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NE Colloquium. John Mihalczo - Historic Measurement with up to 3 Metric Tons of Weapons Grade HEU (93.4 235-U) Metal

In 1959 Y-12 was storing 93.4 wt. % 235 enriched uranium metal castings (25 kg slabs) on three foot centers and was running out of storage space. Y-12 approached the Oak Ridge Critical Experiments (ORCEF) with the question “how close can they be stored to alleviate the storage problem?”. At this time, there were significant lack of cross section data (over decades in energy) for multi energy group calculations, so experiments addressed nuclear criticality safety problems. Over 3000 kg of weapons grade HEU metal (over 50 unreflected critical masses) were sent to ORCEF. Very careful experiments were performed with up to 5x5x5 arrays of castings to seek solution to the problem.  With this much material, there was potential for really disastrous consequences. (This type of experiment would never be permitted today). Neutron multiplication measurement were performed to obtain estimated of the critical configurations as a function of spacing between slabs, moderator between slabs, effect of reflectors and internal neutron absorbers. These results for the first experiments with so much enriched uranium metal are presented along with the temporary and final solution to the Y-12 storage problem.

Wednesday, November 7, 2018 at 1:30pm to 2:30pm

Nuclear Engineering Building, 302
1412 Circle Drive Knoxville TN 37996

Event Type

Lectures & Presentations




Current Students, Faculty & Staff


NE Colloquium, NE Fall 2018, Nuclear Engineering



Nuclear Engineering

Contact Name

Michelle McBee

Contact Email

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