IR 05000267/1988026

Insp Rept 50-267/88-26 on 881017-21.No Violations or Deviations Noted.Major Areas Inspected:Failure of Emergency Diesel Generator Output Breakers to Automatically Close During 881011 Test & Routine Insp of Instrument Calibr

ML20206B900
Person / Time
Site:	Fort Saint Vrain
Issue date:	11/04/1988
From:	Stetka T, Wagner P NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
To:
Shared Package
ML20206B858	List: IR 05000267/1988026 ML20206B853
References
50-267-88-26, NUDOCS 8811160048
Download: ML20206B900 (11)

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APPENDIX U.S. NUCLEAR REGULATORY COM41SSION

REGION IV

NRC Inspection Report: 50-267/88 26 Operating License: OPR-34 Docket: 50-267 Licensee: Public Service Company of Colorado (PSC)

2420 W. 26th Avenue, Suite 15c  ;

Denver, Colorado 80211

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Facility Name: Fort St. Vrain (FSV)

Inspection At: FSV, Platteville, Colorsdo [

Inspection Conducted: October 17-21, 1988 Inspector: 6tu A //

C.CWasfer, Reactor Inspector, Plant Systems Dat'e gP[Sectior', Division of Reactor Safety rw & // //

Approved:/ iviYioY . fet fa,~ Chief, Plant Systems Section Date ,

of Reactor Safety  !

Inspection Sumary Inspection Conducted October 17-21, 1988 (Report 50-267/88-26) t Areas Inspected: Reactive, announced inspection of the failure of the

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emergcncy diesel generator output breakers to automatically close during an October 11, 1988, test and a routine inspection of the instrument calibration progra Results: Within the area inspected, no violations or deviations were i

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l l I i l 8011160048 PDR 891107 '

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O ADOCK 05000267 f PDC

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DETAILS Persons Contacted

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PSC l J. M. Williams, Licensing l C. H. Fuller, Manager, Nuclear Production l H. L. Brey, Manager, Nuclear Licensing and Resources

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R. Sargent, Assistant to the Vice President, Nuclear Operations R. Craun, Nuclear Engineering Manager R. W. Moler, Planning & Scheduling H. O'Hagan, Outage Manager l

M. Block, System Engineering Manager i

J. P. Hak, Supertindent *

' L. Gramling R. Sutton, SupervisorQuality Supervisor, Nuclear Licensing(QA Assurance -) Operators Auditing l

S. W. Chesnutt, Supervisor, Nuclear Licensing - Compliance M. H. Holmes, Nuclear Licensing Manager W. D. Rodgers, Nuclear Licensing and Resources D. W. Evans, Operations Manager J. K. Jackson, Supervisor QA/ Quality Control (QC)

M. J. Ferris, QA Operations Manager J. R. Reesy, Support Engineering Manager D. Warembouing, Manager, Nuclear Engineering R. A. Schenderlein, Special Projects These persons attended the exit interview on October 21, 1988. The NRC inspector also contacted other engineering, licensing, and craft personne . Emergency Diesel Generator Test (92700) System Design and Background The onsite AC power supply to the essential loads at the Fort S Vrain Nuclear Generating 3tation (FSV) is provided by emerger.cy diesel generator sets (EDG) 1A and 18. Each of the EDGs is driven by two diesel engines (diesel engines A and B on EOG 1A and diesel engines C and 0 on EDG 18), one mounted on each er.d of the 480V generator with the capability of being disconnected (declutched) from the generator. With both engines operating, the EDG is rated at 1210 kw; if one of the engines fails, the EDG can provide 605 kw to the bus. A simplified one-line diagram is provided in Figure 1, attache The NRC inspector reviewed the licensee's schematic diagrams related to the automatic operation of the onsite power i

supplies to evaluate system operation, Upon a loss of off-site power (LOSP), a start signal is provided to the engines of both EDG The 480V switchgear bus supply breakers I

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252TR1, 252TR2, and 252TR3 are tripped and loads are tripped off the 480VAC buse *

When either EDG 1A or 18 has started and its output voltage is enough to pick up) relay (XTR-92204 will be CR-9201 (EOGTimer energize A) orT1CR-9202 functions(EDG 1B), timer to provide a motor T1 1-second signal every 3 seconds, alternately, to relays CR-9203 (EDG 1A) and CR-9204 (EDG 1B). Should a failure of Timer T1 occu Timer T2 (XRT-92204-01) would be energized and provide the function to CR-9203 and CR-920 Relay CR-9203 (EOG 1A) or CR-9204 (EOG 10) would be energized when its associated generator had both of its diesels running and the  !

Timer T1, 1-second signal was present. The relay that was energized first (CR-9203 or CR-9204) would determine the generator that m uld supply power to two of the 480V buses; the other generator would supply (powerforonly relay TR-9202 EDGto1B itsor associated bus TR-9201 for EDG when 1A) the times1-second time delay out. Relays TR-9201 and TR-9202 are energized when the opposite EDG's output breaker closes and auxiliary relays close a contact as the result of a two out of three undervoltage condition. Should relay CR-9203 be energized first, a trip signal is sent to bus tie breaker 252BT32 (Bus 2 to Bus 3) and a close signal is sent to bus tie breaker 252BT12 (Bus 1 to Bus 2) and EDG 1A output breaker 252DGIA. The opposite action would occur if CR-9204 were energized first, breaker 252BT12 would receive a trip signal and breakers 252BT32 and 252DG1B would receive a close signa After a confirmation signal is received from both bus tie breakers that they have opened or closed in accordance wDb input signals from relays CR-9203 or CR-9204, either relay 286G1A or 286G1B respectively would be energized. Relay 286GIA (EDG 1A) or 286G1B (EDG 18), when energized, provides a signal to programmer IA and programer 18 deenergizes the T1 timer motor, and locks out the opposite 286 relay. Relays 286G1A and 236G1B a N hand reset (GE type HEA61) and

!. remain in set position after the inpr signal is remove If rela and 2)willy 286GIA sequenceisonenergized, programmer loads connected to 480V Bus IANo(Sequence I and A, Drums 1 programmer IB (Sequence B Drum 1 and 2) will sequence on loads connected to 480V Bus 3. If relay 286G1B is energized, programer IB

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(Sequence A, Drums 1 and 2) will sequence on loads connected to Bus 3 and programer IA (Sequence B, Drums 1 and 2) will sequence on loads connected to Bus Programers 1A and IB will run for 100 seconds, sequencing on the loads as required. After loads are sequenced on, the EOGs continue to supply the necessary electric power for essential equipmen An internal licensee evaluation (EE-92-0008) stated that no loads

were automatically sequenced onto Bus 2, however, the FRC inspector's

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review disclosed some inconsistencies between the licensee's evaluation, the FSAR, and the electrical drawings with regard to this Bus 2 lo:d sequencing. The licensee agreed to evaluate the apparent inconsistencies and correct the appropriate documents. This is considered 1.o be an unresolved item pending clarification of the i nconsistencie Unresolveditem(267/8826-01): Evaluate inconsistencies between plant drawings and the FSAR to determine whether loads are sequenced onto EDG Bus In compliance with FSV Technical Specification SR 5.6.le, "Standby Diesel Generator Surveillance," the licensee performs a simulated loss of off-site power (LOSP) and turbine trip test at least once each refueling cycle to provide assurance of proper system operatio The test is performes' in accordance with Procedure SR 5.6.la-1.5Y dated March 9, 1988. .'he procedure contains provisions for ensuring that where circuitry is duplicated, the dupitcate circuits are both tested for proper functioning, i.e., automatic power transfer to the 480V Bus 2 and proper load sequencing based on the first available ED In order to test these duplicated circuits, one set of circuitry is inhibited, the test is run and the circuitry is restored. Ther1 the other duplicated circuits are inhibited, the test run again, and ali circuits are restored to norma During an LOSP test on October 11, 1988 EDG IB duplicated functions were inhibited in accordance with SR 5.6.le-1.5Y. When offsite power was removed from the feeders to the 480V bus, the feeder breakers (252TR1, 252TR2, and 252TR3) opened, and normal load shedding occurre Both EDGs (all four engines) started and came up to rated speed and voltage within specification; however, neither EDG output breaker (252DG1A or 252DG1B) closed to energize the 480V buses. The bus tie breaker (252BT12) did close as expecte The control room operator attempts to restore normal (offsite) power to the 480V essential buses were unsuccessful. The EDG output breakers were plcced in "pull-to-lock" to inhibit them from closing, and tne functions which had been inhibited were restored. The restcration of offsite power could still not be accomplished. The EDG output breakers were then released frora "pull-to-lock" and both, closed, thereby energizing the buses as wa: expected to occur initially during the tes Power was subsequently transferred back to the offsite source without problem, Evaluatic/:

The NRC inspector discussed the sequence of events and the followup actions with licensee personnel involved. As the result of these discussions, the NRC inspector determined that the licensee had already addressed the areas of concern. The NRC inspector corrpared the SR 5.6.le-1.5Y requirements to the detailed schematic drawings to

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determine if such items as incorrect initial positions of switches or circuit breakers, failures of relay, switch or breaker contacts, and changes to the circuitry design could have resulted in the conditions which were observed during the October 11, 1988 tes None of these conditions were detennined to be a verifiable cause of the test failur The licensee had reverified that the initial conditions were apparently correct through reviews and personnel interviews. The licensee had also physically checked the involved relays, switches, and circuit breakers. Although no failures or problems were identified, the licen:ee decided that a prudent action would be to replace the relay contacts on relay CR-9302. The NRC inspector examined the replaced contacts and although not in a new condition, found them to be acceptable. Since no verifiable cause for the malfunction could be determined, the licensee decided to reperform the test. The licensee decided that this reperformance would utilize more personnel as observers than the number required by the procedure and would include additional monitoring instrumentation. The necessary procedural changes to accomplish this additional monitoring were incorporated in accordance with license requirement The NRC inspector observed the performance of the second LOSP test on October 18, 1988, from the control room. The NRC inspector verified the control room initial conditions (switch and circuit breaker positions) prior to the test, observed proper implementation of the test requirements, and proper operation of the equipment. When offsite power was removed by opening the transfonner output breaker, all AC power was lost, the 480V bus feeder breakers opened, loads were shed, and both EDGs started and came on-line to power the 480V essential buses (EDG 1A powered Bus 2 through Tie Breaker 252TB12 as expected). After verification from the observers that all equipment had functioned and that all 10 data sheets had been properly completed, conditions were restored to normal and preparations for conducting Part 2 of SR 5.6.le-1.5Y were made. (Part 2 requires that EDG 1A functions be inhibited to ensure that the EDG 1B circuitry is functioning properly.) Part 2 of the test was then run with acceptable results. Fnilowing the completion of the test, the data sheets were all colle # d and any unusual observations were documented for evaluation by the engineering organizatio The NRC inspector observed that the test was conducted in a coordinated, careful, and professional manne The NRC inspector met with licensee personnel on October 19, 1988, to discuss the results of the test. The NRC inspector was informed that the only abnormality noted du'ing the test was the closure of the appropriate bus tie circu't breaker (due to an undervoltage signal)

prior to closure of the diesel generator output circuit breake (The timing was considered to be less than 1 second.) The licensee did not consider this to be a concern but was planning to evaluate

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the situation more thoroughly to determine if this undervoltage closure should be disable The NRC inspector queried the licensee about the pcssibility of closing both bus tie breakers at the same time. In addition, the NRC inspector reviewed the schematic diagrams to evaluate the possibilities. The drawings show that an interlock prevents automatic closure of cne bus tie breaker if the other is closed. In the case where both bus tie breakers are open, and both receive a close signal, additionti provisions are present: (1) for an undervoltage condition on Bus 2, a selector switch (HS-92346) must be in either the Bus 1 position to clo p 252BT12 or Bus 3 for 252BT32; and (2) for automatic closurst during an LOSP, relay CR-9203 provides the close signal to 252BT12 and a tr

additional changes continue to be considered. t (5) LER 87-003 I  ! l An inadveru , load shedding of Buses 2 and 3 during relay  ; testing caused ED6 IB to receive a start signal. EDG 1A was out  : of service. Diesel engine C (a part of EDG 1B) however, failed l ! < l I , - - - - - - . - - _ - - , , . . . , . - _ , - _ _ _ _ _ . . . . _ _ _ , . _ _ . __-._____,_____y _ _ . - - _ _ _ . _ . _ _ _ . . . _ _ _ . - _ _ _ , . , _ _ , _ - . _ _ _ _ _ _ _-.

, . , to start and no i trifiable cause was found. Subseo,uently, the engine was serviced and tested satisfactoril (6) LER 87-025 An unintentional trip of offsite power caused the EDGs to start and power the essential buses without inciden (7) LER 87-028 A similar trip of offsite power caused the EDG to actuate and power the essential buses as designe All of the above LER events occurred during periods of reactor shutdown and posed no reactor safety hazard. The NRC inspector determined that the above events were not causally linked to the malfunction on October 11, 1988, Conclusion Based on the licensee's evaluation and inspection of possible causes of the initial malfunction and the successful completion of the LOSP test on October 18, 1988, the NRC inspector concluded that the emergency power system could be considered operable. The NRC inspector determined that additional operator guidance on manual operations involving the EDGs was needed, and while the Operations Order was acceptable for the interim, the need for procedure revisions to be an open item as identified in paragraph 2.b of this repor No violations or deviations were identifie . Instrumentation Calibration (56700) Since the licensee was perfonning maintenance on safety-related instrumentation, the NRC inspector observed an instrument c?libratio The calibration of differential pressure transmitter PDT 21545 for circulator 1A Buffer - Midbuffer, was conductei on October 20, 1988, in accordance with Procedure RP-EQ-15 "Calibration and Maintenance of Foxboro N-E13DM Differential Pressure Transmitters in Non Level Applications," Issue 3, dated November 19, 1987. The replacement testing and calibration of PDT 21545 was specified in Station Service Request 88502230, which had been approved on August 6, 198 The NRC inspector reviewed RP-EQ-15 and the Companion Surveillance Procedure SR 5.4.1.3.6c-R1, "A Circulator Seal Malfunction Calibration." The procedures both contained detailed step-by-step instruction The above procedures contained spaces for the technician to initial and date each step and for a Quality Control (OC) inspector to initial and date those steps of a more critical nature. During the calibration, the _ _ - -

, . . NRC inspector observed that the steps were properly initialed when completed and that all data was properly entered. The data taken (as-found values) during the calibration was all within the allowable limits and no adjustments were made. The NRC inspector also verified that the tools and instruments (torque wrench, voltmeter, pressure measuring device, etc.) were in calibration and noted that the technicians and QC inspector also verified the calibration date The NRC inspector observed that the techniciem rechecked the valve lineup and cleaned the area prior to departing. The NRC inspector had no questions related to the completion of this calibration. ' The NRC inspector also reviewed the records for the calibration of five engineered safety features instruments. The calibrations were perfonned in accordance with the following procedures: SR 5.4.1.2.6.c-R, "Reheat Heater Activity Calibration " Issue 24 dated December 7, 1984, was performed from September 14-16, 1988 . SR 5.4.1.2.7.d-R, "Superheater Heater Temperature Calibration," l Issue 18 dated March 7, 1987, was performed from March 28-30, 1988 l SR 5.4.1.1.6.c-R, "Primary Coolant Moisture Scram Calibration," ' Issue 29 dated March 15, 1985, was performed from March 9 through April 3, 1987 l SR 5.4.1.1.9.c-R, "Primary Coolant Pressure Scram Calibration," Issue 26 dated March 29, 1987, was perfomed from March 30 through April 2, 1987 SR 5.4.1.1.4.d-R, "Linear Power Range Channel Calibration," Issue 22 dated August 9, 1985, was performed from April 3-8, 1987 The NRC inspector's questions related to the completion of these procedures, i.e., signatures and initials for steps and QC witness points, were answered satisfactorily by licensee personnel. The NRC inspector also questioned procedure updating and reviews and noted that there were what appeared to be an excessive number of procedure deviation reports (PDRs) on temporary procedure changes. The NRC inspector was informed that these issues had been the subject of an earlier NRC violation (50-267/8814-01). The licensee responded to this violation by letter dated October 10, 1988, and discussed the surveillance procedure rewrite program which is presently undemay. Based on this response, the NRC inspector had no further questions for this inspectio No violations or deviations were identifie ___- _ _ _ _ _ - _ _ _ _ _ _ _ _ _ - _ _ _ _ ._ _ _ _ _ _ _ _ _ _ _ _ _ _ - _ - _ _ _ _ _ . .__ _______ ____ __ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ - - _ _ _ _ _ _ - ' . ' . . 10 Exit Interview The inspection scope and findings were summarized with those individuals identified in paragraph 1. The information provided to and reviewed by the NRC inspector was not identified as proprietary by the license r ! [ . k L f

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( 4 > u ' Orr sles PowtR statsu A [s.9304) (N-9210) (N*83810 JL i l I I 480VAC '2S2TR1 SWOR NO. 1 400VAC 252TR2 400VAC 252TR3 < - - 1, SWOR HO. 2 , SWOR 'WO. 2 (W-9213) i 252DG1A i -2525712 ...,212, i i , 0 DIESEL ' w OENERATOR DIESEL G g NO. 1A GtWERATOR w NO. 18 (Engine 1A s tal D _ (Engine 1C s 1D) _ s!NrLTPIED ONR-LTNE DIAGRAN OF BREARh2 LINE-DP FIGURE 1 ! r i . L