ML25317A768
| ML25317A768 | |
| Person / Time | |
|---|---|
| Site: | Beaver Valley, Millstone, Calvert Cliffs, Dresden, Davis Besse, Mcguire, Nine Mile Point, Palo Verde, Catawba, Seabrook, Brunswick, Turkey Point, River Bend, Ginna, Callaway, Robinson, South Texas, Comanche Peak, Quad Cities, FitzPatrick, McGuire, LaSalle  |
| Issue date: | 10/31/2025 |
| From: | Knott R Paragon Energy Solutions |
| To: | Hoc H Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| Download: ML25317A768 (1) | |
Text
From:
Richard Knott To:
Hoc, HOO X Cc:
Douglas VanTassell; Tighe Smith
Subject:
[External_Sender] Part 21 Interim Notification Date:
Friday, October 31, 2025 7:11:29 AM Attachments:
ATT00001.txt Interim Report P21-10112025-INT NRC Final.pdf Good morning,
Please see attached interim report provided per 10CFR Part 21 section 21.21(a)(2). Paragon requires more time to complete the failure analysis related to the reported battery failures. We estimate completing the analysis on or before 12/15/2025. During our ongoing evaluation we also identified the Duke Oconee Nuclear Station was not included in the list of potentially affected Licensees.
I confirm that no proprietary, legally privileged, and/or confidential information is included in the attached notification.
Please contact me if you have any questions or concerns.
Best Regards, Richard Richard Knott Vice President, Quality Assurance (518)450-9706 (C) l www.ParagonES.com
Confidentiality Note: The information contained in this message (and attachments) is confidential and may be legally privileged. The message is intended solely for the addressee(s). If you are not the intended recipient, you are hereby notified that any use, dissemination, or reproduction is strictly prohibited and may be unlawful. If you are not the intended recipient please contact the sender by return e-mail and destroy all copies of the original message and attachments.
Paragon Energy Solutions 7410 Pebble Drive
- Fort Worth, Texas
- 76118 817-284-0077
- Fax 817-590-0484 Page 1 of 9 10/31/2025 To:
Document Control Desk U.S. Nuclear Regulatory Commission Washington, DC 20555 Fax Number (301)816-5151 10CFR Part 21 Interim Notification: P21-10112025-INT Rev 0
Subject:
Potential Deviation Related to Stryten (formally GNB) N&M Series Flooded Batteries Installed in 24VDC, 48VDC, 125VDC and 250VDC Station Battery Strings Need for Additional Analysis Pursuant to 10CFR 21.21 (a)(2), Paragon Energy Solutions, LLC is providing this interim notification of ongoing analysis for Part 21 reportability associated with Stryten (GNB) Station Batteries.
Condition being evaluated:
On October 11th, 2025, Paragon reported (NRC EN 57981) failure conditions experienced at Constellation Quad Cities Clean Energy Center and Calvert Cliffs Clean Energy Center. Quad Cities experienced positive post separation from three cells in a safety related battery string at the post seal nut region. The first was identified while replacing a cell after trouble shooting abnormal fluctuations in DC bus voltage following isolation of the connected battery charger. After replacement and upon initiation of the subsequent service discharge test, an adjacent cell positive post separated, resulting in a localized fire near the post. The third cell failed while conducting maintenance to replace the battery string. More recently, in September 2025, Constellation Calvert Cliffs Clean Energy Center reported separation of a positive post from a cell upon initiation of a service test discharge resulting in electrical arcing at the cell post area. The affected battery cells have been in service for 14 years and 11 years respectively. This phenomenon only affects the positive posts on the battery.
Paragon is currently conducting an extensive failure analysis and has not yet identified a defect in the cell post seal design or manufacturing process. More time is necessary to complete the failure analysis; however, the current postulated cause of the post separation is due to a corrosion mechanism. Creep corrosion (a long-term corrosion mechanism), leading to the onset of nodular corrosion in the threaded region of the positive post can occur in flooded lead-acid batteries. Post seal integrity, stresses applied to the post, and elevated temperature above recommended values can all contribute to the accelerated corrosion and premature post failures identified.
Date when evaluation is expected to be complete: 12/15/2025.
See attached list for Licensees utilizing the affected N&M series batteries.
P21-10112025-INT, Rev. 0 Page 2 of 9 Paragon recommends the following for affected Licensees:
- 1. For In-service Batteries: (See attached pictures for examples of the conditions below)
- a. Indication of nodular corrosion is often visible in advanced stages, and Paragon is recommending impacted licensees perform an inspection of their batteries for nodular corrosion.
- b. While performing the inspection for nodular corrosion, identify conditions that could add unnecessary stress to the cell positive posts such as:
o Verify intercell cabling is properly supported such that the weight of the cables is not supported by the post alone.
o Verify proper alignment of intercell connector plates and cells.
- c. During individual cell float voltage measurements (per Manufacturers Instruction Manual and IEEE-450), if abnormally high float cell voltage is measured, Paragon recommends the condition be evaluated in accordance with IEEE 450:2020 C.3.2 to determine if compromised cell post integrity is contributing to the abnormal measurement.
- d. Documented cell deficiencies and anomalies, along with pictures, are requested to be sent to Paragon at Batteries@Paragones.com. Paragon can assist the station with inspection and evaluation of the conditions of the batteries. For emergent issues please call 865-888-6853.
- 2. For Sites Planning Replacement:
- a. Licensees preparing for battery installation/replacement are recommended to contact Paragon and arrange for our team to perform an internal inspection below the positive post seal nut to validate post seal integrity prior to release from the station warehouse or once the battery cells are staged for installation.
- b. Once the post seal verification inspection is complete, Paragon considers new batteries will perform their safety function once installed and maintained in accordance with the Manufacturers Manual, IEEE-450:2020, and Reg Guide 1.129 Rev 4.
- 3. For optimal battery service life, maintain battery room temperature in the recommended range of 75F to 77F.
Based on the analysis completed to date, the observed failure mode takes several years to advance to the point of failure. For in-service batteries, the inspections recommended above enable the Licensees to identify suspect cells and allow for corrective action prior to reaching the point of individual cell failure such that the battery system will perform for the intended service life.
P21-10112025-INT, Rev. 0 Page 3 of 9 Paragon is standing by to assist affected Licensees with questions and concerns regarding this notification.
- Regards, Richard Knott Vice President Quality Assurance Paragon Energy Solutions 817-284-0077 rknott@paragones.com
P21-10112025-INT, Rev. 0 Page 4 of 9 List of Licensees Utilizing Affected Battery Models Paragon has supplied Class 1E and/or commercial grade batteries to the plants identified below. All installations are GNB/Stryten batteries/cells supplied under the Paragon Quality Assurance Program since 2005. It is recommended that plants also consider installations of M and N Series batteries that have been approved for service life extension beyond the 20-year qualified life recommendation or supplied by alternate suppliers.
Site Battery/Cell Model Ameren Callaway NCN-13S, NCN-23S Arizona Public Service (APS)
Palo Verde NCN-33, NCN-33S Constellation Calvert Cliffs NCN-15, NCN-21, NCN-21S, NCN-27 Dresden 2-MCX-5, NCN-21, NCN-21S, NCN-27 Fitzpatrick NCN-35 Ginna NCN-21 LaSalle NCN-17, NCN-17S, NCN-27, NCN-27S, 2-MCX-5 Nine Mile Point NCN-35, NCN-35S Quad Cities 2-MCX-5, NCN-21, NCN-21S, 2-MCX-05, MCX-05 Dominion Millstone NCN-11S, NCN-27, NCN-27S, NCN-35, NCN-35S, NCX-35 NextEra Energy Seabrook NCN-35S Duke Brunswick NCX-9S, NCN-17, NCN-17S Carolina Power & Light NCN-17 Catawba NCN-9, NCN-21, NCN-27 H.B. Robinson NCN-15 McGuire NCN-27 Oconee NCN-27S Entergy River Bend NCN-29S, NCN-29S, NCX-35S Florida Power & Light (FPL)
Turkey Point NCN-17, NCN-17S, NCN-25, NCN-25S, NCN-27, NCN-27S Vistra Beaver Valley NCX-29S, NCX-33S, NCX-35S Comanche Peak NCN-17, NCN-17S, NCN-27, NCN-27S Davis Besse NCN-21, NCN-21S
P21-10112025-INT, Rev. 0 Page 5 of 9 Site Battery/Cell Model South Texas Nuclear Operating Company (STPNOC)
South Texas Project NCN-17, NCN-17S, NCN-27 Bruce Power Bruce Power MCX-09S, MCX-13S, NCN-27, NCN-27S, NCN-35, NCN-35S Siemens/Bruce Power MCX-13, NCN-27 KHNP Hanbit NCN-11S, NCN-33S Kori NCN-11S, NCX-17S, NCN-21S, NCN-25, NCX-27, NCX-31, NCX-31S, NCN-33S, NCX-35 OPG OPG NCN-23 Note: The S suffix is an administrative designator only. The design and manufacturing of cells with or without the S is the same.
P21-10112025-INT, Rev. 0 Page 6 of 9 Visual Inspection Conditions Requiring Further Evaluation During battery system visual inspection, attention should be given to the following conditions.
Positive Post Corrosion Indications - Figures 1 thru 4 below provide visual indicators of corrosion in the post seal area.
Figure 1 Figure 2 Bulging in post seal nut Crack in post seal nut Crack in jar cover Indication of post blackening corrosion past the seal Crack in post seal nut
P21-10112025-INT, Rev. 0 Page 7 of 9 Figure 3 Figure 4 Indication of post blackening corrosion past the seal Failed Post Indication of post blackening corrosion past the seal Crack in post seal nut Crack in jar cover
P21-10112025-INT, Rev. 0 Page 8 of 9 Battery Cabling Support - intercell/tier battery cabling should be well supported with sufficient bend radius to minimize post stress.
Figure 5. Unsupported Inter-Tier Cabling
P21-10112025-INT, Rev. 0 Page 9 of 9 Cell Alignment - Cells should be arranged in the racks to prevent unwanted misalignment which could contribute to stress at the battery terminal post.
Figure 6: (Top) Ideal Cell Alignment, (Bottom Left) Unwanted, Rotated Cell Alignment, (Bottom Right) Unwanted, Shifted Cell Alignment