05000461/LER-2007-001, Regarding Inadequate Consideration of Vortexing in Design Calculations
ML071070294 | |
Person / Time | |
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Site: | Clinton ![]() |
Issue date: | 04/06/2007 |
From: | Bryan Hanson AmerGen Energy Co |
To: | Document Control Desk, Plant Licensing Branch III-2 |
References | |
U-603811 LER 07-001-00 | |
Download: ML071070294 (4) | |
Event date: | |
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Report date: | |
Reporting criterion: | 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 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications |
4612007001R00 - NRC Website | |
text
AmerO aM An Exelon Company Clinton Power Station R. R. 3, Box 228 Clinton, IL 61727 10 CFR 50.73 U-603811 April 6, 2007 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D. C. 20555-0001 Clinton Power Station, Unit 1 Facility Operating License No. NPF-62 NRC Docket No. 50-461
Subject:
Licensee Event Report 2007-001 -00 Enclosed is Licensee Event Report (LER) No. 2007-001 -00: Inadequate Consideration of Vortexing in Design Calculations. This report is being submitted in accordance with the requirements of 10CFR50.73.
This letter contains no regulatory commitments.
Should you have any questions concerning this report, please contact Mr. Kent Scott, Regulatory Assurance Manager, at (217)-937-2800.
Respectfully, Bryan Hanson Site Vice President Clinton Power Station JLP/blf
Enclosure:
Licensee Event Report 2007-001 -00 cc:
Regional Administrator - NRC Region Ill.
NRC Senior Resident Inspector - Clinton Power Station Office of Nuclear Facility Safety - IEMA Division of Nuclear Safety
NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 06/30/2007 (6-2004)
, the NRC may not conduct or sponsor, and a person is not required to respond to, the digits/characters for each block)
I_____________________________________
- 3. PAGE Clinton Power Station 05000461 1 OF 3
- 4. TITLE Inadequate Consideration of Vortexing in Design Calculations
- 5. EVENT DATE
- 6. LER NUMBER
- 7. REPORT DATE
- 8. OTHER FACILITIES INVOLVED M T A YSEQUENTIAL REV M
D Y
FACILITY NAME DOCKET NUMBER MONTH DAY YEAR YEAR NUMBER REV MONTH DAY YEAR None 05000 FACILITY NAME DOCKET NUMBER 02 07 2007 2007 - 001 -
00 04 06 2007 None 05000
- 9. OPERATING MODE
- 11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR§: (Check all that apply)
[1 20.2201(b)
El 20.2203(a)(3)(i)
El 50.73(a)(2)(i)(C)
El 50.73(a)(2)(vii)
[1 20.2201(d)
C3 20.2203(a)(3)(ii)
El 50.73(a)(2)(ii)(A)
[I 50.73(a)(2)(viii)(A)
El 20.2203(a)(1)
[I 20.2203(a)(4)
El 50.73(a)(2)(ii)(B)
[I 50.73(a)(2)(viii)(B) 20.2203(a)(2)(i)
El 50.36(c)(1)(i)(A)
El 50.73(a)(2)(iii)
[I 50.73(a)(2)(ix)(A)
- 10. POWER LEVEL El 20.2203(a)(2)(ii)
[- 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)
[I 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)
[I 50.73(a)(2)(v)(B)
[1 73.71(a)(5) 95.5 El 20.2203(a)(2)(v)
El 50.73(a)(2)(i)(A)
El 50.73(a)(2)(v)(C)
El OTHER (10 CFR 21)
El 20.2203(a)(2)(vi)
El 50.73(a)(2)(i)(B)
ED 50.73(a)(2)(v)(D)
Specify in Abstract below nr in NRC Fnrm 3R6A
- 12. LICENSEE CONTACT FOR THIS LER NAME TELEPHONE NUMBER (Include Area Code)
Russell Peak, Engineering Director (217) 937-3800CAUSE SYSTEM COMPONENT MANU-REPORTABLE
CAUSE
SYSTEM COMPONENT MANU-REPORTABLE FACTURER TO EPIX II FACTURER TO EPIX
- 14. SUPPLEMENTAL REPORT EXPECTED
- 15. EXPECTED MONTH DAY YEAR SUBMISSION El1 YES (If yes, complete 15. EXPECTED SUBMISSION DATE) 0 NO DATE ABSTRACT (Limit to 1400 spaces, i.e., approximately 15 single-spaced typewritten lines)
On February 7, 2007, the Nuclear Regulatory Commission (NRC) issued a White Finding and Notice of Violation, for failure to select an appropriate method for calculating the minimum elevation (i.e., the analytical level) of water above the high pressure core spray (HPCS) pump suction line to preclude vortex formation and subsequent air entrainment in the pump's suction. The finding identified that prior to August 12, 2006, the initiation of suction transfer from the reactor core isolation cooling (RCIC) water storage tank to the suppression pool, as derived by calculation, may not prevent significant air entrainment in the suction of the HPCS pump and subsequent loss of function of the HPCS pump. As a result, the analytical level could have resulted in significant air entrainment potentially causing the HPCS system to be incapable of completing its safety function. A root cause evaluation determined that the cause of this event was the failure to adequately evaluate the uncertainties and associated margins in the calculation used to determine the suction transfer point. Corrective action for this event includes installation of a plant modification to increase the submergence of the suction piping in the RCIC water storage tank to preclude possible vortex formation and air entrainment. This modification was installed August 12, 2006.
NRC FORM 366 (6-2004)
PRINTED ON RECYCLED PAPER NRC FORM 366 (6-2004)
PRINTED ON RECYCLED PAPER (If more space is required, use additional copies of (If more space is required, use additional copies of NRC Form 366A) (17)
CAUSE OF EVENT
A root cause evaluation determined that the cause of the event was the failure to adequately evaluate the uncertainties and associated margins in the calculation used to determine the suction transfer point.
CORRECTIVE ACTION
In December 2005, when it was determined that the margin was low to preclude vortexing with the configuration that existed with the suction source for the HPCS system aligned to the RCIC storage tank, the suction was transferred from the RCIC storage tank to the suppression pool. A plant modification was installed in August 2006 to increase the submergence of the suction piping in the RCIC water storage tank to preclude possible vortex formation and air entrainment.
The following additional corrective actions were identified:
- 1.
Design basis documents for the HPCS system will be updated to include the need to analyze vortexing for the tank low-level setpoint;
- 2.
The calculation developed for the plant modification to increase the submergence of the HPCS piping will be revised to document the uncertainty with respect to margin with regard to vortexing and air entrainment;
- 3.
A sampling of design basis calculations will be reviewed for extent of condition;
- 4.
Other safety-related tank vortex calculations will be reviewed, evaluated and revised as necessary;
- and,
- 5.
Configuration control procedures (CC-AA-309, "Control of Design Analyses" and CC-AA-309-101, "Engineering Standard Use and Adherence") will be revised to ensure that quantification of uncertainties associated with the methodologies is performed for safety-significant functions, or justified for non-safety significant functions, and available margin is evaluated against the determined uncertainty.
PREVIOUS SIMILAR EVENTS
None.
COMPONENT FAILURE DATA
None.
PJHIUF M 366A (1-200)I