ML18139A073
| ML18139A073 | |
| Person / Time | |
|---|---|
| Site: | Surry  |
| Issue date: | 03/31/1980 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML18139A070 | List: |
| References | |
| NUREG-0663, NUREG-663, NUDOCS 8003270152 | |
| Download: ML18139A073 (32) | |
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NUREG-0663 drall en11ir11naaen1a1 llall!Dll!RI related to STEAM GENERATOR REPAIR at SURRY POWER STATION, UNIT NO. 1 VIRGINIA ELECTRIC AND POWER COMPANY MARCH 1980 Docket No. 50-280 U. S. Nuclear Regulatory Commission Office of Nuclear Reactor Regulation S 003 27 0 1 5 2
- e DRAFT ENVIRONMENTAL STATEMENT BY THE U. S. NUCLEAR REGULATORY COMMISSION FOR SURRY POWER STATION, UNIT NO. l STEAM GENERATOR REPAIR VIRGINIA ELECTRIC AND POWER COMPANY Docket No. 50-280 NUREG-0663 MARCH l980
e This draft environmental statement was prepared by the U.S. Nuclear Regulatory Commission staff.
The major issue addressed by this environmental statement is the occupational radiation exposure associated with the proposed Steam Generator Repair Program for Unit 1 of the Surry Power Station.
For further information regarding this environmental review, contact:
Phillip C. Cota, Environmental Project Manager Office of Nuclear Reactor Regulation U. S. Nuclear Regulatory Commission Washington, DC 20555 (301) 492-8432 Comments on this draft statement must be received by the Director, Division of Site Safety and Environmental Analysis, U. S. Nuclear Regulatory Commission, Washington, DC 20555, by May 5, 1980, to be assured that they are taken into account in the preparation of the final environmental statement.
ABSTRACT The staff has considered the environmental impacts and economic costs of the proposed steam generator repair at Surry Power Station, Unit 1.
In response to a Commission order, the staff has focused this statement on the occupational radiation exposure associated with the proposed Unit 1 repair program and on alternatives to reduce this exposure.
The staff has concluded that the proposed repair will not significantly affect the quality of the human environment.
Furthermore, any impacts from the repair program are outweighed by its benefits.
e
SUMMARY
In a letter dated August 17, 1977, Virginia Electric and Power Company (VEPCO) proposed to repair the steam generators in Units 1 and 2 of the Surry Power Station (the Statio_n) (Sect. 2.1).
The Nuclear Regulatory Commiss1on staff (the staff) determined that the proposed program would require amending VEPCO's operating licenses for the station, anq on October 27, 1977, a Notice of the Proposed Issuance of Amendments to the licenses was published in t~e Federal Register.
The staff issued a Safety Evaluation Report on the proposed program in December 1978 and an Environmental Impact Appraisal and Negative Declaration in January 1979 (Sect. ~.2).
Three petitions regarding the program have been received and three Director's decisions on these petitions under 10 CFR 2.206 have been issued denying the requests.
The Nuclear Regulatory Commission (the Commissiqn) has reviewed these decisions and has issued an environmental impact statement on the proposed repair *at Unit 1 (Sect. 2.3 and Appendix A).
The major issue in this environmental review is the occupational radiation exposure that the Unit 1 repair program will entail (Sect. ~:3).
'I, The staff comparatively evaluated the environmental impacts of the proposed program and the following alternatives:
(1) Continuation of the present mode of operation (2) Shutdown and replacement of the unit with a generating plant of different design (3) Decontamination of the steam generators before cutting (4)
Retubing the existing steam generators (5) Complete replacement of the steam generators (6) Shorter-term storage of degraded steam generators before removal from site (7)
Immediate intact shipment offsite (8)
Immediate cut-up and shipment offsite (9) Chemical decontamination followed immediately by cut-up ~nd shipment offsite The staff found none of the alternatives to be obviously superior to the proposed program.
Furthermore, the staff has concluded that the proposed program will not significantly affect the quality of the human environment.
The staff has also concluded that any impacts from the proposed repair program are outweighed by its benefits (Sections 4-6).
ii
SUMMARY
1.0 Purpose of this Environmental Statement
2.0 Background
3.0 Description of the Proposed Repair Method TABLE OF CONTENTS 4.0 Environmental Impacts of Steam Generator Repair Project 5.0 Impacts of Alternatives 6.0 Conclusions 7.0 Federal, State, and Local Agencies to Whom this Environmental Statement Was Sent APPENDIX A Memorandum and Order by the U.S. Nuclear Regulatory Commission iii
1.0 PURPOSE OF THIS ENVIRONMENTAL STATEMENT This environmental statement was prepared in response to a Memorandum and Order by the U. S. Nuclear Regulatory Commission, dated March 4, 1980, in t~e ~atter of_Virg1nia Electric and Pow~r Company (Surry Power Station, Units 1 and 2).
A copy of the order is included in this*document as Appendix A.
1-1
e
2.0 BACKGROUND
2.1 HISTORY OF TUBE DEGRADATION IN STEAM GENERATORS Since the Surry Units began generating power in 1972 and 1973, they have experienced a history of excessive tube degradation in the steam generators, resulting in the condition in which approximately 24 percent of the tubes in Unit 1 and about 21 percent of the tubes in Unit 2 were plugged to prevent the transfer of radioactivity from the primary coolant to the steam system.
The tube degradation is ascribed to a corrosion-related phenomenon called "denting," which involves the buildup of corrosion products in the crevices between the Inconel-600 heat exchanger tubes and the carbon steel tube support plates.
As the corrosion product volume expands, the tubes are dented," and occasionally develop leaks.
The plugging of the damaged steam generator tubes affects the thermal and hydraulic performance of the steam generators.
Although the Unit 2 steam generators have been repaired, the degradation and resultant plugging of the tubes in the Unit 1 steam generators is continuing, and will soon result in serious and expensive operating restrictions such as derating.
Another consequence of the tube degradation is the increased occupational exposure to radiation received by workers during the augmented inspection and plugging operations required on the steam generators because of their degraded condition.
The licensee's proposal to eliminate the tube degradation problem is described in*detail in Reference l, "Steam Generator Repair Program, Surry Power Station, Units 1 and 2," consisting of the original submittal dated August 17, 1977, with revisions dated December 2, 1977; April 21, June 2, June 13, June 30, September l, October 25, and November 10, 1978.
2.2 THE STAFF'S INITIAL ENVIRONMENTAL REVIEW In accordance with 10 CFR §50.59 of the Commission's regulations, a licensee seeking to make a change in the Technical Specifications or a change in the facility involving an unreviewed safety question must submit an application for an amendment to the license.
On August 17, 1977, VEPCO submitted a request for NRC review and approval required in order to repair the steam generators at the Surry Power Station, Units 1 and 2.
It was determined in accordance with 10 CFR §50.59 that such a program would 1nvolve an unreviewed safety question and, therefore, would require an amendment of VEPCO's Facility Operating License Nos. DPR-32 and DPR-37 for the Surry plant.
In accordance with 10 CFR §2.105, a Notice of the Proposed Issuance of Amendments to the licenses at issue was published in the Federal Register on October 27, 1977 (42 FR 56652).
The Notice was also available for public inspection in the Commission's Public Document Room and at the local public document room at the Swem Library, College of William and Mary, Williamsburg, Virginia.
This Notice provided an opportunity for interested persons to request a hearing by November 28, 1977.
No requests for a hearing were received in response to that Federal Register notice.*
To determine whether an environmental impact statement for the proposed repair program was warranted, the staff prepared an environmental impact appraisal.
In order to provide an independent basis for evaluating the radiological impacts associated with the repair of degraded steam generators at large pressurized water reactors (PWR's) we contracted with Battelle Pacific Northwest Laboratories (PNL) to perform a generic radiological assessment of the steam generator repair and disposal operations.
This assessment has been published in an NRC report, 2 NUREG/CR-0199, "Radiological Assessment of Steam Generator Removal and Replacement."
Information useful to the environmental review was also obtained from the NRC staff's Safety Evaluation Report (SER) 3 on the repair project, particularly the sections evaluating (1) the measures to reduce corrosion, (2) the As Low As is Reasonably Achievable (ALARA) considerations, and (3) the radiological consequences of postulated accidents.
- The Atomic Safety and Licensing Board constituted to review requests for a hearing under the October 27, 1977 Federal Register Notice provided the Commonwealth of Virginia the opportunity to file a request for a hearing up to 10 days after issuance of the Staff's Safety Evaluation Report which was issued on December 15, 1978.
On December 20, 1978, the Commonwealth stated it would not request a hearing.
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e Based on the Environmental Impact Appraisal, the staff issued a negative declaration on January 19: 1979, in which it "concluded that an environmental impact statement for this particular action is not warranted because the action will not significantly affect the quality of the human environment."
On the same day, Amendment Nos. 46 and 47 were issued to Facility Operating License Nos. DPR-32 and DPR-37, approving the proposed steam generator repair program, subject to the following conditions:
(1)
All fuel shall be removed from the reactor pressure vessel and stored in the spent fuel pool.
(2)
The temporary containment and ventilation systems shall be operating for all cutting and grinding opera-tions involving components with removable radioactive contamination >2200 DPM per 100 cm2 *
(3)
The health physics program and procedures which have been established for the steam generator repair pro-gram shall be implemented.
(4)
Progress reports shall be provided at 60-day intervals from the start of the repair program and due 30 days after close of the interval with a final report provided within 60 days after completion of the repair.
These reports will include:
(a) A summary of the occupational exposure expended to date using the format and detail of Table 5.3-1 of the report entitled "Steam Generator Repair Program."
(b)
An evaluation of the effectiveness of dose reduction techniques as specified in Chapter 6 of the report entitled "Steam Generator Repair Programs" in reducing occupational exposures.
(c)
- An estimate of radioactivity released in both liquid and' gaseous effluents.
(d)
An estimate of the solid radioactive waste generated during the repair effort including volume and radioactive content.
2.3 ACTIONS UNDER 10 CFR 2.206 By letter dated December 29, 1978, Mrs. June Allen on behalf of the North Anna Environmental Coalition requested that the Nuclear Regulatory Commission prepare an environmental impact statement on the Virginia Electric Power Company's proposed steam generator repair program at the Surry Power Station and hold a Show Cause hearing on this proposed program.
This letter was filed pursuant to 10 CFR §2.206 of the Commission's regulations.
Article 10 CFR 2.206 states that any person may file a request for the Director of Nuclear Reactor Regulation to institute a proceeding to modify, suspend, or revoke a license, or for such other action as may be proper.
In the Director's Decision issued on February 1, 1979, the request was denied.
By letter dated February 20, 1979, the Environmental Policy Institute requested that the Nuclear Regulatory Commission prepare an environ-mental impact statement on the Virginia Electric Power Company's proposed steam generator repair program at the Surry Power Station and hold a Show Cause hearing on this proposed*program.
This letter was filed pursuant to 10 CFR §2.206 of the Commission's regulations.
In the Director's Decision issued on April 4, 1979, this request was denied.
By petition dated April 21, 1979, Mr. James B. Dougherty on behalf of four citizen's groups:
Potomac Alliance, Citizen's Energy Forum, Inc., the Virginia Sunshine Alliance, and Truth in Power, Inc. requested that:
- 1.
The Commission shall suspend VEPCO's Operating License No. DPR-37 and order that the Surry steam generator replacement project be brought to an immediate halt.
- 2.
The Commission shall direct the Director of Nuclear Reactor Regulation to serve upon VEPCO an Order to Show Cause at a public hearing why Operating License No. DPR-37 should not be suspended pending performance of the enviromental studies and other relief described below.
- 3.
The Commission shall direct the NRC staff to prepare an environmental impact statement addressing the Surry project.
- 4.
The Commission shall direct the NRC staff to prepare a programmatic environmental impact statement addres-sing the cumulative environmental impacts and the long-range policy implications of current and future steam generator replacement and repair projects.
- 5.
The Commission shall prohibit the NRC staff from reinstating Operating License No. DPR-37 or permitting further progress on the Surry steam generator replacement program until it has fully reviewed and satisfied 2-2
its obligation under the following sections of the regulations, including making available an opportunity for a public hearing:
(a) 10 CFR §20.302, requiring NRC approval of proposals to dispose of nuclear waste; (b) 10 CFR (50.82, requiring NRC approval of proposals to dismantle nuclear power plants; and (c) 10 CFR §20.l(c), requiring occupational radiation exposures to be maintained as low as is reasonably achievable.
- 6.
The Commission shall prohibit VEPCO from making any modification to the Surry facility resulting in dis-charges into navigable waters until it has obtained from the Commonwealth of Virginia an NPDES permit or an amendment to its current NPDES permit for the Surry plant, as required under, e.g., § 301 and 402 of the Federal Water Pollution Control Act, 42 U.S.C.
§1311 and 1342.
- 7.
The Commission shall prohibit the staff from approving any modification of the Surry facility resulting in discharges into§navigable waters until it has received from the Commonwealth of Virginia the certification required under 401 of the Federal Water Pollution Control Act, 42 U.S.C. ~1341.
- 8.
The Commission shall notify all Atomic Safety and Licensing Boards, as appropriate, of the above actions and shall prohibit the issuance of any permit, license, or amendment thereto allowing the replacement or repair of steam generators pending the completion of the environmental impact statements and other studies described above.
The Secretary of the Commission directed the staff on May 22, 1979, to treat this petition under 10 CFR §2.206 of the Commission's regulations.
Notice that the petition was being treated under 10 CFR 2.206 and was published in the Federal Register, 44 Fed. Reg. 36522 (June 22, 1979).
In the Director's Decision issued on October 24, 1979, the requests of this petition were denied also.
The Commission conducted a sua sponte review of the three Director's decisions, on the issue of the need for an environmental impact statement regarding the proposed repair.
In a Memorandum and Order issued on March 4, 1980, the Commission identified the occupational radiation exposure as tpe only adverse environmental impact associated with the repair program that might be considered significant, stated that it was unable to determine whether the environmental impact is significant, and therefore directed the staff to expeditiously prepare and issue an environmental impact statement on the proposed repair at Unit 1.
(Repairs at Unit 2 are completed.)
2.4 MAJOR ISSUE The major issue is the occupational radiation exposure associated with the proposed repair of the degraded steam generators of Unit 1.
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3.0 DESCRIPTION
OF THE PROPOSED REPAIR METHOD A drawing showing the principal parts of the typical steam generator is presented in Figure 1.
Figure 2 shows the regions where the main cuts are proposed to remove the degraded steam generator.
It shows also the radiation levels in these regions for Unit 2.
A brief description of VEPCO's proposed repair procedure follows.
In preparation for the repair of the steam generators, all of the fuel will be removed from the reactor core and placed in the spent fuel pool.
Then one of the three steam generators will be cut out of the reactor system.
Present plans are to cut through the inlet and outlet reactor coolant piping, and through the steam line piping and feedwater piping.
The steam generator wall will be cut on the transition zone between the lower assembly and the larger diameter upper shell assembly.
The upper assembly will be lifted off and stored inside the containment vessel.
The lower assembly will be lifted by crane from its support, tipped on its side, and transported out of the containment through the equipment hatch.
It will then be transported to the concrete vault where it will be stored until the station is decommissioned.
The replacement lower assembly will be transported into the containment and placed on its support.
The old upper assembly, after some refurbishment, and the new lower assembly will be welded together in the field.
The piping mentioned above will be welded to the repaired steam generator.
The same procedure will be followed for the other two steam generators.
It is anticipated that the unit will be out of service for about six months.
A number of changes (see Sections 2.3 through 2.7 of Reference 1) have been made in the materials, the design and the operating procedure for the replacement steam generators to assure that the corrosion and denting problems will not recur.
Among the more important of these changes are (1) using All-Volatile-Treatment chemistry control in the secondary system from the beginning of operation, (2) using corrosion resistant SA240 Type 405 ferritic stainless steel rather than carbon steel for the support plate material, (3) thermally treating the Inconel 600 heat exchanger tubes for better corrosion resistance, and (4) using a broached hole pattern with a quatrefoil design in the support plates rather than separately drilled flow holes to minimize the accumulation of corro-sion products where the tubes pass through the plates.
The staff's review of the expected effects of the proposed changes is presented in detail in the introductory section of the SER3 for the repair project.
We have concluded in the SER that the new steam generator design incorporates features to eliminate the potential for the various forms of tube degradation observed to date.
The licensee proposes to store the degraded steam generator lower assemblies for the life of the plant in an above-ground concrete structure with walls about 3 feet thick.* The structure will be sealed against water intrusion, but is provided with an internal sump to collect any water which may get in by means such as condensation.
Ventilation to allow for thermal expansion and contraction of the air inside the structure is provided through high efficiency particulate air filters.
Several removable 2-inch plugs will be provided to permit the conduct of radiation surveys without entering the structure.
The method of ultimate disposal will be decided when the reactor itself is scheduled for decommissioning.
- One steam generator lower assembly may be shipped to Hanford for examination and research.
The environmental effects of the shipment of that assembly, upon which the repair effort is not dependent, are to be separately assessed by DOE/PNL. The approval sought for the proposed repair program is not dependent on the proposed shipment.
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e MANWAY ANTIVIBRATION BARS MANWAY CHANNEL HEAD FIGURE l. Typical Steam Generator 3-2
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v A11 values are on c~itact unless oth~r.,i se noted el *. i6' RCS i'u=p Suction RCS Hot Leg 300 IIIR/hOUr 70~-soo mR/r.:u:-
s~-soo mR/hol.U' FIGURE 2 TYPICAL RADIATION LEVELS AROUND STEA.~ GE!l!RATOF.5 WITH PRIMARY SIDE'DRAINED AND SECON!:Ain' SIDE AT 72% LEVEL 3-3
e e
4.0 ENVIRONMENTAL IMPACTS OF STEAM GENERATOR REPAIR PROJECT This assessment of impacts was performed for Surry Power Station Units 1 and 2.
4.1 RADIOLOGICAL ASSESSMENT 4.1.1 Occupational Exposure The generic radiological assessment of steam generator repair, prepared for the NRC by PNL and reported in NUREG/CR-0199, provides an upper bound estimate of the occupational doses and off-site radiological releases associated with the repair of steam generators at a large PWR:
The conservatisms in PNL's methods of assess-ment, described below, provide the opportunity to reduce occupational doses for the repair operations in specific cases considerably below the generic estimates in NUREG/CR-0199.
The PNL generic estimates of occupational exposure (man-rem) were derived by multiplying maintenance activity man-hours by exposure rates (rem/hour) for the repair activities.
Maintenance activities were developed by PNL as a composite of the work descriptions for removal and replacement of the steam generators at Surry and Turkey Point as determined by VEPCO and Florida Power and Light Company.
Man-hour estimates for each activity were developed by PNL based on prior experience with similar activities, using standard estimating techniques.
Exposure rates were based on information from several sources including data from measurements made at several operating PWR's including the Surry Units.
PNL usually selected exposure rate values on the high end of the range of values measured at the several plants.
The generic estimate of the total collective occupational whole body dose for the repair of three steam generators* was presented in NUREG/CR-0199 as a range of values, 3380 to 5840 man-rem.
Both ends of this range were conservatively estimated and represent upper bound values.
The upper value, 5840 man-rem, was estimated assuming no credit for dose saving techniques.
The lower value, 3380 man-rem, was estimated taking credit only for three dose reduction methods:
(1) shielding by raising the steam generator water level, (2) using a limited amount of remote tooling, and (3) increasing the source-to-receiver distance.
VEPCO's total estimate of 2070 man-rem.per unit at Surry included not only these dose reduction measures but also measures such as additional temporary lead shielding, local decontamination, pre-job planning and pre-job training.
The dose reduction procedures proposed by VEPCO are discussed in more detail in our SER. 3 In view of the above discussion, the lower end of the generic range, 3380 man-rem, is the appropriate estimate for comparison with VEPCO's estimate of 2070 man-rem per unit.
A summary comparing VEPCO's estimates with our generic estimates in NUREG/CR-0199 for the four main phases of the project is given in Table 4.1.
Table 4.1 Comparison of Occupational Collective Whole Body Dose Estimates Phase Preparation Removal Installation Storage Total NRC Generic Estimate Dose, man-rem/unit 450-810 1100-1700 1800-330 30 3380-5840 VEPCO Esimtate Dose, man-rem/unit 2070 599 559 877 35 The discrepancies between the detailed estimates are accounted for by the same factors discussed above for the total estimates.
VEPCO's calculations of doses used commonly accepted practices for calculating doses and took into account the dose reduction measures proposed to maintain doses As Low As Reasonably Achievable (ALARA),
including local decontamination, temporary lead shielding, pre-job planning, pre-job training and use of remote tools where practicable.
In Section 6 of Reference l, VEPCO has documented its consideration of the guidance with regard to ALARA issues in Regulatory Guide 8.8, Revision 2. 4 We have reviewed VEPCO's treatment of ALARA issues in detail in Section 4 of the SER. 3 We concluded that VEPCO's efforts to maintain occupational doses ALARA during the repair effort are reasonable.
- Each Surry unit has three steam generators.
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e In summary, the above discussion shows that the differences between the lower generic estimate (3380 man-rem per unit) and VEPCO's estimate* (2070 man-rem per unit) can be reconciled by (1) the use of lower dose rates measured at Surry in the VEPCO estimate and (2) the use of more dose reducing measures by VEPCO than in the generic estimate.
We therefore conclude that VEPCO's estimate of 2070 man-rem is a more realistic estimate than 3380 man-rem* for the repair of the steam generators in one Surry unit.
Consequently, in the remainder *of this appraisal, we have used 2070 man-rem per unit as the occupational dose for the steam generator repair work at Surry.
The replacement of the 3 generators in Surry Unit 2 was completed in 37 weeks in 1979.
The total occupational dose received by workers at Surry Unit 2 during the repair program was 2140 man-rem.
The dose rates at Surry Unit 1 have been 30-40 percent higher than at Unit 2.
However, VEPCO believes that their experience:from com-pleting the Unit 2 repair program will allow them to do a more effective job of maintaining exposures ALARA on Unit 1.
Therefore, VEPCO believes that its original estimate of 2070 man-rem per unit is reasonable for Unit 1.
We followed the work at Unit 2 closely and we agree that 2070 man-rem is a reasonable estimate for.Unit 1.
(Even if Unit 1 doses proved to be 30-40 percent higher than for Unit 2, the basic argu~ents presented in the following paragraphs would still be valid.)
To put into perspective the occupational doses to be incurred in repairing steam generators, it is helpful t6' compare these doses (1) with those expected from the normal operation of nuclear plants, (2) with the projected long-term man-rem saving resulting from steam generator repair and (3) with doses received from natural back-ground radiation.
Although the AEC was starting to compile occupational exposure estimates for nuclear power plant operation at the time that the Surry*1 and 2 FES was prepared in 1972, such exposures were not specifically considered in the Surry 1 and 2 FES.
In recent environmental statements for new nuclear power plants, we have provided an estimate of 500 man-rem *per reactor unit as the average annual occupational dose.
This average is the annual average over the life of*the plant (30-40 years}.
This estimate is based on reported data from operating power reactors; a summary of that data is provided in Table 4.2 That data show that 500 man-rem per reactor unit per year is roughly-the average of the wide range of doses incurred at all light water cooled reactor units over several years. 'The amount of dose incurred at any single* reactor unit in a year is highly dependent on the amount of major maintenance per-formed that year.
Every year several units require some items of major maintenance which result in doses for those units well above the average of 500 man-rem.
These doses are i-ncluded in the average and we do not consider them to be significant deviations from the average.
Simply put, the steam generator repair program is major maintenance which will result in an annual dose for Unit 1 above the average.
However, as Table 4.2 shows, the 2070 man-rem is within the historical range of doses about the average for one unit in a year, and a small fraction of the occupational dose to be expected ovej the life of the plant.
Table 4.2 Occu~ational Dose at U.S. Light Water Reactors (man-rem per reactor unit)
Year Average Low High 1975 475 21 2022 1976 499 74 2648 1977 570 87 3142 1978 497 158 1621 In 1975, 1976, and 1977, workers at Surry Units 1 and 2 received whole body doses of 638 man-rem, 1 1287 man-rem 1 and 1410 man-rem, 6 respectively, during the inspection and plugging of degraded steam generator tubes.
The total occupational doses for the two units were 1649 man-rem in 1975, 3163 man-rem in 1976, and 2416 man-rem in 1977. 5 These doses are higher than the 570 man-rem per year average for U.S. light water reactors in 1977.
We concluded in the SER that the proposed repair would eliminate the potential for the kinds of tube degradation observed to date.
Based on our experience with plants without severe denting problems and the staff conclusion regarding corrosion reduction, doses due to the inspection and plugging of degraded tubes would be markedly reduced, and we conclude that occupational exposure after the repair will be reduced by hundreds of man-rem per 4-2
e year for the two units. This would result in total occupational exposures at Surry approaching more closely the national average value for light water reactors (500 man-rem per reactor-year).
We further conclude that the dose savings of hundreds of man-rem per year would over a period of years tend to offset the immediate one-time dose of 4140 man-rem for repairing the six steam generators in both units.
VEPCO has estimated that the after-repair occupational dose for the inspection and repair of degraded steam generator tubes will be reduced to 25 man-rem per year for the two Surry units.
Although the 25 man-rem per year appears to be a reasonable number for Regulatory Guide 1.83 inspections, we have conservatively estimated a higher value of 100 man-rem per year to account for additional inspections which may be performed to check the initial performance of the improved steam generators and to correspond more closely to recent industry experience.
The saving of occupational exposure resulting from the repair effort may be estimated by subtracting the estimated annual dose after repair from the observed annual dose before repair.
The doses of 1287 man-rem in 1976 and 1410 man-rem in 1977 are considered representative of exposures related to steam generator operation before repair.
The 638 man-rem dose in 1975 is not representative of operation with degraded steam generators because significant tube degradation was not observed in Unit 1 until September 1975 and in Unit 2 until January 1976.
Subtracting the after-repair dose of 100 man-rem from the before-repair range of 1287 to 1410 man-rem leads to a saving of 1187 to 1310 man-rem per year.
At these rates of saving, the 4140 man-rem cost of the repair would be offset in 3 to 4 years, should the units continue to operate.
Operating experience at the Surry plant over the last three years demonstrates that the steam generators can continue to operate with the degraded tubes plugged, but frequent inspection and plugging as performed during the last three years would be required to assure that the integrity of the steam generators would be maintained.
At the current rate of tube plugging, about three percent per year, it is the staff's judgment that, with con-tinued inspections and plugging, Unit 1 could continue to operate for some period and, even if reduced power were required, the economic balance would favor continued operation of the unit, as opposed to decommissioning.
On the other hand, continued degradation of the integrity of a major component, such as steam generators, results in continued small reductions in overall safety margins.
This potential has been carefully considered on the basis of the results of each inspection over the past four years.
While these margins remain acceptable, any continued degradation would require continued careful assess-ment to assure that degradation does not become excessive.
The average* annual dose to an individual due to natural background radiation in the United States is roughly 0.1 rem.
However, there are very broad variations in the average dose due to a number of factors such as altitude above sea level and local geologic formations.
As altitude increases, the dose rate from cosmic radiation (radiation from space) increases.
Because Denver, Colorado, for example, is at a much higher altitude than Washington, D.C., the average natural background dose in Denver is roughly 0.08 rem per year larger than in Washington.
Multiplying 0.08 rem per year times 50 years (a conservative estimate of average lifespan) yields the result that an individual would receive 4 rem more dose from a lifetime of exposure to natural background radiation in Denver than would be received from living in Washington.
The estimated Surry repair program dose of 4140 man-rem for both units will be spread over at least 2000 workers over a two-year period (probably between.2500 and 3500 workers).
Therefore, the average dose to a worker for this project will be roughly 2 rem - half of the variation in natural background radiation described above.
In a different view, 2000 people living in Denver would receive an aggregate of 8000 more man-rem from their lifetimes of exposure to natural background than 2000 people living in Washington, D. C.
The increase~i~:.
dose is not considered-a negative factor in a decision of whether to live in Denver or _Washington, D. C.
Therefore, we conclude that based on a comparison with doses to natural background radiation, the estimated dose for the steam generator replacement represents an insignificant and societally acceptable impact.
We calculate that 4140 man-rem, the occupational dose estimate to replace the steam generators at both units, corresponds to.a risk of less than one premature fatal cancer.
We also calculate that 4140 man-rem.corresponds to a risk of one genetic effect to the ensuing five generations.
These risks are based on risk estimators derived in the BEIR report14 from data for the population as a whole.
For a selected population such as is likely for the exposed workers involved in the repair program con~isting mainl~ of ma~es i~ age ~a~ge from 20 to 40 these risks would tend to be somewhat less.
These risks are incremental risks, risks in addition to the no;mal risks of cancer and genetic effects we all face co~tinuously.
For a population of 2000 these n?rmal risks would result in 300-400 cancer deaths and 100-150 genetic effects (genetic effects are genetic diseases or malformations).
In summary, the staff has drawn the following conclusions regarding occupational radiation ~xposure.
VEPCq's.
estimate of 2070 man-rem per unit for. the repair of the steam generators is reasonable.
This do~e falls within the normal range of annual occupational doses which have been observed in recent years at operatin~ reactors.
Our review in the Safety Evaluation Report3 concludes that VEPCO is taking the necessary steps to insure that 4-3
e 11,
,1 occupational doses will be maintained ALARA.
The renovation of the.steam generators will lead to occupational dose reductions of hundreds of man-rem per year.
These dos~ saving~ over a period of several years will *outweigh the immediate large one-time dose resulting from the repair operation.
The doses to the work force as a whole and to the average worker will be within the variations in lifetime doses due to natural background radiatitm in the U.S.
The individual risks associated with exposures involved in the repair program will be controlled and limited so as not to exceed the limits set forth in 10 CFR Part 20 for occupational exposure.
These limits are intended to assure that the hazard to any exposed individual is extremely small.
The additional health risks due to these doses over normal risks are quite small, less than one percent of normal risks to the project work force as a whole.
For the foregoing reasons, the Staff concludes that the environmental effect due to occupational radiation exposure is insignificant and acceptable, and in any case the proposed repair program wil 1 'reduce occupational, exposure in the long run.
4.1.2 Public Radiation Exposure Our independent analysis of the gaseous and liquid releases of radio'activity from the plant site during the steam generator repair project is based in 1 arge part on the generic' report, 2 NUREG/CR-0199, prepared by Pacific Northwest Laboratories for the NRC.
The estimates of releases in this report are upper-bound values, based on conservatively high estimates, for each type of release.
Similar estimates of the gaseous and liquid effluents during the repair were made by VEPCO i_n Reference 1.
These estimates were based on the specific equipment design and proc_edures to be used at the Surry plant.
Table 4.3 presents the NUREG/CR-0199 estimates2 and VEPCO's estimates 1 of the radioactive effluents which will be released as a result of the repair effort. Table 4.3 also presents Surry.'s reported average radioactive effluent releases for 197612 and 1977, 6 and the annual average radioactive effluent release estimates presented in the Surry FES. 7 Table 4.3 shows that the releases estimated by VEPCO and the generic report for *the repair*
effort are much lower (except for the airborne particulates) than the Surry 1976 and 1977 releases and the FES.
annual average estimates.
For airborne particulates, the VEPCO estimates of releases are in the same range as' or lower than the 1976 and 1977 releases in Table 4.3.
The Surry FES 7 does not present numerical estimates of airborne particulate and tritium releases.
However, airborne particulates and tritium are ~mall dose contribu-tors compared to radioiodine and noble gases for the highest dose pathways of exposure to individuals in the
- general public.
Therefore, the conclusions regarding dose consequences presented in the fES are still.valid.
The VEPCO estimates of gaseous releases from the repair effort are larger than the NRC generi~ esti~ates be~ause.
the VEPCO values include the releases from fuel unloading and reloading, which are much larger than the~aseous '
releases -from the rest of the repair operation.
VEPCO' figures are based mainly on experience at Surry*with refueling operations.
The refueling releases were not included in the NUREG/CR-0199 estimate, sinte the utility normally would plan to carry out the steam generator repair during a scheduled shutdown for refueling.
For the other gaseous releases such as those from pipe cutting, VEPCO used commonly accepted,calculational methods, for example in calculating the kerf for each cut and in assuming that all radioactive material adhering t~.the inner cut surface would become airborne.
Therefore, we conclude that VEPCO's estimates of :gaseous releases, including those from the fuel handling operations, were carried out in an acceptable manner and represent reasonable estimates.*
In Table 4.3 the estimates for liquid releases of tritium vary widely because VEPCO.plans to store the primary reactor *coolant water for re-use, whereas the generic (NUREG/CR-0199) estimate assumes that the coolant is discharged after processing for nuclides other than tritium.
The VEPCO estimate for the release of mixed.. fission and activation products is larger than the generic estimate because the latter did not include the release~ of the secondary coolant nor the local decontamination solutions.
Both estimates included the activities in laundry-waste water.
VEPCO based its estimates *of releases from the laundry waste water and secondary coolant on past measurements of these sources at Surry.
- VEPCO used commonly accepted methods to calculate the releases from local decontamination solutions.
Based on these several considerations, we conclude.that the licensee has made reasonable estimates of the radioactive liquid effluents during the repair effort, and that these estimates correspond, as well, to our own best estimates.
As stated above, steam generator repair at Surry Unit 2 was completed in 1979.
Table 4.3 shows the actual releases* for Unit 2.
As expected, all of the releases were lower than they would have been_ during average, normal operation.
The environmental impact.s created by these releases are less than those stated in the Surry FES.
Therefore, the Unit 1 release estimates have not been changed in light of the Unit 2 measurements.
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Table 4.3 Radioactive Effluents from Surry Station Steam Generator ReQair OQerating ExQerience FES NUREG/
Actual Surry Surry Annual VEPCO CR-0199 Surry 1976 1977 Average Type of Release Release Unit 2 Average Average Release Radioactive Estimates Estimates Releases Releases Releases Estimates Effluent (Ci/Unit)
(Ci/Unit)
(Ci/Unit)
(Ci/Unit)
(Ci/Unit)
(Ci/Unit/Yr)
GASEOUS Noble Gases 100 9600 9510 3360 Halogens (Iodines) 0.0045 included in 0.0000069 0.27 0.24 0.92 particulates Particulates 0.0031 0.0001 0.0013 0.041 0.001 Tritium 8.5 4.3 19 44 I u, LIQUID Mixed Fission &
0.35 0.14 0.5 17 3.8 53 Activation Products Tritium 0.1 190 8.5 390 204 1000
e Our estimates of dose to individuals and to the population as a whble in the area surrounding the Surry site are based on the radioactive effluents which VEPCO estimated for the repair effort (summarized in Table 4.3) and on the calculational methods presented in Regulatory Guide 1.109, 1.111 and 1.113. 11 ' 9 ' 8 We conclude that offsite individuals will receive doses from the repair effort of the same order or less than the annual dose consequences presented in the FES. 7 The doses to the population within 50 miles will be less than 5 man-rem to the thyroid or total body from liquid effluents, and less than 2 man-rem to the thyroid or total body from airborne effluents.
Every year the same populatjon (about 2 million) will receive a total body,dose of more than 100,000 man-re.m from the natural background radiation in the vicinity of Surry (0.065 rem per year). 13 Thus, the population total body dose from the repair effort is less than 0.01 percent of the annual dose due to natural background.
On these bases, we conclude that the doses to individuals in unrestricted areas and to the population within 50 miles due to gaseous arid liquid effluents from the repair project will not be environmentally significant.
VEPCO has estimated that the repair effort will generate 740 cubic meters of solid waste per unit containing 19 curies of radioactivity. 1 Based on the information presented in NUREG/CR-0199, we estimate that 2300 cubic meters of solid waste containing 37 curies of radioactivity will be generated per unit. 2 Our estimate i.s higher than the licensee's estimate because we assumed that all of the radioacitivy in the solutions from main cool~nt pipe decontamination would be solidified.
Neither of these estimates include the radio?ctivity on the inside surfaces of the old steam generators.
In 1976 and 1977, Surry generated an annual average of 370 cubic meters of solid waste per unit containing 310 curies per unit of radioactivity. 6 ' 2 The amount of radioactivity in the wastes from the repair effort will be about 10 percent of this average annual production during operation.
Since the solid wastes represent an impact which is a. small part of the impact from solid wastes from normal operation, we conclude that the radiological impact is not environmentally significant.
Steam generator replacement operations at Unit 2 generated 1600 cubic meters of waste containing 64 curies of radioactivity.
Both the volµme and radioactive content of the solid radioactive waste generated are comparable to our estimates.
On the basis of long-term onsite storage of the degraded steam generators until the reactors are decommissioned, there will be essentially no radioactive effluents from the generators for 30 years Final disposal at that time will result in small offsite gaseous and liquid radioactive releases, because a large frattion of the radioactive nuclides in the steam generators will have decayed in 30 years.
I The stored steam generators will present a source of direct and scattered radiation.
We estimate that each steam generator will contain about 1000 Ci of radioactivity including 720 Ci of Cobalt-60, the principal con-tributor to direct dose.
This is based on the estimate of the contamination of steam generator primary side surfaces given in NUREG/CR-0199. 2 The staff estimated a dose rate of less than 0.0001 millirem per hour at the nearest site boundary due to this activity.
An individual spending an entire year at this location would receive less than 1 millirem of radiation exposure.
This dose would be approximately halved every 5 years because of the decay of the principal dose rate contributing activity, Co-60.
VEPCO made a similar calculation and reached the same conclusion.
Since this dose represents roughly one percent of the annual dose from natural background, 12 the staff concludes that the direct dose impact to the public from the stored generators will be minimal and not environmentally significant.
The repair effort will return the plant to the design condition on which our evaluation in the FES 7 was based.
Therefore, we conclude that the estimates of routine releases of radioactivity and the potential doses to the public from those effluents after the repair should remain as presented in the FES.
Since our estimates of radioactive effluents from Surry during normal operation after the repair effort are about the same or lower than those effluents presented in the FES, 7 we conclude that the impact on biota other than man will be no greater than that impact presented in the FES.
In summary, the offsite doses resulting from the steam generator repair will be less than those from recent plant operation since the expected releases of radioactive material as a result of the repair effort will be less than the releases from normal operation.
These doses are comparable to doses presented in the FES, 7 and small compared to the annual doses from natural background radiation.
Therefore, the radiological impact of the repair project to the public will not significantly affect the human environment.
4.2 ECONOMIC COSTS OF STEAM GENERATOR REPAIR The following analysis is done in 1977 dollars.
VEPCO has estimated that, over the life of the plant, the proposed steam generator repair project will result in a net dollar savings of at least $125,000,000 compared with the cost of continued operation of the existing steam generators, with an optimistic assumed scenario of tube plugging and derating.
The cost of purchasing and installing the steam generator lower assemblies and associated activities is estimated about $66,000,000 for the two units.
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The cost of removal and disposal of the six degraded lower assemblies is expected to be about $10,000,000.
The estimate for replacement power during the outage for repair is about $66,000,000.
The total project cost is, therefore, about $142,000,000.
The cost of replacement power during the outage is based on the higher fuel costs of coal, oil and gas-fired units which VEPCO would press into service to replace the power lost by the shutdown of one of the Surry Units.
The VEPCO estimate of $66,000,000 based on differential fuel costs is reasonable in view of the total value of the replacement power:
822,500 kW x 0.6 capacity factor x 360 days x 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />s/day x $.04/kWhr = $183,000,000.
VEPCO's estimate of $66,000,000 corresponds to a fuel differential cost of about $0.014/kWhr between fossil-fired plants and a nuclear plant.
We consider this differential cost estimate reasonable.
The VEPCO estimated net saving of $125,000,000 is based largely on the cost of replacement power due to derating.
We assessed the reasonableness of this estimate by comparing it to the cost of replacement power if both units had to be derated.
The cost would be about $360,000,000 after 10 years of derating at an assumed rate of 3 percent per year (the current rate of tube degradation is greater than 3 percent per year).
Therefore, VEPCO's estimate that $125,000,000 would be saved over the life of the plant even after spending $142,000,000 for the steam generator repair is conservative.
The VEPCO estimate of $10,000,000 for removal and disposal of the degraded steam generators assumes onsite storage for 30 years followed by sectioning and shipment to a licensed burial facility for low-level waste.
This estimate is not out of line when compared to recent estimates 10 for the decommissioning of complete reactors by dismantlement after a cooling period (about $30,000,000).
This consideration of costs does not take into account the continuing costs of tube inspection and plugging services, nor the costs of possible future modifications to control corrosion, if the repair is not done.
It also does not consider the cost of the current lack of reliability and availability.
In 1976, Surry Unit 1 was offline for 36 days and Unit 2 for 139 days for tube inspection and plugging.
In 1977, the outage times for tube inspection and plugging were 50 days for Unit 1 and 70 days for Unit 2.
In Section 5, the economic and other impacts of alternative methods of repairing the steam generators will be compared.
4.3 NON-RADIOLOGICAL ENVIRONMENTAL COSTS The non-radiological impacts of the repair project on the environment are small compared to those of building and operating the reactors.
These small costs include the commitment of about one acre of land on the site for the storage of the degraded steam generators for the life of the station on the presently existing industrial site. There will be some noise generated by onsite equipment and a s~all effect on local traffic by approxi-
~ately 125 construction workers per shift, but these effects will be insignificant.
The material costs of the proposed action will include about 1350 tons of carbon steel, 48 tons of stainless steel, AND 3000 cubic yards of concrete.
These quantities are about 2 percent of the quantity of steel and about 8 percent of the concrete used in the original construction of the plant.None of these costs is significant 4.4 ENVIRONMENTAL IMPACT OF POSTULATED ACCIDENTS As is discussed in our SER, 3 the design and plant operating parameters which are relevant to accident analyses will not change as a result of the steam generator repair effort.
Therefore, the assessment of the environ-mental impact of postulated accidents presented in the final environmental statements for Surry Units 1 and 2 will be unchanged and remain valid.
However, there are a few types of accidents which are possible due to the operations involved in the repair effort.
One such postulated accident is the rupture of the Reactor Water Storage Tank by a crane drop.
The bounds of the radiological consequences of this accident were discussed in the FES 7 for Surry Unit 2 under the heading -
"Release of liquid waste contents."
A second type of postulated accident related to the repair effort would involve the dropping and rupture of a removed steam generator outside the reactor containment while it was being transported to the storage vault.
This accident would involve the rupture of the steel covers which will have been welded over each of the steam generator cuts to prevent the spread of the neutron-activated corrosion products adhering to the inner surfaces.
The method used to assess the radiological consequences of a rupture which could release contamination on the primary side surfaces to the atmosphere is described in the SER. 3 To obtain* a more realistic estimate for the purpose of evaluating the environmental impact, we used an atmospheric dispersion factor of 1.6 x 10 4 seconds per cubic meter.
On this basis, we concluded that this accident would result in a dose of 0.06 rem to the lungs of an individual at the site boundary.
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e e
The do?e consequences of a drop accident inside containment would be lower since the c9ntainment ventilation syste~ would reduce the radioactivity released to the environment.
In su~mary, we concluded ~hat the consequences of postulated accidents from the repair operation would *no~*be environmentally significa~t.
4-8
- ~,.
i,,
e 5.0 Impacts of Alternatives The analysis in this section was done for both Surry units in 1977 dollars.
The basic choices of future action regarding the tube degradation problem are (1) repair of the degraded steam generators, (2) continuation of the present mode of operation, with increasing costs in plant efficiency and occupational exposure, and (3) shutdown of the Surry Units 1 and 2, and replacement by generating plants of different design.
VEPCO opted for repairing the degraded steam generators, with changes in design, materials and operating procedures calculated to eliminate the tube denting problem.
In the absence of methods to arrest or greatly reduce denting, the continuation of operation for an extended period in the present mode is impractical. With tube degradation and plugging continuing at the present rate, the units would soon be required to operate at lower power.
VEPCO has esti-mated the cost of replacement power, based on fuel differential costs, to be about $180,000 per day for the shutdown of a unit.
Consequently, the cost of derating the Surry units would be high.
Also, the man-rem cost of occupational exposure during inspection and plugging of tubes would continue to be high, resulting in a dose higher than 4140 man-rem in 3 or 4 years.
Laboratory test programs on the denting phenomenon are currently underway to define the corrosion process more precisely and to develop preventive measures such as corrosion inhibitors.
While the combination of steam generator secondary side cleaning and corrosion inhibitors is being studied by some utili-ties to combat denting in its early stages, the denting phenomenon at Surry is too advanced for such measures to be practical. Therefore, VEPCO cannot count on a greatly reduced future rate of tube degradation to justify continuing the present mode of operation.
The option of shutting down the Surry station and replacing it with a plant of different design>f:..is easily shown to be much more costly than that of repairing the steam generators.
VEPCO estimates (Section 5.5.1.3 of Reference 1) that the capital cost of new nuclear units with improved steam generators would be about $2.7 billion dollars and would require about 12~ years to build.
New fossil units would cost abdut $1.2 billion and require about 8 years to build.
(We consider the coal estimate low; capital cost for a coal-fired plant is usually about 80 percent of that for a nuclear plant.) Florida Power and Light Company made a similar comparison for repairing the steam generators in Turkey Point Units 3 and 4.
Their estimate was about $77/kW for the proposed steam generator repair operation, compared to $224/kW for gas turbine units, $1059/kW for a coal-fired plant, and $1448/kW for a nuclear plant of improved design.
Although the Turkey Point estimates are in different terms, the cost comparison again overwhelmingly favors the repair option.
For these reasons, the plant replacement option is net economically feasible.
In addition, there would be significant environmental impacts from such a large-scale construction operation.
The most practical overall option is, therefore, to repair the degraded steam generators.
In the remainder of this section, we shall consider the radiological and economic costs of several alternative ways of repairing and disposing of the degraded steam generators.
An important item in estimating economic costs is the cost of replacement power during unit outage.
VEPCO's cost esti-mate of $66,000,000 for the power needed during the 180-day outage of each unit corresponds to a replacement power cost of nearly $200,000 per unit per day of outage.
5.1 DECONTAMINATION VEPCO has estimated (Section 5.5.2.1 of Reference 1) that chemical decontamination of the steam generators before cutting would result in a net saving of 300 to 400 man-rems per unit in occupational exposure.
However, it would cost about 1.5 months in additional outage of each unit.
Replacement power for this additional outage would cost about $9,000,000.
In addition, about 200,000 gallons of radioactive waste would be produced.
VEPCO also considered mechanical decontamination of the inner surfaces of the steam generator, but estimated that the occupational exposure during the decontamination operation would exceed the later saving in dose to workers.
- From the Need for Station" discussion in the Addendum to the North Anna FES, November 1976, it appears that shutting down a Surry unit would necessitate replacement of the power.
Although system load growth has been less than projected in the Surry FES, there has been no showing that the Surry power is not needed.
5-J
.e Based on our knowledge of the limited experience of the nuclear industry in large-soale, high volume chemical decontamination of reactor coolant systems, we can make the following statements.
Most importantly, decontamination would add significant expense and time delays to the repair effort, including the cost of replacement power during those time delays.
There is a degree of uncertainty about the compatibility of the decontamination fluid with materials in the coolant syste~.
The research and testing which wot.;ld be required to provide adequate assur~Nte of material cornpati b"il i ty to obtain our approva 1 to decontaminate would adversely impact on the cost and sch8dule of this repair effort.
While the lower dose rates resulting from decontamination would reduce oc~t.;;,at i ona 1 dose during the repair ope rat i ans, occupat i ona 1 radiation doses *received during the decontamination effort itself would partially offset the dose reduction.
Decontamination would not remove the radioactivity inside tubes which are plugged.
Large volumes of contaminated fluids would be produced and require processing.
That processing would incur further costs and occupa-tional dose.
In summary, we conclude that the costs of decontamination, including costs due to time delays, would outweigh the dose savings.
Therefore, the use of large-scale decontamination in th1s repair effort is not a viable option.
5.~
RETUBING OF EXISTING STEAM GENERATORS The retubing operation woDld involve (1) removing the upper or ~ome portion of the steam generator, (2) removing the lower a~sembly internals and tubes, (3) replacing the latter with state-of-the-art internals and tubes, (4) refurbishing the upper internals, and (5) welding the dome back in place.
VEPCd has estimated (Section 5.5.1.2 of Reference 1) that the cost of this operation in both dollars and occupational ~xposure would be higher than the proposed replacement of the complete lower assembly.
VEPCO further points out that shop fabrication* of new lower assemblies would provide more positive assurance that the quality of the repaired generators was acceptable.
On the,other hand, the staff is aware of recent developments by Westinghouse in the technology of in-place refurbishmeht which show some promise of reducing unit. outage and personnel expos~re below the va 1 ues for VEPCO' s proposed repair liiethod.
However, at this time we have not made a,detailed assessment of the retubing alternative.
In-pl'ace retubing may be an alternative for steam generator repairs in the future.
However,. at present this method is not an available alternative to the proposed action.
- 5. 3 REPLACEMENT OF THE ENTIRE STEAM GENERATOR For this alternative, a construction opening in the containment wall about 20 f~et wide and 40 feet high would be required, since the upper assembly of the steam generator could not pass through the existing equipment hatch.
The personnel exposure for this alternative would be about the same as for the proposed repair because essentially the same high-dose operatiohs will be required* in each case~ Elimination of the cut across the diameter of each steam*generator results in only a small saving of radiation exposure.
The capital costs are estimated to be about 15 percent higher.. ~he principal cost difference is due to an estimated additional outage of about 100 days per unit for the *alternative. This corresponds to an additional requirement 'of about $40,000,000 worth of.
replacement power during the repair of both units, calculated at the rate of about $180,000 per day of qutage per unit.
For these reasons, the staff concludes that VEPCO's proposed repair method is preferable.
- 5. 4 ALTERNATE DISPOSAL METHODS In the appendix to NUREG/CR-01992 the radiological costs of several alternative methods for the disposal of the degraded steam generators are evaluated.
The results of this analysis are summarized in Table 5.1.
It is seen that the options involving intact shipment would have the lower radiological 'costs; but intact shipment is possible only by barge and at present there i.s no licensed burial ground with facilities for off-loading an entir~ lower assembly from a barge.
The next best alternative, radiologically, would be long-term storage of the generators onsite until the reactors are decommissioned, followed by sectioning and shipment at that time.
This is the plan proposed by VEPCO.
Immediate cut-up and shipment to a burial facility would involve a substantial cost in occupational exposure, even after chemical decontamination.
Comparing Tabl~s 5.1 and 4.3, it is seen that the airborne releases from the segmenting operation would be larger than those from the rest of the repair effort.
- These include pipe cutting, removal of degraded steam generators, and replacement with new steam generators.
5-2
e Table 5.1 Steam Generator Disposal Alternatives Approximate Man-Rem per Option Steam Generator Long-terma storage (including surveillance) 10 with intact shipment a
Long-term storage with cut-up and shipment 16 Shorter-term storage with cut-up - at 5 yr 230 at 15 yr 60 Immediate intact shipment 2.4c Immediate cut-up and shipment by rail/truck - no decontamination 580 Immediate cut-up and shipment by rail/truck - with chemical decontamination 270 a30 to 40 years Approximate Airborne Release Ci per Generator Negligibleb 0.005 0.026 0.015 Negligibleb 0.042 0.010 bSince the steam generator will be sealed before it is removed from containment, no release of radioactive material is expected during the repair operation.
cEstimates for short-term storage followed by intact shipment would be only slightly larger than this, perhaps 5 man-rem.
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111 e
The two, dhposal' alternativ1es considered by VEPCO (Section 5. 5. 2. 2 of Reference 1) were immediate intact barge shi.pment and near-term sectioning for uffs i te di.sposa l.
The estimated eco.homi c and radiological'. costs are given in Table 5. 2 for tne disposal of s.ix steam generators.
Table 5.f Costs of Alternativ8 Disposal Methods (VEPCO)
Method Ons i.te Storage With Final Disposal at Decommi ss i oni.ng Intact Barge Shipruent Near-Term Secti on,i ng Cost. dollars.
1,000,000 1,200,000 to 1,500,000 1,700,000 Exposure,a man-rem 80 200 1000 to 2000 aNote that these doses are for six lower assemblies.
The estimates in Table 5.1 are for one lowerassernbly.
Accordi,ng. to the VEPCO estimates, the proposed disposal method of ons ite storage with final di sposi-ti on 9t the time of plant decommissioning should result in the least': cost in dollars and in radia-t i on 1 e~posure.
The staff agrees that the proposed disposal method costs less in radiation exp.osure than ~Jternatives availabl~' at present.
The proposed onsite storage leaves open the option of intact barge shipment in the event that a burial ground with adequate off-loading facilities becomes a va.i lab le.
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e
6.0 CONCLUSION
We have reviewed the proposed steam generator repair action and have reached the following conclusions.
(1)
The proposed replacement of the lower assemblies of the steam generators is the best available option, from both the radiological and economic standpoints, for eliminating the tube degradation problem.
(2) The one-time occupational exposure of 2070 per unit is larger than the average annual occupational exposure associated with the operation of a nuclear power plant.
However, such occupational exposures or larger exposures would be incurred in a few years by continued operation at Surry even absent the proposed action.
In the long run, the proposed action will cause occupational exposures at an operating Surry facility to be reduced on a long-term cumulative basis as well as on an annual basis.
Therefore, it does not appear that there will be a substantial increase in occupational radiation exposure caused by the work authorized.
We have reviewed the dose reduction measures to be used by the licensee and conclude that the doses would be ALARA.
We have also considered the health effects resulting from such exposure and concluded that these are not significant.
(3) lhe new steam generator design incorporates features which will eliminate the *potential for the various forms of tube degradation observed to date.
(4) The restoration would restore the generators to the condition evaluated in the FES and would result in an occupational dose saving of hundreds of man-rems per year, because there would.be a marked reduction in the amount of tube inspection and tube plugging required to keep the generators in acceptable operating condition.
(5) Offsite doses resulting from the steam generator repair will be less than those from recent plant opera-tions, comparable to doses presented in the FES, 7 and small compared to the annual doses from natural background radiation.
Therefore, the offsite doses will not be significant.
On the basis of the foregoing analysis, the staff concludes that the proposed steam generator repair will not significantly affect the quality of the human environment.
Even if it had been concluded that the absolute occupational dose of the proposed repair program would be of significant impact to the human environment, this impact is outweighed by the decrease in the long-term radiological exposure compared to what would be incurred if the facility were to operate without the proposed repairs and by the economic advantage of the proposed repair program, so we would nonetheless conclude that the proposed repair program should be implemented.
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e 7.0 FEDERAL, STATE, AND LOCAL AGENCIES TO WHOM THIS ENVIRONMENTAL STATEMENT WAS SENT This Draft Environmental Statement was sent to the following:
Advisory Council on Historic Preservation Department of Agriculture Department of the Army, Corps of Engineers Department of Commerce Department of Energy Department of Health, Education and Welfare Department of Housing and Urban Development Department of the Interior Department of Transportation Environmental Protection Agency Commonwealth of Virginia Surry County 7-1
REFERENCES
- 1.
Steam Generator Re~air Program: Surry Power Station, Unit Nos. land 2, Virginia Electric and.Power Company, August 17, 1977, and revisions dated December 2, 1977; April 21, June 2, June 13, June 30, September 1, October 25, and November 10, 1978.
- 2.
NUREG/CR-0199 9 "Radiological Ass~ssment of Steam Generator Removal and Replacement.81 G *. R. Hoenes, D. A. Waite, and W. D. McCormack, Pacific Northwest Laboratories, June 1978.
,3.
Safety Evaluation Report for the Surry Power Station Steam Generator,.
Replacement, U. S. Nuclear Regulatory Commission, December 1978.
4, Regulatory Guide 8.8 1 "Information Relevant to Ensuring that Occupa-tional Radiation Exposures at Nuclear Power Stations will be As Low As is Reasonably Achievable", (Revision 2), U.S. Nuclear R~gulatory Commi ss i en.
S.
NUREG-0482, 110ccupational Radiation Exposure at Light Water Cooled Power Reactors 1977, 11 L. J. Peck, U. S. Nuclear Regulatory Commis-sion, November 1978.
- 6.
"Annual Operating Report of Surry Power Station for 1977, 11 Virginia Electric and Power Company.
..:.:_:_:_:_._.7:
"Final Environmental Statement related to the operation of*Surry Power Station, Unit 2, 11 U. S. Nuclear Regulatory Commission, June 1972.
_S,
- Regulatory Guide 1.113, "Estimating Aquatic Dispersion of Effluents from Accidental and Routine Reactor Releases for the Purpose of Implementing Appendix l," U. S. Nuclear Regulatory Commission.
- 9.
- 13.
Regulatory Guide 1. 111, ".Methods for Estimating Atmospheric Transport and Dispersion of Gaseous Effluents in Routine Releases from Light-Water-Coo 1 ed Reactors. (Revis ion 1), U. S. Nuc:l ear Regulatory
.Commission.
NUREG/CR-0130, "Technology, Safety and Cost of Decommissioning a Reference Pressurized Water Reactor, 11 R. I. Smith, G. J. Konzek and W. £. Kennedy, Jr~_e Pacific Northwest Laboratories, June 1978.
Regulatory Guide 1.11)9, "Calculation of Annual Doses to Man from.
Routine Releases of Reactor Effluents for the Purpose of Evaluating Compliance with 10 CFR Part 50, Appendix ! 1 11 (Revision 1), U.S.
Nuclear Regulatory Commission.
NUREG-0367, "Radioactive Material Released from Nuclear Power Plants (197"6)/1 T.R. Decker, U.S. Nuclear Regulatory Com:nission, March l97S.
NCRP No. 45, "Natural Background Radiation in the United States,"
National Council on Radiation Protection and Measurements>> 1975.
"The Effects on Populations of Exposure to Low levels of.
Ionizing Radiation", (BEIR Report}~ National Academy of Sciences, November 1972, Reprinted July 1974.
e e
APPENDIX A MEMORANDUM AND ORDER BY THE U.S. NUCLEAR REGULATORY COMMISSION IN THE MATTER OF VIRGINIA ELECTRIC AND POWER COMPANY (SURRY POWER STATION, UNITS 1 AND 2)
e UNITED STATES OF AMERICA NUCLEAR REGULATORY COMMISSION COMMISSIONERS:
John F. Ahearne, Chairman Victor Gil insky Richard T. Kennedy Joseph M. Hendrie Peter A. Bradford In the Matter of VIRGJNIA ELECTRIC POWER CO.
(Surry Nuclear Power Station, Units 1 and 2)
For Relief Under 10 CFR 2.206
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MEMORANDUM AND ORDER Docket Nos. 50-280 50-281 The*Commission has before it for sua sponte review three decisions by the Director of the Office of Nuclear Reactor Regulation on petitions1' filed under 10 CFR § 2.206 involving the steam generator repair at the Surry Nuclear Power Station.
On January 29, 1980, the Commission, pursuant to 10 CFR § 2.206{c)(l),
took review of the three decisions on the issue of the need for an environmental impact statement.. regarding the proposed repair.
1/
The three petitions are from the North Anna Environmental Coalition {filed December 29, 1978; denied February l, 1979); the Environmental Policy Institute (filed February 20, 1979, denied April 4, 1979); and the Potomac Alliance, Citizens Energy Forum, Inc., Truth in Power, Inc., and the Virginia Sunshine Alliance (filed April 18, 1979, denied October 24, 1979).
2
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""h 21. d th l
. d d
The primary issue presente by~ e repair,-
an e so e issue cons, ere on the merits in this CofiiiTiission review, is whethe*r the NRC's action in approv-ing the repair is one 11 signific3ntly affecting the quality of the human environ-ment11 for purposes of the Natio:-.a1 Environr.iental Policy Act (NEPA), 3/ and there-fore one that requires an environmental impact statement.
This admittedly vague I
test, and the lack of definitive criteria that can be used in applying it, leaves the Commission and its Staff with a difficult decision in many cases..
The circumstances of this case p~esented the Director with just such a difficult.
decision.
Our review has focused on the occupational radiation exposure that the repair program will entail because W= believe :hat this adverse environmental impact is the only one associated with the repair program that might be considered significant.
We have carefully exar.iined the Dir~ctor 1 s Decisions and the bases therefor, and are. unable to determine fro~ the data. and arguments presented by the Director whether the occupational radiation exposure involved here is signi-
,*1.
ficant.
The Director's Decisions rest essentially on a comparison of the impact
.. ;*?.. '
of the radiation exposure resulting from the repait with the net savings in total occupational exposure resulting from operation using repaired steam generators y
When this issue first aroseg both units at Surry were the subject of the petitions. At this point however, repairs at Unit 2 are essentially completed and the repaifs at Unit 1 are scheduled to begin in June of 1980.
Hence, the need for an environmental irr.pact statement for the Unit, 2 repairs i~ moot.
However, the issue of the need for a statement for the Unit 1 repair is very much alive and is the focus of this Co;.rnission review.
The National Environ~ental Policy Act of 1969, Pub. L. No.91-190, 83 Stat.
852 as amended by Pub. L. 94-83, 89 Stat. 424, 42 U.S.C.
§§ 4321 et~-
3 instead of defective ones, and a comparison with the incidence of cancer for the worker population due to causes other than the repair at Surry.
The first com-parison is relevant to the question whether the expected benefits of the action outweigh the environmental costs, which is distinct from the question whether the expected environmental impact of a federal action is sufficiently great to require an impact statement.
Even if on balance the result of the Federal action is beneficial, the proper criterion on which to base the decision whether to pr~pare an EIS is the significance of the action. 4/ Hence, the.fact that the occupational exposure at Surry (2070 man rems for the repair at each unit) is expected to be less than the occupational exposure resulting from continued operation with defective steam generators over a period of four years is a valid consideration in assessing the merits of the repair once the requirements of
~EPA have been satisfied, but has no bearing in determining the threshold ques-tion of the "significance" of the exposure and the attendant decision whether to prepar~ an environmental impact statement.
The Director 1 s second* basis, comparing the occupational exposures to the number of worker deaths due to cancer from risks unrelated to the repair, neces-sarily entails a judgment regarding the significance of these other risks.
More specifically, it implies the proposition that these*other risks are either not significant or that a small percentage of them is not significant. However, nothing in the Director 1s Decisions establishes this proposition. Thus the comparison, without more, does not enable us to determine whether the exposures here are significant.
4/
See Regulations For Implementing The Procedural Provisions of NEPA, 40 CFR 1508.27(b)(l).
e e
4 Given this, and 9iven the controversy in the scientific co~~~nity as :o the effects of such exposures, we are unable to determine whether the ~nviron~ental*
impacts here aresignificant.
Therefore, we believe that the prefera~l~ ::~-t~
of action in the circumstances of this case is to prepare an environ~en:2.1 impact statement on the repair.
Accordingly, we hereby direct the Staff to expeditiously prepare anJ an environmental impact statement on the proposed repair at Unit 1.
Chairman Ahearne and Commissioner Hendrie dissent from this decisi:J:i.
It is so ORDERED.
For the Co~~ission l~~
s,:.:,;...;EL J.l C:-iiU~
S C
ecret2.ry 01 tff o;;;n1ss1on Dated at ~ashinaton, D.C~,
this ~
da: of f\\arch, 1980.
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