International Explosives Safety Symposium
San Diego, California, August 2018
1
Risk-Based Explosion Assessment
Internal Explosion of Exploration Upper Stage in Vehicle Assembly Building
Jon Chrostowski & Wenshui Gan; ACTA Inc.;
2790 Skypark Drive: Suite 310, Torrance, CA. 90505
Mark Femminineo; NASA/KSC; Exploration Ground Systems, FL
Keywords: explosives safety siting, internal explosion, air blast, fragmentation
ABSTRACT
This paper presents risk-based explosion analyses used to determine if an explosion of NASA’s Space Launch System
(SLS) Exploration Upper Stage (EUS) during fueling in Vehicle Assembly Building (VAB) High Bay 4 can hazard
the Space Launch System (SLS) being processed in Bay 3. This paper focuses on blast fragmentation as it was the
controlling hazard. An estimate of the amount of Net Explosion Weight (NEW) was used to develop a fragment list
(mass, shape, takeoff velocity/angle) given an explosion occurs at ground level in Bay 4. Intervening superstructure
that exists between Bay 4 and Bay 3 (that could potentially block EUS fragments) was modeled based on detailed
visual images (VISSIM) and AUTOCAD/structural drawings. The fragment list was input to a 3D trajectory
application that performs multiple random explosion simulations; each simulation varying fragment ballistic
coefficient and takeoff angle/velocity. Individual fragments are tracked until stopped by the intervening superstructure
or reach Bay 3, potentially impacting the SLS. The probability of impacting the SLS is then determined from the
random simulations; the results are used to help decision-makers determine the efficacy of co-processing within the
VAB and decide what mitigations may be appropriate.
INTRODUCTION
ACTA was asked to evaluate hazards that could result if a hydrazine explosion occurred during processing of an
Exploration Upper Stage (EUS) in VAB High Bay 4 while the SLS is being processed in Bay 3.
Figure 1 shows the
Vehicle Assembly Building and a plan view of VAB Bays 3/4 with the EUS processing location in Bay 4 and the SLS
in Bay 3.
Figure 1. Plan View of VAB High Bays 3 and 4.
Complete documentation is available in Reference [1].
