Chemical Explosion/Nuclear Explosion Equivalences and Differences as Identified in the Near-Field Data From the SPE Program

Date: 4/24/2019

Time: 06:00 PM

Room: Grand Ballroom

The Source Physics Experiment (SPE) is improving understanding of explosion phenomenology. SPE consists of a series of chemical explosions in each of two phases: Phase I in granite and Phase II in dry alluvium. A concern in explosive effects studies is the equivalence between nuclear and chemical sources and the efficacy of using chemical explosives to study nuclear effects.

The SPE near-field includes accelerometers with individual transducers selected based on the expected environment predicted using the work of Perrett and Bass (P&B). P&B is a compendium of nuclear event free-field data, with yield-scaled attenuation fits for peak acceleration, peak velocity, and peak displacement in several geologies, including the two SPE geologies described above plus wet tuff and dry tuff. The fits describe two distinct attenuation regimes: close to the source is a “non-linear” regime dominated by plasticity effects; at distance the “elastic” regime has a slower attenuation rate.

We found that the P&B hard rock fit is a good predictor for SPE Phase I in granite. However, we identified shortcomings of P&B for the dry alluvium Phase II data. The data gathered thus far indicate agreement with the P&B fits in the non-linear regime. However, the break to the linear attenuation regime for SPE alluvium occurs at a closer scaled range than for the nuclear dataset. But once achieved, the Phase II linear rate of attenuation matches that for P&B. In a separate analysis, Bonner et al. describe that the Phase II surface measurements are similarly underpredicted by P&B. The implication is that P&B appears to be a poor indicator of expected ground motion with distance in porous media such as alluvium and possibly tuff. By extension, these results provide some evidence for insufficient efficacy of using chemical sources to replicate nuclear effects.

Presenting Author: Garrett G. Euler

Authors