ML19317H370
| ML19317H370 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 05/31/1980 |
| From: | Cline J, Thomas C, Voilleque P SCIENCE APPLICATIONS INTERNATIONAL CORP. (FORMERLY |
| To: | |
| References | |
| NUDOCS 8006020348 | |
| Download: ML19317H370 (49) | |
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ogr PELIMIMRY DRAFT COMPARISON OF CONTROLLED PURGE AND APPLICATION OF THE SELECTIVE ABSORPTION PROCESS ALTERNATIVES FOR DECONTAMINATION OF TMI-2 REACTOR BUILDING ATMOSPHERE IHIS DOCUMENT CONTAINS (T P00R QUAUTY PAGES C. D. Thomas, Jr.
D. T. Pence P. G. Voillequd B. E. Kirstein J. E. Cline C. A. Pelletier Science Applications, Inc.
May 1930 PELIMIMRY DPAR
~ 8 0 0 6 0 2 0 3Y8 p
TABLE OF CONTENTS Pace 1.
INTRODUCTION 1-1 1.1 Status of TMI-2 Reactor Core and Containment Building 1-1 1.2 Reactor Building Reentry Requirements 1-3 1.3 Dose Rates From 85Kr and Other Sources in the Containment 1-4 1.4 Alternative for 85 r Removal 1-6 K
1.5 Regulations Pertaining to Environmental Radiation Exposure 1-7 1.6 Sources and Atmospheric Inventory of 85 r 1-8 K
1.7 Report Organization 1-9 2.
TECHNICAL EVALUATION CRITERIA 2-1 2.1 Feasibility 2-1 2.2 Effectiveness 2-1 2.3 Practicality 2-1 2.4 Schedule 2-1 2.5 Health and Safety 2-2 2.6 Resource Requirements 2-2 3.
SYSTEM DESCRIPTIONS AND TECHNICAL EVALUATIONS 3-1 85 3.1 System'for Kr Decontamination by Controlled Purge of the Reactor Building 3-1 3.2 Technical Evaluation of Controlled Purge Decontamination System 3-3 3.2.1 Feasibility 3-3 3.2.2 Effectiveness 3-3
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3.2.3 Practicality 3-4 3.2.4 Schedule 3-4 3.2.5 Health and Safety 3-5 3.2.5.1 Radioactivity Releases to the Environment 3-5 3.2.5.2 Radiation Doses to Individuals and Populations 3-6 3.2.5.3 Health Effects 3-8 3.2.6 Resource Use 3-10 3.3 System for Decontamination Using the Selective Absorption Process to Remove 85Kr 3-10 3.4 Technical Evaluation of the Selective Absorption Process 3-12 3.4.1 Feasibility 3-15 3.4.2 Effecciveness 3-13 3.4.3 Practicality 3-14 3.4.4 Schecale 3-15
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3.4.5 Health and Safety 3-18
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TABLE-OF CONTENTS (continued)'
Pace 3.4.5.1 Radioactivity Releases to the Environment 3-18 3.4.5.2 Radiation Doses to Individuals and Populations 3-20 3.4.5.3 Fluorocarbon Releases to the Environ-ment 3-22 3.4.5.4 Health Effects 3-22 3.4.6 Resource Requirements 3-24 4.
2.YSTEM COMPARIS0N 4-1 4.1 Feasibility 4-1 4.2 Effectiveness 4-1 4.3 Practicality 4-1 4.4 Schedule 4-1 4.5 ' Health and Safety 4-3 o4.6 Resource Use 4-3 4,7' Psychological Stress 4-3 4.8 Cost Comparisons 4-5 5.
CONCLUSIONS AND RECCMMENDATIONS 5-1 b
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FIGURES Table Page 3-1 System for. Controlled Purge of Reactor Building............................................
3-2
.3-2 Schematic of the Selective Absorption Process.............................................
3-11 3-3 TMI-2 Reactor Building Decontamination Schedule............................................
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TABLES Figure Page 1-1 TMI-2 Containment Dose Rate Estimates for General Area s on Each El eva ti on......................
1-5 3-1 Expected and Potential Releases of Radionuclides for the Controll ed Purge Al ternati ve.................
3-6 3-2 Radiation Doses to Individuals for the Controlled Purge Alternative....................................
3-7 3-3 Radiation Doses to Population Groups for the Controll ed Purge Al ternative.........................
3-8 3 Heal th Effect Inci dence Ra tes........................
3-9 85 3-5 Expected, Probable and Potential Releases of Kr for the Selective Absorption Process Al ternate.......
3-19 3-6 Radiation Doses to Individuals for the Selective Abs orption Proces s Al terna ti ve.......................
3-21 3-7 Population Doses for the Selective Absorption Pro ces s Al te rna ti ve..................................
3-23 4-1 Compa ri s on o f Al terna ti ves...........................
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Section 1 INTRCDUCTION Background information on the current status and planned recovery operations at the Three Mile Island Unit Two (TMI-2) nuclear power plant is presented in this section.
The first subsection discusses the current status of the reactor core and airborne radioactivity levels within the containment. The need for reentry into the TMI-2 reactor containment building is then discuss-ed. The doses due to the radioactive krypton gas (85Kr) and other radiation sources in the containment are presented in subsection 1.3.
The fourth 85 subsection briefly reviews the alternatives for Kr removal, the conclusions reached in previous evaluations, and the need for the present evaluation.
Subsection 1.5 briefly discusses the pertinent regulations and subsection 1.6 85 describes the present world atmospheric inventory and other sources of Kr in the environment.
1,1 Status of TMI-2 Reactor Core and Containment Building The exact condition of the reactor core at TMI-2 is presently unknown. There have been several estimates of the damage but until the core can be examined there is no way to determine its actual condition.
It is generally accepted, however, that the core did undergo severe damage resulting in disruption of the core geometry.
The damaged fuel in the reactor vessel remains in a safe shutdown mode, with' natural circulation cooling.
Only one core neutron monitoring device is presently operable.
It provides the only real time information confirming the safe shutdown configuration. The core is in corrosive environment (pH 8) as a result of the addition-of sodium hydroxide to the coolant during the accident.
1-1
o.
There are three areas of increasing concern about the status of the core.
The first.is that of a further loss of coolant may occur due to corrosion.
The primary coolant is itself corrosive and portion of the reactor coolant system piping is submerged in corrosive sump water.
The primary coolant pump seals are another possible source of leakage.
Further loss of pri-mary coolant is not a great concern, but having the system far beyond de-sign conditions is not a comfortable position.
The second area of. concern is a possible change in fuel geometry. A core geometry shift could disrupt the present coolant flow paths and change the core cooling situation.
The fuel itself may be corroded and further distributed throughout the primary system, increasing the difficulty of system decontamination.
The last area of concern is that of recriticality. This would have to be considered an
" accident" in that it appears that the core could not achieve a critical condition with the present levels of boron in the reactor coolant system.
The boron would have to be substantially reduced before critically could become possible.
The only mechanism for this to happen would be the inadver-tent admission of unborated water to the primary coolant system.
The TMI-2 reactor containment building has been sealed since before the accident on 28 March 1979.
The containment has been maintained below atmo-spheric pressure for more than a year by the building air cooling system.
This has prevented leakage of fission products out of the reactor building to the environment. Most of the gaseous fission products initially present in the reactor building atmosphere have decayed to undetectable and insigni-ficant levels during the past year.
Repeated measurements have shown the 85 principal nuclide remaining in the containment atmosphere to be Kr.
The reactor containment building atmosphere of TMI-2 presently contains approxi-86 85 3
mately 57,000 Ci of Kr. The measured Kr ccncentration is 1.0 uCf/cm,
1-2 e
r..
-5 The concentrations of other_ isotopes are much smaller:
approximately 4x10 uCi/cm for tritium (3 ), lx10~9 3 for radiocesium (137Cs), and lx10 3
-10 fi uCi/cm 3
129 137 uCi/cm for 1.
The airborne H and Cs inventories are approximately 2 Ci and 0.00006 C1, respectively.
l.2 Reactor Buildiac Reentry Recuirements There are several important reasons why reentry into the TMI-2 reactor building is necessary.
In summary, it is necessary to assess the damage resulting from the accident and to plan and prepare for reactor building decontamination and removal of the damaged fuel.
These general needs en-compass a large number of specific tasks that require reentry.
Some examples are:
o assess the levels and distribution of surface contamination within the reactor containment building o obtain samples to determine the optimum procedure for surface decontamination o perform detailed surveys required to define the radiation fields in the building o perform maintenance on vital equipment, such as the building air-coolers o install additional neutron and radiation monitoring equipment o
inspect equipment needed for decontamination and fuel removal All these tasks must be completed before the building can be der.ontaminated and the. fuel removed.
Detailed preparation and planning cannot proceed significantly until data on actual conditions are obtained by reentry teams.
The planned decontamination of the TMI Unit 2 reactor building is in two phases:
(1) removal of the contaminated water from the building sump and 1-3
4 (2) removal of contamination from building and component surfaces and re-moval of components that have high levels of internal contamination.
Both phases must be' completed before removal of the reactor core can begin.
The schedule for removal of the sump water calls for processing to begin in December 1980.
It is estimated that sump water processing will take 85 four to five months.
It is not necessary that the Kr be removed from the containment for this task to proceed.
Decontamination of the building and component surfaces is a two-step process:
assessment and planning 85 followed by actual decontamination.
Both efforts require removal of Kr from the building atmosphere. To maintain tha schedule of beginning the decontamination when the majority of sump water has been removed, it is necessary to start the contamination assessment and planning work in Septem-85 ber 1980.
Hence the presence of Kr in the building will delay decontamina-tion at about that time.
85 1.3 Dose Rates From Kr and Other Sources in the Containment 85 The estimated contributions to the total dose rate from airborne Kr, surface deposition of fission products, and radionuclides in the sump water are presented in Table 1-1 for the areas to be visited in the first contain-ment reentry efforts (1).
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Table 1-1 TMI-2 CONTAINMENT DOSE RATE ESTIMATES F0F, GENERAL AREAS CN EACH ELEVATION Dose Rate at Specified Location (rem / hour)
Surface Sump 85 Location-Tissue Kr Decosits Water Total 305' Elevation Whole Body 0.9 0.2 1.5 2.6 (Air Lock Elevation)
Skin 9
1 10 347 Elevation Whole Body 1.2 0.4 1.6-(Operating Floor)
Skin 9
2 11 Stairs #1 and #2 Whole Body 1.2 0.2 9.0 10 Skin 9
1 10 Airlock Whole Body 0.9 0.9 Skin 9
9.0 Anteroom Whole Body 0.1 0.1 (Outsit3 Airlock)
Skin 1
1 A
85 Since the principal mode of decay of the Kr gas is by beta particle emission, the dose rate to unprotected skin would be quite large, 9 rem / hour inside the 85 containment.
The Kr contribution to the whole body dose is 35% of the total on the 305' level and 75% of the total on the 347' level.
The. radiation field in the stairwells and on lower levels is dominated by the sump water source.
85 The whole body dose rate from Kr in the reactor-building reduces the maxi-mum stay _ time of any reentry team and the unexposed skin dose rate necessitates
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the use of heavy and cumbersome diving' suits for skin protection during re-entry.
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85 1.4 Alternatives for Kr Removal A brief review of previous evaluations of alternative methods for removal 85 of Kr from the reactor building atmosphere is-presented to place the pre-85 sent comparison in context.
Five alternative methods of Kr removal have been considered:
o controlled purge of the containment atmosphere 85 o adsorption and storage of Kr on charcoal 85 o compression and storage of the gas containing Kr 85 o cryogenic treatment to remove the Kr from the gas in steel cylinders and long-term storage 85 o selective fluorocarbon absorption of Kr from the gas and long term storage in steel cylinders 85 The controlled purge discharges the Kr in the reastor building to the
-environment under meteorological conditions that would provide good dispersion 85 and dilution of the effluent.
The Kr release would be conducted under pre-scribed conditions to limit doses to individuals and to the population near the site.
The other four systems involve treatment of the containment atmo-sphere to remove and concentrate most of the Kr for long term storage (85 85 Kr has a 10.7-year half-life).
Use of one of these systems would reduce planned 85 releases of Kr to the local environment but result in increased risk of accidental releases.
I In November 1979 the Metropolitan Edison Company submitted a safety analysis and environmental report (2,3,4_,5) to the Nuclear Re'gulatory Commission (NRC) in support of their' proposal to conduct a controlled purge of the TMI-2 reacter building atmosphere.
In March 1930, the NRC Staff published an environmental assessment for the decontamination of the TMI-2 reactor building atmosphere (f_).
The Staff concluded that a controlled purge was an acceptable decontamination metned; it met all pertinent regulatory requirements.
The NRC Staff also 1-6
- determined that the alternative systems were acceptable with regard to radiation exposure of nearby residents. The anticipated delay required to design, procure, install, and test such systems was a factor in their recommendation that the controlled purge plan be adopted.
In late March 1980, an independent review (_7_) of the alternatives concluded that a treat-ment that has zero, or nearly zero, release to the atmosphere and concen-85 trates the Kr in gas cylinders would be the most desirable. The reviewer ranked the selective absorption process and the cryogenic processing system as the best and next best alternatives, respectively. The reviewer judged the imple....entation time and system cost estimates of 1 1/2 years and $4 million to be reasonable.
The "near zero release" criterion appeared most important-in the selection of the selective absorption process.
The impacts of time delay, occupational radiation exposure, and system cost were not evaluated.
Differing estimates have been made (References 2-8) of parameters important to the decision process..The purpose of this report is to provide an inde-pendent review of two alternatives now being considered to decontaminate the containment atmosphere:
controlled purge and selective fluorocarbon absorption.
l.5 Reculations pertaining to Environmental Radiation Excosure The NRC regulations controlling environmental radiation exposure are contained in 10 CFR 20 (Reference 9). Design guidelines for light water cooled reactors
.(LWRs) like TMI-2 are contained in Appendix I to 10 CFR 50 (Reference 10).
In developing Appendix I to 10 CFR 50, the Nuclear Regulatory Commission per-formed a thorough evaluation of radioactivity releases in effluents from LWRs.
The goal of the evaluation was criteria to provide numerical definition of release rates that were "as icw as reasonably achievable".
The first draft 1-7 e
numerical criteria, stated in terms of dose to the maximally exposed indivi-dual, were proposed 4 mid-1971. A public rule-making hearing was initiated.
An environmenthi impact statement was drafted, reviewed by many interested parties, and finalized. After an extensive hearing procedure, review, and analysis the final dose criteria were established.
The two criteria most relevant to the present consideration are the 5-mrem annual dose to the whole body and the 15-mrem annual dose to the skin.
Limiting ef?luent re-leases to achieve the Appendix I dose criteria assures that the operations meet the ALARA criterion and that the annual whole body doses resulting from LWR operation will be less than 5 percent of average doses from natural back-ground radiation.
Natural background radiation doses average about 100 mrem /
year in the United States.
The radioactivity release rates required to meet the ALARA dose criteria are more restrictive than those set forth in the Technical Specifications for operation of TMI-2.
Meeting Appendix I criteria also assures compliance with the relevant Environmental Protection Agency guidance for nuclear reactor fuel cycle facilities in 45 CFR 190 (11).
85 1.6 Sources and Atmospheric Inventory of Kr 85 The current average concentration of Kr in the world's atmosphere is between 3
3 15 and 20 pCi/m.
It rose from a level of about 1 pCi/m in the mid-1950s, principally due to nuclear weapons production and testing and other defense 85 related activities of several countries.
Most of the Kr in the environment 85 remains in the atmosphere.
The current atmospheric inventory of Kr is about 80 million curies (12_).
Releases ~ from the Savannah River Plant (SRP) and the Idaho Chemical Processing 85 Plant (ICPP) are the principal sources of Kr in the United States.
Between 1-3 e
March 1975 and September 1977, for example, SRP releases averaged about
' 53,000 Ci/ month (13).
Releases from the ICPP have been intermittent but have been as high as 20-30,000 Ci per month (14).
1.7 Report Organization The reports and background material described in the previous subsection have been reviewed in detail as part of the present assessment of the rela-tive merits of the selective absorption process and a controlled purge as methods of decontaminating the TMI-2 reactor building atmosphere.
Portions of those de 'iments are discussed in more detail in later sections.
Section 2 presents the criteria considered in the evaluation of these two processes.
Section 3 describes the technical features of the two proposed alternative techniques.
Section 4 contains comparisons of the two systems.
Section 5 the conclusions and recommendations of the study.
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F-Section 2 TECHNICAL EVALUATION CRITERIA Six principal criteria were used in the technical evaluation of the two systems now being considered for decontamination of the TMI-2 reactor building atmosphere. These criteria are o feasibility o e.'fectiveness o practicali ty o schedule' o health and safety o resource requirements Each is discussed separately below.
2.1 Feasibility To merit serious consideration, any technological decontamination alternative must be feasible; that is, it must have been developed to the point that its' application to the problem is reasonable from a scientific and engineering s tandpoint.
2.2 Effectiveness 85 Any proposed decontamination technique must be capable of removing the Kr from the reactor building in a reasonable period of time after installation.
2.3 Practicality The practicality criterion addresses the operational complexity of the system, its reliability, and maintenance requirements during the period of performance.
2.4 Schedule
-The overall schedule for accomplishing the decontamination is important for reasons described in the Introduction.
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.s 2.5 Health and Safety The most important criterion in the evaluation of the alternative systems is health and safety.
There are several aspects that deserve consideration.
From the radiological safety point of view, the collective dose to the population (also termed the population dose) is generally taken as the prin-cipal naasure of impact on human health.
There are three principal sources of population dose to be considered:
exposure to the public residing near the facility, exposure to the workers within the plant, and, because any 85 released Kr will be gradually dispersed around the world, exposure of the world population. Other health and safety aspects of the area requiring consideration are general worker safety, industrials hygiene, potential conse-quences of. fluorocarbon releases to the atmosphere, and mental stress.
2.6 Resource Requirements Resource requirements for the alternative techniques are also an important consideration.
Space and building requirements for the decontamination system, technical manpower needs, use of critical materials, and energy consumption are all components of this criterion.
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Section 3 SYSTEM DESCRIPTIONS AND TECHNICAL EVALUATIONS The two decontamination alternatives, controlled purge and selective flouro-carbon absorption followed by purge, are described in subsections 3.1 and
-3.3 respectively.
Each alternative is evaluated in each of the six tech-nical~ areas described in Section 2.
The results of the technical evaluation are presented in subsections 3.2 and 3.4.
85 3.1 System for Kr Decontamination by Controlled Purce of the Reactor Buildinc 85 Metropolitan Edison has proposed removal of the Kr from the TMI-2 reactor building using a controlled purge rate to limit the offsite doses.
The venting
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would be accomplished in a manner that would meet all regulatory requirements i
including the TMI-2 Technical Specifications.
The controlled reactor building purge program is described in References 2-5.
Figure 3-1 shows the existing hydrogen control subsystem,' as modified, that would be used for decontamination by controlled purge.
The system flow rate can be controlled in steps up to a maximum of 1000 cfm. The gas removed from the reactor bui.1 ding would first pass through a sequence of filters: a pre-filter, a high efficiency particulate'(HEPA) filter, a charcoal adsorber, and a second HEPA filter. This combination would remove more than 99.9% of the 129 85 airborne particulate material and about 99% of the airborne 1.
The Kr 3
and the H in the reactor building atmosphere would pass through these filters and be released-to the atmosphere via the Unit 2 vent stack.
85 To meet' the Appendix I dose objectives the Kr relea~se rate (pCi/sec) would be controlled and adjusted hourly as a function of atmospheric dispersion con-ditions.. For a specified release rate, the acceptable purge flow rate depends b
on the. measured Kr concentration in the containment.
At the start of the r
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Lr REACTOR DUILDIrlG
[><C - [
N STACKj
[><0 VENT
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E 111C11 Eff!CIENCY PURGE N
AND CilARC0AL EXilAUST Fall fit'TERS FIGURE 3.1 SYSTEM FOR CONTROLLED PURGE OF REACTOR BUILDIl1G
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85 controlled purge, the Kr concentration in the reactor building will be 3
1.0 uti/cm and the purge flow rate would be relatively low (perhaps about 100 cfm). As venting continues the krypton concentration in the reactor building will decrease and, for the same dispersion conditions, the flow rate can be increased.
During periods of unfavorable meteorology when dispersion would be poor the release would be decreased or stopped, and increased or
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restarted only when meteorological conditions improved.
Reference 6 describes an accelerated venting program using the station's normal containment purge system.
This would provide increased flow rate capacity that could be used 85 when Kr containment concentrations are low and meteorological conditions are favorable. As described, this approach would meet all regulatory requirements with the exception of the TMI-2 operating Technical Specification for instan-taneous release of noble gases. The NRC staff had proposed this modification if it could be implemented by the middle of May.
3.2 Technical Eva?uation of Controlled Purce Decontamination System The results of the technical evaluations in each of the six areas are presented below.
3.2.1 Feasibility The controlled purge system is a technically feasible method of decontaminating the TMI-2 reactor building atmosphere.
It is similar in principle to contain-ment purge systems installed at Three Mile Island and other pressurized water reactors (PWRs) and routinely employed for the same purpose.
3.2.2 Effectiveness Reactor building purges have been shown to be an effective method of removing noble gases from PWR reactor buildings. The tecnnique is used routinely at operating reactors to remove radioactive gases prior to containment entry.
The decontamination factor (DF) of the system is proportional to the volume 3-3
of gas purged..The OF can be increased to any desired level by continued purging.
In this case, it has been estimated that a total volume of about 130 million cubic feet must be purged to hieve a reactor building concen-tration of 10-6 pC1/cm. At a continuous purge rate of 1000 cfm this could 3
be accomplished in 21 days.
The approximate duration of purge is estimated to be 60 days, but will depend on actual meteorological conditions.
3.2.3 Practicality Operation of the purge system itself is a relatively simple inanner. A detailed operational procedure that incorporates all the steps required to assure proper system operation during the controlled release has been prepared.
Eight modi-fications of the hydrogen control system are required before tne controlled purge could take place. We have determined that all but one of these modifica-tions have been completed. The one remaining modification, uncapping the Unit 2 vent stack, cannot be completed until approval of the controlled purge option.is obtained.
3.2.4 Schedule It is estimated that 1-4 days would be required to perform the last system modification described above and to obtain the initial approvals required by the controlled purge operational procedure.
The overall duration of_ the con-trolled purge is estimated to' be 60 days from the time of initiation. This estimate.is based on computer simulations performed using historical meteoro-logical data.
The historical data are only a general guide since conditions vary from year to year and cannot be predicted in advance. However, since the purge could begin promptly after approval, a longer purge duration would probably not have a deleterious impact on the planned schedule (Section 1.2).
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3.2.5 Health and Safety The health and safety aspects of the controlled purge decontamination alternative are considered in this section. The three subsections consider radioactivity releases to the environment, radiation doses to individuals and to populations, and the potential health effects resulting from selection of this alternative.
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3.2.5.1 Radioactivity Releases to the Environment 85 In Table 3-1, the expected and potential Xr releases are given for the controlled purge decontamination alternative.
It was assumed that one con-tainment entry would be made before the controlled purge was initiated and that subsequent entries would be delayed until the purge was completed.
85 It was assumed that the controlled purging removed all the Kr in the 3
reactor building.
An upper limit estimate of the H release during the purge is also given in the table.
An unplanned release could occur if the full flow of the controlled purge system were unintentionally activated.
This release is considered unlikely 85 but, if it did occur, approximately 1700 Ci of Kr could be released to the 85 environment in one hour.
If the accidental release occurred, the total Kr activity released during the purge would be decreased by the amount of the accidental release.
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Table 3-1 EXPECTED AND POTENTIAL RELEASES OF RADIONUCLIDES FOR THE CONTROLLED PURGE ALTERNATIVE Radionuclide Release (Ci) 85 3{i Activity Causing Release Kr EXPECTED Controlled Purge 57,000 30 Containment Entry 25 0.0008 POTENTIAL Accidental Initiation of Purge 1700 0.06 3.2.5.2 Radiation Doses to Individuals and Populations Three population groups will. receive radiation exposure as the result of
. selecting the controlled purge alternative. These are the general popula-tion of. nearby residents,' nearby residents who are plant workers, and the entire population of the world.
The expected maximum individual doses for
.each group are shown in Table 3-2.
These dosos result almost entirely from O
the discharge of the Kr; there is no significant contribution from the discharged 3H. The maximum individual doses for a release of 57,000 Ci
-6 3
was computed using an annual average dispersion factor of 1.8x10 sec/m for'a vent release and the dose conversion factors given in Regulatory Guide 1.109 (15).
The maximum skin dose under those conditions would be 4 mrem. The maximum whole body dose to a member of the local population is 0.05 mrem. Doses received by individuals at locations remote from the plant are variable but extremely smal!. All the doses from expected releases e
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Table 3-2 RADIATION DOSES TO INDIVIDUALS FOR THE CONTROLLED PURGE ALTERNATIVE Maximum Individual Exposed Group Dose (mrem)
EXPECTED Whole Body Skin Nearby Residents General Population 0.05 4
-5
-3 World Population
<10
<10 POTENTIAL Nearby Residents General ~ Population 0.7 50 are well below those received from natural background sources.
The consequences of accidental initiation of the reactor butiding purge
-4 system were computed using a site boundary dispersion factor of 6.8 x 10 3
-sec/m and the dose conversion factors from Reference 15. The maximum potential. doses are 50 mrem to the skin and 0.5 mrem to the whole body.
.These are well-below the guide values in Reference 16.
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Table 3-3 contains the maximum population doses expected from the controlled 85 purge of Kr.
The largest contribution to the total comes from the life-time integrated population dose received by the world's inhabitants (12,).
Table 3-3 RADIATION DOSES TO POPULATION GROUPS FOR THE CONTROLLED PURGE ALTERNATIVE Exoosed Group poculation Oose (person-rem)
Whole Body Skin Nearby Residents General Population 1
80 Plant Workers 1
(a)
World Population 20 2500 Total 22 2600 (a) None in addition to that from whole body exposure.
3.2.5.3 Heal th Effec's The number of radiation induced health effects expected in an exposed population is generally considered proportional to the total population dose (person-rem).
The proportionality factor is the incidence rate per unit population dose (cases / person-rem).
Incidence rates have been derived from data on human exposure to relatively high radiation doses delivered at high dose rates.
However, it is recognized that when the individual doses re-ceived are quite small use,of such derived incidence rates and the popula-tion dose probably overestimates the number of health effects (H). The 38
incidence rates used to calculate health effects in this report are shown in Table 3-3.
Table 3-4 HEALTH EFFECT-INCIDENCE RATES Incidence Rates (cases /oerson-rem)
Exoosed Tissue fatal Not Fatal Genetic Defects (a)
Whole Body 2x10-4 2x10-4 3x10-4 Skin lx10-6 lx10 None
-5 (a) All such cases are assumed to. result in deaths of fetuses in the early stages of development.
With these incidence rates, the population doses summarized in Table 3-2 can be used to estimate the maximum number of health effects expected from selection of the controlled purge alternative.
The maximum number of health effects expected in the nearby population is 0.0005 fatal cancers, 0.001 non-fatal cancers, and 0.0006 genetic defects.
The maximum number of health effects expected in the world population is 0.007 fatal cancers, 0.03 non-fatal cancers,~and 0.006 genetic effects.
The same incidence rates can be used to estimate 'the risks to individuals or family groups who reside near the facility.
Consider an interrelated
. group of' families containing 200 persons who.are all located at che point of highest offsite dose during the controlled purge.
Each would receive a e
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whole body dose of 0.05 mrem and a skin dose of 4 mrem.
The dose received by this population would be 0.01 person-rem to the whole body and 0.8 person-rem to the skin. -The maximum total lifetime risks of fatal cancer, non-fatal cancer, and genetic effects for the group as the result of the con-trolled purge would be 0.000003, 0.00001 and 0.000003 cases, respectively.
3.2.6 Resource Use The fact that most' components of the controlled purge system were already in place in the existing hydrogen control subsystem at TMI-2 limited the resource requirements for this alternative.
Some additional components were required for the system modifications. The principal additions were a 60-horsepower fan and the associated controller. An existing radioactive effluent monitor was modified slightly to extend its monitoring range.
The electrical power required for equipment operation during the controlled purge is approximately 40 kilowatts.
It is estimated that 12 man-months of TMI staff effort would be required to perform and monitor a controlled 60-day purge.
3.3 System for Decontamination Using the Selective Absorption Process to Remove obKr A schematic of the Selective Absorption Process (SAP) for the recovery of 85Kr from TMI-2 is shown in Figure 3-2.
The reactor building atmosphere 85 containing the Kr is withdrawn and filtered to remove particulates. The gas is then cooled, dried, and compressed to 682 kPa (100 psig) and cooled 0
again to -34 C (-30 F).
The gas is then further dried with a 3A molecular 85 sieve col'umn.
The cooled, dried gas containing the Kr is then fed into the bottom of the absorption section of the combination column.
The fluoro-85 carbon solvent flows downward through the column. The Kr dissolves in
' the solvent and the upward flowing gas leaves the top of the column 3-10 e
FIGURE 3.2 SCHEMATIC OF THE SELECTIVE ABSORPTION PROCESS i
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I 13X r3]
MOLECULAR R 12 CONOENSER SIEVE L _J V
A SOLVENT RECYCLE r3 PROOUCT COMBINATION COMPRESSOR J
f
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13X l
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MOLECULAR TRAP j
SIEVE REACTOR 4
MOLE ULAR Kr PRODUCT l
l PA STORAGE S: EVE t _3 FILTER W
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COMPRESSOR 4A MOLECULAR SIEVE SOLVENT SOLVENT STORAGE PUMP dhl 4nsteo QipJ
containing 5 to 10% solvent in the vapor phase.
This decontaminated gas is then passed through a condenser for solvent recovery and returned 85 to the reactor building.
The solvent containing the dissolved Kr and other gases flows down into the fractionating and stripped sctions of the combination column.
Solvent is boiled up from the reboiler where 85 there are essentially no dissolved gases present.
The Kr is withdrawn from the column in a gas stream at a position below the gas feed point where its concentration in the vapor phase reaches a maximum value.
The 85 recovered Kr and other gases pass through a 13X molecular sieve bed and a cold trap for further purification. The gas is then compressed and stored in steel cylinders.
The fluorocarbon solvent is pumped through a cooler and returned to the top of the column.
3.4 Technical Evaluation of the Selective Absorotion Process A comprehensive evaluation of the selective absorption process was performed 85 as it would be applied for Kr removal from the TMI-2 reactor containment building. This evaluation was based on a review of the various technical topical reports concerning the process (19-26); a description, cost esti-mate.and schedule for the use of the SAP for TMI-2 prepared by the Nuclear Division of Union Carbide Corporation (UCC-ND) (2]); and a visit and dis-cussion with UCC-ND personnel.
It ?,hould be emphasized that the evaluation applies primarily to the use of the SAP for treatment of the atmosphere in the TMI-2 containment building when the process is used in a recycle config-uration.
In this scheme, the treated gas effluent from the SAP is returned 3
3 to the containment building. A processing rate of 255 m /h (150 ft / min) as proposed by UCC-ND was assumed.
3-12
l 3.4.1 Feasibility I
There were no technical issues identified that would indicate that the sap could not be applied for the ~ removal of krypton from the TMI-2 con-tainment building. The process is based on well established technology that has been used in the petrochemical.and other industries 'for many years.
Personnel from UCC-ND have adapted this technology using a fluoro-carbon solvent absorbent specifically for noble gas recovery and have characterized the behavior of the interactions of the noble gases and a number of potential interferences with the fluorocarbon solvent.
A review of the measured gaseous components in the TMI-2 containment and the develop-ment work performed and reported by UCC-ND did not, identify any airborne contaminants that would interfere with the operation of the system shown in Figure 3-2.
Although UCC-ND has only had about 1.5 years of experience in operating a system in which the absorption, fractionation, and stripping functions are performed in a single column, UCC-ND personnel appear to have adequately demonstrated its applicability for noble gas recovery.
A number of minor technical issues exist regarding this application of the process, but none would preclude satisfactory operation.
With regard to equipment requirements', no components were identified that would require development or.testino to verify its applicability.
The only required custom-built component appears to be the absorption column for which general design specifications have already been prepared.
3.4.2 Effectiveness The two main criteria considered in evaluating the effectiveness of the SAP
-were the removal efficiency of the process and its capability for providing a relatively pure product that could be safely stored or transported for 3-13 e
.s permanent disposition.
When a recycle scheme is used, the time required 85 to decrease the containment building Kr concentration is fairly in-sensitive to the process krypton removal efficiency, especially if the removal efficiency is above about 90%.
No reasons were identified for operating the process as a single-pass operation whereby the treated effluent would be directly discharged to the atmosphere.
There are no apparent technical or theoretical reasons why the SAP could not be used 85 to reduce the Kr concentration in the containment building by a factor of 1000 or more.
Operation of th2 process for a period of about 25 days 3
3 85 at the capac'ity of 255 m /h (150 ft / min) would reduce the Kr concentra-tion by a factor of 10.
Several technical issues were !dentified regarding the capability of the process to provide a relatively pure product, but these are considered to have little effect on the proposed system application.
At this point, neither the composition of the stored gas nor the number of required storage cylinders is certain.
However, it appears the maximum quantity of product can be limited to several 50-liter (1.5-cf) storage cylinders by judicious selection of column product withdrawal rates and/or product re-cycle.
3.4.3 Practicality The SAP is a relatively complex system that requires trained engineers and technicians.
Because of its complexity, its satisfactory operation will probably require several weeks of checkout.
On the other hand, the process
..is based on sound technical principles that have been studied extensively and are well understood. Although there are many operations involved in the overall process, adequate design of control systems and sufficient pre-operational checkout should assure a high probability of satisfactory pro-cess.;erformance.
3-14
= 0nce the process is operating satisfactorily, few operational problems are expected. Maintenance should be minimal and on-line reliability very high.
_A~ reliability analysis of the process for nuclear fuel reprocess-ing applications was performed by a private consulting firm, and no major adverse equipment shortcomings were identified for extended operation (28).
3.4.4 SchedO e, Reported estimates for the time required to design, procure, construct, test, and install the 150-cfm selective absorption process at TMI-2 range from 6 to 24 months and are shown in Figure 3-3.
Each schedule is based on. different assumptions.
The shortest schedule of six months (29) is based on the assumptions that construction to standard ASME codes for unfired pressure vessels would be sufficient, that adequate funding would be provided [to ensuie there would be no manpower limitations], and interagency transfer or loan of property would be expedited [if necessary].
A "best effort" construction and installation schedule of 13 months involving no contingency and other qualification was prepared by UCC-ND personnel (27_).
This schedule is based on UCC-ND's experience in doing work in the Oak Ridge area utilizing the. UCC-ND staff, craftsman, and facilities.
Some of the main assumptions used in the proposed schedule are:
(1)'the project would be a high priority DOE project; (2) use of occepted conventional industrial standards, practices, and codes (including general adherence to Regulatory Guide 1.143); (3) negotiated procurements, including expediting with pre-miums; (4) adequate and timely site preparation at TMI-2; and (5) concurrent reviews and approvals.
It was also emphasized that UCC-ND personnel have little basis for estimating schedules that would actually be required on
[and for] the TMI-2 site.
3-15 e
THI-2 REACIOR BUILDIt3G DECOt3TAMINATION SCIIEDULE 1980 1901 1982 MJ JAS OND JFM AMJ JAS OND JFMAMJ J A'S 1.
Clean and Remove 24 -
Reactor Building Sump Water r
2.
Investigate Problems r 3: -
- +>:
of Reactor Building
"...:e Decontamination 3.
Decontamination.of tiji:
.......s*
Reactor Building
"^
Y a
ol SAP J"4
?am
{fi.4q q:::
'i 4.
Design, Construction and E.
52
't Testing of SAP minimum time estimate minimum time estimate by Science & Technology miriimum time by Bechtel Power Co.
Committee estimate by ORNL 90% removal 5.
Operatloa of SnP gd.
h p l 99.9% removal-E5"""*5fi
+:
j 99% removal Item 2 requires an estimate of 20-40 entries into reactor building and therefore requires the venting of the building prior to the large part of the effort.
Item 3 requires both the venting of the reactor building and a substantial processing of the reactor sump wa te r.
FIGURE 3-3
The 24-month schedule prepared by Bechtel Power Corporaticn for GPU (_3_0) 0 is based on the total project, including construction of the recovery system, a building to house the process, and the process installation and hookup.
This schedule provides for three levels of building construction code classifications (non-seismic, seismic, and aircraft hardened) with no distinction made for the different times required for esch.
The piping design code varies from ANSI S-31.1/ASME VIII (the least expensive) to ASME Section III, Division 1, Class 3 (the most expensive).
The schedule is based on industry standards for lead times and construction methods and was not optimized. The schedule assumes that regulatory requirements will not become a critical path issue.
It also assumes the availability of base line technology, including design information and criteria for speciality equipment, at the start of the schedule.
Clearly these schedules vary according to the assumptions made and the past experience and perspective of those making them.
It is within reason that a 150 cfm fluorocarbon absorption system can be designed, built and tested at ORNL in six months.
However, if the system were to be built at ORNL, we are more inclined to accept the 13 month estimate of UCC-ND be-cause they are the most familiar with the system and would be the group carrying out the work. When it comes to constructing the building to house the system and installing and testing the system at Three Mile Island, we believe GPU is in the best position to determine. schedule.
They and their contractors have the most experience with the practicalities of design and operations at TMI.
Furthermore, GPU is financially liable for all operations at the site. Therefore, in our judgment the most realistic schedule for having.the system installed and operating at TMI is between 13 and 24 months.
The time available before.85Kr removal from the reactor building atmosphere bec ues-a critical path item is approximately 4 months.
,,j 3-17
, ~,.,
3.4.5 Health 'and Safety Health and safety considerations related to use of the SAP system are presented in the four subsections that follow.
3.4.5.1 Radioactivity Releases to the Environment Radioactivity releases for the SAP alternative are given in Table 3-5.
A range of expected releases is presented for different assumed periods of SAP operation.
Approximately one month of operation is required to
- achieve a DF of 10, two months for a DF of 100, etc.
After SAP operation the remaining activity would be released by purging.
It was assumed that ten containment entries-would be required before the fluorocarbon system could begin operation.
Both " probable" and potential releases were considered.
Leakage frcm the containment as a result of failure of the fan coolers is considered a pro-bable occurrence.
Failure of these fan coolers is considered probable be-cause they have had no preventative maintenance since they were installed about a year prior to the accident and t. ave been operating in a high humidity (and therefore high load) environment since the accident occurred.
Based on the last leak rate test, the leak rate from the containment subsequent to 85 cooler failure has been estimated to be 0.13% per day (18). The total Kr release was calculated for two release durations.
It was assumed that (a) the fan coolers fail after six more months of operation and that the SAP is operational six months later and (b) the fan coolers fail immediately and the SAP is operational in two years.
It was also assumed that the containment leaked _only during the day.
At night it was assumed that no leakage occurred.
t 3-13
, tl
- - :?
Table'3-5 85 EXPECTED, PROBABLE AND POTENTIAL RELEASES OF KR FOR THE SELECTIVE ABSORPTION PROCESS ALTERNATE 85 Activity Causing Release Kr Release (Ci)
. Expected 10 Containment Entries 250 Total Expected Release (Ci) for Assumed DF 85 Venting of Residual Kr Af ter Operation of SAP DF = -10 5700 6000 DF = 100 570 820 DF = 100 57 310 DF = 1000 5.7 260 Probable Fan Cooler Failure 6-Month Release Before SAP 5800 2-Year Release Before SAP 15000
- Potential Interim Storage Tank Failure 3000
- Loss-of Stored Product 57000 x 19
=
j Potential releases are those that could occur due to an accident during operation of the fluorocarbon absorption system.
Failure of the interim 85 product storage tank and total loss of the Kr product were considered.
Both accidents are considered highly unlikely events.
3 Although some H would be released, the amounts would be small (as shown a
in Section 3.3.5) and the dose consequences are insignificant.
For that 3
reason the H releases are not shown in Table 3-5.
Also, it should be 85 noted that if the fan coolers fail, the leakage of Kr from the contain-ment would reduce the expected quantities to be purged after operation of the SAP system.
3.4.5.2 Radiation Doses to Individuals and Populations The e'xpected maximum doses to individuals residing near the plant are shown in Table 3-6.
The doses to individuals residing elsewhere in the world are variable but very small and are not included in the table.
The dose calculation assumptions and techniques employed were the same as those
_used in Section 3.3.5.
The maximum _ skin dose from expected releases is estimated to be 0.5 mrem for a 1-month period of operation of the SAP. The maximum skin dose for a 4-month operational period is 0;02 mrem. The maximum whole body dose for a 1-month period of operation is 0.006 mrem and changes in the same
- way as skin doses with the assumed DF.
The maximum individual doses result-ing _from fan cooler failure are estimated to range from 2-6 mrem to the skin and_0.03 to 0.08 mrem-.to the whole body.
Both the expected and probable doses are.less than 6% of the annual doses from natural sources.
Potential offsite doses.from accidental releases could be as large as 1600 mrem to.the skin and 20 mrem to the whole body.
These are well within the guidelines of Reference 16.
3-20 r
- [. '? *.-
~
Table 3-6 RADIATION DOSES TO INDIVIDUALS FOR THE SELECTIVE ABSORPTION PROCESS ALTERNATIVE Exposed Group Maximum Individual Dose (mrem) for Expected Assumed Decontamination Factor For SAP Operaticn Nearby Residents 10 100 1000 10,000 General Population Skin-0.S 0.06 0.02 0.02 Whole Body 0.006 0.0007 0.0003 0.0002
- Probable-Maximum Individual Dose (mrem)
Nearby Residents 6-month Release 2-year Release General Population Skin 2
6 Whole Body 0.03 0.08 Potential Nearby Residents Tank Failure Total Loss of Product
. General Population
-Skin 90 1600 Whole Body 1
20 e -
3-21 r
~~
The expected'and probable population doses are presented in Table 3-7.
.The expected total population doses range from 10-310 person-rem to the skin _ and 50-60 person-rem to the whole body as the assumed SAP DF varies from 10,000 'down to 10.
Probable population doses range from 250-660 person-rem to the skin and from 2-5 person-rem to the whole body depend-ing on the. assumed duration of leakage.. Again, it should be remembered that containment leakage would reduce the population doses expected from the operation.of the SAP _ system.
3.4.5.3-Fluoroca'rbon Releases to the Environment It-is' conceivable that the entire fluorocarbon inventory of f.out 1000 lbs could be released to the environment.
This is considered to be a low pro-bability event.
The amount of fluorocarbons produced each year is now several hundred million tons and a large fraction of this is eventually released to the environment.
Thus the potentiel fluorocarbon release repre-sents at most a small addition to the total.
3.4.5.4 Health Effects The maximum numbers of health effects resulting from the expected popula-
. tion radiation doses were computed using the incidence rates in Table 3-4.
'The potential health impact of fluorocarbon discharges is considered neg-ligible.
A maximum of 0.01 fatal cancers, 0.01 non-fatal cancers, and 0.02 genetic effects would be expected in the local population as the result of using 85
.the SAP system to. remove Kr. These maximum values are insensitive. to.
the~0F selected.
For the world population, the corresponding maxima are 0.0007, 0.003, and 0.0006 cases of fatal cancer, non-fatal cancer, and
'_ genetic effects,? respectively. These upper limit consequence estimates are also relatively independent'of the DF selected.
3-22 l
- 4 F
M'4
.g e
Table 3-7 POPULATION DOSES FOR THE SELECTIVE ABSORPTION PROCESS ALTERNATIVE Exposed Group Population Dose (person-rem) for Expected Assumed Decontamination Factor For SAP Operatic.
Nearby Residents 10 100 1000 10,000 General Population Skin 8
1 0.4 0.4 Whole Body 0.1 0.01 0.005 0.005 Plant Workers, Whole Body 50 50 50 50 World Population Skin 250 40 10 10 Whole Body 2
0.3 0.1 0.1 Total Skin 31 0 90 10 10 Whole Body 60 50 50 50 Probable Population Dose ' person-rem)
Nearby Residents 6-Month 2-year Release Release General -Popula tion Skin 8
20 4
Whole Body 0.1 0.3 World Population Skin 250 660 Whole. Body 2
5
~
3-23
u.
r 3.4.6 Resource Recuirements In addition to requirements for construction and for process equipment, other resource requirements include site preparation, utilities, and operating manpower.
Site preparation involves construction of a building to house the process and connection of utilities. The required building din.ensions are esti-mated to be 40 by 60 ft and 33 ft high.
These dimensions are based on the required height of the combination column, space for installing over-head lifting equipment, the necessary floor space for the other major pro-cess components and auxiliaries, a separate krypton storage space, and a protected space for operating personnel.
The main utility requirement will be electrical.
Approximately 1 Mw of electrical power will be required.
This estimate is based on the power requirements of the 200 kw reboiler heater, the refigeration for re-ccoling the solvent, the compression and cooling of the system feed stream, and auxiliary and ventilation motors.
The other utility requirements, such as cooling water and liquid nitrogen, are relatively small and are not quantified.
The estimated manpower requirements-for operating the process are one operating engineer and an assistant.
In addition, a qualified engineer thoroughly familiar with the design and operation of the SAF should. be available for assistance during process operation.
It is assumed that health physics services would be provided~by regular TMI personnel.
3-24
- . =. *,
l Section 4 SYSTEM COMPARISONS This'section provides a comparison of the two alternative methods of 65Kr removal from the containment atmosphere controlled purge and selec-tive absorption.
The methods are compared for each criterion listed in Section 2. 'In addition, comparisons are made of system cost and psycho-logical stress on nearby residents.
The comparisons are summarized in Table 4-1 and discussed in the following subsections.
4.1 Feasibility Both alternatives are technically feasible.
4.2 Effectiveness 85 Both 31ternatives are effective ways of reducing Kr concentrations in the' containment atmosphere.
4.3 Practicality Controlled purging is simpler than the use of the SAP system.
-be operable without difficulties.
4.4' Schedule
' The controlled purge' alternative can be ready for operation in 1 to 4 days.
The SAP can probably be ready for operation at TMI in 13 to 24 months.
The best estimate-of the duration for controlled purging is 60 days.
For 85 the SAP to reduce the quantity of Kr from 57,000 Ci'to 570 Ci would take approximately the same time. Using the assumption that 10 entries are made 4-1.
t
- . a;,-
Table 4-1 COMPARIS0N OF ALTERNATIVES SAP with Controlled Criterion Controlled Purge Purge of Residual 1.
Feasible yes yes 2.
Effective yes yes 3.
Practical yes yes 4.
Schedule Time to Begin Process 1-4 days 13-24 months Time Required to Process 60 days 1-3 months 5.
Maximum Expected Health Effects Local Population Fatal Cancers 0.0005 0.01 Non-fatal Cancers 0.001 0.01 Genetic Effects 0.0006 0.02 World Population Fatal Cancers 0.007 0.0007 Non-Fatal Cancers 0.03 0.003 Genetic Effects 0.006 0.0006 6.
-Resource Use Manpower 1 man-year 19 man-years Electricity 40 kilowatts 1000 kilowatts 7.
Psychological Stress
-Level of Stress lower.
higher Duration of Stress Less than 6 months 14-30 months 8.
Costs
$75,000 59-529 million 4-2 7
e-e
85 before the SAP is operational, 250 curies of Kr would be released.
There-fore, to' reduce the quantity of Kr in containment by more than a factor of 100 would not reduce the total dose to the populace much further.
4.5 Health and Safety The computed maximum numbers of health effects expected in the local popula-tion and in the world population are shown in Table 4-1.
They ignore any accidents to construction or operating personnel.
The nu6ers of expected cases vary for the two alternatives but in all cases they are substantially lower than one.
Therefore, no health effects would be anticipated from implementation of either alternative.
4.6 Resource Use Manpower estimates for the controlled purge system are based on 1 shift engineer, 2 plant operators and 1 technician full time during the period of purging.
In addition, two persons will monitor radiation and radio-activity levels off-site.
The 19 man-year effort for the fluorocarbon absorption system is based on an UCC-ND estimate for installation at Three Mile Island and includes one man-year for operation of the system.
It does not appear to include con-struction of the building to house the system.
-4.7 Psychological Stress Studies have shown that psychological stress was experienced during the accident by people living in the vicinity of the plant (31,32,33).
It has been estimated that between 10% and 20% of those living within 15 miles of the site still showed signs of distress in January 1980 (3_3_).
" Continued contradictory news coverage of TMI has provoked a desire [among these living near the plant] during the first six months for 'it to be over with'....
.. )
e
These people are already exasperated by the interminability of the discussion and are coming to resent the fact that TMI was every built" (3_2_).
'Or. Peter Houts, the principal investigator of the study reported in Reference 33, has indicated that had the January 1980 resurvey been carried out in April 1980 the fraction of the population showing signs of distress would have been greater (Personal Communication).
Dr. Houts was alluding 85 to news reports of releases of Kr:
on February 11 due to an instrument 85 line failure and in April when a release of Kr was reported as a result of purging an air-lock.
There was also a news report of a coolant leak into the Auxiliary Building from a valve failure on March 20.
It appears that the psychological stress from these releases is more attri-butable to the fact that they were considered newsworthy than to the quantity of 85"r released.
During the leak of February 11, approximately 0.3 curies 0brwasreleased(j_).
Purging the containment personnel air lock in of 85 April resulted in a release of 0.045 curies of Kr. These releases are 85 trivial compared to the approximately 80 curies of Kr reported as being released per month in normal ventilation exhaust air (34). Attention was drawn to the lesser release situations because they were highlighted by the NRC in Unusual Occurrence Reports.
Given that there would be no health effects from either alternative and that psychological stress is independent of the quantity' released, it would appear-that the least psychological stress is associated with the procedure that can be carried out with the least number of newsworthy incidents, the one which satisfies the desire for "it to be over with".
This criterion favors the controlled purging of the reactor building atmosphere.
4-4
c-
- 'o;y
~
- 4.8LCost Comparisons The cost of_ the controlled purge including engineering, licensing, materials and_ operations is estimated to be $75,000.
The costs for the SAP system were based on information supplied by UCC-ND and from an architect and engineering firm.
Both supplied minimum and maximum co3ts. The estimated costs ranged from $9-29 million; our best' estimate of the actual cost is
$18 million.
~
'e 6
1 f
4-5
~
., +,#
SECTION'S CONCLUSIONS AND RECOMMENDATIONS 85 The two alternatives considered here for removing Xr from the TMI-2 containment building are controlled purging and fluorocarbon absorption 85 (SAP)ofmostofthe Kr followed by purging.the residual.
We offer the following conclusions and recommendations:
o From the points of view of feasibility, effectiveness practicality and the health and safety there is little to chose-between the two alternatives.
o 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.
o From the points of view of schedule and cost, controlled purging -is the best alternative because it is cheaper and can be started within days.
o Therefore it is our opinion that the SAP should not be adopted as a substitute for controlled purging.
f 5-1
d REFERENCES 1.
Metropolitan Edison Company, "Three Mile Island Unit 2 Reactor Building Entry", Docket 50-320, March 21,1980. Available in the NRC PDR" for inspection and copying for a fee.
2.
Metropolitan Edison Company, "Three Mile Island Unit 2 Reactor Building Purge Program' Safety Analysis and Environmental Report", Docket 50-320, November 13,- 1979.
Available in NRC PDR for inspection and copying for a fee.
3.
Letter from Richard H. Vollmer, NRC, to Robert C. Arnold, Metropolitan Edison Co.,
Subject:
Reactor containment building atmosphere cleanup, Docket 50-320, December 18, 1979.
Available in NRC PDR for inspectior}
and copying for a fee.
4.
Letter from John T. Collins, NRC, to R. G. Wilson, Metropolitan Edison Co.,
Subject:
Additional information request for preparation of environ-mental assessment, Docket 50-320, Dec.18,1979. Available'in NRC PDR for inspection and copying for a fee.
5.
Letter from R. F. Wilson, tietropolitan Edison Co. to John F. Collins, NRC,
Subject:
Response to 33 questions on reactor containment building atmosphere cleanup, Docket.50-320, January 4, 1980.
Available in NRC POR for inspection and copying for a fee.
6.
U. S. Nuclear Regulatory Commission, Environmental Assessment for Decon-tamination of the Three Mile Island Unit 2 Reactor Building Atmosphere, NRC Report NUREG-0562. Available for inspection and copying for a fee at the NRC PDR.
7.
Letters from Gerald Pollack, Michigan State University, to Victor Gilinsky, Nuclear Regulatory Commission ~. Available in NRC PDR for inspection and copying for a fee.
8.
Letters from Allan E. Ertel, House of Representatives, to John Ahearne, Nuclear Regulatory Commission. Available in NRC PDR for inspection and copying for a fee.
9.
U. S. Nuclea~r Regulatory Commission.
Rules and Regulations, Title 10 Code of Federal Regulations Part 20, " Standards for Protection Against Radiation", June 1977. Available from public libraries.
10.
U. S. Nuclear Regulatory Commission.
Rules and Regulations, Title 10 Code of Federal Regulations Part 50, " Licensing.of Production and Utiliza-tions Facilities", March 1975, Appendix I, " Numerical guides for desi:n objectives and limiting conditions for operation to meet the criterion' as low as practicable' for radioactive material in light-water-cooled nuclear power reactor effluents". Available in public libraries.
11.
U. S. Environmental Protection Agency.
Rules and Regulations, Title 40 Code of Federal Reoulations Part 190 " Environmental Standards for the Uranium Fuel Cycle", January 1977. Available in public libraries.
12.
National Council on Radiation Protection and Measurements, Krypton-85 in the Atmosohere-Accumulation. Biolocical Sienificance and Control iechnoloav.
.NCRP Report No. 44 (July 1975).
Availaole in technical libraries and from the-NCRP.
,1 "The Nuclear Regulatory Commission P'.biic Document Room (PCR) is located a' 1717;H. Street, N. W., Washington, CC 20555 R-1
... s 13.
National Oceanic and Atmospheric Administration, Measured Weekly and Twice-Daily Krypton-85 Surface Air Concentrations Within 150 km of the Savannah River Plant (March 1975 throuch Sectemoer 1977) - Final Report, NOAA Technical Memorandum ERL ARL-80 (January 1980).
14.
Energy Research and Development Administration, Final Environmental Inact Statement on Waste Management Ooerations at the Idaho National Encineering Laboratory, ERDA-1536 (1975).
15.
U. S. Nuclear Regulatory Commission.
Regulatory Guide 1.109, " Calculation of Annual Doses to Man from Routine Releases of Reactor Effluents for the Purpose of Evaluating Compliance with 10 CFR Part 50, Appendix I",
Copies are available for inspection and copying for a fee from the NRC POR and from the U. S. Government Printing Office, Washington, D. C.
20402. ATTN:
Regulatory Guide Account.
16.
U. S. Nuclear Regulatory Commission.
Rules and Regulations, Title 10, Code of Federal Regulations Part 100, " Reactor Site Criteria", Sept.1, 1978. Available at public libraries.
17.
National Council on Radiation Protection and Measurements, Influence of Dose and Its Distribution in Time on Dose-Response Relationships for low LET Radiation, NCRP Report 64 (May 1980).
18.
MPR Associates, Inc.
"Three Mile Island Unit 2 Containment Atmosphere Cleanup Alternate Systems Evaluation", Docket 50-320, October 9,1979.
Available in NRC PDR for inspection and copying for a fee.
19.
M. J. Stephenson et al., Selective Absorption Pilot Plant for Decontami-nation of Fuel Reprocessing Plant Off-Gas, UCC-ND Report K-1876 (October 1977). Available in Technical libraries.
20.
R. S. Eby, The Desublimation of Kryoton from a Noncondensable Carrier Gas, UCC-ND Report K-1896 (September 1978). Available in Tecnnical libaries.
21.
M. J. Stephenson, " Analysis of a Non-Isothermal Gas Stripper with Volatile Solvent", Presented at the 72nd AICHE Annual Meeting, San Francisco, CA, November 25-29, 1979.
22.
J. H. Shaffer et al, The Solubilities of Kryoton and Xenon at Infinite Dilution in DiBi1Fodifluoromethane, UCC-ND Report ORNL/TM-6652, (January 1980).
Available in Technical libraries.
23.
L. M. -Toth et al, Chemical and Physical Behavior of Some Contaminants in the Fluorocarbon Process, UCC-ND Report ORNL/IM-6484 (November 1978).
Available in Technical libaries.
24.
B. E. Kanak, Analysis of a Gas Absorption System with Soluble Carrier Gas and Volatile Solvent, UCC-ND Report K-2007 (January 1980). Available in Technical libraries.
25.
M.' J. Stephenson, Analysis of a Fractional Gas Stricoer, UCC-ND Report K-1895 '(December 1978).
Available in Technical Libraries.
26.
J. R. Merriman et al, " Removal of Noble Gas by Selective Absorption",
Presented at thiIEternational Symposium on Management of Gaseous Wastes from Nuclear Facilities, IAEA-SM-245/53 (February 1980).
To be published in the conference proceedings.
I r
+
R-2 L
^
27.
J. R. Merriman et al, Use of the ORGDP Selective Absorption Process for. Removal of Krypton from the Containment Building Atmosphere at Teree Mile Island Unit 2, UCC-ND Report K/ET-500 (May 6,1980).
Available in tne NRC POR for inspection and copying for a fee.
28.
D. E. Wood, Availability Analysis of the Freon Absorption System for Treating Effluents from Reprocessing, UCC-ND Report ORNL/IM-5797 (March 1977).
Available in technical libraries.
- 29. Letter from Ron Williams, Committee on Science and Technology, U. S.
House of Representatives, 9 May 1980. Available in NRC POR for inspec-tion and copying for a fee.
- 30. Letter from J. W. Thiesing, Bechtel Power Corporation to R. F. Wilson,
.GPU, 28 April 1980.
Available in NRC PDR for inspection and copying for a fee.
31.
J. G. Kemeny, et al., Report of the President's Commission on the Accident at Three Rile Island (October 1979).
Available in the NRC POR for inspection and copying for a fee.
32.
C. B. Flynn and J. S. Chalmers, The Social and Economic Effects of the Accident at Three Mile Island, NRC Report NUREG/CR-1215 (January 1980).
Available in technical libraries.
33.
Peter S. Houts, et al. Health-Related Behavioral Impact of the Three Mile Island Nuclear incident, Part I,-(April 1980). Availacle from the Pennsylvania Department of Health.
- 34. Letter from Sydney Porter to John Collins, " Effluent Releases from TMI Units 1 and 2 for the month of January 1980" (21 March 1980). Available in the NRC POR for inspection and copying for a fee.
S 4
S R-3
.