[open] Full Disclosures

[Dartz]

From: Ladiesman77@friggarock.fen
To: [Classified disclosures]
Encrypted and Cleared: J247_08_Black
Subj: Critical Vulnerability in Roughriders Engine systems

Anika finally convinced me to release this thing to people who can do something about it. But this really, really must not go outside this group or *very bad things* will happen. It's the sort of thing that, once you read it, you can't ever tell anyone. It's a Great Justice 'Black Notice' sort of thing - the sort of thing troubleshooters will use unecessary force to stop from getting public because it is that dangerous.

Everyone who gets this has been pre-cleared to know about it, and only everyone who has. You can thank 'sis for your conscription. If you think there's anyone else who needs to be on the list, you need to propose it.

If you don't want to know what it is, you can leave right now, because this thing *terrified* me. If you do, there's a tattelate in the link below that'll load the true message from a secure server, and tell me you read it. Clicking the link is basically agreeing to be under a Black Notice for this sort of information.

Spoiler

The short story is, every roughrider engine built in the last 12 years is a proliferation risk.

You know it. Now you can't unknow it.

Background:

Roughriders Cool Cuke engines from 2014 onwards to current run on a mix of Uranium 235 and 238. The Uranium is currently enriched under tight security using an inertial differentiation process. Inside the engine, the U235 is the active reactant, with some of the 238 transmuting into Plutonium to further undergo fission.

The 'Hot Cuke' project.

An ongoing project is to boost a standard Cool Cuke core by using some of the reaction energy to initiate a fusion reaction in a seperate chamber, and use the excess fasat neutrons from this reaction to boost the output from the core by fissioning the 238 alongside the 235. Deuterium was added to the fuel rod to make Uranium Deuteride to up the efficiency of the engine a little.

A test-run for the engine core onboard the Dragon Wagon II ended with the core destroying itself

The deuterium hydride was a moderator for the reactor core. With a low rate of fission within the fuel, and a lot of iodine poisoning, a high gain setting of the fusion booster and the configuration of the engine reflector assembly, the core went supercritical. We had an 'uncommanded fission surplus which rapidly dissasembled the test engine.

The engine was modified with a boron injection system to stop it but, well, the madboy in me triggered and I had a bad idea that I just had to check.

Uranium Deuteride as a path to Nuclear Weapons.

Most nukes use 'Fast' neutrons. Nuclear weapons using 'slow' or moderated neutrons were'nt explored in depth, because two early tests were called failures. The yield was considered too low. Because of the tests were called failures, I think everyone just overlooked the possibility

But both tests prove it was still possible to produce a workinl, small-scale weapon using low enriched Uranium that would still have an explosive yield above what would be possible with conventional explosives.

I ran acomputer simulation of a hollow implosion core made from low-enriched uranium deuteride, with tritium boosting in the pit, was able to achieve an excursion of 3-400 tons equivelant before the simulation crashed. This was based on a computer program designed for modelling engine cores so should be taken with a grain of salt - it didn't model the destruction of the core.

For obvious reasons, a practical test was never done.

The Bottom Line:

Every single Cool Cuke reactor core is a potential proliferation risk each time refuelling is required.

Mitigation of the vulnerability:

The longer a core's been operating, the lower a threat it represents. The risk is highest with fresh engine cores that are being replaced.

As a short term solution, the enrichment ratio of freshly issued cores can be reduced. This will reduce the life of the core, but bring the core below the point where a moderated reaction can actually go supercritical.

As a long-term Asagiri has designed a variant of the Cool Cuke core that will run on reactor grade plutonium. These cores can be swapped for Cool Cuke engines with minimal modifications. Design details are attached - there's enough Plutonium 240 in the fuel mix to make them useless as a weapon material. The 240 does create an additional heatload on the core when it is shut-down that needs a larger heat sink.


We can't build near enough of them to replace every Roughriders engine, or make enough plutonium fuel if someone else could build the cores. So, I've attached the core design and fuel profile to this post. These are freely given with no licensing or stuff.

If you've read that, the floor's now open to coming up with some ways of actually dealing with this. If you haven't, you probably did the right thing.

-Mackie