IEC 60860-2014 pdf – Radiation protection instrumentation – Warning equipment for criticality accidents.
1 Scope and object This International Standard applies to equipment intended to provide warning of a criticality accident by the detection of gamma radiation, neutrons or both from such an event. This standard is primarily intended to apply to equipment design and, therefore, does not address the need for placement of such equipment. The need for criticality alarm systems and the utilisation procedures are described in ISO 7753 and ISO 1 1 320. The primary purpose of the criticality alarm system is to detect radiation from criticality accidents and warn personnel. Suitable alarms shall be provided so that personnel present in the area involved and in adjacent effected areas (often the complete facility) can be warned in the event of a criticality accident occurring. These alarms are intended to activate an evacuation alarm to reduce the probability of serious exposure to personnel. Such systems may also have secondary functions, such as providing a follow-up measurement of the radiation level during the accident. The systems should only be used for these secondary functions, provided that the secondary functions have no adverse effect on the criticality alarms and their essential characteristics (for example, reliability) described in this standard. The object of this standard is to prescribe general, radiation detection, environmental, mechanical, electromagnetic and documentation requirements and to specify acceptance criteria for criticality accident warning equipment. This standard is not applicable to photon or neutron dose equivalent (rate) meters or monitors covered by IEC 60532, IEC 60846 (all parts), IEC 61 01 7 (all parts), and IEC 61 005. This standard is not applicable either to equipment or assemblies used in control and safety systems of nuclear reactors.
2 Normative references The following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. IEC 60050 (all parts): International Electrotechnical Vocabulary (available at http://www.electropedia.org) IEC 61 508 (all parts), Functional safety of electrical/electronic/programmable electronic safety-related systems IEC 62706, Radiation protection instrumentation – Environmental, electromagnetic and mechanical performance requirements ISO 7753:1 987, Nuclear energy – Performance and testing requirements for criticality detection and alarm systems
3 Terms and definitions, quantities and units 3.1 Terms and definitions For the purposes of this document, the following terms and definitions, as well as those given in IEC 60050-395 apply. 3.1 .1 acceptance test contractual test to prove to the customer that the device fulfils certain specifications 3.1 .2 alarm method for notification of a criticality accident 3.1 .3 alarm set point minimum radiation dose and/or dose rate that will activate the alarm 3.1 .4 conventional quantity value (dose) quantity value attributed by agreement to a quantity for a given purpose Note 1 to entry: The term “conventional true quantity value” is sometimes used for this concept, but its use is discouraged. Note 2 to entry: Sometimes a conventional quantity value is an estimate of a true quantity value. Note 3 to entry: A conventional quantity value is generally accepted as being associated with a suitably small measurement uncertainty, which might be zero. Note 4 to entry: In this standard the quantity is the dose. [SOURCE: VIM:2007, 2.1 2] 3.1 .5 criticality accident release of energy as a result of an accidentally produced self-sustained or divergent neutron chain reaction 3.1 .6 criticality alarm system all parts of the assembly, subassemblies, functional units and components that together make a workable system, including all circuitry, alarms, connections, cables, detectors, and auxiliary subassemblies. The criticality alarm system comprises at least the following subassemblies: – detection subassembly, including associated electronics; – warning subassembly including the logic unit and alarm unit