REGULATORY CONCERNS

Southern California Edison (SCE) is a leader in the nuclear industry’s trend to procure and dedicate commercial-grade equipment. Facilities in SCE new Commercial-Grade Dedication Laboratory, which serves the San Onofre Nuclear Generating Station, includes a 1,500 sq-ft seismic qualification laboratory provided by ANCO. Tom Herring, SCE Supervisor of Procurement Engineering, explained that because of the decrease in the number of nuclear-grade vendors, SCE has changed its procurement practices. Ten years ago most components were purchased from vendors with quality assurance programs meeting 10CFR50, Appendix B guidelines. Currently, many required components are unavailable from qualified vendors; and utilities must procure and dedicate (qualify) commercial-grade equipment for use in safety-related applications. This is a significant change from the regulatory and procurement practices of ten years ago and has been under close scrutiny by the NRC, as discussed in Generic Letter 91-05.

ECONOMIC INDUCEMENTS

Mr. Dick Clift, SCE Lead Project Engineer, stated "in order to meet the requirements of 91-05, SCE has committed to providing its commercial-grade laboratory with chemical, civil, mechanical, electronic, and seismic qualification capabilities. The costs of seismic qualification using external laboratories were high, and we had numerous cases where the turnaround in critical situations was too slow. Consequently, we decided to provide our own seismic shake table. We expect costs will break even in less than 3 years, and there is the immediate benefit of having the facilities available whenever we need them."

DESIGN REDUCES TIME & COST

The ANCO R-7 shake table, was installed at SCE’s Mesa facility (San Clemente, CA) in November 1992. A proprietary ANCO design, the R-7 is an upgraded version of the R-5 table which ANCO has used for ten years in its own facilities for seismic qualification of nuclear power plant equipment. Using three actuators, a triple torque tube and air bag suspension, the R-7 can produce statistically independent motion in any of three axes, simultaneously or sequentially, with peak displacements of ± 4 inches, peak velocity of 45 inches/sec, and peak acceleration of 3-10 g’s (for test specimen weights of 500-1,500 pounds). Spectral accelerations in excess of 30 g’s on a 5% damped response spectrum can be achieved. Equipment with base dimensions of up to 5 ft by 6 ft can be accommodated. With these capabilities, approximately 80% of SCE’s seismic qualification testing (per IEEE-344) can be performed in-house. The ability to test triaxially eliminates the need to rotate the test specimen. This reduces test time, cost, and unnecessary fatigue on the test item.

TURNKEY OPERATION

As part of the seismic laboratory, ANCO delivered a three-processor computer system for table control and equalization, dynamic response monitoring, and relay chatter evaluation. ANCO also provided Gardner Systems, Inc. computerized hydraulic controls, they hydraulic power supply, table installation, software, and training for the SCE test facility staff. SCE is providing the table foundation and laboratory structure. The unique symmetrical downturning actuator design of the R-7 allows installation on a simple at-grade flat foundation, eliminating the need for a table "pit".

ANCO’s President, Dr. Paul Ibanez, noted "we are pleased to help SCE achieve more effective and timely qualification capabilities, even though we will be potentially losing some qualification business. We look forward to continued service to SCE, including qualification of larger pieces of equipment, and assisting SCE to get the maximum benefit from their laboratory. This project has given us the opportunity to assemble one of the most unique, modern, capable, and cost-effective seismic shake table laboratories ever designed for in-house nuclear plant equipment qualification.