The MASLWR project is being conducted under the auspices of the NERI(.) program of the purpose of the project is to create a reactor plant concept. | PERFORMANCE AND SAFETY STUDIES FOR MULTI- APPLICATION, SMALL, LIGHT WATER REACTOR (MASLWR)1 James E. Fisher, S. Michael Modro, Kevan D. Weaver Idaho National Engineering and Environmental Laboratory Jose Reyes, John Groome Oregon State University Pierre Babka Nexant, Inc. SUMMARY The Multi-Application, Small, Light Water Reactor (MASLWR) is a modular natural circulation design with the reactor core and steam generator contained in a single vessel, located within a cylindrical containment, which is in turn, submerged in a pool of water. The containment itself is partially filled with water, to serve as a blowdown suppression pool and as a source of core makeup liquid. The core is composed of standard PWR assemblies with an active fuel height of approximately 1 m and consists of cylindrical fuel pins containing UO2 or THO2-UO2 pellets, enriched to < 20%. The steam generator is a helical-tube, once-through heat exchanger, consisting of approximately 1000 tubes arranged in an upwardly spiraling pattern. Water heated by the core flows upward through a central riser and is cooled as it flows downward through an annular space that contains the heat exchanger spiral, and returns into the bottom of the core. Cold feedwater enters the steam generator tubes at the bottom and slightly superheated steam is collected at the top. Steady-state characterization studies were conducted to determine operational parameters and demonstrate system stability. Results of these studies show that the system will operate in a stable state at a thermal power level of 150 MW at a pressure of approximately 10 MPa, while supplying steam at MPa (220 psia) superheated by 10 K. Transient safety studies were done for loss-of-coolant accidents within the containment and other accidents. The results defined the required configuration and sizes of the venting, automatic depressurization, and sump makeup lines. Redundant sets of 3-inch upper containment automatic depressurization system (ADS) vent .
