05000454/LER-2014-001, Regarding Oa Essential Service Water (SX) Makeup Pump Unexpected Auto Start During Ob SX Pump Monthly Surveillance
| ML14083A152 | |
| Person / Time | |
|---|---|
| Site: | Byron  |
| Issue date: | 03/24/2014 |
| From: | Kearney F Exelon Generation Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| 1.10.0101, BYRON 2014-0031 LER 14-001-00 | |
| Download: ML14083A152 (4) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(iv)(A), System Actuation 10 CFR 50.73(a)(2)(iv)(B), System Actuation 10 CFR 50.73(a)(2)(i) 10 CFR 50.73(a)(2)(vii), Common Cause Inoperability 10 CFR 50.73(a)(2) 10 CFR 50.73(a)(2)(viii)(A) 10 CFR 50.73(a)(2)(ii)(B), Unanalyzed Condition 10 CFR 50.73(a)(2)(viii)(B) 10 CFR 50.73(a)(2)(ix)(A) 10 CFR 50.73(a)(2)(x) 10 CFR 50.73(a)(2)(v)(A), Loss of Safety Function - Shutdown the Reactor 10 CFR 50.73(a)(2)(v)(B), Loss of Safety Function - Remove Residual Heat 10 CFR 50.73(a)(2)(i)(A), Completion of TS Shutdown 10 CFR 50.73(a)(2)(v), Loss of Safety Function 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications |
| 4542014001R00 - NRC Website | |
text
Byron Generating Station 4450 North German Church Road Exeton Generation March 24, 2014 LTR:
BYRON 2014-0031 File:
1.10.0101 United States Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Byron Station, Units 1 and 2 Facility Operating License Nos. NPF-37 and NPF-66 NRC Docket Nos. STN 50-454 and STN 50-455
Subject:
Licensee Event Report (LER) 454-2014-001-00, CA Essential Service Water (SX)
Makeup Pump Unexpected Auto-Start during OB SX Pump Monthly Surveillance Enclosed is an LER concerning the Byron Station unexpected auto-start of the OA SX Makeup Pump that occurred on January 23, 2014. This condition is reportable to the NRC in accordance with 10 CFR 50.73(a)(2)(iv)(A) Any event or condition that resulted in manual or automatic actuation of any of the sytems listed in paragraph 10 CFR 50.73(a) (2) (iv) (B).
Should you have any questions concerning this submittal, please contact Mr. Steven Gackstetter, Regulatory Assurance Manager, at (815) 406-2800.
Respectfully, Site Vice President Byron Station FAK!GC/sg
Enclosure:
LER 454-2014-001-00 cc:
Regional Administrator NRC Region Ill NRC Senior Resident Inspector Byron Nuclear Power Station
NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY 0MB: NO. 3150-0104 EXPIRES: 01131/2017 (02-2014)
Estimated burden per response to comply with this mandatory collection request: 80 hours9.259259e-4 days <br />0.0222 hours <br />1.322751e-4 weeks <br />3.044e-5 months <br />.
Reported lessons learned are incorporated into the licensing process and fed back to industry.
Send comments regarding burden estimate to the FOIA. Privacy and Information Collections LICENSEE EVENT REPORT (LER)
Branch (T-5 F53), U.S. Nudear Regulatory Commission, Washington, DC 20555-0001, or by internet e-mail to fnfocoflects.Resource@nrc.gov, and to the Desk Officer, Office of Information end (See Page 2 for required number of Regulatory Affairs, NEOB-10202, (3150-0104), Office of Management and Budget, Washington, DC 20503. If a means used to impose an information collection does not display a currently valid 0MB digits/characters for each block) control number, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.
- 13. PAGE Byron Station, Unit 1 05000454 1
OF 3
- 4. TITLE CA Essential Service Water (SX) Makeup Pump Unexpected Auto Start during OB SX Pump Monthly Surveillance
- 5. EVENT DATE
- 6. LER NUMBER
- 7. REPORT DATE
- 8. OTHER FACILITIES INVOLVED FACILITY NAME KET NUMBER SEQUENTIAL REV MONTH I
DAY I
YEAR Byron Station, Unit 2 05000455 MONTH DAY YEAR YEAR NUMBER NO.
I I
FACILITY NAME NUMBER 01 23 2O14 2014-001
- - 00 03 24 2014 N/A N/A
- 9. OPERATING MODE
- 11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR §: (Check all that apply)
LI 20.2201(b)
LI 20.2203(a)(3)O)
LI 50.73(a)(2)(i)(C)
LI 50.73(a)(2)(vii)
LI 20.2201(d)
LI 20.2203(a)(3)Oi)
LI 50.73(a)(2)Oi)(A)
LI 50.73(a)(2)(viii)(A)
[1 20.2203(a)(1)
LI 20.2203(a)(4)
LI 50.73(a)(2)(ii)(B)
LI 50.73(a)(2)(viii)(B)
LI 20.2203(a)(2)(i)
LI 50.36(c) (1 )(i)(A)
LI 50.73(a)(2)Oii)
El 50.73(a)(2)(ix)(A)
LI 20.2203(a)(2)(ii)
LI 50.36(c)(1 )Oi)(A) 50.73(a)(2)Qv)(A)
LI 50.73(a)(2)(x)
LI 20.2203(a)(2)(iii)
LI 50.36(c)(2)
LI 50.73(a)(2)(v)(A)
LI 73.71 (a)(4)
LI 20.2203(a)(2)(iv)
LI 50.46(a)(3)Oi)
LI 50.73(a)(2)(v)(B)
LI 73.71(a)(5) 100 LI 20.2203(a)(2)(v)
LI 50.73(a)(2)(i)(A)
LI 50.73(a)(2)(v)(C)
LI 50.73(a)(2)(i)(B)
LI 50.73(a)(2)(v)(D)
Specity in Abstract below or in
A.
Plant Condition Prior to Event Event DatelTime: January 23, 2014/0539 hours CST Unit 1
- - Mode 1
- - Power Operations, Reactor Power 100 percent Unit 2
- - Mode 1
- - Power Operations, Reactor Power 100 percent Reactor Coolant System [AB]: Normal operating temperature and pressure.
B.
Description of Event
On January 23, 2014, Byron Unit 1 and Unit 2 were in Mode 1 with reactor power at 100 percent. Operators were restoring the GB SX Makeup Pump to an available on line status following a scheduled work window.
In preparation to execute an auto-start of the GB SX Makeup Pump, the shift began lowering SX tower basin level per Byron operating procedure BOP SX-12, Makeup to an Essential Service Water Mechanical Draft Cooling Tower Basin. During the lowering of the SX basin level, an auto-start of the GA SX Makeup Pump occurred due to a sensed low level in the GA SX tower basin.
The minimum allowed Technical Specification (TS) level for SX Cooling Tower basin water level is 60 percent per Byron TS LCO 3.7.9, Ultimate Heat Sink (UHS). The auto-start level setpoint for each pump is 62 percent. The Byron SX Cooling Tower contains separate basins for the GA and GB SX trains which are hydraulically connected at 64 percent level and above and are physically separated below 64 percent level.
The SX basin level was being lowered on both basins, as they are cross-tied to the 64 percent level. Basin level was being lowered in automatic mode on the Manual/Auto (M/A) station for both GA and GB basin level controllers by reducing the demand signal on the M/A station. This practice causes the makeup to the basins to remain closed until the setpoint on the M/A station is reached. The demand setpoint on the M/A station was set to 71 percent in accordance with BOP SX-1 2, which is well above the expected auto-start setpoint of 62 percent.
As the controller was responding in automatic mode to the setting at 71 percent basin level, it overshot and reached 68 percent, at which time the GA SX Makeup Pump auto started. Additionally, there were adverse environmental conditions outside including high winds that were causing wave action in both basins, which likely contributed to the auto-start of the GA SX Makeup Pump. This level is approximately 6 percent above the designed auto start level of 62 percent.
C. Cause of Event
The cause of the event was that the operating procedure directs the controller to be set at a level that leaves little margin to the SX Makeup Pump automatic start level switch setpoint, especially when adverse environmental conditions such as high winds and wave action exist.
D. Safety Significance
The GA SX Makeup Pump was Operable per Byron TS 3.7.9, Ultimate Heat Sink (UHS). The pump was demonstrated to start on low basin level and was within the frequency requirements of the TS Surveillance Requirement. in this event the pump started early, which is conservative relative to the design setpoint.
Therefore, the safety significance of this issue is considered low.
E.
Corrective Actions
Corrective actions include revising the operating procedures for SX tower basin level manipulations to set the controller at a more conservative target level relative to the SX Makeup Pump trip setpoint. AdditionaJly, notes and cautions will be inserted to better alert the operator of potential SX Makeup pump auto-starts during SX tower basin level manipulations.
F.
Previous Occurrences
There have been no previous occurrences of this nature in the previous three years.