IR 05000440/1991005
| ML20198C641 | |
| Person / Time | |
|---|---|
| Site: | Perry  |
| Issue date: | 06/25/1991 |
| From: | Gardner R, Neisler J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | |
| Shared Package | |
| ML20198C619 | List: |
| References | |
| 50-440-91-05, 50-440-91-5, 50-441-91-03, 50-441-91-3, NUDOCS 9107030104 | |
| Download: ML20198C641 (21) | |
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S. NUCLEAR REGULATORY COMMISSION
REGION III
Reports No. 50-440/91005(DRS); No. 50-441/91003(DRS)
l Docket Nos. 50-440; 50-441 Licensee:
The Cleveland Electric Illuminating Company 10 Center Road
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Perry, OH 44081 Facility Name:
Perry Nuclear Power Plant - Units 1 and 2
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Inspection At:
Perry, OH Inspection conducted:
April 29 through May 24, 1991 Inspection Team:
J. H. Neisler, Team Leader R. A.
Westberg, Assistant Team Leader.
l F. T.
Daniels, Senior Operations Engineer, NRR R. Mendoz, Reactor Inspector NRC Consultants:
P. A.
Lyles, AFCL (Atomic Energy of Canada)
N. J.
Deinha, AECL
,R.
Howe, AECL
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// d[1 N' ) D 9/
4k[
Approved By:
H.
N61sler, Team Leader Date
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Plant systems Section l
add
[ ' d Y '7/
Approved By: /h. ' N.
Gardnef, Chief Date Plant Systems Section Inspection Summary Inspection on Anril 29 through May 24. 1991 (Recorts No.
50-440/91005(DRS): 50-441/91003fDRS))
Special electrical distribution system functional inspection in accordance with temporary instruction (TI) 2515/107 (25107) and extended construction delay inspection of Unit 2 (92050).
Results:
The team determined that the electrical distribution system was functional and that engineering and technical support was acceptable.
-Eight open items were-identified regarding non -
conservative cable impedances (Paragraph 2.1.1), degraded grid voltage calculations (Paragraph 2.1.3), short circuit study assumptions (Paragraph 2.1.5), voltage drop calculations for 460 volt safety related motors (Paragraphs 2.1.7 and 2.1.8), battery sizing calculation assumptions (Paragraph 2.2.2), the Anticipated Transient Without Scram (ATWS) AC voltage drop calculation (Paragraph 2.2.4), and the diesel fuel storage tank degraded lining (Paragraph 2.3.3).
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9107030104 910627 PDR ADOCK 05000440 0-PDR E
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J Table of Contents Title Pace Executive Summary.
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1.0 Introduction.
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2.0 Electrical Syst(ms.
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2.1 AC Systems.
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2.2 DC Systems.
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2.3 Mechanical Support Systems.
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3.0 Engineering and Technical Support.
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4.0 Unit 2 Preservation.
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5.0 Open Items.
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6.0 Exit Meeting.
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Appendix A - Personnel Contacted Y
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Executive Summary During the period April 29 through May 24, 1991, a Region III
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inspection team conducted an electrical distribution system functional inspection (EDSFI) at the Perry Nuclear Power Plant to review the design and implementation of the plant electrical distribution system (EDS) and the adequacy of the Engineering and
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Technical Support (E&TS) organizations.
The team reviewed the electrical and mechanical support systems of the EDS, examined installed EDS equipment, reviewed EDS testing and procedures, and interviewed selected corporate and site personnel.
The team considered the design and implementation of the EDS at
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Perry to be acceptable.
The robust design of the EDS to provide additional safety margins and capacity was considered a strength.
Design attributes of the EDS were retrievable.
Engineering calculations were technically sound, although the team identified some nonconservative assumptions.
The team considered the scope and_ implementation of the site program for surveillance testing i
of the EDS a strength.
Control of modifications to the EDS was acceptable and there appeared to be an adequate interface between i
engineering, operations, and maintenance.
The team found the EDS and related support equipment to be properly installed in the plant and considered the material conditions of the EDS a strength.
The team found significant improvement in the activity of the Independent Safety Engineering Group (ISEG) since the last time the group was inspected.
In addition, the team considered the knowledge and expertise of the engineering staff a strength; however, the training program for the engineering staff was not aggressively implemented.
The team also had several concerns that required further action i
by the licensee.
Examples included:
The lack of a comprehensive load growth control program.
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The use of nonconservative cable sizing and voltage study
calculations.
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The lack of a current design basis document describing the J
l criteria for cable sizing.
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The omission of certain safety related motors from voltage
drop calculations.
Based on initial licensee responses, preliminary calculations and design margins, there appeared to be no immediate operability concerns.
More comprehensive calculations by the licensee are needed to confirm the adequacy of the design margins and calculations.
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1.0 Int;noduction i
l During electrical inspections at various operating plants in the country, the NRC staff had identified several electrical distribution system (EDS) deficiencies.
The special Inspection Branch of the Office of Nuclear Reactor Regulation (NRR)
i initiated inspections of the EDS at other operating plants after they determined that such deficiencies could compromise design margins.
Examples of these deficiencies included unmonitored and uncontrolled load growth on safety buses and inadequate modification, design calculations, testing, and qualification of
commercial grade equipment used in safety related applications.
The NRC considered inadequate engineering and technical support (E&TS) to be one cause of these deficiencies.
l The objectives of this inspection were to assess the performance capability of the Perry EDS and the cao 111ity and performance of the licensee's E&TS group in this area.
For this inspection, the EDS included the sources of power to sy.. ems required to remain functional during and following the design basis events.
EDS components reviewed included the standby diesel generators
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(SDGs), 125Vdc batteries, offsite circuits and switchyard, 4kV switchgear, 480Vac load conters (LCs), 480Vac Motor Control Centers (MCCs), 125Vdc MCCs, battery chargers, inverters, associated buses, breakers, relays, and other miscellaneous components.
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The team reviewed the adequacy of the emergency, offsite and onsite power sources for EDS equipment, the regulation of power to essential loads, protection for postulated fault currents, and coordination of the current interrupting capability of protective devices.
The team also reviewed the mechanical systems that interface with the EDS, including air start, lube oil, and
cooling systems for the SDGs plus the cooling and heating systems for the EDS equipment.
The team walked down originally installed and as-modified EDS equipment for configuration and equipment
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ratings and reviewed qualification, testing, and calibration records.
The team assessed the capability of the licensee's E&TS organization with respect to personnel qualification and staffing, timely and adequate root cause analyses for failures and recurring problems, and engineering involvement in design and operations.
The team also reviewed training for Operations and E&TS personnel relative to the EDS.
l The team verified conformance with General Design Criteria (GDC) 17 and 18 and the applicable 10 CFR 50, Appendix B criteria.
The team also reviewed plant Technical Specifications (TS), :he l
Updated Safety Analysis Report (USAR), and appropriate Safety j
Evaluation Reports (SERs) to verify that TS requirements and licensee commitments were met.
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The areas reviewed and the concerns that were identified are described in Sections 2.0 and 3.0 of this report.
Conclusions
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are given after each of these sections.
A list of the personnel contacted and those who attended the exit meeting on May 24, I
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1991, is provided in Appendix A of this report.
2.0 Electrical Systems 2.1 Class 1E AC Systems
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In order to assess the capability of the electrical distribution
system (EDS), the team reviewed the sizing, regulation, i
protection and installation of EDS loads.
The review included system descriptions, station USAR, equipment sizing calculations, equipment specifications, one-line diagrams, elementary diagrams,
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protective relaying curves, operating procedures and plant walkdowns.
Various critical EDS components were evaluated to assess the adequacy of important parameters such as continuous loading, short circuit capability, etc.
In addition, the EDS was reviewed
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to assess its capability to provide adequate voltage to safety-related loads under both starting and steady state operating conditions.
The preferred power source transformers were
reviewed for their kVA capability, connections to the safety buses and voltage regulation.
The standby diesel generators (SDGs) were reviewed to assess the adequacy of kW rating for the operation of EDS loads.
The 4kV safety buses and their loads i
were reviewed to assess load current, short circuit current capabilities, voltage regulation, adequacy of cable connections
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between loads and Fuses and the adequacy of the degraded grid and loss of power relaying schemes.
The 480Vac safety buses and their connected loads were reviewed to assess load current, short circuit current capabilities, voltage regulation, and the adequacy of cable connections between loads and buses.
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2.1.1 Voltace Reculation Studies The team's review of the following voltage regulation studies determined that non-conservative cable impedances were used:
Calculation No.
Rev. No.
Title 431-85-1
PNPP Auxiliary System Voltage Study 431-85-2
460Vac Safety Related Motor Starting Voltage Drop 431-85-3
460Vac Safety Related Motor Steady State Voltage Drop Study
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The cable impedances identified in these calculations were based
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on a conductor operating temperature of 50*C.
The licensee used this lower conductor operating temperature to justify the use of reduced cable impedance values.
The team's concern was that the licensee did not provide a rigorous technical evaluation to
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l justify a 50*C conductor temperature.
Using an industry accepted I
method based on cable loading, maximum ampacities and ambient temperature, the team performed calculations for a sample of 12 power circuits.
These calculations showed that all of the power circuits sampled would operate at temperatures greater than 50*C.
l Three of the sampled circuits were found to have a calculated i
conductor operating temperature of approximately 70*C.
l In addition to the above concern, it was noted that Calculation No. 431-85-1 incorrectly applied the conductor temperature correction factor to both the resistive and reactive components of cable impedance.
Conductor temperature affects only the I
resistive component of impedance and has no effect on cable (
reactance.
The licensee indicated that it had already identified I
this concern and was in the process of revising the calculation.
Since both of the above concerns result in non-conservative values of voltage drop, the team was concerned with the potential impact this could have with respect to adequate starting and steady-state voltages at the terminals of various EDS loads.
After review of a sample of 460Vac motors, no operability concerns were identified.
The licensee was in the process of revising the plant voltage study (Calculation No. 431-85-1) to include analysis of the 460Vac motors presently addressed in Calculation Nos. 411-85-2 and 431-85-3.
The licensee committed to address the above concerns relative to steady state voltage conditions in this revision of the plant voltage study which will be completed by the end of 1991.
The cables are rated at 90*C, therefore the team concluded that there are no immediate operability concerns to require earliier completion of the licensee's calculations.
Licensee resolution of plant voltage conditions will remain open pending further NRC review (440/91005-01(DRS)).
2.1.2 Auxiliary System Voltace Study The team was concerned that the licensee could not produce an analysis which addressed the maximum expected station EDS voltage.
Branch Technical Position (BTP) PSB-1, Adequacy of Station Electric Distribution System Voltages, states that maximum system voltages should be analyzed with the offsite power supply-(grid) at the maximum expected voltage concurrent with minimum unit loads (e.g.,
cold shutdown, refueling).
The team's concern was that without analysis, the potential existed that an
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overvoltage condition in the offsite power supply could result in overexcitation of various EDS equipment.
In particular, transformers and motors are vulnerable to overexcitation.
This
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condition, if allowed to occur undetected, will result in premature equipment failure due to overheating.
Plant overvoltage conditions were not annunciated in the control room
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and therefore could be undetected.
In response to the team's concern, the licensee provided a draft calculation demonstrating that, at no-load conditions and a maximum offsite power source voltage of 1.02 PU (345KV nominal),
the secondary windings of various EDS transformers would not experience overexcitation (i.e., voltages greater than 110% of nameplate).
Based on these maximum transformer secondary voltages, the team concluded that the EDS motors would also not encounter overexcitation.
The licensee committed to include, as part of its revision of the plant voltage study (calculation No. 431-85-1), additional case studies to formally address minimum plant loading concurrent with maximum grid voltage conditions.
The results of this analysis will bc used to determine a value of offsite power source
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overvoltage.
This information will be provided to the offsite organization, Centerior System Operations Center (SOC), which is responsible for controlling switchyard voltage.
Upon identification of high grid voltage, SOC will be required to notify the Perry Control Room operator of an overvoltage condition.
Both of these commitments were to be completed by June 1, 1992.
2.1.3 Decraded Grid Undervoltace Relayinq During the review of Calculation No. 686-85-24, Revision 2,
" Degraded Voltage and Loss of Of fsite Power Undervoltage Relaying for Divisions 1, 2 and 3," tre team noted that operability of EDS loads may be jeopardized during the initial 5 minute period under degraded voltage conditions.
This 5 minute period would occur if the value of degraded voltage at the 4kV buses stabilized in the range between the setpoint for the degraded grid relays (95% of
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4kV) and the setpoint of the loss of offsite power relays (75% of 4kV).
This range of voltage is below the voltage range analyzed in the licensee's voltage studies.
Any voltage in this range would drop-out the degraded grid relays which would initiate an alarm in the control room if the voltage did not recover within 15 seconds.
A second set of relays would be initiated for a 5 minute time delay before transfer to the diesel generators was initiated.
It is during this 5 minute delay that the EDS bus voltages could not be predicted and adequate starting and steady state voltages at the terminals of the EDS loads could not be ensured.
In addition to the operability of motors and motor
operated valves, the inspection team had a concern with the possible degradation of control circuits associated with relays and motor control center starters.
The lower than expected voltage could result in the inadvertent blowing of safety related control circuit fuses and the dropping out of relays and starters
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and result in the loss of redundant safety loads.
This concern
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will remain open pending further NRC review (440/91005-02(DRS)).
2.1.4 Cable Sizina Desian Bases The team identified the lack of a design basis document which described the philosophy used by Perry to size cable at the 13.8kV, 4.16kV and 480V levels.
The only cable calculation which could be retrieved was Calculation No. CALR10-20, dated April 29, 1976, " Cable Sizing - 13.8kV Buses L10 and L20."
This calculation was intended to document the sizing of power cables based on ampacity at the 13.8kV and 4.16kV levels of the EDS.
However, the calculation lacked sufficient detail to determine
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its adequacy and contained outdated data concerning motor and transformer ratings.
During the design and construction of the plant, the licensee's architect-engineer had developed the Project Design Criteria which included the ampacity and dorating of cables.
This document was not made part of the plant's permanent file as a living document.
In addition, Perry has revised its original cable sizing criteria for certain medium
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voltage cables.
Review of various documents including the
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Project Design Criteria allowed the team to conclude that the subject cables were adequately sized.
However, the team was concerned that the lack of a single comprehensive design basis document describing cable sizing philosophy could result in the incorrect sizing of cable for future plant modifications.
The team considered this to be a programmatic weakness relative to
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the plant's design bases and the licensee's ability to adequately support plant modifications.
2.1.5 Short Circuit Study
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The team determined that EDS short circuit study calculation No.
686-85-100, Revision 1,
" Perry Nuclear Plant Short Circuit Studies," which was perforr.ed assuming nominal system voltages, was nonconservative since actual system voltages may be higher than nominal.
The higher system voltages would produce at least a proportionately higher fault current value than identified in the present calculations.
Since the 13.8kV, 4.16kV and 480V switchgear and 480V motor control centers were conservatively sized, the team did not identify any operability concerns as a result of this nonconservative assumption.
The team was
concerned that the results of the study may be used in the future by personnel not intimately familiar with the assumptions of the study, and as a result, the short circuit values identified in the-study may be assumed by-the user to be maximum values of short circuit current.
The licensee committed to revise Calculation No. 686-85-100 to indicate that at maximum system voltages the short circuit currents will be higher than those calculated at nominal voltages.
This revision will be completed
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by June 1, 1992.
Pending further NRC review, this is considered an open item (440-91005-03(DRS)).
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2.1.6 Auxiliary System Voltane Study Review of Calculation No. 431-85-1, Revision 0,
"PNPP Auxiliary System Voltage Study," identified the following concerns:
Several load sequence times and values of full load current
presently shown on Perry Drawing D-206-009, Revision D,
" Connected, Automatic and Manual Loading and Unloading Safety System Switchgear - Div.
2," did not agree with the times and values of full load current shown in the calculation.
No justification was provided for determining that the loss
of coolant accident (LOCA) scenario identified in the calculation was the diesel generator worst-case loading.
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No explanation was provided in the calculation to explain
i the rationale used in selecting the diesel generator load time sequence case studies.
The licensee committed to address all of the above concerns in the revision of this. calculation which was in process.
2.1.7 Startina Voltace Drop Of 460V Safety Related Motors The team found that Calculation No. 431-85-2, Revision 1,
"460V Safety Related Motor Starting Voltage Drop," did not evaluate the starting voltage drop for all 460V safety related motors powered from motor control centers (MCCs).
This calculation assumed that certain groups of-Class 1E motors did not require evaluation of starting voltage drop under degraded voltage conditions when powered from the offsite power source.
For example, Class 1E motors which were started manually or were started later than 2.5 minutes after the LOCA occurs were not evaluated for starting voltage drop.
As a result, motors such as the diesel generator fuel oil transfer pump, diesel generator fuel oil transfer backup pump and standby liquid control system transfer pump were not included in the analysis.
The team was concerned that any safety related motor would be excluded from this analysis.
Proper starting and acceleration of all safety-related motors is critical to ensuring these components perform their safety functions as well as ensuring that these motors do not jeopardize the EDS by drawing abnormally high starting currents for prolonged periods of time.
The licensee committed to evaluate the starting voltage drop for those motors not originally included in Calculation No. 431-85-2 by June 1, 1992.
The team considered the available' load margins and the sizes of motors involved and determined that the June 1, 1992 commitment was acceptable.
Pending further NRC review, this is considered an open item (440/91005-04(DRS)).
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2.1.8 Steady State Voltage Drop of 460V Safety Related Motors The team determined that Calculation No. 431-85-3, Revision 0,
"460 Volt Safety Related Motor Steady State Voltage Drop Study,"
did not evaluate the steady state voltage drop under degraded grid conditions for all 460V safety related motors powered from MCCs.
This calculation assumed that there was no need to evaluate steady state voltage drops for those safety related motors which started 10 minutes or later post-BOCA.
This was based on the control room operator being able to begin selectively shedding some Class 1E loads so as to allow EDS bus voltages to increase.
The inspection team had the following concerns regarding this approach:
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Adequate procedures for selective load shedding were not
available for operator guidance in determining which loads to shed or when to shed loads.
Without an evaluation of steady state voltage drop, it can
not be ensured that safety related motors will not draw higher than expected values of full load current which could result in excessive voltage drops.
The licensee was in the process of reviewing their vo2Lago drop
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calculations before this inspection and committed to include an j
evaluation of the steady state voltage drop for those motors not originally included in Calculatica No. 431-85-3 by June 1, 1992.
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Pending further NRC review, uhis is considered an open item (440/91005-05(DRS)).
2.1.9 Cable Separation and Cable Trav Fill The team considered the cable installation system to be a strength, particularly in the areas of cable separation and cable tray fill.
This was due to Perry's design which used three safety divisions with uniquely colored cables for each division.
The team also noted that the workmanship in t raining the cables in the cable trays was excellent.
2.1.10 Surveillance Test Procrau The team reviewed approximately 15 surveillance test procedures
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and concluded that the procedures were well written and included clear acceptance criteria.
The ted., a.lso concluded that the instrument setpoints and tolerances specified in the surveillance procedures were within the values specified by the TSs.
The team considered the surveillance test program to be a strength.
l 2.1.11 Surveillance As-Found Data The team observed that the licensee did not take as-found data for safety related instruments that were being removed or
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replaced resulting in the loss of performance data for the replaced instrument.
The failure to record the as-found condition could impact root cause analyses, engineering reviews and procurement decisions when buying new instruments.
2.1.12 SDG Load Secuencina The team noted that the licensee did not calibrate or check the tolerance of six non TS diesel generator time delay sequencing relays.
Table 8.3-1 of the Final Safety Analysis Report (FSAR)
listed the loads and the times that these loads would be sequenced on in the event of a LOCA or loss of offsite power.
However, only the residual heat removal (RHR) and essential service water (ESW) pumps' time delay relays were tested.
The licensee stated that the six relays had not been tested since the initial preoperational test in 1984.
The licensee also stated that the question of relay sequence testing was evaluated in FCR 07785 issued on September 11, 1987.
The FCR stated that the relays were for system operating requirements and not for diesel loading concerns.
The team considered this response to be acceptable.
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2.1.13 Conclusion The team determined that, in general, the performance of the Class 1E AC system was acceptable.
Design attributes of the EDS were strong and retrievable.
Engineering calculations were generally sound although some non-conservative assumptions were j
identified which will require further evaluation and added attention by the licensee.
2.2 DC Systems The team reviewed.the station Class 1E DC systems, 120Vac jnverters and electrical containment penetrations for design compliance to applicable standards and codes.
The inspection included the review of the 125Vdc battery design with respect to sizing, duty cycle loading, electrolyte temperature, battery age and capacity.
The associated battery charger designs were reviewed for total loading requirements and the bases of these calculations were checked for their adequacy.
The inverter's sizing and design criteria were reviewed for their ability to meet applicable standards and power input / output requirements.
Fault study. calculations for the 125Vdc and the 120Vac systems were reviewed relative to system parameters and requirements, applicable standards, correctness, accuracy and standard engineering practices.
Voltage drop studies and cable sizing
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calculations for the 125Vdc and the 120Vac were reviewed relative to system parameters and requirements, applicable standards, correctness, accuracy and standard engineering practices.
A resin' of breaker / fuse coordination and sizing was performed to determine if protection schemes for the DC systems conformed to
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standards and practices used for cration design.
The team also reviewed the electrict.1 penetration design against standards applicable during station design and construction.
2.2.1 Testina Freagency of Class 1E Batteries with Indications el Deoradation The team's review of the Perry Technical Specifications indicated that the required 18 month testing frequency for a class 1E battery showing signs of degradation was in conflict with the Perry USAR.
Perry USAR Table 8.1-2 states, " Maintenance, testing and replacement of Class 1E storage batteries are in accordance with IEEE Standard 450-1980."
IEEE Standard 450-1980, Section 5.2 (3) recommends annual performance tests of battery capacity for batteries which show signs of degradation.
The licensee committed to revise the following documents to maintain consistency with the Technical Specifications:
USAR Table 8.1-2, reference to IEEE Standard 450-1980.
- USAR Table 1.8-1, Regulatory Guide (RG) 1.129 exceptions.
- Technical Specifications, Page B 3/4 8-2, reference to
battery operability based on RG 1.129 and IEEE Standard 450-1980.
The team determined that the inconsistency with IEEE Standard 450-1980 was not safety significant for the following reasons:
The DC system has a significant design margin:
The DC system surveillance and maintenance programs
generally exceed the requirements of IEEE Standard 450-1980; Three redundant Unit 1 DC systems are available; and
Class lE Unit 2 batteries are available to back up the
corresponding Unit 1 battery.
2.2.2 Class 1E Division II Battery Sizino Calculation The team's review of Calculation PRDC-00'05, Revision 0,
" Load Evaluation and Battery Sizing of Divisions I & II Class lE DC Systems," revealed the following weaknesses:
The analysis of the inrush currents associated with spring
charging motors on the 4.16kV switchgear and the 480Vac switchgear was it. consistent with the description provided in the respective vendor's manual.
The vendor's manual for the 4.16kV switchgear indicated that these motors were activated upon switchgear closure.
The calculation assumed activation
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on switchgear trip.
The vendor's manual for the 480Vac switchgear indicated that these motors were activated upon switchgear trip.
The calculation assumed activation on switchgear closure.
The analysis of the battery load for the first minute did
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i not address the latest version of Table 8.3-1 of the USAR.
i The explanation (Page 11 of 31 of PRDC-0005) of the
selection of 60 amps as the peak charging motor current was less conservative than IEEE Standard 485-1978, Section 4.2.3, to which the licensee was committed.
The licensee committed to revise Calculation No. PRDC-0005, Revision 0, to address these issues.
Pending further review by the NRC, this is considered an open item (440/91005-06(DRS)).
2.2.3 DC MOV Toroue Calculations The team's review of Calculation No. 87-30020, Revision 1,
"RCIC (1E51) DC MOV Torque Calculation," identified a non-conservative error in the calculation of the minimum available torque during
l reduced Division I DC s_; TEM * ages.
Calculation 87-30020
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assumed that battery termina-v.o 3es could be used at the RCIC MCC bus.
This resulted in a' :.s-estimation of the available torque for these motors.
I,refin nary calculation including cable voltage drop performei caram. the inspection indicated that adequate torque v?as available to U motor operated valves.
The licensee agreed to revise Ca; ;ulat".n No. 87-30020 to address this issue.
2.2.4 ATWS AC Circuit Voltace Dron The team's review of the system design associated with the ATWS uninterruptable power supply (UPS), 1R14-S013, which feeds panel l
EV-1-B revealed the following weakness:
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The setpoint of the low voltage transfer to the backup power
source was 108i2Vac.
This could allow a transfer as low as 106Vac.
The ATWS DC power supplies fed from the circuits powered by this UPS have a minimum design input voltage of 103.5Vdc.
An approximate calculation of the voltage drop in one of these branch circuits indicated a 5 to 10 volt drop.
This indicated the potential for operation of these ATWS AC power supplies below their design minimum voltages.
The team Getermined that this weakness was not safety significant since it was unlikely that a sustained inverter output voltagc at 106Vac would occur without an inverter failure.
An inverter failure would cause a rapid transfer to the standby transformer.
The licensee committed to perform vc1tage drop calculations for
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all feeders circuits terminated in panels EV-1-A and EV-1-B.
Pending further NRC review, this is considered to be an open item (440/91005-07(DRS)).
2.2.5 Inverter Output Reaulation The team noted that the licensee had not tested the output voltage of the control room inverters to the range of DC supplied input voltages specified in the USAR.
The licensee had only tested the cutput regulation of these inverters at 129Vdc input.
USAR Section 8.3.2.1.2.3 stated that the 125Vdc system and associated loads and controls were designed to operate from 140-105Vdc.
The licensee stated the inverters would maintain an output voltage of 120Vac 2%.
However, the licensee had not demonstrated that the AC output regulation of the inverters would
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operate in the 140-105Vdc input range.
The team considered lack of adequate inverter testing tc be a weakness.
2.2.6 Conclusion The team determined that the overall design and installation of the DC systems were acceptable.
Design attributes were retrievable and verifiable.
Calculations were acceptable; however, more attention was needed in the area of low voltage branch circuit analysis.
The team also concluded that DC system design has sufficient design margin to allow significant load growth.
Most of the concerns noted above were due to insufficient attention to equipment and system details when performing DC system analyses.
2.3 Mechanical Systems The team reviewed the adequacy of the mechanical system design for support of the SDGs.
The review included system walkdowns, examination of the mechanical support systems' design documentation, engineering, vendor, purchasing and plant operations documents including the USAR, TS, and Regulatory Guides.
The team examined mechanical system calculations, process and instrument diagrams, pump and fan performance curves, tank capacities, heating, ventilation and air conditioning (HVAC) flow diagrams, manufacturer's technical manuals and detailed component drawings.
2.3.1 Electrical Space Heaters in SDG Rooms The team was concerned that the electric heaters in the SDG rooms could fall during a seismic event and sever instrument air lines associated with the air start receivers.
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l-The licensee produced calculations demonstrating that the heater supports had been evaluated per Calculation No. 36.01.3.2.56.45.
The team determined that these calculations did not address the construction of the heater itself and its method of attachment to the supports.
The licensee provided a supplementary response which included a PNPP Work Request to examine the method of heater attachment, thread engagement of the support rod and the addition of a double lock nut feature to prevent rotation due to vibration.
This response was accepted by the team.
2.3.2 Diesel Fuel Oil Storace Tank Linina i
The team noted that an analysis of sludge from the bottom of the
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90,000 gallon fuel oil storage tanks indicated that a percentage of the sludge was due to degradation of the tank internal i
i coating.
The licensee had determined that the existing coating was not formulated for use in fuel oil immersion service.
The
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licensee was currently conducting tests on epoxy tank linings to
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select a new lining material.
The team was concerned that the degradation of the coating could result in clogged filters and injectors and affect the operability of the diesels. The licensee plans to replace the tank lining during the next refueling outage.
This is considered an open item pending the licensee's replacement of the degraded coating (440/91005-08(DRS)).
2.3.3 SDG Fuel Transfer Pump Operation The licensee identified that the six diesel generator fuel transfer pumpc could not be operated manually although the
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l licensee's surveillance procedures referenced the manual operation of the pumps.
There was no evidence to indicate that the manual start function had been tested.
The licensee issued Field Change Request (FCR) 14949 on January 7, 1991, to restore i
manual start capability to the pump as originally designed.
I However, the licensee did not correct the errors in the
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procedures until May 3, 1991, when the licensee issued a l
temporary change to revise the procedures.
The above indicates weaknesses in testing and the corrective action program.
i 2.3.4 Conclusions The team concluded that the design and operability of the mechanical systems supporting the SDGs at PNPP were fully demonstrated during the course of the inspection.
Licensee personnel responded quickly to all questions and concerns raised by the team.
In general, the team found the licensee's staff to
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i be well qualified and highly knowledgeable in their respective fields of expertise, particularly the design, installation, and operability of the SDGs and HVAC systems.
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j 3.0 Encineering_and Technical Support (E&TS1 During the inspection, the team evaluated Perry Nuclear Power Plant's E&TS capability.
The team reviewed the licensee's temporary modification program, permanent modification program, 10 CFR 50.59 evaluation program, Quality Assurance audit and verification program, adequacy of engineering interface with the various departments and the training of electrical engineers.
In addition, the team reviewed the rcot cause analyses for licensee event reports (LERs) and operation of the independent safety engineering group (ISEG).
3.1 Modification Program The team noted that the number of open lifted leads, jumpers, temporary electrical devices and mechanical foreign items appeared excessive.
There were over 100 temporary modifications installed in the plant.
The licensee had taken corrective actions to limit the number of temporary modifications and a review of open modifications did not reveal any that circumvented the design change process.
3.2 Eng.ineerina Interfaces The cooperation and inter-departmental relationships with the electrical engineering group appeared to be excellent.
The engineering group (system engineers) and the design engineers were working together to reduce temporary modifications and to expeditiously complete design changes.
The mix of experienced and new engu 'ers was very good with a majority of the electrical engineers having more than six years of onsite engineering experience.
The team considered the onsite experience and working relationship between engineering and other sections of the plant staff to be a strength.
3.3 Electrical Eng.ineer Training TDe team noted that more than half vf the electrical design engineers and three of the electrical system engineers had not completed the five week electrical systems and components course for engineers.
The team considered this to be a weakness in the implementation of the engineer's training program.
3.4 Pe rs on_ne l tLr_ron The team observed that approximately 351 of the condition reports, the source documents for licensee event reports (LERs),
reviewed during the inspection were attributed to personnel errors.
Licensee management was aware of this large number of personnel errors and had initiated a significant corrective action program to reduce or elininate errors including improved working relationships, establ ;hing accountability with manager.
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and supervisors for personnel errors and improved training and tagout procedures.
3.5 Independent Safety Encineerino Group (ISEGL The team noted that effectiveness of the ISEG has been significantly improved since the review conducted in June 1989 by the NRC Diagnostic Evaluation Team.
The ISEG is now staffed with full time, qualified and experienced personnel.
Administrative controls have been developed and implemented to enhance the effectiveness of the ISEG.
Effective controls are in place to assure tracking of ISEG recommendations and responses from affected departments, The ISEG program requires disputed recommendations to be evaluated by corporate management for resolution.
3.6 Load Growth Procram The team noted that the system for load growth on feeders, inverters, batteries, and breakers was fragmented and lacked control.
However, except for a few discrepancies, the tabulation of SDG loads dated February 1991 was acceptable.
Currently the system relies on completion of the " Interface Review Checklist" l
contained in NEI-0330 and revision of specific calculations relative to the inverters, breakers, batteries, and feeders.
While this system was adequate, it could be stressed in the future when the plant has done more modifications to these systems and has reduced existing margins,
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The following weaknesses were noted in the program:
The lack of procedures to control load growth.
- The lack of normalized tabulations of loads (Amps, Watts,
etc) listing each load on the feeders, inverters, batteries,
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and breakers for all normal and emergency conditions.
This
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would establish the design basis for these systems and allow the engineers to assess the additions of load without first revising calculations.
The loads could then be totaled and compared to the continuous and emergency ratings of the buses, feeders, transformers, and cables.
The licensee committed to enhance Procedure No. NEI-0330 to more clearly flag potential load growth related design changes and to consider and implement, as appropriate, additional enhancements l
to their program.
The team had no further concerns.
l 3.7 Conclusions The team found that the licensee provided adequate E&TS to the operational staff.
The improvement of the ISEC functions and administrative controls was a noted strength.
The lack of timely
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training for electrical engineers and the continued high percentage of personnel errors were noted weaknesses.
3.8 Material Condition The team walked down the EDS to assess the overall material condition of installed EDS components.
Material condition of the installed equipment was good.
External and internal cleanliness of EDS components was excellent.
However, the team observed a supply and tool cabinet near the Clasc lE switchgear that was not anchored and could create a missile hazard during a seismic event.
In the essential service water pumphouse, the team observed a barrel filled with trash and scrap lumber set in close proximity to the Class 1E ESW control panel.
The licensee took immediate action to remove these items from the vicinity of the Class 1E equipment.
4.0 Inspection of Unit 2 Preservation Activities (92050)
The inspector reviewed the licensee's current program for maintaining stored-in-place plant structures, systems and compor<e nts ; material in the outside (laydown) areas and i
components and materials stored within the warehouse complex.
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The program and implementing procedure delineate the
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requirements, responsibilities and activities necessary to preserve the plant structures, systems, components and materials until the resumption of Unit 2 const.ruction activities.
The program, as implemented, appeared adequate to ensure plant preservation through the foreseeable future.
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The inspection included an observation of the condition of materials and components stored in the outside storage areas, pipe and HVAC ductwork laydowa area at the Parmly Road location, the cable yard near the training center, and tanks and miscellaneous material stored in the outdoor areas in the warehouse complex.
In general, the material and components were
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in good condition.
Work orders had been issued to remove I
corrosion deposits and touch up pipe coatings.
Weed eradication
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activities were in progress in the laydown areas around pipe i
spool pieces and HVAC ducts.
In general, Unit 2 was well maintained.
Parts and components removed for use in Unit 1 were accounted for by use of tags and a computer tracking system.
Stored-in-place components were protected from adjacent activities by waterproof coverings and/or plywood crates.
Storage areas were clean and free of debris from construction activities.
5.0 Open Items i
Open items are matters which have been discussed with the licensee which will be reviewed further by the team and which
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involve some action
<>n the part of the NRC or the licensee or both.
Open items dicclosed during this inspection are discussed in Paragraphs 2.1.1, 2.1.3, 2.1.5, 2.1.7, 2.1.8, 2.2.2, 2.2.4, and 2.3.3.
6.0 Exit Interview The team conducted an exit meeting on May 24, 1991, at the Perry Nuclear Power Plant to discuss the major areas reviewed during the inspection, the strengths and weaknesses observed and the inspection results.
Licensee representatives and NRC personnel in attendance at this exit meeting are documented in Appendix A of this report.
The team also discussed the likely informational content of the inspection report with regard to documents
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reviewed by the team during the inspection.
The licensee did not identify any such documents or processes as proprietary.
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Appendix A Centerior Enercy (Cleveland Electric Illuminating Company (CEIll
- B.
E.
Beyer, Director, Administration Services L.
B.
Biddlecome, Unit Lead Engineer, Performance Engineering Section
- W.
E.
Coleman, Manager, Quality Assurance Section
- V.
J.
Concel, Manager, System Engineering
- P.
J.
Curran, Instrument and Control Technician
- D.
A.
D'Amico, Systems Engineer M.
Edelman, Senior Vice President, Centerior Energy
- J.
P.
Eppich, Manager, Mechanical Design Section
- R.
C.
Fobell, Electrical Engineer F. T.
Foster, Contract Administrator
- J.
F.
Fronckowiak, Quality Engineer
- G.
H.
Gerber, Senior Project Engineer, Electrical Design
- M.
W.
Gmyrek, Operations Manager
- M.
J.
Hayner, Acting Licensing Manager
- H.
L.
Hegrat, Lead Compliance Engineer
- D.
P.
Igyarto, Training Manager
- W.
R.
Kanda, Manager, Electrical Design Section
- S.
F.
Kensicki, Director, Engineering
>7 U,
- d.
P.
Moffitt, Lead Engineer, System Engineering
- S.
P. Morreale, Lead Electrical Engineer
- B.
E. Nelson, Lead HVAC Design Engineer
- A.
P.
Pusateri, Lead HVAC/ Diesel System Engineer E.
Riley, Director, Quality Assurance
- R.
A.
Stratman, General Manager, Perry Nuclear Power Plant
- B.
D.
Walrath, Manager, Engineering Project Support
- E.
C.
Willman, Senior Project Engineer, Electrical Unit U.
S.
Nuclear Reculatory Commission (NRC)
- T.
Martin, Deputy Director, Division of Reactor Safety
- R.
Gardner, Chief, Plant Systems Section
- P.
Hiland, Senior Resident Inspector
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G.
O'Dwyer, Resident Inspector l
- R.
Winter, Reactor Inspector W.
Scott, Reactor Inspector
- Denotes those attending the exit meeting.
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