IR 05000395/1993010
| ML20035F274 | |
| Person / Time | |
|---|---|
| Site: | Summer  |
| Issue date: | 04/14/1993 |
| From: | Fillon P, Steven Rudisail, Shymlock M NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| To: | |
| Shared Package | |
| ML20035F270 | List: |
| References | |
| 50-395-93-10, NUDOCS 9304210106 | |
| Download: ML20035F274 (10) | |
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NUCLEAR REGULATORY COMMISslON
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j 101 MARtETTA STREET.N.W.
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Report No.:
50-395/93-10 Licensee:
South Carolina Electric & Gas Company Columbia, SC 29218 Docket No.: 50-395 License No.: NPF-12 Facility Name:
V. C. Summer Nuclear Station Inspection Conducted: March 15-19, 1993 Inspectors 4[/%['f3 P.Filliodf Dat6 Sfgned ik S. bS f
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~S. Rudisail Date Signed Approved by:
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4/b93 Milton K. Stiyflyock, Chief Date Signed Plant SystemVSection Engineering Branch Division of Reactor Safety SUMMARY Scope:
This special, announced inspection was conducted in the areas of design of electrical systems and related engineering activities.
NRC Temporary Instruction 2515/111, Electrical Distribution System Followup Inspection, issued May 31, 1991, provided guidance for the inspection.
Results:
NRC Report 50-395/92-04 which documented findings from the EDSFI inspection
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states : "The inspection team's overall findings were generally positive,
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reflecting good design, maintenance and testing." Similarly, the licensee's efforts to address the findings from the EDSFI were thorough, and nearly all open items were closed out during this inspection. Two items remain open from the original inspection as follows:
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9304210106 930414 PDR ADOCK 05000395 G
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. Unresolved Item 92-04-07, Failure to Provide Backup Protection for Electric Penetrations in the Overload Range of Currents (action required by NRC),
Section 2.f
Inspector Followup Item 93-10-02, Validation of System Model for Voltage
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Calculations, Section 2.g
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REPORT DETAILS 1.
Persons Contacted Licensee Employees A. Barth, Civil / Structural Engineer, Design Engineering R. Brady, Electrical Engineer, Design Engineering B. Brown, Supervisor, Electrical Plant Support Systems
- M. Browne, Manager, Design Engineering
- S. Carroll, Sr. Electrical Engineer, Design Engineering J. Derrick, Supervisor, Design Engineering H. Donnelly, Electrical Engineer, Design Engineering
- R. Fowlkes, Manager, Nuclear Licensing
- J. Graham, Nuclear Licensing & Operating Experience M. Hazel, Mechanical Engineer, Design Engineering
- S. Hunt, Manager, Quality Systems
- A. Koon, N0D Project Coordinator
- C. Price, Engineering Services Project Coordinator
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- H. Quinton, General Manager Engineering Services l
- L. Shealy, Sr. Engineer, Quality Engineering l
- J. Skolds, Vice President Nuclear Operations R. Slone, Systems and Performance Engineering W. Stuart, Systems and Performance Engineering V. Taylor, Systems and Performance Engineering A. Torres, Associate Manager, Quality Control
- R. Waselus, Manager, Systems and Performance Engineering
- K. Woodward, Manager, Nuclear Training Other licensee employees contacted during this inspection included engineers, technicians, and administrative personnel.
Other NRC employees:
- L. Keller, Resident Inspector
- Attended Exit Meeting
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l 2.
Electrical Distribution System Functional Inspection Followup (TI 2515/111)
For each of the weaknesses identified by the EOSFI team, the licensee agreed to take specific corrective actions which were either described i
in the report (50-395/92-04) or in their responses to the notices of violation and deviation. In addition there were two unresolved items for j
which the NRC performed additional review. The focus of this inspection
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was to follow up on these matters. Where possible, the licensee's work, 1.e. calculations, procedure changes etc., was inspected to determine whether or not the original issue was resolved.
Each issue is summarized in this section, the inspection activity is described, and the current status is stated. At the end is an overall summary and conclusion statement.
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a.
Violation 92-04-01, Undersize Thermal Overloads and Inadequate Tubing Supports.
The EDSFI team had found that tubing furnished by the diesel generator manufacturer and mounted on the engine did not have-support points consistent with the seismic qualification document.
Tubing bundles which ran along the side of the engine were properly supported. The problem area was tubing at the front and rear ends of the engine. In these areas the tubing support spacing exceeded the guidelines. Analysis has shown that the "as-built" spacing was adequate. As stated in the response to the notice of violation, the licensee performed additional inspections of tubing during refuel outage VII which was ongoing at the time of this inspection. After removal of walkway steel on diesel generator A, tubing supports, which were hidden from view during normal operations, were inspected and found adequate. The same inspection would take place later in the outage on the other diesel generator. The inspector discussed this issue with the cognizant engineer and reinspected the tubing and supports. The inspector concluded that the corrective actions were being completed, and that the issue was resolved.
The EDSFI team had found that the criteria for selecting thermal overload relay heaters was deficient in that it did not consider the situation where the motor being protected was expected to run in the service factor region. A review of all safety-related
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motors and their demand factors made during the original
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inspection identified two motors that could run in the service factor region. The overload heaters for these motors were changed-
out during that inspection. _During this inspection (93-10), the l
licensee stated that they were making a new study of thermal i
overload relay selection to serve as a design basis document.
This study was beyond the corrective actions stated in the response to the notice of violation. They presented a copy of the completed, but unchecked, study to the inspector, and he could see that the service factor consideration was among the selection j
criteria in the study. Violation 92-04-01 is closed.
b.
Violation 92-04-03, Deficiencies in the Control of Drawings, Design Calculations, and Databases This violation involved errors in a set of drawings titled, " Motor Control Center Unit Listing". These drawings were in tabular form and contained information about the starters, breakers, fuses etc.
in the motor control centers. Various types of information did
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i not match the actual installation.
Furthermore, the licensee had two calculations covering the
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determination of voltage at the terminals of motor operated
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valves. One calculation, by Gilbert Associates, Inc, did not include the resistance of overload heaters. The other calculation,
by Impell Co., included the overload heater resistance, but some
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values of resistance were incorrect because they used the i
incorrect motor control center drawings as a source of information.
The root causes of these two problems were failure to update drawings after making changes in the field and a design control l
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l weakness. The licensee has taken adequate actions to correct these problems in the existing documents, and to prevent future I
recurrence.
The inspectors verified the following items:
(a)
The motor control center listing drawings had been updated i
based on field verified information.
(b)
The two voltage calculations had been revised, and results of the two reconciled.
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(c)
Electrical Maintenance Procedure EMP 280.001 was revised to call for engineering review of any changes to thermal overload relay heater sizes. This step would force update of the drawing.
(d)
The inspector looked at the following motor control center compartments to verify that the drawing information was correct: XMCIDA2X compartments 11K, 2EF, 41L, 11EF, 15IJ.
In consideration of the above facts, Violation 92-04-03 is closed.
c.
Violation 92-04-04, Inadequate Instructions for Application of Pre-Approved Disposition No.12 This violation involved a situation where the licensee's program would have allowed Class IE equipment to be replaced after failure of that equipment without any cause evaluation taking
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place. The inspectors confirmed that the corrective actions stated in the response to the notice of violation were carried out by the licensee. The inspectors examined the following documents:
(a)
Preapproved Disposition No. 12, Revision 2 i
I (b)
Preapproved Disposition No. 13, Revision 1, For Nonconformances that Require Engineering Evaluation (c).
Station Administrative Procedure SAP-ll41 Nonconformance Program, Revision 1
Revisions to these documents require that any time there is a need to replace a Class IE component due to failure of that component, that failure will be treated as a nonconformance and hence will j
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receive root cause evaluation. Since the corrective actions stated i
in the response to the violation were implemented by the licensee,
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Violation 92-04-04 is closed.
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d.
Deviation 92-04-05, Potential Deterioration of Emergency Diesel Generator. Underground Fuel Oil Piping and Tanks.
The Cathodic Protection System for the diesel generator fuel oil buried piping has not been working properly since 1980. This
situation constituted a deviation from NRC Regulatory Guide 1.137, j
Fuel-Oil Systems for Standby Diesel' Generators. The licensee made l
the following short-term and long-term commitments to rectify this deficiency:
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(a)
Excavate and examine a section of piping during refuel
outage VII.
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(b)
Examine the tanks and piping near the tanks during refuel outage IX.
(c)
Upgrade the Cathodic Protection System so that it will
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protect the piping from corrosion during refuel outage IX.
The inspector verified that item (a) had been carried out. Some
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corrosion was observed at a point where the return lines penetrate the diesel building wall. Corrosion was observed at points where i
the protective coating had imperfections. The worst case wall
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thickness for the 1.5 inch schedule 40 carbon steel pipe was
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determined to be 37 mils at a pin point. The conclusion from the
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inspection was that the piping would still perform its function.
l Application of proper coating would arrest further corrosion. The
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l inspector also confirmed that the long-term actions were in the
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licensee's tracking system. In consideration of the above, Deviation 92-04-05 is closed.
e.
Unresolved Item 92-04-06, Interpretation of Valid Emergency l
Diesel Generator Start Failure.
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The licensee's position was that an EDG failure to start would not be considered a valid failure if the EDG had been removed from
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service for maintenance. This appeared contrary to RG 1.108,
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position c.2.a.(7).
The NRC reviewed this matter further after the inspection. That review concluded the licensee's classification of the failure in question is consistent with Draft l
Regulatory Guide DG-1021. In consideration of the above, i
Unresolved Item 92-04-06 is closed.
f.
Unresolved Item 92-04-07, Failure to Provide Backup
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Protection for Electric Penetrations in the Overload Range of l
Currents.
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1 For approximately 45 of V.C. Summer's electric penetrations, full
protection was only provided by the primary device. Backup
protection provided protection against the maximum fault current i
.possible but not against current in the overload or low-level
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fault range. This matter is under review by the NRC, and therefore Unresolved Item 92-04-07 remains open.
g.
Calculation Case Needed to Validate the System Model Used in the l
Voltage Calculations (Report 92-04, Section'2.3.4)
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At the time the degraded voltage relays were installed, the
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licensee had validated the system model used in the voltage calculations. The validation was done according to the
recommendations in Branch Technical Position PSB-1. Since that time, they have adopted a new computer code.
Results obtained
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from the new program should have been validated in a similar i
manner to the original calculations, but this had not been done.
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During the EDSFI, the licensee stated they would run this validation case. This work is scheduled for 1993 or early 1994, i
Since the NRC would like to review the results of this computer
run, an Inspector Followup Item is established. It will be j
identified as IFI 93-10-02, Calculations.
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Validation of System Model for Voltage
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Diesel Generator Dynamic Analysis (Report 92-04, Section 2.4.2)
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l At the time of the EDSFI, the licensee stated they were planning l
l to perform a dynamic analysis to more accurately and precisely j
determine the voltage and frequency transient that accompanied j
interval block loading on the diesel generator. Since that time,
the licensee learned that it would be quite difficult to obtain
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all the necessary motor data. The inspector stated that the i
analysis and calculations already in place were sufficient to demonstrate the capacity and capability'of the diesel generator to accept the design load. Therefore, this item is closed, i.
Diesel Generator Start Permissives (Report 92-04, Section 2.4.3)
The team noted that the FSAR identified three engine parameters measured during EDG starting that could produce signals'which would disable the engine starting function. The parameters.are engine speed relay (115 rpm), engine speed relay (335 rpm), and jacket water pressure for engine. speed relay. The licensee. agreed to review this issue and if appropriate alarm these signals so that if they were present (such as from a failed relay) they would be known. The licensee has completed their review and issued a modification to add indication of these relays to' the EDG " ready for auto start" alarm. This modification is schedule for the current refueling outage. This item is closed.
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DC System Short-Circuit Calculation (Report 92-04, Section 2.5.4)
l The EDSFI team identified that the DC System short-circuit
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calculations were not carrying the proper value for the battery charger contribution to fault current. During this inspection, the inspectors verified that the calculation had been appropriately revised, and that the results were acceptable. This item is closed.
k.
Document Discrepancy (Report 92-04, Section 2.5.7)
The team's review identified errors in the trip ratings given in the EDS Design Basis Document and drawing E-201-362, sheet 2, for the MCC XMCIDB2Y circuit breaker feeding the swing charger. These two documents were revised, and this item is closed.
1.
Ground Detection System for DC System (Report 92-04, Section 2.5.8)
Licensee personnel explained that a modification to the system was being implemented which included installation of an automatic ground detection circuit on each DC bus. System Engineers stated that this modification has been completed. The detection circuit automatically places a high impedance ground on the system. The l
ground alternates between the positive and negative legs at five i
minute intervals. A contact making ammeter is set to alarm the presence of a ground fault. This item is closed.
m.
Resolution of Nonconformances (Report 92-04, Section 5.3)
In its review of engineering and technical support the team identified a potential weakness. The licensee's organization was such that a group within the design engineering organization had primary responsibility for resolving nonconformances. As a result, system engineers were not involved in the resolution process in many cases. This situation tends to undermine the effectiveness of the system engineers to take ownership of their
systems. The licensee stated that an objective of the upcoming reorganization would be to give more involvement to system engineers in the nonconformance process. This issue will be monitored by the Resident Inspectors as the reorganization takes effect.
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Inspector Follow-up Item 92-04-08, Preventive Maintenance for 7.2 kV Switchgear The team identified that inspection of the insulation of the 7.2 kV switchgear was not being performed as recommended by the manufacturer. Additionally, the team expressed concern that motor starter contactors were not being inspected. The licensee has revised all applicable procedures to include inspection of bus bar
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insulation and motor starter contactors. This item is closed.
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Inspector Follow-up Item 92-04-09, Preventive Maintenance Trip i
Testing of DC Molded Case Circuit Breakers i
The team identified that overcurrent trip testing of 125 VDC feeder circuit breakers for the load center busses was not being
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performed. The licensee agreed to add the overcurrent_ trip i
testing to the 125 VDC MCCB maintenance program. Also, the i
licensee stated th:t the 7.2 kV switchgear MCCB's would be J
exercised as part of their preventive maintenance.. The inspector l
verified that the_ procedures for maintenance of the 125 VDC feeder i
breakers was revised to include overcurrent trip' testing. The procedures.for exercising the 7.2 kV switchgear MCCB's was also l
reviewed. This item is closed.
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Calibration of Protective Relays (Report 92-04, Section 4.3.1)
The team identified that' the acceptance criteria of calibration procedures for the protective relays was indicated as a range but that setting the relay as close as possible to the set point was
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not a requirement. The licensee agreed that they.would enhance their calibration program by requiring more exact acceptance criteria. The inspector reviewed all applicable calibration
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procedures and found their revision satisfactory. This item is
closed.
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230 kV Switchyard Line Support Connections from the Turbine
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Building (Report 92-04, Section 4.2)
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The team noted that the 230 kV lines from the switchyard were i
supported at the sides of the turbine building. The team j
questioned whether these connections were ever inspected. The
licensee stated that a program to inspect these support connections would be implemented. The inspectors verified that procedures had been revised to implement this inspection. This item is closed.
3.
Exit Interview The inspection scope and findings listed below were summarized on March 19, 1993, with those persons indicated in Section 1.
Proprietary-information is not contained in.this report. There were no dissenting comments received from the-licensee.
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Item Number Description and Reference-
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395, 92-04-01 (Close) Undersize Thermal Overloads Violation -
and Inadequate Tubing Supports, Section 2.a i
395, 92-04-03 (Close) Deficiencies in the Control of-
Violation Drawings, Design Calculations and l
Databases, Section 2.b l
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395, 92-04-04 (Close) Inadequate Instructions for Violation Application of Pre-Approved Disposition, Section 2.c l
395, 92-04-05 (Close) Potential Deterioration of Deviation Emergency Diesel Generator Underground l
Fuel Oil Piping and Tanks, Section 2.d i
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395, 92-04-06 (Close) Interpretation of Valid Emergency
URI Diesel Generator Start Failure, Section 2.e l
395, 92-04-07 (0 pen) Failure to Provide Backup URI Protection for Electric Penetrations in the
Overload Range of Currents, Section 2.f
i 395, 92-04-08 (Close) Preventive Maintenance Inspections IFI for 7.2 kV Switchgear, Section 2.n
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395, 92-04-09 (Close) Preventive Maintenance Trip
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IFI Testing of Important DC Molded-Case
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Circuit Breakers to Verify Their Settings,
Section 2.0 l
i 395, 93-10-02 (0 pen) Validation of System Model for l
IFI Voltage Calculations,- Section 2.g j
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