ML20134J996

Insp Rept 50-312/85-16 on 850601-0714 & 20-31.No Violation or Deviation Noted.Major Areas Inspected:Operational Safety Verification,Maint,Licensee Event Followup,Safety Features Review & Surveillance Activities

ML20134J996
Person / Time
Site:	Rancho Seco
Issue date:	08/13/1985
From:	Eckhardt J, Miller L, Perez G NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V)
To:
Shared Package
ML20134J990	List: IR 05000312/1985016 ML20134J987
References
50-312-85-16, GL-83-28, NUDOCS 8508290543
Download: ML20134J996 (10)

See also: IR 05000601/2007014

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U. S. NUCLEAR REGULATORY COMMISSION

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REGION V-

. Report No.. 50-312/85-16 .

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. ' Docket.No. 50-312

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s- . Licensee: Sacramento Municipal Utility District

.P. O. Box 15830

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Sacramento, California 95813

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Facility Name: RanchoNecoUnitI

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Inspection at: Herald, California (Rancho Seco Site)

Inspection. Conducted: une 1 u and July 20-31, 1985

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Inspectors:

J. HU Ec ard

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oY Resident Inspector

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Date Signed

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Date Signel

G.. PUPer z, Rem)4

f Inspector

Approved By: '#17 I )_

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L. F. e'r Jr. , ftfef

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Reacto Projects Seftion.2

Summary:

Inspection beteen June 1-July 14 and July 20-31, 1985-(Report No. 50-

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312/85-16). ' -

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Areas Inspected: This routine * inspection by the Resident Inspectors involved

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the areas of operational safety; Verification,' maintenance, licensee event

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followup, safety features' review, and surveillance activities. During this

inspection, Inspection. Procedures 61726, 62703, 71707, 71710, 92700, 94703,

92704,'and 92706 were covered.' 'This inspection involved 183 hours0.00212 days <br />0.0508 hours <br />3.025794e-4 weeks <br />6.96315e-5 months <br /> onsite by

two resident inspe'ctors.

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Results: Of the areas.. inspected, no violations or deviations were identified.

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1 DETAILS

1. Persons Contacted ,

P. Oubre', Manager of Nuclear Operations

• G. Coward, Plant. Superintendent

• N. Brock, Electrical /I&C: Maintenance Supervisor

H. Canter, QA Engineer

• R.-Colombo, Regulatory Compliance Supervisor-

• S. Crunk, Associate Nuclear Engineer.

• J. Field, Engineering and Quality Control Superintendent

J. Jurkovich, Site Resident Engineer.

F. Kellie, Assistant Chemical and Radiation Superintendent

R. Lawrence, Mechanical Maintenance Supervisor,

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C. Linkhart, Senior Electrical Engineer

R. Miller, Chemistry and Radiation Protection Superintendent

-S. Redeker, Shift Technical Advisor Supervisor

• R. McQuade, QA Engineer

L. Schwieger, Quality Assurance Director

W. Spencer, Operations Superintendent

Other licensee employees contacted included technicians, operators,

mechanics, security and office personnel.

-* Attended the Exit Meeting on July 31, 1985.

-2. Operational Safety Verification

e

At the start of this report period the licensee was completing the

activities scheduled for their refueling outage which started on March

15, 1985. The plant commenced heatup on June 10, 1985 and reached

criticality on June 14, 1985. Zero and low power physics testing was

performed. On June 18, 1985, reactor power was reduced from fourteen

percent power and cooled down to repair a clogged turbine lube oil line.

Af ter completion of the lube oil system reaintenance, the plant began

heatup on June 23, 1985. The plant was approaching criticality again

when an Unusual Event was declared due to a reactor coolant system leak.

The plant was subsequently brought to cold shutdown, and remained in this

condition throughout the remainder of this report period. The events

surrounding the reactor coolant system leak will be discussed in a future

inspection report (50-312/85-19).'

The inspectors observed control room operations, reviewed applicable

logs, and conducted discussions with control room operators. The

inspectors verified from the control room that the appropriate decay heat

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removal requirements were being met. Tours of the auxiliary building,

turbine building, and reactor building, including exterior areas, were

made to assess equipment conditions and plant conditions. Also the tours

were made to assess the effectiveness of radiological controls and

adherence to regulatory requirements. The inspectors also observed plant

' housekeeping / cleanliness conditions, looked for potential fire and safety

hazards, and observed security and safeguards practices.

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No~ violations or deviations were identified.

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3. Facility Staff Changes

On June 21, 1985 the Chemistry and Radiation Protection (CRP)

Superintendent resigned from his position. In the interim, until the

position is filled, the Assistant Chemistry and Radiation Protection

Superintendent has assumed the duties and responsibilities of the CRP

Superintendent.

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On July 18, 1985 the SMUD Board of Directors announced the selection of i

two new members to the licensee's management staff. These were Messrs. I

Dewey K. Lo'we, selected for Deputy General Manager, and Frank Hahn,

selected for Assistant General Manager for Planning. Mr. Lowe recently

retired as a Major General in the United States Air Force. Mr. Hahn has

recently been the Chief of the Energy Division _for the California

' Department of Water Resources.

The licensee has also announced a temporary position change in the

nuclear training area. The Nuclear Training Superintendent was moved to

a position devoted full time to acquiring a plant specific simulator, and

the Nuclear Training Supervisor has been assigned the duties and

responsibilities of the Nuclear Training Superintendent.

4. Followup on Headquarters Request (Temporary Instruction 2515/67) (Closed)

l The inspectors were requested by NRC Headquarters to review the

~11censee's actions involving a safety issue addressed in IE Information

Notice 83-75, " Improper Control Rod. Manipulation". The notice dealt with

the safety significance of control rod misIositioning

i events, including

plant operation with a mispositioned~ control. rod.

The licensee's procedures and training were reviewed and the following

was identified:

Procedures existed for recovery froai a mispositioned rod

Procedures existed for verifying rod position when one form of

normal indication is lost

Training has been provided fer operators in the proper movement of

control rods, the consequences of improper movement, and the

consequences of operating with a mispositioned rod

It appeared that the licensee has provided the proper procedures and

training to address the safety issue of a misposition control rod.

No violations or deviations were identified.

5. Failure of a Reactor Trip Breaker During Testing (LER 85-06 (Closed))

On June 5, 1985, while the licensee was performing surveillance and

calibration on the "C" channel of the Reactor Protection System (RPS),

the~ reactor trip breaker (RTB), see Figure 1, failed to trip open when

its undervoltage trip attachment (UVTA) was actuated. The licensee

stopped the test being performed, and observed that the undervoltage (UV)

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armature was physically _ stuck in the energized condition. The licensee l

proceeded to.the next portion of the surveillance test, actuated the  !

shunt trip device of the RTB, and successfully tripped the RTB.

Therefore, although the RTB had failed to trip with the undervoltage j

condition, the breaker was operable using the shunt trip device. '

The licensee's design used General Electric (GE) AK-2-25 circuit breakers

as RTBs. This design consists of six RTBs which must operate in a i

one-out-of-two-taken-twice logic to remove power from the control rod

drive mechanisms (CRDMs) and release all control rods into the core.

There are two AC breakers and four DC breakers. AC breakers control all i

the- three phase primary power to the control rod drives; two DC breakers l

control the DC power to safety rod groups 1 through 4; and the other DC

breakers controls the DC power to safety rod groups 5 through 8. When

any 2-out-of-4 protective channels trip, all reactor trip module logics

trip, commanding all control rod drive breakers to trip. i

The RTB's utilized both a UVTA and a shunt trip device to trip.

. Automatic actuation of the shunt trip was added as a response to NRC

Generic Letter 83-28. A trip signal interrupts power to the UVTA and

simultaneously applied power to the shunt trip device. During a loss of

power or a low control voltage condition, the UVTAs would trip the RTBs.

The B&W design also utilized a silicon controlled rectifier (SCR) system

to diversely remove power from the CRDMs and cause the plant to scram.  ;

Power- to each of the regulating rod groups is provided through two '

separate sets of SCRs. This power may be interrupted by two separate

methods: (1) open the two upstream AC RTBs that supply holding power to ,

the rods via the SCRs; or (2) cut off the control power necessary for the l

SCRs to conduct holding power to the rods.  !

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On June 6,1985 the inspectors observed a bench check of the RTB that

failed. The licensee was able to trip the breaker several times using

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the UVTA; but it was noted that the trip paddle (see figure 1) appeared j

to be loose. The licensee was able to move the trip paddle over the l

armature and prevent the armature from moving out of the energized

position. This configuration appeared to have simulated the original

? failed condition of June 5, 1985, because the armature, could not engage .

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the trip paddle when the UVTA was deenergized, llowever, the shunt trip

was able to trip the breaker. The licensee then rotated the trip paddle

to its proper position and was able to trip the breaker using the UVTA.

The licensee's Management Safety Review Committee (MSRC) met the evening i

of June 7, 1985, and decided to functionally test all reactor trip

breakers in accordance with a special test procedure (STP-944) developed,

which incorporated the recommendations of GE Service Bulletin 25-014,

" Generic Preventative Maintenance and Surveillance Instructions for

General Electric AK-2/2-15/25 Reactor Trip Breakers Incorporating

Post-Salem Test and Operating Experience." The testing was performed by

the licensee and observed by representatives from B&W and the GE Service  !

Center in Atlanta, Georgia.

After successful completion of STP-944 it was determined that the

licensee had six operable RTBs and that the cause of the breaker failure

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' appeared to be an exce aive armature to rivet gap clearance. The

r armature to rivet gap was determined to be approxiaately .059' inches.

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~The specification range was .001 to .010 inches. The greater armature to

rivet gap has been shown to allow the trip paddle to move freely and

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b possibly interfere with the proper operation of the armature.

It appears to date that the excessive armature to rivet gap could have

been caused by vibrations of the breaker during transportation to and

from the GE and B&W facilities. ,

The licensee sent the six RTBS and one spare to the GE Service Center at

the commencement of the 1985 refueling outage. The breakers were sent in

response to NRC Generic Letter 83-28 for refurbishment. The breakers,

after completion of the refurbishment, were.sent to B&W to be certified

for seismic and electrical class IE qualifications and for 10 CFR 21

-considerations. The breakers returned to Rancho Seco and the first

functional testing performed was on June 5, 1985, the day of the failure.

The licensee's investigation into the underlying cause of the failure of

the UTVA was extensive. The failed RTB was quarantined and was not

altered, so the licensee was able to identify the probable cause of its

failure. The licensee's performance of STP-944 on the other six RTBs

provided the MSRC with sufficient information to declare the breakers

operable. The licensee also sent a member of their Quality Assurance

department to both the GE Service Center and B&W to observe RTB testing

and to reverify the work performed during breaker refurbishment.

The licensee identified that the GE Service Bulletin recommended the

measurement of the armature to rivet gap, but did not specify the proper ,

position of the armature when measured. ? The licensee discovered that GE

technicians'always measured this gap.with the armature in the energized

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position. .

The licensee'has incorporated.the guidance of the GE Service Bulletin

into their surveillance procedure for- the RTBs. Additionally it appears

that the failure mechanism, excessive armature to rivet gap, has been

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appropriately identified and the, corrective actions performed

s satisfactorily tested all RTBs

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'before the licensee began withdrawing

control rods.

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The licensee reported this event in Licensee Event Report (LER) Number

85-06. The inspector verified that reporting requirements had been met,

causes had been identified, corrective, actions appeared appropriate, and

. generic applicability had been considered. 'This LER is closed.

No violations or deviations were identified.

6. Nuclear Service Cooling Water Pump Breaker

The ' A' nuclear service cooling water (NSCW) pump breaker experienced

three trips during the period of June 11-13, 1985. The NSCW system

removes heat from the decay heat removal system.

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After each of the first two breaker trips, the breaker was tested, placed

, back into service, and successfully completed'its surveillance test. The

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results of tests performed did-not provide sufficient information on the

causes for the breaker's actuation.. On June 13, 1985, the licensee

replaced the breaker and initiated bench testing of it. The licensee had'

the vendor troubleshoot'the breaker; at the end of this report period the

vendor's investigation had not conclusively determined the cause of the

trips.

The licensee has appointed a failure investigation team consisting of

three electrical engineers to review this event.. Their investigation was

not completed at the end of this report period. Therefore, this item

remains open for future review of the team's findings (0 pen Item

-85-16-01).

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During the investigation of the NSCW pump breaker, the licensee

determined that, due to an earlier impeller modification, the pump motor

was drawing current slightly higher than the pump's original rating.

Although the licensee has determined this higher current not to be the

cause of the breaker's trips, a new overload unit setting has been made

for both the A and B train breakers.

No violations or deviations were identified.

7. Reactor Heatup, Startup, and Zero Power Physics Testing

After the ninety day refueling outage, plant heatup commenced on June 12,

1985 and the reactor was brought critical on June 14, 1985. Zero power

physics testing was performed and the plant was taken to 14 percent power

on June 18, 1985. On that date, the plant was shutdown and taken to' cold

shutdown conditions to repair a flow blockage problem in the main turbine

. lubricating oil system.

During this period, the inspectors observed portions of the control room'

activities including plant-heatup, deboration, and physics testing. The

operators were knowledgeable of the plant conditions and were following

applicable procedures.

No violations or deviations were identified.

8. Evaluation of Auxiliary Feedwater System

. Because of a June 9 event at the Davis-Besse facility involving the

auxiliary feedwater (AW) system, the licensee performed an evaluation of

the Rancho Seco AW system to ensure its operability. This evaluat. ion

involved'a review of the latest surveillance testing data, additional

stroke testing'of certain valves, refresher training of all operating

crews regarding a loss of feedwater event, and additional valve lineups

of the AW systems. Additionally, the licensee sent a represent 1tive to

Davis-Besse to obtain first hand information concerning their main

feedwater and AW systems and the events of June 9. The licensee

concluded that there were significant differences between the Rancho Seco

and Davis-Besse AW systems, making the Rancho Seco system much more

reliabic. The inspectors agreed with the licensee's conclusions. The

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'* . The following were the' major design' differences between tho's'ystems at - 1

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Eta'cho a Seco does not have dedicated main' steam isolation valves.

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Actuation of 'the Rancho' Seco main: steam line- break' (MSLB) logic ,

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- system, fas did the. Davis-Besse steam 'and 'feedwater rupture . control '

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JRancho Seco had two motor driven ~' auxiliary feed" pumps. one of Ohich. -

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also has a tanden" turbine drive.. Davis-Besse used two turbine. .'

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. Rancho Seco' operated'wiEh the.pressuriser electr$natic" relief valve

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On June 15 and'16, the inspectors. performed walkdowns;of the AFW system.-

Included in the walkdown wasta valve position check'for each valveu

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' ,- identified in the AFW system operating procedure A.51. . The inspectors +

determined that all, valves were positioned as required.1 The following i

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. Vent and drain valves FWS-135 and FWS-136'were not included'in the

' valve line-up. .These valves were located lietween two closed valves

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in the-test line between the AFW pumps and the condenser.. ,

A. pull box cover was missing on the heat tracing conduit.

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Calibration. stickers for two flow transmitters had the same- *

recalibration dates as the calibration dates.

• - No valve tag was attached to bypass valve FWS-562.'

These minor problems.were immediately corrected by the licensee. t

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'In~ addition to'the system walkdowns, the inspectors attended the operator  ;

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briefings and retraining on the AFW operation, reviewed recent AFW system

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surveillance test data, work requests and outstanding nonconformance

reports to ensure operational readiness.

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No violations or deviations were identified.

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9. Diesel Generator Control Circuit problen ,

After surveillance testing of diesel generator CEA, the bus unloading  ;

. system caused the diesel generator output breaker to cycle, with the

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system in the maintenance stop mode because an undervoltage condition  ;

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existed on 4160V Bus S4A2. Bus S4A2 was deenergized for maintenance

during this time.

To prevent the cycling in the future, in the event that an undervoltage

condition would exist during the time the engine was in the maintenance

> stop mode, the 'Licencee has modified the auto-start circuit for both GEA

and GEB diesel generator engine control circuits. Time delay dropout

relays were added in each auto-start circuit to allow the nor.nal shutdown

timer to time out, thus preventing the diesel generator breaker and bus

unloading system from cycling. The new Class IE relays were installed

within panels H2 DEA and H2 DEB. It is noted that this condition would

have been over-ridden if a safety features actuation signal would have

occurred.

The inspectota reviewed the engineering change notice (A-5730) associated

with this modification ind observed the installed new relays.

No violations or deviations were' identified.

10. Meetings with LRS Implementing Committee, MSRC, and SMUD Board of

Directors

During this reporting period, four significant meetings were held with

the licensee's manai nent.

On June l' *

resident inspectors and Region V management met

with the F ectors subcommittee responsible for implementing the

LRS reconune t . at Rancho Seco. The purpose of this meeting was to

discuss the , ugress and status of the implementation of the

recommendations. The NRC took advantage of this meeting to discuss the

need for continuing programs to ensure the recommendations are

implemented and then to evaluate the effectiveness of the implementation.

On July 3 and July 10, 1985, the resident inspectors and Region V

management attended MSRC meetings. The July 10 meeting was also attended

by representatives of I&E and NRR. The purpose of these meetings was to

discuss the vent pipe break event at Rancho Seco (which will be discussed.

In detail in inspection report 85-19) and other recent problems. The

licensee presented their evaluation of the recent events, corrective

action to ensure the problems are corrected, and long term corrective

action.

On July 18, 1985, Region V management and representatives from I&E and

NRR met with the SMUD Board of Directors to discuss the overall

performance of Rancho Seco. Comparisons of the licensee's present

performance with the performance a year ago were made. Areas coverd

were the licensee's concept of rising standards of excellence, technical '

adequacy, facing facts, respect for radiation, training, responsibility,

and capacity to learn from experience. The licensee was encouraged to

continue with the improving programs that have begun.

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_ ,- . The resident-inspectors' met with licensee representatives (denoted in s

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' paragraph 1)~at various times-during.the' reporting period ~and formally on <

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July;31,71985. The scope., and findings of the inspection activities as .

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. give6/in tthis report, were summarized at the meeting. Licensee

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representatives acknowledged the inspector's findings'. '

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