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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.
T. M. John, Om Pal Singh
Nuclear Science and Engineering | Volume 85 | Number 4 | December 1983 | Pages 362-370
Technical Paper | doi.org/10.13182/NSE83-A18383
Articles are hosted by Taylor and Francis Online.
The results of a theoretical study of noise transmission characteristics of multiplying media and neutron noise source localization in liquid-metal fast breeder reactors (LMFBRs) by using the neutron wave propagation technique is reported. The study was carried out using one-group as well as multigroup diffusion theory. Both theories show that the noise transmission characteristics are quite sensitive to the multiplication factor k of the medium. For k very close to unity, the response of the out-of-core detectors is found to be the same irrespective of the location of the neutron noise source in the multiplying medium. However, for a highly subcritical reactor, the response of the out-of-core detectors is sensitive to the location of the neutron noise source, and from the point of view of the noise transmission characteristics, the medium behaves like a nonmultiplying medium. The analytical results of one-group theory that are fully supported by the multigroup multiregion theory clearly indicate that the neutron noise signal at detector locations can be assumed to be made up of two components—the first (local) is insensitive to the multiplication factor, and the second (global) is very sensitive to the multiplication factor of the system. If the local component can be separated from the total out-of-core detector signal, then a proper calibration of the local component with respect to the various locations of neutron noise source may help in finding the location of the neutron noise source in LMFBR cores. Further, it is observed that, as in the case of nonmultiplying media, noise transmission through largely subcritical multiplying media occurs with equal attenuation for all frequencies w < (υ∑t)min, where υ is the speed of the neutrons and ∑t is the total removal cross section, and for w > (υ ∑,t)min, the attenuation increases with frequency. However, for a critical system, the global component in a multiplying medium is maximum at lower frequencies and decreases rapidly for higher frequencies, and the local component remains the same as in the case of largely subcritical systems.
