Advanced Nuclear Fuel Manufacture Finds Its Way into Industrial Chemical Engineering Literature.

[NNadir]

The paper to which I'll refer briefly in this post is this one: Effect of Temperature on the Fluid Dynamics of Heavy Particles in a Conical Spouted Bed for Nuclear Fuel Coating Guoqiang Wang, Lihua Guo, Feng Zhang, Jun Lin, and Xu Yang Industrial & Engineering Chemistry Research 2025 64 (39), 19237-19244.

I'm a regular reader of this journal for chemical processing insights, although my career has been, for many years, far more involved with analytical chemistry than with the industrial processes which were of interest in my youth. I am not a chemical engineer, nor, if I lived life over again, would I be one. Neither am I a nuclear engineer, although I have spent decades teaching myself about nuclear engineering because from an environmental perspective, I consider nuclear primary energy as the last, best, hope of the Earth.

Pebble bed nuclear reactors have a mixed history; some have operated on an industrial scale, but they never became mainstream. They did exhibit a number of problems; which is not to say they were unworkable. The worst nuclear reactor in the world is superior to the best dangerous fossil fuel power plant. As I understand it, perhaps superficially, there is renewed interest in them in the form of the Kairos reactor, which is a hybrid, pebble bed/molten salt reactor with an intellectual basis out of UC Berkeley's nuclear engineering department.

It apparently is also a technology being explored in China, China being the world leader, in my view, both in having an active and expanding nuclear manufacturing infrastructure as well as a very healthy dollop of nuclear reactor engineering creativity. They build and test novel reactor concepts, both those from long ago, like the famous thorium MSR, and perhaps, as this paper suggests, pebble bed type reactors.

I always sort of wondered how "TRISO" particles, fissionable particles surrounded by a matrix of carbides and silicides, were made, but never so much as to actually look into the matter. Hence this paper, falling into my purview by my general reading, was of interest to me.

From the introductory text:

Spouted bed technology has attracted widespread attention in various engineering fields due to its excellent mixing ability, efficient heat and mass transfer ability, and flexible operating range. (1,2) It has been widely applied in chemical, metallurgical, and energy-related processes, including biomass gasification, (3) waste gasification, (4) steam cracking, (5) fluidized catalytic cracking (FCC) regeneration, (6) iron ore reduction, (7) and nuclear fuel coating, (8) where stable hydrodynamics and uniform temperature distribution are critical for achieving optimal performance. Coated fuel particles are a prospective nuclear fuel form that is widely applicable to high/very high-temperature gas-cooled reactor, pressurized water reactor, solid molten salt reactor, and fully ceramic microencapsulated fuel concept. (9−12) The coating layer on the fuel kernel is considered the first barrier for ensuring the safe operation of a reactor. (13) Generally, the coated fuel particles are prepared by spouted bed chemical vapor deposition technology. (14−16) The quality of the coating layer depends on the hydrodynamic behaviors of particles, which are mainly affected by bed structure, gas–solid properties, and temperature, among other factors. Among these, the temperature is a crucial parameter. Some researchers have reported that inadequate control of particle hydrodynamics at coating temperatures may lead to irregularly shaped particles, twin particles, extensive agglomeration, and surface microcracks on the coating layer, significantly degrading the quality of the coated fuel particles. (17,18)

Currently, many researchers have demonstrated that using pressure fluctuation signals and obtaining power spectral density (PSD) through the fast Fourier transform (FFT) for analysis is a fundamental approach for investigating the hydrodynamic behavior of spouted beds. (19−29) In such analyses, the amplitude and intensity of dominant frequency peaks can be used to characterize the spouting state of the particles, with each peak frequency reflecting a distinct vibration source or hydrodynamic phenomenon within the bed. (20,30−32) Specifically, when the dominant frequency is below about 20 Hz, it usually corresponds to periodic vibrations in the spout zone; when the dominant frequency is above about 20 Hz, it is mainly related to particle motion in the annular zone. (19) Moreover, pressure fluctuation analysis is also widely utilized to examine overall bed dynamics. (31,33−35) However, there have been few studies on the hydrodynamic behaviors of particles at high temperatures. This is primarily due to the difficulty of visually observing and monitoring particles within opaque, high-temperature spouted bed reactors. Lin and Wey (15) studied the influence of particle size distributions on the spouting performance at high temperatures (773–1073 K). They analyzed the PSD functions and concluded the optimal spouting velocity. Svoboda et al. (21) examined the pressure drop fluctuations in the range from 293 to 1073 K, and their results indicated that the intensity and magnitude of the dominant frequency were strongly dependent on both temperature and gas velocity. Kai and Furusaki (36) measured the pressure drop fluctuations and bubble frequency at temperatures ranging from 280 to 640 K, showing that a reduction in both the standard deviation of the main frequency intensity and bubble size suggested improved spouting behavior at higher temperatures. Otake et al. (37) characterized bubble behavior from 298 to 923 K, revealing that bubble frequency increased with temperature, and bubble size was closely related to both bubble frequency and gas velocity. Additionally, Olazar et al. (38) investigated the spouting performance of low-density materials under high temperatures and vacuum conditions, and established a new relationship for the minimum spouting velocity (Ums). Nevertheless, these high-temperature studies reported varying observations and, consequently, inconsistent conclusions. At the same time, they all used low-density materials such as silica–alumina, sand, corundum, lime, and ash, and used conical–cylindrical spouted beds as experimental setups. The density of these materials is typically below 3000 kg/m³, which is much lower than that of nuclear fuel particles. For example, the density of uranium oxide is 10,963 kg/m³...

...this study investigated the effects of temperature (373–1273 K) on the hydrodynamic behavior of heavy particles in a conical spouted bed. The trend of the PSD function with respect to the temperature and gas flow was obtained. Changes in the intensity and magnitude of the main frequency under varying spouting velocities and temperatures were analyzed. Furthermore, a mechanism describing the influence of the temperature on the hydrodynamic behavior of heavy particles using PSD functions is proposed. This study provides insight into the hydrodynamic behavior of high-density particles at elevated temperatures and thus offers a valuable reference for the practical preparation of coated fuel particles...

The paper is, of course, very esoteric, and I won't spend any time on the details. It's just nice to see in a journal dedicated to industrial engineering, which means it's serious.

As the collapse of the planetary atmosphere is now well underway, a discussion of a serious approach to slowing or stopping its rate of acceleration is welcome to see.

After the United States' suicide, in placing power in the likes of Steven Miller and his sock puppet, the orange perverted pedophile, it's nice to believe that the world will yet go on.

Have a nice weekend.