Investigation of crack propagation resistance of 304L, 316L and 316L(N) austenitic steels in liquid sodium

In order to assess the susceptibility of candidate structural materials to Liquid Metal Embrittlement (LME), the fracture behavior of three grades of austenitic steels was investigated in oxygenated (200 wppm) liquid sodium in the temperature range [473–673 K] on notched axisymmetric tensile specimens. The tests were carried out in an inert glove box at very low concentrations of dioxygen and humidity (<1 ppm) to prevent further contamination after pre-exposure in oxygenated liquid sodium. A decrease in crack propagation resistance of the three austenitic steels (304 L, 316 L(N), 316 L) is observed in oxygenated liquid sodium (200 wppm) from 573, 623 and 673 K respectively after pre-wetting in oxygenated sodium. This reduction is correlated with a ductile to brittle change of the fracture surface. This effect observed with the three austenitic steels is attributed to the onset of LME after significant plastic deformation

Progress Report on Target Development

The present document is the D08 deliverable report of work package 1 (Target Development) from the MEGAPIE TEST project of the 5th European Framework Program. Deliverable D08 is the progress report on the activities performed within WP 1. The due date of this deliverable was the 5th month after the start of the EU project. This coincided with a technical status meeting of the MEGAPIE Initiative, that was held in March 2002 in Bologna (Italy). The content of the present document reflects the status of the MEGAPIE target development at that stage. It gives an overview of the Target Design, the related Design Support activities and the progress of the work done for the safety assessment and licensing of the target

Corrosion of Fe-9Cr Steels in Sodium Fast Reactors Environments

The sodium cooled fast reactor is selected by France as the most mature GEN IV concept to be industrially developed by the year 2040. A collaborative research program has been established together with EDF and Areva NP. In this program, different innovations are being considered in the design of the reactor leading to the use of various environments apart from liquid sodium and water vapor encountered in the “classical” sodium fast reactors. As a matter of fact, considerations on the suppression of the water-sodium reaction risk led to the proposal of the use of alternative coolants such as Pb-Bi involving an intermediate circuit between the primary sodium and the steam generator. Other concepts involve the use of supercritical CO2 instead of water vapor in the energy conversion system. In all cases, structural materials encounter severe conditions regarding corrosion concerns: high temperatures and possibly aggressive chemical environments. In this paper, status of the research performed in CEA on the corrosion behavior of the structural material and especially Fe-9Cr steels is presented in the various environments: sodium (see paper by JL Courouau), Pb-Bi, water vapor and CO2. The materials studied are metallic materials: austenitic and ferrito-martensitic steels as well as ODS steels as an option for the cladding material. In the different environments studied, the scientific approach is identical, the objective being in all cases the understanding of the corrosion processes to establish recommendations on the chemistry control of the coolant and to predict the long term behavior of the materials by the development of corrosion models. First, the corrosion mechanisms are analyzed using dedicated experimental devices. As a matter of fact, the complex environments require also controlled, safe and precise experimental systems to perform long duration corrosion tests (several thousands of hours). Therefore, specific experiments, adapted to each corrosive medium, are carried out in the laboratory. For example: - laboratory scale loops are used for liquid metals corrosion studies (use of rotating cylinders to simulate high turbulent conditions), - thermogravimetric analyses are also used to perform gas corrosion studies in representative temperature and environmental conditions,… Then, multi-scale characterization of the materials studied is performed (FEG-SEM, EDX, XRD, GD-OES…), together with precise analyses of the environments tested (in situ measurements with specific probes, gas chromatography…). Corrosion mechanisms are then proposed and models developed, depending on the advancement and the maturity of the program

Final Summary Report on Target Design

The present document is the D13 deliverable report of work package 1, Target Development, from the MEGAPIE TEST project of the 5th European Framework Program. Deliverable D13 is the final summary report on the activities performed within WP 1. The manufacturer (ATEA) has indicated to deliver the target to PSI in the middle of 2005. Assuming that this date is realistic, it can be foreseen that the integral out-of beam test will be conducted during the end of the year 2005 and the beginning of the year 2006. It can be assumed that the irradiation of the MEGAPIE target will start during the second quarter of 2006. The content of the present work package 1 final summary report reflects the status of the MEGAPIE target and ancillary system development at the end of 2004