IR 05000317/1990009
| ML20044A649 | |
| Person / Time | |
|---|---|
| Site: | Calvert Cliffs  |
| Issue date: | 06/19/1990 |
| From: | Cowgill C NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| To: | |
| Shared Package | |
| ML20044A646 | List: |
| References | |
| 50-317-90-09, 50-318-90-09, NUDOCS 9007020012 | |
| Download: ML20044A649 (15) | |
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I U.S. NUCLEAR REGULATORY COMMISSION
REGION I
50-317/90-09
Report Nos.:
50-318/90-09 DPR-53 License Nos.:
DPR 69 Licensee:
Baltimore Gas and Electric Company Post Office Box 1475
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Baltimore, Maryland 21203 Facility:
Calvert Cliffs Nuclear Power Plant, Units 1 and 2 Location:
Lusby, Maryland Inspection conducted:
April 29, 1990 through June 2, 1990 Inspectors:
Larry E. Nicholson, Senior Resident Inspector Allen G. Howe, Resident Inspector Tae J. Kim, Resident Inspector Approved by:
b f(Al M E b /
Curtis J. C6111/ Chief date
Reactor Projects SerAion No. lA Division of Reactor Projects Inspection Summary:
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This inspection report documents routine and reactive inspections during day and backshif t hours of station activities including: plant operations; radio-logical protection; surveillance and maintenance; emergency preparedness; security; engineering and technical support; and safety - assessment / quality verification.
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Results:
No violations were identified.
One unresolved item was identified regarding the overall condition and performance of the salt water system (Section 7.1).
An Executive Summary follows.
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ADOCK 030oo337 PDC J
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EXECUTIVE SUMMARY I
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Plant Operations (Modules 71707, 93702) The operations staff was found to have adequate knowledge and sensitivity -regarding the risks involved with reduced reactor coolant system inventory operation.
Good procedures and contingency plans were observed to deal with this abnormal plant condition, j
Radiological prote: tion (Module 71707) Good containment health physics support and control was observed during outage activities. Routine review in this area-identified no noteworthy findings.
Surveillance and Maintenance (Modules 61726, 62703) Good effort was observed
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in correcting minor electrical penetration deficiencies, although some sub-
.l standard work practices were observed.
Various surveillance tests were
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observed and reviewed with no deficiencies noted.
Emergency preparedness (Module 71707) Routine review in this area identified
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no noteworthy findings.
Security (Module 71707) Routine review in this area identified no noteworthy findings.
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Engineering and Technical Support (Modules 71707, 90712, 92700) System engi-i neering was slow to recognize the significance.of the' heat exchanger fouling.
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Subsequently, significant effort has been expended to resolve the problem.- The l
NRC remains concerned about -the salt water system problems and will closely
follow licensee efforts to resolve the issue.
Various other> engineering
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projects were monitored with no deficiencies noteo.
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Safety Assessment / Quality Verification (Modules 71707,30703) Routine review in-
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this area revealed no noteworthy finpings.
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DETAILS 1.
Summary of racility Activities Unit I remained in cold shutdown for the duration of the inspection period for a planned maintenance outage.
Major activities included-steam gener-ator eddy current testing, reactor coolant pump seal replacement and gen-
eral plant maintenance.
Unit 2 remained defueled for the extended Cycle 8 refueling outage with
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the fuel in the spent fuel pool.
Repair of pressurizer heater penetra~
tions continued throughout the inspection period.
2.
Plant Operations
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2.1 Operational Safety Verification The inspectors routinely observed plant operation and verified that the facility was operated safely and in accordance with licensee procedures and regulatory requirements. Regular tours were conducted of the following plant areas:
-- control room
-- security access point
-- primary auxiliary building
- protected area fence
-- radiological control point
-- intake structure
-- electrical switchgear rooms
-- diec,i generator rooms
-- auxiliary feedwater pump rooms -- turbine building Control room instruments and plant computer indications were observed for correlation between channels and for conformance with technical specification (TS) requirements.
Operability of engineered safety features, other safety related systems and onsite and offsite power sources was verified.
The inspectors observed various alarm condi-tions and confirmed that operator response was in accordance with plant operating procedures.
Routin, operations surveillance testing was also observed. Compliance with TS and implementation of appro-priate actier. 5tatements for equipment out of service was inspected.
Plant rea1ation monitoring system indications and plant stack traces were reviewed for unexpected changes.
Logs and records were reviewed to determine if entries were accurate and identified equipment status-or deficiencies..These records included operating logs, turnover i
sheets, system safety tags, and the jumper and lifted lead book.
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Plant housekeeping controls were monitored, including control and storage of flammable material and other potential safety hazards.
The inspector also examined the condition of various fire protection,
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meteorological, and seismic monitoring systems.
Control room - and shift manning were compared to regulatory requirements and portions of shif t turnovers were observed.
The inspectors found that rontrol
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room access was properly controlled and a professional-atmosphere was
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maintained.
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In addition to normal utility working hours, the review of plant r
operations was routinely conducted during evening and weekend shifts.
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Extended coverage was provided for 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> during evenings and 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> during nights and weekends. Operators were alert and displayed no signs of fatique or inattention to duty.
2.2 Followup of Events Occurring. During Inspection Period
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During.the inspection period, the inspectors provided onsite coverage and follow-up of unplanned events.
Plant parameters, performance of safety systems, and licensee actions were reviewed.
The inspectors confirmed that the required notifications were made to NRC.
During event follow-up, the inspector reviewed the corresponding CCI-118N (Calvert Cliffs Instruction, " Nuclear Operations Sect"n Initiated Reporting Requirements" documentation, including the event details, root cause analysis, and corrective actions taken to prevent recur-rence. The following events were reviewed, a.
Saltwater Pipe Leak On May 4,1990, an operator observed a leak in the discharge
piping of saltwater pump No. 13.
The corresponding saltwater header was isolated and the redundant train placed in service.
On May 5,1990, the licensee requested a temporary waiver of compliance f rom a limiting condition for operation to allow the defective salt water header to be returned to service to facil-itate cleaning of the redundant header heat exchanger.
The licensee was granted the request and the evolution was completed in approximately one hour. Details regarding the saltwater pipe
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l leak and the necessity to clean 6 heat exchangers ~on a fre-quent interval are discussed in paragraph 7.1 of this report, b.
Excessive Containment Penetration Leakage On May 8,1990, the licensee notified the NRC that the combined leakage rate for all penetrations and valves subject to type B and C tests had exceeded the allowable TS limit.
The overall combined leakage measured to date was determined to be 299,925 l
standard cubic centimeters per minute (SCCM) versus a maximum TS limit of 207,600 SCCM.
The licensee notified the NRC pursuant
to the reporting requirements of 10 CFR 50.72,b.2.i. -The major contributor to the total leak rate was the "as found" test of MOV-651 and MOV-652 (shutdown cooling return isolation valves).
The "as found" rate was measured at 143,044 SCCM.
These valvas
were repaired before operation of unit one in April 1990.
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repairs made were primarily adjustments to the closing limits of the operators.
The post maintenance "as lef t" test was 12,874 SCCM. Two other valves that exceeded individual allowable leak l
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rates will be repaired during the current outage. No unaccept-able conditions were identified.
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2.3 Review of Mid-loop Operations The licensee placed unit 1 in reduced inventory operation on May 7, 1990 to support steam generator eddy current testing and reactor coolant pump seal. repairs. Prior to inventory rtduction, the inspector reviewed the licensee's controls for operation with reduced reactor coolant system (RCS) inventory.
Procedure OP-5 " Plant Shut-down From Hot Standby to Cold Shutdown", Appendix 5 Revision 32, provides controls for this operation.
Within the scope of expedi-tious actions and the licensee's plans for long term actions, OP-5 incorporates the recommendations of Generic Letter 88-l'/ for contain-ment closure capability, RCS temperature and level indication, avoid-ance and control of RCS perturbations, RCS inventory addition, and adequate RCS venting while installing steam generator nozzle dams.
Implementation of portions of this procedure _ was independently ver-ified by the inspector.
In performing the verification, the control room operating staff demonstrated a strong knowledge of the proced-ures and requirements for reduced inventory operation. The operators were also familiar with contingency actions and procedures for restoring from a loss of shutdown cooling, loss of RCS inventory, and loss of power to the emergency busses.
The inspector also discussed the nozzle dam installation and removal process with the licensee and ooserved the mock-up used for training the installers.
No unaccept-able conditions were noted.
2.4 Review of Work Inside _ C_ontainment
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The inspector toured the unit I containment building on May 9,1990, to observe ongoing outage activitics and health physics (HP) support.
l Good control of personnel access to the containment was noted.
On the 69' elevation ins'de the containment,- on-shif t HP technicians were available at all times to support outage activities.
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I housekeeping inside the containment, including specific job sites, was adequate.
No unacceptable conditions were noted.
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Radiological Controls During routine tours of the accessible plant areas', the inspectors ob-served the implementation of selected oortions of the licensee's Radio-logical Controls Program.
Utilization and compliance with special work l
permits (5WPs) were reviewed to ensure detailed descriptions of radiolog-ical conditions were provided and that personnel adhered to SWP require-ments. The inspectors observed controls of access to various radiolog-itally controlled areas and use of personnel monitors and frisking methods I
upon exit from these areas. Posting and control of radiation areas, con-taminated areas and hot spots, and labelling and control of containers holding radioactive materials were verified to be in accordance with licensee procedures.
Health Physics technician control and monitoring of these activities were determined to be adequate.
No unacceptable condi-tions were identified.
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4.
Maintenance and Surveillance 4.1 Maintenance Observation
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The inspectors observed maintenance activities, interviewed person-nel, and reviewed records to verify that work was conducted in ac-cordance with approved procedures, Technical Specifications, and applicable industry codes and standards.
The inspectors also verif-ied that:
redundant components were operable; administrative con-trols were followed; tagouts were adequate; personnel were qualified; correct replacement parts were used; radiological controls were pro-per; fire protection was adequate; quality control hold points were adequate and observed; adequate post-matntenance testing was per-formed; and independent verification requirements were implemented.
The inspectors independently verified that selected equipment was properly returned to service.
Outstanding work requests were reviewed to ensure that the licensee gave appropriate priority to safety-related mainti.-nance. The inspec-tors observed / reviewed portions of the following maintenance activities, a.
Electrical penetrations The in,pector observed the repair of defects in the containment electrical penetration IZWC6 in accordance with maintenance order 200-092-409C.
The licensee had previously discovered numerous minor deficiencies in the lugging and terminations inside the containment penetrations. The defects were generally determined to have originated during new construction and included nicked or broken strands, wrong lug size. and bad crimps. The inspector concluded that the repair was being per-formed in accordance with an approved procedure. Each terminal within the penetration was being removed and examined for defects, with defective terminals being replaced. This effort was noted as an example of good comprehensive corrective action to an identified problem.
A poor work practice was observed regarding the mechanics sitting in the electrical cable trays to perform this work.
In addition, work practices regarding wire
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marking and the need to san e. the removed defective lugs were unclear to the craft at the jobsite.
These observations were relayed to the maintenance department management.
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Later in the inspection period, the inspector observed thq repair of defects in containment penetration 12WE2 in accordance with maintenance order 200-114-597C.
The inspector observec that the workers were sitting on a platform designed to fit over the electrical cable tray rather than sitting in the cable tray as previously observed.
The repair included the replacement of all terminations as experience gained on previous repairs demon-strated that this method was more ef fective. The inspector con-cluded that this repair was performed in accordance with approved procedures, b.
Saltwater Air System Modifications The inspector observed portions of the installation of saltwaur air system tubing to various safety related valves in the Unit 2 component cooling water room. The work was performed in accord-ance with maintenance order 200-120-776A.
The inspector con-cluded that the indallation was performed in accordance with approved procedures.
The inspector observed that while clean-11 ness was generally maintained on the tubing internals via taping the open ends, methods.to maintain cleanliness were
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inconsistently applied for tubing staged at the jobsite for fabrication. Some of this tubing was not stored with both ends covered.
The inspector discussed cleanliness controls with the licensee and contractors performing the work and determined that methods and practices w'ere adequate to maintain or establish cleanliness prior to final installation. No unacceptable condi-tions were noted.
c, Closeout of Unit 2 Pressurizer
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l In preparing for closeout of the Unit 2 pressurizer, the licen-see performed an inspection via a remote controlled video
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I camera.
As a result of this inspection, the licensee deter-mined that an entry would be required to remove the debris found during the inspection. The licensee constructed a mockup of the pressurizer bowl to train personnel for the entry.
Two pres-surizer entries were made to install scaffolding, clean the i
pressurizer internals, and to remove the scaf folding and clean-
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ing equipment.
The pressurizer was successfully cleaned and closed out per maintenance order 209-142-4023.
The inspector reviewed the results of the entries and discussed the evolution with the appropriate station personnel.
No unacceptable condi-tions were noted,
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d.
Motor Operated Valve (MOV_) Overhaul During this inspection period, the inspector observed MOV actu-ator overhaul and inspection activities which were conducted in accordance with maintenance orders (M0 No. 209-088-674B and M0 No. 209-088-702C).
Maintenance procedures MOV-1, " Inspection and Maintenance of Limitorque Motor Operated. Valve (MOV) Actu-ator SMB-000," and MOV-2,
" Inspection and Maintenance of Limitorque Motor Operated Valve (MOV) Actuator SMB-00," were part of the MOs which specified the steps to disassemble, inspect and reassemble Limitorque actuators.
Contractor personnel performed the MOs and.the licensee Quality Control (QC) staff provided QC inspection of the overhaul activ-ities.
The QC inspectors utilized job specific inspection pro-cedures which are based on the appropriate maintenance proced-ures.
The inspector concluded that both procedures, MOV-1 and MOV-2, were comprehensive and thorough.
The M0s clearly spec-i ified post-maintenance testing requirements including a signa-ture analysis (i.e., Votes).
The contractor maintenance per-sonnel were knowledgeable about the Limitorque operator main-tenance.
No unacceptable conditions were noted.
4.2 Surveillance Observation The inspectors witnessed selected surveillance tests to determine whether properly approved procedures were in use; technical specifi-cation frequency and action statement requirements were satisfied; necessary equipment tagging was performed; test instrumentation was in calibration ana properly used; testing was performed by qualified i
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properly dispositioned.
Portions of the following activities were reviewed, a.
STP 0-090-2 " Breaker Lineup Verification" b.
STP M-152-1
"No, 11 Station Battery Weekly Check" c.
STP 0-73C-1
" Component Cooling Water Pump Performance Test" d.
STP 0-087-1
" Borated Water Source Operability Verification" e.
STP M-571-1 " Local Leak Rate Testing" l
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STP M-574-1
" Eddy Current Exam of Calvert Clif f s Nuclear Power l
Plant Unit 1 Steam Generators"
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In addition to review of the surveillance activities associated with steam generator eddy current testing, the inspector reviewed licensee plans for examination of the tubes for circumferential cracks in the
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tube sheet area.
Further details of the result of this inspection are contained in NRC Inspection Report 50-317/90-11.
4.3 Receipt inspection of Control Element Assembly
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On May 7, 1990, the inspector observed the licensee's receipt inspec-tion of a new control element assembly (CEA) and subsequent fuel movement in the spent fuel pool to place the CEA in the appropriate
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fuel assembly.
The activities-were conducted in accordance with the station procedure, Fuel Handling (FH-48), Rev. 3., Appendix 0, "New CEA Handling and Inspection Procedure."
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The Appendix 0 to the procedure FH-48 had been added to facilitate the receipt of the replacement CEA. The Appendix directs the receipt inspection and handling of new CEAs and spent fuel pool (SFP) fuel
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movement in support of CEA-transfer.
The receipt inspection deter-mines whether or not there has been damage while in storage or during shipping which could degrade performance.
In addition, the receipt inspection provides an opportunity to make an early check of CEA resistance to travel in fuel assembly guide iub::
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Two qualified nuclear engineering personnel performed the receipt (
inspection in accordance with FH-48.
The inspector independently performed a visual inspection of end cap welds, finger surfaces, and I
end fittings of the CEA for porosity defects or foreign debris. The CEA was then transferred into a new fuel assembly guide tube for a friction test.
No problems were noted, i
Prior to the SFP fuel movement in support of the CEA transfer, the inspector noted that all precautions and prerequisites required by l
Technical Specifications for fuel movement were met.
All fuel
assembly movement was performed in accordance with Procedures FH-48
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and 01-25A.
All fuel movement was properly-documented in FH-48
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Appendix 0-2,
"The Special Nuclear Material Transfer Form," as required.
The inspector observed _ that the HP technicians provided
excellent support during the fuel movement.
No unacceptable condi-
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tions were noted.
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The inspectors routinely toured the onsite emergency response f acilities and discussed program implementation with the applicable station person-nel.
The resident inspectors had no noteworthy findings during this
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inspection period in this area.
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Security During routine inspection tours, the inspectors observed implementation of portions of the security plan.
Areas observed included access point search equipment operation, condition of physical barriers, site access control, security force staffing, and response to system alarms and degraded conditions.
These areas of program implementation were deter-mined to be adequate. No noteworthy findings were observed.
7.
Engineering and Technical _Su,pport
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The inspector reviewed selected design changes and modifications made to the facility which the licensee determined were not unreviewed safety questions and did not require prior NRC approval as described by 10 CFR 50.59. Particular attention was given to safety evaluations, Plant Oper-ations Review Committee approval, procedural controls, post-modification testing, procedure changes resulting from this modification, operator training, and UFSAR and drawing revisions, The following activities were reviewed:
7.1 Fouling _of Salt Water Heat Exchangey The inspectors reviewed the licensee actions regarding the opera-bility of the saltwater system.
This system provides cooling to the l
component cooling heat exchangers, the service water heat exchangers, l
and the emergency core cooling system (ECCS) room coolers. The salt-water system is needed to reject heat to the ultimate heat sink-(Chesapeake Bay).
Each unit has two independent saltwater trains with three pumps (one per train and a swing pump).
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On May 4,1990, an operator noticed an unisolable leak at a pipe
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flange-to pipe weld in the discharge piping of saltwater pump No. 13.
The af fected component was classified as ASME Code Class 3.
Isola-ting the leak required isolating the entire No. 11 saltwater. header.
The operating staff realigned heat loads to the No. 12 saltwater header and removed the No,11 header f rom service.
The section. of pipe containing the defect was removed and a f ailure investigation l
was ongoing as the inspection period ended.
The inspectors will l
review the failure analysis and accompanying corrective _ actions as
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part of the unresolved item listed below.
Prior to removing the defective pipe from the No, 11 salt water header, the licensee was required to place the header back into ser-vice to facilitate cleaning of the No.
12 service water heat exchanger. This evolution was the subject of a request for regional temporary waiver of compliance that was granted on May 5,1990.
The evolution also highlighted an existing inspector concern regarding excessive biological fouling and operability of the salt water heat exchanger.
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Due to seasonal increases in the rate of biolological fouling of salt
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water heat exchangers, the licensee began a program of cleaning the exchangers approximately every 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> based upon high saltwater differential pressure.
Large amounts of marine growth and shells were removed during cleaning.
This issue was placed on the Plant Operations and-Safety Review Committee (POSRC) agenda arid was the subject of several engineering presentations during the ir spection period.
The inspectors attended the presentations and noted that System i
Engineering was slow to recognize the operational significance of the heat exchanger excessive fouling rate. Eventually, at the request of the General Supervisor of Operations, they performed an engineering evaluation which demonstrated that the saltwater system was capable of performing its intended function while the reactor was shutdown in the current mode with containment open and at reduced RCS inventory.
A significant amount of engineering resources was devoted to this I
issue as the inspection period ended.
Further analysis indicated that a worst case total loss of salt water and an initial service water temperature of 95 degrees F may render the emergency diesel
generators inoperable in less than nine minutes. The inspectors will
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continue to review both the failure of the salt water pipe weld and the operational impact of increased marine fouling as an unresolved item (50-317/90-09-01 and 50-318/90-09-01).
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Safety Assessment an_d Quality Verification
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8.1 Plant Operations and Safety Review Committee-The inspector attended several Plant Operations and Safety Review Committee (POSRC) meetings,.
TS 6.5 requirements for required member attendance were verified.
The meeting agendas included procedural changes, proposed changes to the TS, Facility Change Requests, and
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minutes from previous meetings, items for which adequate review time was not available were postponed to allow committee members time for further review and comment, The inspector noted that presentations to POSRC were conducted in a formal and professional manner.
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all, the level of review and member participation was adequate in fulfilling the POSRC responsibilities.
8.2 _ Review of Written Reports The inspector reviewed Periodic and Special Reports, Licensee Event Reports (LERs), and Safeguards Event Reports (SERs) for clarity, validity, comprehensiveness, accuracy of the root cause and safety significance description, and adequacy of corrective action.
The inspector also verified that the reperting requirements of 10 CFR 50.73, 10 CFR 73.71, applicable station procedures, and Technical Specification 6.9 had been met.
The following reports were reviewed:
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l LER 90-07 Failure to Test Supervised Circuits Supervision Due
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to Omission of Circuits from the Surveillance Procedure
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LER 90-08, Inadequate Hydrogen Analyzer Calibration
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LER 90-09, Inoperable Fire Barrier Penetration
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LER 90-11, Power Operated Relief Valve Inoperability
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LER 90-12, Potential for Post-LOCA Boron Precipitation
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LER 90-13, Axial Shape Inder Channels Out of Specification
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LER 90-14, Delta T Channels Out of Specification
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LER 90-15, Inadequate functional Test of Reactor Circuit
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Breaker Shunt Trip Rel y Contact The issues discussed in I.ERs 90-11 through LERS 90-15 were reviewed in Inspection Report 50-317/90-08 and 50-318/90-08.
The inspectors had no additional questions regarding these reports.
9.
Followup of Previous Inspection Findings
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In response to the current number of outstanding inspection items and the age of some of tne items, the licensee has initiated efforts to address closeout and facilitate NRC review of these items.
Actions include the assignment of personnel to coordinate licensee completion of these items
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and submittal to the NRC for review, assignment of technical contacts to address inspector questions, and tracking of the status with periodic reports to management.
The inspector will follow these initiatives in future inspections.
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Licensee actions taken in response to open items and findings from pre-I vious inspections were reviewed, The inspectors determined if corrective
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l actions were appropriate and thorough and previous concerns were resolved, Items were closed where the inspector determined that corrective actions i
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would prevent recurrence.
Those items for which additional licensee I
action was warranted remain open.
The following items were reviewed.
- 9.1 [ Closed)UNR 50-317/87-17-01; 50-318/87-19-01 This issue involved the licensee discovery that certain Reactor Pro-tection System (RPS) setpoints associated with the unit 2 thermal I
margin / low pressure trip were not updated for cycles 4 through 7.
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subsequent analysis concluded that even though the as-found setpoints were non-conservative with respect to the setpoints specified by Combustion Engineering, the available conservatism in the overall analysis would have bounded the error and provided assurance that the plant operated safely.
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The inspector reviewed the associated letters, safety analysis,10 CFR 50.59 analysis and recomnendations and concluded that adequate corrective actions were perfornied.
This problem was discovered by a dedicated systems engineering group who recognized and challenged the incorrect setpoints. The dynamic compensation has since been removed as a setpuint of the thermal margin / low pressure trip circuit.
Therefore, this problem will nor recur.
This item is considered closed.
9.2 (Closed) Violation (50'-318/88-17-01)
This violation concerned the inoperability of Emergency Diesel Gener-
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ator (EDG) 21 which occurred. June 4 to June 6,1988.
The EDG was
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made inoperable when an operator placed the voltage regulator mode
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selector switch in " manual" (vice " auto" for operability) during a surveillance test and lef t the switch in this position when the test
was completed.
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The inspector reviewed the' circumstances that led to the event, analysis of the ef fects on EDG operation for various accidents, and the licensee's short-term corrective actions. These actions included counseling the operator regarding procedure adherence, additional training and procedure changes to alert operators about the effect of
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this switch position, and also to require periodic switch position verification.
A long term corrective action to install an alarm associated with this switch has been planned for implementation by the licensee. The inspector concluded that. these corrective actions are adequate.
The inspector had no further questions regarding this item.
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9.3 { Closed) Violation (50-317/89-03-03)
This violation concerned the startup of unit I without performance of the required reactor protective. system (RPS) manual reactor - trip l
functional test within the previous seven daysr This test was not performed due to an apparent administrative error that resulted in misplacing the last page of the functional test procedure (STP-0-6-1)
which contained the appropriate test steps.
l The inspector reviewed the completed and in progress corrective.
l actions and discussed these actions with cognizant licensee person-
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nel.
One of the actions included the addition of-purpose statements
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to procedures.
This action-was scheduled to be' complete. by l
January 31, 1991, The licensee's current projection 'is that the action will not be complete by this date and will sbbmit a revised.
schedule.
The inspector concluded that the completed and planned actions are adequate. This item is considered clos 9d.
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9.4 Closed UNR (50-317/87-06-02; 50-318/_87_-06-02)
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This item was opened pending completion of the licensee's root cause analysis of the 2-RV-439 relief valve inlet piping failures at Calvert Clif fs Unit 2.
Thermal relief valve 2-RV-439 provides over-pressure protection for the low pressure safety injection (LPSI) sys-tem.
The two failures of the 1/2-inch inlet piping to the relief valve which occurred in March and May of 1987 resulted in small cool-ant leaks which required temporary realignment of the shutdown cool-ing flow paths.
On March 24, 1987, the weld at the half coupling from the 6-inch LPS!
discharge piping header to the 1/2-inch nipple leading to 2-RV-439 had failed. As a corrective action, the licensee added an additional support on the 1/2-inch line.
On May 7,1987, the weld f ailed again in the same location and with the same failure mode.
Both of the failed inlet connections to 2-RV-439 were subjected to microscopic metallurgical examination by the l ice.15ee Materials Engir,eering and Analysis Group. These examinations revealed that the microstructure of the connections was that of a typical 304 stainless stee'.
The material chemistry of the weld base metal was within spec fications. No indications of latent welding or material defects were found that could be responsible for the f ailures, it was con-
cluded from the microscopic examinations that both failures were due
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to f atigue.
The loading was a combination of torsion and bending.
On May 23,1987, the inlet piping to 2-RV-439 was replaced with a redesi.)ned configuration which includes a 3/4-inch schedule 80 riser instead of a 1/2-inch schedule 40 riser and a weldolet butt welded to the r i r.e r instead of a socket weld.
The use of the weldolet and 3/4-inch schedule 80 pipe provides for a stif fer connection which is more resistant to the f atigue type of f ailure.
These fittings have
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nore naterial to absorb the torsion and bending stresses.
The weldolet allows the use of butt welds which are more resistant to the ef fects u' cyclic loading because it is a better continuation of the l
base metal.
l The licensee performed a liquid penetrant examination of the present l
2-RV 439 configuration on March 14, 1988, after approximately one l
year of operation and two shutdown cooling evolutions, This examina-
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l tion revealed that no damage had occurred to date for the present I
configuration at the location of the two previous failures.
The licensee also reviewed relief valve applications in Unit I and Unit 2
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This review concluded that the orig-
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inal 1/2-inch inlet piping to 2-RV-439 was unique.
All other relief
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valve inlets for these systems are 3/4-inch or greater including the comparable Unit 1 LPSI thermal relief valve 1-RV-439.
Based on licensee actions to date, this item is closed.
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13-10. Management Meeting During this inspection, periodic meetings were held with station manage-ment to discuss-inspection observations and findings. At the.close of the inspection period, an exit meeting was held to summarize the conclusions -
of the inspection.
Ne written material. was given to the -licensee and no proprietary informatici related to this. inspection was. identified.
10.1 Preliminary _ Inspection findinos Unresolved item-50-317/90-09-01 and 50-318/90-09-01.- Review ~ Salt Water Piping Failure Mechanism and Fouling Concerns.-
10.2 AttendanceatManagement_,MeetingsConductedbiRegionBased'
[nspectors
_
Inspection Reporting Date
$ubject Report No.
LInspector May 18, 1990 Modifications 50-317/90-10 LJ.Carrasco June 1, 1990 Eddy Current Test-50-317/90-11 R. ' Winters'
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