Patent Application
20180315512
This invention pertains in general to self-contained power supplies and, more particularly, to such a power supply that is designed to operate in the vicinity of a radiation source
Conventional nuclear reactors require reactor vessel penetrations for the cabling that communicates signals from the in-core instrumentation to the control room. The penetrations are often a source of leakage of reactor coolant over the life of the reactor vessel. Therefore, it has always been an objective to reduce the number of reactor vessel penetrations to the minimum required for safe operation of the nuclear plant. One way to reduce the number of in-core instrumentation penetrations is to transmit the in-core detector signals wirelessly. However, wireless transmission of the detector signals would require a self-sustaining power source within the reactor vessel. It is well understood that conventional power sources such as chemical batteries, thermoelectric generators or vibration energy harvesters that would traditionally provide the voltage and current for such a wireless transmitter, cannot survive the in-core environment of a nuclear reactor.
It is also well known that vacuum micro-electronics (VME) devices can survive the reactor in-core environment, but devices based upon that technology also require a power source located within the interior of the reactor vessel. As schematically illustrated in
This invention achieves the foregoing objective by providing an in-core electronics assembly including a solid state vacuum micro-electronics device. The solid state vacuum micro-electronic device comprises a cathode element; an anode element; a means for establishing a voltage bias between the grid and ground; and a voltage source for establishing a desired voltage bias between the anode element and ground. A housing sealably encloses the cathode, the anode and the grid and a heater is disposed within the housing proximate or as part of the cathode for heating the cathode, wherein the heater comprises fissile material.
In one embodiment, the cathode element is wrapped around the fissile material. In another embodiment, the cathode element extends through the fissile material. Preferably, the dimensions of the fissile material is not larger than 0.1 inch in height and 0.230 inch in diameter. In one such embodiment, the fissile material is uranium dioxide less than 5 w/o.
Preferably, the voltage source is responsive to irradiation within a reactor core to provide the desired voltage and in one such embodiment the voltage source is a self-powered in-core radiation detector. The in-core electronics assembly also includes one or more sensors with signal outputs that are monitored through the grid. Desirably, the in-core electronics assembly includes a wireless transmitter which is powered by the solid state vacuum micro-electronic device. The invention also contemplates a solid state vacuum micro-electronic device comprising some of the foregoing elements.
A further understanding of the invention can be gained from the following description of the preferred embodiments when read in conjunction with the accompanying drawings in which:
The preferred embodiment of this invention comprises a vacuum micro-electronics (VME) device with a fissionable heater element capable of producing the energy necessary to power the vacuum micro-electronics device directly from the thermal energy produced by fissile material, such as U-235.
Another important aspect of this invention deals with powering the anode/plate terminal 16 of the VME. The anode/plate terminal of the VME can be connected to a self-powered detector (SPD) emitter or several SPDs in order to generate the required electrical power needed. Typical SPDs behave like ideal current sources and produce a current proportional to the neutron flux as described in US 2013/0083879. This invention utilizes the SPDs properties to create a potential difference across the VME anode terminal 16.
The VME of this invention can be located in the top nozzle of nuclear fuel assembly such as the top nozzle shown in
While specific embodiments of the invention have been described in detail, it will be appreciated by those skilled in the art that various modifications and alternatives to those details could be developed in light of the overall teachings of the disclosure. Accordingly, the particular embodiments disclosed are meant to be illustrative only and not limiting as to the scope of the invention which is to be given the full breadth of the appended claims and any and all equivalents thereof.
