05000530/LER-1995-001

LER-1995-001,

Event date:	9-5-0522
Report date:	0-0-0530"0-0-0530" contains a sequence that could not be interpreted against an available match matrix for date components.
Reporting criterion:	10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications
5301995001R00 - NRC Website

1. REPORTING REQUIREMENT:

This LER 530/95-001 is being written to report an event that resulted in the power plant being in a condition prohibited by the plant's Technical Specifications (TS) in accordance with 10CFR50.73(a)(2)(i)(B).

Specifically, at approximately 1102 MST on April 12, 1995, Palo Verde Unit 3 was in Mode 1 (POWER OPERATION), operating at approximately 100 percent power, when a momentary entry into TS Limiting Condition for Operation (LCO) 3.0.3 was made by Control Room personnel (utility, licensed) following a determination that the ACTION statement for TS LCO 3.4.9 could not be met because of the identification of a leak through a cracked weld in piping near the A charging pump (CB) suction drain valve 3JCHAVX083.

TS LCO 3.4.9 requires that the structural integrity of ASME Code Class 1, 2, and 3 components shall be maintained in accordance with Specification 4.4.9 during all Modes. With the structural integrity of any ASME Code Class 2 components) not conforming to the above requirements, restore the structural integrity of the affected components) to within its limit or isolate the affected components) prior to increasing the Reactor Coolant System (AB) temperature above 210 degrees Fahrenheit (F).

2. EVENT DESCRIPTION:

On April 12, 1995, during area rounds, a Unit 3 Auxiliary Operator (utility, nonlicensed) discovered a leak through a cracked weld in piping near the A charging pump suction drain valve. Upon reviewing TS, Control Room personnel (utility, licensed) identified that TS LCO 3.4.9 Action b was not met. The Control Room personnel entered TS LCO 3.0.3 at 1102 MST until the A charging pump could be isolated. The A charging pump was isolated at 1111 MST, TS LCO 3.0.3 was exited and compliance with TS LCO 3.4.9 ACTION b was achieved (i.e., isolate the affected component prior to increasing the Reactor Coolant System temperature above 210 degrees F).

EVENT:

Three charging pumps (CHA-P01, CHB-P01 and CHE-P01) supply Reactor Coolant System (RCS) makeup and RCP seal injection flow. The pumps are positive displacement pumps and each pump has a design capacity of 44 gallons per minute (gpm) at a discharge head of 2470 pounds per square inch (psi). The Design Basis requires that two charging pumps be supplied from a separate emergency power bus, and, that the third charging pump be capable of receiving power from either emergency power bus. Charging pump CHE-P01 is designed to be powered from either emergency power bus.

TS LCO 3.1.2.4 requires that at least two charging pumps be OPERABLE in MODES 1 through 4 (POWER OPERATION to HOT SHUTDOWN). At the time of discovery all three charging pumps were operable. Therefore, the removal of the A charging pump had no impact on plant operations and no additional TS LCOs needed to be entered as a result of this condition.

The event did not result in any challenges to the fission product barriers or result in any releases of radioactive materials.

Therefore, there were no safety consequences or implications as a result of this event. This event did not adversely affect the safe operation of the plant or health and safety of the public.

4. CAUSE OF THE EVENT:

An independent investigation of this event was conducted in accordance with the APS Corrective Action Program. On April 12, 1995, a visual examination of the welds on piping near the A charging pump suction drain valve was performed. No obvious faults were identified, although each weld was observed to have small irregularities.

A preliminary evaluation, based on testing, visual examination, and restoration, has determined that the apparent cause was a defective weld, most likely from original fabrication (SALP Cause Code B:

Design, Manufacturing, Installation Error). The evaluation determined that the defective weld failure was accelerated by the vibrational forces of the charging pump suction line from pump operation. Pulsations from each charging pump occur at approximately 600 and 1200 pulses per minute.

No unusual characteristics of the work location (e.g., noise, heat, or poor lighting) directly contributed to this event. There were no personnel or procedural errors which contributed to this event.

5. STRUCTURES, SYSTEMS, OR COMPONENTS INFORMATION:

Although there were no structures, systems, or components that were inoperable at the start of the event which contributed to this event, the apparent cause of the leakage was concluded to be due to a defective weld, most likely from original fabrication. The welds attached a valve to the suction line of the charging pump for the purpose of providing a drain for the line.

No additional structures, systems, or components were inoperable at the start of the event which contributed to this event. There were no additional component or system failures involved; therefore, no safety systems were rendered inoperable. No components with multiple functions were involved. There were no safety system actuations and none were required.

6. CORRECTIVE ACTIONS TO PREVENT RECURRENCE:

On April 12, 1995, the A charging pump was isolated to comply with TS LCO 3.4.9 and TS LCO 3.0.3 was exited. Visual inspections of the B (CHB-P01) and E (CHE-P01) charging pumps did not identify any material nonconformance or leakage.

On April 13, 1995, visual inspections were completed on all three charging pumps in Units 1 and 2 and no weld material nonconformance was detected.

On April 18, 1995, the Unit 3 A charging pump was repaired and returned to service. Both the piping and the weld were designed and installed per the applicable requirements of the ASME Boiler and Pressure Vessel Code. Sufficient nondestructive examinations were performed before, during and after the repair process to provide assurance that the pressure boundary was restored to within its original structural limits. Since all ASME Code requirements were met for stresses and fatigue allowables over a forty year design life, the repair is considered to be permanent.

7. PREVIOUS SIMILAR EVENTS:

A similar event to this condition was reported pursuant to 10CFR50.73 by LER 530/94-004-00, dated June 27, 1994. That LER reported conditions where two TS LCO 3.0.3 entries were made until TS LCO 3.4.9 ACTION b was met. This LER identified weld failures for a sample nozzle and instrument nozzle on steam generator 2 (SG-2) (AB).

Corrective actions taken for the previous event would not have prevented this event.

Arizona Public Service Company == PALO VERDE NUCLEAR GENERATING STATION ==

P.O. BOX 52034 o PHOENIX, ARIZONA 85072-2034 192-00930-JML/BAG/BE JAMES M. LEVINE May 5, 1995 == VICE PRESIDENT ==

NUCLEAR PRODUCTION

U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Mail Station P1-37 Washington, DC 20555 Dear Sirs:

Subject: Palo Verde Nuclear Generating Station (PVNGS) Docket Nos. STN 50-530 License Nos. NPF-74 Licensee Event Report 95-001-00 Attached please find Licensee Event Report (LER) 95-001-00 prepared and submitted pursuant to 10CFR50.73. This LER reports a Technical Specification Limiting Condition Operation (TS LCO) 3.0.3 entry until TS LCO 3.4.9 ACTION b was met by isolating the charging pump. In accordance with 10CFR50.73(d), a copy of this LER is being forwarded to the Regional Administrator, NRC Region IV.

If you have any questions, please contact Burton A. Grabo, Section Leader, Nuclear Regulatory Affairs, at (602) 393-6492.

Sincerely, JML/BAG/BE/pv Attachment cc: L. J. Callan (all with attachment) K. E. Perkins K. E. Johnston INPO Records Center *** END OF DOCUMENT ***