D

Experimental Boiling Water Reactor Decontamination and Decommissioning Project

Charles Fellhauer Technology Development Division

Argonne National Laboratory

Presentation to Duke Engineering and Services, Inc.

Charlotte, North Carolina

May24,1995

DISCLAIMER

Portions of this document may be illegible in electronic image products. Images are produced from the best available original document.

Waste Packaging

Bins designed for high-density waste used for metal and bioshield concrete

Voids in all bins filled with compactable trash

Simple, inexpensive hoods allow trash placement with HEPA ventilation protection

Special liner used for core support plate

Hardware baskets designed for easy handling, rapid draining

Shields designed with remotely operated winches for control rods, hardware baskets, and 55-gallon drums

Reactor vessel head and index plate (37,900 lb)

S tee1 and concrete shield blocks (35,000)

3,000 lead bricks (134,500 lb)

DISCLAIMER

This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsi- bility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Refer- ence herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recom- mendation, or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof.

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conservatively

Expand use of scheduled bioassay

Ensure bioassay data reach key managers in timely fashion

Lessons Learned: Prevention and Early Detection (cant.) Lessons Learned: Prevention and Early Detection (cant.)

Establish personal protective equipment levels

Investigation committees should be preselected, trained, and dedicated to the investigation function

Improvement in recovery procedure roles is desirable

“Surge” analytic capability is needed for sample analysis

Lessons Learned: Management Issues

No clear consensus on balancing internal exposure against other health and cost variables

Facility definition criteria must be clear and promptly communicated so that lab can accurately categorize and update facility status

Lessons Learned: Noteworthy Practices

Prompt response by lab project manager mitigated exposure

w Entry and exit bioassay data were extremely valuable

a Archiving of air samples was key to dose assessment and event reconstruction

Excellent record keeping helped in understanding and reconstructing events

c ANL-E Exposure Control Enhancement Highly Effective

Since restart at EBWR, all bioassay data have been negative

D&D Lessons Learned I II

Maintain continuous safety presence at job site

rn Use your data base on past costs for estimating

m “Niche” contractors can be very productive

m Continuously use your lessons learned

For technical information on the EBWR D&D project, contact Charles Fellhauer, Reactor D&D Technology Center, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439. Phone: (708) 252-9569; Fax: (708) 252-9274.

For information on the Reactor D&D Technology Center, contact Sam Bhattacharyya, Reactor D&D Technology Center, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439. Phone: (708) 252-3293: Fax (708) 252-4007.

Disclaimer

Argonne National Laboratory is operated by The University of Chicago for the US. Department of Energy (DOE) under contract No. W-31-109-Eng-38. Accordingly, the US. Government retains a non-exclusive, royalty-free license to publish or reproduce the published form of this contribution, or allow others to do so, for U.S. Government purposes.

This publication was prepared as an account of work sponsored by an agency of the US. Government. Neither the US. Government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the U S Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the US. Government or any agency thereof.

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Background Informa tion Argonne National Laboratory’s (ANL’s)

Experimental Boiling Water Reactor (EBWR) was a fully operational facility built to demon- strate an integrated power plant that used a direct-cycle boiling water reactor as a heat source. Initial operation began in 1956 with a 20-MW(t), 5-MW(e) design. EBWR was upgraded for operation up to 100 MW(t) and recommenced operation in 1962. The EBWR was used in the Department of Energy’s (DOE’S) Plutonium Recycle Program, which studied the use of plutonium as a fuel in light- water thermal systems. The plant was shut down, defueled, and placed in dry lay-up in 1967. The decontamination and decommission- ing (D&D) of EBWR began in January 1986.

Work Progression Phase I of the D&D consisted of planning the

project, developing budgets and schedules, and assembling the work group. The first major task was to remove 2,600 cubic feet of asbestos piping insulation from the EBWR facility. Phase I was completed in 1988.

Phase I1 was devoted to the removal of the turbine-generator system, condenser and circula- tion water systems, filter systems, demineralizers, and all steam piping. Reactor systems were removed and size-reduced for packaging with conventional power tools and oxyacetylene torches. Personnel exposures were easy to manage because of isotope decay during the 21-year safe storage period that the facility had gone through.

Decontamination (by means of sandblasting) of larger equipment items, such as the condenser and turbine units, was very effective. These decontamination efforts released about 90 per- ~

cent of these components to a commercial metal recycler. The spent-fuel pool was also high- ~

pressure, water-sprayed cleaned; drained; and repainted. A thorough, general clean-up of the entire four levels of the EBWR plant was performed.

(See Figure 1 for an overall view of the EBWR facility.) This phase of D&D was completed in late 1989.

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Experimental Boiling Water Reactor Facility

Preparation for Phase 111, removal of reactor internals, included the design and construction of a water filtration and transfer system for the fuel pool and a high-efficiency particulate air (HEPA) system near the reactor vessel to filter out air- borne radioactivity during cutting operations.

Phase III-A D&D activities began in March 1994. ALARON Corporation was contracted to provide the personnel and equipment to perform the remaining D&D work. During March, the control rods and the reactor core assembly were removed from the reactor and placed in the fuel pool for size-reduction and packaging. The core assembly had a maximum contact dose rate reading of 200 Roentgedhr.

The underwater size-reduction of the reactor core assembly began in April 1994. This work was carried out underwater in the fuel pool with a plasma-arc-torch system. All remaining reactor internals (steam ducts. shock shields, thermal shields, experimental appendages, etc.) were removed from the vessel with a plasma arc torch

Inside Surface:

Outside Surface:

and transferred to the fuel pool for size- reduction. All nozzle penetrations into the reactor vessel were removed by using a WACHS Technical Services (WTS) split-frame pipe cutter. A manway was cut in the reactor vessel wall through the lower pipe access to provide access to the cutting equipment.

Size-reduction activities (Phase III-B) continued in the fuel pool during May 1994, when the cutting and removal of the reactor vessel were completed. WTS accomplished the vessel segmentation by using a split-frame, inside-diameter cutting machine. The vessel bowl cut was done first and the bowl piece removed. The vessel barrel was cut four times to produce five ring segments. Each ring was lowered to the bottom of the vessel cavity. After all cuts had been completed, the top vessel ring was then removed and staged in a holding area on the fourth level of the containment building. (See Figure 2 for cut locations and vessel dose rate information.)

Section 1 Section 2 Section 3 Section 4 Section 5 Section 6 30 500 300 30 10 5

4 40 15 5 3 1

@ 54.178 - 54.622 54.622 98,622 58.622

Section #2 T Section #3 l- -- Section #4 -T- Section a5 Section #6 1

Contact Dose Rate (rnR/Hour)

The other rings were removed, the last ring being placed in the cutting tent for additional size- reduction. The reactor cavity was then cleaned in preparation for concrete coring operations and cavity liner cutting and removal.

During June 1991, reactor vessel ring-size- reduction and packaging were completed - two weeks before the DOE-Headquarters

scheduled date. The reactor cavity lower shield plug was removed, and concrete core bores of the bioshield were obtained. An abrasive water jet was used successfully in a SO-foot- (15 meter-) long test cut. (Table 1 gives performance data for each method of cutting the reactor vessel. Table 2 shows metal-cutting methods used at the EBWR.) The WTS split-frame, inside-diameter cutting

Comparison of the Three Cutting Methods Used for Size-Reducing the EBWR Reactor Vessel

Table 1 Cutting Methoc

WTS vessel-cuttin1 machine (mechanical)

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Flow jet. high-pressure watt grit cutting system

Oxy genlacety lene cutting torch

Cutting Speeds

A total of 197" with one vertical cut over 4" deep was made on the bottom bowl in 18 hours, for a cut rate of 0.18"lmin (most difficult cut). A total of 1056" with 4 horizontal cuts 2.5" deep was made on the remainder of the vessel in 22 hours, for a cut rate of 0.8"lmin.

A total of 540" with 12 cuts 2.V deep was made on a section of reactor vessel In 679 min, for a cut rate of .795"/min. These cuts were performed to test the ability of a water jet system to segment an irradiated reactor vessel.

Numerous cuts were made on the 2.5"-thick reactor vessel rings that had been segmented with the WTS vessel- cutting machine. The torch was mounted on a track system, which allowed cut rates of up to 12"lmin.

Advantages

Due to the presence of stainless-steel wool on the outside of the vessel, a mechanical cutting method was selected over flame cutting. This provided a smokeless, clean cut on the vessel and generated very little rad waste. Set-up was reiatively easy, and remote operation was available during actual cutting operations.

The flow jet produces a high-quality cut and can be set up fairly rapidly after initial equipment set-up and testing. When utilized with a track system, it allows for remote Operation by the operator.

The system provided a fast, inexpensive method to size-reduce the reactor vessel rings into pieces, which were packaged into accept- able disposal pack- ages. The equipment was easy to operate and allowed remote operation after set-up,

Disadvantages - Each large cutting machine is custom-built for each application. This results in a large fabrication expense fw the equipment. Trained operators are requiraIl for operation, and - hands-on assembly iE required during set-$,

The equipment is -- relatively expensive am requires trained operG tors for set-up and operation. Control of the overspray Is extremely dmicult. A relatively laze amount of rad waste - was generated in the form of water and garnet (grit). Depth-of-cut control was not possWe a6 was evldenced by the holes cut in the water1 grit collection drums and spray deflector plates.

HEPA ventilation and smoke control were required. The operator was requfred to physi- cally perform a hands& set-up after each cut. Fire watch and heat stress monitoring werer" required during the *

cutting operations. -."

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EBWR D&D Project Metal-Cutting Methods Table 2

CuttinaMethod I ComPonents Cut Advantages Disadvantages Requires HEPA ventilatlon/containm&'% for smoke.

PAK 45 (dry) plasma arc

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Thermal shields, reactor vessel lugs.

Fast, cuts up to 4"-thick stainless steel.

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PAK 45 (underwater) plasma Brc shields, control rods

Core assembly, thermal

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PAK 10 (dry) plasma arc

Steam duct, feed-water and spray rings, miscella- neous stainless steel

Remote underwater cutting, smokeless.

Requires water -: treatment for water qualitylclarity. Remot$ handling difficult - without guides or manipulators.

Fast, cuts up to I"- thick stainless steel.

Requires HEPA --. ven tilation/containmd% for smoke.

Oxygenlacetylene torch Reactor vessel, reactor cavity liner, miscellaneous carbon steel

Easy to use, inexpensive, good cut quality when used with a track system.

Requires HEPA ventIlation/containm&t for smoke. -

Easy to use, Inexpensive. Requires HEPA ventilation/contahmeR for smoke; does not bum as hot as Q

acety ien e. a

WTS vessel-cutting machine

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Reactor vessel, reactor cavity liner

Smokeless. limited waste, remote operation, exceltent cut quality.

Expensive (each '* ~. machine is specially + built): requires trained operators; set-up can - be difficult. ii * -ilt..l

WTS split-ring rnach in es

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Reactor vessel nozzles Smokeless, limited waste, remote operation, excellent cut quality.

Requires trained I

operators. . _

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WTS rail mill Shield plug liner, reactor cavity liner

Easy to use, qulck set-up, smokeless, excellent cut quatity.

Requires trained -- operators; welding I_

required during set-up~ on vertical and overhead applications,

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Flow-jet water system Reactor vessel Smokeless, relatively easy set-up after initial installation; excellent cut quality; relatively remote operation.

Messy, high waste- - water generation. Unable to control dep& of cut (cut through splash plates and watt# collection drums). i Requires trained 1" operators: extremely high-pressure water, elaborate containment- and water collection/ filtration equipment required. Expensfve. -

Inexpensive, easy to use, readily available, smokeless.

Pipe cutters, saw-z-ah, porta-band saws

Misceltaneous carbon steel pipe and metal

_ _ Limited applications, - non-remote operation. I

dose rate reading of 200 Roentgedhr. The remaining reactor internals were removed using a shielded man basket in the reactor vessel. All reactor nozzles were cut flush with the exterior of the reactor vessel to facilitate vessel removal operations.

Phase III-€3, In May 1991, reactor vessel removal began in parallel with the activities discussed in Phase 111-A. The thermal shields were reduced in size and packaged. The reactor vessel was segmented into rings about five feet high, each weighing approximately 13,000 pounds. Once removed, these rings were placed in a containment tent and cut vertically by a track-mounted oxyacetylene torch. The resulting pieces were then packaged in metal containers for shipment to the U.S. Department of Energy (DOE) disposal site at Hanford, Washington. During work on the reactor vessel, a crew at the fuel pool continued to reduce the size of core internals and package them.

The 32-ton reactor cavity shield plug was removed by using a remote-controlled, electro- hydraulic impact machine. Phase 111-B was completed 16 days before the DOE - Headquarters scheduled date.

___ investigative time and operational chnnges associated with restart of the project, the incident provided a valuable lesson in planning for the unforeseen. The project required entry and exit bioassays for all contractor D&D workers. Contractor personnel leaving the site in July had positive bioassay results for tritium. Additional bioassays revealed isotopes not previously found, including fission products and transuranics, mainly Cs137, Sr90, and Am241. Twelve workers- had positive bioassay results for Am241 - an alpha-particle emitter with a long half-life that is known to accumulate in body tissues. The maximally exposed individual had 300 millirem of radiation exposure.

Through careful analysis of 250 air samples correlated to work progress, Am241 was detected in the corrosion layer of reactor hardware in the ~

fuel pool. The concentrations of Am241 were below the detection capability of field instru- ments and only became a potential hazard because of plasma-arc-cutting operations.

After this potential hazard had been properly addressed, work restarted in the fuel pool in February 1995. Size-reduction and packaging of reactor hardware were completed in May 1995.

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Bioshield concrete removal operation. Phase IV - Bioshield Removal (July 1994 -December 1994)

liner, were removed from the reactor cavity bioshield. An additional 900 cubic feet of activated concrete were also removed from the bioshield.

In all, 3,000 lead bricks, as well as the steel

Coping with the Unexpected

stopped all D&D work because of positive bioassay results among the workers. Although this incident cost the project five months of

In early September 1993, the project manager

Planned Work Removal of the D&D support systems (water ~

filtration and HEPA systems) is scheduled to be ~

completed in May 1995. Facility decontamina- - tion and final surveys are scheduled to be completed in July 1995. Project close-out activities and waste shipments should be completed in September 1995.

project is approximately 19 person-REM.

cost at completion is $13,595,000.

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Total estimated radiation exposure for the

Total cost to date is $1 1,941,000. Estimated L

Contact For technical information on the EBWR

D&D project, contact Charles Fellhauer, Reactor D&D Technology Center, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439. Phone: (708) 252-9569; Fax: (708) 252-9274.

ogy Center, contact Sam Bhattacharyya, Reactor D&D Technology Center, Argonne National

Illinois 60439. Phone: (708) 252-3293; Fax: (708) 252-4007.

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For information on the Reactor D&D Technol- ~

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- Laboratory, 9700 South Cass Avenue, Argonne, ~ __

- Argonne National Laboratory is operated by

The University of Chicago for the U.S. Department of Energy under contract No. W-3 I- 109-Eng-38.

machine was used to segment the steel cavity liner. A total of 35,000 pounds of concrete and 7,900 pounds of steel was free-released for recycle or scrap. Size-reduction continued in the fuel pool.

Phase IV began in July 1994 with removal of the reactor cavity liner. Approximately 3,000 fifty-pound lead bricks were removed from the bioshield. About 89 percent (134,000 pounds) of this lead was surveyed and free- released for recycle. The lead was smelted and formed into shield blocks for use in ANL's Advanced Photon Source. Size-reduction of core intemals continued in the fuel pool. Thirteen drums of remotely handled, irradiated reactor hardware were removed from the pool. The contact dose rate ranged from 1 to 9 Roentgedhr for these drums.

Removal of the activated portion of the bioshield concrete began in August 1993. This work was accomplished through use of a BROKK 250 electro-hydraulic, remote- controlled impact machine. One retention tank was removed from the first level of the containment building and placed in the cutting tent for size-reduction and packaging.

Work continued until September 9, 1993, on size-reduction of irradiated hardware in the fuel pool. On that date, the project manager stopped all D&D work at the EB WR because of positive bioassay results. Twelve workers had Am241 uptakes, and nearly all workers had some mount of tritium uptake. An investigation into the cause of these internal exposures continued through Decem- ber 1993. Since adequate data were available by early November to indicate that the source of Am241 and H3 was in the fuel pool, limited work was allowed in areas not related to the fuel pool. The activated portion of the concrete bioshield was removed during November and December by means of the BROKK machine. Approximately 50,000 pounds of activated concrete were removed. (See Figure 3 for a diagram of the cavity concrete removal . )

an Argonne Operational Readiness Review (ORR) for restarting D&D activities at the EBWR.

During J a n u q and February 1995, the project completed a DOE ORR. Work resumed on February IS, 1995. With the removal of recirculation pipes from the reactor cavity walls, a radiological survey of the cavity was begun.

In December 1994, the project completed

In March 1995, six baskets of irradiated hardware were removed from the fuel pool and packaged for disposal. Contact dose rates on the baskets ranged from 2 to 200 Roengtehr.

Packaging of reactor intemals was completed in May 1995, and work began to decontaminate the fuel pool 'and dispose of the water.

Schedule The EBWR project is about eight months

behind schedule because of the five-month investigation of Am241 exposure and the result- ing requirement that the remaining tasks be performed in series rather than in parallel.

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Future Program Adequate funding to complete the project in

FY95 is expected to be available. Facility decontamination and final surveys are scheduled to be completed in July 1995.

Activity Assessment Analytical data were obtained from samples of

internal components, the reactor vessel, bioshield concrete, and bioshield lead. These data were

used to develop scaling factors to allow the use of the C060 one-meter dose rate to calculate the activity of the other isotopes in the waste package. This method of estimating the curie content of waste packages was reviewed and approved by the waste disposal site operator.

Decontamination

taminate and free-release the reactor vessel closure head. This metal was released for recycle. Bioshield lead bricks were not contami- nated; the majority had no detectable activation. A total of 134,000 pounds of lead was released for recycle.

Disc grinders and drills were used to decon-

Cutting Techniques Cutting of reactor vessel internals underwater

with a plasma arc was done satisfactorily, but not without some problems. As conductivity increased in the fuel pool, the operator was unable to strike an arc or even maintain an arc underwater. Consultations with the plasma arc manufacturer led to the use of an argon-hydrogen gas mixture, with satisfactory performance.

The need to protect workers from electrical shocks led to insulation of pool handrails and surrounding flooring, along with the use of nonconducting tools. Plasma-arc cutting released small amounts of radioactivity from the corrosion layer of irradiated hardware in the pool. These small amounts, below the detection thresholds of conventional field instruments, were not detected during the work and resulted in worker uptakes of Am241, H3, C060, SPO, and Cs137. These uptakes were detected only because of the additional sophistication of entry and exit bioassays.

Remote Operation The remotely operated BROKK machine

performed very well overall during removal of the 12-ton reactor cavity shield plug. Once the impact work was completed, the machine 'arm was fitted with a bucket scoop and used to load the high-density concrete rubble into 68-cubic- foot shipping containers. The same machine was used to remove activated concrete from the bioshield. A few mechanical problems with the equipment were experienced, and the final 50,000 pounds of rubble had to be loaded manually into waste containers.

Two transfer shields were used in the packag- ing process for irradiated hardware. Each was equipped with a remote pendant-operated switch. One shield was used to lift hardware baskets

from the fuel pool and shield them during transfer to the other shield, which held an empty 55-gallon (200-liter) drum. The drum shield provided shielding during drum-closure operations and during transfer of the drum to the trailer-mounted storage cask. Each shield was constructed at Argonne to provide four-inch lead equivalent shielding to operating personnel. The shields performed as intended; personnel exposure was acceptable for the packaging operations.

Radioactive Waste Management Containers of radioactive waste are being

transferred to the ANL Waste Management Operations Group for shipment to the DOE - Hanford disposal site near Richland, Washington. Containers of mixed waste are also being transferred to waste management for shipment to Hanford for storage. Over 2,600 cubic feet of contact-handled, low-level waste have been shipped to Hanford for disposal. Nineteen 55-gallon drums of remote-handled, low-level waste have been transferred to waste manage- ment for shipment to Hanford. All these wastes contain over 550 curies of radioactive materials.

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Health and Safety Over 5 1,000 man-hours of work were com-

pleted between April 1991 'and the end of March 1995. There has been only one OSHA- reportable injury, and there have been no lost time incidents, no personnel contaminations, and no cases of overexposure to ionizing radiation. Total project radiation exposure to date is 13.4 person-REM compared to a planned total project exposure of 18.9 person-REM.

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Project Management The project is fully staffed with a project

manager, a project engineer, and a project secretary. This staffing provides the necessary oversight and direction to the D&D support service contractor. The support services contrac- tor has 13 employees on the job site performing D&D tasks. Subcontractors were used for vessel- ~

cutting and concrete demolition work.

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costs Total cost of the project is estimated at

$1 3595,000. Actual costs to date are approxi- mately $1 1,93 1,000.

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Qtr I, 1994 rask Name Duration Start Finish Dec Jan I Feb I Mar Apr

__ 12120193 + 1 m E B Contract Award

Premobilization

Procedures

Engineering 8 Fabrication

Training

Mobilization

Advance Site Set-up

Crew Travel

Site Training & Set-up

iemove Reactor lnternals

Remove Control Rod Blades

Remove Core Assembly

Remove Remaining lnternals

Size Reduce & Package Rx lnternals

Start Size Reduce & Package lnternais

Americiam Investigation & Restart Activities

Complete Size Reduction & Packaging Rx lnternals

bmove & Package Rx Vessel

Remove Nozzles

Remove Rx Bottom

Segment Rx into Rings & Remove

Size Reduce & Package Rx

Lmove & Size Reduce Bioshleld '

Perform Core Bores

Remove Bottom Shield Plug

Remove Rx Cavity Liner

Remove Lead

Start Bio-Shield Concrete Removal

Complete Concrete Removal

temove & Decon Systems

Remove Water

Remove Systems

Decon Areas

Remove HEPA System

'erform Release Surveys & Demobilize

'repare Final Report

w 65d

6w

85d

9d

27d

15d

I d

I l d

2 l d

5d

2d

13.5d

275d

114

112d

49d-

49d

8d

2d

1 4

25d

152d

3d

15d

19d

21 d

15d

3w

33d

5d

14d

I l d

6d

3w

42d

12120/93

1 2/2iE3

12/20193

2/1/94

2/14/94

2/14/94

3/7/94

3/8/94

3/23/94

w m 4

m/94

41 /94

415194

4/5/94

911 2/94

2/15/95

4/21/94

4/21 194

Ei13/94

5J594

5/25/94

5/25/94

5/25/94

mm 6 / 2 w

711 5/94

811 5/94

11/11/94

4/25/95

4/25/95

5im

Y l 7 B

6/1/95

6/9/95

7/21 B

3/18/94 1; 3/11/94 !I-_

3/22/94

4120194

3/29/94

3131B4

4rrmgq

4124195

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