Misty Castle: High-Explosive Nuclear Effects Simulations at White Sands Missile Range

Middle North V: Dice Throw (1976)

“The Dice Throw events were the last programmed tests to be conducted in the Middle North series. It consisted of five phases:

1. A series of 1-pound tests to examine cratering and fireball effects due to explosive configuration and charge detonation system variations in a highly controlled test medium;
2. A series of 1,000-pound equivalent events to gain experience with ANFO, as well as also examining cratering and fireball effects in a common medium using both TNT and ANFO charges;
3. A series of 5-ton equivalent events to identify the most likely ANFO source configuration;
4. A series consisting of two 100-ton equivalent events in a geology of Air Force interest to verify the program compliance to objectives and to provide detailed data to support charge performance characterization of a 500-ton equivalent event;
5. The 500-ton equivalent event.

Phases 1 through 4 were called the ANFO Charge Development Program, with Phases 1 and 2 conducted on Kirtland Air Force Base, Albuquerque, New Mexico. Phases 3 and 4 were conducted on the White Sands Missile Range at the Queen 15 location and were titled Pre-Dice Throw I and II, respectively. Phase 5 of the program was called Dice Throw and was conducted at the Giant Patriot site also located on White Sands Missile Range. The overall program was conducted from January 1975 through June 1977 with a total of 42 agencies participating.”

Pre-Dice Throw I (1975)

Objectives

Primary Objective: Develop a charge configuration using ANFO that would best match the blast results of TNT.

Secondary Objective I: Measure airblast and detonation velocity.
Secondary Objective II: Measure ground-motion and localized seismic activity.
Secondary Objective III: Collect ejecta and study earth-particle motion.

Event Summary

“[Pre-Dice Throw I] was conducted in April through July 1975, at a dry, fine-grained alluvial site near Queen 15 on White Sands Missile Range… The intent was to select an ANFO charge which appeared to best meet the program objectives by using lightly instrumented and well photographed events.”

“Approximately 30 channels of ground-motion and airblast instrumentation were recorded on each of the first three events, and six channels of airblast data were recorded on the fourth event. Each event was photographically recorded with high-speed cameras from three azimuths, and measurements of the craters and ejecta were taken.”

“The results of the first three events… indicated that the objective of matching basic phenomenological effects of TNT and ANFO detonations was obtainable; however, ANFO did not produce a cleaner airblast environment than TNT in the [Events II and III] detonations. A fourth ANFO event [Event IV] was executed in an attempt to reduce anomalous explosive jetting. Arguments for number, shape and size of boosters, charge configuration and containment methods were reviewed and an ANFO charge was designed to incorporate all reasonable changes. Among the changes incorporated were: the use of a seven cylindrical booster-initiation system in place of a larger five-point system; a charge constructed of bagged ANFO in place of a container filled with loose ANFO; a redundant firing system; and an adjustment to the charge configuration to improve cratering correlations with the TNT baseline data. The event designated as [Event IV] produced a shock environment with no perceptible explosive jets.”

“The results of [Pre-Dice Throw I] thus indicated some marked variations between ANFO and TNT detonations, although the primary objectives of the program were met if proper care were taken with charge construction and initiation techniques.”

Pre-Dice Throw II (1975)

Objectives

Primary Objective: Prepare an initial high-explosive test environment for instrument and equipment calibration and best practices in preparation for the upcoming Dice Throw test.

Secondary Objective I: Measure and collect debris/ejecta.
Secondary Objective II: Obtain seismic refraction/reflection data.
Secondary Objective III: Measure free-field airblast environment, detonation velocity, and thermal environment.
Secondary Objective IV: Compare actual test data to predicted models.

Event Summary

“The Pre-Dice Throw II program conducted near the Queen 15 Site on White Sands Missile Range consisted of three separate events: the Cylindrical In-Situ Test (CIST), the 100-ton TNT surface-tangent sphere, and 120-ton ANFO right-circular cylinder, base-tangent to surface, with hemispherical top. This phase of the Dice Throw program was initially designed as a calibration series for the main event. However, because of the amount of experimental participation on the TNT event, which was required for cratering, airblast, and ground-shock data to calibrate the specific geology, the word calibration was dropped.”

“The CIST required a cased hole with steel liner 47 feet deep and 28 inches in diameter to contain the explosive. The explosive used was 205 pounds of 400-grain PETN primacord with a weight distribution of 5 pounds per foot. The total depth of the charge from the ground surface was 41.3 feet. The primacord was strung on racks which were hooked together.”

“This test was designed to measure the dynamic response of the site area geology to a cylindrically symmetrical high-explosive shock input, the data obtained providing a data base from which the in-situ dynamic material properties may be determined. These properties were required to adequately define the constitutive relationships needed for free-field computer simulation. Four types of measurements were made: cavity pressure, acceleration (horizontal and vertical), and stress and strain.”

“The 100-ton TNT surface-tangent sphere event used a charge with a radius of 7.87 feet and was placed on a base made of three layers of 3/4-inch plywood nine feet in radius. The lower hemisphere was supported with polystyrene blocks that were cut to conform to the outer surface of the TNT. These polystyrene blocks were pre-cut and marked according to TNT layer prior to stacking. Each layer of TNT was sprayed with an anti-static solution. The charge was designed by the Defense Research Establishment Suffield in Alberta, Canada.”

“The 120-ton ANFO charge was a right-circular cylinder, base-tangent to the ground surface, hemispherical top, with a multiple detonation system. The charge was constructed from pre-mixed bagged ammonium nitrate and diesel fuel, composed of 94.5 percent ammonium nitrate and 5.5 percent Number 2 diesel fuel. The length to diameter proportion of the cylindrical section was 0.75 to 1.00.” A total of 297 man-hours were required to stack the entire 120-ton charge.

Dice Throw (1976)

Date: 6 October 1976
Location: Giant Patriot Site, White Sands Missile Range
Explosive Charge: 628 tons, ANFO

Objectives

Primary Objective: Provide a simulated nuclear blast and shock environment for target-response experiments that are vitally needed by the military services and defense agencies concerned with nuclear weapons effects, and to confirm empirical predictions and theoretical calculations for blast response of military structures, equipment, and weapon systems.

Secondary Objective I: Measure the airblast and thermal environments in and around Ground Zero.
Secondary Objective II: Obtain data on the blast effects of hardened shelters and equipment.
Secondary Objective III: Measure and collect ejecta and debris from blast.
Secondary Objective IV: Document the nature of the ground-motion environment and localized seismic situation.

Event Summary

“In January 1975, under the direction of the Defense Nuclear Agency, an intensive program was initiated to develop an alternate high-explosive source for use on large-scale nuclear weapons effects testing programs. Several factors contributed to the need for an alternate explosive source. Among these were the dwindling reserves of TNT, which had been salvaged from munitions, and mounting costs for remolding TNT into a suitable size and shape for charge construction. In addition, TNT detonations commonly exhibited a large number of ‘explosive jets,’ or airshock anomalies, resulting in perturbed dynamic pressures in some regions of the test bed which adversely affected the desired uniform airshock expansion in a highly unpredictable manner. The net effect was that 20 to 30 percent of the surface airblast targets could be subjected to a shock environment for which they were not designed, resulting in loss of valuable experimental data.”

“Dice Throw was the fifth in a series of 500-ton high explosive events conducted by the Defense Nuclear Agency for the Department of Defense. This event was designed to provide a blast and shock environment comparable to a 1-kiloton nuclear source using only conventional explosives.”

Dice Throw was conducted at the Giant Patriot Site, located 12 miles southeast of Stallion Range Center in the northern portion of the range, approximately 100 miles north of main post. The site itself was laid out with three instrumentation parks. To reach the site, WSMR constructed a total of seven miles of paved road to support the fielding efforts.

Most of the experiments were placed in the predicted overpressure range of 5-100psi. The closest experiment to the charge container was fielded by Boeing, and was located only 200 feet from ground zero.

Thirty-one different experiments and twelve scientific support functions were fielded for the Dice Throw event. The Department of Defense fielded fifteen experimental programs while military contracting companies fielded ten programs. Participating foreign countries were the United Kingdom, Canada, Norway, Sweden, the Federal Republic of Germany, and the Netherlands. These countries performed six distinct experiments.

The explosive charge was composed of 622 tons of bagged and bulk ANFO, producing a stack approximately 30 feet in diameter and 37 feet in height. Building the stack required 24,903 fifty-pound bags of ANFO. The design and construction of the stack was performed by the Civil Engineering Research Facility of the University of New Mexico. Due to delays during the stack building phase, charge construction operations had to be performed at night. The structure covering the charge was erected primarily to provide protection from the weather and was dismantled prior to event execution.