IR 05000387/1998007
| ML17164A832 | |
| Person / Time | |
|---|---|
| Site: | Susquehanna  |
| Issue date: | 10/15/1998 |
| From: | NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| To: | |
| Shared Package | |
| ML17164A830 | List: |
| References | |
| 50-387-98-07, 50-387-98-7, 50-388-98-07, 50-388-98-7, NUDOCS 9810200195 | |
| Download: ML17164A832 (96) | |
Text
U.S. NUCLEAR REGULATORYCOMMISSION
REGION I
Docket Nos:
License Nos:
50-387, 50-388 NPF-14, NPF-22 Report No.
50-387/98-07, 50-388/98-07 Licensee:
Pennsylvania Power and Light Company 2 North Ninth Street Allentown, Pennsylvania 19101 Facility:
Susquehanna Steam Electric Station Location:
P.O. Box 35 Berwick, PA 18603-0035 Dates:
July 21, 1998 through August 31, 1998 Inspectors:
K. Jenison, Senior Resident Inspector J. Richmond, Resident Inspector A. Blarney, Resident Inspector D. Florek, Project Engineer C. Sisco, Senior Licensing Examiner J. McFadden, Radiation Specialist T. Moslak, Radiation Specialist W. Maier, Emergency Preparedness Specialist Approved by:
Clifford Anderson, Chief Projects Branch 4 Division of Reactor Projects 98i0200i95 98iOi5 PDR ADOCK 05000387
EXECUTIVE SUMMARY Susquehanna Steam Electric Station (SSES), Units 1 &. 2 NRC Inspection Report 50-387/98-07, 50-388/98-07 This integrated inspection included aspects of Pennsylvania Power and Light Company's (PPS.L's) operations, engineering, maintenance, and plant support at SSES.
The. report covers a 6-week period of resident inspection; in addition, it includes the results of announced inspections by regional operator licensing specialists, regional radiation specialists, and a regional emergency preparedness specialist.
~Oerations
~
The licensee conducted plant operations in accordance with SSES procedures, and established effective equipment alignment and operability. The alignment of the Ultimate Heat Sink, Reactor Water Cleanup and Transverse Incore Probe systems
'as determined to be adequate.
The material condition of both units was adequate.
(Section 01.1)
On July 2, 1998, a Unit 2 scram during plant startup occurred due to poor reactivity control management.
Procedures did not contain sufficient restrictions for reactivity manipulations of Group 2 control rods, operating crew team dynamics and shift management and supervisory oversight were not effective in preventing the scram.
After criticality but before the point of adding heat was achieved, control rod withdrawals were stopped for about 60 minutes.
During this time, core decay heat caused reactor coolant temperature to increase, returning the core to a subcritical condition. With the core now subcritical, and lacking specific procedural restrictions, a Plant Control Operat'or (PCO), with approval of the senior reactor operator responsible for reactivity management, continuously withdrew a Group 2 control rod. The continuous rod withdrawal caused relatively high reactivity addition and power increase rates.
Two PCOs attempted to up-range intermediate range monitors (IRMs) to keep the IRMs on scale.
Each PCO down-ranged an IRM, in error, resulting in a reactor scram.
(Section 01.2)
PPSL failed to promptly identify and take corrective actions for a significant
'ondition adverse to quality that could have prevented the July 2, 1998 reactivity control scram event.
PPRL failed to initiate a condition report following a June 26, 1998, reactivity control event in which continuous Group 2 rod withdrawal caused a relatively high reactivity addition rate and a corresponding high rate of power increase which required operator action to mitigate.
On July 2, 1998, a similar Group 2 control rod withdrawal led to a reactor scram.
The failure to initiate a condition report was a violation of 10CFR 50 Appendix B Criterion XVI. (Section 01.2)
~
PPS.L's initial corrective actions following the Unit-2 scram on July 2, 1998, were adequate, including the activities of the Event Review Team, Plant Operations Review Committee, and Independent Safety Engineering Group.
(Section 01.2)
Executive Summary (cont'd)
Based on inspector review of a sample of 38 Operability Determinations (ODs) and Condition Report (CR) action items, PPRL adequately identified degraded conditions on safety related equipment, adequately initiallyresolved the degraded condition, and if appropriate, developed adequate long term corrective actions.
(Section 04.1)
The startup training portion of the SSES licensed operator re-qualification program'as adequate, However, on July 2, 1998, operators departed from the startup training by using two Plant Control Operators to operate, the intermediate range monitor range switches, PPRL training and condition report action items on training in support of the July 3, 1998, startup were adequate.
(Section 05.1)
PPRL identified that the primary coolant degasifier exhaust treatment system may have been degraded, due to water intrusion and wetting of the charcoal filter, and had not been surveillance tested, as required by Technical Specification.
The licensee's corrective actions were adequate.
This non-repetitive, licensee identified and corrected violation is being treated as a non-cited violation. (Section 08.1)
PPSL identified that the position indication for some primary containment isolation valves had not been tested as required by Technical Specifications.
The licensee's corrective actions were adequate.
This non-repetitive, licensee identified and corrected violation is being treated as a non-cited violation. (Section 08.1)
PP&L identified that a fire barrier wall in the emergency diesel generator building was not included in fire protection surveillance procedures.
The licensee's corrective actions were adequate.
This non-repetitive, licensee identified and corrected violation is being treated as a non-cited violation. (Section 08.1)
PPKL identified that a portion of Residual Heat Removal system logic had not been surveillance tested, as required by Technical Specification.
The licensee's corrective actions were adequate.
This non-repetitive, licensee identified and corrected violation is being treated as a non-cited violation. (Section 08.1)
PPRL took adequate initial corrective actions for a non-conservative ultimate heat sink (UHS) Technical Specification (TS) surveillance requirement that resulted from a PPRL evaluation.
However, since the PPSL TS surveillance requirement acceptance criteria for key UHS parameters do not consider instrument measurement uncertainty in establishing the acceptance criteria, an unresolved item was identified to review a PPSL assessment of margins available in the UHS analysis and a PPRL.
'assessment of measurement uncertainty as applied to the surveillance procedures.
(Section 08.3)
Maintenance
~
Based on inspector review of twelve activities, pre-planned maintenance and surveillance activities were found to be appropriately conducted and controlled.
(Section M1.1)
Executive Summary (cont'd)
The licensee's presentation of training to the offsite emergency response agencies was good and included all the topics required by NRC regulations. (Section P8)
The solid radioactive waste management program was effective based on proper implementation of the program by knowledgeable personnel, the existence of appropriate procedures and controls, and the acceptable condition of facilities and equipment.
The Process Control Program was complete, detailed, and provided an accurate description of the waste types generated; waste stream sampling and analyses performed, and waste processing methods used. (Section R1.1)
The program to transport low level radioactive waste and other radioactive materials was generally effective.
The shipping manifests and supporting documentation were properly prepared, radiation and contamination limits were met, waste was properly classified, and shipments were properly typed as to their Department of Transportation class. (Section R1.2)
The NRC and Department of Transportation training and retraining requirements for radioactive waste group personnel were met.
While overall performance was effective, compensatory measures were initiated to assure that personnel training and qualification in the use and application of programs and procedures used to document waste shipments, and classify waste type, was sufficient. (Section R5)
The self-assessment and corrective action programs, in the area of radioactive waste and radioactive material transportation, were effective'. The Technical Specification required audit was extensive in scope and depth, and surveillance and quality control inspections identified items for enhancement and corrective action.
The threshold for generation of condition reports was low. (Section R7)
1
SUMMARY GEORGE T. JONES
Mana ement Pers ectives CONSERVATIVEDECISIONS Questions Raised on Standby Liquid Control System (SLCS)
Susquehanna Site
- Restore
- Prevent Recurrence Engineering
- Review and Confirm SLCS Requirements Independent Assessments Evsioste PPaL Response De(ennhe Compliance wiNA'tWS Rufe Cj
0
Management Perspectives CoNsERvATIvE DEcIsIor4s Qusadons Ralssd on Standby Urtuld Control Systs
{SLCS)
Vg
Management Perspective
~ SLCS was and has been operable and met AlWS requirements.
~
Initial actions taken were conservative and consistent with regulatory guidance. '
We have captured all ATWS rule requirements in our field procedures.
~ 'issues highlight need for clear documentation.
>> Willintegrate into our CLB projec Management Perspective
'cont'd.)
~ Maintenance procedure improvement is a department priority.
>> We expect vendor information to be appropriately translated into Maintenance procedures.
>> In this case, our prior experience was not translated into the procedure.
~ -CR program entered when appropriate.
~ Charging of accumulator does not affect the test results.
>> Prudent prerequisite considering function.
Lessons Learned
~ Design documentation detail.
~ Application ofvendor recommendations into Maintenance procedures.
~ Condition reporting.
~ Engineering evaluation Agenda MANAGEMENTPERSPECTIVES GEORGE T. JONES SYSTEM DESIGN AND EVALUATION GLENN D. MILLER OPERATIONS AND MAINTENANCE GEORGE J. KUCZYNSKI CONSERVATIVEACTIONS SUMMARY GEORGET. JONES System Design 8z Evaluation
~ Technical Issue
~
SLC System Design Overview
>> SLCS Original Design Basis
>> SLCS Accumulator Design
>> ATWS Rule Implementation
>> Power Uprate Implementation
~
Engineering Evaluation
>> Overview
>> Conclusions
System Design &Evaluation
~
Technical Issue:
>> Do pressure pulses from the positive displacement SLCS pumps divert flow from the RPV by liftingthe relief valve'
>> Is the SLCS accumulator needed to prevent the pressure
'ulses (or pressure waves) from liftingthe relief valve'
>> Is the SLCS accumulator function required for system operability',
SLCS Original Design Basis
~
Functions as diverse backup to CRD System.
~
System performs a function "Important to Safety", but is not required to be safety related.
~
Single pump operation:
>> Two 100% capacity pumps/manual initiation.
>> 41.2 gpm 12.6 wt % boron.
>> design assures 660 ppm in RPV in 90-120 minutes:
achieves cold shutdown with all rods out
~
Accumulator function was to dampen pressure pulsations to reduce vibration SLCS Accumulator
'
Purpose:
>> Dampen pressure pulsations to reduce vibrations on piping systems.
~
In the late 1960's, a piping failure at a European BWR led to the following SLCS improvements:
>> Heavier wall piping,
>> Triplex or quintiplex pumps,
>> Added accumulators to dampen piping vibration.
~
BWR plant testing in 1968 on a SLC system similar to SSES:
>> Magnitude of pulsations is effectively unchanged with or without accumulators.
ATWS Rule (10CFR50.62)
Implementation
~
PPBL implemented two pump SLCS operation:
>> 82.4 gpm O13.6wt%:
~
Two pump operation increases system pressure.
>> Relief valve tolerance changed from 1400 psig s 3% to 1400 psig +3%, -0%
>> Test shows LTR margin to relief valve setpoint satisfied
>> LTR margin accounts for pressure pulsations therefore
. accumulator not needed to prevent relief valve lifting
~
Current Technical Specifications remain based on original design.
~
Documentation on need for accumulator during system operation not establishe Power Uprate Implementation
~
Reactor operating pressure increased:
>> SLC system pressure increase evaluated by GE and found acceptable.
>> No reliance placed on accumulator to prevent relief valve from lifting.
~
Reactivity requirement for cold shutdown conditions unchanged:
>> Cycle specific analyses show requirement is met.
~
Documentation on need for accumulator during system operation not established.
SLCS SIMPLIFIEDDIAGRAM TEST TANK ACCLPELATCR le RELIEF VALVE HAO EXPLOSIVE VALVE PIMP IA STORAGE TAN<
ACCQEAATM RELIEF VALVE RAO EXPLOSIVE VALVE
Evaluation Overview
~
Prior to 9/9/97:
>> Accumulator viewed as functioning to dampen pressure pulsations to reduce vibration.
~
Subsequent to 9/9/97:
>>
Engineering questions function ofaccumulator and conservatively assumes accumulator needed.
>> Design function of accumulator was known, however.
magnitude of pressure pulsations not described, inconclusive as to effect on system operability, concern was relief valve opening resulting in flowdiversion, engineering conservatively determined that accumulator was required based on level of understanding at that time.
~
Engineering commences detailed review of need for accumulator.
Evaluation Overview
~
Determine the magnitude of pulsations.
>> Initial magnitude estimated as high
~
Determine potential effects of pulsations on relief valve operation.
~
Assess impact of degraded SLCS performance on overall plant response to ATWS:
>> Analysis results reviewed with NRC Residents,
>> Developed followwn actions including detailed system analysis.
~
Determine overall effect on system considering system interactions.
>> Final evaluation shows accumulators not required for system operabilit Evaluation - Overview
~
More extensive investigation revealed:
>>
GE test results with and without accumulator.
~ negligible differences in piping vibration
>> ATWS LTR pressure margins were met.
>> Power uprate evaluation of pressure margin acceptable.
>>
Need to consider system effects which reduce magnitude of pulsations.
~
System effects show:
>> Reactor vessel acts like an accumulator.
>> Friction losses in piping willattenuate pressure pulses.
>> Pressurized reactor vessel willact to smooth pressure pulses.
>> Relief valve is located on a branch line which willsee reduced pressure pulses.
Evaluation Conclusions
~
Conclude that original design statement is correct.
~
SLCS accumulator not required for system operability:
>> SLC system is not dependent upon the'accumulator to meet Technical Specification and ATWS Rule requirements:
only function is to dampen vibration due to pressure pulsations (or pressure waves)
~
>> The design purpose ofthe accumulator was dearly identified in the original design documentation, however its role in SLCS operation could have been more clearly defined.
~
Conservative decisions made throughout process.
~
Documentation enhancements neede k
Evaluation - Conclusions
~ Technical Issue:
>> Pressure pulses from positive displacement SLCS pumps do not divert flow from RPV by lifting the relief valve.
>> The SLCS accumulator is not needed to prevent pressure pulses (or pressure waves) from liftingthe relief valve.
>> The SLCS accumulator function is not required for system operability.
Agenda MANAGEMENTPERSPECTIVES GEORGE T. JONES SYSTEM DESIGN AND EVALUATION GLENN D. MILLER OPERATIONS AND MAINTENANCE GEORGE J. KUCZYNSKI CONSERVATIVEACTIONS SUMMARY GEORGE T. JONES
Timeline Historical
~
Prior to 4/22/91 Routine surveillance activities. Maintenance support proceduralized for bladder pressurization.
~
4/2281 RIEE 91-0106 approved replacing schrader valve and bladder for the 1T207NB and 2T207B accumulators. Solves need to take LCOs.
~
9/08/92 SOOR 2-92-085 written to document that the "B" SLCS pump was declared inoperable when its associated accumulator was found depressurized.
The reason that the pump was declared inoperable on this occasion was because the bladder needed to be changed and the pump had to be isolated from the SLCS tank to perform the work.
Timeline - Recent
~
9/09/97 Event: NRC questions operability: QA questions LCO issue.
CR 97-2958 written.
~
Engineering begins review of SLCS accumulator design basis.
~
9/10/97 CR 97-2973 written to identify potential pre-conditioning.
~
10/07/97 EWR M70463 written to Nuclear Technology to determine function of the accumulators.
~
10/27/97 PCAF 1-97-6695 issued to MT-053-003, SLCS accumulator maintenance.
PCAF adds precautions that accumulator needed for operabilit t
Timeline Recent
~
11/19/97 Accumulator precharge checks increased to monthly.
First checks performed on unit 2. Both accumulators'ressure satisfactory, but schrader valve on B accumulator leaks following charging.
LCO entered, Valve replaced.
CR 97-3810 written.
~
1&21/97 Unit 2 B accumulator bladder develops leak. Bladder replaced.
CR 97-3845 written.
~
11/24/97 S0-253-004 revised to resolve potential pre-conditioning activities.
~
11/2&97 Event: Both ALBSLCS accumulators found with pressure below specified ranges. CR 97-3888 written.
~
11/2&97 Accumulator pressure checked on both units. Allfour found acceptable.
Timeline Recent
~
11/28/97 Accumulator pressure checked on both units. Allfour found acceptable.
~
12/01/97 Accumulator pressure checked on both units. One accumulator found at 1010 psi. Both Unit 2 accumulators recharged.
CR 97-3924 written.
~
12/02/97
>>
11/2&97 Event reported via ENS as loss of a safety function.
CR 97-3932 written.
>> Nuclear Engineering informs Systems Engineering that the accumulators are required forpump operabilit Timeline - Recent
~
12/03/97 Unit 2 accumulator pressure found high.
Depressurized to acceptable range.
CR 97-3941 written.
~
12/04/97 Quarterly flowsurveillance, SO-153-004, successfully fun.
~
12/05/97 Accumulator pressure checked on both units. Ailfour found acceptable.
~
12/12/97 Accumulator pressure checked on both units. Allfour found acceptable.
~
12/19/97 Accumulator pressure checked on both units. Allfour found acceptable.
Timeline - Recent
~
12/26/97 Accumulator pressure checked on both units. One Unit 2 accumulator found low after Mechanic had trouble seating the gauging tool. Accumulator recharged.
CR 97-4140 written.
~
1/02/98
'
Accumulator pressure checked on both units. Schrader valve stem broke while installing the gauging tool. Schrader valve replaced.
CR 98-0009 written. Decided on a two week pressure check frequency.
>> LER 97-025-00 submitted to NRC reporting that both trains of SLC were determined inoperable on 11/25/9 Timeline Recent
~
1/%$ 8 Calculation EC-053-1001 approved. revising the acceptable accumulator pressure range from 1020-1085 psig to 875-1085 psig.
~
1/16/98 Accumulator pressure checked on both units. Allfour found higher than normal range.
Depressurized to 1065 psig.
CRs 98-0166, -0167, -0168, and -0169 written.
~
1/30/98 Accumulator pressure checked on both units. Allfour found acceptable.
~
2/04/98 NRC Inspection Report 97-10 Issued, opening unresolved item to track the SLC accumulator depressurization event.
~
2/13/98 Accumulator pressure checked on both units. Allfour found acceptable.
Timeline - Recent
~ K4/98-3-28/98 Installation of permanent local pressure indication and positive shutoff valves per modification program.
Daily check of accumulator pressure added to operator rounds.
~
3/13/98 PLA-4870 written to NRC as PP8L's initial response to the SLCS unresolved item.
~
4/30/98 PP&L concludes that the SLCS accumulators are not required for SLCS operabilit Operations and Maintenance Initial Conservative Actions
>> Restored SLCS to known operable condition.
>> Increased monitoring frequency accumulator pressure.
>> Performed root cause analysis of depressurization.
>> Revised procedure for tightening valve caps.
>> New valve caps installed.
>> Reviewed event with Maintenance personnel.
>> Performed modifications.
Permanent pressure modification on accumulators.
Replaced valves with positive shutoff valves.
PPEzL Assessment of Apparent Violation 98-01-06
~
EEI 98-01-06
>> SLCS accumulator pressure discovered below acceptable range.
>> No Condition Report initiated.
~ Assessment
>> Prior to 9-9-97 - Accumulators considered not required for SLCS safety function.
>> 9-9-97 to 4-98 - The need for the accumulator was in, question. A CR conservatively initiated for each occurrence where an accumulator found outside its required pressure ban PP8zL Assessment of Apparent Violation 98-01-06 Assessment
<cont'd.)
>> Checking/charging was planned and done as routine surveillance support.
Not considered a discrepancy.
>> This was not symptomatic of a threshold too high for CR initiation.
>> Post 4-98 - PP8L determines the accumulator not required for Tech Spec or ATWS rule compliance.
>> The CR program was entered when appropriate.
When the need for an LCO was questioned.
When accumulator pressure found low during time when need foraccumulators in question PPRL Assessment of Apparent Violation 98-01-06 Assessment (Cont'd.)
>> The process is capturing the right issues and meets the requirements of Appendix B.
>> Beyond Appendix B, the organization is conservative on CR initiation. CR's are written when anyone sees a
'situation that is not expected.
>> Had the need for the accumulator been questioned on previous events, a CR would have been entere PP&L Assessment of Apparent Violation 98-01-07
~
EEI 98-01-07
>> Procedures controlling the SLCS maintenance activities were not adequate to ensure the accumulator charging valve cap installed in accordance with the vendor's instructions.
~ Assessment
>> PPBL expectations are that vendor instructions be specifically referenced or included in maintenance procedures, factoring in our experience and engineering input.
PP&L Assessment of Apparent Violation 98-01-07
~ Assessment (cont'd.)
>> The Maintenance procedure MT-053-003 did not fully meet PP&L expectations, but the differences were subtle:
Vendor instruction states:
"Replace cap and twist one half turn beyond hand tightness."
Maintenance procedure stated: "Replace valve cap on accurnuIator."
>> Corrective action was taken to incorporate the vendor information and our experience into MT-053-003.
>> Installed modification to improve the design, removing the need for multiple maintenance activitie PP &LAssessment of Apparent Violation 98-01-07
~ Assessment (cont'd.)
>> Broader corrective actions were underway that bound this issue.
>> We'e identified opportunities to improve the Maintenance program in the areas of planning and procedures.
PP8zL Assessment of Apparent Violation 98-01-07
~ Assessment (cont'd.)
>> Administrative controls for usage of vendor instructions being revised.
>> Focus seminar of Maintenance planners with other key personnel conducted to improve the quality of the work packages in the field.
>> Self-assessment and feedback processes being strengthened, including worker feedback checklists.
>> Overall planning improvement plan in progres I
PP&L Assessment of Apparent Violation 98-01-08
~
EEI 98-01-08
>> SLCS Surveillance Test specified that maintenance personnel pre-charge the accumulator.
>> This resulted in SLCS pump being tested in condition
'ifferent from as-found condition.
PP &LAssessment of Apparent Violation 98-01-08
~
Upon further evaluation, recharge of accumulator not "Pre-conditioning". Accumulator not required to meet Technical Specification or ATWS Rule requirement, nor is it needed for SLCS to perform its design basis function.
~
Checking / charging the accumulator is a prudent prerequisite considering its function - only to dampen pressure pulsation from the SLCS pumps.
~
Checking/charging the accumulator does not affect SLCS testing or data gatherin Sumxnary: Response to Apparent Violations
~ Questions on need for accumulator led to prompt conservative actions.
~ CR Program requirements were met.
~ PP8 L expectations were not fullymet in MT-053-003.
~ Pre-conditioning did not occur on accumulators.
Agenda MANAGEMENTPERSPECTIVES GEORGE T. JONES SYSTEM DESIGN AND EVALUATION GLENN D. MILLER OPERATIONS AND MAINTENANCE GEQRGE J. KUczYNsKI CONSERVATIVEACTIONS SUMMARY GEORGE T. JONES
e
Summary
~ SLCS was and has been operable and met ATWS requirements.
~
Initial actions taken were conservative and consistent with regulatory guidance.
~ We have captured all ATWS rule requirements in our field procedures.
~
Issues highlight need for clear documentation.
>> Willintegrate into our CLB project.
Suimrrtary (cont'd.)
~ Maintenance procedure improvement is a department priority.
>> We expect vendor information to be appropriately translated into Maintenance procedures.
>>
In this case, our prior experience was not translated into the procedure.
~ CR program entered when appropriate.
~ Charging of accumulator does not affect the test results.
>> Prudent prerequisite considering functio