Neutron radiography study of a LaNi5-based hydrogen storage device

MEYER G. O.; BARUJ A.; BORZONE E. M.; CÁRDENAS R.; SOMOZA J.; RIVAS S.; SÁNCHEZ F. A.; MARÍN J.

Florianópolis

Congreso; XI Congresso SBPMat; 2012

SBPMAT - Sociedade Brasileira de Pesquisa em Materiais

Devices based on the use of hydride forming materials (HFM) represent a safe and efficient option for hydrogen storage and transport. However, it is usually necessary to modify some of the hydride properties in order to make them suitable for specific applications. For example, even the simplest design of a hydride containing device for mobile applications must take into account the poor thermal conductivity of these alloys in order to optimize heat exchange and achieve an adequate hydrogen flow on discharge. Although simulation of HFM behaviour during the operation of these devices reduces costs and design time, it is not always reliable because hydride formation or decomposition is a first order transition with an important heat of reaction, the equilibrium pressure depends on temperature and degree of reaction, and some hysteresis is always present. Therefore, the design of experiments to validate simulation hypothesis are always welcomed, mainly if they are non destructive ones. Neutron radiography (NR) is a recently developed non-destructive technique that permits the direct observation of hydrogen localization.In this work we present images of a hydrogen storage prototype based on the use of a hydride forming material (LaNi5) obtained in the newly assembled NR line at the experimental nuclear reactor RA-6 located in Bariloche. The technique allows correlating optical contrast variations in the images with the different neutron interaction levels of the components of the device. Neutron interaction is strong with hydrogen, while being weak with most standard structural metals, thus allowing the preferential analysis of hydrides inside containers. Figure 1 shows an example of the images obtained on the hydrogen storage prototype. NR images during in-situ operation of the device provide a valuable information that can be used to correlate the relevant control parameters, like hydrogen flow, outlet pressure and hydride temperature, with the observed hydrogen spatial distribution inside the container. This information can be used to validate device operation simulations and models and to achieve advanced design and testing capabilities.