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Conference Spotlight
2025 ANS Winter Conference & Expo
November 8–12, 2025
Washington, DC|Washington Hilton
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Latest News
DNFSB’s Summers ends board tenure, extending agency’s loss of quorum
Lee
Summers
The Defense Nuclear Facilities Safety Board, the independent agency responsible for ensuring that Department of Energy facilities are protective of public health and safety, announced that the board’s acting chairman, Thomas Summers, has concluded his service with the agency, having completed his second term as a board member on October 18.
Summers’ departure leaves Patricia Lee, who joined the DNFSB after being confirmed by the Senate in July 2024, as the board’s only remaining member and acting chair. Lee’s DNFSB board term ends in October 2027.
C. A. Bisselle, John A. Wethington, Jr.
Nuclear Technology | Volume 5 | Number 6 | December 1968 | Pages 445-455
Technical Paper and Note | doi.org/10.13182/NT68-A27970
Articles are hosted by Taylor and Francis Online.
A technique was developed for determining the previously unknown thermal-neutron diffusion parameters, ∑a and D, of a small amount of a moderating material, perfluorodimethylcyclohexane, C8F16. A two-region cylindrical system consisting of C8F16 in the core region and water in the reflector region was pulsed with neutrons to obtain the decay constants for several heights of the system. By comparing these results with those obtained from a similar water-graphite experiment and by utilizing one-group, two-region diffusion theory, it was possible to obtain the desired parameters for the fluoro-carbon, i.e., D(C8F16) = 1.02 cm, ∑a(C8F16) = 90 × 10−5/cm, and L(C8F16) = 33.6 cm. This technique offers a convenient method for determining the neutron diffusion parameters of small samples of rare materials.
