ATTACHMENT 6 Operation Jangle Project 6.3-2 Evaluation of the Potential Respiratory Hazard to Tank Crews Required to Operate in Contaminated Areas by Elmer H. Engquist July 1952 Chemical and Radiological Laboratories Army Chemical Center, Maryland Preface This report covers work conducted under Operation Jangle Project 6.3, "Evaluation of Protective Equipment", John R. Hendrickson, Project Officer. The work at the test site was coordinated and conducted under the direction of the author. The cooperation of many Chemical Corps individuals, too numerous to mention by name, assigned to the above projects contributed to the accomplishments of the objectives of this study. In addition, an Ordnance Test team, directed by Captain David W. Armstrong and Mr. Norman Arnold, Ballistics Research Laboratories, Aberdeen Proving Ground, Maryland, and an Army Field Forces Board No. 2 Test Team, directed by Lt. Col. John S. Sandiland, provided the Secretary support in the operation of the M-26 tanks and the Personnel Carrier, (illegible). Each group provided many valuable suggestions and direction to the author. The assistance of Pfc John Sweeney was particularly valuable to the author in carrying out the installation of test apparatus and the tank collective protectors in the vehicles. - iii - Project 6.3-2 Contents Preface ............................................iii Abstract ............................................ix Chapter 1 Introduction ..............................1 1.1 Objective ...................................1 1.2 Authority ...................................1 1.3 Historical ..................................1 1.4 Theoretical .................................2 Chapter 2 Experimental ...............................4 2.1 Instrumentation .............................4 2.2 Vehicles ....................................4 2.2.1 M-26 Tank .............................4 2.2.2 Personnel Carrier (illegible) .........4 2.3 Exposure Position of Vehicles ..............4 2.3.1 During Shot ...........................4 2.3.2 ......................................6 Chapter 3 Results ....................................8 3.1 Airborne Activity Level in Vehicles During Underground Shot ............................8 3.2 Airborne Activity Level in Vehicles During Test Run ....................................8 Chapter 4 Discussion ..................................11 4.1 Variation of Airborne Activity ..............11 4.2 Factors Affecting Application of Data .......11 4.3 Factors by Which Measured Airborne Concentration Exceed Maximum Allowable Concentrations ......12 4.4 Evaluation of the Potential Hazard ..........13 Chapter 5 Conclusions and Recommendations ............14 5.1 Conclusions .................................14 5.2 Recommendations ............................14 Appendix A Maximum Allowable Concentrations of Fission Products in the Air As A Function of Exposure Time and Time After Detonation .........16 - v - Project 6.3-2 Appendix B Maximum Allowable Concentrations of Fission Products in the Air As a Function of Exposure Time and Time After Detonation (continued) ....29 Illustrations Chapter 1 Experimental 2.1 Chemical Corps Filter Sampler ................5 2.2 Chemical Corps Filter Sampler Installations on the M-26 Tanks .............................5 2.3 Chemical Corps Filter Sampler Installation in M-26 Tank ...................................6 2.4 Areas of Operation of Vehicles in Contaminated Areas ........................................7 Appendix A Maximum Allowable Concentrations of Fission Products in the Air As a Function of Exposure Time and Time After Detonation A.1 Maximum Permissible Concentrations of Fission Products in the Air - 1 hr to 1000 hr ...21 A.2 Maximum Permissible Concentrations of Fission Products in the Air - 10 hr to 1 yr ...22 A.3 Maximum Permissible Concentrations of Fission Products in the Air - 1 hr to 1000 hr..25 A.4 Maximum Permissible Concentrations of Fission Products in the Air - 10 hr to 1 yr....26 Appendix B Maximum Allowable Concentrations of Fission Products in the Air As a Function of Exposure Time and Time After Detonation (continued) B.1 Maximum Permissible Concentrations of Fission Products in the Air - 1 hr to 1000 hr...38 B.2 Maximum Permissible Concentrations of Fission Products in the Air - 10 hr to 1 yr......39 - vi - Project 6.3-2 Tables Chapter 3 Results 3.1 Airborne Activity Level in Armored Vehicles ...(illegible) 3.2 Airborne Activity Level During Armored Vehicle Test Run ..................................... (illegible) Chapter 4 Discussion 4.1 Factors By Which Measured Airborne Concentration Exceeds Maximum Allowable Concentrations .....12 Appendix A Maximum Allowable Concentrations of Fission Products in the Air As a Function of Exposure Time and Time After Detonation A.1 Maximum Permissible Concentrations of Various Elements in the Atmosphere for Continual Exposure ................................17 A.2 Concentration of Sr90 in air necessary to cause retention in the human body 1 micro- curie (cr 2 microcuries of 3r90-illegible, since they are parent and daughter in stable equilibrium (during the following periods of time, based on the absorption and permanent retention of (illegible) of the activity ..18 A.3 Maximum Permissible Fission Product Concentration............................20 A.4 Analysis (illegible) ....................23 A.5 Maximum Permissible Fission Product Concentration ...........................24 Appendix B Maximum Allowable Concentrations of Fission Products in the Air As a Function of Exposure Time and Time After Detonation (Continued) B.1 Concentrations in the air necessary for retention in the human body of 1 microcurie of (illegible) (illegible) based on 100% inhalation, 25% absorption of the material inhaled, and 25% retention of the absorbed material ............33 - vii - Project 6.3-2 B.2 Maximum Permissible Fission Product Concentrations ..........................32 B.3 Analysis Sheet ..........................34 B.4 Maximum Permissible Fission Product Concentrations ..........................35 - viii - Project 6.3-2 Abstract The objective of this investigation was to assess the inhalation hazard to armored vehicles crews during the exposure to an underground and surface detonation of an atomic weapon and during operation, following the detonation, of the armored vehicles within the contaminated area resulting from fall-out. Two types of armored vehicles were employed in this study, two Medium Tanks, M-26, and one Personnel Carrier, (illegible) Pilot Model No. 5 During the surface shot only the two tanks were exposed 2000 ft. in an upwind direction from ground zero and operation to within approximately one-tenth mile of ground zero. No contamination area was traversed during this operation since the fall-out was restricted to a long narrow corridor in the downwind direction. During the underground shot all three vehicles were exposed at 2000 ft. in a downwind direction in an area contaminated to a level of approximately 550 (illegible)/hr. at (illegible). One tank was exposed head-on, with hatches open, one tank side-on with hatches closed, and the Personnel Carrier, head-on with the commander's and driver's hatches open. Following the shot at (illegible) + 50 hr., after contamination, the vehicles were operated with one tank leading with hatches open, and the other vehicles following with hatches closed, up to and beyond the crater lip and return. During both exposure of the vehicles during the underground shot and operation through the contaminated area the airborne activity exceeded by a large degree the maximum allowable concentrations established by the Department of Defense and the U.S. Atomic Energy Commission for lifetime exposure. Preliminary to this operation a study was made to develop a basis for short-time exposure to airborne activity without exceeding the maximum allowable concentrations retained within the body. This study is appended to this report. The activity level measured exceeded the standards for eight hour exposure by a factor of 10 to 300. There is thus a potential respiratory hazard during the initial 24 hour period to armored vehicle crews not wearing protective masks. The degree of this hazard can not be firmly established due to the lack of definitive medical data on the result of this exposure. ix However, adequate protection can be provided to armored vehicle crews through the use of protective masks, and/or, tank collective protectors, and their use in similar situations is recommended. Project 6.3-2 It is further recommended that results of this study be applied to the development of the overall hazard only after adequate consideration for the external dose to which personnel would simultaneously be exposed. - x - Chapter 1 Introduction 1.1 Objective The objective of this investigation was to assess the inhalation hazard associated with (1) exposure of armored vehicles to an underground and surface detonation of atomic weapons, and, (2) operation of armored vehicles through areas contaminated with fission products resulting from fall-out from such detonation. 1.2 Authority the study on armored vehicles was conducted under Operation Jangle Project 6.3, "Evaluation of Protective Equipment". The personnel carrier was included in accordance with first Indorsement, G4/F4/(illegible), dated 24 October 1951, from Office, Ac/S, (illegible), Department of Army, to Chief Chemical Officer, D/A, on basic letter from Office, Chief of Army Field Forces, Fort Monroe, Virginia, subject: "Atomic Weapons Effects Testing". 1.3 Historical Previous atomic weapons test, with the exception of Test Baker at Operation Crossroads were detonated as low air (illegible) or detonated on towers. Thus, they were essentially of the non-contaminating type of burst since a major fraction of the fission product activity rose with the cloud and was diluted in the atmosphere. On 5 June 1950 the Joint Chiefs of Staff directed that underground and surface tests of nominal (20-30 kiloton) atomic weapons be conducted. As a result the Department of Defense through the Armed Forces Special Weapons Project established Operation Windstorm to be conducted on (illegible) in the Aleutian Islands. Subsequently, this operation was canceled because of unfavorable test conditions of weather and terrain. The tests were then rescheduled as Operation Jangle for conduct with scaled atomic weapons, of approximately 1.25 kiloton yield, at the Nevada Proving Ground, U.S. Atomic Energy Commission, Mercury, Nevada. the surface test was detonated on 19 November 1951. - 1 - Project 6.3-2 1.4 Theoretical The maximum permissible concentrations of radioactive isotopes in air have been established by the U.S. atomic Energy Commission as standards for the control of radioactive materials in laboratories using such isotopes1,2. These concentrations are stipulated to constitute no hazard to personnel engaged in isotope work on a lifetime basis. No standards are available for guidance of military operations in contaminated areas. It is a logical assumption that such operations are conducted with consideration of the hazards of such operations and acceptable risks will be taken where necessary for the accomplishment of the mission. Thus, such operations should only be conducted after assessment of the potential hazard and with adequate consideration of the risk. In military operations in contaminated areas it is expected that exposures will not be guided by standards established on the basis of lifetime exposure but rather on one-site, or at best a few, exposures to the hazard. A study was made prior to Operation Jangle to provide such a basis for military exposure. The calculations of Hunter and Ballou were used to furnish individual and total beta activities for fission products at various times between 1 hr. and 1 yr. after detonation. Then the concentration in air necessary to cause the deposition and retention of the maximum permissible amounts of (illegible) was calculated for several times after detonation, and for various exposure times. Each of the other fission products considered hazardous was then compared at several times to (illegible) on the basis of relative activity and toxicity. The possibility that "Bad factors" might appear as decay products of active material already in the body was considered. The estimated were made of their radio-toxicity relative to Sr90. This relative value was called the "Sr90 equivalent". The concentrations necessary to cause retention of 1 Sr90 equivalent at various times were calculated and a graph prepared showing maximum permissible concentrations of fission products from 1 hr. to 1 yr. after detonation for various exposure times. This study results in the development of a much higher maximum permissible concentration then those set for long term exposure.3. __________________________________________________________________ 1. Handbook of Atomic Weapons for Medical Officers, Prepared by Armed forces Special Weapons Project, Department of Army Handbook 8-11, June 1951. 2. Subcommittee on Internal Dose of the National Committee on Radiation Protection, "Maximum Permissible Concentrations of Radioisotopes in the Air, Water, and in the Human Body". (1951) 3. (Illegible) 64 "Maximum Allowable Concentration of Fission Products in the Air as a Function of Exposure Time and Time After Detonation". - 2 - Project 6.3-2 This study was further extended with modifications of the assumptions, refinement of the calculations, and consideration of the plutonium hazard. This study developed even higher concentrations than the initial study4. The reports are included as Appendices A and B. ___________________________________________ 4. CRLIR 81 "Maximum Allowable Concentration of Fission Products in the Air as a Function of Exposure Time and Time After Detonation (Continued)". - 3 - Chapter 2 Experimental 2.1 Instrumentation To determine the airborne activity in the vehicles, and on the exterior of the vehicles, a Chemical Corps filter sampler was used. This device samples approximately one (illegible) of air through a 100 sq cm sheet of Chemical Corp. Type 6 filter material backed up with two sheets of Chemical Corps Type 5 filter material for support. This unit is shown in Fig. 2.1. The units were operated for one hour starting at five minutes prior to the shot. 2.2 Vehicles 2.2.1. M-26 Tank The filter sampler was installed in the bow between the driver and assistant driver, in the turret ahead of the (illegible) seat, and on the outside fender of the tank. These installations are shown in Fig. 2.2. and Fig. 2.3. 2.2.2. Personnel Carrier T18E1 The filter sampler was located in the crew compartment only in this vehicle. 2.3 Exposure Position of Vehicles 2.3.1. During Shot During the surface shot the two medium tanks, M-26, were located 2000 ft, 15 degrees east of south, from ground zero. One tank was located head-on, and one side-on, to ground zero. This location was upwind of the area of contamination and little, if any, significant fall-out occurred at the location of the vehicles. The principle evaluation for the purposes of this report was conducted on the underground shot. The three vehicles were located at 2000 ft from ground zero in the fall-out direction. This area was contaminated. - 4 - For Reference See (3pm30.gif) - 5 - For Reference See (3pm31.gif) - 6 - For Reference See (3pm32.gif) - 7 - Chapter 3 Results 3.1 Airborne Activity Level in Vehicles During Underground Shot The data on airborne beta activity level in vehicles are given in Table 3.1. The samples were taken for 55 minutes following the shot and the counting data were arbitrarily corrected to H-hr + 1 hr by means of the decay equation for gross fission products, A = A(illegible), where the decay exponent was taken as 1.48.This was the experimentally determined value on the samples. Activity levels collected by the samples varied randomly with location within the vehicles from 0.17 to 0.45 millicuries per liter of air. the following averaged concentrations were obtained for the three vehicles. Vehicle Millicuries/Liter M-26 Tank - Hatches Closed 0.23 M-26 Tank - Hatches Open 0.27 T18E1 Personnel Carrier 0.28 3.2 Airborne Activity Level in Vehicles During Test Run Following The Underground Shot The data shown in Table 3.2 were obtained during the test run following the underground shot through the contaminated area to the crater lip and beyond, and return, as shown in Fig. 2.3. - 8 - Project 6.3-2 Table 3.1 Airborne Activity Level in Armored Vehicles Vehicle Location Activity Sampling Sampling Activity/ (mc) Time Volume Liter (min) (1/min) (mc/liter) ___________________________________________________________________ M-26 Tank Turret 12.2 60 1.23 0.17 424-S M-26 Tank Hull 21.2 60 1.08 0.33 424-S M-26 Tank Outside 11.0 60 0.95 0.19 424-S Average Concentration .................................0.23 M-26 Tank Turret 30.6 60 1.12 0.25 418-S* M-26 Tank Hull 13.0 60 1.23 0.18 418-S* M-26 Tank Outside 14.0 60 1.28 0.18 418-S* Average Concentration..................................0.27 Personnel Personnel 19.4 60 1.15 0.28 Carrier Comp't T18E1 _________________________________________________________________ *Hatches Open - 9 - Project 6.3-2 Table 3.2 Airborne Activity Level During Armored Vehicle Test Run * Vehicle Location Activity Sampling Sampling Activity/ (mc) Time Volume Liter (min) (1/min) (mc/liter) ___________________________________________________________________ M-26 Tank Turret 2.63 23 1.12 0.102 418-S M-26 Tank Hull 1.0 23 1.23 0.035 418-S M-26 Tank Outside 0.12 23 1.28 0.004 418-S Average Concentration..................................0.066 M-26 Tank Turret 0.48 23 1.23 0.017 424-S M-26 Tank Hull 9.0 23 1.08 0.362 424-S M-26 Tank Outside 1.2 23 0.95 0.055 424-S Average Concentration..................................0.18 Personnel Personnel 1.0 23 1.15 0.038 Carrier Comp't T18E1 _________________________________________________________________ *M-26 Tank 424-S was the lead vehicle, hatches open, followed by the M-26 Tank 418-S, and the Personnel Carrier, T18E1, hatches closed. - 10 - Chapter 4 Discussion 4.1 Variation of Airborne Activity It is considered significant that the airborne activity does not appear to vary markedly with the operational condition of the tanks, that is, whether the vehicle hatches are open or closed during the period of exposure. This is clearly indicated by the data given in Section 3.1. It was further indicated immediately after removal of the sampling papers from the test samplers when the papers were monitored by survey meters at H-hr + 70 hrs before shipment to the Army Chemical Center for detailed analysis. The measured activity on the papers at that time varied from 7 to 35 mr/hr at 6 in. from the samples. During the test run through the contaminated area following the underground shot it is to be noted that there was no significant difference in activity in the lead vehicle as opposed to the two following "Buttoned up" vehicles, with ventilating system operating. This strong indication that the major portion of the airborne material within the vehicle was a secondary aerosol created from contamination within the vehicle itself. 4.2 Factors Affecting Application of Data Before applying the results of this investigation to an assessment of inhalation hazard associated with airborne radioactive material to armored vehicle personnel there additional factors should be considered. First it should be emphasized that no effort was made to limit the spectrum of particle size range for lung retention. The particle size for retention has an upper limit of 10 microns, and more probably 3 microns. Data developed by Operation Jangle Project 2.51, Airborne (illegible) Studies, indicate that less than 10 percent of the total airborne activity is in the inhalation hazard size range of 0.5 to 5.0 micron5. Second, the protective measures available to personnel must be considered. The gas mask, or more specifically for armored vehicle crews, the Tank Collective Protector, (illegible), has an extremely high efficiency for the removal of gross fission product contaminant associated with the cloud and (illegible) surge created by an underground detonation.6 _________________________________________ 5. Letter to, Office of the Director, Effects Test, c/o Technical Operations Squadron (Prov), Washington 13, D.C., From Co. (illegible) C Chemical and Radiological Laboratories, Army Chemical Center, Md., dated 18 April 1952. 6."Evaluation of Protective Equipment", Operation Jangle Project 6.3, John H. Hendrickson, Army Chemical Center, Maryland. - 11 - Project 6.3-2 The average concentration of these units by radioactive particles was measured at (illegible) percent, that is, 1.8 parts in 10,000 pass through the tank collective protector filter unit. Third, the time of exposure must be considered. For short-term exposure, if one accepts the assumptions as outlined in Appendices A and B which provide the basis for calculation of short-term exposure to gross fission products, 6 hr exposure to 0.1 to 0.0035 microcuries per liter of gross fission products can be tolerated during the period of H + 1 hr to H + 1 day. This time of exposure was the shortest considered in the analysis and, since tank crews generally could be expected to be exposed for even shorter periods than 6 hrs during operations within contaminated areas, they could tolerate slightly higher levels of airborne contamination. 4.3 Factors by Which Measured Airborne Concentration Exceed Maximum Allowable Concentrations The concentrations given in Table 3.1 and 3.2 allowing for the 10 percent size range factor, exceed the maximum allowable concentrations given in Appendices A and B, as given in Table 4.1 Table 4.1 Factors by Which Measured Airborne Concentration Exceed Maximum Allowable Concentrations Time of Maximum Allowable Measured Concentration Factor by Which Exposure Concentration Maximum Minimum by Measured Value uc/1 uc/1 uc/1 Exceeds Max. (for 8 hr Exp.)1 Allowable Conc. Maximum Minimum ______________________________________________________________________ H + 24 hr 0.0035 0.252 0.034 72 10 H + 1 hr 0.1 28. 3.1 280 38 _______________________________________________________________________ 1. Appendices A and B - 12 - Project 6.3-2 4.4 Evaluation of the Potential Hazard Thus, unprotected Personnel would be exposed to concentrations exceeding the maximum allowable concentration for (illegible)hr exposure to a factor of 10 to (illegible), and there is thus a requirement for tank personnel to wear protective masks when operating within contaminated areas. Such protective masks would probably be worn for comfort purposes under any conditions, if available, under dusty conditions such as were encountered at the Nevada Proving Ground. Wearing protective masks, with penetration of 2 parts in 10,000, and considering that 10 percent of the activity is in the respiratory size range, the concentrations inhaled are well below the maximum allowable concentration for eight hourexposure as outlined in Appendices A and B. There thus appears to be little hazard to tank crews wearing protective masks. Without more definitive respiratory retention data, and the results of such exposure, it is not possible to determine the magnitude of the hazard to unprotected personnel. By comparison of the measured activity levels with U.S. Atomic Energy Commission and military standards for maximum permissible concentrations of radioactive isotopes in the air for lifetime exposures (which offer substantial safety factors), and by comparison with the short-term exposure limits for negligible hazard there is an exposure proven to avoid all hazards. However, the degree of the hazard present in exposure which exceeds the maximum allowable concentrations has not been established to date and therefore the magnitude of the exposure to unprotected tank personnel cannot be firmly established. - 13 - Chapter 5 Conclusions and Recommendations 5.1 Conclusions 1. Based on the data developed by this study there is a potential respiratory hazard during the initial 24 hr period to armored vehicle crews not wearing protective masks from the airborne fission product activity associated with the base surge and during the operation of armored vehicles through contaminated areas. 2. Satisfactory respiratory protection can be provided to armored vehicle crews operating in contaminated areas through the use of protective masks, and/or, tank collective protectors. 5.2 Recommendations 1. In developing the overall personnel hazard it is recommended that the results of these studies be applied only after adequate consideration for the external dose to which personnel would also be exposed. 2. It is recommended that protective masks, and/or tank collective protectors, be used in situations similar to that presented by the Operation Jangle tests. 3. It is recommended that these data be extrapolated to the condition encountered during detonations of nominal or operational atomic weapons. - 14 -