05000387/LER-2015-004

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LER-2015-004, Secondary Containment Inoperable due to Secondary Containment Boundary Door Found Ajar
Susquehanna Steam Electric Station Unit 1
Event date:
Report date:
Reporting criterion: 10 CFR 50.73(a)(2)(v)(C), Loss of Safety Function - Release of Radioactive Material
Initial Reporting
ENS 51017 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material
3872015004R00 - NRC Website

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.

Susquehanna Steam Electric Station, Unit 1 05000387

CONDITIONS PRIOR TO THE EVENT

Unit 1 — Mode 1, approximately 97 percent Rated Thermal Power Unit 2 — Mode 5, 0 percent Rated Thermal Power There were no systems, structures, or components that were inoperable at the start of the event and contributed to the event.

EVENT DESCRIPTION

On Sunday, April 26, 2015 at 2230, with Unit 2 shut down for the 17th Refueling Outage, the Shift Manager approved Operations personnel to perform Attachment C, "Operation of 818 Elevation Floor Plug Checklist," in accordance with procedure OP-134-002, "Reactor Building HVAC Zones 1 and 3." This ventilation system realignment was done in support of Unit 2 outage activites to allow equipment to be moved in and out of the 101 railroad bay door. When in this alignment, Door-721 becomes a Secondary Containment boundary door and the door must remain in the closed position. On Monday, April 27, 2015, at 0058 hours6.712963e-4 days <br />0.0161 hours <br />9.589947e-5 weeks <br />2.2069e-5 months <br />, Control Room personnel signed off completion of OP-134-002, Attachment C.

On Monday, April 27, 2015 at 0850 hours0.00984 days <br />0.236 hours <br />0.00141 weeks <br />3.23425e-4 months <br />, during the performance of plant operator rounds, a plant operator found Secondary Containment boundary Door-721 unlatched and protruding out approximately 0.25 inches from the door frame. The plant operator immediately contacted Control Room personnel of the as-found and Unit 2 due to Secondary Containment being declared inoperable. The door was subsequently closed and Secondary Containment was recovered. At 0915 hours0.0106 days <br />0.254 hours <br />0.00151 weeks <br />3.481575e-4 months <br /> on April 27, 2015, TS 3.6.4.1, Condition A, was exited.

REPORTABILITY

On April 27, 2015, at 1546 hours0.0179 days <br />0.429 hours <br />0.00256 weeks <br />5.88253e-4 months <br />, an 8 hour9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> ENS (#51017) was made to the Nuclear Regulatory Commission in accordance with 10 CFR 50.72(b)(3)(v)(C) for any event or condition that could have prevented the fulfillment of the safety function of structures or systems that are needed to control the release of radioactive material.

SSES has no redundant Secondary Containment system.

In accordance with 10 CFR 50.73(a)(2)(v)(C), this LER is being submitted 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. Secondary Containment differential pressure was maintained throughout the time period that the Door-721 was not fully closed and latched.

CAUSE OF THE EVENT

The apparent cause of the event was plant personnel did not comply with the signage on Door-721, nor did they challenge the door after passing through it. As a result, Door-721 did not close properly.

ANALYSIS/SAFETY SIGNIFICANCE

POTENTIAL CONSEQUENCES

When the 818 Hatch Alignment is in effect, Door-721 provides a Secondary Containment boundary. The potential consequences of having this door open could have resulted in a failure to maintain/establish Secondary Containment during accident conditions.

ACTUAL CONSEQUENCES

There were no actual consequences of this event. Technical Specification 3.6.4.1 Secondary Containment differential press was maintained throughout the period that Door-721 was ajar. As such, Secondary Containment could have performed its safety function of isolating as assumed in the SSES accident analysis since differential pressure was maintained. Therefore, the safety function of the Secondary Containment boundary and Standby Gas Treatment systems were unaffected and remained operable during this event. As such, there were no actual consequences to the health and safety of the public.

Additionally, this event will not be counted as a safety system functional failure (SSFF) for the NRC performance indicator since there was no loss of Secondary Containment's ability to fulfill its safety function.

CORRECTIVE ACTIONS

Key Completed Action —

  • Door-721 was immediately closed.

Planned Actions —

  • Issue Site Communications to reinforce expectations to site personnel to comply with door signage and the requirement to gently challenge doors (when entering and exiting) in the power block per the plant standards.
  • Include the expectations in General Employee Training.

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