ML20206M676
| ML20206M676 | |
| Person / Time | |
|---|---|
| Site: | Dresden  |
| Issue date: | 08/13/1986 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20206M681 | List: |
| References | |
| NUDOCS 8608210312 | |
| Download: ML20206M676 (9) | |
Text
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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATING TO THE OPERATION OF A MOBILE VOLUME REDUCTION SYSTEM COMMONWEALTH EDISON COMPANY DRESDEN NUCLEAR POWER STATION, UNIT NOS. 2 AND 3 DOCKET NOS. 50-237 AND 50-249
1.0 INTRODUCTION
In a letter dated April 10, 1984, Commonwealth Edison Company (CECO) notified NRC that CEC 0 desired'to acquire and operate a Mobile Low-Level Radioactive Waste Volume Reduction System (MVRS) incinerator at Dresden Nuclear Power Station (DNPS). .By its letter dated November 7,1984 CECO (the licensee) submitted its Safety Evaluation Report (SER) titled
" Operation of a Mobile Low-Level Radioactive Waste Volume Reduction System" to operate the MVRS incinerator at DNPS pursuant to Section 20.305 of 10 CFR Part 20. Subsequently, the licensee submitted a revised SER with its transmittal letter dated January 3,1985, incorporating responses to the staff's licensing review questions. The licensee referenced in its SERs l the Aerojet Energy Conversion Company (AECC) Licensing Topical Reports '
(LTR),AECC-4-P/NPdatedMay1,1984andAECC-4-NP-A(NRCacceptedversion) dated November 9, 1984.
The staff reviewed the LTR and prepared a Safety Evaluation (SE) (October 26, 1984) accepting it for referencing in license applications to the extent speciffed and under the limitations delineated in the staff's SE. Subsequent to the issuance of the staff's SE, AECC modified the MVRS design and submitted Revision 1 to the LTR with its transmittal letter dated January 15, 1986.
The staff reviewed the revision and prepared a Supplemental SE (April, 1986) accepting the design changes proposed. The licensee referenced Revision 1 to AECC Topical Report, AECC-4-NP-A in a letter dated December 12, 1985.
The basis for the staff's acceptance of the AECC Topical Report was the staff's conclusion that the MVRS is designed and can be operated in accordance with current guidelines of applicable regulatory guides, standard review plan, branch technical positions, and Federal regulations. The staff's evaluation and conclusions with respect to the MVRS are presented in the staff's SE and its Supplemental SE. AECC will own, operate, and maintain the MVRS at DNPS. The MVRS is limited to processing only Class A Waste as defined in Section 61.55 of 10 CFR Part 61 as proposed in the licensee's SERs. Hence, the MVRS waste product must satisfy the minimum requirement set forth in Section 61.56 of 10 CFR Part 61, 2.0 EVALUATION The AECC Topical Report, AECC-4-P/NP-A, Revision 1 dated January 15, 1986 (AECC Topical Report) contains information pertaining to the MVRS design 0600210312 860313 DR ADOCKOD00g7
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2 y- bases, the process and equipment' descriptions, process parameters, process material balance, piping and instrument diagrams, the system operation, and equipment arrangement. The MVRS employs a controlled air incinerator with a liquid offgas cleanup system. It is capable of converting combustible, low-level dry' radioactive solid wastes (DAW), and radioactively contaminated oil into an ash that can be appropriately packaged for offsite land disposal.
The MVRS is composed of '(a) a conIrolled air incinerator, (b) a wet offgas cleanup system. (c) an offgas treatment system, and (d) an ash handling system, all mounted on separate enclosed skids in three trailers.
The controlled air incinerator is a two-stage combustion device. The primary combustor operates at a negative pressure under air-limiting and under-fire conditions at a fixed temperature of about 1600'F. The secondary combustor also operates at a negative pressure, but with high excess air and at a high temperature (2100*F).
The incinerator is batch-fed with compacted, shredded or non-compacted trash, plus a small quantity of concentrated scrub liquor (see below) via an air-lock feeder and ram arrangement. Contaminated oil is fed to the primary chamber by a separate burner. The disposable product from the system is removed as ash from the primary chamber.
The offgas from the secondary combustion chamber is quenched and scrubbed of particulates and acid-gases in two liquid venturi scrubbers. The scrub liquor is separated from the gases in a vessel which contains a liquid sump, a gas-liquid da-entrainment section, and a demister. Scrub liquor recirculation is controlled automatically in reference to liquor flow rate, liquor solids content (about 20 Wt percent), sump level, and pH. No liquid wastes are generated by the MVRS.
The gas treatment system draws the cleaned, saturated offgas from the wet scrubbers, heats it slightly by compression using an induction fan, passes it through a filter assembly, and releases it to the atmosphere after monitoring for airborne radioactivity.
The staff's SE for acceptance of the AECC Topical Report contains the basis for acceptance and delineates the specific limitations. It also requires specific additional information for licensing review and approval for the individual user applications. In conducting the evaluation the staff requested the following specific site related additional information:
(1) Any exceptions or deviations from the MVRS Topical Report dated May 1, 1984, and its Amendment No. I dated September 1, 1984.
(2) Interfaces between the plant and the MVRS.
(3) A Process Control Program (PCP) which assures that the solid waste product meets guidelines set forth in Branch Technical Position ETSB 11-3, Rev. 2 July 1981.
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3 Y (41 Waste classification program to demonstrate that the solid waste product is Class A in accordance with 10 CFR Part 61, Section 61.55, and meets the minimum requirements set forth in 10 CFR Part 61, Section 61.56(a). !
l (5) Description of the solid waste product container to be used for l ultimate disposal of the MVRS product.
(6) An evaluation of offsite doses from effluent releases and direct radiation due to normal operation of the MVRS including anticipated operational occurrences.
2.1 Exceptions and/or Deviation from the MVRS Topical Report The licensee has taken one exception to the NRC approved MVRS Topical Report by not providing a charcoal adsorber in the offgas treatment system.
The use of the MVRS at DNPS is limited for only (1) low-level drv combustible solid radwaste with a contact dose rate reading at a waste collection container surface of less than or equal to 25 mR/hr, and (2) contaminated oil with radioactivity concentration of less than or eaual to 0.1 pCi/cc. ,
On the basis of the staff's cumulative review of the licensee's semi-annual effluent release reports and NUREG/CR-4379, the staff estimates that each Dresden unit will generate approximately ?0,000 cubic feet of low , level dry combustible solid radwastes per year containing less than 5 curies of total radioactivity (primarily Co-58, Co-60, Cs-134, and Cs-137), with no detectable radioiodines in the dry solid radwaste. For the contaminated oil the licensee states that the only radioisotopes detected thus far are Cr-51, Mn-54, Co-60 and Cs-137 with no detectable radiciodines.
In view of the estimated low levels of radiciodines in the process stream, the staff concludes that the licensee's exception in not providino a charcoal adsorber to remove radiciodines in the MVRS offgas treatment system is acceptable, provided that the licensee periodically collects and analyzes representative samples of radioactive iodines and particulates in the offoas treatment system effluent during all modes of MVRS operation.
This requirement is to assure and verify the absence of any radioiodine releases. The sampling and surveillance requirements for iodine and particulates in gaseous effluents are specified in the DNPS Technical Specifications. The staff also requires that the licensee implement administrative controls to ensure that the contaminated oil will be incinerated on a batch basis only, subsequent to the complete isotopic analysis of representative samples of oil from each batch and/or composite samples from not more than five 55-gallon drums. The licensee should maintain adequate records of oil analysis to document all radioactive releases and resulting offsite doses.
In addition to the above exception taken by the licensee, the staff also found that the licensee has taken a deviation from the Topical Report in that the MVRS will not be operated by AECC, but by a subcontractor to the AECC under supervision of an AECC foreman.
4 I
The licensee submitted with its transmittal letter dated March 21, 1985 the minimum required operator qualification and operator training programs for the MVRS. The staff reviewed the submittals and found them to be satisfactory and acceptable.
2.2 Interfaces between DNPS and MVRS A concrete pad (60 feet by 60 feet with an overall thickness of approximately 10 inches) is provided for the MVRS structural foundation as shown in Figure 2.
The pad consists of poured-in-place concrete.
The staff reviewed the licensee's analysis on the use of eight 250 gallon propane storage tanks used in the mobile volume reduction system. Each of the eight tanks is to be located in a 40 square foot diked enclosure on a 40 foot long trailer as shown in Figure 1. The trailer will be parked on a concrete pad as indicated on Figure 2. The distance from the trailer to the closest air intake for the reactor facility is approximately 300 feet.
The air intake louvers are about 12 meters higher than the elevation of the propane storage tanks. If released from any of these tanks, propane will tend to flow along the ground, since it is heavier than air.
The licensee has calculated that the release of all the propane from a single tank (875 pounds) will result in a propane concentration of 5.3x10-4 lb. of propane per cubic foot of air (4.71x103PPM), which is stated by the licensee to be below the flamable limit of 1.48x10-3 pounds of propane per 4
cubic foot of air (1.3x10 PPM).
The staff performed independent calculations whicn indicate that at 300 feet (91 meters), with a wind speed of 1 meter /second and Pasquill "F" conditions, the maximum propane concentration would be 500 PPM at the closest air intake elevation. This is below the propane lower flammability 4
limit (C )g of 2.69x10 PPM. The n.aximum concentration at ground elevation 5
at 300 feet is 2.1x10 PPM for approximately 10 seconds. The staff's calculations indicate that with a ventilation rate of one air change per hour, the concentration of propane within the building will be well below the flammable limits for air intakes located either at ground level or at 12 meters above ground.
i The staff has estimated the blast overp essure due to the release and ignition of the contents of a single ta'k 30C feet from the turbine building air intakes louvers. Using a TNT e4uivalency factor of 2.4 for propane,'and assuming that only propane in the initial puff release (30% of total release) is detonated, the blast overpressure is 2.5 psi.
The staff has estimated the diameter of a propane fireball to be about 86 feet. The duration of the fireball would be about 2 seconds, and the thermal flux at 300 ft. is approximately 9 YW/M2 ,,
- Note: Flux required to ignipe wood after 1 minute = 38.7 KW/M . A thermal flux f SKW/M will cause personnel burns in 30 seconds and 12.6 KW/M will cause wiring damage. Ref. " Hazardous Materials Spills Handbook, " Gary F.:Benrett, et al., pp., 10-74 l
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g I The staff has also considered the possibility that the postulated detonation of a single propane tank could rupture one or more of the remaining seven propane tanks. It was assumed conservatively that all of the seven tanks would fail and release all of the propana in each tank. The initiatino event, namely the detonation of a propane cloud from the first tank, is a high energy yield event. Hence, it would act as an ignition source for the postulated subseouent release of additional propane. The result would be the generation of a fireball which would not be larger than about 163 feet in diameter and which would burn for about 4 seconds. The thermal flux is 2
estimated to be about 42 KW/M .
The staff has also investigated the question of delayed ignition of a propane gas cloud and determined that it will not affect the safety of the nuclear facility. The staff's calculations indicate that the flammable portion of a propane puff release will he in the vicinity of the turbine and Unit 2 reactor buildings for approximately 10 seconds (assuming a wind speed of 1 meter /sec.). Following passaae of the " puff", the concentration of propane in the plume would be below the flammable level due to the reduction in the propane liquid evaporation rate caused by the dike surrounding the propane storage tanks. This dike would restrict the evaporation rate so that at 300 feet the concentration of propane in the plume is below the flammable limits. Without the dike, the concentration of propane in the plume is above the flammability value.
These calculations are conservative in that they do not include credit for olume meander or " wake effect" of the plume traveling between buildings.
Poth of these effects would further dilute the propane concentration.-
In view of the results of the above analysis, the staff concludes that the use of 250 gallon propane storage tanks at the proposed location does not present an undue hazard with respect to the safety of the nuclear facility.
The other interface requirements provided for the MVRS by the licensee include electrical power, service water, fire protection water (a hydrant located approximately 100 feet south of the MVRS padi, and telephone service.
The staff finds that the interface requirements listed in the Topical Report l
are met by the licensee and, therefore, are acceptable.
2.3 Process Control Prooram (PCP)
The AECC has developed and provided an acceptable PCP to ensure that the agglomerated ash / salt product from the MVRS is capable of meetino the free standino liquid guidelines described in Branch Technical Position ETSB-11-3, Rev. 2.
I Performance tests were conducted at the Aero.iet test facility to determine the optimum ratio of water to ash product. In the range of 85 to 150 cc of water per liter of ash, the waste ash product exhibited an agolomerated dense granular form. The test also revealed that the moisture content could be increased to as high as 170 cc of water per liter of ash product without having free-standing water in the waste container. When less than 75 cc of water per liter of ash product was used, the agglomeration was incomplete, and some fines resulted. The test results indicate the optimum ratio to be approximately 100 cc of water per liter of ash product. On the basis of these tests, the staff finds the use of the AECC PCP for the MVRS operation at DNPS to be acceptable.
Y The staff reavires the licensee tn obtain ash samples from the the first five ash containers for DAW and contaminated oil feed. Moreover, the licensee should obtain at lent one ash sample from every ten (101 subsequent ash containers (1) to determine operational variances and establish a date base, and (2) to verify the absence of free liquid in the ash containers. The licensee should also provide a complete 10 CFR Part 61 isotopic analysis for one typical ash sample. This analysis should be done at the beginnina of the operation and thereafter at least as often as recommended in the Branch Technical Position on Waste Classification. The licensee is required to limit dry solid radwaste to packages whose surface dose rates are no more than 25 millirem per hour and contaminated oil whose total radioactivity concentration is not greater than 0.1 pC1/cc.
The licensee stated in its SERs that the operation of the MVRS is limited to process Class A Waste as defined in Section 61.55 of 10 CFR Part 61, and that the licensee will meet the minimum requirements set forth in Section 61.56 of 10 CFR Part 61. In addition, the licensee must meet the licensed waste burial site operator requirements.
On the basis of actual pre-operational test results performed on an as-built PVPS at one AECC test facility, the staff concludes that the physical form and characteristics of the ash product can meet the minimum waste form requirements set forth Section in 61.56(a) of 10 CFR Part 61.
2.4 Solid Waste Product Container Section 61.56(a) of 10 CFR Part 61 requires that Class A waste nust not be packaged for disposal in cardboard or fiberboard boxes. The licensee states that the waste ash product will be anglomerated and will be packaged in " strong tight containers" to meet the waste disposal burial site requirements and DOT regulations.
2.5 Offsite Doses and Radioactive Effluent Release AECC calculater' in the MVRS Topical Report the estimated annual release of radioactive materials in caseous effluents resulting from the operation of the MVRS. AECC used an annual radioactivity innut rate of 5.2 Ci in DAW and an overall system decontaminatica factor (DF) of a million.
A compilation of data on solid radwaste shipments from operatinn LWRs as reported in the licensee's semi-annual effluent release reports shows an annual average radioactivity input rate of less than 5 Ci per unit in DAW.
NUREG/CR-4370 estimates an annual average radioactivity of less than 4.5 l
Ci per unit in DAW at DNPS (i.e., fresh water cooling and deep bed condensate polishing systems). The staff used an annual radioactivity input rate of 5 Ci per unit in DAW and an overall system DF of 100.000, i The staff's DF is based on (1) the performance test results for as-built MVRS l
venturi scrubbers, (2) the HEPA fi'ter DF's specified in NIIREG-0016, Rev. 1 as reproduced below:
i f
. 7 3 Decontamination Factors Used AECC Staff Primary Combustor 20 20 Scrubbers 1000 50 Filter 200 100 Overall 4,0ED00 10EU00 The AECC calculation indicates a total airborne radioactivity release of 1.3x10-6 Ci per year, compared to the staff's 1.5x10-4 Ci. These release rates are insignificant in comparison with approximately 0.45 Ci of airborne radioactive particulates released in 1984 and 0.1 Ci in 1985 from DNPS Unit Nos. 2 and 3.
Using the methods of Regulatory Guide 1.109, the staff has estimated the doses to a maximally exposed member of the public, as well as the population as a whole in the area surrounding the DNPS. Doses to the total body and any organ were estimated due to exposure to airborne radioactive effluents from the incineration process for the ground shine, inhalation and food ingestion pathways. The dose estimates are based on the airborne radioactive particulate releases of 1.5x10-4 C1. Doses to the maximally exposed indi-vidual were estimated for an individual at the site boundary, 0.9 kilometers north of the incinerator, assuming a continuous ground-level relea,se. An average annual atmospheric dispersion factor of 9.3.x10-5 sec/m3and average annual relative deposition factor of 9.3x10-8 ,2 7 were used to estimate doses.
The highest annual dose to the total body and any organ of the maximally exposed individual is estimated to be less than 0.1 mrem from exposure to radioactive effluents from the incineration. This annual dose estimate is a small fraction of ALARA design objectives set forth in Appendix I to 10 CFR Part 50. The annual do::e to the population within 50 miles of Dresden from exposure to radioactive effluents from the incinerator is estimated to be less than 0.1 person-rem. This annual population dose estimate is also a small fraction of the total annual population dose resulting from operation of Dresden Units 2 and 3 (i.e., 160 person-rem).
The dose to the maximally exposed individual is estimated to be a small fraction of the annual exposure to natural background radiation, which is about 105 mrems for the state of Illinois.
3.0 CONCLUSION
On the basis of the foregoing evaluation, the staff concludes that the operation of the the MVRS will not present an undue hazard with respect to either safe operation of DNPS Units 2 and 3, or public health and safety with respect to the release of effluents. Therefore, the staff finds the licensee request to operate the MVRS at Dresden pursuant to Section 20.305 of 10 CFR 20 to be acceptable.
Principal Contributors: J. Lee, K. Campe, C. Ferrell and T. Mo Dated: August 13, 1986
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