Document: NUREG-0800
Document ID: 67fa6795-0863-41e9-b45d-53138007a192
Document Type: srp
Title: Revision 6 – August 2016
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML1601/ML16019A358.pdf
Revision Date: 2023-06
Chapter: 7
Section ID: 7
CFR Part: 
CFR Title: 

Content:
he Institute of Electrical & Electronics Engineers (IEEE) Standard (Std) 603-1991, “IEEE Standard Criteria for Safety Systems for Nuclear Power Generating Stations,” and the correction sheet dated January 30, 1995. For nuclear power plants with construction permits issued before January 1, 1971, the applicant or licensee may elect to comply instead with their plant specific licensing basis. For nuclear power plants with construction permits issued between January 1, 1971, and May 13, 1999, the applicant or licensee may elect to comply instead with the requirements stated in IEEE Std 279-1971, “Criteria for Protection Systems for Nuclear Power Generating Stations.” IEEE Std 279-1971, Clause 4.15, and IEEE Std 603-1991, Clause 6.8.2, include requirements that when a reactor operation requires a more restrictive setpoint, the design shall provide positive means of assuring the more restrictive setpoint is used. Before the development of IEEE Std 279-1971 the staff required automatic adjustment to more restrictive settings of trips affecting reactor safety by means of circuits satisfying the single-failure criterion. The basis for this requirement is that the function can be accomplished more reliably by automatic circuitry than by a human operator. This design practice, which has also been adopted independently by the national laboratories and by much of industry, served as the basis for Clause 4.15 of IEEE Std 279-1971 and Clause 6.8.2 of IEEE Std 603-1991. More recently, applicants stated that their protection systems were designed to meet IEEE Std 279-1971 or IEEE Std 603-1991. A number of designs were proposed and accepted which reliably and simply satisfy this requirement. During the review of some applications, however, certain design deficiencies were found. The purpose of this position is to provide additional guidance on the application of Clause 4.15 of IEEE Std 279-1971 and Clause 6.8.2 of IEEE Std 603-1991. B. BRANCH TECHNICAL POSITION 1. If more