Development and validation of simulation model for ADS beam interruption transient

Accelerator Driven Sub-critical System (ADS) applies the spallation neutrons as the external neutron source to drive the sub-critical reactors. It has the sub-critical inherent safety feature and the large flux and powerful transmutation ability for long-lived radiation nucleus, and it has been universally regarded as the most promising approach to dispose the long-lived nuclear wastes. In the ADS system, the external neutron source is generated by the proton beam bombarding of the spallation targets. The beam interruption transients will directly cause the power fluctuation of the subcritical reactor core, and then affect the safety of the whole ADS system. In this paper, a new ADS beam interruption transient model is promoted by researching the existed ADS model and methods worldwide. Based on the universal CFD programme FLUENT, the new model FIUENT-ADS is developed by integrating Point Kinetic Model (PKM) and Pin Thermal Model (PTM) with the assistance of User Defined Functions (UDF) tools. Validated by the international benchmark published by OECD/NEA, the key validating parameters could meet the results in this paper with a maximum calculation error of 5.2% which is equivalent to other international calculation programmes with similar functions. The results demonstrate that the new model has certain credibility, and it could meet the preliminary requirements of the research and analysis of ADS beam interruption transient. (authors)