Work Package 2

Welding development and characterization

The objectives of GEMMA WP2 are to characterize welded components with respect to microstructure, to determine welding residual stresses, to establish test procedures and to derive reference material data on mechanical properties in air. In collaboration with WP1 and WP4, the aim is to provide recommendations for adapting and/or developing assessment procedures and Design Rules for welded components in liquid metal cooled nuclear reactors. The work is performed in support of the component design, safety assessments and licensing of European liquid metal cooled fast reactors: Sodium-cooled Fast Reactor (SFR) demonstrator ASTRID (Advanced Sodium Technological Reactor for Industrial Demonstration), MYRRHA technology prototype for Lead-cooled Fast Reactors (LFR), and ALFRED demonstrator for LFR. Since AFCEN’s (Association Française pour les règles de Conception de construction et de surveillance en Exploitation des matériel des chaudières électroNucléaires) RCC-MRx Design Code has been chosen for the design of ASTRID, MYRRHA and ALFRED, the primary goal is to support the development of Design Rules for RCCMRx. The activities contribute towards the objective of EERA JPNM and CEN Workshop 64 to develop RCCMRx into a joint European code for all future European innovative nuclear installations.

The activities assume having available sufficient quantities of reference welds (coupons) following the RCCMRx specifications delivered by partners in-kind in WELLMET. WELLMET is an in-kind Pilot Project launched in the frame of EERA JPNM. Additionally, eight welded specimens will be manufactured (using ASTRID reference materials and Welding Procedure Specifications) and specifically instrumented to allow modelling of residual stresses and related effects of post-weld heat treatment, building on activities conducted in-kind in the frame of EERA JPNM Pilot Project RESTRESS. Measurements of the residual stresses by different techniques will be undertaken for validation of the models. The microstructure and reference mechanical properties in air of all these welds will then be characterised for base material, heat affected zone and weld material, the latter both in longitudinal and transversal directions. Comprehensive reference microstructural analysis of these specimens will be conducted to allow characterisation of the involved degradation mechanisms (in collaboration with WP4 where tests will be performed in HLM environments) and of the welding residual stresses (incl. the effect of post-weld heat treatment). Finally, WP2 (in collaboration with WP1 and WP4) will provide recommendations on how to develop and/or adapt Design Rules in RCC-MRx for manufacturing and design of components with welds for MYRRHA and ALFRED, as well as for ASTRID.

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