Validating the current configuration at a nuclear plant

One nuclear plant needed a process to validate that the configuration running on the control processors matched that of the intended design—no easy task, because the DCS parameter settings can run into the tens of thousands. The goals of the CM application in this case became the following:

 

• Fulfill the basic requirement of comparing the current configuration to an approved off-line design and present the discrepancies in a clear and concise format.
• Provide flexibility to track configuration changes without altering the plant’s engineering change process.
• Cover the gaps in the DCS vendor’s software, mainly in the areas of documenting the hardware and field wiring terminations.
• Provide a mechanism for introducing new points and configurations into the DCS.
• Wrap all of this functionality into an easy-to-use interface.

The first step was to select a database platform. It was expected that only one or two engineers would be actively using the database. Given budget and schedule constraints, Microsoft Access combined with Visual Basic won out over MySQL and Sequel Server because plant personnel would be most familiar with the former and setup time would be less. Access also does not require a dedicated server.

One challenge that had to be overcome was developing an extraction tool that would convert the DCS vendor’s proprietary information into a readable format.

The next step was to organize the data, segregating it into configuration information that is hardware independent and design information that is hardware dependent. (Hardware can advance rapidly while the design essentially remains the same.) In a subsequent layer of organization, the database fields were further classified as engineered, exempt, or reference information.

Each field was then controlled and secured relative to its importance, with engineered data at the top of the list. Fields classified as exempt include point classification, internal database revision numbers, and system codes. Reference information includes such data as drawing numbers, safety class, and sequence of events designation. Once this data is properly placed within the relational database tables, information can be presented in a clear, organized manner by using queries and forms.

To develop the tag or points list, the process engineer first adequately defines the desired inputs and outputs. This basic engineering information is then entered into the design database. Subsequently, a tag list is generated, which only contains the relevant engineering information needed by the software engineer. Fully defined block parameters received from the vendor are imported into the relational database, where they become part of the baseline (or off-line design) once new points are brought on-line in the field.

Validating the current on-line configuration is possible by using various software tools to report discrepancies in the parameter block settings as well as any new or missing configuration blocks. New block reporting also captures and verifies that new points were successfully migrated from the accepted off-line design into the control processors. Such verification supplements the plant’s engineering change process and provides complete confidence in the updated on-line configuration. Hardware integrity checks for the control processors, fieldbus modules, and termination assemblies are also built into the database.

Putting guards in place prevents improper changes from being implemented. “Improper” in this case means that they have not undergone required “doer, reviewer, approver” checks. The engineering modification coordinator has final control over implementing any change modification. Once the modification is validated with the Compare tool, the change is propagated throughout the database and archived for record-keeping purposes. Numerous reports can be generated, viewed, or printed. Examples include field wiring termination reports (by cable or termination assembly), block configuration parameters (vendor parameter settings), configuration validation exceptions (comparison), design block information (I/O list), and DCS plant modification report summary.

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