The Design Bases Rule (DBR) Set specifies which
specific requirement sources will be included in the
Configuration Management System (CMS). DBRs can be as
precise or as general as desired, ultimately
affecting only the scope of material included in the
CMS. The Design Bases Rules are designed to allow the
CMS developer to control the scope of the material
within the CMS. Since the cost of implementation is
directly related to the scope of material included,
this is a feature that allows the developer the
ability to manage the cost of retro-fitting the CMS
into an existing installation.
A decision was made to treat all requirements
uniformly regardless of source. While the CMS will
keep track of which requirements are regulatory
versus those that are not, the requirement hierarchy
does not specify a difference. As a result, concepts
such as Design Bases Values and Controlling
Parameters (and the associated confusion) are
eliminated.
Requirements are captured verbatim within the CMS
regardless of source, and are parsed (i.e., broken
down into smaller parts) as necessary to produce
manageable Design Bases Specifications. Software
technology makes management of large numbers of
complex requirements feasible, and opens up the
possibility that in the future, if requirement
sources adopt common technology for transfer of data,
the CMS would read requirements directly from the
regulator and other sources.
Design Bases Specifications (DBS) translate the
parsed requirements into high level statements that
describe how the specific nuclear production facility
will implement the requirement. Structure, System,
and Component Specifications (SSCS) translate
plant-specific DBSs into statements that specify how
individual structures, systems, and components (SSCs)
will implement the DBSs.
From SSCSs, we move into the historical engineering
work. SSCSs generate three classes of information:
Supporting Design Information, Design Parameters, and
Supporting Operating Information. Supporting Design
Information (SDI) is the set of documents that design
and procure individual components, including
calculations, drawings, purchase specifications, and
orders. Design Parameters (DP) are the values that
define characteristics, set points, and limits
associated with facility structures, systems, and
components. Finally, Supporting Operating Information
(SOI) is the set of procedures and operational
documentation necessary to fulfill specific
requirements.
Note that the SSCSs flow down to the documentation
(i.e., the SSCSs are implemented using
documentation). Then it is the documentation that
specifies the SSC, not the other way around. Finally,
at the bottom of the hierarchy, each SSC in the
physical facility is represented and connected to the
requirements that specify the SSC.