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Atlanta, GA|Atlanta Marriott Marquis
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NRC’s David Wright visits the Hill and more NRC news
Wright
The Nuclear Regulatory Commission is in the spotlight today for three very different reasons. First, NRC Chair David Wright was on Capitol Hill yesterday for his renomination hearing in front of the Senate’s Environment and Public Works Committee. Second, the NRC released its updated milestone schedules according to the Nuclear Energy Innovation and Modernization Act (NEIMA) and the executive orders signed by President Trump last month; and third, as reported by Reuters on Tuesday, 28 former NRC officials have condemned the dismissal of Commissioner Hanson earlier this month.
Renomination: EPW Committee chair Sen. Shelley Moore Capito (R., W.Va.) opened the hearing with a statement praising Wright’s experience and emphasized the urgency of stable leadership at the NRC.
“China is executing a rapid build-out of its nuclear industry,” Capito said. “The demand for clean, baseload power is skyrocketing as we position America to win the AI race.”
C. D. Bowman, E. G. Bilpuch, D. C. Bowman, A. S. Crowell, C. R. Howell, K. McCabe, G. A. Smith, A. P. Tonchev, W. Tornow, V. Violet, R. B. Vogelaar, R. L. Walter, J. Yingling
Nuclear Science and Engineering | Volume 161 | Number 1 | January 2009 | Pages 68-77
Technical Paper | doi.org/10.13182/NSE161-68
Articles are hosted by Taylor and Francis Online.
The results of two experiments combined show that the diffusion length D for thermal neutrons in the graphite studied is 24% larger than expected from classical experiments and that the boron equivalent absorption is smaller than expected and consistent with zero. Taken together, the results indicate a reduction in parasitic thermal neutron absorption in heterogeneous graphite reactors by about 30%. The first experiment measured the z-dependence of thermal neutron flux in a column of 12 t of granular graphite with a neutron source at the bottom. A second measurement was made by pulsing the column with a neutron source at its center and measuring the neutron decay rate as a function of time after a pure exponential decay had been established. The diffusion coefficient D adjusted to a density of 1.60 g/cm3 is 1.05 ± 0.03 cm compared with the commonly accepted value of 0.85 ± 0.013 cm. The absorption in our graphite owing to impurities was found to be <10% of that from carbon alone. The parameter a/D that measures neutron loss was determined to be 0.000235 ± 0.000026 cm-2 for a density of 1.60 g/cm3 and may be compared with the commonly accepted value of 0.000340. The performance of graphite thermal spectrum reactors constructed using our graphite would be significantly enhanced over present expectations because neutron loss to graphite is a major factor in the neutron economy of graphite-moderated thermal reactors.