces at elevated temperatures under saline
conditions) was announced. 12

13. Sorption of Nd3+ onto Dolomite in
variable I NaCl (H. Emerson - FIU)
13
0%
5%
10%
15%
20%
25%
30%
35%
40%
45%
50%
1 10 100 1000 10000
Ceffluent/Cinfluent
Volume (mL)
0.1 M IS 5 M IS
Column
Experiments
Batch Studies

14. Modeling, Solubility, and
Temperature Effects
 THEREDA overview given – progress continues in this modeling
activity (Moog)
 Feedback from the TDB Pitzer SOAR activity through some
presentations – issue of how to properly phrase the Pitzer
model and associated coefficients (Voight)
 Updates from THERMAC - a collaborative project investigating
aquatic chemistry and thermodynamics of actinides at elevated
temperature conditions (Altmaier)
 Description of the proposed WIPP An(III)-borate model was
provided (Xiong)
14

15. Discussion Issue #1
ABC Salt V
 Completeness and Data Gaps (if any) in the
 Pitzer Data Base
Status:
1) There is a sense that the models need to be updated
and some data gaps need to be filled. Progress is
being made, albeit very slowly.
2) Relatively few temperature-variable data exist, but
those that are available show decreasing solubility and
a higher degree of crystallinity.

16. Actinide Redox and Solubility
 Speciation and redox chemistry of U(IV) (Yalcintas)
 Uranium(IV)-EDTA, under redox controlled conditions, shows evidence
of ternary complex formation
 Advances in Np(V) solubility and Speciation (Fellhauer)
 Solubility + speciation of Np(V) in neutral to alkaline NaCl / MgCl2 /
CaCl2 solutions
 Good progress reported on phase identification and correlation with
solution chemistry
 WIPP redox model and plutonium oxidation state distribution
(Reed)
 WIPP redox model is by expert opinion since the initial license
(unchanged)
 Newer data in the literature and WIPP specific data is suggesting that,
in the presence of Fe(0,II), we expect the formation of Pu(III) in some
simplified systems.

17. Pu(V/VI) Reduction by Lower-
Valent Fe in Brine (with Pu-242)
~ 3-month
Analyses -
all Pu(IV)
~ 6-year
Analyses –
mostly
Pu(III)XANES analysis performed at
the APS, courtesy of Dan Olive
and Jeff Terry (IIT)

18. Discussion Issue #2: Actinide Redox in
the Salt Repository Case
How well are we able to predict/model/understand redox
evolution and control in a repository?
Is there sufficient experimental evidence available for saline
systems to assess An redox processes under reducing
conditions?
Plutonium case:
 Which are the relevant Pu oxidation states under
oxidizing, anoxic or strongly reducing conditions in rock
salt.
 How will strongly complexing ligands affect Pu redox state
distribution?
 Are our current TDBs adequate to assess Pu redox state
distributions?

19. Plutonium Speciation and Oxidation
State Distribution
Status:
1) Many new data are available – these show that reducing conditions are
established and maintained under repository-relevant conditions when iron is
present. Overall a very good result for actinide containment.
2) How we define oxidation distribution in these long-term scenarios in complex
systems is being revisited. Active and collaborative discussions are expected
in the next few years.

20. Are there synergies and/or overlapping
issues between the Actinide/brine group
and Geotechnical Activities?
Actinide/Brine Topics: Actinide Solubility/Redox/Speciation,
Microbial, Corrosion, Brine Chemistry
Potential areas of overlapping interests:
 Better definitions/understanding of early pre-saturation phase
 Microbial issues – biodegradation and GG
 Redox as it relates to iron or waste degradation pathways
 Effects of elevated temperatures (e.g. repository design) on brine
evolution and near-field environment (thermal waste only)
 Water availability and brine evolution
 Microbial viability
 Issues of radiolysis
20

21.  Welcome presentation by Tod Shrader (Manager, DOE-
CBFO) that announced that the WIPP had re-opened
and is again receiving waste.
 Outstanding discussion throughout the workshop – a
good mix of attendees.
 Excellent discussions on actinide solubility studies
and redox – these led to recommendations for future
direction/focus.
 Plenary talk by Marilena Ragoussi (NEA-TDB) on
database activities (there was also a coupled Pitzer
SOAR meeting after the workshop).
 Salt repository research continues (despite
distractions) – this shows that Salt continues to be a
good geology for nuclear waste disposal.
Key Results and Observations

22. Department of Energy, Carlsbad Field
Office (DOE-CBFO) for programmatic
support
Carlsbad Environmental Monitoring and
Research Center (CEMRC) for sponsoring
the Sunday PM reception, AV support,
and staff support for the logistics of the
workshop
Nuclear Energy Agency (NEA), this
workshop is a listed activity of the NEA
Salt Club
Federal Ministry for Economic Affairs and
Energy (Germany) for programmatic
support
Los Alamos National Laboratory Civilian
Nuclear Programs Office and Conference
Management team for logistical support
This workshop is co-organized
by Los Alamos and KIT-INE.
We wish to acknowledge and
express thanks to the following
support and sponsorship:
Sponsorship and Support

23. ABC Salt V Workshop, Ruidoso NM USA
March 26-28, 2017
ABC-Salt (VI) is tentatively planned for
Spring/Summer of 2019 and will be combined
with HITAC and hosted by KIT/INE in Germany
ABC Salt Workshop