05000250/LER-2002-001, Florida Power & Light, Vital Battery Cell Voltage Below Technical Specification Allowable on June 5, 2002
| ML022240149 | |
| Person / Time | |
|---|---|
| Site: | Turkey Point  |
| Issue date: | 08/01/2002 |
| From: | Mcelwain J Florida Power & Light Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| L-2002-126 LER-02-001-00 | |
| Download: ML022240149 (5) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications |
| 2502002001R00 - NRC Website | |
text
0 FPL AUG 0 1 2002 L-2002-126 10 CFR § 50.73 U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, D. C. 20555 Re:
Turkey Point Unit 3 Docket No. 50-250 Reportable Event: 2002-001-00 Date of Event: June 5, 2002 Vital Battery Cell Voltage Below Technical Specification Allowable The attached Licensee Event Report 250/2002-001-00 is being submitted pursuant to the requirements of 10 CFR § 50.73(a)(2)(i)(B).
If there are any questions, please call Olga Hanek at (305) 246-6607.
Very truly yours, hn P. McElwain Vice President Turkey Point Nuclear Plant OH Attachment cc:
Regional Administrator, USNRC, Region II Senior Resident Inspector, USNRC, Turkey Point Nuclear Plant 721 an FPL Group company
Abstract
On June 5, 2002, with the unit operating at approximately 100% reactor power, a quarterly surveillance performed under Technical Specification 4.8.2.1.b recorded a 3A vital battery individual cell voltage that was below the Technical Specification allowable value. This condition was recognized during a review of the quarterly surveillance test results by an Electrical Maintenance Supervisor at 1340 on June 17, 2002. This was reported immediately to the Nuclear Plant Supervisor and the 3A battery was declared inoperable. Operation of the unit with an inoperable vital battery for more than two hours is prohibited by Technical Specification 3.8.2.1. Since the condition existed for a longer time than permitted by Technical Specification action statement 3.8.2.1.b, the plant entered TS 3.0.3 and completed the required recovery actions within the time allowed by Technical Specification 3.0.3. The spare battery was placed in service on June 17, 2002 at 1423 and Technical Specification 3.0.3 was exited. This event is reported per the requirements of 10CFR50.73(a)(2)(i)(B).
The cause of this event was a small internal short circuit, causing a low voltage condition on one vital battery cell. Contributing causes were personnel error and inadequate procedures for identifying the Technical Specification impact of the failed surveillance. Corrective actions include personnel training and revisions to surveillance procedural guidance.
NRC FORM 366 (1-2001)
(If more space is required, use additior
EVENT DESCRIPTION
On June 5, 2002, with the unit operating at approximately 100% reactor power, a quarterly surveillance performed under Technical Specification (TS) 4.8.2.1.b recorded a 3A vital battery [EJ, BTRY] individual cell voltage that was below the Technical Specification allowable value. This condition was recognized during a review of the quarterly surveillance test results by an Electrical Maintenance Supervisor at 1340 on June 17, 2002. This was reported immediately to the Nuclear Plant Supervisor (NPS), and the 3A battery was declared inoperable. With one of the required battery banks inoperable, TS 3.8.2.1 action b. allows two hours to restore the required battery banks to operable status or be in at least hot standby within the next 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> and in cold shutdown within the following 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />. Since the condition existed for a longer time than permitted by Technical Specification action statement 3.8.2.1.b, the plant entered TS 3.0.3 on June 17, 2002 at 1340. The spare battery was placed in service on June 17, 2002 at 1423 completing the required recovery actions within the time allowed by Technical Specification 3.0.3. Technical Specification 3.0.3 was exited. This event is reported per 10CFR50.73(a)(2)(i)(B) due to operation of the unit in a condition prohibited by the plant's TS.
BACKGROUND Emergency power for vital instrumentation and controls is supplied by a station DC power system containing five safety related 125VDC batteries and four DC distribution panels. Two battery banks are associated with each unit. A spare battery bank can be substituted for any of the other four battery banks to allow for testing or maintenance. Each battery has been sized to support operation of its required loads for two hours without terminal voltage falling below its minimum required value.
Technical Specification Table 4.8-2, Category B provides the battery cell voltage limit and allowable values. A battery whose parameters satisfy the allowable value, but does not meet the limits may be considered operable, provided the parameters are restored to the Category B limits within 7 days. Values that are below the allowable value render the battery inoperable. The limit and allowable value for battery float voltage are 2.13 VDC and 2.07 VDC, respectively.
The 3A vital battery consists of 60 individual cells connected in series. Cell #28 voltage of the 3A vital battery was found at 2.06 VDC, which is below the allowable limit.
SEQUENCE OF EVENTS On June 5, 2002, a quarterly surveillance performed under Technical Specification (TS) 4.8.2.1.b recorded a 3A vital battery individual cell #28 voltage of 2.06 VDC, which is below the TS limit and allowable values of 2.13 VDC and 2.07 VDC, respectively. As required by procedure, the journeyman immediately notified his General Maintenance Leader (GML) of the unacceptable as-found condition. The GML instructed the journeyman to complete the surveillance for the rest of the battery. The journeyman noted in the remarks section of the procedure that the voltage on cell #28 did not meet acceptance criteria, and proceeded to complete the surveillance for the rest of the battery at the end of shift.
The GML has the responsibility to review the as-found cell voltage data to determine if any corrective actions are required, such as electrolyte level correction or the performance of an equalizing charge. The GML did not recognize the TS impact of not meeting the acceptance criteria on cell #28. Since the surveillance test was completed at the end of the shift, the GML turned over the work package for review to an Electrical Supervisor.
(If more space is required, use additional copies of (If more space is required, use additional copies of NRC Form 366A) (17)
With a conservative assumption that the internal short had reduced the capacity of cell #28 to zero, the evaluation determined that the battery string was capable of meeting its design load profile. The as-found voltage and electrolyte values for the remaining 59 cells in the 3A battery support the following conclusions: 1) the 3A battery was capable of providing the capacity found during the previous performance test (104%); 2) the electrolyte solution of the battery was not degraded and was capable of passing the current from the remaining 59 cells; 3) the remaining cells had sufficient capacity to satisfy the required load profile; and 4) the minimum battery terminal voltage during a design basis event would remain above the minimum design value of 105 VDC.
Therefore, the noted degraded condition of cell #28 would not have prevented the 3A battery string from meeting its design function. Thus, the health and safety of the public were not affected by this event.
CORRECTIVE ACTIONS
The following corrective actions have been completed:
- 1. Replaced cell #28 of the 3A vital battery
- 2. Provided training to Electrical Maintenance personnel addressing the event and emphasizing the reporting requirements and management expectations.
- 3. Battery Surveillance Procedures have been enhanced to include caution statements requiring immediate NPS notification, if acceptance criteria is not met, and a briefing requirement prior to performing the surveillance to ensure all personnel are aware of the applicable Technical Specification and NPS notification requirements.
ADDITIONAL INFORMATION
EIIS Codes are shown in the format [EIIS SYSTEM: IEEE component function identifier, second component function identifier (if appropriate)]. There have been no previous similar events at Turkey Point Units 3 and 4.
N