[ RadSafe ] Re: Spent Fuel and Decay - Dangerous for Millions ofYears?

Mon Jul 30 16:24:33 CDT 2007

Out of curiosity, is the fuel used in CANDU reactors
recycled?

--- "Brennan, Mike  (DOH)" <Mike.Brennan at DOH.WA.GOV>
wrote:

> >From the NWMO report:
> 
> "The radiotoxicity analysis for used CANDU fuel
> suggests that this material is a potential internal
> exposure health risk for more than one million years
> (Mehta et al. 1991; AECL 1994).  Similar analysis
> for used pressurized water reactor (PWR) fuel with
> enriched uranium-
> 235 suggests that the radiotoxicity of used fuel
> becomes equal to the equivalent uranium ore
> after about 130,000 years (IAEA 2004). Other
> analysis suggests the time period is between
> 500,000 and one million years (OECD 2004)."
> 
> I am sure I join with everyone on the site to
> encourage people to not eat neither spent fuel,
> regardless of age, nor uranium ore.  I will even go
> so far as to recommend that people not eat ceramic
> of any sort, or ore no matter what toxic metal might
> be refined from it.
> 
> I submit that any set of assumptions that result in
> spent nuclear fuel being as available for
> unintentional ingestion as uranium ore is suspect,
> and needs very strong justification before being
> accepted.   
> 
> -----Original Message-----
> From: radsafe-bounces at radlab.nl
> [mailto:radsafe-bounces at radlab.nl] On Behalf Of Leo
> M. Lowe
> Sent: Monday, July 30, 2007 6:36 AM
> To: radsafe at radlab.nl
> Cc: JGinniver at aol.com
> Subject: [ RadSafe ] Re: Spent Fuel and Decay -
> Dangerous for Millions ofYears?
> 
> Your point about "dangerous" is well taken.  A
> simplistic comparison of total activity or dose
> rates certainly does not give the entire picture of
> the potential hazards of spent fuel.  A more
> complete description is required.
> 
> However, the purpose of my comment about the dose
> rate near spent fuel, which perhaps could have been
> more clearly stated, was to indicate that spent fuel
> would not necessarily be immediately hazardous for
> "millions of years" to anyone exposed.  While it
> would be very radioactive for a long time, the
> direct doses, such as for example might be
> encountered if retrieval were required, could be
> easily handled long before millions of years have
> past.  Note that the dose rate of 0.82 mSv/h from
> one spent fuel bundle after 500 years is with no
> shielding.
> 
> >Message: 6
> >Date: Fri, 27 Jul 2007 17:39:36 +0200
> >From: Peter Bossew <peter.bossew at jrc.it>
> >Subject: Re: [ RadSafe ] Re: Spent Fuel and Decay -
> Dangerous for
> >         Millions        of      Years?
> >To: radsafe at radlab.nl
> >Message-ID: <46AA11B8.7070205 at jrc.it>
> >Content-Type: text/plain; charset=ISO-8859-1;
> format=flowed
> >
> >A useful document (although 10 y old), I find:
> >
> >  http://www.senat.fr/rap/o97-612/o97-612_mono.html
> >
> >A table with inventories can be found in sec. 2.1,
> Le butoir du césium.
> >tMLi = t de métal lourd irradié.
> >
> >What "dangerous" means, is rather a philosophical
> question which can 
> >hardly be solved by scientific reasoning. Comparing
> the total 
> >activities or dose rates of U ore and spent fuel or
> reprocessing 
> >residues is somewhat problematic, because the
> compositions are very 
> >different, and therefore their behaviour in the
> environment and the 
> >biological efficiencies.
> >
> >pb
> >
> >
> >
> >
> >
> >Leo M. Lowe wrote:
> > > Hello,
> > >
> > > Further to the on-going discussions on the decay
> of spent fuel, the 
> > > National Waste Management Organization (NWMO),
> the Canadian 
> > > organization responsible for advising on how
> Canada should manage 
> > > it's spent nuclear fuel, gives a graph of the
> decay of the 
> > > radioactivity of CANDU (natural uranium) fuel
> and a table of the 
> > > dose rate around a spent CANDU fuel bundle (see
> Table A3-3 in NWMO 
> > > final report available at http://www.nwmo.ca/ )
> > >
> > > At 500 years of decay, the dose rate at 0.3 m
> distance from the 
> > > bundle is 0.82 mSv/h.  Therefore, as has been
> pointed out by others, 
> > > a worker could spend up to  7 working days (56
> hours) next to the 
> > > bundle and still not exceed the 50 mSv/y
> occupational dose limit for exposure in
> > > a single year.   While this is certainly not
> recommended, and the fuel
> > > is still quite "hot', this puts the oft-heard
> statements about the 
> > > spent fuel being dangerous for millions of years
> in a different 
> > > perspective.
> > >
> > > Regards,
> > > Leo Lowe
> > >
> 
> 
> 
> Leo M. Lowe, Ph.D., P.Phys.
> 
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