IR 05000458/2018010
| ML18085B197 | |
| Person / Time | |
|---|---|
| Site: | River Bend  |
| Issue date: | 03/26/2018 |
| From: | Greg Werner NRC/RGN-IV/DRS/EB-2 |
| To: | Maguire W Entergy Operations |
| Werner G | |
| References | |
| BL-12-001 IR 2018010 | |
| Download: ML18085B197 (31) | |
Text
March 26, 2018
SUBJECT:
RIVER BEND STATION - NRC INSPECTION OF TEMPORARY INSTRUCTION 2515/194, INSPECTION OF THE LICENSEES IMPLEMENTATION OF INDUSTRY INITIATIVE ASSOCIATED WITH THE OPEN PHASE CONDITION DESIGN VULNERABILITIES IN ELECTRIC POWER SYSTEMS (NRC BULLETIN 2012-01) - INSPECTION REPORT 05000458/2018010
Dear Mr. Maguire:
On February 8, 2018, the U.S. Nuclear Regulatory Commission (NRC) completed an inspection at the River Bend Station. On February 8, 2018, the inspectors discussed the results of this inspection with you and other members of your staff. The results of this inspection are documented in the enclosed report.
The NRC inspectors did not identify any findings or violations of more than minor significance.
This letter, its enclosure, and your response (if any) will be made available for public inspection and copying at http://www.nrc.gov/reading-rm/adams.html and at the NRC Public Document Room in accordance with 10 CFR 2.390, Public Inspections, Exemptions, Requests for Withholding.
Sincerely,
/RA/
Gregory E. Werner, Chief Engineering Branch 2 Division of Reactor Safety
Docket No. 50-458 License No. NPF-47
Enclosure:
Inspection Report 05000458/2018010 w/ Attachments: 1. Table 1 - Information Gathered for Temporary Instruction 2515/194 2. TI 2515/194 Inspection Documentation Request
Enclosure U.S. NUCLEAR REGULATORY COMMISSION
Inspection Report
Docket Number:
05000458
License Number:
Report Number:
Enterprise Identifier: 000512/05000458/I-2018-010-0019
Licensee:
Entergy Operations, Inc.
Facility:
River Bend Station
Location:
Saint Francisville, Louisiana
Inspection Dates:
February 5, 2018, to February 8, 2018
Inspectors:
S. Graves, Team Lead, Senior Reactor Inspector, Region IV
S. Makor, Reactor Inspector, Region IV
Accompanying
G. Matharu, Senior Electrical Engineer, NRR/DE/EEOB
Personnel:
K. Nguyen, Electrical Engineer, NRR/DE/EEOB
J. Quichocho, Chief, NRR/DE/EEOB
Approved By:
G. Werner, Branch Chief, Engineering Branch 2
SUMMARY
The U.S. Nuclear Regulatory Commission continued monitoring licensees performance by conducting Temporary Instruction 2515/194, Inspection of the Licensees Implementation of Industry Initiative Associated with the Open Phase Condition Design Vulnerabilities in Electric Power Systems (NRC Bulletin 2012-01), at River Bend Station, in accordance with the Reactor Oversight Process. The Reactor Oversight Process is the Nuclear Regulatory Commissions program for overseeing the safe operation of commercial nuclear power reactors. Refer to https://www.nrc.gov/reactors/operating/oversight.html for more information.
List of Findings and Violations
None.
Additional Tracking Items
None.
INSPECTION SCOPE
This inspection was conducted using Temporary Instruction 2515/194 (ADAMS Accession No. ML17137A416), dated October 31, 2017. The inspectors reviewed the licensees implementation of Nuclear Energy Institute voluntary industry initiative in compliance with Commission guidance. The team discussed the licensees open phase condition system design and ongoing implementation plans with plant staff, Entergy Corporate staff and vendor staff.
The team reviewed licensee and vendor documentation, and performed system walkdowns to verify that the installed equipment was supported by the design documentation. The team verified that the licensee had completed the installation and testing of equipment (with the exception of the tripping functions), installed and tested alarming circuits both local and in the control room, and analyzed potential impacts associated with the design implementation on the current licensing basis.
OTHER ACTIVITIES
- TEMPORARY INSTRUCTIONS, INFREQUENT AND ABNORMAL
Temporary Instruction 2515/194 - Inspection of the Licensees Implementation of Industry Initiative Associated With the Open Phase Condition Design Vulnerabilities in Electric Power Systems (NRC BULLETIN 2012-01)
The objective of Temporary Instruction 2015/194 is to verify that licensees have appropriately implemented the Nuclear Energy Institute voluntary industry initiative including updating their licensing basis to reflect the need to protect against open phase conditions and to gather the information necessary for Office of Nuclear Reactor Regulation staff to determine whether the licensees have adequately addressed potential open phase conditions.
Temporary Instruction 2515/194-03.01 - Voluntary Industry Initiative (Part 1)
River Bend Station selected the open phase detection system designed and manufactured by PCS2000 Solutions, LLC, as the design vendor for the open phase condition system. At the end of this inspection the PCS2000 system was still in the monitoring mode of operation to facilitate continued data gathering of grid perturbations for evaluation of alarm and trip setpoints.
The open phase condition equipment was installed on the preferred station service transformers RTX-XSR1C and RTX-XSR1D which power the station vital busses. The licensee was scheduled to transition the PCS2000 system to full implementation (tripping functions enabled) in December 2018. The licensee was preparing the full implementation engineering changes and associated documents for this transition, however they were not available for review at the time of inspection.
Section 03.01 of the Temporary Instruction required the determination whether the licensee appropriately implemented the voluntary industry initiative, dated March 16, 2015 (ADAMS Accession No. ML15075A454), by verifying the following:
a. Detection Alarms and General Criteria
1. Either open phase conditions are detected and alarmed in the control room, or
- (a) The licensee has demonstrated that open phase conditions do not prevent the functioning of important-to-safety systems, structures, and components,
- (b) open phase condition detection will occur within a reasonably short period of time (e.g., 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />), and
- (c) the licensee has established appropriate documentation regarding open phase condition detection and correction.
2. Either detection circuits are sensitive enough to identify an open phase condition for
credited loading conditions (i.e., high and low loading), or if automatic detection may not be possible in very low or no loading conditions when offsite power transformers are in standby mode, automatic detection must happen as soon as loads are transferred to this standby source. Additionally, the licensee has established appropriate shiftily surveillance requirements to look for evidence of open phase conditions.
3. Open phase condition design/protective schemes minimize misoperation or spurious
action in the range of voltage unbalance normally expected in the transmission system that could cause separation from an operable off-site power source.
Licensees have demonstrated that the actuation circuit design does not result in lower overall plant operation reliability.
4. New non-Class-1E circuits are not used to replace existing Class-1E circuits.
5. The updated safety analysis report has been updated to discuss the design features
and analyses related to the effects of, and protection for, any open phase condition design vulnerability.
b. Protective Actions
1. If the licensee determines there is no single credible failure that could cause an open
phase condition, then verify that the licensee has developed and issued a full engineering evaluation to document the basis for open phase condition as a non-credited event. The Bruce Power and Forsmark operating experience must be considered as part of this analysis.
2. With open phase condition occurrence and no accident condition signal present,
either an open phase condition does not adversely affect the function of important-to-safety systems, structures, and components, or
- (a) technical specification limiting condition for operation are maintained or the technical specification actions are met without entry into Technical Specification Limiting Condition for Operation 3.0.3 (or equivalent),
- (b) important-to-safety equipment is not damaged by the open phase condition, and
- (c) shutdown safety is not compromised.
3. With open phase condition occurrence and an accident condition signal present,
automatic detection and actuation will transfer loads required to mitigate postulated accidents to an alternate source and ensure that safety functions are preserved as required by the current licensing bases, or the licensee has shown that all design basis accident acceptance criteria are met with the open phase condition, given other plant design features. Accident assumptions must include licensing provisions associated with single failures. Typically, licensing bases will not permit consideration of the open phase condition as the single failure since this failure is in a non-safety system.
4. Periodic tests, calibrations, setpoint verifications, or inspections (as applicable)
have been established for any new protective features. The surveillance requirements have been added to the plant Technical Specifications, if necessary to meet the provisions of 10 CFR 50.36.
Temporary Instruction 2515/194-03.02 - Information Gathering for Voluntary Industry Initiative Assessment (Part 2)
Section 03.02 of the Temporary Instruction required information gathering as part of the initial inspections to enable the Nuclear Reactor Regulation staff to determine whether the modifications implemented by the licensee of each unique open phase condition system design for the voluntary industry initiative adequately address potential open phase conditions. The information gathered for this section is tabulated in, Table 1 - Information Gathered for Temporary Instruction 2515/194, to this report.
INSPECTION RESULTS
Based on interviews and discussions with the licensee and the vendor, review of available design, testing, grid data trending results documentation, tour of the vendor facility, and walkdowns of installed equipment, the team had reasonable assurance the licensee appropriately implemented, with noted exceptions discussed below, the voluntary industry initiative.
Temporary Instruction 2515/194-03.01 - Voluntary Industry Initiative (Part 1)
a. Detection Alarms and General Criteria
- (1) The team determined by walkdowns and observation that open phase conditions will be detected and alarmed in the control room.
- (2) The team determined that detection circuits were sensitive enough to identify an open phase condition for all credited loading conditions.
- (3) No Class-1E circuits were replaced with non-Class 1E circuits in the design.
b. Protective Actions Criteria
- (1) The team determined the licensee identified they were susceptible to an open phase condition and were implementing design changes to mitigate the effects.
- (2) The team determined that with an open phase condition present and no accident condition signal, the PCS2000 system would not adversely affect the function of important-to-safety systems, structures, and components.
No findings were identified, however the team identified the following exceptions to the Temporary Instruction criteria resulting from the incomplete design modifications:
c. Detection Alarms and General Criteria Exceptions
- (1) The licensees design was operating in the monitoring mode to gather data to ensure the open phase condition design and protective schemes would minimize misoperation, or spurious action in the range of voltage unbalance normally expected in the transmission system. Because actual demonstration of this criterion requires the system to be in operation with final trip setpoints established, the team was not able to fully verify this criterion. After discussions with licensee and vendor staff, and design document and test results reviews, the team had reasonable assurance that the actuation circuit design would not result in lower overall plant operation reliability.
The team did not identify any issues of concern.
- (2) The Updated Safety Analysis Report had not been updated at the conclusion of the onsite inspection. The team held discussions with the licensee concerning their interpretation of the guidance in the voluntary industry initiative related to adding open phase condition related entries to their licensing basis documents. The licensee entered this issue into their corrective action program as Condition Report CR-RBS-2018-00891 to determine if the Updated Safety Analysis Report would be updated prior to initiating the full design (trip functions enabled) or during the next normal final safety analysis report (FSAR) update cycle. The team did not identify any issues of concern.
d. Protective Actions Criteria Exceptions
- (1) The licensees open phase condition design solution used the existing load transfer scheme for safety-related accident loads; only a new tripping condition (open phase)had been added to the electrical faults which result in safety-related loads being transferred to the onsite emergency power system. Because actual demonstration of this criterion requires the system to be in full operation, the team was not able to fully verify this criterion. Through review of available design documents and discussions with plant engineering and vendor staff, the team had reasonable assurance that with an open phase condition present and an accident condition signal, the PCS2000 system automatic detection and actuation would transfer loads required to mitigate postulated accidents to an alternate source and ensure that safety functions are preserved, as required by the current licensing bases. The team did not identify any issues of concern.
- (2) The licensee had not finalized documentation for periodic tests, calibrations, setpoint verifications, or inspection procedures for open phase condition-related components at the time of this inspection. The licensee had initiated action requests to establish these activities. The team reviewed the action requests (AR283793283793and AR283795283795documents outlining the proposed periodic testing and periodicities for the newly installed equipment, reviewed historical system logs related to system performance, reviewed and discussed planned testing, calibration, and inspections. The team also held discussions on the licensees plans to include open phase condition-related components into the Maintenance Rule (10 CFR 50.65) program. The licensee entered this issue into their corrective action program as Condition Report CR-RBS-2018-00893. Existing plant equipment will continue to be maintained according to the licensees current preventative maintenance program. The licensee planned to use guidance in the North American Electric Reliability Councils Reliability Standard PRC-005 and vendor maintenance guidance to maintain the added switchyard relaying equipment for the PCS2000 design. The team did not identify any issues of concern.
EXIT MEETINGS AND DEBRIEFS
On February 8, 2018, the team presented the Temporary Instruction 2515/194 inspection results to Mr. W. Maguire, Site Vice President and other members of the licensee staff. The inspectors verified no proprietary information was retained or documented in this report.
DOCUMENTS REVIEWED
Inspection
Procedure
Type
Designation
Description or Title
Revision/
Date
Calculations
G13.18.3.6-026
River Bend Open Phase with
Loss-of-Coolant Accident
Analysis
G13.18.3.6-025
River Bend Open Phase
Feasibility Analysis
G13.18.3.6*018 Electrical Transient Analysis
Program Database Input
Source Study
E-216
(ECN 55751)
Normal Battery BYS-BAT01 B
Duty Cycle, Current Profile
and Size Verification
E-222-NJS-
LDC1 QR
E-222-NJS-LDC1 QR, 480
VAC Normal Load Center and
Motor Control Center Load
Tabulation including Cable
Verification
Drawings
242.112-027-
20
Outline - Type SL
Transformer, 230kV/4160V
242.112-027-
25
RTX-XSR1C Power
Transformer Open Phase
Detection 3-Line AC
Schematic
242.112-027-
26
RTX-XSR1D Power
Transformer Open Phase
Detection 3-Line AC
Schematic
242.112-027-
034
RTX-XSR1C Power
Transformer OPD Sensor, and
CT Mounting Layout and
Details
242.112-027-
035
RTX-XSR1D Power
Transformer OPD Sensor, and
CT Mounting Elevation and
Details
Inspection
Procedure
Type
Designation
Description or Title
Revision/
Date
242.112-027-
040
RTX-XSR1D Power
Transformer OPD Sensor, and
CT Mounting Layout and
Details
242.112-027-
041
RTX-XSR1D Power
Transformer OPD Sensor, and
CT Mounting Elevation and
Details
EE-003ZQ
RTX-XSR1D Power
Transformer Open Phase
Detection 3-Line AC
Schematic Asset Numbers
EE-030A
Arrangement Transformer
Yard Unit 1
EE-030E
Sections and Details
Transformer Yard 2A
EE-040A
Conduit Plans and Details
Transformer Yard Area
EE-040B
Conduit Plans and Details
Transformer Yard Area
ESK-08SPR18
Elementary Diagram 125VDC
Control Circuit Preferred
Station Service XFMR
Protection
ESK-08SPR19
Elementary Diagram 125VDC
Control Circuit Preferred
Station Service XFMR
Protection
EE-001AC
Start-Up Electrical Distribution
Chart
ESK-08SPR04
Elementary Diagram 125VDC
Control Circuit Preferred
Station Service XFMR Backup
Protection
ESK-08SPR07
Elementary Diagram 125VDC
Control Circuit Preferred
Station Service XFMR Backup
Protection
Inspection
Procedure
Type
Designation
Description or Title
Revision/
Date
ESK-08SPR15
Elementary Diagram 125VDC
Control Circuit Preferred
Station Service XFMR Backup
Protection
ESK-08SPR17
Elementary Diagram 125VDC
Control Circuit Preferred
Station Service XFMR Backup
Protection
EE-003ZS
Wiring Diagram Open Phase
Detection Panel RTX-XSR1C
EE-003ZT
Wiring Diagram RTX-XSR1D
Open Phase Detection Panel
242.112-027-
048
Connection Diagram Power
Transformer System 1 and 2
Open Phase Detection
RTX-XSR1C
242.112-027-
049
Connection Diagram
RTX-XSR1D Power
Transformer System 1 & 2
Open Phase Detection
ESK-11SPF01
Elementary Diagram Station
Protection Reserve Station
Service Line
ESK-11SPF02
Elementary Diagram Station
Protection Reserve Station
Service Line
ESK-08SPR20
Elementary Diagram 125VDC
Control Circuit Dual Channel
Transfer Trip ACB 06, 07, 11
ESK-08SPR21
Elementary Diagram 125VDC
Control Circuit Dual Channel
Transfer Trip ACB 15, 26, 27
Engineering
Changes
Design Change to Detect
Primary Side of RTX-XSR1C
and RTX-XSR1D (BYRON
EVENT) IER-L2-12-14,
Condition Report
2015
Inspection
Procedure
Type
Designation
Description or Title
Revision/
Date
RTX-XSR1C, Design Change
to Detect Open Phase
Condition
RTX-XSR1D, Design Change
to Detect Open Phase
Condition
47360
Engineering
Reports
RBS-EE-17-
00002
RBS Open Phase Detection
Monitoring Period Report
March 2015 - January 2016
RBS-EE-17-
00003
RBS Open Phase Detection
Monitoring Period Report
January 2015 - July 2017
RBS-EE-18-
00001
RBS Open Phase Detection
Monitoring Period Report July
2017 - January 2018
Miscellaneous
RBG-47430
Letter from River Bend Station
Response to Request for
Additional Information
Regarding Response to
Bulletin 2012-01, "Design
Vulnerability In Electric Power
System"
January 31,
2014
RBG-47299
90-Day Response to
Bulletin 2012-01, Design
Vulnerability in Electric Power
System River Bend Station -
Unit 1
October 24,
2012
AR 283793283793Preventive Maintenance
Change Request:
RSS1 Open Phase Detection
System Protection Relays and
Current Transformers
RSS2 Open Phase Detection
System Protection Relays and
Current Transformers
October 16,
2017
Inspection
Procedure
Type
Designation
Description or Title
Revision/
Date
AR 283795283795Preventive Maintenance
Change Request:
RSS1 and RSS2 Open Phase
Detection System
October 16,
2017
Procedures
Degraded Grid
010
Log Report - Normal
Switchgear, Control, and
Diesel Generator Buildings
107
OSP-
28R107CN-E
Procedure Action Request
Change Notice for Log Report
- Normal Switchgear, Control,
and Diesel Generator
Buildings
Log Report - Outside Area
093
Log Report - Outside Area
064
ARP-680-09
P680-09 Alarm Response
033
SOP-0055
Main and Station
Transformers (SYS #311)
040
Vendor
Documents
P517-0109
PCS2000 Open Phase
Detection System User
Manual
Work Orders
00365542
Install PCS2000 Relay on
RTX-XSR1C for Open Phase
Detection
April 11, 2017
00365543
Install PCS2000 Relay on
RTX-XSR1D for Open Phase
Detection
September 15,
2015
Corrective Action Documents (CR-RBS-)
2015-08755
2017-08510
2018-00893
2017-01281
2018-00360
2012-01000
2017-00493
2018-00396
2017-05750
2017-00501
2018-00495
2018-00892
2017-01217
2018-00857
2017-02356
2018-00859
2017-02770
2018-00894
2017-03493
2018-00891
Table 1 - Information Gathered for Temporary Instruction 2515/194
A
Detection and Alarm
Scheme
Describe Observations/Comments
Are all credited offsite power
sources specified in
Updated Safety Analysis
Report Chapters 8.1, 8.2,
and 8.3 and plant Technical
Specifications considered in
the design of open phase
condition detection and
protection schemes?
Yes
No
Updated Safety Analysis Report Section 8.1
states that River Bend Station is provided
power from the 230 kV bays of the Fancy Point
substation via two physically and electrically
independent lines. Each 230 kV line is
terminated at a transformer yard. Transformer
yard 1 includes preferred station service
transformer RTX-XSR1C and yard 2A includes
RTX-XSR1D. The Updated Safety Analysis
Report section also states that standby 4160 V
buses ENS-SWG1A and ENS-SWG1B are
connected to preferred station service
transformers RTX-XSR1C and RTX-XSR1D,
respectively. The transformers in both
transformer yards support the normal operation
and safe shutdown operation of River Bend
Station Drawings 0242.112-027-025 and
242.112-027-026 show the inputs of the new
open phase detection system being connected
to the high side of preferred station service
transformers RTX-XSR1C and 1D.
References:
Updated Safety Analysis Report Section 8.1
and 8.2
Drawings: 0242.112-027-025 and
242.112-027-026
detection scheme(s)
installed to monitor the
qualified offsite power paths
to the engineered safety
feature buses during all
modes of operation?
Yes
No
The PCS2000 system overview and user
manual states that the system is capable of
detecting open phase conditions anywhere on
the direct line between the source breaker and
the power transformer while in standby mode
and drawing excitation current, lightly loaded or
fully loaded. This also includes the detection of
an open phase and grounded condition, a
double open phase and grounded condition,
and an open phase with line charging current
on the high side of a power transformer.
The system has two modes of monitoring the
power transformer for an open phase condition:
no load excitation current mode and transformer
load mode. Internal logic is used to measure
the power transformer high side current levels
and give alarming/tripping priority to either
mode based on the power transformer current
levels RTX-XSR1C and RTX-XSR1D provide
preferred source of power for the engineered
safety feature buses from Offsite sources. The
licensee stated that Engineering Calculation
G13.18.3.6*025 that performed the feasibility
analysis at River Bend Station considered
various open phase configurations for different
station loading scenarios. The audit team did
not review the feasibility studies.
What is the scope of open
phase conditions considered
by the licensee?
Did the licensee exclude
certain open phase
conditions (e.g., high voltage
or low voltage side of power
transformers), operating and
loading configurations in
their analyses? If so,
identify the technical
justifications for any
exclusion.
Yes
No
The scope of open phase condition scheme
considered the high voltage side of the
transformers only. Open phase conditions on
the low voltage side are not expected to occur.
The PCS system is capable of detecting open
phase conditions anywhere on the direct line
between the source breaker and the power
transformer while in standby mode and drawing
only excitation current, lightly loaded or fully
loaded. This includes the detection of an open
phase and grounded condition, a double open
phase and grounded condition, and an open
phase with line charging current on the high
side of a power transformer. Preventive
maintenances on switchgears include
inspecting the bus for damaged components,
loose parts, corrosion, etc. Thermography tests
are performed on various safety-related
components that include motor control centers,
switchgears, transformers, and distribution
panels. Safety-Related breakers are inspected
and refurbished, motors are inspected and
baker tested on a periodic basis through the
preventive maintenance process. Apart from
various maintenance activities that ensure
expected operation, system engineering and
operations perform frequent walkdowns to
identify any system anomalies. Based on this,
the requirement for a separate system that
monitors for open phase condition on the plant
side is not required.
Are the detection schemes
capable to identify open
phase conditions under all
operating electrical system
configurations and plant
loading conditions?
Yes
No
The licensee indicated that Engineering
Calculation G13.18.3.6*025 performed the
feasibility analysis at River Bend Station and
considered various open phase configurations
for different station loading scenarios. Report
No. RBS-EE-17-00002, Revision 1 for RTX-
XSR1D open phase detection system provides
monitoring data between March 2015 and
January 2016. The report was revised to add
more detail on plant specific events.
Specifically, the report updated data for events
which includes timestamps, sequence
components, and calculations to estimate
horsepower for each motor start event and load
change event. A review of the revised report
RBS-EE-17-00001, shows the systems
response to motor starts at various estimated
loads, different load changes and transformer
energization. A review of the report indicates
that the detection schemes are capable of
identifying open phase conditions under all
operating electrical system configurations and
plant loading conditions.
If the licensee determined
that open phase condition
detection and alarm scheme
was not needed, did the
licensee provide adequate
calculational bases or test
data?
Are all open phase
conditions detected and
alarmed in the main control
room with the existing
relays?
Yes
No
Yes
No
The licensee has determined that open phase
condition detection and alarm scheme is
needed at its facility.
The alarms from the open phase detection
system are tied into common alarms for
transformer trouble and annunciated in a panel
in the main control room. The alarms signify
Preferred Station Service Transformer Trouble.
Are the detection and alarm
circuits independent of
actuation (protection)
circuits?
If the detection, alarm, and
actuation circuits are
non-Class 1E, was there
any interface with Class 1E
systems?
Yes
No
Yes
No
Relay contacts in each relay in the system
provide trip/alarm signals which use circuits that
are independent of each other.
There are no interfaces with Class 1E systems.
Did the manufacturer
provide any information/data
for the capability of installed
relays to detect conditions,
such as unbalanced voltage
and current, negative
sequence current,
subharmonic current, or
other parameters used to
detect open phase condition
in the offsite power system?
What are the analyses and
criteria used by the licensee
Yes
No
The open phase detection system uses a
combination of parameters to determine an
open phase condition. These include specific
differences between phase currents relating to
magnitudes and phase angles, as well as
comparisons of current sequence components.
A variety of initial input data is used for each
transformer: winding configuration, expected
and actual nominal excitation current, mega volt
amp and voltage, inrush delay, and time delays
for trips. Monitoring data is used to update and
adjust input data and typical levels of
unbalance. A high-level description of the open
phase condition detection circuit requires the
to identify the power system
unbalance due to open
phase conditions; and
loading and operating
configurations considered
for all loading conditions
which involve plant trip
followed by bus transfer
condition?
If certain conditions cannot
be detected, did the licensee
document the technical
basis for its acceptability?
Did the licensee perform
functional testing to validate
limitations specified by the
manufacturer of the relays?
Yes
No
Yes
No
following conditions: 1. The current(s) drops in
the phase this is open, drops below a low
percentage setpoint of the nominal current. This
includes both fundamental and root mean
square components. 2. The current in the intact
phase(s) stays above a high percentage
setpoint of the nominal current. Certain
restraint setpoints also need to be met such as
the ratio of fundamental to root mean square
current, ratios of sequence components, and
holding these conditions for the required
amount of time.
River Bend Station performed calculations that
evaluated various loading conditions in
conjunction with the transmission system model
for various open phase condition configurations.
Failure modes and effects analysis was
performed and used as an input into
Engineering Change 47357 and testing
procedures for the engineering change to
ensure misoperation are minimized. Functional
testing including Factory Acceptance and Site
Acceptance testing were performed as part of
Engineering Change 47357 prior to
commissioning the system.
detection circuit design
features minimize spurious
detections due to voltage
perturbations observed
during events which are
normally expected in the
transmission system?
Identify whether the licensee
considered alarm/trip
settings coordination with
other electric power system
relays including
transmission system
protection features setup to
avoid false indications or
unnecessary alarms.
Yes
No
There are several restraints built into the
detection logic to prevent spurious detections
from normal transmission disturbances. These
restraints with initial setpoints were created
from PCS Lab testing, and were updated and
expanded based on testing and data collected
from installed systems: Entergy engaged an
external consulting company (Sargent & Lundy)
to develop test cases for the River Bend Station
open phase condition detection scheme. The
test cases considered different types of
disturbances on the transmission system;
monitoring data from the River Bend Station
systems and from other sites open phase
detection systems include multiple transmission
faults and disturbances used to validate and
tune restraint setpoints. Engineering
Calculation G13.18.3.6*025 developed and
documented the power system model for the
station auxiliaries, and the transmission network
near River Bend Station for system analyses
using industry-approved software named
electro magnetic transient program. The
calculation provided inputs for testing a relaying
scheme that is able to reliably detect an open
phase event at the high voltage side of the
preferred station service transformers being fed
from offsite power circuits without false
actuation due to various disturbances (e.g.
transformer energization, motor starting, station
faults, transmission system disturbances etc.).
Alarm Circuits: As documented in Engineering
Change 47357, several fuses were installed to
provide adequate protection between the
PCS2000 cabinets and the transformer control
panels. Coordination plots of the fuses with the
upstream protective devices are attached with
Engineering Change 47357. The final alarm
actuation setpoints will be developed after
substantial monitoring periods.
Trip Circuits: Protective coordination of the trip
circuits with offsite and onsite protection system
will be evaluated as part of the future
engineering change that will be performed to
enable trip functionality.
Reference Documents:
RBS-EE-17-00002, RBS-EE-17-00003,
G13.18.3.6*025, and Engineering Change 47357
Identify how the alarm
features provided in the
main control room including
setpoints are maintained,
calibrated, and controlled.
Alarms from the open phase detection system
sent to the main control room are managed in
several ways. The monitoring period and data
are used to adjust alarm setpoints, troubleshoot
issues that arise, and give operating experience
on alarms. The system has physical (test)
switches that can be used to block specific
alarms once they have been acknowledged,
such as a device problem or loss of power (this
allows the main control room alarm to be
cleared and prevents masking of other alarms).
The switches can also be used to prevent
spurious main control room alarms during
troubleshooting or when setpoints are updated
(in addition to procedures being developed).
The system cabinets are locked and the relays
are (non-default) password protected. Setpoint
control is also accomplished through
as-found/as-left relay settings comparison
procedures used in Entergy Transmission.
North American Electric Reliability Council
standards are utilized to perform preventive
maintenance and calibration of relays. The
relays and other digital components that are
part of the open phase detection system were
evaluated and are controlled by Entergy critical
digital asset procedures.
Does the open phase
condition detection scheme
consider subharmonics in
the supply power or offsite
power system?
Yes
No
The open phase detection system considers
both fundamental and root mean square
components of each phase current as well as
the ratio between fundamental and root mean
square. The open phase detection system also
considers instantaneous current magnitudes
along with short-and long-term smoothed
(averaged) magnitudes. The monitoring period
will be used to establish the threshold for
background and transient subharmonics, and
adjust trip or actuation setpoints above the
threshold.
detection and alarm circuit
components scoped into the
licensees maintenance rule
program?
Yes
No
The Engineering Change required to install the
trip functionality is a work in progress. The
maintenance rule program applicability/inclusion
will be evaluated in the ongoing engineering
change that enables the trip functionality. This
is consistent with the process and procedures
followed by Entergy. Condition Report
CR-RBS-2018-00893 was initiated to document
this question and ensure that the maintenance
rule applicability is evaluated through the
engineering change process.
The components added through the open
phase detection system are scoped into the
preventive maintenance program. These action
requests initiated preventive maintenances and
calibrations for the open phase components.
The actual preventive maintenance will be
processed through the regular work
management schedule. The licensee has
currently implemented a modification that
installed the open phase detection system in
the monitoring and alarm mode. The system
currently does not have the trip functionality
enabled.
B
Protection Scheme
Yes/No
Describe Observations/Comments
Record location of the
sensing of the protection
scheme (e.g., high voltage
or low voltage side of the
transformer, engineered
safety feature bus, etc.).
Location:
High voltage side of preferred power station
service transformers
Record the classification of
the protection scheme,
safety or non-safety.
Did the licensee consider
the interface requirements
for non-safety with safety-
related circuits?
Yes
No
Classification: Non-Safety
There are no direct interfaces with safety-
related systems
Record the type of the
protection scheme, digital or
non-digital.
Are cyber security
requirements specified for
digital detection scheme?
Yes
No
N/A
The protection scheme is digital. The open
phase detection system utilizes microprocessor
relays, computers, satellite synchronized
clocks, and annunciators. The components are
considered digital.
The cyber security evaluation was performed as
part of Engineering Change 47357. The
components installed by this engineering
change are considered Critical Digital Assets.
The components installed by the engineering
change have software equipped which were
evaluated by the engineering change and
classified as Level B software.
Did the licensee consider
any design features to
prevent protective functional
failures for open phase
condition protection system?
Yes
No
The engineering change evaluates the
installation of the open phase system that has
redundant circuits. To enhance reliability, the
two systems communicate by fiber optic
interface to exchange information. Separate
output contacts are provided in redundant
cabinets for the following functions: open
phase detection, ground overcurrent detection,
mode disagreements, and relay failure. The
open phase detection system installed on the
transformer follows a one out of two taken twice
logic. This ensures that a single failure of a
protective relay cannot affect the credited offsite
power source.
Identify the number of
channels provided per
offsite power source, and if
there is independence
between channels and
sensors.
Two independent sets of current
transformers/sensors are provided per offsite
power source. Each sensor provides input to its
own set of relays that sense current
imbalances. The relays are connected in such
a manner that the system requires a one out of
two taken twice logic.
What is the safety
classification of power
supply for the protection
scheme?
The power supply for the protection scheme is
non-safety related. This is consistent with the
safety classification of the preferred station
transformer and the open phase detection
systems.
Was a loss of power to the
protection scheme
considered?
Yes
No
The impacts of loss of power supply to the
protection scheme have been evaluated in the
failure modes and effects analysis performed as
part of Engineering Change 47357. The loss of
power supply is identified through a relay self-
test and a system alarm is provided that would
notify operations of a loss of power supply.
Moreover, the system relays and other
components are supplied by DC power that is
fed from a non-safety battery system. Upon
loss of charger, the battery is capable of
supplying loads for a 2 hour2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> period as credited
in the system design. AC power is supplied to
the panels space heaters. Loss of AC power
supply is considered in the failure modes and
effects analysis.
Identify if the licensee
considered the
consequences of a failure or
malfunction of a channel.
The PCS2000 system installed at River Bend
Station is built with coincidence logic to add
defense-in-depth and reduce spurious
actuations. The open phase detection system
follows a one out of two taken twice logic. The
system has redundant panels that contain two
Schweitzer Engineering Laboratories (SEL)
451 relays each, which take inputs from
independent current sensors. To enhance
reliability, the two panels will communicate by
fiber optic interfaces to exchange information.
The SEL relays that sense open phase
conditions are digital microprocessor relays that
have self-monitoring capabilities. A relay failure
is detected through a relay self-test. A relay
self-test failure is identified by a system alarm.
In a one out of two taken twice logic, the failure
of one relay does not have the potential to
spuriously trip offsite power source. The
second relay in the panel and the two relays on
the redundant panel are relied upon to detect
The digital relays fail in as is configuration and
will not actuate a trip signal. It is unlikely that
two out of four relays will fail in an actuated
mode. Therefore, failure of a single channel
current sensor or the entire channel of an open
phase detection system, the coincidence logic
at River Bend Station (one out of two taken
twice) prevents spurious misoperation/spurious
trip of offsite power source.
Did the design consider the
single failure criteria as
Yes
No
The open phase detection is a non-safety
related system and may potentially fail during
outlined in the general
design criteria (GDC) or the
principle design criteria
specified in the Updated
Safety Analysis Report?
postulated accidents or plant shutdown
resulting from an external event. In the event of
an open phase condition in power source
related with one safety division, coupled with a
single failure in the opposite (or redundant)
train, the safe shutdown capability may be
adversely impacted as both trains may not be
available to power the safety-related busses.
Since failures in non-safety systems are
considered to occur when evaluating
conformance to the single failure criterion
(safety systems), the open phase condition
scheme at River Bend Station does not conform
to the single failure criteria as outlined in the
GDC or the principle design criteria specified in
the River Bend Station Updated Safety Analysis
Report (i.e., for an open phase condition, a
non-Class 1E circuit should not preclude the
onsite electrical power system from being able
to perform its safety function given a single
failure of the onsite power system).
Did the licensee identify the
industry standards and
criteria to verify power
quality issues caused by
affect redundant engineered
safety feature buses?
What industry standards
were used to develop the
acceptance criteria for open
phase condition trip setpoint
or analytical limit?
Yes
No
Based on the various loads and generating
stations around River Bend Station, the power
flow from and to the Fancy Point switchyard
does not see much noise. Additionally,
Engineering Calculation G13.18.3.6*025
modelled the transmission system near River
Bend Station on EMTP and ran various loading
scenarios for multiple open phase condition.
The monitoring period at River Bend Station will
also enable the site to monitor the offsite source
for general disturbances and noise. The
setpoints will be adjusted accordingly.
The trip setpoints will be evaluated with the
associated industry standards in a future
engineering change that will enable the trip
functionality. The licensee is proposing a trip
setpoint of less than 5 seconds which will
ensure any heating effects from unbalanced
voltage conditions do not adversely impact plant
motors.
What are the analytical limits
or criteria used for setpoints
of the actuation/protection
scheme to provide adequate
protection for motors and
sensitive equipment?
The actual setpoints for the actuation circuits
will be evaluated as part of the future
engineering change that will enable the trip
functionality. The licensee is proposing a trip
setpoint of less than 5 seconds which will
ensure any heating effects from unbalanced
voltage conditions do not adversely impact plant
motors.
What are the design
features provided to
preclude spurious trips of
the offsite power source
(e.g. coincidence logic)?
The PCS2000 system installed at River Bend
Station is built with coincidence logic to add
defense-in-depth and reduce spurious
actuations. The open phase detection system
follows a one out of two taken twice logic. The
system has redundant panels that contain two
SEL 451 relays each which take inputs from
independent current sensors. To enhance
reliability, the two panels will communicate by
fiber optic interfaces to exchange information.
The SEL relays that sense open phase
conditions are digital microprocessor relays that
have self-monitoring capabilities. A relay failure
is detected through a relay self-test. A relay
self-test failure is identified by a system alarm.
In a one out of two taken twice logic, the failure
of one relay does not have the potential to
spuriously trip offsite power source. The
second relay in the panel and the two relays on
the redundant panel are relied upon to detect
What analyses have been
performed by the licensee
which demonstrates that the
not adversely affect the
function(s) of
important-to-safety
equipment required for safe
shutdown during anticipated
operational occurrences,
design basis events, and
accidents?
If an analyses was not
performed, what justification
was provided?
Are bus transfer schemes
and associated time delays
considered?
Yes
No
Engineering Calculation G13.18.3.6*026 was
developed to determine the minimum amount of
time an open phase event on the high side of
the preferred transformer, occurring
simultaneously with a loss-of-coolant accident,
could persist before damage to or tripping of,
medium voltage and low voltage auxiliary power
system motors would result.
Further analysis including time delays
associated with bus transfer schemes will be
evaluated by a future engineering change that
will be performed to enable the trip functions of
the open phase detection system.
protection/actuation circuit
components scoped, as
appropriate, into the
licensees maintenance rule
program?
Yes
No
The Engineering Change required to install the
trip functionality is a work in progress. The
maintenance rule program applicability/inclusion
will be evaluated in the ongoing engineering
change that enables the trip functionality. This
is consistent with the process and procedures
followed by Entergy. Condition Report
CR-RBS-2018-00893 was initiated to document
this question and ensure that the maintenance
rule applicability is evaluated through the
Engineering Change.
C
Updated Safety Analysis
Report Updates to Reflect
the Need to Protect Against
No
Describe Observations/Comments
Using items 1 to 6 below as
examples, identify whether
the licensee has updated
the Updated Safety Analysis
Report (and supporting
documents such as
calculations of record,
design change
modifications, etc.) to
ensure plant-specific
licensing basis/requirements
include discussions of the
design features and
analyses related to the
effects of, and protection for,
design vulnerability:
The open phase detection system is currently in
monitoring phase and a future engineering will
be performed to actuate the trip functionality.
All Updated Safety Analysis Report /Licensing
basis changes will be evaluated by the future
engineering change. Condition Report CR-RBS-
2018-00891 was created to track Updated
Safety Analysis Report Changes.
The plant-specific analysis
and documentation that
established the resolution of
design vulnerability,
including the failure mode
analysis performed.
N/A
Description of open phase
condition automatic
detection scheme, including
how offsite power system
detected from sensing to
alarm devices (loss of one
or two phases of the three
phases of the offsite power
circuit both with and without
a high-impedance ground
fault condition on the
high-voltage side of all
credited qualified offsite
power sources under all
loading and operating
configurations; and loss of
one or two phases of three
phases of switchyard
breakers that feed offsite
power circuits to
transformers without
ground).
Detection circuit design
features to minimize
spurious indications for an
operable offsite power
source in the range of
voltage perturbations, such
as switching surges,
transformer inrush currents,
load or generation
variations, and lightning
strikes, normally expected in
the transmission system.
Alarm features provided in
the main control room.
Discuss the engineered
safety feature bus alignment
during normal plant
operation and the operating
procedures in place to
address open phase
conditions. If the plant
auxiliaries are supplied from
the main generator and the
offsite power circuit to the
engineered safety feature
bus is configured as a
standby power source, then
should be alarmed in the
main control room for
operators to take corrective
action within a reasonable
time.
Describe the automatic
protection scheme provided
including applicable industry
standards used for
designing the scheme.
Design features to minimize
spurious actuations for an
operable offsite power
source in the range of
voltage perturbations, such
as switching surges,
transformer inrush currents,
load or generation
variations, and lightning
strikes, normally expected in
the transmission system
should be described.
Brief discussion of the
licensees analyses
performed for accident
condition concurrent open
phase conditions which
demonstrate that the
actuation scheme will
transfer engineered safety
feature loads required to
mitigate postulated
accidents to an alternate
source consistent with
accident analyses
assumptions to ensure that
safety functions are
preserved, as required by
the licensing bases.
D
Technical specification
surveillance requirements
and limiting condition for
operation for equipment
used for open phase
condition mitigation
Describe Observations/Comments
The open phase detection system is currently in
monitoring phase and a future engineering will
be performed to actuate the trip functionality.
All Updated Safety Analysis Report / licensing
basis changes will be evaluated by the future
engineering change. Condition Report CR-
RBS-2018-00891 was created to track Updated
Safety Analysis Report Changes. The final
design of the open phase detection scheme will
trip the offsite source emanating from the 230
kV switchyard (Fancy Point) upon detecting an
open phase condition independent of plant
operating mode (start up, normal operation, or
accident condition). The loss of one offsite
source will require entry into appropriate
technical specification related limiting condition
for operation. Technical specification related
surveillance requirements have not been
developed yet.
Are technical specifications
surveillance requirements
and limiting condition for
operation for equipment
used for the mitigation of
identified and implemented
consistent with the
operability requirements
specified in the plant
technical specifications?
If the licensee determined
that technical specifications
are unaffected because
being addressed by
licensee-controlled
programs, is the technical
justification adequate?
Yes
No
Yes
No
The open phase detection system is currently in
monitoring phase and a future engineering will
be performed to actuate the trip functionality.
All Updated Safety Analysis Report /Licensing
basis changes will be evaluated by the future
engineering change. Condition Report CR-
RBS-2018-00891 was created to track Updated
Safety Analysis Report Changes
N/A - see above
E
Provide a brief summary of
plant modification performed
under
CFR 50.59.
Engineering Change 47357 involved the installation of an
open phase detection system on the offsite power supply
to preferred station service transformers 1RTX-XSR1C
and 1RTX-XSR1D. This system will be capable of
detecting open phase conditions - including an open-
phase and grounded condition, a double open-phase and
grounded condition, and an open phase with line charging
- anywhere between the Fancy Point substation 230 kV
buses and these transformers. The system will also be
capable of detecting open phase conditions while the
transformers are fully loaded, lightly loaded, or drawing
only excitation current. Upon detection of an open phase
condition, a control room alarm will be actuated.
The initial phase of the activity included data collection
and performance monitoring of the new system. The
open phase detection system will be modified under a
separate activity to trip preferred station service
transformers 1RTX-XSR1C or 1RTX-XSR1D - which will
result in an automatic start of the safety-related
emergency diesel generator to supply the engineered
safety feature buses.
The scope of Engineering Change 47357 involves the
installation of an open phase detection system on the
offsite power supply to preferred station service
transformers 1RTX-XSR1C and
1RTX-XSR1D, and includes:
- New bushing sensors and new neutral current
transformers will be installed on the high side of the
transformers
New open phase detection cabinets and associated
structural components will be installed above the
transformer oil containment pits
New cables to connect the new open phase detection
equipment to existing plant equipment will be
installed; AC power will be supplied from new
480/120V transformers located near the new
open phase detection cabinets, and fed from
NHS-MCC-18A and NHS-MCC-20A, while DC power
will be supplied from battery 1BYS-PNL03B via
1CES-PNL1G and 2CESPNL1F
Upon detection of an open phase condition, the
existing transformer alarm circuit will be actuated
REFERENCE: River Bend Station Process Applicability
Determination Engineering Change 47357
TI 2515/194 Inspection Documentation Request
Please provide the following documentation (Items 1 - 6) to the lead inspector prior to the onsite
inspection date, preferably no later than January 22, 2018. Whenever practical, please provide
copies electronically (IMS/CERTREC is preferred). Please provide an index of the requested
documents which includes a brief description of the document and the numerical heading
associated with the request (i.e., where it can be found in the list of documents requested).
Sam Graves, Lead Inspector
RIV/DRS/EB2
1600 E. Lamar Blvd.
Arlington, TX 76011
817-200-1102
samuel.graves@nrc.gov
1. Copies of any calculations, analyses, and/or test reports performed to support the
implementation of your open phase condition (OPC) solution. If, in your implementation,
OPCs are not detected and alarmed in the control room please include documentation that:
a) demonstrates the OPC will not prevent functioning of important-to-safety SSCs; and b)
detection of an OPC will occur within a short period of time (e.g., 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />).
2. Copies of any modification packages, including 10 CFR 50.59 evaluations if performed,
used for or planned for the implementation of your OPC solution.
3. Copies of periodic maintenance, surveillance, setpoint calibration, and/or test procedures
implemented or planned, for your OPC solution.
4. Copies of your licensing basis changes to Updated Final Safety Analysis Report (UFSAR)
and/or Technical Specifications (TS), as applicable, which discuss the design features and
analyses related to the effects of, and protection for, any open phase condition design
vulnerability.
5. Copies of any procurement specifications and acceptance testing documents related to the
installation of your OPC solution.
6. Copies of any site training the team will need to accomplish to gain access to areas with, or
planned, major electrical equipment used in your OPC solution (i.e. switchyard).
Please provide the following documentation to the team when they arrive onsite. Whenever
practical, please provide copies electronically, except for drawings. Drawings should be
provided as paper copies of sufficient size (ANSI C or D) such that all details are legible.
7. A brief presentation describing your electric power system design and typical electrical
transmission and distribution system alignments; OPC design schemes installed to detect,
alarm and actuate; bus transfer schemes; and maintenance and surveillance requirements.
This presentation should be a general overview of your system. Please schedule the
overview shortly after the entrance meeting.
8. Plant layout and equipment drawings for areas that identify: (a) the physical plant locations
of major electrical equipment used in your open phase condition solution; (b) the locations of
detection and indication equipment used in the open phase condition sensing circuits.
9. If OPC actuation circuits are required, provide documentation that demonstrates continued
coordination with the other protective devices in both the offsite electrical system (within
River Bend Station area of responsibility) and the onsite electrical systems.
10. Access to locations in which open phase condition equipment is installed or planned (i.e.
switchyard, transformer yard, etc.)
11. Copies of documentation or testing that demonstrates your OPC solution minimizes spurious
actuation or misoperation in the range of voltage imbalance normally expected in the
transmission system that could cause undesired separation from an operable off-site power
source.
This document does not contain new or amended information collection requirements
subject to the Paperwork Reduction Act of 1995 (44 U.S.C. 3501 et seq.). Existing
information collection requirements were approved by the Office of Management and
Budget, Control Number 31500011. The NRC may not conduct or sponsor, and a person
is not required to respond to, a request for information or an information collection
requirement unless the requesting document displays a currently valid Office of
Management and Budget control number.
This document will be made available for public inspection and copying at
http://www.nrc.gov/reading-rm/adams.html and at the NRC Public document Room in
accordance with 10 CFR 2.390, Public Inspections, Exemptions, Requests for
Withholding.
SUNSI Review: ADAMS: Non-Publicly Available Non-Sensitive Keyword: NRC-002
By: STG Yes No
Publicly Available Sensitive
OFFICE
SRI: EB2
RI:EB2
C:EB2
C:PBC
C:EB2
NAME
SGraves
SMakor
GWerner
JKozal
GWerner
SIGNATURE
/RA/
/RA/
/RA/
/RA/
/RA/
DATE
2/27/2018
2/27/2018
03/13/2018
03/26/2018
03/26/2018