ML20212K919
| ML20212K919 | |
| Person / Time | |
|---|---|
| Site: | Peach Bottom  |
| Issue date: | 02/28/1987 |
| From: | PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC |
| To: | |
| Shared Package | |
| ML20212K808 | List: |
| References | |
| NUDOCS 8703090456 | |
| Download: ML20212K919 (29) | |
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ENVIRON 4 ENTAL REPORT OF THE CURRENT DEC0tNISSIONED STATUS OF THE PEACH BOTTOM UNIT NO.1 4
i'i Philadelphia Electric Company Docket No. 50-171 February, 1987 7 3090 k5 p P
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I. StM%RY This document addresses the envirorynental aspects of the current deconmissioned status of the Peach Bottom Nuclear Station No.1. The station was a 40 megawatts electrical, helltm cooled graphite I
moderated reactor designed by the former General Atomics Division of General Dynamics Corporation. The balance of plant, which was designed and constructed by Bechtel Corporation, utilized a Westinghouse Electric i I
Corporation turbine generator for electric generation. Philadelphia Electric Company was the operator of the plant, and one of the fifty three utilities that financed its construction through the High Temperature Reactor Development Association. Construction of the plant was begm on February 23, 1962, and conmercial power generation was I achieved in June 1967. The plant was shut down October 31, 1974 ,
I defueling was completed in June 1975, and decomnissioning activities which f resulted in the present facility status were completed in February 1978.
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? The decomnissioning operation is detailed in a Deconmissioning Plan (ref.1) which was submitted to the U. S. Atomic Energy Comnission
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for approval simultaneously with a request for authorization to amend Provisional Operating License NO. DPR-12 to possess-but-not-operate status. The deconmissioning activity entailed removal of all radioactivity outside of an Exclusion Area, within which remains the containment f
building, the fuel storage pool and liquid waste system basement. All spent fuel was removed from the reactor vessel and returned to its owner where it is currently being stored.
Similarly, areas outside the Exclusion Area which contained surface contamination were decontaminated to levels less than those
! specified in USNRC Regulatory Gulde 1.86 Termination of Operatino Licenses for Nuclear Reactors, dated June 1974. -Within the Exclusion Area,-surface decontamination was performed to the extent feasible.
'The liquid waste system basement was fully decontaminated, except for 11 embedded pipes, while the containment building and the fuel storage pool were partially decontaminated. Facilities within the Exclusion Area are subjected to periodic Inspections in accordance with the Unit
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1 Technical. Specifications. A radioactivity Inventory estimate Indicates that approximately 0.2 megacuries of activity remain within the Exclusion Area as of January 1987. This radioactivity is connposed' mainly of neutron activation products within the reactor vessel and fixed contamination within the primary coolant system. The containment building is vented through an absolute filter to maintain pressure equalIbrlun wIth the environment.
During the decomnissioning operation appropriate measures were taken to prevent the spread of radioactivity. All contaminated solid material which was removed from the site was shipped to an approved burial ground. Shipments conformed to all appilcable standards and j regulations. Liquid and gaseous radioactive wastes were processed on-site and released in accordance with the requirements of the Plant Technical Specifications. At the completion of all work associated with the decomnissioning, a final inspection and survey of the plant was perfonned to assure that all detectable contami'ation outside of the Exclusion Area had been removed, and that the status of all systems within the containment building and fuel storage pool structure were in accordance with the Decomnlssioning Plan. The f'nal inspection and survey were published as part of the Decomnissioning Final Report (Ref. 2). The decomnissioning of PBAPS Unit No. I did not result in
any significant adverse environmental Impact, nor will the continued
- safe storage period (SAFSTOR).
The continued SAFSTOR involves only a radiological survey of the i
Exclusion Area on a semlannual basis. There is no operating equipment, l
no pressurized vessels and no liquids or gases present. There is minimal fire hazard and all radioactive material is fixed. Therefore, continued SAFSTOR imposes no significant additional impact on the environment. The aesthetic nature of the site is not significantly changed. The most prominent structure, the containment building was not removed.
In this assessment, three alternatives which cover the spectrun of deconmissioning choices are considered from the standpoint of environmental Impact. These alternatives are:
- 1. DECON-Total Removal
- 2. ENTOMB-On-Site Entcmbment
- 3. SAFSTOR-Deconmissioning It is our conclusion that neither the DECON (Total Renoval)
Alternative nor ENTOMB (On-Site Entcmbment) Alternative would result in a significant reduction in the environmental impact compared to the continuance of the SAFSTOR (Deccmnissioning) Alternative. This reason, as well as the radiological advantages associated with delaying ultimate dismantling of the unit, provides the basis for the choice of the SAFSTOR Plan as the preferred alternative for Peach Bottom Unit No. 1.
II. BACKGROt10 A. Plant History The Peach Bottom Unit No.1 is located in Peach Bottcm
. 1 Township, York County, Pennsylvania, on the western shore of the Conowingo Pond at the mouth of Rock Run Creek on a site owned by Philadelphia Electric Company. The City of Lancaster with a population of approximately 85,000 in 1980 is the nearest population center and is located approximately 19.4 miles north of the plant site. The nuclear plant was a prototype 40 Ne high temperature gas-cooled reactor which used hellun as the primary coo 1Ing fluid.
The plant contained a reactor with 804 fuel elements surrounded by a graphite reflector, and a reactor coolant system of two parallel looos, each containing a centrifugal type ges circulator, three quick closing stop valves and a steam generator. At 100% power conditions, the coolant, hellun, exited the core at an average outlet temperature of 1318 F and returned to the core after heat removal in the steam generator at a temperature of 652 F . The heat was transferred in the steam generator to a working fluid, water.
The water was converted to superheated steam at 1000 F and a pressure of 1450 psig. The steam produced was used to drive a 3600 rpm turbine generator for electrical energy. production.
The Peach Bottom Unit 1 fuel elements contained fuel compacts consisting of uranlun and thoriun in the form of carbides uniformly dispersed as particulates in a graphite matrix.
Each particle was pyrolytically coated with a dense carbon that served to increase retention time of fission products during reactor operation. Consequently, most of l the fission products are retained within the fuel particle assuring low primary coolant system radioactivity levels.
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Each fuel' element was Internally purged directly to a purification system where the fission products were delayed to permit radioactive decay of the short-lived Isotopes or removal of.the long-lived Isotopes as gaseous radwaste. The purification system consisted of a series of charcoal traps that were removed during the decomnission program and shipped to a IIcensed burial site.
These unique designs features (pyrolytic coated fuel particles and a fuel purge / trapping system) resulted in low primary system contamination levels, icw radioactive waste release rates, and minimal plant background radiation and personnel exposure levels.
Construction of Peach Bottom Unit I was begun In 1962. Initial criticality was attained on March 3, 1966. In June 1967 the plant went into connercial operation. Philadelphia Electric shut down the plant on October 31, 1974 and comnenced deccanissioning the plant at that time. Deconnissioning activity was completed in February 1978 at which time the plant was put in SAFSTOR. The decision to decmmission the plant was based on the successful camletion of the development program to demonstrate viability of the HTGR concept and the high I
cost of upgrading the plant to meet existing AEC/NRC safety I
criterla in order to obtain a full-term operating Ilcense. The operating IIcense extension expired on Jme 24, 1974. The license was revised to possess-but-not-operate status on July 14, 1975.
B. Present Decomnissioned Status of Plant The decomnissioning of Peach Bottom Unit i reduced the controlled access area (Exclusive Area) to include only the i reactor containment, the spent fuel pool building and the I l
liquid waste system basement. The Exclusion Area is bounded ;
by a chain-link fence and padlocked doors to prevent l l
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uncontrolled access. The areas within the Exclusion Area l 1
were decontaminated where feasible. -All remaining radiation areas of greater than 1.0 mr/hr and all areas which remain contaminated, are sealed by locked gates and/or gratings and are posted as Controlled Areas (signs Indicate the radiation / contamination levels in the area). More than 99.9 percent of the estimated 0.2 megacurles of radioactive material currently left within the Exclusion Area are the neutron activation products contained in the reactor vessel materials.
The final status of the plant is as follows:
- 1. All fuel was shipped off-site'.
- 2. Control rods were deactivated and locked in place in the reactor core.
- 3. Core spacers, reflector blocks and reflector elements were left in place in the reactor vessel .
- 4. Liquids and all pressurized gases were removed from systems in the Exclusion Area. Liquid and gaseous wastes were processed and released in accordance with established procedures and regulations.
- 5. Flamnable material was removed from the containment with the exception of the graphite material within the reactor vessel which was sealed within the primary system boundary.
- 6. The primary system was closed completely. All openings made as a result of the Post Operative Sampilng Program were sealed by welding caps or metal plates over the
openings. The sampilng program was conducted by General Atomic Corporation to validate generic HTGR design' codes and predictions by comparison of actual to predicted . thermal, fission product and material behavior.
The main circulator shaft penetrations'were sealed.
- 7. All fluid and gaseous penetrations into the containment vessel were cut, capped and welded shut.
'8. Major equipment in the containment such as fuelhandling '
equipment was retired in place after external decontamination.
- 9. All monitoring systems were secured.
4' 10. All utility service to the containment with the exception of Ilghting was pennanently secured.
- 11. The containment structure is vented through an absolute filter assently to the atmosphere in order to prevent temperature t
Induced pressure changes with respect to the environment.
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- 12. All contaminated materials and systems outside the Exclusion Area were decontaminated or shipped off-site fcr IIcensed burial.
- 13. Offices, laboratory spaces, the control- room at other areas outside containment were surveyed, decor.taminated as necessary, and released for unrestricted use.
- 14. Ancillary facIllties and balance of plant were retired in place, dispositioned of as scrap or sold.
- 15. A survelliance program was implemented after conpletion of the deconmissioning operation. The conplete details of the deconmissioning work done and the SAFSTOR status i
of PBAPS Unit I were published in the "Deconmissioning L Peach Bottom Unit 1 Final Report," July 1978 (Ref.2).
- 16. Missile beams were positioned over the reactor vessel l
and containment building crane was disconnected.
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III. ASSESSMENT A. Environment inpact The proposed action to continue SAFSTOR of the Peach Bottom Unit No. I will not cause a significant environmental inpact.
The considerations that lead to this conclusion are as I follows:
Radioloalcal Releases To The Environment During SAFSTOR More than 99.9 percent of the residual radioactivity
- remaining is due to neutron activation products contained in the reactor vessel materials. Most of the other by-product
- material is fixed contamination on the internal surfaces of
[ the primary coolant piping and steam generators. Further,
- piping penetrations, except for the filtered vent installed in the equipment door, into the containment structure have been sealed. During the Deconmission Program, radioactive liquid and gases were removed from the site, thus eliminating any potential sources or transport mechanisms for releasing radioactivity to the environment. For these reasons there is a very low probability of by-product material migration and release to the environment. Inspections performed to date have confirmed the absence of by-product material migration. Only a small fraction of the remaining deposited radioactivity would be released even in the event of a flood collapsing the reactor containment (Ref. 5). The pubile dose impact of such an event would be insignificant.
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Accidents and Natural Phenomena Occurrences
- During the Decomnission Program, nuclear fuel and radioactive Ilquids and gases were removed from the site. Consequently, the probability of a Design Bases Accident or lesser nuclear 4 related accident has been eliminated during the SAFSTOR phase.
The numerous physical barriers surrounding the residual reactivity preclude exposure to the pubile and' plant personnel.
The only potential high radiation area in the Unit 1 facility is the cavity containing the reactor vessel. The cavity is enclosed by eight foot thick concrete walls, and all reactor vessel access ports have been sealed with shleid plugs and bilnd flanges. Three foot thick concrete beans have been j positioned over the sealed reactor vessel access ports. The refueling floor crane needed to lift the beams has been mechanically and electrically deactivated.
Most of the residual radioactivity outside the reactor vessel cavity resides in the primary coolant piping and steam generators as internal surface contamination (approximately 20 curies). The rooms enclosing these components have been sealed.
All of these areas are further enclosed by the locked containment building and exclusion area fence.
Flanmable material with the exception of the graphite contained within the reactor vessel was rerreved from within the controlled areas of the plant during deconmissioning.
Radioactive systems outside of the Exclusion Area of the deconmissioned site were decontaminated or removed from the site to a burial ground. Areas within the Exclusion Area were decontaminated to the extent feasible.
Thus, the potential impact upon the environment due to accidents and natural phenomena occurrences such as floods, fires, earthquakes is significantly lower than such potential impacts of an operating plant. During SAFSTOR, a semlannual radiological and physical inspection of the Exclusion Area and its barriers is performed to assure that the facility will have no impact on the environment.
Noise and Traffic During SAFSTOR the noise level and traffic density at Unit No I site will be minimal. The vast majority of traffic is due to the use.of the Administration Building in support functions for Unit Nos. 2 and 3 and is not associated with the deconmissioned facility. Such levels of traffic and noise are 1
significantly less than those being experienced at the site of Peach Bottom Unit Nos. 2 and 3 due to power production activities. The overall effect upon the environment of the area is insignificant.
Visual Aesthetics The change in environmental impact during SAFSTOR will be insignificant since the containment structure and other major buildings will not be removed.
B. Adverse Environmental Effects During SAFSTOR there will be continued restriction of publIc access to the site. However, the impact of the restricted public access is not a significant factor due to the close proximity of Peach Bottom Unit Nos. 2 and 3 which also restrict pubile access to this area.
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C. . Relationship Between Short Term and Long Term Productivity The SAFSTOR condition of Peach Bottom Unit No. I has returned a portion of.the present site to a condition that does not restrict its future use. The Exclusion Area which includes the containment structure, the spent fuel pool building and 4
the 11guld waste system basement will not be returned to unrestricted use in the near future. However, this land could'be returned to unrestricted use, if required, at a later date by removal of the equipment within the Exclusion Area, removal of all above grade structures and backfill of the land. Economic considerations and the desire to Ilmit radiation exposure of personnel who are to acconplish the
' DECON-Total Removal are factors which should be considered in evaluating the balance between the advantages of land utilization and the cost of making this land available. In the case of the Peach Bottom Unit No. 1 site, the higher radiation exposure which would be sustained by construction i
personnel and the total dollar outlay In removing the radioactive material from the Exclusion Area, are not countered by any advantage galned by unrestricted use of the '
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small area of land due to its proximity to Units 2 and 3.
Radioactive decay of this radioactive material over a period of 40 years will reduce the economic and radiological
- penalties which are required for full release of this land in the future. In addition, deferral of final decontamination and dismantilng would benefit from technological improvements
! over the next several decades in areas of robotics, decontamination, and equipment disasserrbly techniques. These
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advanced techniques would further reduce radiation exposures and radwaste.
D. Irreversible and Irretrievable Conmitments of Resources The SAFSTOR condition of Peach Bottom Unit No. 1 does not entall' Irreversible and irretrievable conmitments of
. resources.- The significant resource to be considered is the land within.the site. Even though the'1and wiji'not be returned to unrestricted use in the near future, the land could be made available at a later time by removal 'of the above grade containment structure, radioactive equipment within'the containment,_and fuel storage pool, and i
restoration of the natural grade of the land.
E. Alternatives
-1. Backaround In the deconmissioning of a nuclear plant there is a spectrum of choices available for the final
- deconmissioned status of the plant. Three possible choices which cover the spectrun of alternatives available have been considered in arriving at the reconmended decmmissioned status. Each of these choices are discussed below in this section.
- a. DECON Alternative This alternative requires the total off-site removal of all radioactive materials. The facility license would be terminated and the site would be released for unrestricted use. Under this alternative there are two sub-options. The site can be totally razed and backfilled, or the site can be left intact with the containment, spent fuel t-
building, and 11guld waste system roan remaining, but with all radioactive material and radioactively contaminated surfaces removed.
Both sub-options require the removal of all radioactive
[ material and the removal and/or decontamination of radioactivity contaminated equipment and structures.
This option has been reviewed previously and found to be less desirable than SAFSTOR (Ref. 5).
A major effort under the DECON option is the complete removal of the reactor vessel and Internals.
Because of its size and Induced radioactivity, the reactor vessel would have to be shipped in sections in ccmnercially available licensed shipping casks to a licensed burial site.
All remaining contaminated parts of the plant would be decontaminated or runoved fran the site to a burial ground. Concrete surfaces such as the biological shleiding and the spent fuel pool would require removal of the contaminated concrete and shipment to a burial site. Further decontamination and/or removal of other plant structures and surfaces would be determined by smear samples and core borings. All contaminated equipment and piping within the containment would be removed or decontaminated to acceptable levels. Under the sub-option of complete removal of all site structures, the containment building, spent
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fuel building, and portions of the auxillary-building would be completely removed. Backfilling of the land would be required in order to restore the area. The office and maintenance shop building would be left intact for the continued use of Peach l Bottom Unit Nos. 2 and 3 support activities. This sub-option would restore the site as nearly as possible to its natural state and the backfilled land could be utilized for other limited purposes.
This alternative would not require a long term inspection and surveillance program. The principal disadvantage of this alternative is the exposure of personnel which would result from the removal of highly radioactive sections of the reactor vessel and internals. In addition, disposal of activated components would be difficult since there are currently no sites available for deep geologic disposal.
DECON would include the cutting of the reactor vessel, primary coolant piping and steam generators for shipment to a licensed burial site. There is a potential for a limited release of airborne particulate material to the environment during this cutting process.
The advantages of DECON over SAFSTOR as discussed in NUREG-0586 (Ref. 7) are minimized because PBAPS Unit 1 is within the SITE BOUNDARY of PBAPS Units 2 and 3. Therefore, the site cannot be used for
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7 other purposes, nor is it extremely valuable. Due to these considerations with only minor improvements in land use and aesthetics, this alternative was rejected,
- b. ENTOMB Alternative This alternative would permit entantment of all non-flanmable solid radioactive material. All graphite including the reactor blocks would be removed from the reactor vessel and the vessel would be filled with some material which would reduce the free voltsne. Concrete plugs would be poured in all personnel, pipe and cable accesses to the main biological shleid. Concrete covers vould also be poured over the main refueling floor so that the sealed biological shleid would then become the entombment structure. All contaminated material outside the biological shleid would be removed from the site for burial and all subgrade areas would be backfilled to grade. All non-contaminated equipment would be left in place. The containment structure would not be removed, since it could provide additional protection for the entembment structure.
This alternative would not result in the ultimate restoration of the site to its natural state. The Inventory of radioactive material remaining under this alternative would be about the same as the
Inventory remaining under the SAFSTOR Alternative, and approximately the same inspection, surveillance and maintenance activities would be required.
Radiation exposure during deconmissioning would be less than the DECON Alternative but more than the SAFSTOR Alternative.
PBAPS Unit No.1 can not be considered for entcrnbment due to the presence of several long Ilved radioisotopes, including nickel-63 and nioblun-94. These nuclides would not decay to levels permitting release of the facilities for unrestricted use within the foreseeable lifetime of any man-made structure.
This alternative has the additional disadvantage of increasing the volune of waste material and the complexity of total facility removal If ultimately total removal becomes necessary. (Ref. 7).
- c. SAFSTOR Alternative This alternative provides for the continued SAFSTOR status of PBAPS Unit 1 and assumes that at a later date (in approximately 40 years) total removal of the plant could be acconplished. PBAPS Unit No. I was deconmissioned using the guidance of Regulatory 1- Guide 1.86 (Ref. 6) which resulted in a condition of " Passive Safe Storage (mothballed)". In current terminology, this is equivalent to " Passive SAFSTOR" (Ref. 7). The primary system is sealed to enclose the residual radioactivity contained within the system. An Exclusion Area has been established
., ,-- around the containment, the fuel storage pool, and the 11 auld waste system basement. All contaminated' systems outside the Exclusion Area have been completely removed or decontaminated. Area decontamination within the Exclusion Area was I acconplished where feasible. The f+0 year extension of_PBAPS Unit 1 SAFSTOR will significantly reduce l
the radioactivity present and permit integration of the Unit 1 DECON program Into the Unit 2-3 deconmissioning prograrn.
3 This long' term passive SAFSTOR will reduce the 1
' occupational dose during ultimate dismantlement due
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to the decay of fission products and major activation i products. The ganma dose reduction is primarily i
! due to the decay of cobalt-60 (Ref. 7) In the reactor vessel and internals. The ganma dose rates will be reduced to approximately 0.5 percent of the 1986 ganma dose rates by the year 2026. In addition, i by 2026 further dose reduction is likely due to Improved methods resulting from advances In technology
! and experience gained in dismantilng other facilities.
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Since the containment interior is accessible for
, inspection and survelliance, the long term Integrity of the structure can be monitored and the effects of natural phenomena evaluated. The Inspection and surveillance will result In the only occupational dose during SAFS10R. Since the maxinun radiation '
level in any accessible area within the Exclusion Area is less than 1 mr/hr (Ref. 2) the total dose is 4
negligible.
Unit I shares the same site with operating units
'(Peach Bottom Units 2 and 3), permitting continuous observation of the Unit 1 facility. The former J Unit 1 Administration building is used as an emergency support facility under the Units 2 and 3 Emergency Prepardness Plan, and for classroom space and other miscellaneous support activities necessitating almost daily occupancy by plant personne1. Uti1IzatIon of security, engineering, and health physics personnel from Units 2 and 3 provide ample and readily available man power resources at a nominal expense for an effective Inspection program of the Unit 1 facility.
! Consequently SAFSTOR is compatible with the
(. long-term use of the entire Peach Bottom site.
V. CONCLUSION i The best alternative for PBAPS Unit No. 1 is the continued SAFSTOR. Due to PBAPS Unit No. 1 location on site with operating power reactors (PBAPS Units Nos. 2 and 3), the disadvantages of SAFSTOR are minimized as are the advantages of DECON maximized.
ENTOMB is not a vlable choice due to the presence of long Ilved radioisotopes. SAFSTOR will reduce personnel radiation exposure, the levels of radioactive waste shipped to a licensed burial site, the difficulty in meeting current low level waste allotments, and the risk of potential environmental effects associated with the other alternatives. Considering the stability and Isolation of the residual radioactivity remaining, as well as the current inspection program, the potential health risk to the public Is non-existant.
REFERENCES
- 1. Deconmissioning Plan and Safety Analysis Report Peach Bottom Atomic Power Station Unit 1, 1975
- 2. Deconmissioning Peach Bottom Unit 1 Final Report, July 1978
- 3. PBAPS Unit 1 Annual Deconmission Report 1979 and following
- 4. PBAPS Units 2 and 3 Environmental Report
- 5. Lear, George, NRC, letter to E. G. Bauer, PECo., July 14, 1975
- 6. Regulatory Guide 1.86, Jme 1974
- 7. Draft Generic Environmental Impact Statement on Deconmissioning of Nuclear Facilities NUREG 0586 January 1981
- 8. Appendix A to Operating License Technical Specifications and Bases for Peach Bottcm Atomic Power Station Unit No. 2 and 3
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PHILADELPHIA ELECTRIC COMPANY PEACH BOTTOM ATOMIC POWER STATION UNIT NO. 1 INFORMATION REQUESTED IN ENCLOSURE NO. 2 0F NRC CORRESPOM)ENCE DATED MAY 7,1986 00CKET NO. 50-171
r .
R Question 1 Provide an updated inventory of radionuclides (current curie quantitles) as previously tabulated on page 34 of your May 15, 1975 Deconmissioning Plan. Include niobiun-94, europILm-152 and carbon-14 l I
In the updated table.
Response
Figure 3.11-la (Rev. 1) of the May 15, 1975 Decemnissioning Plan is attached to include nioblun -94, europlun -152, carbon -14, and copper
-64 isotopes. In addition, the estimated values for the other isotopes listed in the Figure have been revised to reflect more current conservative assunptions. Figure 3.12 is attached to provide the activation source strengths for the isotopes IIsted in Figure 3.11-la (Rev. 1) as of January 1, 1987. 1 l
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5
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- l Question 2-Provide a second table that projects the radioactive Inventory at the time you Intend to remove residual radioactivity from Peach Bottom 1.
Response
Figure 3.13 is attached to provide the activation source strengths on
? January 1, 2027 for the isotopes IIsted in Figure 3.11-la (Rev. 1).
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4 Question 3 Provide an estimate of the deposited activity (contamination) as shown in Figure 3.11-2 of your DeconTnissioning Plan for the times indicated in items 1 & 2 above.
Response
Figure 3.11-2 (Rev. 1) is attached to include estimates of deposited activity on the interior surfaces of the reactor coolant system on January 1, 1987, and January 1, 2027.
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i l FIGURE 3.11-2 (Rev.1) [
l_____________________________________________________________;
l Deposited Activity on the Interior Surfaces l l of the l l= Reactor Coolant System l
- _____________________________________________________________l l_____________________________________________________________l l l Nuclide l Activity (Curies) at Date l l l Half-Life l--------------------------------]
l Radionuclide l (Days) l 05/01/75 l'01/01/87 l 01/01/27 l i____________________________________________________________ l l Cs-137 l 10957.5 l 2.02E+01 l 1.54E+01 l 6.12E+00 l l_____________________________________________________________l l Cs-134 -l 748.8 l 5.80E+00 l 1.12E-01 l 1.50E-07 l l_____________________________________________________________l l Ce-144 l 284.0 l 2.00E+00 l 6.08E-05 l 1.99E-20 l
- _____________________________________________________________l l Sr-90 l 10263.5 l 2.00E+00 l 1.50E+00-l 5.59E-01 l l_____________________________________________________________l l TOTALS l l 3.00E+01 l 1.70E+01 l 6.68E+00 l
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l Question 4 Identify any benefits that result from your proposed delay in removal of the residual radioactivity with respect to: The methods that would be used in removing radioactivity, any reduction in the total person-Rem exposure to workers, and reduction in the voltsne of radioactive weste produced during dismantilng. Provide graphs of gamna radiation exposure vs. time that workers would be exposed to when removing residual radioactIvlty.
Response
Ntsnerous radiological and ALARA benefits result frcrn delaying the final decontamination and removal of residual radioactivity:
- 1) Experience gained from the dismantilng of other sites and technological advances in the area of robotics and the handling of radwaste should reduce the radiation exposure to personnel involved in the eventual removal of residual radioactivity and equipment disasserrbly.
- 2) Delaying the final decomnissioning by 40 years will lower the gamna activity of the activated steel components in the reactor by a factor of approximately 200 (the primary gamna emitter is Co-60 with a half-life of 5.2 years). 1.tkewise, the total activity will be reduced by,a factor of 18 over the same time period. Therefore, we can expect a proportionate reduction in total person-REM exposure to workers decontaminating and dismantilng equipment.
- 3) Advances in the handling and ccznpaction of radwaste should reduce the volune of radioactive waste associated with the dismantilng and decontamination.
- 4) Delay In the removal of residual radioactivity from Unit I should likewise minimize the potential hazards resulting from airborne radiation sources to onsite personnel involved with the operations of Units 2 and 3.
- 5) Since the DECON alternative is not presently viable for Peach Bottcm Unit 1, detailed radiation studies associated with plant disassently have not been performed. Consequently, detailed gamna radiation exposure graphs and data are unavailable at this time. However, based on the argunents stated previously, It can be expected that delay in the removal of residual radioactivity from the site to the year 2027 should result In a proportionate reductico in the gamna person-REM exposure to workers by a factor of approximately 200. When the ultimate deconmissioning plans for Peach Bottom Unit 1 are developed, evaluations of worker radiation exposure during removal of residual activity will be perfonned.
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Question 5 Enclosure No. 3 (Letters from the NRC to Stanford University) states our present criteria for release of a facility to unrestricted access.
Provide an evaluation of the predicted radiation levels in buildings, rooms, and structures relative to that criteria at the time in which
,you intend to remove the residual radioactivity. Will any structures meet Enclosure No. 3 criteria at that time without further decontamination?
Response
Since the DECON alternative is not presently viable for. Peach Bottom Unit 1,. detailed studies to predict radiation levels in buildings, rooms, and structures at the time of disassembly have not yet been performed. When the ultimate deconmissioning plans for Peach Bottom Unit 1 are developed, such an evaluation will be performed and the results compared to the NRC criteria for release of the facility to unrestricted access which are in effect at that time.
CWW/cb/02028704 -
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