Capsule containing samples for radiation testing is guided under through a seal to an exact position within a nuclear reactor. A Linear Variable Differential Transformer /LVDT/ flexplate deflection circuit monitors the force on the capsule as it is positioned within the reactor

Roller, R.

Yaroshuk, N.

English

NASA Technical Reports Server

May 1968
	 Brief 68-10147 
.. 
AEC-NASA TECH BRIEF H 
AEC-NASA Tech Briefs describe innovations resulting from the research and development program 
of the U.S. AEC or from AEC-NASA interagency efforts. They are issued to encourage commercial 
application. Tech Briefs are published by NASA and may be purchased, at 15 cents each, from 
the Clearinghouse for Federal Scientific and Technical Information, Springfield, Virginia 22151. 
Deflection Circuit Monitors Force on Object under Water 
Capsule 
Test Capsule\	 ,_(Mounting i Frame 
1 —Mil Deflection 
Per 200 Lb Force 
Variable Demodulator 
Differential	 Unit 
Charger 
Mounted 
Flexplate 
The problem: 
In nuclear component radiation testing, a capsule 
containing samples for radiation must be guided 
under water through a seal to an exact position within 
the reactor. When the capsule is under water, it is out 
of sight and, consequently, any guidance error result-
ing in binding of the capsule in the seal, or contact 
with any body must be detected before the thin walled 
capsule is damaged. Therefore is it necessary to moni-
'tor the force on the capsule as it is being positioned 
within the reactor and provide an alarm or stop the 
positioning system if the forces increase above a 
predetermined amount. 
The solution: 
A linear variable differential transformer (LVDT) 
flexplate deflection circuit that monitors the force 
on the capsule as it is positioned within the reactor.
To 
	
k.000 Lb rci 
1_•,	 Charger- 
________ meter 
Trigger	 fT1	 I—.1 
How it's done: 
The capsule containing the samples is mounted on a 
frame which deflects when the capsule contacts any 
object or unusual force while it is being positioned. 
The force on the capsule is relayed to a flexplate 
mounted on the capsule positioning device. A force of 
200 lb on the capsule produces a deflection of I mil 
on the flexplate. A linear variable differential trans-
former, with its associated demodulator, detects the 
flexplate deflection and puts out a signal proportional 
to it. A variable-voltage Schmitt trigger unit is set to 
trip when the deflection is at the maximum desired 
level. 
The Schmitt trigger unit is set for a 12,000-pound 
shutoff. Thus, whenever the capsule encounters any 
deflecting force during positioning that is equal to
12,000 pounds, the Schmitt trigger activates a relay 
(continued overleaf) 
This document was prepared under the sponsorship of the Atomic 
Energy Commission and/or the National Aeronautics and Space 
Administration. Neither the United States Government nor any per-
son 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 the use of any information, apparatus, 
method, or process disclosed in this document may not infringe pri-
vately owned rights.
https://ntrs.nasa.gov/search.jsp?R=19680000147 2020-03-12T05:28:22+00:00Z
drive that is connected to the capsule charger motor. 
The relay shuts off the charger motor until the cause 
of the deflecting force can be determined. 
Use of this deflection circuit prevents damage to 
reactor parts or to the capsule and its contents while 
the capsule is being inserted through 'the seal near the 
reactor for testing. 
Notes: 
1. This technique is not limited to underwater use, 
and possible areas of application include off-shore 
oil rigs, mining, and heavy industry. 
2. Inquiries concerning this innovation may be di-
rected to:
Technology Utilization Officer 
AEC-NASA Space Nuclear 
Propulsion Office 
U.S. Atomic Energy Commission 
Washington, D.C. 20545 
Reference: B68-10147
Patent status: 
No patent action is contemplated by AEC or 
NASA.
Source: R. Roller and N. Yaroshuk

of the Westinghouse Astronuclear Laboratory

under contract to

AEC-NASA Space Nuclear Propulsion Office

(NUC- 10147) 
Brief 68-10147	 Categdry 01


Deflection circuit monitors force on object under water

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