ML21043A198
| ML21043A198 | |
| Person / Time | |
|---|---|
| Site: | LaSalle  |
| Issue date: | 02/12/2021 |
| From: | Kenneth Riemer Division Reactor Projects III |
| To: | Rhoades D Exelon Generation Co, Exelon Nuclear |
| References | |
| IR 2020501, IR2020004 | |
| Download: ML21043A198 (22) | |
See also: IR 05000373/2020004
Text
February 12, 2021
Mr. David Rhoades
Senior VP, Exelon Generation Company, LLC
President and CNO, Exelon Nuclear
4300 Winfield Road
Warrenville, IL 60555
SUBJECT: LASALLE COUNTY STATION - INTEGRATED INSPECTION REPORT
05000373/2020004; 05000374/2020004; 05000373/2020501 AND
Dear Mr. Rhoades:
On December 31, 2020, the U.S. Nuclear Regulatory Commission (NRC) completed an
inspection at LaSalle County Station and discussed the results of this inspection with
Mr. J. Washko, Site Vice President, and other members of your staff. The results of this
inspection are documented in the enclosed report. The NRC also completed the Emergency
Preparedness Exercise Scenario Review Inspection. This inspection began on
September 28, 2020, and issuance of this letter closes Inspection Report Number 2020501.
One finding of very low safety significance (Green) is documented in this report. This finding
involved a violation of NRC requirements. We are treating this violation as a non-cited violation
(NCV) consistent with Section 2.3.2 of the Enforcement Policy.
If you contest the violation or the significance or severity of the violation documented in this
inspection report, you should provide a response within 30 days of the date of this inspection
report, with the basis for your denial, to the U.S. Nuclear Regulatory Commission,
ATTN: Document Control Desk, Washington, DC 20555-0001; with copies to the Regional
Administrator, Region III; the Director, Office of Enforcement; and the NRC Resident Inspector
at LaSalle County Station.
D. Rhoades 2
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 Title 10 of the Code of Federal Regulations 2.390, Public
Inspections, Exemptions, Requests for Withholding.
Sincerely,
/RA/
Kenneth R. Riemer, Chief
Branch 1
Division of Reactor Projects
Docket Nos. 05000373 and 05000374
License Nos. NPF-11 and NPF-18
Enclosure:
As stated
cc w/ encl: Distribution via LISTSERV
Non-Sensitive Publicly Available
SUNSI Review
Sensitive Non-Publicly Available
OFFICE RIII
KRiemer:wc via
NAME
DATE 2/12/2021
U.S. NUCLEAR REGULATORY COMMISSION
Inspection Report
Docket Numbers: 05000373 and 05000374
License Numbers: NPF-11 and NPF-18
Report Numbers: 05000373/2020004; 05000374/2020004; 05000373/2020501 AND
Enterprise Identifier: I-2020-004-0063
Licensee: Exelon Generation Company, LLC
Facility: LaSalle County Station
Location: Marseilles, IL
Inspection Dates: October 1, 2020 to December 31, 2020
Inspectors: J. Bozga, Senior Reactor Inspector
G. Edwards, Health Physicist
M. Garza, Emergency Preparedness Inspector
J. Havertape, Reliability and Risk Analyst
W. Schaup, Senior Resident Inspector
R. Zuffa, Illinois Emergency Management
Approved By: Kenneth R. Riemer, Chief
Branch 1
Division of Reactor Projects
Enclosure
SUMMARY
The U.S. Nuclear Regulatory Commission (NRC) continued monitoring the licensees
performance by conducting an integrated inspection at LaSalle County Station, in accordance
with the Reactor Oversight Process. The Reactor Oversight Process is the NRCs 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
Testing Does Not Assure the Capability to Connect to the Required Alternate Offsite Power
Supply
Cornerstone Significance Cross-Cutting Report
Aspect Section
Mitigating Green None 71153
Systems NCV 05000373,05000374/2020004-01
Open/Closed
The inspectors identified a Green finding of very low safety significance and an associated
non-cited violation of Title 10 Code of Federal Regulations, Part 50, Appendix B, Criteria XI,
"Test Control," for the licensee's failure to establish a test program to assure that all testing
required to demonstrate the crosstie breakers capability to connect to the required alternate
offsite power supply would perform satisfactorily in-service was performed in accordance with
written test procedures which incorporate the requirements and acceptance limits contained in
applicable design documents. Specifically, station surveillance procedure LOS-AP-R2 did not
test the operation of applicable portions of the protection system for the crosstie breakers to
assure that failures or substandard performance of the crosstie breakers remained
undetectable so that the required reliability of the crosstie breakers was maintained.
Additional Tracking Items
Type Issue Number Title Report Section Status
LER 05000374/2019-001-00 LER 2019-001-00 for 71153 Closed
LaSalle County Station, Unit
2, Safety-Related Electrical
Bus Under Voltage Results
in Valid Actuation of the
Common Emergency Diesel
Generator.
2
PLANT STATUS
Unit 1 began the inspection period at rated thermal power. On December 19, 2020, the unit
was down powered to 84 percent power to perform feedwater valve testing, channel distortion
testing, and to perform a rod sequence exchange. The unit was returned to rated thermal
power on December 20, 2020. The unit remained at or near rated thermal power for the
remainder of the inspection period.
Unit 2 began the inspection period at rated thermal power. On October 24, 2020, the unit was
down powered to 85 percent power to make repairs to the number 2 rectifier, perform scram
time testing, and make a rod pattern adjustment. The unit was returned to rated thermal power
on October 25, 2020. On November 14, 2020, the unit was down powered to 72 percent power
to make a rod pattern adjustment. The unit was returned to rated thermal power on
November 15, 2020. On December 12, 2020, the unit was down powered to 83 percent power
to make repairs to perform turbine and feedwater valve testing, perform channel distortion
testing, and make a final rod pattern adjustment for fuel end of cycle. The unit was returned to
rated thermal power on December 13, 2020. The unit remained at or near rated thermal power
for the remainder of the inspection period.
INSPECTION SCOPES
Inspections were conducted using the appropriate portions of the inspection procedures (IPs) in
effect at the beginning of the inspection unless otherwise noted. Currently approved IPs with
their attached revision histories are located on the public website at http://www.nrc.gov/reading-
rm/doc-collections/insp-manual/inspection-procedure/index.html. Samples were declared
complete when the IP requirements most appropriate to the inspection activity were met
consistent with Inspection Manual Chapter (IMC) 2515, Light-Water Reactor Inspection
Program - Operations Phase. The inspectors reviewed selected procedures and records,
observed activities, and interviewed personnel to assess licensee performance and compliance
with Commission rules and regulations, license conditions, site procedures, and standards.
Starting on March 20, 2020, in response to the National Emergency declared by the President
of the United States on the public health risks of the Coronavirus Disease 2019
(COVID-19), resident inspectors were directed to begin telework and to remotely access
licensee information using available technology. During this time, the resident inspectors
performed periodic site visits each week; conducted plant status activities as described in
IMC 2515, Appendix D, Plant Status; observed risk-significant activities; and completed onsite
portions of IPs. In addition, resident and regional baseline inspections were evaluated to
determine if all or portions of the objectives and requirements stated in the IP could be
performed remotely. If the inspections could be performed remotely, they were conducted per
the applicable IP. In some cases, portions of an IP were completed remotely and onsite. The
inspections documented below met the objectives and requirements for completion of the IP.
3
REACTOR SAFETY
71111.01 - Adverse Weather Protection
External Flooding Sample (IP Section 03.03) (1 Sample)
(1) The inspectors evaluated that flood protection barriers, mitigation plans, procedures,
and equipment are consistent with the licensees design requirements and risk
analysis assumptions for coping with external flooding.
In addition, the inspectors evaluated readiness to cope with external flooding for the
following areas:
Lake Screen House
Unit 1 Division 3 core standby cooling system pump room
Unit 2 Division 3 core standby cooling system pump room
71111.04 - Equipment Alignment
Partial Walkdown Sample (IP Section 03.01) (3 Samples)
The inspectors evaluated system configurations during partial walkdowns of the following
systems/trains:
(1) Unit 2 low pressure core spray on November 3, 2020
(2) Unit 2 Division 2 diesel generator on November 10, 2020
(3) Unit 1 Division 2 core standby cooling system on November 10, 2020
71111.05 - Fire Protection
Fire Area Walkdown and Inspection Sample (IP Section 03.01) (1 Sample)
The inspectors evaluated the implementation of the fire protection program by conducting a
walkdown and performing a review to verify program compliance, equipment functionality,
material condition, and operational readiness of the following fire areas:
(1) Fire Zone 3l4, Unit 2 reactor building, elevation 673', reactor core isolation cooling
and low pressure core spray pump corner room on November 3, 2020
Fire Brigade Drill Performance Sample (IP Section 03.02) (1 Sample)
(1) The inspectors evaluated the onsite fire brigade training and performance during a
live fire training session at Collins Station on October 6, 2020
71111.11A - Licensed Operator Requalification Program and Licensed Operator Performance
Requalification Examination Results (IP Section 03.03) (1 Sample)
(1) The inspectors reviewed and evaluated the licensed operator examination failure
rates for the requalification annual operating exam administered between the dates of
September 4, 2020 and October 6, 2020
4
71111.11Q - Licensed Operator Requalification Program and Licensed Operator Performance
Licensed Operator Performance in the Actual Plant/Main Control Room (IP Section 03.01)
(1 Sample)
(1) The inspectors observed and evaluated licensed operator performance in the control
room during a down power of Unit 2 to support minor repair activities and rod pattern
adjustments on November 14, 2020
Licensed Operator Requalification Training/Examinations (IP Section 03.02) (1 Sample)
(1) The inspectors observed and evaluated a licensed operator requalification training
exam (ESG 101, Revision 4) on December 3, 2020
71111.12 - Maintenance Effectiveness
Maintenance Effectiveness (IP Section 03.01) (4 Samples)
The inspectors evaluated the effectiveness of maintenance to ensure the following
structures, systems, and components (SSCs) remain capable of performing their intended
function:
(1) Review of the LaSalle County Station periodic assessment of the maintenance rule
program, July 2018 through June 2020
(2) Units 1 and 2 emergency diesel generator air start system maintenance effectiveness
(3) Jacket water leak identified on the Unit 2 Division 3 diesel generator on July 28, 2020
(4) Unit 2 low pressure core spray maintenance effectiveness
71111.13 - Maintenance Risk Assessments and Emergent Work Control
Risk Assessment and Management Sample (IP Section 03.01) (3 Samples)
The inspectors evaluated the accuracy and completeness of risk assessments for the
following planned and emergent work activities to ensure configuration changes and
appropriate work controls were addressed:
(1) Unit 2 online risk Yellow for functional testing of level 8 trip for reactor core isolation
cooling turbine and main turbine on October 1, 2020
(2) Both units online risk Yellow for unit common diesel generator relay calibrations on
October 8, 2020
(3) Unit 1 online risk Yellow with high pressure core spray (HPCS) pump inoperable as
part of a planned Division 3 diesel generator system outage on October 27, 2020
71111.15 - Operability Determinations and Functionality Assessments
Operability Determination or Functionality Assessment (IP Section 03.01) (8 Samples)
The inspectors evaluated the licensee's justifications and actions associated with the
following operability determinations and functionality assessments:
5
(1) Action Request 4372856, "Unit 1, 250 Vdc Battery, Cell Number Four Positive Post
Corrosion"
(2) Action Request 4373154, "Unit 2, 250 Vdc Bus, 221Y to 121Y Bus Crosstie Breaker
Broken Clip"
(3) Action Requests 4377417 and 4377514, "Unit 2, Division 2 Diesel Generator Air Start
System Failed Pressure Drop Test"
(4) Action Request 4377806, "Unit 1, Reactor Vessel Internals, Core Shroud Fuel Lift
Loads"
(5) Action Request 4379968, "Unit 1, Localized Corrosion Spots Identified On 1HP54A
Piping"
(6) Action Request 4381024, "Unit 1, Division 1 Annunciators, Unexpected Main Control
Room Alarm 1PM01J-A416"
(7) Action Request 4386372, "Unit 1, Division 3 Room Cooler, LOS-DG-SR7 Acceptance
Criteria Not Met"
(8) Action Request 4387815, "Unit 2, Division 1 Room Cooling Fan, 2A RHR [residual
heat removal] Pump Room Duct Temp Indicates Low"
71111.18 - Plant Modifications
Temporary Modifications and/or Permanent Modifications (IP Section 03.01 and/or 03.02)
(1 Sample)
The inspectors evaluated the following temporary or permanent modifications:
(1) Engineering Change Request 448254, "Addition of a Spring to the Diesel Generator
Air Start System Check Valves"
71111.22 - Surveillance Testing
The inspectors evaluated the following surveillance tests:
Surveillance Tests (other) (IP Section 03.01) (2 Samples)
(1) LOS-DG-R2A, "Unit 2 Division 2 Diesel Generator 24-Hour Endurance Run" on
November 17, 2020
(2) LOS-SC-SR1, "Secondary Containment Leak Rate Test" on November 11, 2020
In-Service Testing (IP Section 03.01) (1 Sample)
(1) LOS-RH-Q1, Attachment 1A, "Unit 1A Residual Heat Removal System Operability
and In-Service Test" on October 6, 2020
FLEX Testing (IP Section 03.02) (1 Sample)
(1) LOS-FSG-SA1, "Semi-Annual FLEX Generator Functional Run 0FF01KA" on
October 8, 2020
6
71114.04 - Emergency Action Level and Emergency Plan Changes
Inspection Review (IP Section 02.01-02.03) (1 Sample)
(1) The inspectors completed an evaluation of submitted emergency action level and
emergency plan changes on December 2, 2020. This evaluation does not constitute
NRC approval.
71114.06 - Drill Evaluation
Select Emergency Preparedness Drills and/or Training for Observation (IP Section 03.01)
(1 Sample)
(1) The inspectors observed the LaSalle pre-exercise drill on October 6, 2020
71114.08 - Exercise Evaluation Scenario Review
Inspection Review (IP Section 02.01- 02.04) (1 Sample)
(1) The inspectors reviewed and evaluated the proposed scenario for biennial
emergency plan exercise on October 14, 2020
(2) On November 23, 2020, Exelon submitted a letter to the NRC (ML20328A292)
requesting the postponement of the biennial emergency preparedness exercise from
November 17, 2020, to CY 2021 due to health and safety considerations associated
with the COVID-19 Public Health Emergency
OTHER ACTIVITIES - BASELINE
71151 - Performance Indicator Verification
The inspectors verified licensee performance indicators submittals listed below:
EP01: Drill/Exercise Performance (IP Section 02.12) (1 Sample)
(1) Unit 1 (10/01/2019 - 09/30/2020)
Unit 2 (10/01/2019 - 09/30/2020)
EP02: ERO Drill Participation (IP Section 02.13) (1 Sample)
(1) Unit 1 (10/01/2019 - 09/30/2020)
Unit 2 (10/01/2019 - 09/30/2020)
EP03: Alert & Notification System Reliability (IP Section 02.14) (1 Sample)
(1) Unit 1 (10/01/2019 - 09/30/2020)
Unit 2 (10/01/2019 - 09/30/2020)
MS05: Safety System Functional Failures (SSFFs) Sample (IP Section 02.04) (2 Samples)
(1) Unit 1 (10/01/2019 - 09/30/2020)
(2) Unit 2 (10/01/2019 - 09/30/2020)
7
MS09: Residual Heat Removal Systems (IP Section 02.08) (2 Samples)
(1) Unit 1 (10/01/2019 - 09/30/2020)
(2) Unit 2 (10/01/2019 - 09/30/2020)
MS10: Cooling Water Support Systems (IP Section 02.09) (2 Samples)
(1) Unit 1 (10/01/2019 - 09/30/2020)
(2) Unit 2 (10/01/2019 - 09/30/2020)
BI01: Reactor Coolant System (RCS) Specific Activity Sample (IP Section 02.10) (2 Samples)
(1) Unit 1 (08/01/2019 - 09/30/2020)
(2) Unit 2 (08/01/2019 - 09/30/2020)
OR01: Occupational Exposure Control Effectiveness Sample (IP Section 02.15) (1 Sample)
(1) 08/01/2019 - 09/30/2020
PR01: Radiological Effluent Technical Specifications/Offsite Dose Calculation Manual
Radiological Effluent Occurrences (RETS/ODCM) Radiological Effluent Occurrences Sample
(IP Section 02.16) (1 Sample)
(1) 08/01/2019 - 09/30/2020
71152 - Problem Identification and Resolution
Semi-Annual Trend Review (IP Section 02.02) (1 Sample)
(1) The inspectors reviewed the licensees corrective action program for potential
adverse trends and did not identify any trends that might be indicative of a more
significant safety issue
Annual Follow-up of Selected Issues (IP Section 02.03) (1 Sample)
The inspectors reviewed the licensees implementation of its corrective action program
related to the following issues:
(1) Automatic depressurization system safety relief valve 'S' spuriously actuated
71153 - Follow-up of Events and Notices of Enforcement Discretion
Event Report (IP Section 03.02) (1 Sample)
The inspectors evaluated the following licensee event reports (LERs):
(1) LER 2019-001-00, Safety-Related Electrical Bus Under Voltage Results in Valid
Actuation of the Common Emergency Diesel Generator (ADAMS Accession No.
ML19119A235). The inspection conclusions associated with this LER are
documented in this report under Inspection Results Section 4OA3.
8
INSPECTION RESULTS
Assessment 71152
The inspectors reviewed Action Request 4321045, "Automatic Depressurization System
Safety Relief Valve 'S' Spuriously Actuated," as a sample for annual selected issue(s) for
follow-up focusing on the following performance attributes of IP 71152:
- complete, accurate and timely documentation in the corrective action program
- consideration of the extent of condition and cause, generic implications, common
cause, and previous occurrences
- evaluation and timely disposition of operability and reportability issues
- classification and prioritization of the resolution of the problem commensurate with
safety significance
- identification of corrective actions, which were appropriately focused to correct the
problem
- completion of corrective actions in a timely manner commensurate with the safety
significance of the issue
- operating experience is adequately evaluated for applicability and applicable lesson
learned are communicated to appropriate organizations and implemented
The inspectors determined that the licensee had appropriately followed station procedures
and the station's corrective action program to ensure all elements inspected were adequately
addressed.
Assessment 71152
The inspectors reviewed action requests entered into the corrective action program for the
following:
- complete, accurate, and timely documentation of the issue identified in the corrective
action program
- evaluation and timely disposition of operability and reportability issues
- consideration of extent of condition and cause, generic implications, common cause,
and previous occurrences
- classification and prioritization of the problems resolution commensurate with the
safety significance
- identification of corrective actions that are appropriately focused to correct the
problem
- completion of corrective actions in a timely manner commensurate with the safety
significance of the issue
- identification of negative trends associated with human or equipment performance
that can potentially impact nuclear safety
- operating experience is adequately evaluated for applicability, and applicable lessons
learned are communicated to appropriate organizations and implemented
The inspectors completed the review and noted a trend in the area of assessing risk
associated with maintenance activities at the sight. Instances included the site online risk
modeling tool not updated to reflect the unavailability of a valve used for reactor containment
isolation cooling and pressure control function during maintenance on the condensate
storage tank for Unit 1, identification of a maintenance evolution that had the potential to
place a half scram trip into the reactor protection system on Unit 2, and maintenance using a
9
crane near power generation lines going offsite on Unit 1. Each individual event was
captured in the licensees corrective action program along with the trend identified by the
inspectors as Action Request 4371257. The first two items were briefed out to the licensee
as minor violations and reflected on the appropriated condition reports by the licensee. The
issue with the crane was document as a 10 CFR 50.65(a)(4) violation in the resident
inspector third quarter report in 2020. These items were identified in the earlier portion of the
assessment period and corrective actions to date appear successful at addressing the trend.
The resident staff will continue to monitor through risk evaluation inspection and the
corrective action program.
Testing Does Not Assure the Capability to Connect to the Required Alternate Offsite Power
Supply
Cornerstone Significance Cross-Cutting Report
Aspect Section
Mitigating Green None 71153
Systems NCV 05000373,05000374/2020004-01
Open/Closed
The inspectors identified a Green finding of very low safety significance and an associated
non-cited violation of Title 10 Code of Federal Regulations, Part 50, Appendix B, Criteria XI,
"Test Control," for the licensee's failure to establish a test program to assure that all testing
required to demonstrate the crosstie breakers capability to connect to the required alternate
offsite power supply would perform satisfactorily in-service was performed in accordance with
written test procedures which incorporate the requirements and acceptance limits contained
in applicable design documents. Specifically, station surveillance procedure LOS-AP-R2 did
not test the operation of applicable portions of the protection system for the crosstie breakers
to assure that failures or substandard performance of the crosstie breakers remained
undetectable so that the required reliability of the crosstie breakers was maintained.
Description:
On February 28, 2019, LaSalle Unit 2 was shut down in Mode 5 for a refueling outage
(L2R17). At 2117, during the performance of station surveillance procedure LOS-AP-R2,
Unit 2 Alternate Power Source Breaker Operability Surveillance, air circuit breaker
(ACB) 1414 and ACB 2414 that should have powered the safety-related bus from the
alternate offsite power source tripped, resulting in a valid under voltage condition on the
Unit 2, Division 1 safety-related bus and actuation of the Division 1 [unit common] diesel
generator. The inability to supply power from the alternate offsite circuit for Unit 1 required
operators to enter a 72-hour shutdown time clock in accordance with LaSalle Station TS 3.8.1
due to the loss of one required offsite power source. The Division 1 diesel generator
responded as expected, Unit 1 remained stable at full power, all Technical Specification (TS)
actions were performed and, all affected systems were restored. The licensee reported the
event within eight hours to the NRC on March 1, 2019, which was documented as Event
Notification 53903, and the licensee documented the event in the corrective action program
as Action Request 4225076. This action request stated under recommend actions
"Investigate why [ACB] 1414 locked out and tripped especially with only 40-50 amps on the
buses 241Y/X."
The purpose of station surveillance procedure LOS-AP-R2 was to demonstrate the manual
transfer of the unit power supply from the normal offsite circuit to the alternate offsite circuit
which is supplied through the other unit satisfying TS surveillance requirement 3.8.1.8. The
surveillance is performed once every two years during a refueling outage. Air Circuit Breaker
10
1414 is the Unit 1, Division 1 safety-related bus crosstie breaker, and ACB 2414 is the Unit 2,
Division 1 safety-related bus crosstie breaker. During power generation operations, these
circuit breakers are normally open. The breakers are only closed for testing or during actual
accident conditions during which time both circuit breakers are closed manually. This allows
Unit 2 to receive offsite power from Unit 1 in the event of a failure of the Unit 2, Division 1
diesel generator or Unit 1 to receive offsite power from Unit 2 in the event of a failure of the
Unit 1, Division 1 diesel generator.
During this performance of the surveillance test procedure, operations personnel performed
Attachment B of the procedure instead of Attachment A of the procedure that had been
performed in previous outages because the Unit 2 unit auxiliary transformer (UAT) was not
back feeding the unit, a requirement to use Attachment A. Operations personnel were able to
close ACBs 1414 and 2414 in accordance with the surveillance instructions; however, when
Step 1.G.5, Open Bus 241Y Normal Feed Breaker 2412 was performed, ACBs 1414 and
2414 tripped opened concurrently.
Following the surveillance test, it was discovered that the differential current protective relay
for ACB 1414, 1487-AP020A, had a flag actuate on the A-phase. The licensee replaced
1487-AP020A with a previously calibrated relay and began diagnostic testing using
Attachment C of the surveillance procedure, with one recorder installed on each of the six (6)
phases that fed 1487-AP020A. The diagnostic testing under attachment C was completed
without ACB 1414 and ACB 2414 tripping; however, the recorders identified that the A-phase
of ACB 2414 was not passing current. Troubleshooting continued. The 1487-AP020A relay
was removed and it was identified that there was a broken lug on the terminal that fed
1487-AP020A from the Unit 2, Division 1 safety-related bus. As corrective actions, the
licensee replaced the broken lug and tested the circuit using the surveillance procedure
Attachment B, with the recorders installed and a jumper installed that would maintain ACB
2415. Additional post-maintenance testing was performed to verify the crosstie breakers
would function properly. On March 2, 2019 at 12:35, the licensee exited TS 3.8.1 on Unit 1
after declaring the offsite power source operable based on the testing performed on the
crosstie breakers. Later that day station surveillance procedure LOS-AP-R2, Attachment C
was successfully performed with no jumpers installed.
Additionally, the licensee submitted LER 2019-001-00, "Safety-Related Electrical Bus Under
Voltage Results in Valid Actuation of the Common Emergency Diesel Generator," on
April 29, 2019, to satisfy reporting requirements to the NRC.
Shortly after the event had occurred, a discussion between the resident inspectors and the
shift operations superintendent, about anything that was different about this performance of
the surveillance compared to previous performances, discovered that the attachment used
during this performance [attachment B] was not normally the one performed and that the
current load on the safety buses was higher than the current load that would be seen if they
normally performed attachment. Attachment A was the one normally performed and during
the performance of that attachment current loads were minimal on the safety bus.
Additionally, the inspectors noted a limitation in the procedure that states "That the load on
the bus to be crossed-tied to Unit One's 4.16 kV [safety bus] must be minimized such that the
breaker rating of 1200A on the unit tie breakers ACB 1414, ACB 2414, ACB 1424 and ACB
2424 must not be exceeded." When asked, the shift operations superintendent stated that to
meet the intent of the limitation and to minimize impact to the plant if something happened
during the surveillance, operations minimized bus loading to the maximum extent practical.
11
With the help of regional electrical engineering subject matter expert, the inspectors obtained
the relevant work orders, corrective action documents, causal products, and LER to review
and determined the following.
The unit tie phase A/B/C differential current relays (1487-AP020A/B/C) are configured such
that they will not pick up if the differential current sensed by the relay is less than 0.5 amps
(A). The signal provided to 1487-AP020A is the A-phase bus current transformers (CTs) at
ACB 1414 and ACB 2414. These CTs each have a ratio of 1200:5 A. As such, the minimum
differential bus current that will pick up 1487-AP020A is 120 A. Relays 1487-AP020A/B/C will
never pick up if the bus current is less than 120 A.
With the lug broken at the ACB 1414 CT, the differential current seen by 1487-AP020A would
be the same as the actual bus current.
During the L2R17 testing under LOS-AP-R2, the following was observed when the strip chart
recorder was connected:
- When Attachment C was performed on March 2, 2019, at 02:08, 0.25 A of secondary
CT current was observed (60 A bus current). As this is less than the 0.5 A (120 A bus
current) required to pick up 1487-AP020A, the relay could not have picked up (even
with a broken CT lug)
- When Attachment B was performed on March 2, 2019, at 12:25, 1.75 A secondary
CT current was observed (420 A bus current). This is greater than current required to
pick up 1487-AP020A (if the CT lug had not previously been repaired).
There is no record of bus current during previous performances of LOS-AP-R2 (i.e. earlier in
L2R17 or during previous RFOs); however, the above data indicates that performance of
Attachment C (or Attachment A) will not guarantee adequate current to pick up
1487-AP020A/B/C in the presence of a faulty sensing circuit (e.g. a broken CT lug).
The inspectors reviewed previous performances of the surveillance procedure.
LOS-AP-R1, Unit 1 Alternate Power Source Breaker Operability Surveillance, is performed
every Unit 1 refueling outage (PMID 81429-01).
Recent history as follows:
WO Date Att Performed
4762067 Feb 2020 Att A
1906733 Mar 2018 Att A
1716099 Mar 2016 Att A
1520229 Feb 2014 Att A
LOS-AP-R2, Unit 2 Alternate Power Source Breaker Operability Surveillance, is performed
every Unit 2 refueling outage (PMID 81430-01).
Recent history as follows:
WO Date Att Performed
4608404 Mar 2019 Att C
1812255 Mar 2017 Att A
12
1620125 Feb 2015 Att A
1415318 Feb 2013 Att A
The inspectors determined that the last physical inspection of the wire lug occurred during
PMID 00060290-01 the 1AP04E-12 cubicle inspection using station procedure LES-GM-103,
"Inspection of 4.16 kV and 6.9 kV ITE Circuit Breakers," in accordance with step 4.24.10 that
states: CHECK terminal boards for loose connections and TIGHTEN as necessary (including
top cubicle above breaker compartment).
The broken CT lug was located in the top cubicle above breaker compartment 1AP04E-12 it
would be expected that a broken lug would have been identified during this inspection.
PMID 00060290-01 was last performed on October 28, 2014, under Work Order 1188553-01.
The licensees quality assurance topical report, Revision 96, Section 11.2.6 "Surveillance
Test," states, "The companys test program covers surveillance testing during the operational
phase to provide assurances that failures or substandard performance do not remain
undetected and that the reliability of safety-related systems in maintained."
The LaSalle Final Safety Analysis Report, Section 8.3.1.2 "Analysis," states in part,
"Provisions have been made in the design of offsite and onsite power systems for the
inspection and testing of appropriate parts of the systems. Periodic tests can be made of
major portions of the power systems under conditions simulating the design conditions."
The inspectors noted that the surveillance procedure does not provide any instructions to
ensure that a minimum load should be on the bus to ensure the CTs are functioning properly
and that the licensee does not perform any other maintenance or testing that would
demonstrate the CTs would will perform satisfactorily in-service.
The inspectors final determination was that station surveillance procedure LOS-AP-R2 could
be performed with satisfactory results without demonstrating that the CTs would perform
satisfactorily in-service and that this was the only maintenance or testing the licensee
performs that would demonstrate the CTs perform satisfactorily in-service.
Corrective Actions: The licensee repaired the broken lug on the 'A' phase of the current
transformer and satisfactorily demonstrated that the CTs would perform in-service though
surveillance and additional testing measures. The licensee has made changes to the station
surveillance procedures to ensure the CTs are verified to perform satisfactorily in-service.
Corrective Action References: Action Requests 4225076, 4225628 and 4362548
Performance Assessment:
Performance Deficiency: The inspectors determined that the licensee's testing program (to
demonstrate the manual transfer of the unit power supply from the normal offsite circuit the
alternate offsite circuit) for the crosstie breakers did not assure that failures or substandard
performance of the crosstie breakers remained undetectable so that the required reliability of
the crosstie breakers was maintained, and was therefore a performance deficiency.
Screening: The inspectors determined the performance deficiency was more than minor
because it was associated with the Procedure Quality attribute of the Mitigating Systems
cornerstone and adversely affected the cornerstone objective to ensure the availability,
reliability, and capability of systems that respond to initiating events to prevent undesirable
consequences.
13
Significance: The inspectors assessed the significance of the finding using Appendix A, The
Significance Determination Process (SDP) for Findings At-Power. The inspectors reviewed
the performance deficiency in accordance with the screening criteria contained in IMC 0609,
Appendix A for inspection findings at-power. The inspectors determined that a detailed risk
evaluation was required because they answered "Yes" to the relevant portion of Question 3,
"Does the finding represent an actual loss of function of at least a single train for greater than
its TS-allowed outage time?" The TS-allowed outage time for one required offsite power
source is 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />. The licensee stated in Action Request 4225076 that a broken lug was the
cause of ACB-1414 failing to close as required on February 28, 2019. Therefore, the
inspectors concluded that the affected offsite power source would have likely failed to perform
its function and that this condition likely existed since the licensee had last opened the
ACB-1414 cabinet door on October 6, 2016. As a result, a detailed risk evaluation was
required.
A regional senior reactor analyst performed a conditional analysis of the ACP-1414 breaker
being non-functional for a one-year exposure time. The internal events results were a
delta-CDF = 3E-8/year and the external events results were qualitatively and quantitatively
determined to be less than a delta-CDF of 1E-6/year for a total of < 1E-6/year. The following
factors were considered and included in the quantification:
- mitigating strategies equipment (a.k.a., FLEX)
- licensee plant-specific action basic event values were used
- common cause failure probabilities were propagated in the model
- external events contributions were assessed using the licensees fire probabilistic
risk assessment base model and some FLEX credit was applied
- hardened containment venting was applied
Based on information from the inspectors, no recovery probabilities were applied for the failed
crosstie breaker. For a thorough explanation of how the risk analysis was performed,
including a description of epistemic uncertainties, please see the attached detailed risk
evaluation.
Cross-Cutting Aspect: None
Enforcement:
Violation: Title 10 CFR 50, Appendix B, Criterion XI, Test Control, states, A test program
shall be established to assure that all testing required to demonstrate that SSCs will perform
satisfactorily in-service is performed in accordance with written test procedures which
incorporate the requirements and acceptance limits contained in applicable design
documents. The test program shall include, as appropriate, operational tests during nuclear
power plant operation.
The LaSalle Final Safety Analysis Report, Section 8.3.1.2 "Analysis," states in part,
"Provisions have been made in the design of offsite and onsite power systems for the
inspection and testing of appropriate parts of the systems. Periodic tests can be made of
major portions of the power systems under conditions simulating the design conditions."
Contrary to the above, since 1981, the licensee failed to establish a test program to assure
that all testing required to demonstrate the crosstie breakers capability to connect to the
required alternate offsite power supply would perform satisfactorily in-service was performed
14
in accordance with written test procedures which incorporate the requirements and
acceptance limits contained in applicable design documents. Specifically, the licensee failed
to assure the performance of all testing required to demonstrate: (1) the operability and
functional performance of the crosstie breakers; and (2) the operability of the alternate source
of offsite power as a whole and, under conditions as close to design as practical, the full
operation sequence that brings the alternate offsite power source into operation, including
operation of applicable portions of the protection system, and the transfer of power among
the nuclear power unit.
Enforcement Action: This violation is being treated as a non-cited violation, consistent with
Section 2.3.2 of the Enforcement Policy.
EXIT MEETINGS AND DEBRIEFS
The inspectors verified no proprietary information was retained or documented in this report.
- On December 31, 2020, the inspectors presented the integrated inspection results to
Mr. J. Washko, Site Vice President, and other members of the licensee staff.
- On October 8, 2020, the inspectors presented the annual licensed operator
requalification examination inspection results to Mr. K. Heuser, Regulatory Exam Author
Licensed Operator Requalification Training, and other members of the licensee staff.
- On November 9, 2020, the inspectors presented the 71151 performance indicator
verification inspection results to Mr. J. Moser, Radiation Protection Manager, and other
members of the licensee staff.
- On December 2, 2020, the inspectors presented the IP 71114.04 exit meeting inspection
results to Mr. D. Moore, Senior Manager - Emergency Preparedness, and other
members of the licensee staff.
15
DOCUMENTS REVIEWED
Inspection Type Designation Description or Title Revision or
Procedure Date
71111.01 Corrective Action AR 4381678 2020 Lake Dike Inspection Results 11/02/2020
Documents
Procedures LTS-1000-32 LaSalle Cooling Pond Dike Inspection 10
LTS-1000-4 Core Standby Cooling System Pond Surveillance 16
Work Orders WO 4849167 Core Standby Cooling System Pond Sediment Deposition 07/09/2020
Check
71111.11A Procedures TQ-AA-150-F25 LaSalle 2020 LORT Annual Exam Status Report 10/02/2020
71111.12 Corrective Action AR 4368082 LPCS Discharge Pressure Low Alarm Would Not Clear 09/08/2020
Documents Following Pump Run
Engineering LaSalle Station, Periodic Assessment of the Maintenance Rule Program 10/05/2020
Evaluations Units 1 and 2,
July 2018 through
June 2020
Miscellaneous AR 4359288 (A)(1) Determination for Jacket Water Leak Identified on the 10/29/2020
2B Diesel Generator
AR 4359288 Maintenance Rule Functional Failure Determination for 10/29/2020
Jacket Water Leak Identified on the 2B Diesel Generator
LAS-1-DG Diesel Generator Maintenance Rule Function Scope Basis 11/02/2020
Document
LAS-2-LP Low Pressure Core Spray Maintenance Rule Basis 11/02/2020
Document
Low Pressure Health Group Issue Action Plan 10/03/2020
Injection
LS-MRULE-010 PRA Application Notebook, LaSalle Station Maintenance 0
Rule (a)(3) Assessment Input
71111.15 Corrective Action AR 4372243 U1 250 Vdc Ground Alarm 09/26/2020
Documents AR 4372856 1DC01E Cell #4 Positive Post Identified with Corrosion 09/26/2020
AR 4373164 Revise Operations DC Battery Procedures 09/30/2020
AR 4377417 2DG-17MB Flange Leaking During PMT 10/18/2020
AR 4377514 2A DG 'B' Air Compressor Check Valve Test Failed 10/18/2020
LOS-DG-Q2
AR 4377806 LaSalle Unit 1 Core Shroud Fuel Lift Loads 10/19/2020
16
Inspection Type Designation Description or Title Revision or
Procedure Date
AR 4379968 Localized Corrosion Spots Identified on 1HP54A Piping 10/27/2020
AR 4381024 Unexpected MCR Alarm 1PM01J-A416 10/30/2020
AR 4387815 2A RHR Pump Room Duct Temp Indicates Low 12/03/2020
Corrective Action AR 4372880 NRC Identified - 250 Vdc Battery Inter-Cell Resistance 09/29/2020
Documents Readings Not Taken
Resulting from
Inspection
Drawings 1E-1-4011KG Schematic and Wiring Diagram Annunciator and Sequential F
Events Recorder Logic System 1PA03J System Part 55
1E-1-4011KH Schematic and Wiring Diagram Annunciator and Sequential F
Events Recorder Logic System 1PA03J System Part 56
1E-2-4089AA Schematic Diagram Core Standby Cooling System VY, E
Part 1
1E-2-4089AE Schematic Diagram Core Standby Cooling System VY, B
Part 5
Engineering EC 388089 Evaluation of Unit 1 Core Shroud Inspection Results from 0
Changes L1R14
EC 633091 1VY02A DP Acceptance Criteria 0
Engineering EC 632877 1HP54A Structural Integrity Evaluation Using Code Case 0
Evaluations N-513
Work Orders WO 5046987 LOS-DG-SR7, Attachment D, 1VY02A DP Test 11/24/2020
71111.18 Engineering ECR 448254 Design Engineering Evaluation of Installing the Spring In 10/20/2020
Changes 2DG049B
Engineering CHRON 115629 Engineering Work Request E92-074 Removal of Springs 05/11/1992
Evaluations from Check Valves 0DG023A/B and 1/2DG049A/B
71111.22 Procedures LOS-CS-SR1 Secondary Containment Leak Rate Test 8
LOS-LP-Q1, Unit 1 Low Pressure Core Spray Operability and In-Service 59
Attachment 1A Test
LOS-RH-Q1, Unit 1 A Residual Heat Removal System Operability and 95
Attachment 1A In-Service Test
Work Orders WO 1886736 Operations LOS-CS-SR1, Secondary Containment Leak 11/11/2020
Rate
WO 4796552 In-Service Test - Comprehensive Pump Test for 1E21-C001 12/03/2020
WO 5029860 Semi-Annual FLEX Generator Functional Run 0FF01KC 10/08/2020
17
Inspection Type Designation Description or Title Revision or
Procedure Date
WO 5029861 Semi-Annual FLEX Generator Functional Run 0FF01KB 10/08/2020
WO 5029862 Semi-Annual FLEX Generator Functional Run 0FF01KA 10/08/2020
WO 5060585 Operations LOS-RH-Q1, 1A RHR Attachment 1A 10/05/2020
71114.04 Corrective Action AR 4325295 Perform an Impact Review of EAL Revisions from 03/10/2020
Documents EOP/SAMG Revision 4
AR 4328154 EP FAQ EAL Change License Amendment Implementation 03/20/2020
Actions
AR 4329864 NOS ID: Revise Standardized Emergency Plan 03/26/2020
AR 4334253 Emergency Plan: CDAM 50.54(q) Potential Deficiencies 04/09/2020
Miscellaneous Eval No. 20-35 EALs LaSalle Station 05/28/2020
Eval No. 19-29 Exelon Nuclear Standardized Radiological Emergency Plan 09/04/2019
Eval No. 19-65 Exelon Nuclear Standardized Radiological Emergency Plan 09/06/2019
Eval No. 19-79 Various Station Emergency Preparedness Annexes 11/08/2019
71151 Miscellaneous Alert and Notification System Reliability Performance 10/01/2019 -
Indicator Records 09/30/2020
Emergency Response Organization Drill Participation 10/01/2019 -
Performance Indicator Records 09/30/2020
Drill and Exercise Performance - Performance Indicator 10/01/2019 -
Records 09/30/2020
LS-AA-2090 Monthly Data Elements for NRC Reactor Coolant System August 2019
Specific Activity - September
2020
LS-AA-2140 Monthly Data Elements for NRC Occupational Exposure August 2019
Control Effectiveness - September
2020
LS-AA-2150 Monthly Data Elements for RETS/ODCM Occurrences August 2019
- September
2020
71152 Corrective Action AR 4321045 Automatic Depressurization System Safety Relief Valve 02/24/2020
Documents Spuriously Actuated
Miscellaneous LAS-31541 Failure Analysis of a Switch, Pressure, Range 200-1350 psi 1
for LaSalle
71153 Corrective Action AR 4225870 4,0 Critique for LOS-AP-R2 03/03/2019
Documents AR 4362548 PCRA Requested for LOS-AP-R1 and LOS-AP-R2 08/12/2020
18
Inspection Type Designation Description or Title Revision or
Procedure Date
ECAP 4225076- Breaker Tip Due to Terminal Lug Degradation 04/11/2019
03
Procedures LOS-AP-R2 Unit 2 Alternate Power Source Breaker Operability 6
Surveillance
Work Orders WO 4893155 ACB 1414 Had a Lockout Trip While Performing LOS-AP-R2 03/01/2019
19