ML19344D823
| ML19344D823 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 08/11/1980 |
| From: | Harold Denton Office of Nuclear Reactor Regulation |
| To: | Ponzi J AFFILIATION NOT ASSIGNED |
| References | |
| NUDOCS 8008260020 | |
| Download: ML19344D823 (4) | |
Text
44 August 11, 1980 l
Mr. Joe Ponzi 293 Illinois Avenue Westerville, Ohio 43081
Dear Mr. Ponzi:
Given below are answers to the questions in your letter of July 18, 1980, to the Nuclear Regulatory Commission.
1.
What type of nuclear power plant is Three Mile Island?
Both nuclear power units at Three Mile Island use pressurized-water reactors and natural-draft cooling towers. The design electrical rating of Unit 1 is B19,000 net kilowatts and of Unit 2 is 906,000 net kil owatts.
2.
What caused the accident there?
The accident was caused by a series of mechanical and human malfunctions. The investigation into the accident by the NRC Office of Inspection and Enforcement found inadequacies in six major areas:
equipment perfonnance, transient and accident analyses, operator training and perfomance, equip-ment and system design, infonnation flow, and implementation of emergency planning. Had particular actions been taken by the plant operators or had certain equipment been designed differently, the consequences of the accident could have been pre-vented or significantly reduced.
1 3.
How much water was spilled in the contairrnent building?
About 600,000 gallons. -
4.
How many nuclear power plants are in Ohio? And how many are being planned to be built?
The only nuclear power plant in Ohio with an operating I
license is Davis-Besse Unit 1.
Under construction are Zimmer Unit 1 (scheduled to begin operation in 1981) and Perry Units 1 and 2 (scheduled to begin operation in 1984 and 1988, respectively).
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P.r. Joe Ponzi
-2 August 11,1980 lims much radiation can a persen be exposed to without 5.
contracting cancer er any other related disease in the years to co:.u?
A report just issued by the tiational Acadeny of Sciences on "Tne Effects en Population of Exposure to Low Levels of Ionizing Radiation," by tt;e Cort:ittec on the Biological Effects of Ionizing Radiations, stated:
"The Coiuittee recognizes thct there is great uncertainty in regard to the shape of the dose-respanse curve for cancer induction by radiation, especially at low dose....For the lifetime risk of cancer mortality induced by low-LET radiation (x rays and gaana rays) fro, a single whole body absorbed dose of 10 rads (a rad corresponds to the absorbtion of 100 ergs of energy per gram of tissue), based on the linear-quadratic model, the estimates of increase in risk range fraa 0.5 to 1.C of the naturally occurring cancer mortality, depending on tne projection model.*
For continuous lifetime exposure to I rad /yr, the estimates range frou 3 to C~....The co=nittee does not know whether dose rates of about 100 mrads/yr (a nrad is one-thousandth of a rad) are detrimental to man...."
"*In interpreting the percentage increases in cancer risk above the naturally occurring rate, the following is an example:
If the naturally occurring lifetiae cancer risk is 160,000 cases per million persons, the rate i s 16*..
An increase due to radiation equal to 0.5" of the natural rate will result in an increase of 160,000 X 0.005, or 800 cases
--that is, 160,000 total cases will occur.
This represents a rate of 16.08; after radiation."
OFFICE SURNAME DATE
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Mr. Joe Ponzi August 11, 1930 t
I In connection with the Committee's statement that i
i it does not kno.i whether dose rates of about 100 meads /yr are detrir., ental to man, it may be noted that the highest net reading of dosimeters at off-site loca. ions around Three Mile Island in tne period after the accident corresponded to about l
27 mraJs.
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6.
How much gas was recently vented frau Three Mlle Island and what kind?
About 45,000 curies of krypton -85 has been vented froi.i the contaiment building of Three Mile Island Unit 2.
(A curie of material has the same rate of radioactive decay as approximately one gram of radiuu.)
f 7.
Have there been similar accidents in the U.S.A. or l
in the world?
t I
In 1974 an incident occurred at the NOK-1 nuclear pouer plant in Beznau, Switzerland, that bears some similarity to the Three Mile Island accident.
In 1977 an incident occurred at the Davis Besse nuclear power plant in Ohio that bears a strong resemblance to the THI accident.
In February 1900, an incident occurred at the Crystal River nuclear pouar plant in Florida that has some similarities to the TMI accident.
In none of these cases was there dauage to the reactor ccre, such as occurred in the TMI i
accident.
8.
What kind of fuel is most used in nuclear reactors and what kind is most deadly?
I The fuel most conmonly used in nuclear reactors is l
uranium enriched in the isotope uranium -235.
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Natural uranium is used as fuel in some reactors.
In underground mining of uraniu.a. ventilation must be provided to rer.ove radon gas that is emitted.
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P.r. Joe Ponzi August 11,1980 Another fuel is plutonium, which is produced by irradiating uranium in a reactor, is handled in glove boxes or by remote control to protect against the alpha particles cuitted, and is very toxic when ingested.
Still another fuel is urantun -233, which is produced by irradiating thorium in a reactor and is acco nsnied by the isotope uraniua
-232 with a radioactivc daughter that enits penetrating ganaa rays that must be shielded against.
I trust that these answers provide the infomatio1 you are sccking.
Sincerely, esi-d Tr.cd 91 E. G Cue 4J!arold R. Denton, Director 4ffice of Nuclear Reactor Regulation DISTRIBUTION Docket 50-320 NRC PDR LPDR TERA NSIC HRDenton EGCase PFine PPAS TSB R/F BSnyder A
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