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C.1 Introduction

This appendix provides information on various field and laboratory equipment used to measure radiation levels and radioactive material concentrations. The descriptions provide general guidance, and those interested in purchasing or using the equipment are encouraged to contact vendors and users of the equipment for specific information and recommendations. Although most of this equipment is in common use, a few specialty items are included to demonstrate promising developments.

The equipment is divided into two broad groupings of field survey and laboratory instruments, and each group is subdivided into equipment that measures alpha, beta, gamma, X-rays, neutron and radon. A single sheet provides information for each system and includes its type of use (field or lab), the primary and secondary radiation detected, applicability for site surveys, operation, specificity/sensitivity, and cost of the equipment and surveys performed.

The sheet contains the following sections:

  • Applicability for site surveys. In this section it is discussed how the equipment is most useful for performing site radiological surveys.
  • Operation. Herein basic technical information is provided on what the system includes, how it works, how to use it practically in the field, and its features.
  • Specificity/Sensitivity. This section addresses the system’s strengths and weaknesses, and the levels of radioactivity it can measure.
  • Cost. The information obtained in this section has been obtained primarily from discussions with manufacturers, users, and reviews of product literature. The cost per measurement is an estimate of the cost of producing and documenting a single data point, generally as part of a multipoint survey. It assumes times for instrument calibration (primarily if conducted at the time of the survey), use, sample analysis, and report preparation and review. It should be recognized that these values will change over time due to factors like inflation and market expansion.

It is assumed that the user of this Appendix has a basic familiarity with field and laboratory equipment. Some of the typical instrument features and terms are listed below and may not be described separately for the individual instruments:

  • Field survey equipment consists of a detector, a survey meter, and interconnected cables, although these are sometimes packaged in a single container.
  • The detector or probe is the portion which is sensitive to radiation. It is designed in such a manner, made of selected materials, and operated at a high voltage that makes it sensitive to one or more types of radiation. Some detectors feature a window or a shield whose construction material and thickness make the detector more or less sensitive to a particular radiation. The size of the detector can vary depending on the specific need, but is often limited by the characteristics of the construction materials and the physics of the detection process.
  • The survey meter contains the electronics and provides high voltage to the detector, processes the detector’s signal, and displays the readings in analog or digital fashion. An analog survey meter has a continuous swing needle and typically a manually operated scale switch, used to keep the needle on scale. The scaling switch may not be required on a digital survey meter.
  • The interconnecting cables serve to transfer the high voltage and detector signals in the proper direction. These cables may be inside those units which combine the meter and detector into a single box, but they are often external with connectors that allow the user to interchange detectors.
  • Scanning and measuring surveys. In a scanning survey, the field survey meter is operated while moving the detector over an area to search for a change in readings. Since the meter’s audible signal responds faster than the meter display, listening to the built-in speaker or using headphones allows the user to more quickly discern changes in radiation level. When a scanning survey detects a change, the meter can be held in place for a more accurate static measurement.
  • Integrated readings. Where additional sensitivity is desired, the reading can be integrated using internal electronics or an external scaler to give total values over time. The degree to which the sensitivity can be improved depends largely on the integration time selected.
  • Units of measure. Survey meters with conventional meter faces measure radiation levels in units of counts, microRoentgen (μR), millirad (mrad), or millirem (mrem) in terms of unit time, e.g., cpm or μR/hr. Those with SI meter faces use units of microSievert (μSv) or milliGray per unit time, e.g., μSv/hr or mGy/hr.