NUREG-1537, Part 2 - NRC

CHAFIE 7
* The sensitivity of each sensor channel should be commensurate with the )
precision and accuracy to which knowledge of the variable measured is
required for the protective function.
The automatic reactor runback or shutdown (scram) subsystem should be
fail-safe against malfunction and electrical power failure should be as close
to passive as can be reasonably achieved, should go to completion once
initiated, and should go to completion within the time scale derived from
applicable analyses in the SAR.
* The RPS should be designed for reliable operation in the normal range of
environmental conditions anticipated within the facility.
* The scram operator should be able to operate the system by means of
readily available switches, or by interlock activation.
* The scram system should be designed to annunciate the channel initiating
the action, and to require resetting to resume operation.
* The scram system should be designed to maintain reactor shutdown
without operator action to at least the shutdown margin as defined in
Chapter 4 and the technical specifications.
* The RPS function and time scale should be readily tested to ensure
operability of at least minimum protection for all reactor operations.
* Information about the RPS detector or sensor devices should be sufficient
to verify that individual safety limits are protected by independent channels,
and that LSSS and LCO settings can be established through analyses and
verified experimentally.
* Hardware and software for computerized systems should meet the
guidelines of 7-4.3.2-1993 and RG 1.152, Revision 1, and software
should meet the guidelines of ANSVANS 10.41987 applicable to nonpower
reactor systems. ANSI/ANS 15.15-1978 and draft ANSIANS
15.20 are useful as general guides for the design, implementation, and
evaluation of I&C systems for non-power reactors and should be used
where applicable.
* Consult NRC Generic Letter 95-02 for I&C systems that are being
upgraded to systems based on digital technology.
NUREG-1537.PART2 7-12 REV 0,2/96
NUREG-1537,PART2 7-12 REV 0, 2/9
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