Electronic calorimetric computer calculates nuclear reactor thermal power output to a nominal accuracy of 1 percent. Heat balance is determined by an electronic approach. The thermal power is calculated using the inlet and outlet temperatures and the volume of cooling water and is displayed by a digital readout system

Heckelman, J. D.

English

NASA Technical Reports Server

Isolated 
Power 
Supply
—30 V dc I	 I Platinum	 Platinum 
Power	 Resistance	 Resistance 
Supply	 Temperature	 Temperature 
4	 Sensor	 I I	 Sensor 
+ 30 V dc 
Power 
Supply 
April 1968	 Brief 68-10138 
NASA TECH BRIEF 
NASA Tech Briefs are issued to summarize specific innovations derived from the U.S. space program, 
to encourage their commercial application. Copies are available to the public at 15 cents each 
from the Clearinghouse for Federal Scientific and Technical Information, Springfield, Virginia 22151. 
Electronic Calorimetric Computer 
Damping 
Capacitor and 
Switch 
XP Pressure 
	 Amplifier ______________ Square Root 
Transducer	 I	 Circuit
Multiplying	 Oto lOOmv I 	 I p-I
	
Readout ut
 Instrument 
117 V ac Power 
A calorimetric computer has been designed to cal-
culate nuclear reactor thermal power output to a 
nominal accuracy of 1%. A heat balance is determined 
by an electronic rather than an electromechanical 
approach. The thermal power is calculated using the 
inlet and outlet temperatures and the volume of cool-
ing water. This power or, selectively, any of the com-
ponent function values, can be displayed by a digital 
readout system. 
In operation, two similar channels operate from a 
common +30 vdc and —30 vdc power source. Each 
channel uses three sensors to gather data: a differ-
ential pressure (AP) transducer whose voltage output 
is a function of coolant flow, and two platinum tem-
perature sensitive resistors that measure the system 
differential temperature (ST). The thermal power is 
proportional to flow times AT. 
A highly regulated dc voltage is applied to the 
AP transducer whose output of approximately 0 to 25
m y
 is raised to 0 to 10 v by the amplifier whose gain 
is varied to span the channel. Damping in the coolant 
flow circuit is by a capacitor in the feedback loop 
of the amplifier. Output of the amplifier is fed to the 
square root circuit whose 0 to 10 v output is propor-
tional to coolant flow. Flow = where K is a 
constant determined by circuit values and now tube 
characteristics. The square root circuit consists of an 
operational amplifier with a special nonlinear resistor, 
having a parabolic e vs i characteristic, in its feed-
back circuit. This resistor is mounted in an oven 
operated at constant temperature to maintain an ac-
curacy of 0.2%. 
The multiplying circuit is a bridge that provides 
the product of a voltage proportional to coolant now 
and a differential resistance proportional to differen-
tial temperature, the resultant product being a voltage 
proportional to reactor thermal power. The platinum 
temperature sensitive resistors, sensing core inlet and 
(continued overleaf( 
This document was prepared under the sponsorship of the National 
Aeronautics and Space Administration. Neither the United States 
Government nor any person acting on behalf of the United States
Government assumes any liability resulting from the use of the 
information contained in this document, or warrants that such use 
will be free from privately owned rights.
https://ntrs.nasa.gov/search.jsp?R=19680000138 2020-03-12T05:29:05+00:00Z
core outlet temperatures, form two legs of the bridge, 	 Patent status-., 
whose excitation voltage is the output of the square 	 No patent action is contemplated by NASA. 
root circuit.	 Source: James D. Heckelman 
Notes:	 (LEW-90254) 
1. With modification, this computer could be used to 
monitor or control either or both flow systems of 
heat exchangers in industrial applications. 
2. Inquiries concerning this innovation may be di-
rected to:
Technology Utilization Officer 
Lewis Research Center  
2 1000 Brookpark Road 
Cleveland, Ohio 44135 
Reference: B68-10138 
Brief 6810138
	 Category 01


Electronic calorimetric computer

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