1.  Field of the Invention
The present invention relates to fluid monitoring devices.  More specifically, the present invention relates to devices for monitoring the temperature and flow rate of a flowing fluid. 
2.  Discussion of Background
A number of devices exist to measure fluid flow rates.  Some of these are venturi tubes, tubes that have a narrowed or restricted portion where the flow increases in accordance with Bernoulli's Law and where the pressure can be compared to that at the unrestricted portions of the tubes.  Some devices have so-called venturi center bodies.  A venturi center body is a device in a tube that, by blocking part of the tube, reduces or constricts the flow area and thus creates a pressure drop much as with the usual venturi tube. 
As examples of venturi center bodies, see the devices disclosed in U.S. Pat.  Nos.  4,644,800 issued to Kozlak, 1,829,703 issued to Larner and 1,126,275 issued to Rice.  The Kozlak device also includes a thermocouple for measuring the temperature of the fluid in addition to the flow rate. 
In nuclear reactors, the flow rate and temperature of the reactor coolant are important physical parameters.  Flow rates and temperatures are related to efficiency and nuclear safety.  It is therefore important to monitor the flow rate and temperature of each coolant passage in a reactor core.  Since dimensions and tolerances within a nuclear reactor are crucial, flow rate and temperature monitoring devices must be compact and efficiently designed.  Also, since the environment of use in a reactor is fairly hostile, characterized by high temperatures and high radioactivity levels, the flow meters must be both rugged and easily replaceable. 
There is thus a need for devices that accurately and continuously measure flow rates and temperatures in coolant channels in nuclear reactors and are designed for that specific environment and conditions of use.