|Susquehanna Steam Electric Station Unit 2 1 Of 4|
|Reporting criterion:||10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications|
|3882017002R00 - NRC Website|
|Person / Time|
|Site:||Susquehanna Steam Electric Station Unit 2 1 Of 4, Susquehanna|
Susquehanna, Talen Energy
Document Control Desk, Office of Nuclear Reactor Regulation
|Download: ML17125A026 (5)|
comments regarding burden estimate to the Information Services Branch (T-2 F43), U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001, or by e-mail to Infocollects.ResourceOnrc.qov.
and to the Desk Officer, Office of Information and Regulatory Affairs, 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 05000388 NUMBER NO.
- 002 - 00 Unit 2 2017
CONDITIONS PRIOR TO EVENT
Unit 2 — Mode 5, 0 percent Rated Thermal Power
While in Mode 5, Refueling, Operations with the Potential for Draining the Reactor Vessel (OPDRV) activities were performed as part of the Unit 2 18th Refueling and Inspection Outage (U2 18 RIO) without an operable secondary containment [EIIS Code: NG]. The event timeline for the planned activities is as follows:
3/6/2017, 17:15 — Operations entered Unit 2 Limiting Condition for Operations (LCO) 18.104.22.168 due to Zone II Secondary Containment isolated from the Recirculation Plenum and relaxed in support of outage activities.
3/6/2017, 17:41 to 3/29/2017, 13:21 — Station performed OPDRV activities under the provisions of EGM 11- 003, Revision 3, in support of U2 18 RIO.
3/30/2017, 14:12 — Operations cleared Unit 2 Technical Specification LCO 22.214.171.124 as Zone II was re- established and un-isolated from the recirculation plenum.
The station used the provisions of EGM 11-003, Revision 3 to perform the following outage activities:
- Recirculation system [EIIS Code: AD] flushes and maintenance
- Local Power Range Monitor (LPRM) [EIIS Code: IG] replacements
- Control Rod Drive (CRD) Mechanism [EIIS Code: AA] replacements
- Reactor Pressure Vessel (RPV) [EllS Code: RPV] Letdown established (Water Level remaining above RPV Flange)
- Hot Spot Flushes and Reactor Pressure Vessel Bottom Head Drain Flushes During the Mode 5 OPDRV window discussed above, one unplanned OPDRV event occurred. On 3/14/2017 at approximately 15:40, while performing quarterly valve exercising of the Division II RHR Pump Suction Valves, the procedural step to close the RHR minimum flow isolation valve was incorrectly marked as completed, but was not performed prior to the stroking of the RHR Shutdown Cooling Suction valve. This resulted in an unintended flow path from the Reactor Vessel to the Suppression Pool. The Operator recognized the minimum flow valve was open and immediately closed it.
An evaluation of all OPDRV activities that were in progress when this occurred determined that at no time did the calculated maximum leak rate exceed the EGM-11-003 allowable time to drain down to the top of the RPV flange.
comments regarding burden estimate to the Information Services Branch (T-2 F43), U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001, or by e-mail to Infocollects. Resourcef@nrc nov. and to the Desk Officer, Office of Information and Regulatory Affairs, 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 05000388 NUMBER NO.
CAUSE OF EVENT
Implementation of EGM 11-003, Revision 3, interim actions during the U2 18 RIO was a planned activity. As such, no cause determination was performed for the planned activities listed above.
With respect to the unplanned OPDRV event, the cause of the event was determined to be less than adequate use of human performance tools by the Operator. Specifically, procedure use and adherence was not performed correctly during completion of the surveillance activity. Additionally, a peer check was not consistently used during the performance of the procedure.
This event is reportable in accordance with 10 CFR 50.73(a)(2)(i)(B) as a condition prohibited by SSES Unit 2 TS 126.96.36.199, which prohibits activities identified as OPDRVs while secondary containment is inoperable.
The planned OPDRV activities described in this report were accomplished using the interim actions provided by the NRC in EGM 11-003, Revision 3. In accordance with station procedures controlling OPDRVs, SSES adhered to the NRC plain language meaning of OPDRV activities that could potentially result in draining or siphoning the Reactor Pressure Vessel (RPV) water level below the top of the fuel. This included evolutions involving aligning and realigning plant systems prior to achieving steady-state water level control, without taking credit for mitigating measures. SSES also met the requirements which specify the minimum makeup flow rate and water inventory availability. This ensures an adequate defense in depth was maintained to minimize the potential for the release of fission products with secondary containment not operable. Since these compensatory measures were implemented, an adequate level of safety was provided during the performance of the planned OPDRV activities described in this report.
During the unplanned OPDRV event, other planned OPDRV activities were in progress. As a result, adequate defenses were in place to ensure water inventory is maintained. Engineering evaluation of the event determined the total drain rate for the configuration was within the EGM guidance for ensuring the time to drain down the water inventory from the RHR-High Water level to the RPV flange remained greater than24 hours
. This was based on the aggregate flow from the existing OPDRVs in progress and the unplanned drain path.
Based on the review above, there were no actual consequences to the health and safety of the public as a result of both the planned and unplanned OPDRV activities.
comments regarding burden estimate to the Information Services Branch (T-2 F43), U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001, or by e-mail to Infocollects.ResourcePnrc.gov. and to the Desk Officer, Office of Information and Regulatory Affairs, 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 05000388 NUMBER NO.
Technical Specifications Task Force traveler 542 (TSTF-542), revision 2, associated with generic resolution of this issue, was approved by the NRC in December 2016. SSES will submit a License Amendment Request (LAR) to adopt this TSTF within the timeframe defined in EGM 11-003, Revision 3. No regulatory commitments are associated with this report.
The following corrective actions were implemented as a result of the unplanned OPDRV event:
1. The individual involved in the unplanned OPDRV was coached and remediated.
2. An Operations department communication with respect to Stop Work practices, procedure use and adherence and peer checking was completed.
PREVIOUS SIMILAR EVENTS
Revision 3," dated May 10, 2016.