05000387/LER-2012-004
| Susquehanna Steam Electric Station Unit 1 | |
| Event date: | 01-28-2011 |
|---|---|
| Report date: | 06-26-2012 |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications |
| 3872012004R00 - NRC Website | |
CONDITION PRIOR TO THE EVENT
Unit 1 - Mode 1, 35 percent Rated Thermal Power (at the time the event occurred on January 28, 2011)
EVENT DESCRIPTION
On April 27, 2012, it was determined that PPL Susquehanna, LLC (PPL) failed to enter Unit 1 Technical Specification (TS) 3.6.4.2, "Secondary Containment Isolation Valves" Limiting Condition for Operation (LCO) when the primary containment nitrogen makeup line spectacle flange (1S2104) was rotated in the open position in Modes 1, 2 and 3. This condition was identified as a result of questions raised regarding the need to enter TS LCO 3.6.4.2, in addition to TS LCO 3.6.1.3, "Containment Systems Primary Containment Isolation Valves," when the Unit 1 and Unit 2 spectacle flanges were rotated to the open position.
A review of Unit 1 and Unit 2 control room logs for the past three years identified that on two occasions in 2011 (January 28, 2011 and June 25, 2011), only TS LCO 3.6.1.3 had been entered when the Unit 1 flange was rotated open. No entry into the LCO for TS 3.6.4.2 occurred. Because the amount of time in which the Unit 1 spectacle flange was rotated open could not be exactly determined, the time when the LCO for TS 3.6.1.3 was entered and exited for the spectacle flange was used to conservatively determine the durations.
On two occasions, the Unit 1 spectacle flange was open for greater than the combined completion times for TS 3.6.4.2, Condition C.1 and D.1 (4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> and 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />, respectively) of 16 hours1.851852e-4 days <br />0.00444 hours <br />2.645503e-5 weeks <br />6.088e-6 months <br />. As a result, these events are reportable in accordance with 10 CFR 50.73(a)(2)(i)(B), as a condition prohibited by Technical Specifications.
CAUSE OF THE EVENT
Less than adequate guidance specified in Operations procedures and status control mechanisms for controlling Secondary Containment. The required station procedures, work instruction templates, the SSES Nuclear Information Management System component information "Requirements" field, and work orders for primary containment nitrogen makeup line spectacle flange work activities do not provide sufficient detail to address Secondary Containment status control and Technical Specification compliance.
ANALYSIS / SAFETY SIGNIFICANCE
The spectacle flanges (1S2104 and 2S2104) on the Unit 1 and Unit 2 primary containment nitrogen supply lines are not secondary containment isolation devices. SSES FSAR Table 6.2-15, FSAR Section 6.2 and calculation EC-059-1024, defines the design function of the spectacle flanges as Secondary Containment Bypass Leakage control. As with other piping systems that penetrate secondary containment, the piping forms the boundary protection from inleakage. Whether the blind side or the spectacle side of the flange is installed, the pipe provides protection from inleakage into the secondary containment boundary not the installed flange.
As such, this event had no impact on the health and safety of the public.
- The spectacle flanges (1S2104 and 2S2104) on the primary containment nitrogen makeup supply lines were deleted from the Unit 1 and 2 TS Bases Table B3.6.4.2-2, "Secondary Containment Ventilation System Passive Isolation Valves or Devices.
Key Planned Corrective Actions
- Review station procedures that could manipulate the components listed in TS Table B 3.6.4.2-1 and 3.6.4.2-2, to ensure that a precautionary or prerequisite note and procedural steps are added to contact Operations for entry or exiting TS 3.6.4.2. Procedural step shall reflect contacting Operations prior to manipulation of these components.
- Label penetrations and valves listed in TS Table 3.6.4.2-2 from TS 3.6.4.2 with the following note:
"Operation of these components can cause entry in to LCO 3.6.4.2 condition, contact control room for further information.
PREVIOUS SIMILAR EVENTS
None