ML19210E997
| ML19210E997 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 10/19/1979 |
| From: | Harold Denton Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML19210E923 | List: |
| References | |
| NUDOCS 7912130371 | |
| Download: ML19210E997 (5) | |
Text
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V DISTRIBUTION Docket File OELD NRR Reading M. Groff EDO-RAB Reading G. Ertter (68SS)
CCT 1 9:9.8 W. Pasciak C. Paul F. Congel A. Ferguson T. Murphy SECY (3) 79-2108
-For:
The Cer=issicners W. Kreger OCA (3)
D. Nuller TMI PS Reading Thru:
Ex ec ut i ve D i rect o r(3(,cg,[gga;,igwi,,J(. Den to n TMI A/D Reading
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I!arold R. Denton, Director Office cf ?!uclear Feactor Regulation
Subject:
INFCF.ATION PE0CEST CCf:CERNI!G RADICLOGICAL PELEA5ES AT TFI j
Purnose:
Approval of a letter to Congrestran :' orris Ucall and Congressman Jeres Ueaver Siscussien:
Cn July 13, 1979, Ccccressran Forris Wall ano Cengresscan Jares
- caver-requestad infctmtien (see Erclcsure 2) concernirt the cacnitude cf radiological releases as a result c' tFe incidert at Three Mile Island t'uclear Station, and estirates cf the degree of uncertainty in the calculations of bu' an exposure.
The proposed respense to these Corcresscen (Enclosure 1) addresses their cencerns.
It relies or data collected by "etropolitan Ediscn (the licersce). en a report prepared i'y the /d Hoc Interagency Pese Assessrent Croup for Deleases to the Attcsp.Fere, and en a draft decurent for the releases to the aquatic envircrrent that is being prepared by the p.adiclogical Assessrent Branch staff.
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Enclosures:
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Proposed respcnse y
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Ltr fr. Congressran Udall and fEra C ",, '7
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Congressnan ' Weaver, dtd 7/13/79
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IDENTICAL LTR 4 /; ;; - (-s) SENT TO REPRESENTATIVE JAMES WEAVER TFe Honorable t'arris K. Udall, Chaiman Subccrnittee on Energy !. the Envirorcent 1
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This letter is in response to your letter dated July 13, 1979, recuesting information regarding the releases of radioactive raterials to tFe environrent for the period of ?' arch 2C,1979 through April 7, in79, at Three File Island Puclear Station. You requested our position recarding the following points:
l.
The.,annitude of the release that occurred each day during the reriod March 20 through April 7 of icdine, xenen, ard ctrer isotopcs tPat r.icht have contributed significantly to huran exposure.
2.
The degree of uncertainty and sources therecf in estirates of the radiological release and resulting buran exrosure.
3.
The staff's calculations leading to esticates of tLe release cf iodine, xenen, and other isotopes, and diculatiers of Furan exacsure to ionizing radiation.
With regard to the magnitude of releases that occurred, encicsure I lists data collected by "etropolitan Edison's consultants, Porter rert:
cased Censultants Inc., for releases that were made to tre atrosphere.
on radioactivity species r,easurerents r..ade both in the plure and at off-site locations, only icdine and ncble cases are listed in tre erc!csure because they were the only radioactive raterials that were released cf any censecuence.
The radiciodine releases were detemined frm an analysis of iodire cellectine charcoal cartridges in the effluent sanpling syster for the Unit 2 staticn exhaust vent. For I-131, the licensee has esticated arrrnxirately la curies released through "ay,1979. Since this estinate was rade frer reasurerer.ts of sarples frer, the scurce of release, we independently esticate that it is accurate within a factor of about two.
The station roble gas ronitorinr: syster was rade increrative hy hich ra fic-activity levels very early in the accident. Therefore, cchie gas releases were estimated frc offsite TLD reasurerents, the retecrclogical discersico characteristics during the accident, and tFe plu e radionec!ide cerrositien as detc~-ired '"r Felicerter reaeure-ents. TFis caire1 3 t i e r M
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The Honorable Porris Udall 2
procedures for estimating a source term in this manner are described in a rep 9tt by the licensees' consultants, Pickard, Lowe, and Garrick.t'l In this report the activity of noble gases released is estimated to be about 10 million curies during the first month after the accident, most of which was released during the first few days.
It should also be mentioned that an alternative method for measuring the source tenn which is based on a correlation of recordings from an area radiation monitor inside the building near the release duct with the effluent monitor, has been developed by Dr. Carol Burger of Ogg) Ridge National Laboratory for the President's Commission on TFI.t Her results were that the total noble gas activity released was about 2.4 million curies. The staff,will review that report when it is released by the President's Commission on TMI.
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The NRCiurrently
~ ia Task Force reviewing ~whether the~ TMI accident was an Extra-ordinary Nuclear Occurrence (10 CFR 140.83). In this connection, we are again reviewing the releases frm TMI and will make publicly available the results of this review when available near the end of October.
Based on cur analysis of the uncertainties existing in the factors above, the estimate that 10 million curies of Xe-133 were released could range frm about 1 million curies to 40 million curies.
However, it is important to note that this uncertainty in the noble gas source does not affect our confidence in the population doses or the associated health effects in any way. The reason for this lies with the fact that the doses were measured directly in the environ-ment and do not depend on knowledge of source magnitude. Enclosure 2 describes and provides an analysis of the magnitude of the releases that were made to the river. These values were detennined from actual measurements of samples of effluents prior to release. At no time were the licensee's release limits as set by the technical specifications violated for the gLuid discharges wt en the release rates are averaged over one day.
Operating within the technical specifications limits would assure that the resulting radiological impact is minimal or non-existent.
(1) Woodard, Keith, " Assessment of Offsite Radiation Doses from the Three Mile Island Unit 2 Accident", July 31, 1979, Report TDR-TMI-116, Pickard, Lowe and Garrick, Consultants.
(2) Burger, Carol, "Repcrt by the Task Group on Health Physics and Dosimetry" Sept. 28, 1979, President's Commission on TMI.
(3) Executive Surinary of Liquid and Gaseous Peleases frm TMI Porter-Gertz Consultants, Inc., August 24, 1979.
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NRC FORM 318 (9-76) NRCM 0240 WU.S. GOVERNMENT PRINTING OFFICE: 1979 289 369
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The Honorable Norris Udall 3
Our response to your question regarding the uncertainties in the health impacts requires rather detailed discussion. Presently, the FRC staff and the Metropolitan Edison consultants have relied on off-site dose data (from T1.D's) to estimate both the magnitude of the noble gas releases and the magnitude of human exposure.
Estimations of human exposure for various distances and directions from TMI were interpolated from the T1.D data using several calcula-tional proceduresd)These procedures are described in the Ad Hoc Committee Report and enclosure 3.
It is the NRC staff's position that the individual doses estimated in this way are reasonable and most likely overestimate the doses received by real individuals. Nevertheless, the doses calculated in this manner were used to estimate the cumulative population se and health effects. Based on the Ad Hoc Committee Report, the estimated population dose is 3300 man-ren with a range frm 1600 to 5300 nan-rem. Using the 3300 man-rem value, less than one additional fatal cancer (0.7) is expected over the lifetime of the exposed population (about 2,000,000 people). Depending upon the opinion of various experts in the field of risk estimation, the health impact can range frcrn a minimum of zero (0) to as much as about 10 additional fatal cancers. We are not aware of any new information that would significantly affect these conclusions.
The staff calculation of do and health effects are contained in the Ad Hoc Committee Report for air releases and in enclosure 2 for river releases. Enclosure 3 describes the staff's procedure for estimating noble gas releases. In addition, enclosure 3 contains a more detailed description of a procedure to estimate population doses. The licensee's radioiodine releases infonnation listed in enclosure 1 is primarily based on direct measurements of activity in charcoal cartridges. Samples of liquid were analyzed prior to discharge; thus, the liquid releases are based on direct measurerents rather than on calculations. Hence, no calculational methods were needed for the radiciodine or liquid release values.
Sincerely, 1546 265 Joseph M. Hendrie Chairman
Enclosures:
see attached page D
(4) Population Dose and Health Impact of the Accident at Three Mile Island Nucipw 9t atinn IL t _ h.lmme Du g1 stc7 (~,
4 de OFFICE h. Washington, ). C. 20555, Pay 1979.
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NRCWORM 318 (9-76) NRCM 0240 D U.S. GOVERNMENT PRINTING OFFICE: 1979-289-369
The Honorable Morris Udall 4
Enclosures:
1.
Surmary of Gaseous Releases to the Envirorrent at THI During the Period of 3/28-3/31/79 2.
Releases of Radionuclides into the Susquehanna River from TNI During the Period of 3/28-5/11/79 -
Data and Analysis 3.
A Method for Calculating Doses to the Population from Xe-133 Releases During the Three P.11e Island Accident
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DU.S. GOVERNMENT PRINTING OFFICE: 1979 289 369 NRC FORM 318 (9 76) NRCM 0240