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{{#Wiki_filter:)IRC Form 366              U.S. NUCLEAR REGULATORY COMMISSION                                APPROVED BY OMB NO. 31604104                EXPIRES 06r30/2001 (6-1998)                                                                                    ESTFIIATED BURDEN PER RESPONSE TO COMPLY WITH THIS MANDATORY INFORMATION COLLECTION REOVEST: 500 HRS. REPORTED LESSONS LEARNED ARE INCORPORATED INTO THE LICENQNG PROCESS AND FED BACK TO INDUSTRY.
LICENSEE EVENT REPORT (LER)                                            FORWARD COATUENTS REGARDING BURDEN ESTIMATE TO THE INFORMATION AND RECORDS MANAGEMENT BRANCH Irar Fss). V.S. NUCLEAR REGVIATORY CoseaISSION. WASHINGTON. DC 20555OXI. AND TO THE PAPERWORK REDVCTION PR<MECT ISI500101L OFFICE OF MANAGEMENT AND BUDGET. WASIeNGTON. OC (See reverse for required number of                              20505 digits/characters for each block)
FACILITYNAME (I )                                      II DOCKET NUMBER I2)                        PAGE IS)
Cook Nuclear Plant Unit 1                                          05000-315                              1  of3 TITLE I4)
Air System for Emergency Diesel Generators (EDG) May Not Support Long Term Operability Due to Original Design Error EVENT DATE (6)                        LER NUMBER (6)                    REPORT DATE (7)                    OTHER FACILITIES INVOLVED (8)
FACILllYNAME                        DOCKEr NUMBER SEQUENTIAL      REVISION                                        Cook Unit 2                        05000-316 MONTH        DAY      YEAR      YEAR        NUMBER        NUMBER      MONTH        DAY      YEAR FACIUTY NAM                        DOCKET NUMBER 04          07      1999      1999            011          00        05          04      1999 OPERATING                      THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR g: (Check one or mor e) (11)
MODE (9)                        20.2201 (b)                      20.2203(a)(2)(v)                        50.73(a)(2)(i)                  50.73(a)(2)(viii)
POWER                          20.2203(a)(1)                    20.2203(a)(3)(i)                        50.73(a)(2)(ii)                  50.73(a)(2)(x)
LEVEL (10)          00                                                                                                                    73.71 20.2203(a)(2)(i)                20.2203(a)(3)(ii)                      50.73(a)(2)(iii) 20.2203(a)(2)(ii)                20.2203(a)(4)                          50.73(a)(2)(iv)                  OTHER 20.2203(a)(2)(iii)              50.36(c)(1)                            50.73(a)(2)(v)
Specity in Abstract below 20.2203(a)(2)(iv)                50.36(c)(2)                            50.73(a)(2)(vii)            or n NRC Form 366A UCENSEE CONTACT FOR THIS LER (12)
NAME                                                                                                  TELEPHONE NUMBER 01Ktvde Area Code)
Ms. M. B. Depuydt, Compliance Engineer                                                    616/465-5901, x1 589 COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT (13)
REPORTABLE                                                                                REPORTABLE TO CAUSE        SYSTEM      COMPONENT    MANUFACTURER      TO EPIX                                      coM poNENT        MANUFACTURER                  EPIX E
SUPPLEMENTAL REPORT EXPECTED 14                                        EXPECTED                      MONTH                          YEAR X      YES                                                                                  SUBMISSION                        07            01            1999 If Yes, corn lete EXPECTED SUBMISSION DATE                                            DATE 15 Abstract (Umit to 1400 spaces, I.e., approximately 15 single-spaced typewritten lines) (16)
In February 1999, during the Expanded System Readiness Review of the Emergency Diesel Generator (EDG) system, the ability of the starting air/control air system to support long term operability of the EDGs was questioned due to the non-safety related design of the compressors. An operability determination was performed which concluded that the EDGs could not maintain long term operability without reliance on the non-safety related, non-seismic starting air compressors, and were therefore inoperable. On April 7, 1999 an ENS notification was made in accordance with 10CFR50.72(b)(2)(I),
for an unanalyzed condition with potential safety significance.
The apparent cause of the inadequacy of the EDG starting/control air system is original design error. The designers apparently failed to consider that the starting air system provides the control air to the EDG, and loss of air could result in shutdown of the engine. A temporary modification to supply makeup air capability in Modes 5 and 6 is being prepared.
Options for the permanent solutions are currently under review and the method selected will be implemented via a design change prior to restart of each unit.
The control air leakage rate and expected EDG run time without makeup air capability has not yet been quantified for the current system configuration. Testing is being conducted as part of the proposed temporary modification to quantify the expected leakage rate. Once the leakage rate is known, the results will be evaluated to determine the safety significance of the identified condition.
9'2)05ii0294 '2)'2)0504 PDR          ADOCK 050003% 5 8                                PDR
 
0 NRC FORM 366A            U.S. NUCLEAR REGULATORY COMMISSION (6-1998)
LICENSEE EVENT REPORT (LER)
TEXT CONTINUATION FACILITYNAME (1)                                                DOCKET NUMBER(2)        LER NUMBER (6)            PAGE (3)
YEAR    SEQUENTIAL    REVISION Cook Nuclear Plant Unit 1                            05000-315              NUMBER      NUMBER        2of3 1999        011        00 TEXT (ifmore space is required, use additional copies of NRC Form (366A) (11)
Conditions Prior to Event Unit 1 was in Mode 5, Cold Shutdown Unit 2 was in Mode 5, Cold Shutdown Descri tion of Event On February 18, 1999, during the Expanded System Readiness Review of the Emergency Diesel Generator (EDG) system, the ability of the starting air/control air system to support long term operability of the EDGs was questioned due to the non-safety related design of the compressors.                              I The compressois, compressor drive motors, the piping between each compressor and the respective discharge check valve are not safety related components. Although the EDG starting air compressors are supplied from a Class 1E power source and are anchored per Seismic Class 1 criteria, they are neither safety related, or seismically qualified.
When this question arose, Operations requested additional information from Engineering, which led to an operability determination being performed. The determination considered the design function of the EDGs, the starting air compressors and the control air function of the starting air system. Central to the determination is the design function of the control air for the EDG, which is discussed in detail in the Analysis section of the LER, and the "mission time" or how long the EDGs would need to run after an accident.
In the course of performing the operability determination, no finite statement could be found in the design or licensing basis documentation that defined the mission time of the EDGs. A decision was made to use a value of seven days, which is supported by the Technical Specification requirements for the amount of fuel oil that is required to be on hand to run the EDGs.
Using this information, the operability determination concluded that the EDGs could not maintain long term operability without reliance on the non-safety related, non-seismic starting air compressors and were therefore inoperable.
Cause of Event The cause of this event was a design deficiency in the EDG and its supporting systems that occurred during original plant design. The designers apparently failed to consider that the starting air system provides the control air to the EDG, and loss of control air could result in shutdown of the engine. Although the EDG starting air compressors are supplied from a Class 1E power source and are anchored per Seismic Class I criteria, they might not function in a seismic event because of their lack of qualification. The EDG air system was modiTied in 1994 and replacement compressors were installed, however, the replacement compressors were also classified non-safety.
Anal sis of Event On April 7, 1999, 'at 1501 hours EDT, an ENS notification was made in accordance with 10 CFR 50.72(b)(2)(i), any event found while the reactor is shut down, that, had it been found while the reactor was in operation, would have resulted in the.
nuclear power plant being in an unanalyzed condition that significantly compromises plant safety. This LER is therefore submitted in accordance with 10 CFR 50.73(a)(2)(ii)(A), for the same criteria.
The EDG system is a safety related system that provides reliable and readily available onsite AC power in the event of the loss of offsite power supply to the essential loads necessary to safely shutdown the reactor under any normal operating or accident conditions. The EDGs are designed to start automatically upon receipt of a safety injection signal and/or a loss of offsite power signal and be ready to accept loads within 10 seconds of receiving a start signal.
The starting air system supplies compressed air for starting the EDG. Each EDG has its own starting air system consisting of two redundant starting air compressors. Each compressor has one receiver of sufficient volume, 285 cubic feet, for at NRC FORM 366A (6-1998)
 
NRC FORM 366A            U.S. NUCLEAR REGULATORY COMMISSION (6-1998)
LICENSEE EVENT REPORT (LER)
TEXT CONTINUATION FACILITYNAME (1)                                                DOCKET NUMBER(2)      LER NUMBER (6)              PAGE (3)
YEAR  SEQUENTIAL      REVISION Cook Nuclear Plant Unit 1                            05000-315            NUMBER        NUMBER        3 of 3 1999      011            00 TEXT (Ifmore space Is required, use additional copies of NRC Form (366A) (17) least two EDG start attempts when pressurized to 220 psig. Each of the two starting air trains supplies starting air within the pressure range of 220 to 247.5 psig. Both starting air trains are independently actuated by the diesel engine control system upon receipt of an EDG start signal. If either compressor/receiver should fail the other is capable of starting the EDG. The system is designed to have the EDG at speed and ready to accept load within.10 seconds of start initiation.
The starting air system also provides compressed air for the starting air supply valve actuators, the diesel engine control system and the turbocharger aftercooler cooling water regulating valves.
The starting air system consists of two independent trains of one air compressor and one air receiver each. Each starting air receiver is replenished by its associated starting air compressor that cycles as necessary to maintain the receiver air pressure between 220 and 247.5 psig. The air receivers also supply the diesel engine pneumatic controlsystem with 100 psig air via pressure reducing valves. The 100 psig engine control air is required to maintain the throttle control cylinder's actuating rod retracted and thus maintain fuel flow to the engine. The minimum control air pressure required to maintain the throttle control cylinder's actuating rod fully retracted is 60 psig.
Ifthe starting air compressors are unavailable to replenish the air receivers following an EDG start, the volume of air remaining to supply the control air requirements is limited. Based on pre-operational test data, starting air receiver pressure could range from 188 to 132 psig following an emergency start. It was postulated that the leakage from the system would result in a loss of air receiver pressure of approximately 25 psi in a twelve hour period. At this postulated leakage rate, the control air pressure could drop below the critical value of 60 psig in a period less than 7 days.
However, since the evaluation was based on engineering judgement, the actual leakage rate and expected EDG run time without air makeup after start of the engine has not been quantified for the current system configuration. Testing is being conducted as part of a temporary modification to quantify the leakage rate. When this testing is completed, the safety significance of the identified condition will be evaluated and provided as a supplement to this LER.
Corrective Actions This condition was discovered with both units in cold shutdown. All four EDGs had previously been declared inoperable on January 11, 1999 due to HFA relay problems (see LER 315/99-001-00). No immediate corrective actions were necessary to maintain compliance with the Technical Specifications since the EDGs were already inoperable.
In order to support EDG operability in Modes 5 and 6, a method of supplying control air makeup for extended EDG operation, without reliance on the starting air compressors, will be established. This will be done via the temporary modification process, and any required operator actions will be controlled by an approved procedure. Prior to declaring any EDG operable, a test of the makeup air method will be performed to demonstrate the acceptability of operator actions and to verify performance of the makeup air source.
A permanent solution fpr the control air problem will be developed to restore conformance with the plant design basis and to support EDG operability in all Modes. Options for the permanent solution are currently under review and the method selected will be implemented via the design change process prior to restart of each unit.
Actions to prevent recurrence have been previously provided in AEP:NRC:1260GH, "Enforcement Actions 98-150, 98-151, 98-1 52 and 98-186, Reply to Notice of Violation Dated October 13, 1998", dated March 19, 1999.
Previous Similar Events 315/98-019-02                                                      315/88-014-00 315/98-031-01                                                      315/87-024-00 315/98-029-00                                                      315/87-020-00 315/98-046-00                                                      315/98-049-00 NRC FORM 366A. (6-1 998)}}

Latest revision as of 06:36, 29 October 2019

LER 99-011-00:on 990407,air Sys for EDG Will Not Support Long Operability.Caused by Original Design Error.Temporary Mod to Supply Makeup Air Capability in Modes 5 & 6 Was Prepared
ML17325B581
Person / Time
Site: Cook American Electric Power icon.png
Issue date: 05/04/1999
From: Depuydt M
INDIANA MICHIGAN POWER CO.
To:
Shared Package
ML17325B580 List:
References
LER-99-011, LER-99-11, NUDOCS 9905110294
Download: ML17325B581 (4)
v • d • e


Text

)IRC Form 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB NO. 31604104 EXPIRES 06r30/2001 (6-1998) ESTFIIATED BURDEN PER RESPONSE TO COMPLY WITH THIS MANDATORY INFORMATION COLLECTION REOVEST: 500 HRS. REPORTED LESSONS LEARNED ARE INCORPORATED INTO THE LICENQNG PROCESS AND FED BACK TO INDUSTRY.

LICENSEE EVENT REPORT (LER) FORWARD COATUENTS REGARDING BURDEN ESTIMATE TO THE INFORMATION AND RECORDS MANAGEMENT BRANCH Irar Fss). V.S. NUCLEAR REGVIATORY CoseaISSION. WASHINGTON. DC 20555OXI. AND TO THE PAPERWORK REDVCTION PR<MECT ISI500101L OFFICE OF MANAGEMENT AND BUDGET. WASIeNGTON. OC (See reverse for required number of 20505 digits/characters for each block)

FACILITYNAME (I ) II DOCKET NUMBER I2) PAGE IS)

Cook Nuclear Plant Unit 1 05000-315 1 of3 TITLE I4)

Air System for Emergency Diesel Generators (EDG) May Not Support Long Term Operability Due to Original Design Error EVENT DATE (6) LER NUMBER (6) REPORT DATE (7) OTHER FACILITIES INVOLVED (8)

FACILllYNAME DOCKEr NUMBER SEQUENTIAL REVISION Cook Unit 2 05000-316 MONTH DAY YEAR YEAR NUMBER NUMBER MONTH DAY YEAR FACIUTY NAM DOCKET NUMBER 04 07 1999 1999 011 00 05 04 1999 OPERATING THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR g: (Check one or mor e) (11)

MODE (9) 20.2201 (b) 20.2203(a)(2)(v) 50.73(a)(2)(i) 50.73(a)(2)(viii)

POWER 20.2203(a)(1) 20.2203(a)(3)(i) 50.73(a)(2)(ii) 50.73(a)(2)(x)

LEVEL (10) 00 73.71 20.2203(a)(2)(i) 20.2203(a)(3)(ii) 50.73(a)(2)(iii) 20.2203(a)(2)(ii) 20.2203(a)(4) 50.73(a)(2)(iv) OTHER 20.2203(a)(2)(iii) 50.36(c)(1) 50.73(a)(2)(v)

Specity in Abstract below 20.2203(a)(2)(iv) 50.36(c)(2) 50.73(a)(2)(vii) or n NRC Form 366A UCENSEE CONTACT FOR THIS LER (12)

NAME TELEPHONE NUMBER 01Ktvde Area Code)

Ms. M. B. Depuydt, Compliance Engineer 616/465-5901, x1 589 COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT (13)

REPORTABLE REPORTABLE TO CAUSE SYSTEM COMPONENT MANUFACTURER TO EPIX coM poNENT MANUFACTURER EPIX E

SUPPLEMENTAL REPORT EXPECTED 14 EXPECTED MONTH YEAR X YES SUBMISSION 07 01 1999 If Yes, corn lete EXPECTED SUBMISSION DATE DATE 15 Abstract (Umit to 1400 spaces, I.e., approximately 15 single-spaced typewritten lines) (16)

In February 1999, during the Expanded System Readiness Review of the Emergency Diesel Generator (EDG) system, the ability of the starting air/control air system to support long term operability of the EDGs was questioned due to the non-safety related design of the compressors. An operability determination was performed which concluded that the EDGs could not maintain long term operability without reliance on the non-safety related, non-seismic starting air compressors, and were therefore inoperable. On April 7, 1999 an ENS notification was made in accordance with 10CFR50.72(b)(2)(I),

for an unanalyzed condition with potential safety significance.

The apparent cause of the inadequacy of the EDG starting/control air system is original design error. The designers apparently failed to consider that the starting air system provides the control air to the EDG, and loss of air could result in shutdown of the engine. A temporary modification to supply makeup air capability in Modes 5 and 6 is being prepared.

Options for the permanent solutions are currently under review and the method selected will be implemented via a design change prior to restart of each unit.

The control air leakage rate and expected EDG run time without makeup air capability has not yet been quantified for the current system configuration. Testing is being conducted as part of the proposed temporary modification to quantify the expected leakage rate. Once the leakage rate is known, the results will be evaluated to determine the safety significance of the identified condition.

9'2)05ii0294 '2)'2)0504 PDR ADOCK 050003% 5 8 PDR

0 NRC FORM 366A U.S. NUCLEAR REGULATORY COMMISSION (6-1998)

LICENSEE EVENT REPORT (LER)

TEXT CONTINUATION FACILITYNAME (1) DOCKET NUMBER(2) LER NUMBER (6) PAGE (3)

YEAR SEQUENTIAL REVISION Cook Nuclear Plant Unit 1 05000-315 NUMBER NUMBER 2of3 1999 011 00 TEXT (ifmore space is required, use additional copies of NRC Form (366A) (11)

Conditions Prior to Event Unit 1 was in Mode 5, Cold Shutdown Unit 2 was in Mode 5, Cold Shutdown Descri tion of Event On February 18, 1999, during the Expanded System Readiness Review of the Emergency Diesel Generator (EDG) system, the ability of the starting air/control air system to support long term operability of the EDGs was questioned due to the non-safety related design of the compressors. I The compressois, compressor drive motors, the piping between each compressor and the respective discharge check valve are not safety related components. Although the EDG starting air compressors are supplied from a Class 1E power source and are anchored per Seismic Class 1 criteria, they are neither safety related, or seismically qualified.

When this question arose, Operations requested additional information from Engineering, which led to an operability determination being performed. The determination considered the design function of the EDGs, the starting air compressors and the control air function of the starting air system. Central to the determination is the design function of the control air for the EDG, which is discussed in detail in the Analysis section of the LER, and the "mission time" or how long the EDGs would need to run after an accident.

In the course of performing the operability determination, no finite statement could be found in the design or licensing basis documentation that defined the mission time of the EDGs. A decision was made to use a value of seven days, which is supported by the Technical Specification requirements for the amount of fuel oil that is required to be on hand to run the EDGs.

Using this information, the operability determination concluded that the EDGs could not maintain long term operability without reliance on the non-safety related, non-seismic starting air compressors and were therefore inoperable.

Cause of Event The cause of this event was a design deficiency in the EDG and its supporting systems that occurred during original plant design. The designers apparently failed to consider that the starting air system provides the control air to the EDG, and loss of control air could result in shutdown of the engine. Although the EDG starting air compressors are supplied from a Class 1E power source and are anchored per Seismic Class I criteria, they might not function in a seismic event because of their lack of qualification. The EDG air system was modiTied in 1994 and replacement compressors were installed, however, the replacement compressors were also classified non-safety.

Anal sis of Event On April 7, 1999, 'at 1501 hours0.0174 days <br />0.417 hours <br />0.00248 weeks <br />5.711305e-4 months <br /> EDT, an ENS notification was made in accordance with 10 CFR 50.72(b)(2)(i), any event found while the reactor is shut down, that, had it been found while the reactor was in operation, would have resulted in the.

nuclear power plant being in an unanalyzed condition that significantly compromises plant safety. This LER is therefore submitted in accordance with 10 CFR 50.73(a)(2)(ii)(A), for the same criteria.

The EDG system is a safety related system that provides reliable and readily available onsite AC power in the event of the loss of offsite power supply to the essential loads necessary to safely shutdown the reactor under any normal operating or accident conditions. The EDGs are designed to start automatically upon receipt of a safety injection signal and/or a loss of offsite power signal and be ready to accept loads within 10 seconds of receiving a start signal.

The starting air system supplies compressed air for starting the EDG. Each EDG has its own starting air system consisting of two redundant starting air compressors. Each compressor has one receiver of sufficient volume, 285 cubic feet, for at NRC FORM 366A (6-1998)

NRC FORM 366A U.S. NUCLEAR REGULATORY COMMISSION (6-1998)

LICENSEE EVENT REPORT (LER)

TEXT CONTINUATION FACILITYNAME (1) DOCKET NUMBER(2) LER NUMBER (6) PAGE (3)

YEAR SEQUENTIAL REVISION Cook Nuclear Plant Unit 1 05000-315 NUMBER NUMBER 3 of 3 1999 011 00 TEXT (Ifmore space Is required, use additional copies of NRC Form (366A) (17) least two EDG start attempts when pressurized to 220 psig. Each of the two starting air trains supplies starting air within the pressure range of 220 to 247.5 psig. Both starting air trains are independently actuated by the diesel engine control system upon receipt of an EDG start signal. If either compressor/receiver should fail the other is capable of starting the EDG. The system is designed to have the EDG at speed and ready to accept load within.10 seconds of start initiation.

The starting air system also provides compressed air for the starting air supply valve actuators, the diesel engine control system and the turbocharger aftercooler cooling water regulating valves.

The starting air system consists of two independent trains of one air compressor and one air receiver each. Each starting air receiver is replenished by its associated starting air compressor that cycles as necessary to maintain the receiver air pressure between 220 and 247.5 psig. The air receivers also supply the diesel engine pneumatic controlsystem with 100 psig air via pressure reducing valves. The 100 psig engine control air is required to maintain the throttle control cylinder's actuating rod retracted and thus maintain fuel flow to the engine. The minimum control air pressure required to maintain the throttle control cylinder's actuating rod fully retracted is 60 psig.

Ifthe starting air compressors are unavailable to replenish the air receivers following an EDG start, the volume of air remaining to supply the control air requirements is limited. Based on pre-operational test data, starting air receiver pressure could range from 188 to 132 psig following an emergency start. It was postulated that the leakage from the system would result in a loss of air receiver pressure of approximately 25 psi in a twelve hour period. At this postulated leakage rate, the control air pressure could drop below the critical value of 60 psig in a period less than 7 days.

However, since the evaluation was based on engineering judgement, the actual leakage rate and expected EDG run time without air makeup after start of the engine has not been quantified for the current system configuration. Testing is being conducted as part of a temporary modification to quantify the leakage rate. When this testing is completed, the safety significance of the identified condition will be evaluated and provided as a supplement to this LER.

Corrective Actions This condition was discovered with both units in cold shutdown. All four EDGs had previously been declared inoperable on January 11, 1999 due to HFA relay problems (see LER 315/99-001-00). No immediate corrective actions were necessary to maintain compliance with the Technical Specifications since the EDGs were already inoperable.

In order to support EDG operability in Modes 5 and 6, a method of supplying control air makeup for extended EDG operation, without reliance on the starting air compressors, will be established. This will be done via the temporary modification process, and any required operator actions will be controlled by an approved procedure. Prior to declaring any EDG operable, a test of the makeup air method will be performed to demonstrate the acceptability of operator actions and to verify performance of the makeup air source.

A permanent solution fpr the control air problem will be developed to restore conformance with the plant design basis and to support EDG operability in all Modes. Options for the permanent solution are currently under review and the method selected will be implemented via the design change process prior to restart of each unit.

Actions to prevent recurrence have been previously provided in AEP:NRC:1260GH, "Enforcement Actions98-150, 98-151, 98-1 52 and 98-186, Reply to Notice of Violation Dated October 13, 1998", dated March 19, 1999.

Previous Similar Events 315/98-019-02 315/88-014-00 315/98-031-01 315/87-024-00 315/98-029-00 315/87-020-00 315/98-046-00 315/98-049-00 NRC FORM 366A. (6-1 998)

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