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

[Peter Bossew]

Leo, and others,

I agree with you. The figure which you gave clearly shows that the 
frequently heard claim, that spent fuel is a "deadly danger for 100.000s 
of generations", is obviously nonsense, in terms of handling that stuff. 
On the other hand, I would not recommend eating it, even after 1 Mill. 
years ;-)  . Also, some of the longest-lived nuclides (99Tc, 129I) are 
quite mobile, unfortunately.

regards,
pb




Leo M. Lowe wrote:
> 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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-- 


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Peter Bossew 

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