05000237/LER-2008-003, Regarding Control Room Emergency Ventilation Air Conditioning System Inoperable Due to Excessive Vibration
| ML082050233 | |
| Person / Time | |
|---|---|
| Site: | Dresden  |
| Issue date: | 06/23/2008 |
| From: | Wozniak D Exelon Generation Co, Exelon Nuclear |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| SVPLTR 08-0038 LER 08-003-00 | |
| Download: ML082050233 (4) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(v), Loss of Safety Function 10 CFR 50.73(a)(2)(i) 10 CFR 50.73(a)(2)(vii), Common Cause Inoperability 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)(iii) 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 |
| 2372008003R00 - NRC Website | |
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Exelon Generation Company, LLC www.exeloncorp.com NucleaT Dresden Nuclear Power Station 6500 North Dresden Road Morris, IL 60450-9765 10 CFR 50.73 SVPLTR # 08-0038 June 23, 2008 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Dresden Nuclear Power Station, Units 2 and 3 Renewed Facility Operating License Nos. DPR-19 and DPR-25 NRC Docket Nos. 50-237 and 50-249
Subject:
Licensee Event Report 237/2008-003-00, "Control Room Emergency Ventilation Air Conditioning System Inoperable Due To Excessive Vibration" Enclosed is Licensee Event Report 237/2008-003-00, "Units 2 and 3 Control Room Emergency Ventilation Air Conditioning System Inoperable Due To Excessive Vibration," for Dresden Nuclear Power Station, Units 2 and 3. This event is being reported in accordance with 10 CFR 50.73(a)(2)(v)(D), "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."
Should you have any questions concerning this report, please contact Mr. Bob Rybak, Acting Regulatory Assurance Manager, at (815) 416-2800.
Respectfully, David B. Wozniak Site Vice President Dresden Nuclear Power Station Enclosure cc:
Regional Administrator-NRC Region III NRC Senior Resident Inspector - Dresden Nuclear Power Station
/.+02..
NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 06/30/2007 (6-2004)
, the NRC may digits/characters for each block) not conduct or sponsor, and a person is not required to respond to, the informntinn nollec.tinn.
- 3. PAGE Dresden Nuclear Power Station, Unit 2 05000237 1 OF 3
- 4. TITLE Control Room Emergency Ventilation Air Conditioning System Inoperable Due To Excessive Vibration
- 5. EVENT DATE
- 6. LER NUMBER
- 7. REPORT DATE I
- 8. OTHER FACILITIES INVOLVED SEQUENTIAL REV FACILITY NAME DOCKET NUMBER MONTH DAY YEAR YEAR NUMBER NO.
MONTH DAY YEAR Dresden Unit 3 05000249 0FACILITY NAME DOCKET NUMBER 04 23 2008 2008 - 003 -
00 06 23 2008 N/A N/A
- 9. OPERATING MODE
- 11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR§: (Check all that apply)
El-20.2201(b)
El 20.2203(a)(3)(i)
El 50.73(a)(2)(i)(C) 0l 50.73(a)(2)(vii)
El 20.2201(d)
El 20.2203(a)(3)(ii)
El 50.73(a)(2)(ii)(A)
El 50.73(a)(2)(viii)(A)
El 20.2203(a)(1)
E] 20.2203(a)(4)
El 50.73(a)(2)(ii)(B)
El 50.73(a)(2)(viii)(B)
El 20.2203(a)(2)(i)
El 50.36(c)(1)(i)(A)
El 50.73(a)(2)(iii)
El 50.73(a)(2)(ix)(A)
- 10. POWER LEVEL El 20.2203(a)(2)(ii)
El 50.36(c)(1)(ii)(A)
[3 50.73(a)(2)(iv)(A)
El 50.73(a)(2)(x)
El 20.2203(a)(2)(iii)
El 50.36(c)(2)
El 50.73(a)(2)(v)(A)
El 73.71(a)(4)
El 20.2203(a)(2)(iv)
El 50.46(a)(3)(ii)
[E 50.73(a)(2)(v)(B)
El 73.71(a)(5) 100 El 20.2203(a)(2)(v)
[E 50.73(a)(2)(i)(A)
El 50.73(a)(2)(v)(C)
E] OTHER El 20.2203(a)(2)(vi)
E] 50.73(a)(2)(i)(B) 0 50.73(a)(2)(v)(D)
Specify in Abstract below or in (If more space is required, use additional copies of NRC Form 366A) (17) by refrigerant, which migrates back to the compressor during the off cycle and mixes with the oil. The liquid refrigerant acts like a solvent and washes the oil from the bearings. Based on the vendor's failure analysis and operating experience, the pistons farthest away from the oil pump to be most vulnerable. This was confirmed by the failed rods #11 and damaged rod #12, being the farthest away from the oil pump.
Although the cause could not be determined, the most likely cause is attributed to the combination of floodback and flooded starts.
D.
Safety Analysis
The Control Room Heating, Ventilation and Air Conditioning (HVAC) System is designed with two (2)
HVAC Systems. One system is a non-safety related "A" Train System with an air handling unit, 2/3-5731, a return air fan, 2/3-5728, and two (2) 50 percent RCUs. The second of the two HVAC systems is the safety related "B" Train HVAC System (i.e. CREVS) comprised of an air handling unit, 2/3-9400-100, an air filtration unit, 2/3-9400-101, and a RCU, 2/3-9400-102. This system is designed in accordance with General Design Criterion 19, "Control Room Habitability," to maintain the control room habitability in the event of a Design Basis Accident. The system is designed to maintain the Control Room between 70 and 80 degrees F.
The safety significance of the event is minimal. During this event, DNPS continued to operate within the requirements of the TS. The operability of the system was restore well within the completion time established the plant's technical specifications. Additionally, the CREVS during this event maintained the capability to isolate and pressurize the control room envelope in the event of a postulated radiological or toxic gas event. Therefore, the consequences of this event had minimal, impact on the health and safety of the public and reactor safety.
E.
Corrective Actions
The compressor was replaced and the system was successfully returned to service on May 1, 2008.
Engineering will verify performance of the system's thermal expansion valves and take additional actions, as appropriate.
Following the completion of the actions associated with the equipment apparent cause analysis, Plant Engineering will evaluate system operation to determine the effectiveness of the actions taken.
Based on this evaluation, if it is determined that system reliability has not been improved, further actions will be developed and implement, as appropriate.
F.
Previous Occurrences
A review of DNPS Licensee Event Reports (LERs) for the last three years identified LER 2006-005-00 which describes a freon leak that resulted in a CREVS inoperability.
G.
Component Failure Data
NA