Novel modular natural circulation BWR design and safety evaluation

Abstract

Long fuel cycle design Double passive safety system Design basis accident analysis RELAP5 simulation a b s t r a c tThe Purdue NMR (Novel Modular Reactor) represents a BWR-type small modular reactor with a significantly reduced reactor pressure vessel (RPV) height. Specifically, it has one third the height of a conventional BWR RPV with an electrical output of 50 MWe. The preliminary design of the NMR-50 including reactor, fuel cycle, and safety systems is described and discussed. The improved neutronics design of the NMR-50 extends the fuel cycle length up to 10 years. The NMR-50 is designed with double passive engineering safety system, which is intended to withstand a prolonged station black out with loss of ultimate heat sink accident such as experienced at Fukushima. In order to evaluate the safety features of the NMR-50, two representative design basis accidents, i.e. main steam line break (MSLB) and bottom drain line break (BDLB), are simulated by using the best-estimate thermal-hydraulic code RELAP5. The RPV water inventory, containment pressure, and the performance of engineering safety systems are investigated for about 33 h after the initiation of the accidents.

Experimental investigation of natural circulation instability in a BWR-type small modular reactor

“…The preliminary conceptual design of the NMR-50 is developed at Purdue Thermal Hydraulic and Reactor Safety Laboratory (TRSL) (Ishii et al, 2013;Ishii et al, 2015). Selected design parameters of the RPV are shown in Fig.…”

“…Some SMR designs, such as the Mitsubishi's Integral Modular Reactor (IMR) (Hibi et al, 2004), the Purdue University's Novel Modular Reactor (NMR) (Ishii et al, 2015), and the NuScale Power Reactor (Ingersoll, 2009) etc., have simplified the reactor system and integrated the passive safety systems by removing the primary coolant pumps. These SMRs are designed to operate and manage Design Basis Accidents (DBAs) under natural circulation cooling instead of traditional forced circulation cooling.…”

Startup instability in natural circulation driven nuclear reactors

“…Therefore, the length ratio of the NMR test facility to the NMR-50 was 1/1.2 after considering the ceiling height. The total height of the test facility was about 7 m, which was very close to that of the prototypic design of the NMR-50 reactor [2]. Due to the limitation of the lab space, the area ratio between the model and the prototype was close to 1/1000.…”

“…Since 1980s, GE also developed advanced boiling water reactor (ABWR), simplified boiling water reactor (SBWR), and economic simplified boiling water reactor (ESBWR). Apart from the conventional BWRs, some small modular reactors (SMRs) are also in fast development by taking advantage of mature boiling water technology, such as the Mitsubishi's integrated modular water reactor (IMR) with a thermal output of 1000 MW [1], and Purdue's novel modular reactor (NMR-50) with a thermal output of 165 MW [2]. The design of reactors mentioned above except for the BWRs/1~6 eliminate the recirculation loops and pumps by utilizing natural circulation to provide the driving force, which is induced by the density difference between the hot leg and cold leg.…”

Modeling of flashing-induced flow instabilities for a natural circulation driven novel modular reactor

“…A recent research has been performed to investigate the flow instability in a Novel Modular Reactor (NMR) design for low power and low pressure conditions. The NMR developed at Purdue University is a BWR-type small modular reactor design, which relies on natural circulation to provide driving force for both normal operations and accidental management [10][11][12]. In previous research, a natural circulation test facility was scaled and designed from the NMR by using the three-level scaling method.…”