[ RadSafe ] RE : Spent fuel and decay

Thu Jul 26 18:03:57 CDT 2007

John --

The code is called ORIGEN (Oak Ridge Isotope Generation and Depletion
Code) and is part of Oak Ridge's SCALE (Standardized Computer Analyses
for Licensing Evaluations) package.  There are several versions -- the
current supported version is ORIGEN-ARP 5.1 ... see
http://www.ornl.gov/sci/origen-arp/index.htm 

Jim

>>> John R Johnson <idias at interchange.ubc.ca> 7/26/2007 18:31 >>>
Jim and Mike

I knowl that there was a computer program that gave the isotope 
concentrations in spent fuel as a function of time, and burn up, since
the 
spent fuel was removed from the reactor. I don't know what it was
called but 
it may be referenced in
DOSE CONVERSION FACTORS USED IN THE CURRENT CANADIAN HIGH LEVEL WASTE 
DISPOSAL ASSESSMENT STUDY

J. R. Johnson

AECL-7869, Radiation Protection Dosimetry 3 No. * (1982) 47-50.

John***************
John R Johnson, PhD
CEO, IDIAS, Inc.
Vancouver, B. C.
Canada
(604) 222-9840
idias at interchange.ubc.ca 

----- Original Message ----- 
From: "Jim Hardeman" <Jim_Hardeman at dnr.state.ga.us>
To: "Mike (DOH) Brennan" <Mike.Brennan at DOH.WA.GOV>;
<radsafe at radlab.nl>
Sent: Thursday, July 26, 2007 3:15 PM
Subject: RE: [ RadSafe ] RE : Spent fuel and decay

> Mike --
>
> Good observation. As I recall, the primary driver for long-term
isolation 
> of spent fuel is dose through the groundwater pathway. I'd have to go
back 
> and look not only at 10 CFR 63 but EPA's standards, but I believe EPA

> wants groundwater concentrations of radionuclides to be less than
their 
> Maximum Contaminant Level (MCL) over the entire period over which 
> consequences are assessed -- I think that's now up to 100,000 years.
>
> I don't know much about the geology of Washington State, but if your

> geology is anywhere like Georgia's, you'll find quite a few places
that 
> exceed MCL for naturally-occuring radionuclides (Ra-226, Ra-228,
uranium 
> being the ones currently regulated -- plus total alpha activity
(excluding 
> uranium) and total beta activity) . While the MCL for beta-emitters
is 
> based on dose (i.e. 4 mrem/yr assuming 2 liter per day consumption
rate), 
> the actual dose from Ra-226, Ra-228 and uranium at MCL concentrations
will 
> be substantially greater. The MCL for uranium, for example, is in
ug/l (30 
> ug/l as I recall) rather than pCi/l. We've noticed that the U-234 /
U-238 
> ratio in groundwater isn't constant, and that the dose associated
with a 
> concentration of 30 ug/l can vary considerably based on the U-234 /
U-238 
> ratio.
>
> What I'm getting at here is that the regulatory framework for spent
fuel 
> actually regulates risk through the groundwater pathway at a value
far 
> less than the risk associated with groundwater that might be
associated 
> with natural uranium deposits.
>
> My $0.02 worth --
>
>>From the piney woods of northern Michigan (on vacation)
>
>
>
> Jim Hardeman, Manager
> Environmental Radiation Program
> Environmental Protection Division
> Georgia Department of Natural Resources
> 4220 International Parkway, Suite 100
> Atlanta, GA 30354
> (404) 362-2675
> Fax: (404) 362-2653
> Personal fax: (678) 692-6939
> E-mail: Jim_Hardeman at dnr.state.ga.us 
>
>
>>>> "Brennan, Mike  (DOH)" <Mike.Brennan at DOH.WA.GOV> 7/26/2007 17:49
>>>
>>From the information I have and the interesting site Leo linked to,
I
> agree that driver for activity in the long run is Pu.  I just ran a
> spread sheet looking at the U235-U238-Pu239 ratios and the effect on
> total activity, and it is clear that once the fission fragments have
> decayed away enough (a couple hundred years, more or less) the total
> activity is mostly driven by how much U238 was changed into Pu239,
and
> how much of the Pu239 was in turn destroyed by fission.  While these
> numbers would all depend on the original make-up of the fuel and its
> history with a reactor, it seems reasonable to say that the fuel
would
> reach its original activity after around 10,000 years (fairly wide
band
> "around"), and that it would be low enough activity to handle
without
> special precautions several thousand years before then.
>
> All in all, while spent fuel presents non-trivial challenges for
> storage/disposal, the claims that it must be kept isolated for
100,000
> (or 1,000,000, as I heard recently) years is clearly not based on
actual
> risk.
>
>
>
> -----Original Message-----
> From: radsafe-bounces at radlab.nl [mailto:radsafe-bounces at radlab.nl]
On
> Behalf Of Pete_Bailey at fpl.com 
> Sent: Thursday, July 26, 2007 10:32 AM
> To: radsafe at radlab.nl 
> Subject: [ RadSafe ] RE : Spent fuel and decay
>
>
>> ... how long it takes spent fuel to decay to the Aactivity level it
>> had before going into the reactor?
>
> If by 'activity level', you mean 'curies', one very very long time.
>
>> I realize it is highly dependant on factors such as level of
>> enrichment, amount of burn-up, activation of cladding, etc, and
>> breeding of Pu.
>
> Level of enrichment & 'burn-up'(MWT/MTU) drive the length of time.
> Most activation products (active...of clad) fizz out in  a decade or
> so...
> The breeding of Pu....it ain't there to
> start with (for all intent and purposes), and has mega-year
half-life.
> _______________________________________________
> You are currently subscribed to the RadSafe mailing list
>
> Before posting a message to RadSafe be sure to have read and
understood
> the RadSafe rules. These can be found at:
> http://radlab.nl/radsafe/radsaferules.html 
>
> For information on how to subscribe or unsubscribe and other
settings
> visit: http://radlab.nl/radsafe/ 
> _______________________________________________
> You are currently subscribed to the RadSafe mailing list
>
> Before posting a message to RadSafe be sure to have read and
understood 
> the RadSafe rules. These can be found at: 
> http://radlab.nl/radsafe/radsaferules.html 
>
> For information on how to subscribe or unsubscribe and other settings

> visit: http://radlab.nl/radsafe/ 
> _______________________________________________
> You are currently subscribed to the RadSafe mailing list
>
> Before posting a message to RadSafe be sure to have read and
understood 
> the RadSafe rules. These can be found at: 
> http://radlab.nl/radsafe/radsaferules.html 
>
> For information on how to subscribe or unsubscribe and other settings

> visit: http://radlab.nl/radsafe/ 