PREDICTION OF FALLOUT
FROM SUBSURFACE NUCLEAR DETONATIONS
JOSEPH B. KNOX
University of California, Lawrence Radiation Laboratory,
Livermore, California
ABSTRACT
A numerical simulation model has been developed for the prediction of
fallout from subsurface nuclear detonations that produce craters
through spall and the action of the cavity gas. The physical processes
modeled are atmospheric transport, lateral eddy diffusion, and gravitational sedimentation of radioactive particulates. This cratering fallout model is normalized to the observed external gamma-dose-rate
fields of the Sedan (100 kt) and the Danny Boy (0.43 kt) cratering shots
conducted at the Nevada Test Site. Calculations of the fallout patterns
for additional shots, used for testing the prediction capability of the
cratering fallout model, indicate that the model gives estimates of the
external gamma dose rate at H+ 1 hr with a maximum error of a fac-
tor of 2 to 3 in the gamma dose rate vs. distance along the hot line of
the pattern,
INTRODUCTION
During the past few years, a small but continuing effort has been
expended in developing a model for predicting fallout from subsurface
nuclear detonations. In this report the experience in predicting fallout
from surface bursts that is transferable to the construction of a fallout
model for subsurface detonation is summarized, the development of the
fallout model for subsurface nuclear detonations (the cratering fallout
model) is described, the predictive capability of the modelis illustrated
by means of independent test cases, and some of the problems asso331