ML23214A034
| ML23214A034 | |
| Person / Time | |
|---|---|
| Issue date: | 08/02/2023 |
| From: | -Neednewvalue, Rojas J Office of Nuclear Regulatory Research |
| To: | |
| Shared Package | |
| ML23214A033 | List: |
| References | |
| Download: ML23214A034 (1) | |
Text
Project:
Advanced characterization of ATF cladding for understanding their degradation under short-time temperature excursions and implications in dry storage PI: Jessika Rojas, Associate Professor Co-PI:
Carlos E. Castano (Assistant professor)
Braden Goddard (Assistant Professor)
Reza Mohammadi (Associate Professor)
Virginia Commonwealth University U.S. Nuclear Regulatory Commissions 35th Annual Regulatory Information Conference
This work is being supported by NRC University Nuclear Leadership Program Industry and University collaborators:
Nanomaterials Characterization Core Facility at VCU Ge Global Research (Andrew Hoffman),
Rajnikant Umretiya Acknowledgements TEAM MEMBERS Dr. Reza Mohammadi MNE Dr. Carlos E.
Castano MNE Dr. Braden Goddard MNE Dr. Jessika Rojas MNE Victoria Davis Ph.D student, MNE Caleb King UG. Res. Asst. MNE Tristan Norrgard UG. Res. Asst. MNE Christian England UG. Res. Asst. MNE James Cahill Ph.D. student MNE 2
Moving on to the topic of todays talk 3
o Fukushima nuclear disaster The Fukushima Daiichi Accident Report by the Director General (2015)
Earthquake Tsunami Zr + 2 H2O ZrO2 + 2 H2 Exothermic reaction and release of hydrogen Hydrogen explosion Zircaloy How to improve the safety and reconstruct the publics confidence in nuclear power?
radioactive release https://world-nuclear.org/
Accident Tolerant Fuel Technologies 4
Improved Clad Reaction Kinetics with Steam o
Heat of Oxidation o
Oxidation rate o
Hydrogen bubble and explosion o
Hydrogen embrittlement of the clad Improved Fuel Properties o
Lower operating temperatures o
Clad internal oxidation o
Fuel relocation o
Fuel melting Improved Cladding Properties o
Clad fracture o
Geometric stability o
Thermal shock resistance o
Melting of the cladding Enhanced Retention of Fission Products o
Gaseous fission products o
Solid/liquid fission products Arevas Enhanced Accident Tolerant Fuel Program (2017)
ATF Claddings Concept 1 Surface modification Zr alloys Surface coating FeCrAl Cr Mo SiC Concept 2 Replacement Alloys APMT C26M 310SS
How do these cladding concepts evolve at high temperatures?
5 How does the material evolves at high temperatures and how quick?
Surface characterization before and after CHF testing Cladding Heat flux Fuel Pellet Coolant:
water After CHF Zr-4 PVD Cold Spray The following reactor parameters affect safety margins:
- Reactor power
- Reactor coolant flow rate
- Reactor coolant inlet temperature
- Reactor coolant pressure Umretiya, R.V., Elward, B., Lee, D., Anderson, M., Rebak, R.B. and Rojas, J.V., 2020. J. Nuc. Mat., 541, p.152420.
Project Goals 6
The main goal of this project is to investigate the oxidation and degradation of accident-tolerant fuel (ATF) claddings, both Cr-coated Zircaloy and FeCrAl alloys, under short time temperature excursions and quenching performance that will reveal their behavior and evolution during accident scenarios.
This project also investigates the mechanical properties of these materials relevant to dry storage conditions.
Implementing (ATF) cladding in light water reactors (LWRs) and advanced reactor designs aims to improve fuel reliability and safety during design-basis and beyond-design-basis accident scenarios.
Implementation of non-destructive examination techniques for quality control of coated Zircaloy.
Zr-4 subjected to rapid heating and cooled in air or water
Research Objectives 7
Aim 1: ATF cladding selection, sample manufacturing, and characterization:
- Use various advanced materials characterization techniques to study surface characteristics microstructure, materials surface chemistry, mechanical properties Aim 2: Short-time temperature excursions and quenching:
- We will investigate cylindrical specimens of both pristine and aged specimens
- The aging process: samples exposed to BWR and PWR using a hydrothermal autoclave
- The specimens will be subjected to high temperature heating profiles to peak temperatures ~1400 C Aim 3: Simulated dry-storage conditions and ductility studies:
- The simulated dry storage conditions for the specimens: Interim Staff Guidance 11, Rev. Spent Fuel Project Office Aim 4-5: Development of X-ray fluorescence spectroscopy ATF cladding non-destructive examination:
- Design and construction of XRF setup for continuous analysis of cylindrical specimens The versatility of X-ray fluorescence spectroscopy will allow for simultaneous elemental composition and coating thickness analysis
8 Materials Selection and characterization Figure 1. ATF cladding samples selected for materials characterization. In the photograph, A)
FeCrAl alloy C26M, B) Zircaloy-4, C) Cr-coated Zr-4 prepared by PVD, D) Cr-coated Zr-4 prepared by Cold-spray Phenom ProX SEM Scanning Electron Microscope (SEM) used to image sample surfaces Equipped with energy dispersive spectroscopy (EDS)
Sample mounted on a powder specimen holder filled with polyvinylpyrrolidone (PVP) powder for XRD analysis PANalytical XPert Pro Diffractometer To obtain crystalline structure of materials PHI VersaProbe III X-ray Photoelectron Spectrometer To study chemistry of sample surface JEOL JEM-F200 TEM Transmission electron microscope for nanoscale analysis
Coating deposition: Cr-Zr4 9
o The XRD patterns of the substrate Zr-4 and Cr-coated Zr-4 (PVD and Cold spray) confirm the hexagonal closed packed crystal structure of substrate and the presence of Cr layer with cubic crystal structure.
o SEM micrographs evidence a Cr coating thickness of AR-Zr4-Cr-CS and AR-Zr4-Cr-PVD of 29.0+/-2.0 µm and 6.48+/-1.41 µm, respectively.
Cross sectional SEM view for Cr-coated Ziraloy-4: a) AR-Zr4-Cr-CS and b) AR-Zr4-Cr-PVD Cr-coating Zircaloy-4 Cr-coating Zircaloy-4 a) b)
X-ray diffraction patterns of Zircaloy-4 (AR-Zr4), AR-Zr4-Cr-PVD and AR-Zr4-Cr-CS.
(110)
(200)
(211)
(220)
(101)
(002)
(102)
(110)
(103)
(112)
(004)
(202)
(211)
(114)
10 FeCrAl Alloys: another alternative SEM micrograph of etched FeCrAl APMT Average grain size 8.35 +/- 2.03 µm SEM micrograph of etched FeCrAl C26M Average grain size 46.04 +/- 19.50 µm
%wt.
Cr Al Mo Y
Si Fe C26M 11.894 5.263 1.978 0.027 0.279 Balance APMT 21.146 2.701 3.059 0.127 0.886 Balance
11 Design of Temperature Excursions and Quenching device Induction coil where samples are centered for testing Pyrometer with data acquisition software for measuring temperature during testing Stainless steel Bubbler system as steam generator Water container for quenching process Flowmeter for measuring argon input flow Submersible Pump for Water, Impact-Resistant/Open-Air, 120V AC a 7.5 kW high-frequency (100-400 kHz) induction furnace Temperature excursion and quenching setup.
SolidWorks model showing the inputs for steam, water, and argon into the system.
Stainless steel rod Set screws Drill bushing Sample rod
Example of heat excursion and water quenching 12 Video of thermal shock event at 30% power of the induction furnace Date acquisition software recording temperature of the sample from the pyrometer Photograph of thermal Shock at 30%
power of the induction furnace
13 Preliminary results with Zr-4 and Zr-702 The top images show sample rods heated and cooled in air. The bottom images show sample rods heated with quenching.
1% 5% 10% 16%
5% 10% 15% 20%
Temperature profiles of Zr-4 in dry air The system can achieve a maximum heating rate of 100 ºC/s
14 Preliminary results with Zr-4 and Zr-702 SEM micrographs of Zr-702 after rapid to various temperatures and water quenching a) 800 ºC b) 865 ºC c) 1200 ºC.
Average thickness of the oxide layer is 3.4 +/- 0.4 µm, 8.8 +/- 1.1 µm, 21.9 +/- 8.3 µm, respectively ZrO2
-Zr(O)
Prior ZrO2
-Zr(O)
Prior ZrO2
-Zr(O)
Prior ZrN
15 Progress on X-ray fluorescence spectroscopy for ATF Quality control X-ray fluorescence working principle for elemental analysis X-ray beam spot size 3 mm Thickness measurements down to nanometer scale; ability to evidence thickness variations and lack of coating.
Fig. 1. Diagram of X-ray tube from C.
Turner, et al., Mobile Miniature X-ray Source IXRi IXRs layer IXRs subs
16 MCNP simulation of the X-ray source for benchmarking with the experimental results Effect of W collimator and 1 µm graphene window on the spectrum generated by an 8 and 15 keV electron beam Transmission spectra produced by the Ag target anode with an incident electron beam energy of 8, 15, 20, and 50 keV The future work include validating the X-ray simulated beam with the emission spectra from several substrates.
Defects will be manufactured on the surface of the Cr-coated Zr-4 specimens and XRF spectra at various length steps will be collected to determine the resolution of the device for quality control
17 Concluding remarks:
Accident tolerant fuel cladding materials have been acquired and characterized. FeCrAl alloys and Cr-coated Zircaloy-4, produced by PVD and cold spray, are the focus of our work.
A system for heat excursion and quenching procedures has been designed and built. The system relies the induction mechanism to heat the metallic samples at a high rate. The device includes several components that includes gas, steam, and water inlets.
Preliminary tests have been conducted with Zr-4 and Zr-702 to optimize the device. The results obtained for these specimens aligned with those reported in the literature on high temperature oxidation of Zircaloys in various environments.
Monte Carlo N-Particle simulations have been completed to generate an X-ray spectrum of our handheld device. The results of the modeling implemented to achieve the output spectrum of the XRF device are supported by the presence of predicted characteristic X-rays and X-ray attenuation.
Design of experiments for FeCrAl and Cr-coated Zr cladding for high temperature excursions and quenching.
The output spectra obtained for the XRF device will be used as the source definition for future models. The spectra will be used to produce fluorescence in various material specimens.
Dry storage simulated environments, temperature profiles and hoop stresses, are being determined. A loading mechanism has been designed and is being manufactured.
Future work:
18 Thank You!!
Questions??
Contact Information:
Jessika Rojas, Associate Professor Virginia Commonwealth University jvrojas@vcu.edu