ML19257C548

Plan for Temporary Onsite Storage of Low Level Radwaste.

ML19257C548
Person / Time
Site:	Browns Ferry
Issue date:	01/21/1980
From:	TENNESSEE VALLEY AUTHORITY
To:
Shared Package
ML19257C543	List: ML19257C542 ML19257C548
References
NUDOCS 8001290377
Download: ML19257C548 (18)

Text

PLAN FOR TDiPORARY ONSITE STORAGE OF LOW-LEVEL RADI0 ACTIVE WASTE BROWNS FERRY NUCLEAR PLANT UNITS 1, 2, AND 3 January 21, 1980 TENNESSEE VALLEY AUTHORITY 1827 265' 8001290

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TABLE OF CONTENTS I. INTRODUCTION II. NEED FOR ONSITE STORAGE III. CABLE WARE 110USE A. Existing Structure B. Structural Modifications C. Restrictions on Use of the Structure IV. GENERAL CONSIDERATIONS A. Criteria B. Operations C. Radwaste Volume Rcduction D. Physical Security E. Container Integrity F. Spontaneous Combustion G. Design Basis Event for Drum Restraints 11 . Structural Design of Cable Warehouse I. ALARA Considerations V. RADIOLOGICAL ASSESSMENT A. Assumptions /Results B. General Observations / Conclusions VI. DECOMMISSIONING A. Statement of Intent B. Guideline Criteria C. Subsequent Use of Area Appendix A - TVA Plan for Permanent Storage / Disposal of All Low-Level Radioactive Waste Generated by TVA Nuclear Plants

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W I. INTRODUCTION The Tennessee Valley Authority (TVA) hereby proposes to amend operating license numbers DPR-33, DPR-52, and DPR-68 for Browns Ferry Nuclear Plant units 1, 2, and 3 to allow the storage of low-level radioactive trash generated in the routine operation of the facility. The trash will be stored onsite in a warehouse designed initially for storage of electrical cable. Provisions being made to adequately isolate the low-level trash and its associated radioactivity from the environ-ment are described herein. Because the cable warehouse is outside the existing restricted area boundary provisions will be made to provide an adequate level of physical security. These provisions are also described herein.

II. NEED FOR OUTSIDE STORAGE At the present time the low-level radioactive trash being generated at the Browns Ferry Nuclear Plant is being stored temporarily in the plant and in trailers onsite within the restricted area boundary. The radioactive resins and higher level trash continue to be shipped to the licensed disposal facility at Barnwell, South Carolina. The need for temporary storage of trash has come as a result of a severe cut back in TVA's allocation of radioactive waste shipment to the Barnwell burial site.

III. CABLE WARElIOUSE A. Existing Structure The cable warehouse consists of a covered concrete floor slab (300 feet by 50 feet), with a perimeter fence and loading dock.

There are paved roads into the area. The cable warehouse is onsite, but outside the existing security area (see Figure 1).

B. Structural Modifications

1. The wooden substructure of the roof and columns will be covered with a fire retardant coating. The coatings under consideration are:

PPG 42 Speed Ilide Gilman 110 - Flame Chek Albi 107A These coatings have been tested in accordance with ASTM E84 for flame spread, fuel contributed, and smoke development as follows:

Flame Spcead - 15

'uel Contributed - 15 lake Development - 15 ,

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2. A (watertight) concrete curb eight inches high and six inches thick will be poured around the entire cable warehouse area. This curb will be bonded to the concrete floor slab by means of an epoxy sealer. This curb is needed to contain any rainfall and water from potential fire fighting operations.

C. Restrictions on Use of the Cable Warehouse

1. The cable warehouse will be used for the storage of low-level compactible/noncompactible trash only. Compactible/ noncom-pactible trash will be basically composed of the following iaterials:

1. Paper, including blotter paper

2. Plastics

3. Respirator cartridges

4. Protective clothing

5. Laboratory equipment (vials, glassware, plastic bottles)

6. Tape and rope

7. Piping and valving

8. Scaffolding and ladders

9. HEPA filters

10. Mop heads

11. Other wood and small metal objects

2. The total activity of waste stored in the cable warehouse will not exceed 1,320 curies.

3. All containers of waste which will be stored in the cable warehouse will be removed before August 1, 1981.

4. No wooden boxes or other combustible boxes will be placed in thie storage location.

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IV. GENERAL CONSIDERATIONS A. Criteria The following criteria apply to the onsite storage of low-level radioactive trash in the cable warehouse.

1. Contaminated compactible trash will be packaged in DOT 17H steel SS -gallon drums (minimum wall thickness, 0.0428 inches).

If other containers are needed, metal boxes will be con-structed. Noncompactible trash will be packaged in metal boxes fabricated from steel plate (0.0428 inches minimum thickness).

2. Fire protection will be provided by existing hydrants in the area. Manual firefighting will be used to extinguish any fires. A routine roving fire watch sur-veillance of the temporary storage area will satisfy the necessary fire detection requirements.

3. Monitoring will consist of daily surveys by Health Physics that include surface contamination determination, as appropriate, and radiation dose rate measurements. No airborne radiation sampling is required.

4. The immediate area surrounding the cable warehouse will be designated a controlleo access area. The area will be enclosed and signs posted , ting Health Physics access requirements for entrance inta the area. Access to all areas in the vicinity of stored waste will be controlled as necessacy to ensure compliance with 10 CFR 20 provisions.

5. Liquid releases from within the curbed area will conform to 10 CFR 20, Appendix B, Table 2, 90lumn 2, for unrestricted areas. These limits are 1 x 10_ p Ci/ml for gross beta-gamma activity or an MPC ratio less than 1.0.

6. All drums selected for storage at the cable warehouse will be limited to a maximum contact dose rate of 700 mrem per hour. No shielding external to the drum will be used to meet these limits.

7. The activity of each container will be limited to no more than 0.5 curies and the total limit for the storage area will not exceed 1,320 curies. Only a small number of drunsare expected to have a content activity of 0.5 curies.

The average activity per durm is expected to be less than 0.1 curie.

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8. Removable radioactive contamination on the surface of containers shall be limited to the levels specified in 49 CFR Part 173.397. All containers will be decontaminated to less than these levels before storage. With these low values for permissible levels of surface contamination, the generation of measurable airborne radioactivity above back-ground has a very low probability and the generation of hazardous airborne radioactivity levels a much lower probability still.

Since the only nonaccident circumstances under which the generation of measurable radioactivity concentrations can be postulated are the removal by air currents of contamination from the surfaces of the waste containers there is no need for airborne radioactivity monitoring.

9. All containers of trash placed in temporary storage in the cable warehouse will be held secure at all times by means of an installed restraint system. This system will hold all containers secure during all severe environmental conditions up to and including the design basis event for this waste storage facility. (See section IV.G., " Design Basis Event for Drum Restraints").

B. Operations

1. Movement of Containers - The drums and metal boxes containing the trash will be moved into the warehouse with a forklift of the grabber design. Only one drum or container will be moved at a time. The containers will be stored in accordance with General Criteria Number 9.

2. Dewatering of Area - Any accumulation of water within the curbed area will be removed by means of a portable sump pump. The activity of the water will be monitored before dewatering operations. Any radioactive liquid that exceeds the limits of General Criteria Number 6 will be transported to the Radwaste Building for processing. (See General Criteria Number 6)

3. Remedial Actions (Cleanup) - The content of the containers to be stored in the cable warehouse will be restricted to low-level radioactive waste either in the form of noncompactible loose material / trash or compactible trash. (See section III.C.)

In addition, the radioactivity of each container will be limited to 0.5 curies. (See section IV.A., Criteria Number 7)

In the event that a container is punctured, crushed, cracked or opened, and turned over during transit or while in storage the contents should not be released. Punctured drums will be repaired utilizing existing plant procedures. However, if some of the contents are released it will be collected, packaged, and stored. If the container is irreparably damaged it will be cut up and packaged as low-level radioactive waste.

The area of the floor with which the released trash was in contact will be monitored for activity and appropriate measures, s taken to decontaminate the area.

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C. Radwaste Volume Reduction The following items describe the actions currently implemented and proposed for radwaste volume reduction at Browns Ferry Nuclear Plant.

1. Some outage generated trash is currently monitored by Health Physics personnel and separated into contaminated and noncontaminated categories.

2. Some wooden scaffold boards are being replaced with aluminum scaffolding.

3. Under consideration are such things as collection of all new lon exchange resin bags in special wire mesh baskets; placement of trash cans with green insert bags for clean trash and cans with yellow insert bags for contaminated trash; and use of mops with detachable mop heads and reusable handles.

D. Physical Security

1. Access to the cable warehouse will be restricted by means of a fence eight feet in height consisting of a nine gauge two-inch mesh with a seven foot chain link fabric and three strands of barbedwire inclined outward. Access to the area will be through one gate which will be kept locked or guarded when access is needed by plant personnel.

2. Regular periodic security checks of the area surrounding by Public Safety Service (PSS) officers who patrol the site 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> a day.

3. When plant personnel are within the security fence for monitoring or package storage, the Health Physics technician shall be responsible for maintaining radiological safety during operations inside the storage area.

4. PSS officers will unlock the security area for personnel entrance, lock the area at the end of disposal operations, and maintain control of all keys to the area.

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E. Container Integrity The materials which will be stored in the cable warehouse, listed in section III, item C.1, are nonagressive with respect to corrosion attack on trash containers, liowever, some of these materials (e.g., mop heads and blotter paper) can be wet at the time of packaging. Absorbent material such as diatomaccous earth will be added to packages containing wet waste. If wet trash is packaged, the corrosion attack from this wet trash will be negligible due to the limited contact with the internal surfaces of the containers and the small amount of moisture present.

All external surfaces of the drums and metal boxes are painted to prevent external corrosion attack, llowever, water does attack mild steel, at a corrosio ate of 0.002 to 0.02 inch per year at a temperature of 77 F. Thus, if the paint becomes scraped away in small areas and the containers continuously exposed to moisture, the wall thickness is sufficient to ensure container integrity in excess of two years. The containers are not continuously exposed to moisture during the storage period, thereby significantly decreasing the rate of corrosion attack.

Based on the above discussion, the radwaste container integrity is more than adequate for the proposed 18-month temporary storage period. When the containers are transferred to permanent onsite storage facilities, they will be inspected for fatigue, failure, and damage. TVA is still evaluating the optimum materials and container design for long-term storage of low-level radioactive waste.

(1) Corrosion Data Survey, Fif th Edition, compiled by N. E. Ilammer, National Association of Corrosion Engineers, llouston, Texas, 1974.

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F. Spontaneous Combustion TVA has evaluated the potential for spontaneous combustion in the low-level waste trash containers. This evaluation assessed the potential for spontaneous ignition from two standpoints:

1. Heat generated due to the radioactivity of the stored trash, and

2. Spontaneous heating due to the content of the stored trash, e.g., oil- or grease-soaked rags or clothing.

The heat generated by the low-level of radioactivity contained in the trash is negligible.

The spontaneous heating phenomenon associated with oily rags or clothing, etc. , applies only to those liquids coming directly from a living source, i.e., animal oils. Most flammable liquids are not subject to spontaneous heating.

The types of flammable liquids which may be present in the stored trash, in the form of oily rags or clothing, would generally be petroleum products such as lubricating oils or grease and are not subject to spontaneous heating. There may be some potential for the storage of small quantities of rags or clothing contaminated with paint containing drying oils or turpentine, which are rated moderate and low hazard, respectively. Hawever, the configuration of the stored trash, i.e., compacted in sealed drums, is such that insufficient oxygen is available to contribute to the oxidation process, and therefore, combustion does not occur.

Based on the above, we conclude that spontaneous combustion does not represent a significant concern.

G. Design Basis Event For Drum Restraints

1. For purposes of temporary storage of low-level radioactive waste in the cable warehouse at the Browns Ferry Nuclear Plant the following event with its associated frequency of recurrence has been used as the design basis event:

Basic Wind - wind velocity of 95 miles per hour

- 100-year recurrence frequency

2. The probability of a tornado with maximum wind speeds higher than the 95 miles per hour value striking the plant in any one year is 7 x 10-4 This is considered to be small enough to be neglected.

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H. Structural Design of Cable Warehouse The cable storage warehouse was designed to withstand the following severe environmental events:

Design wind - 80 miles per hour Snow loading - 20 inches These events are equal to or greater than the requirements as specified in the International Conference of Building Officials, Uniform Building Code, 1976.

We do not anticipate that a failure of the cable storage warehouse or its superstructure will result in unacceptable damage to the drums and metal boxes that will be in storage.

I. ALARA Considerations ALARA considerations applicable to the handling of the drums in preparation for transport to, and placement in the temporary storage facility are covered in appropriate plant instructions. Since the temporary storage facility is located in a warehouse area in which access is required for normal operation of the plant, it was decided that 16-inch-thick concrete block shield walls should be erected on the (assumed) south and east sides of the structure. These walls will be crected concurrently with the storage operation. This timing is acceptable since the dose rate from the initial storage will be but a small fraction of that of the filled facility and the construction time for the walls is less than a month; hence the walls will be in place when required. It was decided not to enclose the other two faces of the facility with similar shield walls because, in these directions, the revised fence location precludes entry to areas where radiation levels would be significant. It was also judged that ease of access for placing drums in storage as well as for emergency actions such as fire fighting outweighed the gain from a shield wall.

To achieve dose rates of 10 CFR 20 (0.6 mrem /hr), a security fence will be located appro::imately 500 feet to the north of and approximately 260 feet to the east and west of the cable warehouse structure. When the new shield wall is erected, there is no need to move the existing security fence on the south side of the structure.

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V. RADIOLOGICAL ASSESSMENT A. Assumptions /Results

1. The proposed radioactive trash temporary storage facility is located approximately 875 meters from the closest unshielded boundary. The dose rate expected at that distance from the (completely filled) temporary facility is about 4 x 10-4 mrem per hour. This dose rate was calculated using the point-kernel-with-buildup approximation. Note that this approach includes the contribution from scattered radiation (the so-called skyshine) because the buildup factor is the ratio of the dose rate, at a point embedded in an infinite medium due to a point source in the same medium, as determined by a rigorous method which treats all significant applicable physical pnenomena to the dose rate, at the same point and from the same source, due to the uncollided flux only. Because of the large distance involved, it is reasonable to assume the f acility is embedded in a semi-infinite ocean of air, thus making the buildup hypothesis applicable.

2. The assumptions used in the radiological assessment of the storage of low-level radioactive trash in the cable warehouse are summarized in Table V-1.

3. The results of the radiological assessment are summarized in Table V-2.

t B. General Observations / Conclusions Based on the assessment results the following observations and conclusions can be made.

1. The value of <1 percent of MPCw (Maximum Permissible Concentration) for the maximum radionuclide concentration at the nearest public water supply from an accidental release of activity to the river via groundwater is an acceptably small fraction of the MPCw.

2. The value of 3.1 mrem / year for exposure to the nearest unshielded site boundary from direct radiation snine is a very small fraction of the 40 CFR 190 limit (25 mrem / year).

We believe that this fraction is acceptably small.

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VI. DECONIMISSIONING A. Statement of Intent

1. After all containers of radioactive trash have been removed and the structure is no longer needed as a radwaste storage area, the cable warehouse will be decommissioned in accordance with the guidelines presented in section VI.B. below.

2. In general, we anticipate that acceptable decontamination of the cable warehouse, temporary waste storage area, to be performed as part of its decommissioning will not be difficult.

B. Guideline Criteria

1. Since there are no specific requirements or guidelines for the decommissioning of a temporary radioactive waste storage facility, TVA has developed those presented below. We believe these guidelines are reasonable and fully acceptable.

(a) TVA will make a reasonable effcrt to eliminate residual contamination.

(b) No radioactive surf ace will be covered by painting, plating, or other method until it is known that contamination levels, to be determined by a survey and documented, are below a reasonably achievable limit.

(c) TVA will use the limits presented in Table I of USNRC Regulatory Guide 1.86 as guidelines.

C. Subsequent Use of Area

1. Before release of the premises for unrestricted use, TVA will make a comprehensive survey establishing that the level of residual contamination is as low as reasonably achievable.

A report describing the survey and its results will be filed with the Director, Office of Nuclear Reactor Regulation, U.S. Nuclear Regulatory Commission, with copies to the Director, Office of Inspection and Enforcement Headquarters and to the Director, Region II OIE office. The survey report will bc filed at least 30 days before the planned date o#

abandonment of the temporary storage area.

2. TVA plans to use the cable warehouse and surrounding area for other plant operations following abandonment.

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APPENDIX A TVA PLAN FOR PEPJ1ANENT STORAGE / DISPOSAL OF ALL LOW-LEVEL RADIOACTIVE WASTE GENERATED BY TVA NUCLEAR PLANTS The plan for providing storage for all low-level radioactive waste from all TVA nuclear plants has the following three key points:

1. Design and construct temporary onsite storage facilities, if required.

2. Design and construct permanent (life of the plant) onsite low-level radioactive waste storage facilities at each nuclear plant site.

3. Design and construct low-level radioactive waste volume reduction / solidification facilities at each nuclear plant site.

The recent cutbacks in storage space allocations and the very real possibility of complete closure of all commercial disposal facilities requires immediate action to ensure continued plant operation. The actions we are taking are based on previous studies. For future plants beyond Browns Ferry, Sequoyah, and Watts Bar, we intend to implement onsite storage, as required, and volume reduction to coincide with plant need dates.

Our ultimate objective is to provide for the storage of all low-level radioactive waste generated by each of TVA's nuclear plants and to provide this storage through the plant life.

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Tcble V - 1 MAJOR ASSUMPTIONS FOR RADIOLOGICAL ASSESSMENT OF CABLE STORAGE WAREHOUSE FOR THE TEMPORARY STORAGE OF LOW-LEVEL WASTE AT BROWNS FERRY NUCLFAR PLANT General Type of Waste Miscellaneous LLW trash Maximum Total Activity 1320 Curies Isotopic Breakdown About 77 percent 2n-65, 6 percent 1-131, 4 percent Co-60, 4 percent Cr-51, 3 per-(typical) cent Cs-137, 3 percent Cs-134, and 3 percent other fission, corrosion and activa-tion products.

Dimensions of Ware- 15.2m x 91.4m (50 ft. x. 300 ft.)

house Releases During Normal Operation Under normal operation, all water entering the storage area will be collected and sampled before release. If the sample contains activity in a concentration > 1 x 10-7 p Ci/ml, the leachate will be collected and taken to the plant's liquid radwaste treatment system before release in order to meet Appendix I criteria. Therefore, impacts will be within Appendix I guidelines as the result of liquid releases during normal operation.

Accidental Release to River (via ground water)

Cause of Release An unspecified event causing complete degradation of collection curbs and sump, followed by a 10.2-cm (4-inch) rainfall.

Leach Fraction 100 percent of activity in the waste is assumed to leach out of the storage area and into shallow ground water.

400m (1,310 ft.)

~}h.TravelDistancetoRiver 1.5 m/d (5 ft/d) ps) Ground water speed

,4 g Total Soil Porosity 50 percent 1.6 g/cm3 Bulk Soil Density rs) Distribution Coefficients Leddicotte, et al., " Suggested Concentration Limits for Shallow-Land Burial of

'-J (Kp) Radionuclides," Tucson, Arizona, March 7, 1978.

'I3 Leachate Volume 1.4 x 108 cm 3 Rivet Dilution Factor 1.8 x 10-5 at nearest public water supply (17.7 km downstream).

Table V - 1 (Continued) -

MAJOR ASSUMPTIONS FOR RADIOLOGICAL ASSESSMENT OF CABLE STORAGE WAREHOUSE FOR THE TEMPORARY STORAGE OF LOW-LEVEL WASTE AT BRORNS FERRY NUCLEAR PLANT Accidental Fire Fractional Release 0.01 From Fire -3 3 Meteorology (fifth- 3.4 x 10 s/m perc entile ,1-hr ,

ground level X/Q)

Distance to Site 600 m (1,97n ft.)

Boundary Direct Radiation Exposure Rate from 700 mR/h - contact Each Drum Distance to site 875m(2,875 ft.)

Boundary Distances to Security 500 ft. - North, 260 ft. - West & East Fence

1. WASH-1238, DOE /EIS-0026.

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Table V - 2 .

SUMMARY

OF RitDIOLOGICAL ASSESSMENT FOR THE TEMPORARY STORAGE OF LOW-LEVEL WASTE IN THE CABLE STORAGE WAREHOUSE AT BROWNS FERRY NUCLEAR PLANT Release During Normal Operation Impacts will be within Appendix I criteria as the result of releases during normal operations.

Accidental Release to River (via ground water)

Maximum Radionuclide <1 percent MPC,1 Concentration at Nearest Public Water Supply Accidental Fire Air Subccrsion Dose at 7 mren (whole body)

Site Boundary Inhalation Dose at Site 100 nrc= (whole body)

Boundary 100 nrem (bone) 1,420 nrem (lung) 1,000 mren (thyroid)

Dose Guidance - 10CFR20 limits - 500 crea/yr to whole body, 3,000 aren/yr to thyroid, and 1,500 cren/yr to individual organs.

Direct Radiation Dose Rate at Security 0.6 tR/hr Fence 3.1 crem/yr CI) Direct Exposure at closest psy unshielded site boundary w g[ (40CFR190 Limit - 25 crem/yr)

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Table V - 2 (Continued) -

SUMMARY

OF RADIOLOGICAL ASSESSMENT FOR THE TDiPORARY STORAGE OF LOW-LEVEL WASTE IN THE CABLE STORAGE WAREHOUSE AT BROWNS FERRY NUCLEAR PLANT Curie Limit Maximum Number of Curies 13z0 Ci to be Stored in Cable Storage Warehouse

1. As defined in 10CFR20.

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