iiinova — where your digital self keeps evolving

Nick Touran @whatisnuclear.com · 09/08/2026

I just used AI last weekend to turn a cool live skychart thing I made years ago into my watch face and it's absolutely awesome. I refuse to buy the "all AI is slop" argument.

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Nick Touran @whatisnuclear.com · 09/08/2026

Serious question to people who are protesting data centers: how would you feel if they were operated offshore? ⚛️Powered with sustainable nuclear ⛲Cooled with abundant seawater 🏠Not in anyone's backyard 🧑‍🔧Built in shipyards reindustrializing America 🇺🇸 Allows us to stay competitive internationally

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Nick Touran @whatisnuclear.com · 29/05/2026

What does "going critical" mean? If you shoot a neutron into some uranium ore, some atoms will split by fission, but you haven't made a nuclear reactor. Too many secondary neutrons leak out or get absorbed without splitting neighboring atoms. 1/n

Chain reaction pic from Duderstadt and Hamilton

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Nick Touran @whatisnuclear.com · 20/05/2026

This Combustion Engineering facility in Chattanooga, TN fabricated 57 reactor pressure vessels for US reactors, plus more overseas, and lots of other heavy equipment. As the nuclear industry ramps back up in the US, I hope we see lots more facilities like this soon.

Combustion Engineering facility in Chattanooga, TN showing lots of reactor pressure vessels

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Nick Touran @whatisnuclear.com · 27/01/2026

The classic mouse trap and ping pong ball demo, from Martin Marietta. Only problem is that the mouse traps flying around set off other mouse traps, dramatically increasing keff. They should have glued them to the bottom. (VHS quality because, well, it was on VHS)

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Nick Touran @whatisnuclear.com · 17/01/2026

Nuclear waste transport cask testing... with Red Alert music

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Nick Touran @whatisnuclear.com · 16/01/2026

At the end the girl says to check out "The Harnessed Atom" at the Dept of Energy. It's a teacher's lesson guide for nuclear lessons with tons of cool activities. www.energy.gov/ne/articles/...

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Nick Touran @whatisnuclear.com · 12/01/2026

Flash animations from the 2006 version of whatisnuclear dot com, made by yours truly. "This is what they stole from us" 😂

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Nick Touran @whatisnuclear.com · 07/01/2026

The Beetle, everyone's favorite actually-real mecha, inside and out. It was designed to do maintenance in the highly radioactive areas around nuclear-powered long-range bomber aircraft back in the nuclear-powered flight days.

The Beetle, taken from https://babel.hathitrust.org/cgi/pt?id=uc1.b4540517&view=1up&seq=293&skin=2021&q1=beetle and cleaned up with AI

The Beetle cap inside, taken from https://babel.hathitrust.org/cgi/pt?id=uc1.b4540517&view=1up&seq=293&skin=2021&q1=beetle and cleaned up with AI

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Nick Touran @whatisnuclear.com · 07/01/2026

I'm currently getting these historical nuclear films digitized. Standby! As far as I can tell, none of them exist online yet except the Accident Testing one, which shows the Sandia cask tests. I'm getting that one scanned with hopes that it'll be extra high quality for everyone's pleasure.

list of films being scanned, including:

- Umatic
- Numatec The Enrichment of Uranium
- Managing nuclear waste at the Nevada Test Site
- Basalt Waste Isolation Project
- VHS
- Splitting Atoms - An Electrifying Experience
- Martin Marietta Energy Systems Mouse trap -fission chain reaction
- Sun of Man
- Enriched Uranium
- 16-mm
- Accident Testing

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Nick Touran @whatisnuclear.com · 12/10/2025

Here's what neutron chain reaction dynamics kinda look like. The green bar is control rod position and the trace shows reactor power, starting at 1. After each control adjustment, there is a 'prompt jump' followed by a longer exponential tail from delayed neutrons.

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Nick Touran @whatisnuclear.com · 01/10/2025

Taking a Geiger counter on a flight with the sound on is a great way to get some serious side-eye from your neighbors, maybe leading to a good discussion about dose rate

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Nick Touran @whatisnuclear.com · 30/08/2025

Pretty neat model of a PWR from the 1965 Boy Scouts Atomic Energy merit badge book. Honestly, building this would help kids understand quite a bit about a reactor.

model reactor from boy scouts https://archive.org/details/atomicenergy00boys/page/n1/mode/2up

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Nick Touran @whatisnuclear.com · 18/08/2025

Looking into the core of BORAX-5, which pushed the limits of what a BWR could do: nuclear superheat and natural circulation. The superheat region is in the center. BWRs today are not so bold as to superheat steam. Have materials improved enough to try again? Probably!

Looking into the BORAX-5 nuclear reactor core

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Nick Touran @whatisnuclear.com · 04/08/2025

Getting these 45 historical nuclear films from 1955-83 dug up and digitized has been one of the coolest and most rewarding things I've done with What is Nuclear. Thanks to you all for your interest and support in this project! There are only ~100 left to get. whatisnuclear.com/museum/

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Nick Touran @whatisnuclear.com · 03/07/2025

As a penance I added CANDU to the scoping tool whatisnuclear.com/neutronics-s...

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Nick Touran @whatisnuclear.com · 03/07/2025

This is just a low-power easy-to-reconfigure critical mockup to verify the calculations and do design optimization. In the real system it would be an actual rotating drum.

real control drum design https://babel.hathitrust.org/cgi/pt?id=mdp.39015001554800&seq=216&view=1up

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Nick Touran @whatisnuclear.com · 03/07/2025

Beryllium triflute that fit between the pins in the PPA. Who's working on beryllium triflutes today?!

beryllium triflute https://babel.hathitrust.org/cgi/pt?id=mdp.39015001554800&seq=72&view=1up

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Nick Touran @whatisnuclear.com · 03/07/2025

When you have a small and high-leakage core (e.g. a sodium-cooled, beryllium or ZrH-moderated one), you can adjust control from the edge of the core.

core diagram showing rotating control drum mockups from ppa-19

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Nick Touran @whatisnuclear.com · 03/07/2025

Here's Preliminary Pile Assembly-19, where rotating control drums were first mocked up in a critical facility around 1951. Note the six smaller hexagon outlines on each corner of the central hex, each of which represents a control drum.

ppa-19 circa 1951 https://doi.org/10.2172/348907

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Nick Touran @whatisnuclear.com · 02/07/2025

We debate this endlessly within the pro-nuclear world, but I really don't think it's super complicated. There's plenty of room to promote either without throwing the other under the bus.

guy pressing two buttons to build LWRs and advanced reactors

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Nick Touran @whatisnuclear.com · 01/07/2025

No, it's very commonly stated but is not right. Plutonium for bombs was made by specialized Pu-production reactors (graphite or heavy water moderated). SFRs, PWRs, and MSRs are substantially worse for making plutonium. MSR was abandoned because (see text from whatisnuclear.com/thorium-myth...)

text from https://whatisnuclear.com/thorium-myths.html#myth1

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Nick Touran @whatisnuclear.com · 28/06/2025

Big Rock Point in Northern Michigan was the prettiest nuclear plant. It's crazy that one little 71 MWe plant like this can make enough electricity to power a whole county in peak fudgie season.

Nuclear plant along Lake Michigan with American flag. From Greenwood Cemetery archives

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Nick Touran @whatisnuclear.com · 22/06/2025

Weapons-grade enriched uranium is mostly U-235, which is less stable: it has a 704 million year half-life. A kg of it puts out 80 million alphas per second at 4.6 MeV each, so like 60 microwatts of radiation. Still, not a big radiological deal (worry more about the chemical hazard of UF₆).

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Nick Touran @whatisnuclear.com · 22/06/2025

Natural uranium is mostly U-238, with a 4.5 billion yr half-life. A kg of it kicks out 12M alpha particles per second with 4 MeV of energy each, generating 8 microwatts of ionizing radiation. It's not super hazardous, and you can hold it in the palm of your hand with a glove.

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Nick Touran @whatisnuclear.com · 18/06/2025

After much effort, I'm happy to finally present the Universal Reactor Memorandum of Understanding (MOU). This MOU is hereby issued between all current and future reactor companies and all current and future power customers. Congrats to all.

Universal MOU between all reactor companies and all customers

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Nick Touran @whatisnuclear.com · 17/06/2025

I just won a chunk of graphite from the world's first man-made nuclear reactor (CP-1) in a raffle from at the #ANSAnnual conference. I've desperately wanted one of these for decades, and entered at the last minute, thanks to a serendipitous seating at the lunch table. I'm so lucky and grateful!

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Nick Touran @whatisnuclear.com · 05/06/2025

I may have peaked as a nuclear engineering intern at the Idaho National Lab

Photo of me by a sign that says "Frank Church River of No Return Wilderness, Salmon National Forest"

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Nick Touran @whatisnuclear.com · 24/05/2025

Oh really? I was just approximating from this arrow www.energy.gov/sites/prod/f...

arrow from https://www.energy.gov/sites/prod/files/2018/01/f46/doe-ionizing-radiation-dose-ranges-jan-2018.pdf

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Nick Touran @whatisnuclear.com · 24/05/2025

Here, I made a handy radiation dose conversion chart for ya

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Nick Touran @whatisnuclear.com · 24/05/2025

Also this kind of text does support maintaining safety: www.whitehouse.gov/fact-sheets/....

screen shot from https://www.whitehouse.gov/fact-sheets/2025/05/fact-sheet-president-donald-j-trump-directs-reform-of-the-nuclear-regulatory-commission/#:~:text=MODERNIZING%20NUCLEAR%20REGULATION%3A%20Today%2C%20President,support%20our%20domestic%20nuclear%20industry.

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Nick Touran @whatisnuclear.com · 18/05/2025

Aha using the lattice subdivide trick as described in the docs increases speed by 19x. NICE.

triso compact in hex pincell with subdivided cubical lattices for speed in openmc.

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Nick Touran @whatisnuclear.com · 18/05/2025

OpenMC does an excellent job packing TRISO particles, but holy cow is transport slow! I'm getting 167 neutrons/second, gasp.

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Nick Touran @whatisnuclear.com · 17/05/2025

If you're ANYWHERE NEAR Baltimore, don't miss this chance to hop aboard the Nuclear Ship Savannah for National Maritime Day 2025. Sunday May 18, 10am–3pm 4601 Newgate Ave, Baltimore, MD 21224, USA www.ns-savannah.com/event-detail...

picture of nuclear ship savannah for open house

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Nick Touran @whatisnuclear.com · 17/05/2025

Hey TRISO modelers, when you build a neutronics input with TRISO fuel, what are your favorite ways to set a given packing fraction without cutting off particles on the edge of your pebble or compact? Does everyone just write a packing script?

hex lattice representation of TRISO particles showing cut-offs

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Nick Touran @whatisnuclear.com · 10/05/2025

This is one of the most important messages in advanced nuclear right now. www.ans.org/news/2025-05...

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Nick Touran @whatisnuclear.com · 09/05/2025

Here's the unfinished/abandoned Juragua Nuclear Power Plant in Cienfuegos, Cuba. They planned to build 12 VVER-440s with the help of the USSR but pulled the plug on the project in 1997. en.wikipedia.org/wiki/Juragua...

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Nick Touran @whatisnuclear.com · 09/05/2025

Intermediate heat exchanger comparison for some sodium-cooled reactors

Size comparison for numerous intermediate heat exchangers for sodium nuclear reactors in the US, some of which are extrapolated. source: https://babel.hathitrust.org/cgi/pt?id=mdp.39015041125884&seq=387&view=1up

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Nick Touran @whatisnuclear.com · 05/05/2025

Don't miss the sizing and weights of the Superphénix vessel and head. The concrete and steel head was 24 meters in diameter, 3 meters thick, and weighed over 4000 tonnes unequipped! 😲

Giant 24-meter diameter concrete reactor vessel

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Nick Touran @whatisnuclear.com · 03/05/2025

Lots of major equipment was fabricated for the Clinch River Breeder. Here's testing of the reactor closure head. The rotating plugs allow fuel handling without opening up the reactor. Inset rotating plugs allow you to reach all core positions. Thanks to @AaloAtomics for making this scan possible.

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Nick Touran @whatisnuclear.com · 03/05/2025

Here are the proposed changes in Dept of Energy budget from the White House's budget plan released yesterday:

table of budget cuts in DOE, from https://www.whitehouse.gov/wp-content/uploads/2025/05/Fiscal-Year-2026-Discretionary-Budget-Request.pdf

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Nick Touran @whatisnuclear.com · 02/05/2025

LANL is planning to vent some radioactive tritium. They did a worst-case analysis and found that the highest dose any one person could get is 20 mrem, which is pretty low, roughly the same as taking 5 round-trip flights. This is ~1/15th the average yearly natural background dose.

analysis from LANL showing worst case https://www.lanl.gov/engage/environment/ftwc

relative dose rates in mrem from https://www.energy.gov/sites/prod/files/2018/01/f46/doe-ionizing-radiation-dose-ranges-jan-2018.pdf

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Nick Touran @whatisnuclear.com · 01/05/2025

Views of the massive 100 ft-deep limestone excavation for the Clinch River Breeder Reactor Plant near Oak Ridge, filmed on September 10, 1983. The embattled project was cancelled soon after, and the hole was filled back in. 😔

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Nick Touran @whatisnuclear.com · 27/04/2025

Okrent, "Nuclear Reactor Safety: On the History of the Regulatory Process" was written based on an 'unpublished' 1,100-page manuscript summarizing ACRS minutes. The book is out of print, but the manuscript is available here: www.nrc.gov/docs/ML0906/...

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Nick Touran @whatisnuclear.com · 25/04/2025

In sodium-cooled fast breeder reactor land, they turned on their first 600 MWe CFR-600 back in 2023 (based on operational experience from their smaller operational SFR, CEFR) and are expected to turn the second one on next year.

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Nick Touran @whatisnuclear.com · 25/04/2025

We often worry that if we don't build more nuclear power quickly, China might take the lead. In reality, we are ~20 years behind, with 0 workhorse reactors under construction and 0 operational non-water reactors, meanwhile, China has 28 huge power reactors under construction now

Graph showing US nuclear capacity (100 GW) and under construction (0) and China capacity (~60 GW) and under construction (~40 GW).

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Nick Touran @whatisnuclear.com · 23/04/2025

"In this experiment which is built to a scale of 1: 7.5 80,000 glass spheres simulate the flow of spherical fuel elements in the core of the pebble-bed reactor. From left to right the photos show the way of a new charge of coloured spheres through the core in the course of twelve hours."

small scale experiment of glass beads representing pebbles in a pebble bed nuclear reactor. from https://archive.org/details/1964-book-gerwin-atoms-germany-225x-40/page/n122/mode/1up?q=KNK+

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Nick Touran @whatisnuclear.com · 19/04/2025

Airships with cargo payloads in the triple or quadruple digit tons!? 🤯This is an amazing idea, the first one that's pulled my attention away from shipyard constructed reactors in a long time. This could be a game-changer for delivering factory-produced reactor modules without size constraints.

an amazing thread from https://x.com/HarksenNiels/status/1913694774344695861

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