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2026 Annual Conference
May 31–June 3, 2026
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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.
E. E. Bloom, F. W. Wiffen, P. J. Maziasz, J. O. Stiegler
Nuclear Technology | Volume 31 | Number 1 | October 1976 | Pages 115-122
Technical Paper | Material | doi.org/10.13182/NT76-A31703
Articles are hosted by Taylor and Francis Online.
Results of a series of neutron irradiation experiments conducted on annealed and 20% cold-worked Type 316 stainless steel in a high-flux mixed-spectrum fission reactor to simulate a controlled thermonuclear reactor (CTR) first wall displacement per atom (dpa) and helium production are reviewed. Using previously suggested criteria of a maximum of 10% volume increase and a minimum of 0.5% uniform strain in a uniaxial tensile test, estimates of temperature and fluence limits for this alloy are made. The large amounts of helium produced by irradiation in the mixed-spectrum fission reactor caused significantly more swelling than occurred in fast reactor irradiations (low helium-generation rates). Cold working effectively suppressed swelling up to 550 to 600°C. Using a criterion of 10% swelling and limited data on the fluence dependence of swelling, a first wall life of 16.5 (MW yr)/m2 (at 530°C) for 20% cold-worked Type 316 stainless steel is estimated. Embrittlement may be the property that limits first wall life. At 350°C acceptable ductility was retained in the cold-worked steel to very high damage levels (49 dpa, 3320 appm helium), and it appears that the 0.5% uniform strain criterion will not be limiting. At higher temperatures, however, this is not the situation. At 650°C the uniform and total plastic strain were zero in samples irradiated to 61 dpa and 4140 appm helium. At 575°C, 0.5% uniform strain was retained in the cold-worked material to relatively high damage levels; however, the fractures were intergranular. The creep-rupture life at 550 and 45 000 psi was reduced by 5 × 104 compared to the unirradiated property. Generally greater embrittlement in the solution-annealed material suggest that cold-worked material would be preferred for CTR first wall structures. The marked reduction in ductility and rupture life and intergranular tensile fractures suggest that stress will have to be maintained at very low levels to prevent fracture. The loss of ductility indicates reductions in fatigue life that must be investigated.
