ANSI N42.18-2004 pdf download Specification and Performance of On-Site Instrumentation for Continuously Monitoring Radioactivity in Effluents
1. Introduction
The release of radioactivity from nuclear facilities to the environment generally is monitored by installed instrumentation. The objective of such instrumentation is to measure the quantity or rate, or both, of release of radionuclides in the effluent streams and to provide documentation useful for scientific and legal purposes. This standard applies to continuous monitors that measure normal releases, detect inadvertent releases, show general trends, and annunciate radiation levels that have exceeded predetermined values.
2. Scope
This standard provides recommendations for the selection of instrumentation specific to the continuous monitoring and quantification of radioactivity in effluents released to the environment. The effluent streams considered may contain radioactive gases, liquids, particulates, or dissolved solids singly or in combination. This standard specifies detection capabilities, physical and operating limits, reliability, and calibration requirements and sets forth minimum performance requirements for effluent monitoring instrumentation. Unless otherwise specified, the criteria herein refer to the total system. This standard applies only to monitoring during routine operation that includes abnormal releases. Emergency situations, where additional performance capability will be required, are a matter of separate consideration. Also outside the scope of this standard are sample extraction and laboratory analyses, normally used for intercomparison between monitor calibrations and laboratory analyses, and other applications for continuous monitoring instrumentation such as environmental monitoring or process control. Sampling techniques are covered in ANSI N13.1-1969, Guide to Sampling Airborne Radioactive Materials in Nuclear Facilities.
3. Definitions
These definitions are restricted to the purpose of this standard.
accuracy: The degree of agreement with the true value of the quantity being measured.
NOTE — Accuracy is subject to the influence of unknown systematic errors.
authorities: Any governmental agencies or recognized scientific bodies which by their charter define regulations or standards dealing with radiation protection.
calibrate: Adjustmentsystem and the determination of system accuracy using one or more sources traceable to the NBS (National Bureau of Standards).
check: The use of a source to determine if the detector and all electronic components of the system are operating correctly.
detector: Any device for converting radiation flux to a signal suitable for observation and measurement.
effluent: The liquid or gaseous waste streams released to the environment.
extracameral effect: Apparent response of an instrument caused by radiation on any other portion of the system than the detector.
in line: A system where the detector assembly is adjacent to or immersed in the total effluent stream.
off line: A system where an aliquot is withdrawn from the effluent stream and conveyed to the detector assembly.
on site: Location within a facility that is controlled with respect to access by the general public.