Text

Decontamination of Kr-85 from TMI Nuclear Plant, Rept to Governor of PA
	ML19317H393
Person / Time
Site:	Crane
Issue date:	05/15/1980
From:	Beyea J, Bridenbaugh D, Kendall H; UNION OF CONCERNED SCIENTISTS
To:	;
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	NUDOCS 8006040047
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DECONTAMINATION OF KRYPTON-85 FROM THREE MILE ISLAND

_ NUCLEAR PLANT THIS DOCUMENT CONTAINS POOR QUAUTY PAGES l

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1 Tb-BF A REPORT OF THE UNION OF CONCERNED SCIENTISTS TO THE GOVERNOR OF PENNSYLVANIA

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MAY 15, 1980 4

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,6 DECONTAMINATION OF KRYPTON-85 FROM THREE MILE ISLAND NUCLEAR PLANT Study Dire: tor Henry W.

Kendall Study Membcre Jan Beyea Robert Pollard Dale =G.

Bridenbaugh Edward Radford Gregory C. Minor Frank von Hippel (Reviewer)

A REPORT OF THE UNION OF CONCERNED SCIENTISTS TO THE GOVERNOR OF PENNSYLVANIA MAY 15, 1980 A,,

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THE UNION OF CONCERNED SCIENTISTS 1384 Massachusetts Avenue Cambridge, Massachusetts 02238 617-547-5552

({) copyright Union of Concerned Scientists 1980 1

The Union of Concerned Scientists is a non-profit tax exemp coalition of scientists, engineers and other professionals concerned about the impact of advanced technology on society.

l UCS has conducted a series of independent technical studies on a wide range of questions relating to nuclear power plant safety,. radioactive waste disposal options, nuclear arms race issues, energy policy alternatives and Liquefied Natural Gas transport and storage hazards.

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TABLE OF CONTE.'TS Members of Study Acknowledgements 1-I.

Introduction II.

The Krypton Problem 2.

A.

Radiation Levels 9-B.

Need for Reactor Building Entry 1.

Introduction 2.-

Reactor Building Integrity 3.

Reactor Coolant System Integrity 4.

Safeguarding Against Accidental Criticality 5.

Conclusions on Need for Entry 19.

C.

References III.

Venting 20.

A.

Gs eral Considerations in Venting

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21.

Radiation Exposure and Direct Health Effects B.

27.

C.

Stress-Related Public Health Effects 29-D.

Elevated Release 1.

Introduction 2.

Hot Plume i

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Tethered Balloon

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b IV. e Krypton Recovery A.

, Introduction 46.

B.

Selective Absorption 46 C.

Cryogenic Processing 49.

D.

Gas Compression and Charcoal Adsorption 51.

V.

Findincs and Recommendations A.

Findings 53.

B.

Recommendations 57.

Appendices I.

Incinerator Information 58.

II.

Tethered Balloon 61.

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Members of The UCS Studv Group Jan Beyes, Ph.D, Nuclear Physicist and Senior Energy Scientist with the National Audubon Society.

Specialist in airborne dispersion and radiation effects from aitborne releases of radioactivity.

Dale G. Bridenbaugh, BSME, PE Mechanical Engineer.

Partner MHB Techaical Associates.

Former manager of (Nuclear Plant) Performance and Improvement, General Electric Nuclear Energy Division.

Henry W. Kendall, Ph.D, Experimental Physicist in elementary particle physics.

Professor of Physics at Massachusetts Institute of Technology and Chairman, Union of Concerned Sicientists.

Gregory C. Minor, MSEE Electrical Engineer.

Partner MHB Technical Associates.

Former manager Advanced Control and Instrumentation Engineering, General Electric Nuclear Energy Division.

Robert D. Pollard, BSEE Nuclear Safety Engineer, Union of Concerned Scientists. Formerly Licensing Project Manager, Nuclear Regulatory Commission.

Edward Radford, M.D.

Professor of Environmental Epidemiology, Graduate School of Public Health, University of Pittsburgh.

Chair National Academy of Sciences Advisory Committee on Biological Effects of Ionizing Radiation (BEIR).

Frank von Hippel, Ph.D (Reviewer of the UCS Study. )

Theoretical Physicist.

Senior Research Physicist, Center for Enviromental and Energy Studies, Princeton University.

American Physical Society Reactor Safety Study add NRC Risk Assessment Review Group specialiring in reactor accident consequence and strategies for their mitigation.

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Acknowledgements The Union of Concerned Scientists (UCS) wishes to ex-press i.ts appreciation to Governor Richard Thornburgh of Pennsylvania and his staff, especially Mssrs. Roland Page and Paul Critchlow for-their help and support throughout the course of the study.

Tom Overcamp, Associate Professor in Clemson University's Department of Environmental Systems Engineering, provided much valuable advice and carried out useful calculations _

in support of our proposed het plume venting scheme.

UCS is grateful to the Office of the Secretary of the Air F,orce, Hans Mark and to the Office of the Under Secretary of Defense, William Perry, for help they provided.

Tom Kelly and his associates of the U.S. Air Force Geo-physical Laboratory made numerous suggestions and calculations bearing on tethered balloon technology.

We thank them.

We extend thanks to Walter Martin of the Office of Naval Research, Jean Nelson of Winzen International, Inc.,

George Rathjens of M.I.T., Bruce Preston of Public Service Electric and Gas, Arthur Winters of Air Products and Chemicals, Inc., Milton Lytton of Mitre Corporation, Ward Diethorn of Pennsylvania State University, and Evelyn Bromet, Ph.D.

of the University of Pittsburgh.

We benefited greatly from discussions with representatives of the citizens groups which comprise the TMI Legal Fund.

We wish to thank Robert Arnold and his associates of Metropol' tan Edison, and Harold tenton, Bernard Snyder,

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and John Collins of the Nuclear Regulatory Commission for their cooperation in supplying the quantity of information I

we requested.

The. National Audubon Society (Russell Peterson, President) very kindly allowed Dr. Beyea to join our study.

a physicist on the UCS staf f, provided important Jim Leas, information on Krypton recovery and storage techniques.

Finally, we ac9.nowledge the support and aid provided by the UCS staff in Cambridge and Washington, especially Janice Candelora, Andrea Fishman, and Bette Pounders.

(The cover page illustration represents the radioactive decay scheme of krypton-85.)

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INTRCDUCTICM During the accident at the Three Mile Island (TMI) nuclear plant which started March 28, 1979, extensive melting of the reactor fuel released substantial quantities of the' accumulated radioactive fission products into the reactor coolant system and reactor building.

Among these was much of the radioactive krypton-85.

The physical quantity of krypton is very small, no more than a few cunces it would occupy about 1 3 cubic feet if isolated.

Unfortunately, it is uniformly mixed with the roughly 2 million cubic feet of air in the sealed Three Mile Island Unit 2 reactor containment building.

Krypton is the 36th element in the periodic table.

At room temperature it is a gas with a density three times that of air.

From its position in the periodic table a chemist would at once know that it has little chemical activity; indeed, it is classified as inert.

The nuclear physics of krypton is far more varied.

There are twenty-one isotopes of krypton.

Chemically they are identical, but their nuclear masses differ.

Six of these isotopes are stable, but the remaining fifteen are all radioactive to some degree.

In the fission chain reactions that split the uranium nuclei, about 0.3% of the fiss. ions yield Kr-85, with a radioactive half-life of 10.7_ years.

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2 The krypton-85 is biologicallyhazardous because of Short-range beta particles emitted by the its radioactivity.

krypton-85 can irradiate skin or other tissue and its more penetrating gamma radiation can cause whoic body irradiation.

As we discuss below in more detail, worker entry into the TMI reactor building in order to carry out maintenance, inspection, and werk associated with decontamination of the plant is substantially In the upper levels hindered by the presence of the krypton.

the krypten appears to be the source of of the reactor building, most of the damaging radiation and thus poses the mest important restriction to free worker access.

' The Union of Concerned Scientists (UCS) Study Group believes that ultimate decontamination of the plant is an absolute l

. Decontamination must include ecmplete remova necessity.

of the damaged fuel rods and of the contaminated water.in the The plant cannot be sealed and containment sump and elsewhere.

This would constitute a negligent disposal walked away from.

Important means for a very large quantity of radioactivity.

quantities of these toxic materials would ultimately find their way into the environment during the tens or hundreds of thousands of l

years that some of them will remain hazardous.

Accordingly, UCS has concluded that the krypton must be removed from the TMI reactor building so that an orderly

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program of decontamination can be undertaken. The prcolem is how to do this in a manner which ' protects the safety of the workers who may be exposed to the krypton and also safeguards the physical and mental health of members of the public who may also be exposed.

Based on arguments emphasi=ing the need for prcmpt entry into the reactor building and calculations that claim to show small or negligible consequences to the public, Metropolitan Edison (Met Ed) has proposed to vent and flush the reactor building through a 160 foot vent pipe located '

near ths. building over a period of from 5 to 50 days.

The Nuclear Regulatory Commission (NRC) staff indicated its initial approval of this scheme.

The radioactive plume from this release would mix in the turbulent wind-induced wake downwind of this building and, in some wind directions, in the wakes of the cooling towers.

Some of the radioactive gas would therefore hug. the ground.

This would result in beta and gamma radiation doses to persons exposed to-the contaminated wind.

For this reason we refer to this venting scheme as a " ground-level" release.

This Met Ed and NRC proposal to conduct ground level venting has resulted in inmense anxiety and considerable resistance in a significant portion of the population near the plant. This population was subject to the lengthy trauma of tha accident itself and to the subsequent efforts, not entirely successful, to prevent unexpected leaks of radio-activity.

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4 On March 28, 1980, Pennsylvania Governor Richard Thornburgh asked UCS to make an independent evaluation of

. the krypton 41em.

The UCS Study Group evaluated the need for containment enrry, the urgency of that need, the impact of the ground level venting of the krypton, and the advantages and disadvantages of the four alternative krypton recovery schemes rejected We by Met Ed and the NRC in making their choice to vent.

also searched for solutions to the krypton problem not

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previously proposed.

Because the NRC staff and Met Ed had announced their ' decision to vent before the UCS meeting with Governor Thornburgh and because the NRC has the legal authority to allow the venting to proceed and wishes to do this promptly, UCS was under great pressure to complete its study in a most rapid manner. We have done so.

Barely a month could be devoted to the task, from its inceptior.

to the delivery of our conculsions to Governor Thornburgh and to the public.

This is our report.

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THE KRYPTON PROBLEM i

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Radiation Levels l

i The difficulties posed by the krypton-85 in the contain-ment aris~e from its radioactivity.

As shown in Figure 1, krypton-85 decays dominantly by emission of beta particles of maximum energy 0.67 MeV.

However, 0.4% of the krypton atoms decay with a icwcr energy beta spectrum acccmpanied by a gamma ray of 0.514 Mev.

The amount of krypton-85, expressed as radioactivity, is about 57,000 curies.

Because of the biological hazard ~

j posed by the radiation, this is by no means a small quantity.

Beta particles travel only a short distance in human tissue, so the principal injury from exposure outside the body is to the skin or, if the gas is inhaled, to the lungs and to other tissues of the body to which krypton-85 may be carried if dissolved in the blood.

Conventional radiation protective clothing does not, rovide sufficient protection to workers against the beta particles.

A heavy diving suit with breathing apparatus is required for adequate protection for workers who would encounter the gas but work in such gear is awkward and the suit is subject to leaks or other failure.

The gamma rays are more penetrating and cannot be effectively stopped by sty practical protective clothing of any sort.

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produce whole body radiation exposure.

Ramoval of the krypton-85 will not significantly reduce the gamma radiation to workers in the lower part of the contain-ment.

The.gedioactive materials concentrated in the 600,000 gallons of water in the building sump are a far more intense source of gamma radiation.

Some surface deposition, or

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Ra The radioactive decay scheme' of the fission product krypton-85.

The branching ratios, lifetimes and gamma energy and beta spectrum end point are shown.

The stable daughter nuclide is rubidium-85.

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However, in the upper portions of the containment where successive concrete floors provide signifi-

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l cant shie'iding from gamma radiation originating in the sump, the beta exposure from the krypton appears to be the principal hazard to entering workers.

The estimated radiation levels in the containment building with the krypton present are shown in the following tables.

The estimates were provided by Met Ed personnel.

UCS has no way to verify these numbers or estimate the uncertainfies in them, but they appear to be reasonable.

Gamma Radiation Levels (REM / hour)

Sump, just above water surface 125 15 ft. above water, at 305 ft. building elevation:

Radioactive plate out 0.26 Kr-85 0.66 Sump water 1.08 a_1 sources 2.0 57 ft. above water, at 347 f t. building elevation:

Radioactive plate out 0.4 Kr-85 1.1 All sources (total) 1.5 b7.4

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8 Beta Radiation Levels (REM / hour)

All locations, dcminated by kr-85 No protective clothing 200-300 Special protective clothing (with minor leaks) and with self-contained breathing equipment 9

To put the gamma levels in perspective, one should note that less than one hour occupancy at the su=p level would induce acute radiation sickness and would increase the exposed individual's risk of eventually developing cancer by several percent.

Three hours occupancy would result in a nearly even chance of death within weeks.

A one hour exposure to beta levels exceeding 200 REM /hr would lead to increased risk of skin and lung cancer.

While the precise relationship between dose and outeeme is not known, there is no question that such a dose is exceedingly unwise.

Indeed, even individual beta skin exposures at the 10 REM level should be avoided if at all possible.

In ~ summary, there is no question, in our view, that removal of the krypton. is necessary before decontamination work in the containment can proceed.

The central considera-tion 'for worker protection is the need to minimize their exposure to the krypton beta radiation.

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Need For Reactor Buildina Entry 1.

Introduction There appears to be no significant disagreement about

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the ultimate need for worker access to the TMI-2 reactor building.

Relatively free personnel access will eventually be necessary to remove the damaged fuel and to decontaminate the reactor coolant system and reactor building.

No one knowledgeable of the type and quantity of radioactive material present in the damaged plant would ever suggest that the plant could be abandoned without a major clean-up to guard against eventu.a1 release of some of that material to the environment.

There is, however, disagreement about the urgency of the need for reactor building entry.

The reasons advanced by Met Ed and the NRC (in NUREG-06 62) for promptly regaining access to the reactor building fall into three categories:

1) Maintaining reactor building integrity, 2) assuring continued integrity of the reactor coolant system, and 3) safeguarding cgainst accidental criti-cality (restart) of the reactor.

As long as these conditions are maintained, there is no urgent short-term need for person-nel access to the reactor building.

However, te ability to maintain these conditions depends partly on components located within the reactor buil. ding.

Access to the reactor building cLaid be required by the actual failure, or concern for the failure, o(,these components.

There are only a few such important components and these are addressed in the following discussion.

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Reactor Building Integrity Reactor building integrity is provided by the reinforced concrete building and its extensions.

The extensions include piping penetrations and isolation valves, electrical penetra-tions and personnel and equipment hatches.

However, the reactor building is not leaktight.

The pressure test of building integrity conducted prior to the accident showed that at 56 psig, the building leaked at a rate of less than 0.1% by weight per day.'

(The design leak rate is 0.2% by weight per day at 60 psig.)

The leakage rate has apparently remained very low.

We have identified no likely failure that would increase the present low leakage rate.

l As long as the reactor building pressure continues to remain slightly negative, no direct leakage of the krypton is possible.

In fact, air is probably leaking into the building.

The negative pressure is being maintained by the combination of the low leakage rate, the release of a small portion of the building atmosphere through the steam generator cooling mode, and operation of four fan coolers.

'The reactor is being cooled by natural circulation which transfers heat to the steam generator.

The secondary side of the steam generator is being maintained at a vacuum l

to permit boildn; at a temperature below 212'F.

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This discharge of a small portion of the reactor building atmosphere may be compensating for the air leaking into the. reactor building.

The heat sources being controlled by the fan coolers are about 50% of the decay heat being generated in the reactor and the solar energy input to the reactor building.

About half the decay heat is being transferred to the reactor building atmosphere because some of the reactor coolant piping is submerged in the 600,000 gallon pool of water in the bottom of the building.

The heat is transferred from the reactor cool-ant to the pool and then to the building atmosphere.

Met Ed and NRC have estimated that,1f all fan coolers failed during the peak summer solar heat load, reactor building pressure could increase to 4 psig in the worst case.

With positive pressure in the building, some leakage of the krypton could occur.

Therefore, Met Ed and NRC argue that prompt reactor building access is needed for maintenance of the fan coolers.

The UCS study group concludes that the desire for access to the fan coolers does not justify immediate venting of the krypton.

The reasons for this conclusions are three-fold:

there are several mitigating actions available, the ha:ards posed by fan cooler failure have been exaggerated, and venting could take place later if in fact the fan coolers did fail.

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12 The heat load now being carried by the fan coolers can be reduced.

Met Ed plans to place a low flow decay heat removal system in operation soon.

Operation of this system will make it possible to reduce reactor coolant temperature and thereby reduce the heat being transferred to the building pool and atmosphere.

The total decay heat load is currently about 540,000 BTU / hour and the fan coolers are removing only about half of that -- about 270,000 STU/ hour.

Met Ed esti-mated that the peak solar energy load would contribute about half the total heat load to be removed by the fan coolers --

another 270,000 ETU/ hour.

Spraying water on the outside of the bu'ilding could help reduce the solar energy contri-bution.

Nevertheless, since the heat removal capacity of each f an cooler is 1.4 million BTU / hour, it appears that operation of just onc of the five coolers is probably ade-quate to maintain reactor building temperature at its present level.

However, there is no way of being certain that at least one fan cooler will continue to be operable.

Four of the five units have been in operation since the accider.t began.

They were qualified to operate for only 3 to 4 hours4.62963e-5 days 0.00111 hours 6.613757e-6 weeks 1.522e-6 months of accident conditions and are supposed to receive main-tainance once a year.

Nevertheless, the one fan cooler not now in operation is believed to be operable and the dual speed motors could conceivably.* unction on high speed should the windings now in service fail.

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13 Even assuming that all fan coolers failed completely, l

l the hazard to the public would be slight.

NRC exaggerated the hazard by calculating a radiation dose to the public far in excess of the expected dose by assuming an unrealistic leak rate.

(See page 4-5 of NUREG-0662.)

Although building pressure was estimated by NRC to be 1-2 psig, *:he leak rate used by NRC was the leak rate that would occur only if pressure increased to 60 psig or if the leakage paths increased in.

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The NRC further assumed that this high leak rate would be constant over a 30-day period.

We believe that if the

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situation aris2s where all methods of reactor building heat removal fail, the partial venting of the containment could take place then, if needed, to reduce the radiation dose to the public from the uncontrolled ground level release of the krypton.

Furthermore, if such venting were used, it would not be necessary to release the entire contents of the building but only the fraction needed to reduce building pressure to O psig.

The bulk of the krypton would not be released.

In summary, the UCS study group concludes that immediate venting of the TMI-2 reactor building is not necessary to maintain building integrity, there is no immediate need for fan cooler maintenence, and the public can be protected even if all fan coolers fail.

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Reactor Coolant System Integrity Met Ed and NRC have also advanced concerns about the integrity of -the reactor coolant system as a reason for prompc-ly venting the krypton in the reactor building.

They specu-late that the submergence of some of the reactor piping in the 600,000 gallons of contaminated water and the exposure of piping, the reactor, and steam generators to contaminants in the building atmosphere cou'.d cause accelerated corrosien which could lead to a failure of these pressure boundary components.

Such a failure could lead to a loss-of-coolant accident and severely complicate the clean-up process and the status of the damaged plant.

Based on our review of the alternatives to venting and the need for access to the reactor building, we conclude that failure by accelerated cercosion is not significant to the particular issue of immediate krypten removal.

We agree that removal of the krypton is ultimately necessary to achieve relatively free access to the reactor building.

However, no gases have been reported present that are a severe threat to the integrity of the piping and components exposed to the building atmosphere.

In addition, venting would have little or no effect on the integrity of or access to piping sub-merged in the contaminated water.

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We therefore conclude that treatment of the contaminated sump water, rather than venting of reactor building, is the b

action needed to alleviate concern about the loss of reactor

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Until a. plan for treatment of the water is approved, speculation about failure of components submerge'd in the sump water cannot be used as justification for venting.

If the treatment is accomplished remotely and externally,.the need for building access is even less urgent.

If tne method of water treatment approved requires access, venting (or an alternative developed by the time access for water treatment is needed) could be used.

In summary, the UCS study group concludes that immedia:p venting is not needed to assure continued reactor coolant system integrity.

4.

Safeguarding Against' Accidental Criticality The possibility of the reactor accidentally starting up again (achieving criticality) has also been advanced as a basis for immediate venting of the krypton.

The particular concerns related to personnel access are the need to ensure adequate boron concentration in the reactor coolant and the availability of neutron detectors.

The only method available for keeping the reactor sub-critical is to maintain the boron concentration in the reactor cooling water sufficiently high.

Met,Ed has ~ calculated that in the worst case (i.e., all control rods and burnable poison rods removed and the core slumped on the lower grid in the reactor vessel), ths reactor will remain subcritical by a large margin if boron concentration is 3500 ppm or greater.

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A 16 Presently, boren concentration is being maintained at 3700 ppm.

When the low flow decay heat removal system is placed into operation,which is scheduled for May 1980, there will be thorough mixing of the reactor coolant.

This will eliminate the expressed concern about the boren concentration in the ecolant sample'being representative of the boren concentration in the reactor vessel.

In any event, perscnnel access to the reactor building will not materially aid in determining or in maintaining the boron concentration.

The only direct way to determine whether the reactor is suberitical is to measure the neutron level.

Only one of the plants' two source range neutron detectors (the most sensitive of three ranges of neutron detectors) is presently operable.

Failure of the last instrument would make future, direct verification of shutdown difficult if not impossible.

However, two factors relate to whether immediate acce'ss to the reactor building is needed to repair the other source range detector.

First, it is not known whether removal of the krypton would make the location of the source range detector (the 327 foot level near the top of the reactor) accessible.

In all likelihood, venting will have little impact on the radiation dose rate at this location, but the mobility of personnel would be improved by elimination of the need for bulky protective clothing.

Entry into the reactor building in the near futurg, in~special heavy protective suits, could give l

l some indication of the radiation levels in this area.

Second, I

l failure of the source range detector would, of course, not 9

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An additional failure or personnel error leading to dilution of the boron would be required.

Thus, increasing the sampling frequency to deter-mine boron concentration could compensate for failure of th.e remaining source range neutron detector.

If the reactor did bewome critical, it would be detected by temperature increases of the reactor water (although n,ot as quickly as if the source range detector remains operable).

In addition, special instru-ments are now being connected to the power range detectors which may also indicate criticality.

In summary, the UCS study group concludes that it is highly unlikely that the reactor will become critical and that Emmediate access to the reactor building will not sig-nificantly affect either the ability to keep the reactor suberitical or the ability to reachieve shutdown if criti-

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cality occurred.

5.

Conclusion on Need for Entry Relatively free worker access to the reactor building is eventually necessary in order to decontaminate the plant.

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radiation dose to workers from the krypton in the building atmosphere effectively precludes the necessary access.

There-fore, the krypton must eventually be removed from the building.

On the basis of^ concerns about reactor building integrity, reactor coolant' system integrity, and accidental criticality,

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Met Ed andthe NRC concluded that building entry was urgently needed -- within a few weeks or months.

The UCS study group 9

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- concludes that none of the concerns expressed by Met Ed and NRC have sufficient merit to justify their proposed schedule.

Furthermore, we have identified no other concerns that would support a conclusion that prompt entry in the short time they propose is needed.

The UCS study group concludes that taking additional time to develop an alta".ative course of action to the r

Met Ed/NRC venting propc. 1 is justifiable for reasons discusse.d later.

Such a course would not pose an undue rish to the health and safety of the public. -However,

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v because of the uncertainty about future problems developing that are not now foreseen, the delay should be no longer than necessary.

It must not be much longer than a year and certainly no longer than a year and a half.

Furthermore, if an emergency si'tuation developed that required prompt building entry, the krypton could be vented in a few da'ys in the manner proposed by. Met Ed and MRC.

We believe this possibility to be remote.

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- Reference, Stection 'II

- NVREG-06'62

" Environmental. Assessment for Decontamination of the Three Mile Island Unit 2 Reactor Suilding Atmosphere," U.S.

Nuclear-Regulatory' Commission, March 1980.

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VENTING A.

General Considerations in Ventinc Venting of the contaminated containment gases as proposed

.by NRC and Met Ed would employ,a 160 foot stack located near the containment building.

This stack is sufficiently short so that the released gases would mix with the turbulent wake downwind of the containment building, and.for some wind directions the wakes of the cooling towers.

The resul-tant plume of radioactive air would initially be roughly as wide and as high as the building and would quickly come into and remain in contact with the ground.

Maximen radiation levels occur very near the release site.

Because the beta emissions from krypton travel only a relatively short range in air, and are the dominant emission, a ground level cloud gives rise to the

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greatest radiation exposure to people.

A cloud more than a few meters distant irradiates only by its gamma ray emissions.

If the release point is elevated so that no building wake entrainment occurs, then the plume initially will not contact the ground.

As the wind carries the material along, mixing and diffusing of the plume will cause lateral and vertical dispersion of the material and at some distance downwind l

(depending on the release height and weather conditions) the now more dilute material will contact the ground.

The maximum radiation levels may occur at scme distance from the release point.

The maximun radiation exposures in such cases 1

l

~'

.+g. '. w p 3 < v 'em w-r w

.f 4

s yeg tw=w o,

v.

p meg g, w,9w, m w w w a.s.

$g

.,,.n, 3

.,%p..

,w

21 may be dramatically lower than for ground level releases.

For this to occur the release point must be effectively far above the structure tops so that ne structures intercept the plume.

In our search for means to reduce the radiation exposures to persons on the ground we examined the possibility of venting frem the top of one of the 370 foot TMI cooling towers.

Mixing in the tower wake occurs so quickly downwind, however, that no appreciable reduction in the ground dose off-site is achievable.

Consequently, we turned to other alternatives discussed later in our report.

5 Radiation Exposure and Direct Health Effects Our calculations for the total beta skin dose and separately for the total gamma dose are given in Tables 1 and 2 for a variety of release heights and entrainment. They are based on a standard gaussian plume model described in another publication.~

(Beyea, 1979).

They are expressed in millirem (0.001 Rem) and are totals following complete containment purge.*

They are also based on the assumption that venting is completed in 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months .

For longer venting periods the variability of the wind direction will cause the plume to wander significantly and the doses to decrease perhaps by. a factor of two or three.

Because venting as proposed by Met Ed/NRC would require 5-50 days our calculations with respect to this effect are conservative overestimates.

-We assume that any significant quantitles of airborne particles in the containment carrying radioactive cesium will be removed from the release stream through' filtering as proposed by Met Ed.

9 n.

--. ~....

=~m-

~~

22 There are three distinct doses to note:

A.

Beta skin dose -- dependent

. the ground-level concentrations of Kr-35.

B.

Beta and gamma doses following inhalation --

also dependent on ground-level concentration.

C.

Cloud gamma doses.

The results for cases A and B are probably unreliable for very high plumes because the plume model has not been adequately tested for such circumstances.

In general the exposures are very small in such cases for it is known

~

that the doses drop off very quickly with increased release height.

There is an additional uncertainty for case B owing to the difficulty of determining how much radiation will be distributed within the body.- However, it is known that skin is the tissue exposed to the highest dose frem the betas of airborne Kr-35.

The low solubility of krypton gas in water makes internal doses quite small, especially for developing embryos.

Fat solubility plays a minor role for short exposures because absorption levels are determined by colubility in blood.

The I

small volume of gas in the reapiratory tract air passages reduces the direct beta dose to values below the skin dose.

Tabli 2 includes l

l in an approximate way the small contribution to the whole body I

dose from inhalation of material.

The dcminant contributor to this dose, case C, is " cloud shine" (direct radiation'from O

.a

~

-e.

~mm.

~,..~.ei n.

'I

',64,* m; 9 *= w_

ya

'4 w esw ays,

,m,

~

l

33 the radioactive cloud).

The information in the tables is appropriste to release under restricted meteorological conditions known as D-stability, corresponding to nighttime or overcast day release, and for a wind of 11 mph (5 m/sec).

Doses vary as the inverse of the wind speed.

We assume that releases are cnly allowed during periods when meteorological conditions are such that doses would not be significantly greater than those shown.

4 The largest ga=ma dose occurs close to the plant for the

" ground-release" case, proposed by the NRC/ Met Ed.

It is 0.03 millirem.

This should be compared with the radiation background to which we are all exposed, from naturally occurring terrestrial and cosmic sources, of about 100 millirem per year.

The dose at this worst case location from a ground release corresponds to 3 hours3.472222e-5 days 8.333333e-4 hours 4.960317e-6 weeks 1.1415e-6 months of normal background exposure.

In contrast, a release at a 300 meter height yields a maximum dose of 0.001 millirem.

From current evidence of effects of whole body radiation on human populations, the above considerations indicate that at the doses postulated, no health effects would be anticipated as a result of the " ground release" venting.*

The amount of exposure is so low that it falls in the range of background variability naturally occurring for the citizens living around the plant.

This variability arises from differences in body characteristics (e.g., potassium-40 content), the amount of certain nuclides naturally present in soil (uranium and radium) and the type of materials in. one's home (e.g. brick and stone vs. frame).

While The total population dose received while the plume is recognizable

,as a plume would be less than one person-rem.

be m.

w.mo,em s

,w.

g a os e

m, sm e w,, emoww -

ar-wn~

24 we believe that any additional whole body radiation exposure will increase cancer risk, exposures well below the natural lifetime

. variation of background sources will lead to effects so minimal that they cannot be detected by any method.

Doses to the body frem beta radiation, while larger than the gamma dose by factors of about 100, are not whole body exposure.

Beta radiation from Kr-85 involves only a limited portion of the body tissue, principally the skin, and doses anticipated are far below the levels required to induce beta burns (radiatione{ythema) of the skin.

It is possible that the larger beta doses from Table 1

~

would increase the chances of developing skin cancer.

However, the best present evidence suggests, but does not prove, that doses substantially in excess of 10,000 to 50,000 millirem are recuired in order to increase the incidence of such cancer.

The pressnt margin of safety appears to us to be comfortably large.

One matter of importance in all predictions of the kind we are discussing is uncertainty, and therefore possible error, in the results.

We estimate the uncertainty in the dose predictions of Tables 1 and 2 to be a factor of 10.

That is to say the ex-pected radiation doses under the stated conditions could be as much as ten times greater, or ten times less, than our numbers.

Consideration of the worst case exposure, unlikely but poscible within our estimated uncertainties, does not change our view that direct health effects will be absent from venting the Kr-85 even from the "gr,cund-level" release.

Our conclusions in this regard are similar o,those reached by the NRC and Met Ed.

1 m.--,_.

_m-

25 TAE!.E 1 Beta Skin Dose (Millirem) Plume Center: ne l

~

ease Height (meters) 50-125 125 200 300

' 500 700 d

DISTAEE

."hetg In wake of Not in Wake cooling tcwer 660 ft. 990 ft.

1650 ft.

2300 ft.

(Hiles)

)

prorosal 1

5.7 3.3 0.31 0.0009

'2 2.9 1.8 0.90 0.007 0.0007 3

1.8 1.2 0.90 0.19 0.009 4

1.2 0.90 0.77 0.25 0.028 2.3x10-5 5

0.S7 0.70 0.63 0.28,

0.048 1.9x10~'

6 0.67 0.53 0.53 0.27 0.067 0.0007 7

0.53 0.47 0.47 0.26 0.076 0.0017 8

0.43 O.37 0.40 0.24 0.087 0.0032 2.2x10~

9 0.37 0.32 0.33 0.22 0.09 0.005 6 x 10~

10 0.32 0.28 0.29 0.21 0.093 0.007 0.00013 15 0.087 0.017 0.0013 20-0.07 0.022 0.0035 30 0.024 0.007 40 0.021 0.009 50 0.0093 100 0.007

-5

- Less than 10 This table gives the plume centerline doses for complete purge of the TMI containment building. The underlined entries are the downwind positions of the maximum radiatien exposures.

The dcses have been calculated for a 24-hour zelease, D atmospheric stability class, flat terrain, and cn 11 mph wind.

Beta doses (in millirem) are calculated as 60 times the " exposure" (in curie-seconds per cubic meter).

Doses could be greater at locations with elevations higher than the elevation at the release point. See the text for further discussion of th'e table.

h g

e e

p ww -

.e g.i

.-,w-,*

, w-+.

pusame.,..

=.

26 TABLE 2 - Total GP.m.a Dose (Millirem) Plume Centerline f

tease Height 50-125 125 200 300 500 700 (meters )

DISTANCE

[*yl" In wake of Not in Wake c ling tower 660 ft. 990 ft.

1650 ft.

2300 ft.

(Miles) h prep sal 1

0.03 0.021 0.0067 0.002 0.0005 5 x 10-5

-5 f

0.017 0.012 0.007 0.002 0.0005 5 x 10 2

3 0.011 0.009 0.006 0.0023 0.00C57 6 x 10-5 4

0.008 0.006 0.005 0.0025 0.0006 6 x 10-$

5 0.006 0.005 0.005 0.0023 0.0007 7 x 10-5 6

0.005 0.004 0.004 0.0022 0.0003 3.x 10-5 7

0.004 0.004 0.003 0.002 0.0003 9 x 10-5 1,3xyg_g 8

0.004 0.003 0.003 0.0019 0.0009 9.6x10-5 1,4 xyg :

~4

-5 9

0.0031 0.003 0.003 0.0018 0.0008 1.1x10 1.5 x10 10 0.M27 0.002 0.002 0.0017 0.0003 1.2x10 1.7 xic"

-4

-4 15 1.8x10 2.8 X10

-4

-I 20 2.2x10

4. 3 x10

-f 30 2.1x10 7.3xio

-f 40 a.7 xio

-I 50 s.3 xio 100 e.7 xio !

-5 0

Less than 10 This table cives the plume centerline doses for ccmplete purge of the TMI containment' building. The underlined entries are the dcwnwind positions of the maximum radiation exposures.

Doses were calculated as the sum of the whole body cloud dose and the inhalation dose (600 millirem per curie inhaled).

The cloud dose value was obtained by using cn approximate geometrical correction factor (Slade,1968) to ad-just the easily calculated dess from an infinite cloud (0.48 milli-rem per curie-second per cubic meter).

See the text and Table 1 l

notes for further discussion of the table.

O l

27 C.

Stress-Related Public Health Effects There are public health effects of venting, aside from possiblebut imperceptible direct effects of radiation, which cannot be dismissed lightly.

We refer here to the perceptions of hazard by the people living near TMI, and the health significance of these perceptions.

These psychosocial problems have been investigated'by the group at Hershey Medical Center, and in addition are currently under study by a team from the Western Psychiatric Institute of the University of Pittsburgh.

The latter study is not yet analyzed sufficiently for conclusions to be drawn.

The problems have also been manifest in angry confrontations between citizens of the Harrisburg area and NRC/ Met Ed officials,especially over the proposal of these officials to carry out the " ground-level" release of the krypton-85 gas.

The Pennsylvania State University Medical Center at Hershey, supported by a grant from the Electric Power Research Institute, issued a report in April, 1980 entitled " Health-Related Behavioral Impact of the Three Mile Island Nuclear Incident."

This report included results of a series of telephone interviews conducted in April, 1979, July, 1979, and January, 1980.

The first involved nearly 700 people living within 5 miles of TMI, the second involved over 1500' people living within 55 miles of TMI, and the third series, including reinterviews, involved over 950 persons.

It is clear from this report that a number of physical and behavioral symptoms can be related to an "o

s S

pe

.wg,,gy..,-yes

r. h+

- W*

,W"****'"

'"W*#

" * * " ~ ~ ' '

/*

~~

'2 8 '

individual's proximity to the TMI plant.

Contrary to expectation, the prevalence of these symptoms has not declined in the nine months between April, 1979 and January, 1980.

Indeed some may have increased.

The " physical stress" symptoms included headaches, diarrhea, constipation, abdominal pain, sweating spells, stomach trouble, frecuent urination, and rash.

" Behavioral stress" symptoms included irritability, fits of anger, sleeplessness, loss of appetite, feeling trembly, interrupted thought processes, and overeating.

These symp: cms and behavioral effects eviden:1y have arisen from anxiety engendered by proximity to the plant, fear of exposure to radioactivity, and apprehens.ons concerning 4

loss of trust of official reassurances about potential radio-active releases.

It-is significant that between 10% and 20% of the population sampled within 10 miles of the plant was affected, as the Penn State Study concluded.

Beca'use some 200,000 persons live in this area, the number of affected persons may be inferred to be in the range of 20-40,000.

This is a surprisingly large number.

e 4

4 h,

a

. s '* I.

4

'a 4

ve**

uhr, I

a-t***

e-em g e

g=

myr=

r c

g.- i p.

,,.4

%w rywp.,_.

.g 9,

p g

.p.

29 It is in stark contrast to claims that only a few, perhaps only one person, were " victims" of the Three Mile Island accident.

While the' methodology poses some difficulty to interpretation of these results, the findings are striking.

If this conclusion is valid, it indicates a medical problem of major public health importance.

There is therefore good reason to conclude that the deliberate venting of krypton-85, already opposed by many citizens, may seriously exacerbate'the problems of the mental and physical health of.

the public that the stress of the planned exposure would engender.

D. Elevated Release 1.

Introduction Because of the significant and unacceptable public health consequences described above, which we believe would stem,from the ground-level venting planned by Met Ed and the NRC, the UCS

. Study Group devised two alternative venting methods each of which we believe to be superior.

Use of either one would result in very large reductions in the radiation dose affecting any segment of the public as compared with the " ground-level" release.

All doses would be significantly lower, and the O O e

O

3G

peak dose would be moved trther from the plant as well as diminished.

This substantial dilution and transfer of impact would be achieved b, 2 evating substantially the effective point at Ohich the containment building gas would be released into the atmosphere.

2.

Heated Plume The first UCS alternative employs the buoyancy imparted to gas by heating it.

This'is a familiar effect frequently summarized in the aphorism -- heat rises.

We find that a heated plume can be produced with readily available equipment and at moderate cost, that flushing of the containment can be carried out in a few days, and that significant reductions in ground level beta skin doses can be achieved.

The heating could be carried out using a modified commercially available incincerator fueled by oil or natural gas.

Buoyant Plumes

If an incenerator with very buoyant emissions can be installed, the containment gases,. including the krypton, will

~

rise with the plume.

The effective height of emission of the gases can be much greater than the stack height and more than enough to clear all building and cooling tower turbulent

The material set forth in th,s section was prepared by Dr.

Thomas Overcamp, Associate Professor in Clemson University's l

Department of Environmental Systems Engineering.

s

~

=

e

' ' =.

v-w+-e,, m.

.w,

31 wakes by a considerable margin.

The effective height of emission, h, is given by the expression e

he=hs + ah where h is the height of the incinerator stack and ah is the s

final plume rise.

If Ah is large, the gases will diffuse as if they were emitted from a very tall chimney.

This is the mechanism that leads to the reduction of ground radiation levels as compared with a cold release at height hs-The theory of the rise of buoyant plumes was developed by Briggs (1969), Hoult, Fay, and Forney (1969) and others.

The rise is a function of the initial momentum of the plume and its buoyancy.

For highly buoyant plumes as from the pro-posed incinerator, the final rise can be predicted frcm considering just the plume's buoyancy.

4 The final rise is a function of the buoyancy, the wind speed, and the stability of the atmosphere.

The buoyancy of the plume is measured by its buoyancy flux, F:

T, - T F = go, w a

o 4

Ts where g is the gravitational acceleration, D is the stack s

diamatar, w,,o is the exit velocity of the gases, and T and s

T are the exit and ambient temperatures respectively.

a 4 *

v p'4h

-F.M*

1 -'*uo98' w w** y ' ti #w W7 '

^+-M W w p,

4

hM 6==m - s. g

%*-% m 7 v.

-'. - Me= N eo

, - E t-w

32 Atmospheric conditions can be classified as unstable, neutral or stable.

Unstable conditions occur on sunny days with light winds.

Neutral conditions' occur under overcast conditions during tre day or night and also for very windy conditions.

Stable atmospheres occur under clear skies at night with light winds.

For neutral to unstable conditions, the most widely used plume rise for=ula is one proposed by Briggs (1970).

l/3 2/3 l.6 F (3.5x)

Ah =

u in which u is the wind speed and x is given by the empirical formula x = 34 F2/5 (m) 55 m'/s where F>

3 This formula is the one used by the U.S. Environmental Protection Agency for modeling buoyant plumes from power plants And industries.

It is recommended by many others ( A. S.11. E., 1979) as the state of the art formula.-

For stable conditions, the recomgended formula is Ah = 2.4.IF.g)

\\

in'which'S is a stability parameter given by e

t'1"

t%

5 eh.-

, p ympe-m qw s e y,, y ;

,y.-

m

,w_,,

M d

31 d*

S = 2.

T,, O + 0.01 dT8 where is in "C/m dz j

For stable conditions, the stability parameter will typically have a galue between 10-4 and 10-3 see -2, The incinerator we piopose would have a height of 250 ft. (76m), an exit diameter of 6ft. (1.83c), an exit velocity of 100 ft/s (30.5m/s), and an exit temperature of 18000F (1256 To avoid any possibility of the plume from the incinerator being trapped in the wake of a ecoling tower, the incinerator should be sited two or three cooling tower heights away from any tower.

This corresponds to 750-1000 ft.

If this is not possible,'the incinerator should be taller or a more detailed study shculd be undertaken to determine the potential for interference.

For this incinerator, the buoyancy flux is 193 m*/ s.

For any given atmospheric conditionn, the plume rise and effective height of emission can be estimated using the above formulas.

For example, if the wind speed is 6.7 mph (3 m/s), the plume rise for neutral conditidns will be 1000 ft. (300 m).

If the atmosphere is stable and the stability parameter is 10-3 2, the plume rise see is'315 ft. (96 m).

These correspond to effective heights of emission of 1240 ft. (376 m) and 570 ft. (172 m) respectively.

\\

These heights are sufficient to clear any terrain obstacles within 6 miles (10 km) of the plant.

1 Figure 2 gives the calculated plume rise of this incinerator for various wind speeds and stabilities.

The predictions show that the plume rise is higher for lower wind speeds.

The neutral stability is generally higher than the stable plume rise.

These predictions will have to be modified if there is an elevated I

g h

m;

..g e e ee g,

.gw===*.w.-

w eg m****"

T

""esw-

NN

%F

-*"-\\

g I.

34 inversion that limits the rise of the plume.

The average height of such an elevated inversion over that area is 1000 to 1800 m depending on the season of the year and the daily weather conditions (Holzworth, 1972).

fed i

6 4

4 a

i e

a 908

\\

100

~le c t

nea t' ru.

kn b

(N

~

),

~

J 4:e 300 S =,ggi W

290 gp N

L

g. g-3 100

.s O

I f

I 1

I I

1 1

I o

I 7

's

,Y 6~

6 r

g q

to u>~ls P.lume Rise Versus Wind Speed for heutral conditions and'various Stable conditions.

Figure 2 p

t e

4 '

%T,-

- y>'9 g

gje HM r tw "

yq h**" tT% _*, dM -* W t N.* * *

t-T y A

NJ WV:s*+y%"-'***M i*T

35 From the information in Figure 2 and an assumed stack height cf 250 ft. (75 m) it can be seen that effective heights of emiss' ion in excess of 900 ft. are achievable in many cir-cumstances, especially with low to moderate light wind conditions.

~

Radiation Exposure The reduction in the beta skin dose (the radiation effect of most concern) in tne heated plume case, as compared to 'the

" ground level" release, is extremely large within a few miles of the release point for a 1000 ft. emission height -- a facter of 4000 reduction at 2 miles, and a factor of nearly 15 at 5 miles.

See Table 1.

At greater distances, the fraction decreases owing to vertical diffusion of the plume.

The maximum dose occurs at a considerable distance from the release point, as discussed earlier, at least 8 to 10 miles distant, and in some weather circumstances at 20 miles or more.

The magnitudes of the skin doses', for appropriately chosen weather conditions, are very small by any reasonable measure.

The Facility We have carried out a preliminary investigation of the size and configuration, cost, and availability of the incinerator necessary to knplement the hot plume release.

The details are included in, Appendix I and are summarized here.

G O go

- - - - +=

e4.

., ww-s q w =, -

-==

m.ev

-w--

e-

. %.w.=7

.+w-vm.

g*

--w-~~-,

36 The incinerator would employ a 6 ft. diameter refractory-lined stack perhaps 250 ft. (75 m) high.

With a discharge temperature of 1800*F and an exit velocity of 100 feet per second, it would run with natural draft and a negative furnace pressure, minimizing ground level leakage.

Fuel requirements would be in the range of 250 gallons per hour of liquified petroleum gas.

If containment gas were vented into the furnace at 100 cubic feet per second, only a few days of release time, perhaps spread over sevcral weeks, would be required for reduction of the containment krypton concentration to below Maximum Permissible Concentration of 10 CFR 20.

Total fuel cost would be below S20,000.

Rough estimates of the construction time for the facility are in the acceptable range of 7-9 months, at a cost, exclusive of those special features required for the delivery and special handling of the contaminated gas to the incinerator furnace, of $250,000. The time estimate does not include the possibility that top-priority expediting, aided by support from the US Government [ortheimmediateavailabilityofausedincinerator could appreciably speed things up.

Evaluation UCS regards the hot buoyant plume proposal as promising.

It is cased on well known phenomena that may be predicted with adequately s, mall uncertainty.

The venting can be monitored and halted as. req'uired.

The technology of producing the plume is

' W' f

*9"'

MH + -4 e-6w As p eyn m,4,

4

37 mundane and the equipment easy to manufacture or possibly, obtain second hand.

The risk of an accident of unacceptable scale during the venting seems to be very low because the amount of krypton in the system at any given time is small. For the same reason worker doses may be kept low as well.

Coping with unexpected changes in the weather during venting is accomplished by system shutdown.

Elevated rele'ases have the advantage that even the skin _ dose can be kept well below the skin dose any individual receives in one year from natural background.

Finally, there are large reductions in beta skin dose compared to the ground level release scheme.

The levels are likely (although by no means certainly) to be acceptable to

,4-people living in the vicinity of the release point.

At the very least, reductions of this magnituce woulc be perceivwU by 3:

the public as an attempt to reduce the radiation exposures and,

?

thereby, tne possible stress-related public health' impact that venting might have.

S gg 6

4 l

e e

. - ~ ~ - - - -

-~

"~^~

~

38 3.

' Tethered Balloon Release 1

Introduction The second alternative devised by UCS to implement an elevated release point makes use of a tethered unmanned balloon to support a light-weight impermeable fabric-rein-forced tube.

By this means it is possible to achieve a release height in the :.nge cf 1000 to 2000 ft. (300-600 m).

The reduction in groun(-level beta skin dose within a few miles of the release point, as compared with the "grotnd-level" release, is very great.

Because the technique is new, and innovative, we have taken special pains to establish its practicality as well as we could in the time available.

In this effort personnel of the U.S. Air Force Geophysical Laboratory have been of particular help.

Balloon Technology l

Tethered balloons, manned and unmanned, have long been used in military and non-military affairs.

Both the U.S. Air

(

l Force and the U.S. Navy have active programs that involve l

l such~. lifting devices.

These, and free flight balloons, levitated by helium, nay typically be filled through a 1 ft.

diameter hgpa made of 0.003 inch polyethylene.

Hoses some 600 ft. long have accommodated gas flow rates in the vicinity l

of 30 cubic feet per second.

p

~.

.4c 1

,,..,,e-,

n~~~.

y..,

m

..,.,.~.y.,

-,...w-.

..._-..s.

.~

m

~

30 What we propose is a hose or tube of coated nylon able to withstand perhaps three times the pressure of unrein-forced polyethylene.

It would contain an integral suppor-ting cable of Kevlar, an exceptionally strong lightweight material, to reduce the tendency of the tube to kink and to provide support.

Kevlar tether cabia weighs 50 lbs/1000 ft.

-and has a 16,000 lb. breaking strength.

The tube would be supported nearly vertical by an unmanned non-spherical aerodynamically-shaped balloon.

The balloon would be tethered by two or perhaps three Kevlar cables arranged so the ballocn remained over the ground end of the fabric tube.

A diffuser at the balloon, or exit, end of the tube would produce adequate back pressure to ensure the tube remained well inflated.

2000 feet of fabric tube of the I

sort required would weigh less than 500 lbs., perhaps as

^

little as half that.

Inflatable fabric balloons employing 45,000 cu. ft. of helium are now available as are Portable winches for handling them.

They have a' payload of about 1500 lbs. and are simple to handle.

On an ordinary single tether, with no tube, they can fly in winds up to 20 Kts and can be recovered from an altitude of 2000 ft. in 10 minutes.

It is estimated that a double tether arrangement and a tube payload should not significantly increase recovery time.

Figure 3 illustrates a double tether arrangement, launch ready and in operation,which is based on a preliminary Air Force. concept.

O.

~-.--.L-.-,..

~~~-r*~

40 SCHEMATIC 1

VENTING BY TETHERED BALLOON l

Launch Ready Zalleen lL " E %uger I

Tatker p/

Te%.cr line ETube l

1 9

kwmc8 h.ve

[

1-

/'

't

/ <

<s s

ii e

i i i i,,,3,,,,

'A

-2C,00$t

-)

51 % -

~ - -

t i

l l

l Operational Position 7

r-

\\

Cu

[_

L-I

r r<

e i

r FIGURE 3

'4'

-*C.

N waa se m e wpe m9,

41 About six people are needed to inflate and fly such a balloon, and that number of people must be on call if recovery 1,s required.

Two persons are all that are required for " babysitting"'while the device is tethered aloft.

At a balloon height of 2000 feet wind drag limits the tube diameter to about 1 foot.

For this altitude achievable flow rates, according to the Geophysical Laboratory experts, would exceed 60 cubic feet per second and may exceed 100.

For a 1000 ft. 1 tube, the ficw rate could conservatively exceed 100 cubic feet per second because a larger diameter tube can' be used.

At this latter rate, as with the heated plume, a total release time of a few days is all that is required to bring the containment krypton concentration below the maximum per-missible concentration for workers.

Night time periods of stable air uinimize the ground level radiation exposure,

'su t this exposure is already so small for release heights-above 1000 feet that venting could probably proceed in all wind strengths in which.the balloon was flyable.

Radiation Exposure With a release height in the range o. 1000-2000 feet, a plume remains largely overhead for ten or several tens of miles.

As it is borne by the wird, the-plume diffuses vertically and laterally and its concentration dwindles.

The ground level radiation exposure at all distances is S

O-D 4

-,,.ww..

t_pg

-,g-

, e e, 7

-.~.~ %.

--e+

m r.-

s <

42 dramatically reduced over " ground level" release.

Table 1 tells the story.

For the highest release, out to 6 miles from the release point, the beta skin dose (again, the radiation of most importance) is reduced by factors from a million, at worst, to very much larger numbers when compared with the " ground level" release case.

In the range 20 to 100 miles from the release point, where a very small portion of the plume has diffused to the ground, the exposure is at worst no more than a few percent of the " ground level" case's expcsure at 10 miles.

It is fair to say that the maximum exposure is wholly negligible.

Indeed the ground level radiation probably could not be detected anywhere under the plume of such an elevated release over the background of naturally occurring terrestrial and cosmic. radiations.

Safety The tethered balloon shares with the heated plume the feature that the amount of krypton in the system at any given time is small.

Thus a total release of krypton from the tube stemming from a rupture or from a loss of support is not a major concern.

Nor should worker exposure be large.

l Before routine recovery of the balloon, the tube could be purged with fresh air.

In some tether arrangements proposed 1

by the Air Force experts, recovery does not require approach i

- to or handling of the tube.

Should the b.;11oon break free h

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43 it will simply deflate slowly and come to earth.

The balloon while tethered would represent a considerable hazard to aircraft, especially if, as expected, it were flown primarily at night.

Identification of the balloon by appro-priate lights, and notification to pilots through the FAA's NOTAMS (Notice to Airmen), radio, TV, and newspapers of flight schedules and wind directions would be required.

Costs and Timetable Costs and timetable for a tethered balloon system are somewhat difficult to estimate.

The fabric tube of the required length would require a few weeks of engineering and perhaps a month to fabricate at a cost probably less than $20,000.

A new balloon costs in the vicinity of

$100,000.

Helium need not be purchased because,barring an accident, it can be recovered after the project terminates.

If the tests described below are successful, it should be possible to have equipment ready in about 4 to 7 months from the time of commitment.

It is possible that Air Force balloons, handling equipment, and ground crews could be made available for the venting.

This Ltight appreciably shorten the krypton release schedule and decrease the costs.

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44 l

Evaluation This venting technique we propose is untried.

Tests of the concept are therefore a necessary precursor to a commitme$t to deploy.

Such tests can, fortunately, be carried out with Air Force balloons, at the facility at Hollomon Air Force Base in New Mexico.

Such tests would include air flow rate measurements on balloon supported tubes of the required size and of the required length.

These tests could be carried out in a few weeks and, most fortunately, the Air Force has agreed that they will do them if requested.

The Air Force has already reviewed and commented on our proposal.

Their com=ents are included here in Appendix II.

They regard the technique as workable.

The tests would, hopefully, confirm this judge =ent or, nearly as good, lead to the prompt solutien of new difficulties the tects unearthed.

A Three Pdle Island site visit is necessary to establish whether or not an adequate area exists in which to establish the needed tether and the ground-based gas system.

The site is hardly ideal for balloon flights with its cooling' towers and power lines.

It is not, however, an impossible location.

The tethered balloon venting appears to be the most attractive of the venting schames in terms of costs, schedules, and, especia11yg. radiation exposure.

While there are some significant unknows remaining, these can be illuminated promptly and*with seemingly modest effort.

This venting scheme will lead to very great reductions in l

radiation exposure.

However, we do not know whether even this very

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1ow exposure will be acceptable to citizens in the area.

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45 E.

References, Part III American Society of Mechanical Engineers (1979):

Recommended Guide for the Prediction of the Discersion of Airborne Effluents, A.S.M.E.,

New York, 87 pp.

Beyea, Jan (1979) :

Scme Long-term Consequences of Hvpothetical Releases of Radioactivity to the Atmosphere from Three Mile Island, Report to the President's Council on Environmental Quality.

Briggs, G.A.

(1970):

Some Recent Analyses of Plume Rise Observations, Second International Air Pollution Conference, Academic Press, New York.

Holzworth, G.C.

(1972):

Mixing Heichts, Wind Speeds and Potential for Urban Air Pollution Throughout the Contiguous United States, U.S. Environmental Protection Agency, AP-101, 118 pp.

Hoult, D.P.,

J.A. Fay, and L.J. Forney (1969) :

A Theory of Plume Rise Ccmpared with Field Observations, J. Air Pollution Control Associations: 19, pp. 585-590.

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IV.

KRYPTON RECOVERY I

A.

Introduction Met Ed and NRC identified four major alternatives to t

ground-level venting of the krypton, all of which involve recovery of the krypton rather than venting:

These are selective absorption, cryogenic processing, gas compression, and charcoal adsorption.

The UCS study group identified no additional alternatives other than the tethered balloon and heated plume modifications to the venting proposal.

Our evaluation of the four alternative recovery methods is presented below.

We conclude that the selective absorption and cryogenic processing alternatives are preferable to Met Ed's venting proposal if they could be accomplished in less than a year.

The gas compression and charcoal adsorption alternatives are not realistic alternatives because of the long time needed for their implementation and the hazard presented by the nature of the long-term gas storage facilities required with these methods.

B.

Selective Absorption The selective absorption process exploits the different i

solubilities of different gases in fluorocarbon solvents.

In the particular system under consideration for use at TMI, the krypton is"' dissolved in a common refrigerant, Freon.

The ab-sorbed gas is carried by the refrigerant to a different section of the system where the refrigerant is heated to release the e,1

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47 krypton.

The krypton is recovered and stored in standard-sized gas cylinders.

The. principal advantage of the selective absorption is that the krypton can be removed from the reactor building and stored with negligible release to the environment.

There is also a high degree of assurance that the system would be effec-tive because of the extensive experience with pilot plants at i

Oak Ridge National Laboratory since 1967.

A third generation pilot plant with a capacity of 15 scfm has been successfully operated for the last 18 months.

The principal disadvantage of this alternative is the time required to implement it.

The NRC's estimated time to construct a selective absorption system at TMI was 1 1/2 to 2 years or longer depending on regulatory requirements.

The Oak Ridge National Laboratory's estimates range from 1 1/2 to 4 years, but individual engineers r.t Oak Ridge estimate only three months assuming the availability of i

components and regulatory approval.

Recently, the staff of the Science and Technology Committee of the U.S. House of Representa-tives estimated six months.

Another possibility discussed was moving the pilot plant from Oak Ridge to TMI.

We believe this is not a reasonable plan because the capacity of the pilot plant is only 15 scfm.

It i

would therefore require a processing time of about two years I

to remove 99.9% of the krypton.

This~is an unacceptable delay in our judgment, i

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e Since the principles of operation of the selective absorp-tien process are well-understood and the components are either standard' items or easily fabricated, we foresee no difficulty in secling up to a system with a capacity of 150 to 250 scfm.

This would reduce the processing time to two or three months.

With regard to the ha:ard presented by long-term storage of the krypton as an undiluted compressed gas, we conclude that NRC has exaggerated the problem.

In NUREG-0662, it was assumed that all 57,000 curies of krypton would be stored onsite in a single container that might rupture.

This is unrealistic.

Storage of the krypton at 500 psi in five or six standard gas cylinders rated for more than 3000 psi would significantly re-duce the probability and magnitude of an accidental release.

Furthermore, we believe that it is feasible to ship the krypton offsite or store it inside the TMI-l containment or in a specially constructed facility to ensure against accidental release In summary, the UCS study group recommends that the selec-tive absorption alternative be reassessed.

The first step needed is a determination of the availability of components.

If the components are all readily available for a system capacity on the order of 200 scfm and the projected time for construction is not excessive, we see no obstacles to using selective absorp-tion as the met *'.od of krypton recovery.

C. Cryocenfc Processinq l

l The cryogenic procassing system operates on the principle of condensing the krypton from the building atmosphere by direct e

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43 contact with liquid nitrogen.

The liquid krypton is then va-porized and stored in standard gas cylinders or other suitable containers.

The principal advantages and disadvantages of the cryogenic processing system are similar to those of the selective absorp-tion system.

The krypton can be recovered and stored with negli-gible release to the environment.

The storage of the gas presents no more difficulty than discussed above for sel:ctive absorption.

However, the time required to implement a cryogenic processing system at TMI was estimated by NRC and Met Ed to be 20-30 months.

There has been extensive experience with cryogenic processing on a commercial scale to recover Kr-85 at nuclear fuel reproces-sing p' ants.

While the system is more complex than salective ab-l sorption, three major U.S.

companies and several foreiga ecmpanies manufacture cryogenic equipment for production and commerical nuclear applications.

A cryogenic system has been in op'eration at the Idaho Falls Rare Gas Recovery Facility since 1959.

This system recovers Kr-85 from contaminated air resulting from the reprocessing of fuel rods.

The cryogenic system design evaluated by Met Ed and NRC was the system available for purchase from the Limerick plant.

This syster was designed by the Linde Division of Union Carbide.

A particular hazard associated with this system is the proposal to add' catalytic recombiners to the front end to remove oxygen.

The hydrogen supply for the recombiners would constitute a fire or explosion hazard.

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50 Another cryogenic processing system that may be useful at 4

TMI is owned by the Public Service Electric and Gai. Company of New Jersay.

This system is presently in storage at the two Hope Creek nuclear plants which are under construction but are not scheduled to begin operation until 1987.

The system compon-ents are assembled and mounted on skids.

Therefore, the system can be easily transported to TMI and quickly installed.

There are actually three systems, one for each plant and a spare, with I

a capacity of 75 scfm.

These systems were designed and bui_lt by Air Products, Inc.

Hope Creek and Air Products engineers each estimated that the three systems could be moved to TMI and erected in two or three months af ter a suitable building to house them was available.

We are informed that, in an effort to assist, Public Service Electric and Gas is willing to sell the systems to Met Ed and this would not adversely affect the Hope Creek construction schedule.

The Hopa Creek cryogenic systems are designed to process air with as high or higher radioactive contamination than found in the TMI containment building atmosphere.

The systems use an insignificant amount of hydrogen to remove the small amount of oxygen mixed with the krypton at the end of the process and thus would not have the same risk of fire or explosion as the system evaluated by Met Ed and the NRC.

The total cost of the three Hope Creek cryogenic systems is about $5 million.

We recommend that the feasibility of using the Eope Creek systems at TMI be examined further before a" decision on the method of krypten removal is made.

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51 D.

Gas Comoression and Charcoal Adsorption The UCS study group concludes that, in view of the other potential alternatives to the venting proposal evaluated by Mct Ed and the NRC, the gas compression and charcoal adsorption alternatives do not merit further consideration.

We have reviewed the evaluations performed by Met Ed and NRC of these two alternatives and conclude that their evaluations are unduly pessimistic.

The construction time of the. storage facility for the gas compression system can be reduced in several ways.

Larger diameter piping and/or gas storage at a higher pressure could reduce the proposed 28 miles of piping significantly.

For the charcoal adsorption alternative, the amount of charcoal needed could be reduced significantly by regenerative use of a much smaller amount of charcoal.

For both charcoal adsorption and gas compression, removing only 90% of the krypton an_d venting the rest woeld shorten the construction time and reduce the radia-tion dose to the public by a factor of ten compared to venting the entire building atmosphere.

The method of storing the krypton can be designed so that it would be unrealistic to postulate the ground level release of all 57,000 curies of the krypton which was NRC's assumption in NUREG-0662.

Even if the gas compression and charcoal adsorption alter-natives were re-examined in detail to determine a more realistic construction schedule and assessment of the storage hazards, we conclude that other alternatives are preferable.

Considering the very low public and worker radiation doses resulting from an ele-vated venting scheme (whether heated plume or tethered balloon),

selective absorption cr cryogenic processing, it is unlikely that i

m s.

52 either gas compression or charcoal adsorption could achieve lower doses.

Furthermore, we believe that the construction time for either a gas compression or charcoal adsorption system could not be as short as the time needed to implement elevated venting, selective absorption or cryogenic processing.

We therefore con-clude that no further consideration of the gas compression or charcoal adsorption alternatives is warranted.

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53 V.

FINDINGS AND RECOMMENDATIONS A.

Findines KRYPTON PROBLEM Sealing and abandoning the TMI plant is not an alter-native to clean-up.

The plant must be decontaminated whether it is to be restarted or decommissioned.

Relatively free access to the reactor building is j

necessary to acccmplish the decontamination work.

1 The beta and gamma radiation from the krypton-85 in the building atmosphere effectively precludes the necessary personnel access.

Therefore, the krypton eventually must be removed.

l Met Ed and the NRC advanced concerns about reactor building integrity, reactor coolant system integrity, I

and accidental criticality as bases for recommending prompt removal of the krypton.

None of these con-cerns have sufficient merit to justify a conclusion that personnel entry is necessary within a few weeks or months.

A delay of a year in removal of the krypton would not pose an undue risk to the health and safety of the public.

However, because of the possibility of unfor-1 seen problems, the delay should not be more than a year and a half.

If an unforseen emergency developed, the krypton could be removed in a few days using the

' venting scheme recommended by Met Ed and the NRC staff.

RADIATION EXPOSURE We carried out independent calculations of the beta skin dose exposures and gamma whole body exposures expected downwind under the plume from a complete purge'of the TMI containment building by venting under varied conditions and at a range of vent altitudes.

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The greatest radiation exposures result from the venting proposal advanced by Met Ed and NRC.

Re-lease heights well above the largest structures at TMI reduce the doses markedly, and in some cases by enormous factors.

The largert gamma dose a person could receive under the Met Ed/NRC proposal is 0.03 millirem and occurs close to the plant.

It corresponds'to 3 hours3.472222e-5 days 8.333333e-4 hours 4.960317e-6 weeks 1.1415e-6 months of exposure to the naturally-occurring rndicactive back-ground of approximately 100 millirem per year.

The beta skin doses are tyoically 100 or so times greater than the ga=ma doses, but involve only a limited portion of body tissue.

Evidence suggests that beta doses in excess of 10,000 to 50,000 milli-ram are required to increase the incidence of skin cancer.

UCS concluded that direct radiation-induced health effects from exposure to Kr-85 even from the Met Ed/

NRC proposed venting wculd be absent.

These conclu-sions are similar to thase reached by the NRC and Met Ed.

STRESS-INDUCED PUBLIC HEALTH EFFECTS There has been marked stress-induced illness in persons living within ten miles of TMI.

This has surfaced in angry con-frontations between citizens and NRC and Met Ed officials.

A recent medical study has shown thet between lot and 20% of the some.200,000 people living within 10 miles of TMI show evidence of " physical stress" including headaches, diarrhea, and stomach trouble, and " behavioral stress," including irritabilit", sleep-lessness, and loss of appetite.

UCS concludes that this indicates a stress-induced medical problem of major public health importance.

There is good reason to believe that at least the Met Ed/NRC venting, already opposed by many citizens, may seriously exacerbate this problem.

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os VENTING PROPOSALS UCS has devised two venting schemes in which radiation exposures are much lower than the already small exposure ex-pected from the Met Ed/NRC proposal:

The first makes use of a gas or oil-fired small incin-erator feeding a 6 foot diameter 250 foot stack.

The contam-inated containment air is, fed into the furnace, buoyed by the heat, and elevated far above the stack and all TMI structures.

This scheme can yield an effective release height approaching 1000 ft. and in some cases more.

The reduction in radiation exposure at 2 miles from i

TMI, for example, is by a factor of 4000 over the Met Ed/NRC case, and a factor of 15 at 5 miles.

This scheme uses conventional technology, is prac-tical, reasonably rapid to implement, and of modest projected cost.

The second UCS proposal would vent from a reinforced fabric tube, supported by a tethered balloon at 2000 ft. altitude.

U.S.

Air Force balloon experts made a preliminary review of the pro-posal and found it workable.

The ground-level radiation' is so low with this scheme (very much lower than even the hot plume),

that in all probability it.could not be detected at all.

Tethered balloon venting appears to be a practical proposal in terms of costs, schedules and especially, radiation exposure.

Some residual questions can be rapidly resolved by tests at Hollomon Air Force Base and by a TMI site visit.

Air Force balloons and handling gear might possibly be available for the TMI venting if appropriate.

l It is not certain, however, that either of these schemes would be perceived as acceptable by the citizens of the area.

The same psychosocial prob-lems as we anticipate would occur with the proposed

., Met Ed/NRC venting could occur with any deliberate release of Kr-85, even if dose reductions of the magnitude expected by the two methods suggested were achieved.

. _ ~

56 KRYPTON RECOVERY PROPOSALS Use of a selective absorption system to recover the krypton for storage avoids a deliberate releas-to the environment, but there is a question whether it can be implemented in less than a year.

There has been extensive experience with pilot plants at Oak Ridge National Laboratory.

Therefore, there is a high degree of assurance that construction of a selective absorption system ten times larger than the pilot plant would be an effective means of krypton recovery.

A determination of the availability of the necessary components can be done in a few days to help determine whether the system could be imple-t mented in less than a year.

A cryogenic processing system to recover the krypton l

for storage would also avoid any deliberate release l

to the environment.

Three cryogenic systems now in l

storage at the construction site of the Hope Creek nuclear plant have a total capacity sufficient to recover the krypton from the TMI containment in a few months.

Construction at the TMI site would take two or three months after a suitable building is available.

The owners of the cryogenic systems are willing to sell them to Met Ed and that would not delay construction of the Hope Creek plants.'

The gas compression and charcoal adsorption methods of krypton recovery do not merit further consideration.

Considering the very low public and worker radiation l

doses resulting from an elevated venting scheme, selec-tive absorption or cryogenic processing, it is unlikely j

that either gas compression or charcoal adsorption could achieve lower doses.

Furthermore, the construc-l tion time for either a gas compression or charcoal adsorption system could not be as short as the time I

needed to implement elevated venting, selective ab-sorption, or cryogenic processing.

l The tethered balloon scheme might prove valuable as an emergency backup system if one of the krypton recovery schemes were selected.

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B.

Recommendations i

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 compara.tle to those expected from the Met Ed/NRC venting proposal.

We recommend evaluation and public discussion of the two UCS venting proposals, each of which would yield a markedly decreased ground-level radiation exposure.

Each appears potent.ially attractive, but there remains an open question of citizen acceptability of deliberate releases of Kr-85.

Evaluations can be carried out promptly.

We recommend reevaluation and public discussion of 4

the two krypton recovery proposals previously rejected by the NRC and Met Ed:

cryogenic processing and selec-tive absc.ption.

Because each recovery method has the potential for implementation within one year, either one might prove the technique of choice in ridding the containment building of Kr-85.

We recommend that the final choice among the alternatives give significant weight to the need we identify. of having the krypton removed within one year.

This must be in addition to the absolute need to ensure the health and safety of the much-stressed population around TMI.

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50 Appendix I Incinerator Information.

The following information was obtained on the high temperature, high velocity, high stack incinerator. Dr. Thomas i

Overcamp made the original suggestion of the use of a 6-foot diameter incinerator stack, approximately 200 feet high.

Such incinerators are made by the John Zink Ccmpany, located in-Tulsa, Oklahoma.

John Young, one of their engineers in their Process Systems Division,was very helpful.

Conversation with him produced the following details:

He believes that the incinerator concept is a very workable idea.

He is of British background and spoke of having significant experience in the UK in dealing with the release of various pollutants through similar means.

He said that they were very successful but wen the disfavor of the Norwegians due to their ability to left it out of the UK and into Scandinavia.

i He recommended the use of a 6-foot. diameter refractory-l line stack.

He felt that 200 to 250 feet would be t

l ideal and further recommended a discharge terperature of 1800?F and a velocity of approxima :ely 100 feet s

l per second.

Such conditions would permit the incinera-I

-tor to be operated only with a natural draft from N

e i- ;.

is the stack, giving a negative furnace pressure which would be highly desirable in minimizing ground-level leakage.

He calculates it would require approximately 10 to I

6 40 x 10 BTU's per hour to maintain these stack conditions.

He recommends firing with gas rather than fuel oil and indicated that either natural gas or liquified petroleum would be fine.

UCS has checked with Met Ed on the availability of natural gas on site and does not have a firm answer yet.

The pre-liminary response was that the quantity was not available.

UCS checked locally in California on availability of LP gas.

LP gas has a heating value of approximately 90,000 BTU's/ gallon.

Based on this heating value and the 20 million BTU's per hour, operation would require approximately 200 to 250 gallons per hour or, assuming 10 hours1.157407e-4 days 0.00278 hours 1.653439e-5 weeks 3.805e-6 months operation per day, roughly 2,000 gallons per day.

LP gas is available in California at a cost of about $.75 per gallon, so the fuel cost would be something less than $2,000 per day.

Young recommended using an incinerator with a self-suppo;;_ng stack.

Stack sections are normally fabricated

. in 50-foot lengths and his estimate of time to erect ej

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60 the system was about one month.

This time, of course, follows manufacture of the equipment and assumes' an appropriately designed foundation.

Ballpark estimates for time to design and manufacture, and cost cf procurement are:

Fourteen weeks from date of order for production of drawings for approval.

Fourteen to eighteen wecks frem date of drawing approval for manufacturing.

i Cost of the system would be approximatcly S200,000 to $250,000 complete with stack, burners, and controls.

This would not, of course, include th,e fuel supply piping or necessary auxiliary power but if fuel is supplied by tank truck, this should not be an expensive system.

UCS has not done any checking on availability or comp *.exity of piping systems for the expansion of LP gas at the necessary flow rates, but it is likely that freeze-up problems might be predicted.

l l

Total weight of the incinerator is estimated at 130,000 lbs.

The combu,stion chamber is a part of the lower stack section and would probably be about 10 feet in diameter.

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cA Appendix II This appendix, relating to the tethered balloon venting scheme, includes:

1)

Letter to H.W. Kendall from Thomas W. Kelly, Director, Aerospace Instrumentation Division, U.S. Air Force Geophysics Laboratory.

2)

Air Force Feasibility Evaluations.

Further attachments referenced in the latter document are omitted ! rom the UCS Report.

A version of the referenced figures is included in the body of the report as Figure 2.

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'M @'k%tk DEP ARTMENT OF THE AIR FORCE AIR FORCE GEOPHYSICS LABORATORY (AFSC)

HANSCOM AIR FORCE BASE, MASSACHUSETTS 01731

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R$ PLY TO Am o's LC (Mr. Kelly, 3004) 8 May 1980 Feasibility Evaluation sume er:

Professor Kendall Union of Concerned Scientists 1384 Massachusetts Ave.

Cambridge, MA 02133

Dear Professor Kendall,

The enclosed memorandum summarizes a rather hurried assessment of the feasibility of using a tethered balloon for Krypton disposed at Three _

Mile Island. Although the assessment is hardly definitive, all balloon related aspects of the undertaking are well within the range of existing balloon technology.

The problem, of pumping air through a long flexible tube at comparatively high rates is outside our experience, however, the enclosed calculations indicate that the desired flow rates can be achieved. This result can easily be verified by a simple, inexpensive experiment to put that uncertainty at rest. The remaining question concerning the suitability of Three Mile Island for tethered balloon flight operations can best be resolved by a brief site survey -- a matter of one day.

Please call if the Air Force Geophysics Laboratory can be of further assistance in this matter.

Sincerely, 1

THOMA W KELLY 1 Atch Director a/s Aerospace Instrumentation Division 6,

s D

t

63 FEASIBILITY EVALUATION The Aerospace Instrumentation Division of the Air Force Geophysics Laboratory has reviewed' the feasibility of raising a 1 ft, diameter flexible tube, to an altitude of, two thousand feet above the Three Mile Island Nuclear Power Plant using a tethered balloon. Our conclusion is that the proposed balloon operation is indeed feasible. The suggested configuration is that of using a single 45,000 cu. ft tethered balloon with two tether lines. The first line would be positioned over ground zero and serve _to support the flaxible tube while the second line would be used to raise and

~

lower the system and to pre' vent twisting of the flexible tube.

A candidate tube material is ILC Advanced Balloon Material which weighs 2

8 oz/yd and has an allowable stress of 117 pounds / inch. Calculations have 3

indicated that a flow rate of 60 to 100 ft /sec can be maintained with a 10.0 psi differential pressure. This would result in a maximum stress level of only 60.0 pounds / inch, well below the 117 allowable.

The balloon itself, when filled with helium, would have a gross lift of 2800 pounds. The net lift is then calculated by subtracting the balloon weight (1000!), the tube weight (350#) and the weight of the two tether lines (140#). This results in a net lift of 1300f, more than enough to insure stability under 20 knot wind conditions.

The proposed concept is based upon the availability of an unobstructed space on the order of 2000 feet long by 200 feet wide.

If open spaces of this magnitude are not available, other concepts, although less desirable, may be feasible.

Attachment #1 to this document gives the flow characteristics of the gas venting tube, while figure #1 and 2 define the balloon system configuration.

Questions relating to the operation of such a balloon system including limitations imposed by air safety, flight control instrumentation, costs and schedults have not been addressed.

--

ML19317H393

Text

Dear Professor Kendall,

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