05000255/LER-1998-001, :on 980101,large Leak of CCW During Power Operation Was Noted.Caused by Failure of Flanged Joint Rubber Gasket.Ccw Sys Was Refilled,Vented & Chemistry Restored to Normal
| ML20202E460 | |
| Person / Time | |
|---|---|
| Site: | Palisades  |
| Issue date: | 02/02/1998 |
| From: | Kozup C CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| To: | |
| Shared Package | |
| ML18067A831 | List: |
| References | |
| LER-98-001, LER-98-1, NUDOCS 9802180154 | |
| Download: ML20202E460 (5) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(1) 10 CFR 50.73(a)(2)(iv), System Actuation 10 CFR 50.73(a)(2) |
| 2551998001R00 - NRC Website | |
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NRC FORed 304 -
U.S. NUCLEAR REiULATORY _
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- - PALISADES NUCLEAR PLANT 05000255 1 of 5 TITLE - LARGE LEAK OF COMPONENT COOLING WATER DURING POWER OPERATION EVENT DATE LER NUMBER REPORT DATE OTHER FACILITlES INVOLVED 0E
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MONTH DAY
. YEAR YEAR MONTH DAY YEAR N 8ER N 8 0
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- - 2 98 rActuTY NAME DOCKET NUMBER OPERATING THIS REPORT IS SUstelTT1!D PURSUANT To THE REQJIRERIENTS OF 10 CFRU (check one or more)
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N 20.2201(b) 20 2203(aX2)(v) 50.73(a)(2)(1) -
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20.2203(aX3Xn) 50.73(aX2Xin) 73.71 20.2203(a)(2Xn) 20.2203(a)(4) 50.73(a)(2)(iv)
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20.2203(aX2)(in) 50.36(c)(1) x 50.73(aX2Xv)
Specify in Abstract below 20 2203(a)(2)(iv) 50.36(c)(2) 50.73(a)(2)(vil) or in NRc Form 366A LIC:=: CONTACT FOR THIS LER NAME Charles S. Kozup, UCensing Engineer TELEPHONE NUMBER (include Area Code)
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CAUSE
SYSTEM COMPONENT MANUFACTURER REPORTA8LE
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SYSTEM COMPOWENT MANUFACTURER REPORTABLE TO NPRDS TO NPROS B
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.N X-CC PSV A499-N SUPPLEGAENTAL REPORT EXPECTED MONTH DAY YEAR YES No EXPECTED If yes COMPLETE EXPECTED COMPLETION DATE X
SUBRAISSION DATE ABSTRACT At 1500 hours0.0174 days <br />0.417 hours <br />0.00248 weeks <br />5.7075e-4 months <br /> on January 1,1998, the plant was operating at 100% power. 'A component cooling w ter leak on the 'A' Radioactive Waste Evaporator Distillate Cooler increased from about 100 ml/ min to r. bout 200 gpm, which was more than the makeup capacity of the Component Cooling Water (CCW) system. The leak emptied the CCW Surge tank and resulted in a reduction in the normal CCW Discharge header pressure of about 120 psi to 98 psi. The operators used Off Normal Procedure 6.2 for Loss of Component Cooling Water and isolated applicable components.
The leak was identified and isolated by the operators within about 15 minutes.
No abnormal component temperatures were observed and no effect on the Primary Coolant Pump -
sanls was identified. After the leak was isolated, the operators refilled and vented the CCW system. Isolated components were returned to service. The chemistry of the CCW system was retumed to normal. Multiple venting evolutions were performed over the next several days to c sure all the air was removed from the CCW system.
A multidiscipline review team was created to review the event and develop corrective actions to prsvent similar occurrences in the CCW or other plant systems.
9902190154 990202 PDR ADOCK 05000255 S
NRC FoRH 366A U.S. NUCLEAR REGULATORY CoMMISSloN M5 LICENSEE EVENT REPORT (LER)
TEXT CoNTINUATloN FACILITY NAME DOCKET LER NUMBER PAGE CONSUMERS ENERGY COMPANY YEAR SEQUENTIAL REVISION NMR NMR PALISADES NUCLEAR PLANT 050002ss 2 OF 5 98 001 00 TEXT
EVENT DESCRIPTION
On December 24,1997, an air leak was identified on the solenoid valve for the Evaporator Component Cooling Water (CCW) Return Valve CV-0977B. Air to the solenoid valve was isolated, closing CV-09778, which is its required safety position. The closure of CV-0977B isolated return CCW flow from the evapolator and pressurized the radioactive waste evaporators to full CCW system pressure of about 120 psi. On December 26,1997, maintenance planning determined replacement of the solenoid valve was needed, and that engineering assistance was required.
Since liquid radioactive waste inventory was low, Operations had no concerns with leaving the cvaporator isolated for up to two weeks.
On December 28,1997, a component cooling water leak of about 100 ml/ min was observed coming from a gasketed flange on the 'A' Radioactive Waste Evaporator Distillate Cooler.
Operations began to monitor the leakage several times per shift. On Monday, December 29, 1997, the Fix It Now team observed the leak and determined that attempts to tighten the flange would probably not reduce the leakage and could cause the leakage to increase.
On January 1,1998, at about 1500 hours0.0174 days <br />0.417 hours <br />0.00248 weeks <br />5.7075e-4 months <br />, with the plant cperating at 100% power, the distillate cooler leak increased to about 200 gpm, which was more than the makeup capability of the CCW system. The leak emptied the CCW Surge Tank and resulted in a reduction in the CCW dischaige header pressure to 98 psi, in response, the Shift Supervisor briefed the operating crew and directed a review of Off Normal Procedure (ONP) 6.2," Loss of Component Cooling Water", to prepare the crew for activities to arrest the CCW inventory loss, and prepare for a potential reactor trip. Charging and Volume Control System letdown flow was then isolated and the running charging pump was secured. In stating his expectations to the control room operators, the shift supervisor conservatively directed that if abnormal operating conditions developed on the CCW pumps, the piant was to be shut dawn by tripping the reactor and stopping the primary coolant pumps.
About 1515 hours0.0175 days <br />0.421 hours <br />0.0025 weeks <br />5.764575e-4 months <br />, the operators identified and isolated the CCW leak by closing the Spent Fuel Pool Cooling Valve, CV-0944A, from the control room and by closing the Evaporator Supply Valve, CV-0944, locally. Since CV-0977B, was closed prior to the leak, these actions stopped the leak cnd allowed the CCW system to refill.
After the CCW system refilled, the system was vented multiple times over the next several days to cssure air was removed from the system, and some portions of the CCW system isolated during this event were returned to service.
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.U.$.10 CLEAR REGULATORY CoMMISSloN 4/95 LICENSEE EVENT REPORT (LER)
TEXT CONTINUATION FACILITY NAME I
DOCKET LER NUMBER PAGE CONSUMERS ENERGY COMPANY YEAR SEQUENTIAL REVISION NWBER NWBER PAllSADES NUCLEAR PLANT 05000255 3 OF 5 98 001 00 i
' EXT On January 2,1998, a multidiscipline Incident Response Team was created to investigate this cvent. This team investigated the event to determine if allimmediate corrective actions were identified and adequately completed, and to determine whether any plant actions taken prior to the cvent needed improvement. In addition, the incident Response Team evaluated whether 4
additional corrective actions were needed to prevent additional problems.
ANALYSIS OF THE EVENT
Operator response to the loss of component cooling water was generally very good. The 4
operators quickly identified the source of the leak, isolated it and restored component cooling water. In addition, the Operations crew demonstrated excellent knowledge of the system conditions, and their equipment control and communications were good throughout the event.
Support response from system engineering and health physics organizations was good.
The multidiscipline review determined that some of the actions taken prior to and following the leak could have been improved. Some of the noted deficiencies were:
1)
The method and the materials used in the 1989 gasket replacement in the evaporator were not consistent with current standards. The replacement gasket material was rated for only 100 psi whereas the systern design pressure is 150 psi. This issue raised concerns whether other areas of the plant were susceptible to similar rubber gasket i
leaks.
2)
While using ONP 6.2," Loss of Component Cooling Water", to reestablish CCW inventory, the operating crew identified that the ONP 6.2 direction to start all CCW pumps was not appropriate for this loss of inventory event. This issue raised concerns that other ONP's may contain similar inappropriate instructions.
3)
The operating crew's decision to deviate from the ONP 6.2 instructions to start all CCW pumps did not meet expectations.
4)
Because the leak was quickly isolated, the CCW system refilled and the CCW system continued to operate throughout the event, the staff was slow to recognize that the CCW system had temporarily degraded to the point of inoperability due to air entrainment during the inventory transient. This delayed until the following day the determination that a four hour non-emergency report should be made.
i
r,U.S. NUCLEAR REGULATORY CoMMISSloN 4/95 LICENSEE EVENT REPORT (LER)
TEXT CONTINUATION FACILITY NAME DOCKET LER NUMBER PAGE CONSUMERS ENERGY COMPANY YEAR
$EQvEN M WSON NuuaEn NuueEn PALISADES NUCLEAR PLANT 05000255 4 op 3 98 001 00 T' EXT In addition, the CCW Surge Tank Level Switch setpoints are being evaluated to increase the time between annunciation and subsequent degradation of CCW pump net positive suction head.
This was the first time a multidiscipline incident Response Team was used at Palisades to provide immediate event evaluation. Use of this team was a success.
SAFETY SIGNIFICANCE
The loss of CCW with the plant at power has a relatively low reactor safety significance. The safety significance of the CCW leak was evaluated using the plant risk model and was confirmed through a Plant Safety Analysis review. Plas guidelines for planned maintenance activities cssess a core damage frequency increase ot - 1
- = not significant. This event was determined 4
to increase the core damage frequency by 1.6.
The response of the operating crew to this event was timely, averting a potential plant trip and its cssociated challenge to the engineered safety systems.
CAUSE OF THE EVENT
The loss of CCW was caused by the failure of a flanged joint rubber gasket which was made from Chesterton 124 material and was installed in 1989. The new gasket was not an exact replacement for the original gasket, which was supplied with the evaporator, and was made from Gates R807R rubber. No engineering design change was authorized for the change in gasket materials and configuration. The new material was rated for only 100 psi, while the system design pressure is 150 psi. In addition, the new gasket was not made as a one piece gasket, but as a three piece gasket. This change did not comply with our present standards for maintenance.
The failure to utilize the design change process to specify a gasket of a different material and design is the root cause of this event.
NRC FORM 3HA u.S. NOCLEAR REoVLATORY COMMISSION 445 LICENSEE EVENT REPORT (LER)
TEXT CONTINUATION FACILITY NAME DOCKET LER NUMBER R PAGE CONSUMERS ENERGY COMPANY YEAR SEC, N L R SiON PALISADES NUCLEAR PLANT 05000255
, 5 OF 5 98 001 00 g
' EXT CORRECTIVE ACTIONS COMPLETED T'.ie following actions have been completed.
1)
The CCW system was refilled, vented and chemistry restored to normal.
2)
The solenoid valve on CV-0977B was replaced.
3)
The gasketed flange on the 'A' Radioactive Waste Evaporator Distillate Cooler was replaced.
4)
All the ONP immediate actions were reviewed for possible inappropriate actions.
5)
ONP 6.2 was revised to clarify immediate actions for a loss of CCW inventory.
6)
The use of rubber gaskets in other plant applications was reviewed to determine if any similar failures could result in a challenge to the reliability of other systems. No other applications wcre identified which could challenge the reliability of reactor safety systems.
7)
The operations department was instructed on the proper decision process to be used to deviate from a procedure step in an emergency.
8)
The Maintenance Department planners have been briefed of this event and on the need for design change controls to implement non-exact replacements.
CORRECTIVE ACTIONS TO BE COMPLETED The following actions will be completed.
1)
Reinforce the expectation to promptly evaluate _whether an event could have caused degradation of systems or components that could affect operability, even when system operation appears normal.
2)
The CCW Surge Tank Level Switch setpoints will be evaluated to improve the time between the alarm indication and the subsequent degradation of CCW pump net positive suction head.