05000483/LER-2010-004, Regarding Unanalyzed Single Failure Component for Ultimate Heat Sink/Essential Service Water
| ML101200537 | |
| Person / Time | |
|---|---|
| Site: | Callaway  |
| Issue date: | 04/30/2010 |
| From: | Neterer D AmerenUE, Union Electric Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| ULNRC-05701 LER 10-004-00 | |
| Download: ML101200537 (11) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(ii)(B), Unanalyzed Condition 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)(8) 10 CFR 50.73(a)(2)(viii)(8) 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)(8) 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)(8) |
| 4832010004R00 - NRC Website | |
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wAmeren UE AmerenUE Callaway Plant April 30, 2010 u.s. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555-0001 ULNRC-05701 PO Box 620 Fulton, MO 65251 10 CFR 50.73(a)(2)(ii)(B)
Ladies and Gentlemen:
DOCKET NUMBER 50-483 CALLAWAY PLANT UNIT 1 UNION ELECTRIC CO.
FACILITY OPERATING LICENSE NPF-30 LICENSEE EVENT REPORT 2010-004-00 UNANALYZED SINGLE FAILURE COMPONENT FOR ULTIMATE HEAT SINKIESSENTIAL SERVICE WATER The enclosed licensee event report is submitted in accordance with 10CFR50.73(a)(2)(ii)(B) in order to report a condition identified as one that resulted in the plant being in an unanalyzed condition that significantly degraded plant safety.
The condition involves the failure to consider and properly analyze a single-failure condition that may be assumed for the Ultimate Heat Sink Cooling Tower Bypass Valves.
This letter does not contain new commitments.
Sincerely,
~
David W. Neterer Plant Director EMF/nls Enclosure a subsidiary of Ameren Corporation
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wAmeren UE AmerenUE Callaway Plant April 30, 2010 u.s. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555-0001 ULNRC-05701 PO Box 620 Fulton, MO 65251 10 CFR 50.73(a)(2)(ii)(B)
Ladies and Gentlemen:
DOCKET NUMBER 50-483 CALLAWAY PLANT UNIT 1 UNION ELECTRIC CO.
FACILITY OPERATING LICENSE NPF-30 LICENSEE EVENT REPORT 2010-004-00 UNANALYZED SINGLE FAILURE COMPONENT FOR ULTIMATE HEAT SINKIESSENTIAL SERVICE WATER The enclosed licensee event report is submitted in accordance with 10CFR50.73(a)(2)(ii)(B) in order to report a condition identified as one that resulted in the plant being in an unanalyzed condition that significantly degraded plant safety.
The condition involves the failure to consider and properly analyze a single-failure condition that may be assumed for the Ultimate Heat Sink Cooling Tower Bypass Valves.
This letter does not contain new commitments.
Sincerely,
~
David W. Neterer Plant Director EMF/nls Enclosure a subsidiary of Ameren Corporation
ULNRC-05701 April 30, 2010 Page 2 cc:
Mr. Elmo E. Collins, Jr.
Regional Administrator U. S. Nuclear Regulatory Commission Region IV 612 E. Lamar Blvd., Suite 400 Arlington, TX 76011-4125 Senior Resident Inspector Callaway Resident Office U. S. Nuclear Regulatory Commission 8201 NRC Road Steedman, MO 65077 Mr. Mohan C. Thadani (2 copies)
Senior Project Manager, Callaway Plant Office ofNuc1ear Reactor Regulation U. S. Nuclear Regulatory Commission Mail Stop 0-8G 14 Washington, DC 20555-2738 ULNRC-05701 April 30, 2010 Page 2 cc:
Mr. Elmo E. Collins, Jr.
Regional Administrator U. S. Nuclear Regulatory Commission Region IV 612 E. Lamar Blvd., Suite 400 Arlington, TX 76011-4125 Senior Resident Inspector Callaway Resident Office U. S. Nuclear Regulatory Commission 8201 NRC Road Steedman, MO 65077 Mr. Mohan C. Thadani (2 copies)
Senior Project Manager, Callaway Plant Office ofNuc1ear Reactor Regulation U. S. Nuclear Regulatory Commission Mail Stop 0-8G 14 Washington, DC 20555-2738
ULNRC-05701 April 30, 2010 Page 3 Index and send hardcopy to QA File A160.0761 Hardcopy:
Certrec Corporation 4200 South Hulen, Suite 422 Fort Worth, TX 76109 (Certrec receives ALL attachments as long as they are non-safeguards and may be publicly disclosed.)
LEREvents@inpo.org (must send the WORD version ofthe LER to this address)
Electronic distribution for the following can be made via LER ULNRe Distribution:
A. C. Heflin F. M. Diya D. W. Neterer L. S. Sandbothe C. O. Reasoner ill S. A. Maglio S. L. Gallagher T. L. Woodward (NSRB)
T. B. Elwood E. M. Fast R. J. Andreasen D. E. Dumbacher (NRC)
B. A. Brook (WCNOC)
Ms. Diane M. Hooper (WCNOC)
Mr. Dennis Buschbaum (Luminant Power)
Mr. Ron Barnes (APS)
Mr. Tom Baldwin (pG&E)
Mr. Wayne Harrison (STPNOC)
Mr. John O'Neill (pillsbury Winthrop Shaw Pittman LLP)
Missouri Public Service Commission Records Center (INPO)
ULNRC-05701 April 30, 2010 Page 3 Index and send hardcopy to QA File A160.0761 Hardcopy:
Certrec Corporation 4200 South Hulen, Suite 422 Fort Worth, TX 76109 (Certrec receives ALL attachments as long as they are non-safeguards and may be publicly disclosed.)
LEREvents@inpo.org (must send the WORD version ofthe LER to this address)
Electronic distribution for the following can be made via LER ULNRe Distribution:
A. C. Heflin F. M. Diya D. W. Neterer L. S. Sandbothe C. O. Reasoner ill S. A. Maglio S. L. Gallagher T. L. Woodward (NSRB)
T. B. Elwood E. M. Fast R. J. Andreasen D. E. Dumbacher (NRC)
B. A. Brook (WCNOC)
Ms. Diane M. Hooper (WCNOC)
Mr. Dennis Buschbaum (Luminant Power)
Mr. Ron Barnes (APS)
Mr. Tom Baldwin (pG&E)
Mr. Wayne Harrison (STPNOC)
Mr. John O'Neill (pillsbury Winthrop Shaw Pittman LLP)
Missouri Public Service Commission Records Center (INPO)
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 collection.
- 13. PAGE Callaway Plant Unit 1 05000483 1 OF 8
- 4. TITLE Unanalyzed Single Failure Component for Ultimate Heat Sink/Essential Service Water
- 5. EVENT DATE
- 6. LER NUMBER
- 7. REPORT DATE
- 8. OTHER FACILITIES INVOLVED SEQUENTIAL REV FACILITY NAME DOCKET NUMBER MONTH DAY YEAR YEAR NUMBER NO.
MONTH DAY YEAR FACILITY NAME DOCKET NUMBER 3
2 2010 2010 - 004 -
00 4
30 2010
- 9. OPERATING MODE
- 11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR§: (Check all that apply) o 20.2201(b) o 20.2203(a)(3)(i) o 50.73(a)(2)(i)(C) o 50.73(a)(2)(vii) 1 o 20.2201 (d) o 20.2203(a)(3)(ii) o 50.73(a)(2)(ii)(A) o 50.73(a)(2)(viii)(A) o 20.2203(a)(1) o 20.2203(a)(4)
~ 50.73(a)(2)(ii)(8) o 50.73(a)(2)(viii)(8) o 20.2203(a)(2)(i) o 50.36(c)(1 )(i)(A) o 50.73(a)(2)(iii) o 50.73(a)(2)(ix)(A)
- 10. POWER LEVEL o 20.2203(a)(2)(ii) o 50.36(c)(1 )(ii)(A) o 50.73(a)(2)(iv)(A) o 50.73(a)(2)(x) o 20.2203(a)(2)(iii) o 50.36(c)(2) o 50.73(a)(2)(v)(A) o 73.71(a)(4) 100 o 20.2203(a)(2)(iv) o 50.46(a)(3)(ii) o 50.73(a)(2)(v)(8) o 73.71 (a)(5) o 20.2203(a)(2)(v) o 50.73(a)(2)(i)(A) o 50.73(a)(2)(v)(C) o OTHER o 20.2203(a)(2)(vi) o 50.73(a)(2)(i)(8) o 50.73(a)(2)(v)(O)
Specify in Abstract below or in
- 1.
LICENSEE EVENT REPORT (LER)
- 1. FACILITY NAME
- 2. DOCKET
- 6. LER NUMBER
- 3. PAGE I SEQUENTIAL I REVISION Callaway Plant Unit 1 YEAR NUMBER NUMBER 05000483 2010 004 00 2
OF
INITIAL PLANT CONDITIONS
The plant was in MODE 1, Power Operation, at 100% reactor power when the subject condition was discovered. No structures, systems, or components were inoperable at the time of discovery that contributed to this event.
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- 2.
EVENT DESCRIPTION
On March 2, 2010, a question pertaining to the design of the essential service water (ESW) system [EllS system: BI] and associated ultimate heat sink (UHS) [EllS system: BS] at Callaway, with respect to conformance to 1 OCFR50 Appendix A General Design Criteria (GDC) 44, was identified. GDC 44 states that a system transferring heat from structures, systems, or components (SSCs) to the UHS shall be provided and function under normal and accident conditions. Suitable redundancy and isolation capabilities of this system shall be provided such that the safety functions can be accomplished, assuming a single failure.
Specifically, based on a review of the UHS thermal performance analysis calculation, it was questioned whether a particular single active component failure should have been considered for the UHS cooling tower bypass valves [EllS system: BS, component: HCV], and if so whether or not UHS calculations bound this single failure scenario. Further review of the UHS calculations determined that the most limiting single active failure with respect to the thermal capacity of the UHS, i.e., the failure of a UHS cooling tower bypass valve, had not been identified or evaluated. This condition was entered into Callaway's Corrective Action Program as CAR 201001813.
The UHS consists of a seismic Category I mechanical draft cooling tower [EllS system: BS, component:
CTW] and a seismic Category I source of makeup water (retention pond [EllS system: BS, component:
RVR]) for the tower. The UHS cooling tower provides heat dissipation from the ESW system for safe shutdown of the unit following an accident. The UHS cooling tower is divided into four cells with one fan [EllS system: BS, component: FAN] assembly (fan, gear reducer [EllS system: BS, component: RGR],
and motor [EllS system: BS, component: MO]) per cell. Two of the four cells (one train of the ESW) are required for safe shutdown. Supply headers and spray pipes [EllS system: BI, component: PSP] for each train of ESW from the power block are separated by interior walls. Freeze protection of the UHS cooling tower fill (cross-pack corrugated asbestos cement board that increases the surface area of the water flowing through it in order to maximize heat transfer) is provided by automatic bypass of the spray system.
With the UHS cooling tower bypass valves (EFHV0065 for Train 'A' and EFHV0066 for Train 'B') open, ESW from the power block is diverted directly into the cooling tower basin [EllS system: BS, component:
RVR], thus bypassing the UHS cooling tower.
When the ESW system is put into operation, water is drawn from the UHS retention pond by means of the ESW pumps. It is then pumped through the power block components and returned to the UHS cooling tower basin. As noted above, ESW discharge water from the power block is directed into the UHS cooling tower basin through a normally open UHS spray system bypass valve (in each train). The UHS bypass valves will automatically close when discharge water temperature is at or above 91 degrees Fahrenheit in order to direct water through the UHS cooling tower fill. As described in the Callaway Final Safety Analysis Report (FSAR), operator action may be necessary to maintain UHS pond temperature within allowable limits by defeating the automatic bypass of the UHS spray system and manually closing the UHS bypass valve in order to send return water over the fill. This allows UHS pond cooling and performance monitoring during plant operation when freezing in the tower is not a concern.
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Component: BK, Containment Fan Cooling System (PWR)
HX, Exchanger, Heat BS, Ultimate Heat Sink System BKR, Breaker CTW, Cooling Tower FAN, Fan HCV, Valve, Control, Hand MO, Motor RGR, Gear, Reduction RVR, Reservoir CB, Chemical and Volume Control/Makeup and Purification System (PWR)
TK, Tank CC, Closed/Component Cooling Water System HX, Exchanger, Heat ED, Low-Voltage Power System - Class IE BU, Bus EK, Emergency Onsite Power Supply System DG, Generator, Diesel KA, Condensate Storage and Transfer System TK, Tank NA, Control Building/Control Complex ANN, Annunciator MCBD, Control Board (Main)
NO, Fuel Building NN, Circulating Water Structures CTW, Cooling Tower VI, Control Building/Control Complex Environmental Control System FAN, Fan
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