ML20077B923

Rev 3,to Process Control Program for Solidification of Radwaste

ML20077B923
Person / Time
Site:	Quad Cities
Issue date:	03/31/1983
From:	COMMONWEALTH EDISON CO.
To:
References
PROC-830331-01, NUDOCS 8307250498
Download: ML20077B923 (9)

Text

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e ID/TSI-I QUAD-CITIES STATION PROCESS CONTROL PROGRAM FOR SOLIDIFICATION OF RADIOACTIVE WASTE RE7ISION 3 MARCH 1983 l

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I. PURPOSE The purpose of this Process Control Program is to insure that all low level radioactive westes solidified at Quad-Cities Mielear Power Station are vold of any free standing water. This taanual sets forth the steps used to solidify radioactive vaste and to verify the final product is free of veter. Both the cement and DOW solidification systems are covered by this Program. Solid vastes at Quad-Cities Station consist of filter media (powdered resin and fiber) and bead resin. When expended, these unstes are transferred to various storage tanks.

II. SOLID WASTE SYSTEM DESCRIPTION The resin slurry is transferred to one of two centrifuges for dauntering. The centrifuges have a capacity of 25 gpm. The solids are separated from the unter and drop into a hopper associated with each centrifuge. The water is routed back to a storage tank.

Each hopper has a 40 cubic foot capacity. At the bottom of the hopper there is a hopper discharge valve. This is a remotely operated, air operated, f ail closed valve. Connected to the hopper discharge i

i valve is the sludge chute and the drum feed valve. The sludge chute

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is 8 inches in diameter and 6 feet 5 inches long, with a capacity of 2.2 ' cubic feet. The drum feed valve is also remotely operated, air l

i operated, and fail-closed. The hopper discharge valve and the drum 1

feed valve are interlocked to prevent both valves from being open simultaneously.

Cement is added to a drum fran the cement silo. The cenent silo has a capacity of 620 cubic feet. Cement is fed through a

s rotary- feeder down a transfer tube through the mixer haad, into the drum. The air.or goes into the drina and forms a seal to prevent dispersion  ;

of cement dust or spillage during mixing. The mixer has two speeds, 100 rpm and 200 rpm, that are programmed into the mix cycle.

Drums are capped at the load-out conveyor area before loading-

, into a shipping cask. A cao is set in place and a seal ring is snapped over it. A threaded bolt is used to tighten the seal ring.

Drim storage consists of three conveyor lines, with room for 25 drtais on each line.

III. OPERATION OF THE CEMENT SOLID WASTE SYSTEM In order to insure solidification of spent resins with no free water, tests vsre conducted at Quad-Cities Station using unspent resin. Fresh resins were mixed up in the proportions that would be expected to be normally processed. These resins were then put into a drum and the drum was processed through the cenent system. The , drum ,

ins capped as normal and allowed 'to set in storage for 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. ' <

Af ter 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, the drum was cut open lengthwise and inspected. The results of the inspection resulted in a change of the proportions of ,

water and cament until the final product was solid and free of unter. -

A series of drums were processed using spent resins, and-the drums were visually inspected for no free water prior to shipoing. No free water uns observed.

The general procedure that Ls followed to process spent resins is described below. Specific plant operating procedures are f ollowed by the operator.

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i. The septy drtan is covered with a plastic bag and taped in place to prevent external contamination.

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3. A half of a bag of dry canent is added to the empty drina.

,,C. The empty drums are loaded on a conveyor.

D '. Ons empty drum from the conveyor is loaded on a transfer cart

, (remote operation).

.- The transfer cart is advanced to the selected hopper station (remote operation) .

F. Water is added (remote operation). Normally 12 gallons of veter

! are added to each' drum. This amount can be varied if necessary for cczaplete solidification. The amount of water required is selected, and a flow integrator gives the inlet valve a closed

- signal when that amount is delivered.

G. The drum is filled with resins to a prescribed level (remote F

operation) . The resin is transferred from the hopper to the drum through the sludge chute.. The discharge valve on the sludge chute is a manually operated remote valve. The operator views

.the drtra through a mirror and fills the drum to the first roll s

hoop frcrt the top of the drum. Although this method of adding resin to the drum is not precise, it can be controlled to a high degree. If an operator determines that the quantity of resins variae from the prescribed level, he can compensate with water and/gr cement.

H. The drum is transferred to the mixing station (renote operation) .

I. The cement timer is set.

J. The mixer cycle (renote operation) is started. The mixe r lowe rs

' into the drum and foms a tight seal. The mixer will begin to

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, rotate at slow speed. The air slide blower and dust collector are started. The cement feeder and vibrators start and cement is

, metered to the drtm. The si:Eer incredses to fast speed. The cement feeder stops and the air slide blower and dust collector stop. When the mixer completes' the cycle, the RPM meter will start to decrease. At this point, the mixer control switch is moved fran AUTO. to FAST and the mixer is given an additional 5 minutes on fast speed. The switch is then returned to AUTO, and the mixer cycle is complete.

K. The $rtan is transferred to the inspection station (renote operatlod<',

L. The sized drum contact radiation reading are logged and the dontents of the drian are observed. If it is determined char more

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canent is required, the drum is returned to the mixer and additional l

catent is added. When the mix is satisfactory, the drum is

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/ transferred to the drum storage lines.

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j IV . VERI?IC ATION OF CEMENT SYSTEM SOLI 3IFICATION

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The solidified drum is verified to be void of free water prior co-

, loading into a shipping cask. The drum is transferred from the storage

,- lines to the load-out conveyor. At this point, the drum is visually verified to be void of free wa ter, the protective plastic Sag is

- removed, and the drum is capped. The drum is then surveyed for smearable ,

contanination and dose rate. The drum is then loaded into the shipoing cask.

If a drum is found to contain free wa ter, it will be noted as su ch. Dry cement will be added such that all of the free water is 4

absorbed or the drum will be recycled through the etixing line as required. The drum will not be shipped until all free water is absorbed.

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DOW SOLIDIFICATION SYSTILM DESCRIPTION The DOW Syste is utilized at the Station to augment and supplement the cement system. It offers the advantage of reduced radiation expoenre to operators involved with performing the necessary package handling operations.

The DOW Systen basically consists of a series of chemical additions to radusta sludge in a disposable mixing liner that also serves as the shipping container. These chemicals, namely the binder, CMC-7M filler material, Tamol, catalyst, and promotor, are mixed with the radweste and a water-free solidified mass is produced. Some radwaste may not need' CMC-7M for solidification, such as Cleanup Sludge.

Additions to the liner are made, through a fill head that fits over the liner.

A batching tank is utilized to collect the radwaste to be solidified.

The tank can be filled fra any of the following:

A. Condensate Phase Separators.

B. Cleanup Phase Separators.

C. Spent Resin Tanks.

D. Waste Sludge Tank.

E. Floor Drain Domineralizer.

Af ter the tank is filled with radvaste, a decant pump is used to remove water frcza the top of the settled sludge. '4 hen the decanting operation is completed, the tank contains about 1,900 gallons of sludge.

The mixing tank is operated on recirculation in order to allow a tank sample to be takan for analysis and sample solidification tests.

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A binder tank is located underground west of the Unit 2 L.P.

Heater Bay. A binder pump is used to pump the binder from the tank to the liner. Radweste is transferred to the liner from the mixing tank by means of a radunste pump. Flushing capability exists on these lines. Air-driven pumps are used to pump catalyst Tamol, and prcmoter to the liner. CMC-7M is a solid that is manually added to the liner, if needed.

A temperature monitor in the liner is used to note the raximum temperature during the exotherm. At this point the waste is solidified, and the liner is prepared for shipment.

VI. OPERATION OF THE DOW SOLIDIFICATION SYSTEM A liner is prepared for use by installing a thermocouple and adding CMC-7M (if necessary) . The fill head is placed over the liner and locked in-place. The fill head off-gas ventilation blower is started.

Binder is added to the liner. A batcher is set for the proper amount, and the binder is pumped frce the tank. The CMC (if added) and binder are then mixed for about 15 minutes, and Tamol is then add ed. The proper amount to be' added is set on the hatcher.

The radwaste is then added to the liner. The mixing tank is first mixed for about 10 minutes. The proper amount of raduaste to be l

( pumped is set on the cointer on the radunste pump. Waste flow to the liner is monitored by a TV camera, and the liner is mixed for about 5 l minutes af ter radwaste has been added to the liner. The radwaste nipe i

lines and waste transfer hose to the fill head are then flushed.

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Catalyst is added to the liner. The proper amount is set on the I batcher. The liner is then mixed for about15 minutes. Promoter is added af ter having set the proper mount on the batcher. After mixing, the temperature of the emulsion is monitored and the maximum temperature is noted. Af ter the taperature begins to decrease, the fill head is removed.

The liner is then covered with a lid , secured , surveyed, and shipped.

VII. VERIFIC ATION OF DOW SYST'JM SOLIDIFIC ATION Verification of solidification first involves sampling the raduaste prior to solidification in order to determine the proper proportions of the chemical ingredients that will produce an acceptable, unter-free solid. A representative laboratory sample of waste is taken frcm the sampling line. Small, scaled-down amounts of chemicals are added. in the lab in proper quantities. The quantities depend on DOW Co. recommendations and on the type of raduaste to be solidified. Staticn procedures shall specify these quantities. The following process is then perf ormed:

A. Weigh CMC (if to be used) and binder into a disposable container.

B. Start mixer. Adjust to good vortex.

C. Add Tamol. Observe color change from anber to silvery wh ite .

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t E. Slowly add radioactive waste while .aintaining a good vortex.

Observe the mixing action to ensure emulsification has occurred.

F. Continue adding renaining radioactive unste to the nix. As the mix gets more viscoua, lower the container to :naintain a good vo rt ex .

i G. When all the waste has been added, continue mixing. Emulsion f .-

I' should be light-colored, high viscosity and homogeneous.

H. Add catalyst and mix.

I. Add promoter. Start stopuntch and mix.

J. Remove sample from mixer.

K. Insert taiperature monitoring probe. Determine gel time by probing periodically.

L. Record appropriate amounts of chemical used on data sheet.

M. Stop timer when gelation has occurred.

N. Record maximum exothern on data sheet. If the gel time and temperature change are acceptable, write up appropriate formulas and scale-up numbers for use in the plant. Solidification of the sample is hereby verified. If solidification is not acceptable.

take another radwaste sample and adjust concentration of ingredients such that solidification is verified.

The scale-up numbers are those 92antities and proportions of CMC-7M, (if needed) Tamol, radweste, binder, promoter, and catalyst that are to be actually used in the process of solidification. These numbers are converted to settings to be placed on the batchers and pump counters.

To 62rther verify solidification, a- quality check of the liner is performed prior to installing the lid. Both a visual inspection and a penetration probe are performed. The visual inspection verifies no free-standing unter, and the surf ace resistance to penetration verifies a solid nass.

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