requirements such as capacity, reliability, limits, and settings. Component information such as seismic
qualification and equipment environmental qualification would be included here if not in a separate topical
DIS. Include or reference component design basis.
Discussion may include the following:
A description of each major component
A discussion of operating modes and the role of the component in the system
A discussion of how the installed component configuration satisfies the system design basis
These topics are separated from previous discussion for the benefit of the end-user. Selection of these
or other topics may be based on an analysis of user needs. Topics that are not separated would be
included in the previous sections. Both design requirements and design basis would be provided, with
emphasis on the design requirements. It may be appropriate to reference some basis material. The
following design topics for a system DIS could be presented:
Applicable Topical Areas. This section would reference applicable topical DISs and discuss
the scope covered by the topical DIS. Design requirements and design basis covered in topical
DISs do not have to be covered in the system DIS. The system DIS would provide a pointer to
the applicable topical DISs.
External Hazards. Discussion of the applicability of certain external hazards to the system may
be presented. Alternatively, reference discussion provided in topical DISs, such as
environmental qualification requirements, seismic requirements, fire protection requirements,
and hazards protection requirements (including flood protection, missile protection, tornado
protection, lightning protection etc.).
Structural Requirements. Discussion of the requirements for seismic, wind, thermal, water,
and any other static and dynamic load condition (including accidents), stress, shock, and
reaction forces. Equipment foundations and major components (e.g., tanks, pumps, heat
exchangers, ducts, and duct supports) may be discussed.
Operational Requirements. Description of specific operational requirements established in the
design process, such as acceptable operating modes, required operating ranges and limits,
special operational actions to be taken in the event of component failures or unusual operating
conditions (such as severe weather), special system interlocks requirements, and key
operational considerations for equipment and personnel protection.
Maintenance Requirements. Description of specific maintenance requirements established in
the design process, such as periodic maintenance requirements, acceptable maintenance
practices, preapproved part replacements, and maintenance ranges (e.g., switch setting
ranges, torque ranges etc.).
Special Material or System Chemistry Considerations. Discussion of any special materials
used in the system or components and the basis for material selection. Any materials that are
prohibited from use in the components/systems should be stipulated. In addition, any special
system chemistry considerations should be defined and discussed in this section.