A HOMEMADE FALLOUT METER, THE KFM HOW TO MAKE AND USE IT FOLLOWING THESE INSTRUCTIONS MAY SAVE YOUR LIFE I. The Need for Accurate and Dependable Fallout Meters II. Survival Work Priorities During a Crisis If a nuclear war ever strikes the United States, survivors of the blast and fire effects Before building a KFM, persons expecting a nuclear attack within a few hours or would need to have reliable means of knowing when the radiation in the days and already in the place where they intend to await attack should work with environment around their shelters had dropped enough to let them venture safely outside. Civil defense teams could use broadcasts of surviving radio stations to the following priorities: (1) build or improve a high-protection-factor shelter (if give listeners a general idea of the fallout radiation in some broadcast areas. possible, a shelter covered with 2 or 3 feet of earth and separate from flammable However, the fallout radiation would vary widely from point to point and the buildings); (2) make and install a KAP (a homemade shelter-ventilating pump) -- measurements would be made too far from most shelters to make them accurate if instructions and materials are available; (3) store at least 15 gallons of water for enough to use safely. Therefore, each shelter should have some dependable each shelter occupant -- if containers are available; (4) assemble all materials for one or two KFM’s; and (5) make and store the drying agent (by heating wallboard method of measuring the changing radiation dangers in its own area. gypsum, as later described) for both the KFM and its dry-bucket. During a possible nuclear crisis that was rapidly worsening, or after a nuclear attack, most unprepared Americans could not buy or otherwise obtain a fallout meter -- an instrument that would greatly improve their chances of surviving a nuclear war. The fact that the dangers from fallout radiation -- best expressed in terms of the radiation dose rate, roentgens per hour (R/hr) -- quite rapidly decrease during the first few days, and then decrease more and more slowly, makes it very important to have a fallout meter capable of accurately measuring the unseen, unfelt and changing fallout dangers. Occupants of a fallout shelter should be able to control the radiation doses they receive. In order to effectively control the radiation doses, a dependable measuring instrument is needed to determine the doses they receive while they are in the shelter and while they are outside for emergency tasks, such as going out to get badly needed water. Also, such an instrument would permit them to determine when it is safe to leave the shelter for good. III. How toUse These Instructions to Best Advantage 1. Read ALOUD all of these instructions through Section VII, “Tools Needed,” before doing anything else. 2. Next assemble all of the needed materials and tools. 3. Then read ALOUD ALL of each section following Section VII before beginning to make the part described in that section. Untrained families, guided only by these written instructions and using only low cost materials and tools found in most homes, have been able to make a KFM by working 3 or 4 hours. By studying the operating sections of these instructions for about 1 hours, average untrained families have been able to successfully use this fallout meter to measure dose rates and to calculate radiation doses received, permissible times of exposure, etc. A FAMILY THAT FAILS TO READ ALOUD ALL OF EACH SECTION DESCRIBING HOW TO MAKE A PART, BEFORE BEGINNING TO MAKE THAT PART, WILL MAKE AVOID- ? ABLE MISTAKES AND WILL WASTE TIME. The KFM (Kearny Fallout Meter) was developed at Oak Ridge National Laboratory. It is understandable, easily repairable, and as accurate as most civil defense fallout meters. In the United States in 1976 a commercially available ion chamber fallout meter that has as high a range as a KFM for gamma radiation dose-rate measurements retailed for $600. 4. Have different workers, or pairs of workers, make the parts they are best qualified to make. For example, a less skilled worker should start making the drying agent (as described in Section VIII) before other workers start making other parts. The most skilled worker should make and install the aluminum-foil leaves (Sections X and XI). 5. Give workers the sections of the instructions covering the parts they are to build--so they can follow the step-by-step instructions, checking off with a pencil each step as it is completed. Before a nuclear attack occurs is the best time to build, test and learn how to use a KFM. However, this instrument is so simple that it could be made even after fallout arrives provided that all the materials and tools needed (see lists given in Sections V, VI, and VII) and a copy of these instructions have been carried into the shelter. 6. Discuss the problems that arise. The head of the family often can give better answers if he first discusses the different possible interpretations of some instructions with other family members, including teenagers. 7. After completing one KFM and learning to use it, if time permits make a second KFM--that should be a better instrument. A KFM is a simple electroscope fallout meter with which fallout radiation can be measured accurately. To use a KFM, an electrostatic charge must first be placed on its two separate aluminum-foil leaves. These leaves are insulated by being suspended separately on clean, dry insulating threads. To take accurate readings, the air inside a KFM must be kept very dry by means of drying agents such as dehydrated gypsum (easily made by heating gypsum wallboard, “sheetrock”) or silica gel. (Do not use calcium chloride or other salt.) Pieces of drying agent are placed on the bottom of the ionization chamber (the housing can) of a KFM. An electrostatic charge is transferred from a homemade electrostatic charging device to the two aluminum-foil leaves of a KFM by means of its charging-wire. The charging-wire extends out through the transparent plastic cover of the KFM. When the two KFM leaves are charged electrostati- cally, their like charges (both positive or both negative) cause them to be forced apart. When fallout gamma radiation (that is similar to X rays but more energetic) strikes the air inside the ionization chamber of a KFM, it produces charged ions in this enclosed air. These charged ions cause part or all of the electrostatic charge on the aluminum-foil leaves to be discharged. As a result of losing charge, the two KFM leaves move closer together. To read the separation of the lower edges of the two KFM leaves with one eye, look straight down on the leaves and the scale on the clear plastic cover. Keep the reading eye 12 inches above the SEAT. The KFM should be resting on a horizontal surface. To be sure the reading eye is always at this exact distance, place the lower end of a 12-inch ruler on the SEAT, while the upper end of the ruler touches the eyebrow above the reading eye. It is best to hold the KFM can with one hand and the ruler with the other. Using a flashlight makes the reading more accurate. If a KFM is made with the specified dimensions and of the specified materials, its accuracy is automatically and permanently established. Unlike most radiation measuring instruments, a KFM never needs to be calibrated or tested with a radiation source, if made and maintained as specified and used with the following table that is based on numerous calibrations made at Oak Ridge National Labor- atory. The millimeter scale is cut out and attached (see photo illustrations on the following page) to the clear plastic cover of the KFM so that its zero mark is directly above the two leaves in their discharged position when the KFM is resting on a horizontal surface. A reading of the separation of the leaves is taken by noting the number of millimeters that the lower edge of one leaf appears to be on, on one side of the zero mark on the scale, and almost at the same time noting the number of millimeters the lower edge of the other leaf appears to be on, on the other side of the zero mark. The sum of these two apparent positions of the lower edges of the two leaves is called a KFM reading. The drawing appearing after the photo illustrations shows the lower edges of the leaves of a KFM appearing to be 9 mm on the right and zero and 10 on the left, giving a KFM reading of 19 mm. (Usually the lower edges of the leaves are not at the same distance from the zero mark.) As will be fully explained later, the radiation dose rate is determined by: TABLE USED TO FIND DOSE RATES (R/HR) 1. charging and reading the KFM before FROM KFY READINGS exposure; TIME INTERVAL OF AN EXPOSURE R E A D - 2. exposing it to radiation for a specified time in the location where measure- INGS R/HR R/HR R/HR R/HR R/HR 2 mm 6.2 1.6 0.4 0.1 0.03 ment of the dose rate is needed -- when 4 mm 12. 3.1 0.8 0.2 0.06 outdoors, holding the KFM about 3 ft. 6 mm 19. 4.6 1.2 0.3 0.08 above the ground; 8 mm 25. 6.2 1.6 0.4 0.10 10 mm 31. 7.7 2.0 0.5 0.13 12mm 37. 9.2 2.3 0.6 0.15 3. reading the KFM after its exposure; 14mm 43. 11. 2.7 0.7 0.18 4. calculating, by subtraction, the difference between the reading taken before exposure and the reading taken after exposure; 5. using this table to find what the dose rate was during the exposure -- as will be described later. Instructions on how to use a KFM are given after those detailing how to make and charge this fallout meter. To get a clearer idea of the construction and use of a KFM, look carefully at the following photos and read their captions. A. B. An Uncharged KFM. The charging wire has been pulled to one side by its adjustment-thread. This photo was taken looking straight down at the upper edges of the two flat, 8-ply aluminum leaves. At this angle the leaves are barely visible, hanging vertically side by side directly under the zero mark, touching each other and with their ends even. Their suspension- threads insulate the leaves. These threads are almost parallel and touch (but do not cross) each other where they extend over the top of the rim of the can. Charging a KFM by a Spark-Gap Discharge from a Tape That Has Been Electrostatically Charged by Being Unwound Quickly. Note that the charged tape is moved so that its surface is perpendicular to the charging-wire. The high-voltage electro- static charge on the un- wound tape (that is an insulator) jumps the spark-gap between the tape and the upper end of the charging-wire, and then flows down the charging-wire to charge the insulated aluminum- foil leaves of the KFM. (Since the upper edges of the two leaves are 3/4 inch below the scale and this is a photo taken at an angle, both leaves appear to be under the right side of the scale.) C. D. A Charged KFM. Note the separation of the upper edges of its two leaves. The charging- wire has been raised to an almost horizontal pos- ition so that its lower end is too far above the alu- minum leaves to permit electrical leakage from the leaves back up the charging-wire and into the outside air. Also note the SEAT, a piece of pencil taped to the right side of the can, opposite the charging wire. Reading a KFM. A 12- inch ruler rests on the SEAT and is held vert- ical, while the reader’s eyebrow touches the upper end of the ruler. The lower edge of the right leaf is under 8 on the scale and the lower edge of the left leaf is under 6 on the scale, giving a KFM reading of 14. For accurate radiation measurements, a KFM should be placed on an approximately horizontal surface, but the charges on its two leaves and their displacements do not have to be equal. INSTRUCTIONS, Page 5 ADJUSTMENT THREAD (NYLON IS TAPE REMOVABLE TRANSPARENTCOVER AND CHARGING WIRE AND TO FIT OVER SEAT ON CAN TAPE EDGE OF SKIRT OF COVER TIED TO TOP TOGGLE (SMALL SLIVER (COVER AND CHARGING WIRE NOT SHOWN) OF WOOD TAPE TOGGLE OUTSIDE OF CAN f % OF CAN INSIDE 2 in. (This is a Full Scale V. Materials Needed 10. An ordinary wooden pencil and a small toothpick (or split a small sliver of wood). A. For the KFM: (In the following list, when more than one alternative material is given, the best material is listed first.) 1. Any type metal can, approximately 2-9/16 inches in diameter inside and 2-7/8 inches high inside, washed clean with soap. (This is the size of a standard 8-ounce can. Since most soup cans, pop cans, and beer cans also are about 2-9/16 inches in diameter inside, the required size of can can also be made by cutting down the height of more widely available cans -- as described in Section IX of these instructions.) 2. 3. 4. 5. 6. 7. 8. 9. Standard aluminum foil -- 2 square feet. (In 1977, 2 square feet of a typical American aluminum foil weighed about 8.2 grams -- about 0.29 OZ.) (If only “Heavy Duty” or “Extra Heavy Duty” aluminum foil is available, make 5-ply leaves rather than 8-ply leaves of standard foil; the resultant fallout meter will be almost as accurate.) Doorbell-wire, or other light insulated wire (preferably but not necessarily a single-strand wire inside the insulation) -- 6 inches. Any type of lightweight thread (preferably but not necessarily nylon). (Best is twisted nylon thread; next best, unwaxed lightweight nylon dental floss; next best, silk; next best, polyester.) -- 3 feet. (Thread should be CLEAN, preferably not having been touched with fingers. Monofilament nylon is too difficult to see, handle, and mark.) A piece of clear plastic -- a 6 x 6 inch square. Strong polyethylene (4 mils thick) used for storm-proofing windows is best, but any reasonably stout and rather clear plastic will serve. The strong clear plastic used to wrap pieces of cheese, if washed with hot water and soap, is good. Do not use weak plastic or cellophane. Cloth duct tape (“silver tape”), or masking tape, or freezer tape, or Scotch-type tape -- about 10 square inches. (Save at least 10 feet of Scotch Magic Transparent Tape for the charging device.) Band-Aid tape, or masking tape, or freezer tape, or Scotch transparent tape, or other thin and very flexible tapes -- about 2 square inches. Gypsum wallboard (sheetrock) -- about l/2 square foot, best about 1/2 inch thick. (To make the essential drying agent.) Glue -- not essential, but useful to replace Band-Aid and other thin tapes. “One hour” epoxy is best. Model airplane cement is satisfactory. 11. Two strong rubber bands, or string. B. For the Charging Devices: 1. Most hard plastic rubbed on dry paper. This is the best method. a. Plexiglas and most other hard plastics, such as are used in drafts- men’s triangles, common smooth plastic rulers, etc. -- at least 6 inches long. b. Dry paper -- Smooth writing or typing paper. Tissue paper, news- paper, or facial tissue such as Kleenex, or toilet paper are satisfactory for charging, but not as durable. 2. Scotch Magic Transparent Tape (3/4 inch width is best), or Scotch . Transparent Tape, or P.V.C. (Polyvinyl chloride) insulating electrical tapes, or a few of the other common brands of Scotch-type tapes. (Some plastic tapes do not develop sufficiently high-voltage electrostatic charges when unrolled quickly.) This method cannot be used for charging a KFM inside a dry-bucket, needed for charging when the air is very humid. C. For Determining Dose Rates and Recording Doses Received: 1. A watch -- preferably with a second hand. 2. A flashlight or other light, for reading the KFM in a dark shelter or at night. 3. Pencil and paper -- preferably a notebook. D. For the Dry-Bucket: (A KFM must be charged inside a dry-bucket if the air is very humid, as it often is inside a crowded, long-occupied shelter lacking adequate forced vent- ilation.) 1. A large bucket, pot, or can, preferably with a top diameter of at least 11 inches. 2. Clear plastic (best is 4-mil-thick clear plastic used for storm windows). A square piece 5 inches wider on a side than the diameter of the bucket to be used. 3. Cloth duct tape, one inch wide and 8 feet long (or 4 ft., if 2 inches wide). Or 16 ft. of freezer tape one inch wide. 4. 5. 6. 7. 8. Two plastic bags 14 to 16 inches in circumference, such as ordinary plastic bread bags. The original length of these bags should be at least 5 inches greater than the height of the bucket. About one square foot of wall board (sheetrock), to make anhydrite drying agent. Two l-quart Mason jars or other airtight containers, one in which to store anhydrite and another in which to keep dry the KFM charging devices. Strong rubber bands -- enough to make a loop around the bucket. Or string. Four square feet of aluminum foil, to make a vapor-proof cover -- useful, but not essential. VI. Useful but not Essential Materials --Which Could be Obtained Before a Crisis-- 1. An airtight container (such as a large peanut butter jar) with a mouth at least 4 inches wide, in which to keep a KFM, along with some drying agent, when it is not being used. Keeping a KFM very dry greatly extends the time during which the drying agent inside the KFM remains effective. 2. Commercial anhydrite with a color indicator, such as the drying agent Drierite. This granular form of anhydrite remains light blue as long as it is effective as a drying agent. Obtainable from laboratory supply sources. VII. Tools Needed Small nail sharpened Stick, or a wooden tool handle (best 2 - 2 1/2 inch diameter and at least 12 inches long) Hammer Pliers Scissors Needle quite a large sewing needle, but less than 2 1/2 inches long Knife with a small blade -- sharp Ruler (12 inches) VIII. Make the Drying Agent -- The Easiest Part to Make, but Time Consuming -- For a KFM to measure radiation accurately, the air inside its ionization chamber must be kept very dry. An excellent drying agent (anhydrite) can be made by heating the gypsum in ordinary gypsum wallboard (sheetrock). Do NOT use calcium chloride. Take a piece of gypsum wallboard approximately 12 inches by 6 inches, and preferably with its gypsum about 3/8 inches thick. Cut off the paper and glue, easiest done by first wetting the paper. [Since water vapor from normal air penetrates the plastic cover of a KFM and can dampen the anhydrite and make it ineffective in as short a time as two days, fresh batches of anhydrite must be made before the attack and kept ready inside the shelter for replacement. The useful life of the drying agent inside a KFM can be greatly lengthened by keeping the KFM inside an airtight container (such as a peanut butter jar with a 4-inch-diameter mouth) with some drying agent, when the KFM is not being used.] Break the white gypsum filling into small pieces and make the largest no more than l/2 in. across. (The tops of pieces larger than this may be too close to the aluminum foil leaves.) If the gypsum is dry, using a pair of pliers makes breaking it easier. Make the largest side of the largest pieces no bigger than this. Dry gypsum is not a drying agent. To drive the water out of the gypsum molecules and produce the drying agent (anhydrite), heat the gypsum in an oven at its highest temperature (which should be above 400 degrees F) for one hour. Heat the gypsum after placing the small pieces no more than two pieces deep in a pan. Or heat the pieces over a fire for 20 minutes or more in a pan or can heated to a dull red. If sufficient aluminum foil and time are available, it is best to heat the gypsum and store the anhydrite as follows: a. b. So that the right amount of anhydrite can be taken quickly out of its storage jar, put enough pieces of gypsum in a can with the same diameter as the KFM, measuring out a batch of gypsum that almost covers the bottom of the can with a single layer. Cut a piece of aluminum foil about 8 in. x 8 in. square, and fold up its edges to form a bowl-like container in which to heat one batch of gypsum pieces. C. Measure out 10 or 12 such batches, and put each batch in its aluminum foil “bowl.” d. Heat all of these filled “bowls” of gypsum in hottest oven for one hour. 6. 7. 8. e. As soon as the aluminum foil is cool enough to touch, fold and crumple the edges of each aluminum foil “bowl” together, to make a rough aluminum-covered “ball” of each batch of anhydrite. f. Promptly seal the batches in airtight jars or other airtight containers, and keep containers closed except when taking out an aluminum-covered “ball.” Since anhydrite absorbs water from the air very rapidly, quickly put it in a dry airtight container while it is still quite hot. A Mason jar is excellent. To place anhydrite in a KFM, drop in the pieces one by one, being careful not to hit the leaves or the stop-threads. The pieces should almost cover the bottom of the can, with no piece on top of other pieces. To remove anhydrite from a KFM, use a pair of scissors or tweezers as forceps, holding them in a vertical position and not touching the leaves. IX. Make the Ionization Chamber of the KFM (To Avoid Mistakes and Save Time, Read All of This Section ALOUD Before Beginning Work.) Remove the paper label (if any) from an ordinary 8-ounce can from which the top has been smoothly cut. Wash the can with soap and water and dry it. (An 8-ounce can has an inside diameter of about 2-9/16 inches and an inside height of about 2-7/8 inches.) Skip to step 3 if an 8-ounce can is available. If an 8-ounce can is not available, reduce the height of any other can having an inside diameter of about 2-9/16 inches (such as most soup cans, most pop cans, or most beer cans). To cut off the top part of a can, first measure and mark the line on which to cut. Then to keep from bending the can while cutting, wrap newspaper tightly around a stick or a round wooden tool handle, so that the wood is covered with 20 to 30 thicknesses of paper and the diameter (ideally) is only slightly less than the diameter of the can. One person should hold the can over the paper-covered stick while a second person cuts the can little by little along the marked cutting line. If leather gloves are available, wear them. To cut the can off smoothly, use a file, or use a hacksaw drawn backwards along the cutting line. Or cut the can with a sharp, short blade of a pocketknife by: (1) repeatedly stabbing downward vertically through the can into the paper, and (2) repeatedly making a cut about l/4 inch long by moving the knife into a sloping position, while keeping its point still pressed into the paper covering the stick. Next, smooth the cut edge, and cover it with small pieces of freezer tape or other flexible tape. 3. 4. 5. 6. Cut out the PAPER PATTERN TO WRAP AROUND KFM CAN. (Cut one pattern out of the following Pattern Page A.) Glue (or tape) this pattern to the can, starting with one of the two short sides of the pattern. Secure this starting short side directly over the side seam of the can. Wrap the pattern snugly around the can, gluing or taping it securely as it is being wrapped. (If the pattern is too wide to fit flat between the rims of the can, trim a little off its lower edge.) Sharpen a small nail, by filing or rubbing on concrete, for use as a punch to make the four holes needed to install the stop-threads in the ionization chamber (the can). (The stop-threads are insulators that stop the charged aluminum leaves from touching the can and being discharged.) Have one person hold the can over a horizontal stick or a round wooden tool-handle, that ideally has a diameter about as large as the dia- meter of the can. Then a second person can use the sharpened nail and a ham- mer to punch four very small holes through the sides of the can at the points shown by the four crosses on the pattern. Make these holes just large enough to run a needle through them, and then move the needle in the holes so as to bend back the obstructing points of metal. PUNCH SMALL SHARPENED SMALL NAIL HANDLE INSIDE The stop-threads can be installed by using a needle to thread a single thread through all four holes. Use a very clean thread, prefer- ably nylon, and do not touch the parts of this thread that TO NEEDLE SMALL TOGGLE TIED TO END OF THREAD TOGGLE THIS SMALL 1/2 in. FROM CAN; LATER THREAD IS will be inside the can and will serve as the insulating STOP- stop-threads. Soiled threads THREAD are poor insulators. (See illustrations.) SIDE OF CAN SINGLE THREAD THREADED THROUGH 4 HOLES TO MAKE 2 STOP-THREADS CUT EXACTL Y ON SIDE LINES H O L E F O R STOP- THREAD TABLE USED TO FIND DOSE RATES (R/HR) FROM KFM READINGS ‘DIFFERENCE BETWEEN THE READING BEFORE EXPOSURE AND THE READlNG AFTER EXPOSURE (8-PL Y STANDARD. FOIL LEAVES, DIFF.* IN TIME INTERVAL OF AN EXPOSURE READ- 1 HR. INGS R/HR R/HR R/HR R/HR R/HR 2 mm 6.2 1.6 0.4 0.1 0.03 4mm 12. 3.1 0.8 0.2 0.06 6mm 19. 4.6 1.2 0.3 0.08 8mm 25. 6.2 1.6 0.4 0.10 10 mm 31. 7.7 2.0 0.5 0.13 12mm 37. 9.2 2.3 0.6 0.15 14 mm 43. 11. 2.7 0.7 0.18 TOP OF CAN FASTEN THREADS HOLDING ALUMINUM LEAVES HERE OF l-IN. PENCIL (FOR RULER REST) SEAT FOR STOP- T H R E A D HOLES FOR STOP-THREAD BOTTOM OF CAN (ABOVE LIP) CUT EXACTL Y ON SIDE LINES TOP OF CAN FASTEN THREADS HOLDING ALUMINUM LEAVES HERE TABLE USED TO FIND DOSE RATES (R/HR) FROM KFM READINGS ‘DIFFERENCE BETWEEN THE READING BEFORE EXPOSURE AND THE READING AFTER EXPOSURE (8 PL Y STANDARD FOIL LEA VE OF I-IN. PENCIL (FOR RULER REST) HOLE FOR STOP- THREAD 10 mm 12mm 14 mm S) TIME INTERVAL OF AN EXPOSURE 15 SEC. 1 MIN. 4MIN. 16MIN. 1 HR. R/HR R/HR R/HR R/HR R/HR 6.2 1.6 0.4 0.1 0.03 HOLES FOR STOP-THREAD 12. 3.1 0.8 0.2 0.06 FOR 19. 4.6 1.2 0.3 0.08 STOP- 25. 6.2 1.6 0.4 0.10 THREAD 31. 7.7 2.0 0.5 0.13 37. 9.2 2.3 0.6 0.15 43. 11. 2.7 0.7 BOTTOM OF CAN (ABOVE LIP) PAPER PATTERN TO WRAP AROUND KFM CAN (GLUE OR TAPE SECURELY TO CAN) CUT OUT THESE PATTERNS, EACH OF WHICH IS THE EXACT SIZE FOR A KFM. PATTERN PAGE (A) CAUTION: XEROX COPIES OF THESE PATTERNS WILL BE TOO LARGE. Before threading the thread through the four holes, tie a small toggle (see the preceding sketch) to the long end of the thread. (This toggle can easily be made of a very small sliver of wood cut about 3/8 in. long.) After the thread has been pulled through the four holes, attach a second toggle to the thread, about l/2 inch from the part of the thread that comes out of the fourth hole. Then the thread can be pulled tightly down the side of the can and the second small toggle can be taped securely in place to the side of the can. (If the thread is taped down without a toggle, it is likely to move under the tape.) The first toggle and all of the four holes also should be covered with tape, to prevent air from leaking into the can after it has been covered and is being used as an ionization chamber. X. ‘Make Two Separate 8-Ply Leaves of Standard [Not Heavy Duty*] Aluminum Foil Proceed as follows to make each leaf: 1. 2. 3. 4. 5. 6. Cut out a piece of standard aluminum foil approximately 4 inches by 8 inches. Fold the aluminum foil to make a 2-ply (= 2 thicknesses) sheet approximately 4 inches by 4 inches. Fold this 2-ply sheet to make a 4-ply sheet approximately 2 inches by 4 inches. THE SQUARE CORNER 8-PLY SHEET THIRD-FOLD EDGE Fold this 4-ply sheet to make an 8-ply sheet (8 sheets thick) approximately 2 inches by 2 inches, being that the two halves of the second-fold edge are exactly together. This third folding makes an 8-ply aluminum foil sheet with one comer exactly square. Cut out the FINISHED-LEAF PATTERN, found on the following Pattern Page B. Note that this pattern is NOT a square and that it is smaller than the 8-ply sheet. Flatten the 8 thicknesses of aluminum foil with the fingers until they appear to be a single thin, flat sheet. Hold the FINISHED-LEAF PATTERN on top of the 8-ply aluminum foil sheet, with the pattern’s THIRD-FOLD EDGE on top of the third-fold edge of the 8-ply aluminum sheet. Be sure that one lower corner of the FINISHED-LEAF PATTERN is on top of the exactly square corner of the 8-ply aluminum sheet. 7. 8. 9. 10. 11. While holding a straight edge along the THREAD LINE of the pattern, press with a sharp pencil so as to make a shallow groove for the THREAD LINE on the 8-ply aluminum sheet. Also using a sharp pencil, trace around the top and side of the pattern, so as to indent (groove) the 8-ply foil. Remove the pattern, and cut out the 8-ply aluminum foil leaf. While holding a straight edge along the indented THREAD LINE, lift up the OPEN EDGE of the 8-ply sheet (keeping all 8 plies together) until this edge is ver- tical, as illustrated. Remove the straight edge, and fold the 8-ply aluminum along the THREAD LINE so as to make a flat-folded hem. Open the flat-folded hem of the finished leaf until the 8-ply leaf is almost flat again, as shown by the pattern, from which the FIN- ISHED-LEAF PATTERN has al- ready been cut. Prepare to attach the aluminum- foil leaf to the thread that will suspend it inside the KFM. THREAD L I N E THE SQUARE CORNER OF 8-PLY SHEET THIRD-FOLD EDGE OF 8-PLY SHEET *If only heavy duty aluminum foil (sometimes called “extra heavy duty”) is available, make 5-ply leaves of the same size, and use the table for the 8-ply KFM to determine radiation dose rates. To make a 5-ply leaf, start by cutting out a piece of foil approximately 4 inches by 4 inches. Fold it to make a 4-ply sheet approximately 2 inches by 2 inches, with one corner exactly square. Next from a single thickness of foil cut a square approximately 2 inches by 2 inches. Slip this square into a 4-ply sheet, thus making a 5-ply sheet. Then make the 5-ply leaf, using the FINISHED-LEAF PATTERN, etc. as described for making an 8-ply leaf. INSTRUCTIONS, Page 11 PATTERN FOR CLEAR-PLASTIC COVER FOR KFM CAN THE PAPER SCALE TO THE COVER OF CAN, THE KFM LEAVES SHORT SIDE OPEN EDGE CUT ALONG THREAD LINE ENDS OF MAR KS ALSO CUT ON 20 15 10 5 0 5 10 15 20 THIS LINE 8-PLY LEAF CUT ALONG ENDS OF MARKS THIRD-FOLD EDGE ALSO CUT ON 20 15 10 5 0 5 10 15 20 THIS LINE FINISHED-LEAF PATTERN (CUT OUT EXACTLY ON SIDE LINES) PAPER SCALE (TO BE CUT OUT) CAUTION: XEROX COPIES OF THE FINISHED-LEAF AND THE PATTERN PAGE (B) SCALE PATTERNS WILL BE SLIGHTLY TOO LARGE. If no epoxy glue* is available to hold down the hem and prevent the thread from slipping in the hem, cut two pieces of tape (Band-Aid tape is best; next best is masking or freezer tape; next best, Scotch tape). After first peeling off the paper backing of Band-Aid tape, cut each piece of tape l/8 inch by 1 inch long. Attach these two pieces of tape to the finished 8-ply aluminum leaf with the sticky sides up, except for their ends. As shown by the pattern on the following pattern page, secure l/8 inch of one end of a tape strip near one corner of the 8-ply aluminum foil leaf by first turning under this l/8-inch end; that is, with this end’s sticky side down. Then turn under the other l/8-inch-long end, and attach this end below the THREAD LINE. Slant each tape strip as illustrated on Pattern (C). Be sure you have read through step 18 before you do anything else. 12. 13. 14. 15. 16. Cut an 8-l/2-inch piece of fine, unwaxed, very clean thread. (Nylon twisted thread, unwaxed extra-fine nylon dental floss, or silk thread are best in this order. Nylon monofilament “invisible” thread is an excellent insulator but is too difficult for most people to handle.) Cut out Pattern (C), the guide sheet used when attaching a leaf to its suspending thread. Then tape Pattern (C) to the top of a work table. Cover the two “TAPE HERE” rectangles on Pattern (C) with pieces of tape, each piece the size of the rectangle. Then cut two other pieces of tape each the same size and use them to tape the thread ONTO the guide sheet, on top of the “TAPE HERE” rectangles. Be very careful not to touch the two l-inch parts of the thread next to the outline of the finished leaf, since oil and dirt even on clean fingers will reduce the electrical insulating value of the thread between the leaf and the top rim of the can. With the thread still taped to the paper pattern and while slightly lifting the thread with a knife tip held under the center of the thread, slip the finished leaf under the thread and into position exactly on the top of the leaf outlined on the pattern page. Hold the leaf in this position with two fingers. While keeping the thread straight between its two taped-down ends, lower the thread so that it sticks to the two plastic strips. Then press the thread against the plastic strips. With the point of the knife, hold down the center of the thread against the center of the THREAD LINE of the leaf. Then, with two fingers, carefully fold over the hem and press it almost flat. Be sure that the thread comes out of the corners of the hem. Remove the knife, and press the hem down completely flat against the rest of the leaf. Make small marks on the thread at the two points shown on the pattern page. Use a ballpoint pen if available. 17. 18. Loosen the second two small pieces of tape from the pattern paper, but leave these tapes stuck to the thread. Cut 5 pieces of Band-Aid tape, each approximately l/8 inch by l/4 inch, this small. Use 3 of these pieces of tape to secure the centers of the side edges of the leaf. Place the 5 pieces as illustrated in the SIDE VIEW sketch below. ORNL DWG 76.6542 5 PIECES OF I 1/8 IN. X 1/4 IN. I AND LATER TO CAN SIDE VIEW END VIEW SHOWING THE TWO LEAVES CHARGED (WHEN NOT CHARGED, T H E L E A V E S H A N G PERPENDICULAR AND TOUCHING.) *If using epoxy or other glue, use only a very little to hold down the hem, to attach the thread securely to the leaf and to glue together any open edges of the plied foil. Most convenient is “one hour” epoxy, applied with a toothpick. Model airplane cement requires hours to harden when applied between sheets of aluminum foil. To make sure no glue stiffens the free thread beyond the upper corners of the finished leaf, put no glue within l/4 inch of a point where thread will go out from the folded hem of the leaf. The instructions in step 11 are for persons lacking “one hour” epoxy or the time required to dry other types of glue. Persons using glue instead of tape to attach the leaf to its thread should make appropriate use of the pattern on the following page and of some of the procedures detailed in steps 12 through 18. COVER THE TWO "TAPE HERE" RECTANGLES WITH SAME-SIZED PIECES OF TAPE, IN ORDER TO KEEP FROM TEARING THIS PAPER WHEN REMOVING TWO ADDITIONAL PIECES OF TAPE. THEN, BY PUTTING TWO OTHER PIECES OF TAPE THIS SAME SIZE ON TOP OF THE FIRST TWO PIECES, TAPE THE THREAD ONTO THIS GUIDE SHEET, AND LATER ATTACH A LEAF TO THE TAPED-DOWN THREAD. TAPE HERE TO HOLD THREAD SECURELY OVER THREAD LINE USE BALLPOINT PEN TO MARK THREAD HERE MARK THREAD HERE TAPE TAPE HERE THREAD LINE I I , THREAD LINE HERE DO NOT TOUCH DO NOT TOUCH OR MARK THIS OF THREAD THIS I-INCH PART l-INCH PART OF THE THREAD OF FINISHED BAND-AID PLASTIC (1/8” X 1”) ALUMINUM-F0I L WITH STICKY SIDE UP AND LEAF ENDS FOLDED UNDER SO AS TO STICK TO ALUMINUM (OR USE A VERY LITTLE EPOXY.) PATTERN (C) (Cut out this guide along its border lines and tape to the top of a work table.) WARNING: The parts of the thread that will be inside the can and on which the leaf will be suspended must serve to insulate the high-voltage electrical charges to be placed on the leaf. Therefore, the suspended parts of the thread must be kept very clean. 4. XI. Install the Aluminum-Foil Leaves 5. Use the two small pieces of tape stuck to the ends of a leaf-suspending thread to attach the thread to the outside of the can. Attach the tapes on opposite sides of the can, so as to suspend the leaf inside the can. See END VIEW sketch. Each of the two marks on the attached thread MUST rest exactly on the top of the rim of the can, preferably in two very small notches filed in the top of the rim of the can. Each of these two marks on a thread should be positioned exactly above one of the two points shown on the pattern wrapped around the can. Be sure that the hem-side of each of the two leaves faces outward. See END VIEW sketch. Next, the suspending thread of the first leaf should be taped to the top of the rim. Use a piece of Band-Aid only about l/8 in. x l/4 in., sticking it to the rim of the can so as barely to cover the thread on the side where the second leaf will be suspended. Make sure no parts of the tapes are inside the can. Position and secure the second leaf, being sure that: a. b. C. d. e. f. g. The smooth sides of the two leaves are smooth (not bent) and face each other and are flush (= “right together”) when not charged. See END VIEW sketch and study the first photo illustration, “An Uncharged KFM”. The upper edges of the two leaves are suspended side by side and at the same distance below the top of the can. The leaf-suspending threads are taped with Band-Aid to the top of the rim of the can (so that putting the cover on will not move the threads). No parts of the leaf-suspending threads inside the can are taped down to the can or otherwise restricted. The leaf-suspending parts of the threads inside the can do not cross over, entangle or restrict each other. The threads come together on the top of the rim of the can, and that the leaves are flat and hang together as shown in the first photo illustration, “An Uncharged KFM.” If the leaves do not look like these photographed leaves, make new, better leaves and install them. Cover with tape the parts of the threads that extend down the outside of the can, and also cover with more tape the small pieces of tape near the ends of the threads on the outside of the can. 6. To make the SEAT, cut a piece of a wooden pencil, or a stick, about one inch long and tape it securely to the side of the can along the center line marked SEAT on the pattern. Be sure the upper end of this piece of pencil is at the same position as the top of the location for the SEAT outlined on the pattern. The top of the SEAT is 3/4 inch below the top of the can. Be sure not to cover or make illegible any part of the table printed on the paper pattern. Cut out one of the “Reminders for Operators” and glue and/or tape it to the unused side of the KFM. Then it is best to cover all the sides of the finished KFM with clear plastic tape or varnish. This will keep sticky-tape on the end of an adjustment thread or moisture from damaging the “Reminders” or the table. XII. Make the Plastic Cover Cut out the paper pattern for the cover from the Pattern Page (B). From a piece of clear, strong plastic, cut a circle approximately the same size as the paper pattern. (Storm-window polyethylene plastic, 4 mils thick, is best.) Stretch the center of this circular piece of clear plastic over the open end of the can, and pull it down close to the sides of the can, making small tucks in the “skirt,” so that there are no wrinkles in the top cover. Hold the lower part of the “skirt” in place with a strong rubber band or piece of string. (If another can having the same diameter as the KFM can is available, use it to make the cover -- to avoid the possibility of disturbing the leaf-suspending threads.) Make the cover so it fits snugly, but can be taken r COVER off and replaced readily. (CLEAR KEEP THIS SMALL PART PLASTIC) Just below the top of the rim of the can, bind the covering plastic in place w i t h a l/4-inch-wide piece of strong tape. (Cloth duct tape is best. If only freezer or masking tape is available, use two thicknesses.) Keep vertical the small part of the tape that presses against the rim of the can while pulling the OF THE 1/4 IN. TAPE VERTICAL WHILE PULLING TAPE AROUND RIM OF CAN OF CAN RUBBER BAND OR STRING EDGE OF PLASTIC I COVER length of the tape horizontally around the can so as to bind the top of the plastic cover snugly to the rim. If this small part of the tape is kept vertical, the lower edge of the tape will not squeeze the plastic below the rim of the can to such a small circumference as to prevent the cover from being removed quite easily. INSTRUCTIONS PAGE 15 REMINDERS FOR OPERATORS THE DRYING AGENT INSIDE A KFM IS O.K. IF, WHEN THE CHARGED KFM IS NOT EXPOSED TO RADIA- TION, ITS READINGS DECREASE BY 1 MM OR LESS IN 3 HOURS. READING: WITH THE READING EYE 12 INCHES VERTICALLY ABOVE THE SEAT, NOTE ON THE MM SCALE THE SEPARATION OF THE LOWER EDGES OF THE LEAVES. IF THE RIGHT LEAF IS AT 10 MM AND THE LEFT LEAF IS AT 7 MM, THE KFM READS 17 MM. NEVER TAKE A READING WHILE A LEAF IS TOUCHING A STOP-THREAD. NEVER USE A K F M READING THAT IS LESS THAN 5MM. REMINDERS FOR OPERATORS FINDING HOW LONG IT TAKES TO THE DRYING AGENT INSIDE A KFM GET A CERTAIN R DOSE: IF IS THE CHARGED DOSE RATE IS 1.6 R/HR OUTSIDE KFM IS NOT EXPOSED TO RADIA- AND A PERSON IS WILLING TO TION, ITS READINGS DECREASE TAKE A 6 R DOSE, HOW LONG CAN BY 1 MM OR LESS IN 3 HOURS. HE REMAIN OUTSIDE? ANSWER: FINDING HO" LONG IT TAKES TO G E T A C E R T A I N R A I N DOSE RATE IS R/HR AND A PERSON IS WILLING TO TAKE A 6 R DOSE, HOW LONG CAN HE REMAIN OUTSIDE? ANSWER: 6 R 1.6 R/HR = 3.75 HR = 3 HOURS AND 45 MINUTES. FINDING A DOSE RATE: IF BEFORE XPOSURE A KFM READS 17 MM AND IF AFTER A l-MINUTE EXPOSURE IT READS 5 MM, THE DIFFERENCE IN READINGS IS 12 MM, THE AT- TACHED TABLE SHOWS THE DOSE RATE WAS 9.6 R/HR DURING THE EXPOSURE. FINDING A DOSE: IF A PERSON WORKS OUTSIDE FOR 3 HOURS WHERE THE DOSE RATE IS 2 R/HR, WHAT IS HIS RADIATION DOSE? ANSWER 3 HR x 2 R/HR = 6 R. 6 R 1.6 R/HR = 3.75 HR = 3 HOURS AND 45 MINUTES. FALLOUT RADIATION GUIDES FOR LY EXPOSED TO A TOTAL RADIA- TION DOSE OF MORE THAN 100 R DURING A 2-WEEK PERIOD 6 R PER DAY CAN BE TOLERATED UP TO TW0 MONTHS WITHOUT LOSING THE ABILITY TO WORK. EXPOSURE A KFM R FINDING A DOSE RATE IF BEFORE EADS 17 MM AND IF AFTER A l-MINUTE EXPOSURE 100 R IN A WEEK OR LESS IS NOT IT READS 5 MM, THE DIFFERENCE LIKELY TO SERIOUSLY SICKEN. IN READINGS IS 12 MM, THE AT- TACHED TABLE SHOWS THE DOSE IN A FEW DAYS IS LIKELY RATE WAS 9.6 R/HR DURING THE TO PROVE FATAL UNDER POST- EXPOSURE. ATTACK CONDITIONS. FINDING A DOSE: IF A PERSON WORKS OUTSIDE FOR 3 HOURS 600 R IN A WEEK OR LESS IS CERTAIN TO CAUSE DEATH WHERE THE DOSE RATE IS 2 R/HR, WHAT IS HIS RADIATION DOSE? WITHIN A FEW WEEKS. ANSWER 3 HR x 2 R/HR = 6 R. FALLOUT RADIATION GUIDES FOR LY EXPOSED TO A TOTAL RADIA- TION DOSE OF MORE THAN 100 R DURING A 2-WEEK PERIOD: 6 R PER DAY CAN SE TOLERATED UP TO TWO MONTHS WITHOUT LOSING THE ABILITY TO WORK. IN A WEEK OR LESS IS LIKELY TO SERIOUSLY SICKEN. 350 R IN A FEW DAYS IS LIKELY TO PROVE FATAL UNDER POST- ATTACK CONDITIONS. 600 A IN A WEEK OR LESS IS CERTAIN TO CAUSE DEATH WITHIN A FEW WEEKS.