05000254/LER-2019-003, Water Found in Control Room Emergency Ventilation Air Filtration Unit
| ML19354A102 | |
| Person / Time | |
|---|---|
| Site: | Quad Cities  |
| Issue date: | 12/20/2019 |
| From: | Ohr K Exelon Generation Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| SVP-19-086 LER 2019-003-00 | |
| Download: ML19354A102 (5) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(v), Loss of Safety Function 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications |
| 2542019003R00 - NRC Website | |
text
=~Exelon Generation SVP-19-086 December 20, 2019 U.S. Nuclear Regulatory Commission ATIN: Document Control Desk Washington, D.C. 20555 Quad Cities Nuclear Power Station, Unit 1 Renewed Facility Operating License No. DPR-29 NRG Docket No. 50-254 10 CFR 50.73
Subject:
Licensee Event Report 254/2019-003-00 'Water Found in Control Room Emergency Ventilation Air Filtration Unit" Enclosed is Licensee Event Report 254/2019-003-00 'Water Found in Control Room Emergency Ventilation Air Filtration Unit", for Quad Cities Nuclear Power Station, Unit 1.
This report is submitted in accordance with 1 O CFR 50. 73(a)(2)(i)(B) for any operation or condition which was prohibited by the plant's Technical Specifications. It is also being submitted in accordance with 10 CFR 50.73(a)(2)(v)(D) for any event or condition that could have prevented the fulfillment of the safety function of structures or systems that are needed to mitigate the consequences of an accident.
There are no regulatory commitments contained in this letter.
Should you have any questions concerning this report, please contact Rachel Luebbe at (309) 227-2813.
R~,~lL-Kenneth S. Ohr Site Vice President Quad Cities Nuclear Power Station cc:
Regional Administrator-NRG Region Ill NRG Senior Resident Inspector - Quad Cities Nuclear Power Station
NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 03/31/2020 (04-2018)
, the NRC may not conduct or sponsor, and a person is not required to respond to, the '1fonnation collecfon.
3.Page Quad Cities Nuclear Power Station, Unit 1 05000254 1
OF 4
- 4. Title Water Found in Control Room Emergency Ventilation Air Filtration Unit
- 5. Event Date
- 6. LER 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 Quad Cities Nuclear Power Station Unit 2 05000265 Facility Name Docket Number 10 27 2019 2019 - 003 00 12 20 2019 n/a 05000
- 9. Operating Mode
- 11. This Report is Submitted Pursuant to the Requirements of 10 CFR §: {Check all that apply)
D 20.2201(b}
D 20.2203(a}(3}(i}
D 50.73(a}(2}(ii}(A}
D 50.73(a){2}(viii}(A)
D 20.2201(d}
D 20.2203(a}(3}(ii)
D 50.73{a}(2}(ii}(B)
D 50.73(a){2}(viii}(B) 1 D 20.2203(a}( 1}
D 20.2203(a}(4}
D 50.73(a}(2)(iii)
D 50.73{a)(2}(ix)(A)
D 20.2203(a)(2)(i)
D 50.36(c}(1 }(i}(A}
D 50.73(a}(2)(iv}(A)
D 50.73{a){2}{x) 1 O. Power Level D 20.2203{a}{2}(ii)
D 50.36(c}(1 }(ii}(A}
D 50.73(a}(2}(v}(A}
D 73.71 (a)(4}
D 20.2203(a}(2}(iii}
D 50.36(c}(2)
D 50.73(a}(2}(v}(B)
D 73.71{a)(5}
D 20.2203(a}(2}(iv}
D 50.46(a}(3}(ii}
D 50.73{a}(2}(v}(C}
D 73.77(a)(1}
100 D 20.2203(a}(2}(v)
D 50.73(a}(2}(i}(A)
~
50.73(a}(2}(v}(D}
D 73.77(a}(2)(i}
D 20.2203{a}{2}{vi}
~ 50.73(a}(2}(i}(B)
D 50.73(a}(2}(vii}
D 73.77(a)(2}(ii}
D 50.73(a}(2}(i}(C}
D Other (Specify in Abstract below or in SEQUENTIAL NUMBER 003 REV NO.
00 Based on the amount of water found in the AFU on October 27, 2019, it is conservatively assumed that leakage past AOV 0-4199-315 started when the isolation from the fire protection system was removed on October 11, 2019 following maintenance. It is also conservatively assumed that the AFU was not functional from October 11, 2019, until the filters were replaced and the AFU returned to service on October 29, 2019. This 18 day period exceeds the seven (7) day Completion Time allowed under Technical Specification (TS) 3.7.4 Condition A. Therefore, this event is also reportable under 10 CFR 50.73(a)(2)(i)(B), for any operation or condition which was prohibited by the plant's Technical Specifications.
C. CAUSE OF EVENT
Due to lack of instructions in Work Order (WO) 1845827, a PMT to stroke AOV 0-4199-315 to verify full disk to seat contact following maintenance activities was not performed.
Previous WO No. 345740 which entailed performing the same work scope in 2005 included PMT instructions to verify that the valve did not leak. This information was not included in the 2019 WO.
The cause of the event is inadequate technical human performance in the preparation and review of the 2019 work instructions. A contributing cause is a lack of questioning attitude on both the scope of the work and the possible outcomes of the work.
D. SAFETY ANALYSIS
System Design
Habitability systems are provided to ensure that Main Control Room operators are able to remain in the Main Control Room and operate the plant safely under normal conditions and to maintain the plant in a safe condition under accident conditions. The worst-case design basis accident (OBA) for habitability considerations is postulated as a loss of coolant accident (LOCA) with main steam isolation valve leakage at TS limits.
Per Updated Final Safety Analysis Report (UFSAR) Section 6.4,"Habitability Systems," the Control Room Heating, Ventilation, and Air Conditioning (HVAC) systems are capable of maintaining the control room atmosphere suitable for occupancy throughout the duration of a OBA. The AFU provides filtration functions to support CREVs operation.
The emergency operation of CREVs does require manual actions.
Per UFSAR Section 6.5.1.2, "Control Room Ventilation System Filter Pack," temperature is monitored at the filter pack inlet, after the electric heater and after the activated carbon adsorber bed. The temperature element after the activated carbon adsorber provides an interlock to allow the fire protection deluge to be activated.
Safety Impact Per TS Bases 3.7.4, the CREV System is considered operable when a booster fan is operable, High Efficiency Particulate Air (HEPA) filter and charcoal adsorbers are not excessively restricting flow and are capable of performing their filtration functions, the heater, ductwork, valves, and dampers are operable, and air circulation through the filter train can be maintained.
SEQUENTIAL NUMBER 003 REV NO.
00 The wetting of the charcoal filter, prefilters, and HEPA filters, precluded the capabilities of the AFU to perform the expected filtration functions. Air flow may have also been restricted; therefore, CREV system was declared inoperable as a result of this condition. An exact time of inoperability could not be determined, so the date that the work isolation boundary was removed, October 11, 2019, is conservatively considered the start time. This time period exceeds the seven (7) day Completion Time for TS 3.7.4, Condition A, Required Action A.1.
Risk Insights The plant Probabilistic Risk Assessment (PRA) model gives no credit to the Control Room Envelope (CRE) and does not include it in the model; hence, the CREV AFU filter wetting event did not contribute to a measurable increase in risk.
This event is a Maintenance Rule Functional Failure (MRFF) and a Safety System Functional Failure (SSFF).
E. CORRECTIVE ACTIONS
Immediate:
- 1.
Isolated fire suppression system leakage
- 2.
Replaced charcoal trays, prefilters, and HEPA filters.
Follow-up:
- 1.
Repair AOV 0-4199-315 to ensure proper seat leakage.
- 2.
Correct the model work orders to include proper PMT instructions.
- 3.
Modify the fire protection deluge line to the AFU to provide additional protection against filter wetting.
F. PREVIOUS OCCURRENCES
No previous LERs or Issue Reports were identified at QCNPS address wetting or submergence of AFU filters. No similar ICES/IRIS events were found in the last 10 years.
G. COMPONENT FAILURE DATA
Failed Equipment: VALVE, AOV; 1" 600# S/N 80349 Component Manufacturer: BW/IP INTERNATIONAL, INC.
Component Model Number: 104DA6.001 Component Part Number: N/A This event has been reported to ICES/IRIS. Page _4_ of _4_