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What’s the most difficult question you’ve been asked as a maintenance instructor?
Blye Widmar
"Where are the prints?!"
This was the final question in an onslaught of verbal feedback, comments, and critiques I received from my students back in 2019. I had two years of instructor experience and was teaching a class that had been meticulously rehearsed in preparation for an accreditation visit. I knew the training material well and transferred that knowledge effectively enough for all the students to pass the class. As we wrapped up, I asked the students how they felt about my first big system-level class, and they did not hold back.
“Why was the exam from memory when we don’t work from memory in the plant?” “Why didn’t we refer to the vendor documents?” “Why didn’t we practice more on the mock-up?” And so on.
M. Fukushima, J. Goda, A. Oizumi, J. Bounds, T. Cutler, T. Grove, D. Hayes, J. Hutchinson, G. McKenzie, A. McSpaden, R. Sanchez, J. Walker, K. Tsujimoto
Nuclear Science and Engineering | Volume 194 | Number 2 | February 2020 | Pages 138-153
Technical Paper | doi.org/10.1080/00295639.2019.1663089
Articles are hosted by Taylor and Francis Online.
To validate lead (Pb) nuclear cross sections, a series of integral experiments to measure lead void reactivity worth was conducted systematically in three fast neutron spectra with different fuel compositions on the Comet critical assembly of the National Criticality Experiments Research Center. Previous experiments in high-enriched uranium (HEU)/Pb and low-enriched uranium (LEU)/Pb systems had been performed in 2016 and 2017, respectively. A follow-on experiment in a plutonium (Pu)/Pb system has been completed. The Pu/Pb system was constructed using lead plates and weapons-grade Pu plates that had been used in the Zero Power Physics Reactor (ZPPR) of Argonne National Laboratory until the 1990s. Furthermore, the HEU/Pb system was reexamined on the Comet critical assembly with a newly installed device that can measure the compression of the stack, improving reproducibility. Using the lead void reactivity worth measured in these three cores with different fuel compositions, the latest nuclear data libraries, JENDL-4.0 and ENDF/B-VIII.0, were tested with the Monte Carlo calculation code MCNP® version 6.1. As a result, the calculations by ENDF/B-VIII.0 were confirmed to agree with lead void reactivity worth measured in all the cores. It was furthermore found that the calculations by JENDL-4.0 overestimate by more than 20% for the Pu/Pb core while being in good agreement for the HEU/Pb and LEU/Pb cores.
