Design and structural assessment of the Spallation Neutron Source 2.0 MW target

Johns, Kevin; Mach, Justin; Gorti, Sarma B; Jiang, Hao

doi:10.1016/j.nima.2021.165799

Cited by 4 publications

(1 citation statement)

References 14 publications

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“…The strain/stress results from finite element simulation are utilized further in fatigue analysis to estimate component's lifetime and integrity. So, the strain response collected from simulation, particularly the strain peaks and the strain range (max strain -min strain) of the profile are critical in estimating steel vessel's fatigue cycles, as demonstrated by recent efforts [36,37]. At most sensors except R, T and G, the predicted peaks of sensor strains shown in Figure 8 are close to or higher than the experimental mean values in the short 0.001 second history.…”

Section: Inverse Uq Resultsmentioning

confidence: 66%

Bayesian Inverse Uncertainty Quantification of the Physical Model Parameters for the Spallation Neutron Source First Target Station

Radaideh,

Lin,

Jiang

et al. 2022

Preprint

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The reliability of the mercury spallation target is mission-critical for the neutron science program of the spallation neutron source at the Oak Ridge National Laboratory. We present an inverse uncertainty quantification (UQ) study using the Bayesian framework for the mercury equation of state model parameters, with the assistance of polynomial chaos expansion surrogate models. By leveraging high-fidelity structural mechanics simulations and real measured strain data, the inverse UQ results reveal a maximum-a-posteriori estimate, mean, and standard deviation of 6.5 × 10 4 (6.49 × 10 4 ± 2.39 × 10 3 ) Pa for the tensile cutoff threshold, 12112.1 (12111.8 ± 14.9) kg/m 3 for the mercury density, and 1850.4 (1849.7 ± 5.3) m/s for the mercury speed of sound. These values do not necessarily represent the nominal mercury physical properties, but the ones that fit the strain data and the solid mechanics model we have used, and can be explained by three reasons. First, the limitations of the computer model or what is known as the "model-form uncertainty" that would result from numerical methods and physical approximations. Second, is the biases and errors in the experimental data. Third, is the mercury cavitation damage that also contributes to the change in mercury behavior. Consequently, the equation of state model parameters try to compensate for these effects to improve fitness to the data. The mercury target simulations using the updated parametric values result in an excellent agreement with 88% average accuracy compared to experimental data, 6% average increase compared to reference parameters, with some sensors experiencing an increase of more than 25%. With a more accurate strain response predicted by the calibrated simulations, the component fatigue analysis can utilize the comprehensive strain history data to evaluate the target vessel's lifetime closer to its real limit, saving tremendous target cost and improving the design of future targets as well.

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Section: Inverse Uq Resultsmentioning

confidence: 66%