[Isotope-prod] Meeting notes

[George Neil]

Kevin
Can you give us a ROM?
George


On 9/12/2015 10:01 PM, Pavel Degtiarenko wrote:
> Hi George and All,
>
> I have set up a toy FLUKA model for the Radium irradiation, that can 
> simulate Ac-225 production. That is all extremely preliminary and 
> would require independent verification. But one immediate engineering 
> question came along, and in any case it will have to be answered 
> before we could propose a solution for the Radium irradiation problem.
>
> The question is: what is the maximum heat power that could be 
> deposited safely and continuously into the Radium target.
>
> In any realistic setup, power deposition in the target will be not 
> small. The figure of merit, "Ac-225 hourly production per power in the 
> target" in (mCi/hour)/kW, varies, depending on the setup, from about 6 
> mCi/h/kW in the case when 150 MeV beam strikes directly at the target, 
> - to about 22 mCi/h/kW at 75 MeV and with a 2 rad. lengths radiator in 
> front of the target. The setup with thin radiator and sweeping magnet 
> before the target can produce 13 mCi per hour in the target 10 cm away 
> from the radiator at the full beam 150 MeV, 1 mA (150 kW), and the 
> power in the target is evaluated to be about 700 W. The term "hourly 
> production" here means that the target is irradiated for one hour, 
> parent Ra-225 is produced, and then, in 15-20 days, Ac-225 daughter is 
> "harvested".
>
> One gram (one Ci) of Radium is a small target, I used a cylinder 1 cm 
> length and 0.48 cm diameter.
>
> Seems like for any setup we would need a reliable engineering 
> evaluation of the methods of taking heat off the small target. That 
> would be one of the critical parameters that set limits on possible 
> solutions.
>
> One approach could be to investigate the option to use a beryllia (for 
> example, see http://www.sanjosedelta.com/beryllium_oxide.shtml) 
> vessel, holding Radium, cooled from the outside (by water?..). It 
> should be shaped appropriately (with cooling fins attached, or such). 
> The irradiation could happen through the entrance beryllia window.
>
> Radium boils at 1140 C, and beryllia can be operated at up to 1800 C. 
> So I guess the option to remove Radium from one such vessel into 
> another without a loss could be the distillation process again: heat 
> everything above 1140 C and attach a fresh vessel with a colder bottom.
> Actinium should mostly stay, as it boils above ~3000 C.
>
> Best regards,
> Pavel