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
Nuclear Installations Safety
Devoted specifically to the safety of nuclear installations and the health and safety of the public, this division seeks a better understanding of the role of safety in the design, construction and operation of nuclear installation facilities. The division also promotes engineering and scientific technology advancement associated with the safety of such facilities.
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
Apr 2024
Jan 2024
Latest Journal Issues
Nuclear Science and Engineering
June 2024
Nuclear Technology
May 2024
Fusion Science and Technology
Latest News
Commercial nuclear innovation "new space" age
In early 2006, a start-up company launched a small rocket from a tiny island in the Pacific. It exploded, showering the island with debris. A year later, a second launch attempt sent a rocket to space but failed to make orbit, burning up in the atmosphere. Another year brought a third attempt—and a third failure. The following month, in September 2008, the company used the last of its funds to launch a fourth rocket. It reached orbit, making history as the first privately funded liquid-fueled rocket to do so.
Osamu Mitarai, Akio Sagara, Nobuyoshi Ohyabu, Ryuichi Sakamoto, Akio Komori, Osamu Motojima
Fusion Science and Technology | Volume 56 | Number 4 | November 2009 | Pages 1495-1511
Technical Paper | doi.org/10.13182/FST09-A9253
Articles are hosted by Taylor and Francis Online.
A new control method for the unstable operating point in the force-free helical reactor (FFHR) is proposed for low-temperature and high-density ignited operation. While in the stable ignition regime, the error of the fusion power of e'DT(Pf) = +(Pf0 - Pf) is used to obtain the desired fusion power with proportional-integral-derivative control of the fueling, we have discovered that in the unstable ignition regime, the error of the fusion power with an opposite sign of e'DT(Pf) = -(Pf0 - Pf) can stabilize the unstable operating point. Here, Pf0 is the fusion power set value, and Pf is the measured fusion power. Around the unstable operating point, excess fusion power (Pf0 < Pf) supplies fueling, increases the density, and then decreases the temperature. Less fusion power (Pf0 > Pf) in the subignited regime reduces the fueling, decreases the density, and then increases the temperature. While the operating point rotates to the clockwise direction in the stable ignition boundary, it rotates to the counterclockwise direction in the unstable ignition regime. Using this control algorithm, it is demonstrated that the operating point can reach the steady-state condition from an initial very low-temperature and low-density regime. The fusion power can also be shut down from the steady-state condition without any problems. Furthermore, characteristics of the stable and unstable ignition regimes are compared for the same fusion power, and control robustness to changes with various parameters has been studied.