A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

M

maintenance:
The organized activity, both administrative and technical, of keeping structures, systems and components in good operating condition, including both preventive and corrective (or repair) aspects.

• corrective maintenance: Actions that restore, by repair, overhaul or replacement, the capability of a failed structure, system or component to function within acceptance criteria.
  Contrasted with preventive maintenance.
• periodic maintenance: Form of preventive maintenance consisting of servicing, parts replacement, surveillance or testing at predetermined intervals of calendar time, operating time or number of cycles.
  Also known as time-based maintenance.
• planned maintenance: Form of preventive maintenance consisting of refurbishment or replacement that is scheduled and performed prior to unacceptable degradation of a structure, system or component.
• predictive maintenance: Form of preventive maintenance performed continuously or at intervals governed by observed condition to monitor, diagnose or trend a structure, system or component’s condition indicators; results indicate current and future functional ability or the nature of and schedule for planned maintenance.
  Also known as condition-based maintenance.
• preventive maintenance: Actions that detect, preclude or mitigate degradation of a functional structure, system or component to sustain or extend its useful life by controlling degradation and failures to an acceptable level.
  Preventive maintenance may be periodic maintenance, planned maintenance or predictive maintenance.

medical practitioner:
An individual who: (a) has been accredited through appropriate national procedures as a health professional; (b) fulfils the national requirements on training and experience for prescribing procedures involving medical exposure; and (c) is a registrant or a licensee, or a worker who has been designated by a registered or licensed employer for the purpose of prescribing procedures involving medical exposure. [40]

member of the public:
In a general sense, any individual in the population except, for protection and safety purposes, when subject to occupational or medical exposure.  For the purpose of verifying compliance with the annual dose limit for public exposure, the representative individual in the relevant critical group.

migration:
The movement of radionuclides in the environment as a result of natural processes.
Most commonly, movement of radionuclides in association with groundwater flow.

mill tailings:
The residues resulting from processing ore to extract uranium series or thorium series radionuclides, or similar residues from processing ores for other purposes.

minimization, waste:
The process of reducing the amount and activity of radioactive waste to a level as low as reasonably achievable, at all stages from the design of a facility or activity to decommissioning, by reducing waste generation and by means such as recycling and reuse, and treatment, with due consideration for secondary as well as primary waste.

mining and milling:
Mining in a mine that yields ore containing uranium series or thorium series radionuclides either in sufficient amounts or concentrations to warrant exploitation or, when present in conjunction with other substances being mined, in amounts or concentrations that require radiation protection measures to be taken; and processing of radioactive ores from such mines to produce a chemical concentrate.
This definition includes those mining and milling operations aimed at extracting uranium series or thorium series radionuclides and those aimed at extracting other substances from ores which represent a significant radiological hazard.

model:
An analytical representation or quantification of a real system and the ways in which phenomena occur within that system, used to predict or assess the behaviour of the real system under specified (often hypothetical) conditions.

• computational model: A calculational tool that implements a mathematical model.
• conceptual model: A set of qualitative assumptions used to describe a system (or part thereof).
  These assumptions would normally cover, as a minimum, the geometry and dimensionality of the system, initial and boundary conditions, time dependence, and the nature of the relevant physical, chemical and biological processes and phenomena.
• mathematical model: A set of mathematical equations designed to represent a conceptual model.

monitoring:
1.   The measurement of dose or contamination for reasons related to the assessment or control of exposure to radiation or radioactive substances, and the interpretation of the results. [40]
Measurement is used somewhat loosely here.  The ‘measurement’ of dose often means the measurement of a dose equivalent quantity as a proxy for a dose quantity that cannot be measured directly.  Also, sampling may be involved as a preliminary step to measurement.
Monitoring may be subdivided in two different ways: according to where the measurements are made, into individual monitoring, workplace monitoring, source monitoring and environmental monitoring; and, according to the purpose of the monitoring, into routine monitoring, task related monitoring and special monitoring.

• area monitoring: A form of workplace monitoring in which an area is monitored by taking measurements at different points in the area.
  As opposed to measurements by a static monitor.
• environmental monitoring: The measurement of external dose rates due to sources in the environment or of radionuclide concentrations in environmental media.
  Contrasted with source monitoring.
• individual monitoring: Monitoring using measurements by equipment worn by individual workers, or measurements of quantities of radioactive materials in or on their bodies.
  Also called personal monitoring.  Usually contrasted with workplace monitoring.
• personal monitoring: Synonymous with individual monitoring.
• personnel monitoring: The overall effect of a combination of individual monitoring and workplace monitoring.
• routine monitoring: Monitoring associated with continuing operations and intended: (1) to demonstrate that working conditions, including the levels of individual dose, remain satisfactory; and (2) to meet regulatory requirements.
  Routine monitoring can be individual monitoring or workplace monitoring.
  Contrasting terms: task related monitoring and special monitoring.
• source monitoring: The measurement of activity in radioactive materials being released into the environment or of external dose rates due to sources within a facility or activity.
  Contrasted with environmental monitoring.
• special monitoring: Monitoring designed to investigate a specific situation in the workplace for which insufficient information is available to demonstrate adequate control, by providing detailed information to elucidate any problems and to define future procedures.
  Special monitoring would normally be undertaken at the commissioning stage of new facilities, following major modifications either to facilities or procedures, or when operations are being carried out under abnormal circumstances, such as an accident.
  Special monitoring can be individual monitoring or workplace monitoring.
  Contrasting terms: routine monitoring and task related monitoring.
• task related monitoring: Monitoring related to a specific operation, to provide data to support the immediate decisions on the management of the operation.
  Task related monitoring can be individual monitoring or workplace monitoring.
  Contrasting terms: routine monitoring and special monitoring.
• workplace monitoring: Monitoring using measurements made in the working environment.
  Usually contrasted with individual monitoring.

2.   Continuous or periodic measurement of radiological or other parameters or determination of the status of a system.  Sampling may be involved as a preliminary step to measurement.
Although the concept is not fundamentally different from (1), this definition is more suited to the types of monitoring concerned primarily with safety (i.e. keeping sources under control) rather than with protection (i.e. controlling exposure).  This definition is particularly relevant to monitoring of the status of a nuclear installation by tracking plant variables, or monitoring the long term performance of a waste repository by tracking variables such as water fluxes.  These examples differ from definition (1) in that the routine measurements are themselves of no particular interest; the monitoring is only to detect unexpected deviations if they occur.

• condition monitoring: Observation, measurement or trending of condition indicators with respect to some independent parameter (usually time or cycles) to indicate the current and future ability of a structure, system or component to function within acceptance criteria.