# Presentation: 476919

## Fundamental needs in separations chemistry:  Building the foundation for advances in nuclear fuel-cycle separations

**Oak Ridge National Laboratory**
**BES Workshop on Basic Research Needs for**
** ****Advanced Nuclear Energy Systems**
**Bethesda, MD**
**July 30–August 4, 2006**

***Fundamental needs in separations chemistry:  Building the foundation for advances in nuclear fuel-cycle separations***

**(Planning for what we know we don’t know vs. Planning for what we don’t know we don’t know)**

**O****AK**** R****IDGE**** N****ATIONAL**** L****ABORATORY**
**ARGONNE NATIONAL LABORATORY**
**IDAHO NATIONAL LABORATORY**
**WASHINGTON STATE UNIVERSITY**
**U. S. D****EPARTMENT**** ****OF**** E****NERGY**

## Can a basic-research scientist make an impact on nuclear fuel-cycle separations?

- Cost and schedule
- Harsh conditions
- Large equipment
- Rapid throughput
- Small equipment size
- Flowsheet compatibility

**Engineering requirements**

- Lifetime of materials
- Safety & environment
- Waste disposition
- Nonproliferation
- Complexity
- Culture factors

- “Cool” ideas in specialty area
- Basic principles and understanding
- Study of clean, small model systems
- Copious publication in open literature

**World of the basic researcher**

***Challenge lies in having the right knowledge at the right time, plus a team of good engineers interested in collaboration!***

## Can a basic-research scientist make an impact on nuclear fuel-cycle separations?

- Awareness of applied problem
- Can translate problem into science needs
- Works in a strategically fertile research area
- Sustained effort
- Window of opportunity opens

**Some success factors:**

*Basic research does NOT provide new technology. Rather, it provides the discovery, understanding, and knowledge that enables the creation of new technology. That is, it enables; it provides the “TOOLS.”*

***Although the odds are against the single high-payoff discovery,***
***the answer is “yes”!***

*But none of these factors is necessary.*

## Impacts of science are subject to temporal coincidences of needs, knowledge creation, inspiration, and opportunity

***Impacts of science are subject to temporal coincidences of needs, knowledge creation, inspiration, and opportunity***

- Milestones

- Eurekas

**SCIENCE**

- Physics
- Chemistry
- Theory

- Materials
- Fuel Fabrication
- Reactors
- Separations
- Repositories

**TIME**

- Applied
- Need

- Science Needs

- Knowledge
- & Concepts

- Invention & Development

**FUNDAMENTAL KNOWLEDGE PRODUCTION RATE**

**Window of Opportunity**

- What we know  -------------------------------  What we don’t know we don’t know
- ----------  What we know we don’t know ----------

**ENGINEERING**
- (Nuclear fuel cycles)

**APPLIED**
**SCIENCE**

- New
- Technology

**“****Valley of Death”**

- Directed or
- Use-inspired

- Office of Science

- Office of Nuclear Energy

- Who funds this part?

## A successful spin-off!

**Understanding of polyether synthesis, equilibria, structure, and solvation phenomena enabled development of the CSSX process**

**Cross-cutting portfolio:  BES/EMSP/ESP/TFA/EM-40**

**34M gallons of legacy HLW in tanks**
**Tetraphenylborate problem in 1995/96**
**CSSX selected from ~140 technologies**
**Extensive testing and demos in FY00-02**
**Decision to implement in Oct., 2001**
**SWPF design >2004; operation >2010**
**Mobile unit testing in 2006.**

**A successful spin-off!**

**Cs must be removed from SRS HLW**

- DOE decided in 2001 to implement the CSSX process for Cs removal from high-level salt waste at the SRS

*Department of Energy Record of Decision: Savannah River Site Salt Processing Alternatives*, Federal Register, Vol. 66, No. 201, pp. 52752–52756, October 17, 2001.

**(Valley of death traversed!)**

## Test rig set up in SRTC Shielded Cells Facility

**Test rig set up in SRTC Shielded Cells Facility**

**View through cell window**

** ****Demo funded by USDOE-EM**

## CSSX Flowsheet: High decontamination of HLW

**CSSX Flowsheet: High decontamination of HLW**

** ****ANL test (simulant)**
** ****March 2002**
** ****11 cycles; 14 h; 36 L**
** ****DF****avg**** = 420,000**
** ****CF****avg**** = 15.5**
** ****SRTC test (supernate)**
** ****May 2002**
** ****24 h; 50 L**
** ****DF****avg**** = 520,000**
** ****CF****avg**** = 12.7**
** ****SRTC test (salt cake)**
** ****May 2002**
** ****25.5 h (16/9.5*); 45 L**
** ****DF****avg**** = 352,000/28,600***
** ****CF****avg**** = 13.2/15.8***
***Reduced solvent flow**

- Leonard, et al., ANL02/22, 2002; *Solvent Extr. Ion Exch.*, 2003. Norato, et al., WSRC-TR-2002-00243, 2002; WSRC-TR-2002-00307, 2002; Walker, et al.,* Sep. Sci. Technol.*, 2005.

** ****Demo funded by USDOE-EM**

## Need to transform primary separation methods

**Need to transform primary separation methods**

**Solvent extraction**
**Ion Exchange**
**Adsorption**
**Volatilization**
**Dissolution**
**Crystallization**
**Electrorefining**
**Filtration**
**Membranes**

**Liquid–liquid**
**Liquid–solid**
**Gas–solid**
**Solid–gas**
**Solid–liquid**
**Liquid–solid**
**Solid–liquid–solid**
**Solid–liquid–solid**
**Liquid–solid–liquid**

**Breakthrough potential:**
-     New materials
-     Use of magnetic, electric, gravitational fields
-     Use of novel fluids (SCFs, ionic liquids, etc.)
-     Incorporation of recognition and nanostructural features
-     Novel devices and configurations

***Major techniques used in nuclear separations:***

**Long-term**

- Thermodynamics and kinetics of phase change and transfer
- Interfacial phenomena

- Driving Force
- Selectivity
- Cyclability
- Kinetics
- Stability

**Key properties:**

## Some cross-cutting science themes

**Some cross-cutting science themes**

**  ****Nanochemistry and tailored nanoenvironments**
**  ****Chemistry at interfaces**
**  ****Chemical recognition**
**  ****Synthesis and properties of soft materials**
**  ****Neutron science and structural analysis**
**  ****Computational chemistry**

**Cl****-**** binding**

**Cs****+**** binding**

**Chemical recognition**

**Tailored nanoenvironments**

**Synthesis of soft materials**

**Chemistry at interfaces**

**Neutron science**

## Prior workshop report lays groundwork:

***Bruce A. Moyer,*****1***** James J. Laidler,*****2**
***K. Michael Goff,*****3***** and  Kenneth L. Nash*****4***** ***
**1****Oak Ridge National Laboratory, ****2****Argonne National Laboratory, **
**3****Idaho National Laboratory, and ****4****Washington State University**

***Workshop on Science and Technology Challenges for the Advanced Fuel Cycle Initiative***

**O****AK**** R****IDGE**** N****ATIONAL**** L****ABORATORY**
**ARGONNE NATIONAL LABORATORY**
**IDAHO NATIONAL LABORATORY**
**WASHINGTON STATE UNIVERSITY**
**U. S. D****EPARTMENT**** ****OF**** E****NERGY**

- http://www.sc.doe.gov/production/bes/reports/list.html

**Gaithersburg, MD, Sept. 12, 2005**

***Prior workshop report lays groundwork:***

## Current impediments

**Near-term**

**Aqueous (UREX-type) separations perceived as costly**
-       Public acceptance issue.
-       Costs cited as impediment to deployment.
**Incomplete dissolution of spent fuel**
-       0.1% TRU content not dissolved.
-       Additional processing required, raising costs.
**Proliferation risk**
-       Accountability often cited as impediment.
-       Concerns regarding precision limitations.

## On-line monitoring a major need

**Impact:**
- Accountability concern. Potential show-stopper for aqueous reprocessing if public perceives that streams of nuclear materials are not precisely monitored and controlled.
- Ideally (grand-challenge aspect), on-line monitoring is desired to be so good that inherent proliferation resistance would not have to be required.
- High-throughput separations require broad-based on-line monitoring for process control, avoidance of plant upsets, more rapid recovery, reduced down time.
- Minimal set of needs must be defined for short-term.
- In long-term, desire complete real-time data on concentrations of all actinides, fission products, other key elements, extractants, solvent components, and degradation products as well as physical properties of streams.

**Scientific challenges:**
- High specificity reagents and transduction mechanisms.
- Physics of interactions of radiation with materials.
- Nanomaterials for rapid response.

**Near-term**

## Actinide-lanthanide separations a major need

**Impact:**
- A concern for recycle of TRUs to thermal reactors. Need high DFs.
- Recycle to fast reactors has lower selectivity requirements. Pyrochemical technology promising.
- Reliable aqueous technology does not exist. Present generation of extractants is unstable.

**Scientific challenges:**
- Understanding of structure & bonding of actinides and lanthanides.
- Development of high-specificity reagents for extraction.
- Understanding of thermodynamics of liquid solutions, interfacial phenomena, and radiation effects.

**Near-term**

## Vision for the long-term

**Long-term**

**Rapid science-based design of reprocessing plant**
-       All types of unit processes
-       Actinides, lanthanides, FPs, cladding materials, etc.
**Performance by design**
-       Any feed stream
-       Specified product streams at desired purity
**Minimized environmental impact**
-       No TRUs to repository
-       Long-lived FPs to ultimate transmutation or robust waste forms
-       Minimal secondary waste, efficient internal recycle
**Proliferation resistance**
**Energy efficient, economic, safe, small footprint**

*Science and computational models will be so advanced that the designer of the future will be able to input the desired performance of a separations plant within specified constraints and find an optimum molecular composition of mass-transfer agents and configuration of process equipment. *

## Grand Challenge:  Understanding molecular and supramolecular behavior of multicomponent liquids

**Long-term**

**Liquid phases have eluded understanding**
- For example, after over a century, the calculation of activity coefficients in the most studied fluid, water, remains an exercise of data fitting and empirical parameterization.
**Applies to all liquid phases**
-        Aqueous solutions, organic solvents, supercritical fluids
-        Ionic liquids, molten salts, and molten metals
-        Complex, multicomponent, nonideal systems
**Experimental efforts working closely with computational efforts**
- Sophisticated models:  Take into account relativistic effects, open-shell configurations, and simultaneous interactions among dozens of disparate species from bulk to trace concentrations.

*It is envisioned that the structure and behavior of liquid phases will become so well understood that key properties of interest for nuclear fuel cycle development, such as solvation thermodynamics and distribution ratios, can be predicted.*

## Fundamental science needs

**Understanding solvation interactions and transfer phenomena**
-       What are the thermodynamics of a species interacting with a matrix?
-       What is the cost of moving a species from one matrix to another?
-       These questions are the essence of separations
-       Generic questions apply to many separations, aqueous & pyro
-       Matrix effects (solvent, polymer, salt, ...) long-standing unknown
-       Key to predicting distribution & selectivity
-       Need to focus on f-elements, FPs, other

- ~~~~~~~~~~~~~~~~

**Phase 2**

**Phase 1**

_***Partitioning ***_

_***Major question in SS&T***_

**Difficult experimental problems**
-       Solvation involves large energies
-       Small differences, large uncertainties
-       Need better methods and data

**Theory may overcome experiment**
-       Need better models
-       Calculations eventually better than data

## Fundamental science needs, cont.

**Understanding diffusion**
-       Slow mass transfer a limitation of solid-phase materials
-       Breakthrough in enhancing diffusion would have large impact
-                Membranes and ion exchange would benefit, for example
-        Important aspect of volatilization, dissolution, leaching
**Self-assembly phenomena**
-       Key to understanding solubility phenomena, phase splitting
-       Key to understanding speciation in SX
-       Possible new routes to nanostructured extractive materials
**Structure, bonding, solution chem of heavy elements, FPs**

## Grand Challenge:  Design, synthesis, and characterization of specific receptor materials for selective separations

**Long-term**

**Broad scope of materials**
- Sequestering agents, extractants, precipitants, sorbents, ion-exchange resins, inorganic materials
**Challenging design criteria**
- Favorable thermodynamics, rapid kinetics, structural features, binding-release cycles (e.g., switching on and off), robustness (e.g., self healing) to radiation and chemical degradation
**Economical synthesis methodology for designer materials**
- Synthesis methodology is an art.
- Needed are ways to predict synthesis routes and conditions.

*It is envisioned that one will be able to design receptors that will bind any target species from multicomponent gas or liquid phases and that will possess specified properties to function in a certain separation system.*

## Fundamental science needs

**New receptor molecules for recognition**
-      Paradigm shift in extractive separations
-      Desire high specificity for actinides and FPs
-           Soft-hard donor interactions (separate An from Ln)
-            U extractant that cannot bind Pu would be proliferation resistant
-           Cationic FPs (e.g.,137Cs, 90Sr), anionic FPs (e.g., 99Tc, 129I)
**High-yield, green syntheses of extractive materials**
-       Designing ligands is one thing, making them is another
-       Good preps open doors to use, but require new reactions
**Switching mechanisms**
-       Turning extractive materials on and off for efficient extract-strip cycle
-        Key to reduced waste production and small footprint
**Predictive capabilities for extraction and structure**
-        Dynamics of solution structure and transport processes
-        Molecular modeling
-        Molecular design of extractive materials

- Host cavity containing Cs+ ion

## Grand Challenge:  Understanding interfacial phenomena

**Long-term**

**Interfacial phenomena control mass transfer**
- Throughput depends on interfacial fluxes
**Many processes depend upon interfacial good behavior**
- Dispersion and coalescence of drops in liquid-liquid extraction
- Crystal growth and flocculation in precipitation
- Electrodeposition
- Controlling corrosion
**Some separations employ the interface as the binding site**
- Adsorption
- Electrodeposition
**Poorly understood**
- Difficult experiments, usually avoided altogether
- Real opportunity for modeling

*It is envisioned that the structure, thermodynamics, and dynamic properties of interfaces will be so well understood that engineers will be able to design high-throughput processes in optimal equipment.*

## Grand Challenge:  Understanding and controlling radiation effects

**Long-term**

**Inertness to high-energy chemical species**
**Self healing**
**Production of benign degradation products**
**Prediction of interaction of molecules with high-energy particles**

*It is envisioned that materials used in separation processes, including mass-transfer agents, construction materials, and waste forms, will be highly robust to radiation environments.*