[ RadSafe ] Tritium contamination

Tue Nov 1 17:08:10 CDT 2011

In Europe it is free release at 1E4kBq/kg Euratom 96/29 Basic Safety Standards Directive Art 3 Annex TableA  or a total quantity of 1E6 Bq. This is ridiculously high. Tritium affects larval development of invertebrates at very low activity levels. It also dissolves in metals, which is why the nuclear idustry wanted the Euratom transposition. 
Chris Busby

-----Original Message-----
From: radsafe-bounces at agni.phys.iit.edu on behalf of Harry Reynolds
Sent: Tue 01/11/2011 20:56
To: The International Radiation Protection (Health Physics) Mailing  List; Jerry Cohen
Subject: Re: [ RadSafe ] Tritium contamination

I would be interested in what free release limits are applied to tritium contamination in countries other than the US. 

BTW Franz, the limits in the US are not uniform between agencies and states.

Harry

-----Original Message-----
From: radsafe-bounces at health.phys.iit.edu [mailto:radsafe-bounces at health.phys.iit.edu] On Behalf Of franz.schoenhofer at chello.at
Sent: Tuesday, November 01, 2011 2:50 PM
To: Jerry Cohen; The International Radiation Protection (Health Physics) MailingList
Subject: Re: [ RadSafe ] Tritium contamination

Jerry et al., 

Probably the concern is, what maximum permisible contaminant levels are prescribed by authorities - whether they make sense or not, they have to be fulfilled. Your comment, Jerry, is fully justified, but does not help when it comes to legislation. 

I am somewhat surprised that Martin (hej!) asks RADSAFE for advice since he is dealing with a Swedish problem. I would be very surprised if limits and legislation in Sweden would be the same as in the USA. I know to well that US persons tend to assume that their national legislation is applicable and valid all over the world, which it is clearly not! 

I have  been working in a  group of the Austrian Standardisation  Institute on decontamination of surfaces. The problem in this tritium case is not to the surface. Anyway I refused to support the groups conclusions, because this is such an unbelievable difficult and complex question that it cannot be easily solved by just a few simple tests, even for common radionuclides. To many parameters!!!! We did not even touch the question of tritium.

Best regards,

Franz  

---- Jerry Cohen <jjc105 at yahoo.com> schrieb:
> Based upon any credible exposure scenario, Tritium is simply not a serious 
> health threat.
> So, why the concern?
> 
> 
> 
> 
> ________________________________
> From: Scott Davidson <bsdnuke at gmail.com>
> To: The International Radiation Protection (Health Physics) Mailing List 
> <radsafe at health.phys.iit.edu>
> Sent: Mon, October 31, 2011 8:26:21 AM
> Subject: Re: [ RadSafe ] Tritium contamination
> 
> You seem to be on the right track.  Unless the material is porous or
> has a particular affinity for tritium, then when it is dry, the
> tritium will be gone.
> 
> Porous is on atomic/molecular level where tritium can permeate the
> material.  This would be evident if wipes came up contaminated after
> decontamination (weeping).  This was the classic "re-appearium" that
> occurred on casks that were used in spent fuel pools and can occur
> from many radionuclides.  The NRC has some old guidance on cask
> weeping.
> 
> Materials with an affinity for tritium include some metals that form
> hydrides and things with hydrogen in them.  Some metal hydrides will
> be stable and not release their hydrogen (tritium) readily.  But if
> the tritium concentration is high, some exchange will occur and be
> well fixed.  Likewise for plastics or other polymers that might
> exchgange a hydrogen for tritium.
> 
> There is a lot of information in chapter 5 of DOE Handbook 1129 a
> portion a different section is shown as "19-26" but I am not sure how
> much you want to make this a science project.
> 
> On Mon, Oct 31, 2011 at 11:03 AM, Olsson Mattias :MSO
> <mso at forsmark.vattenfall.se> wrote:
> > Dear Radsafers,
> >
> > I am playing around with a nuclide vector that I hope to be able to
> > apply for free release measurements. The assumption is that the
> > contamination comes from BWR reactor water, and at least Co-60 is
> > measurable with a gamma detector. I want to use Co-60 as a key nuclide
> > to estimate the amount of a whole array of other nuclides by using the
> > known composition of the activity in reactor water.
> >
> > To set this up is not very difficult, and I also add a function to let
> > the nuclide vector "age" for the cases where it is known that the
> > contamination occured some time ago.
> >
> > The thing is that the free release measurements will be done on dry
> > materials. That means that the tritium, which is fairly abundant in the
> > reactor water, will no longer be there during the measurement. I suppose
> > *some* tritium will be retained on the materials, though. Surfaces are
> > somewhat prone to exchange protons in an aqueous environment, if nothing
> > else. Anyway... What I wonder is if there is any experience on here on
> > how much tritium will stay as contamination on a surface if the surface
> > is first splashed with tritiated water and then allowed to dry. I
> > imagine this would depend on a number of factors (type of surface, ratio
> > between available surface and the amount of tritiated water etc) that
> > would make a general statement hopeless, but if there are any practical
> > examples I would love to hear about them! It could lead me towards a
> > conservative reasonable assumption.
> >
> > All the best,
> >
> > Mattias Olsson, Sweden
> > _______________________________________________
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--
Franz Schoenhofer, PhD, MinRat
Habicherg. 31/7
A-1160 Vienna
Austria
mobile: ++43 699 1706 1227

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