ML19331D444

Final Environ Assessment for Decontamination of TMI Unit 2 Reactor Bldg Atmosphere, Vol 1 of Final NRC Staff Report

ML19331D444
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Site:	Crane
Issue date:	05/31/1980
From:	Office of Nuclear Reactor Regulation
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References
NUREG-0662, NUREG-662, NUREG-CR-1662, NUREG-CR-1662-V01, NUREG-CR-1662-V1, NUDOCS 8009020493
Download: ML19331D444 (96)

Text

NU REG-0662 Vol.l Final Environmental Assessment for Decontamination of the

Three Mile Island Unit 2 l Reactor Building Atmosphere Final NRC Staff Report l

atsIu"sh ay TMI Support Staff l

Office of Nuclear Reactor Regulation l

U.S. Nuclear Regulatory Commission Weshington, D.C. 20556 r

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TABLE OF CONTENTS Pa21 i

l Preface..

v 1.

Summary and Recommendation...

1-1 l

2.

Proposed Action.......

2-1 3-1 3.

Introduction....

f 4.

Reactor Building and Airborne Activity.

4-1 4

4-1 4.1 Gas Sampling and Analysis....

4-1 4.2 Source Term Derivation..

2 i

5.

Need for Decontamination.......

5-1 6-1 6.

Decontamination Alternatives...

6-1 1

6.1 No Action...

1 6.2 Reactor Building Purge System..

6-1 6.2.2 Slow Purge....

6-1 6-6 i

6.2.3 Fast Purge..

6-8 6.2.4 Elevated Release Points.

I Extending Stack Hwight to 400 Feet..

6-8 6-9 Constructing a 1000-Foot Stack..

6.2.5 Staff Evaluation of Union of Concerned Scientist Elevated Release Proposals..

I

'l

,I Hot Plume Release Through a 250-Foot Stack..

6-9

[

The Tethered Balloon / Tube Release at 2000 Feet..

6-10 6-l' 6.3 Selective Absorption Process System.

6.4 C5arcoal Adsorption Process System..

6'/

6.5 Gas Compression System.

6 22

( 24 6.6 Cryogenic Processing System.

2-30 6.7 Combination Process and Purge Systems....

6-31 6.8 Onsite Long-Term Storage of Kr-85...

l 6.9 Transportation and Offsite Disposal...

6-33 l

7.

Health Ef'fects...

7-1 7-1 7.1 Physical....

7-8

7. 2 Psychological Stress.

8.

Radiological Environmental Monitoring Program..

8-1 9-1 l

9.

Fesponse to Comments 10.

Piblic Information Activities.

10-1 11-1 11.

References a

12-1

12. Glissary 1

i s

111 1

l

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1-1 1.0 Summary and Recommendation The NRC staff has prepared this summary of the Final Environmental Assessment for those who prefer to follow the main themes of the assessment without referring to the technical descriptions, calculations, and other data that provide the foundation upon which the staff's recommendation is based.

The krypton-85 (Kr-85) released into the reactor building during the accident on March 28, 1979, must be removed from the building so that workers can begin the tasks necessary to clean the building, maintain instru-ments and equipment, and eventually remove the damaged fuel from the reactor core. Those tasks must be performeo whether or not the plant ever again produces electricity. Radiation from the krypton gas, although thinly dispersed through the reactor building atmosphere, nevertheless poses a threat to workers who would have to work in the building for prolonged periods.

This Final Environmental Assessment (NUREG-0662) presents a discussion of the information considered by the hRC staff in arriving at its recommendation that the preferred method for removing the krypton-85 from the reactor building is by a kind of flushing process by which the gases would be pushed out of the building and fresh air pulled in.

The Metropolitan Edison Company (the licensee) on November 13, 1979, asked the NRC staff fcr permission to purge or remove the reactor building atmosphere containing the krypton-85 to the outside (Ref.1). In March 1930, the NRC staff published the draf t version of this Environmental Assessment (NUREG-0662) and two subsequent A,ddenda for public comment (Ref. 2).

The staff has received approximately 800 conents on the draft Environmental Assessment. Of these, approximately 195 responses generally supported the purging of the reactor building, approximately 500 opposed it, and the remaining responses were either recommended alternatives for removing the krypton or comments that took no position on the staff's recommendatio-Substantive comments received by the NRC s.taff will be printed in Volume 2 of this Assessment.

From this process have emerged some NRC staff conclusions on four basic aspects of dealing with the reactor building atmosphere:

---The potential ohysical health impact on the public of using any of the pro,iosed strategies for getting rid of t'le krypton-85 is negligible.

---The potential psychological impact is likely to grow the longer it takes to reach a decision, get started, and complete the process.

---The purging method is the quickest and the safest for the workers os Three Mile Island to accomplish.

---Overall, no significant environmental impact would result from use of any of the alternatives discussed in this Assessment.

The problem As will be developed in the following discussion, decontamination of the reactor building atmosphere at this time is a necessary activity irrespective of whether subsequent cleanup operations are authorized or of the nature of such operations. There presently exists a need for relatively prolonged access to the reactor building for purposes of maintenance of equipment essential for continuation of the safe shutdown mode and for data gathering activities so that the nature and extent of future cleanup measures can be determined. In

1-2 addition, it is believed that the prompt initiation of decontamination will be beneficial from the standpoint of alleviating some of the psychological stress now being experienced by the nearby public.

Furthermore, authorization of any of the alternative methods for decontaminating the reactor building atmosphere, being an action independent of any subsequent cleanup activities, does not foreclose, nor predetermine, the consideration or selection of any alternative to such subsequent measure.

Taking the foregoing into consideration, the staff believes that it is in the best interest of the public health and safety to authorize this activity at this time, prior to issuance of the Programmatic Environmental Impact Statement, now in preparation.

The March 28, 1979 accident in Three Mile Island Unit 2 heavily damaged the uranium fuel in the core of the j

reactor. Many radioactive substances that normally remain trapped in the fuel rods were released when the fuel rods were themselves broken. Some of the radioactivity, in the form of gases, leaked out of the reactor system, along with a large amount of water. Some of the gaus escaped to the environment and some of the water reached other parts of the plant be bre being captured. A great deal of water and a substantial amount of radioactive gases remained confined in the reactor building.

As long as the damaged fuel in the reactor core is cooled and remains relatively undisturbed and surrounded by baron, there is essentially no chance that the fuel chain reaction, which was abruptly stopped by the accident, could start again. But as time passes, the NRC staff believes that there will be an increasing chance of essential equipment wearing out or malfunctioning. If the core were accidentally to begin to undergo a chain reaction once more, it could cause releases of more radioactivity within the reactor building. Therefore, I

removal of the damaged fuel for safe storage is the paramount objective of the cleanup of TMI-2.

Shortly after the accident, the radioactive gases xenon and iodine accounted for most of the radioactivity in the reactor building atmosphere. But because these gases decayed to nonradioattive forms rapidly, they now account for only about one millionth of the radioactivity in the building air. Nearly all of the radoactivity now in that air comes f rom the relatively longer-lived krypton. Traces of a radioactive form of hydrogen, called tritium, are in the building atmosphere at levels 10,000 times lower than the krypton. Most of the radiation given off by krypton-85 in the reactor building is a kind that can be blocked by heavy layers of clothing (which could also severely hamper workers). However, it is not this " beta" radiation that is of primary concern for worker health. The primary concern is with the more penetrating gamma radiation. Since l

krypton-85 contributes significantly to the gamma dose within the reactor building (it accounts for as much as l

75% of the total in some areas of the building), removal of the krypton is necessary. Even with the krypton-85 re cved, there would still be radiation from the damaged reactor core, from radioactive material deposited on l'

si rface, and from the more than seven feet of contaminated water in the basement of the building. But, the radiation dose rate for workers would be cut from about 2.3 rem per tour to 1.6 rem per hour at the 305-foot level in the building, and from about 1.3 to 0.3 at the 347-foot level if the krypton-85 were removed from the building.

At the present time, the reactor building is sufficiently air-tight so that steady cooling of the air in the building has kept its pressure at slightly below outside air pressure. Whatever small air leakage there has been has come in from the outside, rather than to the outside. However, the cooling system fans, designed to run continuously for only a few hours, have been running for more than i year, and they may fail over a period l

of time.

If they do, a rise in pressure inside the reactor building would lead to small putfs of uncontrolled l

1sakage of the building atmosphere to the outside. This would not pose a health hazard to the public but l

would be of major concern and could contribute to anxiety among residents in the area., Controlled and monitored removal of the building atmosphere before the cooling fans fail would avert that possibility.

I I

L

1-3 The Proposed Solution In performing its Environmental Assessment of Metropolitan Ediso#s proposal to purge the reactor building atmosphere, the NRC staff has not only evaluated that plan Out also has evaluated several alternatives, including the following:

1.

No action, j

2.

Purging (Slow or Fast, Lower or Higher Release Points).

3.

Selective Absorption Process.

I 4.

Charcoal Adsorption, Including a Refrigerated Adsorber System.

5.

Gas Compression and storage.

6.

Cryogenic Processing (Liquifying the Gas and Storing for Later Disposal) 7.

A Combination of Purging and the Other Alternatives.

1.

No Action Leaving the contaminated air in the reactor building indefinitely would leave one important phase of the cleanup process undone. It would also carry other risks. First, it would be physically more difficult, if not impractical, for workers to do any significant cleanup work in the building because of the heavy protessive clothing and air-supply equipment they would be required to wear. Under these conditions, workers may be r

limited to only 15-30 minutes in the building before air supplies must be replaced. Dose considerations would also limit the " stay time" of workers in the building. Second, to the extent that it would interfere with maintainance of already over used equipment in the building, indefinite delay might cause failure of equipment essential to keeping the damaged reactor core in a safe condition. Third, the building could begin to leak i

unexpectedly. Although the leakage is not considered a significant threat to the health t.nd safety of the l

public, it could generate the same anxiety and stress that similar minor leakage incidents at the plant have i

generated in the past.

2.

Purging The TMI-2 reactor building has two separate systems that can be used to move air from the inside of the building to the outside by way of filtering and monitoring equipment leading to a ventilation stack that reaches 160 feet in the air. The smaller of the two systems was designed as a backup system to the hydrogen recombiner system to reduce hydrogen concentrations in the building following a loss-of-coolant accident so as to prevent possible gas explosions. This hydrogen control subsystem, when modified, would employ a fan with the capacity to move up to 1,000 cubic feet of air per minute. This fan would be started slowly and run at low rates until the krypton-85 concentrations in the building had been lowered by dilution with fresh air so that larger volumes could be sent outside without raising the concentrations of radioactivity around the site. If this system of fans and ducts was used by itself, it would take about 30 days of actual purging, spread over about a 60-day period, to complete the purging operation. The larger of the reactor building purge systems is the building's venti-l 1ation system. If this larger system were used along wth the hydrogen control subsystem, both systems could remove the required amount of air in about five days of actual purging, during good weather, over a 14-day period. Both the hydrogen control subsystem and the reactor building purge systems are equipped with control valves and their I

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1-4 cwn trains of filters so that fine particulate radioactive material would be removed from the :fr before it is discharged to the outside through the ventilation stack. Just before reaching the stack, the air from the reactor building would be mixed with air from other plant buildings to provide some dilution before it is discharged from the stack. As the air bearing the krypton-85 is pelled out of the reactor building, fresh air from the outside would enter the building through an open valve.

The staff also examined the possibility of extending the 160-foot high stack to 400 feet with piping supported by scaffolding or guy wires. The staff believes that under the best of weather conditions elevating the stack could reduce the maximum possible exposures closest to the site to as little as 1/8th the dose predicted to occur for the 160-foot stack. The staff has estimated that designing, construction, and leak testing the added stack section would delay cleanup of TMI-2 by about four to five months.

The staff next considered construction of a r.aw 1000-foot stack to provide additional altitude for releasing the reactor building air. The staff estimated that it wculd take at least 11 months to design, build, and test such a stack to adequate safety criteria. They also felt that while the higher stack would reduce the public's radiation exposure, the projected exposure was already so low as to pose no radiological health hazards and that the minimum of an 11-month delay to build a stack of 1000 feet could not be justified.

Finally, the staff evaluated two proposals submitted by the Union of Concerned Scientists to Governor Thornburgh (Ref. 3).

The first proposal was that the reactor building air be heated to give it more buoyancy upon its release from the stack for more effective rise and dispersal.

The NRC staff believes that although heating of the discharge would reduce the public's radiation exposure somewhat, the UCS has underestimated the time it would take to put such an incinerator-heating system into operation, and that instead of the seven to nine months predicted by the UCS, it would take a minimum of 9 months. (The UCS estimated construction time only, excluding design, engineering, procurement, and testing of the incinerator scheme.) The staff said the expected dose reduction of a factor of about 30 to an individual and the delay do not justify the impac't of delaying the cleanup operation.

The second proposal was that a 2000-foot tube of reinforced f abric, held alof t by a tethered balloon, be used as a stack for discharge of the teactor building air. Because the method is unique and untried, the staff said there was some uncertainty as to how long it would take to implement, but the staff thought it could work. The staff thought it would take 7 to 10 months to design, build, and test such a system. However, the staff felt that the psychological impact of a balloon clearly visible over the site may offset any advantage which might be gained by a reduction of the dose to any individual.

3.

Selective Absorption The selective absorption process would withdraw all the air in the reactor building, separate from it essentially all the krypton, and return the decontaminated air to the reactor building. The contaminated air would pass through a column in which liquid Freon would absorb the krypton while allowing the other gases to pass through unchanged. Once separated, the krypton could be stored for approximately 100 years under either high pressure in a few gas cylinders, or under low pressure in a larger number of cylinders.

l The Union Carbide Company of Oak Ridge, Tennessee, has been developing 3 selective absorption process since 1967. Their latest small-scale pilot plant, in operation since 1978, can remove 99.9% of the krypton passed through it. Union Carbide of ficials are optimistic that a larger version of this pilot plant (scaled up at i

least 10 times) can work at Three Mile Island. Estimated times for completing this larger version vary. Oak Ridge personnel estimate that a system could be put in service at TMI in 10 months. To construct the system j

j in this period would require a crash program that would use standard industrial design criteria, off-the-shelf i

i

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1-5 i

components, and no competitive bidding. This estimate does not consider the need for a suitable building at the TMI sf*e and is based on other questionable assumptions.

I In the best judgment of NRC construction experts, the shortest possible time to design, procure, construct and l

test a suitable selective absorbtion system is 16 months. This time period is considered by the staff to be l

an undesirable delay in getting the cleanup of the reactor building initiated It is relevant to note that the Oak Ridge Naticnal Laboratory, the organizaton most know?edgable abcut the selective absorption system, has recommended against using that system and favors coMrolled purging to dispose of the krypton gas.

4.

Charcoal Adsorption I

4 Charcoal adsorption is a process by which the contaminated air from the reactor building would be piped into large tanks containing charcoal. The krypton would adhere to the surface of the charcoal after coming in 1

contact with it.

The charcoal from this process would then be isolated and stored, The MtC staf f evaluated both normal temperature and refrigerated charcoal adsorber systems. Both systems f

require large quantities of charcoal; the first 34,000 tons and the second 12,000 tons. During normal operation, no releases of radioactivity would be expected. Since noble gases do not react chemically with charcoal, but just stick to its surface, long-term surveillance would be required during storage. The krypton-bearing charcoal would have to be stored (and watched over) for up tc 100 years to allow the radioactivity to decay to insignificant levels.

4 i

l The staff's major concern was the environmental impact of long-term onsite storage, and the long delay caused I

by construction of the charcoal system. Construction and testing of a charcoal system would delay by from two to four years the containment atmosphere cleanup. The staff considers this to be an intolerable delay in the j

overall cleanup effort.

5.

Gas Compression i

1 l

Gas compression is a process by which the air containing the krypton gas in the reactor building would be drawn off into pressurized storage containers. These pressurized containers would then be stored in sealed I

sections of piping. For example, at a pressure of 300 pounds per square inch, about one million cubic feet of pipe, 36 inches in diameter would be required. This corresponds to about 28 miles of piping. The advantages of this process are that it would expose the general population to less radioactivity than purging the krypton and gas compression and is a known technology. The disadvantages are that two to four years would be required to put the system into operation, the krypton gas would have to be maintained under pressure in storage in many pressurized containers for approximately 100 years, and the krypton could leak at some time during storage.

The staff has concluded that this alternative is impractical.

6.

Cryogenic processing j

Cryogenic processing is the condensation of kryptoa-85 from the incoming air by bringirg it into direct contact I

with liquid nitrogen (-320*F).

The liquified krypton-85 is collected, restored to a gas form, and stored to I

allow decay. An alternative to storing would be to transport the containers of the separated krypton (whether l

from the cryogenic or selective absorption systems) to a burial ground or to a remote area and release the krypton gas to the environment.

f 1

j The NRC has looked at several cryogenic systems available from commercial nuclear power plants. None of these l

systems has been operated successfully. Although these new systems could be purchased, a new buildina would i

I

1-6 be required to house the systee and contain any possible leakage. The cryogenic system would be connnected to the piping of the existing hydrogen control system. The air from the reactor building would be passed through the filters and charcoal adsorber of the hydrogen control system and then piped to the cryogenic processing system in the adjacent building. At least'20 months are estimated to be required to obtain a fully operational cryogenic systen at the TMI site. This estimate is based on NRC staff assessments and consultations with construction engineers at Oak Ridge National Laboratory.

During the approximately 2- -month period required to process the reactor bullidng atmosphere, about 60 curies of krypton-85 would be released to the environment with the purified effluent from the system. Also, some leakage from the systee is anticipated, but the staff believes this can be minimized by judicious monitoring and a rapid system shutdown if trouble develops. However, based on ilmited experience with these systems, operation and maintenance are likely to result in a relatively high occupational dose. Designs have been proposed to store the radioactive krypton on the site while it decays. This will require surveillance for 100 years and represents a continuing risk to workers at the site, as well as a potential source of anxiety to the public. Alternatively, burial or release of the contaminated krypton at a remote site could be accomplished.

However, the NRC staff believes that release in a remote area probably would not be acceptable to local officials and residents.

7.

Combined Processes The staff evaluated combinations of various alternatives, using one of the krypton extraction and recovery systems, such as charcoal adsorption, gas compression, cryogenic, or selective absorption for most of the krypton, and purging the rest to the environment. One of the krypton recovery systems would trap about 95% of the krypton (54,000 curies) and the other 5% (3,000 curies) could be released to the environment. The size of the processing system or the size of the storage facility for the final saterial holding the krypton would be only about 25% to 33% of what would be needed if there were no purging used at all. Of all the combinations considered by the staff, those using smaller size cryogenic processing or selective absorption could be built the fastest but even so would take at least one year to be operational. Additional time would then be required to complete the processing and final purging. The staff still considers this an unacceptable delay in the overall decontamination of the reactor building atmosphere.

Onsite Long-Ters Stor y of Krypton-85 With the exception of direct controlled purging of the reactor building to the outside, all the proposed processes leave the radioactive krypton to be stored onsite, in some form, for about a century. If a leak were detected in an above ground storage facility at the site, actions could be taken to terminate the leak by transferring tne contents of the leM ing container to a new one.

The staff believes that more study is needed in the selection of materials for such storage containers, and in their fabrication, because of the possibility that containers may corrode over the projected 100 years it will take the krypton radioactivity to decay away.

Transportation and Offsite Disposal M ternatively, the krypton gas would be appropriately packaged and tr.

'ted to a waste burial facility for burial cr taken to a remote location, such as a desert, and released to -he environment. The hRC staff estimates that the impact of handling, packaging, transportation and burial or remote release of the kr-85 would be 8-24 person-ree (total body).

1-7 Public Health and Environmental Effects Physical Effects The NRC staf f has determined that there are neg' gible physical public health risks associated with the use of any of the alternatives (excepting the "no action" alternative). For the venting alternative in particular, in independent analyses, the National Council on Radiation Protection and Measurements, the U.S. Environmental Protection Agency, the U.S Department of Health, Education, and Welfare, and the Union of Concerned Scientists have reached the same conclusion. Additionally it should be noted that, based on the relatively greater radiosensitivity of humans, purging would have no adverse impact on plants or animals.

An estimate of the total number of fatal cancers, resulting from purging and the other siternatives, has been made by the NRC staff. The total potential cancer deaths for both the 50-mile population surrounding TMI-2 and plant workers is estimated to range from a minimum of 0.0003 (purge option) to a maximum of 0.034 (cryogenic option). Almost all of this small risk would be borne by workers exposed at the plant (purge = 0.0002, cryogenic = 0.034).

The total fatal cancer risk among all people within 50 miles of TMI from purging would be about 0.0001. This corresponds to an average risk of 0.000000000045 to each of 2,200,000 individuals living within 50 miles of the plant, i.e., about 5 chances in 100 billion.

The total risk of some type of genetic abnormality, resulting from the decontamination alternatives, to the public within 50 miles and plant workers has also been estimated. This genetic risk has been estimated to range from a minimum of 0.0005 effects (purge option) to a maximum of 0.066 effects (cryogenic option).

Again, almost all the risk would be borne by workers (and their descendants) at the plant (purge 0.0003 effects; cryogenic 0.066 effects. The maximum genetic risk to any offsite member of the public from the various options would be 5 chances in 100 million (0.000000005), compared to the current expectation of all kinds of normally occuring genetic effects of one million to five million in 100 million (0.01 to 0.05).

Finally, the NRC staf f has estimated risks associated with development of skin cancer. As a result of purging, a skin dose of 11 ares (see Table 1.1) to the maximum exposed individual, is estimated to result in a risk of death of about one chance in a billion (0.000000001). A population skin dose of 63 person-res (purge option) would be estimated to cause considerably less than one (about 0.000006) additional skin cancer deaths among the 50-mile population of 2.2 million people. This compartd with about 4,000 deaths from skin cancer (from other causes, primarily sunlight), which would normally be expected in the 50-mile population (assuming 75 years life expectancy) around TMI. Other risk comparisons are provided in Tables 7.2 and 7.3.

Psychological Stress The various alternatives for decontamination of the TMi-2 reactor building atmosphere are expected by the NRC l

staff to have different psychological impacts.

l The NRC staff, with the assistance of consulting psychologists from the Human Design Group, has compared these to what already has been found by some studies of the psychological stress effects of the TMI accident.

Previous research suggests that an event line the accident at TMI-2 produces two types of stress: short and I

i continuing. Short-ters effects or those directly related to the occurrence of the incident are reported to be

[

fntense but short-lived. Some researchers have reported that while stress-related indicators were high shortly af ter the accident, they had dissipated by mid-summer of 1979. Their findings suggest that stress changes with time, and that long-term mental health implications may be less than previously thought.

I

1-8 Based on consultations with psychologists, the staff has concluded that the purging alternative, which can be implemented promptly, has less potential for creating long-term psychological stress than those alternativet which take longer to complete. Furthermore, since a prompt decision on, and completion of, purging will be the first major step toward eventual cleanup of the reactor building and decontamination of the site, it is anticipated that a majority of the public will perceive this action as leading to elimination of future risks from TMI-2. The NRC staff, based on advice received from its consulting psychologists, believes that this public perception will reduce the stress and anxiety of the public.

~

Radiological Environmenta1 Monitoring Program The radiological environmental monitoring around the TMI site and nearby comunities during decontamination of the reactor building atmosphere would be performed by (1) the U.S. Environmental Protection Agency, (2) the Commonwealth of Pennsylvania, (3) the U.S. Department of Energy, (4) the Nuclear Regulatory Commission, and (5) Metropolitan Edison Company (the licensee),

The EPA is the lead agency for the Federal government in monitoring the area surrounding Three Mile Island.

EPA operates a network of eighteen air monitoring stations ranging from one-half to seven miles from TMI. EPA will also use a number of mobile radiation monitoring vehicles positioned in the predicted downwind trajectory during purging. EPA will issue daily reports of their measurements to the public during the purging of krypton.

In addition to their own direct monitoring, the Department of Energy and Comonwealth of Pennsylvania are sponsoring a Comunity Radiation Monitoring Program that involve people from 12 communities in an approximate 5-mile circle around TMI.

About 50 individuals have completed training classes conducted by the Nuclear Engineering Department of Pennsyl-vania State University. The classes involved classroom instructions, laboratory training, and actual radiation monitoring in the field. The teams will use EPA gama-rate recording devices, which are currently in place around THI, and which will be supplemented by gama/ beta sensitive devices being furnished by DOE through EG&G Idaho, Inc.

The training sessions were designed to provide a working knowledge of radiation, its effects, and detection techniques, and included hands-on experience with monitoring equipment in the field. Citizens will be expected to demonstrate minimal competence in radiation monitoring Defore actual monitoring efforts begin. Following j

the completion of training, team representatives in each of 12 selected areas have been gathering and reporting data from the gamma and gamma / beta-sensitive instruments on a routine basis.

Response to Comments The draf t " Environmental Assessment for recontamination of the Three Mile Island Unit 2 Reactor Building Atmosphere" (NUREG-0662) and two sub, sent addenda were issued for public coments late in March 1980. The

{

public coment period en,ed May 16. Approximately 800 responses have teen received, each of which fell into one of three categories- (1) those supporting the purging alternative recommended by the NRC staff (approxi-mately 195 responses), (2) those opposed to the purging alternative (approximately 500 responses), and (3)

[

f those who recommend decontamination alternatives other than those discussed in the Environmental Assessment or who otherwise commented on the assessment (approximately 105 responses). Section 9 of this report provides the NRC staff's response to these coments.

Copies of correspondence received ase available for inspection and copying for a fee at the NRC Public Document Room at 1717 H Street, NW, Washington, D.C.10555, and at the NRC Local Public Document Rooms, State Library 1

j-i

1-9 of Pennsylvania, Government Publications Section, Education Building, Commonwealth and Walnut Street, Harrisburg, PA 17126, and York College of Pennsylvania, Country Club Road, York Pennsylvania 17405. All substantive comments received will be published in Volume 2 of this final assessment.

Public Information Activities In an effort to better inform the public in the area around Three Mile Island about the contents of the draft Environmental Assessment (NUREG-0662, and Addenda 1 and 2), NRC has conducted a series of 38 informational meetings and activities. The staff also issued an easy-to understand report that answers frequently asked questions about removing the krypton from the reactor building. Copies of the report, " Answers to Questions about Removing Krypton from the Three Mile Island Unit 2 Reactor Building" (NUREG-0673), are available free of charg* by writing to the Division of Technical Information and Document Control, U.S. Nuclear Regulatory Commi sion, Washington, D.C.

20555.

Most of the meetings held were planned by the NRC, although some were organized by other interested groups, at which NRC officials were invited participants. Members of the U.S. Environmental Protection Agency and the Pennsylvania Department of Environmental Resources (DER) were usually invited participants at these seetings.

EPA officials outlined their agency's program and responsibilities for environmental monitoring in the vicinity of the TMI site, while State DER personnel explained the comunity monitoring program and other state functions related to the clean up of TMI Unit 2.

At these meetings, NRC officials expressed their willingness to meet with other groups of people who had an interest in receiving additional information on the Environmental Assessment or clean up operations at Unit 2.

Table 1.1.

Environmental Impacts of Alternatives for Removina the Kryston-85 from the Reactor-Building Atmosphere Total Offsite Dose to Maximum Exposed Individual

• Method Normal Processing Accidents Occupational Exposures Reacter Building Beta skin dose -

Beta skin dose - 25 mres 1.2 person-ree Slow Purge 11 mres Total bc'v gamma dose - 0.3 mrem Total body gamma dose -

0.2 mrem Reactor Building Same as above Same as above Same as above Fast Purge Elevated (400 ft.)

Approximately 1/8 (0.13)

Same as above Same as above Purge of Slow Purge above Elevated (1000 ft.)

Approximately 1/230 (0.004)

Same as above Same as above Purge of Slow Purge above Hot Plume (250 ft.)

Approximately 1/30 (0.003)

Same as above Same as above T*

Purge of Slow Purge above 5

Balloon / Tube (2000 ft.)

Approximately 1/300 (0.003)

Same as above Same as abcve Purge of Slow Purge above Selective Absorption Less than Cryogenic Absorption Process 115-220 person-res Process System Processing System Beta skin dose - 6 mrem Total body gamma dose - 0.1 mrem Gas Storage Beta skin dose - 1700 mres Total body gamma dose - 20 mren Charcoal Adsorption less than Cryogenic Ambient Charcoal System 47 person-rem Systems Processing System Bela skin dose - 41 mrem Total body gamma dose - 0.5 mrem Refrigerated Charcoal System Beta skin dose - 174 mree Total body gamma dose - 1.5 mres

O t

Table 1.1 (Continued)

Total Offsite Dose to Maximum Exposed Individual

• Method Normal Processina Accidents Occupational Exposures Gas Comoression Less than Cryogenic Beta skin dose - 410 mrea 41 person-ree System Processing System Total body gamma dose - 5 mrem Cryogenic Processing Beta skin dose -

Beta skin dose - 1700 ares 157-255 person-rem System 0.01 aren Total body gamma dose - 20 mrem Total Body Gamma dose -

less than 0.0002 mrem Ccobination Process /

Approximately 1/95 (0.01)

Beta skin dose - 1700 mrem 115-255 person-rem Purge of Slow Purge above Total body gamma dose - 20 mrem No Action Beta skin dose - 0.01 area (The potential offsite and occupational Total body gamma dose -

dose from the extremely large inventory less than 0.0002 mrem of radioactive material within the reactor building cannot be reliably estimated for long periods of containment, but is potentially high and could exceed other y

alternatives considered.)

f:

"The collect *s 50 mile offsite population doses resulting from the purging alternat?ves are estimated to be 0.76 and c3 person rem for total-body and skin doses respectively. Although elevating the release point would reduce these population dose estimates, the reduction would probably be no greater than 10%.

4 l

2-1 2.0 Proposed Action The action proposed is to purge from the reactor building at Three Mile Island, Unit 2, the krypton-85 released from the damaged fuel as a result of the accident on March 28, 1979. This NRC staff Final Environmental Assessment responds to a proposal submitted by Metropolitan Edison Company (the licensee) for purging the reactor building atmosphere through the building's existing hydrogen control subsystem (Ref. 1).

This Assessment does not address decontamination of reactor building equipment, interior walls and surfaces, and treatment and disposition of water in the reactor building sump or in the reactor coolant system. These issues will be addressed in a Programmatic Environmental Impact Statement to be issued by the NRC staff later in 1980.

3-1 3.0 Introduction As a result of the March 28, 1979 accident at the TMI Unit 2 facility, significant quantities of radioactive fission products and particulates were released into the enclosed reactor building atmosphere beca;se of sub-stantial fuel failure in the reactor core. At the present time, the dominant radionuclide remaining in the reactor building atmosphere is krypton-85 (Kr-85), which has a 10.7 year half-life. Based on periodic sampling of the reactor building atmosphere Since the accident, the concentration of the Kr-85 in the building is about 1.0 pC1/cc, yielding a total inventary of approximately 57,000 curies. Reactor building atmosphere sampling and analysis are discussed in detail in Section 4.0.

At the present time the reactor is safely shut down, and is being maintained that way with the damaged fuel in the reactor vessel. Reactor building air-cooling equipment is maintaining the building at a slightly negative pressure (approximately -0.7 psig) with respect to the outside atmosphere. This pressure differential ensures essentially no leakage of the reactor building atmosphere to the environment. However, before the facility can be considered to pose no threat to public health and safety, the damaged fuel must be removed from the reactor vessel and building, placed in containers if necessary, and safely stored. The radiation levels in the reactor building are currently such that occupancy is severely restricted. Less restricted access to the reactor building is required to facilitate the gathering of data needed for planning the building decontamina-tion program, and for the subsequent work required to accomplish decontamination and other cleanup operations.

Less restricted occupancy will require that the building atmosphere De decontaminated to protect workers from exposure to the beta and gamma radiation associated with the Kr-85 in the reactor building atmosphere.

On November 13, 1979, the licensee submitted a request to the NRC staff for authorization to decontaminate the reactor building atmosphere by controlled purging (feed and bleed) through the reactor building hydrogen control subsystem (Ref. 1).

In a letter to the licensee on December 18, 1979, the staff withheld approval of the request to purge the building and stated that the NRC would prepare an Environmental Assessment on the subject in early 1980 (Ref. 4).

The staff reviewed the licensee's submittal, including the discussion of various alternatives to reactor building purging. As a result cf that review, the staff requested additional information in the form of 33 questions on December 18, 1979 (Ref. 5). The licensee responded to the staff's request on January 4,1980 (Ref. 6). Pursuant to the requirements set forth in the Comission policy statement of November 21, 1979 (Ref. 7) and the February 11, 1980 Order by the Director of the Office of Nuclear Reactor Regulation (Ref. 8), the NRC staff prepared a draft Environmental Assessment (NUREG-0662) in March 1980 (Ref. 2).

That assessment included the staff's evaluation of licensee modifications to the reactor building hydrogen control subsystem, as well as a discussion of the need to decontaminate the reactor building a,nosphere and alternatives to controlled purging to the environment. The original coment period for NUREG43662 was scheduled to end April 17, 1980, but was extended by the Comission, at the request of the Governor of Pennsylvania, to May 16, 1980. This Final Environmental Assessment (NUREG-0662) is based on information and public coments received since publication of the draft Assessment and includes an update of the NRC staff's evaluation of reactor building decontamination alternatives, and an evaluation of potential physical and psychological health effects associated with reactor building purging.

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I 4.0 Reactor Buildina Airborne Activity 4.1 Gas Samplina and Analysis fhree types of reactor building air samples are periodically collected to determine the nature of airborne contaminants in the building. Samples are taken for noble gases (including Kr-85), particulate matter, and radiofodine activity. Air samples are taken from two points in the reactor building. The samples are transmitted through two lines running from the dome to the reactor-building air-sample gaseous monitor.

Redundant inlet and discharge valves are provided for the system to prevent a single-active failure of any valve from impairing the function of the system. Samples are analyzed with a gas chromatograph to determine hydrogen content and isotopic composition is determined with a gamma spectrum analyzer. The Kr-85 gas activity in the reactor building atmosphere is determined by gamma spectroscopy techniques. Isotopic identification is made on the basis of the discrete energy levels at which gamma rays are absorbed in a germanium-lithium (GeLi) detector. Particulate activity is determined in the reactor building atmosphere by pumping building air through a filter. Particulate activity is removed from the air by filters, which are then analyzed using gamma spectroscopy. To determine the concentrations of the different types of iodine in the atmosphere, a sample of the reactor building air is pumped through a series of filters. Separation of the different forms of iodine is accomplished based on the relative affinity of each iodine species for a specific filter medium.

Each filter is then analyzed using gamma spectroscopy.

In addition to the routine sampling for noble gases, particulates, and iodine, samples are obtained for tritium, and gross beta analyses. T5e results of the sampling program are presented in the following section, " Source Term Derivation."

4.2 Source Term Derivation Sample results to date indicate that the dominant isotope within the reactor building atmosphere is Kr-85.

Radioactive decay has reduced other radioactive isotopes of xenon and krypton to negligible quantities.

Reactor building gas sample data from May to December 1979 indicate the source term for Kr-85 is 0.78 pCi/cc, with a standard deviation of 10.23 pC1/cc. Since late 1979, reactor building gas-sampling techniques were improved to eliminate small sample line leaks and to allow for direct counting of the samples. With these improved sampling techniques, the source term for Kr-85 is measured to be 1.04 pCi/cc, with a smaller standard deviation of 2 0.03 pCi/cc. This smaller standard deviation indicates improved sampling accuracy. Other noble gases (e.g., Xe-131m, Xe-133m, Xe-133, Xe-135) have decayed to below minimum detectable activity (MDA)

-6 levels of 1 x 10 Cl/cc Radioactive decay has reduced iodine levels in the reactor building to below MDA levels of 1 x 10 pCf/cc.

Particulate levels, primarily those of cesium-137, are less than 1 x 10 pCi/cc. Reactor building air samples have been specifically analyzed for strontium-89/90. Those analyses, plus the results of gross beta analyses,

-10 show that airborne strontium-89/90 levels are small, that is, in the order of 1 x 10 C1/cc. The airborne concentration levels of all the above isotopes are measured to be below the maximum permissible concentration (MPC) levels listed in Table 1 of Appendix B to 10 CFR 20 (Ref. 9). Additionally, it should be noted that all of the decontamination alternatives (listed in Section 6) include systems (e.g., HEPA, and charcoal filters)

4-2 which, if utilized, would further reduce the already small airborne concentration of thest isotopes. T he removal ef ficiency (99.97% or better) of these filters would redace any release of particulate radiation to negligible quantities.

-5 Airborne tritium concentrations in the reactor building are measured to be approximately 8.4 x 10 Ci/cc.

This value is consistent with the calculated estimates of airtarne tritium concentration which.is based on eactor building relative humidity and on tritium measured in the reactor building sump water. This concentration is 10 times lower than the maximum permissible aircorne concentration limit for tritium listed in Table 1 of Appendix B to 10 CFR 20 (Ref. 9).

5-1

- 5. 0 heed for Decontamination of the Reactor Buildina Atmosphere 5.1 Summary The reactor building atmosphere needs to be decontaminated in a timely manner primarily to permit the less restricted access to the reactor building necessary to gather information, to maintain equipment, and to proceed toward total decontamination of the Unit 2 facility. At present, the Kr-85 dispersed inside the reactor building atmosphere limits operations which could be conducted inside the building to preliminary cortamination data gathering. Following decontamination of the reactor building atmosphere, larger scale activities, such as detailed radiation mapping, preliminary decontamination, and shielding piacement, will be possib'e since lowered, radiation exposure levels will reduce the need for personnel protective gear.

The eventual removal of fuel from the reactor vessel (or defueling) is an important milestone in the overall cleanup effdrt which cannot proceed until atmospheric decontamination is completed. Defueling will eliminate the small, but finite, potential for inadvertent core recriticality, wMich could occur, for example, from accioental boron dilution of the reactor coolant. In addition, defueling will eliminate the major source of radioactive i

material in the reactor building. Decontamination of Kr-85 in the atmosphere would also provide the less restricted access to the reactor building needed to repair or replace core nuclear instrumentation, to raintain the reactor building air cooling system, and to support procetting of the reactor building sump water.

Although difficult to quantify, present conditions inside the reactor building pose risks to the physical and psychological health of residents in the Harrisburg-Middletown area. Public healtt. risks, including psychological stress, will continue to be a concern throughout the cleanup process. In the NRC staff's opinion, elimination of these risks require a safe and expeditious completion of all cleanup activities at the site. Decontamination of the reactor building atmosphere is the next required step in achieving this goal.

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5.2 Discussion The TMI-2 reactor is presently being maintained safely shut down, with damaged fuel in the reactor vessel. The i

i entent of fuel damage and the present core configuration are unknown. It is inportant that the reactor continue to be saintained subcritical and that the damaged fuel inside the reactor be removed from the reactor vessel and placed in a safe configuration to eliminate any potential for core recriticality.

As the minimum negative impact, core recriticality would result in the production of additional radioactive material which would require decontamination. Core recriticality could also lead to further degradation of the reactor coolant system and the possibility of uncontrolled release of radioactivity to the environment.

The licensee is presently relying on boron injected into tne reactor coolant system to maintair. the cere sub-I critical. Normally, this function is accomplished by inserting control rods into the core. During the accident, however, it is believed that some of the control rod material melted and may have drained out of the core. At presert, most instrumentation provided for monitoring reactor neutron flux, and therefore providing feedback on boron effectiveness, is inoperable. Only one nuclear instrument channel is operating. If this instrument fails, direct measurement of neutron flux in the reactor core would not be possible. It would then be necessary to infer the status of the core by periodic sampling and analysis of boron concentration in the reactor coolant. Although the staff considers the potential for core recriticality to be of low probability, it.will be a nunter of years before defueling is anticipated. In the interests of public and worker health and safety, the staff believes that q

removing the fuel in a timely fashion will eliminate the potential risk, no matter tow small, associated with the core in its present condition. Since decontamination of the reactor building atmosphere is the necessary next step in the path leading to core defueling, it should be undertaken in a safe and expeditio s manner. Purging the reactor building can achieve both of those goals, s

i 5-2 While activities leading to core defueling are being undertaken, it will be necessary to continue direct core monitoring. To allow the remaining core monitoring instrumentation to deterioriate would pose additional risks to the public ano to workers because of the potential for core recriticality to result in the generation of more radioactive fission products at Three Mile Island. Should this existing instrumentation f ail it will be necessary to decontaminate the reactor building atmosphere to achieve the access recessary to repair or replace them.

At present, radiation levels in the reactor building at the 305-and 347-foot elevations would result in total body dose rates of approximately 2.3 ren/ hour and 1.3 res/ hour, respectively. If a reactor building entry is made prior to decontamination of the atmosphere, heavy protective clothing and equipeent will be required. The neces-sary gear, including self-contained respiratory equipment, radiation detectors, communications equipment, per-sonnel dosimeters, and protective c.sthing would weigh approximate y 85 pounds and would hamper the powement necessary for workers to perform decontamination or maintenance-related tasks inside the building. Heavy pro-tective clothing would be expected to shield workers from essentially all of the direct beta radiation from the krypton cloud (150 rem / hour to unshielded skin), although some d' f f usion of the krypton through the suit would i

probably occur. This clothing, however, would not protect workers from gamma radiation or from high energy beta-emitting radionuclides which are believed to contaminate surfaces inside the building.

Decontamination of the reactor building atmosphere would reduce the total body dose rate by 30% on the 305-foot elevation and by 75% on the 347-foot elevation (the operating floor) to 1.6 rem / hour an3 0.3 rem / hour, respec-tively. The dose-rate values shown telow provide an example of expected dose rates accruing to an individual in self-contained breathing apparatus and protective clothing.

Dose Rate (Rem / Hour)

Radiation Elevation 305 Feet Before Decontamination After Decontamination Gamma (total body) 2.3 1.6 Beta (skin)

0. 8 0.8 Radiation Elevation 347 Feet Before Decontamination After Decontamination Ganma (total bcdy) 1.3 0.3 Beta (sk:n) 1.2 1.2 It should be noted that Kr-85 beta skin dose (approximately 150 res/ hour) is not a factor in this example due to the presence of protective clothing before decontamination and elimination of Kr-85 beta radiation af ter decon-tasination. Decontamination of the reactor building atmosphere, then, is necessary to reduce worker risk from gamma total-body exposures from Kr-85 and to eliminate and the risk and inefficiency of working in burdensome pro-tective clothing (including risks involving tearing the protective suit and worker injuries doe to (311ing).

i 4

j 5-3 i

j The reactor building atmosphere, which is at 100% relative humidity, is currently being maintained at approxi-sately 75'f by the reactor building air-cooling system. This cooling action is nalntaining the reactor building l

at a slight negative pressure (approximately -0.7 psig) with respect to the outside atmosphere. This pressure i

differential prevents leakage of the reactor building atmosphere to the environment. Other factors that affect the pressure differential between the reactor building atmosphere and the outside atmosphere include: (1) pressure differentials caused by wind currents over and around the building, (2) changes in barometric pressure, (3) changes in external air temperatures, and (4) the solar heat load on the building. The building air-cooling fans (four i

l operating, one standby) were qualified for three to four hours of continuous operation in a 100% relative humidity l

environment. Four fans have been operating nearly continuously since the March 28, 1979 accident in a high-humidity environment. It is not known if the standby fan is operable. The operating fans can reasonably be expected to fail sequentially over a period of time. Their sequential failure would result in a decrease of heat removal capability from the reactor building atmosphere and could ultimately cause the atmospheric pressure in the I

reactor building to increase and become positive relative to the outside atmosphere. The NRC staff has calculated j

that for worst-case conditions (i.e., all fans fall), this pressure could rise to as high as four psig. The j

reactor building has a design leakage rate of 0.2% by weight per day at 60 psig. The measured leakage rate of the reactor building during its most recent leak-rate test (conducted in early January 1978) was 0.095% by weight per day at 56 psig. Based on the relationship between observed leak rate and differential pressure, the staff calcu-lates that uncontrolled leakage of Kr-85 from the reactor building would not exceed five curies per day. The corresponding beta skin dose to the person receiving maximum exposure from this leakage would be dependent on local meteorology (i.e., the dispersion factor or X/Q) which typically varies from 1 x 10

• to 1 x 10 7 sec/m8 l

Thus, the one-day dose could vary from approximately 0.02 millirems to 0.00002 millirems. In view of the fact l

that the annual average X/Q is approximately 6.7 x 10 8 sec/m3 and uncontrolled leakage from the reactor building would involve small amounts of Kr-85, the staff does not consider such leakage likely to threaten the health and safety of the public. However, based on past public response to relatively small leaks of gaseous effluents to the environment, (e.g., leakage from the makeup and purification system resulting in a gaseous discharge of 0.3 Ci t

of Kr-85 on February 11, 1980), the staff believes that future uncontrolled leaks could generate significant psychological stress in the community. In the staff's view, a controlled purge, which is publicly announced, j

fully monitored, and conducted durir.g favorable meteorological conditions, is preferable to uncontrolled leakage.

The reactor building cooling system will also perform a vital function following decentamination of the reactor building atmosphere. This system will be needed to maintain a reasonable working environment inside the building and allow expeditious building decontamination and defueling activities. Decontamination of tne reactor building atmosphere would allow for cooling system maintenance and avoid recovery effort delays that might accompany cool-ing system failures.

Although a discussion of systems and alternatives for processing the reactor building sump water is not appro-I priate for this document (the forthcoming Programmatic Environmental Impact Statement is the appropriate document),

access to the reactor building will be necessary to ef fectively suppor' processing this water. Should NRC approve 1

9 1

a system for processing the sump water, the licensee vill require less restricted access to the reactor building to support processing with area washdowns. Area washdowns will assist in the removal of the crud and filterable material that would otherwise adhere to the walls and surfaces in the basement of the building as water levels decline. The primary reason for these washdowns is to protect workers from direct or airborne (from drying out) i sources of radiation from the walls. Area washdowns will not be possible unless the reactor building atmosphere is decontaminatet Lastly, the NRC staff believes expeditious decontaminaton of the reactor building atmosphere is necessary to

}

reduce long-term psychological stress in the TMI area by shortening the time necessary to complete the entire cleanup project.

l

6-1 6.0 Decontamination Alternatives 6.1 No Action The NRC staff has considered the possiblilty that no action be taken to decontaminate the TMI-2 reactor building f

atmosphere. This alternative would necessitate retaining the radioactive gas within the reactor building. This option has been rejected, however, as totally inappropriate for several reasons.

First, taking no action would subject the public to potential health and safety risks which exceed those of any other alternative, considered within this Environmental Assessment, for decontaminating the reactor building atmosphere. The potential rist s associated with taking no action are discussed in detail in Section 5.0.

These risks include possible core recriticality and corresponding production of additional radioactive materials. The 1

NRC staff believes that minimizing these risks depends on access of workers to the reactor building to permit continuation of activities leading to eventual defueling. This access, in turn, depends on the decontamination of the reactor building atmosphere.

An indepth discussion of both public health and occupational risks resulting from the employment of other deconta-mination alternatives is presented in the following subsections. Public hee.lth risks for all alternatives have been determined to be negligible.

6.2 Reactor Building Purae Systems 6.2.1 Introduction

~

A number of purge methods could be used to decontaminate the reactor building atmosphere. The staff has evaluated four purge methods which could be implemented ut111 ring existing plant systems and structures and two other purge methods which would require either new or modified plant system and structures. Those methods include: (1) a slow purge using the existing hydrogen control subsystem with relt:.ses from the unmodified 160-foot plant vent stack; (2) a fast purge using the existing hydrogen control subsystem and reactor building purge system with releases from the 160-foot plant vent stack; (3) an elevated purge using the existing hydrogen control subsystem and reactor building purge system with releases from the plant vent stack vlevated to 400 feet; and (4) an elevated purge using the existing reactor building purge system with releases from a new 1000-foot stack.

In addition, the staff has evaluated two methods of purging proposed by the Union of Concerned R ientists in a i

report submitted to the Governor of Pennsylvania (Ref. 3). The two methods proposed are release of a heated plume from a 250 foot refractory lined stack and an elevated release at 1000 to 2000 feet through a relatively light-weight tube held aloft by a tethered balloon.

6.2.2 Slow Purae The hydrogen control subsystem was "ginally installed for use as a backup system to the hydrogen recombiners.

The system is being modified to :,ow variable flow rates up to a maximum of 1000 cfm. Actual purge rates during a purge would be dependent on meteorolegical conditions and reactor butiding concentrations of Kr-85.

The hydrogen control subsystem would withdraw the reactor building atmosphere through a filter system, monitor the effluent radioactivity levels, and discharge the effluent through the 160-foot plant vent stack to the Environment.

i

, _ _ _ _ _. ~. _ _ _.. - - - - _ _. _ _ _ _ _ _ _ _ _

64 These releases would be made based on existing meteorological conditions such that release rates of radioactive materials would be controlled to ensure that the requirements of 10 CFR Part 20, the design objectives of 10 CFR Part 50, Appendix I (Ref. 11) and the applicable requirements of 40 CFR Part 190.10 (Ref. 12) are not exceeded.

6.2.2.1 System Description and Operation The proposed purge of the Unit 2 reactor building atmosphere to the environment would use the hydrogen control subsy en of the reactor building ventilation system. Radioactive gases purged from the reactor building would be dit:/.ed with the exhaust air from the ausiliary and fuel building ventilation systems and released throt.gh the Unit 2 vent stack, which is 160 feet above grade level. The major components of this system include: an eshaust fan, isolation valves, filtration system, and a radiation monitoring system. The flitration system consists of a prefilter, a HEPA filter, an activateJ charcoal filter, and a downstream HEPA filter. Replacement air to the reactor building would be supplied through the reactor building pressurization valve.

The slow rate purge alternative recommended by the NRC staff would be carried out within several limiting conditions. Most importantly, purging would be controlled to limit the cumulative maximum individual offsite dose resulting f rom the purge to less than the annual dose design objecthes (5 arem total body,15 arem skin) of Appendix ! to 10 CFR Part 50 (Ref. 11). Doses would be tracked during actual purging by using real-time meteorological data to calculate hourly dose rates in affected sectors surrounding the plant. (The region around TMI is divided into 16 directional sectors; w nd directional changes during purging will result in i

differing dose rates for individu(1 sectors.)

Cumulative dose, based on these calculated dose rates in each affected sector, would be updated hourly throughout the purge process. No hypothetical person in any s*ctor would be permitted to receive a dose in excess of the Appendix ! dose design objective. For example, if the calculated cumulative dose to a hypothetical person, based on actual Kr-85 release rates and real-time meteorology, reached the annual Appendix I total body (5 mrem) or beta skin (15 mree) dose objective in the North sector, purging would be discontinued when existing wind conditions could result in any incremental increase in dose to the North sector, in addition to Appendix 1 constraints, the slow purge procedure would be limited by the existing Three Mlle Island effluent release technical specifications for noble gases (Ref. 13). These specifications consist of an instantaneous release rate limit and a quarterly average release rate limit. Although these specifications have dose limitations as their bases, they have bean implemented as noble gas release rate limits. Release rate j

alone determines conformance or non-conformance with the technical specifications. As applied to the slow purge rate alternative, the technical specifications effectively apply only to Kr-85 since it is the remaining noble gas in the reactor building.

One Kr-85 release rate technical specification requires that the instantaneous rate not exceed 45,000 pC1/sec.

3 This instantaneous limit is derived from the annual average X/Q* (6.7 x 10 8 sec/m ) for the TMI site and the maximum permissible concentration (MPC) for Kr-85 in unrestricted areas (3 x 10 ' pCf /cc) as listed in 10 CFR 20 Appendix B, Table 2, Column 1 (Ref. 9).

This specification provides for short-term operational flexibility.

Any extended release at this relatively high rate would quickly become limiting to operation because the cumulative Appendix I dose restriction also limits the conduct of the purge alternative (Ref. 11).

A quarterly averaged release rate technical specification limit of 7200 pCi/sec, based on a more restrictive X/Q sec/m ), would also be applicable to a slow purge. This quarterly averaged release rate limit 3

value (4.2 x 10 5 is based on not exceeding, in one quarter, four times the annual Appendix ! dose design objective. Again this l

'See the Glossary for a definition of X/Q.

l l

6-3 specification provides for relatively short periods of operational flexibility because relatively high release rates (and hence dose rates) can be averaged in a quarter with relatively low release rates. Cumulative Appendix I dose, however, cannot be exceeded.

The dose rate during a purge period is dependent on the product of three variables; the Kr-85 release rate, meteorological dispersion f actor (X/Q) and the Kr-85 dose conversion f actor. Only the Kr-85 dose conversion f actor is a fixed value.

While meteorology (X/Q, sec/m3) cannot be controlled during a purge, release rate (C1/sec) can be adjusted to limit the resulting dose rate. During periods of less favorable meteorology, therefore, release rates can be selectively reduced to maintain desired dose rate levels. Detailed licensee procedures for maintaining acceptable purge dose rates during varying meteological conditions by adjusting release rates, have been reviewed and approved by the NRC staff. In addition, members of the NRC onsite staff will monitor the licensee's actions during the entire purge.

At the onset of the slow purge scenario, purge rates would be expected to be in the range of 50 to 75 cfa. As the Kr-85 concentration in the reactor building decreases, the purge rate would be increased to a maximum of approximately 1000 cfm.

The purge rate during any period would be dependent on the aforementioned limiting conditions.

The incremental dose (mrem) for each purge period is obtained from the product of the dose rate (arem/sec) and time duration (sec) of the period. The total dose due to the entire purge of 57,000 Ci of Kr-85 is obtained by summing the individual incremental doses from each purge period. The staff estimates that over a 60-day period it would require approximately 30 days of actual purging to reach the MPC level of 1 x 10 5 pct /cc in the reactor building.

During purge operations with the hydrogen control subsystem, makeup air would be supplied to the reactor building through the reactor building pressurization valve. This ensures that air would flow into the reactor building and a small negative pressure relative to the auxiliary building would be maintained with the hydrogen control subsystem exhaust fan. The reactor building pressurization valve is interlocked with the exhaust fan to shut when the fan stops. hevertheless, there is the potential for backflow of contaminated reactor building air through the reactor building pressurization valve to the 328-foot level of the auxiliary building if the reactor building pressure is not maintained slightly negative with respect to the auxiliary building. General area radiation monitors in the auxiliary building would detect the radioactivity to signal for isolation of the reactor building by stopping the purge.

Flow rate, temperature, and radiation level of hydrogen control subsystem flow would be monitored during purging operations. System flow rate, temperature, and radiation level are measured at the hydrogen control subsystem fan discharge pc, int. General area radiation levels around t M filter housing on the 328-foot level of the j

auxiliary building weJ1d be monitored by a local radiation monitor. General area radiation monitors have local l

and remote readouts in the Unit 2 control room.

Ta01e 6.2-1 provides a list of the major components used in the hydrogen control subsystem. The subsystem exhaust fan is interlocked to stop automatically and valves close automatically to isolate the system if high activity is detected in the effluent.

Figure 6.2-1 provides a flow diagram of the hydrogen control subsystem. Modifications to the hydrogen control subsystem would include (1) replacing the hydrogen control subsystem exhaust fan with a fan capable of producing a maximum flow of 1000 cfe, (2) recommissioning the auxiliary building and fuel-handling building filter trains, (3) calibrating and reactivating the stack monitor, (4) securing the supplementary filter train by turning off thc supplementary fans and closing the isolation door from the stack inlet plenum to the filters, and (5) uncap-ping the plant vent stack.

l 6-4 Table 6.2-1 Hydrogen Control Subsystem Effects of Loss System Operator of Operator Auto-Action Interlocks Fan AH-E-34 Electrical Reduced flow Stop fan High activity thru system on HPR-229" Pressure Sens-Electrical Fall at is None None ing Line Isolation Valves A-V5 &

AH-V6 R8 Pressuri-Air operated Valve fail Closes on When fan AH-E-34 zation closed loss of stops, valve Valve AH-V7 power shuts R8 Hydrogen Electrical Fall as is None None Control motor-opera-Valve AH-V25 ted local control R8 Hyd: ogen Air operated Fall closed Opens when fan None Control Dis-starts charge Valve AH-V36 Reactor Bldg.

Air operated Fall closed No.9e None Hydrogen Con-trol Isola-tion Valve AH-V52 AH-V-3A, B Air operated Fall closed Fall closed None RB Isolation on high loss of power Valves radiation,

" Monitor mounted in the exhaust duct downstream of the exhaust fan.

6-5 6.2.2.2 Occupational Exposure The design criteria for the existing hydrogen control subsystem is consistent with ths "as low as reasonably achievable" guidance of 10 CFR Part 20 and Regulatory Guide 8.8 (Ref. 14). Control during a purging interval would be exercised remotely from the Unit 2 control room. However, an auxiliary operator would be required to be in the auxiliary building during system operation. This operator would have communication ties with the control room and be stationed in a low-radiation area.

J The dose to operators during processing will be approximately 0.8 person-rem. Changing the two HEPA filters will also contribute to occupational exposure. These filters have a surface dose rate of appmximately 0.17 R/hr and filter changeout will require approximately one-half hu a per filter. It is expected that the filters will be changed only once at the end of the purge operation, resulting in approximately 0.4 person-rem. There-fore, the total exposure for processing and filter changeout would be approximately 1.2 person-rem.

6.2.2.3 Environmental Impact Slow Purae - Using the Hydrogen Control Subsystem With Release from the Unmodified 160-foot Plant Vent Stack.

Based on the release of 57,000 ci, and the annual average dispersion factor of 6.7 x 10.e 8

sec/m, the beta skin dose is estimated to be 11 arem and the gamma total body dose is estimated to be 0.2 mrem. These numbers represent the maximum dose that could occur to an individual present at the site boundary for 70% of the release period.

In the staff's evaluation, an annual average X/Q is used to calculste offsite concentration and dose. The annual average X/Q is used because predictions of actual meteorological conditions for a particular time are impossible. However, the probabilities are high for having hourly 'tmospheric diffusion conditions during any a

season that would provide a considerably less conservative X/Q than the annual average X/Q used by the staff in their evaluation.

The dose received by the population residing in the 50-mile radius around the reactor due to the release of the 57,000 Cl of Kr-85 was evaluated. The methods used for this calculation are described in Regulatory Guide 1.109 (Ref. 15). A standard grid was employed which segmented the population into 160 elements. This grid contains 16 sectors (N clockwise through NNW) each centered on the appropriate direction. Each sector is divided into segments at standard distances of 2000 f t (.37 mi),1, 2, 3, 4, 5,10, 20, 30, 40, and 50 miles. The meteoro-logical dispersion parameters which were used were the same as those that were used for the Final Supplement to the Final Environmental Statement for Three Mile Island Nuclear Station, Unit 2, (NUREG-0112), issued December 1976 (Ref. 16).

The meteorological dispersion parameters represent annual average conditions and were developed on the basis of historical data collected at the site. The 1980 population was taken from NUREG-0558 (Population Dose and Health Impact of the Accident at the Three Mlle Island Nuclear Station) (Ref.17).

The 50 mile population dose calculated by this methed is 0.76 person-rem total body due to the gamma component of krypton decay and 63 person-rem skin due to the beta component of the krypton decay.

6.2.2.4 Accident Analysis The components for the purge system are located in the Unit 2 auxiliary building. A major rupture in the purge system would allow Kr-85 to be released to the auxiliary building. Any Kr-85 released to this building would be exhausted through the auxiliary building ventilation system to the plant stack. This path would be the same release pathway as that for the normal purge system.

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6-7 Figure 6.2-2 provides a flow diagram of the reactor building purge system. The major components of this system l

include two air supply fans and filter units, two isolation valves in each purge air supply duct, two air exhaust fans and filter units, and two isolation valvea in each purge air exhaust duct. The exhaust filter units consist of a prefilter, a HEPA filter bank and a second HEPA filter bank.

I The slow purge method evaluated in Section 6.2.2 was based upon not exceeding the existing Appendix B Technical l

i Specification limit (45,000 pCi/sec) for Krypton-85 (Kr-85) releases through the 160 foot plant vent stack

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(Ref. 9).

These echnical Specification limits are based on conservative annual average meteorological con-8 ditions, where X/- = 6.7 x 10 5 sec/m. However, by controlling the purge rates to take advantage of more favorable meteoro ogical conditions, higher purge rates can be achieved while still not exceeding the require-ments of 10 CFR Part 20 (Ref.19), the design objectives of 10 CFR Part 50, Appendix ! (Ref. 11) and the applicable requirements of 40 CFR Part 190.10 (Ref. 12).

When favorable meteorological conditions exist, the hydrogen control subsystem would be operated at its maximum flow rate of 1000 cfm until the Kr-85 concentration in the reactor building h reduced to 0.22 uCi/cc. It would require approximately 50 hours5.787037e-4 days <br />0.0139 hours <br />8.267196e-5 weeks <br />1.9025e-5 months <br /> to reduce the current reactor building Kr-85 concentration of 1.0 uC1/cc to 0.?2 uCi/cc. When the reactor building Kr-85 concentration is reduced to 0.22 uCi/cc, the hydrogen control subsystem would be secured and the the reactor building purge system started with an approximate flow rate of 5000 cfm.

The reactor building purge system would operate at 5000 cfm for approximately 70 hours8.101852e-4 days <br />0.0194 hours <br />1.157407e-4 weeks <br />2.6635e-5 months <br /> to reduce the building concentration of Kr-85 to MPC (1 x 10 5 uCi/cc). Thus, the total actual purge time using both systems would be approximately 120 hours0.00139 days <br />0.0333 hours <br />1.984127e-4 weeks <br />4.566e-5 months <br />. The calendar time frame necessary to complete the fast purge scerario is dependent upon achieving favorable meteorology and is especially sensitive to the seasonal variations that can occur (see discussion in Section 6.2.3.3).

6.2.3.2 Occupational Exposure The occupatiunal exposure anticipated from the fast purge smnario is approximately the same as for the slow purge scenario as discussed in Section 6.2.2.2.

6.2.3.3 Environmental Impact The fast purge environmental impact would be approximately the same as for the slow purge as discussed in Section 6.2.2.3.

For the fast purge during the spring season (March-May) there is a f air likelihood of being able to expeditiously release and maintain sufficiently low doses to the public in accordance with the criteria discussed in Section 6.2.3.1.

We estimate that favorable meteorology during these months may permit the fast purge option to be accompIhhed within a 2-calendar week period. However, for the fast purge during the summer and f all months (June-October), we estimate, based on historical data which show a small probability of favorable meteorological conditions, that this alternative would require approximately two calendar months to complete. Thus, given the June tnru October meteorological conditions, the calendar time frame necessary for both the fast purge and slow purge are essentially equivalent. As the period of favorable meteorology (i.e.,

March-May) is nearly over, the staff considers the fast purge to be a less desirable alternative for the following reasons:

(1) The advantage of the fast purge, namely a lessening of potential psychological stress for area residents, would be lost during the summer months when total elapsed time required for both fast and slow purge alter-natives are essentially the same.

6-8 (2) Reactor building purging should not be delayed past the summer and f all months to allow for better winter meteorological conditions for those reasons elaborated in Section 5.0.

6.2.3.4 Accident Analysis The accident analysis described in Section 6.2.2.4 would apply to this alternative.

6.2.4 Elevated Release Points 6.2.4.1 Introduction Stacks are normally designed to assure that ef fluent exit velocities will give eanimum rise to releases and eliminate the make-cavity effects of adjacent structures. Factors af fecting meteorological dispersion of stack ef fluents include the height and position of nearby structures and the layout of local terrain. The existing plant vent stack is 160 feet above grade, with an exit diameter of 9 feet. In order to evaluate the dose reduction offered by increasing stack height, the staff has evaluated the alternatives of raising the existing stack to 400 feet or construction of a ne= 1000-foot stack.

6.2.4.2 Estendinq 5 tack He'cht to 400 Feet 6.2.4.2.1 Description A teeporary sheet setal entension with the same diameter as the existing stack, could be used to elevate the existing plant stack to 400 feet above grade. The extension would be surrounded with scaf folding, which =ould be used to support the entension with the aid of guy wires. The existing stack could also be elevated to 400 feet by the addition of 10-foot sections of the carbon-steel pipes. These sections would have the same diameter as the existing stack.

Assuming that procurement of the necessary materials for extending the stack can be readily accomplished, the staff estimates that the engineering design, orocurement, construction, and leak testing cf either variation would require a minimum of four to five sonths. This estimate does not consider the potential interferences of existing and new structures (e.g., processed mate

• storage tanks) which may result in further schedule celays.

6.2.4.2.2 Occupational Exposure Occupational exposures described in Section 6.2.2.2 would apply to this alternative.

6.2.4.2.3 Environeental Impact An increase in stack height to 400 f t would clininate the ef fect of the reactor building make cavity he.ever, the stack would remain within the wake cavity of the site cooling towers. In addition, the plant location in a river valley surrounded by higher elevation terrain diminish the effects of an elevated release point of l

400 feet. An increase in the plant st.ck height (up to 400 f t) would reduce the already negligible (see Section 7.1) dose to the maximum exposed individual by a factor of approximately eight belem the doses esticated for the j

fast or slow purge.

l 6.2.4.2.4 Accident Analysis The Accident analysis described in Section 6.2.2.4 would apply to this alternative.

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6-9 6.2.4.3 Cor.structing a 1000-Foot Stack The staff has evaluated the dose reduction benefit resulting from the construction of a 1000-foot stack.

A 1000-foot stack would assure that releases are unhindered from the effects of all onsite structures. The technology for constructing a stack this height is well established.

A stack 1000 feet high would require, at a minimum, a 60-foot diameter base. Construction of a foundation this size would require not less than three months and construction of the remainder of the stack would require approximately six months. Additional design, engineering, construction, and testing time req'uired to connect the stack with the existing purge syste9 and ensure proper operation would add two to three months to the instal-lation schedule. Therefore, the staff estimates that a minimum of 11 months would be required to construct and make functional a new 1000-foot stack.

6.2.4.3.1 Occupational Exposure Occupational exposures described in Section 6.2.2.2 would apply to this alternative.

6.2.4.3.2 Environmental Impact A stack release at 1000 feet would physically place radioactive effluents above the effects of the cooling tower wake cavity and nearby terrain and would result in reducing offsite doses to the maximally exposed individual by a factor of approximately 230 below the doses estimated for the fast or slow purge.

6.2.4.3.3 Accident Analysis The acc_ident analysis described in Section 6.2.2.4 would apply to this alternative.

6.2.5 Staff Evaluation of Union of Concerned Scientist Elevated Release Proposals 6.2.5.1 Introduction In response to a request by tha Governor of Pennsylvania, the Union of Concerned Scientists (UCS) evaluated the health and safety consequences of the disposition of the reactor building atmosphere including the purging alternative recommended by the NRC staf f in its draf t Environmental Assessment (NUREG-0662). In their report to the Governor (Ref. 3), the UCS reported that based on " current evidence of ef fects of whole body radiation on human populations,

,no health effects would be anticipated as a result of the ' ground release' venting."

However, the UC5 did not recommend purging, as proposed by the staff, because of the potential psychological stress UC5 believes purging might induce. As a result, the UCS proposed two alternative means of purging the reactor building which they believe will minimize potential psychological stress. The first method proposes purging by heating the effluent with an incirerator prior to releasing it through a 250-foot refractory lined stack. The t.econd method proposes an elevated release at 1000-2000 feet through a relatively light weight tube held aloft by a tethered ballon.

6.2.5.2 Hot Plume Release Through a 250-Foot Stack 6.2.5.2.1 Description The staff has evaluated the Union of Concerned Scientists (U5C) preposal to construct an incinerator (and stack) to heat the ef fluent p.rged f rom the reactor building. Under ideal conditions, an incinerator of this type should be located as close as possible to 1 9 auxiliary building to minimite the engineering and construction

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6-10 ef fort necessary to interf ace =ith the reactor building purge systes. UCS " rough estimates" place the construc-tion time for an incinerator f acility at f ree seven to nine sonths. This time estimate does net include time requirements for design, engineering, procureseet of saterial, and pre-cperaticnal testing. The staff esticates for these required ef forts wculd add at least two months to the overall construction ef fort, resulting in a minisus schedule cf nine months for systee avallatility.

6.2.5.2.2 Cccupational Exposure Occupational esposures described in Section 6.2.2.2 -ould apply to this alternative.

6.2.5.2.3 Environmental Irpact Staff evaluations show that dose reductions can be achieved if heat is added in sufficient cuantities to alle=

the ef fluents to raise above the make cavity of the cooling towers. The release cf a eeated plume free a 250-foct stack would result in reducing of fsite doses to the manipally esposed individual Dy a f actor of appre-minately 30 below the doses estinated for the f ast or lo= purge.

6.2.5.2.4 Accident Analysis The impact of an accicent involving this alternative =ould result in a total-tody cose =hich is apprcximately five tiees greater than the slo = purge accicent dose discussed in Section 6.2.2.4 These deses =culd still represent a small fraction of 10 frR Part 100 accident-dese limits (Eef. 18).

6.2.5.3 Tre Tethered Balloon / Tube Release at 2000 Feet 6.2.5.3.1 Cescription Tre staf f has evaluated tre UCS pecposal to purge tse reactor building atscsphere threugh a reinferced f atric tute held alof t at 2000 feet aeove Three Mile Island by a tetnered talloon ( Also see Section 9.2.5)-

As stated by the UCS, this technique is unigme and untried a*d =culd require further study to deterwire its feasibility.

In addition, the UCS stated that tney did not knc. if suitatie space was available en Three Mile Island to ircierent this alternative.

In general, the staff finds tBe UC5 pecpesal, =et te not =ithcut pretless, technically =araatle and pretably capable of being implemented =it9in a yeae from tre time the decision is sade to use it.

l The major problee with the UCS proposal is that, at present, there is no existing a*ea en Three Mile Istard

=5fth is suitable for lau ching the tethered talleen aad its attacPed 20GO-foot f abric tute.

The UC5 has stated n

that their preposal mould require uncestructed ground and air scace accccuiaately 2003 feet Icrq ty 200 feet mice.

The staf f has examined TPree Mile Island f or poteatial sites cf suf ficiert sice to iPoletent the bCS i

l preposal.

The island is appecnisately 11,000 feet in length by 1,700 feet in =icts.

Tre ncrtteen cre-ttird of the island is occupied by Thre* Mile Island Nuclear Station Units I and 2.

Tee soutaern pret of the island contairs sose 0-pen area, a f airly large moeded aret. and a shalle= basin area trat is pro.e to ficoding. Tre aeea with the ecst open 5 ece is south of the Unit 2 cocling 10=ers and includes an existirg parking Ict IBe staff estimates tre open space to be appromieately 200 feet er more =ide and 1500 feet icn;. Scee trees in t*e -cceed aeea cf the island =ould have to be recoved te enlarge tPe area.

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6-11 This potential site is a considerable distance from the auxiliary building and the reactor building purge system with which it would have to interface. The large distance would magnify the engineering and construction ef fort involved, and would ultimately impact the schedule for system availability. A detailed design and layout of the interconnecting piping between the auxiliary building and the launch site would have to be performed.

The piping would have to be buried (at least in some locations) in order not to restrict normal traf fic (e.g.,

solid radmaste shipments, concrete truck deliveries, etc.) about the site. The piping would require leak testing following welding to ensure that no gas bypass pathways exist. The need for booster pumps wou'd have to be determined in a detailed engineering evaluation. The staff has also consulted with the Department of Energy's (DOE) Ames Laboratory concerning the feasibility of the UCS balloon proposal. In their judgment, the first 500 to 1000 feet of elevation crucial in determining what ef fect wind shear and air turbulence will have on fabric tube behavior. Te ting is recommended. The staff concurs with this observation. Thus, a test of the integrity of the reinfo ced fabric tube (1-foot diameter) under different wind shear and air turbulence conditions would be required. The staff envisions these tasks as a major desion effort. The staff has determined that the schedule required to accomplish these actions and demonstrate system operability is longer than the timetable estimated to the UCS for system availability.

The UCS stated that a timetable for a tethered balloon system was "somewhat difficult to estimate" but projected a schedule of four to seven months. This schedule is based on the availability cf a suitable location on Three Mile Island for system implementation and successful completion of feasibility tests. Based on the remote location of suitable land area from the auxiliary building, the staff believes that the UCS has underestimated the engineering and construction effort required to maje this technique workable. The staff estimates that this effort would require from 7 to 10 months to make the tethered balloon system operable. The staff does not believe that postponing decontamination of the reactor building atmosphere for this period of time is acceptable for the reasons discussed in Section 5.0.

6.2.5.3.2 Occupational Exposure Provided adequate controls are established to isolate or bury the required interconnectirg piping, the occupa-tional exposures described in Section 6.2.2.2 would apply to this alternative.

6.2.5.3.3 Environmental Impact An elevated release at 2000 feet would physically place radioactive effluents above the effects of the cooling tower wake cavity and nearby terrain and would result in reducing offsite doses to the maximum exposed individual by a factor of approximately 300 below the doses estimated for the f ast or slow purge. However, the staff would have to assess the psychological impac* of this highly visible alternative on nearby residents.

6.2.f.3.4 Accident Analysis The accident analysis described in Section 6.2.5.2.4 would apply to this alternative.

6.2.6 Summary The staff has evaluated six alternative methods for purging the contaminated reactor building atmosphere to the environment. Those methods include (1) a slow purge using the existing hydrogen coatrol subsystem with releases from the unmodified 16> foot plant vent stack, (2) a fast purge using the existing hydrogen cortrol subsystem and reactor building purge system with releases from the 160-foot plant vent stack, (3) an elevated purge using the existing hydrogen control subsystem and reactor building purge system with releases from the plant vent stack elevated to 400 feet, (4) an elevated purge using the reactor building purge system with releases

6-12 from a new 1000-foot. stack, (5) a hot plume release using the reactor building purge systee and a new i ncinerator and 250-foot stack (a UCS proposal), and (6) an elevated purge using the reactor bulloing purge system and a reinforced f abric taoe held alof t at 2000 feet by a tethered balloon (a UCS proposal).

All six purge alternatives are similar in some respects. All the proposed alternatives would result in appro-minately the same occupational esposure and the consequences of a postulated accidental release are also roughly equivalent. All the alternatives are capable of being implerented in accordance with the requirements of 10 CFR Part 20 (Ref. 19), the dose design objectives nf 10 CFR Part 50, Appendix I, (Ref 15), and the applicable require-ments of 40 CFR 190.10 (Fef. 12). No health effects -ould De anticipated froe implementing any of the sin purge alternatives (see Settion 7.1).

However, there are signifiCant dif ferences among these alternatives. The slow purge and fast purge Could essentially be implemented lerediately (except for meteorological constraints for the f ast purge). The remaining four alternatives would require modifications ta plant systems and structures resulting in estimated schedules for system availability ranging from a sinimum of four to five months (stack modified to 400 feet) to as long as 11 months (a new 1000-foot stack). Another potential dif ference associated with the various purge altcrnatives is the potential psychological impact that each mignt have.

In fact, the UC5 proposed their sariations of tne purge alternative not because of concern over health ef fects (none are anticipated), but as a means of reducing potential psychological stress. Because of inherent and uncertain delays, the NRC staff does not believe that the UCS proposals wculd succeed in alleviating psychological stress. On the contrary, the tethered balloon could even augment stress, depending on public perception. A tethered balloon would be easily visible to the nearby residents and would be an attraction of sorts that may create as such stress as it is intended to alleviate.

The HEC staff supports the slow purge alternative as the best means cf decontaminating the reactor building atmosphere, thereby empediting the continued cleanup of the plant in a safe nanner.

In the staff's opinion, J' best means of alleviating psychological st ess in the vicinity around the plant is to cceplete the overall recovery ef f ort safely and quickly.

6.3 Selective Absorption System 6.3.1 Introcaction The selective absorption system evaluated by tre NRC staff would operate by withdra.ing gases from the reactor building, separating essentially alt the krypton from the gases, and returning the gases to the reactor buildirg.

Krypton is separated f rom other gases in a combination adsorption stripping column which operates at greater than atmospheric pressure and uses a 11auid fluorocarbca as a solvent. The separated and concentrated krypton may then be stored ersite or transported of f site foe disposal. Alternatively, krypton gas in containers could be transported to and released at some remcte site.

6.3.2 System Description and Operation A fluorocarbon absorption process for removing ncble gas fission products (krypton and menon), carbon-14, and other radioactive contaminar3% f rom gaseous waste, has been under developeent since 1967 by Union Carbide at Oak Ridge National Laboratory (CE%t). Following their initial work to obtain solvent chemistry informatien and to develop the process system OE5L personnel constru(: ) a small pilot plant.

This pilot plant utilizes a single absorption coluna process with a maxieus gas flow rate of 15.0 scfm and has been in cperation since 1978.

Actual removal ef ficiencies greater than 99.9% for krypton have been cbtained. However, these ef ficiencies were obtained for influent concentrations of noble gases substantially higher

• 'ir those existing in the reactor building. Based on the results of the developeental and pilot plant test r ograms, CRNL personeel are optimistic that their absorption process could be used at Three nile Island (TMI).

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6-15 The existing pilot plant, hcwever, is not believed, by either the hRC staff or ORNL personnel, to be a practical system for decontaminating the TMI reactor building atmosphere. This small-scale laboratory system was not designed to be portable and is not readily adaptable for use at TMI. Approximately 50% of the hardware, including refrigeration and reversing heat exchanger systems, which would be needed at THI, are not presently incorporated in the ORNL model. Most importantly, however, the existing pilot plant is unacceptable for use in decontasinating the atmosphere in the reactor building because of this system's very small flow capacity. At 15 scfm it would require nearly three years of continuous processing (i.e., no downtime for repairs and maintenance) to decontami-nate the atmosphere to the maxmimum permissible Kr-85 consentration (1 x 10 5 pCi/csA) for workers as required by 10 CFR 20 (Ref. 19).

A larger selective absorption system, with the capability to process approximately 150-200 scfs, has also been evaluated by the NRC staff. Although a selective absorption system of this size has never been constructed, it would be expected to ef fectively remove more than 99% of krypton f rom the process stream. After passing through the column, the gis stream would flow back to the reactor building. Krypton would be removed f rom the column in a separate flow stream and transferred to pressurizeo containers for long-ters (100 years) storage. The krypton removal may be accomplished by either a bleed-and-feed process or by continuous operation. A system designed to process 150-200 scfm, if operated continuously for about two months, would reduce the amount of Kr-85 in the reactor building atmosphere to less than 0.1% of its current inventory. We estimate that processing about 23,000,000 ft of gas (11.5 reactor-building volumes) would be required to reduce the krypton level in the 3

reactor-building gases to the manicum permissible concentration of Kr-85.

This would require approximately three months of continuous processing.

The absorption system is based on the property of a fluorocarbon, namely dichlorodifluoromethane, or Freon 12, to selectively absorb ncble gases. The process has been integrated into a single combination column with sup-porting equipment, as shown in Figure 6.3-1.

Contaminated gases are withdrawn from the reactor building, dehu-midified, filtered, compressed to approximately 125 psig, and cooled to near -30*F.

The gas would then be fed into the absorption section of the combination column and contacted countercurrently with the downflowing liquid freon solvent. The solvent containing the dissolved Kr-85 would subsequently flow into the intermediate and final stripper sections of the column. The reboller at the bottom of the column would operate at 104*F and 125 psig. The solvent f rom which the Kr-85 has been removed would be cooled to -33*F before it would be pumped back to the top of the column. Trace quantities of water and iodine may be removed from this solvent stream by a molecular sieve and/or silver-impregnated zeolite prior to recycling. The decontaminated gas would then leave the top of the column. Decontaminated gases may contain 5 to 10% Freon 12, and would, therefore, be passed through a turboempander and a molecular sieve bed (a filter) to recover solvent. Tne decontaminated gas would then be recycled into the reactor building until the Kr-85 concentration reached allcwable limits.

The concentrated krypton waste gas =culd be compressed and placed in high prcssure cylinders for storage. The cumulative waste gas collected from processing the contents of the reactor building cculd be stored at 2000 psig J

in a few stancard gas cylinders. The internal volume of one standard gas cylinder is 1.54 feet. The krypten 3

activity in a cylinder will necessitate radiation shielding (approximately one inch of lead) and some cooling.

4 Alternatively, the krypton gas could be stored at lower pressure (and with lower risk of leakage) in a larger number of these cylinders. Onsite storage is discussed in Section 6.8 and transportation and, burial or release of krypton in a remote :ccation are discussed in Section 6.9.

Members of the NRC staf f with extensive nuclear constructinn experience estimate that it would require at least j

16 months

• to make a scaled up selective absorption system, capable of processing 150-200 scfm. into operation

'ORNL personnel have estimated that a minimum of 13 months would be required on a " test effort" schedule for making a 150-scfm system operational at IMI.

This estimate inCIudes no Contingencies and several simplifying assumptions (Ref. 23).

A more optimistic schedule of 6 months has also teen estimated by a Congressional staff aide (See Section 9.0).

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6-17 (2) Gas Storage The process product, concentrated krypton gas, coJld be stored onsite in pressurirec containers. Numerous container configurations can be designed. For 7 bounding calculation, the staff has asummed that all 57,000 Curies of krypton are stored in one container. If that container ruptured, a release of the krypton to the confinement structure and subsequent releases to the envirorment over a two-hour period would result in a total-body gamma dose at the site boundary of 20 mrem and a beta skin dose of 1700 mree, assuming a l

X/Q of 6.8 x 10 sec/m This calculated total body dose is a small fraction of the limits set forth in 10 CFR Part 100 (Ref. 15). There are no skin dose limits in 10 CFR Part 100 Summary The selective absorption process has been studied and has had extensive development on a small scale. Large-scale operation has not been proven, but all signs indicate that the absorption system would perform satisfacto-rily to remove krypton from the TMI reactor building atmosphere. The existing pilot plant at ORNL is not portable and does not incorporate all of the components which would be needed at TMI. The pilot plant, because of its small flow capacity, would require more than three years to process the building atmosphere to the maximum permissible concentration of Kr-85.

The NRC staff's "best effort" estimated time required to construct a scaled-up (150-200 scfe) absorption system at TMI is at least 16 months, but a longer time may be needed, depending on the number and complexity of problems that could arise during the design, procurement, construction, testing, or operation phases of such a project. Based on prior operating esperience, the occupational exposure due to processing should be very low.

Doses to the public would be neglibible since only minimal leakage of Ar-85 f rom the system itself is expected. The estimated occupational exposure resulting from extended onsite storage is90-170 person-rem.

(See Section 6.8.)

See Section 6.9 for a discussion of transportation and offsite disposal.

Worst case accident scenarios do not result in threats to public health and safety.

6.4 Charcoal Adsorption Systems 6.4.1 Introduction The following discussion presents the NRC staf f evaluation of a nonregenerative charcoal adsorber system. This system is siellar to those used in boiling water reactor (BWR) of f gas treatment systems which are routinely used to retain noble gases for decay prior to their release to the environment. The staff evaluated both the ambient temperature and refrigerated charcoal adsorber systems. Both systems would require extremely large volumes of charcoal; the ambient system would require 34,000 tons and the refrigerated system 12,000 tons. Both charcoal systems when operating normally would have no releases associated with them; however, during anticipated operational occurrences minor releases can be expected. Since noble gases do not react chemically with charcoal, long-term survelance would be required.

A regenerative charcoal adsorber system was proposed in a public comment. The NRC staff has determined that this proposal is not feasible and it is not recommended. A discussion of this proposal is contained in Section 9.5.16.

6.4.2 System Description and Operation Ambient Charcoal System. The transfer of radioactive airborne activity from the reactor building to the ambient charcoal system would follow the same flow-path described for *" purge system. The radioactive airborne activity f rom the reactor building atmosphere will contain moisture. If the charcoal in the adsorber system is exposed to humidity in excess of 3%, the charcoal would lose its capacity to adsorb krypton. The major fraction of the moisture would be removed as the airborne activity passed through the cooler condenser. Additional moisture

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Ref rigerated Adsorber System. This system would require 150 tanks of charcoal. The radioictivity in each succeeding tank would decrease as the activity in the reactor building decreased. The tank with the highest activity would contain approximately 4300 Curies. If the same accident assumptions are used for this evaluation as were used above, the resulting doses would be increased by a factor of 3.

Therefore, a beta skin dose of 124 mrem and a total body dose gamma of 1.5 area could be expected.

Summary It is possible to remove the Kr-85 f rom the reactor building with either room-temperature or refrigerated charcoal adsorber systems. The primary advantages of the rooe-temperature charcoal adsorber system are simplicity of operation and the capacity to accommodate extremely radioactive gas mixtures. However, the major disadvantage for a room-temperature charcoal adsorber system is the large volame of charcoal it requires. A refrigerated charcoil adsorber system would reduce the volume of charcoal required. However, to gain a reduction in charcoal volume, an increase in equipment complexity would result. Since the primary form of radioactivity in the reactor-building atmosphere is Kr-85, a noble gas fission prod.:ct that does not ordinarily react chemically, the charer,a1 adsorber would function as a physical adsorber to retain the Kr-85.

Loaded charcoal beds ~would then have to remain in storage approximately 100 years to permit radioactive decay of Kr-85 to insignificant levels. The hRC staff has estimated that a charcoal system could be made operational in 2-4 years. This lead time is unacceptable for those reasons discussed in Section 5.0.

6.5 Gas Compression System 6.5.1 Irtroduction The gas compression system involves drawing off the reactor building atmosphere into suitable pressurized storage containers so that the entire inventory of Kr-85, remains in pressurized storage for approutmately 100 years to permit radioactive decay to insignificant levels. Tnis system would reduce the Kr-85 concentration in the reactor building by feed and-bieed operation to the maximum permissible concantration of 1 x 10 5 pCi/cc. To accomplish this, approximately 23 million cubic feet (11.5 reactor-building volumes) would have to be processed by the system.

I The staff has received a number of letters from the public suggesting alternatives to the onsite purging of the l

Kr-8., g a s. Included were suggestions for compression and storage of Kr-85 and of f site shipment with subsequent release at a remote site. Transportation and off site disposal of Kr-85 are discussed in Section 6.9.

Addi-tionally, concents on gas compression alternatives are addressed in Section 9.0, 6.3.2 Systee Description e,d Operation The gaseous contents of the reactor building would be transferred to pressurized gas containers for long-term stcrage. The containers can be designed in various pressure / volume combinations to accomodate the reactor-building gases.

To reduce activity in the reactor building to maufmum permissible concentrations, a total of 11.5 reactor building volumes (23 million cubic feet) would be transferred to storage. The compressed gas train would include gas dryers, a charcoal adsorber, a HEPA filter, three gas compressors, storage containers, and associated piping and valves. F igure 6.5-1 provides a flow diagram of the system. The compressed gas would remain stored on the site for approximately 100 years to allow the Kr-85 to decay to insignificant levels. The minimum volume for the storage system would result if the gas were stored at the highest possible pressure. The practical upper pressure limit for gas storage is 2500 psig. At this pressure, 80,000 sta,dard gas bottles (1.54 cubic feet) would be needed to store the gas. An alternative to extended onsite storage would be to package the gas for

6-?3 offsite disposal. This alternative is discussed in Section 6.9.

At the other end of the spectrum is a large-volume, low pressure storage system. For example, if a container the size of the existing reactor building were constructed, the gas could be stored at 170 psig.

4 The General Public Utilities Corporation (CPU) contracted with MPR Associates to investigate the most practical means for storing the compressed gas (Ref. 21). MPR recommended a low pressure storage system in which the gas would be stored at 340 psig in 36-inch outside-diameter standard-wall pipes. One million cubic feet of storage volume would be required, which would be equivalent to 150,000 linear feet, or 28 miles of pipe. The proposed pipe storage complex is divided into two major sections (high activity and low 6ctivity) to minimize shielding requirements. The high-activity piping section would include 20% of the piping and would contain 90% of the ur-85.

The high-activity section would be segregated into five units to limit Kr-85 releases in the event of leakage and to optielte inherent shielding. Low-acti'.ity pipe units would be placed to the outside of the storage area to act as a shield for the highest activity units in the center. The butiding to nouse the hign-activity piping, the filters, dryers, and gas compressors, would be 260 feet long, 90 feet wide, and 30 feet high. Six inches of concrete shielding around the high-activity piping would be required. The low-activity pipe section would con'ain 80% of the total piping and 10% of the Kr-85.

The building for housing the low-activity piping would le 220 feet long, 160 feet wide,...d 60 feet high. It would require no shielding.

6.5.3 Occupational E>?osure No significant amount of radiation exposure should be incurred by plant personnel during operation of the gas compression system. All system components are relatively simple and should require minimal maintenance during gas processing. Should maintenance be required, most components could be isolated and purged to decrease radiation exposure during repairs. The staff estimates an occupational exposure of aporoximately six person-rems during operation and maintenance.

Periodic maintenance of the long-term storage system is a potential source of occupational exposure. Although a system can be designed for mainterance-free operation, it would be unrealistic to assume that some maintenance would not be necessary during the approximtely 100 years of storage required. The staff estimates that surveil-lance and maintenance during long-term storage would result in an occupational exposure of approximately 42 person rems.

6.5.4 Environmental impact Krypton-85 can be removed f rom the reactor building and stored in pressurized containers with minimal release to the environment. The resulting doses to the public due to the anticipated minor releases would be insignificant.

Although subsequent long-term storage in pressurized containers ensite will nut affect the environment directly, the potential for accidental releases will remain for over 100 years as the stored Kr-85 decays.

6.5.5 Accident Analysis the gas compression process was analyzed for its radiological consequencos following an accidental release of i

compressed gas from the storage system. The radiological consequences of a failure in the feed train were not analyzed since it was assumed that the f eed process would be isolated well before the accidental release approached a magnitude which would equal a release following a storage-system failure. The accidents analyzed therefore, represent the most severe occurrences with raspect to their potential exposure potential at the site bounda ry.

Analyses were performed on accidental releases from several storage configurations.

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6.*4 Assuming the t>epressed gas storage system is segregated into fcur units, postulated unit f ailure with a subsecsent release of 14,250 Curles to the environment in a t.o-hour period would result in a site boundary total-body gamma dose of 5.0 sees and a teta skin oose of 410 sees assuming a conservative I/Q of 6.8 x 10'* sec/m. The 2

total body gamma cose is a small f raction of the limit set forth in 10CFR Part 100 (Ref.15); 10CFR Part 100 does not include a limit for beta skin exposure.

Surma ry The gas compression systee of fers several advantages. The gas cospression system is essentially a "zero release" f

system which could be cperated to decontaminate the reactor-building atmosphere with insignificant environmental tecact. The occupational exposure resulting f rom cperation and long-ters surieillance of the systen is estimated to be 41 person-ress. The major disadvantages of the gas compression system is the extensive time required to build and install the systes (25 to 35 months). The HEC staf f considers this time period unacceptable for the reasons discussed 43 Section 5.0.

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6.6 Cryogenic Processinc Systee 6.6.1 Introduction A potential seams of decontaminating the centaminated reactor-tuilding atmosphere is through the use of a cryogenic precessing systes. The operating principle of the cryogenic processing systes is the condensation of Kr-85 f rom the incoming air by direct contact with liquid nitrogen (boiling point, -195.6*C).

The liquefied (r-85 would be allowed to concentrate and would then be vaporized and transferred to an onsite storage f acility for sutseovent disposition. Use of the liquef action or cryogenic processes has been recommended by various members of the public.

The NEC staf f has evaluated the availability of an esisting cryogenic processing systes (CPS) at a coecercial boiling =ater nuclear power plant to decontaminate the reactor-building atmospoere. The cryogenic systee has never been placed into operation and is teing of fered for sale by its current o=ner tecause of anticipated hich operating costs and the degree of continued maintenance that the unit would require.

Althc9qh the system is available for purchase and use by the licensee, the erection of a new building would be required to hcuse the l

system tecause of toe need to confire anticipated leakage from the CFS. The building.ould te approminately 110 i

feet long by 72 feet.ioe and culd vary in height f roe 20 feet to 35 feet.

l 6.6.2 System Description and Cre*ation l

l It instal ed, the cryogenic systes =0uld connect.ith the reactor build 1rg through the esisting hydrogen-centrol systee. The contaminated air f ree the reactor building would be tramsported tc the cryogenic processing systen in the adjacent building af ter passing through the PEF A filters and charcoal adsorter of the hydrogen control systre.

The cryogenic processing systes consists of three peccessing trairs. The major conconents of each train are tre prefilter, catalytic ecoeciter, af tercooler, and cryogenic treatment subsystes. The three processing trairs are supported by a hydrogen storage system, a liquid-nitregen storage system, a%d a ncble gas storage system. A f!c= diagens of the cryogenic processtng systes is shc.n in Figure 6.6-1.

The cryogenic processing system can process air f rca tre reactor building at a flev rate of approuisately 225 sefa. Af ter passing through the bf A filters and cnarcoal aJscrters cf the hydragen control systee for removal of trace quantitles of at rocrne radic-active particulates, the air f rom the reactor building would be heated in the CPS preScater prior to injection into the CP5 catalytic recordiner for osygen rencval and corresponding volume recuction of the recoeciner ef fluent.

The ef fluent cas f rom the reconoiner would twen be cocted in a de=astream aftercoolee and directed to the cryogenic l

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C-2E treatment subsystem (CTS). The c.ajor components of the CTS consist of two feed compressors, a gas preheater, a i

trace recombiner, an af tercooler, a separator, three prepurif ters, a cooldown heat enchanger, a removal column, a condenser heat erchanger, a phase separator, a decay column, a hydrocarbon conversion unit, and an amDient heater. (A flow diagram of the cryogenic treatment subsystems is shown in Figure 6.6-2.)

The ef fluent gas f rom the CPS af tercooler would enter the suction side of the CTS feed compressors. The feed coepressors would transport the gas through the preheater, trace recombiner and af tercooler for gas heating, removal of trace quantities of omygen, and gas cooling, respectively. Moisture would be removed from the cooled gas in a downstream separator. The gas would then enter the prepurifier for reroval of cartion dioside and any 4

j remaining moisture. The purified gas would then enter the cooldown heat exchanger to reduce the gas temperature to approximately -29'f.

The chilled gas would enter the removal column where the methane and noble gases (essertially Kr-85 and stable krypton, menon, and argon) would be removed by condensation from counterflowing j

liquid nitrogen to collect in a pool at the bottom of the removal column. At periodic intervals, the condensed metnare and noble gas pool would be vaporized and removed from the column via the CPS product compressor and compressed into storage vessels for onsite storage at ambient temperatures. See Section 6.8 for a discussion of i

onsite storage. The licensee estimates that it would take from 20 to 30 months to put the system into operation.

from consultations with construction engineers at Oak Ridge National Laboratories and in the nuclear industry, i

the staff estimates that it would take a minimum of 20 months tc get any CPS operational.

i 6.6.3 Occupational Exposure Of all the alternative systems considered for the cecontamination of the reaci.or building atmosphere, the CPS is the most complex in that it consists of more and varied components than the other systems and is expected to f

require a greater degree of maintenance during operation. In addition, the system operates at positive pressure (65 psig) so leaks must be considered as an anticipated operational occurrence. If leakage from the system occurred downstream of the CTS removal column, that leakage would contain highly concentrated Kr*85 (that is, at least three orders of magnitude higher than in preceding portions of the system). Therefore, the esposure to j

workers operating and maintaining the CPS is anticipated to be greater than that of any of the other treatment l

alternatives. The licensee estimates the exposure to workers due to processing, maintenance, and required surveillance activities during long-ters onsite storage of the kr-85, would be approximately 570 person-ress.

Most (approximately 901) of this estimated exposure would occur because of surveillance activities (inservice j

inspection of components, maintenance, and sampling) associated with the long-tere storage of Kr-85.

The staff, f

however, does not agree with the licensee's estimates of the frequency and dose rates that could be encountered during surveillance activities nor with licensee estimates that exposure to workers would be in the range of 137 to 255 person-ress. The staff's lower estimate is based on the emphasis that would be placed on maintaining inplant exposure ALARA and on the assumption that workers would spend less time in high-dose-rate areas than the licensee has estimated. The licensee agrees that extra steps could be taken during design, engineering, and construction stages to reduce worker exposure; however, they state that such changes would significantly extend l

the 20- to 30-month perlo; estimated for implementation of the CPS. The NRC staff believes that if ALARA concepts are implemented in the int.ial engineering and design efforts for the facility, the schedule would not be signifi-l l

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6.6.4 Environmental Impact t

l The CPS, designed f or a removal ef ficiency of 99.9% is not, therefore, a "Zero-release" system. During the l

estimated 2-1/2 months that would be required to process the reactor-building atmospshere, approximately 60 curies of Kr-85 would be discharged in the purified gas effluent from the system. In addition to this, an unspecified amount of Kr-85 would be discharget 'n the environment due to anticipated leakage f rom the system.

The staff believes that the CPS can be designec > minimize the environmental impact of uncontrolled leakage by

6-27 judicious monitoring and rapid system isolation upon indication of an upset condition. In any event, the staff ostimates that the environmental impact during normal operation cf the CPS =culd be insignificant (i.e., less than 0.01 alliress beta skin dose and 0.0002 millf rems total-body gamma dose, assuming a X/Q of 5 x 10~5 2

sec/m ).

6.6.5 Accident Analysis The CPS was analy2ed for the hypothetical worst-case f ailure of the Kr-85 storage system. This failure assumes the rupture of all gas storage vessels and a corresponding breac. of the secondary storage containment structure.

Under these circumstances, the entire Kr-85 inventory of approximately 57,000 curies is assumed to be released to the environment over a two-hour period. Based on anrual average meteorological conditions, the calculated total-body gamma radiation exposure to a person at the site boundary would be 20 milliress, with a corresponding beta skin dose of 1700 milliress, assuming a X/Q of 6.8 s 10

• sec/m. This calculated total-body dose is a 2

small fraction of the limits set forth in 10CFR Part 100 (Ref. 15). There are no skin dose limits in 10 CFR Part 100.

6.6.6 Air Products and Chemicals, Inc., and MITRE Corp. Systems The CPS discussed in the preceding section was chosen as a typical cryogenic system that is currently available.

This system is designed by Linde Division of the Union Carbide Corporation. Another currently available CPS, which operates by essentially the same principle, is designed by Air Products and Chemicals, Inc. This system also uses the basic two-step process, which consists of hydrogen and oxygen recombination, and then removal and concentration of the radioactive gas by cryogenic distillation.

Yet another CPS was described by the MITRE Corporation. This system proposal, while using the same cryogenic techniques, would include a closed recycle to the reactor building. The proposal states that the system ould also employ several other unique features including a normal krypton makeup feed, and a process combination of air separation plant, krypton distillation column, and molecular sieve filter bed to remove the Ar-85.

The proposed project schedule totals 11 months, which would allow nine months for procurement, f abrication modifica-tions, and installation, and t-o months for the startuo, debugging, system optial2ation, and removal of the e

Kr-85.

However, the schedule dees not censider the need for a r'e building to house the system. The NRC staff, based on the discussion in Section 6.6.2, believes this schedule to te an unrealistically shcri esticate.

Summary The cryogenic system evaluated bere is essentially the same as the other currently available CPS. A difference noted is the addition of a hydrogen supply to the recombiner in the Linde system to further avoid osygen accumula-tion. The PITRE systew, which includes an air-separation technique and a recycle to the reactor cuilding,.ould require additional fabrication, and more importantly, may require proof-testing before finali2ation of a system design.

The primary advantage of each CPS proposed is that the of f site erwironmental irpacts either from operation of the system or f rom worst case accident scenarios are insignificant. Selection of any CPS as the best alternative is not without its disadvantages, however. First, design, construction, housing, and testing the CPS mould result in significant delays in the TMI cleanup effert. From hDC staff consultations with construction engineers at Oak Ridge National Laboratory and in the nuclear industry, we estimate that it would the a minimum of 20 months to get any CPS cperational. Second, based on prior emperience, operation and maintenance of each CPS would te likely to produce a relatively high occupational exposure. Finally, the onsite storage of concentrated quantities of Kr-85 generated by each alternative would require long-term periodic sursellia,ce and =ould accordingly represent a continuing risk to workers on the site, as well as to the public.

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E-20

6. 7 Combination Process and Purge Systems

6. 7.1 Introduction The staff has evaluated the feasibility of combining a krypton-recovery system (charcoal adsorption, gas compression, cryogenic prncessing, or sel(ctive absorption) with one of the building purge alternatives (hydrogen control or reactor-building purge system). This combination method would be performed in two steps.

First, a krypton-recovery system (the primary system) would process and contain approximately 95% of the krypton from the reactor building. Then the remaining krypton (approximately 3,000 curies) would be purged to the environment through either the hydrogen control or reactor-building purge system (the secondary system).

The chief advantage of this alternative is the shortened time period, relative to the alternatives discussed in Sections 6.3-6.6, which would be required to implement it.

This advantage results f rom smaller scale processing system requirements. If a 95% Kr-85 removal ef ficiency is desired with the primary system, approximately six million cubic feet of contaminated air will have to be processed be fore purging could proceed. In order to process this volume within approximately two months (comparable to sinw purge time) the primary system would require a flow capacity of 75-100 scfm.

This, primary system used in combination with purging would require flow or storage capacity (,1f, gas compression is chosen as the primary system) approximately 25-33% of the capacity requirement for f ull-scale krypton-recovery systems described within this assessment.

The staf f has estimated a schedule for making a combination alternative operational. The two primary systems that could be operational in the least time are the cryogenic processing system (CPS) and the selective absorp-tion system (SAS). The staff estimates that the minimum times for a full-scale CPS or 5A5 to be operational are 20 months and 16 months, respectively. The charcoal-adsorption system and gas-compression systems would require a minimum lead time of 24 months for full-scale system availability and would represent a major construction effort. Even scaled-down, charcoal adsorption (e.g., 3000 tons of ref rigerated charcoal) or gas compression (e.g., 7 miles of 35-inch 00 pipe storage) systems represent relatively impractical alternatives compared to the CPS and SAS.

6.7.2

System Description

In the NRC staf f's estimation, a scaled-down CPS wculd consist of one 75-scfm processing train (as opposed to three trains in the full scale system). The remainder of the CPS, including the noble gas storage system, would remain essentially as designed for the full scale system (see Section 5.4.2).

The staff estimates, based on the construction of a small building for a CPS with one processing train, that the lead time for the CPS might be reduced, as compared to full scale, by as much as 4 months. Thus it would still take approximately 16 months to make a small-scale CPS operational and an additional two months to process the first six million cubic feet of contaminated air.

At least another month would be required for purging, assuming summer /f all meteorological conditions (see Section 6.2), to reduce the reactor building concentration of Kr-85 to below maximum permissible concentrations of Kr-85 (that is, less than 1 x 10 5 pCi/cc).

The full-scale SAS described in Section 6.3 would require the capability of processing several hundred standard cubic feet per minute of reactor-building air, whereas, the scaled-down SAS would be required to process from 75 to 100 scfm.

Thus, the scaled-down system could consist of a single train and feed components (dryer, compressor, cold trap, and molecular sieve) and a lower flow capacity absorption column. The requirements for the noble gas storage system would remain unchanged but the overall building requirements would be smaller than needed for the full scale system. The staf f estimates that the lead time for the small scale SAS might be reduced by as much as four months. Thus it would still take a minimum of 12 months to get a small scale SAS operational, followed by several months of system operation and at least one month for subsequent reactor-building purging.

6-31 These estimates for anticipated lead times for scaled-down cyrogenic processing and solvent absorption systems are based on the simplest designs and assume little or no redundancy (for increased reliability) in system com-These estimates also assume minimum standards in regulatory requirements (Ref. 22) for building and ponents.

system quality and seismic classification. Thus the schedules for a combination method do not reflect allowances for regulatory requirements which may be recommended as the result of a detailed staf f review of a licensee proposal for such a method.

6.7.3 Occupational Exposure The occupational exposures that could result from implementation of this alternative range from 115-255 person-res (depending on the selection of either the SAS or CPS as the primary system) and are discussed in Sections 6.3.3 and 6.6.3.

6.7.4 Environmental Impact The environmental dose impact associated with this alternative (assuming 5% of the reactor-building atmospheric inventory of Kr-85 is purged) would be approximately 1/95 (0.01) of the ispact associated with the slow purge alternative discussed in section 6.2.

This would present negligible public health risk (See Section 7.1.)

6.7.5 Accident Analysis The accident analyses described in Sections 6.3.5 and 6.6.5 would apply to this alternative. The resulting total-body and beta skin dose to the maximum exposed individual are estimated to be 20 and 1700 eres, respectively.

Summa ry The staf f's evaluation shows that the' " combined" alternative methcd can reduce the lead time f or system avail-ability by as much as 25%. Nevertheless, the minimum time frame to make this method operational is one year and, for tte reasons outlined in Section 5.0, represents an unacceptable delay in the decontamination of the reactor-building atmosphere.

6.8 Onsite Long-Term Storage of Krypton-85 All alternatives proposed for removing the Kr-85 gas, other than by reactor-building purge or disposal off site (see Section 6.9), require provisions for a long-tere storage facility on site (for approximately 100 years to allow for radioactive decay).

See Section 6.9 for a detailed discussion of the trans-portation and offsite disposal of radioactive gases.

The existing technology for storing Kr-85 is limited. Table 6.8-1 provides an assessment of different storage techniques.

land burial is a common disposal method at the conmercial low-level waste facilities, the NRC Although shallow staff is opposed to bu ~

of any radioactive waste at Three Mile Island because of the potential for subsequent release to the environment. Thus onsite gas storage in an engineered facility remains as the only practical alternative, even though this type of storage has not been perfected, for example, container Corrosion is a

Also, major problem that can be caused by collected gas impurities such as oxygen or nitrogen oxide, and water.

rubidium, the decay product of Kr-85, say combine with oxygen to form Rb 0.

The long-term corrosion effects of 2

Rb 0 in pressurized storage containers of Kr-85 are not known.

Thus further study and staff evaluation would be 2

necessary if a Kr-85 disposal method were chosen that required long-term storage.

Table 6.8-1.

Comparison of Krypton-85 Containment Techniques

• Technique Development status Advantages Disadvantages Low pressure tanks Feasibility studies performed; Low pressures with low peak Very large storage volume; ozone no field tests probability removal required; radiolytic product corrosion unknown High pressure cylinders Used for shipment at ICPP; low-storage volumes; long Long-term corrosion unknown; high no long-term tests technical background pressures increase probability of massive release; secondary containment required Adsorption on charcoal Development data completed; Reduces vapor pressures large storage volume; fire short-term operation of containers and explosion hazard Encapsulation Laboratory studies only Reduces vapor pressures of Effects of radiation, temperature, (include solid partly completed centainers; provides and corrosion need extensive study; matrix entrapment primary containment process technically difficult e.g., clathrates)

Engineered storage Cost and feasibility studies Protection from environment, Delay in IMI cleanup g

facility continuing; r.o field earthquakes, and gas leaks; experience secondary containment and recovery of leaked gases 3Adapted from T. R. Pinchbacks, " Materials Screening Test for the Krypton-85 Storage Development Program, "tG and G, CR EY-76 c-01-1570, January 19, 1979.

I 6-33 6.9 Transportation and Offsite Disposal 6.9.1 Discussion The implementation of the Cryogenic Processing System alternative, Selective Absorption Process System alter-native, or Gas Compression System alternative (using high pressure standard gas cylinders) would result in contained inventories (57,000 Ci) of Kr-85 which would be stored onsite to permit radioactive decay. Based on the half-life of 10.7 years for Kr-85, it would take approximately 100 years for the krypton to decay to insignificant levels. An alternative approach to extended storage of the gas at THI would be to transfer the gas to DOT and NRC approved containers for transportation and offsite disposal.

The staff has considered several alternatives of disposing of the Kr-85 at an offsite location. The alternatives include transport to a commercial low level waste burial ground (for burial) and transport to a remote location (e.g., a desert) for release to the environment.

6.7.2 Environmental Impact There are three commercial low-level waste burial grounds currently in operation, located in Barnwell, South Carolina; Beatty, Nevada; and Richland, Washington. However, the State of South Carolina has imposed a ban on shipments of waste from THI Unit 2, leaving only the two Western sites as potential receipients of gas-filled containers of Kr-85 from TMI. Each site has different criteria for acceptance and burial of radioactive gases in Federally approved containers. The Richland, Washinoton site is licensed to accept pressurized containers (up to 1.5 atmospheres absolute) of gases containing not more than 100 curies per container. The containers must also be buried individually and located at least 10 feet from neigboring containers. Given the site restrictions for burial of radoactive gases at Richland, the inventory of Kr-85 from TMI would require approx-imately an acre and a half of burial space.

The site in Beatty, Nevada is licensed to accept gas containers that are pressurized up to one atmosphere (absolute) and limited to 1000 curies or less. Gas containers containing f rom 100 to 1000 curies must be surrounded by at least 6 inches of concrete on all sides.

It should be noted that transportation of radioactive gases for disposal in commercial shallow land burial sites has not been a common practice in the U.S.

Given the burial site limitations f or container pressure and curie content, and the required use of DOT and NRC approved shipping containers, the number of required containers for transporting 57,000 Ci of Kr-85 is potentially high. Under ideal conditions, a minimum of 57 and 570 containers would be required for acceptance at Beatty and Richland, respectively.

The environmental impact resulting from the burial of 57,000 Ci of Kr-85 would essentially be the population exposure incurred by the workers who would be required to package the gas at TMI, handle the gas shipping containers, transport the gas to a low level waste burial site and handle the gas containers at the burial site.

The packaging and transportation of the Kr-85 gas would De conducted in accordance with appropriate DCT and hRC regulations. The atimated exposure resulting from these operations would range from 8 to 24 person-rems. The corresponding populaticn exposure to members of the general public is negligible by comparison because of limited contact of the waste containers to the general public during transportation. In addition, the staff assumed that the population dose due to subsequent release (from corrosion of the containers in the ground) of the total inventory of Kr-85 gas is also negligible. The asst.mption is based on the minimal environmental dose impact af a release of 57,000 curies of Kr-85 (see Section 6.2) and low population density in the vicinity

't the bud al site.

6-34 The alternative to offsite burial is transportation to a remote location for controlled release to the environ-ment. This alternative presupposes that a suitable facility would be constructed to effect a controlled release at the remote site. This alternative also assumes that there will be a negligible population dose to the public following release for the reasons elaborated above. Because the same basic operations (i.e., oackaging, handling at TMI, transportation to a remote location, and nandling at the remote site) and limitations (i.e., DOT and NRC packaging and transportation regulations) on tSie alternative apply to the operations for the burial alternative.

l the expected population dose is the same, namely, 8 to 24 person-rem. Although burial or release of the radioactive krypton of a remote site could be accomplished, the NRC staf f believes this probably would not be acceptable to local officials and residents.

6.9.2 Summa ry The environmental dose impacts resulting from the operations associated with transportation and offsite disposal would be in addition to the exposures incurred during the decontamination (i.e., during process operation) of the reactor building atmosphere but would not include the euposure incurred for the surveillance required during extended storage.

Although the environmental dose impact resulting from transportation and offsite disposal of the packaged Kr-85 s

is Megligible, the NRC staff does not recommend this course of action for the following reasons. This course would presuppose the selection of a reactor building atmosphere decontamination alternative which would result in a delay of the entire TMI cleanup effort, Purging, as a method of decontamination, could be accomplished quickly with negligible public health consequences (see Section 7.0).

I 1

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Health Effects 7.1 Physical 7.1.1 Summary and Conclusions The NRC staff has determined that there would be negligible physical public health risks associated with the use of any alternative evaluated in this assessment, eFCept the "no action" alternative. For the staff's proposed purging alternative in particular, this determination has been supported by others, including the U.S. Environmental Protection Agency, the U.S. Department of Health, Education, and Welfare and two groups of independent scientists reporting to the Governor of Pennsylvania. The Union of Concerned Scientists reported that, based on " current evidence of effects of whole body radiation on human populations,

..no health eff.'*s would be anticipated as a result of the ' ground release' venting" (Ref. 3).

The National Council on Radiat'an Prctection and Measurements (NCRP) in their report to the Governor, noted that " exposures likely to be received as a result of venting are no valid bases for concern with respect u health effects" (Ref. 23). In the hkC staff's judgment, there is, then, no physical public health basis for eliminating the purge alternative.

Additionally it should be noted that, based on the relatively greater radiosensitivity of humans, there would be no edverse impact on plants or animals following purging.

7.1. 2 Discussion The NRC dose model for Kr-85 and other noble gases released at the time of the accident is based on present day state-of-the-art dosimetric models. Noble gases have no significant food pathway involvement or modes of exposure other than from immersion in a cloud of the gas. The NRC Kr-85 dose model is in gaod a';.eement with estimates provided by other groups. The National Council on Radiation Protection and Measuremeits provides a consensus of the risks of Kr-85 exposure in Krypton-85 in the Atmosphere--Accumulation, Biologica# S4nificance, and Control Technology (hereafter NCRP Report 44) (Def. 24). Much of the basic information about Kr-85 in this section is derived from NCRP Report 44.

Krypton-85 is a radioactive isotope produced by the fission of several heavy isotopes, stich as uranium-235, uranium-238, an:1 plutonium-239. Most of the Kr-85 in the TMI-2 reactor building resulted from the fission of uranium-235 priar to the accident. Krypton is one element in the series of noble gases that include, in order of increasing atomic mass, helium, neon, argon, krypton, xenon, and radon. These gases are colorless, tasteless, and do not undergo chemical reactions with other molecules in living tissue. Krypton-85 has a 10.7 year radiological half-life and emits beta particles by two different decays. Beta emission is not followed by emission of a. gamma ray for 99.6% of this decay process.

People are continuously exposed to Kr-85 which is normally contained in the world's atmosphere. In the past krypton has been released into the atmosphere during nuclear weapons tests. In addition, krypton has and continues to be released to the atmosphere from nuclear fuel reprocessing plants throughout the world. As a result of these releases, background levels of krypton throughout the earth's atmosphere are readily detectable with suitable irstruments. In the TMI hea, for example, the U.S. Environmental Protection Agency has measured 3

normal background concentrations to be about 30 pCi/m. This cnncentration results in annual Kr-85 background skin and total-body doses of about 0.00004 and 0.0000005 mrem respectively to all members of the public. This compares to an aserage annual total-body background dose (from sources other than medical) of about 100 mrem in the U.S.

Medical and dental exposures normally account for another 100 mrem per year to individuals in this country.

Krypton-85 has low blood solubility and high lipid (fat) solubility, but diffuses rapidly in tissue to reach concentrations proportional to those in the surrounding 3(r a condition ref erred to as an equilibrium concen-

'tration. NCRP estimates that the equilibrium concentration of Kr-85 in body tissues (pCi/g) relative to the

7-2 surrounding air (pCi/cm ) is as follows: (1) separable fatty tissue, f.uch as Dreasts, tnigns, waistlines and 3

around some body organs-41% of the concentration in air, (2) skeleton-13% of the concentration in air, (3) soft tissues (5 :h as organs, muscles, brain, etc.), -8.3% of tne concentraticn in air.

Considering the dose from beta ps.

.hes and gamaa rays (plus their resulting radiations, such as bremstrahlung*) both f rom around and inside a person, the skin is the organ that receives the highest numerical dose. followed by lung and bone tissue. However, as noted in NCRP Report 44, the skin is one of the least susceptible tiisues to radiogenic Furthermore, while any cancer is potentially f atal, most skin cancers lend themselves to successf ul cancer.

treatment.

The 1973 draft report of the Conmittee on the Biological Effects of Ionizing Radiation (National Academy of Science) provides a tentative estimate of risk of radiogenic skin cancer (Ref. 25).

That model would indicate that the risk of inducing a f atal radiogenic skin cancer is less than 1% of the risk of death f rom other cancers resulting f rom totil-body irradiation (per unit of dose). As a result, the NRC staff concludes that the total-body dosc is critical for determination of cancer mortality risk for estimating genetic risk for both sexes.

This will be discussed in mnre detail later in this section.

The NRC health effects model was developed in 1975 f or the Reactor Saf ety Study by a 13-member advisory group, (ttree of whose members were also members of the 1972 National Acade?y of Sciences Committee on the Biological Ef fects of Ionizing Radiation (BEIR) (Ref. 26).

The advisory group included six physicians, ore veterinarian, and six life scientists. Two members were from the University of Pittsburgh School of Public Health.

The NRC health effects model is shown in Figure 7.1 in graphic form.

This model, which uses observed estimates fecm the 1972 NA5/EEIR Report (Ref. 27), assumes that, following a radiation dose, there is a latent period during which no cancers occur. The latent peric is variable, and is assumed to be dependent only on the speci f ic type of cancer. *

• Following the latent period there will a period in which cancers will be observed (plateau).

Using the total-body dose estimates f or the alternatives shewn in Table 1.1 and the NRC cancer mortality risk estimate of 135 deaths per million person-rem, the potential cancer deaths were calculated. The total poteritial cancer mortality to both the 50-mile population surrounding TMI-2 and to plant workers is estimated to range from a minimum of 0.0003 (purge option) to a maximum of 0.034 (cryogenic option).***

Almost all of that risk would be borne by workers esposed at the plant (purge = 0.0002, cryogenic = 0.034).

The carcer mortality risk among the general population within 50 miles resulting f rom the purge option would bd**i6UUT"O.0Iai.

The mauimam potential lifetime-individual risk of cancer mortality would accrue to a fetus that received the minimum estimated dose of 0.2 mrem.

Using 300 deaths per million person-rems frcm Table 7.

the excess cancer-mortality risk for this scenario would be six chances in 100,000,000 (0.00000006) compe-ed to a current normal lifetime espectancy (,f one chance in five (0.2) from all types J' cancers. Risks for al; other age groups world be e'en lower than this extremely small value.

v Using the total body dose estimates for the options shown in Table 1.1, and the NRC Genetic effect rist estimate of 260 cases per millico person-rem the potential geretic effects per generation were calculated. The total

• A type of u-ray.

• • Anim31 studies indicate that the latert period generally increases with decreasirg dose.

• • • EPA, in an April 11, 1380 letter to NRC, (Ref. 28) independent y estimated 0.00022 and 0.057, respectively.

These values represent close agreement with NRC estimates.

i Kw Uz<

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LATENT w

9 PERIOD

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t SINGLE DOSE OF RADI ATION TIME Figure 7.1 Basic Model for Latent Cancer Fatalities

7-4 potential for genetic ef fects in plant workers and the 50-mile population surrounding TMI-2 is estimated to range from a mininca of 0.0005 (purge option) to a manieus of 0.066 (cryogenic option). Almost all the risk would be borne by future descendants of =crkers at the plant (purge = 0.0003, cryogenic = 0.C66).

The maxieus genetic risk to future descendants of any offsite seeiber of the public would be five chances in 100,000,000 (0.00000005) compared to the current expectation of a normally occurring genetic effect at a rate between one and five chances in 100 (.01 to.05).

Recent cancer statistics indicate that more then 14 persons per 10,000 persons =111 contract skin cancer each year (calculated f rom Ref. 29). Thus, the typicai risk of occurrence per lifetire is about 11%. Most of these cancers occur on the f ace, neck, arms, and hands due to esposure to the ultraviolet (tN) rays from the su%

Since most sCn cancers are not f atal, erst are unrepor ted in cancer registries. Estimates indicate more inan 300,000 new cas's of skin cancer occured in the U.S. (population of 220 million) in 1979 (Ref. 29).

hc=ever, of those cases reported, there were 5,900 deaths. Of those that died, 4,300 (out of 13,600 cases) were from nelancaas," and 1,600 (out of acre than 300,000) =ere f rca other types of skin cancer. Therefore, the acetality rates were about 30% f or melanosas and less than 0.5% fcr non-selanosas. The overall lifetfee sortality risk of all types of skin cancer is currently less than 7 chances per 1,000 persons (that is, about 1.5% of the total risk of cancer scrtality).

T'e 1979 drat EEIR report indicates on the erder of one e of skin cancer.ill develep per year per sillien person res of low LET radiation (such as emitted by Kr-85) (Ref. 25). Although no studies have indicated a definite 'Xrease % eelancsas as a result of radiation exposure, it was assured for this assessrent that the utality (not incidence) free radiegenic skin cancers is the same as for naturally occurring li f e t h s, ris*

spontaneous s6 in s *ncers.

That assusrotion implies that the lifetire sortality risk is on the order of one death per eillion person-res (skin).

Bau d on this assumption, the lifetime cancer mortality risk from a total body dose is at least 135 times greater than a comparaDie skin dese."

The beta dose to the exposed skin f rom Kr-85 is about 20 times greater tr e tre total body gamma dose f or unprotected verters of tre public. This isplies that the cancer scrtality risk f rom Kr-85 atin doses to the public would te on the order of 60% of the cancer sortality risk f rca the Kr-85 t >tal body de:e.

fherefore a skin dose of 11 aree to an individua' (purge cption) would te predicted to cause less than ore j

(about 0.000006) additional skin cancer sortality asong the 50-mile ocpulation of 2.2 millien pecple. This coreares with 4,000 espected deaths f rom skin cancer f rom other causes (primarily sunlight), and over 400.CCC total expected cancer deaths in the area regardless of whether the Kr-85 is released or not.

Using the estiestes of averace life-shortening in Table 7.1, and the dose estinates in Table 1.1, it is possible to estiente the average loss-of-life expectancy associated with latect ca.cer ecrtality. The namisun li'c secrtening *culd result free irradiatien of a fetus in the ecther's cit.

Using 7.2 days per rez. the manicas dose of 0.? eres.ould result in a statistically average risk of 2.1 sin tes.

Risas to all other age groups uculd be even less.

helanosas are a r'are t,ut da gerous skin cancer.

"135 cancer deaths /10pperson-ree (total beed, g" ersen i I cancer oeatns/10 res (so n)

7-5 Table 7.1 Summary of Age Specific Cancer Mortility Risk Estimators and Associated Life-Shortening Potential Cancer Mortality Average Life-Shortening Age Group per 108 Person-Rem

• per Person-Rem

• Totals Hours Total Days In-Utero 150 Leukemias 300 87

7. 2 150 All others 0-0.99 years 50 Leukemias 93 25

1. 5 43 All others 1-10 years 50 Leukemias 150 24

1. 5 55 All others 11-20 years 25 Leukemias 196 10 2.0 171 All others 12 20-70 years 23 Leukemias 131 5

0.63 108 All others 10 All ages 28 Leukemias 135 10 1.2 107 All others 18 afor a population composed only of that age group.

A summary of other common competing risks of mortality comparable te the maximum total-body dose (purge option) is shown in Table 7.2.

Table 7.2.

Summary of Lifetime Risks of Mortality Numerically Equivalent to 0.2 mrem Type of Activity Equivalent Mortality Riska Causes of Deaths Cigarette Smoking Inhaling of few puffs lung cancer and cardiovascular diseases Drinking A few sips of wine cirrhosis of the liver Automobile driving three miles accidental death Commercial flying 14 miles accidental death Canoeing 20 seconds drowning Being a man aged 60 ene minute all causes of death at age 60 3 5ir Edward Pochin, "The Acceptance of Risk," (Ref. 30).

The staf f has compared the osse conversion f actors for the noble gases released during the TMI-2 accident with that for Kr-85.

It can be shown that it would require the release of approximately 500 millien Curies of Kr-85 under the same exposure conditions that existed during the accident to result in population doses comparable to those received f rom the 10 million curies of xenon and krypton radioisotopes actually released during the accident. Stated another way, the release of $7,000 Curies of Kr-85 under acciderat exposure conditions would have resulted in only about 0.01% of the population dose which was estimated to have resulted from the accioent.

+. -

7-6 It should be noted that even the relatively large amounts of noble gases (including Kr-85) released during the accident were determined to present little risk to the public by the Kemeney Comission (Ref. 31), Rogovin Report (Ref. 32), and NRC staff (Ref. 17).

Comparison with Other Radiological Risks A sumary of other common competing risks of mortality comparable to the maximum total-body dose (purge option) is shown in Ta'se 7.3.

Table 7.3.

Sumary of Latent Radiogenic Cancer Risks Comparable to 0.2 mrem Type of Exposure Equivalent Radiological Risk Source of Dose Comercial Subsonic 29 minute flight at 30,000 ft.

cosmic rays jet travel (Ref. 33)

Comercial supers 3nic 18 minute flight at 60,000 ft.

cosmic rays jet travel (Ref. 33)

Living in Denver, Colorado one day cosmic ray and (as opposed to Middletown) terrestrial radia-tion (Ref. 34)

Moving to a location about one year cosmic rays 20' higher in elevation (Ref. 34) than Middletown (same type of home)

Sleeping with about eight months naturally occurring K-40 another person at eight hours / day gamma rays (Ref. 35)

Living at the site about two weeks natural radioactivity boundary of a coal-emitted by coal f' red plant combustion (Ref. 36)

Living in a tight, about one night increased levels erargy efficient house of Rn-222' 8

Assumes (a) one extra 0.001 pCi of Rn-222 per m of room air (actual measurements have shown up to 8

0.03 pCi of Rn-222/m )* and 50% equilibrium for radon progeny, (b) 2 x 4

• lung-cancer deaths per working-level month (WLM), and (b) being at home 100 hours0.00116 days <br />0.0278 hours <br />1.653439e-4 weeks <br />3.805e-5 months <br /> per week (or approximately 15 hours1.736111e-4 days <br />0.00417 hours <br />2.480159e-5 weeks <br />5.7075e-6 months <br /> per day). Therefore, (2 x 20 4 lung cancer deaths) * (0.005 WL @ S0 percent equil) * (100 hrs /wk)**

(

WLM

^)

(

0.001 pCi/m

)

( 40 hrs /wk) 3 (12 months) 30 deaths I

(

yr

) million people or: 3 chances in 100,000 compare with (0.0002 rem) x (1.35 x 10

• cancer deaths /(ram)

= 3 chances in 100,000,000 f.e., about 1,000 times greater risk for an energy ef ficient house

. (365 dm), (24 hrs) 8.8 hrs (a good night's sleep)

( 1000

)

(day)

[

'Hallowel, et al., invited paper,1979 Heeting of the American Nuclear Society, San Francisco, CA.

i

• • Correction for dif ferences in exposure periods at home compared with uranium miners.

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7-7 Based on the cancer statistics just discussed, about 11 out of every 100 persons will develop a skin cancer during their lifetimes (Ref. 24).

It is assumed'that most of the current risk is due to exposure of the skin to ultraviolet rays from the sun.

Since the current risk of skin melanomas among black persons is only about 18% that of,hite persons, it was assumed the difference is largely due to greater protection of the garminal layer of skin from UV by melanin pigments in the epidermis of black people. If it is conservatively assumed that the dif ference is due only to UV irradiation, then about 80% of all skin cancers in the U.S. would be due to exposure to the sun (i.e., about 9 cases per hundred persons).

Comparing these figures with the 1979 draf t BEIR estimate of about one case per year per million person rem (Ref. 25) indicates that background radiation accounts for less than 1% of the expected skin cancers.* This is further evidence that the skin is relatively insensitive to ionizing radiation.

Some people (for example, f armers, commercial fisherman) spend as much as a third of their lives exposed to the direct rays of the sun (primarily head, neck, arms, and hands). Others (e.g., miners, u ' ice workers, etc.) may spend less than one-tenth of each adult work day in the sun.

'It was assumed here that the average person spends about 3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> per day (including weekends, childhood and retirement years) in the sun.

The average risk of UV induced skin cancer is therefore:

0.09 skin cancers r 1.1 x 10 8 skin cancers / hour of s"n.

(3 hrs / day)(365 days /yr)(75 yrs / person),

Using the 1979 draft BEIR estimate of 10 8 cases of radiogenic skin cancer per year per person-rem yields on estimated equivalence of 0.045 hours5.208333e-4 days <br />0.0125 hours <br />7.440476e-5 weeks <br />1.71225e-5 months <br /> of exposure to sunlight and one millirem of skin dose (Ref. 25).**

Using the maximum individual skin dose estimated by NRC (11 mrem), the added average risk of skin cancer would be equivalent to spending 30 minutes in the sun.

The average individual in the population would have an added risk of skin cancer equal to about a half-second of exposure to the sun's rays.

' impected: 0.11 x 2.2 x 10' = 24 mil' ion cases of skin cancer. From 0.1 rem /yr of background radiation:

(TTietime ) (0.1 mm) (2.2 x 10" persons) (s50 years at risk) (I *

)

Y"d

• " C ' "C "'

year person rem x M

= 8 x 104 skin cancers or, 8 x

< 0.4% of total expected x 9

• • 1x 10 8 skin cancers /yr per person-rem) (50 years at risk) = 45 hours5.208333e-4 days <br />0.0125 hours <br />7.440476e-5 weeks <br />1.71225e-5 months <br /> 1.1 x 10 " skin cancers / hour of sun person-rem

t 7-8

7. 2 Psycrolodcal Stress 7.2.1 Coxlusion The staf f conclu.es trat tr.e psy.tclogical stress resultirq f ree atmos;teric purgiN.f11 te less seesee tr.49 f rom any of tre otrer scontamin.ation alteenatises. Purging the reacter t-cilding is tre cuickest cf tre cecontamination alteo ntNs and mill, trerefore, result in stress cf shcrter d,. ration relative to t*e ctrer al terr.ati v es.

5,x h..

.stes -3J14 use consiceeably acre coecles equi;eent and peccesses at =culd th rety prolor.g tre uncertainties aN associated stress over tPe possibility cf accidertal releases. In a Mitien, resoving K--65 from the reacter twilding may te perceived as a crwial first ste; in ; cgress tcward cierall decer.tatination of T*f -2 and elisir.ation cf the pote9tial fcr f uture ciset.ctica f ree that unit.

The staff ackrc= ledges t%at tP4 carging reccamendation say be urpcpular to a segment of tPe 1ccal peculatice aM pertehed as further evidence of %C thse9sitivity tc treir a: pee'sensices. %caet*eless, the staf f telieves that, given the atsence of raciological risk from t.*e ;u ging c; tion, in tre 10 % r.S. getect decentaisir.stica r

of the reactor taildirq atsosphere =ill substantially alleviate psyc*clogical steess d e to a coveen cuer urplanaec radiological releases f rom the f acility aN cm. cts ados.t tre atility aw cecistveress cf tre %8C to take af firsative nessu es.

7.2.2 Discussion A nueer of stucies rec. cried psychological distress as =idespetad in the ;<calatic+. 4th-4 TPeee Mile Islam w recuer, sone level cf psycrological dist*ess cer.tir5es tc De at tV time of the accicent (Ref s. 31, 37-19).

e assoctited =ith marious issses surre. Ming tPe current at future status of t*e f acility (&ef s. M. 39).

In particular, anniety is higa aseg sove meters cf tre pcpulatien at the pec.s;*ct cf ae)T'tonM releases tc t*e ea.iroerent f rom the n.mit 2 reacter tuilding (Ee' 31). Eeccqnizing this f act, t'.e staf f has epiceed tre pcssible dif fe*eet le.els aad cearacteristics of psycaclegical stress associated with each c' t** ceccetani-natice alteenatives. In reaching coa.clusicrs c*n the eef atise csyc*tolcgical iscsacts anc g t*.e alter *4 tines.

t*e staf f considered sese al so.eces, ircluding studies of psyc*clegical stress 4M csycf.otegical secwecca (cf rele' acce.ere studies, ty es;*rts en psy--Mcgical stress tief s. 31, after effect) c' disastees. Of particular 37-41), that specifically SM *essed coNitfoes in t><

Three wif e IslaN area at am e.al:,,atic, cf r e.li c c eavre n t s. IFe " man Oesign Grcwc. assisted tPe staf f's e.aluaticn.

The *aa-Cesi;7 Cec # s pri cipal acceen are af filiated with the Ce: setae-t of w+ dical Psychcicqy, U7ifcened Service Uni.ersity c' tre Healt*, Seevices.

Based on cens Itatices with psyc clogists tPe staf f ccScludes tPat tre pu girg alte*Mti e *as less pcteettal r

for creating teaq-teen psychclogical stress than t*cte alterratives =^ich take ic ger 1 t ec l enest Psy Oological steels is a ccacies set of rental, teMeicral ad ;*ysiclogicai ; ecomea.3, a *es; case ;atteen resultiaq f rie a persM's a;praissi cf sn e.ent cr situatien tra* trecaters soFe kid cf 44 ger.

• -a*1r, c*

loss.

7*e se patterr.s include mcreased ;*ysical aM psycNicgical accusal, aM a seare f ce altereati=es te ccse =sth er redoce darger er loss If a percel.ed tregat is rci ccrtectied er rea,ced, a persco affected may suf f er pspNIcgical as well as p% sical strain a*4 t*keir ccesehe <es.

Stress 8-ty be i-O ed Cy a wide variety of situatices ce ene**s.

Tne level cf s.ress is gemeeally -asssciated.it*: a ;ees cC s pe r*eptice cf

' ti!c mest peescas

• ave t*e ca;4 city to eecceer coite well f ros acwtc stress the severity of less cr *ars.

u Caned by a specific event, a small reeceatage cf a pchlation say enterience lasti g ;*)sicai 4Wce escticaal e' f ec t s f ree t*e s ame e v e a t.

5,x h c r ec9 ic s tre s s, *c=es er. is usua?lp related *c e etts.*:ich. ca.se 5t ess for Ic q periocs.

=*iile c'*cnic ccesehenses cf s crt-ters eieets tPat ca.ase stress a*e still a$ cce 1 cs,ei t i ca.

the 10*g aN s%cet-te-n sytc tows aee sistl ae.

e1rc ti cm) tensics, ccqaiti ve irc air 1he-t, s ad scea tic c 'ec l ai ets.

the ps)c clogical steess assCCif ted wit

• a*Resc*eric dece'taWi atic* cf 1*e N "2 reactCe The CCnCl4isicas en a

buildf rq are, in part, based co t* ee saluable s* Aies that ha.c ecceived vice distriti.:tio^.

T**y are OcMrer=vN's tecMical repet fjef. 3 7) f e r t*e 4.eee y Corpri s s icn, **cs.ts' st4f (Eef 33)

• • e t*e fearsfloaaia

___ -. ~_-

i i

4 7-9 Department of Health, and Flynn's preliminary report (Ref. 39) on the TMI telepnone survey of resioents around IMI f or the NRC.

Each of these studies attempts to answer in part the question, "What are the mental health a

consequences of the accident?" Each examined different indicators of psychological stress, some of which are reports by individuals on their physical or mental well-being. These reports, nevertheless, agree that there was an increase of psychological stress initially following the accident that had diminished by mid-summer, 1979. They felt that this drop indicated that stress linked with the accident was acute or event specific.

Houts.(Ref. 38) and others (Ref s. 37-39), however, find several indicators of stress that remain high even aft.

the accident. The continuing stress seems related to two issues: future decontamination plans for TMI-2, and a distrust of those responsible for these activites. These two interrelated issues represent a new source of stress that continues beyond the accident. The Kemeny Commission suggests that stress was induced and exacerbated by a lack of confidence in those currently in charge of TMI operations. These stresses are seen to be acute. In addition, the Commission

• proposes that any increase in the incidence of long-term i

mental or physical health t oblems caused by the accident will be insignificant. The effects of stresses in the post-accident period are uncertain; however, several researchers (Refs. 40, 41) foresee no long-term stress-related health proble15.

As a result of the above review, the staf f suggests that current distrust of authority in a percen tage of the population will be an important f actor in the community's evaluation of any decontaminatic:, gian (Ref s. 37-39).

Such distrust can heighten a person's or a community's perception of potential danger and their feelings of lack of antrol, as was found in several studies (Refs. 38, 39).

These feelings may cause some TMI resideits j

to resist any agency sponsored action. The level and duration of stress is determined in part by how long the source of the stress is present and by how people perceive their ability to cope with it.

Perceived fcelings of lack of control found in the TMI community are enhanced by previous conflicting and inconsistent stances 1

made by the major organizations involved during and after the accident (Ref. 31).

In addition to stress related to distrust of authority, there is the issue of duration of st.rss and related stressors. Some stress will exist in the TMI area as long as decontamination is

=yed and agencies are seen

.e by some to lack credibility and are perceived as insensitive to the area's welf are.

Acute stress for many residents could be elevated by the purging, but should diminish thereafter.

Thus, three sources of s, cess seem pertinent to IMI-2 decontamination: (1) the duration of reactor building atmosphere decontamination 1

operations; (2) the immediate fears purging arouses; and (3) distrust of authorities responsible for decontamination activities.

I 1

i A

i 6

-._,cc...,_.,

,__,-_,-,,_.---~,,.m.y,--

,_m mm,,,,

,,,...--v_,v.,r,,,m.-..--

8-1 8.0 Radiological Environmental Monitoeing Program 8.1 Introduction The radiological environmental monitoring around the TMI site and nearby communities during decontamination of the reactor building atmosphere would be perfonied by (1) the U.S. Environmertal Protection Agency (EPA), (2) The Commonwealth of Pennsylvania, (3) the U.S. Dep&rtment of Energy, (4) the Nuclear Regulatory Commission, and (5)

Metropolitan Edison Company (the licensee).

Ert. program is summarized in the following subparagraphs; a more complete description is given in the Er A report, "Long-Term Environmental Radiation Surveillance Plan for Three Mile Island," March 17, 1980.

8.2 U. 5. Environmental Protection Agency (EPA) Radiological Monitoring Program EPA has been designated by the Executive Of fice of the President as the lead Federal Agency for conducting a com-prehensive long-term environmental radiation surveillance program as a follow up to the accident at TMI-2.

EPA has recently incorporated a separate section in their surveillance plan detailing the monitoring program to be implemented should the NRC staff proposal to purge the reactor building atmosphere be approveo. EPA operates a network of 18 continuous air-monitoring stations at radial distances ranging from 0.5 mile to 7 miles from TMI.

Seven miles was established as the point well beyond that which EPA expects to detect any emissions from TMI-2.

Each station includes an air sampler, a gamma rate recorder, and three TLDs. A list of sampling locations is shown in Table 8.1.

These stations constitute EPA's baseline, long-term monitoring program. The air sampler units sample at approximately 2 cfm and the samples are collected from each station and analyzed typically three times per week.

All samples are analyzed by gamma spectroscopy at EPA's Harrisburg Laboratory using a Ge(Li) detector with a lower Ilmit of detection for cesium-137 or iodine-131 of approximately 25 pCi (0.15 pCi/m3 for a 48-hour sample).

Each monitoring station is equipped with a ganma rate recorder for measuring and recording external exposure.

Recorder charts are read on the same schedule used for air sample collection and the charts are removed weekly for review and storage at EPA's laboratory in Las Vegas, Nevada.

Thermoluminescent dosimeters have been placed at each monitoring station and at 0.25 mile intervals along roads immediately parallel to the Susquehanna River near TMI out to a distance of about 2.5 miles from the reactor.

TLDs have also been placed on the islands located 0.5 miles to 1.5 miles west of the reactor site (Shelley, Hill, Henry, Kohr and Beech Islands). These dosimeters are read quarterly.

In addition to the above, a weekly compressed gas sample is taken at the Observation Center and sent to EPA Las Vegas for a determination of krypton and xenon.

The EPA's base long-term program discussed above will continue and will be augmented in the following manner if purging of krypton is approved.

A monitoring program consisting of survey meter and ion chamber measurements, collection of compressed air samples for Kr-85 analysis and intensified collection of samples f rom routine air monitoring stations will be implemented.

-g

8-2 A.

Nbile Nnitorirq - su vey meter and ico-chaeoer e

e A einin.e of th*ee ectile radiation sonitoring personael edi;Ced =ith suewey instrunents aM o*e Icw range p*essurized ico-cnasc.er mill be positioned in the predicted c~=%ind trajectory du*ing p=*girq.

Netterfrg perso-nrel =ll! be cre n f ree other Federal a;eNies as well as f ree the ESA in ceder to provide 24 rcer cov e ra ge.

In aMition to making rad atin acasueenents t* req *c=t the dy, perscarel will te pee;ared to collect ccepressed air sa=ples based cm those seasureseats.

B.

trypton-85 Sae011r.g Four coecressed air sasoling units mill be positic-red at fined ocations for tre collection of meetly sancies.

The units will be placed at WiMietc=n, the Ctservation Center, Baiatridge aM Goldsbere in ceder to prc<ise represe*tative coverag+ =115 enchasis in the peedowirmaat wird directicas. Sarpileg will te co%cted f ce cee to two meets pricr to purghg to proeide ta:tground data for t*-e I"! 4*ea.

Sa*cles roati*ely cc11ected in

%ev ada =ill prov*de an iMication cf =ce'omice ascie-t tr-85 leiels for ccec3*ative puercses. In aMitice three concressed air sancli-g units will te deoloyed with tre accile acnitcr$. A ainiu of ese sancie will be ctifected each day (at the credictsd o*f site 1xation of s.auiem pluw coventratica). Additica.at sancies will te collected, =^el necessary, Sased ucon survey neter asd ion-cMste* data.

All sancies =ill be analyzed at tre EDA laboeatory facilitie* in Macristueg.

C.

Yrit ius Mcnitc* ing O'e solecular sieve saerfee mill be c;erated at the Ctse%atice Center for collection cf at.ncspPeric acisture f or tritius 4* nlysis. Analyses will te cerfereed at the EPA lateratery f acility ie earristu s.

e O.

9 utive Air %:mitacir; %etmock.

0

}n order to seeif y that ro e&di3%clic,5 Ot*er than Er-65 a*e released to t*e en irOveat d#f g purgi%,

saeples f roa the establis*wd ret =crk cf eiq* teen creratiag staticrs will coSti*se to te collected. S&Petes iD tre d;=*=ird sect 0e will be CoIItcted every day, ratFer IM* t*, IN*ee tiees per week LMer rcewal CONI

• tiens, In aMition at le a s t cre s aro l e f ros "cr at eo)* Statice s in each cad

• ant net in tM d?.*=ind tra,iec-tory will te collected aN a lly!ed cm a daily bisis.

En reports an results o< their etc*ie; nemeenents fra t*eir reelice precan th-ce times ea:n =m te tre public aM ne=$ eedi a.

If a.rnic, negi,g is a:c*eved, ET A will nate daity repcets to t*e c.blic aN r+=5 nedia starting ac;rcuiutely t=c meets te'0*e intiation of gu*ging, aN C0rtir#g vtil purgirg is cescleted.

e.3 Ce e =*alth of Fe esy1.amta Radiole;ical wenitceing Pe:g*an h

TBe Cepart> tent cf Erviroventa! Eescu-ces of t*e Cemhrwea!!*i of Feansy1.ania crerates t**ee ccetiNeus air sar ling static 5; one at the Et a*gelical Press f aildtrf H Ha*Pist.eg, One at tre It'! Ctsenatica Eeildirg, aN c*e in OcIdstceo acar the beat dco. Each air sa*clirg statica ce*sists cf a Oneticulate filter fc11o=ed by a charc0al Cartridge. The filters aM cartridges are c*aNed te*ki);

t*, pa rt i c ul a t e a i r s aec l e s a*e Gi"FLa sc aared a t tetJ CC14ted f ee ee&cto"rel a te d ra di cng. l i de s.

IPe particulate air sa Cigs a e CMccsited harterly aM V31y ed fcr Sr-S9 a M Sr-90.

i*e co-artcal savoles are qsma sca-~cd fe* *eacic--related *adc %clices.

I*ey do act We.er.

a.e, e maei m, to s,-e

, a.e er ~

.s..--

,,n-..

8-3 8.4 U.S. Department of Energy 8.4.1 Cossounity Monitoring Pror; ras The Department of Energy and Cormonwealth of Pennslyvania are sponsoring a Consunity Radiation Monitoring Peogras.

This program has as its purpose to: (a) provide independent verification of radiation levels in the TMI area by trained local coesunity pecple, and (b) to increase public usderstanding of radiation and its effects. The approach to achieve this purpose has involved the selecticn of individuals by local of ficials f rom the following 12 communities within approximately five miles around TMI.

I East Mar.chester Twp.

Londonberry Twp.

York Haven Lowee "wa tara T=p.

Coney Twp.

Goldsboro F ai rvi e. T wp.

Royalton west Donegal T.p.

Middleto.n Newterry Two.

Elizabetetc.,

Approximately 50 individuals participated in trainis; classes cond cted by mercers of tre haclear Ersincering Departeent of the Pennsylvania S. ate University. A; promis-ately 15 training sessions =e-e conoscted involving classroom instructions, laboratory training and actual radiatien eenitoring in the field. The teams utilized EFA ganna rate recording devices which are cu ren*!y in place artar<1 TMI and will be supplemented ty gansa/ beta sensi-r tive devices.hich are teing furnished by DCE thecugh EG&E Idaho, Inc. This training was steuctured to cc.er the following areas:

1.

Classroos instruction Introduction to radicactivity i

Interaction cf radiation with natter Methods of radiation detection r

Radiation countieg variables Radiation protection units

!ealth physics procedures Radiatic, interaction with biolcgical systees Administrative precedares for Cereunity Radiation Monitoring Progras IMI-2 &cCident and Cle39Up

?eteo clegical conditiens 2.

L#scratory testruction G. M. (Geiger Mueller) ccunting enceriments Radiation counting statistics Mc 4 toring equipeent f amiliarization

8-4 Argon-41 and Krypton-85 monitoring Supervised area monitoring with actual procedures and equipment At the completion of the instruction phase, a final examination was given. This was followed by fleid monitoring training of approximately one week.

The training sessions provided basic information on radiation, its effects, detection techniques, and included hands-on experience with monitoring equipment in the field. Citizens were expected to demonstrate competence in both the theoretical and practical aspects of the course before actual monitoring ef forts begin, following the completion of training in the third week of April, team representatives in each of the 12 selected areas began data acquisition from the gamma and gamma / beta sensitive instruments on a routine basis. Detailed procedures were developed to consolidate the information being obtained into a central point of contact in the Commonwealth of Pennslyvania for dissemination to the press, local of ficials, and other interested parties on a routine basis.

Maintenance and calibration procedures were also developed and are in place prior to the initiation of routine field monitoring. The Community Monitoring Program was initiated on May 21 and the results of measurements from this program are reported daily to the public.

8.4.2 DOE - Atmospheric Release Advisory Capacity The Department of Energy will makv available during the purging operations its Atmospheric Release Advisory Capacity (ARAC). This ARAC system will provide independent predictions of the dispersion patterns for the krypton release based on local meteorological data and National Weather Service reports. T[esepredictionswilluseatmo-spheric dispersion models which have been verified during many years of field experience and tests in Government programs. The predicted dispersion patterns will be provided to the Environmental Protection Agency to serve as a basis for their positioning of ground level monitoring teams. These predictions will also be provided to the utility and the NRC, as an additional means of assuring that the purging operation is being adequately controlled.

8.5 U.S. Nuclear Regulatory Commission Radiological Monitoring Program l

l The Nuclear Regulatory Commissien (NRC) would operate one air sampling station located in the middle of the reactor complex. The air samoles would be changed weekly and analyzed by gamma spectrometry. The NRC would place l

two sets of 1LDs at 59 locations as shown in Tabla 8.2.

Both sets would be read on a monthly basis; however, flexibilityexiststoreadon$tetatmorefrequentintervalsshouldconditionswarrznt.

Licensee'sRadiohqicalEnvbonmentalMonitoringProgram 8.6 Thelicenseenormallyutilizes72radiologicalenvironmertalmonitoringlodionstomonitorplantreleaseswith two thermoluminescent dosimeters (TLDs) at eich locatien, In addition to these required TLDs, four additional TLDs will be placed in each of these locations during controlled purge; two for periodic readouts (f requency depends upon purge duration and the influence of plume) and the remaining two for assessment of the integrated dose over the entire purge period. In anticipation of certain sectors coming under the influence of the plume for a greater duration of purge period, additional TLDs will be placed in selected areas.

In addition to the TLD monitoring, grab air samples will be obtained by an individual (s) dispatched via two-way communications to the projected p1rme touchdown area during the controlled purge. The air sampler will be placed and operated such that a grab sample will be s btained over a 15-20 minate period while immersed in the plume.

Hourly update of plume direction and touch-down area, utilizing real time monitoring and an assessment program, will be obtained and disseminated to field sampling teams.

l h

8-5 Table 8.1 Three Mile Island EPA Long-Term Surveillance Stations Air Samplers, Gamma Rate Recorders, TLDS i

STATION AZ DISTANCE (Miles)

ASSOCIATED TOWN 3

325 3.5 Meade Heights, PA - Harrisburg International Airport 4

360 3.0

• Middletosa, PA - Elwoods' Sunoco Station 5

040 2.6 Royaltown, PA - Londonderry Township Building 9

100 3.0 Newville, PA - Brooks Farm (Earl Ninsley Res i -fence) 11 130 2.9 Falmouth, PA - Charles Brooks Residence 13 150 3.0 Falmouth, PA - Dick Libhard Residence 14 145 5.3

• 8ainbridge, PA - Bainbridge Fire Company 16 180 7.0

• Manchester, PA - Manchester Fire Dept.

17 180 3.0

• York Haven, PA - York Haven Fire Station 20 205 2.5 Woodside, PA - Zane Resner Residence 21 250 4.0

• Newberrytown, PA - Exxon Kwick Service Station 23 265 2.9 Goldsboro, PA - Muellar Resident 31 270 1.5

• Goldsboro, PA - Dusty Miller Residence 34 305 2.7 Plainfield, PA - Polites Residence 35 068

3. 5 Royaltown, PA - George Hershberger Residence 36 095 0.5 TMI Observation Cer.ter 37 025 0.7 North Gate, TMI 38 175 0.8 South Gate, IMI

• Sampling stations located in indicated town. Other sampling stations are located near indicated towns.

T 8.6 Table 8.2 DESCRIPT10N OF NRC TLD LOCATIONS I

El - Hwy. 441 on Laurel Road let telephone pole on right outside vendor TLD box.

90*

0.45 mi NEl - On telephone pole by Gcorge Beyer Market, Ceyers Church Road of f 441.

25*

0.8 mi NE2 - On telephone pole at intersection of Hillsdale and next road on left f rom Ceyers Church Road (closed road to gold church) by yellowish red house.

19*

1.9 mi N1 - On chain link fence for power substation, Middletown SE corner.

358' 2.6 mi NE3 - On telephone pole on Rt. 230 directly across from Shady Lane Motel.

15' 3.05 mi NE4 - On telephone pole on Rt. 743 just north of Texaco atation, just north of Turnpike underpass.

55*

6.5 mi N2 - On telephone pole on Middletown Road N of Rt. 283, directly acrosa the street from childrens care center.

N} - On sign pole on Middletown Road at intersection to Rt. 322 E.

Signpole says 322 West.

0*

7.0 mi N4 - On telephone pole on Hoe Road, just N. of intersection of Union Deposit Road.

2nd pole on lef t.

O' 9.0 mi N5 - On telephone pole on Rt. 39 at intersection of Rt. 22 (Allentown Rd.)

0*

13 mi NW5 - Environmental Station (Met Ed) at West Fairview, rear to Annex Building Fairview Fire Department, adjacent to tracks.

305*

15 mi NW4 - On telephone pole on Meadowbrook just of f Bridge Street, one block on N.

side f rom Bridge Street.

300*

8.6 mi NV3 - On telephone pole on Old York Road. Ist pole over turnpike overpass, west side.

295*

7.4 mi NW2 - On telephone pole on Marsh Road by Culvert under RR tracks of f Old York Road.

300*

5.9 mi NW1 - On telephone pole directly in front of church at intersection of Rt. 262 E and Rt. 392 W (Valley Road and Yocuatown Road).

305*

2.6 mi WI - On "No Parking Any Time" sign within 18' of water at old boat ramp at Goldsboro.

264*

1.25 mi W2 - On const?.nt monitor inside chain link fence to Monitoring Station, Goldsboro on Rt. 262.

By stream.

252' l.3 mi SW1 - On telephone pole approximately 25' from tracks in turn around full of flattened beer cans.

Across f rom 2 small trailers (green and blue) in clearing (N end).

200*

2.1 mi W3 - On telephone pole on Pines Road at intersection of 974 Red Mill Road.

near Newberry.

264*

2.9 mi.

W5 - On telephone pole at intersection of Rt. 382 and Rt. 177 NW corner Lewi sbu rg.

259' 7.3 mi.

W4 - On telephone pole on Rt. 392 (Pathshill Road) just beyond Ridge Road on S. side.

Beyond sharp bend.

266*

5.9 mi

8.7 Table 8.2 (Continued)

SW2 - On telephone pole at intersection of 382 E and 295. Diagonally across f rom Texaco station, York Haven Road and Reeders Hill Rd.

Pleasant Crove.

203*

2.5 mi S On telephone pole at intersection of Rt. 181 and 382. Across street f rom York Haven Of fice.

In f ront of Catholic church, York Haven.

168*

3.15 mi S On telephone pole at intersection of Meeting House Road and N. George Street (Rt. 181 S), Manchester.

175' 5.1 mi S On telephone pole on Rt. 238 at ictersection tc Rt. 181 S.

By old brick and cement block building, Emigsv111e.

180*

9.1 mi SW3 - On telephone pole at intersection of Lewisberry Road and Butter Road.

By small f rame house near Anderson town.

210' 8.1 mi SW4 - On telephone pole at intersection of Butter Road and Bull Road 215*

10.1 mi S York substation, sampling enclosure.

180*

12 mi SE5 - On telephone pole at intersection of 441 N and Vinogary Ferry Road across entrance to Cargill Truck entrance.

SE4 - On pole at intersection of 441 N and 241 N.

Pole next to fruit stand.

141*

4.6 mi SE3 - On chain link fence on right side by Collins Substation sign at intersection of 441 and Falmouth Road.

160*

2.25 mi SE2 - On telephone pole at intersection of 441 N and Turnpike Road.

162*

1.85 mi SE1 - On telephone pole across f rom Red Hill Farm f ruit stand 441 N, I mile from 3 Mile Island.

150*

1 mi E2 - On telephone pole at Hillsdale Road and Turnpike Road.

110*

2.7 mi E3 - On telephone pole at Turnpike Road and Bossier Road.

101*

3.7 mi E4 - On telephone pole at intersection of V Hight Street and Mosorte Road, Eliza be t ht own.

90*

7.0 mi E5 - Meadow Lane, 1st house on south side of street.

86*

0. 4 mi N

- Rte 441 03*

1.8 mi NE - Under TM1 high tension lines 44*

1.1 mi ENE - Rte. 230 64*

3.8 mi SE - Rte. 411 130' O.5 mi Ssw - Seech Island 203*

0.7 mi SW - Newber ry Township 227' l.8 mi NNW - Shelly Island 289*

0.3 mi

8.8 Table 8.2 (Cer,tinued) hT4 - T m of Plainfield 30l*

1. 3 si Y4 - Hill Island 316*

1.2 ai F4 - Highspire 326*

5 at NW - Kohr taland 332' O.5 mi NRC - TLD SCHOOL 1,0 CATIONS Ela NORTWJtEERLAND SCHOOL 2.4 al N N1b MNSBERCER SO!OOL

?.7 mi hT4 Nic FEASER SCHOOL 3 mi N N1d CAPITOL cad 1CS, PEXX STATE U.

3.5 al N4 Nie GtANDVIrd SCHOOL 3.5 mi NW N1f MIDDLETOW HIGi SCHOOL 4 ni NW NE-3a TOWSHIP SCHOOL 3.6 mi NE W-3a ErdBERRY SQiOOL 4.4 mi W S-la TCRI MAVEN-Nrd5URG SCHOOL 3.3 31 S SE-4a RAIN 5 RIDGE SCHOOL 5.0 mi SE o

e

9-1 9.0 Response to Comments 9.1 Introduction The draf t " Environmental Assessment for Decontamination af the Three Mile Island Unit 2 Reactor Building Atmosphere" (NUREG-0662) and two subsequent addenda were issued for public comment. The public comment period for these three documents ended May 16, 1980. At the close of the comment period approximately 800 responses had been received.

Comments on the Environmental Assessment were received from various Federal, State, and local agencies and of fi-cials; from nongovernmental organizations, and from private individuals. All substantive comments received appear in Volume 2 of this Assessment. The comments received fell into.one of three categories: (1) those supporting the purging alternative recommended by the NRC staff (approximately 195 responses), (2) those opposed to the purging alternative (approximately 500 responses), and (3) those who recommended decontamination alternatives other than those discussed in the Environmental Assessment or who otherwise commented on the assessment (approxi-mately 105 responses). The third category also included all other comments on the five alternatives evaluated in the Environmental Assessment, as well as suggestions for additional methods for decontaminating the TMI-2 reactor-building at.90 sphere. Several of the responses included specific editorial comments. Where appropriate, these comments have been resolved by revision of appropriate sections of this final Environmental Assessment.

9.2 Comments Supporting the Recommended Purging Alternative The NRC staf f received approulmately 195 responses supporting the purging alternative recommended in the Environ-mental Assessment.

9.2.1 President's Council on Environmental Quality (CEQ). CEQ stated that in their view the hRC staf f's proposal to separate the decontamination of the reactor building atmosphere f rom the preparation of the Programmatic Envi-ronmental Impact Statement ooes not violate 40 CFR $ 1506.1 (1979) (Limitations on actions during hEPA process) of the Council's regulations implerenting the National Environmental Policy Act.

9.2.2 fhe U.'S. Environmental Protection Agency (EPA).

EPA stated that the most acceptable method for decontami-nating the IMI-2 reactor building atmosphere is a controlled purge to the environment in as short a time as possi-ble, when meteorological conditions most favor dispersion. EPA based its recommendation of this method on the very low environmenta' and public health impact that would result from the controlled release of the Kr-85 and stated that this method would eliminate the large occupational radiation exposure which could occur from use of the other decontamination alternatives. EPA also stated that their assessments of the offsite doses for the purging alternative were in general agreement with those calculated by the NRC staff and that the esticated health risk of releasing the Kr-85 was 0.0001 excess deaths to the 1,750,000 population within 80 kilometers (50 miles) of Three Mile Island.

9.2.3 U.L Department of Health, Education and Welf are (HEW).

The HEV Careau of Radiological Health commented that af ter reviewing the draf t Environmental Assessment and its two addenda, it is their conclusion that the purgirg of the KR-65 in the TMI-2 reactor building to the atsasphere under controlled release is the prudent and proper course of action which provides minimal, if not Zero,' health impact. They further noted that although members of the public in the vicinity of IMI may call for alternatives

9-2 that do not release the KR-85 to the environment, the occupational workers are also members of the public and the health Impact (if any) best relates to the total population dose in person rem (both occupatioaal and general public). In this regard, they stated that it would be appropriate for the NRC to provide estimates of the total population dose (both offsite and occupational). The NRC staff has included these recommended dose estimates in this Final Environmental Assessment.

9.2.4 The U.S. Department of Energy (DOE).

DOE submitted two responses. The Assistant Secretary for Nuclear Energy stated that his staff had performed an independent review of the matter and had concluded that a controlled purge was indeed the preferred method for decontamination since it would result in less public radiation exposure than accrues from many other power plants, both nuclear and fossil. This response urged the Commission to act promptly on the matter, and in the event of NRC approval, offered the resources of DOE to assist in monitoring off-site conditions during the purging process to help guarant?e that conditions rerain within acceptable limits. (See Section 8.0).

Their support for the purging alternative was reiterated by a DOE representative on April 25, 1980 during a Commission briefing on.

Selective Absorption Process as an Alternative in Dealing with Krypton in TMI ' Containment.

The second DOE response, f rom the Assistant Secretary for Environment, stated that their review had identified several areas where they felt that additional information or clarification would enable a more complete assessment of the potential effects of the removal of krypton gas from the reactor building. The following comments on NUREG-0662 were of fered for consideration:

The accident analysis for each alternative, including the proposed action, should include estimates of the probability of occurrence of the worst case scenarios. This would permit a more complete evaluation of the potential for adverse health and safety impacts.

A more precise estimate of the time necessary to implement the various alternatives should be provided because of the importance of this factor in the overall decision-making process. Estimates should be based on realistic projections of an accelerated construction / testing program for each alteenative.

The potential hazards associated with the storage of Kr-85 should be quantified to the extent possible in order to better reflect the seriousness of problems associated with the storage.

Advanced A more detailed description of t!.e monitoring program for the proposed action would be helpful.

monitoring to calibrate and verify analytical methods for predicting the incremental dose at the site boundary should be discussed. The ability to promptly and accurately determine of f site concentrathns also should be discussed in more detail.

The description of DOE's radiological monitoring program (Section 8.0) does not represent an accurate summary of our current efforts. An updated version of this section is enclosed for your information.

The The nature and extent of the controversy surrounding the proposed venting should be presented.

basis for the technical questions being raised by various segments of the public and scientific com-munity along with a critical evaluation of their concerns would provide a more meaningful assessment of the significance of the impacts of the proposal.

The recommendation to include estimates of the probability of occurrence of the worst case scenarios for the various postulated accidents was considered by the NRC staff. Since the health effects resulting from worst case accident scenarios for any of the alternatives are negligible, the probabilities of occurrence are irrelevant.

Although these probabilities have rot been quantified, they are considered low. As for the proposed actions to be taken in the event of a postulated accident, the NRC staff will require that appropriate emergency and contingency procedures be prepared and approved pursuant to the requirements of the f acility Technical Specifications prior to the implementation of any decontamination alternative.

The estimated times to implement the various decontamination alternatives, including the use of accelerated construction / testing programs, have been reviewed.

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9-3 The potential hazards associated with long-ters storage of Kr-85 and the hRC staf f's reason for recommending against long-term storage of Kr-85 are discussed in Section 6.8.

The description of the monitoring program to be used if the purging alternative is approved, has been revised and updated to reflect the current monitoring program. Section 8.0 contains a detailed discussion of the planned monitoring program, including an updated version of the DCE sponsored portion.

In its preparation of this final Environmental Assessment, the NRC staff has again evaluated, as recommended, the nature and extent of the controversy surrounding its recommendation to decontaminate the TMI-2 reactor building atmosphere by purging to the environment as presented in araft NUREG-0662. An evaluation of the public comments and responses to this proposal is contained in Section 9.0 of this fina' Environmental Assessment while section 7.2 contains a discussion of the psychological aspects of the proposal.

9.2.5 Advisory Committee on Reactor Safeguards.

in a joint meeting between the hRC Commissioners and the Advisory Committee on Reactor Safeguards ( ACRS) on April 4

11, 1980, several members of the ACRS recommended that the reactor building atmosphere should be decontaminated soon by controlled purging to the enstronment. Their reasons for this recommendation mere that a controlled purge would permit less restricted access to the reactor building for equipment and instrument maintenance and repair which may be required in the near future, and that the health ef fects of a controlled purge would te very small.

9.2.6 Governor of Pennsylvania.

The Governor's comments were contained in a letter submitted to Chairman Ahearne af ter the Governor received an independent assessment of the proposed decontamination effort from the Union of Concerneu Scientists (UCS). The Governor had requested this independent assessment and had teen granted an entension of the public comrent period to permit the completion of this independent assessment. In his letter to Chairman Alearre, the Governor stated:

This is to notify you of my views, on behalf of the Common =ealth of Fennsylvania, regarding the procesal now before you to remove radioactive krypton 85 from the Three Mle Island Unit 2 containment building by the process of venting it into the atmosphere.

I have sought and received assessments from the broadest range of knowledgeable sou ces available r

regarding potential health effects of that proposal. These sources tave incluced:

• Members of your own staf f, and especially Mr. Harold Centon, your director of nuclear reactcr eegulation.

• The Union of Concerned Scientists (UCS), the nation's foremost critic. I telieve, of existing nuclear power safety levels.

• The National Council on Radiation Protection and Measurements (NCRP), an organization of dis-tinguished scientists and physicians which has been instrumental ir setting radiation health standards in this country for nearly 20 years.

• Representatives of the electric utility and nuclear industries.

• The U.S. Department of Health. Education, and welfare.

• The Governor's Commission on Three Mile Island.

'The Pennsylvania Cepartments of Health and Public helfare, the latter of which has jurisdictier. in the area of mental health in our state.

• The Fennsylvania Cepartment of Environmental Resources (CE E), including its eureau of Radiation Protection.

The assessments of these various groups and institutions are teing formsrded to you under secartte cover, and I respectfully request that you enter thee into your of ficial record on this matter.

9-4 There is, I have found a broad-based consensus among these sources that the enting proposal now before you would have, in the words of the Concerned Scientists, "no direct radiation-induced health ef fects on the residents of this area."

Sfallarly, the NCRP concludes:

"the esposures likely to be received as a result of venting are not a valid basis for concern with respect to health ef f ects."

There is a consensus on the accuracy of the radiation dose rate calculationt made by your staff, in conjunction with the utility, smd there is a consensus that those dose rates are " ins gnificant.*

i I should point out that the Union of Concerrad Scientists feels that the psychological stress alreadj emperienced by many residents of this area since March 28, 1979 should seriously be considered in any decision you make with regard to the cleanup operation on Three Mile Island, and I agree with that.

As you know, I previously instructed attorneys for the Commenwealth to introduce stress as a legitimate f actor for you to consider in other decisions growing out of this incident.

I am ad,ised and I believe, however, that the question of stress, as related to the venting plan, is directly lin6ed to the question of its safety, and that the consensus finding tnit the plan poses no radiation threat to public health should, in itself, substantiaily reduce any stress that eight have accompanied it.

UC5 also recommends that you consider two alternative venting plans described in its report, and that you reconsider two non-venting plats previously rejected by your staf f.

I am sure you will gine due consideration to those recommendations. I do urge that any new assessments te completed as promptly as possible. I as advised and believe that the sooner this matter is resolved, the sooner any stress related to it will be dissipated.

I recognize that part of the delay already esperienced has been due to my ef f ort to be assu ed of the r

safety of venting. I now have that assurance, and I feel that a safe cleanup plan should be imple-mented as quickly as possible.

Should you proceed with the venting pro-osal advanced by your staf f, be assured that I as prepared to support that decision. fo minimize stress, I am prepared to commit all of the rescurces at ey disposal to assure the residents of the area, as ! am now persuaded, that this plan is, indeed, a safe cre.

In his letter, the Governor noted that the UC5 had recommended consideration of two alternative purging plans as well as consideration of the Cryogenic Processing System and the Selective Absorption process Systes (Gef. 3).

In preparing this final invironmental Assessment, the NRC staf f has evaluated the two alternative purging plans suggested by the UCS and has also reconsidered use of the Cryogenic Processing Systee and the Selective Absorption Precess Systee.

The first of UC5' proposed plans would use a tethereo talioen to support a 2000-foot-nigh reinforced f abric stack, a discussion of which is given in Section 6.2.5.

This technique is unique and untried, as stated by UC).

In general, the staff finds the UC5 proposal technically workabte and probably capable of being implemented within a year from the time the decision to use it was made. However, 'he staf f has examined Three Mile Island for uncbstructed ground and air space to laun;h a tethered ballon. Adequate unobstructed land recommenced for the ballon launch is not readily available on the islard without substantial podification to the site.

The second proposal of UC5 was that the reactor building atmosphere be heated in an incinerator and discharged through a 250-f oot-high stack. The staff evaluated this proposal in Section 6.2.5.

Reconsideration of the Cryogenic Processing and Selective Absorption Precess Systems are contained in Sections 6.6 and 6.7, respectively.

Having evaluated these proposals, the staf f continues to believe that the Ar-85 should te purged to the envirenzent through the hydrogen control system.

F inally, the staf f and the Cnnmonwealth of Pennsylva9f a would ha,e to ascertain the psychological irpact on the nearby residents regarding the Kr-85 purging techniques proposed by the UCS.

Ihts difficult task was recognized by UCS as a valid concern in its report to the Governor.

As enclosures to a subsequent letter, the Governor of Pennsylvania provided copies of the varicas reports and assessments he had referred to in nis prev.ous letters and stated that the joint press release which he h+1 devel-oped with the UCS contained a clarification regarding the first reconnendation on page 57 of the UCS report. The subject UCS recommendation stated:

9-5 UCS recommends against any procedure that would result in citizens in the area around TMI being deliberately exposed to radiation from the plant at levels comparable to those expected from the Met Ed/NRC venting proposal.

Dr. Henry W. Kendall, UCS chairman, said the organization ultimately decided to recommend against implementation of the existing Met Ed/NRC venting plan, but he emphasized that this was primarily because of the stress problem.

The enclosed report of The Governor's Commission on Three Mlle Island stated:

In light of our review of the alternative risks, this Commission urges the NRC to make a prompt decisien concerning the proposed venting of the Unit 2 containment building atmosphere. Avoidance of this decision by the NRC is unacceptable. This Commission woul not oppose r.n NRC decision to vent the krypton gas, provided that dose levels projected in the

1. ironmental impact assessment at acceptable. This position is based on a careful review of t' sest evidence available at this time. (emphasis in original)

An enclosed memorandum to the Governor from the Pennsylvania Department of Environmental Resources stated that they had concluded that controlled purging using the hydrogen cont,rol system, as recommended by the NRC staff, was the preferred alternative for removing the krypton from the reactor building atmosphere.

An enclosed letter to the Governor from the Pennsylvania Department of Health recommended that in an effort to minimize stress, both present and accumulative, purging of the krypton from the reactor building be accomplished as soon as possible and in as brief a time period as possible.

An enclosed letter to the Governor from the Pennsylvania Department of Public Welfare stated that making a deci-sion on purging and proceeding in a responsible fashion could in the long run minimize stress and reduce the potential for anxiety and depression among the population that lives near TMI.

9.2.6 State of Maryland.

The State of Maryland responded with two sets of comments. Their first response addressed the staff's recommenda-tion in the basic Environmental Assessment (N'JRFG-0662), while their second response addressed Addenda 1 and 2 of NUREG-0662. In their first response (March 31, 1980), the State of haryland agreed with the NRC staff recommenda-tion that purg a the reactor building atmosphere to the environment is the best available option. They did, however, recommend that real-time environmental and meteorological monitoring be used for dose-rate monitoring and reduction during purging operations to ensure that the of fsite doses are estimated accurately and minimized. They i

also stated t'is was the proper time to makr a decision regarding the decontamination of the reactor building h

atmosphere and that this action should be c.,nsidered apart from the Programatic Environmental Impact Statement being preparod by NRC on all TMI-2 decontamination activities. They note that no benef it would be served ty a delay and that, instead, delaying the decision would result in "a substantial loss." In their second response (April 22, 1980), they stated that the fast purge described in Addendum 2 of NUREG-0662 (a five-day purge over a two week period) does not of fer any net psychological advantage and that this option should be rejected in favor of a purge program which would use real-time meteorological data to minimize the highest offsite dose.

9.2.7 Member of the Pennsylvania House of Representatives.

One member of the Pennsylvania House of Representatives submitted as a comment a letter he had sent to all elected officials in his legislative district requesting that they join him in his call to come together and furnish the leadership necessary to accomplish a safe and empeditious cleanup at TMI. He also submitted several responses he had received in support of his call. Another member submitted a letter in which he stated: " Vent it!"

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9-6 9.2.8 Comissioners of Cunderland County, Pennsylvania.

The Coenissioners of Cumberland County, Pennsylvania, submitted a resolution supporting the recommended purging alternative. Their resolution stated that it is in the public interest to provide for the henith and welfare of the people of Cumcerland County by cleaning up TMI as soon as possible and that "the Government" should esert the necessary leadership to accomplish this action.

9.2.9 Middletown Porough Cou cil, Middletown, Pennsylvania.

n The Middletown Borough Council passed a resolution in support of purging the krypton-85 gas into the atmosphere.

This resolution stated: "this council supports the venting (of krypton-85 gas in the atmosphere) as reconnended by the NRC staf f and calls for implementation as quickly as possible."

9.2.10 Borough of Royalton, Pennsylvania.

The Borough of Royalton, Pennsylvania subeltted a resolution supporting the recoenended purging alternative and the cleaning up of TWI as soon as possible. This resolution stated that their support was based on determinations by the NRC and EPA staf f s that it is safe and proper to purge the Kr-85.

9.2.11 National Council on Radiation Protection end Measurements (NCRP).

The NCRP, in addition to the UCS, mas specifically requested by the Governce of Pennsylvania to review the proposed purgiaq operation. The NCRP submitted a response in which they stated:

At the request of Governor Thornburgh of Pennsylvania, the National Council on Radiation Protection and Measurements (NCRP) has emasined scientific material relating to the health ef fects of krypton-85, updated its Report No. 44 on krypton-85 published in 1975, and estimated the doses to the public and the risks associated with them for the amounts of krypton-85 expected to be released as a result of the preposed venting at the Three Mile Island nuclear power plant. The findings are that the sauteus doses likely to L.e received by any person are very small.

Superficial beta radiation to the skin is the primary potential health concern; ho=ever, in the total population =lthin 50 alles no cases of skin cancer would be expected f rom the doses likely to be received.

The risk ta the maufnally esposed individual pesber of the population at the plant boundary is estimated to be equ'

• nt to the risk of skin cancer resulting f rom exposure to a few hours of sunlight, which is known to be the principal cause of skin cancer in the general pcpulation.

The dose expected from the penetrating radiation is about 100 tiees less than that from the superficial radiation and the risk of inducing cancer is correspondingly smaller.

The NCRP concludes that the esposures likely to be received as a result of venting are not a valid basis l

f or concern with respect to health ef f ects.

9.2.12 hitural Resources Defense Council (NEDC).

f The NRDC provided a response by phone in =hich tney supported the recomended purging operation by stating:

1 Provided that the amount of radioactive saterials to be vented are =5at they are reported to be (for enarole in NURM-0662), and provided that the venting procedures are appropriately conducted, then the public health t'sks (somatic and genetic consequences) associated with venting the TMI-2 containment are not significans, that is, sufficient to warrant esclusion of this option.

t 9.2.13 Other Cements $t:pporting Controlled Purging.

j in addition to the coceents f rom these government agencies, of ficials, and scientific organizati ps, cceents l

supporting the recomended purging alternative mere also received f rca approximately 30 nongeverrmental organiza-tions. These included the Pennsylvania Charter of Ccemerce, Lebanen Valley Chamber of Ccmerce, Greater i

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9-7 i

Harrisburg Area Chamber of Commerce, York Area Chamber of Commerce, Hanover Area Chamber of Commerce, Lancaster Association of Commerce & Industry, Manufacturers' Association of York, Pennsylvania, Greater and Central Pennsylvania Building and Construction Trades Council. Harrisburg-Hershey Area Tourist Promotion Agency, 1

Harrisburg Hospital, American Association of Meat *rocessors, and various business'es in the TMI area, and approximately 150 private individuals and members of the professional community. Those commenting typically

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l recommended that controlled purging be performed soon to permit continuation of the required cleanup activities.

I 9.2.14 Science Applications inc. (SAI).

At the request nf *he Commission, the NRC Office of Policy Evaluation (a Commission staff office), contracted with sal to perform an independent technical evaluation of the purging alternative and Selective Absorption Process 4

(Ref. 43). SAI's conclusions and recommendations were:

From the points of view of feasibility, effectiveness practicality and the health and safety there is little to choose between the two alternatives.

From the point of view of psychological stress on nearby populations, purging is the best alternative because it can be carried out in the least time with the fewest newsworthy incidents.

From the points of view of schedule and cost, controlled purging is the best alternative because i;.5 i

cheaper and can be started within days.

Therefore it is our opinion that the SAP should not be adopted as a substitute for controlled purging.

9.3 Comments Opposing the Recommended Purging Alternative i

Approximately 500 responses opposing the purging alternative recommended by the NRC staff were received. Included in these comments was a resolution by the County Commissioners of Dauphir, hunty, Pennsylvania, opposing the selease of the krypton-85. The reasons stated for their opposition were (a) the health of humans, animals and plants nearby cannot be fully guaranteed, (b) the full health implications of low level radiation exposure are not known, (c) health studies on human thyroids and various ailments af flicting animal life have not been completed to determine what effect, if any, previously released low level radiation has already had on humans and animals in the TMI area, (d) other options remain for the removal of the krypton-85 which have not been assessed independently by experts outside the NRC or Metropolitan Edison Company, (e) experience of the last thirty years froO radiation exposure to indigenous populations near nuclear sites indicates clear health risk and resultant increased health problems from varying exposure levels to radioactive particles, (f) radiation and exposure measure-ment standards currently being used by the NRC and Metropolitan Edison Company are based on experiments and standards discredited by recently completed Heidelburg Studies and serious questions as to their accuracy and validity therefore exists in the scientific community.

The lower Swatara Board of Commissioners Dauphin County, Pennsylvania, passed a resolution initially stating opposition to the purging into the atniosphere but further stating that they would accept the final recommendation

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of the Union of Concerned Scientists.

The Newbury Township Board of Supervisors, York County, Pennsylvania, also submitted a resolution which opposed the release of krypton-85 into the atmosphere; however, no specific reasons for their opposition were provided.

i The Mayor of Lebanon, Pennsylvania, submitted a statement opposing the purging alternative and urging that alter-j native cleanup methods, which would not release radioactive material into the atmosphere, be employed without delay.

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A member of the House of Representatives of the Commonwealth of Pennsylvania submitted a response in which he requested that the recommended purging operation be delayed at least until an independent assessment could be i'

9-8 performed. The Union of Concerned Scientists was suggested as a possible organization to perform such an assessment.

The TM! Legal Fund submitted a response in =hich they stated their opposition to the recomended purging operation. They summarized their opposition into the following three corcerns:

1.

There is no emergency at hand. Data may be collected and containment facility equipment may be inspected and maintained without removal of the kryptc,n-85 gas. There is adequate time to implement an alternative system for krypton-85 removal from the containment building atmosphere.

2.

Venting of krypton-85 gas into the air which surrounds TMI-2 carries definite genetic and carcinogenic risks to the people of nearby comunities. For a population which has already endured severe psychological stress, the proposed venting will only exacertate this state of stress.

3.

The proposed venting cannot be controlled due to meteorologic uncertainty. The monitoring as descrited by the NRC is incapable of providing suf ficient information for the protectinn of people in comunities surrounding TMI-2.

They also urged that data collection be initiated, that the containment building equipment be inspected and maintenance begun at TMI-2, but that the krypton-85 gas be reta'ned until an alternative system has been installed for its safe and efficient removal.

The TMI Legal Fund response also stated that (1) the draf t Environment Assessment did not adequately evaluate the potential health ef fects of the purging operation, (2) an independent assessment of the purging operation should be obtained (3) the segmentation of the reactor building atmosphere decontamination ef fort f rom the Programatic Environmental lepact Statement was an illegal action, (4) the sonitoring program and criteria were insuf ficient, and ($) the krypton being approximately five times denser than air will therefore settle into low-lying areas such as valleys and basements in the absence of adequate convection.

In addition to the above noted coments, additional coments cpposing the recomended purging alternative were received from approximately 10 nongovernment organizations (including the Of fice of the Provost, Capital Cascus, the Pennsylvania State University; the National Audubon Society; Taxpayers Association of Lacka-anna County; Heathcote Valley Alliance; Air and Water Pollution Patrol; Lehigh-Focono Comittee of Concern; and various businesses in the TMI area); and f rom approximately 485 private individaals. Their reasons for opposing the recomended purging operation included the following: (1) that the public be esposed to no additional radioactive effluents from THI, (2) that one or more of the other alternatives for decontamination evaluated in the draft Environeental Assessment be used to eliminate or minial2e the release of Kr-85 to the environment, (3) that there is no perceived or recognized need for the decontamination (several persons suggested that the f acility be entombed in its present condition), (4) that any purging operation te delayed at least until students are released from the schools for sumer vacation, (5) that any purging operation should te accompanied by a more extensive conitoring progras, and (6) that an independent assesseent of the recoerended purging operation te first performed by a citizen-dominated group.

9.4 NRC Staf f Responses to Coments Opposing the Recommended Purging Alternative A detailed discussion of the health effects associated with the various alternatives for decontaminating the reactor building atmosphere has been incorporated into Section 7.0 of this document. The hRC staff has determined that the potential for adverse radiological health effects to the public due to utilization of any of the decontamination alternatives is regligible and that the public health and safety will not be adversely af fected by

l 9-9 the purging operation. Therefore, since the recommended purging operation can be accomplished without signific&nt risk to the health and safety of the public, and since the purging operation can be imlemented immediately as recommended in Section 5.0, the NRC staff recommends that use of the purging a % rnative be authorized soon, rather than waiting for installation of one of the other decontamination methods.

At the request of Governor fhornburgh of Pennsylvania, the public comment period for NUREG-0662 and its two Addenda was extended to May 16, 1980. The reason for the Governor's request was to permit sufficient time for completion nf an independent assessment of the decontamination operation by the Union of Concerned Scientists (UCS). The Governor specifically requested the UC$ to perform such an assessment so that he could receive information from the broadest range of knowledgable sources available. In their report to the Governor, the UCS stated:

i UCS concluded that direct radiation-induced health ef fects from exposure to Kr-85 even from the Met Ed/NRC proposed venting would be absent. These conclusions are similar to those reached by the NRC and Met Ed.

In Addendum 2 to NUREG-0662, the NRC staff evaluated and recommended a variation in the purging alternative which would permit the purge to be completed in an elapsed purging time of approximately 120 hours0.00139 days <br />0.0333 hours <br />1.984127e-4 weeks <br />4.566e-5 months <br /> over a two-week period, provided it was performed before about mid-May to take advantage of expected favorable meteorology.

However, because of the delays to permit comments on decontamination alternatives, the NRC staff no longer recommends this variation in the purging alternative. The extended comment period has also delayed the purging operation until at least the beginning of the school summer vacation period, a delay requested by several com-mentators. However, for the reasons described in Section 5.0, the NRC staff now recommends that the purging alternative evaluated in Section 6.2 be accomplished without further delay.

Although several commentators did not recognize or acknowledge the need for decontaminating the reactor building, the NRC staff believes that it is imperative that this action be taken. The staff's reasons u r believing that this action must be taken are discussed in detail in Section 5.0.

This staff position was also supported by the UCS in their report to the Governor of Pennsylvania:

The Union of Concerned Scientists (UCS) Study Group believes that ultimate decontamination of the plant is an absolute necessity. Decontamination must include complete removal of the damaged fuel rods and of the contaminated water in the containment sump and elsewhere. The plant cannot be sealed and walked away from. This would constitute a negligent disposal means for a very large quantity of radioactivity.

Important quantities of these toxic materials would ultimately find their way into the environment during the tens or hundreds of thousands of years that some of them will remain hazardous.

Accordingly, UCS has concluded that the krypton mg be remosed from the TMI reactor building 50 that an orderly program of decontamination can be undertaken. The problei is how to do this in a manner which protects the safety of the workers who may be exposed to the kryp"on and alse safeguards the physical end mental health of members of the public who may also be exposed.

The UCS did however conclude that in their opinion a delay in removal af the krypton of up to a year and a half would not pose an undue risk to the health and safety of the public. Such a delay would of course postpone any substantive progress in the overall cleanup program and as stated in Section 5.0, the NRC staff believes that the cleanup program should progress in a timely manner.

The radiological ronitoring programs f or the IMI site and surrcunding area consist of several programs described in Section 8.0. In the epinion of the NRC staff, these programs with EPA having the lead for federal agencies, as designated by the Executive Office of the President) will provide an adequate monitoring of the recommended pt.rge operation. The on going cionitoring programs will be supplemented by the DOE prcgram described in Section 8.0 if the purging alternatise is approved. A cadre of about 50 lacal residents have been trained to participate in the DCE monitoring program. EFA will supplement its existing fiwd monitoring stations with mcbile units positioned in areas of expected maximum dose. Reports of measurements will be made daily by EPA to the pQlic and media.

9-10 Ce*trel cf t*e ps sf rq cceration.ill te ac caclisr+d t*re,,;*i f rew-t (at least Scarly) scriterias of t*e e

esisting retececlogical ccMitions aM reacter Niidi*g efflucat flo. rate.

T*e OCf setecect:sical fceecastlag radic1:S cal eenitcriN ;*:;*as i

and acaitering casatilities.111 utilfre tais infc*satico in cenj,.nctica ith results aM.ill te comunicated to 19 cc-trol rcco to assure t*.at tre c.malative S:ses to t*4 ;.eli: in a y sectcr.111 ret esteed those in Se-ctica 7.0 cf ints assessneat f *e %M staf f disagrees with allegatices t*at separating tac rea: tee Nileirg a:Jicsc***e oncertas i a.atie-n e f f ert f ree t*e Programatic Eaviro*eettal !sca:t Stateeemt.a s 111+;41.

T*is is sarocried ty CET s ceme-is, reted in Section 9.2.1 Tre basis for t*e staf f position is tre ConatssicW s Mience-21, 1979 Stateset cf Feif ty aN clea-ly resersed t*e cctiem te 40tice of Irtent to Frepare a Prcgramsetic f reirc-seatal !ac-act State +ct,.aica aatSorize swcm as action.*en it stated:

T*e ce.elecment of a peo;-amatic incart statewet.111 net peeciwde ;*onet 0:missicm a:tica #ea naeded. Tre Cemission cres recognize, rewe=er, that as ite its E;ic:*-II at:re.a1 a:ti:+, a y a:tica taaen in the assence cf an overall f aca:t stateweet.ill lead to a~; sweets tAat t*ere P-as t+e a, t aasecate erwironse.tal asaly sis, e.ee, =*ere t*e (cm issien's actica itself is 54corte: ty as e eirc~

setal assessment. As in settling 4,oe t*e se:ce of t*4 peo;*6matic inc.act statece-1, CIO cam lend ae re.

f er em ancle s*culd t*e Cemission tef c-e coecletiN its ;*cgeansatic statenet oecice assistaN e that it is in t*e test icterest of t*e palic health av safety tc cecentasir. ate tre et;n le.e1.aste

.ater ec. f r tN coetai-ment Niidim;. cr to per;e tr.at edidiN of its radicattise gases, t*e C missi:n w eceer, as stated in t*e

.ill constoer CE;'s ae. ice as to the Coenission's %EFA res:cesittlities.

e w y 25 stategent, a*y artica of t-is ai M.ill ect te taaem u-til it ras w-oe g:^e as Ccsusi s sica's a

en irc-mental renic, and f et*e-3:re.ith eccertAtt f:r c alic cce e t creeice?

Altw;*. a.eypica gas is a;;eoninately five tipes denser te,a7 air, it.ill n:t settle irto 1:w-lyieg areas 0*

taseeets as sv?;ested by se eral cementaters. Tr.e p*ysical ce cteties of gases (as es:eesset in tre p*ysical la.s tnat cestrite tre dispersien cf gases) ;+eveet t*e settlevet cf le. coxe-tratices cf ce ser gases 1-t:

le-.-lying areas.

7'e an; ten ceve-tration in tN reactse Nileias atmos:*ere is at a:; :=in.ately t*e sa.se cox e-tratica as naturally occarei g aortan in tre ea*ta.'s itses;*ere.

T*e raturally occw-r6; an;tc9 is tr i f o*a ly dis tr iNtes t.*eemq*c.t (Se e art *

• s at>resg *e re as i s t*e a n; tea i n. t*e reart:* NildiN's at.ncs;*e'e; i*

reitaer case *as t*e try; ten settled teto Icelyi ; areas.

9.5 Ct ce Cemets en t*e Recem# reed Pmi's alte rati e 9.5.1 lat-co ction T*e %i0 staf f recei.e3 a:c-ciis.ately 105 res;cnses previciN either s;ecific c: mets en tre fine alte-*.atfie net.*oss es alvated en %CEEMH2 fer ceco-tania.at tag tN reactc* Nilain; at.acs:rere er sv;gestic75 fr-escitie al pet *ofs fce at :CSC 1 i s h i N t*e reb re'0 de< O4t &W 5 Sa t I O"-

i t

I i.5.2 W*Cer Of CE*y'es s l

4 becer of CcNress f ree Persy1.amia sw Jitted a ccee-t e; csiag t?e cua,-ieg occatic9 aM recemeMi g that f

IN Selective Dscritici I*0 cess te used.

I*is rtC!aWre-M.iOF.as ta5ed LMn !?e DN'esstaC s Delief that t?e 1

5electise escrptic, trocess coald te placed irt eceratica in sin sc-t's a t tr.at esce;t fer t*e p egirg l

alternative, it =%15 te t*e least espensi e alte-sati e to isoleneat The sin e th inclene-tatioe time.35 f

Dased cn a revie. ;eefcered. at bis etAest, ty a sescer of t*e staff cf !?e U. L % se cf ie;eese*tatines l

Cemittee o, 5:ience aN Tececb;y. tu Ces-essus also rewsted Cas E! ;e satis-ai taterat: y (Obt) ::

reassess t*eir time estisate fer.*ec a Selecti.e Arse ;tien h ecess systen et see. ate ca:a:ity cc 1 ee pia:ec l

into oc c atie,at twi.

Om sesewesi, rex *te: trat.itw eest ef cris tesy eetes tf aii cre ~e:

parties, suc$ a systea cevic te eceratienal at Tw! in 13 scates.

i*e Tw Pm;-as Office also resested an i

l assessne*t Cf t*e OrcOcsed sc*e %les fCr fatricatiOO a-d i*sta1I4tian Of 5.,Ch a sy1tes by t*e Iea:10r C0"st*V: tic

• 4 l

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9-11

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and Engineering Support Branch of the NRC's Of fice of Inspection and Enforcement. The Reactor Construction and I

Engineering Support Branch concluded that the six-month schedule proposed by the staff of the Committee on Science j

and Technology was unrealistic and that the 13-month ORNL schedule was optimistic. They further concluded that i

their minimum schedule estimate would be 16 months with their best estimate being even longer.

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9.5.3 U.S. Department of the Interior l

The Department of the Interior commented that the draft report did not discuss what effects, if any, the proposed i

release of krypton would have on fish and wildlife resources and their habitats. As noted in Section 7.1, the recommended purging operation will have no significant effect on fish or wildlife resources or on their habitats.

i 9.5.4 MITRE Corporation I

The MITRE Corporation submitted a comment proposing to use a cryogenic air separation plect for removing the krypton from the reactor building atmosphere. This proposed method would be similar in operation to the Cryogenic

}

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Processing System described and evaluated in Section 6.6.

An evaluation of the proposal nubmitted by the MITRE Corporation and the NRC staff reasons for not recommending its use are included in that section.

9.5.5 International Business Machines Corporation (IBM) i A technical report copyrighted in 1979 by IBM was submitted as a comment. This report, " Encapsulation of f

Radioactlye Noble Gas Waste in Amorphous Alloy," describes a method for long-term storage of Kr-85. Use of this storage method requires that the Kr-85 first be separated ' rom the reactor building atmosphere by use of a f

cryogenic distillation tower similar to the Cryogenic Processing Systea described in Section 6.6.

As noted in that section, construction and operation of such a system wculd require a minimum 20 month delay which for the j

reasons discussed in Section 5.0 of this document are considered unacceptable. Therefore, no further actions have been taken on this comment.

)

9.5.6 Pennsylvania State Un Qersity l

l The Pennsylvania State University submitted a comeent suggesting the use of an oxygen liquefaction unit. This

)

unit would concentrate more than 99% of the krypton in the liquid oxygen product. The liquid oxygen would then be passed through a bed of adsorbent material such as silica gel where the krypton would be selectively adsorbed.

The separation of the krypton from the oxygen could be done either onsite or offsite. Such an oxygen liquefaction unit would be similar to the Cryognic Processing System evaluated in Section 6.6.

Due to the time required for construction and operation of such a unit (a minimum of 20 months), use of this method is not recommended.

l 9.5.7 Science Applications. Inc. (SA1) 1 A comment in the form of a proposal to remove the krypton from the TMI-2 reactor building atmosphere was received I

from SA!. The proposed method would use a selective adsorption process. In their proposal, SAI estimated that such a system would require nine months for design, construction and checkout. Due to this delay in system l

availability, the NRC staf f does not recommend further consideration of this proposal.

I 9.5.8 Environmental Policy Center j

l 1

The Environmental Policy Center submitted a comment suggesting that rather than decontaminating the reactor building, it and the radioactive wastes within it should be entombed. However, since it is imperative that the damaged fuel be removed from the reactor to prevent either its potential recriticality or eventual escape to the environment over very long time periods, the entombent suggestion is not considered a viable alternative, i

I

4 9-12 9.5.9 Environmental Coalition on Nuclear Power (ECNP)

I A comment from the FCNP recommended that rather than implementing the purging alternative, the krypton be removed j

from the reactor building atmosphere by one of the other alternatives (charcoal adsorption, gas compression, i

cryogenic processing, or selective absorption) and then transferred to some unpopulated place for release under controlled conditions. Because of the negligible adverse radiological health effects of the proposed purging operation, and becaule of the delays (16 months or longer) associated with the implementation of any of the other J

decantamination alternatives which do not purge, the NRC staff continues to recommend that the purging alternative be selected as the method for decontamination of the reactor building atmosphere.

The ECNP further stateI that if their recommendation was not implemented, there were at least two other alternatives which have not been evaluated by the NRC staff: (1) transfer the gas (the THI-2 reactor building atmosphere) to the TMI-2 reactor building and store it tharre until removal could be accomplished by one of the other decontamination alternatives, and (2) purge the TMI-2 reactor building atmosphere to the environment rapidly, as in a " puff release."

The NRC staff has reviewed tnese suggested alternatives and considers both of them unacceptable for the following reasons. As noted in Section 6.2, to reduce the radioactivity in the TMI-2 reactor building atmosphere to maximum l

permissible concentrations wouM regoire the transfer of about 23 million cubic feet of air. This trar.sfer would, I

in turn, pressurize the TMI-1 reector building to 170 psig, a pressure significantly in excess of its design pressure of 60 psig. Therefore, t a nsfer of the gas is not a viable alternative.

1 g

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In preparing Addendum 2 to NUREG-0662, the NRC staff evaluated variations in the purging alternative in an attempt to minimize the duration of the recommended purge operation. In this evaluation, the staff determined that it would not be advisable to purge the reactor building as rapidly as physically possible since such a purge would most probably result in beta skin doses in unrestricted areas in excess of the design objectives of 10 CFR Part 50, Appendix I (Ref. 15).

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9.5.10 Pennsylvania Dutch Visitors Bureau (PDVB) l The POVB suggested that all future news releases relating to releases of radioactivity contain an explanation (in layperson's terms) of physiological and environmental impacts. The NRC TMI Program Office has issued an easy-to-understand report that answers questions most frequently asked about the proposed purge of krypton from the reactor building. This report states in layman's terms the potential health impacts likely to occur when the krypton is released. Copies of the report, " Answers to Questions about Removing Krypton from Three Mile Island, tJnit 2 Reactor Building "(NUREG-0673) are available free of charge by writing to the Division of Technical Information and Document Control U.S. Nuclear Regulatory Commission, Washington, D.C.

20556. In addition, Section 1.0 was written to provide a fairly complete discussion of the entire final assessment report for the layperson.

Section 7.0 of the final assessment also describes the health effects of the various alternatives for decentaminating the reactor building atmosphere.

9.5.11 Hershey Entertainment & Resort Company (HERCO)

HERCO requested that the purging operation be scheduled (consistent with safety) either prior to or just af ter the peak June - August tourism season. For the reasons described in Section 5.0, the NRC staff recommends that the purging cperation te performed soon. The information in Section 7.0 is provided to alleviate public concerns about the health ef fects of the purging cperatf or, ahich have been cetermir.ed to te negligible.

3-13 l

9.5.12 Oak Ridge National Laboratory (ORNL)

ORNL suggested a possible mechanism for alleviating some of the public concern regarding the preposed purge operation. Their suggestion was to encourage and fund local radiation monitoring efforts for the duration of the planned release. They further suggested that the Commonwealth of Pennsylvania should be requested to assist or oversee this effort. The DOE monitoring program described in Section 8.0 will function essentially as suggested by ORNL. Approximately 50 local residents have been trained to participate in monitoring the recommended purge operation.

9.5.13 Councilman and Director Department of Public Safety, City of Lebanon, Fennsylvania The Councilman and Director Department of Public Safety, City of Lebanon, Pennsylvania recommended a delay in the purging operation and asked for "a stronger, more concerted ef fort to establish a factual, responsible, pubile information source which may enjoy a greater degree of public confidence than that now experienced by the NRC.

the Governor's request for participation by the Union of Concerned Scientists may be a step in this direction."

Such a delay was granted and the UCS submitted their report to the Governor of Pennsylvania on May 15, 1980. The Governor subsequently stated that he was prepared to support the purging decision if the Commission proceeded with the purging proposal advanced by the NRC staff. He further stated:

"To minimize stress, I also am prepared to commit all of the resources al my disposal to assure the residents of the area, as I am now persuaded, that this plan is, indeed, a safe one."

9.5.14 West Shore School District li,e West Shore School District requested that approval of the purging operation be postponed until after the schools in the TMI area have closed for the summer. They further stated that most of these schools will close for the summer during the week of June 9.

The decision to extend the public comment period on NUREG-0662 to May 16, 1980 effectively granted this request.

9.5.15 Regional Planning Council The Regional Planning Counci' for the Baltimore, Maryland area tommented that while in previous statements it has supported the position that there should not be a release of radioactive material from the cleanup process before I

the preparation of an Environmental Impact Statement, it does recognize the need for timely action by the NRC when it finds that public safety requires release of material before the EIS is completed. They also commented that the Environmental Assessment falls to mention a deadline for release of the gas. They recommended that the purge operation be delayed until the Union of Concerned Scientists study requested by the Governor of Pennsylvania was completed. Since the UCS study has now been completed, the NRC staff recommends, for the reasons stated in Section 5.0, that the purging operation be performed soon and prior to completion of the Programmatic Environ-mental Impr-t Statement.

They also requested that Maryland health officials be notified in advance of the purge operation so that monitoring stations can be established by Maryland officials. The NRC staf f intends to provide at least a ten-day 3dvance notice to all pertinent officials, to the press, and to the public for the controlled purging cperation.

9.5.16 Additional Comments from Individuals in addition to the above-noted comments, approximately 90 additional responses were retelved from individuals who provided specific comments or, the alternative methods evaluated in NUREG-0662 or suggestions for additional methods for accomplishing the required decontamination. The additional comments or suggestions were broad

_ _. _ _. _.. ~

9-14 ranging. They included suggestions (1) to purge the reactor building atmosphare into balloons and release the contents at high elevations (2) to evacuate the residents in the TMI area during the purging operation, and (3) to modify the charcoal iJsorption process to minimize the quantity of charcoal required. Some persons urged that NRC staff members and officials be present in the IMI area during the purging operations, expressed concern about possible releases of other radioactive materials, questions differences in the quantities of Kr-85 reported by the licensee (44,000 curies) and by the NRC staf f (57,000 curies) and worried that additional quantities of fission products are continuing to be generated. One person recommended that the cleanup operation be performed by the Naval Reactors Branch of DOE. Several other persons suggested that any necessary maintenance and repairs within the reactor building could be performed by workers dressed in protective clothing without prior removal of the Kr-85.

A number of letters suggested that the krypton gas be placed in high-altitude balloons and transported for release high in the atmosphere. Although high* altitude balloons are technically feasible as an alternative to Controlled purging, their use could increase the risk of an uncontrolled release that could result in higher radiation exposures to the workers and the public than would occur from the alternatives discussed in this report.

A large number of balloons would be required and they would have to be of immense voluse because krypton-85 is a heavier-than-air gas which would require the addition of helium gas or lif t capability to the balloons as a volume ratio of approximately 30 times that of krypton-85. Moreover, the probability for a balloon burst is fairly high.

Based on the National Oceanic and Atmospheric Administration experience with high-altitude weather balloons, the chance of no balloon burst is in the range between 75 to 85%, but can drop as low as 50% during periods of gusty winds. This probability, coupled with the large number of balloons that would be necessary (assuming krypton-85 is transported as a gas), would increase the overall probability of a premature balloon burst. Solutions would then need to be devised for retrieval and disposal of the contaminated balloons. Finally, use of balloons for transporting radioactive gas may further aggrevate the psychological stress of some residents in the THI area due to the obvious visibility they would provide. In summary, since the radiological health effects associated with the recommended purging operation are negligible, and since the probable disadvantages outweigh the advantages of using balloons in transporting and remotely releasing the Kr-85 gas, use of this concept is not recommended.

o Recommendations that local residents be evacuated during any purging operation were based on the assumption that an evacuation would protect residents f rom any radiological hazards associated with the release of the Kr-85.

However, as discussed in Section 7.0, the adverse radiological health effects of the recommended purging operation will be negligible and, therefore, evacuation of the local residents is neither required nor recommended.

The suggested variation in the charcoal adsorption process recommends that three containers of charcoal to be used.

In this variation, the reactor building atmosphere would be filtered, dried, refrigerated, and passed over ref rigerated charcoal until krypton breakthrcugh occurred in the first container. The krypton in this first container would then he desorbed by admitting heated and humidified air.

The desorbed krypton would be transferred to a second refrigerated container of charcoal for storage. The adsorption and desorption in the first container would then be repeated for several cycles. Although the charcoal loses its ability to adsorb krypton with ircreasing humidity, this ability is only decreased in magnitude, it is not eliminated. SIgnifiCant holdup is still obtained at high humidity, and desorption would not be easy. Therefore, transfer of krypton, as the proposal suggests, cannot be espected as easily as stated. Since this concept is the basis for the entire proposal, the rest of the proposal simply does not follow and its further consideration is not recommended.

Several suggestions were made that NRC staff members and officials be present in the IMI area during the purging operations. The reasons for these suggestions included that their presence would be a demonstration of confidence in statements by the NRC staff that the radiological health effects are negligible. Members of the NRC professional staff would be at, and in the vicinity of, TMl daring purging operations to oversee these operations.

F15

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10-1 10.0 Public Information Activities In an ef fort to better inform the public in the area around Three Mile Island about the contents of the draf t Environmental Assessment (NUREG-0662, and Addenda 1 and 2), NRC has conducted 38 informational meetings and activities. The staff also issued an easy-to-understand report that answers frequently asked questions about removing the krypton from the reactor building. Copies of the report, " Answers to Questions about Removing Krypton from the Three Mlle Island Unit 2 Reactor Buildinq" (NUREG-0613), are available free of charge by writing to the Division of Technical Information and Document Control, U.S. Nuclear Regulatory Commission, Washington, D.C.

20555.

Most of the meetings held were planned by the NRC, although some were organf red by other interested groups, at which NRC officials were invited participants. Members of the U.S. Environmental Protection Agency and the Pennsylvania Department of Environmental Resources (DER) were usually invited participants at these meetings. EPA officials outilned their agency's program and responsibilities for environmental monitoring in the vicinity of the TMI site, while state DER personnel explained the community monitoring program and other state functions related to the clean-up of TMI Unit 2.

At these meetings, NRC of ficials expressec. heir willingness to meet with other groups of people who had an interest in receiving additional information on the Environmental Assessment or clean-up operations at Unit 2.

This effort of communicating with the public fell into three broad categories:

1 15 public meetings and meetings with interested citizens groups, 16 meetings with elected officials, and 7 press conferences and appearances on public information radio and television shows.

10.1 Public Meetings and Meetings with Interested Groups On March 19, 1980, NRC conducted a public meeting in Middletown to inform local citizens of the contents of the draft Environmental Assessment. Following this initial meeting, NRC officials attended similar gatherings in surrounding communities at the request of state and local officials.

The NRC staff also met with a wide variety of interested groups which included:

Chambers of Commerce Civic Service Organizations Medical Associations School Board Officials Religious leaders Teacher Organizations ihree Mile Island Alert Meetings with the Capital Forward Group and Three Mile Island Alert were attended by Chairman Ahearne and Comnis-stoner Hendrie, respectively, in addition to NRC staff participation.

10-2 10.2 Briefings for Elected Officials In addition to meeting with Governor Thornburgh, Harold Denton, Director of the Of fice of Nucles.r Reactor Regulation, and other members of the NRC staff met with various city officials from major metr 9politan areas surrounding Three Mile Island. Meetings were held with the Commissioners and other officials from the four counties closest to IMI: Dauphin, Lancaster, York, and Lebanon. Five briefings were alsa conducted in dif ferent geographic locations for elected officials from the Boroughs and Townships which surround Three Mile Island.

10.3 Press Conferences and Television and Radio Appearances Harold Denton held several press conferences in central Pennsylvania, one of which was held jointly with Governor Thornburgh to discuss the Environmental A'ssessment. John 1. Collins, Deputy Program Director, TMI Program Office, appeared on several television and radio talk programs where listeners or panel members asked questio% concerning the tc. 'eanmental Assessment. These appearances by Mr. Collins were in addition to his numerous other television and ra n, interviews concerning a wide range of topics relating to activities at tha 'N site.

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11-1 11.0 References 1.

Matropolitan Edison Company "Three Mile Island Unit 2 Reactor Building Purge Program Safety Analysis and Fnvironmental Report," Docket 50-320, November 13, 1979. (PDR)*

2.

U.S. Nuclear Regulatory Commission, " Environmental Assessment for Decontamination of the Three Mile Island Unit 2 Reactor Building Atmosphere - Draft NRC Staff Report for Publi: Comment," USNRC Draft report NUREG-0662, March 1980. (DTIDC) 3.

Union of Concerned Scientists, " Decontamination of Krypton-85 f rom Three Mile Island Nuclear Plant," A Report to the Governor of Pennsylvania, May 15, 1980. (PDR) 4.

Letter f rom R. H. Vollmer, NRC, to R. C. Arnold, Metropolitan Edison Co.,

Subject:

Reactor Containment Building Atmosphere Cleanup, Docket 50-320, December 18, 1979. (PDR) 5.

Letter from J. T. Collins, NRC, t' '

F. Wilson, Metropolitan Edison Co.,

Subject:

Additional Inf ormation Request for Preparatic.. of Environmen'.! Assessment, Docke' 50-320 December 18, 1979.

(PDR) t 6.

Letter f rom R. F. Wilson, Metropolitan Edison Co., to J. F. Collins, NRC,

Subject:

Response to 33

]

Questions on Reactor Containment Building Atmosphere Cleanup Docket 50-320, January 4,1980.

(PDR) 7.

U.S. Nuclear Regulatory Commission, " Statement of Policy and Notice of Intent to Prepare a Programmatic Environmental Impact Statement." (PDR) 8.

U.S. Nuclear Regulatory Commission, " Order by the Director of the Office of Nuclear Reactor Regulation,"

Docket 50-320, February 11, 1980. (POR) 9.

U.S. Nuclear Regulatory Commission, Rules and Regulations, Title 10, Code of Federal Regulations Part 20, Appendix B. Table 1.

(PL) 10.

Metropolitan Edison Company. " Technical Evaluation Report for Submerged Demineralization System (505),"

l April 10, 1980. (PDR) 11.

U.S. Nuclear Regulatory Commission, Rules and Regulations Title 10, Code of Federal Regulations Part 50,

" Licensing of Production and Utilization facilities," March 1975, Appendix I, " Numerical Guides for Design Objectives and Limiting Conditions for Operatic to Meet the Criterion as low as Practicable for Radioactive Material in Light-Water-Cooled Nuclear Powe Reactor Effluents." (PL) 12.

U.S. Environmental Protection Agency, Rules and "squic-. ions, Title 40, Code of Federal Regulations Part 190 " Environmental Standards for the Urant m Fo+1 Cycle," January 1977. (PL) 13.

Three Mile Island Nuclear Station, Unit 2, Environmental Technical Specifications, Appendix B to Operating License DPR-73. February 8, 1978. (PDR) 14.

U.S. Nuclear Regulatory Commission Regulatory Guide 8.8, "Information Relevant to Ensuring That Occupational Radiation Exposures at Nuclear Power Stations Will Be as Low as Is Reasonably Achievable."

(PDR, GPO)

• For in'-rSation on document availability, see Page 11-4.

l

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11-2 15.

U.S. Nuclear Regulatory Comission, Regulatory Guide 1.109, " Calculation of Annual Doses to Man f roe Routine Releases of Reactor Effluents for the Purpose of Evaluating Compliance with 10 CFR Part 50, Appendix I."

(POR,GPO) 16.

U.S. Nuclear Regulatory Correissicq, " Supplement to the Final Environmental Impact Statement for Three Mlle Island, Unit 2 " Docket 50-320, USNRC Report NUREG-0112, Cecerber 1976. (DTIDC) 17.

U.S. Nuclear Regulatory Coausission, "Pepulation Oose and Health Impact of the Accident at the Three Mile Island Nuclear Station," USNRC Report NUREG-0558, May 1979. (DTIDC) 18.

U.S. Nuclear Regulatory Comission Rules and Regulations, Title 10 Code of Federal 8eculations Part 100, " Reactor Site Criteria," September 1,1978. (PL) 19.

U.S. Nuclear PegulaNry Commissicn, Rules and Regulations Title 10 Code of Federal Ee;ulations Part 20

" Standards for Protection Against Radiation," June 1977. (PL) 20.

MPR As ociates, Inc., "Three Mile Island Unit 2 Containment Atmosphere Cleanup Alternate Syster.

Evaluation," Docket 50-320, Septeter 14, 1979. (PCR) 21.

U.S. Nuclear Regulatory Comission, Regulatory Guide 1.143, " Design Criteria for Radioactive Waste Management, Systems, Structures, and Coeponents Installed in Light Water Cooled Nuclear Power Plants."

(POR, GPO) 22.

J. R. Merriman, J. A. Parson, R. C. Riepe, and M. J. Steptenson, Oak Ridge National Laboratory, "Use of the CRGDP Selective Absorption Process for Gemoval of Krypton from the Containment Building Atmosphere at Three Mile Island, Unit 2," May 6, 1980. Available from ORNL, Oak Ridge, Tennessee 37830.

23. National Council en Radiation Protection and Measurecents, " Krypton-85 in the Atmosphere - With 5pecific References to the Public Health Significance of the Proposed Controlled Release at Three Mile Island,"

May 16, 1980. (PCR) f 24.

National Council on Radiation Protection and Measurements, " Krypton-85 in the Atmosphere -- Accumulation, Biological Significance, and Control Technology." July 1, 1975. Available free NCRFM, Washington, OC.

25.

National Academy of Sciences, Cemtttee on the Biological Ef fects of Ionizing Radiations, (1979 draf t report) "The Effects on Populations of Exposure to to. Levels of Icnizing Radiations," 1979. (PCR) 26.

U.S. Neclear Regulatory Comission. " Reactor Safety Study -- An Assessment of Accident Risks in U.S.

Conriercial Nuclear Po er Plants," Appendia VI, WASH-1400 (NUREG-75/014), Octode, 1975. (DTIDC) 27.

National Academy of Sciences Advisory Ccemittee en tre Biological Ef fects of lenizing Radiation, "The Effects on Populattens of Espesure to Low Levels of Ionizing Radiation," Novercer 1972. (PDR) i 28.

Letter from W. N. Hedeman, Jr., to Q. H. Yollser, NEC,

Subject:

Draft Environmental Assessment for Cecontamination of the Three Mile Island Unit 2 Reactor Building Atmosphere " (NUREG-0662 plus Addendues 1 and 2), dated April 11, 1990. (PCR) 4

,m

11-3 29.

American Cancer Socie'.y. "1979 Cancer Facts and Figures," 1978. Available from ACS, New York.

30.

E. Pochin, "The Acceptance of Risk," British Medical Bulletin 31, 3, 184-190 (1975). Available from public technical libraries.

31.

J. G. Kemeny, " Report of the President's Commission on the Accider.t at Three Mile Island," U.S.

Government Printing Office, Washington, DC, 1979. (DTIDC) 32.

M. Rogovin and G. T. Frampton, Jr., (NRC Special Inquiry-Group), "Three Mile Island, a Report to the Commissioners and to the Public," April 5, 1979. (DTIDC) 33.

U.S. Environmental Protection Agency, " Estimates of loriring Radiation Doses in the United States " EPA Publication ORP/C50 72-1 (1972). Available from EPA, Washington, DC.

34.

U.S. Environmental Protection Agency, " Natural Radiation Exposure in the United States," EPA Publication ORP/510 72-1 (1972). Available from EPA, Washington, DC.

35.

A. Weinberg, International Conference of Radiology and Radiation Biology, Seattle, Washington, July 15, 1974, cited in F. H. Schmidt and D. Bodansky, The Energy Controversy: The Light Over Nuclear Power, University of Washington, 1976. (PL) 36.

U.S. Environmer*, Protection Agency, " Radiological Impact Caused by Emissions of Radionuclides into the Air in the C..ited States," EPA Publication 520/7-79-006 (1979). Available from EPA, Washington, DC.

37 B. P. Dohrenwend, et al.

" Technical Staff Analyses Report on Behavioral Effects: To the President's Commission the Accident at Three Mile Island," October 1979. (PDR) 38.

P. 5. Houts, et al,, " Health-Related Behavioral Impact of the TMI Nuclear Incident: Report Submitted to the TMI Advisory Panel on Health Research Studies of the Pennsylvania Department of Health," Part I, April 1979. (PDR) 39.

C. B. Flynn, Mountain West Research, Inc., "Three Mile asland Telephone Survey: Preliminary Report on Procedure of Findings," USNRC Report NUREG/CR-1093, October 1979. (DTIDC) 40.

Memorandum from D. P. Cleary, to W. H. Regan

Subject:

"THI-2 Atmospher:c Decontamination," May 1,1980, g

reporting on a talephone conversation of April 21, 1980, between B. P. Dohrenwend and D. P. Cleary.

(PDR) 41.

Memorandum f rom D. P. Cleary, to W. H. Regan, subject:

"THI-2 Atmospheric Decontamination," May 27, 1980, reporting on an telephone conversation of May 9, 1980, between G. J. W3rhect and D. P. Cleary.

(PDR) 42.

A. Baum, " Psychological Stress and Alternatives for Decontamination of Reactor Building Atmosphere,"

USNRC Draft Report. To be issued as a formal NRC report in June 1980.

i 43.

Science Applications, Inc., " Comparison of Controlled Purge and Application of the Selective Absorptinn Process Alternatives for Decontamination of TMI-2 Reactor Building Atmosphere," May 1980. A copy is bound into Volume 2 of this Assessment.

11-4 NRC documents referenced in this report are available from the following sources:

(PDR) - USNRC Public Document Room,1717 H Street, N.W., Washington, DC 20555. Available for inspection and copying for a fee.

(DTIDC) - Copies are available for sale from the Pubitcations Sales Manager, Division of Technical Information and Document Control, USNRC, Washington, DC 20555. Single copies of draft reports are available f ree of charge f rom the same address.

(PPR, GPO) - Copies are available from the NRC FOR for inspection and copying for a fee, and from the U.S.

Government Printing Office, Washington, DC 20402, Attn: Regulatory Guide Account.

(PL) - Available from a public library.

12-1 4

4

12. Glossa ry Absorbed dose - The energy imparted to matter by ionizing radiation.

l Anticipated Operational Occurrence - Miscellaneous conditions or actions such as equipeent f ailure, operator error, i

administrative error, that are expected to occur that are not of magnitude great enough to be considered an accident.

{

Background radiation - Radiation arising from natural radioactive saterials always present in the environment, including solar and cosmic radiation and radioactive elements in the upper atmosphere, the ground, building mate-rials, and the human body.

In the Harrisburg area the background radiation level is about 125 arem per year.

Beta parcticles - Charged particles emitted f rom the nucleus of a atom, with a mass and charge equal in magnitude to that of the electron.

j 4

Cf M - (ubic feet per minute Contr;1 rod - A rod containing material that absorbs neutrons; used to control or halt nuclear fission in a reactor.

I Core - The part of a nuclear reactor that contains the fuel (fissionable saterial). In a reactor like that at TMI, the r.gion containing fuel-bearing rods.

Critica - Tere used to describe the capability of sustaining a chain reaction at a constant level.

Cryogeric Processing - tow-temperatue separation processrs whereby materials that are normally gases are isolated and recow. red f rom other gases by liquifying thee at lo= teeperatures.

Cubic Centi eter (ce) - Unit f or seasuring valuee. Approximately 947 cubic centimeters is equal to one U.S. quart.

Curie (Ci) - The special unit of radioactivity. Activity is defined as the numoer of nuclear transformations occur-ring in a given quantity of material per unit time.

Decay heat - Heat produced by the decay of radioactive particles; in a nuclear reactor this heat, resulting from materials lef t f rom the fission process, must be removed af ter reactor shutde=" to prevent the core from over-beati ng.

See Radioactive decay.

Dose - Denotes the quantity of radiation or energy absorbed. For special purposes it must be appropriately qualf-fied.

If unqualified, it refers to absorbed dose. See Absorbed dose.

Dosimeter - Dose seter. An instrument that measures radiation dose. See TLD Camma rays - Short = ave length electromagnetic radiation of nuclear origin esitted from the nucleus of an atos. A form of ionizing radiation.

12*2 Malf-life - Tt4 tise required for half cf a given radioactive sut) stance, decay.

NEPA - High-ef fiClercy particulate filter.

Ionization - Tre process try =%fch a ceutral atm or selecule acoutres a positive or a negative charge.

Icotting Radiation - Any fees of radiation that displaces electrons f rom atees or eclecules. Tr4 resalting atte or molecule is an ion.

lons C+come electrically charged as a result of this process.

Krypton An inert noble gas (it dc45 ret irteract crenically =tth cteer cresical eleoeets or coepou 4s) alth a r

half-iffe of 10.7 years.

@ - Linear energy transfer. A seasure of tP4 capacity cf biolegical saterial to atsort lonizin; radiaticm.

g - Minism Detectable Activity. Minisys lenel of radioactivity detecta01e with witort'v; festruments.

Metecrolcotcal ou;arsion f actor (r/Q) - A f acter (secoMs/s ) which accounts fer site-specific seteorological 2

data in relating tP4 concentration (C1/s ) of radioactime saterials, at a given location, to a release rate 3

(Ci/sec) cf radicactive saterial et anotter location.

uf erecurie (oC1) - t; nit f or seasuring radioactivity. Or4 sicrocurie is one-silliceth cf a curie (1/1,0CC.C<C).

See curie.

wilitcurie (=Cl) - 1.mit for sensoring radicactivity. One silitcu-ie is er4-thcusaMth (1/1,CCO) cf a curie.

Wi11 t ree (aree) - Cr+ cre-thousaMth (1/10CC) cf a ree; see M.

$ - Manisus Femissible Cor<entratien of radicactive esposure, as specified in Title 10 Code of feceral Ecgr lations, Part 20. Ta:1e B.

hoble gases - Ire-t gases that oc net readily react c*+eically micct*e* elenents. f **se gases inc1we relius, neco, krypton, senen, aM racce, 4xlear Ee;ulatery Cweissien (%C) - U.S. a;evy rescensitte fer t*e lice sta.;, regalatf cn, av te.s;+ctico of coarsecial, test, aN research r clear reactors, as =+11 as nuclear saterials.

l Ceder o' magnitwe eithin a facter of 10.

Perscn-ress - The sus of the individal doses recefied by each secer cf a certain geci.: ce poc latica. It is calculated by suitiplying tre a.erage dese per ;4rson ty the rNacer of gersens. Ccese w ily, t*e collective ese j

is estressed in person-reits. Fcr esascle, a t*cwav peccie each espcsed to cae aren whid have a collective 6:se l

cf 1 person-res.

Q - PovMs per square inc% ga:.p;e.

A seasure of tre cif ference in pressure atene ce telcw ecr%al at,sesperic pressure.

i r,ad - TPe basic eit of absceted ccse of icnitity raaf attom A cose of ore rad means tN atsc-ctice cf IX ergs of radiation energy per gram of atserting saterial.

s

l 12-3 Radiation - Energy in the form of rays (light, heat X-ray, radio waves) sent out through space from atoms and molecules as they undergo internal change.

Radioactive decay - The spontaneous natural process by which an unstable radioactive nucleus releases energy or particles to become stable.

Radioactivity - The spontaneous decay of an unstable atom. During the Jecay process, lonizing radiation is usually given of'.

Rey.'.or (nuclear) - A device in which a fission chain reaction can be initiated, maintained, and controlled.

Reactor buildina - The structure housing the nuclear reactor. Also called containment building or reactor containment building.

Reactor vessel

• Ihe stGel Vessel Containing the reactor Core; also Called pressure vessel.

Rem - A standard unit of radiation dose. Frequently radiation dose is measured in millirems for low-level radiation; 1,000 millfrems equal one rem.

SCFM - Standard Cubic Feet Per Minute. " Standard" refers to standard conditions of pressure and temperature.

Selective Absorbtion Procell - A eparation process whereby a liquid is used to selectively absorb (separate) a selected material (gas) from a source gas stream (air).

Source Term - Defines an amount of radioactive material.

Il0 (thermoluminescent dosimeter) - A solid-state device used to measure nuclear radiation doses. See Dosimeter.

Tritium - A radioactive isotope of hydrogen.

Wake-Cavity Ef fect - The region of turbulance immediately to the rear of a solid body, like a building, that is formed when wind currents flow over and around the object.

X/Q - See Meteorological Dispersion Factor.

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I

"' "" 336 U S NUCLEAR REGULATO3Y COMMIS$10N (7 77)

BIBLIOGRAPHIC DATA SHEET

}

4 TETLE AND SUBTsTLE LAdd Volume No. otwormnotel

~

NUREG-0662, Volume 1 2 (Lena bleh)

Final Environmental Assessment for Decontamination of the Three Mile Island Unit 2 Reactor Building Atmosphere

3. RECIPIENT'S ACCESSION NO.

7. Au f HO R tS)

5. D ATE REPORT COMPLE TED M ON TH l DEAR i

May 1980 I

9 PE RFORMING ORGANIZATION N AME AND M AILING ADDRESS (include I,p Coor/

DATE REPORT ISSUED l

TMI Program Office M*y'"

l ! *g*8O Office of Nuclear Reactor Regulation l

U.S. Nuclea; Regulatory Commission 6*""

1 8 (Leave omel

12. SPONSORING ORGANIZATION N AME AND M AILING ADORESS (incluar 2,p Coorf L

Same as 9 ti. CONTR ACT NO 13 TYPE OF REPORT PE Rf 00 COVE RE D (inclus+e dares)

Final NRC Staff Report f

15. SUPPLEMENTARY NOTE S 14 (Leave we61

16. ABSTR ACT GOO words or less!

This final Environmental Assessment evaluates the environmental impacts of alternative methods for decontaminating the reactor building atmosphere at Three Mile Island, Unit 2 and incorporates comments on de ontamination alternatives from Federal, State, and local officials and from private citizens and groups.

The staff recomends that the reactor building be purged over a 60-day period.

i

.l 17 KE Y WOHOS AND DOCUME NT AN ALYSIS 17a DE SC RIP T ORS i

i 17n IDENTIFIE RS OPEN E NDED TE RYS r

)

18 AVAIL ABillTY ST ATEVE NT i s SE CU RI T Y C L A S5 tT* s vomrf 21 NO Oc PAGE S I

20 SE cum Tv CL ASS t T* s cari 22 PRsCE Unlimited s

NRC FORu DS 417 ts

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