Note by the Secretary, Subject: Radiological Safety Criteria for the Nevada Test Site

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November 13, 1956 COPY NO. :15 ATOMIC ENERGY COMMISSION RADIOLOGICALSAFETY CRITERIA FOR THE NEVADA TEST SITE Note by the Secretar~ 1, The General Manager has ~equested that the attached report by the Director of Biology and Medicine be circulated for considerationby the Commissionduring the week 2, The criteria proposed in the those referred to In AEC 944.!“Nevada Test Site Activities for Asst. Gen. Mgr. Adm, New York Operations San Francisco Oprns

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ATOMIC ENERGY COMMISSION RADIOLOGICALSAFETY CRITERIA FOR THE NEVADA TEST SITE Report to the General Manager by the pirector of BI.O1ORYand Medicine 1. To establish radiological safety criteria for exposures to gamma radiation from fallout to populations around the Nevada 2, The trend in thinking of the InternationalCommission on Radiation Protection, the National Committee on Radiation Protection, and the National Academy of Scier.ceis toward more restrictive criteria for standards of radiation protection. 3, In light of the above, it is recommendedthat radiological safety criteria for exposures to gamma radiation from fallout to populations around the Nevada Test Site should be as follows: a. The current criterion of 3,9 roentgons fOr any one year; plus an additionalrestriction of b. 10 roentgens in a period of 10 years, with the first of the successiveten-year periods starting in the spring of 1951. 4, These should be construed to be operationalguides rather than maximum permissible limits, since exposures somewhat in excess would not be hazardous. 5. The Divisions of Military Application,Information Services, Office of the General Counsel and the Office of Classificationconour in the recommendationof this paper.

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< 6, The General Manager recommends that the Atomic Energy for gamma exposures set forth in ParagraPh 3 above. of the criteria will be stated in the anno~ncementof the c. Note that operationalmean; for giving effect to the=teria in paragraph 3 above will be developed by the Test Manager and the Division of Military Applicationwith the technical guidance of the Division of Biology and Medicine. d. Note that the Joint Committee on Atomic Energy.— the GAC, and the MLC will be advised of this action by letter such as Appendix “B”* LIST OF ENCLOSURES y Draft Letter to JCAE, MI/Jand GAB,,,,...,... 6

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%,, BACKGROUND AND DISCUSSION 1. The trend in thinking of the InternationalCommission on Radiation Protection, the National Committee on Radiation Protection,and the National Academy of Science is toward more restrictivecriteria for standards of radiation protection. The National Academy of Science Report recommends, “---That for the present it be accepted as a uniform national standard that X-ray posal of radioactivewastes, experimentalinstallations,testing of weapons, and all other humanly controllablesources of radiation~ be so restricted that members of our general population shall not receive from such sources an average of more than 10 roentgens, in addition to background, of ionizing radiation as a total accumulated dose to the reproductivecells from conception to age 30.---” The NAS Report also states, “---That individualpersons not receive more than a total accumulated dose to the reproductive cells of 50 roentgens up to a,ge30 years---”. 2, The dividing line between “individualpersons” and “general population” is not distinct in the NAS Report, The numbers of people involved around the Nevada Test Site might not constitute a “general population” yet it probably would be difficult to categorizemany thousands of people as “individual persons,” Further, there is in a sense “inbreeding”within this

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3. Judging from past experienceat the Nevada Test Site, i.twould not be operationallyfeasible to limit exposures to 10 roentgens in 30 years. The situation becomes one of facing the problem frankly and in the interests of the National Defense defining the degree of risk, as the Commission has done in the past. It would appear that a reasonable figure would lie somewhat between the 10 and 50 roentgens per 30 years. The acceptable value of exposure within this range is dependent upon onels respect to the imperativeness since even the highest value I not be considereda dangerous of the indi.vidualfshealth nor of major conse4 of the nuclear exposure in terms (Fifty roentgens might double the mutation rate, but this would be for a relatively small number of persons in terms of the general population,) Based on such reasoning we are recommending that the operationalguide be arbitrarily establishedat 10 roent.gensin a period of 10 years with the first of the successive ten year periods starting in the spring of 1.951. (The date of the first nuclear tests in Nevada.) This criterion should not be construed as a maximum limit beyond which sertous effects might be expected, but rather it should be thought of as an operational 4. The operationalfeasibility of 10 roentgens may be estimated by noting that during the five years at Nevada Test Site the highest total accumulated’exposure to any community has been about four and one-half roentgens (about 15 people living at a motor court received about seven to eight roentgens). This might suggest a degree of ease in meeting the criteria that does not in fact exist. The relatively low exposures are the result of the most exacting plans and procedures for

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conducting the tests including many long delays until weather conditionswere favorable. The permissiblesectors and distances around NTS for deposition of relatively heavy fallout are limited, thus requiring a continuationof strict criteria in the timing’ of the detonations. The use of higher towers, surfaced areas around ground zero, and the possible use of balloons for suspending the nuclear devices as well as other methods of detonation under consideration,should assist in reducing the fallout outside the Nevada Test Site. Unlike accumulationof doses by small increments (as in energy installation)providing opportunity for preventive established limits are approached, the occurrence of fallout on a community can be a quanta event and once it has occurred certain exposures will ensue unless rather drastic action such as evacuation is taken. Therefore, operationalrequirements would indicate a relatively large radiation exposure guide for a single year. The criterion of 3.9 roentgens per year has been in effect, widely reported by the Atomic Energy Commission and used in educational programs with the people around the NTS. Therefore, in the absence of any compelling reason to the contrary, It i~- recommended that this criterion be retained. As with the criterion of 10 roentgens in 10 years, it should be made clear that 3,9 roentgens per year is an operationalguide, and exposures somewhat in excess of this should not be construed as being hazardous. 6. The method of estimating the gamma doses shall be according to AEC 141/15 (as possibly amended, following re-. evaluation of the relevant data), radiologicalsafety criteria procedures for protecting the public during weapons testing at Nevada Test Site.

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1. The trend in thinking of the InternationalCommission on Radiation Protection, the National Committee on Radiation Protection, and the National Academy of Science is toward more restrictive criteria for standards of radiation protection. 2. In keeping with this philosophy the Atomic Energy Commission has recently app?oved an additionalrestrictive criterion for exposure to gamma radiation from fallout to populations around the Nevada Test Site, To the current criterion of 3.9 ro.entgensfor any one year which will be retained, there will be an additional restriction of 10 roentgens in a period of 10 years, with the first of the successive10-Year periods starting in the spring of 1951 (the date of the first nuclear series at the Nevada Test Site). 3. These criteria are construed as operationalguides rather than maximum permissible limits since exposures somewhat in excess of these values would not be consideredhazardous.