05000389/LER-2009-001, Main Feedwater Isolation Valves Stroke Time Potentially Affected by Temperature
| ML091100396 | |
| Person / Time | |
|---|---|
| Site: | Saint Lucie  |
| Issue date: | 04/08/2009 |
| From: | Johnston G Florida Power & Light Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| L-2009-075 LER 09-001-00 | |
| Download: ML091100396 (5) | |
| 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 |
| 3892009001R00 - NRC Website | |
text
FPL Florida Power & Light Company, 6501 S. Ocean Drive, Jensen Beach, FL 34957 April 8, 2009 L-2009-075 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: 2009-001 Date of Event: March 19, 2009 Unit 2 Main Feedwater Isolation Valves Stroke Time Potentially Affected by Temperature The attached Licensee Event Report 2009-001 is being submitted pursuant to the requirements of 10 CFR 50.73 to provide notification of the subject event.
Very ly yours, oronýL.Ihins n
Site Vice Presi t St. Lucie Plant GLJ/dlc Attachment an FPL Group company
NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 08/31/201C 9-2007)
Estimated burden per response to comply with this mandatory collection request: 50 hours5.787037e-4 days <br />0.0139 hours <br />8.267196e-5 weeks <br />1.9025e-5 months <br />. Reported lessons learned are incorporated into the licensing process and fed back to industry. Send comments regarding burden estimate to the Records and FOIA/Privacy Service Branch (T-5 LICENSEE EVENT REPORT (LER)
F52), U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001, or by internet e-mail to infocollectsenrc.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
1 OF 4
- 4. TITLE Unit 2 Main Feedwater Isolation Valves Stroke Time Potentially Affected by Temperature
- 5. EVENT DATE
- 6. LER NUMBER
- 7. REPORT DATE
- 8. OTHER FACILITIES INVOLVED MONTH DAY YEAR YEAR SEQUENTIAL REV HFADALYT NYME DOAKET NUMBER NUMBER NO.
MONTH DAY YEAR FACILITY NAME DOCKET NUMBER 03 19 2009 2 0 09 -
0 01 0 0 04 08 2009
- 9. OPERATING MODE
- 11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR§: (Check all that apply)
El 20.2201(b)
[I 20.2203(a)(3)(i)
El 50.73(a)(2)(i)(C)
[] 50.73(a)(2)(vii)
El 20.2201(d)
El 20.2203(a)(3)(ii)
[: 50.73(a)(2)(ii)(A)
El 50.73(a)(2)(viii)(A)
El 20.2203(a)(1)
El 20.2203(a)(4)
El 50.73(a)(2)(ii)(B)
[D 50.73(a)(2)(viii)(B)
El 20.2203(a)(2)(i)
El 50.36(c)(1)(i)(A)
El 50.73(a)(2)(iii)
E] 50.73(a)(2)(ix)(A)
- 10. POWER LEVEL El 20.2203(a)(2)(ii)
El 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)
El 50.36(c)(2)
El 50.73(a)(2)(v)(A)
El 73.71 (a)(4) 100%
El 20.2203(a)(2)(iv)
El 50.46(a)(3)(ii)
El 50.73(a)(2)(v)(B)
El 73.71(a)(5)
El 20.2203(a)(2)(v)
El 50.73(a)(2)(i)(A)
El 50.73(a)(2)(v)(C)
E] OTHER El 20.2203(a)(2)(vi)
[
50.73(a)(2)(i)(B)
El 50.73(a)(2)(v)(D)
Specify in Abstract below or in This condition could have been applicable to any or all of the four feedwater isolation valves on Unit 2.
Documented stroke times for all four MFIVs have been less than the 5.15 seconds criteria during past testing. There are no other hydraulic/pneumatic valves in the steam trestle. Unit 1 MFIVs are nitrogen medium action valves and are not affected by this condition.
This is a legacy issue applicable to Unit 2 MFIVs and therefore is not considered a repeat event.
Analysis of Safety Significance St. Lucie Unit 2 TS 3.7.1.6 requires four MFIVs to be Operable in Modes 1, 2,
and 3 except when the MFIV is closed and deactivated.
The loss of all MFIVs would result in entry into TS 3.0.3 for failure to isolate any flow path and require action within one hour for Unit 2 to be placed in a Mode in which TS 3.7.1.6 does not apply (Modes 4,
5, or 6).
Review of records over the last three years show the worst case condition (loss of all MFIVs) for ambient temperatures less than 60'F existed for a 22-hour period, with 39 'F being the lowest temperature reached.
During this period, Unit 2 was in a Mode in which TS 3.7.1.6 applied.
Based on vendor manual information and Engineering judgment, the TS MFIV stroke time of 5.15 seconds could have been exceeded if automatic closure had been required due to a steamline break or main feedwater line break.
Due to the complexity of the MFIVs a precise closure time could not be calculated,
- however, the containment analysis used for the installation of replacement steam generators for Unit 2 was revisited to assess the affects on containment, containment pressure, and off-site doses. The new containment analysis used an improved estimate computer code (Gothic) using replacement steam generator conditions, which are conservative with respect to 'the old steam generators.
Results of this review concluded peak containment pressure would have remained below the design pressure limit of 44 psig and containment integrity would not be challenged until an internal containment pressure of approximately 95 psig was reached.
Given the worst-case ambient temperature identified 39°F, and assuming the MFIVs fail to stop full main feedwater flow, significant "margin to containment failure" still remained. Site boundary dose was also reviewed and determined not to be impacted for MFIV closure times in excess of 5.15 seconds.
Based on this evaluation, the potential safety consequences of the event are judged to be low and there would have been no significant impact on the health and safety of the public.
Corrective Actions
The corrective actions and supporting actions are entered into the site corrective action program.
Any changes to the proposed actions will be managed under the corrective action program.
Corrective Actions Taken
- 1. Temporarily installed temperature indicators in the steam trestle on MFIVs, on both headers, to monitor MFIV temperatures to ensure they do not go below 600 F.
- 2.
Reviewed MFIVs and trestle design for other covers in lieu of the tarp.
- 3.
Reviewed vendor and design documents of main turbine for applicability.
- 4. Covered MFIVs with tarps and placed space heaters to maintain ambient temperatures above 60OF
- 5.
Revised procedure ADM-04.03, "Cold Weather Preparation,." to include MFIVs on Unit 2 and guidance for maintaining temperature above 60'F
- 6.
Added MFIV actuator temperature to electronic shift operations management systems (ESOMS) data logger to check and log ambient temperatures each shift to ensure actions are taken; if temperature falls below 65°F.
Long Term Corrective Actions Replace MFIV actuators to operate at all temperatures at the site.
Similar Events
A search of the corrective action database for St. Lucie was performed to identify events related to a Main Feedwater Isolation Valves and none were found.
This event is not considered a repeat event.
Failed Components Main Feedwater Isolation Valves, Anchor Darling Valve Co.,
Model 20"-W7920697