The Kearny fallout meter, or KFM, is an expedient radiation meter. It is designed such that someone with a normal mechanical ability would be able to construct it before or during a nuclear attack, using common household items. The Kearny fallout meter was developed by

Cresson Kearny Cresson Henry Kearny (; – ) wrote several survival-related books based primarily on research performed at Oak Ridge National Laboratory. Career Kearny attended Texas Military Institute in the 1930s, where he became the commanding officer of the ...

from research performed at

Oak Ridge National Laboratory Oak Ridge National Laboratory (ORNL) is a U.S. multiprogram science and technology national laboratory sponsored by the U.S. Department of Energy (DOE) and administered, managed, and operated by UT–Battelle as a federally funded research and ...

and published in the

civil defense Civil defense ( en, region=gb, civil defence) or civil protection is an effort to protect the citizens of a state (generally non-combatants) from man-made and natural disasters. It uses the principles of emergency operations: prevention, miti ...

manual ''

Nuclear War Survival Skills ''Nuclear War Survival Skills'' or NWSS, by Cresson Kearny, is a civil defense manual. It contains information gleaned from research performed at Oak Ridge National Laboratory during the Cold War, as well as from Kearny's extensive jungle liv ...

'' (). The plans were originally released in Oak Ridge National Laboratory publication ORNL-5040, ''The KFM, A Homemade Yet Accurate and Dependable Fallout Meter'' and have been formatted in a newsprint-ready layout so that they may be quickly printed with accurate dimensions in local newspapers. It must be built from a correctly scaled copy of the plans; photocopies and printouts of digital copies may not be to scale.

History

Devised in 1978 by Cresson Kearny, the Kearny fallout meter is an application of the

gold-leaf electroscope The electroscope is an early scientific instrument used to detect the presence of electric charge on a body. It detects charge by the movement of a test object due to the Coulomb electrostatic force on it. The amount of charge on an object is ...

developed in 1787 by Abraham Bennet. Prior to this, the use of the

electrometer An electrometer is an electrical instrument for measuring electric charge or electrical potential difference. There are many different types, ranging from historical handmade mechanical instruments to high-precision electronic devices. Modern ...

principle for radiation detection had seen widespread application in the form of the

quartz fiber dosimeter A quartz fiber dosimeter, sometimes called a self indicating pocket dosimeter (SIPD) or self reading pocket dosimeter (SRPD) or quartz fibre electrometer (QFE), is a type of radiation dosimeter, a pen-like device that measures the cumulativ ...

. Professional radiation meters, while more accurate and more durable, had a number of potential issues, including cost and lack of availability, which it was hoped the Kearny fallout meter would address.

Use

Commercially made radiation meters are typically based on electronic circuitry or require a battery-powered charging apparatus, allowing susceptibility to battery shortages and to

electromagnetic pulse An electromagnetic pulse (EMP), also a transient electromagnetic disturbance (TED), is a brief burst of electromagnetic energy. Depending upon the source, the origin of an EMP can be natural or artificial, and can occur as an electromagnetic fie ...

. The Kearny fallout meter was designed to utilize static electricity, produced by (for example) a hard plastic rubbed on dry paper. The KFM was also designed to be less expensive to build than the purchase price of dosimeters and to be made out of commonly available materials, such that they could be constructed even after a disaster. Most commercial radiation meters also require initial and periodic professional calibration, but "... if a KFM is made and maintained with the specified dimensions and of the specified materials, its accuracy is automatically and permanently established by unchanging laws of nature". The designed operating range is from 30 m R/h to 43 R/h, with accuracy of ±25%. "A KFM looks like a toy" has been cited as a "major disadvantage" of the design. Yet another disadvantage is the method of operation, the meter does not provide the measurement on charging, but the charging cause two aluminium leaves to repel. The angle between the leaves is measured, and then the user measures the rate in which the leaves close.

How it works

An electrostatic charge is placed upon two aluminium foil leaves, causing them to repel. As radiation strikes the meter, the foil leaves lose their charge and start to droop. This droop can be measured, and its rate can be established. The KFM has been used as a science project, demonstrating the effects of

ionizing radiation Ionizing radiation (or ionising radiation), including nuclear radiation, consists of subatomic particles or electromagnetic waves that have sufficient energy to ionize atoms or molecules by detaching electrons from them. Some particles can travel ...

. The dimensions of a KFM and the weight of its leaves permanently establish its calibration, when built as specified with a properly sized scale.

References

External links

Plans

* ''

'' Appendix C by Cresson Kearny {{ISBN, 0-942487-01-X
Full Report: The KFM, A Homemade Yet Accurate and Dependable Fallout Meter

PDF version of the plans

Nuclear War Survival Skills

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Cold War Nuclear warfare Civil defense Disaster preparedness Improvisation Ionising radiation detectors 1978 introductions 1978 in science Science and technology in the United States