Critical Assemblies: Dragon Burst Assembly and Solution Assemblies

Abstract

This work reviewed the historical literature associated with the Dragon experiment and Water Boiler reactors operated at Los Alamos during the Manhattan Project. Frisch's invited talk given at the Fast Burst Reactor Conference held the University of New Mexico in Albuquerque, NM in 1969 is quoted. From the literature review, basic models for the Dragon experiment and for a Water Boiler type assembly (aqueous homogeneous reactor) were created that can be used for conducting multi-physics simulations for criticality excursion studies. This methodology utilizes the coupled neutronic-hydrodynamic method to perform a time-dependent dynamic simulation of a criticality excursion. MCNP® was utilized to calculate important nuclear kinetic parameters that were incorporated into the models. Simulation results compared reasonably well with historic data.

Nuclear Science for the Manhattan Project and Comparison to Today’s ENDF Data

“…Peierls deputized for Chadwick and had a highly impactful role at Los Alamos as Bethe's Theoretical Division's T-1 group leader for implosion physics (at Los Alamos he was known as much for his hydrodynamics expertise as for his nuclear physics 38 ). Frisch became the leader of the Gadget Division's criticality group, G-1, and made numerous nuclear physics contributions at Los Alamos (for example, the Dragon experiment described in this issue 23 ), and Peierls tells the nice story that Frisch was equally renowned for his talents on the piano, and at one musical evening in Los Alamos the remark was overheard: "This guy is wasting his time doing physics!" (Ref., 5 26 These are shown below in Fig.…”

“…A two-pronged approach was taken, one being to measure the fundamental "differential" cross sections and neutron energy and scattering angle spectra, the other being to measure integral quantities. This paper focuses on the former approach, while other papers in this issue by Hutchinson, Kimpland, Myers et al [22][23][24] and Ref. 25 focus on the latter approach: integral critical assembly measurements.…”

Thirty Minutes Before the Dawn

“…The implosion concept was more complex than a gun, but such a design would overcome the predetonation problem and require less fissile material. Meanwhile, progress was being made to determine the critical masses and hence the amounts of special nuclear material needed (see Chadwick,5 Hutchinson et al, 6 and Kimpland et al, 7 this issue). Just two weeks later, Oppenheimer reorganized the Laboratory to make the implosion concept a reality.…”

Criticality Experiments with Fast 235U and 239Pu Metal and Hydride Systems During the Manhattan Project

“…These types of measurements were then performed during 1944 and 1945, as described below and in our companion paper on the Water Boiler and Dragon. 6 The results of these criticality experiments were so important that Oppenheimer stated to "notify him at once if any serious change in the estimated critical mass should be indicated by the experiments". 7 The focus of this work is on two specific experiments: one using metal 235 U and 239 Pu in spherical geometry and one utilizing cubes of 235 U in hydride form.…”