ML15259A521

Part 21 Report - Potential Failure of Electromatic Relief Valve Cutout Switches

ML15259A521
Person / Time
Site:	Dresden, Quad Cities
Issue date:	09/10/2015
From:	Porter D E GE-Hitachi Nuclear Energy Americas
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
51386
Download: ML15259A521 (13)

Text

09/10/2015 U.S. Nuclear Regulatory Commission Operations Center Event RevortPart 21 (PAR) Event # 51386Rep Org: GE-HITACHI NUCLEAR ENERGY Notification Date I Time: 09/10/2015 15:50 (EDT)Supplier:

GE-HITACHI NUCLEAR ENERGY .Event Date I Time: 04/16/2015 (EDT)Last Modification:

09/10/2015

• Region:

I Docket#:City: WILMINGTON Agreement State: YesCounty: License #:State: NCNRC Notified by: DALE E PORTER Notifications:

PATTY PELKE R3DOHQ Ops Officer:

JOHN SHOEMAKER PART 21/50.55 REACTORS EMAILEmergency Class: NON EMERGENCY 10 CFR Section:21.21 (a)(2) INTERIM EVAL oF DEVIATION PART 21 REPORT -POTENTIAL FAILURE OF ELECTROMATIC RELIEF VALVE CUTOUT SWITCHESThe following information was excerpted from an Interim Part 21 Report, received from GE-Hitachi (GEH) viaemail:"[This GEH Report #MFN-1 5-042 R2, is a closure of a Part 21 60-Day Interim Report Notification, containing]

information concerning an evaluation of the failure during bench testing of Electromnatic Relief Valve Actuators (ERV -GEH Part number 352B2632G001) caused by the failure of a cutout switch to determine applicability tocomponents previously supplied to and accepted by licensees.

GEH has performed component testing but hasbeen unable to complete the evaluation to determine if a Reportable Condition, in accordance with 10 CFR 21.21exists."Testing was unable to model plant conditions with sufficient accuracy to draw conclusions based on the results.As such, in accordance with discussions with the sites previously identified as potentially applicable to thisconcern, GEH will close this 10 CFR Part 21 evaluation with a 10 CFR 21.21(b)

Transfer of Information to theDresden 2 and 3 and Quad Cities I and 2 sites."References

1. 60-Day Interim .Report Notification, Titled: Potential Failure of Electromatic Relief Valve Cutout Switch,Numbered:

MFN 15-042 RO, Dated: June 12, 2015.2. 60-Day Interim Report Notification, Titled: Potential Failure of Electromatic Relief Valve Cutout Switch,Numbered:

MFN 15-042 RI, Dated: June 22, 2015.The original notification was reported on June 12, 2015. Because there was a proprietary information disclaimer atthe top of that page, GEH revised the original report and submitted that revised letter on June 17, 2015. The 09/10/2015 U.S. Nuclear Regulatory Commission Operations Center Event Report Page 2revision 1 letter was posted in ADAMS with the following accession numbers as the original report.-ML15169A007

-Part 21 60-Day Interim Report Notification:

Potential Failure of Electromatic Relief ValveCutout Switch. (2 page(s),

6/17/20 15)-ML15169A008

-Attachment I -US Plants Potentially Affected.

(1 page(s),

6/18/2015)

-ML15169A009

-Attachment 2 Day Interim Report Notification Information per 21.21 (a)(2). (2 page(s),6/18/2015)

-ML15169A010

-Enclosure 1 -MFN 15-042 R0 -Description of Evaluation.

(6 page(s),

6/1 8/201 5)If you have any questions, please call;Dale E. PorterSafety Evaluation Program ManagerGE-Hitachi Nuclear Energy Americas LLCPh: (910) 819-4491.

• HITACHI GE Hitachi Nuclear EnergyDale E. PorterSGE-Hitachi Nuclear Energy Americas LLCSafety Evaluation Program Manager3901 Castle Hayne Rd.,Wilmington, NC 28401USAT 910 819-4491September 10, 2015 Dale.Porter@GE.Com MEN 15-042 R2U.S. Nuclear Regulatory Commission Attn: Document Control DeskWashington, DC 20555-0001

Subject:

Closure of Part 21 60-Day Interim Report Notification:

Potential Failure of Electromatic Relief Valve Cutout SwitchThis letter provides information concerning an evaluation of the failure during bench testing ofElectromatic Relief Valve Actuators (ERV -GEH Part number 352B2632G001) caused by thefailure of a cutout switch to determine applicability to components previously supplied to andaccepted by licensees.

GEH has performed component testing but has been unable to completethe evaluation to determine if a Reportable Condition, in accordance with 10 CFR 21.21 exists.Testing was unable to model plant conditions with sufficient accuracy to draw conclusions basedon the results.

As such, in accordance with discussions with the sites previously identified aspotentially applicable to this concern, GEH will close this 10 CFR Part 21 evaluation with a10 CFR 21.21(b)

Transfer of Information to the Dresden 2 and 3 and Quad Cities 1 and 2 sites.If you have any questions, please call me at 19101 819-4491.

Sincerely, Dale E. PorterSafety Evaluation Program ManagerGE-Hitachi Nuclear Energy Americas LLC MFN 15-042 R2Pge2o2Page 2 of 2References

1. 60-Day Interim Report Notification, Titled: Potential Failure of Electromatic Relief ValveCytout Switch, Numbered:

MEN 15-042 RO, Dated: June 12, 2015.2. 60-Day Interim Report Notification, Titled: Potential Failure of Electromatic Relief ValveCutout Switch, Numbered:

MEN 15-042 Ri, Dated: June 22, 2015.Attachments:

1. .US Plants Potentially Affected2. Transfer Of Information l§21.21(a)(2))

information provided to the Dresden and QuadCities sites

Enclosures:

1.. Description of Evaluation cc: J. Golla, USNRCS. J. Pannier, USNRCA. Issa, USNRCi.F. Zino, GEHJ. F. Harrison, GEHJ. G. Head, GEHJ. Burke, GEHP. L. Campbell, GEH Washington PRC FilePLM Spec 002N8035 R2 MFN 15-042 R2Attachment 1Page l of 1Attachment 1US Plant Potentially AffectedUS BWR Plant and Assaciated Facilities UtilityX ExelanPlantDresden 2-3Quad Cities 1-2xExelon MFN 15-042 R2 Page 1lof 2Attachment 2Attachment 2 -Transfer of Information per §21.21Wb)

(iI Name and address of the individual or individuals informing the Commission.

Dale E. PorterGE Hitachi Nuclear EnergySofety Evaluation Program Manager3901 Castle Hayne Road, Wilmington, NC 284011i11 Identification of the facility, the activity, or the basic component supplied for such facilitywhich fails to comply or contains a defect.See Table 1.liii) Identification of the firm constructing the facility or supplying the basic comPonent whichfails to comply or contains a defect.GE Hitachi Nuclear Energy (GEH) dedicated and supplied the referenced Electromatic Relief Valve (ERV) actuator component parts to the licensees listed in Table 1 from 2008 tothe present.(iv) Nature of the defect or failure to comply and the safety hazard which is created or could becreated by such defect or failure to comply.The defect may reduce the available margin for the contacts thereby preventing a reliefvalve from actuating.

(v) The date on which the information of such defect or failure to comply was obtained.

A Potential Reportable Condition Evaluation in accordance with 10 CFR Part 21 wasinitiated On April 16, 2015.(vi) In the case of a basic component which contains a defect or fails to comply, the number andlocation of these components in use at, supplied for, being supplied for, or may be suppliedfor, manufactured, or being manufactured for one or more facilities or activities subject tothe regulations in this part.See Table 1.(vii) The corrective action, which has been, is being, or will be taken; the name of the individual ororganization responsible for the action; and the length of time that has been or will be taken-to complete the action.GEH is implementing verification of sufficient over travel during the final assembly of theactuator to ensure that the condition does not exist. This will be completed prior to anyfuture shipments.

GEH has been unable to confirm sufficient over travel exists for Dresden & Quad Cities.A testing program was implemented but the testing was unable to model plantconditions with sufficient accuracy to draw conclusions based on the results.

MFN 15-042 R2 Page 2of 2Attachment 2Attachment 2 -Transfer of Information per §21.21(b)

(viii) Any advice related to the defect or failure to comply about the facility,

activity, or basiccomponent that has been, is being, or will be given to purchasers or licensees.

If positive over travel has not been previously confirmed during maintenance activities, perform inspections at the next available opportunity to verify that the condition does notexist.(ix) In the case of an early site permit, the entities to whom an early site permit wastransferred.

This is not an early site permit concern.

ENCLOSURE 1MFN 15-0/42 R2Description of Evaluation Enclosure 1 to MFN 15-042 R2Pae2o6Page 2 of 6Discussion Backqround GEH provides various parts and components that are designed to actuate Electromatic ReliefValves (ERVs). The only manner in which these valves can be opened is from an electrical signalreceived by the actuator.

The ERV Actuator Assembly contains the Solenoid Assembly whichcontains the cutout switch assembly as shown in Figure 1.The cutout switch bypasses the secondary holding coil in order to develop the magnetic fieldenergy to engage the plunger.

When the plunger is fully seated the cut out switch is openallowing current flow thru the secondary coil providing additional inductance to be introduced into the circuit.

Upon the actuation of the solenoid the plunger lowers and impacts the back endof the plunger lever arm. The lever arm pivots, raising the front end of the arm which isconnected to the tension spring. This causes the contact support to rotate (clockwise in Figure 21creating a gap between the contact blocks a~nd the contact bar. The gap between the contactbar and the contact blocks removes the bypass of the secondary coil. The purpose of thesecondary coil is to prevent burnup of the primary coil. When the electrical signal is removed theplunger lifts allowing the plunger lever arm to lift which releases the tension on the tension springand allowing the torsion spring to close the contacts, resetting the actuator.

The resetting force isprovided by a torsion spring by F2 which may be seen in Figure 1. If the secondary coil is notbypassed before the actuation signal is received the actuator will fail to provide the forcenecessary to actuate its valve.Cutau~Swvtt~

EERV Actuator Assebly (352B2632G001)

Solenoi (343A2632G001)

Figure 1 Actuator and Solenoid Assembly in the reset position Enclosure 1 to MFN 15-042 R2Pge3o6Page 3 of 6Figure 2 Over travel of cutout switchCondition Two ERV Actuators, GEH P/N 352B2632GO01, designated as ERV Unit #5 and ERV Unit #8 werereturned to GEH because of functionality issues identified during pre-installation bench testing.They were returned because ERV Unit #5 failed to cycle and ERV Unit #8 was found with a screwhole stripped.

Engineering investigated the "as-found" condition of these two actuatorassemblies.

This investigation included cyclic testing, visual inspection, and dimensional checks.The investigation discovered that ERV Unit #5 failed to actuate in the as-found condition.

Aftermanually manipulating the reset angle ERV Unit #5 successfully actuated twice then failed on thethird cycle. ERV Unit #8 actuated nine times then failed on the 10th cycle.Following the observed

failures, an investigation was initiated to determine the cause of thefailures, and to determine whether the condition applied to components previously supplied toand accepted by licensees.

The investigation concluded that the ERV actuator assemblies failedto change state because of the failure of the cutout switch to fully close and provide theappropriate current path. When ERV Unit #5 failed, a 0.003 inch gap was present between thecontact bar and one of the contact blocks. When ERV Unit # 8 failed, a 0.001 inch gap waspresent between the contact bar and one of the contact blocks. For both ERV Unit #5 and ERVUnit #8 contact existed between the contact bar and one of the blocks but and a gap existedbetween the contact bar and the other contact block.Multiple contributing factors were discovered which could have led to the presence of the gaps.The most significant of these factors is a change in lever arm positioning causing increased forces in the tension spring which prevent proper closure of the cutout switch. Design changesto reduce wear caused by vibration on the actuators changed lever arm position and alsoallowed for additional dimensional tolerance which tended to increase force in the tensionspring. Additionally, insufficient clearances between the lever arm hinge pin and the associated Enclosure 1 to MEN 15-042 R2Pae4o6Page 4 of 6bushing may have contributed to increased frictional forces in the part, becoming a secondcontributing factor.Proper contact in the cutout switch is dependent on the reset angle. For discussion purposes theterm reset angle refers to the angle of the contact support after the plunger lifts and the partresets. The solenoid assembly in Figure 2 is in the reset position therefore the contact support isin the reset angle. Unreliable performance occurs when the reset angle for a given part does notconsistently ensure adequate contact.

Conversely, reliability is achieved when the reset anglealways ensures sufficient contact between the contact bar and the contact blocks.When a part resets there are four moments that determine the reset angle. Three of these arecaused by the forces shown in Figure 3. The fourth is caused by friction.

For a given part themoments caused by forces Fl, F2, and, F3 are only dependent on the angle of the contactsupport.

Therefore any variance in the reset angle is due to variation of the moment due tofriction in the part. The amount of over travel, as shown in Figure 2, is a good indication of thesusceptibility of an assembly to unreliable operation.

Positive over travel ensures proper contactis made despite frictional variation.

Figure 3Friction is present when the assembly is reset, not allowing the contact support to proceedentirely to its neutral, zero friction reset angle. As energy is added to the system sufficient to Enclosure 1 to MFN 15-042 R2Pae5fPage 5 of 6overcome the frictional moment, the contact bar will tend to drift towards its zero friction angle.This means an assembly that doesn't consistently make contact when initially reset would beexpected to do so as energy is added, as by normal system vibration.

ERV Units #5 and #8,which were previously observed to exhibit inconsistent operation, have been manually agitatedduring bench testing at GEH. These assemblies were found to function consistently in thepresence of this agitation.

This agitation was applied during bench testing which consisted ofrepeated instances of assembly actuation followed by mechanical agitation.

Additional testingwas performed to mimic vibrations and impact energies experienced on site. While this testingconfirmed that added energy tended to increase reliability when a gap between the contact barand the contact blocks was present, it was unable to model plant conditions with sufficient accuracy to draw application specific conclusions based on the results.

The primary reason forthis inability was lack of available plant data to describe agitation energies in all the situations where the ERVs would need to be functional.

Extent of Condition In 2006 the ERV actuator and solenoid assemblies shown in Figure 1 were modified to makethem more robust to the effects of vibration.

These parts were first delivered in 2008. Themodified solenoid assemblies became 343A2632G001 and the modified ERV actuator assemblies became 352B2632G001.

These modifications had the unintended consequence of creating thepossibility of producing parts that exhibit the condition.

Therefore all the 343A2632GO01 and352B2632G001 modified actuator assemblies that have been received by the customer areclassified as potentially affected.

Table 1 shows the sites that have received these parts fromGEH.The likelihood of a part not performing its proper function is deemed to be low for the following reasons.* In service parts have passed numerous functional and post-installation tests and there isno reason to believe that reliability would decrease over time.* No operational experience exists in which an installed actuator failed in a mannerconsistent with this potential vulnerability.

• Settling of the components of the actuator assembly due to agitation has been observedin bench testing and is expected to occur during operation.

This settling significantly reduces variation in frictional forces that could cause an assembly to function unreliably.

Further, if site maintenance procedures confirm visual over travel of the cutout switch in the finalassembly, this then provides reasonable assurance that functionality is maintained.

As thenumber of successful cycles of the component increases so does the confidence in thesuccessful operation of the cutout switch.Safety I mpactERV function has the potential to affect the following BWR limits and systems.* Minimum Critical Power Ratio (MCPR)* Reactor Coolant System (RCS)* Automatic Depressurization System (ADSI* Low set relief function*The actual safety impact on the plants is currently unknown.

The safety impact depends on thenumber of actuator assemblies, if any, which have been installed with this condition.

Enclosure 1 to MFN 15-042 R2Pa]ge 6 of 6Conclusions Based on the eva~lua~tions for the subject condition, GEH does not have the information necessary to determine whether the subject condition would, or has, created a Substantial Safety Hazard orwould have created a] Technical Specification Safety Limit violation as it relates to the subjectplant applica~tions.

Additional testing was performed to further investigate this condition to determine whether areportable condition exists. While this testing confirmed tha~t added energy tended to increasereliability when a] ga~p between the contact ba~r and the contact blocks was present, it was unableto model plant conditions with sufficient a]ccuracy to dra~w applica]tion specific conclusions ba~sedon the results.

GEH presents this document aIs a] 10 CFR Part 21.211b1 Transfer of Information sothat the Exelon sta]ff can determine Reporta~bility of this condition.

Recommendations If positive over travel has not been previously confirmed during maintenance activities, performinspection at the next a~vailable opportunity to verify that the condition does not exist.Table 1Plant Customer Shipped Shipped P ar ubr Prt Safety Customer P0 #Description Name Date Quantity PrNubr Description ClassDRESDEN 2&3 Exelon 2014 352B2632GO01 ER c0ao 00000707 13856AssemblyDRESDEN 2&3 Exelon 2014 6 352B2632G001 Q cjaa 00526352AssemblyERV Actiuator Q:UAD CITIES 1&2 Exelon 2008 1 352626320001 Assembly 00000707 13133SolenoidQUAD CITIES 1&2 Exelon 20102 3Z43A2632G001 Assembly Q 00000707 13252_______________modified)

SolenoidQUAD CITIES 1&2 Exelon 2013 1 352B2632GO0t Assembly Q 00000707 13727(modified)

SolenoidQUAD CITIES l&2 Exelon 2008 1 343A2632GO01 Assembly Q 00000707 1_3234______________

_________

m odified)SolenoidQUAD CITIES t&2 Exelon 2013 3 352B2632G001 Assembly Q 00000707 13795______________

_________

________

________

___________

moad ified) ____ _________