|
|
| Line 1: |
Line 1: |
| {{Adams | | {{Adams |
| | number = ML20149G638 | | | number = ML20199K148 |
| | issue date = 07/17/1997 | | | issue date = 11/26/1997 |
| | title = Insp Rept 50-295/97-12 on 970311-0425.Violations Noted.Major Areas Inspected:Operations,Maint & Engineering Associated W/Unit 1 Loss of Offsite Power Event That Occurred on 970311 | | | title = Ack Receipt of 970818,0915 & 29 Ltrs Informing NRC of Steps Taken to Correct Violations Noted in Insp Repts 50-295/97-12 50-295/97-13,50-304/97-13,50-295/97-16 & 50-304/97-16 Issued on 970717,0815 & 28.No Further Questions |
| | author name = | | | author name = Vegel A |
| | author affiliation = NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) | | | author affiliation = NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| | addressee name = | | | addressee name = Brons J |
| | addressee affiliation = | | | addressee affiliation = COMMONWEALTH EDISON CO. |
| | docket = 05000295 | | | docket = 05000295, 05000304 |
| | license number = | | | license number = |
| | contact person = | | | contact person = |
| | document report number = 50-295-97-12, NUDOCS 9707230382 | | | document report number = 50-295-97-12, 50-295-97-13, 50-295-97-16, 50-304-97-13, 50-304-97-16, NUDOCS 9712010028 |
| | package number = ML20149G625
| | | document type = CORRESPONDENCE-LETTERS, OUTGOING CORRESPONDENCE |
| | document type = INSPECTION REPORT, NRC-GENERATED, TEXT-INSPECTION & AUDIT & I&E CIRCULARS | | | page count = 2 |
| | page count = 19 | |
| }} | | }} |
|
| |
|
| Line 19: |
Line 18: |
|
| |
|
| =Text= | | =Text= |
| {{#Wiki_filter:[ | | {{#Wiki_filter:. - - . . _ . - - . - |
| '
| | R / ilk November 26, 1997 i |
| . .
| | . s |
| ,
| |
| U.S. NUCLEAR REGULATORY COMMISSION REGION lli
| |
| .
| |
| Docket No: 50-295 License No: DPR-39 Report No: 50-295/97-12 Licensee: Commonwealth Edison Company Facility: Zion Nuclear Plant, Unit 1 Location: 101 Shiloh Boulevard Zion, IL 60099 Dates: March 11 through April 25,1997 Inspectors: E. W. Cobey, Resident inspector D. R. Calhoun, Resident inspector A Vegel, Senior Resident inspector
| |
| . | | . |
| Approved by: Michael E. Parker, Acting Chief Reactor Projects Branch 2
| | Mr. E |
| !
| | ' |
| j.
| | Site Vice President Zion Station Commonwealth Edison Company ; |
| | | 101 Shiloh Boulevard , |
| i
| | Zion. IL 60099 SUBJECT: NOTICE OF VIOLATION (NRC INSPECTION REPORTS NO. 50 295/97012(DRP) 50 295/97013(DRP),50 304/97013(DRP); and 50 295/97016(DRP); 50 304/97016(DRP)) |
| ' | |
| , ,
| |
| ! !
| |
| l 9707230382 970'717 PDR G ADOCK 05000295 )
| |
| - | |
| PDR !
| |
| ._. _-
| |
| '
| |
|
| |
|
| __
| | ==Dear Mr. Brons:== |
| . .
| | This will acknowledge receipt of your letters dated August 18, September 15, and September 29,1997, in response to our letters dated July 17. August 15, and August 28,1997, transmitting Notices of Violation associated with Inspection Reports No. 50 295/97012(DRP); |
| EXECUTIVE SUMMARY Zion Nuclear Plant, Unit 1 NRC Inspection Reports 50-295/97-12 Thit special inspection included aspects of licensee operations, maintenance, and engineering associated with the Unit 1 loss of offsite power event that occurred on March 11,199 Ooerations
| | 50-295/97013(DRP),50-304/97013(DRP); and 50-295/97016(DRP),50-304/97016(DRP) We have reviewed your corrective actions and have no further questions at this time. These corrective actions will be examined during future inspections. |
| -
| |
| Although the licensee satisfactorily recovered from the event with no actual consequences to the public health and safety, some deficiencies in the licensee's
| |
| ,
| |
| performance unnecessarily hampered and slowed the licensee's response to the
| |
| ; evcnt. These performance issues involved inconsistent communication and coordination between departments, inefficient work planning, plant equipment and operating procedure problems, and insufficient control of operability assessment '
| |
| (Section 01.1)
| |
| -
| |
| Licensee management's discretionary activation of the Technical Support Center, pre-evolu' tion walkdowns of procedures, and the licensee's increased emphasis .
| |
| placed on exhibiting a questioning attitude and performing activities in a controlled l manner demonstrated a conservative operating philosophy focused on safet (Sections 01.1 and 03.1)
| |
| -
| |
| Inconsistent quality of pre-evolution walkdowns of operating procedures and several deficient operations procedures contributed to the delay in restoring offsite powe A violation involved the failure to have an existing procedure for responding to a loss of offsite power event. (Section 03.1)
| |
| The Independent Safety Engineering Group (ISEG) performed a thorough review of
| |
| -
| |
| the Unit 1 loss of offsite power event; however, the inspectors identified that licensee management did not initiate action to address the issues or recommendations of the associated ISEG report in a timely manner. (Section 07.1)
| |
| Maintenance
| |
| -
| |
| The emergency diesel generators successfully started on demand and provided the required electrical power to the Unit 1 engineered safety feature loads: however, the inspectors also concluded that numerous material condition problems extended the recovery time frorn the event by diverting resources and licensee management focus to resolve the issues. (Section M2.1)
| |
| -
| |
| The inspectors identified a violation involving the failure to implement timely and effective corrective actions to prevent the recurrence of malfunctions of sequence timers that control engineered safety feature bus loading. (Section M2.1)
| |
|
| |
|
| . . . . | | Sincerely, |
| . | | /s/ Anton Vegel Anton Vogel, Acting Chief Reactor Projects Branch 2 Docket No. 50 295 Docket No. 50 304 Gee Attached Distribution DOCUMENT NAME: G: ZION \ZIO97012.TKU To receive a copy of this document, indicate in the box "C" = Copy without attach /enci "E" = Copy with attach /enci "N" = No copy OFFICE Rlli , |
| Enaineerinn
| | G NAME Vogellet h - |
| - | | DATE 11/$ f /97 OFFICIAL RECORD COPY l |
| The inspectors identified that the periodic testing of a nonsafety-related sudden pressure relay for the system auxiliary transformer did not demonstrate that the I relay was within calibration and placed the plant at an increased' risk of a spurious loss of offsite power. (Section E2.1)
| | fod"188EIEsdaes l G PDR ,. , |
| | kh (__m - _ . . , . , . , . . . _ -_ ,, ,_ |
|
| |
|
| !
| | _ _ . _ _ _ _ _ _ . _ |
| -
| | .. cc: O. Kingsley, Nuclear Generation Group President and Chief Nuclear Officer M. Wallace, Senior Vice President, Corporate Services H. G. Stanley,' %6 President PWR Operati. t Usison Officer, i:00 800 D. A. Sager, Vice President, Generat6on Support D. Ferrar, Nuclear Regulatory Services Manager 1. Johnson, Uconsing Operations Manager Document Control Desk Ucensing R. Starkey, Plant General Manager R. Godley, Regulatory Assurance Supervisor Richard Hubbard Nathan Schloss, Economist Office of the Attomey General Mayor, City of Zion State Walson Officer State Liaison Officer, Wisconsin Chairman, Illinois Commerce Commission |
| The inspectors identified that between February 27 and March 5,1997, due to l operations management not having ownership of operability assessments, the l operating shift was unaware of the requirements imposed by the operability !
| |
| assessment for emergency diesel generator cylinder liner cracking. (Section E2.2) l
| |
| | |
| -
| |
| Poor commur'ication and documentation of the basis and the compensatory actions l
| |
| required to support thB operability assessment for emergency diesel generator l cylinder liner cracking, unnecessarily complicated the recovery plans and resulted in delays in the restoration of offsite power. (Section E2.2)
| |
| | |
| 3
| |
| | |
| ~ _ _ _ . - _ _ . _ ~ ~ . . - - .. __ .~ _ _ _ _ _ _ . _ . _ _ _ - . . _ _ . _ _ . _
| |
| l
| |
| .
| |
| l .
| |
| l l
| |
| !
| |
| !
| |
| Report Details
| |
| ; - 1. Operations 01 Conduct of Operations l
| |
| 01.1 Loss of Offsite Power to Unit 1 l Insoection Scooe (93702 and 71707)
| |
| >
| |
| , | |
| ' | | ' |
| On March 11,1997, Unit 1 experienced a loss of offsite power. As a result, the '
| | Distribution: ' |
| inspectors responde~d to the site and observed licensee activities throughout the event recovery, in addition, the inspectors performed a follow-up inspection into the circumstances surrounding the event which included evaluating the licensee's root cause investigation, interviewing licensee personnel, and reviewing applicable procedures and documentatio Observations and Findinas Secuence of events Initial Conditions:
| | Docket File DRP OC/LFDCB TSS PUBUC IE-01 DRS (2) |
| Unit 1 -- Cold Shutdown, depressurized with offsite power via the Unit 1 system auxiliary transformer Unit 2 -- Cold Shutdown, depre:,surized with offsite power via the Unit 2 system auxiliary transformer i h1 arch 11,1992 1553 A loss of offsite power occurred on Unit 1 as a result of the isolation of the system auxiliary transformer (SAT) due to a sudden pressure trip. The Unit 1 SAT deluge activated and the 1 A,18, and O emergency diesel generators (EDGs) started and energized their respective buses as designe Operators entered abnormal operating procedure (AOP) 6.3, " Loss of RHR
| | A. Beach RlllPRR Deputy RA RACi (E-Mail) |
| [ Residual Heat Removal] Shutdown Cooling." The commercial phone system was los Operators restarted the 1B RHR pump to re-establish shutdown cooling in accordance with AOP- Upon restoration of shutdown cooling, operators exited AOP-6.3. | | Rlli Enf. Coord. CAA1 (E Mail) |
| | | SRI Zion DOCDESK (E Mail) |
| L i
| | Project Mgr., NRR |
| 1618 The licensee declared an Unusual Event in accordance with Emergency
| |
| : Action Level MU-1 (offsite power being unavailable for greater than l 15 minutes).
| |
| :
| |
| ; 4
| |
| :
| |
| I i
| |
| | |
| . . - . .- - . - . . . = - .. ..
| |
| ~.,
| |
| -
| |
| -
| |
| . l l
| |
| !
| |
| 1640 The licensee completed the initial emergency notification system (ENS)
| |
| i report for the declaration of an Unusual Even l Operators restored spent fuel pool coolin Control room personnel requested that the Technical Support Center (TSC) .
| |
| be activated to assist in restoration activities from the loss of offsite powe I The licensee's intent was to power each engineered safety feature (ESF) bus from its reserve feed on the other unit versus the present power sources from each respective ED l 1730 Operators energized bus 147 from its reserve feed (Unit 2 SAT)in accordance with Emergency Support Procedure (ESP) 6.2, " Energize 4KV j ESF Buses from Reserve Feed" and secured the O EDG.
| |
| | |
| l 1806 The OB instrument air (!A) compressor tripped on high temperatur I Operators entered AOP-3.3, " Loss of Instrument Air."
| |
| | |
| l 1813 Operators restarted the OB IA compressor and exited AOP- The commercial phone system was restore The licensee conducted a follow-up ENS report to update the NRC of the current plant status and prioritie The TSC personnel assumed command and control of the even '
| |
| March 12.1997 0200 Operators completed system operating instruction (SOI) 63BB, "Deenergizing 4KV Non-ESF Buses," in preparation for performing SOI 63A, "345KV Operations," Section 5.8, "Deenergizing the 345KV System Auxiliary Transformer." The licensee isolated the SAT so that the ring bus could be restore Operators attempted to close breaker OCB-67 to restore the ring bus in accordance with SOI-63A; however, the breaker would not close since the 86 relay and the 142 lock out relay were in a tripped conditio Operators reset the 86 relay and the 142 lock out rela Operators restored the ring bus in accordance with sol-63 The licensee conducted a follow-up ENS report to update the NRC of the current plant status and prioritie Operators shifted loads ; @ ration for the transfer of bus 149 to reserve feed in accordance with - '
| |
| F, " Transferring 4KV ESS [ Engineered i
| |
| !
| |
| | |
| i t - - . -- _ - . , . - . , - - --,
| |
| | |
| . .
| |
| Safeguards System] Buses from D/G [ Emergency Diesel Generator) to Reserve Feed with Unit Trip and System Auxiliary Transformer Trip."
| |
| | |
| 0955 Operators identified a needed procedural change to sol-63F regarding the '
| |
| battery charger feed breaker positio Operators placed the transfer of bus 149 to reserve feed on hold, pending the resolution of questions regarding the maximum current rating of the Unit 2 SAT.Z winding power feed cabling and the resolution of seal oil system problem Operators backed out of sol-63 .
| |
| 1130 Design engineering personnel set a current limit of 1200 amps on the Unit 2 SAT to ESF buses on Unit On the recommendation of the Plant Operations Review Committee (PORC).
| |
| | |
| TSC personnel d..ected that the ESF buses remain powered by their respective EDG rather than transfer the buses to reserve feed until the sta*us of the Unit 1 SAT repairs could be determined (expected in approximately seven hours).
| |
| | |
| March 13,1997 0350 The licensee conducted a follow up ENS report to update the NRC of the current plant status and prioritie .1700 System engineering personnelidentified that the bus 147 division 17-2 safe shutdown timer was not fully rese Maintenance personnel replaced the SAT sudden pressure rela March 14.1997 0420 The licensee conducted a follow up ENS report to update the NRC of the current plant status and prioritie Operators energized the Unit 1 SAT in accordance with SOI-63 Operators energized all 4KV non-ESF buses (bus 142,143,144, and 145) in accordance with SOI-638, " Energizing 4KV Non-ESF Buses from the SAT."
| |
| | |
| 1154 While operators attempted to energize bus 135 in accordance with SOI-63H,
| |
| "480V Non-ESF Bus Operations," breaker 1351 did not clos Operators energized bus 132 in accordance with sol-63 .
| |
| l .
| |
| ,
| |
| l 1340 Operators energized bus 133 in accordance with sol-63H; however, the l phase voltages on bus 133 were not within 10 volts as require Operators opened bus 133 feed breaker in accordance with SOI-63H due to the phase t/oltage differenc Operators ener0 ized bus 134 in accordance with SOI-63 Operators secured reserve feed and energized bus 147 from normal fee Operators reset the division 17-2 safe shutdown time l l
| |
| 1832 Operators closed the main feed breaker to bus 148 in accordance with sol- l 63E (bus 148 powered from normal feed and the 1 A EDG). ~
| |
| l l
| |
| 2214 Operators unloaded the 1 A EDG and opened the output breake I 2354 Operators closed the main feed breaker to bus 149 in accordance with SOI-63E (bus 149 powered from normal feed and the 1B EDG). 1
| |
| [Aarch 15.1997 0021 All ESF buses were being powered from normal feed and the licensee terminated the Unusual Even The licensee completed the ENS report for the termination of the Unusual Even Operators energized bus 135 in accordance with SOI 63 The licensee transferred command and control to the control roo Operators unloadt.d the 1B EDG and opened the output breake Operators energized bus 133 in accordance with sol-63H. Electrical maintenance personnel verified that the phase to phase voltage difference was less than 10 volts. The licensee initiated an action request to calibrate the control room indicatio The licensee assigned all restoration items for completion and suspended TSC operatio Evaluation of Licensee's Event Resoonse The inspectors observed licensee event response activities in the control room,
| |
| , TSC, and the plant, talked with involved licensee personnel, and attended related i licensee meetings. Through the observation of licensee interactions and activities over the course of the event, the inspectors arrived at various insights regarding the quality and timeliness of the licensee's event response. Although the licensee
| |
| | |
| .- - . .- ...~ - - . - .. -. . -- . . - - - - - - - - - - - . . -
| |
| l' . .
| |
| -
| |
| L l
| |
| l l
| |
| satisfactorily recovered from the event with no actual consequences to the public health and safety, some deficiencies in the licensee's performance unnecessarily hampered and slowed the licensee's response to the even *
| |
| Communication and coordination between departments was inconsistent, '
| |
| For example, inspectors observed mis-communication regarding the status of safe shutdown timers, operator confusion regarding engineering guidance on loading the EDGs, differing licensee interpretations of the licensee's EDG operability assessment, and a security guard unnecessarily slowing the shif t engineer's access to a vital switchgear roo ,
| |
| '
| |
| -
| |
| The licensee's work planning process did not always ensure recovery work was accomplished in an expeditious manner. For example, inspectors observed that pertinent parties were unaware that needed personnel would not be available to support SAT maintenance activities when planne Slow recovery from the event can be partially attributed to the licensee's increased emphasis on demonstrating a questioning attitude and performing activities in a controlled manner. Related inspector observations and the licensee's discretionary activation of the TSC to remove the burden of managing restoration activities from control room personnelindicated strong licensee management support for a
| |
| . conservative operating philosophy focused on safety. However, the organizational !
| |
| and process problems noted above further extended event recovery tim Conclusions The inspectors concluded that the licensee's response to the event demonstrated clear licensee management efforts to encourage a safe and controlled approach to plant operations. However, the inspectors also concluded that the recovery time of offsite power was extended, unnecessarily increasing the timeframe during which the plant was at increased risk,- due to:. (1) various organization and process problems (noted above): (2) several operations procedures needing revision prior to use (see Section 03.1); (3) numerous equipment issues diverting licensee efforts from recovery of offsite power (see Section M2.1); and (4) confusion regarding the basis for the conclusions and the compensatory actions specified in the EDG operability assessment on cylinder liner cracking (see Section E2.2).
| |
| | |
| 03 Operations Procedures and Documentation
| |
| . 03.1 Ooerations Procedures '
| |
| a,- Insoection Scooe (71707)
| |
| L The inspectors interviewed licensee personnel and reviewed selected procedures utilized during recovery from the loss of offsite power event.
| |
| | |
| !
| |
| | |
| t
| |
| | |
| - y-- 3 -,, , r, - -
| |
| .v,, -
| |
| r -
| |
| | |
| .. -- - -- - - . - - .- - .- .- ---- .- - -
| |
| l
| |
| -
| |
| .
| |
| - Observations and Findinas As a result of the increased focus on conservative operations, which had been prompted by the reactivity management event on February 21,1997, the licensee .
| |
| -
| |
| had been reviewing and performing walkdowns of all operating procedures prior to their performance except under emergency conditions. The licensee also implemented this practice during the loss of offsite power for procedures used in responding to the event. Consequently, the licensee revised four procedures l
| |
| (SOI-63A, "345KV Operations:" sol-63B, " Energizing 4KV Non-ESF buses from the SAT;" SOI-63D, " Transferring 4KV ESS Buses from Reserve Feed to Normal Feed;"
| |
| i and SOI-63E, " Transferring 4KV ESS Buses from D/G to Normal Feed") to incorporate procedural enhancements that the shift determined were necessary prior to the performance of the respective evolution. In addition, the licensee
| |
| ;
| |
| identified that SOI-11K, " Transfer of Fuel Oil from Tanker Truck to Fuel Oil Storage l Tanks," Section 5.3, " Filling Heating Steam Boiler Fuel Oil Storage Tank Using Tanker Truck Fuel Oil Transfer Pump," could not be performed as written without resulting in a fuel oil spill. The licensee also revised this procedur Even though the licensee was performing pre-evolution walkdowns of procedures, the licensee did n6t identify needed procedural enhancements to SOI-63F,
| |
| " Transferring 4KV ESS Buses from D/G to Reserve Feed with Unit Trip and System Auxiliary Transformer Trip," until the procedure was actually being performed. A delay la performing the evolution resulted while the procedural concerns were being resolved. The licensee concluded that this oversight was apparently due to an
| |
| ;
| |
| !
| |
| operator's lack of understanding of licensee management's expectation for walking down procedures prior to implementation. The operator responsible for walking down the procedure had reviewed it versus actually walking it down, which
| |
| ! contributed to the failure to identify the discrepancies.
| |
| | |
| !
| |
| Prior to the performance of SOI-63F, " Transferring 4KV ESS Buses from D/G to Reserve Feed with Unit Trip and System Auxiliary Transformer Trip," engineering personnel recognized that an open item existed from the validation of the Auxiliary Power Design Basis Document in April 1996. The open item addressed the current limit on the Z winding which could allow the cross-tie power feed cables to exceed l their ampacity limit. Specifically, ESP-6.2, " Energize 4KV ESF Buses from Reserve l
| |
| Feed," contained a caution statement which stated: "Do NOT exceed 1800 amps on Z winding of the System Auxiliary Transformer when loading buses that are energized from reserve feed." However, this limit was not sufficient to prevent the ampacity limit for the cross-tie power feed cables from being exceeded, as sol 63F l did not contain any guidance on the ampacity limits of the cross-tie power feed
| |
| ;
| |
| '
| |
| cables for the Z winding. As a result, the licensee delayed the performance of sol-63F pending the resolution of this issue. Subsequently, the licensee specified a
| |
| , conservative administrative current limit on the Z winding of 1200 amps. On i
| |
| March 21,1997, design engineering personnel determined that the allowable current limit on the Z winding of the SAT was 1250 amps when cross tied to the opposite unit.
| |
| | |
| ,
| |
| | |
| f l
| |
| | |
| _ - . _ . _ _ _ _._ _ _ _ _ _ - . - _ _ . _ _ _ . . _ . _ _ _ . _ . - _ _ . , _
| |
| . <
| |
| .
| |
| l In addition, the licensee identified that no procedural guidance existed for
| |
| . responding to a loss of offsite power event. Although portions of existing | |
| ; procedures covered various operating evolutions conducted during the event, no
| |
| | |
| integrated procedure existed to delineate overall strategies in responding to the
| |
| !
| |
| !
| |
| event. ' As a result, the licensee initiated two problem identification forms, 97-1374 and 971386, to address this issue. At the end of the inspection period, the licensee's investigation was stillin progres Conclusions l
| |
| The inspectors concluded that the increased emphasis placed on reviewing the adequacy of procedures prior to their use was conservative. However, the inspectors also concluded that inconsistent quality of the pre-evolution walkdowns ,
| |
| of operations procedures and required procedure revisions contributed to the extensive time required for restoration of offsite powe The failure to have an existing procedure for responding to a loss of offsite power event is considered a violation of Technical Specification 6.2. (50-295/97012-01), as described in the attached Notice of Violatio L 07 Quality Assurance in Operations 07.1 Site Quality Verification (SOV) Oversicht Subsequent to the recovery of offsite power to Unit 1, the independent Safety ]
| |
| Engineering Group (ISEG) performed an independent review into the event (OVL 22-97-026). This evaluation was thorough and contained several pertinent issues and recommendations. The ISEG review was completed on March 24,1997,and distributed to senior licensee management for comment. - However, as of April 28,1997, no response had been received by the ISEG, and the ISEG had not
| |
| ; yet initiated any additional action. The inspectors concluded that the licensee's response to the evaluation did not appear timely.
| |
| | |
| ..
| |
| 08 Miscellaneous Operations issues 08.1 (Closed) LER 50-295/97007: System auxiliary transformer trip caused by spurious operation of the sudden pressure relay with minimalimpact to the plant. This issue is the subject of this inspection report. No new information was provided in the LER. The LER is closed.
| |
| | |
| l
| |
| | |
| l
| |
| !.
| |
| >
| |
| I
| |
| !.
| |
| I
| |
| | |
| l l
| |
| !
| |
| i l l
| |
| - -- -- -. . . - - - ,
| |
| l
| |
| | |
| . .
| |
| !
| |
| ;
| |
| 11. Maintenance M2 Maintenance and Material Condition of Facilities and Equipment M2.1 Material Condition ~ Insoection Scone (62707)
| |
| The inspectors interviewed operations, m'aintenance, and engineering personnel, inspected selected equipment, and reviewed the licensee's corrective actions to previous sequence timer malfunctions, Observations and Findinas On March 11,1997, in response to the Unit 1 loss of offsite power, the EDGs started and the required essentialloads sequenced onto their respective ESF buses; however, the recovery from the event was complicated by the numerous material condition issues that arose during the event. Specific examples included: (1) the
| |
| ~ failure of the division 17 2 safe shutdown timer to reset: (2) the failure of the commercial phone system when offsite power was lost; (3) the loss of instrument air (IA) due to the OB IA compressor tripping on high temperature and the 2A lA dryer failure: (4) the rising pressure in the cardox tank which resulted in a personnel safety concern due to the relief valve being vented into the turbine building: (5) the clogging of the auxiliary building floor drain tank system lines: (6) the overheating of the generator seal oil pump; (7) the f ailure of breaker 1351 to close: (8) the inaccurato control room phase voltage indication on bus 133; and (9) the f ailure of several breaker cubicle shudder mechanisms to operate properly. While none of these individually compromised the safety of the plant, collectively they contributed to the extended recovery from the event due to the diversion of resources and licensee management focus to resolve the issue The malfunction of sequence timers has been a long standing equipment problem at Zion Station. On December 8,1995, all of the bus 149 ESF loads, except the reactor containment fan coolers, simultaneously loaded onto bus 149 during testing. This event was documented in NRC Inspection Report 50-295/95020, 50-304/95020. On January 20,1996, two separate safety injection EDG sequence timer malfunctions occurre As a result of these three events, the licensee conducted a level 2 root cause investigation, Nuclear Tracking System (NTS) No. 295-200 96-CAT 2-003. This investigation concluded that the necessary immediate corrective actions to prevent recurrence were in place. These actions included: (1) system engineering interim guidance for increased cam shaf t clearance; (2) initiated and scheduled action requests / nuclear work requests implementing the interim guidance; and (3)
| |
| maintenance procedure E0231, " Eagle Signal Timer inspection and Lubrication,"
| |
| was updated. However, the work requests to perform these maintenance activities were not completed prior to the failure of the division 17-2 safe shutdown timer to ;
| |
| ! reset on March 11,1997. This was apparently due to the Unit 1 work requests not !
| |
| '
| |
| i
| |
| | |
| !
| |
| | |
| - - -
| |
| l
| |
| | |
| . . - - _ - -. - - - - ... . . . - = . .. . ~ . -
| |
| ,, . .- .
| |
| .
| |
| !
| |
| . s
| |
| ,
| |
| i
| |
| ! being planned until October and Novernber 1996, approximately eight months after the completion of the root cause investigation. Consequently, an opportunity to perform the maintenance activities was missed during Z1F22 (August 27.through September 18,1996).
| |
| | |
| .
| |
| The licensee's root cause investigation team also specified nine additional corrective actions. The inspectors reviewed these corrective actions and determined that one of the nine actions, NTS No. 295-200-96-CAT 2-00306, was never entered into NTS and apparently was never completed. This corrective action specified that the Central Receipt, inspection, and Testing Facility's dedication procedure be revised as necessary to include all applicable critical attributes identified in the sequence timer manufacturer's adjustment procedure. In response to the inspectors'
| |
| concern, the licensee initiated a problem identification form, 97-2179, to investigate the failute to track identified corrective actions to completion, Conclusions The inspectors concluded that the EDGs successfully started on demand and provided the required electrical power to the Unit 1 ESF loads. However, the inspectors also concluded that the numerous material condition problems contributed to the extended time for recovery from the event due to the diversion of resources and licensee management focus to resolve the issue The failure to implement timely and effective corrective actions to prevent the recurrence of sequence timer malfunctions, a significant condition adverse to quality, is a violation of 10 CFR Part 50, Appendix B, Criterion XVI (50-295/97012-02). as described in the attached Notice of Violatio Ill. Enaineering E2 Engineering Support of Facilities and Equipment E Licensee's Root Cause Investination Insnection Scone (37551)
| |
| The inspectors interviewed licensee personnel and reviewed the licensee's root cause evaluation of the loss of offsite power even Observations and Findinas On March 11, the licensee initiated an investigation into the cause of the loss of offsite power event. Based on the results of this investigation, the licensee could not conclusively determine the cause for the Unit 1 SAT trip. However, through j the elimination of other possib:e causes, the licensee concluded that the most
| |
| !
| |
| probable cause of the event was the spurious operation of the SAT sudden pressure relay. Also, the licensee's investigation noted previous instances of spurious-
| |
| ,
| |
| ( 12 l
| |
| . _
| |
| | |
| . . - - - -.
| |
| . .
| |
| i operation of these relays in the industry; however, the licensee was unable to obtain any documentation of these previous failures. The inspectors reviewed the licensee's investigation and determined that the conclusion was reasonabl Additionally, the inspectors identified that the licensee did not calibrate these sudden pressure relays. However, periodic testing was performed on a refueling outage interval. This testing was considered within the craf t capability of the maintenance staff and it roughly corresponded to Test Procedure I as described in the relay vendor information. The testing demonstrates that the relay will change state; but, it does not demonstrate that it will do so at the correct rate. The vendor information described four test procedures of varying complexity, two of which demonstrate that the relay will change state at the specified rat .
| |
| The sudden pressure relay was a transformer protective device utilized to detect sudden pressure increases in the transformer resulting from an internal fault. If the relay was actuating at a relatively low rate, the transformo, would have been susceptible to being tripped by spurious actuations of the relay. While such a setpoint would be conservative from a transformer protection standpoint, spurious actuations could result in a loss of offsite power (and hence loss of shutdown cooling), unnecessarily subjecting the plant to additional transients. The inspectors were concerned that the periodic testing of the sudden pressure relay did not demonstrate that the relay was within calibratio Conclusions The inspectors concluded that the licensee's investigation into the cause of the loss of offsite power was sound and the conclusions were reasonable. Also, the inspectors concluded that the failure to demonstrate that the sudden pressure relay, a nonsafety-related component, was within calibration was a deficiency in the test progra E2.2 Emeroency Digsel Generator (EDG) Onerability Assessment for Cylinder Liner Crackina Insoection Scone (37551)
| |
| The inspectors interviewed licensee personnel and reviewed each revision of the EDG operability assessment for cylinder liner cracking, #ER970090 Observations and Findings On January 27,1997, the 2A EDG experienced a significant drop in crankcase tube oil level during a maintenance run. The licensee's investigation into the event l determined that the loss of tube oil was caused by a through-wall crack in the 1L l cylinder liner. The crack allowed a sufficient amount of cooling water to I
| |
| accumulate in the cylinder to cause the piston to catastrophically fail during engine startup. The review of the licensee's root cause investigation will be the subject of NRC Inspectic.i Report 50-295/97-05, 50 304/97-05.
| |
| | |
| ,
| |
| | |
| l l
| |
| i
| |
| : , .
| |
| -
| |
| i i
| |
| i On February 8,1997, the licensee approved the initial operability assessmen #ER9700909, for the 1 A,1B, O, and 2B EDGs, which concluded that the EDGs were operable. The licensee subsequently inspected and identified additional examples of cylinder liner cracking on the 28 EDG. As a result, on February 27, 1997, the licensee completed an operability issue re-assessment. This re-I assessment specified compensatory actions to be performed to ensure that a cylinder liner through-wall crack did not exist. The re-assessment required these compensatory actions to be performed prior to the next scheduled start of each EDG and approximately 24 hours after each demand or series of demands thereafter until the issue was resolve On March 5,1997, the inspectors identified that the operating shift personnel were planning to perform the monthly operability surveillance test for the O EDG on the day-shif trhowever, operating shift personnel were unaware of the requirement to perform the compensatory action specified in the operability re-assessment prior to engine operation. The licensee had apparently failed to route the re-assessment to i
| |
| the operating shift. The inspectors were concemed that even though operations l management had attended the Plant Operations Review Committee (PORC) meeting which reviewed the operability re-assessment, the compensatory action j requirements were not communicated to the control room operator On March 6,1997, the inspectors discussed this concern with the Unit 1 Plant Manager. He indicated that the problem had occurred due to operations management's lack of ownership of operability assessments and due to programmatic weaknesses in the operability assessment process. Specifically, the operability assessment process did not require revisions to operability assessments )
| |
| to be approved by the operating shif t. He also indicated that corrective actions for I the problems were being developed and would be implemented as soon as practical.
| |
| | |
| ,
| |
| On March 11,1997, Unit 1 experienced a loss of offsite power and the 1 A,18, l- and O EDGs started and essentialloads were sequenced onto their respective ESF buses. This successful start of these EDGs provided assurance that a through-wall crack, of sufficient size to prevent the fulfillment of the EDG's safety function, did not currently exist. The licensee's initial response to the loss of offsite power event was to pursue shifting the ESF buses' power feeds from the EDGs to reserve feed l from the Unit 2 SAT. Since the licensee's operability assessment stated that crack (
| |
| '
| |
| propagation typically occurred during the thermal transient of the EDG cooldown, the inspectors were concerned that the EDGs would be secured without evaluating the potential impact of the cooldown on the EDGs. The licensee had yet to develop a procedure to perform the specified compensatory actions in a manner that did not j require the EDGs to be taken out-of service. In addition, transfer to the reserve l l feed required disconnecting of the applicable EDG from its ESF bus prior to
| |
| ) energizing the bus from the reserve feed (a dead bus transfer).
| |
| | |
| l i l On March 12,1997, a conference call between the NHC and the licensee was I
| |
| '
| |
| conducted to discuss the licensee's plan for recovery ef offsite power to Unit 1.
| |
| | |
| l The inspectors observed a subsequent PORC meeting regarding the EDG operability assessment and the recovery plan Based on the inspectors observations and i
| |
| !
| |
| 14 i
| |
| '
| |
| i l
| |
| l
| |
| . *
| |
| .
| |
| l discussions with senior plant management, the inspectors concluded that senior plant management did not fully understand the deta!is supporting the EDG operability assessment conclusions. This lack of understanding was apparently due to poor communication and documentation of the basis of the specified compensatory actions. As a result of the PORC's recommendations, the licensee -
| |
| decided to keep the ESF buses powered by their respective EDGs and suspended ongoing SOI-63F actions until the status of the SAT could be determine On March 15,1997, the licensee approved revision 2 of the operability assessment which modified the compensatory action requirements. This revision specified that the action, to check for the existence of a cylinder liner through wall-crack, be performed 24 to 48 hours following each EDG demand or series of demand However, the inspectors were concerned with the soundness of the engineering judgement utilized in determining the time interval, in the case of the 2A EDG failure on January 27,1997, the machine had been started within 48 hours and sufficient water had accumulated in the cylinder to result in a catastrophic failure of the 1L piston. The inspectors subsequently raised this concern to senior plant managemen On March 18,1997, the PORC reviewed revision 2 of the operability assessment and determined that it needed to be revised. On March 19,1997, the licensee approved revision 3 without addressing all of the concerns raised by the PORC. In addition, the inspectors noted that this revision omitted the requirement to perform the compensatory action prior to the next scheduled start of each EDG, although that start had not yet been attempted for the 2A EDG. Based on discussions with operations and engineering personnel, the inspectors determined that the omission had been inadvertent. Af ter addressing issues previously raised by the PORC, the licensee approved revision 4 on March 26,199 Conclusions The inspectors concluded that between February 27 and March 5,1997, the operating shift was unaware of the requirements imposed by the EDG operability assessment due to poor communications and a lack of operations ownership of operability assessments. The inspectors also concluded that poor communication and documentation of the basis and the compensatory actions required to support the operability assessment unnecessarily complicated the recovery plans and resulted in delays in the restoration of offsite powe V. Manaaement Meetinas X1 Exit Meeting Summary l The inspectors presented the inspection results to members of licensee l management at the conclusion of the inspection on May 7,1997. The licensee acknowledged the facts presented, but objected to the characterization of licensee performance related to the timeliness of the event response. Specifically, the
| |
| | |
| . .
| |
| licensee did not agree with the inspectors' conclusion that licensee performance deficiencies unnecessarily hampered and slowed the event respons The inspectors asked the licensee whether any materials examined during the inspection should be considered proprietary. . No proprietary information was identifie .
| |
| | |
| 16 i
| |
| | |
| . . . . .
| |
| . .
| |
| ,
| |
| Partial List of Persons Contacted Licensee .
| |
| J. Mueller, Sito Vice President -
| |
| R. Starkey, Plant General Manager
| |
| .R..Godley, Regulatory Assurance Manager M. Weis, Support Services Director R. Zyduck, Site Quality Verification Director G. Vanderheyden, Operations Manager M. Schimmel, Unit 2 Maintenance Manager D. Beutel, Regulatory Assurance M. Wiesneth, Regulatory Assurance fLRC -
| |
| A. Vegel, Senior Resident inspector E. Cobey, Resident inspector
| |
| .;
| |
| | |
| . .. . . .
| |
| - _ - _ >
| |
| .. . .
| |
| -
| |
| | |
| c
| |
| .
| |
| )'
| |
| .
| |
| List of Inspection Procedures Used IP 37551 Engineering IP 62707 Maintenance Observation IP 71707 Plant Operations
| |
| - IP 93702 Prompt Onsite Response to Events at Operating Power Reactors List of items Opened. Closed, and Discussed Oooned 50-295/97012-01 VIO - Failure to have an existing procedure for responding to a loss >
| |
| -
| |
| of offsite power event 50-295/97012-02 VIO Failure to implement timely and effective corrective actions to prevent the recurrence of sequence timer malfunctions Closed 50-295/97007 LER System auxiliary transformer trip caused by spurious operation of the sudden pressure relay with minimalimpact to the plant l- 18
| |
| -- -
| |
| | |
| . . . . .
| |
| . . . . . . .
| |
| ,
| |
| . .
| |
| ,
| |
| List of Acronyms AOP Abnormal Operating Procedure EDG Emergency Diesel Generator ENS Emergency Notification System ESF Engineered Safety Feature ESP Emergency Support Procedure ESS Engineered Safeguards System lA Instrument Air LER Licensee Event Report NRC Nuclear Regulatory Commission NTS Nuclear Tracking System -
| |
| PORC Plant Operations Review Committee RHR Residual Heat Removal SAT System Auxiliary Transformer SOI System Operating Instruction TSC Technical Support Center
| |
| | |
| 8
| |
| .-
| |
| }} | | }} |
