In this paper, fuel rod performance analyses are presented for the Italian 80 MWth XADS (eXperimental Accelerator Driven System). This sub-critical system is cooled by Lead-Bismuth Eutectic (LBE), which rises on average from 300°C to 400°C at the core exit, and is fuelled with UO2-PuO2 mixed oxides. Both the ferritic-martensitic T91 and the austenitic AISI 316L steels have been considered as cladding materials, and the overall fuel rod behaviour has been simulated in normal operation conditions from the beginning to the end of life. In order to point out some critical issues related to the two steels, thermo-mechanical analyses have been accomplished also at extended burn-up. Moreover, a sensitivity study has allowed to evaluate the role of some significant aspects on fuel rod performance. Calculations have been carried out by means of the TRANSURANUS code, which has been recently adapted for modelling the behaviour of T91 and AISI 316L in LBE environment (with in situ oxide layer protection), and three different coolant channels representative of the XADS core have been considered. For the demanding operating conditions of the Hot Channel (HC), the analysis has indicated that corrosion effects would significantly degrade the whole thermo-mechanical performance of fuel rods without the adoption of appropriate protective coatings. The HC fuel rod with T91 cladding exhibits a better performance with respect to the AISI 316L rod in terms of swelling strain, maximum fuel temperature, fission gas release and inner pressure, but the resistance of T91 to radiation embrittlement and creep requires further investigation, especially under closed gap conditions (FCMI - Fuel Cladding Mechanical Interaction).
Fuel Rod Performance Analysis for the Italian LBE-XADS: A Comparison of Two Different Cladding Materials
LUZZI, LELIO;PASTORE, GIOVANNI
2011-01-01
Abstract
In this paper, fuel rod performance analyses are presented for the Italian 80 MWth XADS (eXperimental Accelerator Driven System). This sub-critical system is cooled by Lead-Bismuth Eutectic (LBE), which rises on average from 300°C to 400°C at the core exit, and is fuelled with UO2-PuO2 mixed oxides. Both the ferritic-martensitic T91 and the austenitic AISI 316L steels have been considered as cladding materials, and the overall fuel rod behaviour has been simulated in normal operation conditions from the beginning to the end of life. In order to point out some critical issues related to the two steels, thermo-mechanical analyses have been accomplished also at extended burn-up. Moreover, a sensitivity study has allowed to evaluate the role of some significant aspects on fuel rod performance. Calculations have been carried out by means of the TRANSURANUS code, which has been recently adapted for modelling the behaviour of T91 and AISI 316L in LBE environment (with in situ oxide layer protection), and three different coolant channels representative of the XADS core have been considered. For the demanding operating conditions of the Hot Channel (HC), the analysis has indicated that corrosion effects would significantly degrade the whole thermo-mechanical performance of fuel rods without the adoption of appropriate protective coatings. The HC fuel rod with T91 cladding exhibits a better performance with respect to the AISI 316L rod in terms of swelling strain, maximum fuel temperature, fission gas release and inner pressure, but the resistance of T91 to radiation embrittlement and creep requires further investigation, especially under closed gap conditions (FCMI - Fuel Cladding Mechanical Interaction).I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.