Post-Maintenance Test Programs

Contents

• Introduction
• Notice Summary
• Applicability
• Maintenance Program Requirements
• Post-Maintenance Test Program Requirements
• Event Example
• Event Significance
• Program Control of Post-Maintenance Tests
• Commercial Industry Practice
• Final Evaluation
• References

Introduction

This notice is one in a series of publications issued by the Office of Nuclear and Facility Safety to share nuclear safety information throughout the Department of Energy complex. For more information, contact Dick Trevillian, Office of Operating Experience Analysis and Feedback, Office of Nuclear and Facility Safety, U.S. Department of Energy, Washington, DC 20585, telephone (301) 903-3074. No specific action or responses are required solely as a result of this notice.

Safety Notices are distributed to U.S. Department of Energy Program Offices, Field Offices, and contractors who have responsibility for the operation and maintenance of nuclear and related facilities, and to other organizations involved in nuclear safety. Written requests to be added to or deleted from the distribution of Safety Notices should be sent to: BR Richard L. Trevillian, EH-33, Room E-460 GTN, U.S. Department of Energy, Washington, DC 20585.

The ESH Office of Information Management maintains a file of Safety Notices and supporting information. Copies can be obtained by contacting the Office of Information Management at (301) 903-0449 or by writing to the Office of Information Management, U.S. Department of Energy, EH-72/Suite 100, CXXI/3, Washington, DC 20585.

Notice Summary

A Post-Maintenance Test (PMT) program is used at Department of Energy (DOE) facilities to ensure that structures, systems, or components function according to design specifications following maintenance.¹ Generally, post-maintenance tests are performed after corrective maintenance and sometimes after preventive maintenance. A successful PMT program confirms the following criteria regarding SSC.

• The original deficiency has been corrected.
• No new deficiencies have been created.

The equipment is ready to return to servicesatisfactory PMT verifies that (1) structures, systems, or components function as intended, (2) the deficiency was corrected, and (3) no new problems were created by the maintenance.²

DOE standards cited herein provide useful information related to facility management programs. The Guidelines to Good Practices² are meant to assist DOE field offices and contractor maintenance organizations in developing and reviewing programs for facility maintenance.

Applicability

The information herein applies to DOE departments and contractor organizations that have maintenance and repair responsibilities for production, operation, research, development, and demonstrations. No specific action or response is required solely as a result of this Notice. The Office of Nuclear and Facility Safety recommends processing this information in accordance with the guidance in DOE-STD-7501-95.³

Maintenance Program Requirements

It is essential that DOE facilities, complex-wide, comply with the policy and objectives of DOE 4330.4B¹ when establishing programs cost-effective maintenance and repair of DOE property. The policy requires the following, in part.

• Structures, systems, and components important to safe operation shall be subject to a maintenance program in order to meet or exceed lifetime design requirements.
• Periodic inspection of structures, systems, and components shall be performed to determine deterioration or technical obsolescence that threaten performance and safety.

Important objectives of maintenance programs include the following.¹

• Establish a review and analysis capability for evaluation of maintenance program performance and effectiveness.
• Ensure the reliability, safety, and operability of structures, systems, and components.
• Ensure that responsibility, authority, and accountability for maintenance are defined and appropriately assigned.
• Ensure that programs evaluate and measure property condition.

DOE policy and objectives underscore the importance of a program for maintaining plant safety and reliability. The PMT is one of the following interrelated processes of a maintenance job.

• Planning
• Scheduling
• Executing
• Post-maintenance testing
• Reviewing and completing^4,5

An effective PMT program requires the restoration of structures, systems, and components to operating or standby modes after testing for maximum equipment operability.

Post-Maintenance Test Program Requirements

Organizational and Individual Responsibility - This requirement applies to all structures, systems, or components that have been designated to receive post-maintenance testing. Assigned responsibility ensures that performance standards and test requirements are consistent with plant policies and objectives.⁶ Designating one organization to lead planning, scheduling, and coordination of test performance will ensure achievement of the following goals.

• Planning that ensures a consistent quality of maintenance for structures, systems, and components. The plan must include requirements for worker qualifications and training, job oversight, and quality control documentation.
• Scheduling that assists maintenance managers to control and direct PMT, assess progress, and use resources efficiently.
• Coordination that ensures resources are ready to support maintenance regardless of the complexity of the PMT.⁷

In addition, one individual should be assigned over-all responsibility for conducting the test and another individual should have over-all responsibility for reviewing test data and determining acceptability of the equipment.

Procedural Support - The level of procedural support is determined by the scope of maintenance and the level of required testing, which depend on the complexity of the system or component. Adequate assistance from the lead organization in determining the scope of testing is essential.

Each test procedure should define precautions, limitations, prerequisites, acceptance criteria, performance criteria, and other applicable parameters in accordance with facility-specific requirements.⁸ The level of detail should be based on maintaining safe and reliable facility operation. Functions that may have been affected by the maintenance should be checked.1,9 A procedure can be as simple as verifying a valve lineup after a sampling process or as detailed as an in-depth diesel generator replacement test.

A satisfactory PMT is one that verifies: (1) the ability of a particular SSC to perform its intended function, (2) the original deficiency has been corrected, and, (3) no new or related problems have been created by the PMT activitytest. The following are examples of the types of structures, systems, and components where a PMT may be of value. ²

• Liquid or gas systems
• Design-approved radiation shielding
• Wall thickness of pressure boundaries
• Mechanical strength of components or fittings
• Equipment for special programs
• Electrical distribution equipment and control circuitry
• Electronic components
• Instrumentation and instrument loops
• Measuring and test equipment
• Systems or components installed as temporary substitutes

If the PMT is covered by a regular system operating procedure or a procedure addressing a technical specification, operations personnel or someone from the responsible group should review the document for accuracy and applicability. The reviewer must also ensure that tests are included to verify that maintenance is complete.

Status Control of Post-Maintenance Testing - The status of system or component testing must be tracked to ensure that all tests are complete before work is closed out. Because the test may be part of a work control system with the objective of supporting the completion of maintenance tasks in a safe, timely, and efficient manner, test requirements should be clearly defined and include the following.⁶

• Detailed written test instructions
• Sufficient test scope to verify adequacy of the maintenance
• Test acceptance criteria

After a PMT is completed, the individual with over-all responsibility for reviewing test results must document and validate final test data for compliance with acceptance criteria to ensure that the structure, system, or component is performing properly before it is returned to service. That same reviewer must verify that the problem with the structure, system, or component was corrected and no new problems were introduced.

If the structure, system, or component fails the PMT, the status controller must identify re-testing requirements. A lack of complete documentation and test data may leave operations personnel unaware of equipment degradation or inoperability.

If the PMT cannot be performed immediately after maintenance, the responsible organization should hold the test form or maintenance package open until such time as testing can be accomplished. Then, as facility conditions allow, the reviewer should verify the PMT and close out the test form or maintenance.

Event Example

The following event illustrates how one facility identified and corrected a design deficiency by implementing the PMT program.

On April 6, 1995, at Savannah River, maintenance technicians were performing PMT on a breathing-air system in the H-Area Tank Farm when they discovered that the wrong solenoid valve was installed. ¹⁰

The post-maintenance test was to verify leak-tightness and operability of a solenoid valve that had been replaced. The test technicians used a new PMT procedure that tested both the component and the system under design conditions of low air pressure. The test consisted of isolating the solenoid valve and back-up air supply by closing valve C and pressurizing the header up to valve C using the pressure-regulated air bottles. (See figure) The technicians observed the pressure gage before the solenoid valve at A and after the solenoid valve at B as they pressurized the header. Pressure increased at A but not at B. The technicians had to actuate the pressure switch to energize the solenoid and open the valve. Under past PMT practices, maintenance technicians tested the solenoid valve by actuating the pressure switch at B and verifying solenoid operation. This tested only the valve and not the system response, so the design mistake was missed.

Bottled Air Simplified Flow Diagram

Investigators determined that the wrong valve was specified in the initial design documents when the system was installed in 1975. The original design specified a solenoid valve that was energized to open and fail to the closed position. The design should have specified a valve that was energized to close and fail to the open position. The correct design provides an alternate supply of air if the normal supply from the air-compressors fails or if electrical power to the solenoid is lost. The investigators believed that the new post-maintenance test procedure was instrumental in discovering the design deficiency.

Event Significance

This event is significant because the past PMT procedure for testing the solenoid did not lead to discovery of the wrong system design for twenty years. The incorrect solenoid valve may not have been discovered until the system failed during an emergency if the procedure had not been upgraded. Workers in air-supplied bubble suits need the reserve air provided by the bottles to allow them to exit work areas safely when the normal supply of air is lost.

The post-maintenance test should verify that the system functions as designed and is commensurate with requirements for reliability and safety.

Program Control of Post-Maintenance Tests

Control and documentation are an essential part of a PMT program.5 The following recommendations will assure better test control.

• During the processing of a PMT request, ensure that the responsible organization specifies the test requirements and reviews them for adequacy and inclusion of acceptance criteria.
• Develop clear, concise PMT procedural steps, plainly indicate stop points, and specify required verification signatures.
• Validate procedures against design basis documentation such as calculations and tolerances, vendor manuals, and other equipment-specific information that establishes set points or acceptance criteria.
• Ensure timely revisions to PMT procedures or written instructions by evaluating, correcting deficiencies, and upgrading requirements.
• After satisfactory completion of a PMT, ensure that the responsible organization accepts the structure, system, or component after reviewing and signing the appropriate test documentation.

Commercial Industry Practice

Commercial industry practices include the use of computerized tracking systems, pre-approved tests, and pre-operational system reviews. Computerized tracking of PMT requirements enables operators, planners, and supervisors to sort testing requirements by system and expiration date, reducing administrative workload as well as missed post-maintenance surveillances.

Maintaining pre-approved post-maintenance tests in a data base for each piece of equipment minimizes the work planner's research to prepare a work package. It helps determine required testing and ensures that tests on similar equipment are consistent.

Conducting a pre-operational review following maintenance ensures that the prescribed PMT is adequate based on the work performed. This review should be performed by a group of operations engineers, safety engineers, and maintenance supervisors. The group may prescribe additional testing if deemed necessary. The scope of the PMT procedure must ensure that maintenance was properly performed and that operational characteristics of the component and system continue to meet functional requirements.

Final Evaluation

Post-maintenance test programs should be an integral part of overall maintenance requirements. Maintenance is necessary to ensure safe and reliable operation of DOE facilities. Post-maintenance testing scope and adequate documentation are practices fixed on sound, established principles.

References

1. DOE 4330.4B, Maintenance Management Program.
2. DOE-STD-1065-94, Guideline to Good Practices for Postmaintenance Testing at DOE Nuclear Facilities.
3. DOE-STD-7501-95, Development of DOE Lessons-Learned Programs.
4. DOE-STD-1052-93, Guideline to Good Practices for Types of Maintenance Activities at DOE Nuclear Facilities.
5. DOE-STD-1053-93, Guideline to Good Practices for Control of Maintenance Activities at DOE Nuclear Facilities.
6. DOE-STD-1051-93, Guideline to Good Practices for Maintenance Organization and Administration at DOE Nuclear Facilities.
7. DOE-STD-1050-93, Guideline to Good Practices for Planning, Scheduling, and Coordination of Maintenance at DOE Nuclear Facilities.
8. DOE-STD-1029-92, Writers Guide for Technical Procedures.
9. DOE 5480.19, Conduct of Operations Requirements for DOE Facilities.
10. DOE Occurrence Report SR--WSRC- HTANK-1995-0023, "Design Flaw on Backup Breathing Air System," April 10, 1995.