ML20141A882
| ML20141A882 | |
| Person / Time | |
|---|---|
| Site: | Haddam Neck File:Connecticut Yankee Atomic Power Co icon.png |
| Issue date: | 03/27/1986 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20141A857 | List: |
| References | |
| NUDOCS 8604040566 | |
| Download: ML20141A882 (11) | |
Text
' ~ ~
r- i p *trq'o UNITED STATES g ,
8 o . NUCLEAR REGULATORY COMMISSION l l
r, a wAsHWGTON, D C. 20665
~s
/
I UNITED STATES NUCLEAR REGULATORY COMMISSION CONNECTICUT YANKEE ATOMIC POWER COMPANY
_ DOCKET NO. 50-213 ENVIRONMENTAL ASSESSMENT i
The U. S. Nuclear Regulatory Consnission (the Commission) is considering 1 issuance of a license amendment modifying the technical specifications to )
Connecticut Yankee Atomic Power Company (hereafter CYAPCo or the licensee), l for the Haddam Neck Plant located in.Middlescx County, Conne:ticut. l 1
ENVIRONMENTAL ASSESSMENT J l
Identification of Proposed Action: The requa ted license amendment morjifies i the current technical specifications to (1) pennit the repair of degraded steam generator tubes by installing metal sleeves in the degraded tubes rather than removing them from service by plugging them; (2) change the definition of tube degradation; (3) add additiono? reporting requirements dealing with the Cube sleeving and (4) renumber existing technical specification.pages.
The license amendment is responsive to the licensee's application dated l Decec;5er 6,1985 as modified January 7,1986.
I I
The Need for the Proposed Action: The proposed license amendment is needed to reduce the number of steam generator tubes which may be required to be taken !
out of service if the pitting corrosion previous (y identified had progressed substantially.
8604040566 860327 PDR ADOCK 05000213 P PDR l l
l
1 1
Environmental Impacts of the Proposed Action:
Occupational Exposure The Connecticut Yankee Atomic Pcwer Company has estimated that the occupational exposure from the proposed steam generator repair at Haddam Neck Nuclear i Generating Plant, will be about 600 person-rems. Based on the Staff's *eview of the licensee's report, the Staff concludes that the licensee's estimate of !
600 person-rems to the work force is a reasonable estimate of the expected l dose.
1 To detemine the relative environmental significance of the estimated l occupational dose for the repair, the Staff has compared this dose for the repair with the reported doses experienced at modern pressurized water reactors (PWRs). In addition, the Staff has also compared the estimated risk to nuclear power plant workers tc published risks for other occupations.
Most of the doses to nuclear plant workers result from external exposure to radiation emitted by radioactive materials outside of the body, rather than from internal exposure due to inhaled or ingested radioactive materials.
Experience has shown that the total annual dose to nuclear plant workers varies substantially from reactor to reactor and from year' to year. Recently licensed 1000-MWe PWRs are designed in accordance with the post-1975 regulatory requirements and guidelines that place increased emphasis on maintaining occupational exposure at nuclear power plants as low as reasonably achievable (4LARA). These requirements and guidelines are outlined respectively in 10 CFR Part 20, Standard Review Plan Chapter 12 (NUREG-0800), and Regulatory l Guide 8.8, "Information Relevant to Ensuring that Occupational Radiatica Exposures at Nuclear Power Stations Will Be as Low as Is Reasonably Achievable."
The licensee's proposed implementation of these requirements and guidelines 1 'fcr the repair work has been reviewed by the NRC staff, and the results of {
that review are reported in the staff's Safety Evaluation Reports. l l
1 l;
)
{'
l l- Table I shows the occupational dose history for Haddam Neck. With the ,
addition of 600 person-rems for steam generator repair programs, the average annual dose for the plant will increase by about 10% .from the average of about :
1046 person-rems to about 1146 person-rems (six year average).
I i
- Average collective occupational dose information for 373 PWR reactor-years !
, of operation is available for those plants operating between 1974 and 1983. '
l (The year 1974 was chosen as a starting date because the dose data for years before 1974 are primarily from reactors with average rated capacities below 500MWe.) These data indicate that the average reactor annual collective dose at PWRs has been about 510 person-rem, although some plants have experienced
) annual collective doses averaging as high as about 1350 person-rem per year ;
over their operating lifetime (NUREG-0713, Vol. 5). These dose averages are ,
- based on widely varying yearly doses at PWRs. For example, for the period mentioned above, annual collective doses for PWRs have anged from 18 to 3223 '
person-rem per reactor. However, the average annual dose per nuclear-plant l worker of about 0.8 rem (NUREG-0713, Vol. 5) has not varied significantly !
- during this period. The worker dose limit, established by 10 CFR 20, is 3 rem per quarter, if the average dose ove the worker lifetime is being controlled to 5 rem per year, or 1.25 rem per quarter if it is not.
The wide range of annual collective doses experienced at.PWRs in the United '
States results from a number of factors such as the amount of required mainte-nance and the amount of reactor operations and in-plant surveillance. Because these factors can vary widely and unpredictably, it is impossible to determine in advance a specific year-to-year annual occupational radiation dose for a :
particular plant over its operating lifetime. There may, on occasion, be a need j for relatively high collective occupational doses, even at plants with radiation !
i protection programs designed to ensure that occupational radiation doses will l
{ be kept ALARA.
! In recognition of the factors mentioned above, staff occupational dose I
estimates for environmental impact purposes for the Haddam Neck plant are based j on the assumption that the unit will experience the annual average occupational i
1 4
-,. . - _ . . _ . . ~ .,_..m._.__ __
_ , _ . . . . , _ , . , . _ , . . . . ._.___.____._,.,_,.,,._____,,_,.~._,_.n_,,_,_,. _
....#,. ~~
doses for the unit at the Haddcm heck Plant will be 510 person-rem, but -
annual collective doses could average as much as 3 times this value over the life of the plant.
The average annual dose of about 0.8 rem per nuclear-plant worker at operating g PWRs has been well within the liinits of 10 CFR Part 20. However, for iepact ,
evaluation, the NRC staff has estimated the risk to nuclear-power-plant workers and compared it in Table 2 to published risks for other occupations. :
Based on these comparisons, the staff concit. des that the risk to nuclear- -
plant workers from plant operation is comparable to the ris,ks associated -
with other occupations >
l In estimating the health effects resulting from occupation radiation exposures as a result of this repair, the staff used scmatic (cancer) and genetic l
risk estimators that are based on widely acceptable scientific information.
Specifically, the staff's estimates are based on information compiled by the National Academy of Sciences (NAS) Advisory Committee on the Biological Effects of Ionizing Radiation (BEIR 1,1972; BEIR III,1980). The estimates of the risks to workers and the general public are based on conservative assumptions (that is, the estimates are probably higher than the , actual -
number). The following risk estimators were used to estimate health effects:
135 potential deaths frcm cancer per million person-rem and 22 potential cases cf all forms of genetic disorders per million person-rem.. ,
The cancer-mortality risk estimates are based on the " absolute risk" model describedinBEIRI(NAS). Higher estimates can be developed by use of the
" relative risk" model along with the assun:ption that risk prevails for the l duration of life. Use of the " relative risk" model would produce risk l
values up to about four times greater than those used in this report. The '
staff regards the use of the " relative risk" model values as a reasonable upper limit of the range of uncertainty. The lower limit of the range would be zero because there may be biological mechanisms that can repair
{
damage caused by radiation at low doses and/or dose rates. The number of I
potential cancers would be approximately 1.5 to 2 times the number of I
potential fatal cancers, according to the 1980 report of the National Academy of Sciences Comittee on the Biological Effects of Ionizing Radiation (NAS,BEIRIII).
Values for genetic risk estimators range from 60 to 1100 potential cases of all forms of genetic disorders per million person-rem (NAS, BEIR III). The value of 220 potential cases of all foms of genetic disorders is equal to the sum of the geometric means of the risk of specific genetic deftets and the risk of defects with complex etiology.
The preceding values for risk estimators are consistent with the recomenda-tions of a number of recognized radiation-protection organizations, such as the International Comission on Radiological Protection (ICRP,1977), the National Council on Radiation Protection and Measurements (NCRP, 1975), the National Academy of Sciences (BEIR III), and the United Nations Scientific Comittee on '
the Effects of Atomic Radiation (1982).
The risk of potential fatal cancers in the exposed work-force population at the Haddam Neck facility is estimated as follows: multiplying the annual plant-worker-population dose (about 1010 person-rem) by the somatic risk estimator, the staff estimates that about 0.14 cancer death may occur in the total exposed population. The value of 0.14 cancer death means that the probability of one of facility operation is about 14 chances in 100. The risk of potential genetic disorders attributable to exposure of the Wrk force is a risk borne by the progeny of the entire population and is thus properly considered as part of the risk to the general public.
In sumary, the NRC Staff has drawn the following conclusions regarding occupational radiation dose. The licensee's estimate of about 600 person-rems /
reactor for the repair at Haddam Neck is reasonable. This dose falls within '
the normal range of annual occupational doses observed in recent years at operating reactors. Although the doses resulting from the steam generator repair will increase the annual occupational dose average of 1046 person-rems to approximately 1146 person-rems, this is still well below the 1300 person-rems l per unit annual average which is an upper bound dose average of PWP's experiencing l high levels of special maintenance work. The licensee has' taken appropriate {
i l
l l
l steps to ensure that occupational doses will be maintained within the limits of 10 CFR Part 20 and ALARA. The additional health risks due to these doses over normal risks are quite small, less than one percent of normal risk to the project work force as a whole. The risk to an average individual in the work force will be lower than the risk incurred from partici.oation in many commonplace activities. For the foregoing reasons, the Staff concludes that the environmental impact due to occupational exposure will not significantly affect the quality of the human environment.
Public Radiation Exposure This section contains conservative estimates of the impacts on the public from the proposed steam generatcr repair project. The major sources of radiation and environmental pathways were considered in preparing this section. Public radiation exposure from the Haddam Neck steam generator repair can be estimated by comparing the estimated quantities of radioactive effluents from the steam generator repair with annual average releases and dose estimates from normal operations at Haddam Neck.
The licensee has estimated the amount of radioactivity that will be ieleased in liquid and gaseous effluents as a result of the repair. Those estimates are presented in Table 3. The Staff has reviewed the licensee's estimates and concluded that they are reasonable estimates. Table 3 also presents effluent releases from the plant for the years 1980, 1981, 1983 and 1964 and the FES annual average releases estimates for normal operations. The expected releases from the repair are much less than both the FES estimates and the plant's actual annual releases for nonnal operations. On the basis of this comparison, the staff concludes that the offsite environmental impact that may occur during this period of this procedure will be significantly smaller than that which occurs during normal operation. .
The staff has estimated the doses to individual members of the public as well as the population as a whole in the area surrounding Haddam Neck based on the radioactive effluents which the licensee estimates for the repair (sumarized in Table 3) and on the dose estimates in the FES. In the FES the staff esti-mated that the doses to the total body and any organ of the maximally exposed l
I individual to either radioactive airborne effluents or radioactive liquid effluents would be less than about 5 millf rems. 5fece the radioactive effluents from the repair are estimated to be less than 1% of the effluents from routine operations, the staff estimates that the doses to the total body and any organ of the maximally exposed individual to effluents from the repair will be much less than 1 millirem. This dose is equivalent to a very small fracticn of the limits of 40 CFR Part 190. The annual Ifmits of 40 CFR Part 190 are 25 milli-rems to the total body or any organ except the thyroid and 75 millirems to the thyroid. In a similar manner, the doses to the population of 19,000,000 '
persons within 50 miles of the plant are estimated to be less than 1 person-rems to the total body from exposure to airborne and liquid r3dioactive effluents from the repair. ,
By comparison, every year the same population of about 19,000,000 will receive a cumulatiye total body dose of about 1,L00,000 person-rems from natural background radiation (about 0.1 rem per year per person). Thus, the population total body dose from the repair is less than one millionth of the annual dose due to natural background. On this basis, the Staff concludes that the doses to individuals in unrestricted areas and to the population within 50 miles due to exposure to effluents from the repair will not be environmentally significant.
In summary, the estimated radioactive releases resulting from the repair are much less than those due to nonnal plant operation. The doses due to these releases are small compared to the limits of 40 CFR Part 190 and to the annual doses from natural background radiation. Therefore, the radiological impact of the repair will not significantly affect the quality of the human environment.
Therefore, the Commission concludes that: ,
(1) The estimated total occupational exposure of 600 person-rems / reactor for the repair is within the expected range of doses incurred at light water power reactors in a year.
(2) The risks to the workers involved in the repair are comparable to the risks associated with other occupations.
t
1 I
(3) The licensee has taken appropriate steps to ensure that the occupational dose will be maintained as low as is reasonably achievable and within the limits of 10 CFR Part 20.
(4) The estimated doses to the general public are:
(a) much less than those incurred during normal operation of Haddam :
Neck, and -
(b) negligible in comparison to the dose members of the public receive each year from exposure to natural background radiation.
(5) Based upon the above, there are no significant radiological environmental impacts associated with the proposed amendment. '
With regard to potential non-radiological impacts, the proposed license amendment involves features located entirely within the restricted area as defined in 10 CFR part 20, They do not affect non-radiological plant effluents and have no other environmental impact. Therefore, the Comission concludes that there are no significant non-radiological environmental impacts associated with the proposed license amer.dment.
Alternativt Use of Resources: This action does not involve use of resources not previously considered in the Final Environmental Statement for the Haddam Neck Plant.
- f Atiencies and Persons Consulted: The NRC staff reviewed the licensee's request .
and did not consult other agencies or persons.
FINDING OF NO SIGNIFICANT IMPACT The Comission has detennined not *o prepare an environmental impact statement for the proposed license amendment. .
Based upon the foregoing environmental assessment, we conclude that the proposed action will not have a rignificant effect on the quality of the human environment.
Principal Contributor: John Minns i Dated: March 27,1986 8-I
TABLE 1 ANNUAL COLLECTIVE DOSE AT HADDAM NECK
- Reported Collective Occupational Dose
- Year (Person-rems / Reactor) 1979 1161 1
1990 1353 j 1981 1036
- 1982 126 1983 1384
- 1984 1216 i
3 Average (1979-1984) 1046 i
Average (1979-1985) 1146 USNRC,"Occupationali9adiationExposureatCommercialNuclearPowerReactors, 1983, 'NUREG-0713, Vol. 5, March 1983.
i .
1 l
l l
d i ...
i i
4
, - - . - -,,,m. - - ., - - - w -~- .r,-- , .- t-,- -,,-, , -.- %
,,#--, e - ,- , --
, - - - -y.,,~w c . , ,
l I
Table 2. Incidence of job-related mortalities Mortality Rates Occupational Group (premature deaths per 105 person-years)
Underground metal miners
- 1300 Uranium miners
- 420 Smelter workers
- 190 Mining ** 61 Agriculture, forestry, and fisheries ** 35 Contract construction ** 33 Transportation and public utilities ** 24 Nuclear-plant worker *** 23 Manufacturing ** 7 Wholesale and retail trade ** 6 i
Finance, insurance, and retail estate ** 3 Services ** 3
- Total private sector ** 10
- The President's Report on Occupational Safety and Health, " Report on Occupational Safety and Health by the U.S. Department of Health, Education and Welfare," E.L. Richardson, Secretary, May 1972.
- U.S. Bureau of Labor Statistics, " Occupational Injuries and Illness in the United States by Industry, 1975." Bulletin 1981, 1978.
- The nuclear-plant workers' risk is equal to the sum of the radiation-related risk and the nonradiation-related risk. The estimated occupational risk associated with the industry-wide average gadiation dose of.0.8 rem is about 11 potential premature deaths per 10 person-years due to cancer, based on the risk estimators described in the following text. The average nonradiation-related risk for seven U.S. electrical utilitigs over ti.e period 1970-1979 is about 12 actual premature deaths per 10 person-years as shown in Figure 5 of the paper by R. Wilson and E.S. Kcehl. " Occupational Risks of Ontario Hydro's Atomic Radiation Workers in Perspective," presented at Nuclear Radiation Risks, A Utility-Medk:1 Dialog, sponsored by the Inter.
national Institute of Safety and Health in Washington, D.C., September 22-23, 1980. (Note that the estimate of 11 radiation-related premature cancer deaths describes a potential risk rather than an observed statistic). !
I i
Table 3. Radioactive effluents from the steam generator repairs and ncrmal operations at Haddam Neck Normal operations, Ci/yr/ reactor Type of radioactive Repair, Measured effluent Ci/ reactor 1980 1981 1983 1984 FES Estimates
- Gaseous Noble Gases Negligible ** 1$07 1581 2762 6783 2872 Iodines & Part-
-iculates Negligible ** 0.008 0.01 0.01 0.08 0.73 Tritium Negligible ** 1825 86.5 246 135 ***
Liquid Mixed fission and activation products Negligible ** 0.27 0.71 0.48 0.30 5 Tritium Negligible ** 3291 5289 3899 3662 8000
- FES estimates are taken from Table 3.3.3.4,3.6 and 3.7 FES related to Haddam Neck (Connecticut Yankee) Nuclear Power Plant, Docket No. 50-213, October 1973. -
- Below lower limits of detectability of plant instumentation.
- No value given in the referenced report.
I
, , - - ,- , , - - , , - , - - ,