Design Requirement 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.
Design Requirement 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.
Design Requirement 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 economic
requirements in the CMS.)
Design Requirement 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.)
Design
Requirement 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
DBR.
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Requirements Description