Thermal-hydraulic design and transient evaluation of a small long-life HTR

• Published in: Nuclear engineering and design 2013-02, Vol.255, p.347-358
• Main Authors: Ding, Ming, Kloosterman, Jan Leen
• Format: Article
• Language: English
• Subjects: Applied sciences; Controled nuclear fusion plants; Energy; Energy. Thermal use of fuels; Exact sciences and technology; Fission nuclear power plants; Fuels; Heat transfer; Installations for energy generation and conversion: thermal and electrical energy; Nuclear fuels; Theoretical studies. Data and constants. Metering
• ISSN: 0029-5493; 1872-759X
• DOI: 10.1016/j.nucengdes.2012.11.009

► We present the thermal-hydraulic evaluations of a small, long-life and block-type HTR using the DALTON/THERMIX code system. ► A cross section generation methodology is developed and verified for the diffusion calculations of the small HTR. ► The thermal-hydraulic characteristics of the small HTR during pressurized loss of forced-cooling incidents are compared with depressurized loss of forced-cooling ones. ► The thermal-hydraulic characteristics of a cylindrical core are compared with an annular one. ► Thermal power limit of the small HTR is investigated based on depressurized loss of forced-cooling incidents. Small long-life high temperature gas-cooled reactors (HTRs) may provide electricity or heat for remote areas or industrial users in developed and/or developing countries. Moreover, small HTRs have advantages over large nuclear reactors of demonstrated inherent safety, transportability, modular construction, and flexible site selection. This paper presents the thermal-hydraulic evaluations of the U-Battery, which is a small, long-life and block-type HTR using the DALTON/THERMIX code system. The thermal-hydraulic characteristics of a cylindrical design and an annular design of the U-Battery were evaluated for loss of forced-cooling (LOFC) incidents including depressurized LOFC (DLOFC) and pressurized LOFC (PLOFC) incidents. The calculations show that the stronger natural circulation during the PLOFC makes the reactor core cool faster than during the DLOFC, flattens the radial solid temperature distribution, and transfers more heat from the hot regions (bottom and center of the reactor core) to cold regions (top and periphery of the reactor core). Although the natural circulation in the reactor core is so weak that it is neglected during the DLOFC, the decay heat is removed passively by conduction without any violation of the temperature limits for the 20MWth U-Battery. The comparisons of the cylindrical and annular reactor core configurations show that the latter is a better design with a lower maximum core temperature during the LOFC because of the central graphite reflector. Moreover, it is possible to adopt the current reactor configuration when the thermal power of the U-Battery increases from 20MWth to 40MWth.