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Conference Spotlight
2025 ANS Winter Conference & Expo
November 8–12, 2025
Washington, DC|Washington Hilton
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Energy Secretary to speak at the 2025 ANS Winter Conference & Expo
In less than two weeks, the American Nuclear Society’s second annual conference of the year, the 2025 ANS Winter Conference & Expo, will come to Washington, D.C.
Today, ANS is announcing that Energy Secretary Chris Wright will be joining the list of nuclear leaders slated to speak at the conference.
Click here to register for the meeting, which will take place November 9–12 in Washington, D.C., at the Washington Hilton. Be sure to do so before November 7 to take advantage of priority pricing.
Richard Sanchez
Nuclear Science and Engineering | Volume 177 | Number 1 | May 2014 | Pages 19-34
Technical Paper | doi.org/10.13182/NSE12-95
Articles are hosted by Taylor and Francis Online.
We investigate the degeneracy of the first-order PN equations and construct interface and boundary conditions that ensure a unique solution. Our technique is based on establishing an equivalence between the first- and second-order PN equations and showing that the (regular) second-order equations with opposite parity to N are nondegenerate. Assuming bounded angular flux moments and sources, we derive interface and boundary conditions for the regular second-order equations that, via the equivalence, are those to be used with the first-order PN equations. While providing independent derivations, our results reproduce those derived using solid harmonic expansions by Davison and Rumyantsev in the 1950s.
