Re: Activation and dose rate in concrete in 40 years.

Hello Alberto and Mary,

Thank you for your replies.

My question is in regards to a new project, namely shielding assessment for a vault/target area holding a 24 MeV
cylotron, with multiple beamlines, targets, beam intensities and profiles.

I am sorry but my question was not stated correctly. Turns out the CNSC would like to have an overview of the
radiological state of the cyclotron room at the time of decommission, (30-40 years after the operation). So mainly long
lived activation in concrete (Eu-152, Eu154, Co-60, Cs-134, Ba-133).

Am I correct to say that I the limitation of 20 irradiation time intervals (via IRRPROFI cards) is for older versions of
FLUKA? Looking through the manual for 2011.2.13, I don't see this anywhere. All I see (under section 7.36: IRRPROFi),
is note 1:

"Several cards can be combined up to the desired number of irradiation intervals."

So, is there an unlimited irradiation time intervals that a user can set (not that I am going to go through the trouble
of setting time intervals such as (2 hours/per irradiation * 2x daily) for a total of 1000 hours per year for 30 years
for a particular target for instance).

Thank you,
Mina

On 12-08-09 02:49 PM, Alberto Fasso' wrote:
> Hi Mina,
>
> what is the difference between calculating decay for 5 years and for 40 years?
> (And for 500 years, I add...)
>
> The manual, at the command RADDECAY, says:
>
> 'In the "activation study" mode (WHAT(1)=1) the time evolution is calculated analytically'
>
> So, decay is calculated by a formula, where you can put any time you want.
> Whether you get anything meaningful, depends only on the half-life of the
> radioisotopes present. If there are any very long-lived (I don't think so)
> perhaps you can get some results different from zero even after 40 years.
> Check with RESNUCLE what are the produced isotopes with the longest half-life,
> and make a simple guess if it is worth doing the calculation.
> Normally the longest-lived is tritium with 12 years half-life. 40 years
> are about 3 half-lives, and the activity decreases by a factor about 8.
>
> However tritium is difficult to detect in concrete... but this is another story.
>
> Alberto
>
>
>
> On Tue, 7 Aug 2012, Mina Nozar wrote:
>
>> Hello everyone,
>>
>> Will FLUKA be able to simulate activation and dose rates in concrete (of the vault walls) 40 years after end of beam,
>> i.e. at the time of decommissioning of a cyclotron?
>> I have used FLUKA to look at activations as far as 5 years after EOB but not 40 years.
>>
>> Thank you very much,
>> Mina
>
Received on Fri Aug 10 2012 - 09:03:53 CEST