IR 05000317/2021011
| ML21210A124 | |
| Person / Time | |
|---|---|
| Site: | Calvert Cliffs  |
| Issue date: | 07/29/2021 |
| From: | Glenn Dentel Division of Operating Reactors |
| To: | Rhoades D Exelon Generation Co LLC, Exelon Nuclear |
| Dentel G | |
| References | |
| IR 2021011 | |
| Download: ML21210A124 (8) | |
Text
July 29, 2021
SUBJECT:
CALVERT CLIFFS NUCLEAR POWER PLANT, UNITS 1 AND 2 -
TEMPORARY INSTRUCTION 2515/194 INSPECTION REPORT 05000317/2021011 AND 05000318/2021011
Dear Mr. Rhoades:
On July 14, 2021, the U.S. Nuclear Regulatory Commission (NRC) completed an inspection at Calvert Cliffs Nuclear Power Plant, Units 1 and 2 and discussed the results of this inspection with Mr. Thomas Haaf, Site Vice President and other members of your staff. The results of this inspection are documented in the enclosed report.
No findings or violations of more than minor significance were identified during this inspection.
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, Glenn T. Dentel, Chief Engineering Branch 2 Division of Operating Reactor Safety
Docket Nos. 05000317 and 05000318 License Nos. DPR-53 and DPR-69
Enclosure:
As stated
Inspection Report
Docket Numbers:
05000317 and 05000318
License Numbers:
Report Numbers:
05000317/2021011 and 05000318/2021011
Enterprise Identifier: I-2021-011-0016
Licensee:
Exelon Generation Company, LLC
Facility:
Calvert Cliffs Nuclear Power Plant, Units 1 and 2
Location:
Lusby, MD
Inspection Dates:
July 12, 2021 to July 14, 2021
Inspectors:
A. Patel, Senior Reactor Inspector
F. Arner, Senior Reactor Analyst
Approved By:
Glenn T. Dentel, Chief
Engineering Branch 2
Division of Operating Reactor Safety
SUMMARY
The U.S. Nuclear Regulatory Commission (NRC) continued monitoring the licensees performance by conducting a Temporary Instruction 2515/194 Inspection at Calvert Cliffs Nuclear Power Plant, Units 1 and 2, 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
No findings or violations of more than minor significance were identified.
Additional Tracking Items
None.
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 (COVID-19), inspectors were directed to begin telework. In addition, regional baseline inspections were evaluated to determine if all or a portion 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 on site.
However, all the inspection activities were performed onsite. The inspections documented below met the objectives and requirements for completion of the IP.
OTHER ACTIVITIES
- TEMPORARY INSTRUCTIONS, INFREQUENT AND ABNORMAL
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 inspectors reviewed the licensees implementation of the Nuclear Energy Institute Voluntary Industry Initiative, (ADAMS Accession No. ML15075A454) dated March 16, 2015. This included reviewing how the licensee updated their licensing basis to reflect the need to protect against open phase conditions.
Inspection of the Licensees Implementation of Industry Initiative Associated With the Open Phase Condition Design Vulnerabilities In Electric Power Systems (NRC Bulletin 2012-01) (1 Sample)
- (1) Exelon selected the open phase detection system designed and manufactured by Schweitzer Engineering Laboratories (SEL), as the design vendor for the open phase condition system at Calvert Cliffs Nuclear Power Plant, Units 1 and 2.
Calvert Cliffs Nuclear Power Plant has three independent offsite sources (500kV)which provide power via the 13kV station service buses to the appropriate 4 kV safeguard buses. The open phase detection system is designed to protect the offsite power sources from a loss of phase scenario. Eleven SEL relays were installed to provide detection and alarm capability for open phase conditions associated with the three 500kV-13kV service transformers, four voltage regulators, and four 13kV-4kV service transformers. The relays are wired to provide main control room annunciation if a loss of one or two phase conditions is detected or if the associated relays are non-functional.
In lieu of automatic open phase protective actions, Exelon implemented an alarm only strategy which relies on proper operator actions to diagnose and respond to an open phase condition. At the end of this inspection, the SEL relays were monitoring the associated power sources and would provide main control room annunciation if a loss of one or two phase conditions was detected or if a relay was non-functional.
INSPECTION RESULTS
Observation: Temporary Instruction 2515/194 - Section 03.01(a) and
- (c) Results 2515/194 Based on discussions with Exelon staff, review of design and testing documentation, and walkdowns of installed equipment, the inspectors had reasonable assurance that Exelon is appropriately implementing the voluntary industry initiative at Calvert Cliffs Nuclear Power Plant, Units 1 and 2. The inspectors verified the following criteria:
Detection, Alarms and General Criteria 1. [03.01(a)(1)] Open phase conditions are detected and alarmed in the control room.
2. [03.01(a)(2)] In scenarios where automatic detection may not be possible due to very low or no load conditions, or when transformers are in a standby mode, automatic detection will occur as soon as loads are transferred to the standby source.
Additionally, where automatic detection is not reliable, Exelon has established monitoring requirements on a per shift basis, to look for evidence of an open phase condition.
3. [03.01(a)(3)] The open phase condition design and 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. Additionally, Exelon has demonstrated that the actuation circuit design does not result in lower overall plant operation reliability.
4. [03.01(a)(4)] No Class-1E circuits were replaced with non-Class-1E circuits in this design.
5. [03.01(a)(5)] The Updated Final Safety Analysis Report was updated to discuss the design features and analyses related to the effects of any open phase condition design vulnerability.
6. [03.01(a)(6)] The open phase condition detection and alarm components are maintained in accordance with Exelons procedures or maintenance program, and periodic tests, calibrations setpoint verifications or inspections (as applicable) have been established.
Use of Risk-Informed Evaluation Method 1. [03.01(c)(1)] The plant configuration matched the changes made to the probabilistic risk assessment model to address an open phase condition, and the logic of the probabilistic risk assessment model changes is sound.
2. [03.01(c)(2)] The procedures which validate that the open phase condition alarm would identify the proper indication to validate the open phase conditions at all possible locations.
3. [03.01(c)(3)] Observations associated with procedure(s) and operator actions required to respond to an open phase condition alarm and potential equipment trip match the Human Reliability
Analysis.
4. [03.01(c)(4)] Assumptions listed in the NEI 19-02 Appendix A evaluation and the
sensitivity analyses listed in Section 5 of the evaluation.
5. [03.01(c)(5)] Assumptions, procedures, operator actions and Exelons analyses specified above are consistent with the plant-specific design and licensing basis, including:
- (a) Initiating events considered in the analysis
- (b) Boundary conditions specified in Attachment 1 of the NEI Voluntary Industry Initiative, Revision 3
- (c) Operating procedures for steps taken to recover equipment assumed tripped/locked out or damaged due to the open phase conditions (or use of alternate equipment)
- (d) Where recovery was assumed in the probabilistic risk assessment analysis for tripped electric equipment, restoration of the equipment was based on analyses that demonstrate that automatic isolation trips did not result in equipment damage
EXIT MEETINGS AND DEBRIEFS
The inspectors verified no proprietary information was retained or documented in this report.
- On July 14, 2021, the inspectors presented the Temporary Instruction 2515/194 Inspection results to Mr. Thomas Haaf, Site Vice President and other members of the licensee staff.
DOCUMENTS REVIEWED
Inspection
Procedure
Type
Designation
Description or Title
Revision or
Date
2515/194
Corrective Action
Documents
Resulting from
Inspection
4434683
4434789
4434994
4435033
4435115
Drawings
Electrical Main Single Line Diagram
Revision 54
Engineering
Changes
ECP-14-000629
Open Phase Detection for P-13000-1
Revision 0
ECP-15-000572
Open Phase Detection for P-13000-2
Revision 0
ECP-17-000022
Open Phase Detection Project Support for Revised Algorithm
Revision 0
ECP-17-000029
Calvert Cliffs Electrical Distribution Reliability Improvement
Project (EDRIP) 500kV/13.8kV
Revision 0
Miscellaneous
CA-MISC-028
Calvert Cliffs Nuclear Power Plant Open Phase Condition
Evaluation
Revision 0
Procedures
Electrical Distribution Control System Panel 0C003 Alarm
Manual
Revision 0
13kV & 4kV Essential Feeder Bkrs Control Board Alarm
Manual
Revision 38
13kv & 4kv Essential Feeder Bkrs Control Board Alarm
Manual
Revision 43
13kv & 4kv Essential Feeder Bkrs Control Board Alarm
Manual
Revision 37