Preface
This is the second edition of CSA N290.4, Requirements for reactor control systems of nuclear power plants. It supersedes the previous edition published in 1982. The title has been changed to reflect a change of scope. The new edition not only addresses CANDU reactors but also addresses other types of water-cooled power reactors.
Scope
1.1
This Standard specifies provisions for safe and effective control of reactor power.
1.2
This Standard pertains to all components of the system, including mechanical, process, software, electrical, and instrumentation and control design used for the control of the neutron flux and the thermal output of the reactor.
1.3
In this Standard, control refers to both manual and automatic action.
1.4
In this Standard, control refers to reactor power control, not overall unit control.
1.5
This Standard provides provisions for a design that facilitates reactivity management.
Note: For the purposes of this Standard, reactivity management refers to
(a) the safe, controlled, and conservative performance of plant operation and maintenance activities that affect reactivity;
(b) the active and vigilant monitoring of reactivity changes;
(c) the quick and reliable detection of deviations from expected results; and
(d) limiting rate changes and maximum power changes in response to failures.
1.6
In CSA standards, shall is used to express a requirement, i.e., a provision that the user is obliged to satisfy in order to comply with the standard; should is used to express a recommendation or that which is advised but not required; and may is used to express an option or that which is permissible within the limits of the standard.
Notes accompanying clauses do not include requirements or alternative requirements; the purpose of a note accompanying a clause is to separate from the text explanatory or informative material.
Notes to tables and figures are considered part of the table or figure and may be written as requirements.
Annexes are designated normative (mandatory) or informative (nonmandatory) to define their application.
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