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November 8–12, 2025
Washington, DC|Washington Hilton
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From renaissance to reality: Infrastructure for a global nuclear fuel cycle
Dale Klein
This article was adapted from the author’s speech during a plenary at the 21st International Symposium on the Packaging and Transportation of Radioactive Materials (PATRAM 2025), San Antonio, Texas, July 2025.
There has been a lot of discussion lately about reforming the Nuclear Regulatory Commission. But I want to be clear: When it comes to nuclear safety and security, there is no place for partisan politics. I support efforts to streamline regulatory processes, but the independence and integrity of the NRC must remain sacrosanct. If we are serious about expanding nuclear power and reclaiming our global leadership in nuclear technology, having a strong independent regulator is fundamental.
Right now, we’re on the edge of a global nuclear resurgence driven by rising demand from data centers, growing concerns about energy security, and the need to decarbonize industry.
John F. Carew, Kai Hu
Nuclear Science and Engineering | Volume 152 | Number 3 | March 2006 | Pages 256-273
Technical Paper | doi.org/10.13182/NSE06-A2580
Articles are hosted by Taylor and Francis Online.
The changes in the energy dependence of the neutron removal cross section at the vessel inner wall water/steel interface produce a substantial shift in the neutron spectrum as the fluence propagates into the pressure vessel. To account for this spectral shift, Regulatory Guide 1.99, Revision 2 requires that the fluence used in determining the reference temperature for nil-ductility transition RTNDT be extrapolated from the pressure vessel inner surface using the displacements per atom (dpa).The strong azimuthal and axial variation of the fluence at the vessel inner wall results in a substantial redistribution of the fluence as it propagates through the vessel due to transverse neutron leakage (i.e., perpendicular to the radial direction through the vessel). This transverse leakage tends to increase the dpa radial attenuation in regions of high fluence and reduce the attenuation in regions of low fluence.A series of pressure vessel fluence calculations has been carried out to determine the effect of (a) the transverse neutron leakage and (b) the plant-specific reactor design configuration on the radial attenuation of the dpa through the vessel. The calculations were performed for four operating pressurized water reactors and were carried out using the methods described in U.S. Nuclear Regulatory Commission Regulatory Guide 1.190. The calculations were performed with the DORT discrete ordinates transport code using ENDF/B-VI neutron transport and dpa cross sections.The transverse leakage is found to introduce a substantial variation of the dpa attenuation rate over the inner surface of the vessel. In the belt-line region opposite the core, the transverse leakage results in an ~6 to 14% azimuthal variation and an ~3 to 11% axial variation in the dpa at a 15-cm depth into the vessel, depending on the plant configuration.In order to simplify the determination of RTNDT in probabilistic fracture mechanics analyses, conservative belt-line and reflector region dpa attenuation rates have been determined. Plant-specific analytic expressions for the radial dependence of the dpa through the vessel have also been determined.
