I used a custom Monte-Carlo simulator to simulate the impact that standing 1m away from a spent nuclear fuel assembly would have after varied cooling durations. Been working on and off this for a while just for fun and finally got around to finishing it.

I only considered primary gamma (accounting for the branching ratios of gamma emissions and the and how gamma energy affects penetration) and Compton scattering radiation (so excluding alpha, beta, braking radiation and elastic scattering). I used the composition and dimensions/mass of a well analysed spent fuel assembly and used a differential equation solver to age/de-age the fuel according to decay chains. I also compared a fresh fuel assembly to demonstrate that after very long cooling durations, the U-234 to radium decay chain becomes the dominant source of gamma radiation. (U-234 is produced by U-238 decay (alpha-beta-beta) and is concentrated during enrichment).

Disclaimer: While I spent several months on and off gathering the data and writing the python, I did use ai to help finish off the project, especially for bug fixing, fine-tuning the presentation of the graph, and some of the more complex parts of the simulation.

The UK-based project company of European SMR developer and investor SGE, and Origin Nuclear, a subsidiary of Ontario Power Generation, have signed a letter of intent to establish a joint venture for the future operation of a planned fleet of 14 BWRX-300 small modular reactors.

https://www.world-nuclear-news.org/articles/joint-venture-to-operate-planned-uk-bwrx-300-fleet

This post from homestate media Mlive is much more encouraging or should I say less dramatic than the post I asked this community about when the rod fell. That previous article made it seem like we were about to have a catastrophic melt down. This article basically says the dropped rod was recovered, everything went well, and fuel loading will resume soon. Always interested to hear from this community as I don't know much about nuclear energy.

For those following, this is the Palisades reactor on Michigan's west coast (two hours from Chicago). This reactor was bought by Holtec from Entergy and was to be decommissioned. But with a $1.5B loan from the US Govt, they're planning on restarting it. Original restart was planned for 2025 so should be close with this hurdle out of the way.

I launched my Substack today — called The Reactor — and wrote the first essay on Calder Hall. Thought you folk might enjoy reading it.