A Radioisotope Building PAUL C. TOMPBINS
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Oak Ridge Nationul Laboratory, Oak Ridge, Tenn. T h e design of a building devoted to the processing of radioisotopes is presented. Techniques are based on the development of uni t processes at all levels of activity except those that can be handled adequately by “aseptic” analytical techniques. The most specialized section contains cells (cubicles) with %foot concrete walls. The shielding design is based on 50 curies of 2 m.e.v. gamma radiation, whereas the contamination problem is based on 1 curie per ml. and a 1000-curie total activity of all radiation
types. Facilities for implementing the operational methods are built in wherever possible. Other facilities designed €or dealing with 1 curie of 2 m.e.v. gamma radiation for storage and decontamination of equipment are described. The general ventilation pattern and the waste disposal system are also shown. The general layout of the building, the relations between areas, and the operational regulations that are necessary to make the huilding function efficiently and safely are discussed.
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per hour a t the surface of any shield containing a nontransient source and facing an occupied area. The working area in front of the hood, the various corridors, and the operating faces of the hot installations are examples of areas classed as occupied. ( 2 ) 12 mr. per hour a t the surface of any shield containing a nontransient source and facing a restricted area-e.g., cell anteroom. (3) 12 mr. per hour a t the surface of any shield containing a transient source (drains, etc.) and facing an occupied area. (4) 50 mr. per hour a t the surface of any shield containing a transient source and facing an occupied or transiently occupied area (outside of the building, etc.). Calculations of numbers of curies consistent with these standards were based on 2 m.e.v. gamma radiation with a point source immediately adjacent to the opposite surface of the shield. Significant contamination of an occupied area is undesirable, so steps were taken to keep the contamination confined to restricted areas which could be segregated and identified. Although it is assumed that reasonable precautions will be taken to prevent accidents during normal operation, the facilities have been designed to minimize the consequences of those that may occur-for example, provisions have been made to process active material with the minimum handling.
HIS paper discusses several problems encountered in the design of a building devoted to the nonroutine chemical processing of radioisotopes. The program around which the building was designed is supposed to allow for: (1)development, testing, and approving of routine methods for preparation of radioisotopes; ( 2 ) preparation of radioactive material not available on a routine basis; (3) facilities for testing other proposed separations procedures; and (4) development of new manipulative techniques by means of which either routine procedures or special preparations may be performed with the minimum hazard to personnel. The building and the techniques to be used therein were designed especially to handle a wide range of radioactivity, particularly that incorporating external radiation hazards. The design was developed around the principles discussed by Tompkins and Levy (b). I t was necessary to balance an operational philosophy against the influence arising from intense radioactive sources despite the fact that completely adequate technical procedures have not yet been established. Some consideration inherent in the proposition of handling radioactive material but not particularly important a t lower levels of activity become highlighted a t the activity level contemplated here. Special problems involving the ventilation system and the disposal of radioactive aastes are examples. OPERATIONAL PHILOSOPHY AND DESIGN CRITERIA
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A consideration of the activity levels encountered for different types of work ( 1 ) and the general character of the technique appropriate for each, particularly as regards the external radiation hazard (i?), shows that all ranges of contamination and radiative problems from very low to very high will be encountered. Therefore, the manipulative and control techniques for a single procedure must gradate from ordinary radiochemical laboratory practice through the intermediate semiremote control stages to complete remote control manipulations by chemical engineering methods. The most general philosophy applicable to this type of work would seem t o involve the development of techniques based upon unit processes. The application of these unit processes from a manipulative point of view should be pushed backward toward thp laboratory lev& as far as economically feasible. Because this is a research building, the facilities must allow much more inherent flexibility than is available in a “facto y” where such design specifications as volumes of reactors, and the relative order of specific operations, can be completely specified. The fundamental shielding consideration was based on the feeling that no person should accumulate more than one tenth the daily tolerance dosage of radiation under normal. circumstances except as it is done deliberately. The following shielding schedule was used in an effort to derive this situation: (1) 1 milliroentgen
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Figure 1. Floor Plan
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Figure 2.
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Roof Plan of Cell Block
GENERAL LAYOUT OF BUILDING
The plans for the proposed laboratory were drawn up by a joint group representing the Chemistry Division of the Oak Ridge National Laboratory and the General Engineering Division of the Monsanto Chemical Company. It was designed by the architectural firm of Holabird and Root, Chicago, 111. It is to be an L-shaped two-story building of structural steel with brick and tile exterior walls, concrete floor and roof slab, and glazed tile interior wall. The over-all floor plan is shown schematically in Figure 1. Area I is the “low level” wing, which contains the counting rooms, laboratories, offices, research shops, change room, and service facilities. Area I1 contains the low level facilities which are necessary to support hot sections 111,IV, and V. An instrument
room, laboratory, storage room, and a shop for maintenance of contaminated equipment are on the first floor, and offices are on the second floor. Area 111 consists of a large central bay with clear space to the roof trusses. I n this bay are two sets of cubicles, or cells, described below. Along the west side of the bay in region IV are various rooms shielded with 2-foot concrete walls and ceilings. Ranging from top to bottom in the figure are a shielded laboratory for 1 curie of 2 m.e.v. gamnia or its equivalent in radiative hazard, a storage vault and product dispensary, thp decontamination room. and last the semihot laboratory. The arrows indicate the general flow pattern for the ventilation system and illustrate the principle that air should always be drawn from a region of the lowest potential contamination toward regions of higher potential contamination. The relative contamination potentials are indicated by the stippled areas which appear
Figure 3. Longitudinal Section of Cell Block
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INDUSTRIAL AND ENGINEERING CHEMISTRY
CELL LIGHTS
Figure 4.
Detail of Periscope Sleeve
throughout the building. In the low level wing, these are contined largely to the hoods. Although the general air pattern provides for air flow from the corridors and offices toward the laboratories and out through the hoods, the air flow from the counter room is into the corridor. The air flow is from the low level wing toward the high level wing. Within each individual working area the hoods and table tops constitute the most probable contaminated region. The semihot laboratory is negative in pressure with respect to the low level wing adjacent to it and is closed from it by doors. Figure 6.
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Air flows continuously from the open operating area in the large central bay toward the interior of the cells which are maintained a t the lowest pressure in the building. The cells are provided with a buffer area in the form of an anteroom. The stippled section in the storage room in area I V represents shielded troughs which form conduits for flexible tubes used in the transport of active material. These troughs constitute points where potential leakage is possible and are correspondingly protected with stainless steel linings, hot drains leading from them, and lead covers. Area V is the fan room for the hot end of the building and is considered to be a Figure 5. Vertical Section Showing Drain Protection contaminated region. In addition to fans for the various hoods, this area contains the vacuum -pumps, _ . etc., which will also be significantly contaminated by the very high specific activities contemplated. VENTILATION AND WASTE DISPOSAL SYSTEM
Two independent major ventilation units are supplied, one for the hot end of the building and the other for the low level wing. The equipment for these systems is located in the hot fan room (area V) and the adjacent equipment room. Independent ventilation of each room is probably the most desirable arrangement,
Longitudinal Section of Cell Block
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etc. This is the most extensive system, accommodating large volumes of liquid but low act,ivity levels (microcurie qusntit,ics). Hot drains from the cell blocks, hot hoods, hot sinks, storage lockers, decontamination room, and any place where contamination a t t,he millicurie level is likely. These drains are shielded within the building aiid terminate in tanks just outside the building, where the acid wastes are neutralized before being sent to large storage vats for permanent disposal. Maintenance of this drain system is a potential problem and any leak is bound to result in a high radioactive contamination. Therefore, it should be either completely maintenance-free, or accessible under conditions where the probable resulting contamination can not be serious. At no point where corrosion of the drains is likely t,o be a problem have they been buried in t'he wall. They are run underground under the building in such positions that' there is no potential interference between one drain and another. The sanitary sewer syst,em requires no discussion. CELL BLOCKS
Each cell block, shown in Figure 2, contains four cubicles arranged in a rectangular pattern. The walls are 3 feet of concrete capable of reducing the radiation from 30 curies of 2 n1.e.v. gamma to 1 mr. per hour a t the outside surface when the source is placed adjacent to the other surface. Decontamination facilities are based on the possible use of as much as 1000 curies of a softer radiation. The front vall aiid ceiling are perforated Tvith a large number of access holes to accommodate control rods, periscopes, etc. These holes arc lined with stainless steel tubes, welded to a z//ie-inclistainless steel liner on the interior wall of the cell. h %ton capacity monorail passes ovw removable steel plugs in the roof of the cell. This opening provides access to the interior of the cubicle for bringing in active material even when the equipment inside is contaminated. The pattern of access holss in the roof slab is shown for one cell only, the rest being symmetrically arranged. The roof slabs are made from slwl plates 14 inches thick.
TI'' 1.D HARD LEAD CONDUITS
Figure 7.
Section of Hot Hood
but was ruled out for economic reasons. Instead, central units were provided, with the hope of maintaining the proper flow pattern by static control pressure regulators. Areas I and I1 are to be air-conditioned, but area I11 is not. Air is d r a m into area 111through a filter and heating coil in the roof, from which it is blown downward across the operating area. The fans from the hot hoods in t,he 1-curie laboratory form the permanent exhaust for this air. The other means of exhaust are into the cells, which are kept permanently at a pressure to the operating area, and through other hoods which serve this end of the building. The semihot laboratory and the I-curie laboratory are airconditioned for reasons of personnel safety. Experience has shown that the expendable clothing and glovcs which are required for this type of work promote excessive perspiration which one instinctively tends to wipe from his face. Because t,he hands, or, more properly, the outside surfaces of the gloves almost invariably become contaminated, several cases of face contamination froin this source have arisen. The consequences of contamination arising a t the very high activity levels encountered in the cell blocks, etc., are such t,hat the difficulties of maintaining a drain system appeared less than the potent'ial contamination and radiative hazard arising from handling the radioactive solut,ions. The following drain systems are provided: Chemical waste drains from the laboratory sink, floor drains,
WINDOW\
Figure 8.
Section A A of Hood
Figure 3 s h o m a section through the cell block. The right side s h o m the pattern of the access holes as they appcar from thc inside. Each cell is divided at the 9-foot level by a steel floor 0 inches thick, with a 2-foot-square access hole from the outside operating area appearing just under the level of the floor. All access holes are protected 1%-ithsteel doors 9 inclics thick for radiation protection, and the inner surface is protected with a 0.5-inch stainless steel door which folds away from the exterior t o protect against contamination. The different thicknesses arise from the different geometries between the doors and the roof. When significant portions of t,he concrete shielding have been removed, owing to the design of the holes, the difference has been made up by the insertion of enough lead to bring the total shielding densit,y back to the equivalent of 3 feel of concrete.
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i n t e r i o r s u r f a c e will n o t render the installation inoperative. Conduits running through the walls around the edge of the windows make it possible to run service lines from the inside outward a t the time the experiment is set up, and these services may then be plugged in a t Figure 9. Plan at Top of Semihot Bench will without entering a contaminated region. Figure 8 This is illustrated more clearly in Figure 4, which shows the shows the plan of these conduits at the point marked A A (Figure detail for the periscope holes and the port for the cell lights. 7). The conduits and the entire inner surface of the hood are lined with either lead or stainless steel. A simplified sketch of the drainage system is shown in Figure 5. The hot drain from the top half of the cell is recessed into the wall SEMJHOT LABORATORY and the recess is covered with lead shielding. The recess is thereby lined with stainless steel on three sides and lead on the Figure 9 shows in greater detail the plan of the semihot laborafourth, so that the inner face of the lower cell presents a smooth tory bench, which was designed for operations which do not surface. require the massive shielding and fixed installations needed at Because complete remote control is required for any installathe 1-curie level. This bench was designed for operations utiliztion in these facilities, it was decided that active materials would ing mostly close shielding for radiative protection and manipulabe transported from one place to another in solution, using negators for distance. tive pressure to draw the solution through tubes, Therefore, means should be provided, as seen in Figure 6, to bring the solution to a centrstl point from which it may be directed to any 4 1' L ,6GA ST STEEL IS.8S-CB h desired location in the building. ONE-CURIE HOOD
The 1-curie hoods are designed to provide radiative protection against 1 curie of 2 m.e.v. gamma. The type of structure necessary to meet design specifications is shown in Figure 7. This design is suitable for semiremote control using unit operations and mounted equipment, but is not easily adapted to the use of complex manipulators. The floor consists of a solid steel slab 8 inches thick. At the.front is a lead barrier 8 inches wide, on which individual lead bricks may be piled t o construct a temporary shield as the experiment requires it. The hood is backed against a 2-foot concrete wall through which the ventilation ducts run. The ventilation ducts are fabricated of chemical stoneware. They are provided with drains connecting, with the hot drain system, and contain provisions for flushing them down. The rear of the hood contains a trough to make it possible to wash out contamination when necessary. I n case of a n accident involving the entire sample, the drain is shielded so that adsorption on the
CANOPY FUME HOOD
Figure 10.
Figure 11.
Section of Semihot Bench
As with all other facilities in this region, the table is lined with either lead or stainless steel, as are the immediately adjacent walls to provide a good, decontaminatable surface. The table is against a 2-foot concrete wall to provide radiative protection to those working in the next room and vice versa. This bench follows the same general philosophy \ $ ALONO LEAD ON OONORETE WALL of contamination protection as ENTIRE SPAN illustrated earlier. The tablc is bounded by a lead curb on which smaller barriers may be erected as needed. It is built in the general form of a tray to prevent solution from falling off the table, and a trough is provided a t the rear so that all active material can be forced away from the occupied area as necessary. T h e services are provided on a strip across the front and outside the contaminated region. T h e trough runs behind a cleaning arrangement consisting of tanks to colitain cleaning solution and a shielded hot sink, so that contami-. Elevation of Semihot Bench nated equipment can be trans-
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ported from the working area to the cleaning area by tongs without becoming exposed to an occupied section of the laboratory. Figure 10 shows the front elevation of this table. Although it is a n open table, ventilation ducts are provided to draw air across the table as though it were a hood. The entire wall is lined with lead and is provided with a system of inserts which make it possible t o handle mobile equipment, such as small hoods, a t any desired point. The general plan is to concentrate on the development of techniques that keep contamination confined to the interior of the equipment. Even though this is a relatively low level laboratory, it is still provided with a 4-inch steel slab for t,he table top t o make it possible to work routinely with reasonable quantities of gamma-emitters. A more detailed section is shown in Figure 11.
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according t o common standards, and require a considerable degree of precision machining on massive steel plate. They have been designed t o provide the maximum degree of automatic protection to the people in the building, and also t o make it as easy as possible t o conduet high level work with the minimum contamination hazard. Despite the various facilities, each has its own specified upper limits which should not be exceeded unless particular precautions are taken to offset the additional hazard. Although the average laboratory will not require this particular type of construction, it illustrates a specific application of t h e principles presented by Tompkins and Levy ( 2 )lor the case where a very wide range of radioactive levels are encountered in one locality. LITERATURE CITED
SUMMARY
These facilities illustrate the type of construction that is consistent with the concept of an all-purpose research laboratory utilizing advanced levels of both beta- and gamma-activities, where both the frequency and duration of contact may be con.eidered t o be continuous. They are fantastically expensive
(1) Levy, H. A., Chem. Eng. News, 24, 3168 (1946). (2) Tompkins, P. C., and Levy, H. B., IND. ENC.CHEX., 41, 228 (1948).
RBCEIVEDAugust 28, 1948. Based o n work peiformed under Contract W-35-058-eng-71 for the Atomic Energy Projeot a t Oak Ridge Xationsl Laboratory.
laboratory for Preparation and Use of Radioactive Organic Compounds C. N. RICE Lilly Research Laboratories, Indianapolis, Ind.
A laboratory section for procedures making
use of 1 mc. or less of beta- and gamma-emitting substances is described. The aim has been to design a laboratory which can accommodate slightly greater amounts successfully. The isolated area set aside for this work includes laboratory, animal room, counting room, office, shower room, service room, and cleaning and storage space. Experimental operations at different levels of activity are separated in space. Surfaces are streamlined and as continuous as possible to simplify cleaning and decontamination procedures. Construction materials have been chosen for durability, stability toward solvent action, ease of cleaning, and ease and cheapness of replacement. Air conditioning gives controlled ventilation to protect personnel, to control direction of air movements, and to maintain detection apparatus under reproducible atmospheric conditions.
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HE laboratory described is t o be used for synthesis of
organic compounds containing C14,5 3 5 , radiohalogens, and others; study of the nature of chemical reactions; analysis by the isotope dilution method; study of the efficiencies of separation processes; study of the biological fate of drugs; metabolic studies; investigation of interactions of biological fluids; and physiological permeability studies. Some twenty or more radioelements n i t h many different qualities of radiation will be of interest. Despite the general scope of the installation, the space will be restricted at any one time, because of the limited size of the laboratory, t o a few of the studies mentioned. The desire t o construct a safe laboratory, which will still be useful many years hence, has influenced the design of the laboratory as profoundly as has the type of problems t o be pursued. Prevention of contamination of the laboratory presents a greater
problem in design, however, than does ensuring safety for personnel. Blthough 10-me. amounts of material will be stored, not more than 1 me. will be in experimental use a t one time. It is anticipated that 50 t o 75% of the radioactive substances used will be soft beta-emitters. Close plastic shielding is used for those beta-emitters whose radiations are not stopped by the apparatus containing them. ,4s none of the gamma-emitt,ers with which the laboratory will be concerned in 1-me. amounts have photons of greater than 2 m.e.v. energy, only modest general shielding measures are required. FLOOR PLAN
The general plan of the radioactivity section of the research laboratories is shown in Figure 1. Because the wing in which it is placed was under construction before planning of the radiochemical laboratory was begun, it vias necessary to adapt the laboratory t o a situation which prior planning had produced. This small area, whicll is on the basement level a t the end of a tving, is isolated from other research facilities occupying several wings and floors of the research building. All work with radioactivity will be done in this area. The counting room is placed as far as possible from the area in which experimental work is done. The area is made as self-contained as possible through the inclusion of a shower and toilet room, service room, and janitor's closet. GENERAL CONSTRUCTION
A salient feature of the general construction is the use of wood framing and plywood sheeting. Although this is not standard construction, these materials were chosen because mortar joints
