18.104.22.168 Design Basis Review
If the proposed change is not within the current design basis, the contractor must perform
a design analysis for the change. The design analysis must be sufficiently detailed that
the technical reviewers can assess the adequacy of the analysis. The individuals
responsible for the technical review must be provided with the change control package
for those reviews. The design analysis should include:
current and proposed design inputs and constraints,
an analysis of the proposed changes and their impacts,
consideration of systems interactions,
any assumptions that must be verified in the post-operational testing, and
identification of any computer program that was used in the analysis.
Changes that affect the design basis require a design analysis by the design authority.
The design basis is generally identified by the design requirements in the equipment
database or the references listed in the equipment database. Therefore, changes to the
design requirements identified in the equipment database will likely require a design
Examples of changes that would require a design analysis:
a change that permits an increase in the maximum number of plugged tubes in a
heat exchanger beyond that indicated in the equipment database or safety analysis
a setpoint change outside the range of acceptable setpoints identified in the
Example of a change that does not impact the design basis and generally would not
require a design analysis is a change to an equipment setting that continues to be within
the range specified in the equipment database (e.g., a pump actuation setpoint that is
changed from 60 psig to 62.5 psig when the equipment database indicates the acceptable
range is 55 to 65 psig).
A change to the design basis will often involve a revision to the safety basis (DSA and/or
the TSRs). Revisions to safety bases involve significant effort by the design authority
and include external evaluations and approvals. Typically, changes to safety bases will
require USQ reviews. Consequently, the contractor should weigh the resources needed to
process the design change against the benefits of the proposed change. Another change
that could accomplish the objectives of the original change within the current design
basis might be more cost-effective.