A wipe test counter is a device used to measure for possible radioactive contamination in a variety of environments. When using radioactive materials it is necessary to test for accidental contamination, whether from use of liquid unsealed sources or to check for leaking sealed sources. A swab or small absorbent smear can be used to “wipe” an area, the wipe is then placed into a test tube and counted, typically using a gamma counter. Testing for leaks in this manner is a method described in the ISO 9978 standard.

Equipment

Survey instruments may be used to detect surface contamination without requiring wiping, however this requires careful calibration and technique to ensure adequate sensitivity is achieved. A gamma counter is a typical choice for measuring wipe samples for radioactivity as it allows multiple tests to be counted in a largely automated way. These systems detect radiation using a

scintillator A scintillator is a material that exhibits scintillation, the property of luminescence, when excited by ionizing radiation. Luminescent materials, when struck by an incoming particle, absorb its energy and scintillate (i.e. re-emit the absorbed ...

and

photomultiplier tube Photomultiplier tubes (photomultipliers or PMTs for short) are extremely sensitive detectors of light in the ultraviolet, visible, and near-infrared ranges of the electromagnetic spectrum. They are members of the class of vacuum tubes, more specif ...

and may allow the energy spectrum of a sample to be recorded, which can be used to identify the contaminant. Use of a gamma camera has also been proposed, where collimators are removed to improve sensitivity.

Regulation

Wipe testing is typically a requirement of licenses to hold radioactive materials. In the United States the

Nuclear Regulatory Commission The Nuclear Regulatory Commission (NRC) is an independent agency of the United States government tasked with protecting public health and safety related to nuclear energy. Established by the Energy Reorganization Act of 1974, the NRC began operat ...

requires wipe testing of sealed sources "periodically" using equipment sensitive down to 185

Becquerels The becquerel (; symbol: Bq) is the unit of radioactivity in the International System of Units (SI). One becquerel is defined as the activity of a quantity of radioactive material in which one nucleus decays per second. For applications relat ...

. In the United Kingdom the

Health and Safety Executive The Health and Safety Executive (HSE) is a UK government agency responsible for the encouragement, regulation and enforcement of workplace health, safety and welfare, and for research into occupational risks in Great Britain. It is a non-depar ...

guidance for the

Ionising Radiations Regulations 1999 The Ionising Radiations Regulations (IRR) are statutory instruments which form the main legal requirements for the use and control of ionising radiation in the United Kingdom. There have been several versions of the regulations, the current legisla ...

requires wipe testing (usually every two years) and it is also likely to be a requirement of

Environment Agency The Environment Agency (EA) is a non-departmental public body, established in 1996 and sponsored by the United Kingdom government's Department for Environment, Food and Rural Affairs, with responsibilities relating to the protection and enha ...

permits. In

Australia Australia, officially the Commonwealth of Australia, is a Sovereign state, sovereign country comprising the mainland of the Australia (continent), Australian continent, the island of Tasmania, and numerous List of islands of Australia, sma ...

licence conditions may require adherence to Australian standard AS2243.4 and ISO 9978 for wipe testing of sealed sources.

References

{{DEFAULTSORT:Wipe Test Counter Radiation health effects Particle detectors