ML20245F690
| ML20245F690 | |
| Person / Time | |
|---|---|
| Site: | Peach Bottom  |
| Issue date: | 04/20/1989 |
| From: | Strosnider J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| To: | Corbin McNeil PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC |
| References | |
| NUDOCS 8905020465 | |
| Download: ML20245F690 (2) | |
See also: IR 05000277/1989007
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APR 2 01989
Docket Nos. 50-277
50-278
Philadelphia Electric Company
ATTN: Mr. C. A. McNeill
Executive Vice President-Nuclear
Correspondence Control Desk
P. O. Box 7520
Philadelphia, Pennsylvania 19101
Gentlemen:
Subject: Inspection Nos. 50-277/89-07 and 50-278/89-07
This letter refers to your letter dated March 17, 1989, in response to concerns
identified during the NRC special electrical team inspection as presented at
the exit meeting on February 10, 1989 and transmitted in a subsequent letter
dated March 24, 1989
Thank you for informing us of the corrective and preventive actions documented
in your letter. We note that Attachment I to your letter consists of one page
and appears to be incomplete. We would appreciate it if you could forward a
complete copy of the subject attachment. Your corrective actions with regard
to the subject concerns will be examined during a future inspection of
your licensed program.
Your cooperation with us is appreciated.
Sincerely,
Original Signed:By:
Jack R. Strosni. der
Jack Strosnider, Chief
Engineering Branch
Division of Reactor Safety
8905020465 890420
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G ADOCK 05000277
pg - i
0FFICIAL RECORD COPY RL PB 89-07 - 0001.0.0
04/19/89 gg
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. APR 2 01989 1
Philadelphia Electric' Company 2
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-cc w/ enc 1:
John S. Kemper, Sr , Senior Vice President-Nuclear )
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J. W. Gallagher, Vice President, Nuclear Services
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E. C. Kistner, Chairman, Nuclear Review Board j
Dickinson M. Smith, Vice President, Peach Bottom Atomic Power Station 1
Jack drban, General Manager, Fuels Department, Delmarva' Power & Light Co. i
John F. Franz, Plant Manager, Peach Bottom Atomic Power Station )
Troy B. Conner, Jr., Esquire
W. H. Hirst, Director, Joint Generation Projects Department,
Atlantic Electric
Bryan W. Gorman,: Manager, External Af fairs
Eugene J. Bradley, Esquire, Assistant General Counsel (Without Report)
Raymond L. Hovis, Esquire
Thomas Magette', Power Plant Siting, Nuclear Evaluations
W. M. Alden, Director, Licensing Section
Doris Poulsen, Secretary of. Harford County Council
Public Document Room (PDR)
local Public Decument Room (LPDR)
Nuclear Safety Information Center (NSIC)
NRC Resident Inspector
Commonwealth.of Pen 1sylvania
bec w/ enc 1:
Region.I Docket Room (with concurrences)
";n;;;= nt ^.;;i ct:n t , DR"^ ' (;'/c en:1)
Section Chief, DRP
PAC (23) SfiP :nd (2) E:pectier Reports
Robert'J.' Bores,.DRSS
- R. Martin,-NRR
M. Johnson, EDO
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RI:pDRS
Koshy/pmb Mathew Anderson
4//3 /89 4//3/89 4//f/89
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OFFICIAL RECORD COPY RL PB 89-07 - 0002.0.0
04/12/89
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PHILADELPHIA ELECTRIC COMPANY
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, 2301 MARKET STREET
P.O. BOX 8699
PHILADELPHIA A PA.19101
(21s) e414502
S. J. KOWALSKI
vlCE-PRE 5tOENT
muc6s an s neeno e mene
March 2 7,1989
Docket Nos. 50-277
50-278
U. S. Nuclear Regu3atory Commission
ATTN: Document Control Desk
Washington, DC 20555
SUBJECT: Peach Bottom Atomic Power Station, Units 2 and 3
Special Electrical Team Inspection
50-277/89-07 and 50-278/89-07
REFERENCE: Letter from S. J. Kowalski (PEco) to D. S. Nuclear Regulatory
Commission dated March 3, 1989
Dear Sir:
This 3etter provides an advance response to the potential restart issues
identified by the NRC during the Specia] Electrica) Team Inspection which was
conducted January 30 through Febrenry 10, 1989. At the exit meeting for the
inspection, seven potential restart issues were identified. One of the seven
issues, " underrated fuse and wrong type of fuse", was a two part issue. In
subsequent telephone discussions with Mr. T. Koshy, Inspect $,n Team Leader, he
indicated that each part would be a separate restart issue.
In the 3etter referenced above, Ph13ade3phia Electric committed to
provide a response for each of these issues by March 17, 1989, assuming the
Inspection Report was issued in sufficient time prior to this date. Although
the Inspection Report has not been received by Philadelphia Electric, we are
providing our responses for each of the potential restart issues based on our
current understanding of them. These responses are provided as Attachments 3
through 8 to this 3etter. Calculations and supporting documentation for these
responses are available for your inspection at our corporate office. The
purpose of our submitting these advanced responses is to provide the NRC with
sufficient time to support efforts necessary for restart of Unit 2 in ear 3y
April , 1989.
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Please do not hesitate to contact us if you have any questions concerning
our interpretation or response to the restart issues.
Sincerely
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Attachment 1: Voltage Adequacy at DC MOV's
Attachment 2: Questionable Margin f 2B and 2D Battery
Attachment 3: Underrated Fuse
Attachment 4: Wrong Type of Fuses
Attachment 5: Lack of Surved33ance
Attachment 6: Questionable 13.8kv Switchgear Interrupting Capacity
Attachment 7: Adequacy of MCC Feeder Cable Ampacity Versus Breaker Settings
Attachment 8: Diesel Generator Load Analysis
cc: N.3 T..' Russell, Administrator, Region I, USNRC
C. J. Anderson, Section Chief, Region I, USNRC
T. P. Johnson, USNRC Senior Resident Inspector
T. Koshy, Lead Reactor Engineer, Region I, USNRC
R. E. Martin, Project Manager, NRR, USNRC
T. E. Magette, State of Maryland
J. Urban, De3marva Power
J. T. Boettger, Public Service Electric & Cas
H. C. Schwemm, Atlantic Electric
T. M. Cerusky, Commonwealth of Pennsy3vania
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Attachment 1
' TITLE: VOLTAGE ADEQUACY AT DC MOV's
PECO INTERPRETATION OF CONCERN
Several potential operability problems resulting from design deficiencies in power
supplies for safety related DC motor operated valves have recently been identified.
The NRC Information Notice No. 88-72 entitled, " inadequacies in the Design of DC
Motor Operated Valves", was issued to inform utilities of the potential problems in
the design of dc motor operated valves. It was expected that recipients would
review the NRC Information Notice for applicability to their facilities and consider
actions as appropriate. At the time of the NRC Special Electrical Team Inspection,
PECo had not completed its review of NRC Information Notice No. 88-72.
More recently the NRC issued NRC Information Notice No. 89-11 entitled, " Failure of
DC Motor Operated Valves to Develop Rated Torque Because of Improper Cable
Sizing."
Subsequent to the NRC Special Electrical Team Inspection, NRC Information Notice
No. 89-16 entitled " Excessive Voltage Drop in DC Systems" was issued. This notice
extends the concern of adequate voltage beyond DC motor operated valves.
PECO RESPONSE
INPO SER 25-88 is related to NRC Information Notice No. 88-72. Both of these
documents and NRC Information Notice No. 89-16 were received and are being
tracked in the Operating Experience Assessment Program.
The PECo position on issues of INPO SER 25-88 and NRC Information Notice 88-72
have been defined. It has been determined that a design review of dc motor
operated valves is required and includes the following activities:
A. Confirmation of the electrical design of MOV's in PBAPS Unit 2.
B. Confirmation of the electrical design of MOV's in PBAPS Unit 3.
To support the Unit 2 restart activities, item A has been evaluated as described
below, item B will be completed prior to restart of the Unit 3.
To evaluate the electrical design of dc motor operated valves in the PBAPS Unit 2,
calculations were performed to addrets the capability of each valve to accomplish
the required safety function under the minimum anticipated dc power distribution
system voltage combined with elevated temperatures resulting from postulated
design basis accidents.
This evaluation, which incorporated the concerns presented in NRC Information
Notice 89-16, indicated acceptable operability of dc MOV's with the exception of
the following valves:
MO-2-23-014 MO-2-23-019 MO-2-23-020
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For these valves the results of the calculations indicate that the motors, which utilize
step starting resistors, may not actuate their associated valves immediately under
the applicable limiting case system and environmental conditions. It was concluded j
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Attachment 2
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TITLE: QUESTIONABLE MARGIN OF 28 AND 2D BATTERY
PECO INTERPRETATION OF CONCERN
Site Question for Engineering SOE P-50080, which is the most recent evaluation of
the capacity of batteries 2BD001 and 2DD001, concludes that these batteries have a
design margin and aging factor of 1.0 and 1.15, respectively. IEEE Standard 485
recommends a design margin of 1.15 and an aging factor of 1.25 when sizing a new
battery. Therefore,it is not obvious that batteries 2BD001 and 2DD001 have
sufficient capacity.
PECO RESPONSE
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A new calculation has been prepared to evaluate the margin between the rated
capacity of the battories and the design load profile.This calculation uses the
existing calculations as a basis for the design load' profile and includes an allowance
of 5% for uncertainty in the magnitude of individualloads presently not confirmed
by field walkdown. The calculation evaluates the margin for both a 2 hour2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> and 4
hour duty cycle. The results are as follows:
Percent Margin Percent Margin
for 2 Hour for 4 hour4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />
Battery Duty Cycle Duty Cycle
2 AD001 104 97
280001 52 8
2CD001 104 97
2DD001 52 8
This new calculation also evaluates the consequences of removing the starting
resistors for various dc motor operated valve motors to resolve concerns related to
NRC Information Notice 88 72. The increased inrush current has an impact on the
battery load profile, reducing the available margin. _
PEco has decided to adopt a design load profile of less than four hours, consistent
with typical utility practice. Since the diesels start in approximately 10 seconds and
restore power to the 480V auxiliaries including the battery chargers within' 16
seconds after loss of offsite power, the batteries are only required to provide power
for approximately 16 seconds. Thus, the typical utility practice of using a design
load profile with a duration of two hours provides a significant degree of margin,
The results of the margin calculations, with the increased inrush current due to
removing starting resistors in response to NRC Information Notice 88-72, are as
follows:
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Percent Margin
for 2 Hour
. Battery Duty Cycle
2AD001 104
2BD001 21
2CD001 104
2DD001 21
IEEE Standard 485-1983, which is applicable for sizing a new battery, recommends a .
design factor of 1.15 and an aging factor of 1.25, for a total margin of 44E
However,IEEE Standard 450-1980, which is applicable for the ongoing assessment
of available margin, implies in Section 6.6, " Service Test," that a battery is
acceptable if it passes a service test which duplicates the design battery duty cycle,
as this demonstrates that the battery meets the design requirements of the system.
A battery is acceptable for continued use when the design load profile changes,
provided that a margin exists between the capacity of existing battery and that
required to meet the revised load profile.
The battery discharge tests performed in 1987 demor.strated that the tested
capacity of both batteries exceeded their rated capacity. Since battery capacity
normally decreases only a few percent during the first 10 years of battery life, PECo
concludes that the present battery capacity is still in excess of rated capacity.
Therefore; PECo concludes that the existing Unit 2 batteries are adequate for the
restart of Peach Bottom Unit 2 without further analysis or testing. Due to the
similarity of system design between Unit 2 and 3, confirmation of the adequacy of
the Unit 3 battery is expected. Nonetheless, a similar evaluation of the Unit 3
batteries will be comp 8eted prior to the restart of Unit 3.
PECo is proceeding to prepare new base line calculations to define the loading i
profile for each Class 1E battery in Units 2 and 3. These calculations will be based on I
field walkdown data to establish the load from individual components and will be j
used for load manr ement control to demonstrate that each battery is suitable for !
continued use in accordance with IEEE Standard 450. These calculations will be i
updated and formally revised on a regular basis to account for load changes as the
result of plant modifications and plant operating procedure changes. Walkdown
data is presently being collected, and preparation of these design basis calculations
for Unit 2 will be completed in 1989, and the calculations for Unit 3 will be
completed in 1990.
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TITLE: UNDERRATED FUSES
PECO INTERPRETATION OF CONCERN
NRC Information Notice 84-65 " Underrated fuses which may adversely affect
operation of essential electrical equipment" was issued on August 6,1984. This
notice identified the Gould-Shawmut TR-R100 fuses as having a dc voltage rating of
less than 250 volts.
During the recent NRC Special Electncal Team Inspection at the Peach Bottom
Atomic Power Station Units 2 & 3, the following Gould - Shawmut TR-R100 fuses
were identified in 250Vdc safety related applications:
Bus: 20D11
Circuit 29-1100
RHR Pump Suction
Cooling Valve MO-2-10-017
Bus: 30D011 :
Circuit 29-1100
RHR Pump Suction
Cooling Valve MO-3-10-017
PECO RESPONSE
in response to the concern of TR-R100 fuses installed in safety related 250VDC
applications, Non Conformance Reports (NCR's) P89050-216 and P89111-216 were
generated to resolve this issue at PBAPS Units 2 & 3. These NCR's have been
dispositioned a replace the TR-R100 Gould - Shawmut fuses with
TR-5100 Gould - Shawmut fuses. The installation of the safety related TR-5100 fuse
in MCC 20D11 (30D11) to replace the existing TR-R100 fuses will be completed prior
to restart of each unit.
The specifications for Gould - Shawmut TR-R and TR-5 fuses are described below:
Model TR-R TR-5
Ampere rating 100a 100a
Class RK5 RK5
Sym. Short Circuit Rating 200 KAIC 200 KAIC
UL Listed No Yes
l DC Voltage Rating (Per UL 198L) 200VDC 600VDC
The application of the TR-5100 fuse will provide a 600VDC rating while maintaining
coordination with the upstream protective device. Calculation EE-7 Section E6 has
been revised to document circuit coordination with the new TR-5100 fuse.
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Attachment 3
A design review of the 125/250VDC power system was performed that concluded
the ratings of the remaining fuses are appropriate for the design application. A
walkdown of the subject fuses has confirmed that the installed fuses match the
design drawings.
An engineering memorandum will be issued to electrical engineering and design
personnel to clarify the significance of AC and DC voltage ratings of DC
components. Special consideration for voltage the rating of fuses will be
highlighted. This memo will be issued prior to restart of Unit 2.
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TITLE: WRONG TYPE OF FUSEC
PECO INTERPRETATION OF CONCEfiN
A. The dc control fuses installed in 250 Vdc MCC 20D11 compartment 29-1112 _)
= and 29-1121 are 10A while other MCC compartments have 6A fuses in their
control circuits. The adequacy of this situation needs to be evaluated.-
B.1 Drawings E-26 and E 27 identify the fuses in fuse box 20D19 and 30D19 as
Bussman Class RK5 type FRN,250 Vac. The installed fuses are Gould i
Shawmut Class RK5, type TR-R 250 Vac. The adequacy of the Gould !
Shawmut fuses needs to be evaluated, i
8.2 Circuits 29-BD30604 and 29-BD30605 have 30A type "NON" and "KON" '
fuses installed while drawing E-26 indicates a type "FRN" fuse should be
used. This discrepancy needs to be evaluated.
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PECO RESPONSE
A. Inconsistency of Control Fuse Sizes in 250 Vdc MCC:
The primary purpose of a control fuse is to provide short circuit protection.
Control fuses are sized such that the interrupting rating is not less than the
maximum short circuit current of the control circuit. Although different
from the other control circuit fuses in the MCC 20D11, the existing 10A fuses
for compartments 29-1112 and 29-1121 provide adequate short circuit
protection.
To provide consistency of control circuit protection inside the Unit 2 MCC's,
the 10A fuses will be changed to 6A fast acting Bussman Limitron type fuses.
This work will be accomplished prior to restart of Unit 2. Any corresponding -
changes required in the Unit 3 MCC will be accomplished prior to restart of i
that unit.
B. Installed fuse type inconsistent with design documents:
1. An engineering evaluation indicated the time-current characteristics of
the Gould&.awmut TR-R fuse was similar to the Bussman FRN and .
resulted in no change to the electrical coordination,
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Non Conformance Report (NCR) P899025 312 wasinitiated and
dispositioned to reflect the installed Gould-Shawmut TR-R fuses on
single line drawings, E-26, sheet 1, and E-27, sheet 1. Calculation EE-7,
Section E6 was also updated to reflect the time-c'urrent characteristics
for the type TR-R fuses. This discrepancy was identified and
documented by PECo prior to the NRC Special Electrical Team
inspection. The related documentation has been revised and issued.
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2. An engineering evaluation was performed and showed that the 'l
installed 30A "NON" and "KON" fuses provide electrical system .
coordination with the 20H type FRN supply fuse in 125 Vdc panel
2BD306. However, to p ide consistency with the design documents,
the "NON" and "KON fu>es are being replaced with "FRN" type fuses ;
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as shown on drawing E 26, Sheet 1. This replacement will be completed
prior to restart of PB APS Unit 2.
A walkdown of the Unit 2125/250 Vdc system has confirmed that no
additional discrepancies exist between the single line drawings and the
installed fuses. A similar walkdown for Unit 3 will be done prior to restart of l
Unit 3. Any identified Unit 3 fuse discrepancies will be resolved prior to l
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Unit 3 restart.
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+ Attachment 5 ,
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TITLE: LACK OF SURVEILLANCE
PECO' INTERPRETATION OF CONCERN
The PBAPS 125V battery charger maintenance procedure M-57.4 does not include
maintenance for the AC and DC breakers internal to the battery charger. Is this
exclusion of breakers from Preventative Maintenance (PM) consistent with the
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PBAPS commitment and program for Preventative Maintenance for equipment and J
components or,is it an oversight where a vendor recommended maintenance has
not been included in the plant PM procedure? ,
if the exclusion of the breakers from the plant PM is an oversight,is this an isolated
deviation from the program or a result of programmatic weakness that would cause
recurrence of a similar nature if not corrected?
Relay 27FF in the Diesel Generator System was not included in the yearly PM or
Surveillance Testing. Is this calibration required to ensure operabilay or per vendor
recommendation and thus not included in PM or ST by an oversight? If it is an
oversight,is it an isolated case, or the result of a weakness in the PM program that
may cause a recurrence of a similar nature?
PECO RESPONSE I
The surveillance activity of safety related components such as the breakers and
relays is based on vendor recommendations given in Technical Manuals and EQ
documentation.
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To assure adequate surveillance is being maintained a detailed review of the
present PECo position on Equipment Surveillance, Generic Letter 83-28 actions, and 1
other identified concerns was performed. The results of the review are summarized
below:
1) Aspects of Generic Letter 83 28 addressing utility actions on vendor.
information for safety-related components have been fully responded to by
PECo.
2) PECo commitments of Preventative Maintenance and Surveillance in areas
identified in NRC Inspection Report 86-25 have been fulfilled. The Diesel
Generator Room Supply Fans and Battery Room Exhaust Fans have been
included in the Preventative Maintenance Program.
3) The Vendor Manual Update Program was completed in 1988, including the
revision of affected procedures.
4) PB APS has a committment to the Commonwealth of Pa. to have a program
defined for review, approval, and control of vendor manuals prior to restart of ,
Unit 2.
5) Vendor manuals reviewed during the preparation of this response were found
! controlled and up-to-date.
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Attachment 5
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'6)- Breaker and relay maintenance was included in the Plant Program where l
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require'd by the vendor. i
The 'AC and DC breakers identified during the inspection are installed in each -
battery charger. The basic function of the circuit breakers is to serve as a disconnect l
switch to isolate the battery charger from the AC and DC systems. 'Ine imakers are J
not used as protective devices either for thermal overload or short circuit current. )
The circuit breakers as designed are adequate to achieve their functions in the l
battery charger without routine calibration. Exercising the breakers during )
maintenance of the battery charger is sufficient to provide assurance of their i
intended function. The confirmation of equipment isolation will be included in the
PM program for each the battery charger prior to Unit 2 restart.
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Relay 27FF is a loss of field flashing voltage alarm relay, provided for each diesel
generator. Relay 27FF has been provided to detect a loss of the 125Vdc supply _
voltage to the exciter and to annunciate the loss of voltage after a 20 second time -
delay. Improper relay operation will not prevent the diesel generators from - !
starting or performing their safety function. The 27FF relays will be added to the
PM program associated with each diesel generator and will be functionally tested
prior to Unit 2 restart.
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Attachment 6
TITLE: QUES'TIONABLE 13.8 KV SWITCHGEglNTERRUPTING CAPACITY
PECO INTERPRETATION OF CONCERN
The NRC reviewed the PBAPS Calculation EE-7, Subsection E2 " AC System Fault
Calculation" and raised a concern regarding the low margin in the 13.8kv circuit
breaker interrupting duty. The margin was 1.3% as shown in the calculation.
The NRC also questioned the limiting case electrical' distribution bus configuration j
assumed in the subject calculation. This case assumed "the recirc pump M-G set 1
tripped, the auxiliary buses fast transferred to one offsite power source, and cooling i
towers D & E tripped". The NRC requested comparison of this case with the plant i
startup configuration of two recirculation pump M-G sets running on two offsite 1
power sources before transferring to the one auxiliary system. It was pointed out to
the NRC that the subject calculation is conservative as it did not include f actors such
as cable impedance. The NRC requested an evaluation of the conservatism in the
calculation.
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PECO RESPONSE
"AC System Fault Calculation" was prepared for the Appendix R Breaker / Relay _-
Coordination Study in 1986. The 1.3% margin of 13.8kv breaker interrupting
upacity is based on ANSI standard C37.010-1979.
The calculation has been revised to include the operating configuration case of two
recirculation pump M G sets running on offsite sources. The margin obtained is
11.2% as compared with 1.3%. This confirms that the existing selection of the worst
case operating condition was correct.
The calculation has also been up' d ated to quantify the conservatism resulting from
exclusion of the 13.8kv cable impedance. Accounting for cable impedance, the
marginincreases from 1.3% to 13.4%
Therefore,it is concluded that the PB APS Units 2 & 3 electrical system has adequate 'l
short circuit withstanding capability, as proven by the updated calculations. )
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Attachment 7
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l TITLE: ADEQUACY OF MCC FEEDER CABLE AMPACITY VERSUS BREAKER SETTINGS
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PECO INTERPRETATION OF CONCERN l
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Calculation EE-7, Subsection E-3, Page 5, notes that the long time delay settings of I
certain breakers feeding the MCC's exceed the ampacity of the feeder cables. As a
result, the possibility exists that without protective action, these cables may become 1
overloaded, and therefore overheated.
Calculation EE-7, Subsection E-3, documents breaker coordination. However,it does I
not document the MCC feeder cable ampacities exactly, nor does it document the l
design load on the MCC feeders. The determination of the adequacy of the breaker 1
settings for equipment and cable protection requires additional documentation. l
PECO RESPONSE
PECo has maintained the design philosophy that breakers feeding MCC's should be
set to avoid the possibilty of inadvertent tripping. PECo considers the continued ,
operation of Class 1E systems is more critical than preventing minor short duration
cable overloading.
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Feeder cables to individual loads require overcurrent protection, in addition to fault j
protection, since a compoaent 'ailure or individual fault could result in overloading '
of these dedicated feeder cables. However, cables to MCC's are not subject to the
same type of overloads as the feeders to individualloads. The MCC feeder cables l
require short circuit protection, but the overload protection is controlled by the 1
design process which limits the amount of load applied, rather than from breaker l
overcurrent protection settings. Therefore, the long time element of the MCC !
feeder breakers is not essential for cable overload protection. However, the l
continued operation of the MCC is essential for plant safety in the event of a design j
basis accident. Therefore,it is more prudent to set the long time delay element at a i
relatively high level to avoid the possibility of inadvertent tripping. l
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The cables feeding each MC . are sized on the basis of the anticipated running load
for the MCC. In response to the NRC Special Electrical Team inspection concern, a
reevaluation has been performed which confirms that the feeder cable ampacity l
exceeds 125% of the anticipated worst case running load on the MCC. Therefore,
there is no need to increase the size of any of the feeder cables. '
PECo therefore concludes that the design, as it stands, is adequate and imposes no
constraint on the restart of either Unit 2 or Unit 3.
PEco will revise calculation EE-7, Subsection E-3, to document the design philosophy
for MCC feeder long time cable protection and to confirm the adequacy of the cable
ampacity for the anticipated coincidentalloading.
PECo will review the feasibility and cost benefit of providing an improved design for
MCC feeder cable overcurrent protection. The review will be completed during the
next refuel cycle following restart of Unit 2 and 3.
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Attachment 8
TITLE: DIESM. GENERATOR LOAD ANALYSIS
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PECO INTERPRETATION OF CONCERN !
The NRC 5pecial Electrical Inspection Team identified inconsistencies between the j
emergency diesel generator loading calculation and the mformation presented in
the FSAR Table 8.5.2. !
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Based on these inconsistencies the adequacy of the diesel generator to supply )
power during a plant DB A and shutdown conditions was questioned. Specifically {
the following concerns were identified: l
1, Appropriate conversion of horsepower to KW loading of major !
indiviaual loads.
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2. Determination of the worst case dieselloading based on the l
conditions, described in the FSAR Table 8.5.2. )
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3. Confirmation that the diesel generators are capable of supplying the _
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identified worst case load for the required period of operation.
PECO RESPONSE
A review of the Diesel Generator and Emergency Bus Loading tables of the UFSAR '
show that the highest load occurs on DG El during the 10-60 minute time interval of
the DG loading cycle.
The totalload on DG El during this time interval consists c,f two 4 kV loads (one RHR
pump and one Core Spray pump) and two 480V load groups each of which is
supplied by a 500 KVA load center transformer.
The RH_R pump motor load has been conservatively calculated to be 1604 KW based
on the motor rating of 2000 hp and a fullload efficiency of 93%. This is the value. I
used for the RHR pump motor in the load tabulation of the Voltage Regulation
Study, dated January 1989. This value is considered conservative, as demonstrated
by the pump test curves. These curves indicate a pump runout condition of about
12,000 GPM rec uiring 1900 BHP, while the design rated flow of 10,000 GPM requires
1,800 BHP whic, equates to a 1,444 KW load at 93% efficiency.
The second 4 kV load on DG El is the core spray pump. The nameplate values of 600 '
horsepower and 93% efficiency result in a 481 KW design load.
Loads at 480V and below have been reviewed against the loads used in the Voltage
Regulation Study, the single line diagrams, and schematics to determine
conservative load values.
Since the major loads have been calculated on the basis of rated horsepower and i
nameplate efficiency, the potential for inadvertent overloading has been aveided
as described in Section 2 of Generic Letter 8815, power. factor misapplication.
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. Attachment 8
, The diesel generator is not operated for base load generation, and is only required ;
for sustained operation following a LOOP /LOCA and prior to restoration of offsite
power. Therefore the 200 hour0.00231 days <br />0.0556 hours <br />3.306878e-4 weeks <br />7.61e-5 months <br /> rating is applicable.
The total KW load, assuming conservative loadings as described above is 3,006 KW l
for DG E1. This load is within the 3,100 KW,200 hour0.00231 days <br />0.0556 hours <br />3.306878e-4 weeks <br />7.61e-5 months <br /> rating of the unit. It is
therefore concluded that the diesel generators are adequately rated to support
DBA loading for Unit 2 and emergency shutdown of Unit 3.
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