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 the following priorities: (1) build or improve a high-protection-factor shelter (if
outside. Civil defense teams could use broadcasts of surviving radio stations to possible, a shelter covered with 2 or 3 feet of earth and separate from flammable
give listeners a general idea of the fallout radiation in some broadcast areas. buildings); (2) make and install a KAP (a homemade shelter-ventilating pump) --
However, the fallout radiation would vary widely from point to point and the if instructions and materials are available; (3) store at least 15 gallons of water for
measurements would be made too far from most shelters to make them accurate each shelter occupant -- if containers are available; (4) assemble all materials for
enough to use safely. Therefore, each shelter should have some dependable 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 III. How toUse These Instructions to Best Advantage
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 1. Read ALOUD all of these instructions through Section VII, “Tools Needed,”
during the first few days, and then decrease more and more slowly, makes it very before doing anything else.
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 2. Next assemble all of the needed materials and tools.
to control the radiation doses they receive. In order to effectively control the
radiation doses, a dependable measuring instrument is needed to determine the 3. Then read ALOUD ALL of each section following Section VII before beginning
doses they receive while they are in the shelter and while they are outside for to make the part described in that section.
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 A FAMILY THAT FAILS TO READ ALOUD ALL OF EACH
good. SECTION DESCRIBING HOW TO MAKE A PART, BEFORE ?
BEGINNING TO MAKE THAT PART, WILL MAKE AVOID-
Untrained families, guided only by these written instructions and using only low ABLE MISTAKES AND WILL WASTE TIME.
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 4. Have different workers, or pairs of workers, make the parts they are best
about 1 hours, average untrained families have been able to successfully use this qualified to make. For example, a less skilled worker should start making the
fallout meter to measure dose rates and to calculate radiation doses received, drying agent (as described in Section VIII) before other workers start making
permissible times of exposure, etc. other parts. The most skilled worker should make and install the
aluminum-foil leaves (Sections X and XI).
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 5. Give workers the sections of the instructions covering the parts they are to
meters. In the United States in 1976 a commercially available ion chamber fallout build--so they can follow the step-by-step instructions, checking off with a
meter that has as high a range as a KFM for gamma radiation dose-rate pencil each step as it is completed.
measurements retailed for $600.
6. Discuss the problems that arise. The head of the family often can give better
Before a nuclear attack occurs is the best time to build, test and learn how to use a answers if he first discusses the different possible interpretations of some
KFM. However, this instrument is so simple that it could be made even after instructions with other family members, including teenagers.
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 7. After completing one KFM and learning to use it, if time permits make a
shelter. second KFM--that should be a better instrument.
 If a KFM is made with the specified dimensions and of the specified materials, its
accuracy is automatically and permanently established. Unlike most radiation
A KFM is a simple electroscope fallout meter with measuring instruments, a KFM never needs to be calibrated or tested with a
which fallout radiation can be measured accurately. radiation source, if made and maintained as specified and used with the following
To use a KFM, an electrostatic charge must first be table that is based on numerous calibrations made at Oak Ridge National Labor-
placed on its two separate aluminum-foil leaves. atory.
These leaves are insulated by being suspended
separately on clean, dry insulating threads. 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
To take accurate readings, the air inside a KFM must
two leaves in their discharged position when the KFM is resting on a horizontal
be kept very dry by means of drying agents such as
surface. A reading of the separation of the leaves is taken by noting the number of
dehydrated gypsum (easily made by heating gypsum
wallboard, “sheetrock”) or silica gel. (Do not use millimeters that the lower edge of one leaf appears to be on, on one side of the zero
calcium chloride or other salt.) Pieces of drying agent mark on the scale, and almost at the same time noting the number of millimeters
are placed on the bottom of the ionization chamber the lower edge of the other leaf appears to be on, on the other side of the zero mark.
(the housing can) of a KFM. 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
An electrostatic charge is transferred from a homemade electrostatic charging the lower edges of the leaves of a KFM appearing to be 9 mm on the right and zero
device to the two aluminum-foil leaves of a KFM by means of its charging-wire. and 10 on the left, giving a KFM reading of 19 mm. (Usually the lower edges of the
The charging-wire extends out through the transparent plastic cover of the KFM. leaves are not at the same distance from the zero mark.)

When the two KFM leaves are charged electrostati- As will be fully explained later, the radiation dose rate is determined
cally, their like charges (both positive or both by:
negative) cause them to be forced apart. When fallout TABLE USED TO FIND DOSE RATES (R/HR)
gamma radiation (that is similar to X rays but more FROM KFY READINGS
1. charging and reading the KFM before
energetic) strikes the air inside the ionization chamber exposure;
of a KFM, it produces charged ions in this enclosed TIME INTERVAL OF AN EXPOSURE
air. These charged ions cause part or all of the 2. exposing it to radiation for a specified READ-
electrostatic charge on the aluminum-foil leaves to be INGS R/HR R/HR R/HR R/HR R/HR
time in the location where measure- 2 mm 6.2 1.6 0.4 0.1 0.03
discharged. As a result of losing charge, the two
ment of the dose rate is needed -- when 4 mm 12. 3.1 0.8 0.2 0.06
KFM leaves move closer together. 4.6 1.2 0.3 0.08
outdoors, holding the KFM about 3 ft. 6 mm 19.
above the ground; 8 mm 2 5 . 6.2 1.6 0.4 0.10
To read the separation of the lower edges of the two 10 mm 31. 7.7 2.0 0.5 0.13
KFM leaves with one eye, look straight down on the 12mm 37. 9.2 2.3 0.6 0.15
leaves and the scale on the clear plastic cover. Keep 3. reading the KFM after its exposure; 14mm 43. 11. 2.7 0.7 0.18
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 4. calculating, by subtraction, the difference between the reading taken before
this exact distance, place the lower end of a 12-inch ruler on the SEAT, while the exposure and the reading taken after exposure;
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 5. using this table to find what the dose rate was during the exposure -- as will be
makes the reading more accurate. 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 C. A Charged KFM. Note
following photos and read their captions. the separation of the
upper edges of its two
A. An Uncharged KFM. The charging wire has been pulled to one side by its leaves. T h e charging-
adjustment-thread. This wire has been raised to
photo was taken looking an almost horizontal pos-
straight down at the ition so that its lower end
upper edges of the two is too far above the alu-
flat, 8-ply aluminum minum leaves to permit
leaves. At this angle the electrical leakage from
leaves are barely visible, the leaves back up the
hanging vertically side by charging-wire and into
side directly under the the outside air.
zero mark, touching each
other and with their ends Also note the SEAT, a
even. Their suspension- piece of pencil taped to
threads insulate the the right side of the can,
leaves. These threads opposite the charging
are almost parallel and wire.
touch (but do not cross)
each other where they D. Reading a KFM. A 12-
extend over the top of the inch ruler rests on the
rim of the can. SEAT and is held vert-
ical, while the reader’s
eyebrow touches the
upper end of the ruler.
B. Charging a KFM by a Spark-Gap Discharge from a Tape That Has Been The lower edge of the
Electrostatically Charged by Being Unwound Quickly. Note that the charged right leaf is under 8 on
tape is moved so that its the scale and the lower
surface is perpendicular edge of the left leaf is
to the charging-wire. under 6 on the scale,
giving a KFM reading of
The high-voltage electro- 14.
static charge on the un-
wound tape (that is an For accurate radiation
insulator) jumps the measurements, a KFM
spark-gap between the should be placed on an
tape and the upper end of approximately horizontal
the charging-wire, and surface, but the charges
then flows down the on its two leaves and
charging-wire to charge their displacements do
the insulated aluminum- not have to be equal.
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.)
 INSTRUCTIONS, Page 5
ADJU STMENT THREAD
(NYLON IS
AND
TAPE
TO FIT OVER SEAT
ON CAN TAPE
EDGE
OF SKIRT OF COVER
REMOVABLE TRANSPARENTCOVER
AND CHARGING WIRE
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 . F o r the KFM: (In the following list, when more than one alternative material
is given, the best material is listed first.) 11. Two strong rubber bands, or string.

1. Any type metal can, approximately 2-9/16 inches in diameter inside and B. For the Charging Devices:
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 1. Most hard plastic rubbed on dry paper. This is the best method.
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 -- a. Plexiglas and most other hard plastics, such as are used in drafts-
as described in Section IX of these instructions.) men’s triangles, common smooth plastic rulers, etc. -- at least 6 inches
long.
2. 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 O Z.) (If b. Dry paper -- Smooth writing or typing paper. Tissue paper, news-
only “Heavy Duty” or “Extra Heavy Duty” aluminum foil is available, paper, or facial tissue such as Kleenex, or toilet paper are satisfactory
make 5-ply leaves rather than 8-ply leaves of standard foil; the resultant for charging, but not as durable.
fallout meter will be almost as accurate.)
2. Scotch Magic Transparent Tape (3/4 inch width is best), or Scotch
3. Doorbell-wire, or other light insulated wire (preferably but not necessarily . Transparent Tape, or P.V.C. (Polyvinyl chloride) insulating electrical
a single-strand wire inside the insulation) -- 6 inches. tapes, or a few of the other common brands of Scotch-type tapes. (Some
plastic tapes do not develop sufficiently high-voltage electrostatic charges
4. Any type of lightweight thread (preferably but not necessarily nylon). when unrolled quickly.) This method cannot be used for charging a KFM
(Best is twisted nylon thread; next best, unwaxed lightweight nylon dental inside a dry-bucket, needed for charging when the air is very humid.
floss; next best, silk; next best, polyester.) -- 3 feet. (Thread should be
CLEAN, preferably not having been touched with fingers. Monofilament C. For Determining Dose Rates and Recording Doses Received:
nylon is too difficult to see, handle, and mark.)
1. A watch -- preferably with a second hand.
5. 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 2. A flashlight or other light, for reading the KFM in a dark shelter or at
and rather clear plastic will serve. The strong clear plastic used to wrap night.
pieces of cheese, if washed with hot water and soap, is good. Do not use
weak plastic or cellophane. 3. Pencil and paper -- preferably a notebook.

6. Cloth duct tape (“silver tape”), or masking tape, or freezer tape, or D. For the Dry-Bucket: (A KFM must be charged inside a dry-bucket if the air is
Scotch-type tape -- about 10 square inches. (Save at least 10 feet of Scotch very humid, as it often is inside a crowded,
Magic Transparent Tape for the charging device.) long-occupied shelter lacking adequate forced vent-
ilation.)
7. Band-Aid tape, or masking tape, or freezer tape, or Scotch transparent
tape, or other thin and very flexible tapes -- about 2 square inches. 1. A large bucket, pot, or can, preferably with a top diameter of at least 11
inches.
8. Gypsum wallboard (sheetrock) -- about l/2 square foot, best about 1/2
inch thick. (To make the essential drying agent.) 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
9. Glue -- not essential, but useful to replace Band-Aid and other thin tapes. used.
“One hour” epoxy is best. Model airplane cement is satisfactory.
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. Two plastic bags 14 to 16 inches in circumference, such as ordinary plastic VIII. Make the Drying Agent
bread bags. The original length of these bags should be at least 5 inches -- The Easiest Part to Make, but Time Consuming --
greater than the height of the bucket.
For a KFM to measure radiation accurately, the air inside its ionization
5. About one square foot of wall board (sheetrock), to make anhydrite drying chamber must be kept very dry. An excellent drying agent (anhydrite) can be
agent. made by heating the gypsum in ordinary gypsum wallboard (sheetrock). Do
NOT use calcium chloride.
6. 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. 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,
7. Strong rubber bands -- enough to make a loop around the bucket. Or easiest done by first wetting the paper. [Since water vapor from normal air
string. 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
8. Four square feet of aluminum foil, to make a vapor-proof cover -- useful, made before the attack and kept ready inside the shelter for replacement. The
but not essential. 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
VI. Useful but not Essential Materials used.]
--Which Could be Obtained Before a Crisis--
Break the white gypsum filling into small pieces and make the
1. An airtight container (such as a large peanut butter jar) with a mouth at least 4 largest no more than l/2 in. across. (The tops of pieces larger
inches wide, in which to keep a KFM, along with some drying agent, when it is than this may be too close to the aluminum foil leaves.) If the
not being used. Keeping a KFM very dry greatly extends the time during gypsum is dry, using a pair of pliers makes breaking it easier.
which the drying agent inside the KFM remains effective. Make the largest side of the largest pieces no bigger than this.

2. Commercial anhydrite with a color indicator, such as the drying agent Drierite. Dry gypsum is not a drying agent. To drive the water out of the gypsum
This granular form of anhydrite remains light blue as long as it is effective as a molecules and produce the drying agent (anhydrite), heat the gypsum in an
drying agent. Obtainable from laboratory supply sources. 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.
VII. Tools Needed
If sufficient aluminum foil and time are available, it is best to heat the gypsum
Small nail sharpened and store the anhydrite as follows:
Stick, or a wooden tool handle
(best 2 - 2 1/2 inch diameter and at least 12 inches long) a. So that the right amount of anhydrite can be taken quickly out of its
Hammer storage jar, put enough pieces of gypsum in a can with the same diameter
Pliers as the KFM, measuring out a batch of gypsum that almost covers the
Scissors bottom of the can with a single layer.
Needle quite a large sewing needle, but less than 2 1/2 inches long b. Cut a piece of aluminum foil about 8 in. x 8 in. square, and fold up its
Knife with a small blade -- sharp edges to form a bowl-like container in which to heat one batch of gypsum
Ruler (12 inches) 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.
 3. Cut out the PAPER PATTERN TO WRAP AROUND KFM CAN. (Cut
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 one pattern out of the following Pattern Page A.) Glue (or tape) this
aluminum-covered “ball” of each batch of anhydrite. 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
f. Promptly seal the batches in airtight jars or other airtight containers, and is being wrapped. (If the pattern is too wide to fit flat between the rims
keep containers closed except when taking out an aluminum-covered of the can, trim a little off its lower edge.)
“ball.”
4. Sharpen a small nail, by filing or rubbing on concrete, for use as a punch
6. Since anhydrite absorbs water from the air very rapidly, quickly put it in a dry to make the four holes needed to install the stop-threads in the ionization
airtight container while it is still quite hot. A Mason jar is excellent. chamber (the can). (The stop-threads are insulators that stop the
charged aluminum leaves from touching the can and being discharged.)
7. 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 5. Have one person hold the
bottom of the can, with no piece on top of other pieces. can over a horizontal stick or
8. To remove anhydrite from a KFM, use a pair of scissors or tweezers as a round wooden tool-handle, PUNCH SMALL
forceps, holding them in a vertical position and not touching the leaves. that ideally has a diameter
about as large as the dia- SHARPENED
IX. Make the Ionization Chamber of the KFM meter of the can. Then a SMALL NAIL
(To Avoid Mistakes and Save Time, second person can use the
Read All of This Section ALOUD Before Beginning Work.) sharpened nail and a ham-
mer to punch four very small
Remove the paper label (if any) from an ordinary 8-ounce can from which the holes through the sides of
top has been smoothly cut. Wash the can with soap and water and dry it. (An the can at the points shown
8-ounce can has an inside diameter of about 2-9/16 inches and an inside height by the four crosses on the HANDLE INSIDE
of about 2-7/8 inches.) pattern. Make these holes
just large enough to run a
Skip to step 3 if an 8-ounce can is available. If an 8-ounce can is not available, needle through them, and
reduce the height of any other can having an inside diameter of about 2-9/16 then move the needle in the
inches (such as most soup cans, most pop cans, or most beer cans). To cut off holes so as to bend back the
the top part of a can, first measure and mark the line on which to cut. Then to obstructing points of metal.
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 TO NEEDLE TOGGLE
6. The stop-threads can be
thicknesses of paper and the diameter (ideally) is only slightly less than the installed by using a needle SMALL THIS SMALL
diameter of the can. to thread a single thread TOGGLE
through all four holes. Use TIED TO 1/2 in. FROM
One person should hold the can over the paper-covered stick while a second a very clean thread, prefer- CAN; LATER
person cuts the can little by little along the marked cutting line. If leather END OF
ably nylon, and do not touch THREAD THREAD IS
gloves are available, wear them. To cut the can off smoothly, use a file, or use the parts of this thread that
a hacksaw drawn backwards along the cutting line. Or cut the can with a will be inside the can and
sharp, short blade of a pocketknife by: (1) repeatedly stabbing downward will serve as the insulating STOP-
vertically through the can into the paper, and (2) repeatedly making a cut about stop-threads. Soiled threads THREAD
l/4 inch long by moving the knife into a sloping position, while keeping its SIDE OF CAN
are poor insulators.
point still pressed into the paper covering the stick. (See illustrations.)
Next, smooth the cut edge, and cover it with small pieces of freezer tape or
other flexible tape. SINGLE THREAD THREADED THROUGH 4 HOLES
TO MAKE 2 STOP-THREADS
 CUT EXACTL Y ON SIDE LINES
TOP OF CAN

FASTEN THREADS HOLDING ALUMINUM LEAVES HERE

OF l-IN. PENCIL (FOR RULER REST)

TABLE USED TO FIND DOSE RATES (R/HR) SEAT

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
HOLE 2 mm 6.2 1.6 0.4 0.1 0.03 HOLES FOR STOP-THREAD
FOR 4mm 12. 3.1 0.8 0.2 0.06 FOR
STOP- 6mm 19. 4.6 1.2 0.3 0.08 STOP-
THREAD 8mm 25. 6.2 1.6 0.4 0.10 THREAD
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 BOTTOM OF CAN (ABOVE LIP)

CUT EXACTL Y ON SIDE LINES

TOP OF CAN

FASTEN THREADS HOLDING ALUMINUM LEAVES HERE

OF I-IN. PENCIL (FOR RULER REST)

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 S)

TIME INTERVAL OF AN EXPOSURE

15 SEC. 1 MIN. 4MIN. 16MIN. 1 HR.
R/HR R/HR R/HR R/HR R/HR
HOLE
6.2 1.6 0.4 0.1 0.03 HOLES FOR STOP-THREAD
FOR 12. 3.1 0.8 0.2 0.06 FOR
STOP- 19. 4.6 1.2 0.3 0.08 STOP-
THREAD 25. 6.2 1.6 0.4 0.10 THREAD
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 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 7. While holding a straight edge
preceding sketch) to the long end of the thread. (This toggle can easily be made along the THREAD LINE of the
of a very small sliver of wood cut about 3/8 in. long.) After the thread has been pattern, press with a sharp pencil
pulled through the four holes, attach a second toggle to the thread, about l/2 inch so as to make a shallow groove for
from the part of the thread that comes out of the fourth hole. Then the thread can the THREAD LINE on the 8-ply
be pulled tightly down the side of the can and the second small toggle can be aluminum sheet. Also using a
taped securely in place to the side of the can. (If the thread is taped down without sharp pencil, trace around the top THREAD
a toggle, it is likely to move under the tape.) and side of the pattern, so as to LINE
indent (groove) the 8-ply foil.
The first toggle and all of the four holes also should be covered with tape, to THE
prevent air from leaking into the can after it has been covered and is being used 8. Remove the pattern, and cut out SQUARE
as an ionization chamber. the 8-ply aluminum foil leaf. CORNER
OF 8-PLY
9. While holding a straight edge SHEET
along the indented THREAD
LINE, lift up the OPEN EDGE of THIRD-FOLD EDGE
X. ‘Make Two Separate 8-Ply Leaves of Standard the 8-ply sheet (keeping all 8 plies
[Not Heavy Duty*] Aluminum Foil OF 8-PLY SHEET
together) until this edge is ver-
tical, as illustrated. Remove the
straight edge, and fold the 8-ply
Proceed as follows to make each leaf: aluminum along the THREAD
1. Cut out a piece of standard aluminum LINE so as to make a flat-folded
foil approximately 4 inches by 8 inches.
hem.
8-PLY
2. Fold the aluminum foil to make a 2-ply SHEET
10. Open the flat-folded hem of the
(= 2 thicknesses) sheet approximately 4 finished leaf until the 8-ply leaf is
inches by 4 inches. almost flat again, as shown by the
THE SQUARE
pattern, from which the FIN-
CORNER ISHED-LEAF PATTERN has al-
3. Fold this 2-ply sheet to make a 4-ply
sheet approximately 2 inches by 4 THIRD-FOLD EDGE ready been cut.
inches.
11. Prepare to attach the aluminum-
4. Fold this 4-ply sheet to make an 8-ply sheet (8 sheets thick) approximately 2 foil leaf to the thread that will
inches by 2 inches, being that the two halves of the second-fold edge are suspend it inside the KFM.
exactly together. This third folding makes an 8-ply aluminum foil sheet with
one comer exactly square.

5. Cut out the FINISHED-LEAF PATTERN, found on the following Pattern Page *If only heavy duty aluminum foil (sometimes called “extra heavy duty”) is
B. Note that this pattern is NOT a square and that it is smaller than the 8-ply available, make 5-ply leaves of the same size, and use the table for the 8-ply KFM
sheet. Flatten the 8 thicknesses of aluminum foil with the fingers until they to determine radiation dose rates. To make a 5-ply leaf, start by cutting out a
appear to be a single thin, flat sheet. 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
6. Hold the FINISHED-LEAF PATTERN on top of the 8-ply aluminum foil single thickness of foil cut a square approximately 2 inches by 2 inches. Slip this
sheet, with the pattern’s THIRD-FOLD EDGE on top of the third-fold edge of square into a 4-ply sheet, thus making a 5-ply sheet. Then make the 5-ply leaf,
the 8-ply a l u m i n u m s h e e t . Be sure that one lower c o r n e r of the using the FINISHED-LEAF PATTERN, etc. as described for making an 8-ply leaf.
FINISHED-LEAF PATTERN is on top of the exactly square corner of the
8-ply aluminum sheet.
 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
ALSO CUT ON 20 15 10 5 0 5 10 15 20
THIRD-FOLD EDGE
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 17. Loosen the second two small pieces of tape from the pattern paper, but leave
thread from slipping in the hem, cut two pieces of tape (Band-Aid tape is these tapes stuck to the thread.
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 18. Cut 5 pieces of Band-Aid tape, each approximately
tape l/8 inch by 1 inch long. Attach these two pieces of tape to the l/8 inch by l/4 inch, this small.
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 Use 3 of these pieces of tape to secure the centers of the side edges of the leaf.
inch of one end of a tape strip near one corner of the 8-ply aluminum foil Place the 5 pieces as illustrated in the SIDE VIEW sketch below.
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 ORNL DWG 76.6542
illustrated on Pattern (C).

Be sure you have read through step 18 before you do anything else.

12. 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.) 5 PIECES OF
1/8 IN. X 1/4 IN.
Cut out Pattern (C), the guide sheet used when attaching a leaf to its I
suspending thread. Then tape Pattern (C) to the top of a work table. I
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 AND LATER TO CAN
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 SIDE VIEW END VIEW
the top rim of the can. SHOWING THE TWO LEAVES CHARGED
(WHEN NOT CHARG E D , THE LEAVES HANG
13. With the thread still taped to the paper pattern and while slightly lifting PERPENDICULAR AND TOUCHING.)
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. *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
14. While keeping the thread straight between its two taped-down ends, plied foil. Most convenient is “one hour” epoxy, applied with a toothpick. Model
lower the thread so that it sticks to the two plastic strips. Then press the airplane cement requires hours to harden when applied between sheets of
thread against the plastic strips. 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
15. With the point of the knife, hold down the center of the thread against go out from the folded hem of the leaf.
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 The instructions in step 11 are for persons lacking “one hour” epoxy or the time
thread comes out of the corners of the hem. Remove the knife, and press required to dry other types of glue. Persons using glue instead of tape to attach the
the hem down completely flat against the rest of the leaf. 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.
16. Make small marks on the thread at the two points shown on the pattern
page. Use a ballpoint pen if available.
 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.
USE BALLPOINT PEN TO
MARK THREAD HERE MARK THREAD HERE
TAPE TAPE
I I HERE
HERE THREAD LINE , THREAD LINE

TAPE HERE TO HOLD DO NOT TOUCH DO NOT TOUCH

THREAD SECURELY OR MARK THIS THIS I-INCH PART
OF THREAD
OVER THREAD LINE l-INCH PART
OF FINISHED BAND-AID PLASTIC (1/8” X 1”)
OF THE THREAD
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.
 XI. Install the Aluminum-Foil Leaves 5. 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
Use the two small pieces of tape stuck to the ends of a leaf-suspending thread same position as the top of the location for the SEAT outlined on the pattern.
to attach the thread to the outside of the can. Attach the tapes on opposite The top of the SEAT is 3/4 inch below the top of the can. Be sure not to cover
sides of the can, so as to suspend the leaf inside the can. See END VIEW or make illegible any part of the table printed on the paper pattern.
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 6. Cut out one of the “Reminders for Operators” and glue and/or tape it to the
top of the rim of the can. Each of these two marks on a thread should be unused side of the KFM. Then it is best to cover all the sides of the finished
positioned exactly above one of the two points shown on the pattern wrapped KFM with clear plastic tape or varnish. This will keep sticky-tape on the end of
around the can. Be sure that the hem-side of each of the two leaves faces an adjustment thread or moisture from damaging the “Reminders” or the
outward. See END VIEW sketch. table.

Next, the suspending thread of the first leaf should be taped to the top of the XII. Make the Plastic Cover
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 Cut out the paper pattern for the cover from the Pattern Page (B).
be suspended. Make sure no parts of the tapes are inside the can.
From a piece of clear, strong plastic, cut a circle approximately the same size
Position and secure the second leaf, being sure that: as the paper pattern. (Storm-window polyethylene plastic, 4 mils thick, is
best.)
a. 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 Stretch the center of this circular piece of clear plastic over the open end of the
VIEW sketch and study the first photo illustration, “An Uncharged can, and pull it down close to the sides of the can, making small tucks in the
KFM”. “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
b. The upper edges of the two leaves are suspended side by side and at the can having the same diameter as the KFM can is available, use it to make the
same distance below the top of the can. cover -- to avoid the possibility of disturbing the leaf-suspending threads.)

r
C. The leaf-suspending threads are taped with Band-Aid to the top of the rim Make the cover so it fits
of the can (so that putting the cover on will not move the threads). snugly, but can be taken COVER
off and replaced readily. (CLEAR
KEEP THIS SMALL PART PLASTIC)
d. No parts of the leaf-suspending threads inside the can are taped down to
Just below the top of the OF THE 1/4 IN. TAPE
the can or otherwise restricted.
rim of the can, bind the VERTICAL
e. The leaf-suspending parts of the threads inside the can do not cross over, covering plastic in place WHILE PULLING TAPE
entangle or restrict each other. w i t h a l/4-inch-wide AROUND RIM OF CAN OF CAN
piece of strong tape. RUBBER
f. The threads come together on the top of the rim of the can, and that the (Cloth duct tape is best. If BAND
leaves are flat and hang together as shown in the first photo illustration, only freezer or masking
OR
“An Uncharged KFM.” tape is available, use two
STRING
thicknesses.)
g. If the leaves do not look like these photographed leaves, make new, better EDGE
Keep vertical the small I
leaves and install them. OF PLASTIC
part of the tape that COVER
4. Cover with tape the parts of the threads that extend down the outside of the presses against the rim of
can, and also cover with more tape the small pieces of tape near the ends of the the can while pulling the
threads on the outside of the can. 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 REMINDERS FOR OPERATORS
THE DRYING AGENT INSIDE A KFM FINDING HOW LONG IT TAKES TO THE DRYING AGENT INSIDE A KFM FINDING HO" LONG IT TAKES TO
IS O. K.I F, WHEN THE CHARGED GET A CERTAIN R DOSE: IF IS THE CHARGED G E T A C E R T A I N R A I N
KFM IS NOT EXPOSED TO RADIA- DOSE RATE IS 1.6 R/HR OUTSIDE KFM IS NOT EXPOSED TO RADIA- DOSE RATE IS R/HR
TION, ITS READINGS DECREASE AND A PERSON IS WILLING TO TION, ITS READINGS DECREASE AND A PERSON IS WILLING TO
BY 1 MM OR LESS IN 3 HOURS. TAKE A 6 R DOSE, HOW LONG CAN BY 1 MM OR LESS IN 3 HOURS. TAKE A 6 R DOSE, HOW LONG CAN
READING: WITH THE READING EYE HE REMAIN OUTSIDE? ANSWER: HE REMAIN OUTSIDE? ANSWER:
12 INCHES VERTICALLY ABOVE THE 6 R 1.6 R/HR = 3.75 HR = 6 R 1.6 R/HR = 3.75 HR =
SEAT, NOTE ON THE MM SCALE THE
SEPARATION OF THE LOWER EDGES 3 HOURS AND 45 MINUTES. 3 HOURS AND 45 MINUTES.
OF THE LEAVES. IF THE RIGHT
LEAF IS AT 10 MM AND THE LEFT FALLOUT RADIATION GUIDES FOR FALLOUT RADIATION GUIDES FOR
LEAF IS AT 7 MM, THE KFM READS
17 MM. NEVER TAKE A READING LY EXPOSED TO A TOTAL RADIA- LY EXPOSED TO A TOTAL RADIA-
WHILE A LEAF IS TOUCHING A TION DOSE OF MORE THAN 100 R TION DOSE OF MORE THAN 100 R
STOP-THREAD. NEVER USE A K F M DURING A 2-WEEK PERIOD DURING A 2-WEEK PERIOD:
READING THAT IS LESS THAN 5MM.
6 R PER DAY CAN BE TOLERATED 6 R PER DAY CAN SE TOLERATED
FINDING A DOSE RATE: IF BEFORE UP TO TW0 MONTHS WITHOUT FINDING A DOSE RATE IF BEFORE UP TO TWO MONTHS WITHOUT
XPOSURE A KFM READS 17 MM AND LOSING THE ABILITY TO WORK. EXPOSURE A KFM R EADS 17 MM AND LOSING THE ABILITY TO WORK.
IF AFTER A l-MINUTE EXPOSURE IF AFTER A l-MINUTE EXPOSURE
IT READS 5 MM, THE DIFFERENCE 100 R IN A WEEK OR LESS IS NOT IT READS 5 MM, THE DIFFERENCE IN A WEEK OR LESS IS
IN READINGS IS 12 MM, THE AT- LIKELY TO SERIOUSLY SICKEN. IN READINGS IS 12 MM, THE AT- LIKELY TO SERIOUSLY SICKEN.
TACHED TABLE SHOWS THE DOSE TACHED TABLE SHOWS THE DOSE
RATE WAS 9.6 R/HR DURING THE IN A FEW DAYS IS LIKELY RATE WAS 9.6 R/HR DURING THE 350 R IN A FEW DAYS IS LIKELY
EXPOSURE. TO PROVE FATAL UNDER POST- EXPOSURE. TO PROVE FATAL UNDER POST-
FINDING A DOSE: IF A PERSON ATTACK CONDITIONS. ATTACK CONDITIONS.
FINDING A DOSE: IF A PERSON
WORKS OUTSIDE FOR 3 HOURS WORKS OUTSIDE FOR 3 HOURS
WHERE THE DOSE RATE IS 2 R/HR, 600 R IN A WEEK OR LESS IS WHERE THE DOSE RATE IS 2 R/HR, 600 A IN A WEEK OR LESS IS
WHAT IS HIS RADIATION DOSE? CERTAIN TO CAUSE DEATH WHAT IS HIS RADIATION DOSE? CERTAIN TO CAUSE DEATH
ANSWER 3 HR x 2 R/HR = 6 R. WITHIN A FEW WEEKS. ANSWER 3 HR x 2 R/HR = 6 R. WITHIN A FEW WEEKS.
5. With scissors, cut off the “skirt” of the plastic cover until it extends only about
one inch below the top of the rim of the can.
EXACT SIZE
TIE POINT FOR
6. Make a notch in the “skirt,” about one inch wide, where it fits over the pencil
ONE THREAD
SEAT attached to the can. The “skirt” in this notched area should be only BARE-ENDED
WHOSE TWO-
about 5/8 of an inch long, measured down from the top of the rim of the can. USTMENT-THREAD
ENDS ARE THE
7. Remove the plastic cover, and then tape the lower edges of the “skirt,” inside ADJUSTMENT-
and out, using short lengths of l/4-inch-wide tape. Before securing each short THREADS
FINGER HOLD
piece of tape, slightly open the tucks that are being taped shut on their edges,
so that the “skirt” flares slightly outward and the cover can be readily
removed.
TAPE SECUREL
8. Put the plastic cover on the KFM can. From the Pattern Page (B) cut out the
SCALE. Then tape the SCALE to the top of the plastic cover, in the position INSULATION BAND-AID-TAPE
shown on the pattern for the cover, and also by the drawings. Preferably use
transparent tape.
END OF 2-1/2 IN.
Be careful not to cover with tape any of the division lines on the SCALE THREAD
between 20 on the right and 20 on the left of 0. THIS PART
INSULATION
GOES INSIDE STICKY-ENDED ADJUSTMENT-THREAD
9. Make the charging-wire by following the pattern given below which is exactly THE KFM CAN (ACTUAL SIZE)
the right size.

Doorbell wire with an outside diameter of about l/l6 inch is best, but any BARE WIRE
lightweight insulated wire, such as part of a lightweight two-wire extension
cord split in half, will serve. The illustrated wire is much thicker than bell
wire. To stop tape from possibly slipping up or down the wire, use a very little CHARGING-WIRE
glue.
(= STICKY-ENDED ADJUSTMENT-THREAD
If a very thin plastic has been used for the cover, a sticky piece of tape may (OVERSIZED DRAWING)
need to be attached to the end of the bare-ended adjustment thread, SO both
threads can be used to hold the charging wire in a desired position.

The best tape to attach to an end of one of the adjustment-threads is cloth duct
tape. A square piece 3/4 inch by 3/4 inch is the sticky base. To keep this tape
sticky (free of paper fibers), the paper on the can should be covered with
transparent tape or varnish. A piece about l/8 inch by 3/4 inch serves to stick
under one end of the sticky base, to hold the adjustment-thread. A 3/4 inch by
l-1/4 inch rectangular piece of tape is used to make the finger hold --
important for making adjustments inside a dry-bucket.

With a needle or pin, make a hole in the plastic cover l/2 inch from the rim of
the can and directly above the upper end of the CENTER LINE between the
two leaves. The CENTER LINE is marked on the pattern wrapped around the
can. Carefully push the CHARGING-WIRE through this hole (thus stretching
the hole) until all of the CHARGING-WIRE below its Band-Aid-tape stop is
inside the can.
 XIII. Two ways to Charge a K F M d. Fold the square of paper in the
middle, and move the h a r d
1. Charging a KFM with Hard Plastic Rubbed on Dry Paper. plastic rapidly back and forth
so that it is rubbed vigorously
a. Adjust the charging-wire so on the paper in the middle of
that its lower end is about this folded square -- while the
l/16 inch above the upper outside of this folded square of
edges of the aluminum-foil paper is squeezed firmly
leaves. Use the sticky-tape between thumb and the ends
at the end of one adjust- of two fingers.
ment-thread to hold the discharging the charge on the
charging-wire in this plastic to the fingers, keep
position. Stick this tape them away from the edges of
approximately in line with the paper. See photo.
the threads suspending the
leaves, either on the side of e. Move the electrostatically
the can or on top of the charged part of the rubbed
plastic cover. (If the plastic rather slowly past the
charging-wire is held loose- upper end of the charging-
ly by the cover, it may be wire, while looking straight
necessary to put a piece of down on the KFM. Keep the
sticky-tape on the end of each adjustment-thread in order to adjust the hard plastic approximately perpendicular to the charging-wire and about
charging-wire securely. If a charging-wire is not secure, its lower end may 1/4 to 1/2 inch away from its upper end. The charge jumps the spark gaps
be forced up by the like charge on the leaves before the leaves can be fully and charges the leaves of the KFM.
charged.)
f. Pull down on an insulating adjustment-thread to raise the lower end of the
b. Select a piece of Plexiglas, a draftsman’s plastic triangle, a smooth plastic charging-wire. (If the charging-wire has been held in its charging position
ruler, or other piece of hard, smooth plastic. (Unfortunately, not all types by its sticky-ended adjustment-thread being stuck to the top of the clear
of hard plastic can be used to generate a sufficient electrostatic charge.) plastic cover, to avoid possibly damaging the threads: (1) pull down a little
Be sure the plastic is dry. on the bare-ended adjustment-thread; and (2) detach, pull down on, and
secure the sticky-ended adjustment-thread to the side of the can, so as to
For charging a KPM inside a dry-bucket, cut a rectangular piece of hard raise and keep the lower end of the charging-wire close to the underside of
plastic about 1-1/2 by 5 inches. Sharp corners and edges can be smoothed the clear plastic cover.) Do not touch the charging-wire.
by rubbing on concrete. To avoid contaminating the charging end with
sweaty, oily fingers, it is best to mark the other end with a piece of tape. g. Put the charging paper and the hard plastic in a container where they will
be kept dry -- as in a Mason jar with some drying agent.
C. Fold DRY paper (typing paper, writing paper, or other smooth, clean
paper) to make an approximate square about 4 inches on a side and about 2. Charging a KFM from a Quickly Unwound Roll of Tape. (Quick unwinding
20 sheets thick. (This many sheets of paper lessens leakage to the fingers produces a harmless charge of several thousand volts on the tape.)
of the electrostatic charges to be generated on the hard plastic and on the
rubbed paper.) a. Adjust the charging-wire so that its lower end is about inch above the
upper edges of the aluminum-foil leaves. Use the sticky-tape at the end of
one adjustment-thread to hold the charging-wire in this position. Stick this
tape approximately in line with the leaves, either on the side of the can or
on the plastic cover. (If the plastic cover is weak, it may be necessary to
put a piece of sticky-tape on the end of each adjustment-thread, in order to
hold the charging-wire securely. If a charging-wire is not secure, its lower
end may be forced up by the like charge on the leaves before the leaves can
be fully charged.)
b. The sketch shows the “GET e. Pull down on an insulating adjustment-thread to raise the lower end of the
SET” position, preparatory to charging-wire. If the charging-wire has been held in charging position by
unrolling the Scotch Magic its sticky-ended adjustment-thread being stuck to the top of the clear
Transparent Tape, P.V.C. elec- plastic cover, it is best first to
trical tape, or other tape. Be pull down a little on the
sure to first remove the roll from bare-ended adjustment-thread,
its dispenser. Some of the other and then to move, pull down on,
kinds of tape will not produce a and secure the sticky-ended
high enough voltage. adjustment-thread to the side of
the can so that the lower part of
C. QUICKLY unroll 10 to 12 inches the charging-wire is close to the
of tape by pulling its end with underside of the clear plastic
the left hand. while the rieht cover.
hand allows the roll to unwind “GET SET” POSITION TRANSFERRlNG CHARGE
while remaining in about the D O not touch the charging-wire.
same “GET SET” position only
an inch or two away from the f. Rewind the tape tight on its roll, for future use when other tape may not
KFM.
be available.
d. While holding the unwound tape tight, about perpendicular to the
charging-wire, and about l/4 inch away from the end of the charging-wire,
promptly move both hands and the tape to the right rather slowly -- taking
about 2 seconds to move about 8 inches. The electrostatic charge on the
unwound tape “jumps” the spark gaps from the tape to the upper end of
the charging-wire and from the lower end of the charging-wire to the
aluminum leaves, and charges the aluminum leaves.

Be sure neither leaf is touching a stop-thread.

Try to charge the leaves enough to spread them far enough apart to give a
reading of at least 15 mm.
 XIV. Make and Use a Dry-Bucket

By charging a KFM while it is

inside a dry-bucket with a
transparent plastic cover (see
illustration), this fallout meter
can be charged and used even
if the relative humidity is
100% outside the dry-bucket.
The air inside the dry-bucket is
kept very dry by a drying
agent placed on its bottom.
About a cupful of anhydrite
serves very well. The pieces of
this dehydrated gypsum need
not be as uniform in size as is
best for use inside a KFM, but
do not use powdered anhy-
drite.

A dry-bucket can be readily

made in about an hour by
proceeding as follows:

1. Remove the handle of a large bucket, pot, or can preferably with a

top diameter of at least 11 inches. A 4-gallon bucket having a top
diameter of about 14 inches is ideal. If the handle-supports interfere i in.
with stretching a piece of clear plastic film across the top of the in.
bucket, remove them, being sure no sharp points remain.

2. Cut out a circular piece of clear plastic with a diameter about 5 inches A CENTER PIECE ABOUT
larger than the diameter of the top of the bucket. Clear polyethylene in. BY 1 in. IS FIRST
4 mils thick, used for storm windows, etc., is best. Stretch the CUT OUT OF THE CLEAR
plastic smooth across the top of the bucket, and tie it in place, PLASTIC COVER. THEN
CUTS ARE MADE TO
preferably with strong rubber bands looped together to form a circle. PRODUCE FLAPS, INDI
CATED BY THE DOTTED
3. Make a plastic top that fits snugly but is easily removable, by taping
over and around the plastic just below the top of the bucket.
One-inch-wide cloth duct tape, or one-inch-wide glass-reinforced FLAPS BEFORE BEING
TURNED UP TO VERTI
strapping tape, serves well. When taping, do not permit the lower CAL POSlTION
edge of the tape to be pulled inward below the rim of the bucket. TAPING
 4. Cut two small holes (about 1 inch by 2 inches) in the plastic cover, as C. Replacing the plastic cover, that is best held in place with a
illustrated. Then make the radial cuts (shown by dotted lines) loop of rubber bands.
outward from the small holes, out to the solid-line outlines of the 3
inch by 4 inch hand-holes, so as to form small flaps. d. Charging the KFM with your hands inside the plastic bags,
operating the charging device. Have another person
5. Fold the small flaps upward, so they are vertical. Then tape them on illuminate the KFM with a flashlight. When adjusting the
their outer sides, so they form a vertical “wall” about 3/4 inch high charging-wire, move your hands very slowly. See the
around each hand-hole. dry-bucket photos.

6. Reduce the length of two ordinary plastic bread bags (or similar 12. Expose the KFM to fallout radiation either by:
plastic bags) to a length that is 5 inches greater than the height of the
bucket. (Do not use rubber gloves in place of bags; gloves so used a. Leaving the KFM inside the dry-bucket while exposing it to
result in much more humid outside air being unintentionally pumped fallout radiation for one of the listed time intervals, and
into a dry-bucket when it is being used while charging a KFM inside reading the KFM before and after the exposure while it
it.) remains inside the dry-bucket. (The reading eye should be a
measured 12 inches above the SEAT of the KFM, and a
7. Insert a plastic bag into each hand-hole, and fold the edge of the flashlight or other light should be used.)
plastic bag about l/2 inch over the taped vertical “wall” around
each hand-hole. b. Taking the charged KFM out of the dry-bucket to read it,
expose it, and read it after the exposure. (If this is done
8. Strengthen the upper parts of the plastic bags by folding 2-inch repeatedly, especially in a humid shelter, the drying agent
pieces of tape over the top of the “wall” around each hand-hole. will not be effective for many KFM chargings, and will have to
be replaced.)
9. Make about a quart of anhydrite by heating small pieces of
wall-board gypsum, and keep this anhydrite dry in a Mason jar or xv. How to Use a KFM after a Nuclear Attack
other airtight container with a rubber or plastic sealer.
A. Background Information
10. Make a circular aluminum-foil cover to place over the plastic cover
when the dry-bucket is not being used for minutes to hours. Make If during a rapidly worsening crisis threatening nuclear war you are in the
this cover with a diameter about 4 inches greater than the diameter place where you plan to take shelter, postpone studying the instructions
of the top of the bucket, and make it fit more snugly with an following this sentence until after you have:
encircling loop of rubber bands, or with string. Although not
essential, an aluminum-foil cover reduces the amount of water vapor (1) built or improved a high-protection-factor shelter (if
that can reach and pass through the plastic cover, thus extending the possible, a shelter covered with 2 or 3 ft of earth and
life of the drying agent. separate from flammable buildings), and

11. Charge a KFM inside a dry-bucket by: (2) made a KAP (homemade shelter-ventilating pump) if you
have the instructions and materials, and
a. Taking off wrist watch and sharp-pointed rings that might tear
the plastic bags. (3) stored at least 15 gallons of water for each shelter occupant if
you can obtain containers.
b. Placing inside the dry-bucket:
Having a KFM or any other dependable fallout meter and knowing how to
(1) About a cup of anhydrite or silica gel; operate it will enable you to minimize radiation injuries and possible
(2) the KFM, with its charging-wire adjusted in its charging fatalities, especially by skillfully using a high-protection-factor fallout
position; and shelter to control and limit exposures to radiation. By studying this
(3) dry, folded paper and the electrostatic charging device, section you first will learn how to measure radiation dose rates (roentgens
best a 5-inch-long piece of Plexiglas with smoothed per hour = R/hr), how to calculate doses [R] received in different time
edges, to be rubbed between dry paper folded about 4 intervals, and how to determine time intervals (hours and/or minutes) in
inches square and about 20 sheets thick. (Unrolling a roll which specified doses would be received. Then this section lists the sizes
of tape inside a dry-bucket is an impractical charging of doses (number of R) that the average person can tolerate without being
method.) sickened, that he is likely to survive, and that he is likely to be killed by.
Most fortunately for the future of all living things, the decay of 4. Read the KFM after the exposure, while the KFM rests on
radioactivity causes the sandlike fallout particles to become less and less an approximately horizontal surface.
dangerous with the passage of time. Each fallout particle acts much like a
tiny X ray machine would if it were made so that its rays, shooting out 5. Find the time interval that gives a dependable reading -- by
from it like invisible light, became weaker and weaker with time. exposing the fully charged KFM for one or more of the listed
time intervals until the reading after the exposure is:
Contrary to exaggerated accounts of fallout dangers, the radiation dose
rate from fallout particles when they reach the ground in the areas of the (a) Not less than 5 mm.
heaviest fallout will decrease quite rapidly. For example, consider the
decay of fallout from a relatively nearby, large surface burst, at a place (b) At least 2 mm less than the reading before the
exposure.
where the fallout particles are deposited on the ground one hour after the
explosion. At this time one hour after the explosion, assume that the 6. Calculate by simple subtraction the difference in the
radiation dose rate (the best measure of radiation danger at a particular apparent separation of the lower edges of the leaves before
time) measures 2,000 roentgens per hour (2,000 R/hr) outdoors. Seven the exposure and after the exposure. An example: If the
hours later the dose rate is reduced to 200 R/hr by normal radioactive reading before the exposure is 18 mm and the reading after
decay. Two days after the explosion, the dose rate outdoors is reduced by the exposure is 6 mm, the difference in readings is 18mm -
radioactive decay to 20 R/hr. After two weeks, the dose rate is less than 2 6 mm = 12 mm.
R/hr. When the dose rate is 2 R/hr, people can go out of a good shelter
and work outdoors for 3 hours a day, receiving a daily dose of 6 roentgens, 7. If an exposure results in a difference in readings of less than
without being sickened. 2 mm, recharge the KFM and expose it again for one of the
longer time intervals listed. (If there appears to be no
In places where fallout arrives several hours after the explosion, the difference in the readings taken before and after an
radioactivity of the fallout will have gone through its time period of most exposure for one minute, this does not prove there is
rapid decay while the fallout particles were still airborne. If you are in a absolutely no fallout danger.)
location so distant from the explosion that fallout arrives 8 hours after the
explosion, two days must pass before the initial dose rate measured at 8. If an exposure results in the reading after the exposure
your location will decay to 1/10 its initial intensity. being less than 5 mm, recharge the KFM and expose it
again for one of the shorter time intervals listed.
B. Finding the Dose Rate
9. Use the table attached to the
1. Reread Section IV, “What a KFM Is and How It Works. ” KFM to find the dose rate
TABLE USED TO FIND DOSE RATES (R/HR
Also reread Section XIII, “Two Ways to Charge a KFM,” (R/hr) during the time of FROM KFM READINGS

and actually do each step immediately after reading it. exposure. The dose rate *DIFFERENCE BETWEEN THE READlNG BEFORE EXPOSURE
AND THE READING AFTER EXPOSURE (8-PLY STANDARD
(R/hr) i s f o u n d a t t h e FOlL LEA VES)
intersection of the vertical DIFF.*IN TIME INTERVAL OF AN EXPOSURE
2. Charge the KFM, raise the lower end of its charging-wire column of numbers under RINGS E A D - 15 SEC. 1 M I N 4 MIN 16 MIN 1 HR
and read the apparent separation of the lower edges of its the time interval used and of
R/HR R/HR R/HR R/HR R/HR

leaves while the KFM rests on an approximately horizontal the horizontal line of num-
2mm 6.2 1.6 0.4 0.1 0.03
12. 3.1 0.8 0.2 0.06
surface. Never take a reading while a leaf is touching a bers that lists the calculated
4mm
6mm 19. 4.6 1.2 0.3 0.08
stop-thread. difference in readings at its 8 mm 25. 6 . 2 1.6 0.4 0 .10
left end. 10 mm 31. 7.7 2.0 0.5 0.13

3. Expose the KFM to fallout radiation for one of the time 12 mm

An example: If the time 14 mm 4 3 .
37. 9.2
11.
2.3
2.7
0.6
0.7
0.15
0.18
intervals shown in the vertical columns of the table attached interval of the exposure was
to the KFM. (Study the following table.) If the dose rate is 1 MIN. and the difference in
not known even approximately, first expose the fully readings was 12 mm, the
charged KFM for one minute. For dependable the table shows that the dose rate during the time interval of
measurements outdoors, expose the charged KFM about the exposure was 9.2 R/HR (9.2 roentgens per hour).
three feet above the ground. For most exposures, connect
the KFM to a stick or pole (best done with two rubber Another example: If the time interval of the exposure was
bands), and expose it about three feet above the ground. Be 15 SEC. and the difference in readings was 11 mm, the table
careful not to tilt the KFM too much. shows that the dose rate during the exposure was halfway
between 31 R/HR and 37 R/HR that is, the dose rate
was 34 R/hr.
 10. Note in the table that if an exposure for one of the listed time Another example: Assume that three days after an attack the occupants
intervals causes the difference in readings to be 2 mm or 3 of a dry, hot cave giving almost complete protection against fallout are in
mm, then an exposure 4 times as long reveals the same dose desperate need of water. The dose rate outside is found to be 20 R/hr. To
rate. An example: If a l - min exposure results in a backpack water from a source 3 miles away is estimated to take 2-1/2
difference in readings of 2 mm, the table shows the dose rate hours. The cave occupants estimate that the water backpackers will
was 1.6 R/hr; then if the KFM is exposed for 4 minutes at receive a dose in 2-1/2 hours of 50 R (2.5 hr x 20 R/hr = 50 R). A dose of
this same dose rate of 1.6 R/hr, the table shows that the 50 R will cause only mild symptoms (nausea in about 10% of persons
resultant difference in readings is 8 mm. receiving a 50 R dose) for persons who previously have received only very
small doses. Therefore, one of the cave occupants makes a rapid radiation
The longer exposure results in a more accurate survey for about 1-1/2 miles along the proposed route, stopping to charge
determination of the dose rate. and read a KFM about every quarter of a mile. He finds no dose rates
much higher than 20 R/hr.
,
11. If the dose rate is found to be greater than 0.2 R/hr and time
is available, recharge the KFM and repeat the dose-rate So, the cave occupants decide the risk is small enough to justify some of
measurement -- to avoid possible mistakes. them leaving shelter for about 2-1/2 hours to get water.

C. Calculating the Dose Received D. Estimating the Dangers from Different Radiation Doses

The dose of fallout radiation -- that is, the amount of fallout radiation Fortunately, the human body -- if given enough time -- can repair most of
received -- determines the harmful effects on men and animals. Being the damage caused by radiation. An historic example: A healthy man
exposed to a high dose rate is not always dangerous -- provided the accidently received a daily dose of 9.3 R (or somewhat more) of
exposure is short enough to result in only a small dose being received. For fallout-type radiation each day for a period of 106 days. His total
example, if the dose rate outside an excellent fallout shelter is 1200 R/hr accumulated dose was at least 1000 R. A dose of one thousand roentgens, 3
and a shelter occupant goes outside for 30 seconds, he would be exposed if received in a few days, is almost three times the dose likely to kill the
for 1/2 of 1 minute, or 1/2 of 1/60 of an hour, which equals 1/120 hour. average man if he receives the whole dose in a few days and after a
Therefore, since the dose he would receive if he stayed outside for 1 hour nuclear attack cannot get medical treatment, adequate rest, etc.
would be 1200 R, in 30 seconds he would receive l/l20 of 1200, which However, the only symptom this man noted was serious fatigue.
equals 10 R (1200 R divided by 120 = 10 R). A total daily dose of 10 R (10
roentgens) will not cause any symptoms if it is not repeated day after day The occupants of a high-protection-factor shelter (such as a trench shelter
for a week or more. covered with 2 or 3 feet of earth and having crawlway entrances) would
receive less than 1/200 of the radiation dose they would receive outside.
In contrast, if the average dose rate of an area were found to be 12 R/hr Even in most areas of very heavy fallout, persons who remain continously
and if a person remained exposed in that particular area for 24 hours, he in such a shelter would receive a total accumulated dose of less than 25 R
would receive a dose of 288 R (12 R/hr x 24 hr = 288 R). Even assuming in the first day after the attack, and less than 100 R in the first two weeks.
that this person had been exposed previously to very little radiation, there At the end of the first two weeks, such shelter occupants could start
would still be a serious risk that this 288 R dose would be fatal under the working outside for an increasing length of time each day, receiving a
difficult conditions that would follow a heavy nuclear attack. daily dose of no more than 6 R for up to two months without being
sickened.
To control radiation exposure in this way, each shelter must have a fallout E. Using a KFM to Reduce the Doses Received Inside a Shelter
meter, and a daily record must be kept of the approximate total dose
received each day by every shelter occupant, both while inside and outside Inside most shelters, the dose received by an occupant varies
the shelter. The long-term penalty which would result from a dose of 100 considerably, depending on the occupant’s location. For example, inside
R received within a few weeks is much less than many Americans fear. If an expedient covered-trench shelter the dose rate is higher near the
100 average persons received an external dose of 100 R during and shortly entrance than in the middle of the trench. In a typical basement shelter
after a nuclear attack, the studies of the Japanese A-bomb survivors the best protection is found in one corner. Especially during the first
indicate that no more than one of them is likely to die during the following several hours after the arrival of fallout, when the dose rates and doses
30 years as a result of this 100 R radiation dose. These delayed radiation received are highest, shelter occupants should use their fallout meters to
deaths would be due to leukemia and other cancers. In the desperate determine where to place themselves to minimize the doses they receive.
crisis period following a major nuclear attack, such a relatively small They should use available tools and materials to reduce the doses they
shortening of life expectancy during the following 30 years should not receive, especially during the first day, by digging deeper (if practical1
keep people from starting recovery work to save themselves and their and reducing the size of openings by partially blocking them with earth,
fellow citizens from death due to lack of food and other essentials. water containers, etc. -- while maintaining adequate ventilation. To
greatly reduce the danger from fallout particles entering the body through
A healthy person who previously has received a total accumulated dose of nose or mouth, shelter occupants should at least cover their nose and
no more than 100 R distributed over a 2-week period should realize that: mouth with a towel or other cloth while the fallout is being deposited
outside their shelter.
100 R, even if all received in a day or less, is unlikely to require
medical care--provided during the next 2 weeks a total additional The air inside an occupied shelter often becomes very humid. If a good
dose of no more than a few R is received. flow of outdoor air is flowing into a shelter -- especially if pumped by
briefly operating a KAP or other ventilating pump -- a KFM usually can be
350 R received in a few days or less is likely to prove fatal after a large charged at the air intake of the shelter room without putting it inside a
nuclear attack when few survivors could get medical care, sanitary dry-bucket. However, if the air to which a KFM is exposed has a relative
surroundings, a well-balanced diet, or adequate rest. humidity of 90% or higher, the instrument cannot be charged, even by
quickly unrolling a roll of tape.
600 R received in a few days or less is almost certain to cause death
within a few days. In extensive areas of heavy fallout, the occupants of most home
basements, that provide inadequate shielding against heavy fallout
radiation, would be in deadly danger. By using a dependable fallout
meter, occupants would find that persons lying on the floor in certain
locations would receive the smallest doses, and that, if they improvise
additional shielding in these locations, the doses received could be greatly
reduced. Additional shielding can be provided by placing a double layer
of doors, positioned about two feet above the floor and strongly supported
near their ends, and by putting books, containers full of water and other
heavy objects on top of these doors. Or, if tools are available, breaking
through the basement floor and digging a shelter trench will greatly
increase available protection against radiation. If a second expedient
ventilating pump, a KAP, is made and used as a fan, such an extremely
cramped shelter inside a shelter usually can be occupied by several times
as many persons.

END OF INSTRUCTIONS