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

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

MCM Eleganté Lodge and Suites

March 26-28, 2017

Convention Center, Ruidoso NM, USA

Ruidoso Convention Center

Venue

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

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

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

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)

Offsite monitoring dataPunam 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.

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 anaeorobicconditions – 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

Relationship between water activity, Brine composition, and likely microbial activity (J. Swanson)

10

Repository phases and microbial issues to be considered for salt-based repositories. (Swanson et al, LAUR 16-28895)

11

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

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

Cef

flu

ent/

Cin

flu

ent

Volume (mL)

0.1 M IS 5 M IS

Column

Experiments

Batch Studies

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

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.

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.

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)

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?

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.

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

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

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

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