RE: Helicopter IBIS and Sr-90 sources

["Rick Orthen" <rorthen@cecinc.com>]

The IBIS is manufactured by, and registered to, General Nucleonics, Inc.

(Pomona, CA) under California Registration No. CA321D103G (see

http://www.hsrd.ornl.gov/nrc/sources/pdf/03210103.pdf).  The registered

limit is 500 microcuries Sr-90.



 



DEVICE TYPE: Helicopter Blade Failure Detection Gauge



 



DESCRIPTION:  The device consists of a cylindrical housing typically 5.1"

long and 2.75" diameter which contains a bellows, a system of radial detents

for the bellows assembly and an axial rod which houses the activity in the

form of an Isotope Products Laboratory or Amersham Model GNI 12205 Annular

Beta source. The distal end of the axial rod terminates in a coaxial disc

and the proximal end terminates in a connector attached to the bellows. The

distal end of the housing terminates in a steel reset button. The proximal

end of the housing terminates in a base which attaches to the port of a

helicopter rotor blade and exposes the proximal end of the housing to the

pressurized center of the rotor blade. The interior of the bellows is sealed

and maintained at a reference pressure. The bellows is spring loaded against

the detents. In operation, the bellows is held compressed against the

detents by the differential between the blade pressure and reference

pressure. When the bellows is compressed the source rod is in a retracted

position and is shielded by the housing. If blade pressure fails, the

reference pressure in the bellows is no longer sufficient to hold the

bellows against the spring. The spring acts to release the detents and the

source rod is moved towards the distal end, exposing the source outside the

shield. In this position, a Geiger-Mueller Detector mounted inside the upper

fuselage senses the increased radiation field and signals a pressure failure

to the cockpit display. In all detectors (GNI Model 122XX-1) a 0.01

microcurie Strontium-90 source is incorporated to provide a bias signal for

fail safe



operation.



 



 



Richard F. Orthen, CHMM



Senior Project Manager



Civil & Environmental Consultants, Inc.



Four Triangle Lane, Suite 200



Export, PA  15632-9255



724/327-5200, ext. 231



www.cecinc.com <http://www.cecinc.com/>