PROTECTION OUT TO 10 MILES Mr. HOLIFIELD. Could you furnish to the committee a graduated scale showing the protective value of quonset-type hut shelters buried 3 feet underground, at the top part of the arch; also the same type of a scale showing the additional protection that 1 foot of concrete would give over that type of a structure, and graduate that on the basis of 10 miles from the ground zero of a ground burst. Will you furnish us a table along that line? Mr. CORSBIE. Yes, sir. Mr. HOLIFIELD. You have data which will allow you to do that, do you not? Mr. CORSBIE. I think we have, sir. Mr. HOLIFIELD. Thank you. And give us the pounds per square inch of pressure, the amount of thermal exposure, and the amount of radiation exposure which people would have in a graduated range from zero out to 10 miles in the event of a megaton burst. Mr. CORSBIE. Yes, sir. (The following information subsequently was received:) PROTECTION AGAINST NUCLEAR EFFECTS AFFORDED BY AN UNDERGROUND The protection afforded by an underground, corrugated metal arch shelter under two coverings is considered. In case I the cover consists of a minimum of 3 feet of earth; in case II the cover consists of a minimum of 3 feet of earth plus a 1-foot-thick slab of standard concrete. In estimating the protection afforded by such shelters, it is assumed that the entrances, exits, vents and other openings provide protection against ionizing radiation, thermal radiation and blast consistent with the basic structure. A metal arch shelter designed to withstand 35 pounds per square inch overpressure is described in reference 1. A report on field tests in which the shielding afforded by a minimum of 3 feet of earth was determined is contained in reference 2. Radiation attenuation factors for the shelter with a minimum of 3 feet of earth over the crown of the arch are of the order of 1,250 for initial ionizing radiation and 10,000 for fallout radiation. Attenuation factors for the same shelter with a minimum of 3 feet of earth over the crown of the arch plus 1 foot of standard concrete are of the order of 4,000 for initial ionizing radiation and greater than 200,000 for fallout radiation. Assuming that a war emergency radiation dose of 100 roentgens may be accepted as a nondisabling injury, outside doses of initial radiation of 125,000 roentgens and 400,000 roentgens would not cause disabling injury inside of the two shelters having attenuation factors of 1,250 and 4,000, respectively. Initial ionizing radiation doses of 100,000 roentgens and higher will be observed in regions where blast pressures will destroy all but especially constructed buildings. A fallout radiation attenuation factor of 10,000 will provide excellent protection against fallout radiation. An early time dose rate such as 10,000 r/hr at H+1 hour would be reduced to 1.0 r/hr. During a 2-week period the accumulated dose would be less than 5 roentgens. Attenuation factors greater than 10,000, as seen in case II, would result in much lower inside dose rates and lower accumulated doses. The shelter described in reference 1 was designed to withstand a blast pressure of 35 pounds per square inch. The protection against radiation afforded by both the earth and the earth plus concrete coverings is satisfactory at the 35p.s.i. range from surface burst weapons having yields from 1 to 10 megatons. A 35-p.s.i. shelter at a distance of 2 miles from the point of detonation will withstand the initial ionizing radiation, thermal radiation, and the blast from surface bursts from 1 to 8 megatons. At 2 miles from a 9-megaton surface burst (40 p.s.i.) and 2 miles from a 10-megaton surface burst (44 p.s.i.) some damage may occur to the shelter. The 35-p.s.i. shelter will withstand the effects 1 mile from a 1-megaton surface burst. Some structural damage is expected at 1 mile from a 2-megaton surface burst where the overpressure will be about 64 p.s.i. At 1 mile from a 3megaton surface burst where the overpressure will be about 90 p.s.i. structural damage to the shelter is expected. At 1 mile from surface bursts of 4 to 10 megatons the overpressures will be greater than 100 p.s.i. It is anticipated that there will be no appreciable damage from ground shock to a well-constructed underground shelter beyond 21⁄2 apparent crater radii from surface zero. For a 1-megaton surface burst, 21⁄2 apparent crater radii equal about one-half; for a 10-megaton surface burst, 21⁄2 apparent crater radii equal about 1.1 miles. (Both examples are for wet soil in which the largest apparent craters are produced.) At 21⁄2 crater radii from 1- to 10-megaton surface burst weapons, overpressures would exceed 100 p.s.i., which exceeds the design resistance of the 35-p.s.i. shelter. Inasmuch as the 35-p.s.i. is well beyond the range of 21⁄2 apparent crater radii, structural damage from ground shock should not be expected, although ground shock would be felt by the occupants of a 35-p.s.i. shelter at the 35-p.s.i. range. At such ranges and pressures slight to moderate accelerations and ground roll may occur. Depending on soil characteristics, some attention should be given to protection of shock-sensitive equipment and possible hazards to personnel from displacement and overturning of shelter fittings and furnishings. The use of the 35-p.s.i. shelter for illustrative purposes should not be construed as advocating such a shelter in preference to those which would protect in regions of higher or lower overpressures. For example, a good case may be made for a shelter resistant to all effects at the 10-p.s.i. range and beyond. For a 10megaton surface burst there are about 265 square miles in the ring whose inner boundary is the 10-p.s.i. line (4.1 miles radius) and whose outer boundary is the 2-p.s.i line (10.1 miles radius). Practical design information for shelters and other structures will be found in reference 3. 1. CEX 58.7, AEC Group Shelters. REFERENCES 2. WT 1464, Operation Plumbbob Project 32.3, "Evaluation of Countermeasure System Components and Operational Procedures." 3. ASCE Manual of Engineering Practice No. 42, "Design of Structures to Resist the Effects of Nuclear Weapons," American Society of Civil Engineers, 33 West 39th St., New York City, 1961. Thermal dose at 1 to 10 miles from 1 to 10 megaton surface bursts in calories per square centimeter Initial radiation doses in rem at ranges of 1 to 10 miles from 1 to 10 megaton explosions 1 At ranges of 3 to 3.5 miles and greater initial radiation is not significant. NOTE.-Values are probably valid within a factor of 10. Overpressures in pounds per square inch at ranges of 1 to 10 miles from 1 to 10 megaton surface bursts [Values rounded off to nearest pound per square inch] 1 Maximum fireball radius is greater than 1 miles and less than 2 miles for explosions from 2.5 to 10 megatons. Mr. HOLIFIELD. Proceed. RADIATION DOSES Mr. CORSBIE. The ionizing radiations which accompany and may persist following nuclear explosions are well known for the ability to injure living things. For acute doses of penetrating radiation a report of the National Academy of Sciences-National Research Council has this to say: *** it can be stated with some confidence that total doses up to 150 to 200 roentgens delivered acutely or over days or months, would result in no apparent acute effects and serious late effects in only a small percent of those exposed. When the dose gets larger the clinical symptoms increase. A small percentage of the people receiving doses between 200 and 300 roentgens might need hospitalization; most of those receiving doses between 300 and 400 roentgens would need hospitalization; and all of those receiving doses over 400 roentgens would need hospitalization. The LD-50-that is the lethal dose for 50 percent-is often given as 450 roentgens; that is, 50 percent of the people receiving that much of a dose would not be expected to recover. Mr. HOLIFIELD. You are referring to prompt radiation there and not accumulated radiation over a period of time? Mr. CORSBIE. I am referring to acute radiation. Mr. HOLIFIELD. So the same amount of radiation received over a period of 30 days, of course, would not conform to this lethal dose rate? My question is this. You say that the lethal dose for 50 percent is 450 roentgens. The point I am making is that that refers to an acute or prompt dose of radiation. If that individual got that 450 roentgens over a period of, let us say, 10 days, it would be a different death rate, would it not? Mr. CORSBIE. This quotation refers to days or months for the total dose. And I believe experience would indicate that the longer period over which the dose is received, the less hazardous it is. Mr. HOLIFIELD. Is it not true that our experimental mammals such as mice have been able to take considerably more radiation over a period of time than they could stand in a one-shot dose? Dr. DUNHAM. May I comment on that? Mr. HOLIFIELD. Yes, Dr. Dunham. Dr. DUNHAM. The best information we have now suggests that 450 roentgens given over a period of a few seconds, hours, or several days, would pretty much have the same effect. You earlier said 30 days. Spread over a 30-day period, there would be much less effect. Mr. HOLIFIELD. In other words, you would have to thin it out a little bit in order to keep it from having its cumulative effect? Dr. DUNHAM. That is right. Mr. HOLIFIELD. That brings up the value, then, of 2 weeks, of a period of 2 weeks underground. Dr. DUNHAM. That is the important thing. Mr. HOLIFIELD. When your high radiation is in existence above the ground? Dr. DUNHAM. That is right. Mr. HOLIFIELD. And if you can protect the people during this period of rapid decay in the first 2 weeks, and they come out into an environment of 10 roentgens a day, or something like that, then you have a different situation. If they were exposed to rather heavy doses, the body can tolerate it and throw off to a certain extent its effects, due to the recuperative power of the body? Dr. DUNHAM. There is recovery which sets in almost immediately. Mr. HOLIFIELD. It gives the blood a chance to restore the corpuscles that are killed by radiation, the prompt radiation. Go ahead, Mr. Corsbie. LETHAL DOSE Mr. CORSBIE. The LD-50 is often given as 450 roentgens, that is, 50 percent of the people receiving that much of a dose would not be expected to recover. The LD-50 concept is widely used, and I sometimes believe it may be interpreted as "either you're dead or you're not." Actually the 50 percent who survive will be very ill and their recovery will be slow. Mr. HOLIFIELD. But if you step that up to 600 roentgens, then your LD rates would go up to almost 100 percent, wouldn't it? Mr. CORSBIE. It would increase. Mr. HOLIFIELD. How much would it increase? What is considered the average tolerance of the human body to prompt radiation? I know it will vary some by individuals, but what would you say, 600 roentgens-700? Mr. CORSBIE. There are great differences of opinion, and I would like to refer this to Dr. Dunham, if I may. Mr. HOLIFIELD. Dr. Dunham? Dr. DUNHAM. Certainly somewhere between 600 and 800 roentgens acute radiation exposure would be fatal to practically any individual. There might be an occasional person who would survive. Mr. HOLIFIELD. It would have more effect upon the young than the aged, would it not? Dr. DUNHAM. Not necessarily; no. Mr. HOLIFIELD. About the same effect? Dr. DUNHAM. It would depend more on the state of health of the individual. There isn't that much difference in the different age groups. Mr. HOLIFIELD. Thank you. Go ahead, Mr. Corsbie. CUMULATIVE RADIATION DOSES Mr. CORSBIE. Although acute 150- to 200-roentgen doses will result in no acute effects in the great majority of people, this is not to be construed as a license for indiscriminate exposures until the dose has been accumulated. The values do give a means for making some assumptions with respect to feasible and economical shielding against radiation. They also point out the departure from the conservative peacetime standards which would be unusable in wartime and very likely for many years thereafter. When we look at maps and diagrams of fallout patterns on which dose rates at various times are shown, we often see 1,000 roentgens per hour and other high levels indicated. After a couple of weeks the 1,000 roentgens per hour at H+1 hour will have fallen to 1 roentgen per hour or something in that neighborhood. The fact that the dose rate at 2 weeks is smaller by a factor of 1,000 does not mean that a dose rate of 1 roentgen per hour is nothing to worry about. Careful guidance from local officials and radiological know-how on the part of individuals and families will be required to minimize the effects of radiation. DAMAGE TO STRUCTURES Next I wish to add a few words about physical damage. Shelter from the weather would be important to us in wartime just as it is in peacetime, and we depend on a variety of buildings, facilities, and equipment. Inside the range at which 30 pounds per square inch would occur we |