ON-LINE MONITORING FOR PROCESS CONTROL AND SAFEGUARDING OF - - PowerPoint PPT Presentation

ON-LINE MONITORING FOR PROCESS CONTROL AND SAFEGUARDING OF RADIOCHEMICAL STREAMS AT SPENT FUEL REPROCESSING PLANTS IAEA International Safeguards Symposium: Linking Strategy, Implementation and People October 20-24, 2014

Sam Bryan, Tatiana Levitskaia, and Amanda Casella sam.bryan@pnnl.gov Pacific Northwest National Laboratory PNNL-SA-105110

Process Monitoring Can Be Achieved Throughout the Flowsheet

Global vision: Process monitoring/control at various points in flowsheet Every flowsheet contains Raman and/or UV-vis-NIR active species Coriolis and conductivity instruments can be used on all process streams

Monitoring Is Not Flowsheet Specific

CoDECON dissolved fuel TRUEX TALSPEAK rare earths

U, Pu, Np Tc

FPs Am/Cm

Monitoring of strong acid

• r pH desired

U

Approach: Online Spectroscopic Measurements

 Raman measurements of

– Actinide oxide ions – Organics: solvent components and complexants – Inorganic oxo-anions (NO3

• , CO3

2-, OH-, SO4 2-, etc)

– Water, strong acid (H+), strong base (OH-) – pH – weak acid/base buffer systems

 UV-vis-NIR measurements of

– trivalent and tetravalent actinide and lanthanide ions

 Potential Uses

– Process monitoring for safeguards verification (IAEA) – Process control (operator)

 Previous Experience

– Real-time, online monitoring of high-level nuclear waste in tanks and to the waste pretreatment process – In discussions with actual reprocessing plants for demonstration

Methodology for on-line process monitor development: from proof-of-concept to final output

Static measurements: Model training database Chemometric model development On-line model verification and translation Integrated software for data collection, processing, storage and archiving Real-time on-line concentration data display

Optical spectroscopy for monitoring UO2

2+, Pu, and Np species in fuel

solutions

Detection limits:

• 3.1 mM for UO2
• 0.08 mM for Pu(IV)

Variable UO2(NO3)2 in 0.8M HNO3

wavelength, nm Absorbance Pu(IV) concentration variable 0.1 to 10 mM Feed composition: 1.3 M UO2(NO3)2 in 0.8 M HNO3 UO2(NO3)2 does not interfere with Pu measurements

Variable Pu(IV) in fuel feed simulant Raman spectroscopy Vis-NIR spectroscopy

Proof-of-Concept : Applicability of spectroscopic methods for commercial BWR ATM-109 fuel measurements

 Commercial fuel: ATM-109, BWR, Quad Cities I reactor; 70 MWd/kg; high burnup  Fuel dissolved in HNO3  Performed batch contact on each aqueous feed with 30 vol% TBP-dodecane  Feed, Organic, Raffinate phases successfully measured by

– Raman, Vis-NIR

 Excellent Agreement of spectroscopic determination with ORIGEN code and ICP measurement Bryan et al. Radiochim. Acta, 2011.

Molar units

Vis-NIR spectra of dissolved High-Burnup BWR ATM-109 Fuel: useful for Pu(IV, VI), Np(V, VI), and Nd(III) quantification

Bryan et al. Radiochim. Acta, 2011. Pu(IV) + H2O Np(V)-UO2 Np(V) Pu(VI) Np(VI) + H2O Pu(VI) Pu(VI) Pu(IV) Nd(III) Nd(III)

// //

wavelength, nm absorbance Aqueous phase: ATM-109 feed, variable HNO3

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PNNL’ s centrifugal contactors can be additionally instrumented to support instrumentation evaluation and modeling validation

 Sixteen 2-cm centrifugal contactors installed within shielded glovebox  Instrumented with Raman and UV-VIS-NIR spectroscopic probes

Flow Testing with PNNL’s Solvent Extraction Test Apparatus (SETA)

Centrifugal Contactor System Instrumented with Raman and VIS-NIR Spectroscopic Probes

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Fiber optics for UV/Vis and NIR Raman Probes Raman Input fiber optics glove port cover centrifugal contactors installed within glovebox

Vis-NIR and Raman Multiplexer allows for multiple, simultaneous sensor locations on contactor system

September 2011 10

UV-vis Flow cell Raman Probe

On-line Spectroscopic Measurements test conditions

centrifugal contactors; 2-cm, 3600 rpm Aqueous phase: 11 mL/min Organic phase: 11 mL/min Feed: 20 mM Nd(NO3)3 4M NaNO3 0.1 M HNO3 Organic: 30% TBP/dodecane (PUREX)

Safeguards Application: spectroscopic process monitoring of diversion scenario diversion test conditions

Aqueous phase: 11 mL/min Organic phase: 11 mL/min Diversion experiment 3 mL/min of feed during flow test

Loaded organic

Solvent 30% vol% TBP/dodecane

feed raffinate

Flow Test: Diversion experiment PUREX simulant, Nd(NO3)3, HNO3, NaNO3, TBP/dodecane

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Flow rates and Amounts from Diversion Experiment Feed (aqueous) phase

Spectroscopic measurements for diversion detection

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time (min) wavelength (nm) absorbance

• rganic product (TBP/dodecane) phase

raffinate (aqueous) phase

delta from in-process

Organic Raffinate Feed Organic + Raffinate delta from in-process delta from diversion

delta from diversion

Diversion quantification: mass flow plus spectroscopic measurement

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Excellent agreement between process monitor and mass balance measurements 2.9 x 10-3 mol Nd3+ diverted based on mass balance 3.0 x 10-3 mol Nd3+ diverted based on process monitor analysis

delta from diversion

diversion started at 87 min

Conclusions

 Using simulants and BWR Spent Fuel

– Demonstrated quantitative spectroscopic measurement on actual commercial fuel samples under fuel reprocessing conditions

• Raman for on-line monitoring of U(VI), nitrate, and HNO3 concentrations, for both

aqueous and organic phases

• Vis/NIR for on-line monitoring of Np(V/VI), Pu(IV/VI), Nd(III)

 Demonstrated mass balance in on-line contactor system using low cost spectroscopic process monitoring (~USD 90K)

– During real-time centrifugal contactor TBP/dodecane extraction – Diversion of feed was quantitatively detected within contactor system – pH monitoring and simultaneous Ln (Nd3+) monitoring demonstrated with TALSPEAK system

 Future plans for on-line process monitoring

– Collaborative demonstration on commercial (larger) scale within a reprocessing canyon/plant

Acknowledgements

 U.S. Department of Energy (DOE)

– Fuel Cycle Research and Development (FCR&D), Separations Campaign (NE) – NNSA Office of Nonproliferation and International Security (NA-24)

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