ML19221A089

Ad Hoc Interagency Dose Assessment Group Preliminary Estimates of Population Dose & Health Effects Re TMI-2 Events

ML19221A089
Person / Time
Site:	Crane
Issue date:	04/15/1979
From:	Battist L, James Buchanan, Congel F Office of Nuclear Reactor Regulation, NRC OFFICE OF STANDARDS DEVELOPMENT
To:
References
NUDOCS 7905190107
Download: ML19221A089 (60)

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PRELIMINARY ESTIMATES of POPULATION DOSE and HEALTH EFFECTS Three Mile Island Nuclear Station Unit No. 2 Accident Ad Hoc Intercency Dose Assessment Grouo Lewis Battist Nuclear Regulatory Commission John Buchanan Nuclear Regulatory Commission Frank Congel Nuclear Regulatory Commission Christopher Nelson Environmental Protection Agency Mark Nelson Center for Disease Control Department of Health, Education, and Welfare Harold Peterson Nuclear Regulatory Commissiori Marvin Rosenstein Food and Drug Administration Department of Health, Education, and Welfare Easter Sunday - April 15, 1979 4

7905190(o7.j j27 162 0

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TABLE OF CONTENTS i.

Preface ii.

Summary of Findings 1.

Introduction 2.

Nature of the Radioactivity Released 3.

External Exposure Assessment A.

Ground Station Dosimeters B.

Onsite Metropolitan Edison Dosimeters 4.

Potential Health Impact of External Exposure A.

Health Effects from Low-Level Ionizing Radiation B.

Comparison of Individual Doses with Natural Background C.

Comparison of Health Impact with Natural Cancer Risks D.

Summary of Health Effects E.

Oose Rate Effects 5.

Other Sources of Exposures A.

Skin Dose B.

Inhalation Dose C.

Airborne Radiciodine Concentrations and Doses D.

Ingestion of Iodine-131 in Milk Appendix A - DOE Estimate of External Whole Body Radiation Exposure to Population Around the Three Mile Island Nuclear Station Appendix B - DOE Environmental Deposition Measurements in the Area Surrounding the Three Mile Island Nuclear Power Statico 127 163 e

u PREFACE This report was prepared by representatives of the NRC, HEW and EPA, which constitute an Ad Hoc Population Dose Assessment Group.

It is an assessment of the population dose estimates for the offsite residents within 50 miles of the Three Mile Island Nuclear Station.

The report is being made available at this early date to provide details of the group's analysis and to foster comment from a wide spectrum of interested parties.

The report is being released in preliminary form and has received no internal review in any of the three agencies beyond the reasonable care taken by the rcembers of the Ad Hoc Group to assure that the material included is correct, to our kncwledge.

The dose and health effects estimates are based on those data that permit direct evaluation of dose to the offsite population from radio-activity released into the environment during the accident.

The report also addresses several areas of concern that have been voiced publicly about the types of radionuclides released, about the con-tribution to population dose from beta decays of the radionuclides released, about the degree of coverage afforded by available radiation measurements, and about the range of risk factors that can be used to convert collective dose to projected health effects.

127 164 4

At this point in the assessment, the conclusion of the Ad Hoc Group is that the offsite population dose anscriated with radioactivity released during the reactor accident to date represents minimal risks of additional health effects to the offsite populat;o.

The numerical statement of this conclusion is developed in the report.

The Ad Hoc Group is not aware of any radiation measurements made during the accident that would alter this basic conclusion, although refinement of the numerical estimates can be expected as the data are updated.

The members of the Ad Hoc Group c.oncur that the manner in which the estimates were generated from the dosimetry data was conservative.

ACKNOWLEDGMENTS The Ad Hoc Group acknowledges the assistance of Ted Schoe g of the Department of Energy and Andy Hull of Brookhaven National Laboratory in providing the preliminary assessment in Appendices A and 8.

We especially acknowledge the contribution of Mrs. Jeannette Kiminas of the Nuclear Regulatory Commission staff in preparing this material on such short notice.

i27 165

PRELIMINARY ESTIMATES OF POPULATION DOSF AND HEALTH EFFECTS Three Mile Island Nuclear Station Unit No. 2 Accident Summary of Findings An interagency team from HEW, EDA and NRC has estimated the collective radiation dose received by the approximately 2 million people residing within 50 miles of the Three Mile Island Nuclear Station resulting frcm the accident of March 28, 1979.

The estimates are for the period from March 28 through April 7, 1979.

The principal dose estimate is based upon ground level radia-tion measurements from integrating dosimeters located within 15 miles of the site and represents only the gamma-ray component of the radiation exposure.

The data were obtained frca dosimeters placed by Metropolitan Edison Power Company prior to the start of the in:ident through March 31, 1979, as part of their normal environmental surveillance program, and from measurements made by NRC from noon of March 31 through the afternoon of April 7, 1979.

A second dose estimate, developed independently by the Department of Energy through aerial monitoring that commenced about 4 p.m. on March 28, 1979 is also included.

A variety of other data helpful in assessing other relatively minor components of population dose was also reviewed.

127 166

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The highest radiation measurement that is applicable to the offsite popula-tion occurred in an area east to northeast of the plant.

The maximum indi-vidual dose to a hypothetical person located in this region for the duration of the incident would be about 85 mrem.

The collective dose to the total population within a 50-mile radius of the plant was estimated to be about 3,550 person rem, based on the projected 1980 population estimate.

No reduc-tion in this dose estimate has been made for a significant portion of the population that. relocated from areas close to the nuclear plant or otherwise left the area.

The projected number of fatal cancers over the total lifetime of the entire population located in the ci-mile area is 0.7.

The number of total potential lifetime health effects, including all cases of cancer and genetic effects to future generations, would be approximately 2.0.

A number of questions concerning this analysis are posed and briefly answered below.

More detailed discussions are included in ~he body of the report.

What radionuclides were released into the environment?

The predominant radionuclide released into the environment was xenon-133, with some xenon-135 and small amounts of iodine-131.

This conclusion is based e

127 167

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on the information ava'. ;able to date, which includes the expected inventory of noble gases for the period the reactor was in operation prior to the accident, analyses of airborne radioactivity in the containment structure, measured composition of stack discharges, and the extensive monitoring of environmental samples.

The environmental samples provide the most direct evidence for this conclusion.

What were the highest radiation exoosures measured outside the plant buildings?

Some of the Metropolitan Edison dosimeters located on the Three Mile Island Nuclear Statien site during the first days of the accident reccrded cumulative doses censiderably larger (up to 1,050 mrem) than those located for of fsite populations.

The onsite dosimeter readings are not applicJ 'e to either the maximum dose to an individua' offsite nor the collective (population) dose.

What is meant Ly maximum dose _,2 an individual?

The maximum dose to an ind'vidual applies to a hypothetical person exposed out-of-doors in the area of the maximum recorded exposure readings recorded for an offsite location throughout the period of the incident.

It applies only to that individual or others in the same vicinity and not to any other population segment.

127 168

~

4 What is meant by collective dose (oerson rem)?

The collective dose is a measure of the total radiation dose which was received by the entire population in the 50-mile radius of the Three Mile Island '

site.

It is obtained by multiplying the number of people in a given sector of the area by the dose estimated for that sector and adding up all of the sector totals.

How were the of[ site pooulation dose estimates obtained?

The principal population dose estimate was obtained by analysis of data from integrating dosimeters placed at fixed locations at various distances offsite.

During the period March 28 through March 31 there were a limited number of Metropolitan Edison offsite dosimeter locations.

During the period after March 31, NRC placed 37 dosimeters at offsite locations.

On April 5, 10 additional NRC dosimeters were placed offsite at selected school locations.

After March 31, only the NRC dosimeters were retrieved for analysis.

These dosimeters record the contribution to external radiation exposure from gamma rays emitted from radionuclides.

A second analysis which results from 00E aerial surveys of radiation exposu.es ra,sured in the plume of the radiation releases was also available.

e 127 169 4

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Were the radiation measurements adeouate to determine population health effects?

The extensive environmental monitoring and food sampling were adequate to characterize the nature of the radionuclides released and the levels of radioactivity in those media..The dosimetry work performed by DOE (aerial survey) and Metropolitan Edison and NRC (ground level dosimeters) are suffi-cient to characterize the maximum individual and population dose, when taken as a whole.

The number and location of fixed ground level dosimetdrs for the period March 28 through March 31 was limited.

However, this period was covered by aerial monitoring from about 4 pm on March 28 by the DOE aerial survey and by mobile ground monitoring surveys performed by various organizations from about 10 am on March 28.

What is the contribution of beta radiation emitted from xenon-133 to the total dose?

The beta radiation from xenon-133 can contribute to radiation dose by two modes, inhalation and skin absorption.

The low energy of the xenon-133 beta cannot penetrate past the skin layer.

The total beta plus gamma dose to the skin is estimated to be about 4 times the total body dose from gamma radia-tion alone.

This additional skin dose could result in small increases in the total health effects (about 0.2 health effects) due only to skin cancer.

The increase in total fatal cancers over that estimated for external exposure 127

\\70 e

6 from gamma radiation alone would be about 0.01 fatal cancers.

This contribu-tion would be considerably decreased by clothing or by being indoors.

The dose to the lungs from inhalation of xenon-133 for both beta and gamma is estimated to be approximately 1 percent of that for total body dose from gamma alone.

The dose ta all body organs from inhalation of xenon-133 is approximately 4 percent of that for total body dose from gamma alone.

What radionuclides were found in milk and food and what are their sionificance?

Iodine-131 was detected in milk samples.

The maximum level seen in milk was 300 times lower than the level at which a recommendation would be made to remove cows from contaminated pasture.

Cesium-137 was also detected in milk, but at concentrations anticipated frca residual fallout from previous atmospheric weapons testing.

No increase in radioactivity was found in any other food samples.

How were the health effects estimated?

Health effects were derived from risk factors generally accepted by the scientific community to be the best estimates of health effects from low-level radiation exposure, using the conservative linear, non-threshold dose effect model.

These risk factors are multiplied by the collective dose (person rem) to obtain health effects.

127 17I

7 Have the estimates of radiation dose and health effects changed since the first statement on Aoril 4 at the Senate Hearings?

The maximum dose to an individual has increased from 80 to 85 mrem, as a consequence of adding the contribution from April 2 to April 7.

The estimated collective dose to the populat, ion has almost doubled from 1800 person-rem to 3,550 person-rem.

This increase is due to a more thorough and systematic review of the earlier dosimeter results and to the dose contribution from April 2 to April 7.

The increase in collective dose changes the existing risk of fatal cancers to the 50-mile radius population from 0.36 cancers to 0.71 cancers.

In either instance less than one additional fatal cancer is anticipated.

The change in lifetime risk for all cancers and genetic effects is increased from approximately 1 to approximately 2.

These changes therefore do not alter the previous conclusion of minimal health effects to the entire offsite population from the radioactivity released during the accident.

What does the term "oreliminary estimate" mean?

The dose and health effects estimates contained in this report are based on those data provided the NRC Incidence Response Center before April 7, 1979.

There has not been sufficient time to verify many details concerning the data and to incorporate later updates on the results.

While the Ad Hoc Group feels that the overall conclusion that there was minimal health impact to the popula-tion is correct,'the actual numerical values may be subject to change.

127 172

8 1.

INTRODUCTION The Ad Hoc Population Dose Assessment Group was formed from individuals assigned by their respective agencies to the NRC Incident Response Center on Monday April 2, 1979 and who recognized a common need for an estimate of the public health consequences of,this accident.

Because of the urgency to prepare estimates of the health impact for presentation at the April 4,1979 Senate hearings, the group was forced to rely upon data which were available at the NRC Incident Response Center or easily obtained through existing communication channels with the Federal coordination center adjacent to the Three Mile Island site.

This preliminary report presents the analysis performed at that time, with an extension of the estimate through April 7, 1979.

The Ad Hoc Group has also had a chance to review its earlier calculations and analyze the data in a more systematic fashion.

127 173 4

+

9 2.

NATURE OF THE RADI0 ACTIVITY RELEASED The primary radioactive materials released to the environment appear to be xenon-133 (half-life 5.3 days) and xenon-1:5 (half-life 9.2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />) and traces of radioactive iodine, primarily iodine-131.

This is substantiated by considera-tion of the known course of events, knowledge that the effluents were released through particulate and iodine filters, and from subsequent environmental measure-ments in the diffusing radioactive plume (see Appendix B).

Particulate radio-nuclides such as strontium-90, uranium isotopes, and plutonium would either have been retained in the fuel or if released from the fuel would remain in the coolant water.

These elements have not, to our knowledge, been detected in the environment in the vicinity of Three Mile Island nor in the reactor containment or gas decay tanks.

Radioactive krypton isotopes, which would ordinarily be expected to be released along with the xenon isotopes, do not appear to have been released in comparable quantities.

This may be due to the relatively short half-life (seconds to minutes) of their precursors, compared to the hour to several day half-lives of the radioactive iodine parents of the xenons.

The majcrity of the krypton isotopes appear to have remained within the containment building.

Appendix B describes the environmental surveillance activities of the Department of Energy which measured the radionuclides in the environment from the release.

127 174

10 3.

EXTERNAL DOSE ASSESSMENT A.

Analysis of Metrooolitan Edison and Nuclear Reoulatory Commission Ground Dosimeters The available thermoluminescent dosimeter (TLD) data were used for this evaluation due to three primary factors:

1.

The TLD's placed by the licensee as part of the environmental radiation surveillance program for routine operation were the only devices for measuring radiation exposure that were placed at fixed locations throughout the course of the accident, particularly during the first 3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br />.

2.

The TLD's are dose integrating devices and measure total exposure rather than peak exposure rates which may be transient (of short duration).

3.

Under ideal conditions (which may or may not apply to this situation) they can measure exposures of a few mR (1,2).

(1) Arthur Schambon, "Some Implications of LiF Dosimeters for Environmental Radiation Measurements," U.S. Atomic Energy Commission Report HASL-251 (March 1972).

(2)Gail de P. Burke, " Investigation of a CaF : Mn Thermoluminescent Dosimetry 2

System for Environmental Mor.itoring," U.S. Atomic Energy Commission Report HASL-252 (April 1972).

127 175 4

11 Samples of each type of TLD placed by the various organizations around the TMI site have been collected and exposed to known doses from a calibrated source of xenon-133.

The results of this calibration were not completed in time for consideration for this preliminary report.

TLD data available for the. dose assessment are listed in Tables 3-1 through 3-11.

The locations of these dosimeters are shown in Figures 3-1 and 3-2.

Data for the first two periods 3/28-3/29 and 3/29-3/31 were obtained from stations used by the Metropolitan Edison for their routine environmental monitoring program.

Table 3-1 contains data from both a monthly and a quarterly sampling program.

The quarterly data were adjusted for an assumed 14 mR background to calculate the TLD exposure.

Since an appropriate background correction to the monthly data could not be determined, those values were not adjusted.

The data were ordered according to sector.

Those net dosimeter readings which are from onsite locations are identified with an asterisk in the table.

Since these locations were subject to direct radiation and to high local concentra-tions of xenon-133 they were not considered appropriate for estimating offsite doses for the collective dose calculations.

The net offsite data within a sector were averaged and are listed in the last column of the table.

These exposures are assumed to be representative of those received at distances up to 10 miles.

Exposures for sectors without observation were obtained by interpolation from adjacent sectors.

127 176

12 Since there are data for only 6 offsite locations in 6 sectors, the assess-

, ment for this first period rests on a very small data base.

Metropolitan Edison data for 3/29-3/31 are summarized in Table 3-2.

Data for these observations were provided in units of mR/hr for undesignated time periods which ranged from 36 to 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br />.

The total exposure for the period was calculated assuming a 44-hour period for each exposure.

These data for the period 3/29-3/31 provide observations for 11 locations in 9 sectors.

The increased coverage represents an improvement for purpose of the dose estimation over the previous period.

Descriptions of the station locations are presented in Table 3-3.

Data subsequent to March 31 were obtained from the NRC dosimeters and are summarized in Tables 3-4 through 3-10.

The locations of the NRC TLD's are summarized in Table 3-11.

The background assumed for these stations is 0.19 mR/ day based on an average of TLD data from the 1977 Environmental Monitoring Report (3).

Maximum Dose to an Individual The estimated maximum dose to an individual is tabulated, as a function of time in Table 3-13.

.(3) Metropolitan Edison Company Radiological Environmental Monitoring Report -

Three Mile Island Nuclear Station - 1977 Annual Report, January 1 through December 31.

127 177 4

13 The maximum dose (4) to an individual was estimated for the period 3/28-3/29 as the mean of the TLD exposures of two onsite locations, North Weather Station (152) and North Bridge (252).

While no member of the general public was present at either location, they represent a best judgement of the maximum to which any individual in the general northerly to easterly direction of the plant could have been exposed.

The TLD exposures were corrected for background (14 1 mR.

For the mR) and the dose in mrem assumed to be equal to the exposure period 3/28-3/29 the maximum individual dose was thus estimated to be 45 mrem.

For the period 3/29-3/31 the maximum individual dose was increased by 29 arem, the exposure recorded by the dosimeter of station 4A1.

Subsequent addition to the maximum individual dose are based on the exposure corrected for background at NRC station E1A.

The total dose for the maximum individual is 86 mrem for the period 3/28 tnrough 4/7.

This value is considered a conservative upper bound.

Collective Dose The collective dose was estimated for the population within 50 miles of the plant.

The population data used for the estimate were the 1980 projected (4)The term " dose" is used here for brevity rather than the precise term

" dose equivalent."

\\27

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14 populations given in the SAR(5).

These population distributions are contained in Tables 3-12 and 3-13 covering 0-10 miles and 10-50 miles respectively.

The collective dose in person-rem for each directional sector was calculated as the sum of two parts.

The first part was the product of the average 0-10 mile dose and the 0-10 mile population.

The second part was the product of the corresponding 10-50 mile values.

The 0-10 mile dose for each sector was based on the corresponding net TLD observations assuming that the dose in mrem was equal to the TLD exposure in mR.

For all but the first three periods, net exposures for each TLD in a sector were averaged to obtain the 0-10 mile dose.

For data during the first three periods, an attempt was made to make the estimates more realistic by adjusting each TLD observation to a 5 mile distance assuming an inverse 1.5 power dependence with distance.

Dosimeters within 1 mile were assumed to be at 1 mile as a conservative assumption.

For example, in the 3/28-3/29 period there are two net observations of 8 mR in the SE sector.

Since they are at distances of 9 and 15 miles, the 0-10 mile dose is estimated as (8 x (5/9) 1.5

+8m (5/15) 1.5)/2 = 30 mrem.

The 0-10 mile dose is given in the last calumn of Tables 3-1, 3-2, and 3-4 through 3-10.

(5) Final Safety Analysis Report, Three Mile Island Nuclear Station - Unit 2, Vol. 1, Chapter 2, Figs. 2.1-5 and 2.1-10.

127 179 4

15 The 10-50 mile dose is obtained by assuming a standard dispersion factor that decreases with distance to the -1.5 pcwer.

The 0-10 mile dose is used as the reference dose at 5 miles and the population is assumed to be uniformly distributed within the sector segment.

On the basis of these assumptions the 10-50 mile dose is.0728 times the 0-10 mile dose.

The collective doses are summarized in Table 3-15 for each period of data.

The estimated total collective dose for period 3/28-4/7 is about 3,550 person-rem.

More than half the collective dose calculated was delivered before March 31.

Unfortunately there are very limited data in this period to use for this estimation.

The total value of 3,550 represents a reasonable estimate, in our view, but is clearly limited by uncertainties due to the limited data available for the period 3/28-3/31.

Further refinement of the values used will not reduce the uncertainty due to the limited number cf observations available.

}2) 4

d Figure 3-1.

Location of Metropolitan Edison Dosimetry Sites (March 28-31) and Nuclear Regulatory Commission Sites (After March 31) Within a 10-mile Radius of Three Mile Island Nuclear Station.

See Figure 3-2 for Metropolitan Edison Sites within One-mile Radius, Metropolitan Edison Dosimeters (up to_ Ma'rc'h 311-- ~~_

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16 Table 3-1.

METROPOLITAN EDISON TLD DATA 3/28/79 - 3/29/79 2

TOTAL NET 0-10 MILE I

OIR STATION LOCATION PERIOD EXPOSURE EXPOSURE DOSE (mR)

(mR)

(arem)

N N. Weather Station (.4 mi)

Q 81 67*

0.56 N. York Substation (1.4 mi)

Q 9

0 Middleton Substation (2.6 mi) Q 17 3

NNE N. Bridge (.7 mi)

Q 37 23*

(1.)4 NE (2.3)

ENE Laurel Rd (.5 mi)

Q 17 3

3.1 Rte 241 M

6 6

5 E

Obs. Center (.4 mi)

M

.5

.5 0.05 ESE (15.0)

SE Drager Farm (9 mi)

M 8

8 30.0 Columbia (15 mi)

Q 22 8

SSE Falmouth (2 mi)

Q 12 0

0.0 S

(0.02)

SSW Shelley Island, south Q

7 0*

(0.04)

(1.1 mi)

SW (0.06)

WSV (0.08)

W West Fence M

6 6*

0.09 Shelley Island ctr. (.4 mi)

Q 7

0*

Goldsboro (1 mi)

Q 15 1

W?N Shelley Island, north (.4 mi) Q 7

0*

(0.21)

?N (0.32)

NfM Kohr Island (.4 mi)

Q 8

0*

(0.44)

IQ - Quarterly data (assumed bkg is 14 mR)

M - Monthly data (assumed net) 2Values in parentheses are interpolated.

}27

)b5 Onsite locations not used for offsite dose assessments.

4

~

1/

Table 3-2.

METROPOLITAN EDISlN TLD DATA FOR 3/29/79 - 3/31/79 1

2 DIRECTION STATION CODES TOTAL EXPOSURE 0-10 MILE DOSE (mR)

(mrem)

N 152, 1C1 17.3*, 3.0 1.0 NNE T32 28.2*

(1.7)

(2.4)

NE ENE 4S2, 4A1, 4G1 105.6*, 28.~/, 1.4 3.1 E

553, 5A1 42.3^, 7.2 0.6 (2.6)

ESE SE 7G1, 7F1 1.8, 1.2 4.5 SSE 8C1 9.7 2.9 5

952, 9G1 22.3*, 1.8 6.3 SSW 1081 12.6 1.2 SW 1151 95.9*

(1.3)

WSW 1281 8.1 1.4 (4.2)

W WNW 1452 39.4*

(7.1)

NW 15G1 2.2 9.9 NNW 1651 75.7*

(5.5) nOnsite locations not used in calculations.

1.

Based on 44 hour5.092593e-4 days <br />0.0122 hours <br />7.275132e-5 weeks <br />1.6742e-5 months <br /> period.

2.

0.3 mR background subsequently substracted.

Values in parentheses are interpolated from adjacent sectors.

127 184

18 Table 3-3.

METROPOLITAN EDISON TLu STATICN LOCATIONS STATION LOCATION DESCRIPTION

• CODE 152 0.4 miles N of site, N Weather Station 252 0.7 miles NNE of site on light pole in middle of North Bridge 452 0.3 miles ENE of site on top of dike, East Fence 553 0.2 miles E of site on top of dike, East Fence 952 0.4 miles S of site at South Beach of Three Mile Island 1151 0.1 miles SW of site, west of Mechanical Draf t Towers on dike 1452 0.4 miles WNW of site at Shelley Island picnic area 1651 0.2 miles NNW of site at gate in fence on west side of Three Mile Island 4A1 0.5 miles ENE of site on Laurel Rd., Met. Ed. pole #668-OL SA1 0.4 miles E of site on north side of Observation Center Building 1081 1.1 miles SSW of site on south beach of Shelley Island 1281 1.6 miles WSW of site adjacent to Fishing Creek 1C1 2.6 miles N of site at Middletown Substation 8C1 2.3 miles SSE of site 7F1 9 miles SE of site at Drager Farm of f Engle's Tollgate Road 4G1 10 miles ENE of site at Lawn - Met. Ed. Pole #J1813 7G1 15 miles SE of site at Columbia Water Treatment Plant 9G1 13 ruiles S of site in Met. Ed. York Load Dispatch Station 15G1 15 miles NW of site at West Fairview Substation nAll distances measured from a point midway between the Reactor Buildings of Units One and Two.

127 185 4

19 Table 3-4.

NRC TLD DATA FOR 3/31/79 - 4/1/79 DIRECTION STATION CODES TOTAL EXPOSURE

• 0-10 MILE 00SE (mR)

(mrem)

N N-1, N-2, N-3, N-4, N-5 1.0, (wet), 1.2, 1.0, (wet) 1.39 (1.60)**

NNE (wet), 1.6, 2.1 1.81 NE NE-2, NE-3, NE-4 ENE E-1, NE-1 25, 7.0 1.41 E

E-2, E-2***, E-4, E-1A 4.3, 2.1, 2.5, 8.4 1.87 (2.59)**

ESE SE SE-5, SE-4, SE-3 2.5, 3.0, 2.3 4.96 SSE SE-2, SE-1 3.5, 10.1 0.81 S

S-1, S-2, S-3, S-4 1.6, 1.0, 1.2, 1.2 1.18 SSW SW-1, 0.9 0.21 SW SW-2, SW-3, SW-4 0.9, 1.1, 0.9 1.45 WSW W-2 0.9 0.09 W

W-1, W-3, W-5, W-4 3.0, 1.1, 1.2, 1.0 1.01 WNW NW-3

1. 4 0.53 NW NW-5, NV-4, NW-2, NW-1 4.6, 5.5, 1.2, 0.9 9.09 (5.24)**

NNW sNet mR = (Total mR) - (0.19 mR Bkgd.)

ss Value interpolated frca adjacent sectors.

nss Should be E-3.

127 186

20 Table 3-5.

NRC TLD DATA FOR 4/1/79 - 4/2/79 OIRECTION STATION CODES TOTAL EXPOSURE

• 0-10 MILE COSE (mR)

(arem)

N N-1, N-2, N-3, N-4, N-5 0.3, 0.3, 0.3, 0.3, 0.3 0.11 NNE NE-1, NE-2, NE-3 0.2, 0.3, 0.3 0.08 NE NE-4 0.3 0.11 ENE E-1 0.4 0.21 E

E-3, E-4, E-1A 0.4, 0.3, 0.3 0.21 ESE E-2 0.3 0.11 SE SE-5, SE-4 0.3, 0.3 0.11 SSE SE-3, SE-2, SE-1 0.3, 0.3, 0.3 0.11 S

S-1, S-2, S-3, S-4 0.4, 0.4, 0.4, 0.3 0.19 SSW SU-1, SW-2 0.8, 0.5 0.46 SW SW-3, SU-4 0.4, 0.5 0.26 WSW W-2 0.5 0.31 W

W-1, W-3, W-5, W-4 1.2, 0.5, 0.6, 0.4 0.49 WNW NW-3, NW-1 0.8, 1.7 1.06 NW NU-5, NV-4, NV-2 0.4, 0.3, 0.4 0.18 (0.15)**

NNW xNet mR = (Total mR) - (0.19 mR 8kgd.)

sxValue interpolated from adjacent sectors.

127 W7

~

4

21 Table 3-6.

NRC TLD DATA FOR 4/2/79 - 4/3/79 DIRECTION STATION CODES TOTAL EXPOSURE 8 0-10 MILE DOSE (mR)

(area)

N N-1, N-2, N-3, N-4, N-5 0.37, 0.45, 0.43, 0.48, 0.53 0.26 NNE NE-1, NE-2, NE-3 O.45, 0.48, 0.42 0.26 NE NE-4 0.37 0.18 ENE E-1 0.53 C. 34 E

E-3, E-4, E-1A 0.42, 0.4, 0.73 0.33 ESE E-2 0.55 0.36 SE SE-5, SE-4 0.74, 2.1 1.23 SSE SE-3, SE-2, SE-1 2.8, 4.4, 9.1 5.21 S

S-1, S-2, S-3, S-4 2.2, 1.5, 1.5, 1.4 1.46 SSW SW-1, SW-2

1. 2, 1. 3 1.06 SW SW-3, SW-4 0.78, 0.75 0.57 USW W-2

1. 0 0.81 W

W-1, W-3, W-5, W-4 1.4, 0.78, 0.9, 0.67 0.75 WNW NW-3, NW-1 0.63, 1.3 0.77 NW NU-5, NW-4, NW-2 0.42, 0.40, 0.62 0.29 NNW (0.27)**

A Net mR = (Total mR) - (0.19 mR 8kgd. )

~

xxValue interpolated from adjacent sectors 127 188

22 Table 3-7.

NRC TLD DATA FOR 4/3/79 - 4/4/79 DIRECTION STATION CODES TOTAL EXPOSURE

• 0-10 MILE 00SE (mR)

(arem)

N N-1, N-2, N-3, N-4, N-5 0.32, 0.40, 0.32, 0.33, 0.37 0.16 NNE NE-1, NE-2, NE-3 0.32, 0.37, 0.38 0.17 NE NE-4 0.38 0.19 ENE E-1 0.32 0.13 E

E-3, E-4, E-1A 0.40, 0.35, 0.38 0.19 ESE E-2 0.55 0.36 SE SE-5, SE-4 0.42, 0.30 0.17 SSE SE-3, SE-2, SE-1 0.57, 0.87, 0.43 0.43 S

S-1, S-2. S-3, S-4 1.1, 0.52, 0.47, 0.33 0.42 SSW SW-1, SW-2 1.1, 0.37 0.55 SW SU-3, SW-4 0.65, 0.62 0.45 USW W-2 0.62 0.43 W

W-1, W-3, W-5, W-4 1.7, 1.1, 0.65, 0.42 0.78 WNW NU-3, NU-1 0.40, 0.30 0.16 NW NW-5, NW-4, NW-2 0.42, 0.30, 0.40 0.18 (0.17)**

NNW xNet mR = (Total mR) - (0.19 mR Bkgd. )

xx Value interpolated frca adjacent sectors 127 189

23 Tah': 3-8.

NRC TLD DATA FOR 4/4/79 - 4/5/79 DIRECTION STATION CODES TOTAL EXPOSURE

• 0-10 MILE COSE (mR)

(arem)

N N-1, N-2, N-3, N-4, N-5 0.28, 0.33, 0.34, 0.37, 0.35 0.14 NNE NE-1, NE-2, NE-3 O.45, 0.33, 0.37 0.19 NE NE-4 0.33 0.14 ENE E-1

2. 6 2.41 E

E-3, E-4, E-1A 0.50, 0.43, 1.7 0.59 ESE E-2 0.38 0.19 SE SE-5, SE-4 0.37, 0.53 0.26 SSE SE-3, SE-2, SE-1 0.45, 0.38, 0.92 0.39 5

S-1, S-2, S-3, S-4 0.37, 0.32, 0.40, 0.45 0.20 SSW SW-1, SW-2 0.37, 030 0.15 SW SW-3, SW-4 0.45, 0.45 0.26 WSW W-2 0.72 0.53 W

W-1, W-3, W-5, W-4 1.3, 0.42, 0.60, 0.45 0.50 WNW tal-3, N',l-1 0.38, 0.38 0.19

?N NW-5, tN-4, fM-2 0.32, 0.37, 0.33 0.15 (0.14)**

NNW xNet mR = (Total mR) - (0.19 mR Bkgd.)

xxValue interpolated from adjacent _ sectors 127 190

24 Table 3-9.

NRC TLD DATA FOR 4/5/79 - 4/6/79 DIRECTION STATION CODES TOTAL EXPOSURE

• 0-10 MILE DOSE (mR)

(mrem)

N N-1, N-2, N-3, N-4, N-5 0.32, 0.48, 0.47, 0.42, 0.48 0.26 N-1A, N-1C, N-1E, N-1F 0.50, 0.50, 0.40, 0.47 NNE NE-1, NE-2, NE-3 0.38, 0.47, 0.46 0.25 NE NE-4, NE-3A 0.40, 0.38 0.20 ENE E-1 0.50 0.31 E

E-3, E-4, E-1A 0.48, 0.42, 1.2 0.51 ESE E-2 0.45 0.26 SE SE-5, SE-4, SE-4A 0.62, 0.47, 0.33 0.28 SSE SE-3, SE-2, SE-1 0.40, 0.35, 0.40 0.19 5

S-1, S-2, S-3, S-4, S-1A 0.35, 0.35, 0.40, 0.55, 0.35 0.21 SSW SW-1, SW-2 0.37, 0.43 0.21 SW SW-3, SW-4 0.38, 0.50 0.25 WSW W-2, W-3A 0.37, 0.65 0.32 W

W-1, W-3, W-5, W-4 0.57, 0.38, 0.40, 0.45 0.26 1.'NW NW-3, NW-1 0.40, 0.52 0.27 tid NW-5, NW-4, NW-2 0.48, 0.32, 0.35 0.19 NNW N-18, N-1D 0.40, 0.35 0.19 aNet mR = (Total mR) - (0.19 mR Bkgd.)

\\27 \\9i e

25 Table 3-10.

NRC TLD DATA FOR 4/6/79 - 4/7/79 OIRECTION STATION CODES TOTAL EXPOSURE

• 0-10 MILE DOSE (mR)

(arem)

N N-1, N-2, N-3, N-4, N-5 0.43, 0.4, 0.50, 0.48, 0.52 N-1A, N-1C, N-1E, N,1, 0.47, 0.45, 0.44, 0.37 0.26 NNE NE-1, NE-2, NE-3 0.45, 0.47, 0.45 0.27 NE NE-4, NE-3A 0.43, 0.57 0.31 ENE E-1 0.48 0.29 E

E-3, E-4, E-1A 0.32, 0.22, 0.32 0.10 ESE E-2 0.35 0.16 SE SE-5, SE-4, SE-4A 0.38, 025, 0.25 0.10 SSE SE-3, SE-2, SE-1 0.25, 0.25, 0.55 0.16 S

S-1, S-2, S-3, S-4, S-1A 0.40, 0.43, 0.55, 0.42, 0.43 0.26 SSW SU-1, SW-2 0.45, 0.38 0.23 SW SW-3, SW-4 0.42, 0.50 0.27 WSW W-2, W-3A 0.38, 0.45 0.23 W

W-1, W-3, W-5, W-4 0.48, 0.47, 0.57, 0.57 0.33

\\Jat NU-3, NU-1 0.42, 0.45, 0.3G 0.29 NW NW-5, NW-4, NW-2 0.45, 0.45, 0.38 0.24 NNW N-1B, N-1D 0.50, 0.50 0.31

~

aNet Mean mR = (Total mR) - (0.19 mR Skgd.)

\\27 192

26 Table 3-11.

NRC TLD LOCATIONS STATION DISTANCE DIRECTION SECTOR DESCRITTION E-1

.5 mi 61 ENE 1200' N of E-la NE-1

.8 mi 25*

NNE North Gate NE-2

1. 8 mi 19 NNE Geyers Ch N-1 2.6 mi 358 N

Middletown NE-3 3.1 mi 17 NNE Township School NE-4 6.7 mi 47 NE N-2 5.1 mi 360 N

Clifton N-3 7.4 mi 6

N Hummelstown N-4 9.3 mi 360 N

Union Deposit N-5 12.6 mi 3

N fM-5 13.8 mi 312 fN Harrisburg tN-4 9.6 mi 306 NW Harrisburg fM-3 7.4 mi 297 KtN New Cumberland fN-2 5.9 mi 310 fN Highspire fN-1

2. 6 mi 303 WNW Harrisburn Airport W-1 1.3 mi 263 W

Goldsboro W-2

1. 3 mi 252 WSW Goldsboro SW-1 2.2 mi 200 SSW Bashore Island W-3

2. 9 mi 270 W

Unnamed community

~

W-5

1. 4 mi 262 W

Lewisberry W-4 5.9 mi 272 W

Lewisberry SW-2

2. 6 mi 203 SSW Pleasant Grove 5-1 3.2 mi 169 5

York Haven S-2 5.3 mi 178 5

Conewago Hts S-3 9.0 mi 181 S

Emigsville SV-3 8.3 mi 225 SW Zions View SW-4 10.4 mi 225 SW Eastmont S-4 12.0 mi 184 S

Woodland View SE-5

7. 0 mi 135 SE Bainbridge SE-4 4.6 mi 137 SE Highway 441 SE-3 2.3 mi 160 SSE Falmouth SE-2

1. 9 mi 162 SSE Falmouth SE-1

1. 0 mi 151 SSE Unnamed community on Highway 441 E-2

2. 7 mi 110 ESE Unpopulated area E-3 3.9 mi 94 E

Newville E-4

7. 0 mi 94 E

Elizabethtown E-la

0. 4 mi 90 E

Residence S-la 3.35 mi 173 5

School (added 4/5/79)

SE-4a 5.0 tr.i 146 SE W-3a 4.4 mi 247 WSW NE-3a 3.6 mi 44 NE N-la 2.4 mi 356 N

N-lb 2.75 mi 346 NtG N-1c 3.0 mi 0

N N-1d 3.5 mi 333 NNW

}[

k9 N-le

3. 5 mi 349 N

N-lf 4.0 mi 351 N

e

Jable 3.12..,

PROJECTED 1980 POPULATION DISTRIBUTION, 0-10 MILES THREE MILE ISLAND NUCLEAit STATION, UNIT 2 (FROM FIG. 2.1-5 of SAR)

Oistance (Miles)

~

Sec to r_

0-1 1-2 2-3 34 4-5 5 - 10 0 - 10 N

19 212 3,970 3,772 415 11,840 20,228 NNE 55 75 169 480' 373 11,223 12,375 NE 42 134 2 71 428 186 2,246 3,307 ENE 58 55 lc6 461 262 1,567 2,589 E

42 60 39 137 552 10,431 11,261 ESE 6

36 149 214 236 2,809 3,450 SE 6

94 67 203 395 2,095 2,854 SSE 88 197 117 78 43 3,840 4,364 5

0 0

136 81 7 1,31 7 12,190 14,460

\\

SSW 84 98 584 217 752 6,883 8,610 SW 84 104 1 81 562 219 4,297 5,447 WSW 29 273 117 796 237 2,961 4,41 3 W

36 369 36 331 571 7,155 8,498 WNW 22 106 253 197 235 11,823 12,636 NW 39 106 64 41 1,177 29,482 30,909 NNW 48 98_

1,240 942 1,921 16,632 20,881 658 2,017 7,579 9,676 8,891 136,474

. 166,295 e

9 as.

m

~

~

127 194

- -.... =

L

.. =. -

3

'[,,

Table 3.13.

PROJECTED 1980 FOPULATION DISTRIBUTION,10-50 MILES THREE MILE ISLAfiD tiUCLEAR STATION, UNIT 2

\\

(FROM FIG. 2.1-10 of SAR)

Distance (Miles)

Total

~

Sector 10-20 20-30 30-40_

40-50 10-50 N

12,663 9,005 8,941 47,588 78,197 NNE 18,240 6,856 14,478 45,115 84,659 NE 30,726 38,979 9,546 62,345 150,595 ENE 10,205

.14,757 45,445 177,672 284,079 E

18,853 62,028 42,445 38,754 162,080 ESE 34,339 124,988 27,822 42,737 229,886 SE 20,152 10,000 10,600 26,958 67,710 SSE 44,204 10,774 15,097 66,763 136,838 1,

5 111,002 l' 648 13,477 75,781 214,908

(

SSW 31,917 44,031 18,596 37,729 132,273 SW ll,801 19,931 25,536 18,979 76,247 WSW 5,882 7,996 8,948 23,010 45,836 W

21,769 35,025 10,370 20,602 87,766 WNW 70,460 14,188 5,333 3,681 93,662 NW 99,593 9,308 9,970 12,630 131,501 NNW 26,482 10,517 7,256 12,866 57,121 Total 577,288 433,001 273,860 713,210 997,359

/*

( -

.i 127 1

5 f

I

, - + = = = = - '

I

29 Table 3-14.

ESTIMATED MAXI l'UM DOSE TO AN INDIVIDUAL (Located east or northeast of the site)

Cumulative Total dose (mrem)

Period (1979)

Estimated Dose (mrem)

(to nearest mrem) 3/28 - 3/29 45 45 3/29 - 3/31 29 74 3/31 - 4/1 8

82 4/1 - 4/2 0

82 4/2 - 4/3 1

83 4/3 - 4/4 0

83 4/4 - 4/5 1

84 4/5 - 4/6 2

86 4/6 - 4/7 0

86 127 196

30 Table 3-15.

ESTIM/$TED COLLECTIVE DOSE (person-rem)

~

Total Cumulative Period 0-10 10-50 0-50 Total, 0-50 miles 1979 miles miles miles (to nearest 50) 3/28-3/29 206

$11 717 700 3/29-3/31 764 524 1288 2000 3/31-4/1 537

'215 852 2850 4/1-4/2 44 35 79 2950*

4/2-4/3 109 133 242 3200 4/3-4/4 39 43 82 3260 4/4-4/5 49 82 131 3400 4/5-4/6 41 39 80 3450 4/6-4/7 42 35 77 3550"*

1831 1717 3548

^ In the originai as!.essment, which formed the basis of testimony before the Senate Subcommittee on Health and Scientific Research, this value was estimated to be 1800.

• n In updates of the original estimate, which formed the basis for testimony before the Senate Subcommittee en Nuclear Regulation, this value was estimated to be 2,500.

127 197 4

e

31 8.

Onsite Metropolitan Edison Oosimetry Data for the ceriod through March 31, 1979 Data made available to the Ad Hoc Group on April 12, 1979, indicated that there were some dosimeter readings reported in excess of 100 arem.

These readings greater than 100 mrem are listed below.

These dosimeters were on the site or at sites under the' licensee's control.

The dosimeters with high results on Shelley Island are within the exclusion area of the site.

A map shcwing these dosimeter sites and other Metropolitan Edison dosimeters within 1 mile of the nuclear station is given in Figure 3-2.

Dosimeter Desionation Location Period Dose, mrem TM-16Al 0.4 mi NNW (Kohr Is.)*

9/27/78 - 3/29/79 908 TM-16A1A 0.4 mi NNW (Kohr Is.)*

9/27/78 - 3/29/79 453 TM-1452 0.4 mi WNW (Shelley Is)*'

9/27/78 - 3/29/79 131 TM-1452A 0.4 mi WNW (Shelley Is)*

9/27/78 - 3/29/19 156 TM-16S1 0.2 mi NNW, West Gate 12/27/78 - 3/25/79 1049 TM-1151 0.1 mi SW, W of Cooling Tower on Dike 12/27/78 - 3/31/79 216 TM-1151A 0.1 mi SW, W of Cooling Tower on Dike 3/29/79 - 3/31/79 107 TM-4S2A 0.3 mi ENE, Top of Dike East fence 3/29/79 - 3/31/79 124 Statement by Teledyne Isotopes Inc., "These gross exposures were obtained in the absence of designated control dosimeters for subtracting transit doses and system background."

Since the majority of these dosimeters were onsite they are not considered in the population dose.

The dose received by those onsite will be recorded e

127 198 4

.au lJ SA)

M g 'lu i 6; ',t,.,..

6

, 'O '

.d a - [. ) :,,..9' -. T)

S 4. w.

dhtjib

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~

l R

Siq d'r *4 '*~% 7kJD i

h k : %, -

452

[

k

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p

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go[b k

l g.,]

Q

},:,h

,'s

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16S1 T':,r>ND/::

h m "f9s2 %v fdllo$,(slo,g 1Q115;m m[3~.N.T'i,5jy E m s.p n,, u

~

l'I.ji

~

% ~ s MS2 T

y

.c1,ugu "NTO;, sh g;.p.pg;;%'yp

)/

~c-

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ss

.l

~g% y g p: g.g. v J[. y.! O., 'i.: ',_ j#

~

Q....

M<eQ... e w gjs' Q-o,

'N i,

' M Wl ). h.

'k N

N. E'd N'Q@u?bw: a Ph S,Ollg,

/

N.,

s W

' m Wgp.

s s

4

,s/

n,., -

N w Q, w[gg--

y fa c

%c/

m th \\

%s-Oi.h \\

=.

1001

.'l$,ll (L.) i. : L,,. _

i 3,*i fg

~ *wW 99'::pn,>Og'lg p, '.9 e

j'.,M., fl 'i.' %

Mw.

l h

~ = m,~.

D;?2Wl%;.y&.

&f%kh

=-

a d n~.'A,M e d,

- ~a

- T C

7 5 i n 3-2.

f

=teo"n$@"yjy"Uif

':1Ty"M@

f[ach a the u 16 t arc i 31.1979-5,-

g.

W. n, %,

~

e x m~mqga. p,.17' s

ay

.~

4 4

gsg 4 O

32 in the dosimeters worn by each individual.

The two readings from Kohr Island were also not considered for the population dose since it has been verified that no people were on this site during the accident period.

e e

127 200 4

33 4.

POTENTIAL HEALTH IMPACT A.

Health Effects from Low-Level Radiation The health risks from low-level radiation are derived by assuming that the effects obsarved at high doses from high dose rates can be directly and linearly extrapolated to low doses delivered at very much lower dose rates and also by assuming that there is no absolutely safe dose (or threshold) below which there is no health risk (linear, non-threshold, dose-rate-independent dose-effect relationship).

These assumptions are generally believed to overestimate the health risk from low-level ionizing radiation (1-3).

There are two different types of health risk estimates used in the 1972 BEIR report, one of which is approximately 2 to 5 times higher than the other.

The value: used represent the geometric mean (a kind of average) of the two risk esi.imates.

The average was used in an attempt to reconcile the two types of estimates.

The resultant somatic health risk factors are shown in Table 4-1.

(1) International Commission on Radiological Protection, " Recommendations of the International Commission on Radiological Protection Adopted January 13, 1977" ICRP Publication 26, Pergamon Press, Oxford (1977) Section E pp 6-7.

(2) National Comacil on Radiation Protection and Measurements, " Review of the Current Sta'c of Radiation Protection Philosophy."

NCRP Report No. 43, NCRP, Washington, D.C. (January 15, 1975) p.4.

(3) Advisory Committee on the Biological Effects of Ionizing Radiation (BEIR)

"The Effects on Populations of Exposure to Low Levels of Ionizing Radiation,"

National Academy of Sciences - National Research Council, Washington, D.C.

November 1972, Chapter VII,Section IV pp 87-88.

127 201

34 Table 4-1

~

Estimates of the Scmatic Health Risk frcm Low-Level Ionizing Radiation Effect Health Risk (deaths) per 10 person rem ( )

6 Range Nominal Value Used for

" Average"(b) this Analysis Leukemia 26 to 37 31 Other Fatal Cancers:(c) 61 to 429 160 TOTAL FATAL CANCERS 191 200 Thyroid Cancer 100 to 200 cases (d) 140 cases NON-FATAL CANCER 200 aThe risk values presented are based upon the BEIR Report (3) or interpretations thereof.

bThe " nominal average" risk values presented are based upon linear extrapolations of data obtained at high doses and dose rates to predict somatic effects at low doses and lower dose rates.

These values indicate the range of values and were obtained by applying the absolute risk estimates with a 30 year plateau duration and by applying the relative risk estimates with a lifetime plateau duration for "other fatal cancers."

The ncminal average values are geometric means of the risk values at the ends of the range (i.e., the square root of the product of the values).

CThe number of cases in this category may be twice the number of deaths.

"Other fatal cancers" includes lung, GI tract, bone, kidney, and liver plus other sites.

The deaths due to these cancer are projected assuming the susceptibility of cancer induction by radiation in persons aged less than 10 years is equal to that for persons aged 10 years or more.

dThyroid cancer risks are treated separately owing to the relatively high survival rate compared to the cancers at other sites considered here.

The range of risk values indicated is based on the relative risk model with a 30 year and lifetime plateau duration.

The lifetime survival rate for persons treated for thyroid cancer is about 80 to 90 percent.

127 202 l

35 It is firmly established that ionizing raciation can cause genetic muta-tions, which can be manifested as congenital anomalies (birth defects) or hereditary diseases such as hemophilia or Down's syndrome, in descendents of an irradiated parent or parents.

However, the exact numerical value for the risk of genetic injury from low doses is uncertain.

The genetic effects estimated in 197? Report of the Advisory Committee on the Biological Eifects of Ionizing Radiation 3 are ba' sed upon estir.ates that the radiation dose that would double the natural incidence of genetic anomalies (doubling dose) is between 20 and 200 rem (20,000 and 200,000 mrem).

The lower the doubling dose, the graater the risk from a given radiation dose.

Table 4-2 summarizes the calculation of the genetic risk from the data given in the 1972 BEIR report.

Table 4-3 summarizes the actual health risk estimators used in this analysis.

6 4

e

Table 4-2 Estimates of Genetic Ef fects of Low-Level ionizing Radiation Disease Classification fla tura l Effects per 10 live Estimated Risk 6

Incidence births (*) of 5 rem per per 10 person rem (C) 6 6

(re

• 10 live generation (b) births)

First Generation Equilibrium first beneration Equilibrium Dominant diseases 10,000 50 to 500 250 to 2500s.

6 to 60 30 to 300 Chromosomal and recessive diseases 10,000 relatively very slow relatively very slow slight increase slight increase Congenital anomalies 15,000 Anomalies expressed later 10,000 5 to 500 50 to 5,000 0.6 to 60 6 to 600 Constitutional and degenerative diseases 15,000 TOTAL 60,000 60 to 1000 300 to 7500 7 to 120 36 to 900 6

Risk per 10 people 1,200(d)/ year Geometric Mean 180 (a)From the 1972 BEIR Report (3), Table 4 p. 57 which is believed to be erroneously titled.

~

N This table, like the precedin0 tables 2-3 pp. 54-55, is believed to be for a population of one million " live births" not for a population of one million.

The range of values corresponds to assumed doubling doses between N

20 rem (high values) and 200 rem (lower values).

(b)A generation is assumed to be 30 years.

o (c) Risk per 106 6

person rem = (cases /10 live births) x (30 years /5 rem) x (4 x 106 live births / year per 0

6 2 x 10 people) = 0.12 x cases /10 live births.

(d) Cases /106 6

8 live births x (4 x 10 live births per year / 2 x 10 eople).

37 Table 4-3 Summary of Health Risk Estimates Used in This Analysis Risk per Effects per 6

rem 10 erson-rem

~4 Fatal Cancers 2

x 10 200

~4 Non-Fatal Cancers 7

.( 10 200

-4 Genetic Effects 1.8 x 10 180 TOTAL POTENTIAL

-4 HEALTH EFFECTS 5.8 x 10 580 4

e 4

127 205

38 B.

Ccmoarison of Doses to Individuals from the TMI Accident with Natural Backcround Radiation and its Variability Man is continually exposed to ionizing radiation which occurs naturally.

There are three primary sources of this natural radiation " background":

(1) solar and galactic cosmic radiation, (2) long-lived radionuclides in the earth's crust (primordial radi6nuclides) and (3) radionuclides formed in tha upper atmosphere from the interactions of the cosmic radiation with gases in the atmosphere (cosmogenic radionuclides).

The magnitude and variation in the radiation dose from these natural radiation sources provides one baseline for comparing the doses and the potential health impact from the Three Mile Island accident.

Estimates of the dose from background radiation at several locations in the United States are shown in Table 4-4.

None of these values are measured values but they are generally consistent with reported measurements.( -5)

Table 4-5 compares the estimated individual doses from the Three Mile Island accident to some of the variations in annual radiation doses from background radiation.

It should be noted, however, that the " background" doses are delivered over 1 year whereas the accident doses were delivered over only a (4)D. T. Oakley, " Natural Radiation Exposure in the United States," EPA Report ORP/SID 72-1, U.S. Environmental Protection Agency, Washington, D.C. (1972).

(5) National Council on Radiation Protection and Measurements, " Natural Back-ground Radiation in the United States" NCRP Report No. 45, NCRP, Washington, D.C., November 15, 1975.

127 206

e 39 few days.

The pcasible significance of this higher dose rate is discussed in a following section on dose-rate effects.

It should also be noted that the

" average" doses to individuals within 10 and within 50 miles of the site are numerical averages obtained by dividing the collective population doses by the size of enclosed population.

Clearly, some individuals received more than this dose and others less, depending upon wind direction and distance from the TMI site.

40 Table 4-4 Estimates of Natural " Background" Radiation Levels in the United States Annual Dose Rate (mrem / year) location Cosmic Terrestrial Internal Total Radiatfon( )

Radiation ( )

Radiation ( )

Atlanta, Georgia 44.7 57.2 28 130 Denver, Colorado 74.9 89.7 28 193 HARRISBURG, PA.

42.0 45.6 28 116*

Las Vegas, Nev.

49.6 19.9 28 98 New York, NY 41.0(C)

45. fi(c) 28 115 PENNSYLVANIA 42.6 36.2 28 107 Washington, DC 41.3 35.4 28 105 UNITED STATES40-160 0-120 28 70-310

( )From [(4) Table A-1]

(b) Based upon total of internal (gonadal) doses from [(5) Tables 42 and 43, p. 104].

(c)From [(4) Table A-2]

s Earlier estimates used an approximate value af 125 mrem / year based upon the Final Environmental Statement for the Three Mi'e Island Facility (AEC, 1972, Section VD 7, p. V-28).

As neither vaice: represents direct measure-ments and ambient radiation dose rates are expected to vary by at least 25%

between locations within a 50-mile radius, these estimates are essentially identical.

O 127 208

41 Tiole 4-5 Comparison of Individual Doses from the Three Mile Island Accident With Variations in Natural Background Radiation Doses Source of Radiation Exposure CUMULATIVE lHREE MILE ISLAND TOTAL BDDY DOSES ACCIDENT DELIVERED THRU 4/7/79 Individual remaining out-of-doors at location of highest estimated offsite dose 86 mrem Average dose to a typical individual within:

50 miles of sice 1.6 mrem 10 miles of the site 11 mrem ESTIMATED DIFFERENCE IN NATURAL BACXGROUND VARIATION ANNUAL DOSES Living in Denver, Colorado compared to Harrisburg, PA

+ 80 mrem /yr (from Table 4-4)

Living in a brick house instead of a frame house [Yeates data in (4)

Table 16, p. 35]

+ 14 mrem /kr Added dose from pocassium-40 due to being male instead of female

+

4.8 mrem /yr (There is 25% less potassium in women than men [(5), p. 106])

127 209 f

42 C.

Comoarison of the Potential Health Imoact Estimated for the TMI Accident with Existing Cancer Rates and Risks Cancer is the second leading ccuse of death (next to heart disease) in the United States [(6) p. 14)].

The Vital Statistics of the United States, 1976* shcws that there were 377,312 deaths in the U.S. from cancer, which corresponds to a rate of 175.8* cancer deaths per 100,000 people [(6) p. 14].

Cancer deaths accounted for approximately one-fifth (0.198) of all deaths in the U.S. in 1976.

The existing cancer rate provides an indication of the possibility of detecting any potential increase in cancer incidence.

The cancer death rate for the State of Pennsylvania estimated by The American Cancer Society [(6) p. 12] is 208 per 100,000 (2.08 x 10-3),

Maryland has a lower estimated rate (179 per 100,000) which is closer to the estimated U.S. rate of 180 per 100,000 [(6) p. 12].

Applying these values to the 2,165,651 people estimated to reside within 50 miles of tha Three Mile Island site gives an estimate of 3,900 (U.S.) to 4,500 (Pa) deaths per year for the existing cancer death rate for the population within 50 miles of the TMI site.

Table 4-6 shows the estimated incidence (number of new cases) and death rate for the U.S. population for selected types of cancers.

• 0ur earlier estimates used 1974 statistics and a U.S. cancer death rate of 170.5 per 100,000.

(6)From American Cancer Society, " Cancer Facts and Figures-1979," Reproduced by permission of the American Cancer Society who retains copyrignt.

Sub-sequent quotations should acknowledge the American Cancer Society as the source of these values.

127 219

43 Table 4-6 Ed.imated flew Cancer Cases and Deaths in the United States for 1979 (Existing Rates)

Cancer Site Estimated

• Estimated

• Deaths / Cases ( )

' flew Cases Deaths Digestive Organs 182,900 105,150 0.57 Lung 112,000 97,500 0.87 Bone 1,900 1,750 0.92 Skin (b) (excluding melancmas) 300,000 1,500 0.005 Breast 106,900 34,500 0.32 Genital Organs 143,500 44,800 0.31 Leukemia 21,500 15,400 0.72 Thyroid 9,000 1,000 0.11 All Sites 765,000 395,000 0.52 (a)If cancer rates and the population (and its age composition) were constant this ratio would be a measure of the probability of dying from having specified types of cancer.

As neither existing cancer rates nor the U.S.

population and its age breakdown are constant, this is only an approximate measure of severity of cancers at a particular site.

( ) Melanoma is a skin cancer which has not generally been found to result frcm radiation exposure.

For this reason, melanoma data has been excluded, although it is the predominant form of skin cancer and has a high mortality

~

rate.

From American Cancer Society, " Cancer Fact.s and Figures-1979" p.10.

Repro-duced by permission of the copyright holder, the American Cancer Society.

All subsequent quotations of these values should acknowledge the American Cancer j

Society as the source of these estimates.

127 211

44 The American Cancer Society [(6) p. 14] estimates that, out of 100,000 people, 25,000 will eventually develop cancer and, of these 25,000, about 15,000 will eventually die of cancer.

This gives an estimate of the risk of cancer death of 0.15.*

Applying this approximate statistic to the 2,165,651 people within 50 miles of the Three Mile Island site indicates that approximately 325,000 people in that area would normally die of cancer.

o AAn earlier estimate of 0.12 was obtained by multiplying the 1974 annual death

-3 rate of 1.7 x 10 by 70 years.

127 212 f

~

4

45 D.

Summary of the Health Imoact Table 4.7 shows the estimated potential health effects from the Three Mile Island Nuclear Accident associated with the estimated 3,550 person-rem delivered to the population within 50 miles of the reactor.

These estimates consider fatal cancers, non-fatal cancers and genetic ill-health to all future generations.

The total number of future fatal cancers is less than 1 (0.7).

The additional number of non-fatal cancers is the same.

The total estimated health impact of the accident (through April 7,1979) to the population residing within 50 miles is 2 additional ill-health effects.

This value and those for the cancers are small compared to either the existing annual incidence of similar effects or the potential effects estimated to result from the natural background radiation.

Comparing the total potential health impact of the accident with the estimated life-time natural risk indicates that these effects, if they occur, would be undetectable.

The added lifetime risk of fatal cancer to the hypothetical maximum exposed individual from the accident is 1.9 x 10-5 (0.000019).

This is based upon a presumed 100 mrem dose rather than the calculated 86 mrem value.

This is extremely small (0.013%) compared to the normal risk (0.15) to an individual of dying from cancer.

It is also small (1.1 percent) compared to the potential lifetime fatal cancer risk that would be associated v ith natural background radiation using the same dose-to-health effect relationships as used for the accident impact.

127 213

Table 4-7 Projected Potential llealth Impact of the Three Mile Island Accident Upon the Population within 50 miles (a)

Annual Rates Cumulative llealth Risk Estimated Potential Estimated Potential Impact of Potential Impact of from Existing Impact of flumber who will fiatural Backgroand TMI Accident Rates (b) flatural eventually Radiation (d)

thru 4/7/79

Background

develop effect

(% of normal

(% of normal incidence)

Radiation (c) incidence)

S fatal Cancers 3,900 54 per year 325,000 3,790 (1.2%)

0.7 (2.2 x 10-4 )

flon-Fatal Cancers 4,900 54 per year 216,600 3,790 (1.8%)

0.7 (3.2 x 10-4 )

Genetic Effects 2,600(") 49 per year (*)

78,000(I) 1,460 (1.9%)(I) 0.64 (8.2 x 10-4 )

Total llealth Impact 2.0 Effects

( )2,165,650 projected for 1980.

(b) Based upon U.S. statistics.

(c)A 0.125 rem per year (125 mrem / year); approximately 270,700 person rem.

(d)70 year cumulative exposure.

(")From BEIR 1972 estimates given in Table 4.2 of 1,200 per 10 people.

6 IOftased upon a 30 year reproductive period.

N N

N 4

47 E.

Dose-Rate Effects

~

The estimated dose to a hypothetical individual (85 mrem) is numerically approximately the same as the annual dose from natural background radiation to residents in the Harrisburg area (115-125 mrem /yr).

There has been some concern that, be;ause this dose was delivered in 1 week instead of 1 year, the biological effects of this' accident would be greater than from natural background radiation.

This reasoning presumes a " dose-rate" effect rather than the linear dose-rate-independent dose ef fect model.

If there were such a " dose-rate effect," then the health consequences of the accident would be overestimated and not underestimated.

This is because the estimates of the' health effects of low-level radiation are derived from observations made at much higher doses and dose-rates than experienced during the Three Mile Island Accident.

Existing estimates indicate that somatic effects (cancer) might be over-estimated at low doses by a factor of 2 to 4 (7, 8) and perhaps as much as a factor of 10 (8) and that genetic effects might be overestimated by a factor of 3 (8).

The estimates of the health impact of the Three Mile Island Accident have not included any reduction factor to account for dose-rate effects.

(7) United Nations Scientific Committee on The Effects of Atcmic Radiation,

" Sources and Effects of Ionizing Radiation - 1977 Report", UNSCEAR, United Nations, N.Y.,

N.Y. (1977), Annex G, p. 366, paragraph 36.

(8)NCRP Scientific Committee 40, " Influence of Dose and its Distribution in Time on Dose-Effect Relationships for low-LET Radiation" Draft of February 21, 1979, page 3.

127 215 e

48 5.

OTHER SOURCES OF EXPOSURE A.

Skin Doses and Health Risks from Beta and Gamma Radiation from Xenon-133 s

The contribution of beta particles from xenon-133 is not addressed by either the dose analysis in Section 3 or the health impact analysis in Section 4.

While the beta dose cannot be assessed by direct measurement during the accident, it can be estimated from the literature.

The depth dose from xenon-133 electrons and beta particles decreases by a factor of 0.39 at an areal density in tissue of 0.005 g/cm2 (or a depth of 0.005 cm or 50 pa).

This depth was selected to approximate the thickness of the " dead layer" of skin.(1-2)

The depth dose to blood forming organs from beta particles is essentially zero.

The beta particle skin dose at the 50 pm depth, estimated from the depth dose calcula-8 tions of Berger(3) is 4.7 x 10 mrem /yr per pCi/cm" compared to ORNL [ David Kocher, ORNL, personal communication to C.B. Nelson] estimates of the xenon-133 8

3 gamma-ray total body dose of 1.90 x 10 mrem /yr per pCi/cm, or a factor of 8

2.47 higher.

The gamma-ray skin dose is 2.55 x 10 mrem /yr per pCi/on? Therefore, (1)" Recommendations of the International Commission on Radiological Protec-tion Adopted January 27, 1977," ICRP Publication 26.

Pergamon Press, Oxford, England, paragraphs (63) and (64), p.

13.

(2) National Council on Radiation Protection and Measurements, " Krypton-85 in the Atmosphere - Accumulation, Biological Significance, and Control Technology," NCRP Report No. 44, National Council on Radiation Protection and Measurements, Washington, D.C.,

July 1, 1979.

Table 13, p. 30.

(3)M.J. Berger, " Beta-ray dose in tissue-equivalent material immersed in a radioactive cloud," Health Physics, vol. 26 (1): 1-12 (January 1974).

?

127 216

~

49 8

the cc=bined beta and gamma " skin" duse is 7.25 x 10 mrem /yr per pCi/cm, or a factor of 3.8 times the total body gamma-ray dose.

The TLD readings were assumed to be equivalent to the total body gamma-ray dose.

For the maximum exposed individual, the beta skin dose would be about 325 mrem.

The 1972 report of the National Academy of Sciences' Advisory Committee on the Biological Effects of Ionizing Radiation (4) does not provide numerical estimates of the risk at low doses for skin cancers.

Skin cancers from radia-tion exposure reported in this report are associated with doses above 230,000 mrem in rats and above 450,000 mrem in humans.

This latter dose is sufficient to cause visible effects on the skin and is more than a factor cf 1,000 greater than the estimated total (beta and gamma) skin dose to any exposed individual, even neglecting shielding by clothing or by being indoors.

The International Commission on Radiological Protection considers skin to b3 less liable to develop fatal cancers after irradiation than other tissues (1).

The; recommend a lifetime occupational dose limit for skin of 2,000,000 mrem (1) or 5,000 mrem per year for members of the general public (Reference (1) p.

25).

It is also significant that the ICRP has considered the organ at the highest risk (critical organ) for exposure to radioactive noble gases such as xenon-133 to be the total body and not the skin or lung (5).

(4) Advisory Ccmmittee on the Biological Effects of Ionizing Radiation (BEIR),

"The Effects on Populations of Exposure to Low-Levels of Ionizing Radiation",

National Academy of Sciences - National Research Council (1972) pp 132-135.

(5)" Recommendations of the International Commission on Radiological Protection.

Report of Committee II on Permissible Dose for Internal Radiation," ICRP Publication 2, Pergamon Press, Oxford, England,1959.

127 217 e

e 50 The 1977 report of the United Nations Scientific Committee on the Effects of Atomic Radiation (6) provides estimates of the risk of skin cancer from exposure to high doses.

Neglecting two lower values of approximately 4 x 10',

the 50 year

• lifetime average risk from these data is estimated to be approxi-

-5 mately 1.9 x 10 If the entire population within 50 miles of the TMI site were exposed out-of-doors and without clothing for the entire duration of the accident, the total number of projected heal'h effects (fatal and non-fatal cancers, and genetic defects to all future generations) cou' Mcrease by about 12 percent (from 2.0 to about 2.2) due to all the skin cancers that might occur in the next 70 years.

Only about 6 percent [ Reference (6) Annex G Table 1, p. 363] of these skin cancers would be fatal, so the overall increase in cancer fatalities might be about 2 percent from 0.71 to 0.72.

Thus, the health impact of dose to the skin from beta and gamma radiation is a very small fraction of that estimated for external gamma ray exposure of the total body.

This is actually a life' ?me (70 year) risk since the assumed latent period between radiation exposure and the onset of cancer is 20 years.

Reported mean latent periods for skin cancer are 24.5 and 41.5 years (6) Table 1,

p. 363].

(6) United Nations Scientific Committee on the Effects of Atomic Radiation, UNSCEAR, " Sources and Ef-cts of Ionizing Radiation," 1977 Report, United Nations, N.Y. (197,) Annex G, Radiation Carcinogenesis in Man.

Section H., pp. 411-412.

51 8.

Inhalation Lung Dose and Risk of Lung Cancer The gamma total body dose from xenon-133 is given in NRC Regulatory

-4 3

Guide 1.109(7) Table B.1 as 2.94 x 10 mrem / year per pCi/m.

The xenon-133

-9 inhalation dose factor (8) is 1.57 x 10 mrem per pCi inhaled.

Multiplying this latter value by the annual volume inhaled per year (for an adult) of 3 3

-5 7.3 x 10 m / year gives an equivalent dose factor of 1.15 x 10 mrem / year 3

per pCi/m.

This value is approximately 4 percent, (0.039), of the external whole body dose factor for an equivalent air concentration of xenon-133.

-4 The lifetime lung cancer risk (frca Table 4-1) is 0.4 x 10 per rem or about one-fif th (0.2) of the risk of fatal cancer from total body irradiation.

Combining this with the above estimate of the relative lung-to-total-body dose of 0.039 yields an estimate for the risk of lung cancer due to xenon-133 inhalation of (0.039) (0.2) = 0.0078 or 0.8 percent of the total fatal cancer risk from external gamma irradiation frcm xenon-133.

This is a small increase in risk compared with the other uncertainties in the calculation of health risk.

(7)U.S. Nuclear Regulatory Commission, Regulatory Guide 1.109, Revision 1,

" Calculation of Annual Doses to Man from Routine Reactor Effluents for the Purpose of Evaluating Compliance with 10 CFR Part 50, Apper. dix I,"

October 1977, (8)G.R. Hones and J.K. Soldat, " Age-specific Radiation Dose Comnitment Factors for a One year Chronic Intake" U.S. Nuclear Regulatory Ccmmission Report NUREG-0172 (November 1977), Table 8, p. 38.

127 219

52 C.

Airborne Radiciodine Concentrations and Doses Metropolitan Edison placed charcoal cannister sampling systems in the environment to measure the concentration of radiciodine in air.

The NRC Office of Inspection and Enforcement (I&E), as part of their monitoring program, obtained air samples at " Trailer City" to measure the radiciodine air concentration.

The result obtained from these measurements are given belcw.

Location Period Concentrations 3

Observation Tcwer 3/29/79 - 3/31/79 20 pCi/m 3

2.3 mile SSE (2 x 10 il pCi/cm )

(Met. Ed)

Observation Tower 3/31/79 - 4/3/79 1.4 pCi/m_3 3

(Met. Ed)

(1.4 x 10 12 pCi/cm )

3 Trailer City 4/1/79 - 4/4/79

<9 x 10 13 pCi/cm NRC 3

Trailer City 4/5/79 1.6 x 10 12 pCi/cm NRC The measured radiciodine concentration' in air have been used to estimate maximum dose to a child's (receptor) thyroid using the inhalation dose factor in reference (7), p. 29.

127 220 e

e

53 Dose (mrem)

First three day period 3/29/79 - 3/31/79 concentration 2.3 mi SSE

2. 7 Second three day period 3/31/79 - 4/3/79 0.19 NRC data pCi/cm' for period assume 2 x 10 1 4/2/79-4/3/79 (some overlap with record three-day period) 0.18 3.1 D.

Thyroid Dose from Incestion of Iodine-131 ia Milk A large number of milk samples were collected during the period March 28 through April 4, 1979 from farms and dairies throughout the area surrounding the accident site by, the Pennsylvania Department of Environmental Resources, the Food and Drug Administration and Metropolitan Edison.

Aliquots of several of these were also analyzed by the Environmental Protection Agency.

A summary of the results is given below:

Metropolitan Pennsylvania FDA EPA Edison Number of analyses performed 133 84 4

21 Number of positive resul+.s 7

53 2

18 Average value of positive results (pCi/2) 15 19 17 7

Range of positive results (pCi/2) 11-20 9-41 10-24 1-41 Average minimum detectable activity (pCi/2)

<20

<10

<10

<1 e

127 221 4

54 Additional milk samples collected since April 4 have been negative.

This indicates that any iodine-131 ingested through milk consumption occurred during a period of a few days and can be treated as a single deposition event.

Using the highest concentration of iodine-131 observed in any single sample of milk as the worst case, 41 pCi/2 in goats milk, the dose to the thyroid of an infant drinking 1 liter of milk from that source for the entire duration of the accident would be 5 mrem over the lifetime of the individual.

This is derived from the protective action guide that relates 12,000 pCi/l to a 1.5 rem dose to the thyrcid.

Under these conditions, an adult drinking the same milk would receive a lifetime thyroid dose of 0.5 mrem, based on a thyroid weight 10 times greater than the infant (20 g versus 2 g).

Cesium-137 was also detected in some of the milk samples at levels generally less than 25 pCi/ liter.

The maximum reported level was 37 pCi/ liter.

The presence of this radionuclide is probably due to deposition of residual fallout produced from pr evious atmospheric testing.

Review of results from pasteurized milk samples analyzed for the pre 'ious year from Pittsburgh and Philadelphia by EPA show the presence of cesium-137 also for several samples during that period.

The levels were less than 12 pCi/J.

The Pittsburgh and Philadelphia samples represent milk samples composited from more than one source; the samples collected during the Three Mile Island incident represent specific farms and

~

dairies.

127 222

APPENDIX A Department of Energy (00E) Estimate of External Whole Body Radiation Exposure to Population Around the Three Mile Island (TMI) Nuclear Power Station.

The DOE assessment of the external whole body radiation exposure to the population around the Three Mile Island (TMI) nuclear power station was based on over 125 measurements of radiation taken on March 28, 1979 through April 3, 1979, in the center of the plume of airborne discharges.

These measurements were taken from helicopters, using Geiger-Mueller survey instruments with probes having open, low density windows, to enable measurements of the gamma radiation exposure, plus any contribution from high energy beta radiation.

The radiation survey probe was held external to the belicepter(s) to minimize attenuation of any radiation.

The measurements were made at various distances out to ten miles frcm the TMI plant.

At each distance, the helicepter(s) were maneuvered to find the maxinum radiation

'asure rate, and this maximum salue was used in the calculation of population dose within any ;ector.

The geographical region within a 50-mile radius of the plant was plotted out in concentric and azimuthal sectors, and the population exposure within each sector was calculated based on (a) the measured radiation dose rates,

\\?1 2'

~

O

A-2 (b) records of thu helicopter location for each measurement, (c) the path of the plume, and the duration of its passage, as well as predictions of its course and speed from current meteorological data, and (d) population figures for each sector projected for the 1980 census.

Also assumed was (e) a factor of two reduction in radiation dose to an individual at ground level due to instrument geometry and (f) that _ members of the population were out of doors during the entire duration of passage of the plume.

Figures A-1 and A-2 show e.-posure profiles for the 0-2 mile and the 0-10 mile radii, respectively, for the average exposure to individuals on the ground.

The exposure rates at distances beyond ten miles from the plant were extrapolated from a curve drawn through the exposure measurements measured as a function of distance within ten miles of the plant.

The cumulative population dose to external radiation within the 50-mile radi s using the above data and assumptions was approximately 1700 person-rem u

ible A-1 provides the contributions 425 person-rem through April 3, 1979 T

to the tutal cumulative population dose 1

-5 of the population sectors.

The maximum estimated dose to any person was t mrem to a hypothetical indi-vidual located three-t aths of a mile east of the station for the entire week following the TMI occurrence.

The average estimated dose to the 2,165,651 persons within the area considered would be less than 1 mrem, or abc Jt U; of the yearly i due to natural radiation.

127 224 e

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2, 017 2,675 Figure A-2.

COE 10-mile Exposure Profile (mR) 2-3.il.

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t

e A-3 This assessment overestimates the actual exposure because of the following conservative assumptions:

(a) No reduction of the radiation exposure was made for shielding of individuals during periods they would be inside.

(b) Some of the helicopter flights and radiation dose measurements were made in response to known increases in discharges from the plant.

Therefore, they would be higher than average values.

(c) The maximum doses measured in the plume were applied to the entire sector affected.

Table A-1.

Collective Dose to Population 0-50 miles from Three Mile Island Nuclear Station March 28 through April 3, 1979 Department of Energy Aerial Radiation Survey Radius around Average Estimated Total Total Nuclear Station (miles)

Excosure (mrem)

Pooulation Person-rem 0-1 45 658 29 1-2 38 2,017 77 2-3 27 7,579 208 3-4 18 9,676 175 4-5 15 8,891 133 5-10 5.7 137,474 781 10-20 0.45*

577,288 258 20-30 0.033*

433,001 14 30-40 0.0023*

273,857 0.6 40-50 0.00015*

713,210 0.1 TOTAL 0.77 2,165,651 1,677 425

• Extrapolated doses (see text)

NOTE:

Estimated maximum exposure to a hypothetical person, 0.5 mile east of plant, remaining under the plume for 43 hours4.976852e-4 days <br />0.0119 hours <br />7.109788e-5 weeks <br />1.63615e-5 months <br />, is 95 25 mrem.

127 227 4

e

APPENDIX 8

)

DOE Environmental Deposition Measurements in the Area Surrounding the Three Mile Island Nuclear Power Station Following the accident at the Three Mile Island Nuclear Stations, the DOE established the following environmental monitoring activities starting as of 4:00 p.m. on March 28, at the request of the Commonwealth of Pennsylvania, in accordance witht the DOE Radiological Emergency Assistance Program:

(a)

Helicopter surveys to locate and measure gamma and beta radiation in the airborne discharges.

(b) Ground vehicle radiation curveys in the path of airborne discharges, including some in-situ radionuclide identification by gamma spectrum analysis.

(c)

Collection of environmental soil, grass, surface water, and air samples in the path taken by airborne discharges.

(d) Gamma spectrum analyses of these environmental samples to detect, identify and quantify any radionuclides present.

127 228 e

e

B-2 (e)

Evaluation and interpretation of survey and analytical data to estimate

. population exposure.

s 00E established three field laboratories for analyzing samples of soil, surface water, grass, and air for gamma-emitting radionuclides.

These labora-tories were located at the Capito.1 City Airport.

Each utilized a sensitive, high efficiency lithium drifted germanium detector and multi-channel gamra spectrum analyzer.

One set of each was brought in and manned by radiochemists from the Brookhaven National Laboratory, Bettis Atomic Power Laboratory, and Knolls Atomic Power Laboratory.

Environmental samples were collected by crews from these laboratories, with specific attention to locations near the plant, and to areas over which the plume of discharges from the plant had persisted, and was known to have touched down.

Attention was also given to assuring that the sampling method would establish if any radioactivity from the plume had been deposited on the ground.

The soil, grass and water specimens were skimmed from the largest surface areas practicable to fill Marinelli geometry containers in order to optimize the sensitivity of the analyses, and thereby increase the likelihood of detection.

The air samples were taken both by Silver treated silica gel samplers flown into the pluma to ensure capture of any non-ionic radiciodine present.

Charcoal filters were used in ground sampling larger volumes of air in the plume.

The total number of samples collected and analyzed starting on March 2.9 has been in excess of 800.

The detection sensitivity achieved (minimun 127 2129

B-3 d

detectable activity (MDA)) for iodine-131 was at least one nCi/m for roil

-11 and grass, 1 x 10" pCi/ml for water, and 7 x 10 Ci/ml for air.

Even lower MDA's were achieved on many samples by longer counting periods, by further idealizing of geometry, and when background radiation was lower.

These measures 2

2 enabled sensitivities as low as 0.3 nCi/m for soil, 0.02 nCi/m for grass,

-8

-12 4.0 x 10 Ci/ml for water, and'2.7 x 10 Ci/ml for air.

The gamma spectrum measured for each sample was examined in its entirety to detect any photopeaks.

The detection sensitivity of this equipment was sufficient to reveal any uranium in the air in the range of allowable occupational concentrations, if any had been present.

The analyses of these environmental samples revealed the presence of iodine-131 in only a few air and grass samples, at barely over the detection limit, when the greater sensitivities were achieved.

In a few soil samples, cesium-137 radioactivity was detected as expected at levels normally found due to world-wide fallout from previous atmospheric testing.

The Silver treated si'.

gel air samplers which had been flown through the plume, and the charcoal a.r sample filters used for the high volume ground level samples in the path of the plume, were returned to Brookhaven National Laboratory for further analysis to detect the presence of beta, or alpha emitters by other techniques.

However, such species are considered entirely unlikely since the properties of the chemical species in which such radio-nuclides exist are knowr. to promote retention within the reactor fuel and/or 127 230 a

B-4 coolant.

Containment air samples analyzed on March 30 did not reveal the presence of any such nuclides.

Direct in-situ measurements of radioactivi+> on the ground were also made by the DOE Environmental Monitoring Laboratory (EML) using two large volume, pressurized ionization chambers,'and a very sensitive, high efficiency Lithium drifted Germanium detector gamma spectrometer.

These systems enable detection of variations in radiation levels from natural or man-made radioactivity of a fraction of a microroentgen per hour.

These vehicle mounted systems were deliberately moved to locations where those few environmental grass samples were taken which, when analyzed in the laboratory indicated iodine-131 at concentrations just above the MDA.

These EML measurements confirmed both the concentrations measured in the laboratory, and the Identification of the specific radionuclide iodine-131.

Other measurements by the EML systems also confirmed the generally negative results found in the laboratory analyses of the environmental soil, water and grass samples.

The date, time and specific location of all of the environmental samples, as well as the results of the laboratory analyses are recorded in the Technical Work Record books of the DOE team.

The results of these analyses of the environmental samples, as well as gamma spectrum analyses of the plume raade by the EML mobile system, support the conclusion that the predominant radionuclide in the airborne discharges 127 231 4

~

B-5 was the inert gas xenon-133, with a small amount of iodine-131 also present.

This conclusion is supported by information received from the NRC licensee (Metropolitan Edison) ccncerning the measured soaposition of stack discharges, and the analyses of the air radioactivity in the containment.

4 e

T 127 232 e

e 4