05000317/LER-2018-003-01, Control Room Loss of Ventilation Due to Smoke Detector Failure Causing Common Supply Damper to Shut
| ML18283A306 | |
| Person / Time | |
|---|---|
| Site: | Calvert Cliffs  |
| Issue date: | 10/08/2018 |
| From: | Tierney T Exelon Generation Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| LER 2018-003-01 | |
| Download: ML18283A306 (5) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2) 10 CFR 50.73(a)(2)(viii)(B) 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)(i)(A), Completion of TS Shutdown 10 CFR 50.73(a)(2)(v), Loss of Safety Function 10 CFR 50.73(a)(2)(i) |
| 3172018003R01 - NRC Website | |
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~ e Exelon Generation@
October 8, 2018 U.S. Nuclear Regulatory Commission ATIN: Document Control Desk Washington, DC 20555 Calvert Cliffs Nuclear Power Plant, Units No. 1 and 2 Todd A. Tierney Plant Manager Calvert Cliffs Nuclear Power Plant 1650 Calvert Cliffs Parkway Lusby, MD 20657 410 495 5205 Office 484-459-0142 Mobile www.exeloncorp.com todd.tierney@exeloncorp.com 10 CFR 50.73 Renewed Facility Operating License Nos. DPR-53 and DPR-69 NRC Docket Nos. 50-317 and 50-318
Subject:
Licensee Event Report 2018-003, Revision 01 Control Room Loss of Ventilation due to Smoke Detector Failure Causing Common Supply Damper to Shut The attached report is being sent to you as required by 10 CFR 50.73.
There are no regulatory commitments contained in this correspondence.
Should you have questions. regarding this report, please contact Mr'. Larry D. Smith at (410) 495-5219.
I Respectfully,
~a_,~A.A/
Todd A. Tierney
- /
Plant Manager TAT/PSF/bjm
Attachment:
As stated cc:
NRC Project Manager, Calvert Cliffs NRC Regional Administrator, Region I I
NRC Resident Inspector, Calvert Cliffs D. A. Tancabel, DNR
NRC FORM 366 (04-2018)
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- 1. Facility Name Calvert Cliffs Nuclear Power Plant, Unit 1
- 4. Title
- 2. Docket Number 05000317 3.Page 1
OF 4
Control Room Loss of Ventilation Due to Smoke Detector Failure Causing Common Supply Damper to Shut
- 5. Event Date
- 6. LEA Number
- 7. Report Date
- 8. Other Facilities Involved I
Sequential I Rev Facility Name Docket Number Month Day Vear Vear Number No.
Month Day Vear Calvert Cliffs Nuclear Power Plant Unit 2 05000 318 Facility Name Docket Number 07 07 2018 2018 - 003 01 10 08 2018 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)(iil(A)
D 50.73(a)(2)(viiil(A)
D 20.2201(d)
D 20.22os(a)(3)(ii)
D 50.73(al(2)(ii)(B)
D 50.73(a)(2)(viii)(B)
D 20.22os(a)(1)
D 20.22os(al(4)
D 50.1s(al(2l(m)
D 50.73(al(2l(ix)(A)
D 20.22os(al(2)(i)
D 50.36(c)(1 )(i)(A)
D 50.73(a)(2l(iv)(A)
D 50.73(a)(2)(x)
- 10. Power Level D 20.22os(al(2)(ii)
D 50.36(c)(1)(iil(A)
D 50.73(a)(2)(v)(A)
D 1s.71(a)(4)
D 20.22os(a)(2l(m)
I D 50.s6(c)(2J I'
D 50.73(al(2)(v)(B)
D 20.2203(a)(2)(iv)
D so.46(a)(3)(ii)
D 50.73(a)(2l(vl(C)
D 1s.11(a)(1) 100 D 20.2203(a)(2)(v)
D 50.73(a)(2)(i)(A)
~ 50.73(a)(2)(v)(D)
D 1s.11(a)(2)(i)
D 20.2203(a)(2)(vi)
D 50.73(al(2)(i)(B)
~ 50.73(al(2)(vii)
D 73.77(al(2)(ii)
,~ :
D 50.73(a)(2)(i)(C)
D Other (Specify in Abstract below or in The CREVS and CRETS are a two-train system that serves the common Unit 1 and Unit 2 Control Room. The CREVS is an emergency system that provides automatic airborne radiological, smoke and toxic gas protection for Control Room occupants. The CRETS is an emergency system that provides adequate cooling to maintain equipment in the Control Room operable. The CREVS and CRETS systems share the same ductwork. In the shared ductwork, the supply damper is a single damper that controls flow to both trains. Failure of that single damper renders both trains inoperable due to lack of ventilation flow.
This condition was entered into the corrective action program and the NRC was notified via Event Notification 53493 on July 7, 2018.
C.
CAUSE OF EVENT
This event is 1'documented in the site's Corrective Action Program unc:!er IR 4153797. Field troubleshooting isolated the cause of failure to Control Room ventilation smoke detector (OAE5347). The smoke detector functions to shut the Control Room ventilation supply damper by energizing the associated solenoid valve (O-SV-5342). The associated solenoid valve was observed in the energized state via thermography. The solenoid valve is normally de-energized to
- maintain the damper open.
The apparent cause of the smoke detector failure is that no preventive maintenance activity existed to inspect and clean the Control Room ventilation smoke detector to 1prevent dust and dirt accumulatio1 settling on the smoke detector head.
D.
SAFETY ANALYSIS
The actual consequence resulting from this identified event was the loss of all Control Room ventilation circulation for a ?-minute period of time. During this short loss of ventilation, the Control Room. remained habitable and the temperature remained within operability limits for the equipment in the Control Room. If an event occurred during a loss of ventilation, resulting in a radioactive or toxic gas release, self-contained breathing apparatus is available in the Control Room for the operations staff to support their response to the event. Operations staff are qualified and trained on the use of the self-contained breathing apparatus during plant events. Additionally, the Units were previously analyzed for a loss of Control Room ventilation for an extended period (4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />) as part of the re;,ponse to 1 O CFR 50.63, Station Blackout. That analysis determined that the equipment cduld withstand the loss of ventilation for the extended pJriod of time and still perform its functions.
The probabilistic risk assessment analysis determined that the estimated increase in core damage frequency was less than 1 E-07 and the estimated increase in large early release frequency was less than 1 E-08 per year for the subject condition. The PRA analysis conservatively assumed elevated temperature in the CR due to failure of the CR HVAC damper and that assumed temperature increase would not have a significant impact on plant risk. This issue would be "GREEN" using the NRC's Significance Determination Process.
01 E.
CORRECTIVE ACTIONS
Immediate corrective action was taken to re-open the Control Room supply damper by manually isolating air to the solenoid valve and removing air pressure to return the Control Room supply damper to an open condition.
An additional short-term corrective action was to replace the smoke detector head inside detector assembly. The long-term corrective action is to implement a preventative maintenance activity to clean the Control Room ventilation smoke detectors every ten years per INPO guidance and vendor technical manual guidance.
F.
PREVIOUS OCCURRENCES
No previous similar events have occurred at the site within the last 5 years.
G.
COMPONENT FAILURE DATA
Control Room ventilation smoke detector.
REV NO.
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