Component-Level Grading

DOESTD107393

Further, the DR adjunct program might uncover facility design requirements that affect system grading.

The impact on system grading should be considered for any newly found information. While system

grading is generally a one-time activity, it is reviewed and revised, as necessary, when new information

becomes available.

2.2.2.3 Component-Level Grading

The scope of component grading is much greater than that of system grading because of the much

greater number of components. However, the grading process is analogous. In addition to assigning

grades, this activity also formally establishes the detailed system boundaries and refines the assignment

of components to systems.

Component grading should not be attempted until there is a fairly complete set of design requirements

and thus the necessary level of detail. Initial component-related activities should focus on establishing

system boundaries and assigning components to systems. Initial or default component grades

equivalent to the associated system grade may be assigned until the design requirements information is

complete. If design reconstitution is necessary, the formal review of on-hand design information

documents should be completed fairly early to facilitate component grading. A flowchart for component-

level grading is presented as Figure 28.

List of SSCs. A complete list of facility components is essential if all possible SSCs are to be considered

for inclusion within the CM program. Existing configuration information in the form of a Master

Equipment List (MEL), required by DOE 4330.4A, Maintenance Management Program, or the equivalent

may be an adequate starting point for component evaluation. The initial CM program assessments will

examine the need for facility walkdowns to establish accurate facility drawings and equipment lists. The

CM program plan will reflect the results of these initial assessments. If comprehensive walkdowns are

not necessary and the component lists are essentially complete, system boundary evaluation and

component grading can proceed. However, if walkdowns or other activities are needed to define a

complete list of facility components, they will have to be coordinated with component grading. The

validated MEL should be combined with CM equipment data to form a single, complete equipment list

for the facility, contained in the CM equipment database, that will satisfy all data owners and users.

The first several steps shown in Figure 28 identify the scope of components that need grading. Known

components should be sorted into systems with other components that have the same basic functions

and processes or are located or connected together. Only systems that meet the CM program

equipment scope criteria need to be considered during the component-level grading activity. The next

step refines the system boundaries. Components are already assigned to systems at most facilities.

Following the refinement of system boundaries, it may be necessary to adjust the assignment of

components to systems.

System Boundaries. Facilities should carefully evaluate and define system boundaries. Systems should

contain those components that are necessary to fulfill the system's design requirements (e.g., the

functional and performance requirements). Design codes and standards often identify reasonable and

natural system boundaries. The following system interface considerations may apply to system

boundary evaluation:

Location of piping class breaks

Location of isolation valves

Location of seismic class breaks

Location of test features

Supporting features and functions

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