The Use of a Stirling Engine to Provide Emergency Heat Removal to the Containment Environment of a Nuclear Reactor Building

Abstract

A Stirling engine provides a means to use the thermal energy in the sealed containment environment of a nuclear reactor building to provide emergency cooling. Acting as the prime mover in a coupled heat exchanger system, a Stirling engine could develop fluid flow thereby resulting in forced convection vice natural circulation and would not rely on an external power source during an unusual accident event where no electric power is available.

Claims

1. The claim herein is the novel use of a system that utilizes a Stirling engine to provide the motive driver to a fan to provide forced convection cooling of a hot containment environment which does not rely on an external electrical power source, promotes improved heat transfer over natural convection, and is self-regulated by the thermal conditions in the containment environment.

Description

DETAILED DESCRIPTION

[0011] The invention consists of the use of an air-to-fluid heat exchanger, a fan powered by a Stirling engine, piping containing the secondary fluid, isolation valves for secondary fluid, and a pump power by a Stirling engine.

[0012] The air-to-fluid heat exchanger is envisioned to be a tube-to-fin heat exchanger but other air-to-fluid heat exchanger designs could be adapted for this purpose. The air-to-fluid heat exchanger would be located in the sealed containment environment. Cool liquid from outside containment would flow through the tubed portion of the heat exchanger while the hot containment environment would transfer heat to the finned portion of the heat exchanger. This thermal energy would then be transferred to the tubed portion of the heat exchanger and ultimately transferred to the cool secondary fluid and thus remove the heat from the containment environment.

[0013] In order to promote the flow of air within the containment environment, a Stirling engine connected to a fan would be used. The hot containment environment would provide the hot temperature source to drive the Stirling engine. The secondary fluid could be used as the heat sink for the Stirling engine. Using this difference in temperature to power the Stirling engine, the Stirling engine would be used to drive a fan. This fan would then establish air flow over the finned portion of the heat exchanger. Additionally, using the same temperature difference, a Stirling engine could be connected to a pump to establish flow in the cool secondary loop. The Stirling engine(s) would be located inside the sealed containment environment.

[0014] Piping and isolation valves would be used to conduct the secondary fluid to and from the containment environment. The piping and valves would provide a barrier between the outside environment and the sealed containment environment. While the piping would penetrate the sealed containment, it would not allow the secondary fluid to mix with the containment environment. As such, the containment environment would remain sealed.

[0015] In the normal mode of operation of a nuclear power plant this system would not be in operation. The valves with the secondary fluid would be closed. As such, there would be no heat transfer as all of the components of this system within containment would be at essentially a uniform temperature.

[0016] In the event of a severe emergency where substantial heat is generated in the sealed containment environment, the isolation valves of the secondary fluid would be opened. The secondary fluid would then be permitted to enter the piping. The tube side of the heat exchanger would be connected to this piping. As such, the secondary fluid would then flow through the tubed portion of the heat exchanger. With the secondary fluid flowing in the tubed side of the heat exchanger located in containment a thermal gradient would be developed. The Stirling engine(s) within the sealed containment would then be provided with the energy to circulate air within the containment environment and within the secondary fluid. With this thermal gradient to power the Stirling engines, flow greater than simply natural circulation could be established and remove the energy from the sealed containment environment. It is noted that in addition to the removal of thermal energy by the heat exchanger, by the very nature of the Stirling engine, it too would assist in the removal of this thermal energy by the conversion of heat to work in providing the motive force for the fan and pump. This system would continue to operate until a thermal gradient no longer existed that was sufficient to power the Stirling engines.

DRAWING DESCRIPTION

[0017] FIG. 1 identifies the general layout of the heat removal system which utilizes a fan powered by the Stirling engine to develop forced convection cooling of the hot containment environment.