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=Text=
=Text=
{{#Wiki_filter:Dominion Energy South Carolin a, Inc.
{{#Wiki_filter:Dom in io n En ergy So uth Ca ro lin a, In c. ::F\\ Dominion 5000 Dom inion Bou le va rd, Glen A llen, VA 23 0 60 Dom in ion En ergy.com ii a,,, Energy@
5000 Dom inion Bou levard, Glen Allen, VA 23060 Dom inion Energy.com
August 22, 2022
::F\        Dominion ii a,,, Energy@
 
August 22, 2022 Serial No.:             22-240A Document Control Desk                                                                       VCS-LIC/MM:                 RO U.S. Nuclear Regulatory Commission                                                           Docket No.:               50-395 Washington, DC 20555                                                                         License No.:             NPF-12 DOMINION ENERGY SOUTH CAROLINA (DESC)
Serial No.: 22 -240A Document Control Desk VCS - LIC/MM: RO U.S. Nuclear Regulatory Commission Docket No.: 50 - 395 Washington, DC 20555 License No.: NPF-12
VI RG IL C. SUMMER NUCLEAR STATION (VCSNS) UNIT 1 RESPONSE TO AN APPARENT VIOLATION : (EA-22-039)
 
By {{letter dated|date=May 12, 2022|text=letter dated May 12, 2022}} (Reference 1), the Nuclear Regulatory Commission (NRC) notified Dominion Energy South Carolina (DESC) of an Apparent Violation (AV 05000395/2022001 -01) for "Failure to Correct Condition Adverse to Quality Resulting in Inoperable Emergency Diesel Generator." By {{letter dated|date=July 14, 2022|text=letter dated July 14, 2022}} (Reference 2),
DOM I NION ENERG Y SO UTH CARO LI NA ( DESC )
the NRC preliminarily determined the finding to be of low to moderate safety significance (White) and provided an opportunity for DESC to submit a pre-decisional response to the AV. By {{letter dated|date=July 19, 2022|text=letter dated July 19, 2022}}, DESC informed the NRC that additional written information would be provided for consideration in making a final determination for the AV (Reference 3).
VI RG IL C. S U MMER NUC L EAR ST A TI ON (V CSNS ) U N IT 1 RESP O NSE TO AN APPAREN T VIOL A T ION : ( EA-22-0 39 )
 
By {{letter dated|date=May 12, 2022|text=letter dated May 12, 2022}} (Reference 1 ), the Nuclear Regulatory Commission (NRC) notified Dominion Energy South Carolina (D ESC) of an Apparent Violation (AV 05000395/2022001 -01) for "Failure to Correct Condition Adverse to Quality Resulting in Inoperable Emergency Diesel Generator." By {{letter dated|date=July 14, 2022|text=letter dated July 14, 2022}} (Reference 2),
the NRC preliminarily determined the finding to be of low to moderat e safety significance (White) and provided an opportunity for DESC to submit a pre-decisional response to the AV. By {{letter dated|date=July 19, 2022|text=letter dated July 19, 2022}}, DESC informed the NRC that additional written information would be provided for consideration in making a final determination for the AV (Reference 3).
 
The additional information is provided as Attachment 1 to this letter. This information provides DESC's perspective of the significance of the finding and related facts used to reach our determination.
The additional information is provided as Attachment 1 to this letter. This information provides DESC's perspective of the significance of the finding and related facts used to reach our determination.
Should you have any questions regarding this submittal or require additional information, please contact Mr. Michael Moore, Manager Nuclear Station Licensing at (803) 345-4752.
 
Sincerely, Daniel G. Stoddard Senior Vice President and Chief Nuclear Officer CRAIG D SLY Notary Public Commonwealth of Virginia COMMONWEALTH OF VIRGINIA                                                                         Reg. # 7518653 My Commission Expires December 31, 20~
Should you have any questions regarding this submittal or require additional information, please contact Mr. Michael Moore, Manager Nuclear Station Licensing at (803) 345 -4752.
COUNTY OF HENRICO The foregoing document was acknowledged before me, in and for the County and Commonwealth aforesaid, today by Daniel G.
 
Sincerely,
 
Daniel G. Stoddard Senior Vice President and Chief Nuclear Officer CRA IG D SLY Commonw ea lth Not a ry Public of Virg in ia
 
COMMONWEAL TH OF VIRGINIA R eg. # 75 18653 My Commi ssio n Ex pires Dec em be r 31, 20~
COUNTY OF HENRICO
 
The foregoing document was acknowledged before me, in and for the County and Commonwealth aforesaid, today by Daniel G.
Stoddard, who is Senior Vice President and Chief Nuclear Officer of Dominion Energy South Carolina. He has affirmed before me that he is duly authorized to execute and file the foregoing document in behalf of that company, and that the statements in the document are true to the best of his knowledge and belief.
Stoddard, who is Senior Vice President and Chief Nuclear Officer of Dominion Energy South Carolina. He has affirmed before me that he is duly authorized to execute and file the foregoing document in behalf of that company, and that the statements in the document are true to the best of his knowledge and belief.
                                                *B~[)
Acknowledged before me this...frL_ day of ""J U JL-~*B~[) A _.,_ 022.
Acknowledged before me this ...frL_ day of A""JUJ_.,_L 022.
                                                                              -~
My Commission Expires:        JZ. /31/i..i
                                      ----'=-I-'
                                            ,   c..:.,,i -=;;...____
                                                                                    ~
                                                                                    ~        Public


Serial No. 22-240A Docket No. 50-395 Page 2 of 2
My Commission Expires: JZ. /31/i..i ~
----'=-I-', c..:.,,i-=;;...____ ~ Public Serial No. 22-240A Docket No. 50-395 Page 2 of 2


==References:==
==References:==
: 1. "Virgil C. Summer - Integrated Inspection Report 05000395/2022001 and Apparent Violation," dated May 12, 2022.
: 1. "Virgil C. Summer - Integrated Inspection Report 05000395/2022001 and Apparent Viol a tion," dated May 12, 2022.
: 2. "Virgil C. Summer - NRC Inspection Report 05000395/2022090 and Preliminary White Finding and Apparent Violation," dated July 14, 2022.
: 2. "Virgil C. Summer - NRC Inspection Report 05000395/2022090 and Preliminary White Finding and Apparent Violation," dated July 14, 2022.
: 3. "Virgil C. Summer Nuclear Station (VCSNS) Unit 1 - Pre-Decisional Reply to Apparent Violation 05000395/2022001 -01," dated July 19, 2022. : Response to Apparent Violation 05000395/2022001 -01 Commitments contained in this letter: None cc:   G. J. Lindamood - Santee Cooper L. Dudes - NRC Region II D. Dumbacher - NRC Region II G. E. Miller - NRC Project Mgr.
: 3. "Virgil C. Summer Nuclear Station (VCSNS) Unit 1 - Pre-Decisional Reply to Apparent Violation 05000395/2022001 - 01," dated July 19, 2022.
NRC Resident Inspector
: Response to Apparent Violation 05000395/2022001 - 01
 
Commitments contained in this letter: None
 
cc: G. J. Lindamood - Santee Cooper L. Dudes - NRC Region II D. Dumbacher - NRC Region II G. E. Miller - NRC Project Mgr.
NRC Resident Inspector Serial No. 22-240A Attachment 1 Page 1 of 10
 
Attachment 1
 
RESPONSE TO APPARENT VIOLATION 05000395/2022001-01 Serial No. 22-240A Attachment 1 Page 2 of 10
 
VIRGIL C. SUMMER NUCLEAR STATION (VCSNS)
DOMINION ENERG Y SOUTH CAROLINA, INC. (DESC)
RESPONSE TO APPARENT VIOLATION 0500039512022001-01


Serial No. 22-240A Attachment 1 Page 1 of 10 Attachment 1 RESPONSE TO APPARENT VIOLATION 05000395/2022001-01
Apparent Violation 0500039512022001-01


Serial No. 22-240A Attachment 1 Page 2 of 10 VIRGIL C. SUMMER NUCLEAR STATION (VCSNS)
An NRG-identified Apparent Violation of 10 CFR 50, Appendix B, Criterion XVI, was identified for the licensee failing to correct a condition adverse to quality resulting in the inoperability of the
DOMINION ENERGY SOUTH CAROLINA, INC. (DESC)
RESPONSE TO APPARENT VIOLATION 0500039512022001-01 Apparent Violation 0500039512022001-01 An NRG-identified Apparent Violation of 10 CFR 50, Appendix B, Criterion XVI, was identified for the licensee failing to correct a condition adverse to quality resulting in the inoperability of the
'B' emergency diesel generator (EDG). Specifically, there were indications of erratic governor performance following the January 2022 maintenance package that were identified during testing January 16, 2022. The governor performance was also erratic during the February 9, 2022, surveillance test, after which the licensee declared the EDG inoperable. As a result of this condition, the 'B' EDG was inoperable for a time in excess of its Technical Specification (TS) allowed outage time.
'B' emergency diesel generator (EDG). Specifically, there were indications of erratic governor performance following the January 2022 maintenance package that were identified during testing January 16, 2022. The governor performance was also erratic during the February 9, 2022, surveillance test, after which the licensee declared the EDG inoperable. As a result of this condition, the 'B' EDG was inoperable for a time in excess of its Technical Specification (TS) allowed outage time.
DESC's Response Introduction During post-maintenance testing after a January 15, 2022 '8' EOG maintenance package, erratic oscillations of frequency and kW were determined to have been caused by a detached tachometer signal generator. Following troubleshooting and repair of the signal generator, the oscillations were significantly reduced, and a successful surveillance test was completed on January 16, 2022. Based on field observations and the results of the January 16 surveillance test after the signal generator was repaired, the Shift Manager concluded '8' EOG was operable with the significantly reduced oscillations.
 
DESC's Response
 
Introduction
 
During post-maintenance testing after a January 15, 2022 '8' EOG maintenance package, erratic oscillations of frequency and kW were determined to have been caused by a detached tachometer signal generator. Following troubleshooting and repair of the signal generator, the oscillations were significantly reduced, and a successful surveillance test was completed on January 16, 2022. Based on field observations and the results of the January 16 surveillance test after the signal generator was repaired, the Shift Manager concluded '8' EOG was operable with the significantly reduced oscillations.
 
During a subsequent monthly surveillance test on February 9, 2022, the '8' EOG again met the TS surveillance test criteria, although the number of minor oscillations experienced during the February 9 'B' EOG run had increased when compared to the oscillations experienced during the January 16 surveillance test. After reviewing the information from the February 9 surveillance test, Engineering did not support a recommendation of continued operability and the Shift Manager declared the '8' EOG inoperable based on that recommendation. A broken Amphenol connection was subsequently identified as the cause of the oscillations and repaired.
During a subsequent monthly surveillance test on February 9, 2022, the '8' EOG again met the TS surveillance test criteria, although the number of minor oscillations experienced during the February 9 'B' EOG run had increased when compared to the oscillations experienced during the January 16 surveillance test. After reviewing the information from the February 9 surveillance test, Engineering did not support a recommendation of continued operability and the Shift Manager declared the '8' EOG inoperable based on that recommendation. A broken Amphenol connection was subsequently identified as the cause of the oscillations and repaired.
An independent third-party engineering firm specializing in EOG analysis was contracted to review data from the February 2022 test to determine if the '8' EOG could have provided emergency power to the 1E onsite busses during a loss of offsite power in the as-found condition.
 
An independent third-party engineering firm specializing in EOG analysis was contracted to review data from the February 2022 test to determine if the '8' EOG could have provided emergency power to the 1 E onsite busses during a loss of offsite power in the as-found condition.
The resulting evaluation (Reference 1) concludes that the '8' EOG transient performance limits in Regulatory Guide 1.9 (RG 1.9) were maintained, and the oscillations did not have an adverse impact on the safety function of the 'B' EOG or on its connected safety-related loads.
The resulting evaluation (Reference 1) concludes that the '8' EOG transient performance limits in Regulatory Guide 1.9 (RG 1.9) were maintained, and the oscillations did not have an adverse impact on the safety function of the 'B' EOG or on its connected safety-related loads.
Serial No. 22-240A Attachment 1 Page 3 of 10
Serial No. 22-240A Attachment 1 Page 3 of 10


===Background===
===
Background===
On January 10, 2022, the 'B' EOG was removed from service for a significant maintenance package and was originally scheduled to return to service on January 13, 2022. The restoration of 'B' EOG was delayed until January 16, 2022, due to a number of conditions as noted below:
On January 10, 2022, the 'B' EOG was removed from service for a significant maintenance package and was originally scheduled to return to service on January 13, 2022. The restoration of 'B' EOG was delayed until January 16, 2022, due to a number of conditions as noted below:
* CR-22-00134: The 'B' EOG had erratic indications of frequency and kW. [Dated January 15, 2022, at 03:55]
* CR-22-00134: The 'B' EOG had erratic indications of frequency and kW. [Dated January 15, 2022, at 03:55]
* CR-22-00136: The 'B' EOG mechanical overspeed trip device did not reset properly resulting in an engine trip. [Dated January 15, 2022, at 07:44]
* CR-22-00136: The 'B' EOG mechanical overspeed trip device did not reset properly resulting in an engine trip. [Dated January 15, 2022, at 07:44]
* CR-22-00139: The 'B' EOG signal generator came off the governor tachometer drive shaft. [Dated January 15, 2022, at 19:20]
* CR-22-00139: The 'B' EOG signal generator came off the governor tachometer drive shaft. [Dated January 15, 2022, at 19:20]
On January 15, during performance of a post-major maintenance test per SOP-306, "EMERGENCY DIESEL GENERATOR," Operations noted abnormal frequency oscillations and large kW swings at the 1,000 kW and 2,300 kW load plateaus. Figure 1, '"B' EOG Maintenance Run - January 15, 2022," provides an illustration of the kW oscillations. As a result, Operations secured the diesel after about 30 minutes and generated CR-22-00134.
On January 15, during performance of a post-major maintenance test per SOP-306, "EMERGENCY DIESEL GENERATOR," Operations noted abnormal frequency oscillations and large kW swings at the 1,000 kW and 2,300 kW load plateaus. Figure 1, '"B' EOG Maintenance Run - January 15, 2022," provides an illustration of the kW oscillations. As a result, Operations secured the diesel after about 30 minutes and generated CR-22-00134.
On January 16, the cause of the abnormal frequency and kW condition identified in CR-22-00134 was identified as being due to the 'B' EOG tachometer signal generator becoming disconnected due to inadequate clamping force on its bushing. The condition was corrected by reattaching the 'B' EOG tachometer signal generator using a satisfactory bushing. The 'B' EOG was then operated on the mechanical governor to allow adjustment of the governor high-speed setting and venting of any air that may have been in the governor.
On January 16, the cause of the abnormal frequency and kW condition identified in CR-22-00134 was identified as being due to the 'B' EOG tachometer signal generator becoming disconnected due to inadequate clamping force on its bushing. The condition was corrected by reattaching the 'B' EOG tachometer signal generator using a satisfactory bushing. The 'B' EOG was then operated on the mechanical governor to allow adjustment of the governor high-speed setting and venting of any air that may have been in the governor.
On January 16, 2022, at 03:50, after completion of the high-speed setting adjustment run, Operations started 'B' EOG per SOP-306. During this 3-hour test, there were no oscillations identified by field personnel. However, Operators in the Control Room observing the main control board noted minor oscillations occurred during the fully loaded portion of the test. Figure 2, '"B' EOG Loaded Maintenance Run - January 16, 2022," provides an illustration of the oscillations. The results of the January 16 test showed that the significant oscillations noted during the January 15 test were mostly eliminated and supported a conclusion that the issue in CR-22-00134 had been identified and corrected by reattaching the tachometer signal generator using a satisfactory bushing. The minor oscillations observed during this test were attributed to winter weather causing grid disturbances and potentially small amounts of air venting from the governor after maintenance.
On January 16, 2022, at 03:50, after completion of the high-speed setting adjustment run, Operations started 'B' EOG per SOP-306. During this 3-hour test, there were no oscillations identified by field personnel. However, Operators in the Control Room observing the main control board noted minor oscillations occurred during the fully loaded portion of the test. Figure 2, '"B' EOG Loaded Maintenance Run - January 16, 2022," provides an illustration of the oscillations. The results of the January 16 test showed that the significant oscillations noted during the January 15 test were mostly eliminated and supported a conclusion that the issue in CR-22-00134 had been identified and corrected by reattaching the tachometer signal generator using a satisfactory bushing. The minor oscillations observed during this test were attributed to winter weather causing grid disturbances and potentially small amounts of air venting from the governor after maintenance.
On January 16, 2022, at 21 :29, Operations started 'B' EOG per STP-125.002B, "DIESEL GENERATOR B OPERABILITY TEST'. During this surveillance test, the Control Room operators noted minor fluctuations in 'B' EOG kW output on the main control board. Additionally, field personnel observed occasional movements in the fuel rack, although much less severe and with different characteristics than the condition identified in CR-22-00134. These fluctuations were believed to be due to winter weather causing grid disturbances and potential governor air venting as described above. The same Shift Manager who ordered the EOG secured and


Serial No. 22-240A Attachment 1 Page 4 of 10 declared the EOG inoperable on January 15 during the post-major maintenance test, had no operability concern after this surveillance test. The 'B' EOG met the STP-125.0028 acceptance criteria during this test, including the criteria described below associated with the kW load-range and frequency deviations.
On January 16, 2022, at 21 :29, Operations started 'B' EOG per STP-125.002B, "DIESEL GENERA TOR B OPERABILITY TEST'. During this surveillance test, the Control Room operators noted minor fluctuations in 'B' EOG kW output on the main control board. Additionally, field personnel observed occasional movements in the fuel rack, although much less severe and with different characteristics than the condition identified in CR-22-00134. These fluctuations were believed to be due to winter weather causing grid disturbances and potential governor air venting as described above. The same Shift Manager who ordered the EOG secured and Serial No. 22-240A Attachment 1 Page 4 of 10
 
declared the EOG inoperable on January 15 during the post-major maintenance test, had no operability concern after this surveillance test. The 'B' EOG met the STP-125.0028 acceptance criteria during this test, including the criteria described below associated with the kW load-range and frequency deviations.
* Step 8.1.e: The Diesel Generator must be able to accept a load of between 4150 kW and 4250 kW and operate for at least 60 minutes within this band (T.S. 4.8.1.1.2.a.4).
* Step 8.1.e: The Diesel Generator must be able to accept a load of between 4150 kW and 4250 kW and operate for at least 60 minutes within this band (T.S. 4.8.1.1.2.a.4).
IYR01805, EMERGENCY DIESEL GEN B RW1, (XCP-6221) power data averaged over a ten-minute period is used to monitor this requirement; instantaneous readings are not required to be in this band.
IYR01805, EMERGENCY DIESEL GEN B RW1, (XCP-6221) power data averaged over a ten-minute period is used to monitor this requirement; instantaneous readings are not required to be in this band.
* Step 8.4.e: Steady-state, no-load, frequency deviations are 0.2 hertz or less from the average isochronous speed by both Local and MCB indication.
* Step 8.4.e: Steady-state, no-load, frequency deviations are 0.2 hertz or less from the average isochronous speed by both Local and MCB indication.
On February 9, 2022, during the monthly STP-125.0028 test of 'B' EOG, kW oscillations were noted in the Control Room while the 'B' EOG was synchronized with the grid. Figure 3: "'B' EOG Surveillance Run - February 9, 2022," provides an illustration of the kW oscillations. The magnitude of the oscillations and quick recovery to normal appeared to be similar to the January 16 STP-125.0028 test. Oscillations increased in frequency at the end of the test but were not considered by the Shift Manager to be a substantial concern or a challenge to diesel operability.
On February 9, 2022, during the monthly STP-125.0028 test of 'B' EOG, kW oscillations were noted in the Control Room while the 'B' EOG was synchronized with the grid. Figure 3: "'B' EOG Surveillance Run - February 9, 2022," provides an illustration of the kW oscillations. The magnitude of the oscillations and quick recovery to normal appeared to be similar to the January 16 STP-125.0028 test. Oscillations increased in frequency at the end of the test but were not considered by the Shift Manager to be a substantial concern or a challenge to diesel operability.
Local field observation noted normal engine operation, other than periodic fuel rack movement similar to the January 16 test. The 'B' EOG again met all STP-125.0028 acceptance criteria.
Local field observation noted normal engine operation, other than periodic fuel rack movement similar to the January 16 test. The 'B' EOG again met all STP-125.0028 acceptance criteria.
The Shift Manager determined there was reasonable assurance the diesel could perform its design basis function and was operable. Operations generated CR1191016 to document intermittent 'B' EOG kW oscillations and requested an Operability review from Engineering.
The Shift Manager determined there was reasonable assurance the diesel could perform its design basis function and was operable. Operations generated CR1191016 to document intermittent 'B' EOG kW oscillations and requested an Operability review from Engineering.
Engineering reviewed the test data, observed the increase in the frequency of kW oscillations, and communicated to Operations that they did not have reasonable assurance that the 'B' EOG could perform its function at that time due to the increasing number and magnitude of the oscillations. This was a judgement call from the Diesel Generator System Engineer based on qualitative analysis of the data.
Engineering reviewed the test data, observed the increase in the frequency of kW oscillations, and communicated to Operations that they did not have reasonable assurance that the 'B' EOG could perform its function at that time due to the increasing number and magnitude of the oscillations. This was a judgement call from the Diesel Generator System Engineer based on qualitative analysis of the data.
Subsequent troubleshooting confirmed the 'B' EOG load oscillations were caused by an intermittent open circuit and variable high resistance condition due to a mechanical fatigue fracture of the solder contact at the Pin B location within an Amphenol 90-degree angle plug connector. The broken pin was interrupting the electronic governor 2301A control output signal to the engine-mounted EGB-50P proportional governor/actuator. The broken pin was in the Pin B location, which provides the return path for the electronic governor signal to the actuator. After installation of a new Amphenol connector, the 'B' EOG tested satisfactorily.
Subsequent troubleshooting confirmed the 'B' EOG load oscillations were caused by an intermittent open circuit and variable high resistance condition due to a mechanical fatigue fracture of the solder contact at the Pin B location within an Amphenol 90-degree angle plug connector. The broken pin was interrupting the electronic governor 2301A control output signal to the engine-mounted EGB-50P proportional governor/actuator. The broken pin was in the Pin B location, which provides the return path for the electronic governor signal to the actuator. After installation of a new Amphenol connector, the 'B' EOG tested satisfactorily.
Due to concerns related to the 'B' EOG, DESC contracted a third-party engineering firm, specializing in EOG analysis, to evaluate the impact of the intermittent governor electrical connection.
Due to concerns related to the 'B' EOG, DESC contracted a third-party engineering firm, specializing in EOG analysis, to evaluate the impact of the intermittent governor electrical connection.
Serial No. 22-240A Attachment 1 Page 5 of 10


Serial No. 22-240A Attachment 1 Page 5 of 10 Reason for the Violation Determination of Operability The 'B' EOG oscillations experienced during testing on January 16, 2022, did not result in the
Reason for the Violation
 
Determination of Operability
 
The 'B' EOG oscillations experienced during testing on January 16, 2022, did not result in the
'B' EOG being declared inoperable. The Shift Manager determined that the 'B' EOG was operable on January 16 after performance of STP-125.0028 due to the following:
'B' EOG being declared inoperable. The Shift Manager determined that the 'B' EOG was operable on January 16 after performance of STP-125.0028 due to the following:
* The significant load and frequency oscillations due to the disconnected tachometer signal generator had been corrected on January 16.
* The significant load and frequency oscillations due to the disconnected tachometer signal generator had been corrected on January 16.
* The 'B' EOG met the acceptance criteria of STP-125.0028
* The 'B' EOG met the acceptance criteria of STP-125.0028
* The load and frequency oscillations were not substantive in comparison to the STP-125.0028 acceptance criteria and review of operational parameters. Additionally, the oscillations were believed to be due to winter weather at this time causing grid disturbances and potentially small amounts of air venting from the governor after maintenance.
* The load and frequency oscillations were not substantive in comparison to the STP-125.0028 acceptance criteria and review of operational parameters. Additionally, the oscillations were believed to be due to winter weather at this time causing grid disturbances and potentially small amounts of air venting from the governor after maintenance.
The Shift Manager's perspective was the 'B' EOG oscillations were minor and without adverse impacts, providing reasonable assurance of operability. Therefore, based on the judgement of the Shift Manager, 'B' EOG was declared operable on January 16 after performance of STP-125.0028 and a CR was not deemed to be required. DESC believes that this conclusion was reasonable considering the information available to the Shift Manager and the engineering organization after the completion of STP-125.0028 on January 16, 2022.
The Shift Manager's perspective was the 'B' EOG oscillations were minor and without adverse impacts, providing reasonable assurance of operability. Therefore, based on the judgement of the Shift Manager, 'B' EOG was declared operable on January 16 after performance of STP-125.0028 and a CR was not deemed to be required. DESC believes that this conclusion was reasonable considering the information available to the Shift Manager and the engineering organization after the completion of STP-125.0028 on January 16, 2022.
NOTE: The trend graph referenced in Apparent Violation 05000395/2022001-01 is from the plant computer system, which is reviewed for information only. This trend graph is not part of STP-125.0028, is not reviewed by the Shift Manager, and therefore not required for EOG operability.
NOTE: The trend graph referenced in Apparent Violation 05000395/2022001-01 is from the plant computer system, which is reviewed for information only. This trend graph is not part of STP-125.0028, is not reviewed by the Shift Manager, and therefore not required for EOG operability.
Amphenol Connector Pin Failure After the EOG was declared inoperable on February 9, 2022, troubleshooting confirmed the 'B' EOG load oscillations were caused by an intermittent open circuit and variable high resistance condition (referred to as "disturbances") due to a mechanical fatigue fracture of the solder contact at the Pin 8 location within an Amphenol 90-degree angle plug connector. This solder contact had been subjected to long-term alternating stress because of a design configuration that included no strain relief for the two 16-gauge wires utilized for governor control signal circuit DGU178.
 
Amphenol Connector Pin Failure
 
After the EOG was declared inoperable on February 9, 2022, troubleshooting confirmed the 'B' EOG load oscillations were caused by an intermittent open circuit and variable high resistance condition (referred to as "disturbances") due to a mechanical fatigue fracture of the solder contact at the Pin 8 location within an Amphenol 90-degree angle plug connector. This solder contact had been subjected to long-term alternating stress because of a design configuration that included no strain relief for the two 16-gauge wires utilized for governor control signal circuit DGU178.
 
Additional stress to the solder contacts would likely have occurred during the January 2022 performance of MMP-180.039 (EOG Engine Dynamic Check of Overspeed Governor) and troubleshooting associated with the separate frequency and kW oscillation condition identified on January 15 and documented in CR-22-00134. These maintenance activities were performed properly and with proper care; however, they potentially imparted sufficient additional stress to the fatigue weakened Pin B solder contact to result in the final fast fracture of the solder contact.
Additional stress to the solder contacts would likely have occurred during the January 2022 performance of MMP-180.039 (EOG Engine Dynamic Check of Overspeed Governor) and troubleshooting associated with the separate frequency and kW oscillation condition identified on January 15 and documented in CR-22-00134. These maintenance activities were performed properly and with proper care; however, they potentially imparted sufficient additional stress to the fatigue weakened Pin B solder contact to result in the final fast fracture of the solder contact.
Serial No. 22-240A Attachment 1 Page 6 of 10
After the solder contact fractured, it was prevented from permanently separating by the physical constraints within the Amphenol connector as well as the constant preload provided by the governor control circuit conduit. This condition resulted in kW oscillations at high loads during subsequent e ngine runs.
Third Party Analysis
An independent third-party engineering firm specializing in EOG analysis was contracted to determine if the 'B' EOG could have provided emergency power to the 1 E onsite busses during a loss of offsite power in the as-found condition. The resulting evalu a tion determined tha t the disturbances associated with the broken connector pin were of short dur a tion a nd it is appropriate to consider the transient performance limits in Regulatory Guide 1.9.


Serial No. 22-240A Attachment 1 Page 6 of 10 After the solder contact fractured, it was prevented from permanently separating by the physical constraints within the Amphenol connector as well as the constant preload provided by the governor control circuit conduit. This condition resulted in kW oscillations at high loads during subsequent engine runs.
The resulting eva lua tion determined that EOG 'B' transient performance limits in Regulatory Guide 1.9 (RG 1.9) for frequency (between 57 Hz and 64.5 Hz) and recovery time to within the required transient recovery band(+/ - 1.2 Hz of nominal within 40 percent of the load sequence time) were maintained. The evaluation concludes that the transients (oscillations) caused by the short-duration Pin B disturba nces did not have an adverse impact on the safety function of the
Third Party Analysis An independent third-party engineering firm specializing in EOG analysis was contracted to determine if the 'B' EOG could have provided emergency power to the 1E onsite busses during a loss of offsite power in the as-found condition. The resulting evaluation determined that the disturbances associated with the broken connector pin were of short duration and it is appropriate to consider the transient performance limits in Regulatory Guide 1.9.
'B' EOG or on its connected safety-rela ted loads (Reference 1 ). Reference 1 will be made available to the NRC for review.
The resulting evaluation determined that EOG 'B' transient performance limits in Regulatory Guide 1.9 (RG 1.9) for frequency (between 57 Hz and 64.5 Hz) and recovery time to within the required transient recovery band(+/- 1.2 Hz of nominal within 40 percent of the load sequence time) were maintained. The evaluation concludes that the transients (oscillations) caused by the short-duration Pin B disturbances did not have an adverse impact on the safety function of the
'B' EOG or on its connected safety-related loads (Reference 1). Reference 1 will be made available to the NRC for review.
Review of Third Party Analysis and EOG Mission Time OESC performed an owner's review of Reference 1 and concurred with the conservative methodology and conclusions regarding the capability of the EOG to perform its safety function in the as-found condition following the February 9, 2022, surveillance test (Reference 2). The transient analysis was performed using a revised and validated ETAP model which utilized disturbance durations derived from the February 9 troubleshooting oscilloscope data that were considered representative and bounding for the condition, even when postulated throughout the 24-hour MSPI mission time.
Model simulation results confirmed 'B' EOG frequency would remain within Reg. Guide 1.9 transient limits throughout all accident and load ranges with simulation results indicating margin to allow for a 194% increase in the duration of an open circuit. The model simulations assumed disturbances occurred at the most adverse conditions (i.e., lower loads and maximum frequency response for Open Circuit, and higher loads and minimum frequency response for Non-Open Circuit) to ensure analysis results provided the most conservative EOG frequency response. The simulation results show frequency oscillations would not challenge the engine overspeed trip setting at any point in time.
The duration of the disturbances increasing beyond the stated margin level is not considered credible given the governor control circuit was providing constant preload to prevent a significant increase in the duration of disturbances or permanent separation of the degraded Amphenol Connector Pin. This conclusion is supported by a total of approximately 9 hours of 'B' EOG operation across the entire load spectrum (0-100%) prior to the condition being corrected, and during which the fractured Governor Amphenol Connector Pin B did not permanently separate.


Serial No. 22-240A Attachment 1 Page 7 of 10 Furthermore, extrapolating the load oscillations over the 24-hour mission time indicates the transient load oscillations would not have exceeded the engine's manufacturer & design ratings. In summary, analysis results confirm the 'B' EOG would have remained in continuous operation without interruption by an overspeed trip or degradation detrimental to its operation and would have provided AC power to the required ESF loads throughout the duration of the 24-hour mission time.
Review of Third Pa rty Analysis and EOG Mission Time
Conclusions OESC cites the information above as a basis for disputing the apparent violation and the preliminary risk significance determination contained in the Attachment to the apparent violation (White). In summary, OESC provides the following discussion for disputing the apparent violation and risk evaluation results:
 
OESC performed an owner's review of Reference 1 and concurred with the conservative methodology and conclusions regarding the capability of the EOG to perform its safety function in the as-found condition following the February 9, 2022, surveillance test (Reference 2). The transient analysis was performed using a revised and validated ETAP model which utilized disturbance dur a tions derived from the Febru a ry 9 troubleshooting oscilloscope d a ta that were considered representative and bounding for the condition, even when postulated throughout the 24-hour MSPI mission time.
 
Model simulation results confirmed 'B' EOG frequency would remain within Reg. Guide 1.9 transient limits throughout all accident and load ra nges with simulation results indicating m a rgin to allow for a 194% increase in the duration of an open circuit. The model simula tions assumed disturbances occurred at the most adverse conditions (i.e., lower loads and maximum frequency response for Open Circuit, and higher loads and minimum frequency response for Non-Open Circuit) to ensure analysis results provided the most conservative EOG frequency response. The simulation results show frequency oscillations would not challenge the engine overspeed trip setting at any point in time.
 
The duration of the disturbances increasing beyond the stated margin level is not considered credible given the governor control circuit was providing const a nt preload to prevent a significant increase in the duration of disturbances or permanent sepa ration of the degra ded Amphenol Connector Pin. This conclusion is supported by a total of approximately 9 hours of 'B' EOG operation across the entire load spectrum (0-100%) prior to the condition being corrected, and during which the fra ctured Governor Amphenol Connector Pin B did not permanently separate.
Serial No. 22-240A Attachment 1 Page 7 of 10
 
Furthermore, extrapolating the load oscillations over the 24-hour mission time indicates the transient load oscillations would not have exceeded the engine's manufacturer & design ratings. In summary, analysis results confirm the 'B' EOG would have remained in continuous operation without interruption by an overspeed trip or degradation detrimental to its operation and would have provided AC power to the required ESF loads throughout the duration of the 24-hour mission time.
 
Conclusions
 
OESC cites the information above as a basis for disputing the apparent violation and the preliminary risk significance determination contained in the Attachment to the apparent violation (White). In summary, OESC provides the following discussion for disputing the apparent violation and risk evaluation results:
: 1. The Shift Manager conclusion that 'B' EOG remained operable on January 16, 2022, and that initiation of a condition report was not necessary was a reasonable conclusion considering the information available to the Shift Manager and Engineering organization after the completion of STP-125.002B on January 16, 2022. The Shift Manager determination of operability on January 16 is supported by the third-party analysis, which concludes the transients caused by the short-duration disturbances associated with the broken connector pin did not have an adverse impact on the safety function of the 'B' EOG or on its connected safety-related loads. This analysis provides a high degree of confidence the 'B' EOG was operable during the period from January 16, 2022, through February 9, 2022, and was in full compliance with RG 1.9, and the VCS TS.
: 1. The Shift Manager conclusion that 'B' EOG remained operable on January 16, 2022, and that initiation of a condition report was not necessary was a reasonable conclusion considering the information available to the Shift Manager and Engineering organization after the completion of STP-125.002B on January 16, 2022. The Shift Manager determination of operability on January 16 is supported by the third-party analysis, which concludes the transients caused by the short-duration disturbances associated with the broken connector pin did not have an adverse impact on the safety function of the 'B' EOG or on its connected safety-related loads. This analysis provides a high degree of confidence the 'B' EOG was operable during the period from January 16, 2022, through February 9, 2022, and was in full compliance with RG 1.9, and the VCS TS.
: 2. The NRC Risk Evaluation assumptions are overly conservative when compared to the conclusions of Reference 1 and discussion above. Reference 1 concludes the disturbances associated with the broken connector pin were of short duration and did not have an adverse impact on the safety function of the 'B' EOG or on its connected safety-related loads. The NRC Risk Evaluation assumes that the broken pin would have resulted in the EOG's inability to maintain constant loading in isochronous mode.
: 2. The NRC Risk Evaluation assumptions are overly conservative when compared to the conclusions of Reference 1 and discussion above. Reference 1 concludes the disturbances associated with the broken connector pin were of short duration and did not have an adverse impact on the safety function of the 'B' EOG or on its connected safety related loads. The NRC Risk Evaluation assumes that the broken pin would have resulted in the EOG's inability to maintain constant loading in isochronous mode.
The Corrective Steps that have been Taken and Results Achieved Following the February 9, 2022, surveillance test, CR1191016 was written for the observed 'B' EOG oscillations and to create an action for engineering's review. An initial corrective action to perform a common cause on the 'A' EOG (CA 10894246) determined there was no concern that the kW oscillation condition for 'B' EOG was also present on the 'A' EOG. Therefore, there was no requirement to start the 'A' EOG per TS 3.8.1.1, Action b.2. However, Operations conservatively decided to perform a start of the 'A' EOG to verify it did not have a similar condition. Engineering also observed the start of the 'A' EOG, per STP-125.002A, to support the common cause determination. There were no abnormalities observed during this surveillance test. Observations included fuel rack movement, local panel frequency indication,
 
The Corrective Steps that have been Taken and Results Achieved


Serial No. 22-240A Attachment 1 Page 8 of 10 and governor oil level before and during the run. Additionally, CA 10984866 was written to perform a level of effort evaluation to determine the cause of the 'B' EOG oscillations.
Following the February 9, 2022, surveillance test, CR1191016 was written for the observed 'B' EOG oscillations and to create an action for engineering's review. An initial corrective action to perform a common cause on the 'A' EOG (CA 10894246) determined there was no concern that the kW oscillation condition for 'B' EOG was also present on the 'A' EOG. Therefore, there was no requirement to start the 'A' EOG per TS 3.8.1.1, Action b.2. However, Operations conservatively decided to perform a start of the 'A' EOG to verify it did not have a similar condition. Engineering also observed the start of the 'A' EOG, per STP-125.002A, to support the common cause determination. There were no abnormalities observed during this surveillance test. Observations included fuel rack movement, local panel frequency indication, Serial No. 22-240A Attachment 1 Page 8 of 10
To repair the 'B' EOG kW oscillating condition, Work Order 88201648997 was written and successfully implemented on February 10, 2022, to replace the Amphenol connector. To prevent a potential similar condition on the 'A' EOG, Work Order 88201667470 was implemented on May 23, 2022, to replace the same Amphenol connector.
 
Corrective Steps that will be Taken To prevent recurrence, several corrective actions (CA) were initiated as part of the causal evaluation (CA 10984866). CA 11178458 was initiated for Engineering to present an EOG Amphenol Strain Relief Plant Health Working Group Presentation requesting approval to develop and issue a design change that incorporates strain relief on the governor control signal wires for the 'A' and 'B' EOG mechanical governor Amphenol connectors. This was presented to the Plant Health Work Group on July 18, 2022, and Plant Health Steering Committee on August 9, 2022. CA 11178463 and CA 11178465 were initiated to track implementation of the 'B' and 'A' EOG strain relief design changes, respectively. Both actions have a current due date of June 1, 2023.
and governor oil level before and during the run. Additionally, CA 10984866 w a s written to perform a level of effort evaluation to determine the cause of the 'B' EOG oscillations.
Additionally, Department Tracking Items (DTI), which are not corrective actions, were initiated as program enhancements. One DTI is to revise the DG System Monitoring Plan to incorporate kW and KVAR trending during EOG monthly surveillance testing, including acceptance bands and trigger values for taking action per ER-AA-SYS-1003 (CA 11178468 is due November 16, 2022). Another DTI was initiated to share this Operating Experience event with l&C and Electrical Maintenance technicians (CA 11178469).
 
Date when Full Com pliance will be Achieved Full compliance with RG 1.9 and VCS TS was maintained throughout the time frame of January 16, 2022, through February 9, 2022. The vendor's report supports this operability determination.
To repa ir the 'B' EOG kW oscillating condition, Work Order 88201648997 was written and successfully implemented on February 10, 2022, to replace the Amphenol connector. To prevent a potential similar condition on the 'A' EOG, Work Order 88201667470 was implemented on May 23, 2022, to replace the same Amphenol connector.
 
Corr e c tive Steps th a t w ill be T a ke n
 
To prevent recurrence, several corrective actions (CA) were initiated as part of the causal evaluation (CA 10984 866). CA 11178458 w a s initiated for Engineering to present an EOG Amphenol Strain Relief Plant Health Working Group Presentation requesting a pproval to develop and issue a design change that incorporates strain relief on the governor control signal wires for the 'A' and ' B' EOG mechanical governor Amphenol connectors. This was presented to the Plant Hea lth Work Group on July 18, 2022, and Plant Health Steering Committee on August 9, 2022. CA 11178463 a nd CA 11178465 were initiated to tra ck implementation of the 'B' and 'A' EOG strain relief design changes, respectively. Both a ctions have a current due date of June 1, 2023.
 
Additionally, Department Tracking Items (DTI), which are not corrective actions, were initiated as program enhancements. One DTI is to revise the DG System Monitoring Plan to incorporate kW and KVAR trending during EOG monthly surveillance testing, including a cceptance bands and trigger values for taking action per ER-AA-SYS-1003 (CA 11178468 is due November 16, 2022). Another DTI was initiated to share this Operating Experience event with l&C and Electrical Maintenance technicians (CA 11178469).
 
Date whe n Full Com p lia nc e will be Achi e v e d
 
Full compli a nce with RG 1.9 and VCS TS was m a intained throughout the time frame of January 16, 2022, through February 9, 2022. The vendor's report supports this operability determina tion.


==References:==
==References:==
: 1. MPR Report 0310-0049-RPT-001, "Evaluation of the Impact of Degraded Governor Electrical Connection on 8-EDG Voltage and Frequency," Revision 1 (Proprietary).
: 1. MPR Report 0310-0049-RPT-001, "Evaluation of the Impact of Degraded Governor Electrical Connection on 8-EDG Voltage and Frequency," Revision 1 (Proprietary).
: 2. CR1191016, MSPI Evaluation, PAMS Assignment CA 10997282
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(Vcsns), Unit 1 - Response to an Apparent Violation (EA-22-039)
ML22236A117
Person / Time
Site: Summer South Carolina Electric & Gas Company icon.png
Issue date: 08/22/2022
From: Stoddard D
Dominion Energy South Carolina
To:
Document Control Desk, Office of Nuclear Reactor Regulation, NRC Region 1
References
22-240A, EA-22-039 IR 2022001-01
Download: ML22236A117 (12)
v • d • e


Text

Dom in io n En ergy So uth Ca ro lin a, In c. ::F\\ Dominion 5000 Dom inion Bou le va rd, Glen A llen, VA 23 0 60 Dom in ion En ergy.com ii a,,, Energy@

August 22, 2022

Serial No.: 22 -240A Document Control Desk VCS - LIC/MM: RO U.S. Nuclear Regulatory Commission Docket No.: 50 - 395 Washington, DC 20555 License No.: NPF-12

DOM I NION ENERG Y SO UTH CARO LI NA ( DESC )

VI RG IL C. S U MMER NUC L EAR ST A TI ON (V CSNS ) U N IT 1 RESP O NSE TO AN APPAREN T VIOL A T ION : ( EA-22-0 39 )

By letter dated May 12, 2022 (Reference 1 ), the Nuclear Regulatory Commission (NRC) notified Dominion Energy South Carolina (D ESC) of an Apparent Violation (AV 05000395/2022001 -01) for "Failure to Correct Condition Adverse to Quality Resulting in Inoperable Emergency Diesel Generator." By letter dated July 14, 2022 (Reference 2),

the NRC preliminarily determined the finding to be of low to moderat e safety significance (White) and provided an opportunity for DESC to submit a pre-decisional response to the AV. By letter dated July 19, 2022, DESC informed the NRC that additional written information would be provided for consideration in making a final determination for the AV (Reference 3).

The additional information is provided as Attachment 1 to this letter. This information provides DESC's perspective of the significance of the finding and related facts used to reach our determination.

Should you have any questions regarding this submittal or require additional information, please contact Mr. Michael Moore, Manager Nuclear Station Licensing at (803) 345 -4752.

Sincerely,

Daniel G. Stoddard Senior Vice President and Chief Nuclear Officer CRA IG D SLY Commonw ea lth Not a ry Public of Virg in ia

COMMONWEAL TH OF VIRGINIA R eg. # 75 18653 My Commi ssio n Ex pires Dec em be r 31, 20~

COUNTY OF HENRICO

The foregoing document was acknowledged before me, in and for the County and Commonwealth aforesaid, today by Daniel G.

Stoddard, who is Senior Vice President and Chief Nuclear Officer of Dominion Energy South Carolina. He has affirmed before me that he is duly authorized to execute and file the foregoing document in behalf of that company, and that the statements in the document are true to the best of his knowledge and belief.

Acknowledged before me this...frL_ day of ""J U JL-~*B~[) A _.,_ 022.

My Commission Expires: JZ. /31/i..i ~

'=-I-', c..:.,,i-=;;...____ ~ Public Serial No. 22-240A Docket No. 50-395 Page 2 of 2

References:

1. "Virgil C. Summer - Integrated Inspection Report 05000395/2022001 and Apparent Viol a tion," dated May 12, 2022.
2. "Virgil C. Summer - NRC Inspection Report 05000395/2022090 and Preliminary White Finding and Apparent Violation," dated July 14, 2022.
3. "Virgil C. Summer Nuclear Station (VCSNS) Unit 1 - Pre-Decisional Reply to Apparent Violation 05000395/2022001 - 01," dated July 19, 2022.
Response to Apparent Violation 05000395/2022001 - 01

Commitments contained in this letter: None

cc: G. J. Lindamood - Santee Cooper L. Dudes - NRC Region II D. Dumbacher - NRC Region II G. E. Miller - NRC Project Mgr.

NRC Resident Inspector Serial No. 22-240A Attachment 1 Page 1 of 10

Attachment 1

RESPONSE TO APPARENT VIOLATION 05000395/2022001-01 Serial No. 22-240A Attachment 1 Page 2 of 10

VIRGIL C. SUMMER NUCLEAR STATION (VCSNS)

DOMINION ENERG Y SOUTH CAROLINA, INC. (DESC)

RESPONSE TO APPARENT VIOLATION 0500039512022001-01

Apparent Violation 0500039512022001-01

An NRG-identified Apparent Violation of 10 CFR 50, Appendix B, Criterion XVI, was identified for the licensee failing to correct a condition adverse to quality resulting in the inoperability of the

'B' emergency diesel generator (EDG). Specifically, there were indications of erratic governor performance following the January 2022 maintenance package that were identified during testing January 16, 2022. The governor performance was also erratic during the February 9, 2022, surveillance test, after which the licensee declared the EDG inoperable. As a result of this condition, the 'B' EDG was inoperable for a time in excess of its Technical Specification (TS) allowed outage time.

DESC's Response

Introduction

During post-maintenance testing after a January 15, 2022 '8' EOG maintenance package, erratic oscillations of frequency and kW were determined to have been caused by a detached tachometer signal generator. Following troubleshooting and repair of the signal generator, the oscillations were significantly reduced, and a successful surveillance test was completed on January 16, 2022. Based on field observations and the results of the January 16 surveillance test after the signal generator was repaired, the Shift Manager concluded '8' EOG was operable with the significantly reduced oscillations.

During a subsequent monthly surveillance test on February 9, 2022, the '8' EOG again met the TS surveillance test criteria, although the number of minor oscillations experienced during the February 9 'B' EOG run had increased when compared to the oscillations experienced during the January 16 surveillance test. After reviewing the information from the February 9 surveillance test, Engineering did not support a recommendation of continued operability and the Shift Manager declared the '8' EOG inoperable based on that recommendation. A broken Amphenol connection was subsequently identified as the cause of the oscillations and repaired.

An independent third-party engineering firm specializing in EOG analysis was contracted to review data from the February 2022 test to determine if the '8' EOG could have provided emergency power to the 1 E onsite busses during a loss of offsite power in the as-found condition.

The resulting evaluation (Reference 1) concludes that the '8' EOG transient performance limits in Regulatory Guide 1.9 (RG 1.9) were maintained, and the oscillations did not have an adverse impact on the safety function of the 'B' EOG or on its connected safety-related loads.

Serial No. 22-240A Attachment 1 Page 3 of 10

=

Background===

On January 10, 2022, the 'B' EOG was removed from service for a significant maintenance package and was originally scheduled to return to service on January 13, 2022. The restoration of 'B' EOG was delayed until January 16, 2022, due to a number of conditions as noted below:

  • CR-22-00134: The 'B' EOG had erratic indications of frequency and kW. [Dated January 15, 2022, at 03:55]
  • CR-22-00136: The 'B' EOG mechanical overspeed trip device did not reset properly resulting in an engine trip. [Dated January 15, 2022, at 07:44]
  • CR-22-00139: The 'B' EOG signal generator came off the governor tachometer drive shaft. [Dated January 15, 2022, at 19:20]

On January 15, during performance of a post-major maintenance test per SOP-306, "EMERGENCY DIESEL GENERATOR," Operations noted abnormal frequency oscillations and large kW swings at the 1,000 kW and 2,300 kW load plateaus. Figure 1, '"B' EOG Maintenance Run - January 15, 2022," provides an illustration of the kW oscillations. As a result, Operations secured the diesel after about 30 minutes and generated CR-22-00134.

On January 16, the cause of the abnormal frequency and kW condition identified in CR-22-00134 was identified as being due to the 'B' EOG tachometer signal generator becoming disconnected due to inadequate clamping force on its bushing. The condition was corrected by reattaching the 'B' EOG tachometer signal generator using a satisfactory bushing. The 'B' EOG was then operated on the mechanical governor to allow adjustment of the governor high-speed setting and venting of any air that may have been in the governor.

On January 16, 2022, at 03:50, after completion of the high-speed setting adjustment run, Operations started 'B' EOG per SOP-306. During this 3-hour test, there were no oscillations identified by field personnel. However, Operators in the Control Room observing the main control board noted minor oscillations occurred during the fully loaded portion of the test. Figure 2, '"B' EOG Loaded Maintenance Run - January 16, 2022," provides an illustration of the oscillations. The results of the January 16 test showed that the significant oscillations noted during the January 15 test were mostly eliminated and supported a conclusion that the issue in CR-22-00134 had been identified and corrected by reattaching the tachometer signal generator using a satisfactory bushing. The minor oscillations observed during this test were attributed to winter weather causing grid disturbances and potentially small amounts of air venting from the governor after maintenance.

On January 16, 2022, at 21 :29, Operations started 'B' EOG per STP-125.002B, "DIESEL GENERA TOR B OPERABILITY TEST'. During this surveillance test, the Control Room operators noted minor fluctuations in 'B' EOG kW output on the main control board. Additionally, field personnel observed occasional movements in the fuel rack, although much less severe and with different characteristics than the condition identified in CR-22-00134. These fluctuations were believed to be due to winter weather causing grid disturbances and potential governor air venting as described above. The same Shift Manager who ordered the EOG secured and Serial No. 22-240A Attachment 1 Page 4 of 10

declared the EOG inoperable on January 15 during the post-major maintenance test, had no operability concern after this surveillance test. The 'B' EOG met the STP-125.0028 acceptance criteria during this test, including the criteria described below associated with the kW load-range and frequency deviations.

  • Step 8.1.e: The Diesel Generator must be able to accept a load of between 4150 kW and 4250 kW and operate for at least 60 minutes within this band (T.S. 4.8.1.1.2.a.4).

IYR01805, EMERGENCY DIESEL GEN B RW1, (XCP-6221) power data averaged over a ten-minute period is used to monitor this requirement; instantaneous readings are not required to be in this band.

  • Step 8.4.e: Steady-state, no-load, frequency deviations are 0.2 hertz or less from the average isochronous speed by both Local and MCB indication.

On February 9, 2022, during the monthly STP-125.0028 test of 'B' EOG, kW oscillations were noted in the Control Room while the 'B' EOG was synchronized with the grid. Figure 3: "'B' EOG Surveillance Run - February 9, 2022," provides an illustration of the kW oscillations. The magnitude of the oscillations and quick recovery to normal appeared to be similar to the January 16 STP-125.0028 test. Oscillations increased in frequency at the end of the test but were not considered by the Shift Manager to be a substantial concern or a challenge to diesel operability.

Local field observation noted normal engine operation, other than periodic fuel rack movement similar to the January 16 test. The 'B' EOG again met all STP-125.0028 acceptance criteria.

The Shift Manager determined there was reasonable assurance the diesel could perform its design basis function and was operable. Operations generated CR1191016 to document intermittent 'B' EOG kW oscillations and requested an Operability review from Engineering.

Engineering reviewed the test data, observed the increase in the frequency of kW oscillations, and communicated to Operations that they did not have reasonable assurance that the 'B' EOG could perform its function at that time due to the increasing number and magnitude of the oscillations. This was a judgement call from the Diesel Generator System Engineer based on qualitative analysis of the data.

Subsequent troubleshooting confirmed the 'B' EOG load oscillations were caused by an intermittent open circuit and variable high resistance condition due to a mechanical fatigue fracture of the solder contact at the Pin B location within an Amphenol 90-degree angle plug connector. The broken pin was interrupting the electronic governor 2301A control output signal to the engine-mounted EGB-50P proportional governor/actuator. The broken pin was in the Pin B location, which provides the return path for the electronic governor signal to the actuator. After installation of a new Amphenol connector, the 'B' EOG tested satisfactorily.

Due to concerns related to the 'B' EOG, DESC contracted a third-party engineering firm, specializing in EOG analysis, to evaluate the impact of the intermittent governor electrical connection.

Serial No. 22-240A Attachment 1 Page 5 of 10

Reason for the Violation

Determination of Operability

The 'B' EOG oscillations experienced during testing on January 16, 2022, did not result in the

'B' EOG being declared inoperable. The Shift Manager determined that the 'B' EOG was operable on January 16 after performance of STP-125.0028 due to the following:

  • The significant load and frequency oscillations due to the disconnected tachometer signal generator had been corrected on January 16.
  • The 'B' EOG met the acceptance criteria of STP-125.0028
  • The load and frequency oscillations were not substantive in comparison to the STP-125.0028 acceptance criteria and review of operational parameters. Additionally, the oscillations were believed to be due to winter weather at this time causing grid disturbances and potentially small amounts of air venting from the governor after maintenance.

The Shift Manager's perspective was the 'B' EOG oscillations were minor and without adverse impacts, providing reasonable assurance of operability. Therefore, based on the judgement of the Shift Manager, 'B' EOG was declared operable on January 16 after performance of STP-125.0028 and a CR was not deemed to be required. DESC believes that this conclusion was reasonable considering the information available to the Shift Manager and the engineering organization after the completion of STP-125.0028 on January 16, 2022.

NOTE: The trend graph referenced in Apparent Violation 05000395/2022001-01 is from the plant computer system, which is reviewed for information only. This trend graph is not part of STP-125.0028, is not reviewed by the Shift Manager, and therefore not required for EOG operability.

Amphenol Connector Pin Failure

After the EOG was declared inoperable on February 9, 2022, troubleshooting confirmed the 'B' EOG load oscillations were caused by an intermittent open circuit and variable high resistance condition (referred to as "disturbances") due to a mechanical fatigue fracture of the solder contact at the Pin 8 location within an Amphenol 90-degree angle plug connector. This solder contact had been subjected to long-term alternating stress because of a design configuration that included no strain relief for the two 16-gauge wires utilized for governor control signal circuit DGU178.

Additional stress to the solder contacts would likely have occurred during the January 2022 performance of MMP-180.039 (EOG Engine Dynamic Check of Overspeed Governor) and troubleshooting associated with the separate frequency and kW oscillation condition identified on January 15 and documented in CR-22-00134. These maintenance activities were performed properly and with proper care; however, they potentially imparted sufficient additional stress to the fatigue weakened Pin B solder contact to result in the final fast fracture of the solder contact.

Serial No. 22-240A Attachment 1 Page 6 of 10

After the solder contact fractured, it was prevented from permanently separating by the physical constraints within the Amphenol connector as well as the constant preload provided by the governor control circuit conduit. This condition resulted in kW oscillations at high loads during subsequent e ngine runs.

Third Party Analysis

An independent third-party engineering firm specializing in EOG analysis was contracted to determine if the 'B' EOG could have provided emergency power to the 1 E onsite busses during a loss of offsite power in the as-found condition. The resulting evalu a tion determined tha t the disturbances associated with the broken connector pin were of short dur a tion a nd it is appropriate to consider the transient performance limits in Regulatory Guide 1.9.

The resulting eva lua tion determined that EOG 'B' transient performance limits in Regulatory Guide 1.9 (RG 1.9) for frequency (between 57 Hz and 64.5 Hz) and recovery time to within the required transient recovery band(+/ - 1.2 Hz of nominal within 40 percent of the load sequence time) were maintained. The evaluation concludes that the transients (oscillations) caused by the short-duration Pin B disturba nces did not have an adverse impact on the safety function of the

'B' EOG or on its connected safety-rela ted loads (Reference 1 ). Reference 1 will be made available to the NRC for review.

Review of Third Pa rty Analysis and EOG Mission Time

OESC performed an owner's review of Reference 1 and concurred with the conservative methodology and conclusions regarding the capability of the EOG to perform its safety function in the as-found condition following the February 9, 2022, surveillance test (Reference 2). The transient analysis was performed using a revised and validated ETAP model which utilized disturbance dur a tions derived from the Febru a ry 9 troubleshooting oscilloscope d a ta that were considered representative and bounding for the condition, even when postulated throughout the 24-hour MSPI mission time.

Model simulation results confirmed 'B' EOG frequency would remain within Reg. Guide 1.9 transient limits throughout all accident and load ra nges with simulation results indicating m a rgin to allow for a 194% increase in the duration of an open circuit. The model simula tions assumed disturbances occurred at the most adverse conditions (i.e., lower loads and maximum frequency response for Open Circuit, and higher loads and minimum frequency response for Non-Open Circuit) to ensure analysis results provided the most conservative EOG frequency response. The simulation results show frequency oscillations would not challenge the engine overspeed trip setting at any point in time.

The duration of the disturbances increasing beyond the stated margin level is not considered credible given the governor control circuit was providing const a nt preload to prevent a significant increase in the duration of disturbances or permanent sepa ration of the degra ded Amphenol Connector Pin. This conclusion is supported by a total of approximately 9 hours1.041667e-4 days <br />0.0025 hours <br />1.488095e-5 weeks <br />3.4245e-6 months <br /> of 'B' EOG operation across the entire load spectrum (0-100%) prior to the condition being corrected, and during which the fra ctured Governor Amphenol Connector Pin B did not permanently separate.

Serial No. 22-240A Attachment 1 Page 7 of 10

Furthermore, extrapolating the load oscillations over the 24-hour mission time indicates the transient load oscillations would not have exceeded the engine's manufacturer & design ratings. In summary, analysis results confirm the 'B' EOG would have remained in continuous operation without interruption by an overspeed trip or degradation detrimental to its operation and would have provided AC power to the required ESF loads throughout the duration of the 24-hour mission time.

Conclusions

OESC cites the information above as a basis for disputing the apparent violation and the preliminary risk significance determination contained in the Attachment to the apparent violation (White). In summary, OESC provides the following discussion for disputing the apparent violation and risk evaluation results:

1. The Shift Manager conclusion that 'B' EOG remained operable on January 16, 2022, and that initiation of a condition report was not necessary was a reasonable conclusion considering the information available to the Shift Manager and Engineering organization after the completion of STP-125.002B on January 16, 2022. The Shift Manager determination of operability on January 16 is supported by the third-party analysis, which concludes the transients caused by the short-duration disturbances associated with the broken connector pin did not have an adverse impact on the safety function of the 'B' EOG or on its connected safety-related loads. This analysis provides a high degree of confidence the 'B' EOG was operable during the period from January 16, 2022, through February 9, 2022, and was in full compliance with RG 1.9, and the VCS TS.
2. The NRC Risk Evaluation assumptions are overly conservative when compared to the conclusions of Reference 1 and discussion above. Reference 1 concludes the disturbances associated with the broken connector pin were of short duration and did not have an adverse impact on the safety function of the 'B' EOG or on its connected safety related loads. The NRC Risk Evaluation assumes that the broken pin would have resulted in the EOG's inability to maintain constant loading in isochronous mode.

The Corrective Steps that have been Taken and Results Achieved

Following the February 9, 2022, surveillance test, CR1191016 was written for the observed 'B' EOG oscillations and to create an action for engineering's review. An initial corrective action to perform a common cause on the 'A' EOG (CA 10894246) determined there was no concern that the kW oscillation condition for 'B' EOG was also present on the 'A' EOG. Therefore, there was no requirement to start the 'A' EOG per TS 3.8.1.1, Action b.2. However, Operations conservatively decided to perform a start of the 'A' EOG to verify it did not have a similar condition. Engineering also observed the start of the 'A' EOG, per STP-125.002A, to support the common cause determination. There were no abnormalities observed during this surveillance test. Observations included fuel rack movement, local panel frequency indication, Serial No. 22-240A Attachment 1 Page 8 of 10

and governor oil level before and during the run. Additionally, CA 10984866 w a s written to perform a level of effort evaluation to determine the cause of the 'B' EOG oscillations.

To repa ir the 'B' EOG kW oscillating condition, Work Order 88201648997 was written and successfully implemented on February 10, 2022, to replace the Amphenol connector. To prevent a potential similar condition on the 'A' EOG, Work Order 88201667470 was implemented on May 23, 2022, to replace the same Amphenol connector.

Corr e c tive Steps th a t w ill be T a ke n

To prevent recurrence, several corrective actions (CA) were initiated as part of the causal evaluation (CA 10984 866). CA 11178458 w a s initiated for Engineering to present an EOG Amphenol Strain Relief Plant Health Working Group Presentation requesting a pproval to develop and issue a design change that incorporates strain relief on the governor control signal wires for the 'A' and ' B' EOG mechanical governor Amphenol connectors. This was presented to the Plant Hea lth Work Group on July 18, 2022, and Plant Health Steering Committee on August 9, 2022. CA 11178463 a nd CA 11178465 were initiated to tra ck implementation of the 'B' and 'A' EOG strain relief design changes, respectively. Both a ctions have a current due date of June 1, 2023.

Additionally, Department Tracking Items (DTI), which are not corrective actions, were initiated as program enhancements. One DTI is to revise the DG System Monitoring Plan to incorporate kW and KVAR trending during EOG monthly surveillance testing, including a cceptance bands and trigger values for taking action per ER-AA-SYS-1003 (CA 11178468 is due November 16, 2022). Another DTI was initiated to share this Operating Experience event with l&C and Electrical Maintenance technicians (CA 11178469).

Date whe n Full Com p lia nc e will be Achi e v e d

Full compli a nce with RG 1.9 and VCS TS was m a intained throughout the time frame of January 16, 2022, through February 9, 2022. The vendor's report supports this operability determina tion.

References:

1. MPR Report 0310-0049-RPT-001, "Evaluation of the Impact of Degraded Governor Electrical Connection on 8-EDG Voltage and Frequency," Revision 1 (Proprietary).
2. CR1191016, MSPI Evaluation, PAMS Assignment CA 10997282 0 § § § "T1 § " w.. § 01/16/2203: 30:00 cc ~ § i § ~ § 01/16/22 03:35:00 8 01/16/22 03:40:00 C 0 "T1 01/16/22 03:45:00... 01/15/22 00:25:55 ca
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