IR 05000387/1989005
| ML17156B143 | |
| Person / Time | |
|---|---|
| Site: | Susquehanna  |
| Issue date: | 04/28/1989 |
| From: | Blough A NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| To: | |
| Shared Package | |
| ML17156B142 | List: |
| References | |
| 50-387-89-05, 50-387-89-5, 50-388-89-05, 50-388-89-5, NUDOCS 8905100160 | |
| Download: ML17156B143 (46) | |
Text
U.S.
NUCLEAR REGULATORY COMMISSION
~
REGION I
Report Nos.:
50-387/89-05; 50-388/89-05 Docket Nos.:
50-387; 50-388 License Nos.:
Pennsylvania Power and Light Company 2 North Ninth Street Allentown, Pennsylvania 18101 Facility Name:
Susquehanna Steam Electric Station Inspection At: Salem Township, Pennsylvania Inspection Conducted:
February 5,
1989 - March 11, 1989 Inspectors:
F.
Young, Senior Resident Inspector, SSES J. Stair, Resident Inspector, SSES A. Della Greca, Reactor Engineer, Division of Reactor Safety (DRS)
R. Mathew, Reactor Engineer, DRS Approved By:
A. Randy Bl
, Chief Reactor Projects Section No.
3B Division of Reactor Projects Date Ins ection Summar
T T
T d *
d plant operations, physical security, plant events, surveillance, and mainten-ance activities.
Items reviewed in detail included:
a Unit 1 manual reactor trip due to the failure of a main condensate pump, a Unit 2 manual shutdown due to failure of a reactor building chilled water system (RBCW) containment isola-tion valve to close, a Unit
ESF actuation due to pulling the wrong fuse, and an LER concerning the main steam isolation valve-leakage control system (MSIV-LCS).
Other items reviewed included the licensee's January Monthly Operating Report.
Results:
(1) During this period, operations department personnel generally conducted activities in a professional manner and operated the plant safely.
However, a blocking permit error led to the wrong fuse being pulled resulting in an isolation of RBCW to both reactor recirculation pumps (see Section 2.2).
(2) Routine review of maintenance activities noted good control and perform-ance.
(3) Regarding the electrical fault associated with the 'A'ain S90S100160 S9042S PDR ADOCK 050003S7 Q
Ins ection Summar (Continued)
Condensate Pump requiring a manual scram of Unit 1 (see Section 5.0), operating personnel properly assessed the unique circumstances and took the appropriate corrective actions.
The inspectors noted good involvement of the engineering staff to aid in troubleshooting and development of a repair program and strong involvement by management to ensure the significance of the event was under-stood prior to returning the unit to service.
(4) The licensee monthly opera-ting report was complete and accurate.
Licensee Event Reports (LERs)
were found to provide clear and accurate descriptions of, the events and corrective actions taken, however, an error in the determination of a
CFR 50.72 noti-fication was made with respect to the MSIV-LCS operability (see Section 4.2. 1).
(5) In general, sufficient management involvement and attention were applied to operate both units in a safe manne TABLE OF CONTENTS 1.0 Introduction and Overview.
~Pa e
1. 1 NRC Staff Activities (Module Nos.
30703, 71707, 90712 92700, 92701)
~
1.2 Unit 1 Summary..
1.3 Unit 2 Summary..
1.4 Persons Contacted.
1
1 2.0 Routine Periodic Inspections..
2. 1 Scope of Review.
2.2 Inadvertent Containment Isolation - Unit
(Module No. 93702)
2.3 Containment Isolation Valve Failure To Close Requiring Shut Down Unit 2 (Module No. 93702).
3.0 Surveillance and Maintenance Activities....
3. 1 Surveillance Observations (Module No. 61726)...........
3.2 Maintenance Observations (Module No. 62703)............
4.0 Licensee Reports..
4. 1 In-office Review of Licensee Event Reports (Module No. 90712).
4.2 Onsite Followup of Licensee Event Reports (Module No. 92700).......
4.3 Review of Monthly Operating Reports (Module No. 90713).
5.0 Plant Electrical Transient due to an Electrical Fault on the 'A'ain Condensate Pump Unit 1 (Module No. 92701)..
5 '
Background Event 5.2 NRC Review.
5.3 Safety Significance 5.4 Summary of Event Followup.....
6.0 Exit Meeting (Module No. 30703).............
8
10
14
DETAILS 1.0 Introduction and Overview NRC Staff Activities The purpose of this inspection was -to assess licensee activities at Susquehanna Steam Electric Station (SSES)
during power operation as they relate to reactor safety and worker radiation protection.
This assessment is based on actual observation of licensee activities, interviews with licensee personnel, measurement of radiation levels, independent calculations and selective review of documents.
The inspectors documented the specific purpose of the area under review, scope of inspection activities and findings, along with appropriate conclusions.
1.2 Unit
Summar At the start of the inspection period Unit 1 was in cold shutdown for repairs to the drywell vacuum breaker testing system for vacuum breaker PSV-15704B2 (see Inspection Report 387/89-01 Section 2.6).
On February 7, during startup, an electrical fault in the 'A'ain condensate pump caused a plant electrical transient which resulted in a loss of both reactor recirculation pumps, requiring a manual trip-ping of the reactor ( see Section 5).
The reactor was maintained in cold shutdown until the evaluation of the electrical transient was completed.
Startup recommenced on February 9 with full power being reached on February 14.
The unit operated at or near full power for the remainder of the inspection period.
1.3 Unit 2 Summar At the start of the inspection period Unit 2 was at full power.
On February 27, the unit was manually shut down as a result of the fail-ure of a containment isolation valve in the reactor building chilled water system (RBCW) to close upon loss of power to the valve's isola-tion logic (see Section 2.2)
~
After a short maintenance outage to effect repairs to the RBCW valve, startup was commenced on March 4.
During power ascension, the 'B'eactor feedwater pump discharge valve failed to open.
As a result, the unit was limited to 80 per-cent full power for the remainder of the period pending shutdown to repair or replace the 'B'eedwater pump discharge valve.
1.4 Persons Contacted During the course of the inspection, the inspector interviewed, dis-cussed issues, and received information from various licensee employee Listed below are the licensee management and employees who supplied substantive information.
Members who attended the exit interview on March 22, 1989, are indicated by an asterisk.
J.
A.
R.
G.
" A. J.
J.
R.
- E.
W.
J J
A. F.
- G. J.
C.
D.
T.
R.
W.
E.
T. J.
- J H, J.
N.
D.
"R. J.
H.
L.
" D.
F.
" R.
L.
- H.
G.
" B. J.
Blakeslee, Assistant Superintendent of Plant, SSES Byram, Superintendent of Plant, SSES Dominguez, Operations Senior Results Engineer Doxsey, Reactor Engineering Supervisor, SSES Figard, Supervisor of Maintenance, SSES Graham, Assistant Manager, NQA Iorfida, Supervisor of IKC Computer, SSES Kuczynski, Supervisor of Technical Support, SSES Lopes, Security Supervisor, SSES Markowski, Day Shift Supervisor, SSES Morrissey, Radiological Protection Supervisor, SSES Nork, Plant Engineering Group Supervisor, SSES O'ullivan, Installation Engineering Group Supervisor, SSES Palmer, Jr.,
Superintendent of Operations, SSES Pitcher, Construction Superintendent, SSES Prego, Supervisor of QA Operations, NQA Riley, Supervisor of Health Physics/Chemistry, SSES Roth, Senior Compliance Engineer, SSES Stotler, Supervisor of Security, SSES Stanley, Assistant Superintendent-Outages, SSES Veazie, Sr. Results Engineer IKC, SSES 2.0 Routine Periodic Ins ections The NRC resident inspectors periodically monitored the licensee's compliance with the general operating requirements of the Technical Specifications (TS) in the following areas:
review of selected plant parameters for abnormal trends; plant status from a maintenance/modification viewpoint, includ-ing plant housekeeping and fire protection measures; control of ongoing and special evolutions, including control room personnel awareness of these evolutions; control of documents, including logkeeping practices; implementation of radiological controls; implementation of the security plan, including access control, boundary integrity, and badging practices;
control room operations during regular and backshift hours, including frequent observation of activities in progress, and periodic reviews of selected sections of the unit supervisor's log, the control room operator's log and other control room daily logs; followup of items or activities that could affect plant safety or impact plant operations; periodic plant tours; and, selected licensee planning meetings.
The inspectors conducted backshift and weekend/holiday inspections on February 12, from Noon to 7:00 p.m.,
February 15, from 2:00 a.m.
to 6:00 a.m.,
February 22, from 10:00 p.m.
to Midnight, and March 4, from 8:30 a.m.
to 12:30 p.m.
The inspectors reviewed the following specific items in detail.
2.2 Inadvertent Containment Isolation Unit
On February 27, reactor building chilled water (RBCW)
system valves HV-18791 Al and A2 to the 'A'eactor recirculation pump and HV-18792 A1 and A2 to the 'B'eactor recirculation pump isolated when fuse FU-1A, in Panel 1C681 was removed.
The licensee had intended to remove the fuse supplying power to the 'A'mergency switchgear room cooler discharge damper motor in order to reroute the motor cable, but instead removed the fuse supplying power to the isolation logic for these RBCW System valves.
Immediate corrective actions taken by the operator were to replace the fuse, reset the isolation logic and reopen the affected valves.
The licensee determined that the event was caused by removal of the wrong fuse due to the fact that the blocking permit identified the wrong panel ( 1C681).
The appropriate location was motor supply breaker 1B217-22.
The Equipment Release Form (ERF)
requesting the blocking identified the incor rect location and was reviewed by the Unit Coordinator and the Plant Control Operator, both of whom failed to identify the error.
The licensee reviewed the error leading to the event and discussed the event with the individuals involved in writing the ERF and plant supervision.
In addition, operator refresher training in reading electrical prints will be reevaluated to ensure proper emphasis and understanding is maintained by the operating crews.
The licensee concluded that this was not a generic problem due to the small number of errors that have occurred in relation to the large number of blocking permits reviewe The inspector reviewed the Significant Operating Occurrence Report (SOOR),
the blocking permit, the ERF, and discussed the event with the licensee.
Corrective actions appear acceptable, however the inspector considers this to be another example of a
lapse of atten-tion to detail as discussed in Combined Inspection Report Nos.
387/89-01 and 388/89-01.
2.3 Containment Isolation Valve Failure to Close Re uirin Shutdown-Unit 2 On February 27, a Division II, primary containment isolation (PCI)
occurred when the normal power supply to the 'B'eactor protection system (RPS)
instrument bus failed.
During verification of plant response, the licensee found that PCI valve HV-28792B2 did not close.
This valve is in the reactor building chilled water (RBCW)
system return 'line from the 'A'eactor recirculation pump mo'tor.
Attempts to manually close the valve were unsuccessful and the licensee entered Technical Specification (TS)
Section 3.6.3 which requires either isolation of the penetration resulting in single recirculation loop operation, or a plant shutdown.
Since the valve is located inside primary containment, it was inaccessible during power opera-tion and could not be worked on until the unit was placed in cold shutdown and primary containment deinerted.
As a result, the unit was brought to cold shutdown on February 28 in order to investigate and repair the cause of the failure.
The licensee found that the solenoid valve which supplies air to HV-28792B2 was not functioning.
The valve was replaced and the unit returned to power operation on March 4.
Immediate corrective actions taken by the licensee included resetting the containment. isolation signal and restoring the RBCW system.
Fol-lowing plant shutdown, the licensee determined that the cause of failure of the RBCW valve to close was due to its air supply solenoid valve failing to actuate on loss of power.
The valve was replaced and sent to a research laboratory (Franklin Institute) for analysis in an attempt to determine the failure mode, which will aid in assessing potential applicability to other valves.
Results of the analysis were not available at the end of the inspection period; con-sequently the potential generic applicability of this failure is unresolved (388/89-05-01).
Additionally, the root cause for the failure of the 'B'PS motor generator set was determined to be an internal short circuit to ground in the motor stator windings.
The motor was replaced and the motor generator set returned to service.
This was considered to be an isolated case and no further corrective actions are planned at this time.
The inspector reviewed the significant operating occurrence reports (SOORs)
on the event and discussed the event with the licensee's plant staff.
As a result, the inspector found the licensee's actions in response to the event acceptable and had no further questions at this tim.0 Surveillance and Maintenance Activities The inspector observed selected surveillance and maintenance activities to ensure that the specific programmatic elements described below were being met.
3. 1 Surveillance Observations The inspector observed performance of surveillance tests to determine that the test conformed to Technical Specification requirements; administrative approvals and tagouts were obtained before initiating the surveillance; testing was accomplished by qualified personnel in accordance with an approved procedure; test instrumentation was cali-brated; Limiting Conditions for Operations were met; test data was accurate and complete removal and restoration of the affected com-ponents was properly accomplished; test results met Technical Spec-ification and procedural requirements; deficiencies noted were reviewed and appropriately resolved; and the surveillance was com-pleted at the required frequency.
These observations included:
S0-256-001, Weekly Exercising of Control Rods for Operability, performed on February 12, 1989.
S0-256-007, Control Rod Coupling Check, performed on March 4, 1989.
No unacceptable conditions were identified.
3.2 Maintenance Observations The inspector observed and/or reviewed selected maintenance activ-ities to determine that the work was conducted in accordance with approved procedures, regulatory guides, Technical Specifications, and industry codes or standards.
The following items were verified dur-ing this review:
Limiting Conditions for Operation were met while components were removed from service; required administrative approvals were obtained prior to initiating the work; activities were accomplished using approved procedures and quality control hold points were established where required; functional testing was per-formed prior to declaring the involved component(s)
operable; activ-ities were accomplished by qualified personnel; radiological controls were implemented; fire protection controls were implemented; and the equipment was verified to be properly returned to servic These observations and/or reviews included:
Investigation and repair of vacuum breaker PSV-15704B2 per WA S90191, performed on February 5,
1989.
Investigation and repair of the Unit 1 'A'ain condensate pump per WA S90223, following its failure on February 7, 1989.
Investigation and repair of reactor building chilled water sys-tem isolation valve HY-28792B2 per Work Authorization (WA)
V90090, performed on February 28, 1989.
Replacement of Lamp Sockets, Lamps and Lens Caps in Panel OC653-75C per Construction Work Order (CWO) C80716, performed on March 3, 1989.
No unacceptable conditions were identified.
4.0 Licensee Re orts 4. 1 In-office Review of Licensee Event Re orts LERs The inspector reviewed LERs submitted to the NRC to verify that details of the event were clearly reported, including the accuracy of description of the cause and adequacy of corrective action.
The inspector determined whether further information was required from the licensee, whether generic implications were involved, and whether the event warranted onsite followup.
The following LERs were reviewed:
Unit
89-001-00 Inadvertent Instrument Air Isolation Results In Automatic Reactor Shutdown 89-002-00 Operator Error Caused Feedwater Flow Transient and Reactor Scram 89-003-00 Primary Containment Isolation Valve Isolates Twice Due To Pressure/Flow Perturbations Unit 2 89-001-00 MSIV-LCS Valves Inoperable Due to Environmental Qualifica-tion Deficiencies The above LERs were found acceptabl.2 Onsite Followu of Licensee Everrt Re orts I
For Unit 2 LER 89-001-00, which was selected for. onsite followup, the inspector verified that the reporting requirements of 10 CFR 50.73 had been met, that appropriate corrective action had been taken, that the event was adequately reviewed by the licensee, and that continued operation of the facility was conducted in accordance with Technical Specification limits.
During the Unit 2 refueling outage in the spring of 1988, the licen-see discovered that motor splices utilized on three valves in the Main Steam Isolation Valve Leakage Control System (MSIV-LCS) were not environmentally qualified.
The splices used were lug and bolt, and butt type splices which were considered acceptable when installed by PP8 L Co. in 1983.
These splices were installed on the internal wind-ing connections of the dual voltage motors for valves HV-239F001F, HV-239F006 and HV-239F009.
The licensee immediately replaced all three splices with qualified Raychem NPKV Kit connections.
At the time of discovery, the licensee requested their Nuclear Plant Engineering (NPE)
department to perform an evaluation to determine the operability of the MSIV-LCS subsystem for.the period in which the unqualified splices were installed.
This evaluation appears to have taken an unduly long period of time to complete.
On January 18, 1989, NPE determined that the above three valves should not be considered to have been operable during the period in which the unqualified splices were installed, based on the fact that no analysis had been performed to confirm that the valves would have performed their post-LOCA design function.
A test or anaylsis ta. qualify the= a~ound configuration would have been lengthy, costly, and of no current technical relevance since the splices had been replaced.
The licensee concluded, however, that the safety significance of this condition was minimal.
This was based on NUREG 1169 which indicates that there are relatively low public risks from MSIV leakage without MSIV-LCS, even at relatively high leak rates, if the containment remains intact.
.On January 18, 1989, following engineering review of the as-found spliced connections, the licensee determined that the condition was reportable per
CFR 50.73(a)(2)(i)
and (a)(2)(v).
This was based on Technical Specification 3.6. 1.4 which requires that two independ-ent MSIV-LCS subsystems shall be operable in Conditions 1,
2, and 3.
The action statement requires that with one MSIV-LCS subsystem inop-erable, the inoperable subsystem shall be restored to operable status within 30 day The licensee determination that"the event was reportable based on XO CFR 50.73(a)(2)(v)
appears to be correct However, the criteria con-tained in that section of 50.73 direct?y corresponds to 10 CFR 5Q 72.
(b)(2)(iii) which requires a four-hour report.
The inspector deter-mined that the
. licensee had considerect the requirements of 10'FR 50.72, but believed that the situation made it inappropriate to place a
four-hour notification to the NRC.
This belief was based on the length of time since the event was first discovered (approximately 8 months),
the fact that. corrective action was performed immediately upon discovery, and that an LER was submitted which provided all the appropriate information on the event.
The inspector discussed the requirements of
CFR 50.72 and. the NRC position that a
four-hour notification should have.
been made on January 18, 1989, to activate associated NRC processes for internal notifications.
The licensee acknowledged the requirement, concurred that they should have made the additional notification, and indicated an intent to make the
CFR 50.72 report in any equivalent future situations.
This event is an isolated case of minor safety significance involving misinterpret-ation of the relationship between
CFR 50.72 and
CFR 50.73.
The licensee identified and promptly replaced the questionable sp'lices.
However, their evaluation of operability and reportabi lity appears to have taken an unduly long period of time.
Therefore, the licensee's approach to this issue is unresolved pending additional NRC review (388/89-05-02).
4.3 Review of Monthl 0 eratin Re ort The Monthly Operating Report for January 1989, suhaitted:
by the licensee was reviewed by the inspector to verify that it included the required information; that test results and supporting information were consistent with design predictions and performance specifica-tions; and whether any information in the report indicated an abnor-mal condition.
The report was found to be acceptable.
5.0 Plant Electrical Transient Due to an Electrical Fault on the 'A'ain Condensate Pum Unit
5.1 Back round Event On February 7,
1989, the licensee was in the process of returning Unit 1 to power operations.
The startup had proceeded to the point requiring a
second main condensate pump be placed in service.
The
'A'ain condensate pump was selected and at 1:04:40 p.m.
on February 7, 1989, the operator initiated the starting of the conden-sate pump.
At 1:04:42 p.m.
the operator received indication of an abnormal tripping of this condensate pump followed by the tripping
of numerous other electrical components including both resctar recrv-culation pumps at 1:04:44 p.m.
At the time of the ament, UniC 1 electrical power was being supplied through the 13.8KV auxiTiary bus No.
by the offsite 230KV grid through startup transformer T10 Condensate pump 'A's powered by the No.
11, 13.8KV bus.
A simpli-
.
fied one-line diagram showing the electrical bus arrangement is shown in Attachment 1.
The fault caused the loss of both Unit 1 reactor recirculation pumps.
By procedure, with the reactor critical and no recirculation pumps running, the control room operator is required to manually scram the plant.
The operator in accordance with his procedure immediately scrammed the reactor and carried out the scram procedures.
After completing the initial scram procedures and a walkdown of the plant, the operators restarted the recirculation pumps and established recirculation flow to the reactor vessel.
Personnel access to the affected area in the vicinity of the main condensate pumps was secured.
There was indication by the operator that the capacitor in the electrical lead termination box had failed and this capacitor contained polychlorinated biphenyls (PCBs).
The area was controlled as a toxic hazard area.
Cleanup of the area and repair of the pump leads was accomplished within about two days of the event.
An immediate investigation of the occurrence revealed the apparent initiating event to have been a single phase fault involving one of three cables inside the termination enclosure at the pump motor.
The fault quickly developed into a three phase fault;- This= large fault resulted in degraded voltage conditions on the 13.8KV bus feeding the condensate pump as well as the remainder of the unit's electrical system fed by the same voltage source.
The voltage degradation pro-duced a
series of motor trips, valve closures, relay dropouts and automatic motor starts from the 13.8KV bus down to the 120V control circuits.
A complete list of the equipment affected is provided in Attachment 2.
The largest loads affected by the fault were the reactor recirculation pumps fed by the same 13.8KV bus.
The duration of the fault was calculated to be approximately 200 milliseconds.
The bus voltage recovery time was less than 5 seconds.
In general, only loads which are protected by instantaneous undervoltage relays or which contain auxiliary control relays in 120V circuits were affected.
Several loads associated with Unit 2 were affected by the event.
This resulted from the fact that these loads receive their power from the same startup transformer (T10) which powers the Unit
condensate pump Subsequent investigation determined that the reactor recirculation pumps did not trip on undervoltage, because they are protected by a time-delay undervoltage relay. It was also detereined that they did not trip on overcurrent (faulted)
conditions.
The cause of the i recirculation pump trip is still under investigation.
Because of the initial complexity of trying to describe the event to the NRC, the licensee elected to present their evaluation and results to the NRC staff in the Region I office on February 9.
The licensee presented the sequence of the event, their understanding of the root cause of the event, and their proposed corrective actions.
The licensee's presentation slides are included in this report as Attachment 3-.
As described in the slides, the licensee determined the initial event to be a three phase ground in the 'A'ain Condensate Pump.
The licen-see determined the reason why each individual electrical load either started or stopped.
The proposed corrective action was to repair the pump electrical leads and return the unit to service.
5.2 NRC Review Because of the potential significance of the event, the NRC reviewed the event from operational and electrical system perspectives.
This review was conducted to ensure that the licensee was controlling the evolution in a safe and effective manner.
In addition, the review ensured that any adverse effects resulting from the electrical fault had been considered and that proper engineering techniques were being used to return the unit to service.
5.2.1 0 erational Controls As noted in the paragraph above, the inspector reviewed this event to determine:
details regarding the cause of the event and event chronology; functioning of safety systems as required by plant conditions; consistency of licensee actions with license require-ments, approved procedures, and the nature of the event; and, proposed licensee actions to correct the cause of the even The inspector reviewed the sequence cd events. aef veriAM the accuracy of it from selec~
p'1aM logs, historicai computer plant parameters data amf discussions with plarrt-.,
staff.
The inspector concurred with the licensee's
sequence of events.
The cause for each load actuation was discussed with plant electrical engineering and the licen-see's characterization of the plant response was as expected.
Overall plant response was as designed.
The operator actions and applicable procedures used were reviewed.
In general the procedures effectively controlled the event.
The inspector noted that the procedures, and the operator's previous training did not adequately address how to record/
reset relay targets.
The licensee stated the area would be evaluated and appropriate training given.
The inspector reviewed the licensee's evaluation process to ensure that any adverse effects were identified and that the transient was within the limits of the Final Safety Analysis Report (FSAR).
The inspector attended several of the licensee's internal meetings and a portion of the Plant Operational Review Committee (PORC) meeting associated with this subject.
The inspector concluded, from an operational perspective, that the licensee had properly addressed all concerns, and had taken a
prudent and conservative approach.
Evaluation of the Electrical Everrts Two NRC Region I specialists performed an in depth evalua-tion of the event, including a
review of electrical schematics of the system's configuration and specific loads.
This review was performed in parallel with the licensee's effort to verify the licensee's evaluation results.
The licensee categorized loads according to the method by which they were affected.
The purpose of the evaluation was to assure that the electrical equipment per-formed as designed and to assure that the design was ade-quate.
The licensee's explanation of affected equipment for each category is as follows:
a.
Undervolta e Rela Tri s
These loads operate on instantaneous undervoltage conditions.
Therefore, the momentary loss of voltage (200 msec.
+ voltage recovery time) caused the alarms, trips and pump starts listed under this categor b.
Seal-In Dro outs These loads are manually operated and are Naintatnech in the required condition by means of a cimuit sea)-~
in arrangement, i.e.,
relay contact in parallw) mtb-momentary initiating contact.
Although the relay which provides the seal-in feature is not an under-voltage relay, it is affected by momentary under-voltages and deenergizes under degraded conditions.
The voltage level at which the relay deenergizes is unpredictable.
It is controlled by the manufacturer's tolerances.
Seal-in circuits are intended to dropout
'n loss of voltage.
c.
Contactor Dro outs Contactors and motor starters are large relays and are affected in the same manner as the seal-in relays above.
If contacts from the motor starter or contac-tor are used in control circuits, the controlled equipment will behave in the same manner as it would under loss of voltage conditions.
d.
Process Si nal Tri s
The equipment identified under this category was affected by the loss of other equipment in the process systems.
The start/stop of this equipment is predic-table when a loss of voltage is postulatecf e.
Other The licensee has justified the impact of the event upon the equipment listed under this category.
The explanation provided is reasonable and acceptable.
Causes Of Unit 2 E ui ment Problems The licensee has justified each condition obser ved.
The explanations provided are reasonable and acceptabl For each category listed above, the~ inspectors determined that the licensee had determined'n-appropriate explana-tion.
The review did note that a ~up of the Unit
Safety Parameter Oisplay System (SPOS) display console in the control room around the ti~ ef the.
event occurred;
!
However, it was observed that the Unit 2 SPOS perturbation occurred approximately ten minutes after the event and was apparently unrelated to the Unit 1 event.
In an attempt to establish the cause for the trip of the Unit 1 reactor recirculation pumps, the inspector s observed that the pump protection scheme contains very few alarms and computer inputs.
While this practice minimizes alarms in the control room, it is limiting in the determination of the conditions which led to the trip.
This was complicated by the fact that no manual records were taken to identify the relay targets received.
While this situation did not impact recovery from this event, it was observed that a
manual record of the targets would facilitate an evaluation of this and other similar events.
As discussed above, the licensee agreed to review this weakness and to take the appropriate action.
The inspectors concluded that the licensee's review of the electrical event provided an adequate explanation of the event.
The electrical equipment that was affected by the electrical fault performed as expected.
5.3 Safet Si nificance The safety significance of the event described above was evaluated with the following results:
Condensate Pum Tri The three phase fault at the 13.8KV condensate pump motor was isolated by its feeder breaker within 200 milliseconds, thus protecting the bus and preventing the propagation of the fault to other components in the system.
The speed at which the fault was isolated indicates proper coordination between the protective relays, the feeder breaker and the bus main breaker.
Although the magnitude of the fault was very high, its effect on the feeder breaker and the asso-ciated switchgear was minimal because they are both designed to withstand the maximum calculated short circuit current available at the bu.3.2 Reactor Recirculation
'Fri The reactor recirculattos pmps ~pped while the reactar was operating at 1 percent. power.
At this power leveT, the.
resulting reactor power osciTlatfons were minimal compared to those which would have occurred had the reactor been in the run mode, at 100 percent power.
Nonetheless, the event is bounded by the dual recirculation pump trip event ad-dressed under Chapter 15 of the FSAR.
In response to NRC Bulletin 88-07, the licensee had committed to a
manual shutdown of the reactor in the event of loss of both recirculation pumps.
The licensee complied with this commitment.
5.3.3 Loss of Other Loads The voltage drop experienced as a result of the fault at the condensate pump motor terminals caused several loads to trip or start automatically.
These events are normally considered when the design bases of the systems are estab-lished.
They are acceptable consequences of loss of volt-age conditions'.4 Summar of Event Followu For the event discussed above, the licensed operator response was considered timely.
Applicable emergency procedures were properly implemented.
Followup corrective actions presented by the licensee were in general sound and appropriate for the,'ircumstancesf The licensee's handling of the area of the main condensate pumps in accordance with environmental requirements was done properly and ade-quately.
Electrical troubleshooting and the investigation by corpor-ate and onsite engineering was found to be 'ood.
Review of the engineering work that was conducted by the licensee indicated that the task force that was formed to troubleshoot, repair the pump motor leads, and resolve the technical issues was knowledgeable and staffed with people that were capable of handling the evolution.
The inspec-tor had no further comments on this matter.
On Harch 22, 1989, the inspector discussed the findings of this inspection with station management.
Based on NRC Region I review of this report and discussions held with licensee representatives, it was deter-mined that this report does not contain information subject to
CFR 2.790 restrictions.
At the conclusion, the licensee acknowledged the NRC findings and did not disagree with them or their characterizatio R105 T-20 OX104
2R106 230KV 13.6KV S/U BUS
OA104 24KV 13.8KV AUX BUS pi 12A 2A101 500KV T-21 SHYD 500KV 24KV 2xlolA~B~C GEN 2G101
2X105 pi AUX BUS 128 2A102 1X102 230KV 2IKV 24KV 13.8KV Oi 1it 230KV I
1X101 230KV 24KV GEN IGioi
230KV 1X105 13. SKV HONTPUR NXNTAIN 1R105 1R106 (HSGS)
S/U TRANS 10 OX103 pi AUX BQf S/U BUS pi 1 iA
1A101 OA103 OAIOV OA10 02
'
0@106 ESS201 OX203 OX502 13.8KV 4.16KV OA502 13.8KV 4.16KV OA501 OX&1 4.16KV 13.8KV 13.$ KV 4.16KV ESS101 OX201 ESS211 OX213 13.6KV
~.16KV 2D 2A204 1D 1A204 D
OG501D
}
13.6KV h.16KV ESS111 OX211 A
OG501A 2A2OS
'C DISTRIBUTION NETHORK FIGURE 0
2A202
1A202
OC5018 C
OC501C 1C 1A203 CLOSED CKT BKR OPEN CKT BKR o
THO UNIT OPERATIONAL LINEUP SHORN
Attachment
page 1 of 2 Causes of Unit
& Common Equipment Problems Undervoltage Relay Trips Aux 11 Transformer Trouble Alarm ESS 211 Transformer Trouble Alarm ESS 101 Transformer Trouble Alarm
"A" RB Chiller Tripped
"A" TB Chiller Tripped Stator Cooling Trouble - Second Pump Started
"E" DG Trouble (OB566 Undervoltage).
Seal In Dropouts Containment Purge HV-15713 Closed
"A" Containment Valves Closed Dual Indication
"A2" CRM Pump Tripped Contactor Dropouts RWCU Pumps A & B Tripped Fuel Pool Pumps Tripped Steam Packing Exhauster
"A" Tripped Supp Pool Filter Pump Tripped
& Valves Stayed Open Lube Oil Transfer Pump 1P143 Tripped Unit 1
& Common GRRCCW Pumps Tripped Process Signal Trips Lube Oil Centrifuge Tripped
"C" RFP DC Oil Pump Started All RFP AC Oil Pumps Running Standby RBCCW "A" Started Degassifier Tripped Other SDV Trouble Alarm - Normal Scram alarm.
Sealing Steam Condenser Panel Trouble Caused by SPE
"A" trip.
Computer Problem DCP2
& Disagreement alarms are normal for cpmputer transfers during power system voltage transients.
Recirc
"A" Motor Cooler Leak Alarm Normal for short trip of Recirc pump.
Condensation forms on pump cooler due to loss of air flow and alarms as a leak.
"A" & "B" Recirc Pump Tripped Still under evaluatio Attachment
Daae 2 of 2 t
~
Causes of Unit 2 Equipment Problems
"A" TB Chiller Tripped - Undervoltage relay dropout.
"Al" CRM Pump Tripped Seal in dropout
"A" CAC Valves Closed Seal in dropout.
"A" TBCCM Auto Started Process signal started.
SPDS Console Isolated - Isolation was 10 minutes after condensate pump trip and not caused by even Attachment
Pane 1 of 21
PROMPT OPERATOR RESPONSE TO SIGNIFICANT PLANT EVENT ACTIONS IN ACCORDANCE WITH APPROVED PROCEDURES
TOTAL ORGANIZATIONAL INVOLVEMENT AT OUTSET EXPERTISE OF PLANT, NPE, COMPANY ELECTRICAL ORGANIZATIONS SENIOR MANAGEMENT SUPPORT AND INVOLVEMENT
EXTENSIVE DATA COLLECTION AND ANALYSIS PLANT RESPONSE PER DESIGN DESIGN ADEQUATE AND IN CONFORMANCE TO REQUIREMENTS CLEAR IDENTIFICATION OF ISSUES
COMPREHENSIVE MANAGEMENT PROCESS IN PLACE ENSURE RESOLUTION OF ISSUES OVERALL ASSESSMENT OF SAFETY PRIOR TO STARTUP
Attachment
Paae 2'f 21 EVENT TIMELINE FEBRUARY 7, 1989 0200 0540 1300 UNIT 1 ENTERS CONDITION 2 UNIT 1 REACTOR CRITICAL NORMAL STARTUP EVOLUTION PLACING FEEDWATER/CONDENSATE SYSTEM COMPONENTS IN SERVICE 1304 1325 1335
'w 1500
. OPERATOR STARTS "A" CONDENSATE PUMP OBSERVES EXTENSIVE ELECTRICAL TRANSIENT 25 UNIT 1/COMMON IMPACTS 4 UNIT 2 IMPACTS BOTH UNIT 1 REACTOR RECIRCULATION PUMPS TRIP OPERATOR MANUALLY SCRAMS UNIT 1 AS DIRECTED BY OFF-NORMAL PROCEDURE RESTARTS "A" REACTOR RECIRCULATION PUMP PER EO FLOWCHART AND OPERATING PROCEDURE RESTARTS "B" REACTOR RECIRCULATION PUMP PLANT RECOVERY COMPLETE ROUTINE COOLDOWN COMMENCES FEBRUARY 8, 1989 1410 ENTERS CONDITION 4, COLD SHUTDOWN
Attachment
Paae 3 of 21 EVENT ANALYSIS PROCESS o
INITIATING EVENT APPLICABI E FOR ALL SCRAMS, SHUTDOWNS AND MAJOR TRANSIENTS.
o DATA ANALYSIS/EVALUATIONBY STA PROCESS COMPUTER SEQUENCE OF EVENTS/HISTORY GETARS TRANSIENT MONITORING GRAPHS INVOLVED PERSONNEL DEBRIEFING ESTABLISHED POST EVENT CONTROL ROOM WALKDOWN o
.
SENIOR OPERATIONS MANAGEMENT DEBRIEFING REVIEW EVENT INITIAL IDENTIFICATION OF OPEN ISSUES INVOLVEMENT OF SUPPORT GROUPS
Attachment
Page 4 of 21 EVENT RECOVERY MANAGEMENT RECOVERY TEAM CONSTITUTED RESOURCES SCOPE o
OPEN ISSUES CONFIRMED AND PURSUED o
RESTART ISSUES RESOLVED o
SAFETY REVIEW BY PLANT OPERATIONS REVIEW COMMITTEE RECOMMENDATION FOR RESTART o
SUPERINTENDENT AUTHORIZES RESTART o
FOLLOWUP REPORTS AND ISSUE CLOSEOUT
Attachment
Paae 5 of 21 POST REACTOR TRANSIENT/SCRAM/SHUTDOWN EVALUATION TRANSIENT/SCRAM/SHUTDOWN SHIFT TECH ADVISOR o
INITIATE OCCURRENCE REPORT o
COMPILE DATA o
PROVIDE INITIAL EVALUATION OF PLANT RESPONSE SHIFT SUPERVISOR o
MAKE REQUIRED NOTIfICATIONS o
SOLICIT TRANSIENT/SCRAM/
SHUTDOWN INFORMATION FROM INVOLVED PERSONNEL SENIOR OPS MANAGEMENT (POST SHIFT DEBRIEFING)
o REVIEW EVENT WITH OFF-GOING SHIFT o
ASSURE CAUSE OF EVENT IS IDENTIFIED o
GENERATE A LIST OF OPEN ITEMS LEAD SHIFT TECH ADV o
COORDINATE TRANSIENT REPORT R
OV RY TEAM MEETING o
DEVELOP INITIAL RECOVERY SCHEDULE o
IDENTIFY ANY ADDITIONAL ACTION ITEMS REQUIRED PRIOR TO RESTART o
INITIATE ANY NECESSARY PLANT EQUIPMENT INSPECTIONS o
TASK TEAM FORMATION TO ADDRESS PLANT ISSUES ACTI R
V Y PHAS o
COMPLIANCE VERIFIES PROPER REPORTABILITY o
RESPONSIBLE INDIVIDUALS COMPLETE ASSIGNED ACTION ITEMS THAT ARE REQUIRED FOR RESTART o
RESTART PORC MEETING SHI T TE HNICAL ADVISO o
FINALIZE AND ISSUE TRANSIENT REPORT PLANT SUPERINTENDENT o
AUTHORIZE RESTART
~CONPL tAMC o
TRACK REMAINING OPEN ITEMS
RECOVERY TEAH HANAKR T, DALPIAZ TECINICAL SUPERVISOR DAY SHIFT LEAD T. NIM PLANT ENIR SUPV HINT SHIFT LEAD T. PIENINTESE NSSS MNP SUPV COND PUHP RESTORATION A. IORFIDA ELECTRICAL HAINT SUPV TECH SECTION (10 PEOPLE)
RELAY TEST (2 PEOPLE)
NPE VESSEL (2 PEOPLE)
NPE ELECTRICAL (6 PHPLE)
Ql et
~Q rt
<D O Ch ~
PLANT ÃTR h (mTROLS NPE YSTEHS ANALYSIS (2 PEOPLE)
Attachment
Page 7 of 21 UNIT 1 CONTROL ROOM STAFFING FOR STARTUP
SRO (UNIT SUPERVISOR)
PLANT CONTROL OPERATORS
ON REACTOR OPERATING PANEL
STARTING CONDENSATE PUMP
ON UNIT SERVICES BENCHBOARD MONITORING CONDENSATE PUMP START
Attachment
Paae 8 of 21 PLANT AND OPERATOR RESPONSE PLANT HEATUP AND STARTUP. GO-100-002
INITIAL CONDITIONS REACTOR PRESSURE 480 PSIG REACTOR LEVEL
INCHES
"B" CONDENSATE PUMP IN SERVICE FEEDING VESSEL
PREPARING TO FEED VESSEL WITH FEEDWATER PUMPS ATTEMPT TO START "A CONDENSATE PUMP ELECTRICAL fAULT OCCURS UNIT 1 IMPACTS UNIT 2 IMPACTS
niiav>u>ie>i ~
Pane 9 of 21 CONTROL ROOM ALARMS AND OISBRVBD PLANT RESPONSE U~HT Qf L
E
'BE OIL CEHTRIFU6E TRIPPED AUXILIARYTRNSFORttER 11 ALANS ANKIATED LOSS OF COOLERS LOSS OF CONTROL VCLTAGE TRAHSFORtlER ESS 101 ALARttS ANNUNCIATED LOSS OF COOLERS LOSS OF COHTROL VOLTAGE
~t Tlg
'A1'MTAIMKHTRADIATION ttOHITN TRIPPED
'A'NBOARD ND OUTBOARD COHTAIMet AtteSPHERE Cere.
VALVE CLOSED
'A'URBINE BUILDING CHILLB TRIPPED
'A'URBINE BUILDING CLOSED COOLING MATER PUttP AUTO STARTED TRNSFORttER ESS 211 ALARt5 AHHVHCIATED LOSS OF COOLERS LOSS OF COHTROL VCLTAGE COHTAINttENT PURGE VALVE ttV-1$713 ISOLATED A
CONTAIMSIT SAMPLE VALVE SHSKD OVAL IHDICATIOH
'A'D 'B'EACTOR MATER CLEAWP POTS TRIPPED
'A'D 'S'EACTN tKCIRCVLATIOHPINS TRIPPED
'A'EACTOR BUILDING CHILLER TRIPPED
'A'NSIHE BUILDING CHILLER TRIPPED E. POOL COOLIN6 PCS TRIPPED
'A'ONTAIQKHTRADIATION ttONITOR TRIPPED
'C'EACTOR FEB PVttP DC OIL PVttP FON RWIHG lIILE ALL AC Oll. PCS liERE IN OPERATION
'A'TEAtt PACKING EXHAUSTER TRIPPED
'A'EACTOR BUILDIHG CLOSED COOLIN6 MATER PNt STARTED SCRAtt DISCHAR6E VOLQK TROUBLE ALAI5 ANNOTATED GO@RAIN STATN COOLING MATER Plà TRIPPED SEALING STEAtt COteENSER PAte. tv@LE ALARt5 ueaeCIATED]
PROCESS CON)TER TRNSFERRED TO LPS P56KO PROCESSORS TURBINE MLDING ND tKACTOR BUILDING SAtfLE STATION ALAI5 ANUNCIATED
'E'IESEL GMRATOR TROUBLE ALNS ANSCIATED
'A'EACTN RECIRCVLATIOH Plà tITOR COOLER LBK ALARtl IATED SUPPRESSION POOL FILTER PUtf TRIPPED MITH VALVES STAYIN6 OPEH LUBE OIL TRANSFER PVttP TRIPPED GASEOUS RADMASTE REC0%1%R CLOSED COOLING MATER PUN'RIPPED
Attachment
Paqe 10 of 21 PLANT AND OPERATOR RESPONSE o
ENTER ON-164-002, LOSS OF RECIRC FLOW LOSS OF RECIRCULATION FLOW, ON-164-002 o
OPERATOR INSTRUCTED TO MANUALLY SCRAM REACTOR IF NO REC I RC PUMPS IN SERVICE CONSERVATIVE RESPONSE TO REACTOR STABILITY ISSUE o
ENTER E0-100-101, SCRAM
Attachment
Pave 11 of 21 PLANT AND OPERATOR RESPONSE RECOVERY FROM SCRAM. EO-100-101
PERFORMED IMMEDIATE ACTIONS IN RESPONSE TO SCRAM
DECISION STEP CALLS FOR RESTORATION OF FORCED CIRCULATION BY RESTARTING RECI RC PUMPS IF PRECONDITIONS FULFILLED
OPERATOR VERIFIES COMPLIANCE WITH TECH SPEC TEMPERATURE LIMITS FOR PUMP RESTART
BOTH RECIRCULATION PUMPS RESTARTED
RECOVERY OF AFFECTED EQUIPMENT IN ACCORDANCE WITH OPERATING PROCEDURES PLANT COOLDOWN FOLLOWING SCRAM, GO-100-011
Attachment
PLANT AND OPEIPATOR RESPONSE SUMMARY
OPERATOR ACTIONS APPROPRIATE, IN FULL ACCORD WITH EXISTING PROCEDURES
PLANT EQUIPMENT RESPONDED AS EXPECTED
T-20 230KV OX104 13.8KV pi S/U BUS
OA104 24KV 13.8KV Aux Bus oi 12A 2A101 500KU T-21 SWY0 50PKY 24KV I<
2R106 2xloiAr8>C
~N 2OIOI
2X105 pi AUX BUS 128 2A102 1X102 230KY 24KV 24KV 13.8KV llew QQi Pi fil 1 102 230KV SHI TCHYARO 1X101 230KY 24KV 10101
230KV 1X105 13.$ 0t HONTOUR NNNTAIN iR105 1R106 (HSOS)
S/U TRANS 10 OX103 pi AUX QUQ S/U BUS pi 11A
1A101 OAIOV
04 OA10 02
- 04 OA106
ESS201 OX203 OX502 13.8KV 4.16KV 13.8KV 4.16KV OA502 OA501 OX@A 4 ~ 16KV 13.8KV 13.8KV 4 ~ 16KV ESS101 OX201 t7 ~
tQ (D 13t O
GD 6 (D O
ESS211 OX213 13.8KV 4.16KV 2A204
1A204
005010 A 00501 A ih 13.8KV 4.16KV ESS111 OX211 AC DISTRIBUTION NETWORK FIGURE 0
2A202
1A202
OGSOIB C
OCSOIC 1C 1A203 CKT BKR I
OPEN
~
.
.
g CKT BKR THO UNIT OPERATIONAL LINEUP SHOHN 411K C)
100%
LLI 75%
CCI Cl)
50%
25%
LLI CAPACITlR FAILS%
QLID-FAlLT LESS THAN 30 CYCLES RR 85X RELAYS PROPOSED 13 KV BUS VOLTAGE PROF ILE CP AFAULT SCRAM 1 89 03 0%
1
'3
5
7
TIME IN SECONDS
10
12
100%
QK RECIRC PLOP START LJ 75%
CC Cl 50%
25%
LLj 0%
1
3
5
7
TTkAC Thl C
C C Dhl&C
10
12
Attachment
Paae 16 of 21 Causes of Unit
&. Common Equipment Problems Undervoltage Relay Trips Aux 11 Transformer Trouble Alarm ESS 211 Transformer Trouble Alarm ESS 101 Transformer Trouble Alarm
"A" RB Chiller Tripped
"A" TB Chiller Tripped Stator Cooling Trouble Second Pump Started
"E" DG Trouble (OB566 Undervoltage).
Seal In Dropouts Containment Purge HV-15713 Closed
"A" Containment Valves Closed - Dual Indication
"A2" CRM Pump Tripped Contactor Dropouts RWCU Pumps A
& B Tripped Fuel Pool Pumps Tripped Steam Packing Exhauster
"A" Tripped Supp Pool Filter Pump Tripped Ec Valves Stayed Open Lube Oil Transfer Pump 1P143 Tripped Unit 1
& Common GRRCCW Pumps Tripped Process Signal Trips Lube Oil Centrifuge Tripped
"C" RFP DC Oil Pump Started All RFP AC Oil Pumps Running Standby RBCCW "A" Started Degassifier Tripped Other SDV Trouble Alarm Normal Scram alarm.
Sealing Steam Condenser Panel Trouble Caused by SPE "A" trip.
Computer Problem DCP2
& Disagreement alarms are normal for cpmputer transfers during power system voltage transients.
Recirc "A" Motor Cooler Leak Alarm - Normal for short trip of Recirc pump.
Condensation forms on pump cooler due to loss of air flow and alarms as a leak.
"A" & "B" Recirc Pump Tripped Still under evaluatio Attachment
Paae 17 of 21 Causes of Unit, 2 Equipment Problems
"A" TQ Cgil.ler Tripped Undervoltage relay dropout.
CRM Pump Tripped Seal in dropout
"A" CAC Valves Closed Seal in dropout.
"A" TBCCW Auto Started Process signal started.
SPDS Console Isolated Isolation was 10 minutes after condensate pump trip and not caused by even LINDERVOLTAGE TRIP SCENARIO UV OTHER TRIPS CONTROL SMITCH CONTROL RELAY UV
- a m lb QPn 00 B (D O
UNDER VOLTAGE DROPS-OLIT START RELAY
RELAY SEAL-IN SCENARIO CI CE C3 SI TRIP SIGNALS MOMENTARY HAND SMITCH Ql ~
C~
CD Qln ED O D
+ C+
START COIL LOW VOLTAGE DROPS-OUT SEAL-IN RELAY CONTACTS
CONTAINMENT ATMOSPHERIC CONTROL OPEN ON INBOARD ISI.ATION HSX CC kh~
CLOSE SV SV SV SV SV INBOARD SAMPLE VALVES llF OFFAL-IN DEENERGIZES SOLENOID VALVES O 3o CQ rt
O 3 Ofl
CONTACTOR DROP-OLIT SCENARIO CONTROL SMITCH
42
MOTOR LOV VOLTAGE DROPS-QUT MAIN CQNTACTQR
l h J 0