Document: NUREG-0800
Document ID: 106978f1-fb10-4fa9-ad95-601f3c16bd36
Document Type: srp
Title: Revision 5 - March 2007
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0705/ML070550072.pdf
Revision Date: 2023-06
Chapter: 7
Section ID: 7
CFR Part: 
CFR Title: 

Content:
4 of the NRC position on D3 should be sufficient both for monitoring the plant state and to enable control room operators to actuate the systems that will place the plant in a hot shutdown condition. In addition, the displays and controls should be sufficient for the operator to monitor and control the following critical safety functions: reactivity level, core heat removal, reactor coolant inventory, containment isolation, and containment integrity. This additional manual capability is necessary in new reactors because all of the protection and control systems are digital-computer-based and thus vulnerable to common-cause failure. These displays and controls provide plant operators with information and control capabilities that are not subject to common-cause failures due to software errors in the plant's automatic digital I&C safety system because they are independent and diverse from that system. The point at which the manual controls are connected to safety equipment should be downstream of the plant's digital I&C safety system outputs. These connections should not compromise the integrity of interconnecting cables and interfaces between local electrical or electronic cabinets and the plant's electromechanical equipment. To achieve system-level actuation at the lowest possible level in the safety system architecture, the controls may be connected either to discrete hardwired components or to simple (e.g., component function can be completely demonstrated by test), dedicated, and diverse, software-based digital equipment that performs the coordinated actuation logic. The displays may include digital components that are dedicated exclusively to the display function. Functional characteristics (e.g., range, accuracy, time response) should be sufficient to provide operators with the information needed to place and maintain the plant in a hot shutdown condition. Human factors engineering principles and criteria should be applied to the selection and design of the