Design analysis and calculations

DOESTD107393

therefore, to many different designs. For example, a design constraint for various safety

systems might be that they will be designed with sufficient capabilities to accomplish their

assigned safety functions in the presence of a single failure.

Design analysis and calculations are those intermediate design products that are necessary to

convert the design inputs and constraints into appropriate and complete design outputs. Design

analysis and calculations consist of a wide variety of engineering analyses, calculations, studies,

reports, and technical review checklists necessary to perform complete engineering design.

Examples of design analysis and calculations are: transient analyses, criticality analyses,

seismic stress calculations and analyses, equipment sizing calculations, net positive suction

head calculations, and engineering evaluations of equipment qualification and fire protection.

Design analysis and calculations capture the design assumptions and identify the available

design margin. The design margin is the conservatism between the specified design

requirement and the minimum requirement that could be developed from the design basis.

Design outputs are the documented products of the design process that specify the design

requirements for the facility structures, systems, and components, (SSCs). The design outputs

are the composite result of the engineering organization's consideration of the design inputs,

design constraints, and design analysis and calculations. Design outputs specify what is

required. Design outputs specify the necessary functions, capabilities, capacities, physical sizes

and dimensions, limits and setpoints, etc., as supported by the design basis. Examples of

design output documents are design change packages, drawings, specifications, load lists,

valve lists, one-line electrical diagrams, and setpoint lists. Design outputs include the functional

requirements, as well as procurement requirements, quality assurance actions,

construction/installation specifications and instructions, post-installation testing, post-

maintenance testing, and periodic surveillance/testing requirements. In some cases, the design

outputs are also referred to as the "as-designed conditions." The design output documents

provide the design requirements that dictate the physical configuration of the facility. Design

outputs best support the CM program objectives when they are documented in a format

amenable for proper use by the various user organizations, including procurement, construction,

operations, maintenance, and testing, as well as design engineering.

In relation to the design process, the CM program should be concerned primarily with identifying the design

requirements and design basis established by the design process and with maintaining the CM program basic

relationships based on the established design requirements. Design controls are the measures established

to ensure that the design process activities are carried out in a planned, orderly, correct, and documented

manner. Design controls have a direct impact on the quality of the design requirements that ultimately drive a

CM program. One of the most important design controls is the establishment of the design authority. The

design authority is the single organization responsible for establishing the design requirements, ensuring that

design output documents accurately reflect the design basis, and maintaining design control and ultimate

technical adequacy of the design process. Appendix II-A provides further information on design control.

Appendix II-B provides examples of design inputs, constraints, analysis and calculations, and outputs.

Design Basis vs. Design Requirements. Proper implementation of the DOE CM program entails an

understanding of the terms "design requirements" and "design basis." These terms have been a

particular source of contusion in the commercial nuclear industry. Some references define design

requirements to include not only the specific requirements but also the basis for those requirements.

Other references define design basis to include essential design requirements. From the designer's

viewpoint, design requirements might be the design inputs that are essential; from a construction or

installation viewpoint, design requirements might be everything on the drawings and specifications

I-B-5