|
|
| (2 intermediate revisions by the same user not shown) |
| Line 3: |
Line 3: |
| | issue date = 06/01/1999 | | | issue date = 06/01/1999 |
| | title = LER 99-013-00:on 990327,safety Injection & Centrifugal Charging Throttle Valve Cavitation During LOCA Could Have Led to ECCS Pump Failure.Caused by Inadequate Original Design Application of Si.Throttle Valves Will Be Developed | | | title = LER 99-013-00:on 990327,safety Injection & Centrifugal Charging Throttle Valve Cavitation During LOCA Could Have Led to ECCS Pump Failure.Caused by Inadequate Original Design Application of Si.Throttle Valves Will Be Developed |
| | author name = OROURKE B W | | | author name = Orourke B |
| | author affiliation = INDIANA MICHIGAN POWER CO. | | | author affiliation = INDIANA MICHIGAN POWER CO. |
| | addressee name = | | | addressee name = |
| Line 17: |
Line 17: |
|
| |
|
| =Text= | | =Text= |
| {{#Wiki_filter:E NRC Form 366 U.S.NUCLEAR REGULATORY COMMISSION (6-1998)L(CENSEE EVENT REPORT (LER)(See reverse for required number of digits/characters for each block)APPROVEOSYOMB)IO.31~104 EXP)REB 06r30)2001 ESTSJATED SVRDEN PER RESPONSE TO COMPLY WITH TIES MANDATORY INFORMATION COLLECDON RECVESP.50JJ HRS.REPORTED lESSONS lEARHED ARE INCORPORATED VITO THE UCENSINO PROCESS AND FED SACK'TO INDVSTRY.FORWARD COMNBPS REOARDVIO SVRDEN ESTSIATE TO THE INFORMATION AND RECORDS MANAOEMENT SRANCH IT%FSSL V.S.NVCL EAR REOVIATORY COLSSSSON, WASHSIOTON, DC 2N554NI.AND TO THE P~REDVCTION PRO/ECt O1100100, OFACE OF MANAOEMENT AJID SVOOET, WASISNOTON, DC 20MS FACIUTY NAME (I)Cook Nuclear Plant Unit 1 DOCKET NUMBER t2)05000-315 PAOE IS)1 of3 TITLE (4)Safety Injection and CentNugat Charging Throttle Valve Cavitation During LOCA Could Lead to ECCS Pump Failure EVENT DATE{6)LER NUMBER{6)REPORT DATE (7)OTHER FACILITIES INVOLVED (6)MONTH DAY YEAR YEAR SEQUENTIAL NUMBER REVISION NUMBER MONTH'DAY YEAR ACIUTY NAME D.C.Cook, Unit 2 FACIUTY NAM 05000-316 NUM R 03 27 1999 1999 013 00 06 01 1999 OPERATING MODE (9)POVlER LEVEL (10)0 20.2201 (b)20.2203(a)(t) 20.2203(a)(2N) 20.2203{a) | | {{#Wiki_filter:E NRC Form 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVEOSYOMB)IO.31~104 EXP)REB 06r30)2001 (6-1998) ESTSJATED SVRDEN PER RESPONSE TO COMPLY WITH TIES MANDATORY INFORMATIONCOLLECDON RECVESP. 50JJ HRS. REPORTED lESSONS lEARHED ARE INCORPORATED VITO THE UCENSINO PROCESS AND FED SACK 'TO INDVSTRY. |
| {2)(ii)20.2203(a)(2)(ui) 20.2203(a)(2)(iv) 20.2203(a)(2)(v) 20.2203(a)(3)(I) 20.2203(a)(3)(9) 20.2203(a)(4) 50.36(c)(1) 50.36(c)(2)
| | L(CENSEE EVENT REPORT (LER) |
| UCENSEE CONTACT FOR THIS LER (12)50.73(a)(2)(l) 50.73(a)(2)(6) 50.73{a)(2)(iii) 50.73(a)(2)(lv) 50.73(a)(2)(v) 50.73(a)(2)(vti) 50.73(a)(2)(viii) 73.71 50.73(a)(2)(x)
| | (See reverse for required number of 20MS P~ |
| OTHER SPPCEF in AIJSVect IJeNAN 01 n NRC Form MEA TELEPHONE NUMBER 0IcIvde Area Code)THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR li: (Check one or more)(11)Ms.Brenda W.O'ourke, Compliance Engineer (616)465-5901 x2604 COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT{13)COMPONENT MANUFACTURER REPORTABLE TO EPIX COMPONENT MANUFACTURER REPORTABLE TO EPIX SUPPLEMENTAL REPORT EXPECTED 14 X YES If Yes, corn lete EXPECTED SUBMISSION DATE NO EXPECTED SUBMISSION DATE 15 12 YEAR 01 1999 Abstract{Umit to 1400 spaces, I.e., approximately 15 single-spaced typewritten lines)(16)On March 27, 1999, during development of an Emergency Core Cooling System (ECCS)thermal hydraulic flow analysis model, Engineering concluded that preliminary hydraulic flow analysis results indicated that the Unit 1 Safety Injection (Sl)and Centrifugat Charging (CC)throttle valves could potentially experience cavitation during a LOCA.Specifically, during a LOCA, large differential pressures created across the Sl and CC throttle valves would result in cavitation and possible mechanical erosion of the valves and downstream piping.During post-LOCA conditions, throttle valve erosion could lead to a pump runout condition and subsequent failure of the ECCS pumps.Radiography performed to determine valve position showed the valves to be less open than predicted by the hydraulic analysis.This condition could result in LOCA generated debris becoming lodged in the throttle valve, resulting in reduced flow to the reactor core.Similar conditions exist for the Unit 2 Sl and CC throttle valves.During continuing evaluation, plant personnel concluded that the conditions were reportable on May 4, 1999, and a 4-hour notification was made to the NRC in accordance with 10CFR50.72, for a condition that resutted in the plant being in an unanalyzed condition, and for any event or condition that alone could have prevented the fulfillment of the Sl or CC system safety function needed to mitigate the consequences of an accident.The preliminary cause is inadequate original design application of the Sl and CC throttle valves.Because five of the six Unit 1 throttle valves were found to be less than 44 percent open, these vatves could be assumed to be partially or fully plugged with debris although the amount of plugging would depend on the nature and geometry of the debris.However, partial or full plugging could render the systems not capable of performing their intended safety function during the recirculation phase of a LOCA event.As part of the evaluation, a permanent solution for the cavitation-induced erosion and potential debris plugging will be devetoped to restore conformance with the plant design basis and to support ECCS operability.
| | FORWARD COMNBPS REOARDVIO SVRDEN ESTSIATE TO THE INFORMATION AND RECORDS MANAOEMENT SRANCH IT% FSSL V.S. NVCLEAR REOVIATORY COLSSSSON, WASHSIOTON, DC 2N554NI. AND TO THE REDVCTION PRO/ECt O1100100, OFACE OF MANAOEMENT AJID SVOOET, WASISNOTON, DC digits/characters for each block) |
| Possible modifications are currently under review and the method selected will be implemented prior to restart of each unit.A supplement to this LER will be provided upon completion of the condition evaluation. | | FACIUTY NAME (I ) DOCKET NUMBER t2) PAOE IS) |
| 9906080i48 | | Cook Nuclear Plant Unit 1 05000-315 1 of3 TITLE (4) |
| 'T)9060i PDR ADQCK 050003i5 8 PDR NRC FORM 366A U.S.NUCLEAR REGULATORY COMMISSION (6-1998)LICENSEE EVENT REPORT (LER)~TEXT CONTINUATION FACILITY NAME (1)Cook Nuclear Plant Unit 1 DOCKETNUMBER(2) 05000-315 YEAR 1999 LER NUMBER (6)SEQUENTIAL NUMBER 013 REVISION NUMBER 00 PAGE (3)2 of 3 TEXT (If more space is required, use additional copies of NRC Form (366A)(17)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 March 27, 1999, during development of an Emergency Core Cooling System (ECCS)thermal hydraulic flow analysis model, Engineering concluded that preliminary hydraulic flow analysis results indicated that the Unit 1 Safety Injection (Sl)[BQ]and Centrifugal Charging (CC)[SJJ throttle valves[FCVJ could potentially experience cavitation during a LOCA.Specifically, during a LOCA, large differential pressures created across the Sl and CC throttle valves would result in cavitation and possible mechanical erosion of the valves and downstream piping.Throttle valve erosion during post-LOCA conditions could cause the valves to allow excess flow through the Sl and CC pumps, which could lead to a pump runout condition and subsequent failure of the ECCS pumps.The preliminary flow analysis also predicted that the Sl and CC throttle valves would be less open than previously determined during evaluation of an industry event in 1995.In addition, actual valve stem measurements concluded that the Sl and CC throttle valves were less open than predicted by the preliminary flow analysis.As a result, radiography was performed on April 8, 1999, for two Sl throttle valves to better assess their position.Radiography results also concluded that the throttle valves were more closed than'predicted by the hydraulic analysis, and also showed indications of possible valve erosion.With the throttle valves found less open, debris generated in containment during a LOCA could potentially become lodged in the throttle valves, resulting in reduced flow to the reactor core.Similar conditions exist for the Unit 2 Sl and CC throttle valves.During continuing evaluation of the identified conditions, on May 4, 1999, plant personnel concluded that these conditions were reportable to the NRC.Cause of Event The preliminary cause is inadequate original design application of the Sl and CC throttle valves.At the time of original plant design, this throttle valve design was commonly used throughout the industry for the same throttling application. | | Safety Injection and CentNugat Charging Throttle Valve Cavitation During LOCA Could Lead to ECCS Pump Failure EVENT DATE {6) LER NUMBER {6) REPORT DATE (7) OTHER FACILITIES INVOLVED(6) |
| However, it was not recognized that these valves are susceptible to mechanical cavitation damage as a result of high differential pressures across the valve.Opportunities to identify this potential condition were missed during previous evaluations of industry events regarding the potential for post-LOCA ECCS pump runout damage due to throttle valve degradation. | | ACIUTY NAME SEQUENTIAL REVISION D.C. Cook, Unit 2 05000-316 MONTH DAY YEAR YEAR NUMBER NUMBER MONTH 'DAY YEAR FACIUTY NAM NUM R 03 27 1999 1999 013 00 06 01 1999 OPERATING THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR li: (Check one or more) (11) |
| Anal sis of Event In accordance with the requirements of 10CFR50.72(b)(2)(i) and 10CFR50.72(b)(2)(iii)(D), a 4-hour notification was made to the NRC for a condition that resulted in the plant being in an unanalyzed condition, and for any event or condition that alone could have prevented the fulfillment of the Sl or CC system safety function needed to mitigate the consequences of an accident.As such, this LER is being submitted in accordance with the requirements of 10CFR50.73. | | MODE (9) 20.2201 (b) 20.2203(a)(2)(v) 50.73(a)(2)(l) 50.73(a)(2)(viii) |
| UFSAR Section 6.2 states that the primary function of the ECCS is to provide cooling water to the reactor core in the event of a LOCA.The ECCS system consists of six ECCS pumps: two Centrifugal Charging pumps, two Residual Heat Removal (RHR)pumps, and two Safety Injections pumps.The subject throttle valves are installed on each of the four CC pump lines to the reactor coolant loops and on the discharge side of each Sl pump.NRC FORM 366A (6-1998) | | POVlER 20.2203(a)(t) 20.2203(a)(3)(I) 50.73(a)(2)(6) 50.73(a)(2)(x) |
| NRC FORM 366A U.S.NUCLEAR REGULATORY COMMISSION (6-1998)LICENSEE EVENT REPORT (LER)~TEKF CONTINUATION FACIUTY NAME (1)Cook Nuclear Plant Unit 1 DOCKETNUMBER(2) 05000-315 YEAR 1999 LER NUMBER (6)SEQUENTIAL NUMBER 013 REVISION NUMBER 00 PAGE (3)3of3 TEXT (If more space ls required, use additional copies of NRC Form (366A)(17)The operation of the ECCS following a LOCA consists of two distinct phases: 1)the injection phase during which reactivity is controlled, initial cooling of the core is accomplished, and coolant lost from the primary system is replenished, and 2)the recirculation phase, in which long term core cooling is provided during the accident recovery period.Long term core cooling is provided, in part, by the Sl and CC systems that deliver coolant water from the containment recirculation sump back to the reactor coolant system.Following a LOCA event, any debris that was generated in containment will be filtered through a 0.25-inch square mesh screen[BP](SCN]prior to entering the containment sump to prevent foreign material from entering the ECCS system.V The preliminary results of the ECCS hydraulic flow analysis were used to calculate the potential cavitation damage to the Sl and CC throttle valves under various ECCS system operating configurations. | | LEVEL (10) 0 73.71 20.2203(a)(2N) 20.2203(a)(3)(9) 50.73{a)(2)(iii) 20.2203{a) {2)(ii) 20.2203(a)(4) 50.73(a)(2)(lv) OTHER 20.2203(a)(2)(ui) 50.36(c)(1) 50.73(a)(2)(v) |
| The most limiting operating configuration assumes the throttle valves to be wide open to simulate the maximum erosion condition. | | SPPCEF in AIJSVect IJeNAN 20.2203(a)(2)(iv) 50.36(c)(2) 50.73(a)(2)(vti) 01 n NRC Form MEA UCENSEE CONTACT FOR THIS LER (12) |
| The flow analysis concluded that with the throttle valves wide open, cavitation would likely occur and the Sl pumps would be in a runout condition, while both CC pumps would remain available. | | TELEPHONE NUMBER 0IcIvde Area Code) |
| For the case where only one CC pump is running, analysis results conclude that the single CC pump would go to the runout condition, in addition to both Sl pumps.For this configuration, calculations indicate that the Sl valves would be in a choked flow condition, which could cause cavitation-induced erosion of the valves and/or downstream piping.In addition, the CC throttle valves were calculated to be in the incipient damage range, which is the level at which cavitation is considered sufficient to result in erosion damage.Westinghouse letter NSAL-96-001,"Erosion of Globe Valves in ECCS Throttling Applications," indicates that even with throttle valve erosion, the CC and Sl pumps should remain operable long enough to allow the operators to use the RHR pumps for long term cooling.However, no formal analysis has been performed to validate the impact this condition has on long term ECCS post-LOCA operation. | | Ms. Brenda W. O'ourke, Compliance Engineer (616) 465-5901 x2604 COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT {13) |
| Information received from the valve manufacturer requires the throttle valves to be approximately 44 percent open to ensure debris would not become lodged in the valve.Because five of the six Unit 1 throttle valves were found to be less than 44 percent open, these valves could be assumed to be partially or fully plugged with debris although the amount of plugging would depend on the nature and geometry of the debris.However, partial or full plugging of the Sl and CC throttle valves could render the systems not capable of performing their intended safety function during the recirculation phase of a LOCA.Corrective Actions A permanent solution for the cavitation-induced erosion and potential debris plugging of the throttle valves will be developed to restore conformance with the plant design basis and to support ECCS system operability. | | REPORTABLE REPORTABLE TO COMPONENT MANUFACTURER TO EPIX COMPONENT MANUFACTURER EPIX SUPPLEMENTAL REPORT EXPECTED 14 EXPECTED YEAR X YES SUBMISSION 12 01 1999 IfYes, corn lete EXPECTED SUBMISSION DATE NO DATE 15 Abstract {Umitto 1400 spaces, I.e., approximately 15 single-spaced typewritten lines) (16) |
| Possible modifications are currently under review and the method selected will be implemented prior to,restart of each unit.As part of the Restart effort, an improved operating experience program is being developed. | | On March 27, 1999, during development of an Emergency Core Cooling System (ECCS) thermal hydraulic flow analysis model, Engineering concluded that preliminary hydraulic flow analysis results indicated that the Unit 1 Safety Injection (Sl) and Centrifugat Charging (CC) throttle valves could potentially experience cavitation during a LOCA. Specifically, during a LOCA, large differential pressures created across the Sl and CC throttle valves would result in cavitation and possible mechanical erosion of the valves and downstream piping. During post-LOCA conditions, throttle valve erosion could lead to a pump runout condition and subsequent failure of the ECCS pumps. Radiography performed to determine valve position showed the valves to be less open than predicted by the hydraulic analysis. This condition could result in LOCA generated debris becoming lodged in the throttle valve, resulting in reduced flow to the reactor core. Similar conditions exist for the Unit 2 Sl and CC throttle valves. During continuing evaluation, plant personnel concluded that the conditions were reportable on May 4, 1999, and a 4-hour notification was made to the NRC in accordance with 10CFR50.72, for a condition that resutted in the plant being in an unanalyzed condition, and for any event or condition that alone could have prevented the fulfillment of the Sl or CC system safety function needed to mitigate the consequences of an accident. |
| In addition, the Expanded System Readiness Review project teams are evaluating operating experience information to assess whether applicable industry issues have been adequately addressed for applicability to D.C.Cook.The adequacy of the systems to perform their safety and accident mitigation functions is being reviewed during the discovery process at D.C.Cook under a number of system assessments and programmatic assessments to support the Restart Plan.These include the Expanded System Readiness Review (ESRR)and the Licensing Basis Review.Identified deficiencies are being addressed under the Corrective Action Program.The evaluation for this condition has not been completed. | | The preliminary cause is inadequate original design application of the Sl and CC throttle valves. Because five of the six Unit 1 throttle valves were found to be less than 44 percent open, these vatves could be assumed to be partially or fully plugged with debris although the amount of plugging would depend on the nature and geometry of the debris. However, partial or full plugging could render the systems not capable of performing their intended safety function during the recirculation phase of a LOCA event. As part of the evaluation, a permanent solution for the cavitation-induced erosion and potential debris plugging will be devetoped to restore conformance with the plant design basis and to support ECCS operability. Possible modifications are currently under review and the method selected will be implemented prior to restart of each unit. A supplement to this LER will be provided upon completion of the condition evaluation. |
| Based on the results of the completed evaluation, information regarding the safety significance, and corrective and preventive actions will be provided in an update to this LER.Previous Similar Events None~NRC FORM 366A (6-1998)}} | | 9906080i48 'T)9060i PDR ADQCK 050003i5 8 PDR |
| | |
| | NRC FORM 366A U.S. NUCLEAR REGULATORY COMMISSION (6-1998) |
| | LICENSEE EVENT REPORT (LER) |
| | ~ TEXT CONTINUATION FACILITYNAME (1) DOCKETNUMBER(2) LER NUMBER (6) PAGE (3) |
| | YEAR SEQUENTIAL REVISION Cook Nuclear Plant Unit 1 05000-315 NUMBER NUMBER 2 of 3 1999 013 00 TEXT (Ifmore space is required, use additional copies of NRC Form (366A) (17) |
| | 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 March 27, 1999, during development of an Emergency Core Cooling System (ECCS) thermal hydraulic flow analysis model, Engineering concluded that preliminary hydraulic flow analysis results indicated that the Unit 1 Safety Injection (Sl)[BQ] and Centrifugal Charging (CC)[SJJ throttle valves [FCVJ could potentially experience cavitation during a LOCA. |
| | Specifically, during a LOCA, large differential pressures created across the Sl and CC throttle valves would result in cavitation and possible mechanical erosion of the valves and downstream piping. Throttle valve erosion during post-LOCA conditions could cause the valves to allow excess flow through the Sl and CC pumps, which could lead to a pump runout condition and subsequent failure of the ECCS pumps. |
| | The preliminary flow analysis also predicted that the Sl and CC throttle valves would be less open than previously determined during evaluation of an industry event in 1995. In addition, actual valve stem measurements concluded that the Sl and CC throttle valves were less open than predicted by the preliminary flow analysis. As a result, radiography was performed on April 8, 1999, for two Sl throttle valves to better assess their position. Radiography results also concluded that the throttle valves were more closed than'predicted by the hydraulic analysis, and also showed indications of possible valve erosion. With the throttle valves found less open, debris generated in containment during a LOCA could potentially become lodged in the throttle valves, resulting in reduced flow to the reactor core. Similar conditions exist for the Unit 2 Sl and CC throttle valves. During continuing evaluation of the identified conditions, on May 4, 1999, plant personnel concluded that these conditions were reportable to the NRC. |
| | Cause of Event The preliminary cause is inadequate original design application of the Sl and CC throttle valves. At the time of original plant design, this throttle valve design was commonly used throughout the industry for the same throttling application. |
| | However, it was not recognized that these valves are susceptible to mechanical cavitation damage as a result of high differential pressures across the valve. |
| | Opportunities to identify this potential condition were missed during previous evaluations of industry events regarding the potential for post-LOCA ECCS pump runout damage due to throttle valve degradation. |
| | Anal sis of Event In accordance with the requirements of 10CFR50.72(b)(2)(i) and 10CFR50.72(b)(2)(iii)(D), a 4-hour notification was made to the NRC for a condition that resulted in the plant being in an unanalyzed condition, and for any event or condition that alone could have prevented the fulfillment of the Sl or CC system safety function needed to mitigate the consequences of an accident. As such, this LER is being submitted in accordance with the requirements of 10CFR50.73. |
| | UFSAR Section 6.2 states that the primary function of the ECCS is to provide cooling water to the reactor core in the event of a LOCA. The ECCS system consists of six ECCS pumps: two Centrifugal Charging pumps, two Residual Heat Removal (RHR) pumps, and two Safety Injections pumps. The subject throttle valves are installed on each of the four CC pump lines to the reactor coolant loops and on the discharge side of each Sl pump. |
| | NRC FORM 366A (6-1998) |
| | |
| | NRC FORM 366A U.S. NUCLEAR REGULATORY COMMISSION (6-1998) |
| | LICENSEE EVENT REPORT (LER) |
| | ~ TEKF CONTINUATION DOCKETNUMBER(2) LER NUMBER (6) PAGE (3) |
| | FACIUTYNAME (1) |
| | YEAR SEQUENTIAL REVISION Cook Nuclear Plant Unit 1 05000-315 NUMBER NUMBER 3of3 1999 013 00 TEXT (Ifmore space ls required, use additional copies ofNRC Form (366A) (17) |
| | The operation of the ECCS following a LOCA consists of two distinct phases: 1) the injection phase during which reactivity is controlled, initial cooling of the core is accomplished, and coolant lost from the primary system is replenished, and 2) the recirculation phase, in which long term core cooling is provided during the accident recovery period. Long term core cooling is provided, in part, by the Sl and CC systems that deliver coolant water from the containment recirculation sump back to the reactor coolant system. Following a LOCA event, any debris that was generated in containment will be filtered through a 0.25-inch square mesh screen [BP](SCN] prior to entering the containment sump to prevent foreign material from entering the ECCS system. |
| | V The preliminary results of the ECCS hydraulic flow analysis were used to calculate the potential cavitation damage to the Sl and CC throttle valves under various ECCS system operating configurations. The most limiting operating configuration assumes the throttle valves to be wide open to simulate the maximum erosion condition. The flow analysis concluded that with the throttle valves wide open, cavitation would likely occur and the Sl pumps would be in a runout condition, while both CC pumps would remain available. For the case where only one CC pump is running, analysis results conclude that the single CC pump would go to the runout condition, in addition to both Sl pumps. For this configuration, calculations indicate that the Sl valves would be in a choked flow condition, which could cause cavitation-induced erosion of the valves and/or downstream piping. In addition, the CC throttle valves were calculated to be in the incipient damage range, which is the level at which cavitation is considered sufficient to result in erosion damage. Westinghouse letter NSAL-96-001, "Erosion of Globe Valves in ECCS Throttling Applications," indicates that even with throttle valve erosion, the CC and Sl pumps should remain operable long enough to allow the operators to use the RHR pumps for long term cooling. However, no formal analysis has been performed to validate the impact this condition has on long term ECCS post-LOCA operation. |
| | Information received from the valve manufacturer requires the throttle valves to be approximately 44 percent open to ensure debris would not become lodged in the valve. Because five of the six Unit 1 throttle valves were found to be less than 44 percent open, these valves could be assumed to be partially or fully plugged with debris although the amount of plugging would depend on the nature and geometry of the debris. However, partial or full plugging of the Sl and CC throttle valves could render the systems not capable of performing their intended safety function during the recirculation phase of a LOCA. |
| | Corrective Actions A permanent solution for the cavitation-induced erosion and potential debris plugging of the throttle valves will be developed to restore conformance with the plant design basis and to support ECCS system operability. Possible modifications are currently under review and the method selected will be implemented prior to,restart of each unit. |
| | As part of the Restart effort, an improved operating experience program is being developed. In addition, the Expanded System Readiness Review project teams are evaluating operating experience information to assess whether applicable industry issues have been adequately addressed for applicability to D.C. Cook. |
| | The adequacy of the systems to perform their safety and accident mitigation functions is being reviewed during the discovery process at D.C. Cook under a number of system assessments and programmatic assessments to support the Restart Plan. These include the Expanded System Readiness Review (ESRR) and the Licensing Basis Review. Identified deficiencies are being addressed under the Corrective Action Program. |
| | The evaluation for this condition has not been completed. Based on the results of the completed evaluation, information regarding the safety significance, and corrective and preventive actions will be provided in an update to this LER. |
| | Previous Similar Events None |
| | ~ NRC FORM 366A (6-1998)}} |
LER 99-013-00:on 990327,safety Injection & Centrifugal Charging Throttle Valve Cavitation During LOCA Could Have Led to ECCS Pump Failure.Caused by Inadequate Original Design Application of Si.Throttle Valves Will Be Developed| ML17325B642 |
| Person / Time |
|---|
| Site: |
Cook  |
|---|
| Issue date: |
06/01/1999 |
|---|
| From: |
Orourke B
INDIANA MICHIGAN POWER CO. |
|---|
| To: |
|
|---|
| Shared Package |
|---|
| ML17325B641 |
List: |
|---|
| References |
|---|
| LER-99-013, LER-99-13, NUDOCS 9906080148 |
| Download: ML17325B642 (3) |
|
Similar Documents at Cook |
|---|
Category:LICENSEE EVENT REPORT (SEE ALSO AO
MONTHYEARML17335A5641999-10-18018 October 1999
LER 99-024-00:on 990708,literal TS Requirements Were Not Met by Accumlator Valve Surveillance.Caused by Misjudgement Made in Conversion from Initial DC Cook TS to W Std Ts.Submitted License Amend Request.With 991018 Ltr
ML17335A5531999-10-0707 October 1999
LER 99-023-00:on 990907,inadequate TS Surveillance Testing of ESW Pump ESF Response Time Noted.Caused by Inadequate Understanding of Plant Design Basis.Surveillance Tests Will Be Revised & Implemented
ML17326A1291999-09-17017 September 1999
LER 99-022-00:on 990609,electrical Bus Degraded Voltage Setpoints Too Low for Safety Related Loads,Was Discovered. Caused by Lack of Understanding of Design of Plant.No Immediate Corrective Actions Necessary
ML17326A1121999-08-27027 August 1999
LER 99-021-00:on 990728,determined That GL 96-01 Test Requirements Were Not Met in Surveillance Tests.Caused by Failure to Understand Full Extent of GL Requirements. Surveillance Procedures Will Be Revised or Developed
ML17326A1011999-08-26026 August 1999
LER 99-020-00:on 990727,EDGs Were Declared Inoperable.Caused by Inadequate Protection of Air Intake,Exhaust & Room Ventilation Structures from Tornado Missile Hazards. Implemented Compensatory Measures in Form of ACs
ML17326A0911999-08-16016 August 1999
LER 99-019-00:on 990716,noted Victoreen Containment Hrrms Not Environmentally Qualified to Withstand post-LOCA Conditions.Caused by Inadequate Design Control.Reviewing Options to Support Hrrms Operability in Modes 1-4
ML17326A0771999-08-0404 August 1999
LER 98-029-01:on 980422,noted That Fuel Handling Area Ventilation Sys Was Inoperable.Caused by Original Design Deficiency.Radiological Analysis for Spent Fuel Handling Accidents in Auxiliary Bldg Will Be Redone by 990830
ML17326A0741999-07-29029 July 1999
LER 99-018-00:on 990629,determined That Valve Yokes May Yield Under Combined Stress of Seismic Event & Static,Valve Closed,Stem Thrust.Caused by Inadequate Design of Associated Movs.Operability Determinations Were Performed for Valves
ML17326A0661999-07-26026 July 1999
LER 99-017-00:on 990625,noted That Improperly Installed Fuel Oil Return Relief Valve Rendered EDG Inoperable.Caused by Personnel Error.Fuel Oil Return Valve Was Replaced with Valve in Correct Orientation.With 990722 Ltr
ML17326A0651999-07-22022 July 1999
LER 98-014-03:on 980310,noted That Response to high-high Containment Pressure Procedure Was Not Consistent with Analysis of Record.Caused by Inadequate Interface with W. FRZ-1 Will Be Revised to Be Consistent with New Analysis
ML17326A0491999-07-13013 July 1999
LER 99-016-00:on 990615,TS Requirements for Source Range Neutron Flux Monitors Not Met.Caused by Failure to Understand Design Basis of Plant.Procedures Revised.With 990713 Ltr
ML17326A0331999-07-0101 July 1999
LER 99-004-01:on 971030,failure to Perform TS Surveillance Analyses of Reactor Coolant Chemistry with Fuel Removed Was Noted.Caused by Ineffective Mgt of Tss.Chemistry Personnel Have Been Instructed on Requirement to Follow TS as Written
ML17326A0151999-06-18018 June 1999
LER 99-014-00:on 990521,determined That Boron Injection Tank Manway Bolts Were Not Included in ISI Program,Creating Missed Exam for Previous ISI Interval.Caused by Programmatic Weakness.Isi Program & Associated ISI Database Modified
ML17325B6311999-06-0101 June 1999
LER 99-S03-00:on 990430,vital Area Barrier Degradation Was Noted.Caused by Inadequate Insp & Maint of Vital Area Barrier.Repairs & Mods Were Made to Barriers to Eliminate Degraded & Nonconforming Conditions
ML17325B6421999-06-0101 June 1999
LER 99-013-00:on 990327,safety Injection & Centrifugal Charging Throttle Valve Cavitation During LOCA Could Have Led to ECCS Pump Failure.Caused by Inadequate Original Design Application of Si.Throttle Valves Will Be Developed
ML17325B6351999-05-28028 May 1999
LER 99-S02-00:on 990428,vulnerability in Safeguard Sys That Could Allow Unauthorized Access to Protected Area Was Noted. Caused by Inadequate Original Plant Design.Mods Were Made to Wall Opening to Eliminate Nonconforming Conditions
ML17265A8231999-05-24024 May 1999
LER 98-037-01:on 990422,determined That Ice Condenser Bypass Leakage Exceeds Design Basis Limit.Caused by Pressure Seal Required by Revised W Design Not Incorporated Into Aep Design.Numerous Matl Condition Walkdowns & Assessments Made
ML17325B6001999-05-20020 May 1999
LER 99-012-00:on 990420,concluded That Auxiliary Bldg ESF Ventilation Sys Not Capable of Maintaining ESF Room Temps post-accident.Caused by Inadequate Control of Sys Design Inputs.Comprehensive Action Plan Being Developed
ML17325B5861999-05-10010 May 1999
LER 99-002-00:on 990415,discovered That TS 4.0.5 Requirements Were Not Met Due to Improperly Performed Test. Caused by Incorrect Interpretation of ASME Code.App J Testing Will Be Completed & Procedures Will Be Revised
ML17325B5811999-05-0404 May 1999
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
ML17325B5771999-05-0303 May 1999
LER 99-010-00:on 990401,RCS Leak Detection Sys Sensitivity Not in Accordance with Design Requirements Occurred.Caused by Inadequate Original Design of Containment Sump Level. Evaluation Will Be Performed to Clearly Define Design
ML17325B5581999-04-16016 April 1999
LER 99-006-00:on 990115,personnel Identified Discrepancy Between TS 3.9.7 Impact Energy Limit & Procedure 12 Ohp 4030.STP.046.Caused by Lack of Design Basis Control.Placed Procedure 12 Ohp 4030.STP.046 on Administrative Hold
ML17325B5471999-04-12012 April 1999
LER 99-009-00:on 990304,as-found RHR Safety Relief Valve Lift Setpoint Greater than TS Limit Occurred.Cause Investigation for Condition Has Not Been Completed.Update to LER Will Be Submitted,Upon Completion of Investigation
ML17325B5321999-04-0707 April 1999
LER 99-S01-00:on 990308,discovered That Lock for Vital Gate Leading to Plant 4KV Switchgear Area Was Nonconforming & Vulnerable to Unauthorized Access.Caused by Inadequate Gate Design & Inadequate Procedures.Mods Are Being Made to Gate
ML17325B5161999-04-0101 April 1999
LER 99-007-00:on 981020,calculations Showed That Divider Barrier Between Upper & Lower Containment Vols Were Overstressed.Engineers Are Currently Working on Analyses of Loads & Stress on Enclosures
ML17325B5221999-03-29029 March 1999
LER 99-001-00:on 960610,degraded Component Cooling Water Flow to Containment Main Steam Line Penetrations,Identified on 990226.Caused by Inadequate Understanding of Design Basis.Additional Investigations Ongoing
ML17325B4801999-03-18018 March 1999
LER 99-004-00:on 971030,failure to Perform TS Surveillance Analyses of Rc Chemistry with Fuel Removed Was Noted.Cause of Event Is Under Investigation.Corrected Written Job Order Activities Used to Control SD Chemistry Sampling
ML17325B4741999-03-18018 March 1999
LER 99-005-00:on 940512,determined That Rt Breaker Manual Actuations During Rod Drop Testing Were Not Previously Reported.Caused by Lack of Training.Addl Corrective Actions,Including Preventative Actions May Be Developed
ML17325B4571999-02-24024 February 1999
LER 99-003-00:on 990107,CR Pressurization Sys Surveillance Test Did Not Test Sys in Normal Operating Condition.Caused by Failure to Recognize Door 12DR-AUX415 as Part of CR Pressure Boundary.Performed Walkdown of Other Doors
ML17335A5171999-02-11011 February 1999
LER 99-002-00:on 990112,determined That RCS Pressurizer PORVs Had Not Been Tested,Per Ts.Caused by Inadequate Scheduling Controls Allowing Personnel Error.Surveillance Procedure Was Completed & Updated LER Will Be Submitted
ML17335A5141999-02-10010 February 1999
LER 99-001-00:on 990106,noted That GE Hfa Relays Installed in EDGs May Not Meet Seismic Qualification.Caused by Operating Experience Info Incorrectly Dispositioned in 1985. Updated LER Will Be Submitted by 990405
ML17335A5011999-02-0101 February 1999
LER 98-060-00:on 981231,identified That Rt Sys Response Time Testing Did Not Comply with TS Definition.Caused by Inadequate Procedures.Corrective Actions Will Be Developed & Update to LER Will Be Submitted by 990415.With 990201 Ltr
ML17335A4951999-01-29029 January 1999
LER 98-059-00:on 981230,interim LER -single Failure in Containment Spray Sys Could Result in Containment Spray Ph Outside Design Occurred.Investigation Into Condition Continuing.Update Will Be Submitted by 990514 Ltr
ML17335A4961999-01-27027 January 1999
LER 98-057-00:on 981228,discovered That AFW Valves Were Not Tested IAW Inservice Testing Program.Caused by Failure to Recognize Design Bases Features Re Afws by Personnel. Updated LER Will Be Submittted by 990415.With 990127 Ltr
ML17335A4921999-01-19019 January 1999
LER 98-052-01:on 981128,no Analysis for NSR Sc Manual Loader for Tdafwp Could Be Found in Original Design.Cause Due to All Failure Modes Not Considered When Compressed Air Sys Originally Designed.Performed Review of Components
ML17335A4721999-01-0606 January 1999
LER 98-055-00:on 981207,potential for Condition Outside of Design Bases for Rod Control Sys Was Noted.Caused by Calibration Error Coupled with Single Rod Failure.Condition Rept Investigation Is Ongoing
ML17335A4691999-01-0606 January 1999
LER 98-056-00:on 981211,hot Leg Nozzle Gaps Resulted in Plant Being in Unanalyzed Condition.Analyses Are Being Performed by W to Resolve Problem.Updated LER Will Be Submitted by 990211.With 990106 Ltr
ML17335A4661999-01-0505 January 1999
LER 98-049-00:on 981020,emergency Boron Injection Flow Path Was Inoperable.Caused by Original Design Deficiency. Engineering Evaluation of Event Is Continuing
ML17335A4631999-01-0404 January 1999
LER 98-054-00:on 981202,discovered That at Least One MSSV Had Not Been Reset as Required by Ts.Engineering Is Continuing Review of Extent of Condition for Event.Updated LER Will Be Submitted by 990129.With 990104 Ltr
ML17335A4481998-12-30030 December 1998
LER 98-053-00:on 981130,discovered Use of Inoperable Substitute Subcooling Margin Monitor.Caused by Condition Existing Since Installation of Plant Process Computer in 1992.Updated LER Will Be Submitted.With 981230 Ltr
ML17335A4581998-12-28028 December 1998
LER 98-052-00:on 981128,turbine Driven AFW Pump Speed Controller Failure Mode Occurred.Caused Because Not All Failure Modes Were Considered When Compressed Air Sys Was Originally Designed.Verified Current Design Change Process
ML17335A4281998-12-22022 December 1998
LER 98-051-00:on 981122,reactor Trip Signal from Manual Safety Injection Not Verified as Required by TS Surveillance,Was Discovered.Maintenance Currently Evaluating Significance & Cause of Event
ML17335A4111998-12-17017 December 1998
LER 98-047-00:on 981117,potential for Increase Leakage from Reactor Coolant Pump Seals Was Identified.Util Is Working with W to Resolve Issue.Current Expectations Are to Submit Update to LER by 990215.With 981217 Ltr
ML17335A4141998-12-16016 December 1998
LER 98-058-00:on 981216,postulated High Line Break Could Result in Condition Outside Design Bases for AF Occurred. Caused by Deficiencies Associated with Administration of HELB Program.Analysis of AF Will Be Completed by 990122
ML17335A4181998-12-16016 December 1998
LER 98-050-00:on 980814,ancillary Equipment Installed in Ice Condenser Was Not Designed to Withstand Design Basis Accident/Earthquake Loads.Caused by Lack of Established Design Criteria.Developed Design Criteria
ML17335A3871998-12-11011 December 1998
LER 98-031-01:on 980610,potential Common Mode Failure of RHR Pumps Were Noted.Caused by Inaccurate Values.Accurate Miniflow Numbers Have Been Determined by Flow Testing
ML17335A3821998-12-0808 December 1998
LER 98-039-01 Re EOP Step Conflicts with Small Break LOCA Analysis.Ler 98-039-00 Has Been Canceled.With 981208 Ltr
ML17335A3781998-12-0707 December 1998
LER 98-007-00:on 981106,high Energy Line Break Effects in Auxiliary FW Sys Was Noted.Cause of Event Is Under Investigation & Will Be Completed by 990220.Updated LER Will Be Submitted by 990310.With 981207 Ltr
ML17335A3771998-12-0303 December 1998
LER 98-046-00:on 981103,determined That Afs Was Unable to Meet Design Flow Requirements During Special Test.Caused by Failure to Consider All Aspects of Sys Operation in Design of Suction Basket Strainers.Sys Will Be Redesigned
ML17335A3741998-12-0202 December 1998
LER 97-011-02:on 970822,operation Was Noted Outside Design Bases for ECCS & CSP for Switchover to Recirculation Sump Suction.Caused by Ineffective Change Mgt.Revised Procedure for Switchover 01(02) Ohp 4023.ES-1.3
1999-09-17
[Table view]
Category:RO)
MONTHYEARML17335A5641999-10-18018 October 1999
LER 99-024-00:on 990708,literal TS Requirements Were Not Met by Accumlator Valve Surveillance.Caused by Misjudgement Made in Conversion from Initial DC Cook TS to W Std Ts.Submitted License Amend Request.With 991018 Ltr
ML17335A5531999-10-0707 October 1999
LER 99-023-00:on 990907,inadequate TS Surveillance Testing of ESW Pump ESF Response Time Noted.Caused by Inadequate Understanding of Plant Design Basis.Surveillance Tests Will Be Revised & Implemented
ML17326A1291999-09-17017 September 1999
LER 99-022-00:on 990609,electrical Bus Degraded Voltage Setpoints Too Low for Safety Related Loads,Was Discovered. Caused by Lack of Understanding of Design of Plant.No Immediate Corrective Actions Necessary
ML17326A1121999-08-27027 August 1999
LER 99-021-00:on 990728,determined That GL 96-01 Test Requirements Were Not Met in Surveillance Tests.Caused by Failure to Understand Full Extent of GL Requirements. Surveillance Procedures Will Be Revised or Developed
ML17326A1011999-08-26026 August 1999
LER 99-020-00:on 990727,EDGs Were Declared Inoperable.Caused by Inadequate Protection of Air Intake,Exhaust & Room Ventilation Structures from Tornado Missile Hazards. Implemented Compensatory Measures in Form of ACs
ML17326A0911999-08-16016 August 1999
LER 99-019-00:on 990716,noted Victoreen Containment Hrrms Not Environmentally Qualified to Withstand post-LOCA Conditions.Caused by Inadequate Design Control.Reviewing Options to Support Hrrms Operability in Modes 1-4
ML17326A0771999-08-0404 August 1999
LER 98-029-01:on 980422,noted That Fuel Handling Area Ventilation Sys Was Inoperable.Caused by Original Design Deficiency.Radiological Analysis for Spent Fuel Handling Accidents in Auxiliary Bldg Will Be Redone by 990830
ML17326A0741999-07-29029 July 1999
LER 99-018-00:on 990629,determined That Valve Yokes May Yield Under Combined Stress of Seismic Event & Static,Valve Closed,Stem Thrust.Caused by Inadequate Design of Associated Movs.Operability Determinations Were Performed for Valves
ML17326A0661999-07-26026 July 1999
LER 99-017-00:on 990625,noted That Improperly Installed Fuel Oil Return Relief Valve Rendered EDG Inoperable.Caused by Personnel Error.Fuel Oil Return Valve Was Replaced with Valve in Correct Orientation.With 990722 Ltr
ML17326A0651999-07-22022 July 1999
LER 98-014-03:on 980310,noted That Response to high-high Containment Pressure Procedure Was Not Consistent with Analysis of Record.Caused by Inadequate Interface with W. FRZ-1 Will Be Revised to Be Consistent with New Analysis
ML17326A0491999-07-13013 July 1999
LER 99-016-00:on 990615,TS Requirements for Source Range Neutron Flux Monitors Not Met.Caused by Failure to Understand Design Basis of Plant.Procedures Revised.With 990713 Ltr
ML17326A0331999-07-0101 July 1999
LER 99-004-01:on 971030,failure to Perform TS Surveillance Analyses of Reactor Coolant Chemistry with Fuel Removed Was Noted.Caused by Ineffective Mgt of Tss.Chemistry Personnel Have Been Instructed on Requirement to Follow TS as Written
ML17326A0151999-06-18018 June 1999
LER 99-014-00:on 990521,determined That Boron Injection Tank Manway Bolts Were Not Included in ISI Program,Creating Missed Exam for Previous ISI Interval.Caused by Programmatic Weakness.Isi Program & Associated ISI Database Modified
ML17325B6311999-06-0101 June 1999
LER 99-S03-00:on 990430,vital Area Barrier Degradation Was Noted.Caused by Inadequate Insp & Maint of Vital Area Barrier.Repairs & Mods Were Made to Barriers to Eliminate Degraded & Nonconforming Conditions
ML17325B6421999-06-0101 June 1999
LER 99-013-00:on 990327,safety Injection & Centrifugal Charging Throttle Valve Cavitation During LOCA Could Have Led to ECCS Pump Failure.Caused by Inadequate Original Design Application of Si.Throttle Valves Will Be Developed
ML17325B6351999-05-28028 May 1999
LER 99-S02-00:on 990428,vulnerability in Safeguard Sys That Could Allow Unauthorized Access to Protected Area Was Noted. Caused by Inadequate Original Plant Design.Mods Were Made to Wall Opening to Eliminate Nonconforming Conditions
ML17265A8231999-05-24024 May 1999
LER 98-037-01:on 990422,determined That Ice Condenser Bypass Leakage Exceeds Design Basis Limit.Caused by Pressure Seal Required by Revised W Design Not Incorporated Into Aep Design.Numerous Matl Condition Walkdowns & Assessments Made
ML17325B6001999-05-20020 May 1999
LER 99-012-00:on 990420,concluded That Auxiliary Bldg ESF Ventilation Sys Not Capable of Maintaining ESF Room Temps post-accident.Caused by Inadequate Control of Sys Design Inputs.Comprehensive Action Plan Being Developed
ML17325B5861999-05-10010 May 1999
LER 99-002-00:on 990415,discovered That TS 4.0.5 Requirements Were Not Met Due to Improperly Performed Test. Caused by Incorrect Interpretation of ASME Code.App J Testing Will Be Completed & Procedures Will Be Revised
ML17325B5811999-05-0404 May 1999
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
ML17325B5771999-05-0303 May 1999
LER 99-010-00:on 990401,RCS Leak Detection Sys Sensitivity Not in Accordance with Design Requirements Occurred.Caused by Inadequate Original Design of Containment Sump Level. Evaluation Will Be Performed to Clearly Define Design
ML17325B5581999-04-16016 April 1999
LER 99-006-00:on 990115,personnel Identified Discrepancy Between TS 3.9.7 Impact Energy Limit & Procedure 12 Ohp 4030.STP.046.Caused by Lack of Design Basis Control.Placed Procedure 12 Ohp 4030.STP.046 on Administrative Hold
ML17325B5471999-04-12012 April 1999
LER 99-009-00:on 990304,as-found RHR Safety Relief Valve Lift Setpoint Greater than TS Limit Occurred.Cause Investigation for Condition Has Not Been Completed.Update to LER Will Be Submitted,Upon Completion of Investigation
ML17325B5321999-04-0707 April 1999
LER 99-S01-00:on 990308,discovered That Lock for Vital Gate Leading to Plant 4KV Switchgear Area Was Nonconforming & Vulnerable to Unauthorized Access.Caused by Inadequate Gate Design & Inadequate Procedures.Mods Are Being Made to Gate
ML17325B5161999-04-0101 April 1999
LER 99-007-00:on 981020,calculations Showed That Divider Barrier Between Upper & Lower Containment Vols Were Overstressed.Engineers Are Currently Working on Analyses of Loads & Stress on Enclosures
ML17325B5221999-03-29029 March 1999
LER 99-001-00:on 960610,degraded Component Cooling Water Flow to Containment Main Steam Line Penetrations,Identified on 990226.Caused by Inadequate Understanding of Design Basis.Additional Investigations Ongoing
ML17325B4801999-03-18018 March 1999
LER 99-004-00:on 971030,failure to Perform TS Surveillance Analyses of Rc Chemistry with Fuel Removed Was Noted.Cause of Event Is Under Investigation.Corrected Written Job Order Activities Used to Control SD Chemistry Sampling
ML17325B4741999-03-18018 March 1999
LER 99-005-00:on 940512,determined That Rt Breaker Manual Actuations During Rod Drop Testing Were Not Previously Reported.Caused by Lack of Training.Addl Corrective Actions,Including Preventative Actions May Be Developed
ML17325B4571999-02-24024 February 1999
LER 99-003-00:on 990107,CR Pressurization Sys Surveillance Test Did Not Test Sys in Normal Operating Condition.Caused by Failure to Recognize Door 12DR-AUX415 as Part of CR Pressure Boundary.Performed Walkdown of Other Doors
ML17335A5171999-02-11011 February 1999
LER 99-002-00:on 990112,determined That RCS Pressurizer PORVs Had Not Been Tested,Per Ts.Caused by Inadequate Scheduling Controls Allowing Personnel Error.Surveillance Procedure Was Completed & Updated LER Will Be Submitted
ML17335A5141999-02-10010 February 1999
LER 99-001-00:on 990106,noted That GE Hfa Relays Installed in EDGs May Not Meet Seismic Qualification.Caused by Operating Experience Info Incorrectly Dispositioned in 1985. Updated LER Will Be Submitted by 990405
ML17335A5011999-02-0101 February 1999
LER 98-060-00:on 981231,identified That Rt Sys Response Time Testing Did Not Comply with TS Definition.Caused by Inadequate Procedures.Corrective Actions Will Be Developed & Update to LER Will Be Submitted by 990415.With 990201 Ltr
ML17335A4951999-01-29029 January 1999
LER 98-059-00:on 981230,interim LER -single Failure in Containment Spray Sys Could Result in Containment Spray Ph Outside Design Occurred.Investigation Into Condition Continuing.Update Will Be Submitted by 990514 Ltr
ML17335A4961999-01-27027 January 1999
LER 98-057-00:on 981228,discovered That AFW Valves Were Not Tested IAW Inservice Testing Program.Caused by Failure to Recognize Design Bases Features Re Afws by Personnel. Updated LER Will Be Submittted by 990415.With 990127 Ltr
ML17335A4921999-01-19019 January 1999
LER 98-052-01:on 981128,no Analysis for NSR Sc Manual Loader for Tdafwp Could Be Found in Original Design.Cause Due to All Failure Modes Not Considered When Compressed Air Sys Originally Designed.Performed Review of Components
ML17335A4721999-01-0606 January 1999
LER 98-055-00:on 981207,potential for Condition Outside of Design Bases for Rod Control Sys Was Noted.Caused by Calibration Error Coupled with Single Rod Failure.Condition Rept Investigation Is Ongoing
ML17335A4691999-01-0606 January 1999
LER 98-056-00:on 981211,hot Leg Nozzle Gaps Resulted in Plant Being in Unanalyzed Condition.Analyses Are Being Performed by W to Resolve Problem.Updated LER Will Be Submitted by 990211.With 990106 Ltr
ML17335A4661999-01-0505 January 1999
LER 98-049-00:on 981020,emergency Boron Injection Flow Path Was Inoperable.Caused by Original Design Deficiency. Engineering Evaluation of Event Is Continuing
ML17335A4631999-01-0404 January 1999
LER 98-054-00:on 981202,discovered That at Least One MSSV Had Not Been Reset as Required by Ts.Engineering Is Continuing Review of Extent of Condition for Event.Updated LER Will Be Submitted by 990129.With 990104 Ltr
ML17335A4481998-12-30030 December 1998
LER 98-053-00:on 981130,discovered Use of Inoperable Substitute Subcooling Margin Monitor.Caused by Condition Existing Since Installation of Plant Process Computer in 1992.Updated LER Will Be Submitted.With 981230 Ltr
ML17335A4581998-12-28028 December 1998
LER 98-052-00:on 981128,turbine Driven AFW Pump Speed Controller Failure Mode Occurred.Caused Because Not All Failure Modes Were Considered When Compressed Air Sys Was Originally Designed.Verified Current Design Change Process
ML17335A4281998-12-22022 December 1998
LER 98-051-00:on 981122,reactor Trip Signal from Manual Safety Injection Not Verified as Required by TS Surveillance,Was Discovered.Maintenance Currently Evaluating Significance & Cause of Event
ML17335A4111998-12-17017 December 1998
LER 98-047-00:on 981117,potential for Increase Leakage from Reactor Coolant Pump Seals Was Identified.Util Is Working with W to Resolve Issue.Current Expectations Are to Submit Update to LER by 990215.With 981217 Ltr
ML17335A4141998-12-16016 December 1998
LER 98-058-00:on 981216,postulated High Line Break Could Result in Condition Outside Design Bases for AF Occurred. Caused by Deficiencies Associated with Administration of HELB Program.Analysis of AF Will Be Completed by 990122
ML17335A4181998-12-16016 December 1998
LER 98-050-00:on 980814,ancillary Equipment Installed in Ice Condenser Was Not Designed to Withstand Design Basis Accident/Earthquake Loads.Caused by Lack of Established Design Criteria.Developed Design Criteria
ML17335A3871998-12-11011 December 1998
LER 98-031-01:on 980610,potential Common Mode Failure of RHR Pumps Were Noted.Caused by Inaccurate Values.Accurate Miniflow Numbers Have Been Determined by Flow Testing
ML17335A3821998-12-0808 December 1998
LER 98-039-01 Re EOP Step Conflicts with Small Break LOCA Analysis.Ler 98-039-00 Has Been Canceled.With 981208 Ltr
ML17335A3781998-12-0707 December 1998
LER 98-007-00:on 981106,high Energy Line Break Effects in Auxiliary FW Sys Was Noted.Cause of Event Is Under Investigation & Will Be Completed by 990220.Updated LER Will Be Submitted by 990310.With 981207 Ltr
ML17335A3771998-12-0303 December 1998
LER 98-046-00:on 981103,determined That Afs Was Unable to Meet Design Flow Requirements During Special Test.Caused by Failure to Consider All Aspects of Sys Operation in Design of Suction Basket Strainers.Sys Will Be Redesigned
ML17335A3741998-12-0202 December 1998
LER 97-011-02:on 970822,operation Was Noted Outside Design Bases for ECCS & CSP for Switchover to Recirculation Sump Suction.Caused by Ineffective Change Mgt.Revised Procedure for Switchover 01(02) Ohp 4023.ES-1.3
1999-09-17
[Table view]
Category:TEXT-SAFETY REPORT
MONTHYEARML17335A5641999-10-18018 October 1999
LER 99-024-00:on 990708,literal TS Requirements Were Not Met by Accumlator Valve Surveillance.Caused by Misjudgement Made in Conversion from Initial DC Cook TS to W Std Ts.Submitted License Amend Request.With 991018 Ltr
ML17335A5531999-10-0707 October 1999
LER 99-023-00:on 990907,inadequate TS Surveillance Testing of ESW Pump ESF Response Time Noted.Caused by Inadequate Understanding of Plant Design Basis.Surveillance Tests Will Be Revised & Implemented
ML17335A5631999-09-30030 September 1999
Monthly Operating Rept for Sept 1999 for DC Cook Nuclear Plant,Unit 1.With 991012 Ltr
ML17335A5621999-09-30030 September 1999
Monthly Operating Rept for Sept 1999 for DC Cook Nuclear Plant,Unit 2.With 991012 Ltr
ML17335A5481999-09-30030 September 1999
Non-proprietary DC Cook Nuclear Plant Units 1 & 2 Mods to Containment Sys W SE (Secl 99-076,Rev 3).
ML17335A5451999-09-28028 September 1999
Rev 1 to Containment Sump Level Design Condition & Failure Effects Analysis for Potential Draindown Scenarios.
ML17326A1291999-09-17017 September 1999
LER 99-022-00:on 990609,electrical Bus Degraded Voltage Setpoints Too Low for Safety Related Loads,Was Discovered. Caused by Lack of Understanding of Design of Plant.No Immediate Corrective Actions Necessary
ML17326A1481999-09-17017 September 1999
Independent Review of Control Rod Insertion Following Cold Leg Lbloca,Dc Cook,Units 1 & 2.
ML17326A1211999-08-31031 August 1999
Monthly Operating Rept for Aug 1999 for Cook Nuclear Plant, Unit 2.With 990915 Ltr
ML17326A1201999-08-31031 August 1999
Monthly Operating Rept for Aug 1999 for Cook Nuclear Plant, Unit 1.With 990915 Ltr
ML17326A1121999-08-27027 August 1999
LER 99-021-00:on 990728,determined That GL 96-01 Test Requirements Were Not Met in Surveillance Tests.Caused by Failure to Understand Full Extent of GL Requirements. Surveillance Procedures Will Be Revised or Developed
ML17326A1011999-08-26026 August 1999
LER 99-020-00:on 990727,EDGs Were Declared Inoperable.Caused by Inadequate Protection of Air Intake,Exhaust & Room Ventilation Structures from Tornado Missile Hazards. Implemented Compensatory Measures in Form of ACs
ML17326A0911999-08-16016 August 1999
LER 99-019-00:on 990716,noted Victoreen Containment Hrrms Not Environmentally Qualified to Withstand post-LOCA Conditions.Caused by Inadequate Design Control.Reviewing Options to Support Hrrms Operability in Modes 1-4
ML17326A0771999-08-0404 August 1999
LER 98-029-01:on 980422,noted That Fuel Handling Area Ventilation Sys Was Inoperable.Caused by Original Design Deficiency.Radiological Analysis for Spent Fuel Handling Accidents in Auxiliary Bldg Will Be Redone by 990830
ML17335A5461999-08-0202 August 1999
Rev 0 to Evaluation of Cook Recirculation Sump Level for Reduced Pump Flow Rates.
ML17326A0871999-07-31031 July 1999
Monthly Operating Rept for July 1999 for DC Cook Nuclear Plant,Unit 1.With 990812 Ltr
ML17326A0861999-07-31031 July 1999
Monthly Operating Rept for July 1999 for DC Cook Nuclear Plant,Units 2.With 990812 Ltr
ML17326A0741999-07-29029 July 1999
LER 99-018-00:on 990629,determined That Valve Yokes May Yield Under Combined Stress of Seismic Event & Static,Valve Closed,Stem Thrust.Caused by Inadequate Design of Associated Movs.Operability Determinations Were Performed for Valves
ML17326A0661999-07-26026 July 1999
LER 99-017-00:on 990625,noted That Improperly Installed Fuel Oil Return Relief Valve Rendered EDG Inoperable.Caused by Personnel Error.Fuel Oil Return Valve Was Replaced with Valve in Correct Orientation.With 990722 Ltr
ML17326A0651999-07-22022 July 1999
LER 98-014-03:on 980310,noted That Response to high-high Containment Pressure Procedure Was Not Consistent with Analysis of Record.Caused by Inadequate Interface with W. FRZ-1 Will Be Revised to Be Consistent with New Analysis
ML17326A0491999-07-13013 July 1999
LER 99-016-00:on 990615,TS Requirements for Source Range Neutron Flux Monitors Not Met.Caused by Failure to Understand Design Basis of Plant.Procedures Revised.With 990713 Ltr
ML17326A0331999-07-0101 July 1999
LER 99-004-01:on 971030,failure to Perform TS Surveillance Analyses of Reactor Coolant Chemistry with Fuel Removed Was Noted.Caused by Ineffective Mgt of Tss.Chemistry Personnel Have Been Instructed on Requirement to Follow TS as Written
ML17326A0511999-06-30030 June 1999
Monthly Operating Rept for June 1999 for DC Cook Nuclear Plant,Unit 2.With 990709 Ltr
ML17326A0501999-06-30030 June 1999
Monthly Operating Rept for June 1999 for DC Cook Nuclear Plant,Unit 1.With 990709 Ltr
ML17326A0151999-06-18018 June 1999
LER 99-014-00:on 990521,determined That Boron Injection Tank Manway Bolts Were Not Included in ISI Program,Creating Missed Exam for Previous ISI Interval.Caused by Programmatic Weakness.Isi Program & Associated ISI Database Modified
ML17325B6421999-06-0101 June 1999
LER 99-013-00:on 990327,safety Injection & Centrifugal Charging Throttle Valve Cavitation During LOCA Could Have Led to ECCS Pump Failure.Caused by Inadequate Original Design Application of Si.Throttle Valves Will Be Developed
ML17325B6311999-06-0101 June 1999
LER 99-S03-00:on 990430,vital Area Barrier Degradation Was Noted.Caused by Inadequate Insp & Maint of Vital Area Barrier.Repairs & Mods Were Made to Barriers to Eliminate Degraded & Nonconforming Conditions
ML17326A0061999-05-31031 May 1999
Monthly Operating Rept for May 1999 for Dcp.With 990609 Ltr
ML17326A0071999-05-31031 May 1999
Monthly Operating Rept for May 1999 for DC Cook Nuclear Plant,Unit 2.With 990609 Ltr
ML17325B6351999-05-28028 May 1999
LER 99-S02-00:on 990428,vulnerability in Safeguard Sys That Could Allow Unauthorized Access to Protected Area Was Noted. Caused by Inadequate Original Plant Design.Mods Were Made to Wall Opening to Eliminate Nonconforming Conditions
ML17265A8231999-05-24024 May 1999
LER 98-037-01:on 990422,determined That Ice Condenser Bypass Leakage Exceeds Design Basis Limit.Caused by Pressure Seal Required by Revised W Design Not Incorporated Into Aep Design.Numerous Matl Condition Walkdowns & Assessments Made
ML17325B6001999-05-20020 May 1999
LER 99-012-00:on 990420,concluded That Auxiliary Bldg ESF Ventilation Sys Not Capable of Maintaining ESF Room Temps post-accident.Caused by Inadequate Control of Sys Design Inputs.Comprehensive Action Plan Being Developed
ML17325B5861999-05-10010 May 1999
LER 99-002-00:on 990415,discovered That TS 4.0.5 Requirements Were Not Met Due to Improperly Performed Test. Caused by Incorrect Interpretation of ASME Code.App J Testing Will Be Completed & Procedures Will Be Revised
ML17325B5811999-05-0404 May 1999
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
ML17325B5771999-05-0303 May 1999
LER 99-010-00:on 990401,RCS Leak Detection Sys Sensitivity Not in Accordance with Design Requirements Occurred.Caused by Inadequate Original Design of Containment Sump Level. Evaluation Will Be Performed to Clearly Define Design
ML17335A5301999-04-30030 April 1999
Monthly Operating Rept for Apr 1999 for DC Cook Nuclear Plant,Unit 1.With 990508 Ltr
ML17335A5291999-04-30030 April 1999
Monthly Operating Rept for Apr 1999 for DC Cook Nuclear Plant,Unit 2.With 990508 Ltr
ML17325B5581999-04-16016 April 1999
LER 99-006-00:on 990115,personnel Identified Discrepancy Between TS 3.9.7 Impact Energy Limit & Procedure 12 Ohp 4030.STP.046.Caused by Lack of Design Basis Control.Placed Procedure 12 Ohp 4030.STP.046 on Administrative Hold
ML17325B5471999-04-12012 April 1999
LER 99-009-00:on 990304,as-found RHR Safety Relief Valve Lift Setpoint Greater than TS Limit Occurred.Cause Investigation for Condition Has Not Been Completed.Update to LER Will Be Submitted,Upon Completion of Investigation
ML17325B5321999-04-0707 April 1999
LER 99-S01-00:on 990308,discovered That Lock for Vital Gate Leading to Plant 4KV Switchgear Area Was Nonconforming & Vulnerable to Unauthorized Access.Caused by Inadequate Gate Design & Inadequate Procedures.Mods Are Being Made to Gate
ML17325B5161999-04-0101 April 1999
LER 99-007-00:on 981020,calculations Showed That Divider Barrier Between Upper & Lower Containment Vols Were Overstressed.Engineers Are Currently Working on Analyses of Loads & Stress on Enclosures
ML17325B5491999-03-31031 March 1999
Monthly Operating Rept for Mar 1999 for DC Cook Nuclear Plant Unit 2.With 990408 Ltr
ML17325B5441999-03-31031 March 1999
Monthly Operating Rept for Mar 1999 for DC Cook Nuclear Plant,Unit 1.With 990408 Ltr
ML17325B5221999-03-29029 March 1999
LER 99-001-00:on 960610,degraded Component Cooling Water Flow to Containment Main Steam Line Penetrations,Identified on 990226.Caused by Inadequate Understanding of Design Basis.Additional Investigations Ongoing
ML17325B4801999-03-18018 March 1999
LER 99-004-00:on 971030,failure to Perform TS Surveillance Analyses of Rc Chemistry with Fuel Removed Was Noted.Cause of Event Is Under Investigation.Corrected Written Job Order Activities Used to Control SD Chemistry Sampling
ML17325B4741999-03-18018 March 1999
LER 99-005-00:on 940512,determined That Rt Breaker Manual Actuations During Rod Drop Testing Were Not Previously Reported.Caused by Lack of Training.Addl Corrective Actions,Including Preventative Actions May Be Developed
ML17325B5671999-03-0202 March 1999
Summary of Unit 1 Steam Generator Layup Chemistry from 980101 to 990218.
ML17325B4631999-02-28028 February 1999
Monthly Operating Rept for Feb 1999 for DC Cook Nuclear Power Station,Unit 2.With 990308 Ltr
ML17325B4621999-02-28028 February 1999
Monthly Operating Rept for Feb 1999 for DC Cook Nuclear Plant,Unit 1.With 990308 Ltr
ML17325B4571999-02-24024 February 1999
LER 99-003-00:on 990107,CR Pressurization Sys Surveillance Test Did Not Test Sys in Normal Operating Condition.Caused by Failure to Recognize Door 12DR-AUX415 as Part of CR Pressure Boundary.Performed Walkdown of Other Doors
1999-09-30
[Table view] |
Text
E NRC Form 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVEOSYOMB)IO.31~104 EXP)REB 06r30)2001 (6-1998) ESTSJATED SVRDEN PER RESPONSE TO COMPLY WITH TIES MANDATORY INFORMATIONCOLLECDON RECVESP. 50JJ HRS. REPORTED lESSONS lEARHED ARE INCORPORATED VITO THE UCENSINO PROCESS AND FED SACK 'TO INDVSTRY.
L(CENSEE EVENT REPORT (LER)
(See reverse for required number of 20MS P~
FORWARD COMNBPS REOARDVIO SVRDEN ESTSIATE TO THE INFORMATION AND RECORDS MANAOEMENT SRANCH IT% FSSL V.S. NVCLEAR REOVIATORY COLSSSSON, WASHSIOTON, DC 2N554NI. AND TO THE REDVCTION PRO/ECt O1100100, OFACE OF MANAOEMENT AJID SVOOET, WASISNOTON, DC digits/characters for each block)
FACIUTY NAME (I ) DOCKET NUMBER t2) PAOE IS)
Cook Nuclear Plant Unit 1 05000-315 1 of3 TITLE (4)
Safety Injection and CentNugat Charging Throttle Valve Cavitation During LOCA Could Lead to ECCS Pump Failure EVENT DATE {6) LER NUMBER {6) REPORT DATE (7) OTHER FACILITIES INVOLVED(6)
ACIUTY NAME SEQUENTIAL REVISION D.C. Cook, Unit 2 05000-316 MONTH DAY YEAR YEAR NUMBER NUMBER MONTH 'DAY YEAR FACIUTY NAM NUM R 03 27 1999 1999 013 00 06 01 1999 OPERATING THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR li: (Check one or more) (11)
MODE (9) 20.2201 (b) 20.2203(a)(2)(v) 50.73(a)(2)(l) 50.73(a)(2)(viii)
POVlER 20.2203(a)(t) 20.2203(a)(3)(I) 50.73(a)(2)(6) 50.73(a)(2)(x)
LEVEL (10) 0 73.71 20.2203(a)(2N) 20.2203(a)(3)(9) 50.73{a)(2)(iii) 20.2203{a) {2)(ii) 20.2203(a)(4) 50.73(a)(2)(lv) OTHER 20.2203(a)(2)(ui) 50.36(c)(1) 50.73(a)(2)(v)
SPPCEF in AIJSVect IJeNAN 20.2203(a)(2)(iv) 50.36(c)(2) 50.73(a)(2)(vti) 01 n NRC Form MEA UCENSEE CONTACT FOR THIS LER (12)
TELEPHONE NUMBER 0IcIvde Area Code)
Ms. Brenda W. O'ourke, Compliance Engineer (616) 465-5901 x2604 COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT {13)
REPORTABLE REPORTABLE TO COMPONENT MANUFACTURER TO EPIX COMPONENT MANUFACTURER EPIX SUPPLEMENTAL REPORT EXPECTED 14 EXPECTED YEAR X YES SUBMISSION 12 01 1999 IfYes, corn lete EXPECTED SUBMISSION DATE NO DATE 15 Abstract {Umitto 1400 spaces, I.e., approximately 15 single-spaced typewritten lines) (16)
On March 27, 1999, during development of an Emergency Core Cooling System (ECCS) thermal hydraulic flow analysis model, Engineering concluded that preliminary hydraulic flow analysis results indicated that the Unit 1 Safety Injection (Sl) and Centrifugat Charging (CC) throttle valves could potentially experience cavitation during a LOCA. Specifically, during a LOCA, large differential pressures created across the Sl and CC throttle valves would result in cavitation and possible mechanical erosion of the valves and downstream piping. During post-LOCA conditions, throttle valve erosion could lead to a pump runout condition and subsequent failure of the ECCS pumps. Radiography performed to determine valve position showed the valves to be less open than predicted by the hydraulic analysis. This condition could result in LOCA generated debris becoming lodged in the throttle valve, resulting in reduced flow to the reactor core. Similar conditions exist for the Unit 2 Sl and CC throttle valves. During continuing evaluation, plant personnel concluded that the conditions were reportable on May 4, 1999, and a 4-hour notification was made to the NRC in accordance with 10CFR50.72, for a condition that resutted in the plant being in an unanalyzed condition, and for any event or condition that alone could have prevented the fulfillment of the Sl or CC system safety function needed to mitigate the consequences of an accident.
The preliminary cause is inadequate original design application of the Sl and CC throttle valves. Because five of the six Unit 1 throttle valves were found to be less than 44 percent open, these vatves could be assumed to be partially or fully plugged with debris although the amount of plugging would depend on the nature and geometry of the debris. However, partial or full plugging could render the systems not capable of performing their intended safety function during the recirculation phase of a LOCA event. As part of the evaluation, a permanent solution for the cavitation-induced erosion and potential debris plugging will be devetoped to restore conformance with the plant design basis and to support ECCS operability. Possible modifications are currently under review and the method selected will be implemented prior to restart of each unit. A supplement to this LER will be provided upon completion of the condition evaluation.
9906080i48 'T)9060i PDR ADQCK 050003i5 8 PDR
NRC FORM 366A U.S. NUCLEAR REGULATORY COMMISSION (6-1998)
LICENSEE EVENT REPORT (LER)
~ TEXT CONTINUATION FACILITYNAME (1) DOCKETNUMBER(2) LER NUMBER (6) PAGE (3)
YEAR SEQUENTIAL REVISION Cook Nuclear Plant Unit 1 05000-315 NUMBER NUMBER 2 of 3 1999 013 00 TEXT (Ifmore space is required, use additional copies of NRC Form (366A) (17)
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 March 27, 1999, during development of an Emergency Core Cooling System (ECCS) thermal hydraulic flow analysis model, Engineering concluded that preliminary hydraulic flow analysis results indicated that the Unit 1 Safety Injection (Sl)[BQ] and Centrifugal Charging (CC)[SJJ throttle valves [FCVJ could potentially experience cavitation during a LOCA.
Specifically, during a LOCA, large differential pressures created across the Sl and CC throttle valves would result in cavitation and possible mechanical erosion of the valves and downstream piping. Throttle valve erosion during post-LOCA conditions could cause the valves to allow excess flow through the Sl and CC pumps, which could lead to a pump runout condition and subsequent failure of the ECCS pumps.
The preliminary flow analysis also predicted that the Sl and CC throttle valves would be less open than previously determined during evaluation of an industry event in 1995. In addition, actual valve stem measurements concluded that the Sl and CC throttle valves were less open than predicted by the preliminary flow analysis. As a result, radiography was performed on April 8, 1999, for two Sl throttle valves to better assess their position. Radiography results also concluded that the throttle valves were more closed than'predicted by the hydraulic analysis, and also showed indications of possible valve erosion. With the throttle valves found less open, debris generated in containment during a LOCA could potentially become lodged in the throttle valves, resulting in reduced flow to the reactor core. Similar conditions exist for the Unit 2 Sl and CC throttle valves. During continuing evaluation of the identified conditions, on May 4, 1999, plant personnel concluded that these conditions were reportable to the NRC.
Cause of Event The preliminary cause is inadequate original design application of the Sl and CC throttle valves. At the time of original plant design, this throttle valve design was commonly used throughout the industry for the same throttling application.
However, it was not recognized that these valves are susceptible to mechanical cavitation damage as a result of high differential pressures across the valve.
Opportunities to identify this potential condition were missed during previous evaluations of industry events regarding the potential for post-LOCA ECCS pump runout damage due to throttle valve degradation.
Anal sis of Event In accordance with the requirements of 10CFR50.72(b)(2)(i) and 10CFR50.72(b)(2)(iii)(D), a 4-hour notification was made to the NRC for a condition that resulted in the plant being in an unanalyzed condition, and for any event or condition that alone could have prevented the fulfillment of the Sl or CC system safety function needed to mitigate the consequences of an accident. As such, this LER is being submitted in accordance with the requirements of 10CFR50.73.
UFSAR Section 6.2 states that the primary function of the ECCS is to provide cooling water to the reactor core in the event of a LOCA. The ECCS system consists of six ECCS pumps: two Centrifugal Charging pumps, two Residual Heat Removal (RHR) pumps, and two Safety Injections pumps. The subject throttle valves are installed on each of the four CC pump lines to the reactor coolant loops and on the discharge side of each Sl pump.
NRC FORM 366A (6-1998)
NRC FORM 366A U.S. NUCLEAR REGULATORY COMMISSION (6-1998)
LICENSEE EVENT REPORT (LER)
~ TEKF CONTINUATION DOCKETNUMBER(2) LER NUMBER (6) PAGE (3)
FACIUTYNAME (1)
YEAR SEQUENTIAL REVISION Cook Nuclear Plant Unit 1 05000-315 NUMBER NUMBER 3of3 1999 013 00 TEXT (Ifmore space ls required, use additional copies ofNRC Form (366A) (17)
The operation of the ECCS following a LOCA consists of two distinct phases: 1) the injection phase during which reactivity is controlled, initial cooling of the core is accomplished, and coolant lost from the primary system is replenished, and 2) the recirculation phase, in which long term core cooling is provided during the accident recovery period. Long term core cooling is provided, in part, by the Sl and CC systems that deliver coolant water from the containment recirculation sump back to the reactor coolant system. Following a LOCA event, any debris that was generated in containment will be filtered through a 0.25-inch square mesh screen [BP](SCN] prior to entering the containment sump to prevent foreign material from entering the ECCS system.
V The preliminary results of the ECCS hydraulic flow analysis were used to calculate the potential cavitation damage to the Sl and CC throttle valves under various ECCS system operating configurations. The most limiting operating configuration assumes the throttle valves to be wide open to simulate the maximum erosion condition. The flow analysis concluded that with the throttle valves wide open, cavitation would likely occur and the Sl pumps would be in a runout condition, while both CC pumps would remain available. For the case where only one CC pump is running, analysis results conclude that the single CC pump would go to the runout condition, in addition to both Sl pumps. For this configuration, calculations indicate that the Sl valves would be in a choked flow condition, which could cause cavitation-induced erosion of the valves and/or downstream piping. In addition, the CC throttle valves were calculated to be in the incipient damage range, which is the level at which cavitation is considered sufficient to result in erosion damage. Westinghouse letter NSAL-96-001, "Erosion of Globe Valves in ECCS Throttling Applications," indicates that even with throttle valve erosion, the CC and Sl pumps should remain operable long enough to allow the operators to use the RHR pumps for long term cooling. However, no formal analysis has been performed to validate the impact this condition has on long term ECCS post-LOCA operation.
Information received from the valve manufacturer requires the throttle valves to be approximately 44 percent open to ensure debris would not become lodged in the valve. Because five of the six Unit 1 throttle valves were found to be less than 44 percent open, these valves could be assumed to be partially or fully plugged with debris although the amount of plugging would depend on the nature and geometry of the debris. However, partial or full plugging of the Sl and CC throttle valves could render the systems not capable of performing their intended safety function during the recirculation phase of a LOCA.
Corrective Actions A permanent solution for the cavitation-induced erosion and potential debris plugging of the throttle valves will be developed to restore conformance with the plant design basis and to support ECCS system operability. Possible modifications are currently under review and the method selected will be implemented prior to,restart of each unit.
As part of the Restart effort, an improved operating experience program is being developed. In addition, the Expanded System Readiness Review project teams are evaluating operating experience information to assess whether applicable industry issues have been adequately addressed for applicability to D.C. Cook.
The adequacy of the systems to perform their safety and accident mitigation functions is being reviewed during the discovery process at D.C. Cook under a number of system assessments and programmatic assessments to support the Restart Plan. These include the Expanded System Readiness Review (ESRR) and the Licensing Basis Review. Identified deficiencies are being addressed under the Corrective Action Program.
The evaluation for this condition has not been completed. Based on the results of the completed evaluation, information regarding the safety significance, and corrective and preventive actions will be provided in an update to this LER.
Previous Similar Events None
~ NRC FORM 366A (6-1998)