ML12338A600

Official Exhibit - ENT00284B-00-BD01 - Appendix B - Risks to Health from Radiation Doses That May Result from Nuclear Incidents

ML12338A600
Person / Time
Site:	Indian Point
Issue date:	03/29/2012
From:	Entergy Nuclear Operations
To:	Atomic Safety and Licensing Board Panel
SECY RAS
References
RAS 22120, 50-247-LR, 50-286-LR, ASLBP 07-858-03-LR-BD01
Download: ML12338A600 (94)

Text

United States Nuclear Regulatory Commission Official Hearing Exhibit ENT00284B Entergy Nuclear Operations, Inc. Submitted: March 29, 2012 In the Matter of:

(Indian Point Nuclear Generating Units 2 and 3)

ASLBP #: 07-858-03-LR-BD01 Docket #: 05000247 l 05000286 Exhibit #: ENT00284B-00-BD01 Identified: 10/15/2012 Admitted: 10/15/2012 Withdrawn:

Rejected: Stricken:

Other:

APPENDIXB Risks To Health From Radiation Doses That May Result From Nuclear Incidents

Contents Page B.1 Introduction............................................ B-1 B.1.1 Units of Dose. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. B-1 B.1.2 Principles for Establishing Protective Action Guides . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. B-2 B.2 Acute Effects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. B-3 B.2.1 Review of Acute Effects .............................. B-3 B.2.1.1 The Median Dose for Lethality ................ B-4 B.2.1.2 Variation of Response for Lethality ............ B-5 B.2.1.3 Estimated Lethality vs Dose for Man . . . . . . . . . . .. B-7 B.2.1.4 Threshold Dose Levels for Acute Effects ......... B-10 B.2.1.5 Acute Effects in the Thyroid .................. B-12 B.2.1.6 Acute Effects in the Skin ..................... B-12 B.2.1.7 Clinical Pathophysiological Effects ............. B-12 B.2.2 Summary and Conclusions Regarding Acute Effects ........ B-17 B.3 Mental Retardation ....................................... ' B-17 B.4 Delayed Health Effects .................................... B-18 B.4.1 Cancer .......................................... B-18 BA.1.1 Thyroid ................................. B-20 B.4.1.2 Skin .................................... B-21 B.4.1.3 Fetus ................................... B-21 BA.1.4 Age Dependence of Doses .................... B-22 B.4.2 Genetic Risk ........................ ~ . . . . . . . . . . . .. B-23 B.4.3 Summary of Risks of Delayed Effects ................... B-23 B.4.4 Risks Associated with Other Radiation Standards .......... B-23 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. B-25 111

Figures Page B-1 Acute Health Effects as a Function of Whole Body Dose ............ B-9 Tables B-1 Radiation Doses Causing Acute Injury to Organs ................ B-14 B-2 Acute Radiation Exposure as a Function of Rad Equivalent Therapy Units (rets) .............................. B-15 B-3 Radiation Exposure to Organs Estimated to Cause Clinical Pathophysiological Effects Within 5 Years to 0.1 Percent of the Exposed Population ..................... B-16 B-4 Average Risk of D~layed Health Effects in a Population ............ B-24 IV

APPENDIXB Risks To Health From Radiation Doses That May Result From Nuclear Incidents B.l Introduction is delivered not only at the time of intake from the environment, but This appendix reviews the risks continues until all of the radioactive from radiation that form the basis for material has decayed or is eliminated the choice of Protective Action Guides from the body. Because of the variable (PAGs) for the response to a nuclear time over which such doses may be incident, as well as the choice of limits delivered, the P AGs are expressed in for occupational exposure during a terms of a quantity called the nuclear incident. "committed dose." Conceptually, committed dose is the dose delivered over an individual's remaining lifetime B.l.l Units of Dose following an intake of radioactive material. However, due to differences The objective of protective action in physiology and remaining years of is to reduce the risk to health from life, the committed dose to a child from exposure to radiation. Ideally, one internal radioactivity may differ from would like to assure the same level of that to an adult. For simplicity, adult protection for each member of the physiology and a remaining lifetime of population. However, protective 50 years are assumed for the purpose actions cannot take into account of calculating committed doses.

individual variations In radiosensitivity, since these are not Another important consideration is known. Therefore, these P AGs are that different parts of the body are at based on assumed average values of different risk from the same dose.

risk. We further assume that these Since the objective of protective actions risks are proportional to the dose, for is the reduction of health risk, it is any level of dose below the threshold appropriate to use a quantity called for acute effects (see Section B.2.). "effective dose." Effective dose is the sum of the products of the dose to each The dose from exposure to organ or tissue of the body and a radioactive materials may be delivered weighting factor representing the during the period of environmental relative risk. These weighting factors exposure only (e.g., external gamma (IC-77) are chosen as the ratio of radiation), or over a longer period (e.g., mortality (from delayed health effects) inhaled radionuclides which deposit in from irradiation of particular organs or body organs). In the latter case, dose tissues to the total risk of such B-1

mortality when the whole body is separately considered, when it is irradiated uniformly at the same dose. appropriate; in establishing values for the PAGs.

Finally, doses from different types of radiation (e.g. alpha, beta, gamma, and neutron radiation) have different B.1.2 Principles for Establishing biological effectiveness. These Protective Action Guides differences are customarily accounted for, for purposes of radiation protection, The following four principles by multiplicative modifying factors. A provide the basis for establishing dose modified by these factors is values for Protective Action Guides:

designated the "dose equivalent." The P AGs are therefore expressed in terms 1. Acute effects on health (those that of committed effective dose equivalent. would be observable within a short The PAGs are augmented by limits for period of time and which have a dose a few specific organs (skin and thyroid) threshold below which they are not which exhibit special sensitivity. These likely to occur) should be avoided.

are expressed in terms of committed dose equivalent (rem). In the process 2. The risk of delayed effects on health of developing PAG values, it is (primarily cancer and genetic effects, necessary to evaluate the threshold for which linear nonthreshold dose levels for acute health effects. relationships to dose are assumed)

These levels are generally expressed in should not exceed upper bounds that terms of absorbed dose (rad) to the are judged to be adequately protective whole body from short term (one month of public health, under emergency or less) exposure. Other units conditions, and are reasonably (Roentgens, rem, and rets) are also achievable.

used in information cited from various references. They are all approximately 3. PAGs should not be higher than numerically equivalent to rads in terms justified on the basis of optimization of of the risk of acute health effects from cost and the collective risk of effects on beta and gamma radiation. health. That is, any reduction of risk to public health achievable at P AGs are intended to apply to all acceptable cost. should be carried out.

individuals in a population other than workers performing emergency 4. Regardless of the above principles, services. However, there may be the risk to health from a protective identifiable groups that have different action should not itself exceed the risk average sensitivity to radiation or, to health from the dose that would be because of their living situation, will avoided.

receive higher or lower doses. In addition, some groups may be* at With the exception of the second, greater risk from taking a given these principles are similar to those set protective action. These factors are forth by the International Commission B-2

on Radiological Protection (IC-84b) as of more serious pathophysiological the basis for establishing intervention effects, including death).

levels for nuclear accidents. We examine, below, the basis for estimating effects on health for use in B.2.l Review of Acute Effects applying the first two of these principles. This section summarizes the results of a literature survey of reports of acute effects from short-term B.2 Acute Effects (arbitrarily taken as received in one month or less) radiation exposure in This section provides information some detail. Many reports of observed relevant to the first principle: effects at lower doses differ, and some avoidance of acute effects on health are contradictory; however, most have from radiation. been included for the sake of completeness. The results of the Acute radiation health effects are detailed review described in this those clinically observable effects on Section are summarized in Section health which are manifested within B.2.2.

two or three months after exposure.

Their severity depends on the amount The biological response to the of radiation dose that is received. rapid delivery of large radiation doses Acute effects do not occur unless the to man has been studied since the end dose is relatively large, and there is of World War II. Dose-response generally a level of dose (i.e., threshold) relationships for prodromal below which an effect is not expected to (forewarning) symptoms and for death occur. Acute effects may be classified within 60 days have been developed as severe or nonsevere clinical from data on the Japanese A-bomb pathophysiological effects. Severe survivors, Marshall Island natives pathophysiological effects are those exposed to fallout, and. patients which have clinically observable undergoing radiotherapy.. This work symptoms and may lead to serious has been supplemented by a number of disease and death. Other patho- animal studies under controlled physiological effects, such as conditions.

hematologic deficiencies, temporary infertility, and chromosome changes, The animal studies, usually using are not considered to be severe, but lethality as the end point, show that may be detrimental in varying degrees. many factors can influence the degree Some pathophysiological effects, such of response. The rate at which the as erythema, nonmalignant skin dose is delivered can affect the median damage, loss of appetite, nausea, lethal dose (LD50 ) in many species, fatigue, and diarrhea, when associated particularly at dose .rates less than with whole body gamma or neutron 5 Rlmin (PA-68a; BA-68). However, in exposure, are prodromal (forewarning primates there is less than a 50 B-3

percent increase in the LD50 as dose dose-response curves for prodromal rates are decreased from 50 Rlmin to (forewarning) symptoms and for about 0.01 Rlmin (PA-68a). There is lethality was made in the first edition good evidence of species specificity of "The Effects of Nuclear Weapons" (PA-68a; BO-69). The LD50 ranges (1957) (GL-57), and a more recent and from about 100 rad for burros to over well documented estimate is given in a 1000 rad for lagomorphs (e.g., rabbits). NASA publication, "Radiobiological Response is modulated by: age (CA-68), Factors in Manned Space Flight" extent of shielding (partial body (LA-67).

irradiation) (BO-65), radiation quality (pA-68a; BO-69), diet, and state of health (CA-68). B.2.1.1 The Median Dose for Lethality While animal studies provide The radiation dose that would support and supplemental information, cause 50 percent mortality in 60 days they cannot be used to infer the was estimated as 450 Roentgens in response for man. This lack of early reports (NA-56; GL-57; RD-51).

comparability of man and animals had The National Commission on Radiation already been noted by a review Protection and Measurements (NCRP) committee for the National Academy of calculated that this would correspond Sciences as early as 1956, in to a midline absorbed dose of 315 rad considering the length of time over (NC-74). The ratio of 315 rad to 450 which acute effects might be Roentgens is 0.70, which is about the expressed (NA-56): "Thus, an LD50 , estimated ratio of the active marrow 30-day consideration is inadequate to dose, in rads, to the tissue kerma in characterize the acute lethal dose air, in rads (KE-80). The BEAR response of man, and an LD50 , 60 days Committee noted that the customary would be preferable."! reference to LD50 in animal studies, as if it were a specific property, Several estimates of the levels at independent of age, was not justifiable which acute effects of radiation occur (NA-56): ".. .it is evident, now, that in man have been published. For the susceptibility of a whole population example, an early estimate of the is not describable by a single LD50 .

The published values are usually obtained for young adults and are

~e committee (known as the BEAR therefore maximal or nearly maximal Committee) also noted "The reservation must for the strain. In attempts to estimate be made here that the exposed Japanese population was heterogeneous with respect to LD50 in man, this age dependence age, sex, physical condition and degree of should be taken into consideration" added trauma from burns or blast. The extent (NA-56, pp.4-5). They observed that to which these factors affected the survival the LD50 approximately doubled as rats time has not been determined. In studies on went from neonates to young adults laboratory animals the converse is and then decreased as the animals true--homogeneous populations are studied" (NA-56. p.l-6).

aged further. Finally, the BEAR B-4

Committee concluded: "The situation is B.2.1.2 Variation of Response for complex, and it became evident that it Lethality is not possible to extrapolate with confidence from one condition of Uncertainty in the dose-response radiation exposure to another, or from function for acute effects has been animal data to man" (NA-56, p.I-8). . expressed in various ways. The slope Nevertheless, results from animal of the estimated dose-response function studies can aid in interpreting the has most commonly been estimated on human data that are available. the basis of the percent difference in the LD50 and the LD 15.9 or LDs4.1 (one The NCRP suggested the LD50/60 standard deviation from the LD50 ), as might be 10 to 20 percent lower for the was done by NASA (GL-57). These and old, very young, or sick, and somewhat other parameters derived in a similar greater for healthy adults of manner describe the uncertainty in the intermediate age (RD-51). Other central risk estimate for the estimates of adult LD50/60 have ranged dose-response function.

from about 300 rad to 243 + 22 rad.

These lower estimates are apparently Another means is to use an based on a ratio of air to tissue dose estimate of upper and lower bounds for similar to those calculated for midline the central risk estimate, e.g., the 95 organs in the body; 0.54 to 0.66 (KE-80; percent fiducial limits. At any given OB-76; KO-81). response point on the dose-response function, for example, the LDw the A NASA panel examined all dose causing that response has a patient and accident studies, tried to 95 percent probability of lying between remove confounding factors, and the lower and upper bounds of the concluded, "On this basis, it may be 95 percent fiducial limit for that point.

assumed that the LD50 value of286 rad To estimate this value, probit analyses obtained by a normal fit to the patient were run for each species using data in data is the preferred value for healthy published reports (KO-81; TA-71). This man" (LA-67). provided estimates for each species for comparability analyses. The 95 percent An LD50/60 of 286 + 25 rad fiducial limits at the LD50 response for (standard deviation) midline absorbed LD50/30 studies averaged +9 percent dose and an absorbed dose/air dose (range -9 to +26 percent) and for LD50/60 ratio of 0.66, suggested by the National studies +17 percent (range -20 to +45 Academy of Science (LA-67), is percent). At the LD 15 response, values probably a reasonable value for healthy were +16 percent (range -12 to +50 males. In the absence of more percent) for LD15/30 data and complete information, we assume that +26 percent (range -20 to +65 percent) a value of 300 rad + 30 rad is a for LD15/60 data. For the LDs5 response, reasonable reflection of current values were +17 percent (range -36 to uncertainties for average members of +36 percent) for the LDs5/30 data and the population.

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+24 percent (range -46 to +31 percent) Jones attempted to evaluate the for LDs5/60 data. hematologic syndrome from mammalian lethality studies using the The differences in the magnitude ratio of dose to LD50 dose as an of the fiducial limits are a function of indicator of the steepness of the slope the differences in age, sex, radiation of the dose-response function (JO-81).

quality, degree of homogeneity of the However, he evaluated LD50 studies experimental animals, husbandry, and only of species having a rather steep other factors. The estimates show that slope, i.e., dogs, monkeys, mice, and the fiducial limits, expressed as a swine. He also looked at several percent of the dose at any response, get different statistical models for greater the farther from the LD50 the dose-response functions and pointed estimate is made. For the purpose of out the problems caused by different estimating fiducial limits for humans, models and assumptions, particularly the 95 percent fiducial limits will be in evaluating the tails of the considered to be LD 15 +15 percent, LD50 dose-response function (less than LDlO

+ 10 percent, and LDs5 + 15 percent. and greater than LDgo). Jones Beyond these response levels, the recommended using a log-log model, fiducial limits are too uncertain and which he felt provided a better fit at should not be used. low doses (JO-81).

lfthe median lethal dose, LD50/60' Scott and Hahn also evaluated is taken as 300 +30 rad midline acute effects from mammalian absorbed dose, the response to higher lethality, but suggested using a Weibull and lower doses depends on the degree model (SC-80). One of the advantages of biological variation in the exposed of the Weibull model is that in addition population. The NASA panel decided to developing the dose-response the wide variation in the sensitivity of function, it can also be used to develop patients was a reflection of the hazard functions. These hazard heterogeneity of the sample; and that functions, if developed using the same the variation in sensitivity, the slope of model, can be summed to find the joint the central estimate of the response hazard of several different types of function, would be stated in the form of exposure (SC-83). This would allow one standard deviation calculated as estimation of the total hazard from 58 percent of the LD5o .They further multiple organ exposures to different decided the deviation in the patients types of radiation.

(58 percent) was too great, and the standard deviation for "normal" man As mentioned earlier, the human should be closer to that of dogs and median lethal dose is commonly monkeys (18 percent) (LA-67). (The .reported in terms of the LD50/60' Most rationale for selecting these species laboratory animal median lethal doses was not given.) are reported in terms of the LD50/30' In those cases where estimates of both LD50/30 and LD50/60 are available, I.e.,

B-6

the burro (ST-69), the variation (that physically large animals (swine, burros, is, the slope of the dose-response curve) sheep, and goats), 32 + 12 percent.

is greater in the LD50/60 study than in the LD50/30 study. Both the dog and the monkey data are for LD50/30' and so are B.2.l.3 Estimated Lethality vs Dose not appropriate for direct comparison forMan to man.

As noted in Section B.2.l.1, If an estimate of the deviation is \ dose-response estimates vary for a made for data from other studies and number of reasons. Some factors species, those where most of the affecting estimates for humans are:

fatalities occur within 30 days (like dogs and monkeys) have standard 1. Age:

deviations of from around 20 percent Studies on rats indicate the LD50 is

[swine (x-ray) (ST-69), dogs (NA-66), minimal for perinatal exposure, rises hamsters (AI-65), primates (Macaca) to maximum arourid puberty, and (DA-65)] to 30 percent [swine (60Co) then decreases again with increasing (HO-68)]. Those in which most deaths age (CA-68). The perinatal LD50 is occur in 60 days, like man, have about one-third of that for the healthy deviations from around 20 percent young adult rats; that for the geriatric

[sheep (CH-64)] to 40 percent [goats rat is about one-half of that for the (PA-68b), burros (TA-71)]. Nachtwey, young adult rat.

et al. (NA-66) suggested the steepness of the slope of the exposure response 2. Sex:

curve depends on the inherent Females are slightly* more sensitive variability of the subjects exposed and than males in most species (CA-68).

any variation induced by uncontrolled factors, e.g., temperature, diurnal 3. Health:

rhythm, and state of stimulation or Animals in poor health are usually arousal. So, while the slope of the more sensitive than healthy animals response curve for the patients studied (CA-68), unless elevated hematopoietic by the NASA panel may be activity is occurring in healthy unrealistically shallow for normal animals (SU-69).

human populations, there is no reason to think it should be as steep as those While these and other factors will for dogs and monkeys. affect the LD50/60 and the response curve for man, there are no numerical The average deviation for those data available.

species (burros, sheep, and goats) for which the standard deviation of the The variation in response at a LD50/60 is available has been used as an given dose level increases as the estimator for man. The mean value is population at risk becomes more 34 + 13 percent. This is only slightly heterogeneous and as the length of greater than the average value for all time over which mortality is expressed B-7

increases. In general, larger species fatality, as shown in Figure B-1. (See show greater variance and longer also section B.2.1.4.)

periods of expression than do small mammals, e.g., rodents. It is likely Figure B-1 IS based on the that the human population would show following values:

at least the same amount of variation as do the larger animals, i.e., a Dose (rad) Percent fatalities coefficient of variation of about one-third. <140 none 2 140 5 The d~gree of variation exhibited 200 15 in animal studies follows a Gaussian 300 50 distribution as well as or better than a 400 85 log normal distribution over that range 460 95 ofmortality where there are reasonable statistics. We have assumed here that the functional form of human response For moderately severe prodromal is Gaussian. Generally, sample sizes (forewarning) effects, we believe the for extreme values (the upper and dose at which the same percentage of lower tails of the distribution) are too exposed would show effects would be small to give meaningful results. approximately half of that causing Therefore, we have not projected risks fatality. This yields the following for doses more than two standard results (see also Figure B-1):

deviations from the LD50/ 6o ' We recogr.rize that estimates of acute Dose (rad) Percent affected effects may not be reliable even beyond one standard deviation for a population 50 <2 containing persons of all ages and 100 15 states of health. However, in spite of 150 50 these uncertainties, previous estimates 200 85 have been made of the acute effects 250 98 caused by total body exposure to ionizing radiation as a function of the magr.ritude of the exposure (NC-71; Although some incidence of LU-68; FA-73; NA-73). prodromal effects has been observed at doses in the range of 15 to 20 rads in Given the large uncertainties in patients (LU-68) and in the 0 to the available data, a median lethal 10 rads range of dose in Japanese dose value of about 300 rad at the A-bomb survivors (SU-80a; GI-84),

midline, with a standard deviation of 100 rad, may be assumed for planning

~he risk of fatality below 140 rad is not purposes. Such risk estimates should necessarily zero; rather, it is indeterminate and be assumed to apply only in the likely to remain so. This also applies to interval from 5 percent to 95 percent prodromal effects below 50 rad.

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FIGURE B-1. ACUTE HEALTH EFFECTS AS A FUNCTION OF WHOLE BODY DOSE.

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there is great uncertainty in an LD50/60 from doses of220-310 rad for interpreting the data. Patients may be a healthy young adult population.

abnormally sensitive, so that the Thus, the ill or injured are assumed to dose-response function in patients may have an increased risk of acute represent the lower bound of doses that mortality at high doses.

would show a response in a healthy population (LU-67). The response of The above estimates for LD50/60 are Japanese survivors in the low dose also based on the assumption of ranges is complicated by the blast and minimal medical care following thermal exposure that occurred at the exposure. UNSCEAR (UN-BB) same time (SU-BOb). For these estimates that the threshold for reasons, care should be taken in mortality would be about 50 percent applying estimates of prodromal higher in the presence of more intense effects. The prodomal dose-response medical care.

function listed above is more likely to overestimate the proportion of persons affected than to underestimate it. B.2.1.4 Threshold Dose Levels for Acute Effects These estimated ranges and effects are in agreement with estimates made This section summarizes for manned space flights (LA-67; information available in the literature LU-67), which included consideration of regarding thresholds for health effects.

the effect of abnormal physiology or It also reviews actions that have been sickness in the patients to which the taken as a result of radiation exposure data apply. Uncertainty in estimates to provide insight on dose levels at of the biological effects of radiation which actions to avoid dose may be exposure is great. It is probably due in appropriate.

part to variation in the health of individuals in exposed populations. Some acute effects, such as cellular These estimates assume a healthy changes, may occur at low doses with young adult population and may not be no dose threshold. Most such effects a conservative estimate of risk for have a nnmmum threshold of other population groups, such as detectability; for example, five rad is children or the elderly. Lushbaugh, about the lower limit of whole body et al. (LU-6B) found that prodromal dose which causes a cellular effect effects probably occur in both healthy detectable by chromosome or other and ill persons in about the same dose special analyses (NC-71; FA-73). This range. However, Lushbaugh, et al. value is recommended by UNSCEAR as (LU-6B) and NATO (NA-73) suggest the starting point for biological that acute mortality in a population dosimetry (UN-69). Purrott, et al. have which is ill, injured, or in other ways reported a lower limit of detection of debilitated will occur in 50 percent of chromosome aberrations of 4 rad for that population at doses of 200-250 rad x-rays and 10 rad for gamma rays in about 60 days (LD50/60)' in contrast to (PU-75).

B-10

More recent advanced chromosome 3 rad per year for periods varying from banding techniques permit detection of 2 to 22 years (PO-75). The shortest increased incidence of chromosome exposure period in which abnormal abnormalities from continuous spermatogenesis was reported was 31 exposure to systematically deposited to 41 months (PO-75); at the highest radioisotopes or radioisotopes deposited dose rate reported (3 radia) , this is a in the lung at very low levels, e.g., body cumulative dose of 8 to 10 rem. While burdens of 100 to 1200 pCi of more study is required, these results plutonium-239 (BR-77). While the suggest the need to restrict acute doses exact dose associated with such to below 10 rem to avoid this effect, burdens is not known, it is probably on because a given acute dose is the order of 10 to 100 millirem per anticipated to be more effective than year. Lymphocytes exposed to 5 rem in the same cumulative dose given over a vitro show severe metabolic dysfunction longer period of time (NA-56; UN-58).

and interphase cell death (ST-64). The extent to which similar effects occur Many observations have indicated after in vivo exposure is unknown. that doses of 10 rem or more to the While chromosome abnormalities in pregnant woman are hazardous to the circulating lymphocytes are reported to fetus. Mental retardation due to persist for long periods (UN-69), the exposure of the fetus is discussed in significance of such abnormalities is Section B.3; this discussion is restricted not known (BR-77). to acute effects. The World Health Organization (WHO) indicates that Hug has suggested 5 rem as the there is no evidence of teratogenic lower limit of exposure which might effects from short term exposure of the produce acute effects (WH-65). Five' fetus to a dose less than 10 rad during rad is als.o in the low dose, short-term the early phase of gestation, the period exposure range defined by Cronkite when the fetus is most sensitive to and Haley, and is below the 10 rad these effects (WH-84).

which they thought would cause only a slight detectable physiological effect of A number of authorities have unknown clinical significance (CR-71). recommended that exposures of 10 roentgens or higher be considered as an Although the ICRP has suggested indication for carrying out induced that annual doses of 15 rad would not abortion (RA-59, DE-70, BR-72, impair the fertility of normal fertile NE-76). Brent and Gorson also suggest men (IC-69), an acute dose of 15 rad that 10 rad is a "practical" threshold causes "moderate" oligospermia for induction of fetal abnormalities (approximately 70 percent reduction in CBR-72). The Swedish Government sperm count) which lasts for some Committee on Urban Siting of Nuclear months (LA-67). Popescu and Power Stations stated the situation as Lancranjan reported alterations of follows: "What we have called spermatogenesis and impaired fertility unconditional indication of abortion in men exposed to from 500 millirad to involves the exposure of. pregnant B-11

women where radiation dose to the Effects of radiation exposure of the fetus is higher than 10 rad. When thyroid have been shown in animal such doses are received in connection experiments. Walinder and Sjoden with medical treatment, it has hitherto found that doses in excess of 3,000 rad been assumed that the probability of from 1311 caused noticeable depression damage to the fetus is so high that an of fetal and juvenile mouse thyroid abortion is recommended. The development (WA-69). Moore and probability for such injury is still Calvin, working with the Chinese moderate compared with the normal hamster, showed that an exposure as frequency of similar fetal injuries, and low as 10 roentgens (x-rays) would give the probability is particularly reduced rise to 3 percent aberrant cells when when the dose is received late in the the thyroid was cultured (MO-68).

pregnancy" (NA-74). While the direct relationship of these results to human effects is not certain, mammalian thyroid cells can be injured B.2.1.5 Acute Effects in the Thyroid at exposures as low as 10 roentgens.

Acute effects are produced in the thyroid by doses from radioiodine on B.2.1.6 Acute Effects in the Skin the order of 3,000 to 100,000 rad.

Ablation of the thyroid requires doses The first stage of skin reaction to of 100,000 rad (BE-68). . The thyroid radiation exposure is erythema can be rendered hypothyroid by doses (reddening) with a threshold of from of about 3,000 to 10,000 rad (IC-71). A 300 to 800 rad. Acute exudative thyroid dose from radioiodines of 1000 radiodermatitis results from doses of rad in adults and 400 rad in children 1,200 to 2,000 rad (WH-84).

implies an associated whole body dose of about 1 rad due to radioiodines circulating in the blood. Following B.2.1.7 Clinical Pathophysiological inhalation of 1311, the committed Effects thyroid dose is about one radlpCi intake of 1311 in adults. In the A large amount of anecdotal developing fetus, the thyroid dose information is available on the injury ranges from one to six rad per p.Ci of of organ tissues by high doses of 131 1 entering the mother's body (IL-74). radiation. Acute injury to tissue includes swelling and vacuolation of Although acute clinical effects are the cells which make up the blood only observed at high doses, subclinical vessels, increased permeability of acute thyroid radiation effects may vessels to fluids so that exudates form, occur at lower doses (DO-72). Impaired formation of fibrin clots and thrombi, thyroid capability may occur above a fibrinoid thickening in the walls of threshold of about 200 rad (DO-72). blood vessels, and swelling and vacuolization of parenchymal cells. In summary, there is an initial exudative B-12

reaction followed in time by fibrosis persons within 5 years (TD 0.1/5) is and sclerosis (WH-76, CA-76). taken as the threshold for the initiation of clinical pathophysiological effects in Estimates of radiation doses organs other than thyroid, the necessary to cause severe tissue equivalent dose level for most organs is response in various organs are given in 550 rets or more; testes 440 + 150 rets, Table B-l. These tissue dose estimates ovary 170 + 70 rets, and bone marrow are based on response to radiotherapy 165 rets.

treatment, which is normally given on a fractionated dose basis, but also may The radiation exposure to organs in be given as a continuous exposure. rad units that will cause clinical Therefore, these estimates must be pathophysiological effects within 5 adjusted to the equivalent single years to 0.1 percent of the exposed radiation dose for use in the present population as a function of the duration analysis. The formalism of Kirk, et al. of a continuous level of exposure can (KI-71) is used to estimate the then be estimated by using Goitein's equivalent dose for a single acute modification of the Kirk methodology exposure in rad-equivalent therapy (GO-76). This relationship is shown in units (rets: the dose calculated from Table B-3.

the fractionated exposure which is equivalent to a single acute exposure Bone marrow is an organ of for a specific biological endpoint.) particular concern because Table B-2 lists acute exposure radionuclides known to concentrate in equivalents in rets for various organs. this organ sy~tem occur in nuclear incidents. The acute lethality due to With the exception of bone marrow, the hematologic syndrome (LA-67) is the exposures required to cause estimated to occur in the range of 200 5 percent injury within 5 years (TD to 1,000 rad, so that the difference is 5/5) in internal organs are in the range small between exposure levels that of 1,000 to 5,000 rad. Since, with this might cause acute lethality and type of injury, the dose response is exposure levels that might cause only nonlinear and has a threshold (i.e., is "severe clinical pathophysiology," as nonstochastic), there is an exposure derived from radiotherapy data.

below which injury is not expected. If the shape of the injury dose-response In summary, organ systems are not curve is the same for all internal expected to show symptoms of severe organs as it is for the lung, plotting the clinical pathophysiology for projected two acute exposure equivalents (TD short-term' exposure doses less than a 50/5 and 5/5) for each organ on log few hundred rad. Projected doses to probability paper allows a crude bone marrow at this high level are estimation of the number of clinical relatively more serious and more likely pathophysiological effects per 1000 to result in injury than doses to other persons exposed as a function of dose organ systems. '.

level. If one acute effect per 1000 B-13

Table B-1 Radiation Doses 'Causing Acute Injury to Organs (RU-72, RU-73)

Volume or Risk of injury in five years Organ area of 5 percent 50 percent exposure8 (rad) (rad) Type of injury Bone whole 250 450 aplasia and marrow pancytopenia Liver segment 3000 4000 acute and chronic whole 2500 4000 hepatitis Stomach 100 cm2 4500 5500 ulcer, perforation, hemorrhage Intestine 400 cm2 4500 5500 ulcer, perforation, 100 cm2 5000 6500 hemorrhage Lung whole 1500 2500 acute and chronic 100 cm2 3000 3500 pneumonitis Kidney whole 2000 2500 acute and chronic nephrosclerosis Brain whole 6000 7000 infarction, necrosis Spinal 10 cm 4500 5500 infarction, cord necrOSIS Heart 60 percent 4500 5500 pericarditis and pancarditis Skin 5500 7000 ulcers, fibrosis Fetus whole 200 400 death Lens of whole 500 1200 cataracts eye Ovary whole 200-300 625-1200 permanent sterilization Testes whole 500-1500 2000 permanent sterilization

-Dose delivered in 200-rad fractions, 5 fractions/week.

--- Unspecified.

B-14

Table B-2 Acute Radiation Exposure as a Function ofRad Equivalent Therapy Units (rets)

Risk of injury in five years Volume or Organ area of 5 percent 50 percent exposure (rets) (rets)

Bone marrow whole 230 340 segment 1135 1360 Liver whole 1000 1360 Stomach 100 cm2 1465 1665 Intestine 400 cm2 1465 1665 100 cm2 1570 1855 Lung whole 720 1000 100 cm2 1135 1245 75 percent 770b Kidney whole 875 1000 Brain whole 1770 1950 Spinal cord 10 em 1465 1665 Heart 60 percent 1465 1665 Skin 1665 1950 Fetus whole 200 315 Lens of eye whole 355 620 Ovary whole 200-430a 410-875a Testes whole 340-720a 410-875a (sterilization) aFor a 200-rad/treatment, 5 treatments/week schedule (LU-76).

bReference WA-73.

--- Unspecified.

B-15

Table B-3 Radiation Exposure to Organs Estimated to Cause Clinical Pathophysiological Effects within 5 Years to 0.1 Percent of the Exposed Population (GO-76)

Duration of exposure Ovary Bone marrow Testes Other organs (days) (rad) (rad) (rad) (rad)

(acute) (170 retst (165 rets) (440 rets) (550 rets) 1 315 300 810 1020 2 390 380 1010 1260 4 470 450 1210 1510 7 550 540 1430 1790 30 840 820 2190 2740 365b 1740 1690 4510 5640 "The dose in rets is numerically equal to the dose in rads.

bAssuming tissue recovery can continue at the same rate as observed during 30- to 60-day therapeutic exposure courses.

Even if severe clinical are transitory, others are long-lasting, pathophysiological effects can be but with only minor reductions in avoided, there is still a possibility of functional capacity.

clinical pathophysiological effects of a less severe or transitory nature. The Human data are limited and are 1982 UNSCEAR report (UN-82) reported primarily in the radiotherapy reviewed much of the data on animals literature. The data suggest most and man. In the animal studies, there tissues in man are more radiation were reports of: changes in stomach resistant than those in animals.

acid secretion and stomach emptying at However, the human hematopoietic 50 to 130 rad; stunting in growing system shows a transient response, animals at the rate of 3 to 5 percent reflected by decreased circulating white per 100 rad; degeneration of some cells cells and platelets, at about 50 rad.

or functions in the brain at 100 rad, Temporary sterility has been observed particularly in growing animals; after doses of 150 rad to the ovaries temporary changes in weight of and 10 rad to the testes, when given as hematopoietic tissues at 40 rad; and fractionated doses.

more damage in ovaries and testes caused by fractionated doses rather There is not sufficient data to than acute doses. Some of the effects determine dose-response functions B-16

nor to describe the duration and B.3 Mental Retardation severi ty of dysfunction expected.

Brain damage to the unborn is a class of injuryreported in atomic bomb B.2.2 Summary and Conclusions survivors which does not fall into Regarding Acute Effects either an acute or delayed effect category, but exhibits elements of both.

Based on the foregoing review of What has been observed is a acute health effects and other biological significant, dose-related increase in the effects from large doses delivered over incidence and severity of mental short periods of time, the following retardation, microencephaly (small whole body doses from acute exposure head size), and microcephaly (small provide useful reference levels for brain size) in Japanese exposed to decisionmaking for P AGs: radiation in utero during the Sth to 15th week after conception CBL-73; 50 rad - Less than 2 percent of the MI-76). While the actual injury may be exposed population would be acute, it is not identified until some expected to exhibit prodromal time after birth.

(forewarning) symptoms.

In an early study Mole (MO-S2) 25 rad - Below the dose where suggested that, although radiation prodromal symptoms have may not be the sole cause of these been observed. conditions, it is prudent to treat the phenomenon as radiation-related.

10 rad - The dose level below which a More recently, Otake and Schull fetus would not be expected (OT-S3) have concluded: (1) there is no to suffer teratogenesis (but risk to live-born due to doses delivered see Section B.3, Mental up to S weeks after conception, (2) most Retardation.). damage occurs at the time when rapid proliferation of neuronal elements 5 rad - The approximate mlmmum occurs, i.e., S to 15 weeks of gestational level of detect ability for acute age, (3) the dose-response function for cellular effects using the most incidence during this period appears to sensitive methods. Although fit a linear model, (4) the risk of these are not severe occurrence is about five times greater pathophysiological effects, during the .period S-15 weeks of they may be detrimental. gestation than in subsequent weeks, and (5) in later stages of gestation, e.g.,

Based on the first principle to be after the 15th week, a threshold for satisfied by PAGs (paragraph B.1.6), damage may exist.

which calls for avoiding acute health effects, values of 50 rem for adults and In their published reports, Otake 10 rem for fetuses appear to represent and Schull (OT-S3) evaluated the upper bounds. - incidence of severe mental retardation B-17

using the T -65 dosimetry and the exposed pregnant women be controlled dosimetry estimates developed in the to keep the fetal dose below 0.5 rem ongoing dose reassessment program for over the entire term of pregnancy, and the atomic bomb survivors, and using that no dose be delivered at more than two tissue dose models. Their the uniform monthly rate that would estimated ranges of risk were: satisfy this limit (i.e., approximately 50-60 mremimonth)(EP-87). The 8 to 15 weeks after gestation: NCRP has, for many years, 3-4x10*a cases/rad; recommended a limit of 0.5 rem (NC-71). 1CRP recommends controlling 16 or more weeks after gestation: exposure of the fetus to less than 0.5 5-7x10-4 cases/rad. rem in the first 2 months to provide appropriate protection during the The higher values are based on the essential period of organogenesis T-65 dosimetry and the Oak Ridge (1C-77).

National Laboratory estimate of tissue dose. The lower values are based on Oak Ridge National Laboratory BA Delayed Health Effects dosimetry and the Japanese National Institute of Radiological Sciences This section addresses information estimates of tissue dose. Later relevant to the second principle estimates based on the dose (paragraph B.1.5) for establishing reassessment completed in 1986 are P AGs, the risk of delayed health effects consistent with these published results in exposed individuals. The following (SC-87). subsections summarize the estimated risks of cancer and genetic effects, the In view of the foregoing, the risk of two types of delayed effects caused by mental retardation from exposure of a exposure to radiation.

fetus in the 8th to 15th week of pregnancy is taken to be about 4x10*a per rad. Because of this relatively high BA.1 Cancer risk, special consideration should be given to protection of the fetus during Because the effects of radiation on this period. The risk to a fetus exposed human health have been more after the 15th week is taken as 6x10-4 extensively studied than the effects of per rad. For the cases studied (OT-84), many other environmental pollutants, no increased incidence of mental it is possible to make numerical retardation was observed for exposure estimates of the risk as a result of a during the 1st to the 7th week of particular dose of radiation. Such pregnancy. estimates, may, however, give an unwarranted aura of certainty to Federal Radiation Protection estimated radiation risks. Compared Guidance, adopted in 1987, to the baseline incidence of cancer and recommends that dose to occupationally genetic defects, radiogenic cancer and B-18

genetic defects do not occur very distinguish it from previous reports of frequently: Even in heavily irradiated the BEIR committee.

populations, the number of cancers and genetic defects resulting from radiation The most important epidemiological is known with only limited accuracy. data on radiogenic cancer is that from In addition, .all members of existing the A-bomb survivors. The Japanese exposed populations have not been A-bomb survivors have been studied for followed for their full lifetimes, so data more than 40 years, and most of them on the ultimate numbers of effects is have been followed in a major, caref1,1lly not yet available. Moreover, when planned and monitored epidemiological considered in light of information survey, the Life $pan Study Sample, gained from experiments with animals since 1950 (KA-82, WA-83). They were and from various theories of exposed to a wide range of doses and carcinogenesis and mutagenesis, the are the largest group that has been observed data on the effects of human studied. They are virtually the only exposure are subject to a number of group providing extensive information interpretations. This, in turn, leads to on the* response pattern at various differing estimates of radiation risks by levels of exposure to low-LET radiation.

individual scientists and expert groups.

In summary, the estimation of The estimated cancer risk from radiation risks is not a fully mature low-LET, whole body, lifetime exposure science and the evaluation of radiation presented here is based on a life table hazards will continue to change as analysis using a linear response model.

additional information becomes We use the* arithmetic average of available. relative and absolute risk projections (the BEIR-3 L-L model) for solid Most of the observations of cancers, and an absolute risk projection radiation-induced carcinogenesis In for leukemia and bone cancer (the humans are on groups exposed to BEIR-3 L-L model). For whole body low-LET radiations. These groups dose, this yields an estimated 280 (with include the Japanese A-bomb survivors a possible range of 120 to 1200) and medical patients treated with fatalities per million person-rem for a x-rays for ankylosing spondylitis in population cohort representative of the England from 1935 to 1954 (SM-78). 1970 U.S. population. We assume this The National Academy of Science estimate also applies to high-LET Committee on the Biological Effects of radiation (e.g. alpha emitters); no Ionizing Radiations (BEIR) (NA-80) reduction has been applied for dose and UNSCEAR (UN-77) have provided rate. (The rounded value, 3x10-4 knowledgeable and exhaustive reviews fatalities 3 per person-rem, has been of these and other data on the selected for this analysis.)

carcinogenic effects of human exposures. The most recent of the BEIR studies was published in 1980 3Preliminary reviews of new results from and is here designated BEIR-3 to studies of populations exposed at Hiroshima B-19

Whole body dose means a uniform bloodstream (TG-66). These dose to every organ in the body. In nonuniform distributions of dose (and practice, such exposure situations therefore risk) are taken into account seldom occur, particularly for ingested through use of the weighting factors for or inhaled radioactivity. Inhaled calculating effective dose.

radioactive particulate materials may be either soluble or insoluble. Soluble There is a latent period associated particulate materials deposited in the with the onset of radiation-induced lung will be rapidly absorbed, and the cancers, so the increased risk is not radionuclides associated with them immediately apparent. The increased distributed throughout the body by the risk is assumed to commence 2 to 10 bloodstream. As these radionuclides years after the time of exposure and are transported in the blood, they continue the remainder of the exposed irradiate the entire body. Usually, individual's lifespan (NA-80).

they then redeposit in one or more organs, causing increased irradiation of For uniform exposure of the whole that organ. Insoluble particulate body, about 50 percent of materials, on the other hand, are only radiation-induced cancers in women partially absorbed into body fluids. and about 65 percent in men are fatal (This fraction is typically assumed to (NA-80). Therefore, 1 rem of low-LET be about 8 percent.) This absorption radiation would be expected to cause a occurs over a period of years, with a total of about 500 cancer cases if portion entering the bloodstream and delivered to a population of one million.

another retained in the pulmonary (In the case of thyroid and skin, the lymph nodes. The balance (92 percent) ratio of nonfatal to fatal cancers are of inhaled insoluble particulate much higher. These are addressed materials are removed from the lung separately below.) This corresponds to within a few days by passing up the air an average annual individual passages to the pharynx where they probability of developing cancer of are swallowed. Inhaled insoluble about 7xl0- 6 per year. For perspective, particulate materials thus irradiate the average annual risk of dying of both the lung and the gastrointestinal cancer from all causes in the United tract, with a small fraction being States, in 1982, was 1.9xl0-3

• eventually absorbed into the (footnote continued) BA.1.1 Cancer Risk Due to Radiation Exposure of the Thyroid and Nagasaki indicate that these risk estimates may be revised upwards significantly in the near future, particularly for acute Exposure of the thyroid to exposure situations. EPA has recently used a extremely high levels of radiation may slightly higher value, 4 x 10-4 fatalities in cause it to degenerate. At moderate standards for air emissions under the Clean levels of exposure some loss of thyroid Air Act. We will revise these risk estimates to function will occur. At lower levels of reflect new results following appropriate review.

exposure, there are delayed health B-20

effects, which take the form of both thyroid dose *5 times the numerical thyroid nodules and thyroid value of the PAG for effective dose.

malignancies (NA-72; NA-80). Doses as low as 14 rad to the thyroid have been associated with thyroid BA.1.2 Cancer Risk Due to Radiation malignancy in the Marshall Islanders Exposure of the Skin (CO-70). The increased risk of radiation-induced cancer is assumed to The risk of fatal skin cancer is commence about 10 years after initial estimated to be on the order of one exposure and to continue for the percent of the total risk of fatal cancer remaining lifespan of an exposed for uniform irradiation of the entire individual. body (IC-78). However, since the weighting scheme for calculating The true nature of thyroid nodules effective dose equivalent does not cannot be established until they are include skin, the P AG expressed in surgically removed and examined terms of effective dose does not provide histologically, and those that are protection against radionuclides which malignant can lead to death if not primarily expose skin. As in the case surgically removed (SA-68; DE-73; of the thyroid, the ratio of nonfatal to PA-74). Although thyroid malignancies fatal cancers from irradiation of the are not necessarily fatal, effects skin is high (on the order of 100 to 1).

requiring surgical removal of the It would not be appropriate to ignore thyroid cannot be considered benign. this high incidence of nonfatal skin In this analysis, all thyroid cancers, cancers by allowing 100 times as much both fatal and nonfatal, are counted for dose to the skin as to the whole body.

the purpose of estimating the severity For this reason, evacuation is of thyroid exposures. recommended at a skin dose 50 times the numerical value of the PAG for Based on findings in BEIR-3, we effective dose.

estimate that 1 rem of thyroid exposure carries a risk of producing a thyroid cancer of 3.6x10-4, of which a small BA.1.3 Cancer Risk Due to Radiation fraction (on the order of 1 in 10) will be Exposure of the Fetus fatal (NA-80). Since the calculation of effective dose equivalent does not The fetus is estimated to be 5 to 10 include consideration of nonfatal times as sensitive to radiogenic cancer thyroid cancers and the severity of the as an adult CFA-73; WH-65). Stewart medical procedures for their cure, it is reports increased relative incidence of appropriate to limit the dose to the childhood cancers following prenatal thyroid by an additional factor beyond x-ray doses as low as 0.20 to 0.25 rem that provided by the P AG expressed in and doubling of childhood cancers terms of effective dose equivalent. between 1-4 rem CST-73). She Protective action to limit dose to concluded that the fetus is about thyroid is therefore recommended at a equally sensitive to cancer induction in B-21

each trimester. Her findings are workers and do not take into account supported by similar results reported differences in dose resulting from the by MacMahon and Hutchinson differences in physiological parameters (MA-64), Kaplan (KA-58), Polhemus between children and adults, e.g.,

and Kock (PO-59), MacMahon (MA-63), intake rates, metabolism, and organ Ford, et al. (FO-59), Stewart and size. Although it is difficult to Kneale (ST-70b), and an AEC report generalize for all radionuclides, in some (AE-61). MacMahon reported that cases these differences tend to although there were both positive and counterbalance each other. For negative findings, the combination of example, the ratio of volume of air weighted data indicates a 40 percent breathed per unit time to lung mass is increase in childhood cancer mortality relatively constant with age, so that after in vivo exposure to diagnostic x the ICRP adult model for inhaled rays (1.0 to 5.0 rad): about 1 cancer materials provides a reasonably good per 2,000 exposed children in the first estimate of the dose from a given air 10 years after birth (MA-63). He concentration of radioactive material concluded that although the range of throughout life.

dose within which these effects are observed is wide, effects will be fewer The thyroid is an exception because at 1 rad than at 5 rad. the very young have a relatively high uptake of radioiodine into a gland that Graham, et al., investigating is much smaller than the adult thyroid diagnostic x-ray exposure, found a (see Section BA.2.2.). This results in a significantly increased relative risk of larger childhood dose and an increased leukemia in children: by a factor of 1.6 risk which persists throughout life. We follo'wing preconception irradiation of have examined this worst case mothers or in utero exposure of the situation. Age-specific risk coefficients fetus; by a factor of 2 following for fatal thyroid cancer (See Table 6-8 postnatal irradiation of the children; of "Risk Assessment Methodology" and by a factor of 2 following (EP-89>>) are about 1.9 higher per unit preconception irradiation of the mother dose for persons exposed at ages 0 to 9 and in utero exposure of the child years than for the general population.

(GR-66). Age-dependent dose factors (see NRPB-R162 (GR-85)) for inhalation of 1-131, are a factor of about 1.7 higher BA.1.4 Age Dependence of Doses for 10 year olds than for adults.

Therefore, the net risk of fatal thyroid Almost all dose models are based on cancer from a given air concentration of ICRP "Reference Man," which adopts 1-131 is estimated to be a factor of the characteristics of male and female about 3 higher for young children than adults of working age. ICRP-30 for the remainder of the population.

dosimetric models, which use This difference is not considered large "Reference Man" as a basis, are enough, given the uncertainties of therefore appropriate for only adult exposure estimation for implementing B-22

protective actions, to warrant anomalies, polydactyl, strabismus, etc.),

establishing age-dependent P AGs. 25 percent lead to severe medical problems (i.e., congenital cataracts, diabetes insipidus, deaf mutism, etc.),

B.4.2 Genetic Risk 23 percent would require extended hospitalization (Le., mongolism, An average parental dose of 1 rem pernicious anemia, manic-depressive before conception has been estimated to psychoses, etc.), and 2 percent .would produce 5 to 75 significant die before age 20 (i.e., anencephalus, genetically-related disorders per million hydrocephalus, pancreatic fibrocytic liveborn offspring (NA-80). . For this disease, etc.).

analysis we use the geometric mean of this range, i.e. 1.9x10-5

• This estimate applies to effects in the first generation B.4.3 Summary of Risks of Delayed only, as a result of dose to parents of Effects liveborn offspring. The sum of effects over all generations is estimated to be Table B-4 summarizes average approximately twelve times greater; lifetime risks of delayed health effects that is, 2.3x10-4. In addition, since any based on results from the above radiation dose delivered after a discussion. Because of the nature of parent's last conception has no genetic the dose-effect relationships assumed effect, and not all members of the for delayed health effects , from population become parents, less than radiation (linear, nonthreshold), there half of the entire dose in an average is no dose value below which no risk population is of genetic significance. can be assumed to exist.

Taking the above factors into account, we estimate that the risk of genetically-related disorders in all B.4.4 Risks Associated with Other generations is 1x10-4 per person-rem to Radiation Standards a typical population.

A review of radiation standards for Although the overall severity of the protection of members of the general genetic effects included as "significant" population from radiation shows a in the above estimates is not well range of values spanning several orders known, rough judgements can be made. of magnitude. This occurs because of The 1980. BEIR report referred to the variety of bases (risk, cost,

".... disorders and traits that cause a practicability of implementation, and serious handicap at some time during the situations to which they apply) that lifetime" (NA-80). From the types of influenced the choice of these defects reported by Stevenson (ST-59), standards. Some source-specific it can be estimated that, of all standards are relatively protective, e.g.,

radiation-induced genetic effects, 50 the EPA standard limiting exposure of percent lead to minor to moderate the public from nuclear power medical problems (i.e., hair or ear operations (25 mrem/y) from all path-B-23

Table B-4 Average Risk of Delayed Health Effects in a Populationa Effects per person-rem Whole Body Thyroid C Skin Fatal cancers 2.8E-4b 3.6E-5 3.0E-6 Nonfatal cancers 3.2E-4 3.0E-4 Genetic disorders 1.0E-4 (all generations)

II We assume a population with the same age distribution as that of the U.S. population in 1970.

b Risk to the fetus is estimated to be 5 to 10 times higher.

C Risk to young children is estimated to be about two to three times as high.

ways combined corresponds to a risk exposure to medical and natural (for cancer death) of 5xlO-4 for lifetime background radiation) to individuals in exposure. Similarly, regulations under the population not exceed 0.5 rem in a the Clean Air Act limit the dose due to single year (FR-60) and that the dose emissions of radionuclides to air alone to the fetus of occupationally-exposed from all DOE and NRC facilities to mothers not exceed 0_5 rem during the 0.01 rem per year, which corresponds 9-month gestation period (EP-87). This to a cancer risk of 2xlO-4 for lifetime dose corresponds to an annual exposure. Other guides permit much incremental risk of fatal cancer to higher risks. For example, the level at members of the general population of which the EPA recommends action to about 1.4xlO-4

• If exposure of the fetus reduce exposure to indoor radon (0.02 is limited to one ninth of 0.5 rem per working levels) corresponds to a risk of month over a 9-month gestation period, about 2xlO-2 (for fatal lung cancer) for as recommended, the risk of severe lifetime exposure. All of these mental retardation in liveborn is standards and guides apply to limited to about 7xlO-4

• nonemergency situations and were based on considerations beyond a The International Commission on simple judgement of acceptable risk. Radiation Protection recommends that the dose to members of the public not Federal Radiation Protection exceed 0.5 rem per year due to Guidance for nonemergency situations nonrecurring exposure to all sources of recommends that the dose from all radiation combined, other than natural sources combined (except from sources or beneficial medical uses of B-24

radiation (IC-77). They also Radioiodine: Principles of Nuclear Medicine.

recommend a limiting dose to members Ed. H.N. Wagner, Jr. pp. 343-369, W.B.

of the public of 0.1 rem per year from Saunders Company, Philadelphia (1968).

all such sources combined for chronic BL-73 Blot, W.J. and Miller, R.W. Mental .

(i.e., planned) exposure (IC-84a). These Retardation Following in Utero Exposure to upper bounds may be taken as the Atomic Bombs of Hir()shima and representative of acceptable values for Nagasaki. Radiology 106(1973):617-619.

the situations to which they apply.

That is, these are upper bounds of BO-65 Bond, V.P., T.M. Fliedner, and J.D. Archchambeau Mammalian Radiation individual risk that are acceptable for Lethality. Academic Press, New York (1965).

the sum of all sources and exposure pathways under international BO-69 Bond, V.P. Radiation Mortality in recommendations, for circumstances Different Mammalian Species, pp. 5-19, in that are justified on the basis of public Comparative Cellular and Species benefit, and when actual doses f:rom Radiosensitivity. Eds. V. P. Bond and R.

Sugabara. The Williams & Wilkins individual sources are "as low as Company, Baltimore (1969).

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Radiation Exposure in Pregnancy, Current Problems in Radiology, Vol. 2, No.5, 1972.

BR-77 Brandom, W.F. Somatic Cell Chromosome Changes in Humans Exposed to 239Plutonium and 222Radon. Progress Report, Contract No. E(29-2)-3639, Modification No.

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B-26

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APPENDIXC Protective Action Guides for the Early Phase:

Supporting Information

Contents Page C.1 Introduction........................................... C-1 C.1.1 Existing Federal Guidance ................. ; . . . . . . . .. C-1 C.1.2 Principal Exposure Pathways ........... . ............ C-2 C.2 Practicality of Implementation ............................ C-3 C.2.1 Cost of Evacuation ................................ C-3 C.2.1.1 Cost Assumptions ........................... C-4 C.2.1.2 Analysis .................................. C-5 C.2.1.3 Conclusions ............................... C-10 C.2.2 Risk of Evacuation ................................ C-10 C.2.3 Thyroid Blocking .................................. C-13 C.2.4 Sheltering ................. . ..................... C-14 C.3 Recommended PAGs for Exposure to a Plume during the Early Phase .......................................... C-17 C.4 Comparison to Previous PAGs C-21 C.5 Dose Limits for Workers Performing Emergency Services. C-22 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .... . . . . . . C-24 Figures C-1 Evacuation Model ...................................... C-6 Tables C-1 Costs for Implementing Various PAGs for an SST-2 Type Accident (Stability Class A) .............................. C-7 ill

Tables (continued)

Page C-2 Costs for Implementing Various PAGs for an SST-2 Type Accident (Stability Class C) .............................. C-8 C-3 Costs for Implementing Various PAGs for an SST-2 Type Accident (Stability Class F) ............................... C-9 C-4 Upper Bounds on Dose for Evacuation, Based on the Cost of Avoiding Fatalities ................................... C-11 C-5 Average Dose Avoided per Evacuated Individual for Incremental Dose Levels for Evacuation ..................... C-12 C-6 Representative Dose Reduction Factors for External Radiation ............................................ C-14 C-7 Dose Reduction Factors for Sheltering from Inhalation of Beta-Gamma Emitters ................................ C-16 C-8 Summary of Considerations for Selecting the Evacuation P AGs ...................................... C-18 C-9 Comparison of Projected Doses for Various Reactor Accident Scenarios ..................................... C-21 C-10 Cancer Risk to Emergency Workers Receiving 25 Rem Whole Body Dose ............................................ C-24 IV

APPENDIXC Protective Action Guides for the Early Phase:

Supporting Information C.1 Introduction most likely to provide an upper bound on the magnitude of the variety of This appendix sets forth supporting possible sources of nuclear incidents.

information for the choice of Protective Although atmospheric releases from Action Guides (PAGs) for the early other types of nuclear incidents are phase of the response to a nuclear likely to involve smaller consequences, incident involving the release of the affected populations, and therefore airborne radioactive material. It then the costs and benefits of protective describes application of the basic action are each expected to scale in principles for selection of response roughly the same proportion for lesser levels set forth in Chapter 1 to the magnitude incidents. Thus, basic guidance on evacuation and sheltering conclusions developed for responses to in Chapters 2 and 5. reactor facilities are assumed to remain valid for other types of nuclear Response to a radiological incidents. Supplementary protective emergency will normally be carried out actions, such as washing and change of in three phases, as discussed in clothing to re<;luce exposure of the skin Chapter 1. Decisions during the first and use of stable. iodine to reduce (early) phase will usually be based on uptake of radioiodine to the thyroid, predicted or potential radiological are also considered, but in less detail.

conditions in the environment, rather than on actual measurements. The principal protective action is C.1.1 Existing Federal Guidance evacuation, with sheltering serving as a suitable alternative under some In the 1960's, the Federal Radiation conditions. This appendix examines Council (FRC) defined PAGs and the potential magnitudes and established limiting guides for consequences of predicted exposures of ingestion 'of strontium-89, populations during the early phase, for strontium-90, cesium-137, and selected nuclear reactor accident iodine-131 (FR-64; FR-65). That scenarios, in relation to the benefits guidance applied to restricting the use and detrimental consequences of of food products that had become evacuation and sheltering. Nuclear contaminated as the result of release of reactor facilities are chosen for radioactivity to the stratosphere from evaluation because, due to their weapons testing; During the period number, size of source, and energy immediately following an incident at available to drive a release, they are any domestic nuclear facility, when the C-1

critical source of exposure is expected bloodstream to the thyroid gland where to be a nearby airborne plume, the much of the iodine will be deposited principal protective actions are and most of the dose! will be delivered.

evacuation or sheltering. The P AGs Although dose to skin from materials developed here thus do not supersede deposited on the skin and clothing previous guidance, but provide could be significant, it will be less additional guidance for prompt important in terms of risk of fatal exposure pathways specific to a cancer than dose from inhalation, if domestic nuclear incident. early protective actions include washing of exposed skin and changes of clothing.

C.1.2 Principal Exposure Pathways As the plume passes over an area, The immediate exposure pathway radioactive materials may settle onto from a sub-stratospheric airborne the ground and other surfaces. People release of radioactive materials is remaining in the area will then direct exposure from the cloud of continue to be exposed through radioactive material carried by ingestion and external radiation, and prevailing winds. Such a plume can through inhalation of resuspended contain radioactive noble gases, materials. The total dose from such iodines, and/or particulate materials, deposited materials may be more depending on the source involved and significant than that due to direct conditions of the incident. These exposure to the plume, because the materials emit gamma rays, which are term of exposure can be much longer.

not significantly absorbed by air, and However, since the protective actions will expose the entire bodies of nearby considered here (evacuation and/or individuals. sheltering) may not be appropriate or may not apply for this longer term Another immediate exposure exposure, doses from these exposures pathway occurs when people are beyond the early phase are not submerged in the cloud of radioactive included in the dose considered in the materials. In this case radioactive P AGs for the early phase. It is materials are inhaled, and the skin and assumed that, within four days after clothes may be contaminated. Inhaled an incident, the population will be radioactive materials, depending on their solubility in body fluids, may either remain in the lungs or move via lIn this and all subsequent references, the the blood to other organs. Many word "dose" means the committed dose radionuclides which enter the equivalent to the specified organ, or, if no organ is specified, the sum of the committed bloodstream tend to be predominantly effective dose equivalent from intake of concentrated in a single organ. ' For radionuclides and the effective dose equivalent example, if radioiodines are inhaled, a from external sources of radiation. (Section significant fraction will tend to move B.1.l contains a more detailed discussion of rapidly from the lungs through the units of dose for PAGs.)

C-2

protected from these subsequent doses evaluated here. These factors are on the basis of the P AGs for relocation evaluated to determine whether the and for contaminated food and water. costs are low enough to justify lower (See Chapters 3 and4.) P AGs than would be required to satisfy upper bounds of acceptable risk under Based on the foregoing Principles 1 and 2.

considerations, the PAGs for the early phase are expressed in terms of estimated doses from exposure due to C.2.1 Cost of Evacuation external radiation, inhalation, and contamination of the skin only during Costs incurred to reduce the the early phase following an incident. radiation risk from nuclear incidents can be considered to fall into several major categories. The first category C.2 Practicality of Implementation includes the design, construction, and operation of nuclear facilities in such a Whereas Appendix B deals with the manner as to minimize the probability risk associated with the projected dose and consequences of radiological that could be avoided by any protective incidents. It is recognized that the action, this section addresses the costs probability and consequences of such and risks associated with evacuation incidents usually cannot be reduced to itself. That is, these analyses relate to zero. Therefore, a second category is Principles 3 and 4 for deriving P AGs, necessary: the development' of set forth in Chapter 1, which address emergency response plans to invoke the practicality of protective actions, actions which would reduce exposure of rather than acceptability of risks under potentially exposed populations, and Principles 1 and 2, which is evaluated consequently their risks, if a major in Appendix B. nuclear incident should occur.

The principal relevant protective Both of the above categories of cost actions during the early phase are, as are properly attributed to the cost of noted earlier, evacuation* and design and operation of a nuclear sheltering. In some cases, washing and facility. A third category of costs is the changing of clothing, or thyroid actual expenses incurred by taking blocking may also be appropriate protective actions as the result of an actions. The costs, risks, and degrees incident. In general, the choice of of protection associated with levels for P AGs will affect only this evacuation are generally higher than third category of costs. That is, all those for sheltering. Although there costs in the first two categories are may be some costs and risks associated assumed to be unaffected by decisions with the other protective actions, they on the levels ofPAGs. (This will be the are small and not readily quantifiable. case unless the P AGs were to be* set so Therefore, only the costs and risks high as to never require protective associated with evacuation will be action, in which case response plans C-3

would be unnecessary.) Therefore, the plume, inhalation of radioactive costs associated with implementing the material in the plume, and from four P AGs are evaluated only in terms of days exposure to deposited radioactive the actual cost of response. In a material.

similar manner, the risk incurred by protective actions is compared only to 5. Population distributions are the the risk associated with the radiation average values observed around 111 dose that would be avoided by the nuclear power reactor plants, based on action, and is unaffected by any other 1970 data.

measures taken to reduce risks that fall in the first two categories of cost 6. The cost of evacuation is $185 per identified above. person for a 4-day evacuation involving a 100-mile round trip, with an average of 3 persons per household. These C.2.1.1 Cost Assumptions evacuation costs include wages and salaries of personnel directing the The analyses in this section are evacuation, transportation costs of based on evaluation of the costs of evacuees to and from the staging evacuation and the doses that would be location, food and shelter for the received in the absence of protective evacuees during the evacuation period, actions for nuclear reactor incidents. loss of personal and corporate income These were calculated as a function of during the evacuation period, and the offsite location, meteorological costs of any special supplies (TA-87).

condition, and incident type (TA-87).

Dose and cost data are based on the The estimated costs and doses following assumptions: avoided are based on the following idealized evacuation area model (see

1. Airborne releases are those Figure C.1.):

associated with fuel melt accidents at nuclear reactor facilities followed by 1. All people within a 2-mile radius of containment failure. the incident are evacuated for all scenarios.

2. Meteorological conditions range from stable to unstable, and 2. People are also evacuated from a windspeeds are those typical of the downwind area bounded by equivalent stability class. rays on either side of the center line of the plume, which define the angular

3. Plume dispersion follows a spread (70, 90, or 180 degrees) of the Gaussian distribution, with a 0.01 mls area evacuated by an arc at the dry deposition velocity for iodine and distance beyond which the evacuation particulate materials. dose would not be exceeded on the

. plume centerline .

4. Doses are those incurred from whole body gamma radiation from the C-4

Figure C-l shows the relationShip at the margin, since the cost of between the area in which the evacuating the additional area is evacuation dose would be exceeded and incurred to avoid the incremental the larger area that might be collective dose. Therefore, the evacuated. The figure shows the plume appropriate quantities are the cost and centered in an idealized evacuation risk for the additional area evacuated.

area. Results of analyses on both a total and incremental basis* are presented in Tables C-l, C-2, and* C-3 for accident C.2.1.2 Analysis category SST-~. This is the smallest category of fuel melt accident yielding Evaluation of costs for evacuation effective dose equivalents during the and doses to populations as a function first 4 days of exposure that are of the area evacuated depends ona greater than 0.5 rem outside the variety of assumptions. Three assumed 2-mile evacuation circle for all fuel-melt accident categories, six stability classes. Data on costs versus meteorological stability classes, and the dose saved for all three accident three evacuation area models discussed categories are summarized in Table C-4 above were examined. Detailed in the next section.

assumptions and data are reported elsewhere (EP-87a). Selected data, Changes in population density including the cost per unit of collective would not affect the above results, dose to the population Figure C.l since both cost and collective dose are (person-rem) avoided, are presented in proportional to the size of' the Tables C-l, C-2, and C-3, for three population affected. Factors that could stability classes, for the median affect these results are different nuclear accident category examined assumptions for cost of evacuation, (SST-2). (SST accident categories are accident scenarios, and evacuation area described in Section E.1.2). models. The results will be directly proportional to different assumptions The data are presented for both the for the cost of evacuation. Some data total area and the incremental area on the variation with accident scenario evacuated for each change in dose level are presented in the next section. In examined. When evaluating the cost situations where different widths of per person-rem avoided for a specific evacuation area are assumed, the set of circumstances, it is appropriate change in cost per unit dose avoided to assess the ratio of the total cost to will be approximately proportional to the total dose avoided to calculate the the change in width in degrees. This average cost per person-rem avoided. approximation is more accurate for the However, when one is comparing the higher stability classes (Eand F).

cost versus dose avoided to make a Evacuation within. a 2 mile radius judgment between a variety of different circle and a 90 degree sector in the limiting dose values, it is appropriate downwind direction is generally to compare the dose savings and costs considered to be adequate for release C-5

2 MILE RADIUS

' .. . AREA WHERE PLUME

. '.' -,:' PAGs ARE EXCEEDED

~. AREA EVACUATED*

FIGURE C-1. EVACUATION MODEL.

C-6

Table C-1 Costs for Implementing Various PAGs for an SST-2 Type Accident (Stability Class A)

Total Area Marginal Area Evacuation PAG angle value Dose Dollars! A Dose A Dollars/

(degrees) (rem) Cost A Cost avoided person-rem avoided Aperson-rem (dollars) (dollars)

(person-rem) avoided (person-rem) avoided 70 0.5 2.83E+7 8.97E+4 315 2.16E+7 4.91E+4 440 1 6.68E+6 4.06E+4 164 5.19E+6 2.33E+4 223 2 1.49E+6 1.73E+4 88

1. 19E+6 1.21E+4 98 5 2.99E+5 5.22E+3 57 (a) (a) (a) 9.70E+4 2.44E+3 40 10 90 0.5 3.63E+7 9.29E+4 391 2.78E+7 5.05E+4 550 1 8.54E+6 4.24E+4 201 6.68E+6 2.42E+4 276 2 1.86E+6 1.82E+4 102 1.54E+6 1.28E+4 120 5 3.26E+5 5.41E+3 60 (a) (a) (a) 1.25E+5 2.63E+3 47 10 180 0.5 7.16E+7 9.33E+4 767 5.49E+7 5.06E+4 1080 1 1.67E+7 4.27E+4 391 1.32E+7 2.43E+4 543 2 3.48E+6 1.84E+4 190 3.04E+6 1.29E+4 235 5 4.48E+5 5.46E+3 82 (a) (a) 2.47E+5 2.68E+3 92 10 (a) a The 4-day dose does not exceed the PAG outside the 2-mile radius of the accident site.

The total cost of evacuation within this radius is 2.02E+5 dollars;. the total dose avoided is 2.78E+3 person-rem; and the. total cost per person-rem avoided is $73.

C-7

Table C-2 Costs for Implementing Various PAGs for an SST-2 Type Accident (Stability Class C)

Total Area Marginal Area Evacuation PAG angle value Dose Dollars! 11 Dose 11 Dollars!

(degrees) (rem) Cost 11 Cost avoided person-rem avoided I1person-rem (dollars) (dollars)

(person-rem) avoided (person-rem) avoided 70 0.5 4.95E+7 1. 13E+5 439 3.71E+7 4.95E+4 750 1 1.23E+7 6.31E+4 195 9.87E+6 2.58E+4 382 2 2.46E+6 3.73E+4 66 1.68E+6 1.02E+4 165 5 7.82E+5 2.71E+4 29 3.89E+5 6.15E+3 63 10 3.93E+5 2.10E+4 19 1.32E+5 4.75E+3 28 20 2.60E+5 1.62E+4 16 50 (a) (a) (a) 3.40E+4 2.50E+3 10 90 0.5 6.35E+7 1.13E+5 564 4.77E+7 4.95E+4 964 1 1.58E+7 6.32E+4 250 2 1.27E+7 2.58E+4 491 3.11E+6 3.74E+4 83 2.16E+6 1.02E+4 212 5 9.48E+5 2.72E+4 35 10 5.00E+5 6.16E+3 81 4.47E+5 2.10E+4 21 1.70E+5 4.76E+3 36 20 2.77E+5 1.63E+4 17 (a) (a) (a) 3.40E+4 2.50E+3 14 50 180 0.5 1.25E+8 1.13E+5 1110 9.44E+7 4.95E+4 1910 1 3.10E+7 6.32E+4 491 2.51E+7 2.58E+4 971 2 5.95E+6 3.74E+4 159 4.28E+6 1.02E+4 419 5 1.68E+6 2.72E+4 62 9.90E+5 6.16E+3 161 10 6.87E+5 2.10E+4 33 3.36E+5 4.77E+3 70 20 3.51E+5 1.63E+4 22 (a) (a) (a) 6.70E+4 2.50E+3 27 50 a The 4-day dose does not exceed the PAG outside the 2-mile radius of the accident site.

The total cost of evacuation within this radius is 2.02E+5 dollars; the total dose avoided is 2.78E+3 person-rem; and the total cost per person-rem avoided is $73.

C-8

Table C-3 Costs for Implementing Various PAGs for an SST-2 Type Accident (Stability Class F)

Total Area Marginal Area Evacuation PAG angle value Dose Dollars! !J..Dose Il Dollars!

(degrees) (rem) Cost !J.. Cost avoided person-rem avoided !J.. person-rem (dollars) (dollars)

(person-rem) avoided (person-rem) avoided 70 0.5 8.95E+7 4.61E+5 194 4.01E+7 1.98E+4 2020 1 4.95E+7 4.41E+5 112 2.12E+7 2.17E+4 977 2 2.83E+7 4.19E+5 67 1.59E+7 3.66E+4 436 5 1.23E+7 3.83E+5 32 5.65E+6 2.93E+4 193 10 6.68E+6 3.53E+5 19 3.03E+6 3.18E+4 95 20 3.65E+6 3.22E+5 11 9.70E+5 3.10E+4 32 50 1.49E+6 2.68E+5 5.6 90 0.5 1.15E+8 4.61E+5 250 5.15E+7 1.98E+4 2600 1 6.35E+7 4.41E+5 144 2.72E+7 2.17E+4 1260 2 3.63E+7 4.19E+5 87 2.05E+7 3.66E+4 560 5 1.58E+7 3.83E+5 41 7.26E+6 2.93E+4 248 10 8.54E+6 3.53E+5 24 3.90E+6 3. 18E+4 123 20 4.64E+6 3.22E+5 14 1.30E+6 3.1OE+4 41 50 1.86E+6 2.68E+5 6.9 180 0.5 2.27E+8 4.61E+5 493 1.02E+8 1.99E+4 5120 1 1.25E+8 4.41E+5 285

.5.39E+7 2.17E+4 2480 2 7. 16E+7 4.19E+5 171 4.05E+7 3.66E+4 1110 5 3.10E+7 3.83E+5 . 81 1.44E+7 2.92E+4 492 10 1.67E+7 3.53E+5 47 7.71E+6 3.18E+4 242 20 8.98E+6 3.22E+5 28 2.40E+6 3.10E+4 80 50 3.51E+6 2.68E+5 13 C-9

durations not exceeding a few hours from 0.15 to 0.8 rem, with 0.5 rem and where reliable wind direction being representative of most situations.

forecasts are available. From these data we conclude that, based on the cost of evacuation, a P AG larger than the range of values 0.5 to 5 C.2.1.3 Conclusions rem would be incompatible with Principle 3.

As shown in Tables C-l, C-2, and C-3 for an SST-2 accident, the cost per unit dose avoided is greatest for wide C.2.2 Risk of Evacuation angle evacuation and for the most stable conditions, class (F). Although a Principle 4 requires that the risk of few emergency plans call for evacuation the protective action not exceed the over wider angles (up to 360 degrees), risk associated with the dose that will the model shown in Figure C-l with a be avoided. Risk from evacuation can 90 degree angle is most common. come from several sources, including (1) transportation incidents for both To estimate an upper bound on dose pedestrians and vehicle passengers, (2) for evacuation based on cost, we first exposure to severe weather conditions consider common values placed on or a competing disaster, and (3), in the avoiding risk. As one input into its case of immobile persons, anxiety, risk management decisions, EPA has unusual activity, and separation from used a range of $400,000 to $7,000,000 medical care or services. The first as an acceptable range of costs for source, transportation incidents, is the avoiding a statistical death from only category for which the risk has pollutants other than radiation. For a been quantified. An EPA report risk of 3xl0*4 cancer deaths per (HA-75) evaluated the risk of person-rem (see Appendix B), these transportation fatalities associated dollar values are equivalent to a range with emergency evacuations that have of from about $120 to $2,000 per actually occurred and concluded that person-rem avoided. These values can the risk of death per mile traveled is be compared to the marginal about the same as that for routine cost-effectiveness (dollars per automobile travel. Using this as a person-rem) of evacuation over an basis, the risk of death from travel is angle of 90 degrees. The resulting about 9x10*8 deaths per person-mile, or ranges of upper bounds on dose are 9x10* 6 deaths per person for the shown in Table C-4 for SST-I, SST-2, 100-mile round trip assumed for and SST-3 accident scenarios. The evacuation. Assuming a risk of fatal maximum upper bounds (based on cancer from radiation of approximately minimum costs for avoiding risk) range 3x10*4 per person-rem; such an from 1 to 10 rem, with most values evacuation risk is equivalent to a dose being approximately 5 rem. The of about 0.03 rem.

minimum upper bounds (based on maximum costs for avoiding risk) range C-10

Table C-4 Upper Bounds on Dose for Evacuation, Based on the Cost of Avoiding Fatalitiesa Dose Upper Boundsb,c Accident Atmospheric Maximum . Minimum Category Stability Class (rem) (rem)

SST-1 A 5 0.4 C 5 0.4 F 10 0.8 SST-2 A 1 0.15 C 3.5 0.25 F 10 0.7 SST-3 A (d) (d)

C (d) (d)

F 5 0.45 a Based on data from EP-87a.

b Windspeeds typical of each stability class were chosen.

c Based on an assumed range of $400,000 to $7,000,000 per life saved.

d For stability classes A and C, the dose from an SST-3 accident is not predicted to exceed 0.5 rem outside a 2-mile radius. It is assumed that evacuation inside this radius would be carried out based on the emergency condition on the site. No differential evacuatic;m costs were calculated within this area.

l In comparing this risk (or, more centerline. To assure. that these exactly, its equivalent in dose) to the individuals will be protected, it is risk avoided by evacuation, it is necessary that others on either side important to note that protective action take protective action at exposures that must be implemented over a larger are less than at the plume centerline, population than will actually be and, in some cases, are zero. Thus, the exposed at the level of the PAG. entire evacuated population could Because of uncertainty or incur, on the average, a risk from the unpredictable changes in wind protective action which exceeds the risk direction, the exact location of the of the radiation dose avoided.

plume will not be precisely known. Although it is not possible to assure Dose projections are made for the that no individuals incur risks from maximum exposed individuals - those evacuation greater than their radiation at the assumed location of the plume risks, we can assure that this does not C-ll

occur, on the average, at the outer of transportation, if the centerline dose margin of the evacuation area. For avoided is at or above 0.5 rem.

this reason, we also examined the average dose avoided for the As previously discussed, hazardous incrementally evacuated population for environmental conditions (e.g., severe various choices of evacuation levels. weather or a competing disaster) could Table C-5 presents the results, which create transportation risks from are derived from the data in Tables evacuation that would be higher than C-l, C-2, and C-3. For the levels normal. It is therefore appropriate to analyzed, the average dose avoided is make an exception to allow higher always significantly greater than 0.03 projected doses for evacuation decisions rem. We conclude, therefore, that the under these circumstances. In the choice of PAGs will not be influenced absence of any definitive information by Principle 4, for persons in the on such higher risks from evacuation, general population whose risk from we have arbitrarily assumed that it evacuation is primarily the normal risk would be appropriate to increase the Table C-5 Average Dose Avoided per Evacuated Individual for Incremental Dose Levels for Evacuation Average dose avoided (rem per Centerline dose individual) by stability class (rem)

A C F 0.5 to 1 0.34 0.19 0.07 1 to 2 0.67 0.38 0.15 2 to 5 0.87 0.33 5 to 10 0.75 recommended projected dose for at higher risk from evacuation than are evacuation of the general population average members of the population. It under hazardous environmental would be appropriate to adopt higher conditions up to a factor of 5 higher PAGs for evacuation of individuals who than that used under normal would be at greater risk from environmental conditions. evacuation itself than for the typically healthy members of the population, It is also recognized that those who are at low risk from evacuation.

persons who are not readily mobile are In the absence of definitive information C-12

on the higher risk associated with the year of age be considered for thyroid evacuation of this group, we have blocking in r~diation emergencies in arbitrarily assumed that it is those persons who are likely to receive appropriate to adopt PAGs a factor of a projected radiation dose of 25 rem or five higher for evacuation of high risk greater to the thyroid gland from groups under normal environmental radioiodines released into the conditions. If both conditions exist, environment. . To have the greatest (high risk groups and hazardous effect in decreasing the accumulation of environmental conditions) projected radioiodine in the thyroid gland, these doses up to 10 times higher than the doses .of potassiu,m iodide' should be P AGs for evacuation of the general admimstered irtunediately before or population under normal conditions after exposure. If a person is exposed may be justified. These doses are to radioiodine when circumstances do expected to satisfy Principle 4 without not permit the immediate violating Principles 1 and 3. Although administration of potassium iodide, the they violate Principle 2, Principle 4 initial administration will still have becomes, for such cases, the overriding substantial benefit even ifit is taken 3 consideration. or 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> after acute exposure".

Evacuation and sheltering are, however, preferred alternatives for C.2.3 Thyroid Blocking most situations because, they provide protection for the whole body .

The ingestion of stable potassium and avoid the risk of misapplication of iodide (KI) to block the uptake of potassium iodide.

radioiodine by the thyroid has been identified as an effective protective The Fe'deral Emergency action. The Food and Drug Management Agency ha~ published a Administration (FDA) analyzed Federal policy developed by the Federal available information on the risk of Radiological Preparedness Coordinating radioiodine-induced thyroid cancers Committee regarding the use of KI as and the incidence and severity of side a protective action CFE-85). In effects from potassium iodide (FD-82). summary, the policy recommends the They concluded "... risks from the stock-piling of KI and distribution short-term use of relatively low doses during emergencies to emergency of potassium iodide for thyroid blocking workers and institutionalized persons, in a radiation emergency are but does not recommend requiring outweighed by the risks of stockpiling or distribution to the radioiodine-induced thyroid nodules or general public. The policy recognizes, cancer at a projected dose to the however, that options on the thyroid gland of 25 rem. FDA distribution and use of KI rests with recommends .that potassium iodide in the States and, hence, the policy doses of 130 milligrams (mg) per day statement permits State and local for adults and children above 1 year governments, within the limits of their and 65 mg per day for children below 1 authority, to. take measures beyond C-13

those recommended or required The protection factor may be nationally. characterized by a dose reduction factor (DRF), defined as:

C.2.4 Sheltering DRF = dose with protective action dose without protective action Sheltering means staying inside a structure with doors and windows The shielding characteristics of most closed and, generally, with exterior structures for gamma radiation can be ventilation systems shut off. categorized based on whether they are Sheltering in place (i.e. at or near the "small" or "large." Small structures are location of an individual when the primarily single-family dwellings, and incident occurs) is a low-cost, low-risk large structures include office, protective action that can provide industrial, and commercial buildings.

protection with an efficiency ranging The typical attenuation factors given in from almost 100 percent to zero, Table C-6 show the importance of the depending on the circumstances. It can type of structure for protection from also be particularly useful to assure external gamma radiation (EP-78a). If that a population is positioned so that, the structure is a wood frame house if the need arises, communication with without a basement, then sheltering the population can be carried out from gamma radiation would provide a expeditiously. The degree of protection DRF of 0.9; i.e., only 10 percent of the provided by a structure is governed by dose would be avoided. The DRFs attenuation of radiation by structural shown in Table C-6 are initial values components (the mass ofwalls , ceilings, prior to infiltration of contaminated etc.) and by its outside/inside air- air, and therefore apply only to short exchange rate. These two protective duration plumes. The values will characteristics are considered increase with increasing time of separately. exposure to a plume because of the increasing importance of inside-outside air exchange. However, this reduction Table C-6 Representative Dose Reduction Factors for External Radiation Effectiveness Structure DRF (percent)

Wood frame house (first floor) 0.9 10 Wood frame house (basement) 0.6 40 Masonry house 0.6 40 Large office or industrial building 0.2 or less 80 or better C-14

in efficiency is not dramatic for source L = ventilation rate (hOI), and terms involving primarily gamma radiation, because most of the dose t = elapsed time (h).

arises from outside, not from the small volume of contaminated air inside a Typical values for ventilation rates shelter. Therefore, most shelters will range from one-fifth to several air retain their efficiency as shields exchanges pet hour. In the absence of against gamma radiation, even if the measurements, an air exchange rate of concentration inside equals the 1.0/h may be assumed for structures concentration outside. with no special preparation except for closing the doors and windows. An air The second factor is the exchange rate of 0.3/h is appropriate inside/outside air exchange rate. This for relatively air-tight structures, such factor primarily affects protection as well-sealed residences, interior against exposure by inhalation of rooms with doors chinked and no airborne radionuclides with half lives windows, or large structures with long compared to the air exchange rate. ventilation s4ut off. Using the above The factor is expressed as the number model to calculate indoor concentration of air exchanges per hour, L (hoI), or relative to outdoor concentration after the volume of fresh air flowing into and one, two, and four complete air out of the structure per hour divided by exchanges, the indoor concentration the volume of the structure. Virtually would be about 64 percent, 87 percent, any structure that can be used for and 98 percent of the outside sheltering has some degree of concentration, respectively. It is outside/inside air exchange due to apparent that staying in a shelter for natural ventilation, forced ventilation, more time than that required for one or or Uncontrollable outside forces, two complete air exchanges is not very primarily wind. effective for reducing inhalation exposure.

Assuining constant atmospheric and source conditions and no effects from The inhahition DRF is equal to the filtration, deposition, or radioactive ratio of the average inside to outside decay, the following model can be used air concentration over the period of to estimate the buildup of indoor sheltering. Studies have been concentration of radioactivity, for a conducted of :typical ventilation rates given outdoor concentration, as a for dwellings (EP-78a) and for large function of time after appearance of the commercial structures (GR-86). In plume and of ventilation rate: each case the rate varies according to the air tightness of the structure, windspeed, and the indoor-to-outdoor temperature difference. For the where q = concentratiC?n inside, purpose of deriving P AGs, average ventilation rates were chosen for the Co = concentration outside, two types of structures that are of C-15

greatest interest. Table C-7 shows than a 10 percent increase in the dose calculated dose reduction factors for received during plume passage, inhalation exposure as a function of (EP-78b)), but can be greater for plume duration, for beta-gamma source inhalation dose.

terms, assuming average ventilation rates for these structures. Doses from inhalation during sheltering can be reduced in several A potential problem with sheltering ways, including reducing air exchange is that persons may not leave the rates by sealing cracks and openings shelter as soon as the plume passes with cloth or weather stripping, tape, and, as a result, will receive exposure etc., and filtering the inhaled air with from radioactive gases trapped inside. commonly available items like wet The values for DRFs tabulated in Table towels and handkerchiefs. Analyses for C-7 ignore this potential additional some hypothesized accidents, such as contribution. This effect is generally short-term transuranic releases, show minor for gamma dose (generally less that sheltering in residences and other Table C-7 Dose Reduction Factors for Sheltering from Inhalation of Beta-Gamma Emitters Ventilation rate Duration of (air changes/h) plume exposure(h) DRF 0.3a 0.5 0.07 1 0.14 2 0.25 4 0.41 6 0.54 1.0b 0.5 0.21 1 0.36 2 0.56 4 0.75 6 0.83

-Applicable to relatively "airtight" structures such as well- sealed residences, interior rooms with chinked doors and no windows, or large structures with outside ventilation shut off.

bApplicable to structures with no special preparation except for closing of doors and windows.

C-16

buildings can be more effective than for (avoidance of acute health effects) is beta-gamma emitters, may provide assured by the low risk required to adequate. protection, and may be more satisfy Principle 2, and thus requires effective than evacuation when no additional consideration. Principle evacuation cannot be completed before 2 (acceptable , risk of delayed health plume arrival (DO-90). However, effects) leads to the choice of 0.5 rem as sheltering effectiveness for the an upper bound on the avoided dose inhalation exposure pathway can be below which evacuation of the general reduced drastically by open windows population is justified under normal and doors or by forced air ventilation. conditions. This represents a risk of Therefore, reliance on protection about 2E-4 of fatal cancer. Maximum assumed to be afforded based on large lifetime risk levels considered dose reduction factors for sheltering acceptable by EPA from routine should , be accompanied by cautious operations of individual sources range examination of, possible failure from 1E-6 to 1E-4. Risk levels that are mechanisms, and, except in very higher than this must be justified on unusual circumstances, should not be the basis of the emergency nature of a relied upon at projected doses greater situation. In this case, we judge that than 10 rem. Such analysis should be up to an order of magnitude higher based on realistic or "best estimate" combined risk from all phases of an dose models and include consideration incident may be justifiable. The choice of unavoidable dose if evacuation were of 0.5 rem avoided dose as an carried out. appropriate criterion for an acceptable level of risk during the early phase is a subjective judgment that includes C.3 Recommended PAGs for Exposure consideration. of possible contributions toa Plume during the Early Phase from exposure during other phases of the incident, as well as the possibility The four principles which form the that risk estimates may increase basis for the selection of PAG values moderately in the near future as a are presented in Chapter 1. The risks result of current reevaluations of of health effects from radiation that are radiation risk.

relevant to satisfying Principles 1 and 2 are presented in Appendix Band Principle 4 (risk from the protective analyses of the costs and risks action must be less than that from the associated with evacuation relative to radiation risk avoided) supplies a lower Principles 3 and 4 have been presented bound of 0.03 rem on the dose at which in this appendix. These results, for evacuation of most members of the application to the early phase, are public is justified. Finally, under summarized in Table C-8. Principle 3 (cost/risk considerations) evacuation is justified only at values The following describes how these equal to or greater than 0.5 rem. This results lead to the selection of the will be limiting unless lower values are P AGs. Conformance to Principle 1 required for purely health-based C-17

Table C-8 Summary of Considerations for Selecting the Evacuation PAGs.

Dose Consideration Principle Section (rem) 50 Assumed threshold for acute health effects in adults. 1 B.2.1.4 10 Assumed threshold for acute health effects in the fetus. 1 B.2.1A 5 Maximum acceptable dose for normal occupational exposure of adults. 2 C.5 5 Maximum dose justified to average members of the population, based on the cost of evacuation. 3 C.2.1.3 0.5 Maximum acceptable dose to the general population from all sources from nonrecurring, non-accidental exposure. 2 BAA 0.5 Minimum dose justified to average members of the population, based on the cost of evacuation. 3 C.2.1.3 0.5 Maximum acceptable dose a to the fetus from occupational exposure of the mother. 2 C.5 0.1 Maximum acceptable dose to the general population from all sources from routine (chronic),

nonaccidental exposure. 2 BAA 0.03 Dose that carries a risk assumed to be equal to or less than that from evacuation. 4 C.2.2 vrhis is also the dose to the 8- to 15-week-old fetus at which the risk of mental retardation is assumed to be equal to the risk of fatal cancer to adults from a dose of 5 rem.

C-18

reasons (Principle 2). But this is not doses (i.e. the weighted sum of doses to the case. The single lower purely all organs). As discussed in previous health-based value, 0.1 rem, is only sections, it may be appropriate to valid as a health-based criterion for further limit dose to the thyroid and chronic exposure. skin, to adjust the value for special groups of the. population at unusually In summary, we have selected the high risk from evacuation, and to value 0.5 rem as the avoided dose provide for situations in which the which justifies evacuation, because 1) it general population may be at higher limits the risk of delayed effects on than normal risk from evacuation.

health to levels adequately protective of These are addressed, in turn, below.

public health under emergency conditions, 2) the cost of In the case of exposure of the implementation of a lower value is not thyroid to radioiodine, action based justified, and 3) it satisfies the two solely on effective dose would not occur bounding requirements to avoid acute until a thyrQid dose about 33 times radiation effects and to avoid higher than the corresponding effective increasing risk through the protective dose to the entire body. As noted in action itself. We note that this choice Section BA.l.l, because the weighting also satisfies the criterion for factor for thyroid used to calculate acceptable risk to the fetus of effective dose, does not reflect the high occupationally exposed mothers (as ratio of curable to fatal thyroid cancers, well as falling well below dose values protective action to limit dose to the at which abortion is recommended). thyroid is recommended at a thyroid dose 5 times the numerical value of the As noted in Section C.2A, we PAG.

assume that the dose normally avoidable by evacuation (the dose that Similarly, ,since effective dose does is not avoided by the assumed not include dose to the skin, and for alternative of sheltering) is one half of other reasons discussed in Section the projected dose. The value of the BA.1.2, protective action to limit dose P AG for evacuation of the general to skin is recommended at a skin dose public under normal circumstances is 50 times the numerical value of the therefore chosen as one'rem projected P AG. As in. the case of the thyroid, sum of the committed effective dose this includes ,consideration of the risk equivalent from inhalation of of both curable and noncurable cancers.

radionuclides and effective dose equivalent from exposure to external Special risk groups include fetuses, radiation. ' and persons who are not readily mobile. As noted in Sections BA.1.3 The above considerations apply to and B3, we assume that the risk of evacuation of typical members of the radiation-induced cancer is about 5 to population under normal 10 times higher for fetuses than for circumstances, and apply to effective adults and that the risk of mental C-19

retardation in fetuses exposed during which sheltering is no longer justified the 8th to 15th weeks of gestation is because of its cost or the risk about 10 times higher than the risk of associated with its implementation.

fatal cancer in equivalently exposed Sheltering will usually have other adults. However, due to the difficulty benefits related to emergency of rapidly evacuating only pregnant communication with members of the women in a population, and the public. It is expected that protective assumed higher-than-average risk action planners and decision associated with their evacuation, it is authorities will take into account the not considered appropriate to establish added benefits of sheltering (e.g.,

separate PAGs for pregnant women. communication and established We note that the PAG is chosen planning areas) for decisions on sufficiently low to satisfy Federal sheltering at levels below 0.5 rem.

guidance for limiting exposure of the fetus in pregnant workers. Bathing and changing of clothing are effective for reducing beta dose to Higher P AGs for situations the skin of persons exposed to an involving higher risks from evacuation airborne plume of radioactive were discussed in Section C.2.2. Under materials. Since these are also normal, low-risk, environmental low-cost, low-risk actions, no PAG is conditions, P AGs for evacuation of recommended for initiating their groups who present higher than implementation. It is expected that average risks from evacuation (e.g., any persons exposed in areas where persons who are not readily mobile) are evacuation is justified based on recommended at projected doses up to projected dose from inhalation will be 5 rem. Evacuation of the general routinely advised by emergency population under high-risk response officials to take these actions environmental conditions is also within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> after exposure.

recommended at projected doses up to 5 rem. If evacuation of high risk The use of stable iodine to protect groups under hazardous environmental against uptake of inhaled radioiodine conditions is being considered, by the thyroid is recognized as an projected doses up to 10 rem may, effective alternative to evacuation for therefore, be justified. situations involving radioiodine releases where evacuation cannot be Short-term sheltering is recognized implemented. If procedures are as a low-cost, low-risk, protective action included in the applicable emergency primarily suited for protection from response plan, use of stable iodine exposure to an airborne plume. should be considered for any such Sheltering will usually be clearly situation in which evacuation or justified to avoid projected doses above sheltering will not be effective in 0.5 rem, on the basis of avoidance of preventing thyroid doses of 25 rem (see health risks. However, data are not also C.2.3).

available to establish a lower level at C-20

C.4 Comparison to Previous PAGs airborne. release were calculated for radionuclide mixes postulated for three This section compares the level of nuclear power plant accident protection provided by the previously sequences. The doses were then published P AGs for evacuation (one normalized for each accident so that rem external gamma dose from the they represent a location in the plume and 5 rem committed dose to the environment where the controlling dose thyroid from inhalation, under normal would be equal to the current PAG.

evacuation circumstances) with this These results are shown in Table C-9.

P AG. The effective dose addressed by this PAG, as well as skin,. thyroid, and Based on the results shown in Table external gamma doses from the plume C-9, the following conclusions are during the early phase from the three major exposure pathways for an Table C-9. Comparison of Projected Doses for Various Reactor Accident Scenariosa Accident Effective dose Skin dosed Thyroid dose e External categori' equivalent C (rem) (rem) dosef (rem) (rem)

SST-1 0.7 6 5 0.02 SST-2 1 5 5* 0.4 SST-3 0.4 6 5 0.1 aDoses are normalized to the limiting PAG.

bS ee Table E-1 for a description of these accident scenarios.

'The dose is the sum of doses from 4-day exposure to external gamma radiation from deposited materials, external exposure to the plume,and the committed effective dose equivalent from inhalation of the plume.

~he dose equivalent fro~ external beta radiation from the plume and from 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> exposure to materials deposited on skin and clothing.

eCommitted dose equivalent to the thyroid from inhalation.

fExternal gamma dose equivalent from the plume.

C-21

apparent, for the accident sequences condition of their employment.

analyzed: Examples of occupations that may be affected include law enforcement,

1. The PAG for the thyroid is firefighting, radiation protection, civil controlling for all three accident defense, traffic control, health services, categories. For the SST-2 category, environmental monitoring, animal care, effective dose is also controlling. and transportation services. In Thus,application of the previous P AG addition, selected workers at utility, (5 rem) for thyroid would provide the industrial, and at farms and other same protection as the revised P AG for agribusinesses may be required to all three accident categories. protect others, or to protect valuable property during an emergency. The

2. Skin doses will not be controlling above are examples -- not designations for any of the accident sequences (if -- of worRers that may be exposed to bathing and change of clothing is radiation during emergencies.

completed within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> of plume passage, as assumed). Radiation exposure of workers during an emergency should normally

3. Gamma dose from direct exposure be governed by the Federal Radiation to the plume is small compared to the Protection Guidance for Occupational effective dose from the three major Exposure (EP-87). This guidance exposure pathways combined. specifies an upper bound of five rem committed effective dose equivalent per In summary, for the accident year for most workers. (Pregnant sequences analyzed, the old PAGs women, who, under this guidance provide the same level of protection as should not normally engage in work the new P AGs. For releases that situations that involve more than contain a smaller fraction radioiodines approximately 50 mrem/month, would than these accident scenarios the new normally be evacuated as part of the P AGs are slightly more protective. general population.) The guidance also specifies that doses to workers should be maintained as low as reasonably C.5 Dose Limits for Workers achievable; that doses should be Performing Emergency Services monitored; and that workers should be informed of the risks involved and of Dose limits for workers during basic principles for radiation emergencies are based on avoiding protection.

acute health effects and limiting the risk of delayed health effects, in the There are some emergency context of the need to assure protection situations, however, for which higher of the population and of valuable doses may be justified. These include properties. It is assumed that most lifesaving operations and the protection such workers are accustomed to of valuable property. International accepting an element of risk as a guidance (IC-77) recognizes two C-22

additional dose levels for workers limits for effective dose to the lens of under specially justified circumstances: the eye and 10 times the limits for two times the annual limit for any effective dose to any other organ, tissue single event, and five times the annual (including skin), or extremity of the limit in a lifetime. The dose limits body.

recommended here adopt the former value (10 rem) for operations limited to Situations may occur in which a the protection of valuable property. dose in excess of 25 rem would be The latter value (25 rem) may be required for lifesaving operations. It is permitted for situations involving not possible to prejudge the risk that lifesaving operations or activities that one person should be allowed to take to are essential to preventing substantial save the life of another. However, risks to populations. In this context persons undertaking an emergency "substantial risks" means collective mission in which the dose would exceed doses that are significantly larger than 25 rem to the whole body should do so those incurred through the protective only on a voluntary basis and with full activities engaged in by the workers. awareness of the risks involved, Workers should not operate under dose including the numerical levels. of dose limits higher than five rem unless the at which acute effects of radiation will following conditions are satisfied: be incurred and numerical estimates of the risk.of delayed effects.

1. Lower doses through the rotation of workers or other commonly-used dose The risk of acute health effects is reduction methods are not possible, discussed in B.2. Table C-I0 presents and estimated cancer mortality rates for a dose of 25 rem, as a function of age at

2. Instrumentation is available to the time of exposure. The risk of measure their exposure. cancer from moderately higher doses will increase proportionately. These In addition to the limitation on values were* calculated using risk effective dose equivalent, the dose estimates from BEIR-3 (NA-BO) as equivalent received in any year by discussed in Section BA, and life table workers under normal occupational analyses that assume the period of conditions is limited to 15 rem to the . cancer risk lasts for .the worker's lens of the eye and 50 rem to any other lifetime (BU-:Bl). The risk was organ, tissue (including skin), or calculated for the midpoint of each age extremity of the body. (Extremity is range. Roughly equivalent risks of dermed as the forearms and hands or nonfatal cancer and serious genetic the lower legs and feet (EP-B7).) By effects (if gonadal tissue is exposed) analogy to these dose limits for organs will also be incurred. .

and extremities, the limits for workers performing the various categories of The dose limits of 75 rem to the emergency services are established at whole body previously recommended by numerical values that are 5 times the EPA and 100 rem that has been C-23

recommended by NCRP (GL-57) for percent, chance of death within 60 lifesaving action represents a very high days. This is in addition to a risk of level of risk of acute and delayed about 1 in 30 of incurring fatal cancer.

health effects. A dose of 100 rem is Such high risk levels can only be expected to result in an approximately accepted by a recipient who has been 15 percent risk of temporary incap- made aware of the risks involved.

acity from nonlethal acute effects and Therefore, no absolute dose limit for an indeterminate, but less than 5 lifesaving activities is offered.

Table C-10 Cancer Risk to Emergency Workers Receiving 25 Rem Whole Body Dose Age of the Approximate risk Average years of emergency of premature death life lost if worker at time (deaths per 1,000 premature death of exposure persons exposed) occurs (years) (years) 20 to 30 9.1 24 30 to 40 7.2 19 40 to 50 5.3 15 50 to 60 3.5 11 References Buildings and Vehicles for Plutonium.

DOEIEH-0159, U.S. Department of Energy, Washington (1990).

BU-81 Bunger, B.M., J.R. Cook, EP-78a U.S. Environmental Protection and M.K Barrick. Life Table Methodology Agency. Protective Action Evaluation Part I for Evaluating Radiation Risk - An

- The Effectiveness of Sheltering as a Application Based on Occupational Protective Action Against Nuclear Accidents Exposures. Health Physics 40 (1981):439-Involving Gaseous Releases. EPA 455.

520/1-78-001A, U.S. Environmental Protection Agency, Washington (1978).

DO-90 U. S. D epa r t men t 0 f Energy. Effectiveness of Sheltering in C-24

EP-78b U.S. EnvironIllental Protection FR-64 Federal Radiation Council.

Agency. Protective Action Evaluation Part Radiation Protection Guidance for Federal II - Evacuation and Sheltering as Protective Agencies. Fed~ral Register, 29,12056-12057; Actions Against Nuclear Accidents . August 22, 1964. '

Involving Gaseous Releases. EPA 520/1-78-001B, U.S. Environmental FR-65 Federal Radiation Council.

Protection Agency, Washington (1978). Radiation Protection Guidance for Federal Agencies. Federal Register, QQ, 6953-6955; EP-87 U.S. Environmental Protection May 22, 1965.

Agency. Radiation Protection Guidance to Federal Agencies for Occupational Exposure. GL-57 Glasstone, S. The Effects of Federal Register,Q6 2822; January 27,1987. Nuclear Weapons. U.S. Atomic Energy Commission, Washington (1957).

EP-87a U.S. Environmental Protection Agency. An Analysis of Evacuation Options GR-86 Grot, R.A and AK Persily.

for Nuclear Accidents. EPA 520/1-87-023, Measured Air Infiltration Rates in Eight U.S. Environmental Protection Agency, Large Office Buildings. Special Technical Washington (1987). Publication 904, American Society for Testing and Materials, Philadelphia (1986).

FD-82 Food and Drug Administration.

Potassium Iodide as a Thyroid-Blocking IC-77 International Commission on Agent' in a Radiation Emergency: Final Radiological Protection. Radiological Recommendations On Use. Federal Register, Protection, ICRP Publication 26, Pergamon 47,28158 - 28159; June 29, 1982. Press, Oxford (1977).

FE-85 Fed era I E mer g e n c y NA-80 National Academy of Sciences.

Management Agency. Federal Policy on The Effects on Populations of Exposure to Distribution of Potassium Iodide Around* Low Levels of Ionizing Radiation: 1980.

Nuclear Power Sites for use as a Thyroidal Reports of the Committee on the Biological Blocking Agent. Federal Register,.§Q, 30256; Effects of Iohizing Radiations. National July 24, 1985. Academy Press, Washington (1980).

C-25

APPENDIXD Background for Protective Action Recommendations:

Accidental Radioactive Contamination of Food and Animal Feeds*

• This background document concerning food and animal feeds was published by the Food and Drug Administration in 1982.

APPENDIXE Protective Action Guides for the Intermediate Phase (Relocation)

Background* Information

Contents Page E.l Introduction .. . .. . .. .. .. .. .. .. . .. .. .. .. .. .. .. .. .. .. ... .. .. .. .. .. .. .. .. . .. .. .. .. .. .. .. .. .. ... .. E-l E.1.1 Response Duration .............................. E-l E.l.2 Source Term ............................. . ..... E-2

,E.1.3 Exposure Pathways . ............................. E-3 E.l.4 Response Scenario .............................. E-4 E.2 Considerations for Establishing PAGs for the Intermediate Phase . .. E-6

.E.2.1 Principles ..................................... E-8 E.2.1.1 CostlRisk Considerations .................. E-8 E.2.1.2 Protection of Special Groups ............... E-ll

.E.2.2 Federal Radiation Protection Guides ..... ' ........... E-12 E.3 Dose from Reactor Incidents ....................... ' ....... E-12 E.4 Alternatives to Relocation ................................ E-13 E.5 Risk Comparisons ....................................... E-14 E.6 Relocation PAG Recommendations .......................... E-15 E.7 Criteria for Reentry into the Restricted Zone .. .. .. .. .. .. \ .. .. . .. . .. .. .. .. .. .. E-19 References E-20 Figures E-l Response Areas E-5 E-2 Potential Time Frame of Response to a Nuclear Incident .......... E-7 E-3 Cost of Avoiding Statistical Fatalities and Exposure Rates Corresponding to'Various Total First Year Doses .... ' ........... E-10 E-4 Average Lifetime Risk of Death from Whole Body Radiation Dose Compared to the Average Risk of Accidental Death from Lifetime (47 years) Occupation in Various Industries ................... E-16 111

Tables Page E-l Brief Descriptions Characterizing Various Nuclear Power Plant Accident Types (SN-82) ................................... E-2 E-2 Release Quantities for Postulated Nuclear Reactor Accidents ....... E-3 E-3 Annual Doses Corresponding to 5 Rem in 50 Years ............. E-13 E-4 Measure of Lifetime Risk of Mortality from a Variety of Causes ... E-17 E-5 Summary of Considerations for Selecting PAGs for Relocation .... E-18 E-6 Estimated Maximum Doses to N onrelocated Persons from Areas Where the Projected Dose is 2 REM. . . . . . . . . . . . . . . . . . . . . . . .. E-20 IV

AppendixE

. Protective Action Guides for the Intermediate Phase (Relocation)

Background Information E.l Introduction information relevant to this decision, and selection of the P AG for relocation.

This Appendix provides' The Appendix concludes with a brief background information for the choice discussion of the basis for dose limits of Protective Action Guides (PAGs) for for persons temporarily reentering relocation and other protective actions areas from which the public has been to reduce exposure to deposited relocated.

radioactive materials during the intermediate phase of the response to a nuclear incident. The resulting PAGs E.l.1 Response Duration and associated implementing guidance are provided in Chapters 4 and 7, In order to decide whether to respectively. initiate relocation of the public from specifIc areas it is necessary to predict This analysis is based on the the dose that would be avoided. One

. assumption that an airborne plume of factor in this prediction is the duration radioactive material has already passed of the exposure to be avoided.

over an area and left a deposit of Relocation can begin as soon as radioactive material behind, or that patterns of exposure from deposited such material exists from some other radioactivity permit restricted areas to source, and that the public has already be identifIed. For the purpose of this been either sheltered or evacuated, as analysis, relocation of persons who necessary, on the basis ofPAGs for the have not already been evacuated from early phase of a nuclear incident, as the restricted zone is assumed to take discussed in Chapters 2 and 5. PAGs place on the, fourth day after the for subsequent relocation of the public incident. Return of evacuated persons and other protective actions, as well as to their residences outside the dose limits for persons reentering the restricted zone and transition to area from which the public is relocated, relocation status of persons already are addressed in this Appendix. evacuated is assumed to occur over a period of a week or more.

We fIrst set forth the assumptions used to derive information pertinent to The period of exposure avoided by choosing the dose level at which relocation ends when the relocated relocation of the public is appropriate. person either returns to his property or This is followed by an examination of is permanently resettled in a new E-l

location. At the time of relocation following a nuclear incident. Nuclear decisions, it will usually not be possible incidents can be postulated with a wide to predict when either of these actions range of release characteristics. The will occur. Therefore, for convenience characteristics of the source terms of dose projection, it is assumed that assumed for the development of these the period of exposure avoided is one P AGs are those postulated for releases year and that any extension beyond from various types of fuel-melt this period will be determined on the accidents at nuclear power plants basis of recovery criteria. This (SN-82). Table E-I provides brief assumption corresponds to emergency descriptions of these accident types.

response planning guidance by ICRP Radionuclide releases have been (IC-84) and IAEA (IA-85). estimated for the three most severe accident types (SST-I, SST-2, SST-3) based on postulated core inventories E.I.2 Source Term and release fractions (Table E-2). The other types (SST-4 and SST-5) would The "source term" for this analysis generally not produce offsite doses from is comprised of the quantities and exposure to deposited material types of particulate radioactive sufficient to warrant consideration of material found in the environment relocation.

Table E-I Brief Descriptions Characterizing Various Nuclear Power Plant Accident Types (SN-82)

Type Description SST-I Severe core damage. Essentially involves loss of all installed safety features. Severe direct breach of containment.

SST-2 Severe core damage. Containment fails to isolate. Fission product release mitigating systems (e.g., sprays, suppression pool, fan coolers) operate to reduce release.

SST-3 Severe core damage. Containment fails by base-mat melt-through. All other release mitigation systems function as designed.

SST-4 Modest core damage. Containment systems operate in a degraded mode.

SST-5 Limited core damage. No failures of engineered safety features beyond those postulated by the various design basis accidents. Containment is assumed to function for even the most severe accidents in this group.

E-2

Table E-2 Release Quantities for Postulated Nuclear Reactor Accidents Principal radionuclides Estimated quantity releaseda contributing (Curies) to dose from Half-life deposited (days)

SST-1 SST-2 SST-3 materials Zr-95 6.52E+1 1.4E+6 4.5E+4 1.5E+2 Nb-95 3.50E+1 1.3E+6 4.2E+4 1.4E+2 Ru-103 3.95E+1 6.0E+6 2.4E+5 2.4E+2 Ru-106 3.66E+2 1.5E+6 5.8E+4 5.8E+1 Te-132 3.25 8.3E+7 3.9E+6 2.6E+3 1-131 8.05 3.9E+7 2.6E+5 1.7E+4 CS-134 7.50E+2 8.7E+6 1.2E+5 1.3E+2 CS-137 1.10E+4 4.4E+6 5.9E+4 6.5E+1 Ba-140 1.28E+1 1.2E+7 1.7E+5 1.7E+2 La-140 1.67 1.5E+6 5.lE+4 1.7E+2 aBased on the product of reactor inventories of radionuclides and estimated fractions released for three accident categories (SN-82).

For other types of source terms, lived radionuclides would be released.

additional analysis may be necessary to Consequently, doses due to deposited assure adequate protection. For materials from such accidents would be example, if the release includes a large relatively high during the first year proportion of long-lived radionuclides, followed by long term exposures at doses will continue to be delivered over lower rates.

a long period of time, and, if no remedial actions are taken, the dose delivered in the first year may E.1.3 Exposure Pathways represent only a small portion of the total dose delivered over a lifetime. On The principal exposure pathway to the other hand, if the release consists members of the public occupying land primarily of short-lived radionuclides, contaminated by deposits of radioactive almost the entire dose may be materials from reactor incidents is delivered within the first year. expected to be exposure of the whole body to external gamma radiation.

From the data in Table E-2, it is Although it is normally expected to be apparent that, for the groups of of only minor importance, the accidents listed, both long and short inhalation pathway would contribute E-3

additional doses to internal organs. use in making decisions to protect* the The health risks from other pathways, public. Sheltering, evacuation, and such as beta dose to the skin and direct other actions taken to protect the ingestion of dirt, are also expected to public from the plume will have be minor in comparison to the risks already been implemented. The tasks due to external gamma radiation immediately ahead will be to (1) define (AR-89). Skin and inhalation dose the extent and characteristics of would, however, be important exposure deposited radioactive material and pathways for source terms with identify a restricted zone in accordance significant fractions of pure beta with the PAG for relocation, (2) emitters, and inhalation dose would be relocate persons from and control important for source terms with access to the restricted zone, (3) allow significant fractions of alpha emitters. persons to return to areas outside the restricted zone, (4) control the spread Since relocation, in most cases, of and exposure to surface would not be an appropriate action to contamination, and (5) apply simple prevent radiation exposure from decontamination and other low-cost, ingestion of food and water, these low-risk techniques to reduce the dose exposure pathways have not been to persons who are not relocated.

included in this analysis. They are' addressed in Chapters 3 and 6. In Because of the various source term some instances, however, where characteristics and the different withdrawal of food and/or water from protective actions involved (evacuation, use would, in itself, create a, health sheltering, relocation, decontamination, risk, relocation may be an appropriate and other actions to reduce doses to "as alternative protective action. In this low as reasonably achievable" levels),

case, the committed effective dose the response areas for different equivalent from ingestion should be protective actions may be complex and added to the projected dose from may vary in size with respect to each deposited radionuclides via other other. Figure E-1 shows a generic pathways, for decisions on relocation. example of some of the principal areas involved. The area covered by the plume is assumed to be represented by E.1.4 Response Scenario area 1. In reality, variations in meteorological conditions would almost This section defines the response certainly produce a more complicated zones, population groups, and the shape.

activities assumed for implementation of protective actions during the Based on plant conditions or other intermediate phase. considerations prior to or after the release, members of the' public are After passage of the radioactive assumed to have already been plume, the results of environmental evacuated from area 2 and sheltered in monitoring will become available for area 3. Persons who were evacuated or E-4

~--"",."",."",.

---

~

PLUME TRAVEL'"

DIRECTION tt:l I

C11 ARBITRARY SCALE ----------

LEGEND

.--,I I 1. PLUME DEPOSITION AREA.

1.-.1

~ 2. AREA FROM WHICH POPULATION IS EVACUATED.

~ 3. AREA IN WHICH POPULATION IS SHELTERED.

m 4. AREA FROM WHICH POPULATION IS RELOCATED (RESTRICTED ZONE).

FIGURE E-1. RESPONSE AREAS.

sheltered as a precautionary action for E.2 Considerations for Establishing protection from the plume but whose P AGs for the Intermediate Phase homes are outside the plume deposition area (area 1) are assumed to return to The major considerations In their homes or discontinue sheltering selecting values for these P AGs for when environmental monitoring relocation and other actions during the verifies the outer boundary of area 1. intermediate phase are the four principles that form the basis for Area 4 is the restricted zone and is selecting all P AGs. Those are defined as the area where projected discussed in Section E.2.1. Other doses are equal to or greater than the considerations (Federal radiation relocation P AG. The portion of area 1 protection guidance and risks outside of area 4 is designated as a commonly confronting the public) are study zone and is assumed to be discussed in Sections E.2.2 and E.5.

occupied by the public. However, contamination levels may exist here In addition, a planning group that would be of concern for continued consisting of State, Federal, and monitoring and decontamination to industry officials provided maintain radiation doses "as low as recommendations in 1982 which EPA reasonably achievable" (ALARA). considered in the development of the format, nature, and applicability of The relative positions of the P AGs for relocation. Abbreviated boundaries shown in Figure E-1 are versions of these recommendations are dependent on areas evacuated and as follows:

sheltered. For example, area 4 could fall entirely inside area 2 (the area a. The PAGsshould apply to evacuated) so that relocation of persons commercial, light-water power reactors.

from additional areas would not be required. In this case, the relocation b. The P AGs should be based PAG would be used only to determine primarily on health effects.

areas to which evacuees could return.

c. Consideration should be given to Figure E-2 provides, for establishing a range of PAG values.

perspective, a schematic representation of the response activities expected to be d. The P AGs should be established as in progress in association with high as justifiable because at the time implementation of the PAGs during the of the response, it would be possible to intermediate phase of the response to a lower them, if justified, but it probably nuclear incident. would not be possible to increase them.

e. Only two zones (restricted and unrestricted) should be established to simplify implementation of the PAGs.

E-6

CONDUCT AERIAL AND GROUND SURVEYS. DRAW IS':>DOSE RATE LINES.

IDENTIFY HIGH DOSE RATE AREAS. CHARACTERIZE CONTAMINATION.

RELOCATE POPULATION FROM HIGH DOSE RATE AREAS.

~ ALLOW IMMEDIATE RETURN OF EVACUEES TO NONCONTAMINATED AREAS.

I PERIOD OF ESTABLISH RESTRICTED ZONE BOUNDARY AND CONTROLS.

~

Q RELOCATE REMAINING POPULATION FROM WITHIN RESTRICTED ZONE.

w U)

RELEASE, w

GRADUALLY RETURN EVACUEES UP TO RESTRICTED ZONE BOUNDARY .

a: ..J

) DISPERSION, 0. ~~ CONDUCT D-CON AND SHIELDING EVALUATIONS AND ESTABLISH PROCEDURES 0 :E FOR REDUCING EXPOSURE OF PERSONS WHO ARE NOT RELOCATED.

0 0 0 DEPOSITION, 0

...z SHELTERING, z PERFORM DETAILED ENVIRONMENTAL MONITORING .

tz:j

, w 0 PROJECT DOSE BASED ON DATA.

-...l Q ~

0 EVACUATION, in DECONTAMINATE ESSENTIAL FACILITIES AND THEIR ACCESS ROUTES.

~~

0 0 00( 0. RETRIEVE VALUABLE AND ESSENTIAL RECORDS AND POSSESSIONS.

AND ACCESS w Q

CONTROL REESTABLISH OPERATION OF VITAL SERVICES.

~ BEGIN RECOVERY ACTIVITIES.

(NO TIME SCALE)

MONITOR AND APPLY ALARA IN OCCUPIED _~

CONTAMINATED AREAS.

0.1 1.0 10 100 1,000 TIME AFTER DEPOSITION (DAYS)

FIGURE E-2 POTENTIAL TIME FRAME OF 'RESPONSE TO A NUCLEAR INCIDENT.

f. The P AGs should not include past health. That is, any reduction of risk exposures. to public health achievable at acceptable cost should be carried out.

g. Separate PAGs should be used for ingestion pathways. 4. Regardless of the above principles, the risk to health from a protective

h. P AGs should apply only to action should not itself exceed the risk exposure during the first year after an to health from the dose that would be incident. avoided.

Although these PAGs apply to any Appendix B analyzed the risks of nuclear incident, primary consideration health effects as a function of dose was given to the case of commercial (Principles 1 and 2). Considerations U.S. reactors. In general, we have for selection of P AGs for the found it possible to accommodate most intermediate phase of a nuclear of the above recommendations. incident differ from those for selection of P AGs for the early phase primarily with regard to implementation factors E.2.1 Principles (i.e., Principles 3 and 4). Specifically, they differ with regard to cost of In selecting values for these P AGs, avoiding dose, the practicability of EPA has been guided by the principles leaving infirm persons and prisoners in that were set forth in Chapter 1. They the restricted zone, and avoiding dose are repeated here for convenience: to fetuses. Although sheltering is not generally a suitable alternative to

1. Acute effects on health (those that relocation, other alternatives (e.g.,

would be observable within a short decontamination and shielding) are period of time and which have a dose suitable. These considerations are threshold below which they are not reviewed in the sections that follow.

likely to occur) should be avoided.

2. The risk of delayed effects on E.2.1.1 CostlRisk Considerations health (primarily cancer and genetic effects, for which linear nonthreshold The Environmental Protection relationships to dose are assumed) Agency has issued guidelines for should not exceed upper bounds that internal use in performing regulatory are judged to be adequately protective impact analyses (EP-83). These of public health, under emergency include consideration of the appropriate conditions, and are reasonably range of costs for avoiding a statistical achievable. death. The values are inferred from the additional compensation associated

3. PAGs should not be higher than with employment carrying a higher justified on the basis of optimization of than normal risk of mortality and are cost and the collective risk of effects on expressed as a range of $0.4 to $7 E-8

million per statistical death avoided. Using the values cited above, and The following discussion compares a value for R of 3x10-4 deaths/rem (See these values to the cost of avoiding Appendix B), one obtains a range of radiation-induced fatal cancers through doses of about 0.01 to 0.2 rem/day.

relocation. Thus, over a period of one year the total dose that should be avoided to The basis for estimating the justify the cost of relocation would be societal costs of relocation are analyzed about 5 to 80 rem.

in a report by Bunger (BU-89).

Estimated incremental societal costs These doses are based on exposure per day per person relocated are shown accumulated over a period of one year.

below. (Moving and loss of inventory However, exposure rates decrease with costs are averaged over one year.) time due to radioactive decay and weathering. Thus, for any given Moving $1.70 cumulative dose in the first year, the Loss of use of residence 2.96 daily . exposure Tate continually Maintain and secure vacated decreases, so that a relocated person property 0.74 will avoid dose more rapidly in the first Extra living.costs 1.28 part of the year than later. Figure E-3 Lost business and inventories 14.10 shows the effect of changing exposure Extra travel costs 4.48 rate on the relationship

• between the Idle government facilities 1.29 cost of avoiding a statistical death and Total $26.55 the time after an SST-2 accident (See Table E-1) for several assumed The quantity of interest is the dose cumulative annual doses. The curves at which the value of the risk avoided represent the cost per day divided by is equal to the cost of relocation. Since the risk of fatality avoided by the above costs are expressed in relocation per day, at time t, for the dollars/person-day, it is convenient to annual dose under consideration, calculate the dose that must be avoided where t is the number of days after the per-person day. The equation for this accident. The right ordinate shows the IS: gamma exposure rate (mR/h) as a function of time for .the postulated C radionuclide mix at one meter height.

HE=-

VR where: The convex downward curvature HE = dose results from the rapid decay of C = cost of relocation short.,.lived radionuclides during the V = value of avoiding a first few weeks following the accident.

statistical death Since the cost per day for relocation is R = statistical risk of death from assumed to be constant and the dose radiation dose avoided per day decreases, the cost effectiveness of relocation decreases with time. For this reason it is cost E-9

3 I

0.5 rem

~

2 """"'"

V 1 rem 0.3

-....(f) 107 I

/ ~

~ 0.4

~ 9 I ~

'0 8 - 0.5

~ I ~

7 2 rem 0.6 z

0 6 I ~

0.7

/'

~ 5 0.8 u

0 / ~

~ 0.9 1 .0

..J 4 1/ ~

W ..J ex: <x:

>- 3

~

- :J z

'/

CO z 5 rem <x:

0 W

0 0 2 I-0 2

~

<C

i f V 10 rem 3 0

z 0

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<C a.

CJ) 6

~

u. 1 a 4 UJ a:

9 ~ a:

..J 8 I ~ 5 0

<C u U I ~

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7 CJ)

,I 20 rem a:

~

~

6 5

/'

~

~

- 7 8

E

/

CJ) 9 ex:

w ~ 10 4

~

a.

CJ) 0 3 if ~

u 2

/

(

5 10 15 20 25 30 TIME AFTER ACCIDENT (days)

FIGURE E-3. COST OF AVOIDING STATISTICAL FATALITIES AND EXPOSURE RATES CORRESPONDING TO VARIOUS TOTAL FIRST YEAR DOSES (ASSUMES AN SST-2 ACCIDENT AND A $27 PER PERSON-DAY COST OF RELOCATION).

E-IO

effective to quicldy recover areas where Fetuses are a special group at the population has been relocated at greater risk of .health effects from projected doses only marginally greater radiation dose than is the general than the PAG. population, but not at significantly greater risk from relocation itself. The Only trends and general risk of mental retardation from fetal relationships can be inferred from exposure (see Appendix B) is Figure E-3 because it applies to a significant. It is affected by the stage specific mix of radio nuclides. However, of pregnancy relative to the assumed for this radionuclide mix, cost analysis one-year exposure, because the 8th to supports relocation at doses as low as 15th week critical period during which one rem for the first week and two rem the risk is greatest, must be considered for up to 25 days after an accident. in relation to the rapidly changing dose rate. Taking these factors into account, it can be postulated that the E.2.1.2 Protection of Special Groups risk of mental retardation due to exposure of the fetus during the Contrary to the situation for intermediate phase will range from one evacuation during the early phase of an to five times the cancer risk of an incident, it is generally not practical to average member of the public, leave a few persons behind when most depending upon when conception members of the general population occurs relative to the time of the have been relocated from a specified incident. The elevated risk of area for extended periods of time. radiation-induced cancer from exposure Further, no data are available on of fetuses* is less significant, as differing risks of relocation for different discussed in Appendix B.

population groups. In the absence of such data, we have assumed that these It will usually be practicable to risks will be similar to those from reduce these. risks by* establishing a evacuation. Those risks were taken as high priority for e~orts other than equivalent to the health risk from relocation to reduce the dose in cases doses of 30 mrem for members of the where pregnant women reside near the general population and of 150 mrem for boundary of the restricted zone.

persons at high risk from evacuation However, women who are less than (see Appendix C). Therefore, to satisfy seven months pregnant may wish to Principle 4 for population groups at relocate for the balance of their high risk, the P AG for relocation pregnancy if the projected dose during should not be lower than 150 millirem. pregnancy cannot be reduced below 0.5 Given the arbitrary nature of this rem.

derivation, it is fortunate that this value is much lower than the PAG selected, and is therefore not an important factor in its choice.

E-ll

E.2.2 Federal Radiation Protection mrem/yr is 5 rem. We have chosen to Guides limit: a) the projected first year dose to individuals from an incident to* the The choice of a PAG at which Relocation PAG, b) the projected second relocation should be implemented does year dose to 500 :rw-em, and c) the dose not mean that persons outside the projected over a fifty-year period to 5 boundary of the restricted zone should rem. Due to the extended duration of not be the subject of other protective exposures and the short half-life of actions to reduce dose. Such actions important radioiodines, no special are justified on the basis of existing limits for thyroid dose are needed.

Federal radiation protection guidance (FR-65) for protecting the public, including implementation of the E.3. Dose from Reactor Incidents principle of maintaining doses "as low as reasonably achievable" (ALARA). Doses from an environmental source will be reduced through the The intended actions to protect the natural processes of weathering and public from radiation doses on the radioactive decay, and from the basis of Radiation Protection Guides shielding associated with part time (RPGs) are those related to source occupancy in homes and other struct-control. Although it is reasonable for ures. Results of dose calculations members of the public to receive higher based on the radiological character-exposure rates prior to the source term istics of releases from three categories being brought under control, the of postulated, fuel-melt, reactor establishment of acceptable values for accidents (SST-1, SST-2, and SST-3) relocation P AGs must include (SN-82) and a weathering model from consideration of the total dose over the WASH-1400 (NR-75) are shown in average remaining lifetime of exposed Table E-3. This table shows the individuals (usually taken as 50 years). relationship between annual doses for the case where the sum, over fifty The nationally and internationally years, of the effective dose equivalent recommended upper bound for dose in from gamma radiation and the a single year from man-made sources, committed effective dose equivalent excluding medical radiation, is 500 from inhalation of resuspended mrem per year to the whole body of materials is 5 rem. Radioactive decay individuals in the general population and weathering reduces the second (1C-77, FR-65). These recommend- year dose from reactor incidents to 20 ations were not developed for nuclear to 40 percent of the first year dose, incidents. They are also not depending on the radionuclide mix in appropriate for chronic exposure. The the release.

1CRP recommends an upper bound of 100 mrem per year, from all sources Based on studies reported in combined, for chronic exposure (IC-77). WASH-1400 (NR-75), the most The corresponding 50-year dose at 100 conservative dose reduction factor for E-12

Table E-3 Annual Doses Corresponding to 5 Rem in 50 Yearsa Dose According to Accident Categoryh (rem)

Year SST-1 SST-2 SST-3 1 1.25 1.60 1.91 2 0.52 0044 0.38 3 *0.33 0.28 0.24 4 0.24 0.20 0.17 5 0.18 0.16 0.13 6 0.14 0.12 0.11 7 0.12 0.11 0.090 8 0.10 0.085 0.070 9 0.085 0.075 0.065 10 0.080 0.070 0.060 11 0.070 0.060 0.050 12 0.060 0.055 0.050 15 0.055 0.045 0.040 20 0.045 0.040 0.030 25 0.040 0.035 0.025 30 0.030 0.030 0.025 40 0.025 0.020 0.020 50 0.020 0.015 0.010 aWhole body dose equivalent from gamma radiation plus committed effective dose equivalent from inhalation assuming a resuspension factor of 10-6 mol. Weathering according to the WASH-1400 model CNR-75) and radioactive decay are assumed.

bRadionuclide abundance ratios are based on reactor inventories from WASH-1400 CNR-75).

Release quantities for accident categories SST-i, SST-2 and SST-3 are shown in Table E-2. Initial concentrations are assumed to have decayed for 4 days after reactor shutdown.

structures (frame structures) is about relocated to 60 percent (or less) of the 004 (dose inside divided by dose values shown in Table E-3 before the outside) and the average fraction of application of decontamination.

time spent in a home is about 0.7.

Combining these factors yields a net

• dose reduction factor of about 0.6. In EA. Alternatives to Relocation most cases, therefore, structural shielding would be expected to reduce Persons who are not relocated, in the dose to persons who are

• not addition to dose reduction provided by E-13

partial occupancy in homes and other cesium that are in the range of 0.5 to structures, can reduce their dose by the 0.95, depending on the delay time after application of various techniques. Dose deposition before flushing is applied.

reduction efforts can range from the The factor for ruthenium on asphalt simple processes of scrubbing and/or was about 0.7 and was independent of flushing surfaces, soaking or plowing of the delay of flushing. The results of soil, removal and disposal of small these experiments indicate* that spots of soil found to be highly decontamination of the important contaminated (e.g., from settlement of reactor fission products from asphalt or water), and spending more time than concrete surfaces may be much more usual in lower exposure rate areas difficult than decontamination of (e.g., indoors), to the difficult and time nuclear weapons fallout. Other simple consuming processes of removal, dose reduction methods listed above disposal, and replacement of would be effective to varying degrees.

contaminated surfaces. It is The average dose reduction factor for anticipated that simple processes gamma radiation from combinations of would be most appropriate to reduce simple decontamination methods is exposure rates for persons living in estimated to be at least 0.7.

contaminated areas outside the Combining this with the 40 percent restricted zone. Many of these can be reduction estimated above for carried out by the residents with structural shielding indicates that the support from officials for monitoring, doses listed in Table E-3 may be more guidance on appropriate actions, and than twice as high as those which disposal. The more difficult processes would actually be received by persons will usually be appropriate for recovery who are not relocated.

of areas from which the population is relocated.

E.5 Risk Comparisons Decontamination experiments involving radioactive fallout from Many hazardous conditions and nuclear weapons tests have shown their associated risks are routinely reduction factors for simple faced by the public. A lingering decontamination methods in the radiation dose will add to those risks, vicinity of 0.1 (i.e., exposure rate as opposed to substituting one risk for reduced to 10 percent of original another, and, therefore, radiation values). However, recent experiments protection criteria cannot be justified at the Riso National Laboratory in on the basis of the existence of other Denmark (WA-82, WA-84), using risks. It is, however, useful to review firehoses to flush asphalt and concrete those risks to provide perspective. This surfaces contaminated with radioactive section compares the risks associated material of the type that might be with radiation doses to those associated deposited from reactor accidents, show with several other risks to which the decontamination factors for public is commonly exposed.

radionuclides chemically similar to E-14

Figure E-4 compares recent doses required to produce a similar risk statistics for the average lifetime risk of death from radiation-induced cancer of accidental death in various range from about 0.07 to 33 rem.

occupations to the estimated lifetime risk of fatal cancer for members of the general population exposed to radiation E.6 Relocation PAG Recommendations doses ranging up to 25 rem.

Non-radiation risk values are derived Previous sections have reviewed from information in reference (EP-81) data, standards, and other information and radiation risk values are from relevant to establishing P AGs for Appendix B. These comparisons show, relocation. The results are for example, that the lifetime cancer summarized in Table E-5, in relation to risk associated with a dose of 5 rem is the principles set forth in Section E.2.1.

comparable to the lifetime risk of accidental death in some of the safest Based on the avoidance of acute occupations, and is well below the effects alone (Principle 1) 50 rem and average lifetime risk of accidental 10 rem are upper bounds on the dose death for all industry. at which relocation of the general population and fetuses, respectively, is Risks of health effects associated justified. However, on the basis of with radiation dose can also be control of chronic risks (Principle 2) a compared to other risks facing lower upper bound is appropriate. Five individuals in the general population. rem is taken as an upper bound on The risks listed in Table E-4 are acceptable risk for controllable lifetime expressed as the number of premature exposure to radiation, including deaths and the average reduction of avoidable exposure to accidentally life-span due to these deaths within a deposited radioactive materials. This group of 100,000 persons. For corresponds to an average of 100 mrem purposes of comparison, a dose of 5 per year for fifty years, a value rem to each member of a population commonly accepted as an upper bound group of 100,000 persons for chronic annual exposure of representative of the average U.S. members of the public from all sources population carries an estimated of exposure combined, other than lifetime risk of about 150 fatal cancers natural background and medical (see Appendix B). The number of radiation (IC-77). In the case of deaths resulting from the various projected doses from nuclear reactor causes listed in Table E-4 is based on accidents, a five rem lifetime dose data from mortality records. corresponds to about 1.25 to 2 rem from exposure during the first year and In summary, the riskofpremature 0.4 to 0.5 rem from exposure during death normally confronting the public the second year.

from specific types of accidents ranges from about 2 to 1000 per 100,000

• Analyses based on Principle 3 population. The estimated radiation (cost/risk) indicate that considering cost E-15

1-- CONSTRUCTION & MINING 1 - - - AGRICUL TURE I---TRANSPORTATION & PUBLIC UTILITIES 25 rem AVERAGE FOR ALL UTILITIES

c I---GOVERNMENT W

~

Q I-_SERVICE W 1-- MANUFACTURING II! 1--- RETAIL &

WHOLESALE

~ TRADE w

II!

a.

u.

o

~ 10- 3

~

II!

W

E ffi u.

i w

(!J II!

W ~--1 rem

~

0.5 rem 10*4~~~ __~__~__~__~__~__~__~__~__~__~__~__~

o 2 4 6 8 10 12 14 16 18 20 22 24 26 rem (effective dose equivalent)

FIGURE E-4. AVERAGE LIFETIME RISK OF DEATH FROM WHOLE BODY RADIATION DOSE COMPARED TO THE AVERAGE RISK OF ACCIDENTAL DEATH FROM LIFETIME (47 YEARS) OCCUPATION IN VARIOUS INDUSTRIES.

E*16

Table E-4 Measure of Lifetime Risk of Mortality from a Variety of Causes a .

(Cohort Size = 100,000)

Aggregate years Reduction of Average years Nature of Premature of life lost life expectancy of life lost to accident deaths to cohort at birth (years) premature deaths Falls 1,000 12,000 0.12 11 Fires 300 7,600 0.076 26 Drowning 190 8,700 0.087 45 Poisoning 69 2,500 0.025 37 by drugs and medicaments Cataclysmb 17 490 0.005 30 Bites and 8 220 0.002 27 stings C Electric 8 290 0.003 37 current in homesd aAlI mortality effects shown are calculated as changes from the U.S. Life Tables for 1970 to life

'tables with the cause of death under investigation removed. These effects also can be interpreted as changes in the opposite direction, from life tables with the cause of death removed to the 1970 Life Table. Therefore, the premature deaths and years of life lost are those that would be experienced in changing from an environment where the indicated cause of death is not present to one where it is present. All values are rounded to no more than two significant figures.

bCataclysm is defined to include cloudburst, cyclone, earthquake, flood, hurricane, tidal waves, tornado, torrential rain, and volcanic eruption.

CAccidents by bite and sting of venomous animals and insects include bites by centipedes, venomous sea animals, snakes, and spiders; stings of bees, insects, scorpions, and wasps; and other venomous bites and stings. Other accidents caused by animals include bites by any animal and nonvenomous insect; fallen on by horse or other animal; gored; kicked or stepped on by animal; ant bites; and run over by horse or other animal. It excludes transport accidents involving ridden animals; and tri{)ping,falling over an animal. Rabies is also excluded.

dAccidents ~aused by electric current from home wiring and appliances include burn by electric current, electric shock or electrocution from exposed wires, faulty appliances, high voltage cable, live rail, and open socket. It excludes burn by heat from electrical appliances and lighting.

E-17

Table E-5 Summary of Considerations for Selecting PAGs for Relocation Dose Consideration Principle (rem) 50 Assumed threshold for acute health effects in adults. 1 10 Assumed threshold for acute health effects in the fetus. 1 6 Maximum projected dose in first year to meet 0.5 rem in the second yeartt. 2 5 Maximum acceptable annual dose for normal occupational exposure of adults. 2 5 Minimum dose that must be avoided by one year relocation based on cost. S 3 Minimum projected first-year dose corresponding to 5 rem in 50 year~. 2 3 Minimum projected first-year dose corresponding to 0.5 rem in the second yeartt. 2 2 Maximum dose in first year corresponding to 5 rem in 50 years from a reactor incident, based on radioactive decay and weathering only. 2 1.25 Minimum dose in fJIst year corresponding to 5 rem in 50 years from a reactor incident based on radioactive decay and weathering only. 2 0.5 Maximum acceptable single-year dose to the general population from all sources from non-recurring, non-incident exposure. 2 0.5 Maximum acceptable dose to the fetus from occupational exposure of the mother. 2 0.1 Maximum acceptable annual dose to the general population from all sources due to routine (chronic), non-incident, exposure. 2 0.03 Dose that carries a risk assumed to be equal to or less than that from relocation. 4 IIAssumes the source term is from a reactor incident and that simple dose reduction methods are applied during the first month after the incident to reduce the dose to persons not relocated from contaminated areas.

E-18

alone would not drive the P AG to second year and lifetime objectives values less than 5 rem. Analyses in noted above.

support of Principle 4 (risk of the protective action itself) provide a lower Since effective dose does not bound for relocation PAGs of 0.15 rem. include dose to theskin (and for other reasons discussed in Appendix B)

Based on the above, 2 rem protective action to limit dose to skin is projected committed effective dose recommended at a skin dose 50 times equivalent from exposure in the first the numerical value of the PAG for year is selected as the P AG for effective dose. This includes relocation. Implementation of consideration of the risk of both relocation at this value will provide curable and fatal cancers.

reasonable assurance that, for a reactor accident, a person relocated from the outer margin of the relocation zone E.7 Criteria for Reentry into the will, by such action, avoid an exposure Restricted Zone rate which, if continued over a period of one year, would result in a dose of Persons may need to reenter the about 1.2 rem. This assumes that 0.8 restricted zone for a variety of reasons, rem would be avoided without including radiation monitoring, relocation through normal partial _recovery work, animal care, property occupancy of* homes and other maintenance, and factory or utility structures. This P AG will provide operation. Some persons outside the reasonable assurance that persons restricted zone, by nature of their outside the relocation zone, following a employment or habits, may also receive reactor accident, will not exceed 1.2 higher than average radiation doses.

rem in the -first year, 0.5 rem in the Tasks that could cause such exposures second year, and 5 rem in 50 years. include: 1) chahging of filters on air The implementation of simple dose handling equipment (including reduction techniques, as discussed in vehicles), 2) handling and disposal of section E-4, will further reduce dose to contaminated vegetation (e.g., grass persons who are not relocated from and leaves) and, 3) operation of control contaminated areas. Table E-6 points for the restricted zone.

summarizes the estimated maximum dose that would be received by these Individuals who reenter the persons for various reactor accident restricted zone or who perform tasks categories with and without the involving exposure rates that would application of simple dose reduction cause their radiation dose to exceed techniques. In the case of non-reactor that permitted by the P AGs should do accidents these doses will, in general, so in accordance with existing Federal differ, and it may be necessary to apply radiation protection guidance for more restrictive P AGs to the first year occupationally exposed workers in order to assure conformance to* the (EP-87). The basis for that guidance has been provided elsewhere (EP-87).

E-19

Table E-6 Estimated Maximum Doses to Nonrelocated Persons From Areas Where the Projected Dose is 2 REMa Dose (rem)

Accident No additional dose reduction Early simple dose reductionb Category Year 1 Year 2 50 years Year 1 Year 2 50 years SST-1 1.2 0.5 5.0 0.9 0.35 3.5 SST-2 1.2 0.34 3.9 0.9 0.24 2.7 SST-3 1.2 0.20 3.3 0.9 0.14 2.3 aBased on relocation at a projected dose of 2 rem in the first year and 40 percent dose reduction to nonrelocated persons from normal, partial occupancy in structures. No dose reduction is assumed from decontamination, shielding, or special limitations on time spent in high exposure rate areas.

~e projected dose is assumed to be reduced 30 percent by the application of simple dose reduction techniques during the first month. If these techniques are completed later in the first year, the first year dose will be greater.

References Impact Analysis. EPA-23-01-84-003, U.S.

Environmental Protection Agency, Washington (1983).

AR-89 Aaberg, Rosanne. Evaluation of Skin EP-87 U.S. Environmental Protection and Ingestion Exposure Pathways. EPA Agency. Radiation Protection Guidance to 520/1-89-016, U.S. Environmental Protection Federal Agencies for Occupational Exposure.

Agency, Washington (1989).

FederaIRegister,~ 2822; January 27, 1987.

BU-89 Bunger, Byron M. Economic Criteria FR-65 Federal Radiation Council. Radiation for Relocation. EPA 520/1-89-015, U.S.

Protection Guidance for Federal Agencies.

Environmental Protection Agency, Federal Register, 30, 6953-6955; May 22, 1965.

Washington (1989) 1A-85 International Atomic Energy Agency.

EP-81 U.S. Environmental Protection Principles for Establishing Intervention Agency. Background Report. Proposed Federal Levels for Protection of the Public in the Radiation Protection Guidance for Event of a Nuclear Accident or Radiological Occupational Exposure. EPA 520/4-81-003, Emergency. Safety Series No.72, International U.S. Environmental Protection Agency, Atomic Energy Agency, Vienna (1985).

Washington (1981).

10-77 International Commission on EP-83 U.S. Environmental Protection Radiological Protection. Radiological Agency. Guidelines for Performing Regulatory E-20

Protection. IORP Publication 26, Pergamon SN-82 Sandia National Laboratories.

Press, Oxford (1977). Technical Guidance for Siting Criteria Development. NUREG/CR-2239, U.S. Nuclear 10-84 International Commission on Regulatory Commission, Washington (1982).

Radiological Protection. Protection of the Public in the Event of Major Radiation WA-82 Warming, L. Weathering and Accidents: Principles for Planning, ICRP Decontamination of Radioactivity Deposited Publication 40, Pergamon Press, New York on Asphalt Surfaces. Riso-M-2273, Riso (1984). . National Laboratory, DK 4000 Roskilde, Denmark (1982).

NR-75 U.S. Nuclear Regulatory Commission.

Calculations of Reactor Accident WA-84 Warming, L. Weathering and Consequences. WASH-1400, U.S. Nuclear Decontamination of Radioactivity Deposited Regulatory Commission, Washington (1975). on on Concrete Surfaces. RISO-M-2473, Riso National Laboratory, DK-4000 Roskilde, Denmark. December (1984).

E-21

APPENDIXF Radiation Protection Criteria for the Late Phase Background Information (Reserved)

• u.s. GOVERNMENT PRINTING OFfICE: 1tt21170003M7003