TRISO-fuel element thermo-mechanical performance modeling for the hybrid LIFE engine with Pu fuel blanket

Abstract

a b s t r a c tA TRISO-coated fuel thermo-mechanical performance study is performed for the fusion-fission hybrid Laser Inertial Fusion Engine (LIFE) to test the viability of TRISO particles to achieve ultra-high burn-up of Pu or transuranic spent nuclear fuel blankets. Our methodology includes full elastic anisotropy, time and temperature varying material properties, and multilayer capabilities. In order to achieve fast fluences up to 30 Â 10 25 n m À2 (E > 0.18 MeV), judicious extrapolations across several orders of magnitude of existing material databases have been carried out. The results of our study indicate that failure of the pyrolytic carbon (PyC) layers occurs within the first 2 years of operation. The particles then behave as a single-SiC-layer particle and the SiC layer maintains reasonably-low tensile stresses until the end-oflife. It is also found that the PyC creep constant, K, has a striking influence on the fuel performance of TRISO-coated particles, whose stresses scale almost inversely proportional to K. Conversely, varying the geometry of the TRISO-coated fuel particles results in little differences in terms of fuel performance.Ó 2010 Elsevier B.V. All rights reserved. MotivationThe hybrid version of Laser Inertial Fusion Engine (LIFE) provides an attractive pathway to burn fissile materials such as excess weapons-grade Pu (WG-Pu) or transuranics from processed spent nuclear fuel, which can be burnt up to 99% fraction of initial metal atoms (FIMA) in less than a decade of operation [1]. The LIFE concept being pursued at Lawrence Livermore National Laboratory (LLNL) consists of a point source of 14-MeV neutrons produced by an inertial-confinement fusion engine enveloped by a Be neutron multiplier and a sub-critical fuel blanket. A schematic view of the LIFE engine configuration is shown in Fig. 1. Details about the geometry and the neutronic and thermal-hydraulic performance of the reactor have been given by Abbott et al. [2,3].The type of fuel to be used in the hybrid LIFE engine is still open to debate, including whether it should be in a liquid or solid form. The nominal engine design calls for 2-cm-diameter graphite pebbles containing %1-mm-diameter TRISO (TRI-structural ISOtropic) fuel particles suspended in liquid Li 2 BeF 4 ('flibe') [2]. A TRISO particle consists of an internal fuel kernel surrounded by a low-density pyrolytic carbon (PyC) buffer layer to moderate fission product recoils. The buffer layer is coated successively by an inner high-density PyC layer (iPyC), a thin SiC film, and an outer PyC (oPyC). The configuration of a TRISO particle, with its constituent layers is shown in Fig. 2. The preliminary fuel composition for the WG-Pu engine consists of 20% of Pu oxycarbide (PuCO) embedded in a ZrC matrix (80%). The main objective of this paper is to model TRISO-coated fuel particles under LIFE's conditions using the state-of-the-art in fuel performance modeling, and assess the feasibility of TRISO-coated fuel for LIFE's WG-Pu engine. Next, we review the TRISO-coated fuel perfor...

Material Performance of Fully-Ceramic Micro-Encapsulated Fuel under Selected LWR Design Basis Scenarios: Final Report

“…Based on this expected behavior and the available data up to a fluence level of ~10.0 x 10 21 n/cm 2 a correlation can be derived for fluence levels up to 30.0 x 10 21 n/cm 2 by extrapolation. In reference [14] this has been done based on experimental data from reference [15]. In this case a correlation of the following form was chosen:…”

“…The following values were used in [14] for equation (8): a = 0.140 and b = -1.324 for the tangential direction and a = 0.181 and b = -1.066 for the radial direction. The constant c was chosen to be zero for both directions.…”

Experimental measurement and numerical modeling of the effective thermal conductivity of TRISO fuel compacts

“…All the models with layered particles used the same dimensions and properties for the layers. The values used were determined from multiple sources [2,3,7,[20][21][22][23][24][25] and can be seen in Table 1. The FEA models were made parametric to study the effects of varying the particle-volume fraction between 20% and 40%.…”

TRISO Fuel Performance: Modeling, Integration into Mainstream Design Studies, and Application to a Thorium-fueled Fusion-Fission Hybrid Blanket

“…when varying the magnitude of the LLNL PyC IIDC correlation [45] or using other correlations [19,25,58,68]. .…”

“…The HUPCCO model [45], developed at LLNL, uses a thermo-mechanical stress model with specific consideration given to extending or reformulating material property correlations so that they provide stable and reasonable results at the high neutron fluence levels likely to be achieved during operation of a fusion-fission hybrid system. The current version of HUPCCO exists as a stress analysis tool only; it does not provide any functionality for predicting failure fractions for populations of TRISO particles.…”