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 Revort Part 21 (PAR) Event # 51386 Rep 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: Yes County: License #: State: NC NRC Notified by: DALE E PORTER Notifications:

PATTY PELKE R3DO HQ Ops Officer: JOHN SHOEMAKER PART 21/50.55 REACTORS EMAIL Emergency Class: NON EMERGENCY 10 CFR Section: 21.21 (a)(2) INTERIM EVAL oF DEVIATION PART 21 REPORT -POTENTIAL FAILURE OF ELECTROMATIC RELIEF VALVE CUTOUT SWITCHES The following information was excerpted from an Interim Part 21 Report, received from GE-Hitachi (GEH) via email: "[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 to components previously supplied to and accepted by licensees.

GEH has performed component testing but has been unable to complete the 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 based on the results.As such, in accordance with discussions with the sites previously identified as potentially applicable to this concern, GEH will close this 10 CFR Part 21 evaluation with a 10 CFR 21.21(b) Transfer of Information to the Dresden 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 at the 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 2 revision 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 Valve Cutout 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. Porter Safety Evaluation Program Manager GE-Hitachi Nuclear Energy Americas LLC Ph: (910) 819-4491.

• HITACHI GE Hitachi Nuclear Energy Dale E. Porter SGE-Hitachi Nuclear Energy Americas LLC Safety Evaluation Program Manager 3901 Castle Hayne Rd., Wilmington, NC 28401 USA T 910 819-4491 September 10, 2015 Dale.Porter@GE.Com MEN 15-042 R2 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555-0001

Subject:

Closure of Part 21 60-Day Interim Report Notification:

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

GEH has performed component testing but has been unable to complete the 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 based on the results. As such, in accordance with discussions with the sites previously identified as potentially applicable to this concern, GEH will close this 10 CFR Part 21 evaluation with a 10 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. Porter Safety Evaluation Program Manager GE-Hitachi Nuclear Energy Americas LLC MFN 15-042 R2Pge2o2 Page 2 of 2 References

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

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

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

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

information provided to the Dresden and Quad Cities sites

Enclosures:

1.. Description of Evaluation cc: J. Golla, USNRC S. J. Pannier, USNRC A. Issa, USNRC i.F. Zino, GEH J. F. Harrison, GEH J. G. Head, GEH J. Burke, GEH P. L. Campbell, GEH Washington PRC File PLM Spec 002N8035 R2 MFN 15-042 R2 Attachment 1 Page l of 1 Attachment 1 US Plant Potentially Affected US BWR Plant and Assaciated Facilities Utility X Exelan Plant Dresden 2-3 Quad Cities 1-2 x Exelon MFN 15-042 R2 Page 1lof 2 Attachment 2 Attachment 2 -Transfer of Information per §21.21Wb)(iI Name and address of the individual or individuals informing the Commission.

Dale E. Porter GE Hitachi Nuclear Energy Sofety Evaluation Program Manager 3901 Castle Hayne Road, Wilmington, NC 28401 1i11 Identification of the facility, the activity, or the basic component supplied for such facility which fails to comply or contains a defect.See Table 1.liii) Identification of the firm constructing the facility or supplying the basic comPonent which fails 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 to the present.(iv) Nature of the defect or failure to comply and the safety hazard which is created or could be created by such defect or failure to comply.The defect may reduce the available margin for the contacts thereby preventing a relief valve 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 was initiated On April 16, 2015.(vi) In the case of a basic component which contains a defect or fails to comply, the number and location of these components in use at, supplied for, being supplied for, or may be supplied for, manufactured, or being manufactured for one or more facilities or activities subject to the 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 or organization 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 the actuator to ensure that the condition does not exist. This will be completed prior to any future 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 plant conditions with sufficient accuracy to draw conclusions based on the results.

MFN 15-042 R2 Page 2of 2 Attachment 2 Attachment 2 -Transfer of Information per §21.21(b)(viii) Any advice related to the defect or failure to comply about the facility, activity, or basic component 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 not exist.(ix) In the case of an early site permit, the entities to whom an early site permit was transferred.

This is not an early site permit concern.

ENCLOSURE 1 MFN 15-0/42 R2 Description of Evaluation Enclosure 1 to MFN 15-042 R2Pae2o6 Page 2 of 6 Discussion Backqround GEH provides various parts and components that are designed to actuate Electromatic Relief Valves (ERVs). The only manner in which these valves can be opened is from an electrical signal received by the actuator.

The ERV Actuator Assembly contains the Solenoid Assembly which contains the cutout switch assembly as shown in Figure 1.The cutout switch bypasses the secondary holding coil in order to develop the magnetic field energy to engage the plunger. When the plunger is fully seated the cut out switch is open allowing 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 end of the plunger lever arm. The lever arm pivots, raising the front end of the arm which is connected to the tension spring. This causes the contact support to rotate (clockwise in Figure 21 creating a gap between the contact blocks a~nd the contact bar. The gap between the contact bar and the contact blocks removes the bypass of the secondary coil. The purpose of the secondary coil is to prevent burnup of the primary coil. When the electrical signal is removed the plunger lifts allowing the plunger lever arm to lift which releases the tension on the tension spring and allowing the torsion spring to close the contacts, resetting the actuator.

The resetting force is provided by a torsion spring by F2 which may be seen in Figure 1. If the secondary coil is not bypassed before the actuation signal is received the actuator will fail to provide the force necessary to actuate its valve.Cutau~Swvtt~

E ERV Actuator Assebly (352B2632G001)

Solenoi (343A2632G001)

Figure 1 Actuator and Solenoid Assembly in the reset position Enclosure 1 to MFN 15-042 R2Pge3o6 Page 3 of 6 Figure 2 Over travel of cutout switch Condition Two ERV Actuators, GEH P/N 352B2632GO01, designated as ERV Unit #5 and ERV Unit #8 were returned 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 screw hole stripped.

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

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.

After manually manipulating the reset angle ERV Unit #5 successfully actuated twice then failed on the third 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 the failures, and to determine whether the condition applied to components previously supplied to and accepted by licensees.

The investigation concluded that the ERV actuator assemblies failed to change state because of the failure of the cutout switch to fully close and provide the appropriate current path. When ERV Unit #5 failed, a 0.003 inch gap was present between the contact bar and one of the contact blocks. When ERV Unit # 8 failed, a 0.001 inch gap was present between the contact bar and one of the contact blocks. For both ERV Unit #5 and ERV Unit #8 contact existed between the contact bar and one of the blocks but and a gap existed between 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 changes to reduce wear caused by vibration on the actuators changed lever arm position and also allowed for additional dimensional tolerance which tended to increase force in the tension spring. Additionally, insufficient clearances between the lever arm hinge pin and the associated Enclosure 1 to MEN 15-042 R2Pae4o6 Page 4 of 6 bushing may have contributed to increased frictional forces in the part, becoming a second contributing factor.Proper contact in the cutout switch is dependent on the reset angle. For discussion purposes the term reset angle refers to the angle of the contact support after the plunger lifts and the part resets. The solenoid assembly in Figure 2 is in the reset position therefore the contact support is in the reset angle. Unreliable performance occurs when the reset angle for a given part does not consistently ensure adequate contact. Conversely, reliability is achieved when the reset angle always 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 are caused by the forces shown in Figure 3. The fourth is caused by friction.

For a given part the moments caused by forces Fl, F2, and, F3 are only dependent on the angle of the contact support. Therefore any variance in the reset angle is due to variation of the moment due to friction in the part. The amount of over travel, as shown in Figure 2, is a good indication of the susceptibility of an assembly to unreliable operation.

Positive over travel ensures proper contact is made despite frictional variation.

Figure 3 Friction is present when the assembly is reset, not allowing the contact support to proceed entirely to its neutral, zero friction reset angle. As energy is added to the system sufficient to Enclosure 1 to MFN 15-042 R2Pae5f Page 5 of 6 overcome 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 be expected 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 agitated during bench testing at GEH. These assemblies were found to function consistently in the presence of this agitation.

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

Additional testing was performed to mimic vibrations and impact energies experienced on site. While this testing confirmed that added energy tended to increase reliability when a gap between the contact bar and 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 for this 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 make them more robust to the effects of vibration.

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

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

Therefore all the 343A2632GO01 and 352B2632G001 modified actuator assemblies that have been received by the customer are classified as potentially affected.

Table 1 shows the sites that have received these parts from GEH.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 is no reason to believe that reliability would decrease over time.* No operational experience exists in which an installed actuator failed in a manner consistent with this potential vulnerability.

• Settling of the components of the actuator assembly due to agitation has been observed in 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 final assembly, this then provides reasonable assurance that functionality is maintained.

As the number of successful cycles of the component increases so does the confidence in the successful operation of the cutout switch.Safety I mpact ERV 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 the number of actuator assemblies, if any, which have been installed with this condition.

Enclosure 1 to MFN 15-042 R2 Pa]ge 6 of 6 Conclusions 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 or would have created a] Technical Specification Safety Limit violation as it relates to the subject plant applica~tions.

Additional testing was performed to further investigate this condition to determine whether a reportable condition exists. While this testing confirmed tha~t added energy tended to increase reliability when a] ga~p between the contact ba~r and the contact blocks was present, it was unable to model plant conditions with sufficient a]ccuracy to dra~w applica]tion specific conclusions ba~sed on the results. GEH presents this document aIs a] 10 CFR Part 21.211b1 Transfer of Information so that the Exelon sta]ff can determine Reporta~bility of this condition.

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

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

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

_________

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

_________

________ ________ ___________

moad ified) ____ _________