Reply To: YouTube Focus Fusion Video

[Brian H]

jamesr wrote:

What is the penetration of the gamma? Assuming the B10 to be an external shell around the water, would it be a danger in the surrounding service space? Since the =>12s decay time you give for the B10 is so brief, I would assume that the gamma would be produced only while the core was active, and a short period afterwards (a few minutes to subside to insignificant levels).

The B10 would normally dissolved in the water as boric acid not as a shell An alternative to water could be borated polyethene sheets, as they wouldn’t need to be as thick to slow down the neutrons. The decay time is 1ps not 12s ie. pretty instantaneous.
The low energy gammas do need some additional shielding, but a steel water tank plus a few inches of lead, or a foot of high density concrete should be sufficient.
I can no longer locate the source posting, but I distinctly recall something (I think from Eric) indicating that the B10 was external, not dissolved. Something like 1″ or so thickness.