05000387/LER-2013-007, Regarding Loss of Secondary Containment Due to Drawdown Test Failure

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Regarding Loss of Secondary Containment Due to Drawdown Test Failure
ML14021A098
Person / Time
Site: Susquehanna  Talen Energy icon.png
Issue date: 01/21/2014
From: Franke J
Susquehanna
To:
Document Control Desk, Office of Nuclear Reactor Regulation
References
PLA-7128 LER 13-007-00
Download: ML14021A098 (6)
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LER-2013-007, Regarding Loss of Secondary Containment Due to Drawdown Test Failure
Event date:
Report date:
Reporting criterion: 10 CFR 50.73(a)(2)(v), Loss of Safety Function
10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications
3872013007R00 - NRC Website
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text

JAN 2 1 2014 Jon A. Franke Site Vice President U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555 PPL Susquehanna, LLC 769 Salem Boulevard Berwick, PA 18603 Tel. 570.542.2904 Fax 570.542.1504 jfranke@ pplweb.com SUSQUEHANNA STEAM ELECTRIC STATION LICENSEE EVENT REPORT# 387(388) 2013-007-00 UNIT 1 LICENSE NO. NPF-14 UNIT 2 LICENSE NO. NPF -22 PLA-7128 Docket No 50-387 50-388 Attached is Licensee Event Report (LER) 387(388) 2013-007-00. The LER reports two separate performances of a Secondary Containment test that did not pass acceptance criteria, resulting in the discovery of a loss of safety function.

During initial testing on November 20, 2013 at 2247 hours0.026 days <br />0.624 hours <br />0.00372 weeks <br />8.549835e-4 months <br />, Susquehanna Steam Electric Station (SSES) Secondary Containment drawdown testing failed to meet acceptance criteria of Technical Specification (TS) Surveillance Requirement (SR) 3.6.4.1.5 due to in-leakage flow rate exceeding the allowable value. The test was being conducted on a previously untested alignment of the Unit 1 ventilation system. Prior to the test, Limiting Condition for Operation (LCO) 3.6.4.1 was entered for both Unit 1 and Unit 2 at 2247. Following the unsuccessful test, Secondary Containment was restored to an operable condition by reverting to a previously tested alignment of the Unit 1 ventilation system and LCO 3.6.4.1 was exited at 0240 hours0.00278 days <br />0.0667 hours <br />3.968254e-4 weeks <br />9.132e-5 months <br /> on November 21.

During retesting on December 7, 2013, at 0950 hours0.011 days <br />0.264 hours <br />0.00157 weeks <br />3.61475e-4 months <br />, SSES Secondary Containment draw down testing failed to meet acceptance criteria of TS SR 3.6.4.1.5 due to in-leakage flow rate exceeding the allowable value. Prior to the retest, LCO 3.6.4.1 was entered for both Unit 1 and Unit 2 at 0950. Following the unsuccessful retest, Secondary Containment was restored to an operable condition by reverting to a previously tested alignment of the Unit 1 ventilation system and LCO 3.6.4.1 was exited at 1349 hours0.0156 days <br />0.375 hours <br />0.00223 weeks <br />5.132945e-4 months <br />.

Using the guidance in NUREG-1022 Revision 3, both events were determined to be reportable as an Event or Condition that Could Have Prevented Fulfillment of a Safety Function in accordance with 10 CFR 50.73(a)(2)(v)(C), in that a condition was discovered that would have resulted in the single-train Secondary Containment system to become inoperable in a required mode. The events were also determined to be reportable under 10 CFR 50.73(a)(2)(i)(B) as a Condition Prohibited by Technical Specifications due to the Document Control Desk PLA-7128 Secondary Containment being in the untested alignment for periods that exceeded the time allowed by LCO 3.6.4:1.

There were no actual consequences to the health and safety of the public as a result of these events.

5:{;~fied in this submittal.

~.A. Franke Attachment: LER 387(388) 2013-007-00 Copy:

NRC Region I Mr. J. Greives, NRC Sr. Resident Inspector Mr. J. Whited, NRC Project Manager Mr. L. Winker, P A DEP/BRP

NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 0113112017 (01-2014)

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, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.

YEAR 2013

6. LER NUMBER I

SEQUENTIAL I NUMBER 007 REV NO.

00 2

3. PAGE OF 4

There were no systems, structures, or components that were inoperable at the start of the event and contributed to the event.

EVENT DESCRIPTION

Initial Test sequence of events:

On November 20, 2013, at 2247 hours0.026 days <br />0.624 hours <br />0.00372 weeks <br />8.549835e-4 months <br /> Limiting Condition for Operation (LCO) 3.6.4.1 was entered (as planned) due to Secondary Containment being inoperable following the realignment of the Unit 1 Railroad Bay from Zone 3 (Unit 1 and Unit 2 common refuel area) to a no-zone and opening the Unit 1 Reactor Building Railroad Bay Access Door (Door-101 ).

Drawdown testing commenced at 2317 hours0.0268 days <br />0.644 hours <br />0.00383 weeks <br />8.816185e-4 months <br />. The in-leakage was measured at 5030 cubic feet per minute (cfm) during the drawdown test, which was in excess of the acceptance criteria of less than or equal to 391 0 cfm, thus resulting in a failed surveillance.

Upon failure of the surveillance, Door-1 01 was closed and the Unit 1 Railroad Bay was realigned back to Zone 3 (a known operable alignment with a valid surveillance test). This realignment resulted in in-leakage dropping below the acceptance criteria of less than or equal to 4000 cfm for that configuration. Secondary Containment was declared operable, and LCO 3.6.4.1 was exited at 0240 hours0.00278 days <br />0.0667 hours <br />3.968254e-4 weeks <br />9.132e-5 months <br /> on November 21,2013.

Retesting sequence of events:

On December 7, 2013 at 0950 hours0.011 days <br />0.264 hours <br />0.00157 weeks <br />3.61475e-4 months <br />, LCO 3.6.4.1 was entered (as planned) due to Secondary Containment being inoperable while in the retest alignment. Retesting commenced at 0951 hours0.011 days <br />0.264 hours <br />0.00157 weeks <br />3.618555e-4 months <br />. The retest failed due to average containment in-leakage (4667 cfm) higher than the acceptance criteria. The Secondary Containment ventilation alignment was returned to a previously surveilled test alignment and LCO 3.6.4.1 was exited at 1349 hours0.0156 days <br />0.375 hours <br />0.00223 weeks <br />5.132945e-4 months <br /> following confirmation of reasonable assurance of Secondary Containment integrity.

Per the guidance provided in NUREG-1 022, 8 hour9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> notifications (EN#49565, EN#49614) were made to the NRC in accordance with 10 CFR 50.72(b)(3)(v)(C) for an event or condition that at the time of discovery, could have prevented the fulfillment of the safety function of Secondary Containment to control the release of radioactive material. As such, this LER is submitted in accordance with 10 CFR 50.73(a)(2)(v)(C) for an event or condition that could have prevented fulfillment of a safety function. The events were also determined to be reportable under 10 CFR 50.73(a)(2)(i)(B) as a condition prohibited by TSs due to the Secondary Containment being in the untested alignment for periods that exceeded the time allowed by LCO 3.6.4.1. This event is being reported as a Safety System Functional Failure in the Mitigating Systems cornerstone of the Reactor Oversight Process Performance Indicators.

CAUSE OF THE EVENT

The direct cause of both failed tests was leakage of air into Secondary Containment past Railroad Bay Access Hatch Cover 1 H24, doors, and removable walls due to undetected seal degradation.

~

YEAR 2013

6. LER NUMBER I

SEQUENTIAL I NUMBER J 007 The following apparent causes were found to be unique to the initial test failure:

REV NO.

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3. PAGE OF 4
  • The Unit 1 Railroad Bay airlock was not being periodically tested in its no-zone lineup as is required by TSs. Periodic testing could have identified a degrading trend in Secondary Containment in-leakage prior to exceeding the in-leakage limits.
  • Due to incorrect criticality code classification, there were no periodic preventative maintenance (PM) activities for Hatch Cover 1 H24, doors, and removable walls.
  • Excessive air in-leakage through Door-113A (outside to Zone 1).

The failures of both the initial and retest were found to have the following apparent causes in common:

  • Large amounts of air in-leakage through Hatch Cover 1 H24 and the Unit 2 Reactor Building Truck Bay Access Door (Door-1 02).
  • Numerous smaller leaks were found at various doors, hatches, and seals.

Additional evaluation of the retest failure is in progress. Significant changes as a result of the additional evaluation will be provided in a supplemental report, if necessary.

ANALYSIS I SAFETY SIGNIFICANCE Actual Consequences There were no actual consequences to the health and safety of the public as a result of this event.

Failure of Hatch Cover 1 H24, doors, and removable walls to seal properly resulted in excessive air in-leakage into Secondary Containment. The excessive in-leakage occurred when the Unit 1 Railroad Bay was aligned as a no-zone and Door-1 01 was open. This configuration was identified as a missed surveillance and was being tested when the excessive in-leakage was identified. When the Unit 1 Railroad Bay was realigned to Zone 3 and Door-1 01 was closed, in-leakage dropped below the acceptance criteria.

Potential Consequences With in leakage through Hatch Cover 1 H24, the Secondary Containment could have unknowingly been inoperable (Unit 1 Railroad Bay aligned as a no-zone) during irradiated fuel moves, core alterations, or Operations with the Potential to Drain the Reactor Vessel (OPDRVs), which is prohibited by LCO 3.6.4.1. Were a fuel handling accident or cavity drain down event to have occurred in this configuration, resultant accident dose may exceed that described in the current licensing basis.

If the Unit 1 Railroad Bay is aligned as a no-zone or to Zone 1, Secondary Containment would be considered inoperable, and require entry into LCO 3.6.4.1.

There are no additional potential consequences when the Unit 1 Railroad Bay is aligned to Zone 3. A drawdown test conducted with the Unit 1 Railroad Bay aligned to Zone 3 was successfully completed on 08/19/2011 and re-performed on 12/12/2013.

CORRECTIVE ACTIONS

Corrective actions to address the test failures were identified as follows:

Key Completed Corrective Actions

6. LER NUMBER I

SEQUENTIAL I NUMBER REV NO.

007

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  • Leaks have been repaired on Hatch Cover 1 H24 and various removable walls to limit future in-leakage
  • Corrective maintenance was performed on various doors
  • Door-113A has been sealed (caulked closed).

Key Planned Corrective Actions

  • Corrective maintenance to repair seals and air leaks on Door-1 02
  • Create PM activities to perform seal inspection and repair, as required, on Hatch Cover 1 H24 and Dampers XD17513 and XD17514
  • Create PM activities to perform door alignment, seal and threshold inspections and repairs as required for various doors

PREVIOUS SIMILAR EVENTS

There were no previous similar events identified.

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