IR 05000275/1993024
| ML16342A320 | |
| Person / Time | |
|---|---|
| Site: | Diablo Canyon  |
| Issue date: | 10/28/1993 |
| From: | Johnson P NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| To: | |
| Shared Package | |
| ML16342A318 | List: |
| References | |
| 50-275-93-24, 50-323-93-24, NUDOCS 9312030160 | |
| Download: ML16342A320 (38) | |
Text
U.S.
NUCLEAR REGULATORY COHHISSION REGION V
Report Nos:
Docket Nos:
License Nos:
Licensee:
Facility Name:
Inspection at:
50-275/93-24 and 50-323/93-24 50-275 and 50-323 DPR-80 and DPR-82 Pacific Gas and Electric Company Nuclear Power Generation, BI4A 77 Beale Street, Room 1451 P. 0.
Box 770000 San Francisco, Calsforn>a 94177 Diablo Canyon Units 1 and
Diablo Canyon Site, San Luis Obispo County, California Inspection Conducted:
,August 18 through September 28, 1993 Inspectors:
H. Hiller, Senior Resident Inspector H. Tschiltz, Resident Inspector D. Kirsch, Technical Advisor, Division of Reactor Safety and Projects (September
October 1,
1993)
Approved by:
~Summar:
nson, ie Reactor Projects Section
ate sgne Ins ection on Au ust 18 throu h Se tember
1993 Re ort Nos.
50-275 93-24 and 50-323 93-24 td:
il ti, d
id ti p
i dpi t
p ti maintenance and surveillance activities; followup of onsite events, open.
items, and licensee event reports (LERs);
and selected independent inspection activities.
Inspection Procedures 40500, 51332, 61726, 62703, 62705, 71500, 71707, 71710, 90712, 92700, and 93701 were used as guidance during this inspection.
Safet Issues Hang ement S stem SIHS Items:
None 9312030160 93'28 PDR ADOCK 05000275,
~
."
Results:
General Conclusions on Stren ths and Weaknesses:
Strengths:
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An audit conducted by guality Assurance identified several inconsisten-cies in the in-service testing design basis for both pumps and valves.
The audit also identified inadequate procedures to mitigate a potential loss of the loop seal in the residual heat removal (RHR) system suction line," located above the reactor coolant system (RCS) mid-loop elevation (Paragraph 10).
The questioning attitude of a licensed operator resulted in the identification of isolation valves in the volume control tank relief valve discharge l.ine (Paragraph 5).
. The questioning attitude of a system engineer identified two deficiencies involving low flow in a component cooling water (CCW) line to the RHR pump 2-2 seal cooler (Paragraph 4.a.)
and improper administrative control off a temporary gage on the CCW system.
Weaknesses:
~
A temporary gage was installed without appropriate administrative controls (Paragraph 8).
ll Operators operated ECCS vent valves without valve identification tags.
Si nificant Safet Matters:
None Summar of Violations:
One cited violation was identified concerning installation of a temporary gage in the CCW system without proper documenta-tion.
A non-cited, licensee-identified violation was noted, concerning improper procedural control of the installation and removal of the same test gage during earlier testing (Paragraph 8).
DETAILS Persons Contacted acific Gas and lectric Com an G.
- J W.
- R
- J
- D
- G S.
- W.
S.
T.
- B J.
- C
- J
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- J
- K.
- M.
- J
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- D S.
p.
- R.
- J
- D D.
H. Rueger, Senior Vice President and General Manager, Nuclear Power Generation Business Unit D. Townsend, Vice President and Plant Manager, Diablo Canyon Operations H. Fujimoto, Vice President, Nuclear Technical Services P.
Powers, Manager, Nuclear guality Services S..Bard, Director, Mechanical Maintenance H. Behnke, Senior Engineer, Reg'ulatory Compliance M. Burgess, Director, Systems Engineering G. Chesnut, Reactor Engineer Supervisor'.
Crockett, Manager, Technical and Support Services R. Fridley,'irector, Operations L. Grebel, Supervisor, Regulatory Compliance W. Giffin, Manager, Maintenance Services J. Griffin, Group Leader, Onsite Engineering R. Groff, Director, Plant Engineering A. Hays, Director, Onsite guality Control W. Hess, Assistant Director, Onsite Nuclear Engineering Services R. Hinds, Director, Nuclear Safety Engineering A. Hubbard, Engineer, Regulatory Compliance E. Leppke, Assistant Manager, Technical Services E. Holden, Director, Instrumentation and Controls A. Houlia, Assistant to Vice President, Plant Management H. Oatley, Director, Materials Services R. Ortore, Director, Electrical Maintenance G. Sarafian, Senior Engineer, Nuclear guality Services A. Savard; Director, Technical Services A. Shoulders, Director, Onsite Nuclear Engineering Services P. Sisk, Senior Engineer, Regulatory Compliance A. Taggart, Director, Onsite guality Assurance
- Denotes those attending the exit interview.
The inspectors interviewed other licensee employees including shift supervisors, shift foremen, reactor and auxiliary operators, maintenance personnel, plant technicians and engineers, and quality assurance personnel.
0 erational Status of Diablo Can on Units 1 and
During this inspection period, Unit 1 operated at 100 percent power except for a reduction to 90 percent power for about two hours on September 12, 1993, to conduct main turbine stop valve testing.
Unit 2 operated at lOOX power for the entire report perio.
0 erational Safet Verification 71707 General During the inspection period, the inspectors observed and examined activities to verify the operational safety of the licensee's facility.
The observations and examinations of those activities were conducted on a daily, weekly or monthly basis.
On a daily basis, the inspectors observed control room activities to to determine whether regulatory requirements were satisfied.
Shift" turnovers were observed on a sampling basis to verify that all pertinent information on plant status was relayed to the oncoming crew.
During each week, the inspectors toured accessible areas of the 'facility to observe the following:
(1)
General plant and equipment conditions
Fire hazards and fire fi htin e ui ment ()
g g
q p
(3)
Conduct of selected activities for compliance with the licensee's administrative controls and approved procedures (4)
Interiors of electrical and control panels (5)
Plant housekeeping and cleanliness (6)
Engineered safety features equipment alignment and conditions (7)
Storage of pressurized gas bottles The inspectors talked with control room operators and other plant personnel.
The discussions centered on pertinent topics of general plant conditions, procedures, security, training, and other aspects of the work activities.
verify compliance with selected Limiting Conditions for Operation (LCOs)
as prescribed in the facility Technical Specifications (TS)..
Logs, instrumentation, recorder traces, and other operational records were examined to obtain information on plant conditions and to evaluate trends.
This operational information was then evaluated During plant tours several instances were noted where the potential for seismic interaction existed between material staged for con-struction and maintenance activities and safety-related equipment.
These deficiencies were due to lack of restraint of the construction and maintenance materials stored adjacent to safety-related equip-ment.
Areas where the potential for this type of problem existed included construction laydown areas for installation of pre-outage conduit and cable associated with planned modifications, and a
storage location for a 10-foot diameter stainless steel lifting ring on the roof of the auxiliary building adjacent to the Unit 2 component cooling water (CCW) system surge tan b.
Incomplete restoration following maintenance activities was also identified in several different areas.
Components found to be not fully assembled included the cover of safety-related junction box BJH-48; which'was in installed without any fasteners; and several deck plates associated with the raised flooring in the cable spreading. area adjacent to instrumentation and protection racks, which were installed with bolts missing.
These instances reflected insufficient understanding of management's expectations for restora-tion following maintenance activities.
The licensee agreed to address each of these concerns by correcting the observed deficiencies and discussing proper restoration of equipment and housekeeping with maintenance staff personnel.
The licensee stated that the safety significance of each of the identified deficiencies was minimal.
The inspector discussed the conclusions with the licensee.
The conclusion of;minimal safety significance appeared reasonable.
Radiolo ical Protection c ~
The inspectors periodically observed radiological protection practices to determine whether the licensee's program was being implemented in conformance with facility policies and procedures and in compliance with regulatory requirements.
The inspectors verified that health physics supervisors and professionals conducted frequent plant tours to observe activities in progress and were aware of significant plant activities, particularly those related to radio-logical conditions and/or chal]enges.
ALARA considerations, were
.
found to be an integral part of each RWP (Radiation Work Permit).
d Ph sical Securit Security activities were observed for conformance with regulatory requirements, the site security plan, and administrative procedures, including vehicle and personnel access screening, personnel badging, site security force manning, compensatory measures, and protected and vital area integrity.
Exterior lighting was checked during backshift inspections.
No violations or deviations were identified.
4.
Onsite Event Follow-u 93702 a 0 De raded Com onent Coolin Water CCW Flow to Residual Heat Removal Pum 2-2 Seal Cooler
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2-2 seal cooler was identified during a routine walkdown performed by the system engineer on September 7,
1993.
The flow to the cooler, as indicated by a flapper type flow indicator installed in the CCW return line, appeared to be significantly less than the normal flow rate.
CCW flow rate to RHR pump 2-2 seal cooler was subsequently measured using an ultrasonic flow measuring device and determineddto be less than the required flow rate of 10 gpm.
P
~
~
h Licensee's Actions:
RHR pump 2-2 was declared inoperable and the seal cooler was isolated and disassembled for inspection.
Several pieces of debris, later identified by infrared spectrometry as
'an ethylene propylene material, were removed from. the CCW (shell) side of the seal cooler.
The cooler was then reassembled and placed back into service.
The licensee concluded that the foreign material was
.
from an ethylene-propylene CCW valve liner, a piece of which had been found missing during the Spring 1993 Unit 2 refueling outage.
However, indicated CCW flow to the seal cooler after reassembly was still less than the required flow rate.
A prompt operability assessment and an operability evaluation were performed by the licensee.
Westinghouse also performed an engineering assessment of the reduced seal cooling to RHR pump 2-2.
These evaluations concluded that RHR pump 2-2 was operable through the, next scheduled refueling outage without any CCW flow to the seal cooler, based on the inservice history of the pump seal and the most limiting event requi}ing RHR pump operation.
Subsequent radiography of the RHR pump 2-2 seal cooler CCW supply line identified additional blockage at the 1-1/2" to 1/2" pipe reducer.
This line was cut to remove the material and then reassembled.
The material removed was determined to be the same type as had been previously found in the seal cooler.
Following these corrective actions, flow to the seal cooler was restored and a
'normal flow rate was obtained.
Compensatory measures were initiated by the licensee to ensure that required CCW cooling flow to safety-related components had not degraded.
These actions involved;
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Daily monitoring of flow to components where flow indication was available,
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Measuring component temperatures where CCW flow could not be monitored directly,
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Trending of component temperatures.
The data did not -indicate any reduction of CCW cooling flow to these components.
The safety injection pumps were run to ensure that expected equilibrium temperatures were obtained for the existing
.,
conditions.
The licensee documented these and other corrective actions in non-conformance report DC2-93-TN-N044.
~Summar
Licensee actions restored normal flow to RHR pump 2-2 seal cooler.
Further licensee investigative and corrective actions which deal with the potential for additional foreign material in the CCW system are ongoing (Followup Item 50-323/93-24-01).
No violations or deviations'were identified.
b.
. Use of a Crane Near the Turbine Buildin Qn September 15, 1993, the inspectors observed licensee preparations to lift air conditioner condensers onto the roof of the administra-tion building.
The licensee's plans included positioning the crane
between the north side of the administration building and the south side of the turbine building.
Upon questioning the licensee, the inspector found that:
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The licensee had not specifically evaluated the potential risks-to the Unit 2 emergency diesel generator exhausts, which are located on the south side of the turbine building,
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The licensee had not addressed the adequacy of the exclusion area around the main bank and startup transformers, and
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The licensee had not included detailed instructions for controlling the load path or crane boom swing in a work order for the crane operations.
The inspector discussed
'these concerns with the acting. Mechanical Maintenance Manager, the Shift Supervisor, and the acting Supervisor of Regulatory Compliance.
These discussions determined that several aspects of the job concerning reduction of risk to the plant had been considered and evaluated, but had not been documented.
These included detailed discussions to control boom sweep while positioning the crane, instructions to back out of the job in the event of unexpected conditions, command and control of the rigging job, understanding of crane load factor and wind limitations, Operations involvement to ensure compliance with procedure AP D-758,
"Control of Activities Near Plant High Voltage Lines and Equipment,"
and consideration of 500 KV and 230 KV transformer hazards.
The inspector discussed the need for systematic evaluation of the hazards presented by the crane with respect to the concerns described in 10 CFR 50.59, considering the possibility that placing a movable crane near the turbine building could be considered a
change to the facility.
The licensee determined that a 10 CFR 50.59 evaluation was not necessary since all potential risks presented by the crane had been considered, and were either bounded by analyzed accidents, or were appropriately controlled by riggers who were alert to potential risks to equipment.
A work order was issued to ensure control of the job.
Due to overtime considerations, the job was delayed until the morning of September 16.
The inspector noted that a pre-job briefing was performed by the foreman, discussing the concerns listed above.
The inspectors observed the lifts, and concluded that the job had been evaluated and controlled in an appropriate manner.
No violations or deviations were identified.
5.
Isolation Valve Downstream of Volume Control Tank VCT Relief Valve 40500 During a routine operations review, a licensed operator identified that manual isolation valves were installed on the discharge of the relief valve for the volume control tank (VCT) on both units 1 and 2.
Valves
CVCS-8251A, CVCS-8251B and CVCS-8251C in the discharge of the VCT relief valve could have permitted the relief valve to be manually isolated.
The licensee determined that this configuration was not in full conformance with Section III of the ASHE Code, although the isolation valves are designated on system drawings as being sealed open and were in the sealed open position when the condition was discovered.
As a compensatory action, the licensee locked the valves in the open position with locks and chains.
A similar problem,had been previously identified by the licensee for the positive displacement charging pump (PDP)
1-3 relief valve discharge line.
An isolation valve (CVCS-831)
had been installed in the relief valve discharge line.
Corrective actions taken for a similar problem on the other unit's charging pump 2-3 relief valve addressed the root cause (i.e., the addition of an inappropriate isolation valve using a design change).
The corrective action for the isolation valve on the PDP relief line included licensee review of all design changes to ensure that no design change had added isolation valves downstream of safety relief valves.
The isolation valves on the VCT relief lines appeared to have been in the original Westinghouse design configuration, and therefore did not result from the same root cause as the isolation valve on the positive displacement pump.
An opportunity was missed, however, since a
contributing cause of the installation of the PDP.isolation valve was the lack of familiarity by licensee staff personnel with the ASHE code requirements.
Although not the cause, this lack of familiarity contributed to missed opportunities to identify the VCT isolation valve.
The licensee initiated NCR DCO-93-EN-N015 to resolve this issue.
Addi-tional investigation was initiated to identify any other similar cases, The licensee plans to request a waiver of ASNE code requirements from the NRC for this condition.
The licensee notified Westinghouse of the potential generic implications of this design configuration by a letter on September 15, 1993 (CHRON No. 212249).
The licensee's actions to date appear appropriate.
Since the administrative controls on the isolation valves make isolation of the relief line unlikely, this issue appears to have very low safety significance.
No violations or deviations were identified.
Maintenance 62703 71500 During the inspection period, the inspectors observed portions of, and reviewed records on selected maintenance activities to assure compliance with approved procedures, Technical Specifications, and appropriate industry codes and standards, Furthermore, the inspectors verified that maintenance activities were performed by qualified personnel, in accordance with fire protection and housekeeping controls, and that replacement parts were appropriately certifie The'inspectors observed portions of the following maintenance activities:
Descri tion Dates Performed Block Wall Modifications, Unit 2 4 Kv Switchgear Rooms Positive displacement pump suction stabilizer and pulsation damper test for DCP-N47303, Unit 1 Installation of temporary monitoring equipment at the output of Nuclear Instrument Inverter 2-2..
August 25, 1993 September 3,
1993 September 15, 1993 Control Room Ventilation Breakers Preventative Maintenance September 7,
1993 Replacement of Air Conditioner Evapora-tors Using Crane between Turbine and Administration Building, Unit 2 Replacement of Control Room Ventilation Damper Operator C0115628, Unit 2 September 15, 1993 September 7,
1993 During the inspector's observation of Unit 1 positive displacement pump testing, the inspector identified that a diagnostic transducer was installed in an incorrect location.
The transducer was reinstalled at the proper test point and the correct transducer was used to replace the failed transducer at the designated location.
The procedure for this evolution (PMT 08. 14, Revision 2XPTR) specified the valve to be operated to isolate the transducer prior to removal.
However, this valve, as well as the other recently installed valves, did not have identification tags.
The problem with the transducers was found.and corrected prior to testing being performed with the incorrect installation.
In addition, the licensee took action to install valve identification tags on the affected valves.
The relocation of transducers in an incorrecf manner had no safety significance.
However, the lack of identification tags on valves has been noted in other areas of NRC inspection focus, and will continue to be followed in NRC inspecti'ons.
No violations or deviations were identified.
7.
Surveillance 61726 The inspectors reviewed a sampling of Technical Specifications (TS)
surveillance tests and verified that:
(1)
a technically adequate procedure existed for performance of the surveillance tests; (2)
the surveillance tests had been performed at the frequency specified in the TS and in accordance with the TS surveillance requirements; and (3) test results satisfied acceptance criteria or were properly dispositione The inspectors observed portions of the following surveillance tests on the dates shown:
STP R-26 RCS Primary Coolant Flow Heasure-ments (Data review only)
P d
ddidi STP H-89 ECCS System Venting STP H-16A Operation of Trains A and B
Slave Relays Dates Performed September 14, 1993 September 7-8, 1993 September 9,
1993 Spent Fuel Rack Absorber Surveil-lance (Data review only)
During the inspector's observation of ECCS system venting on Unit 1, three of the vent valves which were operated did not have identification tags.
All three valves (SI-2-3, SI-2-4, RHR-2-998)
had been installed by design changes during the previous refueling outage and had since been operated during the performance of this monthly su} veillance.
The NRC inspector questioned the operator as to how the valves were identified.
The Shift Supervisor was notified and provided the guidance that a second operator independently verify valve identification using a system diagram prior to operating valves without identification tags.
STP R-15 September 20, 1993 Although the valves were correctly identified by the operators, lack of identification of valves is not consistent with Operations Department policy.
Also, increased potential exists for improper system operation when valves have not been clearly identified.
Since these valves had been previously operated during the monthly surveillance, the opportunity had presented itself. to identify and correct the valve labeling deficiencies.
These concerns were communicated to the licensee.
No violations or deviations were identified.
8.
En ineered Safet Feature Verification 71710 During the inspection period, selected portions of the component cooling water (CCW) system for Units
and 2 were inspected to verify that system configuration, equipment condition, electrical lineups, instrumentation, and valves and local breaker positions were in accordance with plant drawings and the Technical Specifications.
Unauthorized Installation and Removal of Ga e:
On September 14, 1993, an inspector conducted a tour of the Unit 2 CCW pump 2-2 room.
The inspector observed a temporary gage installed on the discharge of CCW pump 2-2.
The gage was indicating pump discharge pressure and was secured to the wall by an electrical tie-wrap.
The reason for the temporary installation and the method for securing the gage were questioned by the inspector and discussed with licensee management..
Investigation by the licensee revealed that the temporary
gage installation was not authorized.
The gage was disconnected from the system later that same day.
Further inquiry determined that the temporary gage had initially been
.
installed on April 18, 1993, during the performance of a routine surveillance on CCM pump 2-2 (STP P-BB), after 'it was noted that the normally installed gage (PI-251)
was not reading within its allowable tolerance.
The temporary gage was installed to allow completion of STP P-8B.
After STP P-8B was completed, the temporary gage was removed for post-test calibration.
Following post-test calibration, and after veri--
fication of test gage removal, the test gage was incorrectly reinstalled, without documentation, and remained installed until September 14, 1993, when it was identified by the NRC inspector.
The licensee evaluated the effect of the temporary gage's installation on past system, operability, and determined that it did not create a
condition that was outside the design basis for system leakage.
During the post-test review of documentation, the system engineer identified that the procedure for the surveillance (STP P-8B) did not have provisions for installation of a temporary gage.
The appropriate procedure change to authorize and document use of the gage had not been made.
Rather, the initial installation and removal of the gage was improperly documented in the remarks section of.STP P-BB.
The inspector noted that licensee work authorization an'd temporary modification procedures wer e not followed for;
~
initial installation of the test gage, or
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removal of the test-gage for post-test calibration Paragraph 3. 1 of ADI.ID2, "Review Level A Procedure Review, Approval, Revision Control-and Training Notification," specifies that procedure changes involve change of intent if essential elements of the procedure.
differ from what was previously approved.
Installation and removal of,a test gage for STP-8B is a change of intent to the procedure, for which a
change was required but not issued.
The failure to follow established procedures for controlling work for the installation and removal of the test gage, and performing the surveillance without making the necessary.
procedure changes to authorize the use of a temporary gage, were in violation of 10 'CFR Part 50, Appendix B, Criterion V, which requires that activities affecting quality be accomplished in,accordance with estab-lished procedures.
Since this violation was identified by the licensee, and other criteria of Section VII.B(2) of the NRC Enforcement Policy were satisfied, this violation was not cited (NCV 50-323/93-24-02, Closed).
Unauthorized Reinstallation of Ga e:
After conclusion of the surveillance test discussed above, during which a gage was improperly installed and removed, the same gage was re-installed, without any documentation.
The gage was identified by NRC inspector walkdown, as desc} ibed above.
Installation of the temporary gage without documentation or safety analy-sis'was not in accordance with licensee procedure AP C-4S1,
"Temporary
Hodification Control Plant, Jumpers,"
which requires documentation of temporary modifications to the plant.
This was a violation of plant Technical Specification 6.8. 1, which requires that activities be implemented by approved procedures (Violation, 50-323/93-24-03).
In addition to system walkdown inspection, the inspectors reviewed outstanding operability evaluations, licensee nonconformance reports (NCRs),
and NRC open items concerning the system.
Those issues are discussed in Paragraphs 4b.
One cited and one non-cited violation were noted.
uxiliar Feedwater AFW Pum Shaft End Bell Shrouds 71707
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long). on the end of each of the six AFW pump shaft bearings function as protective casings for blades machined into the end of the pump shaft.
The blades circulate air to remove heat from the bearing.
One shroud is attached to each pump bearing, with two shrouds per pump.
Because painters had painted the outside of the shrouds, Operations staff personnel were concerned that paint dripping into the shroud may have prevented the blades from rotating.
Removal of the shroud with the largest paint buildup (AFW 2-3) revealed that the accumulation of paint did not prevent rotation, and that no wear marks were present on the inside of the shroud.
As a result of this inspection, an additional concern was identified.
The shrouds fit concentrically around the pump casing, secured with small machine screws.
After removal of the shroud, the licensee discovered that some of the threads were stripped, and some heads of screws twisted off during the removal attempt.
These were corrected for AFW pump 2-3.
The concern for the shroud detaching during an event was evaluated, and determined to not be likely, since significant force and use of tools was required to remove the shroud.
The licensee's prompt operability assessment addressed this issue for all six AFW pumps, and concluded that no operability concern existed, either for paint in the shrouds or for stripped machine screws, based on all shrouds being secured by both machine screws and dried enamel paint.
The inspector observed the six pumps, with two shrouds per pump, one on the outboard pump bearing, the other on the inboard pump bearing, in solid contact with the coupling guard which protects the motor to pump coupling.
All shrouds appeared to have been secured with both machine screws and prior coats of paint solidified over the years.
The inspector agreed with the licensee's conclusion that detachment of the shrouds did not appear to be an issue, either for cooling or for mechanical interference with shaft rotation.
The licensee plans to remove and redrill all machine screw holes, and reattach shrouds during the next routine monthly surveillance scheduled for each pump.
No violations or deviations were identifie.
ualit Assurance Audit of Residual Heat Removal RHR S stem 40500 A guality Assurance (gA) audit of the RHR system identified several inservice-testing inconsistencies for pumps and valves.
None of these findings resulted in degraded pump or valve performance.
The gA team also identified a procedural weakness regarding recovery from loss of a'oop seal in the RHR drop line.
This vulnerability exists since a
portion of the Unit
RHR shutdown cooling line to the RHR pump suction is at an elevation higher than the RCS reactor vessel mid-loop elevation.
The licensee imediately initiated procedure changes to correct this vulnerability.
In addition, the licensee issued problem identification documents and initiated corrective actions for each of the findings.
The NRC inspector.concluded that the licensee's actions appeared appropriate.
No violations or deviations were identified.
ll.
Partici ation in Licensee Emer enc Drill 51332 On September'2, 1993, the inspectors participated in an emergency drill.
The inspectors observed operations in the simulator and in the Technical Support Center.
The drill simulated a security event and a loss of coolant accident.
Licensee response observed by the inspectors appeared appropriate and in accordance with emergency response procedures.
No violations or deviations were identified.
12.
Licensee Event Re ort LER Followu 90712 The inspector performed an in-office review of the following LERs associated with operating events.
Based on the information provided in the report, the inspectors concluded that the licensee had met the reporting requirements, had identified root causes, and had taken appropriate corrective actions.
The following LERs are closed:
f Unit 1:'0-275/83-39, Revision
50-275/92-11, Revision
No violations or deviations were identified.
13.
Followu of 0 en Items 92701 a.
Closed 0 en Item 50-275 90-27-01:
Vent Fan Ino erabilit Concerns This issue involved the occurrence of several misoperations (failure to start or tripping) of fan motor and dampers in the auxiliary and fuel handling building ventilation systems, and the licensee's actions to improve reliability and preclude future failures.
The licensee submitted LER No. 1-92-011, Revision 0, regarding the entry into Technical Specification 3.0.3 because of auxiliary building ventilation system inoperability due to personnel error (occurring on December 17, 1992).
This event involved the exhaust fan tripping on thermal overload while the other exhaust fan was'nder maintenance.
This occurred because maintenance personnel did
/
-12-not understand that resetting a signal would stop the operating exhaust fan unit.
The licensee revised the system operating and surveillance test procedures to preclude recurrence.
The licensee reexamined their programs to improve ventilation system reliability as a result of these situations.
A heating, ventila-tion, and air conditioning (HVAC) task force was organized and'a walkdown of various vital and non-vital HVAC systems was performed to identify areas of physical condition or design concerns.
The findings of the walkdowns were resolved and selective.procedure revisions and enhancements were performed.
The inspectors have monitored, periodically, the HVAC systems to as-sess whether the licensee's initiatives were effective in improving HVAC system reliability and performance.
The lower number of HVAC problems indicates that the, licensee's initiatives and actions have improved performance.
Accordingly, this open item is closed.
Closed 0 en Item 50-275 91-03-02:
Licensee's Investi ation of Rebar Corrosion at the Intake Structure This issue involves the observation of reinforcing bar (rebar)
corrosion resulting in concrete spalling at the intake structure, and the effect of the condition on design margins.
The licensee conducted a root cause assessment of the situation and determined the cause to be cyclic exposure to air and salt water.
The licensee's engineering staff performed walkdowns of the intake structure and observed additional areas of spalling due to rebar corrosion.
The licensee repaired all observed locations.
In addition, the licensee performed analysis which established that design margins had been maintained conservatively with respect to the design basis throughout the discrepant condition's existence.
Repairs restored the original design margins.
The inspectors examined the intake structure and established that additional corrosion-caused spalling was not occurring.
Based on the above, this item is closed.
Closed 0 en Item 50-275 91-09-02:
Failure of Auxiliar Buildin'entilation S stem Fans to Automaticall Restart This issue deals with a situation where, following a power interrup-tion, the auxiliary building ventilation fans did not automatically restart after the vital buses were reenergized by the emergency diesel generators; and the fans could not be restarted by operators.
The licensee conducted troubleshooting to determine the cause, and determined that a
12VDC regulator and several capacitors had failed.
Repairs were made and the system was retested satisfactorily.
The licensee researched their records for similar problems and concluded that this was an isolated failure.
Similar failures have not been observed since that time.
Based upon the above, this item is close Closed 0 en Item 50-275 91-27-02:
Increase in Personnel Error Events The issue addressed by this open item concerned the relatively increased frequency of events which were caused by or contributed
= to by personnel error in late 1991.
The licensee'took corrective
'ctions to reduce the frequency of personnel errors.
The inspector had reviewed those actions and determined to leave this item open for a time, during which the inspection staff would monitor the effectiveness of the licensee's actions to reduce personnel errors.
The inspectors determined that the frequency of events with personnel error causes or contributors had decreased, indicating that the licensee's,actions had been effective.
Based on the above, this item is closed.
Closed 0 en Item 50-275 91-37-01:
Loss of Deca Heat Removal I
The NRC inspector reviewed the licehsee's responses to Generic Letter 88-17 and documented the results of these reviews in NRC Inspection Report No. 50-275/91-37.
This open item involved the inspector's observation that some procedures required clarification and revision to assure completeness and consistency of information.
The inspector's specific observations were documented in the aforementioned inspection report.
The licensee performed an assessment of their procedures and agreed with the inspector's observations.
The licensee revised the.
appropriate procedures to address the inspector'.s observation's and the results of their assessment.
Based upon the above, this item is closed.
Closed 0 en Item No. 50-275 92-16-02:
Interference oF Plastic Protective Coverin in the Emer enc Li htin Illumination Paths This issue involved the covering of emergency battery-operated lighting with plastic protective covers during concrete block wall modifications in two switchgear rooms.
The licensee performed a root cause assessment of the situation and determined that the scaffold barrier review had not properly accounted for the design function of the battery-operated lighting.
The licensee revised procedures for temporary installations in safety-related areas to include an assessment of emergency lighting in those areas.
The licensee concluded that the covered lighting was operable, and in the event of a loss of power condition the maintenance workers or operators could easily remove covers to illuminate the area.
In addition, personnel were counseled regarding Appendix R and FSAR requirements.
Based upon the above, this item is close Closed Unresolved Item No. 50-323 90-08-02:
Fuel 8andlin Buildin Brid e Crane Problems This issue involved several problems identified during operation of the Unit 2 fuel handling building bridge crane:
(I) adequacy of modification startup testing; (2) contractor communications and (3) quality assurance involvement.
The licensee issued a nonconformance report to document the situa-tion (DC2-90-TN-N046)
and preclude recurrence.
The licensee revised crane checkout procedures and preventive maintenance procedures to assure that adequate checks are in place to preclude recurrence and.
assure that any future problems with the crane are reported to management.
The licensee replaced the worn braking parts and retested the unit satisfacto'rily.
The licensee held workshops to
',
define management expectations regarding problem communication to
'epartment managers, engineers, and 'general foremen.
guality Assurance (gA) involvement was assessed, with the determination that gA had been involved in -assessing the advisability of jumper installation, and had concurred; and had also discussed the situation with outage management.
Review of thi's unresolved item determined that no violation or deviation was involved.
Based upon the above, this item is closed.
Closed 0 en Item 50-323 93-07-02:
Failure of Safet -Related nverter Y 2 This open item concerned the failure of inverter IY22 on two separate instances during the performance of Unit 2 integrated ECCS timing relay testing.
The licensee conducted troubleshooting for the cause of the failures.
The failure of IY22 to produce an output voltage was determined to be a blown fuse on the DC input to the inverter.
The cause of the blown fuse was determined to be the result of a silicon controlled rectifier misfiring and creating a short circuit, due to the controlling logic board being excessively sensitive to the transient caused by the inserter AC input contactor closing.
The licensee replaced the logic board and returned IY22 to service, satisfactorily.
In addition, the licensee assured that the logic boards on the other instrument inserters were replaced in an effort to preclude recurrence.
Based upon the above, this issue is closed.
Closed 0 en Item 50-323 93-07-05:
Evaluation of Crack Indications in the Accumulator Tanks Claddin This issue deals with the observation of cladding cracking indica-tions in the heat-affected zones of nozzle and girth welds inside the Unit 2 accumulator tanks during the 5th refueling outage.
The
- 15-issue was referred to NRR for technical assistance in resolving the associated technical issues.
The licensee submitted descriptions of accumulator cladding indications in letters to NRR dated April 19 and 28, and August 2, 1993.
NRR evaluated the licensee's submittals and issued a
safety'valuation to the licensee by letter dated September 2,
1993, concluding that the indications were properly dispositioned according to the ASME Code.
Based on the above, this item is closed.
Closed 0 en Item 50-323 93-07-06:
Hissin Seismic Su orts in Breaker Cabinet This issue involved the inspector's.observation of inconsistencies of configurations between redundant 4KV vital switchgear.
guality Assurance inspected the locations and observed some missing vertical stiffeners, screws, and an angle brace.
The engineering issues were evaluated by Nuclear Engineering Services and a
calculation was performed to assess the safety significance.
In addition, the panels were "as-built" inspected and documented because of the inadequate vendor drawings.
Engineering determined that the seismic qualification of the panels was maintained and the
"as-built" configurations was bounded by the seismic qualification calculation.
Therefore, the switchgear remained operable.
Based on the above, this issue is closed.
Closed 0 en Item 50-275 93-03-07 Leaka e Past a Valve Results in Potential For Inade uate ECCS Flow or SI Pum Runout On September 15, 1992, the licensee determined that, during a loss of coolant accident (LOCA), bypass flow leakage through isolation valves SI-8802A and SI-8802B may result in inadequate cold leg injection flow or safety injection (SI)
pump runout.
The licensee attributed this event to inadequate system design, which did not properly address the flow characteristics of the valves.
In summary, the licensee concluded that, based on calculations and the history of valve operation, the plant had never been in a. condition which would have allowed this bypass flow to occur.
The inspector's examination of these conclusions is discussed below.
Detailed Descri tion:
The valves SI-8802A and SI-8802B are four-inch SI system double-disk gate valves which isolate the cold leg injection path from the hot leg injection path.
Because thermal binding of this type of valve had been experienced in the past, the vendor, Anchor Darling, in conjunction with Westinghouse, developed a modification which added a 3/4-inch pressure equalization line.
This line was designed to equalize pressure between the higher pressure side of the valve, in this case the reactor coolant system (RCS),
and the space between the valve disks.
As a result of this pressure equalization path, a flow path can be created. if the RCS
-16-P (originally the higher pressure)
side becomes the lower pressure side.
Fluid from the now higher pressure side (the ECCS system)
would then push the higher pressure side disc off the seat, permitting fluid to flow under the disc and into the RCS via the equalization line.
The vendor recognized the generic design vulnerability, although this specific ECCS installation was not addressed.
The vendor recommended against relying on the downstream side of the valve to isolate flow if the differential pressure was reversed.
Potential Safet Si nificance and Generic Im lications:
During a
LOCA, differential pressure across the valve would reverse if RCS
pressure dropped below SI.pump discharge pressure.
This would result in the potential for ECCS flow to be robbed from the cold leg injection header, and for increased pump flow to the point of SI pump runout.
Use of a double-disc gate valve in an application with reversal of differential pressure would pose the same design vulner-abilities.
The licensee communicated this concern to Westinghouse, since the recommendation to install this type of valv'e in this system configuration had been provided by Westinghouse in response to industry concerns for double-disc gate valve bonnet pressuri-zation.
A Westinghouse Safety Advisory Letter dated June 23, 1993, was issued to all'estinghouse plants to alert licensees to this vulnerability.
The letter recommended that licensees'erify the exact configuration of installed double-disc-gate valves, throttle the associated overpressure line isolation valves, and follow vendor recommendations for modifications to overpressure relief capability.
Immediate Corrective Actions:
As documented in LER 1-92-19, Revision 0, the licensee determined that the 3/4-inch globe valve installed in the equalizing line, SI-8890, could be throttled to 1/4 turn.open to provide an overpressure protection path which would relieve any pressure build-up between the valve discs, and also adequately-restrict ECCS flow through the equalization line.
Past 0 erabilit
The licensee also stated that, regarding past operability, valves 8802A and 8802B were considered leak tight (and therefore operable)
since, based on a history search of plant operations, no differential pressure or flow has existed during the valve closure stroke.
This was considered a basis for operability since the licensee's calculations concluded that the excessive force of the valve stroke was converted into significant wedging force, which would prevent leakage under worst case design basis event differential pressure.
Based on these calculations, and on the system configuration during which the valves are closed, the licensee concluded that no disc leakage would have occurred during any design basis event.
Past issues which have been resolved include adequacy of the licensee's corrective actions to close the equalization valve 1/4 turn to limit leakage,,to determine the root cause, to evaluate missed opportunities, and to evaluate valves of similar design which are installed in the plan No I
Ins ector Concerns:
Based on previous discussions with the licensee, the inspector had identified a concern regarding gate valve leakage.
The licensee stated that the double-disc gate valve SI-8802 would not be expected to leak under LOCA conditions, although the valve manufacturer does not guarantee leak tightness under these differential pressure conditions.
Based on the valve
'
design, and as explained above, leakage would be expected if differential pressure across the valve were to be reversed.
The licensee determined that a maximum of 700 psid would be expected across the valve during a worst case design basis accident.
The licensee calculated that seating force, transferred into wedging
force, would be sufficient to prevent leakage under the seat with this differential pressure..
The inspector asked if maintenance records for the valves had been reviewed to determine if the assumed configuration of the valves had been altered after installation.
The licensee performed a review of maintenance records and determined that the valves had not been altered from original configuration.
At the inspector's request, the licensee provided the calculations to the inspector.
The licen-see's conclusion that seating force was adequate to preclude lifting the disc from the seat appeared to be substantiated by calculation as well as valve performance during several test configurations.
Industry information and vendor communications also supported the licensee's conclusion, and maintenance records indicated that no changes in valve configuration had taken place which may have allowed lower seating force.
The inspector's concern as documented in Open Item 50-275/93-03-02 is therefore resolved (closed).
violations or deviations were identified.
14. ~Ei<<i An exit meeting was conducted on September 28, 1993, with the licensee representatives identified in Paragraph 1.
The inspectors summarized the scope and findings of the inspection as described in this report.
The licensee did not identify as proprietary any of the materials reviewed by or discussed with the inspectors during this inspection.'