The Plant Feature and Performance of Double MS (Modular Simplified and Medium Small Reactor)

A new concept of a small and medium sized light water reactor, named the double MS: modular simplified and medium small reactor (DMS) was developed. The main features of the DMS relative to overcoming the scale demerit are the miniaturization and simplification of systems and equipment, integrated modulation of construction, standardization of equipment layouts, and effective use of proven technology. The decrease in the primary containment vessel (PCV) height is achieved by reducing the active fuel length of the DMS core, which is about 2 m compared with 3.7 m in the conventional boiling water reactor (BWR). The short active fuel length reduces the drop in core pressure and overcomes the natural circulation system. By using the lower steam velocity in the upper plenum in the reactor pressure vessel (RPV), we can adopt a free surface separation (FSS) system. The FSS eliminates the need for a separator and thus helps minimize the RPV and PCV sizes. In order to confirm transient performance, the DMS plant performance under transient conditions was evaluated using the TRACG code. TRACG code, which can treat multidimensional hydrodynamic calculations in a RPV, is well suited for evaluating the DMS reactor transient performance because it can evaluate the void fraction in the chimney and therefore evaluate the natural circulation flow. As a result, the maximum change in the minimum critical power ratio of the DMS was 0.14, almost the same as for the current advanced boiling water reactor (ABWRs). In order to improve safety efficiency, developing an emergency core cooling system (ECCS) for the DMS was considered. The ECCS configuration in the DMS was examined to achieve core coverage and economic efficiency from the following: (1) eliminating high-pressure injection systems, (2) adopting passive safety-related systems, and (3) optimizing distribution for the systems and power source for the ECCS. In this way, the configuration of the ECCS for the DMS was established, providing the same level of safety as the ABWR and the passive systems. Based on the results of the loss of coolant accident analysis, we confirmed that the core can be covered by this configuration. Therefore, the plant concept was found to offer both economic efficiency and safety.

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Steam drum level dynamics in a multiple loop natural circulation system of a pressure-tube type boiling water reactor

Annals of Nuclear Energy ◽

10.1016/j.anucene.2011.06.007 ◽

2011 ◽

Vol 38 (10) ◽

pp. 2227-2237 ◽

Cited By ~ 2

Author(s):

Vikas Jain ◽

P.P. Kulkarni ◽

A.K. Nayak ◽

P.K. Vijayan ◽

D. Saha ◽

...

Keyword(s):

Natural Circulation ◽

Boiling Water ◽

Pressure Tube ◽

Circulation System ◽

Boiling Water Reactor ◽

Water Reactor ◽

Tube Type ◽

Steam Drum

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Description of Typical Flow Instabilities in the Natural Circulation System

10th International Conference on Nuclear Engineering, Volume 3 ◽

10.1115/icone10-22037 ◽

2002 ◽

Author(s):

Shengyao Jiang ◽

Xingtuan Yang ◽

Youjie Zhang

Keyword(s):

Natural Circulation ◽

Great Influence ◽

Operating Conditions ◽

Boiling Water ◽

Flow Instabilities ◽

Circulation System ◽

Boiling Water Reactor ◽

Primary Loop ◽

Water Reactor ◽

Test Loop

The experiments were performed on the test loop HRTL-5, which simulates geometry and system design of the 5-MW Nuclear Heating Reactor developed by the Institute of Nuclear Energy Technology, Tsinghua University. Because of the difference of the geometry design and operating conditions between the heating reactor and the boiling water reactor, the flow behavior presents great differences too, some of which haven’t been deeply studied so far. Results show that in heating reactor, sub-cooled boiling, condensation and flashing play an important role on the flow instabilities of the natural circulation system. Correspondingly, geysering instability, flashing instability, and flow excursion are the very typical instabilities occurring in the primary loop of HRTL-5, which are different from those in boiling water reactor conditions. The compressibility of the steam space on the top of the primary loop has also great influence on the instability of the natural circulation system.

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The Plant Feature and Performance of DMS (Double MS: Modular Simplified and Medium Small Reactor)

Volume 4: Structural Integrity; Next Generation Systems; Safety and Security; Low Level Waste Management and Decommissioning; Near Term Deployment: Plant Designs, Licensing, Construction, Workforce and Public Acceptance ◽

10.1115/icone16-48949 ◽

2008 ◽

Cited By ~ 1

Author(s):

Yukiko Kawabata ◽

Masayoshi Matsuura ◽

Shizuka Hirako ◽

Takashi Hoshi

Keyword(s):

Economic Efficiency ◽

Cooling System ◽

Natural Circulation ◽

Circulation System ◽

Surface Separation ◽

Power Company ◽

Loss Of Coolant Accident ◽

Core Cover ◽

And Performance ◽

Core Cooling

The Japan Atomic Power Company has initiative in developing the DMS concept as a 400MWe-class light water reactor. The main features of the DMS relative to overcoming the scale demerit are the miniaturization and simplification of systems and equipment, integrated modulation of construction, standardization of equipment layouts and effective use of proven technology. The decrease in primary containment vessel (PCV) height is achieved by reducing the active fuel length of the DMS core, which is about two meters compared with 3.7 meters in the conventional BWR. The short active fuel length reduces the drop in core pressure, and overcomes the natural circulation system. And by using the lower steam velocity in the upper plenum in the reactor pressure vessel (RPV), we can adopt a free surface separation (FSS) system. The FSS eliminates the need for a separator and thus helps minimize the RPV and PCV sizes. In order to improve safety efficiency, developing an Emergency Core Cooling System (ECCS) for the DMS was considered. The ECCS configuration in the DMS was examined to achieve core coverage and economic efficiency from the following. 1: Eliminating high-pressure injection systems. 2: Adopting passive safety-related systems. 3: Optimizing distribution for the systems and power source for the ECCS. In this way the configuration of the ECCS for the DMS was established, providing the same level of safety as the ABWR and the passive systems. Based on the results of Loss of Coolant Accident (LOCA) analysis, core cover can be achieved by this configuration. Therefore, the plant concept was found to offer both economic efficiency and safety.

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Safety Features of Advanced and Economic Simplified Boiling Water Reactors

Indonesian Journal of Physics and Nuclear Applications ◽

10.24246/ijpna.v3i1.1-6 ◽

2018 ◽

Vol 3 (1) ◽

pp. 1-6

Author(s):

Ren-Tai Chiang

Keyword(s):

Flow Line ◽

Natural Circulation ◽

Stability Boundary ◽

Boiling Water ◽

Circulation System ◽

Boiling Water Reactor ◽

Circulation Flow ◽

Large Margin ◽

Water Reactor ◽

Safety Features

The Advanced Boiling Water Reactor (ABWR) and the Economic Simplified Boiling Water Reactor (ESBWR) are two kinds of contemporary, advanced, commercially available nuclear power reactors. Reactor internal pumps in an ABWR improve performance while eliminating the large recirculation pumps in earlier BWRs. The utilization of natural circulation and passive safety systems in the ESBWR design simplifies nuclear reactor system designs, reduces cost, and provides a reliable stability solution for inherently safe operation. The conceptually reliable stability solution for inherently safe ESBWR operation is developed by establishing a sufficiently high natural circulation flow line, which has a core flow margin at least 5% higher than the stability boundary flow at 100% rated power of a conventional BWR, and then by designing a high flow natural circulation system to achieve this high natural circulation flow line. The performance analyses for the ESBWR Emergency Core Cooling System (ECCS) show that: (1) the core remains covered with a large margin and there is no core heat up in the ESBWR for any break size, (2) the long-term containment pressure increases gradually with time, in the order of hours, and the peak pressure is below the design value with a large margin, and (3) the margins depend on the containment volumes and water inventories. These safety design features ensure inherently safe ESBWR operation. Enhanced safety features based on lessons learned from the Fukushima nuclear accident are added in ABWR’s and ESBWR’s safety designs. The major enhancements are the further prevention of station blackout and loss of ultimate heat sink.

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The Startup of the Dodewaard Natural Circulation Boiling Water Reactor—Experiences

Nuclear Technology ◽

10.13182/nt107-93 ◽

1994 ◽

Vol 107 (1) ◽

pp. 93-102 ◽

Cited By ~ 3

Author(s):

Wim H. M. Nissen ◽

Jaap Van Der Voet ◽

Jadranko Karuza

Keyword(s):

Natural Circulation ◽

Boiling Water ◽

Boiling Water Reactor ◽

Water Reactor

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Recapturing Net Positive Suction Head Margins in Boiling Water Reactor Emergency Core Cooling Systems

Volume 7: Operations, Applications and Components ◽

10.1115/pvp2017-66141 ◽

2017 ◽

Author(s):

Alan J. Bilanin ◽

Andrew E. Kaufman ◽

Warren J. Bilanin

Keyword(s):

Cooling System ◽

Cooling Water ◽

Boiling Water ◽

Boiling Water Reactor ◽

Cooling Systems ◽

Water Reactor ◽

Loss Of Coolant Accident ◽

Loss Of Coolant ◽

Core Cooling ◽

Reactor Pressure

Boiling Water Reactor pressure suppression pools have stringent housekeeping requirements, as well as restrictions on amounts and types of insulation and debris that can be present in the containment, to guarantee that suction strainers that allow cooling water to be supplied to the reactor during a Loss of Coolant Accident remain operational. By introducing “good debris” into the cooling water, many of these requirements/restrictions can be relaxed without sacrificing operational readiness of the cooling system.

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