nuclear reactors

3 Articles

Deep Fission Wants To Put Nuclear Reactors Deep Underground

November 23, 2025 by 73 Comments

Today’s pressurized water reactors (PWRs) are marvels of nuclear fission technology that enable gigawatt-scale power stations in a very compact space. Though they are extremely safe, with only the TMI-2 accident releasing a negligible amount of radioactive isotopes into the environment per the NRC, the company Deep Fission reckons that they can make PWRs even safer by stuffing them into a 1 mile (1.6 km) deep borehole.

Their proposed DB-PWR design is currently in pre-application review at the NRC where their whitepaper and 2025-era regulatory engagement plan can be found as well. It appears that this year they renamed the reactor to Deep Fission Borehole Reactor 1 (DFBR-1). In each 30″ (76.2 cm) borehole a single 45 MWt DFBR-1 microreactor will be installed, with most of the primary loop contained within the reactor module.

As for the rationale for all of this, at the suggested depth the pressure would be equivalent to that inside the PWR, with in addition a column of water between it and the surface, which is claimed to provide a lot of safety and also negates the need for a concrete containment structure and similar PWR safety features. Of course, with the steam generator located at the bottom of the borehole, said steam has to be brought up all the way to the surface to generate a projected 15 MWe via the steam turbine, and there are also sampling tubes travelling all the way down to the primary loop in addition to ropes to haul the thing back up for replacing the standard LEU PWR fuel rods.

Whether this level of outside-the-box-thinking is a genius or absolutely daft idea remains to be seen, with it so far making inroads in the DoE’s advanced reactor program. The company targets having its first reactor online by 2026. Among its competition are projects like TerraPower’s Natrium which are already under construction and offer much more power per reactor, along with Natrium in particular also providing built-in grid-level storage.

One thing is definitely for certain, and that is that the commercial power sector in the US has stopped being mind-numbingly boring.

 

How Germany’s Troubled Pebble Bed Reactor Came Of Age In China

December 14, 2023 by 57 Comments

Although the concept of nuclear fission is a simple and straightforward one, the many choices for fuel types, fuel design, reactor configurations, coolant types, neutron moderator or reflector types, etc. make that nuclear fission reactors have blossomed into a wide range of reactor designs, each with their own advantages and disadvantages. The story of the pebble bed reactor (PBR) is among the most interesting here, with its development winding its way from the US Manhattan Project over the Atlantic to Germany’s nuclear power industry during the 1960s, before finding a welcoming home in China’s rapidly growing nuclear power industry.

As a reactor design, PBRs do not use fuel rods like most other nuclear reactors, but rather spherical fuel elements (‘pebbles’) that are inserted at the top of the reactor vessel and extracted at the bottom, allowing for continuous refueling, while helium acts as coolant. With a strong negative temperature coefficient, the design should be extremely safe, while providing high-temperature steam that can be used for applications that otherwise require a coal boiler or gas turbine.

With China recently having put its twin-PBR HTR-PM plant into commercial operation, why is it that it was not the US, Germany or South Africa to first commercialize PBRs, but relative newcomer China?

Continue reading “How Germany’s Troubled Pebble Bed Reactor Came Of Age In China” →

Getting IEC Standards For Free

December 26, 2016 by 28 Comments

The International Electrotechnical Commission (IEC) is an international body that issues standards on a wide range of electronics-related topics. How wide? Their mandate seems to span rules for household product safety to the specification of safety logic assemblies in nuclear power plants. Want to know how to electrically measure sound loudness? Test methods for digital door lock systems? Or maybe you’re interested in safety interlock systems for laser processing machines. There’s an IEC standard for that too.

Unfortunately, this information is kept behind a paywall. OK, it’s a lot more like a pay fortress. They really, really don’t want you accessing their documents without first coughing up. This is a shame.

The IEC doesn’t just make the standards in a vacuum, however. Before the scribes touch their chisels to the stone tablets, there are draft versions of the standards that are open for public comment by those knowledgeable in the field. And by “those knowledgeable”, we mean you, dear hacker. Head on over to the public commenting page, sign up, and you’ve got free access to every document that’s currently up for discussion.

Now, it does look like the IEC doesn’t want you sharing these PDFs around — they watermark them with your username and threaten all sorts of things if you use them for anything other than commenting purposes — so don’t go abusing the system. But on the other hand, if you are a private individual who knows a thing or two about a thing or two, we think you’re entirely right to look over their shoulders. Let us know in the comments if you find any gems.

They’ve even got a weekly update feature (in the registration pages) that’ll keep you up to date. And who knows, maybe your two cents, submitted to your country’s chapter of the IEC, will influence future international standards.

Thanks to [Johann] for the great tip!