05000530/LER-2001-002

LER-2001-002, Unit 3 Mode 3 Entry With An Auxiliary Feed Water Pump Inoperable

Palo Verde Nuclear Generating Station Unit 3
Event date:	10-29-2001
Report date:	12-28-2001
Reporting criterion:	10 CFR 50.73(a)(2)(v), Loss of Safety Function
5302001002R00 - NRC Website

NAME

Daniel G Marks. Section Leader. Reaulatory Affairs TELEPHONE NUMBER (Include Area Code) 623=391=6492

13. COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT

CAUSE SYSTEM COMPONENT MANU- FACTURER

TO EPIX

14. SUPPLEMENTAL REPORT EXPECTED 15. EXPECTED

MONTH DAY YEAR

YES (If yes, complete EXPECTED SUBMISSION DATE) X NO 16. ABSTRACT (Limit to 1400 spaces, i.e., approximately 15 single-spaced typewritten lines) control room personnel entered Mode 3 with the steam driven Auxiliary Feed Water (AFW) pump inoperable. Unit 3 was being returned to service following a refueling outage.

Maintenance had been performed on both the steam driven AFW pump and the associated steam supply valves during the outage. Control room personnel incorrectly interpreted a provisional note in TSLCO 3.7.5 that allows Mode 3 operation with the steam driven AFW pump inoperable and proceeded with the mode change to Mode 3 on two separate occasions in violation of TSLCO 3.0.4. The steam supply valves were tagged closed and deenergized to comply with containment isolation requirements of Technical Specification Limiting Condition for Operation (TSLCO) 3.6.3 pending in-service valve testing. (The steam supply valves being closed and deenergized rendered the steam driven AFW pump inoperable.) Planned corrective actions to prevent recurrence include procedure changes and training.

1. REPORTING REQUIREMENT(S):

This LER (50-530/2001-002-00) is being submitted pursuant to 10 CFR 50.73 (a)(2)(i)(B), to report two violations of Technical Specification Limiting Condition for Operation (TSLCO) 3.0.4, which states, "When an LCO is not met, entry into a mode or other specified condition in the Applicability shall not be made except when the associated actions to be entered permit continued operation in the mode or other specified condition in the Applicability for an unlimited period of time.

TSLCO 3.7.5 for the Auxiliary Feedwater (AFW) System (EIIS code: BA) is applicable in Mode 1 (power operation), Mode 2 (startup), and Mode 3 (hot standby). There is no TSLCO 3.0.4 exception provision in TSLCO 3.7.5.

2. DESCRIPTION OF STRUCTURE(S), SYSTEM(S), AND COMPONENT(S):

The AFW System consists of one essential motor driven AFW pump "B" (EMS code: BA, P, MO), one non-essential motor driven AFW pump "N" (EIIS code: BA, P, MO), and one essential steam turbine driven AFW pump "A" (EIIS code: BA, P, TRB) configured into three trains. TSLCO 3.7.5 requires that three AFW trains be operable to ensure that the AFW System will perform the design safety function to mitigate the consequences of accidents that could result in overpressurization of the reactor coolant (EIIS code: AC) pressure boundary.

Two essential and one non-essential AFW pumps, in two diverse trains, ensure availability of residual heat removal capability for all events accompanied by a loss of offsite power and a single failure. This is accomplished by powering the essential motor driven AFW pump from an emergency bus (EIIS code: EK). The non-essential motor driven AFW pump can be manually loaded on its emergency bus.

The third AFW pump is powered by a diverse means, a steam driven turbine supplied with steam from a source not isolated by the closure of the Main Steam Isolation Valves (MSIVs) (EIIS code: SB, ISV).

The AFW System is considered to be operable when the components and flow paths required to provide AFW flow to the steam generators (EIIS code: AB) are operable. This requires that the two motor-driven AFW pumps be operable in two diverse paths, each capable of supplying AFW to either steam generator. The turbine driven AFW pump shall be operable with redundant steam supplies from each of the two main steam (EMS code: SB) lines upstream of the MSIVs and capable of supplying AFW flow to either of the two steam generators. The piping, valves, instrumentation, and controls in the required flow paths shall also be operable.

3. INITIAL PLANT CONDITIONS:

Prior to 1515 MST, on October 29, 2001, Unit 3 was in Mode 4 preparing to enter Mode 3 following a refueling outage. The steam supply valves to AFW pump "A" (containment isolation valves SGA-UV-134, SGA-UV-134A, SGA-UV-138, and SGA-UV-138A) (EIIS code:

NH, ISV) were tagged closed and deenergized to comply with Condition "C" (containment isolation requirements) of TSLCO 3.6.3. AFW train "A" was inoperable. AFW train "B" and AFW train "N" were operable.

4. EVENT DISCRIPTION:

On October 29, 2001, while returning to service following a refueling outage, Unit 3 entered Mode 3 at 1515 MST and Condition "A" of TSLCO 3.7.5. Condition "A" of TSLCO 3.7.5 contains a note that allows the AFW pump "A" to be inoperable in Mode 3 for up to 7 days provided Mode 2 had not been entered following a refueling outage. This note was recently added by License Amendment 134. Control room personnel (utility, licensed) interpreted this note to allow entry into Mode 3 following a refueling outage with the AFW pump "A" inoperable.

Maintenance had been performed on the AFW pump "A" and the associated steam supply valves during the outage. The steam supply valves were tagged closed and deenergized to comply with containment isolation requirements of TSLCO 3.6.3 pending in-service valve testing. (The steam supply valves being closed and deenergized rendered the AFW pump "A" inoperable.) On October 30, 2001, at 0315 MST control room personnel (utility, licensed) commenced a cooldown and depressurization of the reactor coolant system to repair a degrading reactor coolant pump (RCP) seal (EIIS code: AC, P, SEAL). At 0643 MST Unit 3 entered Mode 4 and exited Condition "A" of TSLCO 3.7.5. At 1142 MST Unit 3 entered Mode 5 and exited Condition "C" of TSLCO 3.6.3 for containment isolation valves SGA-UV-134, SGA-UV-134A, SGA-UV-138, and SGA-UV-138A.

Following the repair work on the RCP seal, on November 1, 2001 at 2304 MST, Unit 3 entered Mode 4 and Condition "C" of TSLCO 3.6.3 for containment isolation valves SGA-UV-134, entered Mode 3 and Condition "A" of TSLCO 3.7.5. Following the Mode 3 entry, a training instructor (utility, licensed) working in the outage realized that the mode change might have been done inappropriately and informed the Shift Technical Advisor (STA) (utility, non- licensed) of his concern. The STA reviewed the situation and concurred that entering Mode 3 with the AFW pump "A" was in violation of Technical Specification 3.0.4. On November 2, 2001 at 0854 MST control room personnel (utility, licensed) invoked TSLCO 3.0.5 to remove the tags from containment isolation valves SGA-UV-134, SGA-UV-134A, SGA-UV-138, and SGA-UV-138A for surveillance testing. The containment isolation valves and AFW pump "A" were tested and declared operable. Control room personnel (utility, licensed) exited Condition "A" of TSLCO 3.7.5.

5. ASSESSMENT OF SAFETY CONSEQUENCES:

There were no safety consequences associated with the inoperable AFW train "A" following refueling outage U3R9 for the following reasons:

TSLCO 3.0.4 was violated but compliance with TSLCO 3.7.5 was maintained. Once in Mode 3, following a refueling outage, decay heat load is very low. TSLCO 3.7.5 bases states that a 7 day completion time is allowed for an inoperable steam driven AFW pump in Mode 3 following a refueling outage due to the minimal core decay heat load and the availability of redundant AFW trains.

The condition existed for less than less than 24 hrs. Mode 2 was not entered.

Two other fully operable AFW trains were available during this time and capable of being powered by the emergency power source.

This condition would not have prevented the fulfillment of the safety function and did not result in a safety system functional failure as defined by 10 CFR 50.73(a)(2)(v).

6. CAUSE OF THE EVENT:

An independent investigation of this event was conducted in accordance with Palo Verde's corrective action program. The investigation determined there were two root causes for the event.

The first root cause was inadequate change management. In an effort to minimize overall plant risk, the in-service surveillance tests for the steam supply valves to AFW pump "A" were relocated to a surveillance test normally performed in Mode 3. The impact on the barriers to prevent this event were not thoroughly considered. Affected procedures were not properly revised and training was not implemented.

The second root cause was misunderstanding TSLCO 3.7.5, TSLCO 3.7.5 Condition "A", and incorrectly applying TSLCO 3.0.4. The training related to the changes to the surveillance tests and Technical Specification 3.7.5 was inadequate.

7. CORRECTIVE ACTIONS:

After recognizing that TSLCO 3.0.4 had been violated, the Control Room Supervisor (utility, licensed) invoked TSLCO 3.0.5 to remove the tags from containment isolation valves SGA-UV- 134, SGA-UV-134A, SGA-UV-138, and SGA-UV-138A to perform surveillance testing on the valves and AFW pump "A", exited Condition "A" of TSLCO 3.7.5, and declared AFW train "A" operable.

An independent investigation of this event is being conducted in accordance with Palo Verde's corrective action program. Based on the results of the investigation to date, the following corrective actions are planned to prevent recurrence:

The in-service surveillance test procedure for containment isolation valves SGA-UV- 134, SGA-UV-134A, SGA-UV-138, and SGA-UV-138A and associated cross-reference procedures will be revised to allow performance of valve stroke timing and valve position indication testing in Modes 5 and 6.

The mode change checklist(s) will be revised to include a check of AFW pump "A" operable prior to changing from Modes 4 to 3.

Training will be conducted for licensed operators on TSLCO 3.7.5, and Technical Specification general use including TSLCOs 3.0.1, 3.0.4, and their associated Bases.

If the final results of the investigation substantially change the planned corrective actions, a supplement LER will be submitted.

8. PREVIOUS SIMILAR EVENTS:

In the past three years, no similar events have been reported pursuant to 10 CFR 50.73 for violation of TSLCO 3.0.4.