[ RadSafe ] Beta emitters and external risks

[H. Westenbrink]

John,

For exemple :32P counting on the surface gives 100 microSv/h, then at 
40 inches
the rate is less then 1 microSv/uur. At 280 inches it will be zero

met vriendelijke groet,
Henk Westenbrink
h.westenbrink at amc.nl # 020-56 65752
toezichthoudend stralingsdeskundige
Centraal B-laboratorium (F1-149)
AMC  Amsterdam

----- Original Message -----
From: John Jacobus <crispy_bird at yahoo.com>
Date: Wednesday, October 19, 2005 10:56 pm
Subject: RE: [ RadSafe ] Beta emitters and external risks

> Elisa,
> However, what if the radionuclide is at some distance
> from the person and not on the skin?  Beta emissions
> of 100 keV can penetrate about 6 inches of air, while
> maximum P-32 beta particles can penetrate about 280
> inches of air.  It would appear that P-32 betas would
> have more than enough energy to penetrate air and
> still deposit a dose.  
> 
> How far away from the Kr-85 source were beta burns
> observed?  What was the activity? My estimate is the
> the 700 keV beta particles of unshielded Kr-85 is 70
> inches in air.
> 
> --- Elsa nimmo <Elsa.nimmo at varian.com> wrote:
> 
> > 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
> > _______________________________________________
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> 
> 
> +++++++++++++++++++
> 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
> 
> 
> 	
>        	
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