laboratory for Remote Analysis of Highly Radioactive Samples F. W. DYKES, R. D. FLETCHER, E.
H. TURK, J. E. REIN,
Atomic Energy Division, Phillips Petroleum Co., ldaho
The function of the Idaho Chemical Processing Plant is to recover enriched uranium from expended fuel elements from various types of reactors. The Remote Anal? tical Facility provides facilities for chemical research on extremely radioactive materials and for around-the-clock analytical service for operation of the processing plant. This paper describes the general Imilding la?-out and some typical remote analytical apparatus.
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HE Remote hnalytiral Facility, part of an expansion program at the Idaho Chemical Processing Plant, was coinpleted in May 1955. It provides new facilities both for technitaai development uf new processes dealing with expended fuel elements and for analytical process control. The building. of reinforced concrete, was coiidructed adjacent to the main plant. Its area of 88 by 83 feet is divided into three parallel areas shown in Figure 1. The first contains analytical laboratories, the second decontamination apparatus, and the third a multicurie cell. All three areas open into a main corridor which is parallel t.o and connected with the hot sampling corridor of the main plant.
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analytical laboratories. A paper devoted exclusively to thtl multicurie facility is now in preparation. The analytical area contains both a remote laboratory and ii conventional laboratory. The remote laboratory consists of t,UYJ parallel lines of Berkeley-type hoses. .I heavy shielding nail extends the lengt'h of each line, protecting the analysts who operate the equipment that is within the boxes. The equipment is operated by three means: hand-operated manipulators extending through the shieldirig, pneumatic controls, and electronic* controls. Figure 2 is a photograph of these lines, and Figure 3 is a cross section through the lines. The conventional laboratory is located on the second floor of the Remote Analytical Facility, directly above the remot,e lines. It serves two main purposes: analysis of samples that do not demand shielding protection and esecution of preliminary processing steps for analyses carried out in the remote lines. In a few cases, final processing steps are performed in the conventional laboratory after the constituent to be analyzed is separated from the fission products in the remote line. A photograph of the conventional laboratory is shown in Figure 1. REMOTE LQBOR-ITORY
General Features. The basic unit of the remote laboratory is the analytical box, one of which is qhown in Figure 5 . These boxes, constructed of Formica-covered plywood, are approsimately 3 feet on edge. They are remotely replaceable in the line The top half of each box face, slanted back 15O, has a rectangular glass-covered cutout. A4high-density window in the shielding wall fits this opening, providing the analyst with a good view of the equipment within the bos. The bottom half has two smaller cutouts into which the hand-operated manipulators fit There is still a smaller opening, between the manipulator openings, which provides access to the box for control rods and reagent lines. The floor of the box is covered with a metal tray in which there is an opening with a hinged door. Samples, glassware, and other material are passed into and out of this opening from a dolly traveling on rails below. A drain, for contaminated liquid waste, is located at the rear of the box. Two sodium vapor lamps are mounted on top of the box above small windows. One provides sufficient illumination, the other is standby. Inside each box is a panel providing 110-volt regiilated, 110-volt unregulated, and 220-volt power. Seven AN-type connectors of various sizes are fastened to a second panel. These provide a total of 52 wires for instrumentation. Figure 6 is a photograph of the inside of a box showing these panels.
Figure 1.
First floor plan of Remote inalytical Facility
This paper is concerned mainly with the analytical laboratories. The decontamination area is briefly discussed later. The multicurie facility is dmigned to handle 5 X 10' curies of 1.6-m.e.v. gamma or 1.5 X lo3 curies of 2.55-m.e.v. gamma activity, as well as irradiated plutonium. This area will be used for investigation of new processes involving uranium recovery from spent fuel elements and the utilization of specific fission products from both uncooled fuel elements and from various plant process streams. The multicurie cell is not described in this paper, for the functions of this facility differ greatly from those of the
Utilities piped into the box ai'e water, vacuum, compressed air, propane, nitrogen, hydrogen sulfide, and a water drain. A411 utility piping and electrical and instrument conduits rise vertically from the box, make a right-angle bend, and terminate at quick disconnects in line with the box front. Each box is equipped with pneumatic windshield wipers for cleaning the viewing window. Air flows through the box at the rate of two changes per minute. It enters through a 1-inch-thirk fiberglass filter a t the rear of the box and is pulled out through a :%inch duct a t the top. Sixteen such boxes are in each of the two remote lines. Figure i also shows that these lines extend from the main corridor that connects to the main plant to an 8-foot-wide passageway at the opposite end of the new facility. Vertical H-beam columns are spaced along the lines behind the shielding. Heavy angle iron guides fastened to these H columns support the boxes in position. 1084
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locations. A beam of light froin the snmple dolly lights these to designate the ice cream carton in line with the rectangular opening in the bottom of the box. Both the box and sample dollies are electrically controlled from combined control stations. These stations are located on the shielding wall between each box, as can be seen in Figure 11.
Figure 3.
Section throueti remote laborator)
Boxes are replaceable and are transferred by remotely operated dollies that travel on 2-fooegage railways behind each line. Figure 8 shows a box being placed in B line. The dolly is positioned by controls on the shielding face, two rods are inserted through holes in the shielding and screuwd into receptdes on the box, and the box is pulled into position along the angle guides. The box dolly rails run to the a f o o t pssssgeway, change direction by means of turntables, and terminate in the decontamination area. Here boxes are cleaned of activity and reassembled for future use. Two additional railwayys, one for each line, &re located beneath the box positions, a8 shown in Figure 9, and extend the length of the remote lines. Sample dollies, as shown in Figure 10, travel these rails. These dollies provide the means of transfer between boxes. Samples, reagents, glassware, and solid waste are t r a n s ferred in special holders the si%eof 1-quart ic8 cream cartons. Each dolly can carry six cartons. A stainless steel trough extends the length of each line. Contamination resulting from a spill can be washed to drainage with nitric acid and water ejected from a perforated pipe. Six Lucite rods extend through the shielding a t each of the box
Figure 5.
Analytical box and its cradle
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Ficure 6.
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Box electrical and instrument panels and remote pipetter
Pairs of castle manipulators are set in the shielding. These can be seen in Figure 11. The body of these manipulators is made of lead to provide shielding protection equal to the permanent wall. The manipuliLtor tong e m be rotated 45' about the vertical and horizontal center line of the manipulator. The tong can be unscrewed from the tong end by means of a special holder mounted on the rear rvdl of the box. This allows for remote installation or removal of 8. box even though the manipulator openings are sealed by flexible, air-tight tygon tubes and bellows. Figure 12 shows hour the tube section encloses the tong and the connection of the bellows to the box front. A removable lead plug serves t o seal the smdl opening between the manipulators. This opening, as previously mentioned, provides access for mechanical control rods and reagent lines t o the box. The lead plug usually is constructed with passageways for the tubes and rods. Six feet above floor level the shielding narrows to 4 inches, and is recessed 21 inches to form a utility chase. Sliding doors, shown in Figure 11, provide an easy means of entry to the chase. When a box ia pulled into position, its piping and conduits fit into holes in the 4inch shielding. Hanson disconnects serve to engage the
The sample dolly circuit has an automatic interlock which inactivates all control stations except the one in use. A small, hand-operated conveyor is a1.w installed which serves only the first four boxes. These boxes are used more than are the remaining 12, especially for incoming samples. The line shielding is designed to reduce the rsdiation from 8.35-roentgen-per-hour source of 2.18m.e.v. gammaintensity12inchesfrom theinnersurface to a maximum of 1 milliroentgen per hour a t the outer surface. The shielding, in general, consists of a 9-inch-thick wall of high carbon cast iron (meehanite) with 2 feet of concrete above and t o the rear of it. Cross sections of this shielding are shown in Figures 3 and 9. Boxes are separated by 2 inches of lead. The viewing window set in the shielding is made of high-density glass.
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Figure 8. Installation of analvtieal
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1087 Air enters the operating d e from ceiling vents and leaves a t floor level through grills in the line shielding. It then passes to the rem of the boxes, and, a8 pw4ously described, is pulled through and out the top of the boxes. It is finally discharged to the atmosphere through a stack. The air flow through the operating aisle is a t the rate of ahout ten changes per hour. Box Functions. Each box fulfills a specialized function. The one nearest the main corridor is called the feed-end box. It serves only as a transfer area. As shown in Figure 13, plant samples in lead pigs are brought into the main corridor on manually operated trucks. A sectioned lead door in the corridor wall provides access to the line. The operator aligns the truck rails with rails beneath the feed-end hox and pushes the lead pig in, The samples, in 5-ml., cone-shaped, glass bottles, are removed with a manipulator. They are then transferred, usually via the hand-operated conveyor, t o one of the next twn hole* far storage.
Figure 9.
Section through remote line
Figure 11.
Remote line
A dumbwaiter connects the feed-end box t o the conventional laboratory above. This dumbwaiter, with 8. capacity of four I-quart ice cream cartons, provides the means by which reagents, glassware, and other materials are transferred into the remote lines and by which treated samples free of fission products me passed upstairs for further processing. Each of the two Etomge boxes contains a heavy, cast iron rack which is seen in Figure 14. Each rack provides storage, as well
iodium vapor nectors. The just benesth
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ical apparatus e. As can be bppearance. contaminated the two lines.
Figure 12.
Manipulator tongs inside box
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pulls, by vacuum, the solution into a liquid trap. The liquid trap is equipped with electronic controls which empty it to drainage when it fills to a certain level. The remaining 13 boxes in each line are standard units which are equipped with specialized analytical apparatus. Each box Serves for a different analysis. Examples of Analytical Equipment within Boxes. REMOTE PIPETTER A sample pipetter is installed in the first standard box (Figure 6 ) . This pipetter is a positive displacement, servomotor type patterned after the models originally installed in the Chemical Processing Plant by the Oak Ridge National Lahoratory. Various receptacles, such as sample bottles, test tubes, and beakas, are positioned beneath the delivery needle by means of a slide. The slide is moved by a manudly operated rod passing through a lead plug in the access opening between the manipulators. The pipetter is moved up and down hy an air cylinder, the control of which is mounted on the shidding face.
Figure 13.
Sample carrier and truok
Figure 14. Interior of sample storage box
m additional shielding, for 250 samples of about 35-roentgenper-hour radiation each. Figure 15 shows the lead shielding behind these t w o boxes, which is necessary to protect personnel in the adjacent laboratory area or a worker who may he doing emergency work behind the line, Chain hoists are provided t o remove this lead shielding in case the box must he replaced. Each storage box is equipped with a sample residue disposal unit. This device enables the analyst to discard the unused portion of the sample to suitable drainage. Figure 14 shows a portion of this unit. Two sharpened hollow needles pierce the neoprene gasket on the sample battle when it is pneumatically raised. Rinse water is ejected through one needle, the other
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1089 standard oaustio to the titration beaker by means of l/5--inchdiameter polyethylene tubing extending through the shielding. SOLVENT EXTRACTION APPARATUS.The mam spectrometer method that is used to determine the isotopic distribution of uranium requires high-purity uranium samples. The apparatus in Figure 18 is used for purifying and separating the uranium from foreign ions, including fission products. Liquid-liquid extraction, carried out in test tubes, is used for this purpose.
Figure 16.
Specific gravity apparatus
This pipetter will deliver any desired volume up to 0.8 ml. Precision is of the order of O.Z%, expressed as the standard error of a single delivery. SPECIFICGRAVITY APPARAT~S. The determination of specific gravity is made by the falling-drop technique. The time that a drop requires to fall through a slightly lighter, immiscible liquid is characteristic of its size and density. The apparatus shown in Figure 16 consists basically of a pipetter and 8. series of tubes suspended in a cleaF-plilstic, constant-temperature bath. The analyzed samples are aqueous; therefore the tubes are lilled with immiscible organic liquids covering the desired density range. The pipetter is similar in design to the remote pipetter just described but with one tenth the volume capacity. I n practice, after the pipetter is filled with sample, the pipetter tip is lowered under the surface of one of the organic liquids. A 5 X 10-2 ml. drop is delivered, ahioh breaks away from the pipctt,er tip when it is pulled lip and out of the organic liquid. The drop is watched on its doiT-naard descent by aid of mirrors. The analyst measures the timc vequired for the drop to fall between two lines soribed on the tube. The conversion to specific gravity is made by referring to a series of empirical calibration CWVPR.The calibrations are made with a series of aqueous standards !
