Part 21 Report - 1998-071
ACCESSION #: 9801220103
LICENSEE EVENT REPORT (LER)
FACILITY NAME: Clinton Power Station PAGE: 1 OF 5
DOCKET NUMBER: 05000461
TITLE: Incorrect Cable Resistance and Brake Horsepower Data Used
in the Design Divisions 1 and 2 Emergency Diesel
Generator Vent Fans Results in Design of Fan Motors Being
Outside the Design Basis of the Plant
EVENT DATE: 09/29/96 LER #: 97-034-00 REPORT DATE: 01/16/98
OTHER FACILITIES INVOLVED: DOCKET NO: 05000
OPERATING MODE: 5 POWER LEVEL: 000
THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR
SECTION:
50.73(a)(2)(ii), OTHER
LICENSEE CONTACT FOR THIS LER:
NAME: A.B. Haumann, Nuclear Engineering TELEPHONE: (217) 935-8881,
Department Extension 4078
COMPONENT FAILURE DESCRIPTION:
CAUSE: SYSTEM: COMPONENT: MANUFACTURER:
REPORTABLE NPRDS:
SUPPLEMENTAL REPORT EXPECTED: YES EXPECTED SUBMISSION DATE 03/19/98
ABSTRACT:
Station engineers determined that during degraded voltage conditions, the
Divisions 1 and 2 emergency diesel generator (EDG) room vent, fans could
cause offsite power supply breakers to trip on undervoltage during
transient electrical bus loading conditions associated with a Lose of
Coolant Accident (LOCA) block start. Improper cable resistance values
and brake horsepower ratings were used in the original design of the
Divisions 1 and 2 EDG vent fans. The cable resistance values, provided
by Sargent & Lundy, did not account for the fans' "tin-coated" copper
conductor cables which have a higher resistance than uncoated conductor
cables. Additionally, the brake horsepower of the fan motors was based
on an operating temperature of 96 degrees Fahrenheit (F). The Divisions
1 and 2 EDG room vent fans are required to operate at temperatures below
96 degrees F and thus higher than originally calculated brake horsepower
is required for proper operation. The cause and corrective actions for
this event have not been determined at this time, The cable resistance
issue in also reportable under 10CFR21.
END OF ABSTRACT
TEXT PAGE 2 OF 5
DESCRIPTION OF EVENT
On October 23, 1997, the plant was in Mode 4 (COLD SHUTDOWN) for the
sixth refueling outage (RF-6), and reactor [RCT] coolant temperature was
being maintained within a band of 100 to 120 degrees Fahrenheit (F) and
pressure was zero pounds per square inch (psi). Engineers were
investigating degraded voltage margins and identified that at least five
electrical voltage calculations for the Alternating Current (AC) [ED] and
Direct Current (DC) [EJ] electrical distribution system design used
improper cable [CBL] resistance data provided by Sargent & Lundy (S&L) in
Table B of S&L Standard ESA-102, "Electrical Engineering Standard for
Electrical and Physical Characteristics or Class B Electrical Cables."
The standard established the Clinton Power Station (CPS) design basis
cable resistance used for determining cable tray [TY) loading and voltage
drop calculations. Per S&L Power and Control Cable Specification
STD-EA-253, "General Specification for Power and Control Cable Insulated
with Ethylene-Propylene Rubber," CPS cables with voltage ratings below 5
Kilovolts (KV) have "tin-coated" copper conductors, however, Table B of
Standard ESA-102 provides resistance data for "uncoated" copper conductor
cables. Coated cables have higher resistance values than uncoated cables
and yield slightly lower equipment terminal voltages than established in
at least five electrical calculations. Condition report 1-97-10-414 was
written to Investigate and track the issue. The Operations Shift
Supervisor (SS) entered additional restraints against restoring
operability for Technical Specification (TS) Limiting Condition for
Operation (LCO) 3.8.2, "AC Sources-Shutdown," and 3.8-10, "Distribution
Systems-Shutdown," as operability per these TS LCOs was already
restrained for other reasons.
On December 19, 1997, engineering determined that the Divisions 1 and 2
emergency diesel generator room vent fans [FAN], 1VD01CA and 1VD01CB,
could cause a loss of offsite power during a LOSS of Coolant Accident
(LOCA) block start coincident with a degraded voltage condition. This
determination was based on increased cable resistance due to tin coated
conductors and higher than originally calculated fan brake horsepower.
The brake horsepower for these fan motors is based an a fan operating
temperature of 96 degrees F. Analysis has identified that the fans are
required to operate at temperatures below 96 degrees F. As air
temperature decreases more horsepower is required to drive the fans. The
combination of increased brake horsepower and cable resistance could
cause the Divisions 1 and 2 emergency diesel generator room vent fans to
exceed a 13 second starting time under degraded voltage conditions. CPS
degraded voltage analysis calculation 19-AQ-02, assumes that the 1VD01CA
and 1VD01CB fans accelerate to operating speed in less than 13 seconds.
Failure of the fans to start in 13 seconds could cause the offsite power
supply breakers [BKR] to trip on undervoltage due to transient loading
during a LOCA block start resulting in a lose of offsite power.
Considering the increased cable resistance due to tin-coated copper
conductors and increased brake horsepower due to colder air temperatures,
the assumptions of calculation 19-AQ-02 may not be valid. Therefore, the
design of the Divisions 1 and 2 emergency diesel generator room vent
fans, 1VD01CA and 1VD01CB, in not in accordance with the design basis of
the plant. The operability of Division 3 emergency diesel generator room
vent fan is not affected by this condition.
TEXT PAGE 3 OF 5
The tin coated copper conductors and increased brake horsepower
conditions for the Divisions 1 and 2 emergency diesel generator room vent
fans have existed since initial plant licensing on September 29, 1966.
At that time the plant was in Mode 5 (REFUELING) for initial fuel
loading, and reactor coolant temperature wag ambient and pressure was
atmospheric.
No automatic or manually initiated safety system responses were necessary
to place the plant in a safe and stable condition. This event was not
affected by other inoperable equipment or components.
CAUSE OF EVENT
The cause for this event is still under investigation and will be
provided in a revision to title report.
IP expects to issue a revision to this report identifying the cause,
corrective actions, agreement of the safety consequences and
implications, and previous similar events by March 19, 1998.
CORRECTIVE ACTIONS
This corrective actions for this event have not been determined but will
be provided in a revision to this report.
ANALYSIS OF EVENT
This event is reportable under the provision of 10CFR50.73 (a) (2) (ii)
(B) due to the design of the 1VD01CA and 1VD01CB fan motors being outside
the design basis of the plant.
An assessment of the safety consequences and implications of this event
will be provided in a revision to this report.
ADDITIONAL INFORMATION
No equipment or components failed as a result of this event.
Previous similar event information regarding this event will be provided
in a revision to this report.
For further information regarding this event, contact A. B. Haumann,
Engineering Projects, at (217) 935-8881, extension 4078.
TEXT PAGE 4 OF 5
10CFR21 REPORT 21-97-051
On October 23, 1997, Engineers were investigating degraded voltage
margins and identified that at least five electrical voltage calculations
for the Alternating Current (AC), and Direct current (DC) electrical
distribution system design used improper cable resistance data provided
by Sargent & Lundy (S&L) In Table 2 of S&L Standard ESA-102, "Electrical
Engineering Standard for Electrical and Physical characteristics of Class
B Electrical Cables." The standard established the Clinton Power Station
design basis cable resistance used for determining cable tray loading and
voltage drop calculations. Per S&L Power and Control Cable Specification
STD-EA-253, "General Specification for Power and Control Cable Insulated
with Ethylene-Propylene Rubber," CPS cables with voltage ratings below 5
Kilovolt (KV) have "tin-coated" copper conductors; however, Table B of
standard ESA-102 provides resistance data for "uncoated" copper conductor
cables. Coated cables have higher resistance values than uncoated cables
and yield slightly lower equipment terminal voltages than established in
at least five electrical calculations. Condition report (CR) 1-97-10-414
was written to investigate and track this issue. IP determined that this
condition was potentially reportable under 10CFR, Part 21 on October 25,
1997. IP has completed an revaluation of this issue and concludes that
it in reportable under the provisions of 10CFR, Part 21.
IP is providing the following information in accordance with
10CFR21.21(d)(4). Initial notification of this matter will be provided
by facsimile of thin letter to the NRC Operations Center in accordance
with 10CFR21.21(d)(3) within 2 days of the data the responsible officer
approves this report.
(i) Walter G. MacFarland IV, Chief Nuclear Officer of Illinois
Power Company, Clinton Power Station, highway 54, 6 miles East,
Clinton, Illinois, 61727, is informing the NRC of a condition
reportable under the provisions of reportable under the
provisions of 10CFR21 by means of this report.
(ii) The basic component involved in this report is the use of an
incorrect design standard, S&L standard ESA-102, in the design
of the cables installed at Clinton Power Station.
(iii) The cable design using S&L standard ESA-102 was supplied to CPS
by Sargent & Lundy.
(iv) As discussed in the DESCRIPTION OF EVENT portion of this
report, the nature of the defect is inaccurate cable resistance
values supplied in S&L standard ESA-102 report for design of
cables rated below 5 KV. This information was used in
electrical voltage calculations for the AC and DC electrical
distribution systems.
As discussed in the DESCRIPTION OF EVENT portion of this
report, under degraded voltage conditions, the impact of
increased cable resistance in conjunction with air temperatures
below 96 degrees F an the Divisions 1 and 2 emergency diesel
generator room vent fans could cause offsite power supply
breakers to trip on low voltage during a LOCA block start. A
loss of offsite power reduces Clinton Power Station's defense
in depth during a LOCA.
TEXT PAGE 5 OF 5
(v) On October 23, 1997, Illinois Power identified that improper
cable resistance values from data provided by Sargent & Lundy
In Table B of S&L Standard ESA-102 wave used in at least five
electrical voltage calculations for the AC and DC electrical
distribution systems IP determined that this issue was
potentially reportable under 10CFR, Part 21 on October 25,
1997.
(vi) The Improper cable resistance values were used to determine
cable tray loading and voltage drop of cables rated for less
than 5 KV at CPS. Those applications have been evaluated and
IP has concluded that this issue adversely affects the
Divisions 1 and 2 emergency diesel generator room vent fans,
1VD01CA and 1VD01CB, IP is not aware of other facilities that
stay be affected by this issue. The supplier of the improper
cable assistance values (Sargent & Lundy) is aware of this
issue.
(vii) The corrective actions that IP will take for this event have
not been determined but will be provided in a revision to this
report.
(viii) IP has no additional information to offer.
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