Definition:
A Design Requirement is any statement that specifies capability, capacity, limitations, inclusion, or exclusions that will be complied with at a nuclear production facility as determined by an associated Design Bases Rule.
Design Requirements include ALL requirements that must be met for the construction and operation of the nuclear production facility as specified by the Design Bases Rule Set. These may include all national and state regulatory requirements, other legal requirements, codes and standards, economic and non-regulatory requirements, and contractual obligations.
Example 1:
10CFR50, App. A, Criterion 34 -- Residual heat removal. A system to remove residual heat shall be provided. The system safety function shall be to transfer fission product decay heat and other residual heat from the reactor core at a rate such that specified acceptable fuel design limits and the design conditions of the reactor coolant pressure boundary are not exceeded.
Suitable redundancy in components and features, and suitable interconnections, leak detection, and isolation capabilities shall be provided to assure that for onsite electric power system operation (assuming offsite power is not available) and for offsite electric power system operation (assuming onsite power is not available) the system safety function can be accomplished, assuming a single failure.
Example 2:
10CFR50, App. A, Criterion 46 -- Testing of cooling water system. The cooling water system shall be designed to permit appropriate periodic pressure and functional testing to assure (1) the structural and leaktight integrity of its components, (2) the operability and the performance of the active components of the system, and (3) the operability of the system as a whole and, under conditions as close to design as practical, the performance of the full operational sequence that brings the system into operation for reactor shutdown and for loss-of-coolant accidents, including operation of applicable portions of the protection system and the transfer between normal and emergency power sources.
Example 3:
The plant shall produce 1000 MW electric.
(Note that this is an example of a Design Requirement that flows down from the Design Basis Rule to include contractual or economic requirements in the CMS.)
Example 4:
The Turbine Building elevator shall have a capacity of 5,000 kg.
(Note that this is an example of a Design Requirement that flows down from the Design Basis Rule to include non-regulatory requirements in the CMS.)
Example 5:
Seismic damping values from ASME Code Case N-411 shall be used for all ASME Section III, Division 1, Code Class 1, 2, and 3 piping systems.
(Note that this is an example of a Design Requirement that flows down from the Design Basis Rule to include Codes and Standards requirements in the CMS.)
Be aware that in the first two examples, for the purposes of the CMS, the requirement would be typically parsed into three or four sub-requirements to make crafting the subsequent DBSs more effective. Parsing requirements appropriately will minimize confusion and make the SSC-Requirement relationships more visible.
Also remember that Design Requirements are intentionally non-source specific. They might come from regulatory documents, or they might come from non-regulatory sources. To include or exclude specific sources, craft an appropriate Design Bases Rule.
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