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Category:REPORTABLE OCCURRENCE REPORT (SEE ALSO AO LER)
MONTHYEARCY-99-047, Ro:On 981217,identified Unsuccessful Dewatering of Cnsi HIC, Model PL8-120R,containing Resins.Caused by Apparent Failure of Dewatering Tree.Other HICs Have Been Procured,Recertified & Returned to Plant for Use1999-03-23023 March 1999 Ro:On 981217,identified Unsuccessful Dewatering of Cnsi HIC, Model PL8-120R,containing Resins.Caused by Apparent Failure of Dewatering Tree.Other HICs Have Been Procured,Recertified & Returned to Plant for Use CY-98-136, Ro:On 980727,flow Blockage Occurred & Caused Pressure in Sys to Increase,Resulting in Relief Valve Lifting & Pipe Vibration,Which Caused Leaks to Develop.Caused by Nearly Closed post-filter Inlet Valve.Repaired 2 Leaks in Line1998-08-12012 August 1998 Ro:On 980727,flow Blockage Occurred & Caused Pressure in Sys to Increase,Resulting in Relief Valve Lifting & Pipe Vibration,Which Caused Leaks to Develop.Caused by Nearly Closed post-filter Inlet Valve.Repaired 2 Leaks in Line CY-98-068, Follow-up to Verbal Notification on 980413 of Film on Discharge Canal.Investigation Continuing.Samples Collected for Petroleum Analyses & Biological Characterization at Intake Structure & Discharge Canal.Replaced Sorbent Booms1998-04-15015 April 1998 Follow-up to Verbal Notification on 980413 of Film on Discharge Canal.Investigation Continuing.Samples Collected for Petroleum Analyses & Biological Characterization at Intake Structure & Discharge Canal.Replaced Sorbent Booms CY-98-045, Ro:On 980212,0219,0225 & 0312,separate Sheens of Approx One Cup of oil-like Substance Was Observed at Discharge Canal. Cause Has Not Been Clearly Identified.Called in Vendor Spill to Install Sorbent Booms to Absorb Sheen.W/One Drawing1998-04-13013 April 1998 Ro:On 980212,0219,0225 & 0312,separate Sheens of Approx One Cup of oil-like Substance Was Observed at Discharge Canal. Cause Has Not Been Clearly Identified.Called in Vendor Spill to Install Sorbent Booms to Absorb Sheen.W/One Drawing CY-98-046, Follow-up to 980311 Verbal Notification of Film on Discharge Canal.Cause Not Yet Determined.Film Is Contained & Will Be Absorbed by Containment & Sorbent Booms That Were in Place in Discharge Canal1998-03-12012 March 1998 Follow-up to 980311 Verbal Notification of Film on Discharge Canal.Cause Not Yet Determined.Film Is Contained & Will Be Absorbed by Containment & Sorbent Booms That Were in Place in Discharge Canal CY-97-082, Special Rept:On 970708,routine Surveillance Testing of Seismic Monitoring Sys Instrumentation Revealed,Data Was Not Being Reproduced by Portion of Playback Sys.Station Presently Pursuing Replacement of Seismic Monitoring Sys1997-08-14014 August 1997 Special Rept:On 970708,routine Surveillance Testing of Seismic Monitoring Sys Instrumentation Revealed,Data Was Not Being Reproduced by Portion of Playback Sys.Station Presently Pursuing Replacement of Seismic Monitoring Sys B16268, Special Rept:On 970205,declared Main Stack-Wide Range Noble Gas Monitor Inoperable.Caused by Inadequate Calibr Methods. Will Revise Calibr Procedure to Technique to Demonstrate Accuracy & Linearity Over Intended Range of Monitor1997-02-19019 February 1997 Special Rept:On 970205,declared Main Stack-Wide Range Noble Gas Monitor Inoperable.Caused by Inadequate Calibr Methods. Will Revise Calibr Procedure to Technique to Demonstrate Accuracy & Linearity Over Intended Range of Monitor B15833, Ro:On 960904,loss of Reactor Coolant Sys Inventory Occurred. Caused by Leakage Past RH-V-23A.Issued Stop Work Order & Developed Plan to Review All Outage Work Orders Against Shutdown Risk Mgt Program Key Safety Functions1996-09-0505 September 1996 Ro:On 960904,loss of Reactor Coolant Sys Inventory Occurred. Caused by Leakage Past RH-V-23A.Issued Stop Work Order & Developed Plan to Review All Outage Work Orders Against Shutdown Risk Mgt Program Key Safety Functions ML20058G2431993-12-0202 December 1993 Special Rept:On 931116,routine Surveillance Testing of Wide Range Noble Gas Stack Monitor RMS-14B Completed.Caused by Damaged Calibr Source.New Calibr Source Being Procured & Low Range Channel Detector Will Be Recalibrated to New Source ML20058Q1101990-08-10010 August 1990 Special Rept:On 900727,accident Monitoring Instrumentation Found Inoperable for Core Exit Thermocouple.Troubleshooting Initiated.Util Working W/Vendor to Procure Fully Qualified Replacement Cable ML20248A5741989-09-26026 September 1989 Special Rept:On 890917,quarterly Beta Dose Limit of 10 Mrad for Noble Gases Exceeded.Caused by Degasification of Reactor Coolant Coincident W/Higher than Normal Radioactive Gas Concentration.Degasification Process Completed ML20244A6601989-04-0606 April 1989 Special Rept:On 890309,diesel Fire Pump Declared Inoperable as Result of Failure to Automatically Shut.Caused by Failure of Solenoid Valve Controlling Inlet Flow to Hydraulic Governor Device.Redundant Fire Water Supply Provided ML20153D4911988-05-0202 May 1988 Ro:On 871219 & 880314,spills of Lubricating Oil Occurred. Caused by Equipment Failure in Travelling Water Screen in Cooling Water Intake Structure & Faulty Fitting on Auxiliary Feed Pump.Screen & Fitting on Pump Repaired ML20147C5751988-01-12012 January 1988 Ro:On 871219,1 Quart of Lubricating Oil Leaked from Travelling Water Screen in Cooling Water Intake Structure & Entered Connecticut River.Caused by Equipment Failure.Cause of Spill Corrected ML20141C9551986-03-0101 March 1986 Special Rept:During Fourth Quarter 1985,river Water Sample Determined to Exceed Control Station by Factor of Ten. Caused by Increased Amount of Primary Water Processed.No Corrective Actions Required Due to Insignificant Levels ML20126F1211975-04-0101 April 1975 RO 50-213/75-1:on 750326,packing Gland Leak Rate Exceeded Tech Specs & Valve Steam Leak Offline Pressurized Enough to Lift Sys Valve,Relieving Pressure to Containment Sump.Caused by Inner Set of Packing Failure on Letdown Isolation Valve 1999-03-23
[Table view] Category:TEXT-SAFETY REPORT
MONTHYEARML20217K3301999-10-19019 October 1999 Safety Evaluation Supporting Amend 195 to License DPR-61 ML20206C8761999-04-28028 April 1999 Safety Evaluation Supporting Amend 194 to License DPR-61 CY-99-047, Ro:On 981217,identified Unsuccessful Dewatering of Cnsi HIC, Model PL8-120R,containing Resins.Caused by Apparent Failure of Dewatering Tree.Other HICs Have Been Procured,Recertified & Returned to Plant for Use1999-03-23023 March 1999 Ro:On 981217,identified Unsuccessful Dewatering of Cnsi HIC, Model PL8-120R,containing Resins.Caused by Apparent Failure of Dewatering Tree.Other HICs Have Been Procured,Recertified & Returned to Plant for Use ML20206F1971998-12-31031 December 1998 Annual Rept for 1998 for Cyap. with CY-99-027, Annual Rept for 10CFR50.59, for Jan-Dec 1998.With1998-12-31031 December 1998 Annual Rept for 10CFR50.59, for Jan-Dec 1998.With ML20198G9101998-12-22022 December 1998 Proposed Rev 2 of Cyap QAP for Haddam Neck Plant. Marked Up Rev 1 Included ML20238F2131998-08-28028 August 1998 SER Accepting Defueled Emergency Plan for Emergency Planning for Connecticut Yankee Atomic Power Co CY-98-136, Ro:On 980727,flow Blockage Occurred & Caused Pressure in Sys to Increase,Resulting in Relief Valve Lifting & Pipe Vibration,Which Caused Leaks to Develop.Caused by Nearly Closed post-filter Inlet Valve.Repaired 2 Leaks in Line1998-08-12012 August 1998 Ro:On 980727,flow Blockage Occurred & Caused Pressure in Sys to Increase,Resulting in Relief Valve Lifting & Pipe Vibration,Which Caused Leaks to Develop.Caused by Nearly Closed post-filter Inlet Valve.Repaired 2 Leaks in Line ML20237B7461998-07-22022 July 1998 1998 Defueled Emergency Plan Exercise Scenario Manual, Conducted on 980722 ML20202D1621998-06-30030 June 1998 Safety Evaluation Supporting Amend 193 to License DPR-61 CY-98-068, Follow-up to Verbal Notification on 980413 of Film on Discharge Canal.Investigation Continuing.Samples Collected for Petroleum Analyses & Biological Characterization at Intake Structure & Discharge Canal.Replaced Sorbent Booms1998-04-15015 April 1998 Follow-up to Verbal Notification on 980413 of Film on Discharge Canal.Investigation Continuing.Samples Collected for Petroleum Analyses & Biological Characterization at Intake Structure & Discharge Canal.Replaced Sorbent Booms CY-98-045, Ro:On 980212,0219,0225 & 0312,separate Sheens of Approx One Cup of oil-like Substance Was Observed at Discharge Canal. Cause Has Not Been Clearly Identified.Called in Vendor Spill to Install Sorbent Booms to Absorb Sheen.W/One Drawing1998-04-13013 April 1998 Ro:On 980212,0219,0225 & 0312,separate Sheens of Approx One Cup of oil-like Substance Was Observed at Discharge Canal. Cause Has Not Been Clearly Identified.Called in Vendor Spill to Install Sorbent Booms to Absorb Sheen.W/One Drawing ML20217F0611998-03-31031 March 1998 Historical Review Team Rept ML20217A0001998-03-31031 March 1998 Monthly Operating Rept for Mar 1998 for Haddam Neck Plant ML20217K2101998-03-27027 March 1998 Safety Evaluation Supporting Amend 192 to License DPR-61 CY-98-046, Follow-up to 980311 Verbal Notification of Film on Discharge Canal.Cause Not Yet Determined.Film Is Contained & Will Be Absorbed by Containment & Sorbent Booms That Were in Place in Discharge Canal1998-03-12012 March 1998 Follow-up to 980311 Verbal Notification of Film on Discharge Canal.Cause Not Yet Determined.Film Is Contained & Will Be Absorbed by Containment & Sorbent Booms That Were in Place in Discharge Canal ML20216D6531998-02-28028 February 1998 Monthly Operating Rept for Feb 1998 for Haddam Neck Plant ML20217D7381998-02-28028 February 1998 Revised MOR for Feb 1998 Haddam Neck Plant CY-98-012, Monthly Operating Rept for Jan 1998 for Connecticut Yankee Haddam Neck Plant1998-01-31031 January 1998 Monthly Operating Rept for Jan 1998 for Connecticut Yankee Haddam Neck Plant CY-98-010, Annual Rept for 10CFR50.59,Jan-Dec,19971997-12-31031 December 1997 Annual Rept for 10CFR50.59,Jan-Dec,1997 ML20198N6681997-12-31031 December 1997 Monthly Operating Rept for Dec 1997 for Haddam Neck Plant ML20217P4861997-12-31031 December 1997 1997 Annual Financial Rept, for Cyap ML20199L5891997-12-24024 December 1997 Independent Analysis & Evaluation of AM-241 & Transuranics & Subsequent Dose to Two Male Workers at Connecticut Yankee Atomic Power Plant ML20203K4271997-11-30030 November 1997 Monthly Operating Rept for Nov 1997 for Haddam Neck Plant ML20199B1141997-10-31031 October 1997 Monthly Operating Rept for Oct 1997 for Haddam Neck Plant ML20198M8101997-10-14014 October 1997 SER Accepting Proposed Revs to Util Quality Assurance Program at Facility ML20198J8811997-09-30030 September 1997 Monthly Operating Rept for Sept 1997 for Haddam Neck Plant ML20210P8721997-08-31031 August 1997 Post Decommissioning Activities Rept, for Aug 1997 ML20217Q3171997-08-31031 August 1997 Addl Changes to Proposed Rev 1 to QA Program ML20210U9301997-08-31031 August 1997 Monthly Operating Rept for Aug 1997 for Haddam Neck Plant CY-97-082, Special Rept:On 970708,routine Surveillance Testing of Seismic Monitoring Sys Instrumentation Revealed,Data Was Not Being Reproduced by Portion of Playback Sys.Station Presently Pursuing Replacement of Seismic Monitoring Sys1997-08-14014 August 1997 Special Rept:On 970708,routine Surveillance Testing of Seismic Monitoring Sys Instrumentation Revealed,Data Was Not Being Reproduced by Portion of Playback Sys.Station Presently Pursuing Replacement of Seismic Monitoring Sys ML20210L0521997-07-31031 July 1997 Monthly Operating Rept for July 1997 for HNP ML20149E4451997-06-30030 June 1997 Monthly Operating Rept for June 1997 for Haddam Neck Plant ML20141A0041997-05-31031 May 1997 Independent Assessment of Radiological Controls Program at Cyap Haddam Neck Plant Final Rept May 1997 ML20140H5241997-05-31031 May 1997 Monthly Operating Rept for May 1997 for Haddam Neck Plant ML20141K4201997-05-22022 May 1997 Safety Evaluation Supporting Amend 191 to License DPR-61 ML20141D4141997-04-30030 April 1997 Monthly Operating Rept for Apr 1997 for Connecticut Yankee Haddam Neck ML20138G5901997-04-25025 April 1997 Proposed Rev 1 to Cyap QA Program for Haddam Neck Plant ML20137W8051997-03-31031 March 1997 Monthly Operating Rept for Mar 1997 for Haddam Neck Plant ML20137H3031997-03-31031 March 1997 Rev 2 to Nuclear Training Loit/Lout Audit Reviews ML20137C6281997-03-14014 March 1997 Redacted Version of Rev 1 to Nuclear Training Loit/Lout Audit Reviews ML20137A0801997-02-28028 February 1997 Monthly Operating Rept for Feb 1997 for Haddam Neck Plant ML20135C5101997-02-26026 February 1997 1996 Refuel Outage ISI Summary Rept for CT Yankee Atomic Power Co B16268, Special Rept:On 970205,declared Main Stack-Wide Range Noble Gas Monitor Inoperable.Caused by Inadequate Calibr Methods. Will Revise Calibr Procedure to Technique to Demonstrate Accuracy & Linearity Over Intended Range of Monitor1997-02-19019 February 1997 Special Rept:On 970205,declared Main Stack-Wide Range Noble Gas Monitor Inoperable.Caused by Inadequate Calibr Methods. Will Revise Calibr Procedure to Technique to Demonstrate Accuracy & Linearity Over Intended Range of Monitor ML20135E3221997-02-13013 February 1997 Independent Review Team Rept 1996 MP -1 Lout NRC Exam Failures ML20134L2751997-02-0303 February 1997 Draft Rev to GPRI-30, Spent Fuel Storage Facility Licensing Basis/Design Basis ML20138K5721997-01-31031 January 1997 Monthly Operating Rept for Jan 1997 for Haddam Neck Plant.W/ ML20134L2791997-01-10010 January 1997 Rev 0 to QA Program Grpi ML20134L2911997-01-0808 January 1997 Rev 0 to UFSAR Rev Grpi ML20134L2721996-12-31031 December 1996 Commitment Mgt Grpi 1999-04-28
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CONNECTICUT YANKEE ATOMIC POWER COMPANY HADDAM NECK PLANT 362 INJUN HOLLOW ROAD EAST HAMPTON, CT 06424-3099 August 12,1998 Docket No. 50-213 CY-98-136 U. S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, DC 20555 Haddam Neck Plant Reactor Coolant System Decontamination The purpose of this letter is to update the NRC on the results of the investigation Connecticut Yankee Atomic Power Company (CYAPCO) conducted into the July 27,1998, event at the Haddam Neck Plant, and communicate CYAPCO's basis for continuing with the reactor coolant system (RCS) decontamination (decon). This new information supplements the information provided at the management meeting held with the NRC on August 3,1998.
Background
During the past year CYAPCO, has been diligently performing work activities necessary to support a safe and successful RCS decon. The goal of the RCS decon project is to remove a film of radioactive material which has accumulated on the inside of the RCS piping over the past 30 years. The removal of this materialis accomplished over several decontamination cycles and is beneficial to CYAPCO l y because it will significantly reduce the radiation levels encountered by plant workers during the subsequent decommissioning activities. The first cycle resulted in an approximate 60% reduction in decontaminated system radiation levels.
On July 27,1998, during the first cycle of a multi-cycle evolution, CYAPCO was in the process of aligning the ion exchangers to the primary system. The ion [g/J,L
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exchangers are used to remove the radioactivity from the system during the RCS decon. During this time, a flow blockage occurred and caused pressure in the system to increase, resulting in a relief valve lifting and pipe vibration, which caused leaks to develop in two separate small diameter lines in the system. CYAPCO was able to quickly respond to the event, using contingency procedures provided for this type of situation. The total water volume that leaked to the aerated drain tank was estimated to be 1200-1500 gallores. All leakage was contained, no personnel injury or internal or skin exposure occurred, and there was no release of radioactive water to the environment. l 9808200064 980812 PDR ADOCK 0500o213 S PDR
U. S. Nuclear Regulatory Commission CY-98-136/Page 2 I
, A Discussion immediately after the event occurred, and the plant had been placed in a stable condition, CYAPCO formed a dedicated event review team (ERT). The ERT was comprised of individuals whu were not involved in the RCS decon and represented the Oversight, Operations, Engineering and Corrective Action Departments. This team conducted interviews, reviewed operations logs, reviewed test results and developed hypotheses, in an attempt to determine the root cause. The ERT has concluded that there are two root causes. First, personnel managing the RCS decon demonstrated poorjudgment in making three attempts to valve in a demineralized without changing system configuration. Second, reliance on operator action to control pressure within design basis parameters was inadequate.
CYAPCO has made a significant effort to locate the blockage, including a review of plant log sheets, computer modeling of the effected components, inspection of suspect components and flow testing of the various flow paths in the system.
Review of this data supports the cause of the blockage as the letdown post-filter inlet valve LD-V-238 being in the fully closed or near to fully closed position. The extensive investigation and the related corrective actions ensure that there is no other blockage in the system and that CYAPCO will not be in a position where personnel inappropriately feel the need to act quickly to place a demineralized in service.
On August 3,1998, CYAPCO and the NRC held a meeting at the Haddam Neck Plant during which time CYAPCO presented information on the RCS decon process, the probable cause and contributing causes of the event, along with corrective actions that were taken or were planned. Since that time, the ERT has completed its investigation, has recommended certain additional corrective actions, and CYAPCO has completed a comprehensive evaluation and actions over and above what were discussed on August 3,1998. The additional corrective actions are discussed below.
Additional Corrective Actions Taken CYAPCO has conducted structuralintegrity and material condition inspections of the RCS decon piping. The two leaks in the letdown purification line have been repaired. l The inspections revealed the following:
i e No damaged or failed pipe supports; ;
. No indications of excessive pipe movements; l
. No deformation of piping; e No signs of structural or material degradation to cantilevered vents or drains; and
. Validation of the overall material condition of piping and supports.
U. S. Nuclear Regulatory Commission CY-98-136/Page 3 l
The E8T also identified that Operations personnel were required to perform many valve manipulations using reach-rods. The use of reach-rods does not let the operators visually verify valve position or definitively know what type of valve they are manipulating. Therefore, CYAPCO has developed a list of reach-rod operated valves used in the RCS decon. The list identifies the valve type and number of turns i needed to fully open or close each valve. This list provides guidance to Operations personnel to ensure that when they manipulate a valve it is placed in the correct position. In addition, on-shift field observations by independent engineering personnel are being conducted on key valve operations. To further assist the I operators, new guidance has been supplied regarding expected parameters when aligning to the demineralizers.
CYAPCO has also reviewed the assumed failures contained in the RCS decon safety evaluation to determine if any additional failures need to be considered. As noted in the August 3,1998, meeting, CYAPCO concluded that a booster pump trip circuit should be installed so that in the event the system were to pressurize to an unacceptable level, the pump would automatically trip and prevent the lifting of the relief valve. This would provide a faster response to any pressure transient and I would provide added assurance that the system would not be subjected to an over-pressure transient. CYAPCO's review concluded that any leakage within the associated buildings was bounded by the safety evaluation assumption of a 1600 gallon leak occurring outside.
CYAPCO has performed additional flow testing at flows and pressures consistent with those expected during the RCS decon. This testing did not identify any flow blockage or unexpected pressure increases in the RCS decon lines. No leakage was identified. Flow testing did find that the letdown flow indicator, Fl-113 was out of calibration caused by the vibration during the July 27,1998 event. The indicator was recalibrates, in addition, the system was flow modeled on a computer to reproduce the pressure transient. The only possible way to reproduce the transient was to introduce a total flow blockage of the letdown line. Flow modeling was also used to accurately predict the pressures and pressure drops seen during flow testing and verified that there are no blockages in the system as configured.
CYAPCO has also improved the communication protocol between personnel in the field and in the control room. During the event, information was not effectively communicated between the personnel directing the event who were in contact with personnel in the plant via head sets and the personnel in the control room maintaining the remaining plant in a safe condition and communicating with personnel in the plant by telephone. Information that was relayed by telephone was not effectively communicated to the personnel directing the event. Communication that comes in by telephone will be relayed in an immediate fashion to the Shift
U. S. Nucbar Regulatory Commission CY-98-136/Page 4 Flanager or his designee, as appropriate. Control Room personnelinvolved in the RCS decon will be notified by the Shift Manager of pertinent communication.
CYAPCO has installed additional cameras to monitor critical areas in the pipe trenches. Also, additional pressure and flow instrumentation has been added to monitor for pressure transients.
Conclusion The cause of the flow blockage that occurred on July 27,1998, was the closed or nearly closed post-filter inlet valve. CYAPCO has instituted numerous corrective actions that will prevent or mitigate the effects of pressure transients, along with other actions that will provide assurance of valve positions. Also, additional on-shift personnel have been stationed to verify valve positioning.
Based on the extensive corrective action implemented, CYAPCO is confident that the RCS decon can proceed in a safe manner. With the corrective actions discussed at the August 3,1998 meeting, and in further discussions with the NRC Staff on August 6 and 9,1998 on the corrective actions discussed above, CYAPCO has commenced with Cycle 2 of the RCS decon.
Should you have any questions on the above, or desire additional information, please contact Mr. G. P van Noordennen at (860) 267-3938.
4 Very truly yours, CONNECTICUT YANKEE ATOMIC POWER COMPANY
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R. A. Mellor k-
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Vice President - Operations and Decommissiori ing l
cc: H. J. Miller, Region I Administrator T. L. Fredrichs, Project Manager, Haddarn Neck Plant W. J. Raymond, Senior Resident Inspector, Haddam Neck Plant Director, CT DEP Monitoring and Radiation Division 1
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