05000289/LER-2011-001, Regarding Unanalyzed Condition Affecting Probable Maximum Flood (PMF) Level
| ML11326A282 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 11/20/2011 |
| From: | Chick G Exelon Generation Co, Exelon Nuclear |
| To: | Office of Nuclear Reactor Regulation, Document Control Desk |
| References | |
| TMI-11-161 LER 11-001-00 | |
| Download: ML11326A282 (4) | |
| 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)(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 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications 10 CFR 50.73(b)(2)(ii) |
| 2892011001R00 - NRC Website | |
text
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Nuclear Three Mile Island Unit 1 Route 441 South, P.O. Box 480 Middletown, PA 17057 Telephone 717-948-8000 November 20, 2011 TMI-11-161 10 CFR 50.73 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, D.C. 20555 THREE MILE ISLAND NUCLEAR STATION, UNIT 1 (TMI-1)
OPERATING LICENSE NO. DPR-50 DOCKET NO. 50-289 SUBJECT: LICENSEE EVENT REPORT (LER) NO. 2011-001-00 "Unanalyzed Condition Affecting Probable Maximum Flood (PMF) Level" This report is submitted in accordance with 10 CFR 50.73 (a)(2)(ii)(B). For additional information regarding this LER contact David Atherholt, Manager TMI Unit 1 Regulatory Assurance at (717) 948-8364.
There are no regulatory commitments contained in this LER.
Sincerely, Glen Earl Chick Site Vice President, Three Mile Island Unit 1 Exelon Generation Co., LLC GEC/mdf cc:
TMI Senior Resident Inspector Administrator, Region I TMI-1 Senior Project Manager JE~
NJ(~JL
NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 10/31/2013 (10-2010)
, the NRC may digits/characters for each block) not conduct or sponsor, and a person is not required to respond to, the information collection.
- 3. PAGE Three Mile Island, Unit 1 05000289
- 4. TITLE:
Unanalyzed Condition Affecting Probable Maximum Flood (PMF) Level
- 5. EVENT DATE
- 6. LER NUMBER__
- 7. REPORT DATE
- 8. OTHER FACILITIES INVOLVED MONTH DAY YEAR YEAR SEQUENTIAL REV MONTH DAY YE ACILITY NAME DOCKET NUMBER YEARINUMBER NO.
MONTH_
DAYYEARN/A 05000 FACILITY NAME DOCKET NUMBER 09 26 2011 2011 - 001 -
00 11 20 2011 N/A 05000
- 9. OPERATING MODE
- 11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR§: (Check all that apply)
El 20.2201(b)
Cl 20.2203(a)(3)(i)
[I 50.73(a)(2)(i)(C)
El 50.73(a)(2)(vii)
N E0 20.2201(d)
[E 20.2203(a)(3)(ii)
[I 50.73(a)(2)(ii)(A)
El 50.73(a)(2)(viii)(A)
El 20.2203(a)(1)
[I 20.2203(a)(4)
ED 50.73(a)(2)(ii)(B)
El 50.73(a)(2)(viii)(B)
El 20.2203(a)(2)(i)
[l 50.36(c)(1)(i)(A)
[I 50.73(a)(2)(iii)
[E 50.73(a)(2)(ix)(A)
- 10. POWER LEVEL L] 20.2203(a)(2)(ii)
[E 50.36(c)(1)(ii)(A)
[E 50.73(a)(2)(iv)(A)
El 50.73(a)(2)(x)
El 20.2203(a)(2)(iii)
[E 50.36(c)(2)
[3 50.73(a)(2)(v)(A)
El 73.71 (a)(4)
El 20.2203(a)(2)(iv) 0l 50.46(a)(3)(ii)
F-50.73(a)(2)(v)(B)
El 73.71(a)(5) 100 El 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)
El 50.73(a)(2)(i)(B)
El 50.73(a)(2)(v)(D)
Specify in Abstract below or in NRC Form 366A
- 12. LICENSEE CONTACT FOR THIS LER FACILITY NAME TELEPHONE NUMBER (Include Area Code)
David Atherholt, Manager TMI Unit 1 Regulatory Assurance (717) 948-8364MANU-REPORTABLE MANU-REPORTABLE
CAUSE
SYSTEM COMPONENT
CAUSE
SYSTEM COMPONENT FACURE R
EPOA FACTURER TO EPIX FACTURER TO EPIX D
N
- 14. SUPPLEMENTAL REPORT EXPECTED
- 15. EXPECTED MONTH IDAY IYEAR SUBMISSION [E YES (If yes, complete 15. EXPECTED SUBMISSION DATE)
[D NO DATE ABSTRACT (Limit to 1400 spaces, i.e., approximately 15 single-spaced typewritten lines)
On September 26, 2011, an analysis titled "River Stage Discharge and Discharge Frequency Analysis" was completed. The analysis predicts the water level at the TMI-1 Intake Structure Pump House (ISPH) at the peak flow during a Probable Maximum Flood (PMF) will be 4.3 feet higher than the previous analysis. The new analysis predicts a PMF water level at 313.3 feet at the ISPH. The flood barrier system currently protects TMI Unit I for river levels up to 313.5 feet elevation.
Because the original flood barrier system protected TMI Unit I for river levels up to 311 feet, if the PMF had occurred prior to September 2011, the event had the potential to adversely affect plant safety. No actual flooding occurred. The validity of the flood analysis had not been re-assessed due to the lack of a programmatic requirement to perform periodic re-assessments of the external flood hazard. A repetitive task will be instituted to periodically re-assess the external flood hazard.
NRC FORM 366 (10-2010)U.S. NUCLEAR REGULATORY COMMISSION (10-2010)
LICENSEE EVENT REPORT (LER)
- 1. FACILITY NAME
- 2. DOCKET
- 6. LER NUMBER
- 3. PAGE SEQUENTIAL REV YEAR NUMBER NO.
Three Mile Island, Unit 1 05000289 2011 001 00 2
of 3
A.
EVENT DESCRIPTION
Plant Conditions before the event:
Babcock & Wilcox - Pressurized Water Reactor - 2568 MWth Core Power Date/Time: September 26, 2011/1400 hours Power Level: 100% steady state power Mode: Power Operations There were no structures, systems, or components out of service that contributed to this event.
Event:
On September 26, 2011, an analysis titled "River Stage Discharge and Discharge Frequency Analysis" was completed. The analysis predicts the water level at the TMI-1 Intake Structure Pump House (ISPH) *[MD] at the peak flow during a Probable Maximum Flood (PMF) will be 4.3 feet higher than the previous analysis. The new analysis predicts a PMF water level at 313.3 feet at the ISPH.
The flood barrier system currently protects TMI Unit 1 for river levels up to 313.5 feet elevation.
Because the original flood barrier system protected TMI Unit 1 for river levels up to 311 feet, if the PMF had occurred prior to September 2011, the event had the potential to adversely affect plant safety.
No actual flooding occurred.
B.
CAUSE OF EVENT
The validity of the flood analysis had not been re-assessed due to the lack of a programmatic requirement to perform periodic re-assessments of the external flood hazard.
C.
ANALYSIS / SAFETY SIGNIFICANCE On September 26, 2011, the completion of a new analysis revealed that the PMF elevation had increased from 309 feet elevation to 313.3 feet elevation. Based on the updated analysis, the TMI Unit-1 flood protection systems did not satisfy the licensing commitment for flood protection, prior to a modification made to the flood barrier system in September 2011. This constituted an unanalyzed condition with the potential to exceed the PMF design basis and adversely impact plant safety.
Since no actual flooding occurred, this event did not adversely affect the health and safety of plant personnel or the general public.
D.
CORRECTIVE ACTIONS
The corrective action is to institute a repetitive task to periodically re-assess the external flood hazard.
'4
- - U.S. NUCLEAR REGULATORY COMMISSION (10-2010)
LICENSEE EVENT REPORT (LER)
- 1. FACILITY NAME
- 2. DOCKET
- 6. LER NUMBER
- 3. PAGE SEQUENTIAL I REV YEAR NUMBER NO.
Three Mile Island, Unit 1 05000289 2011 001 00 3
of 3
E.
PREVIOUS OCCURENCES
A review of previous reportable events within the last three years did not identify any events that directly translate to the TMI Unit 1 circumstance. No additional operating experience was found where the flood hazard had been re-analyzed and the results were unexpected, or where the lack of revised analysis was a recognized deficiency.
- Energy Industry Identification System (EIIS), System Identification (SI) and Component Function Identification (CFI) Codes are included in brackets, [SI/CFI] where applicable, as required by 10 CFR 50.73 (b)(2)(ii)(F).