An Estimation of the Inventory of Weapons Grade Plutonium in North Korea Using Depletion Codes.

[NNadir]

I stumbled upon an interesting find while looking for something else:

South Korean nuclear engineers have estimated the amount of weapons grade plutonium produced by North Korea using the 5 MWe YongByon.

The paper in which this is discussed is here: Geon Hee Park, Ser Gi Hong, An estimation of weapon-grade plutonium production from 5 MWe YongByon reactor through MCNP6 core depletion analysis, Progress in Nuclear Energy, Volume 130, 2020, 103533.

I don't have time to discuss the contents of the paper, but here's the conclusion:

We estimated WG plutonium production using the operation history given in the literature and the results of depletion analysis with ORIGEN-S and MCNP6. The estimated WG plutonium productions up to 2015 were compared the reference values given by Hecker, Braun, and Lawrence, which showed that ORIGEN-S overestimates WG plutonium inventory by 4–5.7 kg while MCNP6 underestimates by 2–4 kg in comparison with the reference values. Finally, we estimated WG plutonium productions after 2015 with the assumptions on the capacity factors and the irradiation times by considering two reactor operation and related reprocessing events. With these additional estimates after 2015, the WG plutonium production was estimated to be 46.7–76.6 kg by 2019 using the MCNP6 depletion results.

The "Fat Man" design of a nuclear weapon, utilized a little over 6 kg of plutonium, but it was designed by some of the finest minds that ever lived, using nearly unlimited industrial resources. If the intervening 3/4 of a century have made similar technology available in a poor country like North Korea, this suggest that they might have enough plutonium to make between 8 and 12 Nagasaki type bombs.

They have conducted six nuclear weapons tests.

It is important to note that the Nagasaki bomb, although it destroyed a city, was a relatively small device as nuclear weapons go.

Interesting I think.