05000298/LER-2016-003

LER-2016-003, Scaffold Construction Places Plant in a Condition Prohibited by Technical Specifications

Cooper Nuclear Station
Event date:	09-14-2016
Report date:	11-09-2016
Reporting criterion:	10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications
2982016003R00 - NRC Website

LER 16-003-00 for Cooper Nuclear Station RE: Scaffold Construction Places Plant in a Condition Prohibited by Technical Specifications

ML16326A261
Person / Time
Site:	Cooper
Issue date:	11/09/2016
From:	Limpias O A Nebraska Public Power District (NPPD)
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
LER 16-003-00
Download: ML16326A261 (5)

20555-0001, or by e-mail to Infocollects.Resource@nrc.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. LER NUMBER 2. DOCKET NUMBER 05000- 298 Cooper Nuclear Station

PLANT STATUS

Cooper Nuclear Station was in Mode 1, Power Operation, at 89 percent power, approaching the end of Cycle 29 in two-loop operation, at the time the condition was identified.

BACKGROUND

The safety objective of the Secondary Containment system [EIIS:NG] in conjunction with other...

engineering safeguards and nuclear safety systems is to limit the release to the environs of radioactive material so that off-site doses from a postulated design basis accident will be below the values permitted.

The reactor building isolation and control system serves to trip the reactor building [EIIS:NG] supply and exhaust fans [El IS:FAN], isolate the normal ventilation system and provide the starting signals for the Standby Gas Treatment (SGT) [El IS:BH] system in the event of a postulated Loss of Coolant Accident inside the drywell [EIIS:NG] or the postulated fuel handling accident in the reactor building.

Two normally open dampers [EIIS:DMP], in series, are provided both in the supply path and two exhaust paths for the reactor building and the two supply and exhaust paths for Reactor Recirculation Motor Generator (RRMG) set ventilation. Each set of dampers consists of one air actuated damper, supplied by instrument air backed up by an accumulator [EIIS:ACC] with an assured one-hour supply capacity, and a motor operated damper. These dampers ensure redundant, diverse isolation capability for the reactor building in the event of a release of radioactive material to the reactor building. These dampers close automatically on a Group 6 (Secondary Containment Isolation) isolation signal.

HV-AOV-265 is the RRMG Ventilation Supply Outboard Isolation Valve for RRMG 1B. This air operated valve (AOV) is normally open during plant operation. In addition to driving the actuator shaft, the air actuator cylinder physically rotates when the valve is opened or closed. This results in a large actuator movement path that includes the actuator shaft, cylinder, valve disc arm, and the airlines that connect to the cylinder.

EVENT DESCRIPTION

On September 14, 2016, during testing of the Reactor Recirculation Motor Generator Ventilation Air Operated Isolation Valves, the control switch for HV-AOV-265 was taken to close for valve stroke timing.

The valve failed to close. HV-AOV-265 was declared inoperable and Technical Specification (TS) Limiting Condition for Operation (LCO) 3.6.4.2, Condition A, Required Action A.1, "Isolate the affected penetration flow path by use of at least one closed and de-activated valve within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />," was entered.

In addition, Operations commenced preparations for transitioning the plant to single loop operation, including reducing power to approximately 50 percent to support removing the associated RRMG set from service.

Operations attempted to close HV-AOV-265 while an Engineer was stationed locally to observe the valve's operation. The Engineer identified that during the attempt to close the valve, the air supply line became pinched between the moving cylinder of the valve actuator and a scaffold that had been erected on June 29, 2016, to support work on a different valve.

2016 - 003 - 00 20555-0001, or by e-mail to Infocollects.Resource@nrc.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. LER NUMBER

2016 - 003 - 00 As such, air was restricted from exhausting from the air cylinder, pneumatically locking the piston and preventing the valve from closing. Further investigation revealed that the airline had been crimped and required replacement.

After modifying the scaffold to remove the interference with the operation of the valve, the airline for HV- AO-265 was replaced and the valve stroke testing was re-performed satisfactorily. HV-AO-265 was declared operable and TS LCO 3.6.4.2 was exited. Upon exiting the LCO, activities to prepare for transition to single loop operation were terminated.

BASIS FOR REPORT

This condition is reportable in accordance with 10 CFR 50.73(a)(2)(i)(B) as a condition prohibited by TS because the scaffolding, installed in June 2016, was in a position to block the movement of the valve since that time.

SAFETY SIGNIFICANCE

The safety significance of this event is low. Secondary Containment AOV, HV-AO-265, could not be fully closed; however, the redundant motor operated valve in the RRMG B ventilation inlet flow path; HV-MO- 264, provided the required safety function for Secondary Containment isolation. This event did not cause an impact to the safety of the general public, nuclear safety, industrial safety, or radiological safety.

CAUSE

The root cause of the event was determined to be that the personnel involved in the planning, construction, and inspection of the scaffold built for HV-MOV-264 were not aware of the external movement path of HV-AOV-265 actuator.

CORRECTIVE ACTIONS

Revise Maintenance Procedure 7.0.7, "Scaffolding Construction and Control," to include specific guidance for the planning, building and inspection of scaffolds in the vicinity of the AOVs listed below:

Cooper Nuclear Station 05000- 298 PC-AO-236AV HV-AO-257AV HV-AO-267AV HV-AO-263AV HV-AO-265AV Installed signs in the areas near the AOVs listed below to warn personnel of the external movement of these AOVs:

HV-AO-257AV HV-AO-259AV HV-AO-261AV HV-AO-263AV HV-AO-265AV HV-AO-267AV HV-AO-269AV HV-AO-271AV HV-AO-FCV1045A HV-AO-FCV1045B HV-AO-FCV1046 HV-AO-FCV1047 PC-AO-234AV PC-AO-236AV 20555-0001, or by e-mail to Infocollects.Resource@nrc.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.

PREVIOUS EVENTS

There have been no events reported in the last three years related to scaffold construction impacting the ability of components to perform their safety function.