05000249/LER-2008-001, Regarding Unit 3 Drywell Floor Drain Sump Monitoring System Declared Inoperable
| ML083030045 | |
| Person / Time | |
|---|---|
| Site: | Dresden  |
| Issue date: | 10/16/2008 |
| From: | Wozniak D Exelon Generation Co, Exelon Nuclear |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| SVPLTR #08-0054 LER 08-001-00 | |
| Download: ML083030045 (5) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications 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)(v), Loss of Safety Function |
| 2492008001R00 - NRC Website | |
text
Exelkn, Exelon Generation Company, LLC www.exeloncorp.com Nuclear Dresden Nuclear Power Station 6500 North Dresden Road Morris, IL 60450-9765 10 CFR 50.73 SVPLTR #08-0054 October 16, 2008 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Dresden Nuclear Power Station, Unit 3 Renewed Facility Operating License No. DPR-25 NRC Docket No. 50-249
Subject:
Licensee Event Report 249/2008-001-00, "Unit 3 Drywell Floor Drain Sump Monitoring System Declared Inoperable" Enclosed is Licensee Event Report 249/2008-001 -00, "Unit 3 Drywell Floor Drain Sump Monitoring System Declared Inoperable" for Dresden Nuclear Power Station, Unit 3. This event is being reported in accordance with 10 CFR 50.73(a)(2)(i)(B), "Any operation or condition which was prohibited by the plant's Technical Specifications." There are no regulatory commitments contained in this submittal.
Should you have any questions concerning this report, please contact Mr. Stephen Taylor, 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
NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 08/31/2010 (9-2007)
, the NRC may digits/characters for each block) not conduct or sponsor, and a person is not required to respond to, the information c~nllp.nction.
- 3. PAGE Dresden Nuclear Power Station, Unit 3 05000249 1 OF 4
- 4. TITLE Unit 3 Drywell Floor Drain Sump Monitoring System Declared Inoperable
- 5. EVENT DATE
- 6. LER NUMBER
- 7. REPORT DATE
- 8. OTHER FACILITIES INVOLVED SEQUENTIAL REV MFACILITY NAME DOCKET NUMBER MONTH DAY YEAR YEAR MONTH DAY YEAR N/A N/A l__
_ IFACILITY NAME DOCKET NUMBER 08 17 2008 2008 001 -
00 10 16 2008 N/A N/A
- 9. OPERATING MODE
- 11. THIS REPORT IS SUBMI'TED 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)
El 50.73(a)(2)(vii)
El 20.2201(d)
El 20.2203(a)(3)(ii) 0l 50.73(a)(2)(ii)(A)
El 50.73(a)(2)(viii)(A)
El 20.2203(a)(1)
El 20.2203(a)(4) 0l 50.73(a)(2)(ii)(B)
El 50.73(a)(2)(viii)(B)
E] 20.2203(a)(2)(i)
El 50.36(c)(1)(i)(A) 0l 50.73(a)(2)(iii)
El 50.73(a)(2)(ix)(A)
- 10. POWER LEVEL 0l 20.2203(a)(2)(ii)
El 50.36(c)(1)(ii)(A)
El 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) 100 El 20.2203(a)(2)(iv)
El 50.46(a)(3)(ii)
El 50.73(a)(2)(v)(B) 0l 73.71(a)(5)
[] 20.2203(a)(2)(v)
El 50.73(a)(2)(i)(A)
El 50.73(a)(2)(v)(C)
El OTHER El 20.2203(a)(2)(vi) 0 50.73(a)(2)(i)(B)
El 50.73(a)(2)(v)(D)
Specify in Abstract below or in submitted to the NRC on August 19, 2008, consistent with the guidelines provided in Regulatory Issue Summary 2005-01, "Changes to Notice of Enforcement Discretion (NOED) Process and Staff Guidance," and NRC Inspection Manual Part 9900, "Operations - Notices of Enforcement Discretion."
An emergency TS amendment request, "Request for Emergency License Amendment Regarding Drywell Floor Drain Sump Monitoring System," was submitted on August 18, 2008. The submittal requested the use of the Unit 3 drywell equipment drain sump monitoring system to satisfy the TS 3.4.5 requirements applicable to the Unit 3 drywell floor drain sump monitoring system until the drywell floor drain sump monitoring system is repaired during an outage of sufficient duration, but no later than the startup from D3R20. The NRC issued the amendment on August 22, 2008, within the allowed time period specified in the NOED.
This event is being reported in accordance with 10 CFR 50.73(a)(2)(i)(B), "Any operation or condition which was prohibited by the plant's Technical Specifications." The unidentified drywell leakage could not be measured for a period of time that exceeded the TS 3.4.4 Allowed Completion Time and drywell floor drain sump monitoring system was inoperable for a period of time that exceeded TS 3.4.5 Allowed Completion Time. DNPS, as a result of the emergency TS amendment, is currently in compliance with its TS.
C.
Cause of Event
The cause of the event is indeterminate until the drywell floor drain sump monitoring system can be examined during an outage of sufficient duration, but no later than the startup from D3R20.
The equipment in the flow path of the drywell floor drain sump monitoring system are (1) the drywell floor drain sump pumps [3A-2001-451 and 3B-2001-451], (2) the drywell floor drain sump pump discharge check valves [3-2001-101A and 3-2001-101B], (3) the drywell floor drain sump pump discharge manual isolation valves [3-2001-102A and 3-2001-102A] and (4) the drywell floor drain sump pumps AOV containment isolation valves [3-2001-105 and 3-2001-106]. The two pumps with their associated check and manual valves are in parallel and only one pump needs to function to pump down the sump. The two AOV's are in series and both must operate to pump down the sump.
Since both sump pumps operate independently and were run without successful flow, the likelihood of the cause being a failure of both of the pumps or pump associated valves at the same time is very low. Therefore, the location of the proposed flow blockage is down stream of where the two pump discharge lines tie together. The currently proposed Apparent Cause is a blockage of flow in the three-inch (3") line down stream of where the two pumps tie in together. This blockage may be attributed to some foreign material or either of the drywell floor drain sump pumps AOV containment isolation valves [3-2001-105 and 3-2001-106] separating at the process diaphragm to valve stem connection. In either case, the most likely location for this blockage is at the aforementioned valves, since the weir type design of the diaphragm valves can act as a dam for foreign material.
D.
Safety Analysis
The safety significance of the event is minimal. During this event, DNPS continued to operate within the requirements of the TS and the NRC granted NOED, which temporarily extended the Completion Times of TS 3.4.4 and TS 3.4.5. Additionally, the NRC granted an amendment to allow the use of the Unit 3 drywell equipment drain sump monitoring system to satisfy the TS 3.4.5 requirements applicable to the Unit 3 drywell floor drain sump monitoring system until the drywell floor drain sump monitoring system is repaired during an outage of sufficient duration, but no later than the startup from D3R20. Therefore, the consequences of this event had minimal impact on the health and safety of the public and reactor safety.
E.
Corrective Actions
DNPS verbally requested a NOED on August 17, 2008 at approximately 1030 hours0.0119 days <br />0.286 hours <br />0.0017 weeks <br />3.91915e-4 months <br /> (CDT). The NRC granted the NOED on August 17, 2008 at approximately 1200 hours0.0139 days <br />0.333 hours <br />0.00198 weeks <br />4.566e-4 months <br /> (CDT).
The written NOED request was submitted to the NRC on August 19, 2008, consistent with the guidelines provided in Regulatory Issue Summary 2005-01 and NRC Inspection Manual Part 9900.
An emergency license amendment request was submitted on August 18, 2008. The NRC issued the amendment on August 22, 2008, within the allowed time specified in the NOED.
The drywell floor drain sump monitoring system was reconfigured such that the drywell equipment drain sump monitoring system could be used to quantify unidentified drywell leakage.
The Unit 3 drywell floor drain sump monitoring system will be repaired during an outage of sufficient duration, but no later than the startup from D3R20.
F.
Previous Occurrences
A review of DNPS Licensee Event Reports (LERs) for the last three years did not identified any LERs associated with the drywell floor drain sump monitoring system.
G.
Component Failure Data
N/APRINTED ON RECYCLED PAPERPRINTED ON RECYCLED PAPER