Nick Touran
@whatisnuclear.com
Ph.D./P.E. nuclear engineer and nuclear educator who runs https://whatisnuclear.com. Thinks about how to deliver nuclear power reliably and cheaply, advanced reactors, reactor history, energy.
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.
October 12, 2025 at 2:03 PM
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.
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
October 1, 2025 at 4:58 PM
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
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.
August 30, 2025 at 1:39 AM
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.
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!
August 18, 2025 at 6:00 PM
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!
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/
There are only ~100 left to get.
whatisnuclear.com/museum/
August 4, 2025 at 11:57 AM
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/
There are only ~100 left to get.
whatisnuclear.com/museum/
As a penance I added CANDU to the scoping tool whatisnuclear.com/neutronics-s...
July 3, 2025 at 4:39 PM
As a penance I added CANDU to the scoping tool whatisnuclear.com/neutronics-s...
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.
July 3, 2025 at 12:43 PM
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.
Beryllium triflute that fit between the pins in the PPA.
Who's working on beryllium triflutes today?!
Who's working on beryllium triflutes today?!
July 3, 2025 at 11:53 AM
Beryllium triflute that fit between the pins in the PPA.
Who's working on beryllium triflutes today?!
Who's working on beryllium triflutes today?!
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.
July 3, 2025 at 11:30 AM
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.
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.
July 3, 2025 at 11:30 AM
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.
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.
July 2, 2025 at 11:17 AM
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.
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...)
July 1, 2025 at 2:07 PM
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...)
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.
It's crazy that one little 71 MWe plant like this can make enough electricity to power a whole county in peak fudgie season.
June 28, 2025 at 11:06 AM
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.
It's crazy that one little 71 MWe plant like this can make enough electricity to power a whole county in peak fudgie season.
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).
June 22, 2025 at 2:41 PM
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).
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.
June 22, 2025 at 2:41 PM
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.
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.
June 18, 2025 at 1:46 PM
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.
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!
June 17, 2025 at 7:53 PM
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!
Who's all coming to #ANSAnnual in Chicago?
June 15, 2025 at 8:03 PM
Who's all coming to #ANSAnnual in Chicago?
I may have peaked as a nuclear engineering intern at the Idaho National Lab
June 5, 2025 at 1:26 PM
I may have peaked as a nuclear engineering intern at the Idaho National Lab
Oh really? I was just approximating from this arrow www.energy.gov/sites/prod/f...
May 24, 2025 at 4:32 PM
Oh really? I was just approximating from this arrow www.energy.gov/sites/prod/f...
Here, I made a handy radiation dose conversion chart for ya
May 24, 2025 at 4:20 PM
Here, I made a handy radiation dose conversion chart for ya
Also this kind of text does support maintaining safety: www.whitehouse.gov/fact-sheets/....
May 24, 2025 at 1:24 PM
Also this kind of text does support maintaining safety: www.whitehouse.gov/fact-sheets/....
Aha using the lattice subdivide trick as described in the docs increases speed by 19x. NICE.
May 18, 2025 at 5:59 PM
Aha using the lattice subdivide trick as described in the docs increases speed by 19x. NICE.
OpenMC does an excellent job packing TRISO particles, but holy cow is transport slow! I'm getting 167 neutrons/second, gasp.
May 18, 2025 at 11:54 AM
OpenMC does an excellent job packing TRISO particles, but holy cow is transport slow! I'm getting 167 neutrons/second, gasp.