A new requirement has motivated the development of smaller reactors since the 1980s. Integral type reactors have been highlighted as a promising option. SMART, which is an integral type reactor has been developed at KAERI, and TASS/SMR code was developed to analyze the thermal hydraulic phenomena of the SMART plant. The main purpose of the code is to simulate all relevant phenomena, processes, and conditions inside the reactor coolant system that may occur during such accidents. Development and assessment of the code is represented in detail. By means of the assessment results using experimental data, TASS/SMR code can be used for both the experiment simulation as well as the SMART analysis. The code predicts thermal hydraulic phenomena for the representative accidents for SMART reasonably.
The general trend of the nuclear market has been toward larger unit sizes. However, a new requirement has motivated the development of smaller reactors since the 1980s. Integral type reactors have been highlighted as a promising option (Modro et al., 2002 and OECD NEA, 2011). For this purpose, the design of a 330 MWt integral reactor, SMART (system-integrated modular advanced reactor) plant, has been developed at the Korea Atomic Energy Research Institute (KAERI) (Kim, 2010). SMART adopts a design concept containing most of the reactor coolant system (RCS) components, such as a core, reactor coolant pumps (RCPs), steam generators (SGs), and a pressurizer in a reactor pressure vessel. Also, it is a small-sized advanced integral-type pressurized water reactor with several enhanced safety features, for examples, a passive residual heat removal system (PRHRS) and an external reactor vessel cooling (ERVC). The existing proven technologies are basically adopted for the SMART design. However, SMART also adopts various innovative design features and technologies that need to be proven through experiments and analyses.
For the simulation of a design based transient and accident in an integral type nuclear power plant, it is necessary to develop a system thermal hydraulic analysis code for SMART. A thermal hydraulic analysis code, TASS/SMR, including a helical steam generator heat transfer and condensate heat exchanger models, has been developed to simulate thermal hydraulic phenomena of SMART (Chung et al., 2003). TASS/SMR code can analyze the thermal hydraulic phenomena of SMART under a full range of reactor operating and accident conditions. The basic code structure adopts a one-dimensional geometry. A node and flow-path network models the system responses. The thermal–hydraulic model is formulated with four one-dimensional conservation variables. The application scope of the code covers the analysis of operational transients, design based accidents and accidents involving partial beyond design based accidents for the SMART plant.
This paper presents an overview of TASS/SMR code development and preliminary assessment, mainly focusing on the thermal hydraulic models, a numerical solution, and validation results. Then, three types of basic transient conditions including loss of reactor coolant flow accident, steam line break accident, and feedwater line break accident are analyzed for SMART.
The thermal hydraulic analysis code, TASS/SMR, was developed for conservative simulation of a transient and accident in the integral type nuclear reactor, SMART. The code adopted a one-step implicit numerical method for application.
The validation of TASS/SMR code was performed using the SMART specific SET and IET facility, as well as the international open data like the Bennett experiment. It was shown that the code was predicted conservatively compared with the experimental results.
Also, generic applications, such as the loss of coolant flow accident, were done for the integral reactor, SMART. The results showed that the TASS/SMR code predicted reasonably for representative design based accidents. TASS/SMR code can be used for both the experiment simulation and the analysis of the integral type reactor, SMART.
