DYNA JOURNAL ENGINEERING

The dilemma is not simple, as the former, in addition to the size and the advantage of having some units built and considered as "generation III+", the latter, with a majority still in design, authorisation or projects, are in some cases heading towards incorporating themselves into the so-called "generation IV".
Already almost two years ago, this situation was exposed in our news (https://www.revistadyna.com/noticias-de-ingenieria/mini-y-microreactores-seran-futuro-para-energia-nuclear-de-fision) and the technology of SMR units has been advancing, even encouraged by the development of proposals for obtaining the so-called hydrogen. Our DYNA Magazine, in articles published in March and May 2017 (Nuclear energy in China), presented the projects for the aforementioned SMRs existing in that country within the so-called "generation IV".
We can now say that one of them has become a reality: in December 2023, the first high-temperature gas-cooled modular pebble bed reactor (HTR-PM) of the two that make up the Shidao Bay Nuclear Power Plant in Shandong Province (China), the only one in the world to date within this "Generation IV", began operating tests. It uses helium as a coolant and uses a German system from the 1980s, spheres coated with uranium particles and immersed in graphite, as fuel. With a thermal power of 200 MW per unit, the helium outlet temperature can reach 750ºC, producing superheated steam at 560ºC. In addition to electricity generation, this steam can also be used for residential or industrial applications such as hydrogen production.
Especially in the US, dozens of organisations are developing designs or scale prototypes of SMR reactors with different fuel and cooling technologies (molten salts or metals, gases, or even the usual pressurised water), but without yet obtaining permits or construction agreements. One of them, Terra Power, originally set up by Bill Gates, is also targeting ship propulsion, which is difficult to decarbonise because of the energy required to move the ships. Currently, more than 160 ships are powered by nuclear reactors, mainly submarines, but also other types of ships, especially military vessels such as aircraft carriers and icebreakers. Hyundai Shipyard (Korea) will participate with Terrapower in a process to determine the infrastructure and safety protocols for the use of nuclear reactors on merchant ships and to collaborate with the International Atomic Energy Agency and Ship Classification Entities on an eventual regulatory framework.