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H EXCERPT FROM THE U.S. ARMY'S 5X DECONTAMINATION REVIEW 262 H Excerpt from the U.S. Army's 5X Decontamination Review The following is the text from a memorandum on 5X decontamination for the Chief of the Engineering and Technology Division, U.S. Army, from Barbara A. Kuryk; Chief of the Process Development Branch. Graphical and tabular attachments to that memorandum are not included. 1. A review of documentation concerning 5X decontamination has been completed per your request. A list of the references that were reviewed is provided at enclosure 1. The information reviewed includes literature searches, test reports, general background documentation, and correspondence. This review focused on three aspects of 5X decontamination: related background information, 5X criteria evaluation, and 5X testing. 2. An understanding of the definition of 5X decontamination and the knowledge of the standard Army criteria for 5X decontamination was necessary to review the documentation. Decontamination to the 5X level indicates the equipment or facilities have been completely decontaminated, axe free of agent and may be released for general use or to the public (reference 18). The current standard Army criteria to meet the 5X requirement is to maintain the temperature of the article at 1000°F for 15 minutes ensuring agent destruction (reference 27). 3. Related Background Information. The background topics reviewed are related to 5X decontamination and either support the 5X criteria or are the basis for other studies. The topics of primary interest are laboratory scale incineration studies and hot air decontamination studies. a. Incineration Studies. The incineration studies that were found dealt with the incineration of the nerve agents GB and VX. This information was reviewed to find background substantiation for the 1000°F and 15 minute criteria.
H EXCERPT FROM THE U.S. ARMY'S 5X DECONTAMINATION REVIEW 263 (1) References 4, 6, and 7 are studies done at Aberdeen Proving Grounds in the early 1970's. The purpose of the three studies was to prove the agents GB and VX could successfully be destroyed by incineration. In all three cases operating temperatures exceeded the 1000°F standard by a minimum of 300°F. The reactor residence time, however, was of the order of one second or less. At these operating conditions the agent destruction was better than 99.9% consistently. (2) The aforementioned studies referred to previous work done by Baier and Weller (reference 28) and work done by Reeves and Kurtz (reference 29) on the thermal destruction of the chemical agent GB. The range of operating conditions for this work were 750°F to 1200°F and residence times of 0.13 sec to 2.7 sec. Two approaches to the thermal destruction of GB were investigated; thermal decomposition in a nitrogen atmosphere and catalytic oxidation. The results are presented in Table 1 [Table 1 of the original memorandum is not included here.]. Baier and Weller determined from their data that the decomposition of GB follows first order kinetics. Based on their work, calculations predict a detoxification of 99.99% in 0.1 sec at 1000°F. b. Hot Air Decontamination Studies. The topic of hot air decontamination could not be fully reviewed given time and resource constraints. The information presented in reference 22 indicates the relationship between surface temperature and agent removal has been investigated. Agent removal of 99% or better has been achieved with surface temperatures of 500°F for 90 seconds. Further investigation of the hot air decontamination studies is required to determine to what extent they support the 5X criteria. 4. 5X Criteria Evaluation. A limited number of studies that test the Army's standard for 5X decontamination has been done. The studies completed to date conclusively support the 5X criteria. The most comprehensive work was done by Southern Research Institute (SoRI) (a subcontractor to General Atomics) in support of the cryofracture/incineration development program. Prior to the SoRI study, testing was conducted on the thermal detoxification of M55 Rockets. Brief synopses of these studies follow. a. M55 Rocket Tests. The objective of this study was to verify that samples of the M55 rocket immersed in agents GB and VX can be detoxified at 1000°F and to determine the required residence time. (1) Test Procedure. Representative sections of the aluminum warhead and the fiberglass reinforced plastic (FRP) launch robe were immersed in either GB or VX and heated to 1000°F. The GB samples were
H EXCERPT FROM THE U.S. ARMY'S 5X DECONTAMINATION REVIEW 264 maintained at 1000°F for periods of 1, 3, 5 and 15 minutes. The VX samples were maintained at 1000°F for periods of 2 and 15 minutes. After the constant temperature period the samples were isolated and a set of two bubblers were used for agent detection. The minimum detectable levels for GB and VX using this method are 0.625 à 10-4 mg/m3 and 0.125 à 10-4 mg/m3, respectively. The results for each agent type will be discussed individually. (2) VX Results. No VX was detected for samples with residence times of either 2 or 15 minutes. These results indicate the 5X criteria is adequate for VX. (3) GB Results. Residence time of 5 minutes or less were determined to be inadequate for the detoxification of GB. In each case one bubbler detected GB at concentrations several times above the detectable level, while the second bubbler was below the detectable level. No agent was detected after a residence time of 15 minutes. The results indicate a 15 minute residence time is adequate for the detoxification of GB. The minimum time of 5X decontamination of GB contaminated items cannot be determined from the M55 rocket study since no times between 5 and 15 minutes were tested. b. SoRI Work. The study conducted by SoRI includes a literature review and laboratory scale studies. General Atomics also wrote a 5X Thermal Task Report evaluating the literature review and the laboratory studies performed by SoRI. (1) Literature Review. The literature reviewed by SoRI were studies of the thermal decomposition of chemical agents GB, VX, and HD. The topics reviewed include the mechanism for decomposition, the kinetics of decomposition, and the decomposition products. The most important information presented in the review are the actual test results and the time versus temperature predictions based on analysis of the data. The findings concerning each chemical agent will be discussed individually. (a) The chemical agent GB has been more extensively studied than the other chemical warfare agents. A study as early as 1954 by Reeves and Kurtz resulted in the 100% decomposition of GB at 560°C (1040° F) in 1.08 seconds. Predictions based on the kinetic work preformed by Baier and Weller indicate complete decomposition of GB can be accomplished at 395°C (743°F) in 1.3 seconds. The data presented and the predictions from the kinetic analysis all support the 5X criteria.
H EXCERPT FROM THE U.S. ARMY'S 5X DECONTAMINATION REVIEW 265 (b) A limited number of studies has been devoted to the thermal decomposition of the chemical agent VX. The studies reviewed by SoRI are inconclusive. Inadequate residence times (on the order of milliseconds) resulted in incomplete decomposition. At no temperature was the percent of VX decomposition greater than 71.8%. No predictions based on kinetic analysis were presented. The data presented is insufficient to make a supportive case for the 5X criteria. (c) Several studies have been performed on the thermal decomposition of HD. The main emphasis of a large portion of the work was determining the decomposition products of HD; however, some work was done on the time versus temperature relationship for decomposition. All the actual data presented are at temperatures of 400°C (752°F) or lower and residence times less than 0.5 seconds. At 400°C and 0.41 seconds 98.5 to 98.8% of the HD is decomposed. Based on the data collected, the decomposition of HD would be complete after 2.2 seconds at 400°C. The data presented substantiates the 5X criteria. (2) Laboratory Studies. The SoRI laboratory studies involved the pyrolysis of the chemical agents GB, HD, and VX. The tests were developed to simulate worst case conditions of agent being trapped in a confined space such as a crack of crevice. A quantity of agent was confined in a closed reaction vessel and the reaction vessel placed in a furnace. The operating temperature ranged form 330°C (626°F) to 660°C (1220°F), and the residence time varied from 0 to 60 minutes. The reaction vessel was submerged in liquid nitrogen to stop any further decomposition and the quantity of residual agent was determined. The results for each agent will be discussed individually. (a) GB Results. A definition of residence time is necessary to discuss the GB test results as well as the other agent tests. The residence time, for this study, is the time the reaction vessel spends in the furnace. There has been no adjustment for a heat up period of the reaction vessel, although the cool down period is not included in the residence time. The data for the GB tests are presented in Table 2 [Table 2 of the original memorandum not included here.]. The vessel temperature was never maintained at exactly 583°C (1000° F). At a furnace temperature of 549°C (1020°F) and a vessel maximum temperature of 498°C (928°F) a 99.998% destruction of GB was attained in 10 minutes. A plot of the data at furnace temperatures of 549° C and 457°C is provided in Figure 1 [Figure 1 of the original memorandum not included here.]. An extrapolation of the time versus GB found curves indicates complete GB destruction after 15 minutes at either temperature. The data, although not collected at 1000°F, indicate the 5X criteria is valid for GB.
H EXCERPT FROM THE U.S. ARMY'S 5X DECONTAMINATION REVIEW 266 (b) VX Results. The data for VX tests are presented in Table 3 [Table 3 of the original memorandum not included here.]. At furnace temperatures of 554°C (1029°F) and 618°C (1144°F) the maximum vessel temperatures approach the 1000°F criterion. The two points of most interest are a maximum vessel temperature of 514°C (957°F) and of 527°C (981°F). The residence times for these temperatures are 7 and 5 minutes respectively, and the percent destruction are 99.9988 and 99.9942, respectively. Plots of the time versus VX found at various temperatures are presented in Figure 2 [Figure 2 of the original memorandum not included here.]. Extrapolation of the course of the curves at furnace temperatures of 460°C (860°F), 554°C (1029°F), and 618°C (1144°F) to a time of 15 minutes indicates essentially complete destruction of VX. These results indicate the 5X criteria is valid for the agent VX. (c) HD Results. The data for the HD tests are presented in Table 4 [Table 4 of the original memorandum not included here.]. The results of the HD tests are far less conclusive than the results for the VX and GB. The sampling techniques were inadequate to measure quantifies of HD below 80 micrograms, only confirming agent destruction to 99.6% of the HD samples. This level of destruction was achieved at residence times as short as 6 minutes and maximum vessel temperatures as low as 320°C (608°F). Although the data does not conclusively Confirm the 5X criteria for HI), the data does strongly support the criteria. 4. 5X Testing. a. A 5X testing program is currently on going at the Chemical Agent Munitions Disposal System (CAMDS). The effort is directed towards proving out the capability of the Metal Parts Furnace (MPF) to accomplish 5X decontamination. Simulant tests have been run and the indication is that the 5X criteria can be met by the MPF. A shielding system has been developed to more uniformly heat ton containers and thereby relieve a problem overloading the system due to rapid vaporization of the simulant. Additional simulant test will be run in late April or early May 1989 prior to any agent testing. b. The Johnston Atoll Chemical Agent Destruction System (JACADS) furnaces will be subjected to 5X decontamination validation during systemization. These tests will be conducted in FY1989-1990.
H EXCERPT FROM THE U.S. ARMY'S 5X DECONTAMINATION REVIEW 267 5. Conclusions. a. Background information in the areas of agent incineration, agent thermal decomposition, and hot air decontamination provide an experimental and theoretical basis for the 5X decontamination criteria. b. A limited amount of testing has been performed specifically directed at proving the current 5X criteria are valid. The testing which has been done strongly supports the 5X criteria. c. The current CAMDS MPF test programs have, to date, demonstrated the capability to maintain the temperature and time criteria of 5X decontamination. Further CAMDS and JACADS testing will provide increased confidence in the criteria. 6. The point of contact for the action is Mr. Donald Macfarlane, extension 2514/2361. 7. encls BARBARA A. KURYK Chief, Process Development Branch
