Failure Criteria for Unirradiated PWR Cladding Subjected to Ring Compression Tests

2015 ◽  
Author(s):  
Jesus Ruiz-Hervias ◽  
Miguel Angel Martin-Rengel ◽  
Francisco Javier Gomez-Sanchez
Keyword(s):  
Radial Direction ◽  
Experimental Testing ◽  
Failure Criteria ◽  
Spent Fuel ◽  
Compression Tests ◽  
Fuel Cladding ◽  
Ring Compression Test ◽  
Ring Compression ◽  
Nuclear Fuel Cladding ◽  
Hydride Reorientation

The ring compression test applied to nuclear fuel cladding is relatively easy to perform but difficult to interpret. It can be representative of the loading state associated to a hypothetical spent fuel assembly drop accident. This is particularly important for spent fuel cladding subjected to drying operations previous to storage and transportation, because they may produce hydride reorientation along the radial direction of cladding. In this paper, experimental testing and numerical simulations are combined to obtain operative failure criteria from the results of the ring compression tests on unirradiated pre-hydrided samples with radial hydrides, simulating drying, storage and subsequent transport conditions.

Evaluation of Friction Properties of Magnesium Alloy during Hot Forging by Ring Compression Test

2017 ◽  
Vol 889 ◽  
pp. 119-126
Author(s):  
Sueji Hirawatari ◽  
Hisaki Watari ◽  
Shinichi Nishida ◽  
Yuki Sato ◽  
Mayumi Suzuki
Keyword(s):  
Magnesium Alloys ◽  
Compression Test ◽  
Hot Forging ◽  
Hot Forming ◽  
Compression Tests ◽  
Ring Compression Test ◽  
Stress Strain ◽  
Friction Coefficients ◽  
Ring Compression ◽  
Velocity Motion

This paper deals with friction properties and deformation resistance during hot forming of Mg-Al-Ca-Mn series magnesium alloys. Friction coefficients between dies and magnesium alloys were obtained by ring compression tests that used graphite, PTFE, and an oil lubricant in a hot-forging process. Hot forging was performed under various conditions to clarify the effects of types of lubricants and slide motion of the press machines on friction properties. Two types of slide motion, a constant velocity motion and a pulse motion were selected in the ring-compression test. It was found that graphite with an oil lubricant effectively eliminated die sticking in hot forming of magnesium alloys. The isothermal deformation resistances were derived using friction coefficients obtained by ring-compression tests as well as finite-element simulations. The predicted stress strain curves with temperature were examined with the stress-strain relationship obtained in experiments using a servo press and demonstrated the effectiveness of the proposed method.

Interfacial Friction of Ceramics at High Temperature Ring-Compression Test

2011 ◽  
Vol 704-705 ◽  
pp. 967-972
Author(s):  
Hui Gai Wang ◽  
Yan Pei Song ◽  
Fei Wang ◽  
Kai Feng Zhang
Keyword(s):  
High Temperature ◽  
Boron Nitride ◽  
Friction Factor ◽  
Compression Test ◽  
Elevated Temperatures ◽  
Interfacial Friction ◽  
Average Pressure ◽  
Compression Tests ◽  
Ring Compression Test ◽  
Ring Compression

Using ring compression tests, the interfacial friction and flow stress of 3Y-TZP/Al2O3 composite at elevated temperatures were investigated. Theoretical calibration curves of the friction factor and the relative average pressure curves for the ring compression tests of 6:3:2 standard rings were drawn based on a velocity field capable of describing the bulge phenomena. The lubricant was the boron nitride (hexagonal). The tests were adopted at temperature range of 1400°C-1600°C. Results indicate that the interfacial friction factor has the value in the range of 0.34-0.49, so that boron nitride lubricant can be used effectively in present temperatures. As two extremely important parameters, the temperature and strain rate have no significant effect on the fraction factor. It is proved reliable that the ring-compression test at 1400°C and even higher is used to evaluate the performance of boron nitride lubricant.

Comparison of Ring Compression Testing to Three Point Bend Testing for Unirradiated ZIRLO Cladding

2015 ◽  
Author(s):  
Paul S. Korinko ◽  
Robert L. Sindelar ◽  
Ronald L. Kesterson
Keyword(s):  
Compression Test ◽  
Water Oxidation ◽  
National Laboratory ◽  
Solubility Limit ◽  
Hydrogen Release ◽  
Compression Tests ◽  
Ring Compression Test ◽  
Controlled Cooling ◽  
Ring Compression ◽  
Point Bend

Safe shipment and storage of nuclear reactor discharged fuel requires an understanding of how the fuel may perform under the various conditions that can be encountered. One specific focus of concern is performance during a shipment drop accident. Tests at Savannah River National Laboratory (SRNL) are being performed to characterize the properties of fuel clad relative to a mechanical accident condition such as a container drop. Unirradiated ZIRLO tubing samples have been charged with a range of hydride levels to simulate actual fuel rod levels. Samples of the hydrogen charged tubes were exposed to a radial hydride growth treatment (RHGT) consisting of heating to 400°C, applying initial hoop stresses of 90 to 170 MPa with controlled cooling and producing hydride precipitates. Initial samples have been tested using both a) ring compression test (RCT) which is shown to be sensitive to radial hydride and b) three-point bend tests which are less sensitive to radial hydride effects. Hydrides are generated in Zirconium based fuel cladding as a result of coolant (water) oxidation of the clad, hydrogen release, and a portion of the released (nascent) hydrogen absorbed into the clad and eventually exceeding the hydrogen solubility limit. The orientation of the hydrides relative to the subsequent normal and accident strains has a significant impact on the failure susceptability. In this study the impacts of stress, temperature and hydrogen levels are evaluated in reference to the propensity for hydride reorientation from the circumferential to the radial orientation. In addition the effects of radial hydrides on the Quasi Ductile Brittle Transition Temperature (DBTT) were measured. The results suggest that a) the severity of the radial hydride impact is related to the hydrogen level-peak temperature combination (for example at a peak drying temperature of 400°C; 800 PPM hydrogen has less of an impact/ less radial hydride fraction than 200 PPM hydrogen for the same thermal history) and b) for critical strains in post drying handling, storage and accident conditions the 3 point bend strain tolerance is less affected by radial hydrides than the conventional ring compression test (the radial hydride related Quasi DBTT associated with a three point bend straining is lower (better) than that measured by the ring compression tests).

Superimposed Oscillating and Non-Oscillating Ring Compression Tests for Sheet-Bulk Metal Forming Technology

2015 ◽  
Vol 794 ◽  
pp. 89-96 ◽  
Author(s):  
S. Koch ◽  
Milan Vucetic ◽  
Sven Hübner ◽  
Anas Bouguecha ◽  
Bernd Arno Behrens
Keyword(s):  
Compression Test ◽  
Metal Forming ◽  
Compression Tests ◽  
Ring Compression Test ◽  
Oscillation System ◽  
Bulk Metal ◽  
Bulk Metal Forming ◽  
Forming Technology ◽  
Water Jet Cutting ◽  
Ring Compression

The new manufacturing technology sheet-bulk metal forming (SBMF) combines the sheet metal forming and bulk metal forming techniques. At the Institute of Forming Technology and Machines (IFUM), a new multistage SBMF process is being developed. In order to reduce the friction and improve the dimensional accuracy of the parts, superimposed oscillation is used within the new SBMF process. SBMF processes allow the manufacturing of solid metal components out of flat steel. To analyse the effect of friction on the superimposed oscillating SBMF process more precisely, superimposed oscillating and non-oscillating ring compression tests at room temperature were carried out. Like the semi-finished products for SBMF process the ring specimens were cut out of a sheet plate by water jet cutting. A new tool system with an integrated hydraulic oscillation system was developed for superimposed oscillating compression of the ring specimens. This tool system enables the absorption of the forming force and displacement stroke of the ring specimen during the ring compression test. After the practical experiments, the force profiles of superimposed oscillating and of non-oscillating process were compared. The influence of the frequency on the surface roughness of ring specimens was investigated. Furthermore, the tribological conditions of the superimposed oscillating ring compression test were analyzed.

Structural integrity of hydrided nuclear fuel cladding

2012 ◽  
Vol 1475 ◽  
Author(s):  
Jesús Ruiz-Hervías ◽  
F. Javier Gomez ◽  
Miguel A. Martín-Rengel ◽  
Elena Torres
Keyword(s):  
Nuclear Fuel ◽  
Structural Integrity ◽  
Element Model ◽  
Testing Temperature ◽  
Cohesive Crack ◽  
Crack Model ◽  
Fuel Cladding ◽  
Ring Compression ◽  
Different Temperatures ◽  
Nuclear Fuel Cladding

ABSTRACTThe structural integrity of nuclear fuel cladding is affected by the precipitation of hydrides during operation, which may embrittle the cladding. The aim of this work is to obtain the mechanical and fracture properties of the cladding as a function of the hydrogen content and testing temperature. To this end, the embrittlement caused by circumferential hydrides was simulated on unirradiated fuel cladding samples in the laboratory. The structural integrity of the cladding was assessed at different temperatures (20, 135 and 300ºC), by using the ring compression test. The mechanical properties and the fracture energy were calculated from the experimental load vs. displacement curves, by means of a finite element model which incorporates the cohesive crack model.

Ductility Evaluation of As-Hydrided and Hydride Reoriented Zircaloy-4 Cladding under Simulated Dry-Storage Condition

2014 ◽  
Vol 1645 ◽  
Author(s):  
Y. Yan ◽  
L. K. Plummer ◽  
H. Ray ◽  
T. Cook ◽  
H. Z. Bilheux
Keyword(s):  
Early Stage ◽  
Maximum Load ◽  
Storage Condition ◽  
Normal Operation ◽  
Ring Compression Test ◽  
Ring Compression ◽  
Lower Strain ◽  
Ductile To Brittle Transition ◽  
Hydride Reorientation ◽  
Hoop Stresses

ABSTRACTPre-storage drying-transfer operations and early stage storage expose cladding to higher temperatures and much higher pressure-induced tensile hoop stresses relative to normal operation in-reactor and pool storage under these conditions. Radial hydrides precipitate during cooling and could provide an additional embrittlement mechanism as the cladding temperature decreases below the ductile-to-brittle transition temperature. To simulate this behavior, unirradiated Zircaloy-4 samples were hydrided by a gas charging method to levels that encompass the range of hydrogen concentrations observed in current used fuel. Mechanical testing was carried out by the ring compression test (RCT) method at various temperatures to evaluate the sample’s ductility for both as-hydrided and post-hydride reorientation treated specimens. As-hydrided samples with higher hydrogen concentration (>800 ppm) resulted in lower strain before fracture and reduced maximum load. Increasing RCT temperatures resulted in increased ductility of the as-hydrided cladding. A systematic radial hydride treatment was conducted at various pressures and temperatures for the hydrided samples with H content around 200 ppm. Following the radial hydride treatment, RCTs on the hydride reoriented samples were conducted and exhibited lower ductility compared to as-hydrided samples.

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