"This standard provides minimum requirements for assurance that high-integrity software developed for use by the nuclear industry meets state-of-the-practice expectations for quality. The requirements in this standard are specified for development of high-integrity software. The intent is to set a minimum level of quality assurance and critical technical process requirements to satisfy due diligence. NUREG/CR 6263[1]@1) from which many of the requirements of this standard are derived@ was developed for application to nuclear power plants@ and this standard is primarily applicable to nuclear power plants and other nuclear facilities and operations with similar high consequences and hazards. This standard addresses rigorous@ systematic development of high-integrity@ non-real-time safety analysis@ design@ and simulation software that includes calculations or simulations requiring high functional reliability in order to avoid undetected errors that could have serious consequences if such errors are not detected (the scope of this standard does not include electronic procedures). It is especially important that this standard be followed in cases where calculations are so complex that typical peer reviews are not likely to identify errors. For complex software@ hand calculations and code-to-code comparisons may not be adequate to verify and validate the software. This may include software used for nuclear design and analysis; analysis of postulated accidents and assignment of safety classification levels to systems@ structures@ and components at nuclear facilities; computational fluid dynamics (CFD); thermal hydraulics; structural mechanics; complex Monte Carlo simulations; radiation dosimetry; and nuclear medical applications. An important area covered in this standard is model development and verification (including physics validation)@ which are critically important tasks for high-integrity analysis and simulation software. The requirements in this standard for model development and verification take into consideration several standards for the development of computational models and methods@ including ANSI/ASME VV 10- 2006 [2]@ AIAA G-077-1998 (2002)[3]; U.S. Nuclear Regulatory Commission (NRC) Standard Review Plan@ NUREG-0800@ Sec. 15.0.2[4]; and NRC Regulatory Guide 1.203 [5]. This standard provides the requirements necessary to validate the model by specifying requirements for model development and validation@ except that it does not address the actual planning@ design@ and conduct of validation tests/ experiments. Cybersecurity is another important aspect of high-integrity software and is explicitly addressed in this standard. The requirements in this standard for security requirements were principally derived from NRC Regulatory Guide 1.152 [6]. 1) Numbers in brackets refer to corresponding numbers in Sec. 18@ ""References."""