ML20045C148
| ML20045C148 | |
| Person / Time | |
|---|---|
| Site: | Yankee Rowe |
| Issue date: | 06/17/1993 |
| From: | Thayer J YANKEE ATOMIC ELECTRIC CO. |
| To: | Fairtile M NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM), Office of Nuclear Reactor Regulation |
| References | |
| BYR-93-044, BYR-93-44, NUDOCS 9306220133 | |
| Download: ML20045C148 (10) | |
Text
MANKEEATOMCE ECTMCCOMPANY
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580 Main Street. Bolton, Massachusetts 01740-1398 June 17,1993 BYR 93-044 U.S. Nuclear Regulatory Commission Document Control Desk Washington, DC 20555 Attention:
Mr. Morton Fairtile Senior Project Manager Non-Power Reactors and Decommissioning Project Directorate Division of Operating Reactor Support
References:
(a)
License No. DPR-3 (Docket No. 50-29)
(b)
Letter, M. Fairtile, U.S. Nuclear Regulatory Commission (NRC) to J. Grant, Yankee Atomic Electric Company (YAEC), dated June 16,1993 (c)
Letter, J. Thayer, YAEC, to M. Fairtile, NRC, dated April 23,1993 (d)
NUREG-0586, Final Generic Environmental Impact Statement on Decommissioning Nuclear Facilities, dated 1988 (c)
NUREG/CR-130, Technology, Safety and Costs of Decommissioning a Reference Pressurized Water Reactor Power Station, dated June 1978 (f)
Letter, M. Fairtile, NRC to G. Papanic, YAEC, dated July 16,1987 (g)
Letter, D. Crutchfield, NRC to J. Kay, YAEC, dated March 30,1984
Subject:
ACTIVITIES PRIOR TO DECOMMISSIONING PLAN APPROVAL -
REQUEST FOR ADDITIONAL INFORMATION
Dear Mr. Fairtile:
In Reference (b), the Nuclear Regulatory Commission (NRC) requested clarification of material presented in Reference (c) relating to the application of the NRC guidance criteria for conduct of component removal activities prior to approval of the Yankee Nuclear Power Station (YNPS) Decommissioning Plan. The requested information is presented in the following responses.
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U.S. Nuclear Regulatory Commission June 17,1993 Page 2 1.
Estimate the total occupational and public radiation exposures which will result from the early component remoul project. Catecorize these doses as to whether they result from the exposures durine component removal. release of radioactive material to the environs durine component removal. or from transportation of these radioactive components. Provide a preliminary estimate of the total occupational and public exposures which will result from the entire decommissionine process: (a) with the proposed larne component removal procram in your April 23.1993 letter, and (b) assumine these same larce components are left in place until the year 2000. Provide a comparison of these exposures with the exposure estimates of the Generic Environmental Impact Statement (GEIS) NUREG-0586.
The NRC as concluded in NUREG-0586, " Final Generic Environmental Impact Statement on Decommissioning," (GEIS), (Reference (d)), that both Immediate Dismantlement (DECON) and SAFSTOR are reasonable alternatives for decommissioning power reactors, and that the environmental impact of decommissioning nuclear facilities is similar to or less than that during construction and operation. Therefore, verifying that a proposed decommissioning activity is bounded by the operational environmental impact analysis is sufficient to demonstrate compliance with the GEIS and with the NRC guidance criteria that the activity will not cause a significant environmental impact not previously reviewed.
Ocetmational Dose Assessment Removal of the YNPS steam generators, pressurizer and reactor vessel internals are legitimate decommissioning activities under the definition of decommissioning in 10 CFR 50.2. Due to the timing of these activities, they can be classified as falling under the DECON decommissioning alternative described in the GEIS.
The GEIS has characterized the occupational exposure associated with DECON as equivalent to that experienced during normal refueling and maintenance outages.
At YNPS, the average exposure during the years between 1980 and 1990 with refueling outages is 280 person-rem / year, with a maximum exposure of 474 person-rem reported in 1982. The total occupational exposure for all component
.i removal activities is currently estimated to be 350-400 person-rem. Actual doses i
should be lower through implementation of aggressive ALARA practices.
Individual worker exposure will continue to be well below regulatory limits.
The total exposure estimates to complete YNPS decommissioning are currently being developed and will be submitted to the NRC in the YNPS
l U.S. Nuclear Regulatory Commission June 17,1993 Page 3 Decommissioning Plan. However, they are expected to be within the ranges identified in the GEIS For the DECON case, the total occupational exposure estimate in the GEIS is in the range of 1100-1400 person-rem. If the plant is dismantled in the year 2000, the total occupational dose to complete the dismantlement would be reduced to approximately 40% of the above, or 440-560 person-rem. (This assumes the primary isotope contributing to occupational exposure is Co-60.) Adding the occupational exposures for preparation for SAFSTOR and exposure during the SAFSTOR period, the total is estimated to be 800-1000 person-rem.
The NRC concluded in the GEIS that both the DECON alternative and the 60 year SAFSTOR alternative are acceptable for decommissioning a nuclear power station. The occupational exposures as reported in Table 4.3-2 of the GEIS for these alternatives differ significantly,1200 and 300 person-rem respectively. The exposure for CRP activities would be minimal for the 60 year SAFSTOR alternative. However, the GEIS concludes that the " larger annual occupational radiation dose, which is similar to the routine annual dose from plant operations, is considered of marginal significance to health and safety." Therefore, if CRP occupational exposures are maintained within those presented in the GEIS for the DECON alternative, as well as the historical annual operational exposures, the CRP occupational exposures are acceptable, regardless of the SAFSTOR storage duration.
As indicated in the GEIS, the DECON exposures are offset by the advantages of having experienced plant decommissioning staff, lower overall costs and sooner release of the facility for unrestricted use. Although the YNPS site may not be released until the year 2002, as currently planned, the safety benefits of having experienced staff complete the steam generator and pressurizer vessel removals, reactor vessel internals segmentation, and disposal activities, combined with the economic incentive of completing these activities now, are significant.
Assessment of Releases to the Environment During CRP Figures 1 and 2 summarize the YNPS annual effluent dose reports from 1984 to 1992. It can be seen that with the permanent shutdown of the plant for over eighteen months, gaseous effluents have been virtually eliminated. Liquid effluent releases have also been significantly reduced. This trend is expected to continue throughout the Component Removal Project (CRP) for the following reasons:
Liquid waste generation will not be increased above levels for routine e
shutdown operations. Operation of the liquid waste processing system will be unchanged throughout the project, with the exception of processing the
U.S. Nuclear Regulatory Commission June 17,1993 Page 4 Shield Tank Cavity water after reactor vessel internals segmentation activities. Following internals segmentation, the Shield Tank Cavity water (150,000 gallons), will be processed through the radwaste evaporator. The evaporator distillate will be collected, sampled and discharged in accordance with existing plant procedures. The volume of liquid processed during the CRP will be similar to that volume processed in 1992, where the majority of the plant's radioactive systems, including the reactor coolant and primary auxiliaries, were drained, and the liquid processed through the radwaste evaporator.
No new liquid or gaseous effluent pathways will be created. All potentially e
radioactive liquids will be directed to existing plant collection and processing systems. Potential airborne particulate effluents will be directed to the plant filtered exhaust system for processing and monitoring.
e Direct radiation doses will remain well within current limits. Movement of materials onsite will be controlled to limit direct exposure at the site fence.
Special administrative controls and/or temporary shielding will be utilized to minimize direct radiation exposure during transit of radioactive materials onsite.
i The Radiological Environmental Monitoring Program will continue to be implemented during the current and future decommissioning activities to verify the effectiveness of systems and procedures for control of releases of radioactivity from the plant, and to measure environmental levels of radioactivity for impact assessment.
Transportation Dose Assessme.nt The transportation of radioactive material generated during CRP for offsite i
disposal will be similar to routine shipments made during the 31 years of plant operation. The packages will continue to meet all applicable NRC and Department of Transportation regulatory requirements. Approximately thirty-six shipments of radioactive waste will be made during the project. The shipments will be comprised of ten dry active waste shipments, twenty-four irradiated hardware cask shipments, and two shipments carrying the steam generators and pressurizer. Using the transportation dose data and assumptions presented in Reference (c), and a transportation distance of 1100 miles per shipment, the maximum projected public dose from transportation of waste generated during 1
CRP is estimated to be 760 millirem.
1
U.S. Nuclear Regulatory Commission June 17,1993 Page 5 The transportation dose reported in the GEIS for the DECON alternative is approximately 21 person-rem. This is based on 1363 shipments over a distance of 500 miles. The total number of shipments from YNPS for the entire decommissioning process is expected to be less than 500, over a distance of 1100 miles each; the total projected transportation dose is approximately 11 person-rem.
2.
Confirm in the individual 10 CFR 50.59 analyses, which will be performed for the component removal project cumulative occupational and public radiation dose estimates for all component removal activities will be combined with the dose estimates for the remainine decommissionine activities. and included in the determination as to whether the cumulative resultine environmental impacts exceed those analyzed in the GEIS.
The cumulative occupational, transportation and plant effluent doses will be documented and incorporated into the total decommissioning dose estimates in the YNPS Decommissioning Plan. Based on the CRP exposure estimates discussed in this letter, both the CRP and Decommissioning occupational, transportation, and effluent doses will be within the plant operational experience base, and within the GEIS guidelines.
3.
Provide the rationale for the exclusive use of the fuel handline accident, rather than previously evaluated accident such as the release of caseous or liauid emuents, as a benchmark in the 10 CFR 50.59 analysis process which is used to determine whether the probability of occurrence or consecuences of accidents or couipment malfunctions is increased.
Although the discussion in Reference (c) focused on the material handling events associated with the potential drop of the steam generator and pressurizer vessels being removed during the current project, YAEC stated that the evaluation will consider all potential events which may result in uncontrolled release of radioactive material or uncontrolled exposure to radiation. The potential mechanism for release or specific pathway to the environment and the resultant radiological consequences will be dependent upon the particular event under consideration.
The engineering design change process described in Reference (c), which includes j
a multi-discipline review and approval process, has been demonstrated to be very effective in identifying and evaluating the appropriate range of potential interactions. transients and accidents and assessing their consequences. This process will continue in the future for plant modifications.
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U.S. Nuclear Regulatory Commission June 17,1993 Page 6 4.
Clarify how the inclusion of earthouakes and fire hazards will be address in future 10 CFR 50.59 analyses.
Fire Hazards As indicated in Reference (c), YAEC will continue to utilize the same engineering design change process employed during plant operation and currently employed by YAEC in its services to operating nuclear power plants. YAEC will continue to address the impacts of proposed modifications on plant design and operational features as well as licensing design bases. This includes a review of potential impacts of proposed modifications on the following design features:
i e fire detection and suppression equipment, and systems e fire barrier maintenance and control e personnel training and qualification programs e fire protection program and procedures e control of transient combustible material All modifications are designed, reviewed, and implemented to ensure that adequate fire protection features, programs and procedures are maintained. This includes review and approval by the corporate fire protection specialist as well as i
review by the Plant Operations Review Committee.
Seismic t
Similar to the fire hazards evaluation described above, proposed plant modifications are reviewed to determine the potentialimpact on the seismic design basis of plant systems, structures, and components in the permanently defueled condition.
In the permanently defueled condition, only the Spent Fuel Pool and adjacent structures have a seismic design basis. Since fuel has been removed from the reactor and the Possession Only License prohibits moving fuel into the containment or operating the reactor, those systems, structures, and components once needed to achieve and maintain safe reactor shutdown following a seismic
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event no longer require seismic qualification.
The Spent Fuel Pool structure, fuel transfer chute, and the overhead crane structure were analyzed as part of the NRC's Systematic Evaluation Program. As discussed in the Staff's safety evaluation report, (Reference (f)), YAEC's analysis r
and results were determined by the Staff to be acceptable. The spent fuel storage racks and related structural supports inside the Spent Fuel Pool were also
U.S. Nuclear Regulatory Commission June 17,1993 i
Page 7 designed to the same NRC Spectrum Seismic event, and reviewed and approved by the Staff (Reference (g)). Other seismically qualified adjacent structures, identified in Reference (f), located in proximity to the Spent Fuel Pool and whose failure may impact the integrity of the pool, include the Vapor Container / Reactor Support Structure, Primary Vent Stack and the Elevator Structure.
Any future proposed plant modifications o the Spent Fuel Pool and adjacent structures will be designed and implemented to ensure that the design basis is maintained.
Conclusion a
We trust that the information provided in this letter, along with the detailed information transmitted to NRC in previous licensing submittals, satisfies NRC's needs to better understand how YAEC will implement the NRC guidance criteria for the conduct of pre-Decommissioning Plan activities. In that respect, if you should have any questions regarding the information provided in this letter, please contact Ms. Jane Grant i
immediately so that we can respond to your needs in a timely manner.
i Sincerely, i
i YANKEE ATOMIC ELECTRIC COMPANY
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Jay K. Thayer Vice President and Manager of Operations i
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U.S. Nuclear Regulatory Commission June 17,1993 Page 8 COMMONWEALTH OF MASSACHUSETFS)
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Then personally appeared before me, Jay K. Thayer, who, being duly sworn, did state that he is a Vice President and Manager of Operations of Yankee Atomic Electric Company, that he is duly authorized to execute and file the foregoing document in the name and on behalf of Yankee Atomic Electric Company and that the statements therein are true to the best of his knowledge and belief.
Kathyrn GatesF Notafy Public My Commission Expires 1/24/97 T
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R. Dudley, NRC,NRR E. Kelly, NRC Region I NRC Document Control Desk t
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Figure 1 Yankee Atomic Electric Company Maximum Offsite Doses for Gaseous Effluents 1E+2 1E+2
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