Radioactive krypton adsorption technique is used to determine the surface area of more than one sample of material simultaneously

Roesmer, J.

Roll, J. A.

Rymer, G. T.

Sunday, J.

English

NASA Technical Reports Server

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December 1966	 Brief 66-10710 
ICY C
AEC-NASA TECH BRIEF 
rES
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. 
Radioactive Method Enables Determination of Surface Areas

Rapidly and Accurately 
Heating Jacket 
The problem: 
Reaction rates of processes such as oxidation and 
sublimation are dependent on the exposed surface 
areas available as sites for reaction. The common 
laboratory methods of determining the surface areas 
of materials are time consuming since only one 
sample can be tested per setup and each setup requires 
calibration. When surface areas of many samples of
materials such as graphite, ceramics, and metals have 
to be determined on a daily basis, a more rapid and 
accurate process is required. 
The solution: 
A technique which utilizes the adsorption of radio-
active krypton (95% krypton-5% Kr 85). Measurement 
of the activity of Kr85
 in counts per minute is di-
rectly related to the sample surface area.
- Allk 	(Continued overlenf( 
This document was prepared under the sponsorship of the Atomic 	 liability resulting from the use of the information contained in this 
Energy Commission and/or the National Aeronautics and Space document, or warrants that the use of any information, apparatus, 
Administration. Neither the United States Government nor a.y per- 	 method, or process disclosed in this document may not infringe pri-
son acting on behalf of the United States Government assumes any vately owned rights.
https://ntrs.nasa.gov/search.jsp?R=19660000708 2020-03-11T17:43:07+00:00Z
How it's done: 
In the apparatus shown, six sample area determina-
tions can be made simultaneously. The sample is 
heated to 3001 F and evacuated to a pressure of 10 
mm of mercury. The heating is continued for one half 
hour. The sample is then cooled to room tempera-
ture and then to liquid nitrogen temperature by plac-
ing a dewar of N 2 around the sample flask. The 
radioactive krypton is admitted to the samples to 
a pressure of about 1 mm of Hg. This pressure is main-
tained as adsorption continues by diminishing the sys-
tem volume through the admission of mercury from 
the mercury reservoir. 
When adsorption equilibrium has been established, 
as indicated by constancy of the pressure measure-
ments, each sample is removed and scanned using a 
sodium iodide scintillation counter to determine the 
number of counts per minute. The number of Kr85 
counts per minute is related to the sample surface area 
by a predetermined proportionality constant. Using 
this procedure and apparatus, 12 surface area de-
terminations can be made per 8 hours. This can be in-
creased by increasing the number of sample con-
tainers.
Note: 
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: B66-10710 
Patent status: 
No patent action is contemplated by AEC or 
NASA.
Source: J. A. Roll, G. T. Rymer, 
J. Roesmer, and J. Sunday
of Westinghouse Astronuclear Laboratory
under contract to
AEC—NASA Space Nuclear Propulsion Office 
(NU-0088) 
Brief 66-10710	 Category 03


Radioactive method enables determination of surface areas rapidly and accurately

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