Re: Natural Thorium-Lantern Mantles

[Jack Couch <jgcouc@planetx.bloomu.edu>]

            Earlier, Theresa L Aldridge wrote:
>          I am preparing the proposal for my thesis, "Substitution Of 
>          Natural Thorium In Consumer Products And Resulting Dose 
>          Consequences To The Public".
>     
>          I would like to survey radcon/HP folks to obtain current 
>          information and/or leads, relative to:  the different kinds 
>          of consumer products being used, and more importantly... any 
>          "substitution products or materials" being used to replace 
>          natural Thorium.
>     
>          Theresa_L_Aldridge@Rl.Gov
>          (509)376-5865
>
To Theresa and others who may be interested, Coleman recently 
switched from thorium-based to yttrium-based mantles (marketed
now as Gold Top). Coleman claims that, not only are the new mantles 
non-radioactive, they are structurally stronger (although maybe not as
bright).  
Worldwide, nearly all versions of the incandescent mantles used in 
lanterns still use thorium as the primary ingredient. Thorium-based 
mantles under other brand names can still be purchased at Sear and 
Target stores and at some surplus stores. 

According to Randy May at the Coleman company, their thorium mantles 
contained 300 mg Th-232 corresponding to about 1.2 kBq (33 nCi). A 
quick calculation shows that the dose over 50 y to bone surface tissue 
would be about 24 mSv (2.4 rem) for a mantle if injested. 

The Coleman Company (Wichita, KS) used to distribute a pamphlet 
called "Mantles by the Million."  Call their customer service department 
and ask for either Carolyn Britton or Randy May.  If you are especially 
charming and persuasive, I'm sure they will provide you with a copy of 
the pamphlet plus answer questions about mantles that should be 
useful in writing your thesis.

Gamma spectra of mantles and some dose information have been 
published in the following articles:

H. Mohammadi and S. Mehdizadeh, "Re-identification of Th-232 content 
and relative radioactivity measurements in a number of imported gas mantles,"
Health Phys. 44 (6), 649-653 (1983).

Rudolf J. N. Brits, "Measurement of the Th-232 content of gas mantles,"
Health Phys. 48 (1), 124 (1985).

Jack G. Couch and Kelly L. Vaughn, "Radioactive Consumer Products 
in the Classroom," The Physics Teacher, 33, pp.18-22 (Jan.1995).

Theresa, the third article contains material from Kelly's senior project. It 
includes information and gamma spectra for mantles (Th-232 and progeny), 
Fiestaware dishes (both U-235 and U-238 are identified from the U3O8 
in the orange glaze) and NOSALT (K-40). 

Good luck with your project!  Jack
Jack Couch
Bloomsburg University
jgcouc@planetx.bloomu.edu
"Never assume the obvious is true"
William Safire, in -Sleeper Spy-