Studies on Super-critical Water Reactors Fuel Assemblies using the Sub-channel Code COBRA-EN

In the Generation IV International Forum (GIF) programme, the Super-Critical Water Reactor (SCWR) concept is among the six innovative reactor types selected for development in the near future. In principle the higher efficiency and better economics make the SCWR concept competitive with the current reactor design. Due to different technical challenges that, however, exist fuel assembly design represents a crucial aspect for the success of this concept. In particular large density variations, low moderation, heat transfer enhancement and deterioration have a strong effect on the core design parameters. Only a few computational tools are currently able to perform sub-channel thermal-hydraulic analysis under super-critical water conditions. At JRC-IE the existing sub-channel code COBRA-EN has been improved to work above the critical pressure of water. The water properties package of the IAPWS Industrial Formulation 1997 was integrated in COBRA-EN to compute the Thermodynamic Properties of Water and Steam. New heat transfer and pressure drop correlations more indicated for the super-critical region of water have also been incorporated in the code. As part of the efforts to assess the new code capabilities, both a hexagonal and a square fuel assembly have been analysed. In the latter case the use of the code in combination with the neutronic code MCNP has allowed investigating on the use of hydride fuel in super-critical fuel assembly. The results showed that COBRA-EN was able to reproduce the results of similar studies with acceptable accuracy. Future activities will focus on the validation of the code against experimental data and the implementation of new features (wall, wire wrap models).

AMMIRABILE Luca; 

2010-09-30

ELSEVIER SCIENCE SA

JRC55408

0029-5493,   

www.elsevier.com/locate/nucengdes,    https://publications.jrc.ec.europa.eu/repository/handle/JRC55408,   

10.1016/j.nucengdes.2010.05.025,