[ RadSafe ] Beta emitters and external risks

[Elsa nimmo]

John,

For external risk & beta-emitters, it seems like one needs to be
concerned with nuclides emitting betas energetic enough to penetrate to
the live layer of skin -- energetic enough to penetrate at least 7
mg/sq-cm.  So pure beta-emitters with an Emax < 70 keV just aren't going
to be of concern as an external radiation source. 

One application I worked with for some years used pressurized Kr-85 in
thin-windowed sealed sources.  The Kr-85 betas emitted by the sources
aren't penetrating enough to damage lens of the eye or anyone's internal
organs, but they can cause skin burns depending on the sealed source
design, Kr-85 content, & the exposure time & distance.

Anyway, for beta emitters with an Emax above something like 70 keV,
seems like you have to assess the situation case by case, considering
possible dose from betas capable of reaching live layer of skin....

Regards,
Elsa Nimmo

 

> >> ----- Original Message ----- 
> >> From: "John Jacobus" <crispy_bird at yahoo.com>
> >> To: "radsafe" <radsafe at radlab.nl>
> >> Sent: Friday, October 14, 2005 4:42 PM
> >> Subject: [ RadSafe ] Beta emitters and external
> > risks
> >>
> >>
> >> > Question:  Would you say that beta emitters
> pose
> > an
> >> > external radiation hazard or risk?  I am not
> > consider
> >> > skin contamination.
> >> >
> >> > Are there any (other) beta emitters that you
> would
> >> > consider to be a significant external hazard?
> >> >
> >> > What is your criteria for this judgement?
> >> >
> >> > (Background:  I would in a medical research
> > facility,
> >> > and we require beta shields for work involving
> > large,
> >> > e.g., 10 mCi/370 MBq, amounts of P-32.  Are
> there
> >> > other beta emitters we should worry about?)
> >> >
> >> > +++++++++++++++++++
> >> > On Oct. 5, 1947, in the first televised White
> > House address, President
> >> > Truman asked Americans to refrain from eating
> meat
> > on Tuesdays and poultry
> >> > on Thursdays to help stockpile grain for
> starving
> > people in Europe.
> >> >
> >> > -- John
> >> > John Jacobus, MS
> >> > Certified Health Physicist
> >> > e-mail:  crispy_bird at yahoo.com