Spent Fuel and Waste Science and Technology

Pu Incorporation into Reduced Iron Oxide Phases

Enrica Balboni and Mavrik ZavarinLawrence Livermore National Laboratory

SFWST Annual Working Group MeetingLas Vegas, Nevada

May 22-24, 2018

LLNL-PRES-751812This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under contract DE-AC52-07NA27344. Lawrence Livermore National Security, LLC

With support from Melody Maloubier and Brian Powell (Clemson University)Corwin Booth (Lawrence Berkeley National Laboratory)

Spent Fuel and Waste Science and Technology

TitleMay 23, 2018

Overview of Activity

2

Water

Mineral

Pu Pu

Pu

PuPu

Water

Mineral

Intrinsic colloidsWater

Mineral

Pu

PuPu

PuPu

PuPu

Pu

Pseudo-Colloidal transport

Water

Mineral

Pu

Pu

PuPu

Pu Pu

Pu

Microbial activityWater

Mineral growth

Pu

PuPu

PuPu

Pu

PuPlutonium uptake

This work: coprecipitation of Pu with iron oxides

Radionuclide transport controlled by release, sorption, and colloid facilitated transport processes

How do repository corrosion processes affect the mobility of RNs?

Spent Fuel and Waste Science and Technology

TitleMay 23, 2018

Effect on Repository Performance or Safety Case Confidence

3

Fuel Matrix Degradation Model and Canister Corrosion (ANL) are a key component for evaluation of repository performance assessment and safety case models

Radionuclide may be entrained in the corrosion products

Radionuclide association with corrosion products may lead to reversible (sorption) or irreversible (coprecipitation) sequestration of radionuclides

Lower radionuclide release rates

From Jerden, Frey, and Ebert, 2017

Spent Fuel and Waste Science and Technology

TitleMay 23, 2018

Integration with GDSA/PA and/or the Safety Case

4

Steel corrosion model has been added to the fuel matrix degradation model (FMDM) developed at ANL

Model provides a kinetic source for H2 and Fe2+

The FMDM is intended to be integrated with the GDSA PA model

From Jerden, Frey, and Ebert, 2017

Spent Fuel and Waste Science and Technology

TitleMay 23, 2018

Example Results – Pu Interaction with HFO and Goethite

Ferrihydrite precursor

• pH • time • T°C

HematiteFe2O3

GoethiteFeOOH

Synthesis RoutesRoute A “Coprecipitation” Route B “Sorption”

Method A

Method B

Goethite Hematite

Total of 12 samples

Final Product:Hematite OR

Goethite

CONCLUSION: Pu incorporates into goethite but not into hematite

Spent Fuel and Waste Science and Technology

TitleMay 23, 2018

Example Results – Pu Interaction with HFO and Goethite

Method A

Method B

Goethite Hematite

Total of 12

samples

Focus of the talk: goethite

synthesized with 3000 ppm Pu and

its ferrihydrite precursor

Does the initial association of Pu with the ferrihydrite precursor (sorbed vs coprecipitated) affect the association of Pu with the final

crystalline product

Question

Spent Fuel and Waste Science and Technology

TitleMay 23, 2018

Ferrihydrite EXAFS: PuO2 in “sorbed” ferrihydrite

Spent Fuel and Waste Science and Technology

TitleMay 23, 2018

Goethite EXAFS: PuO2 in “sorbed” ferrihydrite preserved

TEM confirmed PuO2 TEM

Spent Fuel and Waste Science and Technology

TitleMay 23, 2018

Pu Acid Leaching: Nature of Incorporation Affects Pu Release

0

0.5

1

1.5

2

2.5

3

3.5

100

600

1100

1600

2100

2600

3100

3600

0 2 4 6

Fe (p

pm)

Pu (n

g)

HNO3 (M)

Pu-GA Pu-GB Fe-GA Fe-GB

More Pu leached from Goethite (B) than Goethite (A)Goethite (A): formed from aging of ferrihydrite coprecipitated with Pu; Goethite (B): formed from aging of ferrihydrite with sorbed Pu.

Spent Fuel and Waste Science and Technology

TitleMay 23, 2018

Relationship to 2012 UFD Roadmap and R&D Priority Ratings

10

Task #

Task Name/

(and Work Package

number -- if needed or helpful for

more specificity)

Brief Task Description

includingRelevance (and/or input) to PA/GDSA

(nPA = not direct input to PA)

Personnel/Lab

Code(if

applicable)

Importance to Safety Case

(ISC)

(H, M, or L -- see ISC table

definitions)

(Identify applicable

Safety Case element from the provided

figure)

Current "State of the Art" Level

(SAL = 1, 2, 3, 4, or 5 -- see SAL table definitions)

(Give brief update to applicable state-of-the-art "discussion(s)" shown in UFD Roadmap App. A, i.e., those discussion(s) for the

highest scoring related FEPs)

Short-term (1 yr) R&D Priority Scores

& Brief FY19 Work Scope Proposal

(Priority Score = H, M, or L, based on combined ISC and SAL -- see PS

table definitions)

(Also give Roadmap Score for related FEP)

Related UFD Roadmap

Issue(s)/FEP(s), and associated UFD Roadmap priority scores*

(Find highest scoring related

FEP in App. B of UFD Roadmap)

Other Notes/Comments

(e.g., type of linkage to PA-GDSA; inputs

required and/or linkages to other

models and experiments)

4 SNF Degradation

• Mixed potentialmodel of spent fuel matrix degradation (including possible effect of Fe corrosion)• Radiolysis

Frederick,Hammond

SNLJerden,

ANL Caporuscio

LANL Balboni LLNL

PFLOTRAN/FMDM

ISC = High

SC element 3.3.1b

SAL = 5

From Roadmap: U.S. program evaluated the long-term behavior of LWR UOX in oxidizing environments. Other programs have evaluated and are modeling the degradation of UOX and MOX in reducing environments. Little information is available regarding the degradation/alteration of otherUNF types.

PS Matrix Score = H; Roadmap Score = H

For FY19 continue work on FMDM model development and code optimization

• Primary FEP is 2.1.02.01; score = 4.01• Other related FEPs have lower scores

• Direct implementation in PFLOTRAN already complete and now at the testing stage.• Additional development and more efficient coding suggested

9

Waste Package

Degradation Model

(mechanistic)

• Degradation of waste packages and canisters• Carbon steel; stainless steel; copper waste packages Experimental Data• Include various degradation processes (SCC, GC, LC, MIC, early failure)

Jove ColonSNL

Caporuscio LANL

Balboni LLNL

PFLOTRAN et al.

• FEPs 2.1.03.02, 2.1.03.03, 2.1.03.04, 2.1.03.05; scores = 4.34

• Direct implementation in PFLOTRAN suggested (1D model), similar to SNF degradation• Currently evaluating development of thermodynamic relations for high T 316 SS corrosion phase assemblage (e.g., chromite, magnetite)

Spent Fuel and Waste Science and Technology

TitleMay 23, 2018

Current State of the Art and Past Accomplishments

11

Current State of the Art:– ANL FMDM includes fuel degradation and steel corrosion processes

– Role of corrosion products on radionuclide immobilization not included in FMDM or PA models

Past Accomplishments:– Goethite favors uptake of Pu over hematite: crystallographic considerations

– EXAFS and Pu leaching results indicate that a different association of Pu to the ferrihydrite precursor (Pu sorbed or coprecipitated) results in a different association of Pu in goethite

HEMATITE: “compact” structure

GOETHITE“open” structure

Spent Fuel and Waste Science and Technology

TitleMay 23, 2018

Future R&D & Integration Timeframe

12

FY19 effort will focus on radionuclide (Pu) incorporation into reduced iron oxide phases (magnetite, green rust, etc.)

Longterm need to incorporate radionuclide interaction with corrosion products into FMDM or downstream models

From Jerden, Frey, and Ebert, 2017

Spent Fuel and Waste Science and Technology

Questions?

13

Spent Fuel and Waste Science and Technology

Back-Up Slides

14

Spent Fuel and Waste Science and Technology

TitleMay 23, 2018 15

PuPu

PuPu

Spent Fuel and Waste Science and Technology

TitleMay 23, 2018 16

Pu

Pu Pu

Pu