The PM-1 Final Summary Report received via FOIA

By Dr. Nick Touran, Ph.D., P.E., 2023-09-22 , Reading time: 6 minutes

I got it! The PM-1 Final Summary Report was delivered to me yesterday after I filed a FOIA request to the military library that had it cataloged (at their recommendation). This is the pure-gold lessons-learned report from operating a 1 MWe military microreactor in WY for 4 years.


It contains cost and performance information, summarizing which systems worked well and which ones did not. This is a follow-up to some searching I did after getting this summary film digitized.

It’s highly readable. The summary says that it was a big pain to maintain b/c it was too compact. They wanted it designed for maintainability first and compactness next. “Consequently, the Air Force now has a plant that is neither portable nor easily maintainable or operable.” 👀

They had environmental issues. If it was hotter than 80° F outside the turbine oil overheated, but if it was cold the condenser tubes froze. Though it was a 1 MWe reactor, it hardly ever ran over 0.6 MWe.

The Air Force had lots of trouble keeping qualified people around to operate PM-1. Lots of folks trained on it on their way down to Nukey Poo, the reactor powering a McMurdo station in Antarctica.

Total performance is summarized. While they weren’t thrilled with the overall performance, the reactor did have the record uptime at the time of writing: 4101 hours (171 days). This was before commercial LWRs had really been fine-tuned to run 1.5-2 years straight.

The reactor had no shortage of maintenance issues. Its failures caused 40 power outages at the radar station in its 4 years of operation. There were over 100 unplanned scrams.

The maintenance issues are broken down by systems. Each system has a paragraph describing how well or poorly it worked, and suggestions for how to improve in the future. Current microreactor developers: this is super interesting!

They did not like their hair-trigger nuclear instrumentation system. The control rod drives were also highly problematic.

Plant HVAC was their biggest problem.

You get the idea, I won’t list all the rest of them, but it’s most stuff like this. All plant modifications are also listed out. There were a lot of them!

There’s a discussion of how many people would be realistically needed to operate the plant in the field. While 2 people were supposed to operate the plant, a crew of 25 is actually needed.

In summary, the report concludes that without major improvements, nuclear power has a dim economic outlook based on this experience.

Notably, they really were not impressed with how much maintenance the conventional (non-nuclear) parts of the plant required. “Perhaps another approach is necessary”. Direct energy conversion, anyone?

Overall, a highly valuable document of high interest to any reactor designer. I uploaded it here. Enjoy!

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