Document: NUREG-0800
Document ID: fea61ff0-f344-4101-adfb-590e3d9dfafe
Document Type: srp
Title: Draft Revision 6 – August 2015
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML1515/ML15159A946.pdf
Revision Date: 2023-06
Chapter: 7
Section ID: 7
CFR Part: 
CFR Title: 

Content:
cteristics can be divided into two sets: functional characteristics and process characteristics. The first set includes those characteristics that directly relate to the actions that the safety system software must take, while the second includes those characteristics of the software development process that contribute to assurance that the software will perform the required actions. Both sets are important in safety system software. The sets, and the definitions of the characteristics, are listed below. A.3.2.1 Definition of Functional Characteristics Accuracy - The degree of freedom from error of sensor and operator input, the degree of exactness exhibited by an approximation or measurement, and the degree of freedom from error of actuator output. BTP 7.14-7 Draft Revision 6 - August 2015 Functionality - The operations which must be carried out by the software. Functions generally transform input information into output information. Inputs may be obtained from sensors, operators, other equipment, or other software. Outputs may be directed to actuators, operators, other equipment, or other software. Reliability - The degree to which a software system or component operates without failure. This definition does not consider the consequences of failure, only the existence of failure. Robustness - The ability of a software system or component to function correctly in the presence of invalid inputs or stressful environmental conditions. This includes the ability to function correctly despite some violation of the assumptions in its specification. Safety - Those properties and characteristics of the software system that directly affect or interact with system safety considerations. The other characteristics discussed in this BTP are important contributors to the overall safety of the software-controlled safety system, but are primarily concerned with the internal operation of the software. The safety characteristic, however, is primarily concerned with the effect of the