ANS is committed to advancing, fostering, and promoting the development and application of nuclear sciences and technologies to benefit society.
Explore the many uses for nuclear science and its impact on energy, the environment, healthcare, food, and more.
Division Spotlight
Mathematics & Computation
Division members promote the advancement of mathematical and computational methods for solving problems arising in all disciplines encompassed by the Society. They place particular emphasis on numerical techniques for efficient computer applications to aid in the dissemination, integration, and proper use of computer codes, including preparation of computational benchmark and development of standards for computing practices, and to encourage the development on new computer codes and broaden their use.
Meeting Spotlight
2024 ANS Annual Conference
June 16–19, 2024
Las Vegas, NV|Mandalay Bay Resort and Casino
Standards Program
The Standards Committee is responsible for the development and maintenance of voluntary consensus standards that address the design, analysis, and operation of components, systems, and facilities related to the application of nuclear science and technology. Find out What’s New, check out the Standards Store, or Get Involved today!
Latest Magazine Issues
Mar 2024
Jan 2024
Latest Journal Issues
Nuclear Science and Engineering
April 2024
Nuclear Technology
Fusion Science and Technology
February 2024
Latest News
Can hydrogen be the transportation fuel in an otherwise nuclear economy?
Let’s face it: The global economy should be powered primarily by nuclear power. And it probably will by the end of this century, with a still-significant assist from renewables and hydro. Once nuclear systems are dominant, the costs come down to where gas is now; and when carbon emissions are reduced to a small portion of their present state, it will become obvious that most other sources are only good in niche settings. I mean, why use small modular reactors to load-follow when they can just produce that power instead of buffering it?
Alexander Agung, Danny Lathouwers, Tim H. J. J. van der Hagen, Hugo van Dam, Christopher C. Pain
Nuclear Technology | Volume 165 | Number 2 | February 2009 | Pages 133-144
Technical Paper | Fission Reactors | doi.org/10.13182/NT09-A4081
Articles are hosted by Taylor and Francis Online.
A new design of a fluidized bed has been proposed and it has been shown that under steady condition the reactor is able to produce power up to 120 MW. To study the behavior of the reactor under transient conditions as well as its stability, a model describing the coupling of neutronics, thermal hydraulics, and fluidization is applied. The objective of this study is to comprehend whether the reactor is stable under its operational range. Further, knowledge of the extent of operational parameters under large perturbations is necessary for a safe operation.The stability of the system is investigated by numerical means and is performed by linearizing and perturbing the system around its equilibrium points to form Jacobian matrices. The resulting matrices are further used to obtain the eigenvalues of the system. The system is investigated under variation of mass flow rate, and it is found that within the operational range the eigenvalues are located in the negative part of the phase plane, implying linear stability. Further, the calculated decay ratios indicate a strongly damped system.Simulations of transient conditions are performed, namely, a step change in coolant flow rate and inlet temperature, representing situations that might occur in real operations of the reactor. The coolant flow rate is varied by ±1 kg/s and the inlet gas temperature is varied by ±10 K from their steady state of 33 kg/s and 543 K, respectively. Another transient is also simulated, i.e., a transient related to noise resulting from stochastic movements of the fuel particles. For this purpose, an additional term is included in the reactivity feedback and modeled as a time-dependent external reactivity. Magnitude of the variance for this simulation is obtained from the preceding static calculations. These simulations show that the total power of the reactor may fluctuate and reach high values. However, the fuel temperature, thanks to passive reactivity feedback, is well below safety limits at all times.