05000389/LER-2011-001, Regarding Inadvertent Crosstie of Component Cooling Water (CCW) to Control Room A/C Units
| ML110390523 | |
| Person / Time | |
|---|---|
| Site: | Saint Lucie  |
| Issue date: | 01/29/2011 |
| From: | Richard Anderson Florida Power & Light Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| L-2011034 LER 11-001-00 | |
| Download: ML110390523 (6) | |
| Event date: | |
|---|---|
| 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 10 CFR 50.73(a)(2) |
| 3892011001R00 - NRC Website | |
text
0 FPL Florida Power & Light Company, 6501 S. Ocean Drive, Jensen Beach, FL 34957 January 29, 2011 L-2011-034 10 CFR 50.73 U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, D.C. 20555 Re:
St. Lucie Unit 2 Docket No. 50-389 Reportable Event: 2011-001 Date of Event: December 2, 2010 Inadvertent Crosstie of Component Cooling Water (CCW) to Control Room Air Conditioning (A/C) Units The attached Licensee Event Report 2011-001 is being submitted pursuant to the requirements of 10 CFR 50.73 to provide notification of the subject event.
Very truly yours, Richard L. Anderson Site Vice President St. Lucie Plant RLA/dlc Attachment an FPL Group company
NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 10/31/2013 (10-2010)
Estimated burden per response to comply with this mandatory collection request: 80 hours9.259259e-4 days <br />0.0222 hours <br />1.322751e-4 weeks <br />3.044e-5 months <br />. Reported lessons learned are incorporated into the licensing process and fed back to industry. Send comments regarding burden estimate to the FOIA/Privacy Section (T-5 F53), U.S. Nuclear LICENSEE EVENT REPORT (LER)
Regulatory Commission, Washington, DC 20555-0001, or by internet e-mail to infocollects.resourse@nrc.gov, and to the Desk Officer, Office of Information and Regulatory Affairs, NEOB-10202, (3150-0104), Office of Management and Budget, Washington, DC 20503. If a means used to impose an information collection does not display a currently valid OMB control number, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.
3 PAGE St. Lucie Unit 2 05000389
]
1 OF 5
- 4. TITLE Inadvertent Crosstie of Component Cooling Water (CCW) to Control Room A/C Units
- 5. EVENT DATE
- 6. LER NUMBER
- 7. REPORT DATE
- 8. OTHER FACILITIES INVOLVED MONTH DAY YEAR YEAR ISEQUENTIAL I REV MONTH DAY YEAR FACILITY NAME DOCKET NUMBER I_ I I
_FACILITY NAME DOCKET NUMBER 12 02 2010 2011 -
001 00 01 29 2011
- 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)
[I 50.73(a)(2)(i)(C)
El 50.73(a)(2)(vii)
[1E 20.2201(d)
El 20.2203(a)(3)(ii)
El 50.73(a)(2)(ii)(A)
El 50.73(a)(2)(viii)(A)
[I 20.2203(a)(1)
El 20.2203(a)(4)
E] 50.73(a)(2)(ii)(B)
El 50.73(a)(2)(viii)(B)
El 20.2203(a)(2)(i)
El 50.36(c)(1)(i)(A)
[I 50.73(a)(2)(iii)
El 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)
E] 20.2203(a)(2)(iii)
E-50.36(c)(2)
El 50.73(a)(2)(v)(A)
El 73.71(a)(4)
El 20.2203(a)(2)(iv)
[I 50.46(a)(3)(ii)
E] 50.73(a)(2)(v)(B)
E] 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 E] 20.2203(a)(2)(vi)
Z 50.73(a)(2)(i)(B)
[E 50.73(a)(2)(v)(D)
Specify in Abstract below or in
Analysis of the Event
The inadvertent cross-tie of A and B CCW headers to the control room HVA/ACC-3C found during Plant Operator daily rounds violated the independence requirement of the TS 3.7.3 for two independent CCW headers, which is a condition prohibited by Technical Specifications and reportable under 10CFR50.73(a) (2)
(i)
(B),
and 10CFR50.73 (a)
(2)
(vii),
a common cause of inoperability of independent trains.
The CCW system is a closed loop cooling water system configured with two redundant essential supply header systems (designated 'A' and 'B')
each with a pump and heat exchanger and the capability to supply the minimum safety requirements during plant shutdown or design basis accident conditions.
The non-essential supply header which is connected to both essential headers during normal operation is automatically isolated from the essential headers by valve closure on a safety injection actuation signal (SIAS).
Each essential header alone has the heat removal capacity to safely shutdown the reactor or to mitigate the effects of a design basis accident and is separated from the other essential and non-essential header during accident conditions.
During normal operation, the CCW system provides cooling to components important to safety such as reactor coolant pumps, containment fan coolers, and spent fuel pool heat exchangers.
During accident conditions, the CCW system provides cooling for safety related components associated with reactor decay heat removal, containment cooling, and control room habitability.
The three control room air conditioning units are supplied by an essential CCW header.
Each essential CCW header is capable of supplying all three A/C units.
In order to maintain train separation, essential header
'A' is lined up to supply A/C Unit 3A, which is powered by Train A electrical
- power, and essential header
'B' is lined up to supply A/C Unit 3B, which is powered by Train B electrical power.
A/C Unit 3C is a swing component that can have CCW and electrical power supplied from either Train A or B.
In order to maintain train separation, electrical power and CCW must be aligned to the same train.
Cross-connecting CCW trains by opening the supply or return valves to both trains violates the CCW system design criteria for independent trains.
All valves associated with CCW to the A/C units are manually operated.
No indications of CCW alignment to the A/C units are provided in the Control Room or other location.
The normal CCW supply arrangement for A/C 3C is Train A supply valves open, Train B return valves closed.
In this event, an ECO was issued to establish the conditions to cut out and replace a vent valve for the CCW supply header A to control room HVA/ACC-3C.
This valve was found to have a slow seat leak in July 2002 when upstream isolation valve V14510 was open.
The ECO shut CCW supply valves V14510 and V14506 and combined discharger header isolation valve SH14265.
However, during restoration of the ECO on November 10, 2010, CCW supply valves were returned to their default position, Train B to Train A.
The Train A and B return valves were not part of the ECO and remained aligned to alternate Train B resulting in cross-tying the two trains.
Analysis of Safety Significance The inadvertent cross-tie of A and B CCW headers to the control room HVA/ACC-3C found during Plant Operator daily rounds violated the independence requirement of the TS 3.7.3 for two independent CCW headers which is a condition prohibited by Technical Specifications.
An Engineering assessment was performed 4o determine if any additional risk of core damage exists as a result of cross connecting the essential trains of CCW in this event.
The risk was evaluated for both dormal operation, from a seismic event causing total loss of CCW due to a breakfin the cross-tied non-essential header, and during accident conditions from two concurrent initiating events where a postulated LOCA occurs in seismic qualified piping at the same time a seismic event occurs which causes a break in the cross connected non-essential header piping.
In both cases the calculated value for incremental core damage probability (ICCDP) was determined to be non-risk significant and below the threshold established in RG-l.174 for risk significance.
Corrective Actions
The corrective actions and supporting actions listed below are entered into the site corrective action program.
Any changes to the actions will be managed under the commitment management change program.
Immediate corrective actions taken:
- 1. The checklist for Operations Policy 520, check sheet 4, "ECO Release Review and Authorization Check List" was modified to ensure the release is consistent with AB buses alignment.(Complete)
- 2.
Station Clock Reset brief was communicated site wide. (Complete)
The following actions will be tracked within the St. Lucie Corrective Action Program:
- 1. Revise Operations Procedure 2-NOP-52.02 to ensure CCW and ICW valves (including
- V14510, V14518,
- V14514, V14506, MV-14-1, MV-14-2, MV-14-3, MV-14-4, SB21165 and SB21211) have positions tracked in electronic shift operations management system (eSOMS) when transferring 2AB buses and components from A side to B side and from B side to A side.
- 2.
Revise AP-l[2]-0010123 to remove the default positions of CCW valves V14510,
- V14518, V14514, V14506 and the other valves marked with an asterisk (*)
that have the note similar to, "The position of these valves may change due to plant conditions."
- 3.
Revise the following procedures to Aighlight the required configuration control method for the identified swing comp*Dnents:
- l[2]-NOP-14.02 o
V14510 (Unit 2 only),
VT4518 (Unit 2 only),
V14514 (Unit 2 only) o V14506 (Unit 2 only),
M 1, MV-14-2, MV-14-3, MV-14-4 1[2]-NOP-21.01A, B,
C, o
- SH21165, SH21211 1-NOP-52.02, o
MV-14-1, MV-14-2, MV-14-3, MV-14-4,
- SH21165, o
SH21211
- 4.
Perform a "training needs analysis" to determine what additional SRO and SNPO training is needed to address AB bus swing components and configuration control related to this event.
Similar Events
A review of external operating experience (OE) was completed.
Several examples were identified including significant operating event report (SOER),
SOER 98-1, "Safety System Status Control" Corrective actions taken or planned for this SOER are currently in our corrective action program (CAP) and will be reviewed to ensure they are effectively implemented and will prevent recurrence of similar problems.
A review of the St. Lucie CAP data base for similar events found there were no significant PSL events during the past 3 years where an equipment clearance was released as prescribed but in conflict with the existing system lineup which could have resulted in system inoperability.
Failed Components NA