05000237/LER-2016-001, Regarding Secondary Containment Differential Pressure Transient
| ML16104A031 | |
| Person / Time | |
|---|---|
| Site: | Dresden  |
| Issue date: | 04/08/2016 |
| From: | Karaba P Exelon Generation Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| SVPLTR 16-0013 LER 16-001-00 | |
| Download: ML16104A031 (4) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(v), Loss of Safety Function 10 CFR 50.73(a)(2)(ii)(A), Seriously Degraded 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)(iv)(A), System Actuation 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)(i)(B), Prohibited by Technical Specifications 10 CFR 50.73(a)(2)(vii), Common Cause Inoperability |
| 2372016001R00 - NRC Website | |
text
J.cs/' Exelon Generation SVPL TR # 16-0013 April 8, 2016 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Dresden Nuclear Power Station, Unit 2 and 3 Dresden Generating Station 6500 North Dresden Road Morris. IL 60450 www.exeloncorp.com 10 CFR 50.73 Renewed Facility Operating License Nos. DPR-19 and DPR-25 NRC Docket No. 50-237 and 50-249
Subject:
Licensee Event Report 237/2016-001-00, Secondary Containment Differential Pressure Transient Enclosed is Licensee Event Report 237/2016-001-00, "Secondary Containment Differential Pressure Transient ". This report describes events which are being reported in accordance with 10 CFR 50.73(a)(2)(v)(C}, "Any event or condition that could have prevented the fulfillment of the safety function of... systems that are needed to control the release of radioactive material".
There are no regulatory commitments contained in this submittal.
Should you have any questions concerning this letter, please contact Mr. Bruce Franzen at (815) 416-2800.
Respectfully, Peter J Karaba Site Vice President Dresden Nuclear Power Station Enclosure Licensee Event Report 237/2016-001-00 cc:
Regional Administrator - NRC Region Ill NRC Senior Resident Inspector - Dresden Nuclear Power Station
NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 10/31/2018 (11-2015) iJ>'Atltc1u,
, the NRG may not conduct or sponsor, and a person is not required to respond to, the information collection.
- 3. PAGE Dresden Nuclear Power Station, Unit _2 05000237 1 OF 3
- 4. TITLE Secondary Containment Differential Pressure Transient
- 5. EVENT'DATE
- 6. LEA NUMBER
- 7. REPORT DATE
- 8. OTHER FACILITIES INVOLVED I
SEQUENTIAL I REV FACILITY NAME DOCKET NUMBER MONTH DAY YEAR YEAR NUMBER NO.
MONTH DAY YEAR Dresden Unit 3 05000249 FACILITY NAME DOCKET NUMBER 02 09 2016 2016 - 001
- - 00 04 08 16 05000
- 9. OPERATING MODE
- 11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR §: (Check all that apply)
D 20.2201 (bl D 20.2203(a)(3)(il D 50.73(a)(2)(ii)(A)
D 50.73(a)(2)(viii)(A) 1 D 20.2201 (dl D 20.2203(a)(3)(iil D 50.73(a)(2)(ii)(B)
D 50.73(a)(2)(viii)(B)
D 20.2203(a)(1 l D 20.2203(a)(4l D so.13(a)(2)(iiil D 50.73(a)(2)(ix)(A)
D 20.2203(a)(2)(il D 50.36(c)(1 )(i)(A)
D 50.73(a)(2)(iv)(A)
D 50.73(a)(2)(x)
- 10. POWER LEVEL D 20.2203(a)(2)(iil D 50.36(c)(1 )(ii)(A)
D 50.73(a)(2)(v)(A)
D 13.11 (a)(4l D 20.2203(a)(2)(iiil D so.3a(c)(2)
D 50.73(a)(2)(v)(B)
D 13.11 (a)(5l D 20.2203(a)(2)(iv)
D so.4a(a)(3l(iil [8] 50.73(a)(2)(v)(C)
D 13.11(a)(1) 100 D 20.2203(a)(2)(v)
D 50.73(a)(2)(i)(A)
D 50.73(a)(2)(v)(D)
D 13.11(a)(2)(il D 20.2203(a)(2)(vi)
D 50.73(a)(2)(i)(B)
D 50.73(a)(2)(vii)
D 13.11(a)(2)(iil
- ~2 ;;~,,~~~-
- ?;W'.~
D so.13(a)(2)(il(Cl D OTHER Specify in Abstract below or in C.
Cause of Event
The apparent cause of the event was determined to be the system operating with an out of tolerance (OOT} U3 Area DP controller that degraded total system margin.
D.
Safety Analysis
With the exception of the degraded area differential pressure controller, all equipment responded as designed. Operator action to secure Unit 3 RBV in accordance with proceduralized guidance prevented the further degradation of the reactor building differential pressure, maintaining the negative differential pressure and preventing loss of safety function.
This event is of very low safety significance.
This event is being reported under 1 O CFR 50. 73(a)(2)(v)(C) "Any event or condition that could have prevented the fulfillment of the safety function of... systems that are needed control the release of radioactive material."
E.
Corrective Actions
The degraded area DP controller was calibrated and the Unit 3 RBV restored to operation.
Gaps in the maintenance strategy will be identified and eliminated. System upgrades will be reviewed for implementation. The operational response procedure for the loss of plant heating steam will be reviewed for enhancements.
F.
Previous Occurrences
A previous event in 2009 was found during the investigation where a degraded area DP controller caused a loss of secondary containment differential pressure. This event was used in the development of corrective actions.
G.
Component Failure Data
Manufacturer Model Johnson Controls T-5312
PLANT AND SYSTEM IDENTIFICATION
SEQUENTIAL NUMBER 001 REV NO.
00 Dresden Nuclear Power Station (DNPS), Unit 2, is a General Electric Company Boiling Water Reactor with a licensed maximum power level of 2957 megawatts thermal. The Energy Industry Identification System codes used in the text are identified as [XX].
A.
Plant Conditions Prior to Event:
Unit: 02 Event Date: 02/09/2016 Reactor Mode: 1 Mode Name: Power Operation B.
Description of Event
Event Time: 1900 CST Power Level: 100 percent On 2/9/16 at 19:00, the operating heating boiler [LV] shutdown. At 19:15, the Main Control Room (MCR) received alarms indicating that Reactor Building (RB) [NG] DP was below -0.3" wc. An Equipment Operator (EO) was dispatched to take local RB DP readings on the Refuel Floor. Local readings were averaged to be -0.35" we. Operations verified that all Secondary Containment interlock doors, RB blowout panels and reactor building ventilation [VA] (RBV) exhaust hatches were in the proper configuration.
Following the loss of the heating boiler, Operations entered the associated response procedure. This procedure directed field operators to block open all doors of both the U2 and U3 RBV supply plenums to prevent freezing of the ventilation filters and heating coils within the plenums.
At 21 :42, another step change in RB DP was noticed by Operations. Main Control Room RB DP indication degraded from -0.25" wc to -0.12" we. An EO was dispatched to obtain local readings on the Refuel Floor. Local readings were averaged at -0.24" we which required entry into Tech Spec 3.6.4.1.A due to RB DP being greater than Tech Spec required -0.25" wc by local average on the refuel floor.
At 22:05, U3 RBV was secured, and at 22:07 Tech Spec 3.6.4.1.A was exited when RB DP returned to below -0.25" we.
An 8 hour9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> non-emergency notification was made via Emergency Notification System #51721 in accordance with 1 O CFR 50.72(b)(3)(v)(C) for the loss of Secondary Containment.
C.
Cause of Event
The apparent cause of the event was determined to be the system operating with an out of tolerance (OOT} U3 Area DP controller that degraded total system margin.
D.
Safety Analysis
With the exception of the degraded area differential pressure controller, all equipment responded as designed. Operator action to secure Unit 3 RBV in accordance with proceduralized guidance prevented the further degradation of the reactor building differential pressure, maintaining the negative differential pressure and preventing loss of safety function.
This event is of very low safety significance.
This event is being reported under 1 O CFR 50. 73(a)(2)(v)(C) "Any event or condition that could have prevented the fulfillment of the safety function of... systems that are needed control the release of radioactive material."
E.
Corrective Actions
The degraded area DP controller was calibrated and the Unit 3 RBV restored to operation.
Gaps in the maintenance strategy will be identified and eliminated. System upgrades will be reviewed for implementation. The operational response procedure for the loss of plant heating steam will be reviewed for enhancements.
F.
Previous Occurrences
A previous event in 2009 was found during the investigation where a degraded area DP controller caused a loss of secondary containment differential pressure. This event was used in the development of corrective actions.
G.
Component Failure Data
Manufacturer Model Johnson Controls T-5312 S/N RY10812 Type Pneumatic Con roller