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Insp Repts 50-352/96-09 & 50-353/96-09 on 961022-1216. Violations Noted.Major Areas Inspected:Operations,Maint, Engineering & Plant Support
	ML20133H739
Person / Time
Site:	Limerick
Issue date:	01/09/1997
From:	; NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
To:	;
Shared Package
ML20133H694	List: ML20133H691; ML20133H713; ML20133H739;
References
	50-352-96-09, 50-352-96-9, 50-353-96-09, 50-353-96-9, NUDOCS 9701170274
	Download: ML20133H739 (41)
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U.S. NUCLEAR REGULATORY COMMISSION

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REGION I ;

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License Nos. NPF-39

NPF-85 i

Report Nos. 96-09 '

96-09 '?

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Docket Nos. 50-352 j

50-353

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Licensee: PECO Energy !

Correspondence Control Desk i

P.O. Box 195

Wayne, PA 19087-0195

Facility Name: Limerick Generating Station, Units 1 and 2 !

Inspection Period: October 22,1996 through December 16,1996 i

inspectors: N. S. Perry, Senior Resident inspector i

F. P. Bonnett, Resident inspector ,

F. J. Laughlin, Emergency Preparedness Specialist, DRS l

N. T. McNamara, Emergency Preparedness Specialist, DRS !

R. L. Nimitz, Senior Radiation Specialist, DRS

D. M. Silk, Senior Emergency Preparedness Specialist, DRS i

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Approved by: Walter J. Pasciak, Chief l

Projects Branch 4

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9701170274 970109

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additional information obtained after the connector is replaced and the old one is

inspected for indications of other damage or problems (Section E8.1).

Plant Suncort

e PECO Energy continued to maintain a strong Emergency Preparedness (EP) program.

The Emergency Plan and emergency response procedures were current and

effectively implemented. The emergency action level table for radiological releases

was found to be somewhat confusing but easily clarified. The emergency response

facilities were well-maintained and operationally ready, Management control and

involvement was very good. One EP staff position was vacant, but was slated to

be filled. All emergency response organization (ERO) training was current and all

required drills had been completed. The 1995 EP program audit was acceptable in

that it met 10 CFR 50.54(t) requirements, but it provided no substantive feedback

to EP. There were very good mechanisms in place for problem identification and

resolution, including a well-defined self-assessment prograrn (Section P). .

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e Overall, applied radiological controls were good including planning and preparation

for the outage (Section R1.1). Weaknesses were identified in the control of

radioactive sources (Section R1.3). The 10 CFR 20.2002 disposal area was found

to be generally consistent with information provided to the NRC. However, a

violation of 10 CFR 50.9, involving failure to provide complete and accurate

information to the NRC in an application for disposal of slightly contaminated

flowable solids, was identified. The flowable solids were placed on a 40,000

square foot (4 feet thick) concrete stab; and the April 6,1995, submittat did not i

discuss or describe the presence of the concrete pad (Section R2.1).

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01.2 Unit 2 Scram and Start-uo

a. Scone (71707)

Control room operators manually scrammed the Unit 2 reactor on December 6, due to an

EHC oil leak from the No. 2 TCV relayed emergency trip supply (RETS) pressure switch PS-

001202D. Plant management decided to enter an one week outage to repair a number of

plant discrepancies. Operators restarted the reactor on December 13. The inspectors

reviewed the events surrounding the scram, attended various meetings, and discussed the

event with key individuals. Further, the inspectors observed shutdown activities and

portions of the startup in the control room.

b. Observations and Findinas

The operators demonstrated a good awareness of changing plant conditior.d when the

" Turbine Control Valve Fast Closure Trip" annunciator alarmed and a coincident EHC half

scram signal occurred in the control room at 11:20 p.m. The reactor operator (RO) noted

that all TCVs were open and that there were no changes in reactor plant or balance of

plant parameters. After unsuccessfully attempting to reset the half scram, the operators

suspected a blown circuit fuse, but also directed the equipment operator (EO) to assess

conditions at the EHC skid. The EO reported that EHC reservoir level had dropped to a

negative six inches (normal level zero inches) and was continuing to dron. The control

room supervisor (CRS) assessed that EHC conditions were deteriorating and directed the.

RO to insert a manual reactor scram at 11:38 p.m.

Operators responded to the scram well, entering the appropriate procedures and stabilizing

the reactor following the scram. Reactor !evel dropped to -25 inches which required entry

into Transient Response implementation Plan (TRIP) procedure T-101, Reactor Pressure -

Vessel Control. Reactor feed pumps (RFP) remained in service and feedwater flow was

more than adequate for operators to control reactor level. The EO isolated the affected

EHC header to the TCVs (isolating the leak), which allowed the ROs to cool down the plant

using the main turbine bypass valves. Operators placed the plant in a cold shutdown

condition on December 7.

System engineers and operators determined that the reactor protection system (RPS) had

responded appropriately, since the operators initially determined that plant parameters did

not support a half scram and suspected a blown fuse. The RETS pressure switch fell,

because its support bracket failed. This caused the 0.25 inch stainless steel tubing to the

pressure switch to fail. The pressure switch sensing low EHC pressure initiated the non-

resettable half scram signal to the RPS. The TCV did not close because the leak was small

enough to maintain sufficient oil pressure at the TCV servo's actuator disc dump valve to

prevent it from actuating.

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The TCV fast closure scram signal is generated from the RETS pressure switch that senses

l low RETS pressure at the TCV. The scram signal to RPS is an anticipatory signal to scram

l the reactor prior to a pressure and neutron flux transient that would result from a load

reject with or without bypass valves. Fast closure of the TCV is accomplished by the

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repositioning of the TCV actuator disc dump valve in the TCV se 'o redirecting actuating

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oil back to the EHC reservoir.

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l Control room operators maintained a professional atmosphere in the control room during

l the Unit 2 shutdown. The inspector observed the conduct and coordination of several

surveillance tests and maintenance activities being performed in the control room. The

CRS assured that the work was accomplished in an orderly fashion that did not disrupt the

conduct of operations cr cause other distractions, j

Unit 2 operators conducted the subsequent reactor startup well. The inspector observed !

several shift briefings and noted that they were thorough and technically sound. Several

briefings focused on RO response to a short reactor reactivity period, which included three l

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acceptable strategies for addressing the issue. Reactor ongineers were present throughout

the startup, providing assistance to the operators and monitoring core performance and

response. The reactor was made critical at 4:28 p.m. on December 13, and the generator

was synchronized to the grid on December 14,

c. Conclusions

The inspector concluded that the operations staff response to the event, control of the unit

during the shutdown, and conduct during the startup were very good.

01.3 Unit 2 Drvwell Closeout inspection (71707)

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On December 12, the inspector performed a pre-closeout inspection of the Unit 2 drywell !

prior to the formal closcout inspection by plant management. The inspector verified that l

materialin the drywell was properly stored, and that areas, where work had been i

performed, had been cleaned up as required. All areas inspected were found to be in good )

condition, with no discrepancies identified.

O2 Operational Status of Facilities and Equipment j

O 2.1 Routine Plant Tours (71707)

The inspectors used Procedure 71707 to perform routine tours of the facility and also to

walk down accessible portions of the engineered safety feature (ESF) systems:

e Standby Liquid Control System - Unit 1 l

Primary Containment instrument Gas - Unit 2 l

e Drywell portion of Core Spray and Residual Heat Removal (RHR) Systems - Unit 2 l

e Emergency Diesel Generators (EDGs) - Unit 1 and 2 i

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Equipment operability, material condition, and housekeeping were acceptable in all cases I

except for the EDGs (See Section M2.1). Several minor disciapancies were brought to

management's attention and were corrected. The inspectors identified no substantive

concerns as a result of these walkdowns.

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Report Details

Summarv of Plant Status

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Unit 1 began this inspection period operating at 100 percent power. The unit remained at

full power throughout the inspection period with exceptions for testing and the following

plant events.

o October 22 Power was reduced to 91 percent in response to a lube oilleak

at the main turbine front standard. The minor leak was from

the seal between the permanent magnet generator and front .

standard casing. Maintenance technicians repaired the leak '

and reactor operators restored the unit to full power the same

day.

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e November 16 Power was reduced to 60 percent to perform on-line l

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maintenance on 63 hydraulic control units (HCU).

Maintenance activities were completed and the unit retumed to

full power on November 20.

Unit 2 began this inspection period operating at 100 percent power with the six*.h stage l

feedwater heaters removed from service for end-of-cycle (EOC) coastdown operations.

Operators removed the fifth stage feedwater heaters from service on November 6, to

maintain full power operation. Operators manually scrammed the reactor on December 6,

in response to an electro-hydraulic control (EHC) oil leak at the No. 2 turbine control valve

(TCV). After completing a one week maintenance outage, operators restarted the reactor

on Decembsr 13. The unit was operating at 29 percent power when the period ended,

with plant personnel trying to identify the source of air in-leakage to the main condenser..

l. Operations

01 Conduct of Operations'

01.1 General Comments (71707)

Using Inspection Procedure 71707, the inspectors conducted frequent reviews of ongoing

plant operations. In general, PECO Energy's conduct of operations wres professional and

safety-conscious. Operators conducted normal activities including shift turnovers and pre-

shift briefings well. Operators continued to demonstrate good communication skills and

control of several plant evolutions, including the Unit 1 on-line HCU maintenance and

removal of the fifth stage feedwater heaters at Unit 2. Operators responded well to

stabilize plant conditions following the Unit 1 power decrease on October 22, and the Unit

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2 scram.

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' Topical headings such as 01, M8, etc., are used in accordance with the NRC standardized

. reactor inspection report outline. Individual reports are not expected to address all outline

topics.

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07 Quality Assurance in Operations

07.1 Self-Assessment Activities (71707)

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During the inspection period, the inspectors reviewed or attended multiple self' assessment

activities, including.

the December 5, regularly scheduled Nuclear Review Board (NRB) meeting;

various Plant Operations Review Committee (PORC) meetings and meeting minutes;

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e the November 27, EDG Branch critique of the D-14 shutdcwn during its routine

surveillance test to investigate an unusual vibration and noise;

various quality verification and independent safety engineering group reports. i

The NRB and PORC reviewed several activities related to safe station operation. PORC

scheduled several special meetings to discuss root causes and corrective actions for the

Unit 2 scram (see Section E1.2), and corrective actions necessary to implement, to achieve

compliance with the facility operating license regarding a safe shutdown fire (see Section

E1.3). The members of the NRB and PORC actively participated in the meeting with open

discussions on the plant issues while maintaining a focus on safety. The inspector

concluded that the self-assessment activities were effective. j

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ll. Maintenance )

M1 Conduct of Maintenance

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M 1.1 2A Core Sorav Trio Unit Replacement 62707

The inspector observed activities associated with the replacement of the Unit 2, A core v

spray trip unit. Instrumentation and control (l&C) technicians troubleshooting the 2A core

j spray trip unit were very knowledgeable and technically competent in accomplishing the

1 activity. The l&C technicians were members of the Limerick Fix-It-Now (LFIN) team. The

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technicians determined that the trip unit was intermittently causing a channel gross fail

signal and replaced the trip unit.

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The technicians also identified several questionable ground connections that appeared

. loose in back of the core spray logic panel. The technicians notified their supervisor who

initiated an action request to have all cabinet ground connections tightened at a future time

because of system interaction concerns with other operable systems. The ground strip in

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the cabinet affects signal common busses on the trip unit racks which could cause

spurious loss of coolant accident (LOCA) signals in other emergency core cooling systems.

l Maintenance planning assessed that the existing ground connections were adequate and

would be addressed during the upcoming refueling outage.

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, The LFIN performed the troubleshooting and trip unit replacement activities safely. A good

questioning attitude was demonstrated by technicians.

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M1.2 Maintenance Outaae - Unit 2 l

a. Scooe (62707)

As a result of the Unit 2 scram on December 6, plant management decided to implement a

week long maintenance outage. The scope of the outage was to repair the EHC leak,

replace leaking safety relief valves (SRV), repair other leaking valves located in the drywell,

and address seventeen main control room deficiencies. The inspectors reviewed and l

observed activities throughout the outage.

b. Observations and Findinas

Maintenance technicians executed repairs to all RETS pressure switches on all four TCVs.

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The pressure switches were remounted on modified brackets and all stainless steel tubing

to each pressure switch was replaced. Further, l&C technicians identified a possible failure i

of the flexible hoses connecting the EHC supply header to the TCV servo valves and these 1

were replaced. The hoses displayed small bubbles under the outer layer of the hose

material. Subsequent testing at Valley Forge Laboratories determined that the hoses had i

not mechanically failed.

Due to excessive tailpipe temperatures on three SRVs, plant management directed that the

E, G, and H SRVs be replaced. Technicians performed the work well, using the appropriate

procedures and work orders. No discrepancies were noted.

Technicians discovered a substantial leak from the bearing cap of the 2A core spray

testable check valve, HV-052-2F006A. The valve is an inboard primary containment

boundary valve, but the leak did not affect downstream core spray piping. Operators .

assessed that the leak was a substantial contributor to the drywell leakage that had been

slowly increasing prior to the shutdown, and that the leak did not affect the valve's

operability. Technicians replaced the bearing cap gasket which stopped the leak. This

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was determined during various drywell walkdowns during the performance of the reactor

pressure vessel hydrostatic test on December 11. Engineers determined that localleak rate

testing was not required for the repair because the valve internals were not disturbed.

Several other activities were accomplished during the outage including, repair of the 2C

RFP casing drain leaks, replacement of clogged drywell unit cooler condensate flow

elements, and replacement of a degraded circulating water pump expansion joint. The

inspector observed these activities and had no concerns.

c. Conclusions

The inspector concluded that the maintenance outage at Unit 2 was conducted very well.

Many work activities were safely and successfully completed without incident.

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The inspector noted that foreign material exclusion (FME) measures were adequate, but l

questioned the implementation of FME controls during short breaks. The inspector

identified that the upper crankcase or fittings were not covered. These concerns were

immediately addressed by the maintenance personnel. The Maintenance Director informed

the inspector that measures are being established to implement FME controls consistently

during diesel outages.

The D24 EDG failed to shut down during a post-maintenance break-in run. The EO

identified a fuel oilleak at the No.10 cylinder and attempted to shut down the EDG using

the emergency stop pushbutton located on the diesel. l&C technicians identified a faulty ;

contact on the engine trouble shutdown relay that energizes the shutdown relay. The l

control room supervisor (CRS) determined that the failed engine trouble shutdown relay

was e achnical specification (TS) required component; however, the EDG was currently

inoperable for the outage. The system manager initiated a troubleshooting control form to l

test the other engine trouble shutdown relays and verified their operability on the remaining l

seven EDGs.

The Woodward governor replacement went well. The governor was replaced to address a j

speed oscillation problem. Control room operators had observed some hunting and speed

oscillations during normal operations when D24 was carrying the bus and isolated from the

grid. Attempts to tune the governor had not been successful in resolving this problem.

Following the governor replacement, l&C technicians and the system manager tuned the

new governor. The inspector observed the activities, which were well controlled. A

special test was written to demonstrate proper operation of the governor in both the droop

and isochronous modes of operation. The inspector reviewed the procedure and safety

evaluation (10 CFR 50.59) and had no concerns. The system manager successfully

directed the test from she control room, but noticed that the hunting problem had not been

completely resolved.

During the Unit 2 maintenance outage, the CRS removed the D24 EDG from service for

maintenance technicians and the system manager to further investigate the governor

hunting. A knuckle in the linkage arm between the governor unit and engine demonstrated

excessive freedom of movement, approximately 3-4 mils. This fitting is required to be

tight. The loose knuckle introduced a delay in engine response to changes in spaed

causing the governor to overreact to frequency changes. This loose knuckle was replaced.

The D24 EDG performed well during the post-maintenance surveillance test. The D24 EDG

was extensively tested during the performance of ST-1-092-114-2, D24 Diesel Generator

4KV Safeguards Loss of Power Logic System Function Test. The inspector observed the

entire test which demonstrated the EDG's ability to start upon either or both Loss of

Offsite Power (LOOP) and Loss of Coolant Accident (LOCA) signals. Further, the test

demonstrated the EDG's ability to continue running after a complete load shed and the loss

of the largest post-LOCA load (RHR pump).

The inspector observed that no hunting or oscillations occurred during the test, during

parallelling operations with offsite power, or during various generator loading conditions.

The system manager directing the surveillance test maintained good control, as well as the

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M1.3 Hydraulic Control Unit On-line Maintenance - Unit 1

a. Insoection Scoce (62707)

PECO Energy's Nuclear Maintenance Division (NMD) performed an on-line maintenance

outage on selected Unit 1 hydraulic control units (HCUs) beginning on November 16. The

maintenance focused on rebuilding or replacing various HCU components including the

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scram pilot valves and the inlet and outlet scram valve diaphragms. Maintenance

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technicians used maintenance procedure M-047-027, rev. 6, Preventive Maintenance for

HCUs, throughout the activities. NMD technicians rebuilt 63 HCUs over a four day period,

completing the activity on November 20. The inspector observed the activities performed

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b. Observations and Findinas

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Work Activities were planned, coordinated, and exe= ted well between the Operations and

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NMD Departments, and the reactor engineering staff. Operators and reactor engineers

performed a large number of control rod manipulations without error. Further, NMD

personnel performed clearance and tagging responsibilities, maintenance activities, and ,

HCU restoration without error. Following HCU restoration, operators performed scram time

testing to verify the control rod's operability. No discrepancies were identified.

During the maintenance activities, NMD technicians identified two degraded components

on two different HCUs. A scram valve position limit switch which indicates valve position

in the control room and a broken terminal board were replaced. The inspector observed

that the technicians exercised caution and appropriate controls during the repairs.

Radiological controls were noted to be very good.

c. Conclusion i

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NMD had established good control and oversight of the work activities. Technicians and

operators completed the activity without error or challenge to safe plant operations. ;

M1.4 D-24 Diesel Overhaul and Testina

a. Scoce (62707)

From November 18 through 24, maintenance personnel performed the 18 month

inspection, testing and general maintenance on the D24 EDG. The scope of the outage

included the replacement of the Woodward governor. The inspectors observed portions of

the maintenance work and post-maintenance testing, including special test SP-173, D24

Diesel Generator Governor Test and ST-1-092-114-2, D24 Diesel Generator 4KV

Safeguards Loss of Power Logic System Function Test.

b. Observations and Findinas

The maintenance technicians performed the outage well. The inspector observed that

work activities were well controlled, with improved housekeeping practices implemented.

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coritrol room staff that coordinated the various sections of the test to prevent disruptions

in the control room.

c. Conclusions

The inspectors concluded that the Limerick staff performed the 18 month inspection and

maintenance of the D24 EDG well. Improved housekeeping practices during the outage

were observed, but FME controls although adequate, need to be improved. The persistent

effort of plant personnel to identify the cause and correct the oscillation problem was

notable. The operations and technical staffs' performance of the LOOP /LOCA surveillance

test was very good.

M1.5 General Comments on Surveillance Activities (61726)

The inspectors observed selected surveillance tests to determine whether approved

procedures were in use, details were adequate, test instrumentation was properly

calibrated and used, technical specifications were satisfied, testing was performed by

knowledgeable personnel, and test results satisfied acceptance criteria or were properly

dispositioned.

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The inspectors observed portions of the following surveillance activities:

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D14 and D24 overspeed tests

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various EDG monthly tests

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Unit 2 control rod scram timing l

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D24 special test (SP)-173

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Unit 1 standby liquid control pump, valve and flow test l

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D24 loss of power logic system function test

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Unit 1 reactor core injection cooling quarterly test

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security system static inverter test

Observed surveillance tests were conducted well using approved procedures,and were I

completed with satisfactory results. Communications between the various work and i

support groups were good, and supervisor oversight was good.

M2 Maintenance and Material Condition of Facilities and Equipment

M2.1 Emeraency Diesel Generator Material Condition

a. Scope (62707)

During this inspection period, the inspectors conducted thorough walkdowns of all eight

EDGs. The inspectors observed the general conditions of the EDGs and verified that no

conditions existed which would adversely affect the operation of the EDGs, or cause it to

be inoperable.

ML20133H739

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