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.
Explore membership for yourself or for your organization.
Conference Spotlight
Nuclear Energy Conference & Expo (NECX)
September 8–11, 2025
Atlanta, GA|Atlanta Marriott Marquis
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
Jul 2025
Jan 2025
Latest Journal Issues
Nuclear Science and Engineering
September 2025
Nuclear Technology
August 2025
Fusion Science and Technology
Latest News
Remembering ANS member Gil Brown
Brown
The nuclear community is mourning the loss of Gilbert Brown, who passed away on July 11 at the age of 77 following a battle with cancer.
Brown, an American Nuclear Society Fellow and an ANS member for nearly 50 years, joined the faculty at Lowell Technological Institute—now the University of Massachusetts–Lowell—in 1973 and remained there for the rest of his career. He eventually became director of the UMass Lowell nuclear engineering program. After his retirement, he remained an emeritus professor at the university.
Sukesh Aghara, chair of the Nuclear Engineering Department Heads Organization, noted in an email to NEDHO members and others that “Gil was a relentless advocate for nuclear energy and a deeply respected member of our professional community. He was also a kind and generous friend—and one of the reasons I ended up at UMass Lowell. He served the university with great dedication. . . . Within NEDHO, Gil was a steady presence and served for many years as our treasurer. His contributions to nuclear engineering education and to this community will be dearly missed.”
Toshihiro Yamamoto, Hiroki Sakamoto
Nuclear Science and Engineering | Volume 199 | Number 9 | September 2025 | Pages 1365-1375
Research Article | doi.org/10.1080/00295639.2025.2463815
Articles are hosted by Taylor and Francis Online.
The calculation of the inverse reactor period α, which is a fundamental mode eigenvalue of the α-mode nonlinear Boltzmann eigenvalue equation, depends on the kinetics parameters (delayed neutron fractions, precursor decay constants, and delayed neutron spectra) used in the calculation. Recently, we developed a Monte Carlo method to calculate the derivatives of the k-eigenvalue with respect to α. Here, the k-eigenvalue is not a critical eigenvalue; rather, it is a fictitious eigenvalue introduced to determine the α value that satisfies the α-mode nonlinear equation. The sensitivity coefficients of α with respect to the kinetics parameters are expressed as the ratio of the two derivatives: the derivative of the k-eigenvalue with respect to the kinetics parameters and that with respect to α.
This study introduces a new step for calculating the derivatives of the k-eigenvalue with respect to kinetics parameters using the differential operator sampling method. The sensitivity coefficients obtained using the Monte Carlo method have been validated based on their close agreement with the reference solutions obtained using a deterministic method.
