05000482/LER-2001-001, Regarding Potential Submergence of Safety-Related Equipment Due to an Inadequate Flooding Calculation
| ML020350446 | |
| Person / Time | |
|---|---|
| Site: | Wolf Creek  |
| Issue date: | 01/14/2002 |
| From: | Muench R Wolf Creek |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| ET 02-0005 LER 01-001-00 | |
| Download: ML020350446 (7) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(v), Loss of Safety Function 10 CFR 50.73(a)(2)(ii)(B), Unanalyzed Condition 10 CFR 50.73(a)(2)(ix)(A) 10 CFR 50.73(a)(2)(iii) 10 CFR 50.73(a)(2)(x) 10 CFR 50.73(a)(2)(iv)(A), System Actuation 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)(viii)(A) 10 CFR 50.73(a)(2)(ii)(A), Seriously Degraded 10 CFR 50.73(a)(2)(viii)(B) |
| 4822001001R00 - NRC Website | |
text
WELF CREEK
'NUCLEAR OPERATING CORPORATION R. A. Muench Vice President Technical Services JAN 1 4 2002 ET 02-0005 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555
Subject:
Docket No. 50-482: Licensee Event Report 2001-001-00 Gentlemen:
The enclosed Licensee Event Report (LER) 2001-001-00 is being submitted, pursuant to 10 CFR 50.73(a)(2)(v), to identify a potential condition that could have resulted in the failure of equipment to adequately perform its safety function.
Commitments made by Wolf Creek Nuclear Operating Corporation in the enclosed LER are identified in the Attachment.
If you should have any questions regarding this submittal, please contact me at (620) 364-4034, or Mr. Tony Harris at (620) 364-4038.
Very truly yours, Rica Muench RAM/ CLS Enclosure Attachment cc:
J. N. Donohew (NRC), wie; wia W. D. Johnson (NRC), w/e; w/a E. W. Merschoff (NRC), w/e; w/a Senior Resident Inspector (NRC), w/e; wla PO. Box 411 / Burlington, KS 66839/ Phone: (620) 364-8831 An Equal Opportunity Employer M/F/HCNET
Attachment to ET 02-0005 Page 1 of 1 LIST OF COMMITMENTS The following table identifies those actions committed to by Wolf Creek Nuclear Operating Corporation (WCNOC) in this document.
Any other statements in this submittal are provided for information purposes and are not considered to be
commitments
Please direct questions regarding these commitments to Mr. Tony Harris, Manager Regulatory Affairs at Wolf Creek Generating Station, (620) 364-4038.
COMMITMENT
Due Date/Event A long-term resolution of this issue (which will include revision to 9/27/2002 the flooding calculation, and may include throttling the CST isolation valve) will be completed on or before September 27, 2002. The interim action of locking the valve in the throttled position will remain in place until long-term resolution of this condition is implemented.
NRC-FORM 366 U.S. NUCLEAR REGULATORY APPROVED BY OMB NO. 3150-0104 EXPIRES 7-31-2004 (7-2001)
COMMISSION
, the NRC may not digits/characters or each block) conduct or sponsor, and a person is not required to respond to, the information collection.
- 3. PAGE WOLF CREEK GENERATING STATION 05000 482 1 OF 5
- 4. TITLE Potential Submergence Of Safety-Related Equi )ment Due To an Inadequate Flooding Calculation.
- 5. EVENT DATE
- 6. LER NUMBER
- 7. REPORT DATE
- 8. OTHER FACILITIES INVOLVED REV FACILITY NAME DOCKET NUMBER MO DAY YEAR YEAR NUMBER NO MO DAY YEAR FACILITY NAME DOCKET NUMBER 11 16 2001 2001 -- 001
-- 00
- 9. OPERATING ITWIR RPA=('RTI'qiirtmiTTFflnpiiR-qiIA TAnTWRRPFOIIIRFUL~-MTqO n ClnFR-f(hkJt~-,
MODE 1
20.2201 (b) 20.2203(a)(3)(ii) 50.73(a)(2)(ii)(B) 50.73(a)(2)(ix)(A) 10 POWER 20.2201 (d) 20.2203(a)(4) 50.73(a)(2)(iii) 50.73(a)(2)(x)
LEVEL 100 20.2203(a)(1)
= 50.36(c)(1)(i)(A) 50.73(a)(2)(iv)(A) 73.71 (a)(4)
S 20 2203(a)(2)(i) 50.36(c)(1)(ii)(A) 50.73(a)(2)(v)(A) 73.71 (a)(5) 20.2203(a)(2)(ii)
__50.36(c)(2)
X 50.73(a)(2)(v)(B)
OTHER 20 2203(aX 2)(iii) 50.46(a)(3)(ii) 50.73(a)(2)(v)(C)
SpeC Foryn 366Ab illl;-20.2203(a)(2)(iv) 50.73(a)(2)(i)(A) 50.73(a)(2)(v)(D) 20.2203(a)(2)(vi) 50.73(aX2)(i)(C) 50.73(a)(2)(viii)(A) 20.2203(a)(3)(i) 50.73(a)(2)(ii)(A) 50.73(a)(2)(viii)(B)
- 12. LICENSEE CONTACT FOR THIS LER NAME [TELEPHONE NUMBER (Include Area Code)
Karl A. (Tony) Harris, Manager Regulatory Affairs (620) 364-4038MANU-REPORTABLE MANU-REPORTABLE
CAUSE
SYSTEM COMPONENT FACTURER TO EPIX
CAUSE
l SYSTEM COMPONENT FACTURER TO EPIX
- 14. SUPPLEMENTAL REPORT EXPECTED
- 15. EXPECTED MONTH DAY YEAR EXPECTED I
SUBMISSION YES (if yes, complete EXPECTED SUBMISSION DATE)
I X INO DATE
ABSTRACT
On November 16, 2001, Wolf Creek Nuclear Operating Corporation (WCNOC) personnel identified an error in an internal flood calculation. The calculation under estimated the input flow rate from a pipe break in two Auxiliary Building rooms and over estimated the drain flow rate from these rooms. As a result of correcting these values in the calculation, the calculation results now predict a flood water level that would submerge safety-related equipment required to switch the suction of the Auxiliary Feedwater (AFW) pumps from the Condensate Storage Tank (CST) to the Essential Service Water (ESW) system. Evaluations of event scenarios indicate that flooding of safety-related AFW equipment could occur and/or the decay heat removal function of AFW would not be accomplished.
The isolation valve for this line has been throttled, thus reducing the input flow rate and the resultant flood water level to ensure components required to fulfill the AFW system safety function are not submerged.
The cause for including these incorrect assumptions in this calculation is indeterminate due to the historical nature of this condition (the calculation was performed by an Architect/Engineer's staff in 1986). Based on a sampling review of other calculations, this issue is believed to be an isolated case.
This condition is considered to be of minimal safety significance.
NRC FORM 366 (7-2001)
(if more space is required, use additional copies of (If more space is required, use additional copies of (if more space is required, use additional copies of (If more space is required, use additional copies of NRC Form 366A) reduced through the suction to the AFW pumps and through the failed CST to condenser hotwell make-up line. During this time, the flood water level in rooms 1206 and 1207 would submerge the suction pressure transmitters needed to provide automatic switching from the CST to the ESW system. After CST level decreases below the level of the hotwell make-up line, the floor drains in rooms 1206 and 1207 would remove the water to a level that will allow plant operators to perform manual switching the suction of the AFW pumps from the CST to the ESW system. However, these operator actions are not credited in the design bases. In the absence of these actions, there would be insufficient water in the CST to fulfill the AFW safety function during cool down to entry into Residual Heat Removal (RHR) cooling.
Should the initiating event occur with the CST at the high end of the normal operating band, sufficient water would be available to provide cool down to RHR entry conditions without switching suction of the AFW system to the ESW system. In this case, the safety function of the AFW system would not be lost.
A review was performed to ensure that the resultant flood water level in Auxiliary Building rooms 1206 and 1207 of seven (7) feet would not adversely impact the function of the structure. Based on the weight of the maximum volume of water, WCNOC has concluded, based on engineering judgment, that the resultant flooding would not cause the structural failure of floors or walls.
Previous Occurrences
A review of Licensee Event Reports (LERs) associated with calculation errors from 1996 though this event date was performed. No relevant LERs were identified.