Joseph K. Asahina

Long-Term, High-Throughput Operation of a Controlled Detonation Chamber Based on Shakedown Under Initial Overload in the Plastic Range

Hydrostatic or pneumatic overpressure testing prior to actual service provides a number of purposes related to structural integrity of pressure vessels, including some degree of confirmation of both the design and fabrication processes. For detonation chambers designed to control impulsive pressure loadings, preservice hydrostatic testing at impulses greater than those expected during normal operation can provide an added benefit—the ability to reduce cyclic fatigue damage caused by long-term, high-throughput operation, where the chamber may be use to control hundreds or even thousands of detonations without compromising structural integrity through excessive fatigue crack initiation and growth. This paper illustrates the favorable characteristics of controlled detonation chamber operation following an initial preservice impulsive over-testing program that demonstrates shakedown and satisfaction of strain ratcheting criteria, leading to favorable cyclic fatigue behavior during subsequent long-term, high-throughput operation.

Prediction of Time to Significant Cracking and Actual Behavior of an Impulsively Loaded Detonation Chamber for Chemical Weapons Destruction

For repeated operation of a detonation chamber, evaluation of its fatigue damage and estimation of time to crack initiation are of considerable importance from the aspect of safe operation.This paper proposes the use of a sufficiently conservative operation control fatigue evaluation curve, based upon the ASME Code fatigue design curve and the best fit laboratory air curve upon which the design curve is derived, in order to define operational points for actions to inspect for possible fatigue damage and initiate repairs, as needed. The paper also recommends appropriate actions to verify that any needed repairs maintain structural integrity during subsequent operations.Copyright

Damage Caused by Dynamic/Cyclic Loading of Detonation Chamber

The plastic damage caused by multiple dynamic loading and its influence on the ductility and toughness of 3.5%Ni-steel (SA203E) and C-steel (SA516M) were examined for the discussion of integrity design of detonation chambers. V-notched specimens and hourglass specimens were welded on 1/7-scale model of a 1-ton explosive class detonation chamber and subjected to 30 detonation shots. It has been indicated that 30 detonation shots caused pre-strain in the specimens. The ductility was reduced by the pre-strain. The Charpy impact toughness was affected as well in a lower temperature. It has been noted that the damage is developed with fatigue crack growth at notch root of the V-notched specimen.© 2011 ASME

Long-Term and High Throughput Operation of a Detonation Chamber by Utilizing Shakedown Phenomenon Under Initial Overload in Plastic Range

ASME published Code Case 2564 [1] in January 2008 on impulsively loaded vessels, which is currently the first design guidance of this kind worldwide. The authors participated in the Task Group on Impulsively Loaded Vessels reporting to Sec. VIII, Div. 3 [2] and were also intimately engaged in the development, design and operation of the DAVINCH® detonation chambers. DAVINCH® is an acronym for D etonation of A mmunition in a V acuum IN tegrated CH amber, utilized for destruction of old non-stockpile chemical weapons, which were recovered from underground and sea in several areas of Japan, China, and Belgium. The quantity destroyed to-date has reached as high as 7,000 munitions.Copyright

Dynamic Analysis of Detonation Chamber and Assessment Based on ASME Code Section VIII, Division 3 and Code Case 2564

The most simple and effective method for destroying chemical weapons, and thus eliminating stockpiling problems, is to detonate the entire payload in a chamber without separating the chemical agent from the explosives. A double walled chamber was developed by Kobe Steel, Ltd. (KSL) and has destroyed more than 7000 chemical weapons throughout the world since 2000. Explosion analysis (by AUTODYN) and dynamic structural analysis (by LS-DYNA) performed during development of the chamber design are presented with the experimental results. Design of the latest version of the double walled chamber was evaluated in accordance with the ASME Code Section VIII, Division 3 and Code Case 2564 based on the results of dynamic analysis and measured strains.Copyright

A Study on Safer Operation of Impulsively Loaded Vessels

ASME published Code Case 2564 [1] in January 2008 on impulsively loaded vessels, which is the first design guidance of this kind worldwide. The authors participated in the Task Group of Sec. VIII, Div. 3 [2] and were also intimately engaged in development, design and operation of detonation chambers DAVINCH® . DAVINCH® is an acronym for D etonation of A mmunition in V acuum IN tegrated CH amber, utilized for destruction of old non-stockpile chemical weapons, which were recovered from underground and sea in several areas of Japan, China, and Belgium. The quantity destroyed to-date has reached as high as 4,500 items. Figure 1, and 2 show the installations of DV65 at Port Kanda, Japan and DV50 at Poelkapelle, Belgium, with maximum capacity of 65kg and 50 kg TNT-equivalent respectively.Copyright

Detonation Chamber of Chemical Munitions: Its Design Philosophy and Operation Record at Kanda, Japan

Destruction of chemical weapons is a technical area that involves extensive international cooperation, with open discussion among a wide variety of participants aimed at elimination of these weapons of mass destruction. The most common methods for destruction of chemical weapons are: (1) chemical neutralization and (2) incineration after separation of the chemical agent from the weapon’s explosive charge. When the munitions are stockpiled, the agent and the explosive charge are easily separated by means of reverse assembly or water jet cutting. However, for munitions that are not stockpiled, complete separation of agent and explosive charge is nearly impossible.© 2006 ASME