RE:

[rkathren@tricity.wsu.edu (Ron L. Kathren)]

Instead of a 'contact' reading, which is really largely a function of
detector size and geometry, why not make a measurement at a distance of at
least 5-7 times the diameter of the dial, thus approximateing inverse square
and use the age old formula for Ra-226 to convert to activity.  You may have
to make an intergrating devcice (eg TLD) measurement, but that would just
give the calculation more reliability.

Ron Kathren

At 04:01 PM 9/9/98 -0500, SSORG_IT@nv.doe.gov wrote:
>Franz,
>
>Thanks for your reply.  The exact dial I am searching for information on
>was mounted on a Navy Wind Radar Pedestal.  The Pedestal was placed in
>the salvage yard some years ago, the dial was broken, and subsequently
>contaminated the Pedestal and the trailer it was mounted on.
>
>I am trying to make an estimate of Curie activity so I may ship it....It
>has a contact reading of 2.5 mR/hr.
>
>My first message should have been clearer, but it was the first one I've
>sent !
>
>
>	-----Original Message-----
>	From:	Franz Schoenhofer [SMTP:schoenho@via.at]
>	Sent:	Wednesday, September 09, 1998 1:23 PM
>	To:	Multiple recipients of list
>	Subject:	Re: 
>
>	At 13:51 09.09.1998 -0500, you wrote:
>	>I am interested in the range of  Ra-226 activity present in
>various
>	>switches, dials, and gauges.  Any information on typical Ra-226
>activity
>	>levels in these various article would be appreciated.
>	>
>	>Thanks for the information.
>	>
>	>Email ssorg_it@nv.doe.gov
>	---------------------------------------------------
>
>	In Europe the use of Ra-226 is to my knowledge in (almost) all
>countries
>	not allowed any more for these purposes. Ra-226 can therefore
>only be found
>	in very old devices. It has been replaced for instance in dials
>by Pm147
>	and especially tritium. The trend is even to replace tritium in
>dials by
>	phosphorescent material, which will of course not glow after
>some hours in
>	the dark. Ra-226 in the devices you mentioned is now regarded as
>a
>	curiosity, which is much aftersought by some radiation
>protection experts
>	who are interested in the history of radiation protection,
>including me.
>
>	Best regards,
>
>	Franz
>
>	 
>	Franz Schoenhofer
>	Habicherg. 31/7
>	A-1160 Vienna
>	Austria
>	Tel.: +43-1-495 53 08
>	Fax.: same number
>	mobile phone: +43-664-338 0 333
>	e-mail: schoenho@via.at
>
>	Office:
>	Federal Institute for Food Control and Research
>	Department of Radiochemistry
>	Kinderspitalg. 15
>	A-1095 Vienna
>	Austria
>	Tel.: +43-1-40 491 520
>	Fax.: +43-1-40 491 540
>	e-mail: schoenhofer@baluf.via.at
>	
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