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Category:ABNORMAL OCCURRENCE REPORTS (SEE ALSO LER & RO)
MONTHYEARML20058K6971975-05-0101 May 1975 Notifies That Surveillance Test for Exercising Unit 2 Containment Vacuum Breaker Isolation Valve Showed to Be Inoperable & Would Not Close.Maint Work Initiated & Valve Was Returned to Operable Status ML20058K7981975-01-29029 January 1975 AO 75-3:on 750128,both Unit 2 Safety Injection Pumps Incapable of Starting on Automatic SI Signal from Approx 0900 to 100 H ML20127K8731973-10-0808 October 1973 Ao:On 730929,SGBT Sys B Low Heat Alarm Received & Low Differential Pressure Observed.Caused by Failure of 30 Amp 600 Volt Fuse Block Assembly in Heater Circuit.Fuse Block Assembly Replaced & Operability Test Performed ML20127K8761973-10-0505 October 1973 Ao:On 730926,discovered That Low Pressure Cooling Svc Water Sys for Diesel Generators 11 & 12 Not Demonstrated Operable on 730924 & 25,respectively.Caused by Personnel Error.Dg Starting Sys Maint Procedure to Be Revised ML20127K8801973-09-25025 September 1973 Ao:On 730917,sodium Pentaborate Solution Found in Standby Liquid Control Pump 12 Lubricating Oil.Caused by Closed Stuffing Box Drain,Resulting in Leakage Into Crankcase. Crankcase Drained,Flushed & Refilled W/Oil ML20024G2971970-09-29029 September 1970 Ao:On 700920,standby Power Source Failed to Close to Energize Bus,During Test of Emergency Power Source When Power Source 4.16 Kv.Caused by Undervoltage Relay Failing to Drop Out ML20056B7511970-09-29029 September 1970 Ao:On 700921,localized Fire in Portion of SGTS Train a Charcoal Filter Bank Rendered Unit Inoperable.Caused by Overheating One of Four Strip Heaters.Corrective Actions: Place Temp Switch on Filter ML20056B7281970-09-18018 September 1970 Ao:On 700908,failure in Current Limiting Circuitry for Air Heater in SGTS Filter Train a Rendered Unit Inoperable.On 700910,SGTS Filter Train B Failed to Provide Flow Rate Sufficient to Maintain .25 Inch of Water Vacuum 1975-05-01
[Table view] Category:TEXT-SAFETY REPORT
MONTHYEARML20217D1261999-09-30030 September 1999 Monthly Operating Rept for Sept 1999 for Monticello Nuclear Generating Plant.With ML20216E7031999-08-31031 August 1999 Monthly Operating Rept for Aug 1999 for Monticello Nuclear Generating Plant.With ML20210Q0521999-08-0404 August 1999 Safety Evaluation Approving Relief Request 10 to License DPR-22 Per 10CFR50.55a(g)(6)(i).Inservice Exam for Relief Request 10,Parts A,B,C,D & E Impractical & Reasonable Assurance of Structural Integrity Provided ML20210Q6611999-07-31031 July 1999 Monthly Operating Rept for July 1999 for Monticello Nuclear Generating Plant.With ML20209F7901999-06-30030 June 1999 Monthly Operating Rept for June 1999 for Monticello Nuclear Generating Plant.With ML20195H0351999-05-31031 May 1999 Monthly Operating Rept for May 1999 for Monticello Nuclear Generatintg Plant.With ML20206N1721999-04-30030 April 1999 Monthly Operating Rept for Apr 1999 for Monticello Nuclear Generating Plant.With ML20205N0861999-04-12012 April 1999 Safety Evaluation Re Licensee Response to GL 95-07, Pressure Locking & Thermal Binding of Safety-Related Power-Operated Gate Valves ML20205P5701999-03-31031 March 1999 Monthly Operating Rept for Mar 1999 for Monticello Nuclear Generating Plant.With ML20204H4951999-03-18018 March 1999 SER Concluding That Licensee Established Acceptable Program to Verify Periodically design-basis Capability of safety-related MOVs at Monticello.Therefore Staff Concludes Licensee Adequately Addressed Action Required in GL 96-05 ML20205G7391999-02-28028 February 1999 Monthly Operating Rept for Feb 1999 for Monticello Nuclear Generating Plant.With ML20202F7901999-01-25025 January 1999 1999 Four Year Simulator Certification Rept for MNGP Simulation Facility ML20199E4871999-01-0606 January 1999 SER Accepting Licensee 951116,960214 & 0524 Responses to NRC Bulletin 95-002, Unexpected Clogging of Residual Heat Removal Pump Strainer While Operating in Suppression Pool Cooling Mode ML20199F6211998-12-31031 December 1998 Monthly Operating Rept for Dec 1998 for Mngp.With ML20205H0561998-12-31031 December 1998 Northern States Power Co 1998 Annual Rept. with ML20198P0691998-12-28028 December 1998 Safety Evaluation Concluding That NSP Proposed Alternative to Paragraph III-3411 of App III to 1986 Edition of Section XI of ASME Code Provides Acceptable Level of Quality & Safety.Alternative Authorized ML20198D0751998-12-10010 December 1998 Safety Evaluation Supporting NSP Proposed Change to EOPs to Use 2/3 Core Height as Potential Entry Condition Into Containment Flooding ML20198B2531998-11-30030 November 1998 Monthly Operating Rept for Nov 1998 for Monticello Nuclear Generating Plant.With ML20195E3691998-11-12012 November 1998 Safety Evaluation Concluding That Licensee USI A-46 Implementation Has Met Purpose & Intent of Criteria in GIP-2 & Staff Sser 2 for Resolution of USI A-46 ML20195D2381998-10-31031 October 1998 Monthly Operating Rept for Oct 1998 for Monticello Nuclear Generating Plant.With ML20198J4451998-10-22022 October 1998 Rev 2 to SIR-97-003, Review of Test Results of Two Surveillance Capsules & Recommendations for Matls Properties & Pressure-Temp Curves to Be Used for Monticello Rpv ML20154L3471998-09-30030 September 1998 Monthly Operating Rept for Sept 1998 for Monticello Nuclear Generating Plant.With ML20153F0511998-09-21021 September 1998 Rev 2 to MNGP Colr,Cycle 19 ML20153E9361998-09-0808 September 1998 Rev 1 to MNGP Colr,Cycle 19 ML20153B0861998-08-31031 August 1998 Monthly Operating Rept for Aug 1998 for Monticello Nuclear Generating Plant.With ML20237B8461998-07-31031 July 1998 Monthly Operating Rept for July 1998 for Monticello Nuclear Generating Plant ML20236W5041998-07-21021 July 1998 ISI Exam Summary Rept - Refueling Outage 19 ML20236R1941998-06-30030 June 1998 Monthly Operating Rept for June 1998 for Monticello Nuclear Generating Plant ML20249A5861998-05-31031 May 1998 Monthly Operating Rept for May 1998 for Monticello Nuclear Generating Plant ML20247K3971998-04-30030 April 1998 Monthly Operating Rept for Apr 1998 for Monticello Nuclear Generating Plant ML20217D8731998-04-13013 April 1998 Rev 0 to MNGP Colr,Cycle 19 ML20217F6431998-03-31031 March 1998 Monthly Operating Rept for Mar 1998 for Monticello Nuclear Generating Plant ML20216D1041998-03-0505 March 1998 Rev 21 to Operational QA Plan ML20216H6481998-02-28028 February 1998 Monthly Operating Rept for Feb 1998 for Monticello Nuclear Generating Plant ML20203G1431998-02-10010 February 1998 Rev 2 to Inservice Insp Exam Plan,Third Interval,920601- 020531 ML20203B2821998-01-31031 January 1998 Monthly Operating Rept for Jan 1998 for Monticello Nuclear Generating Station ML20202F9161998-01-29029 January 1998 Special Rept:On 980128,two of Three Fire Protection Pumps Were Removed from Svc as Result of Sys Configuration Necessary to Support Planned Maintenance.Fire Pumps Were Returned to Svc on 980128 ML20216D2071997-12-31031 December 1997 1997 Annual Rept for Northern States Power Co ML20197J8131997-12-31031 December 1997 Revised Evacuation Time Estimates for Plume Exposure Pathway Emergency Planning Zone at Monticello Nuclear Power Plant. W/One Oversize Drawing ML20198P2201997-12-31031 December 1997 Monthly Operating Rept for Dec 1997 for Monticello Nuclear Generating Plant ML20203J7131997-11-30030 November 1997 Monthly Operating Rept for Nov 1997 for Monticello Nuclear Generating Plant ML20199G7051997-11-19019 November 1997 Safety Evaluation Authorizing Relief Request 8 of Third 10 Yr Inservice Insp Interval ML20199H8181997-10-31031 October 1997 Monthly Operating Rept for Oct 1997 for Monticello Nuclear Generating Plant ML20217K2081997-09-30030 September 1997 Monthly Operating Rept for Sept 1997 for Monticello Nuclear Generating Plant ML20216H7771997-08-31031 August 1997 Monthly Operating Rept for Aug 1997 for Monticello Nuclear Generating Plant ML20217K2741997-07-31031 July 1997 Monthly Operating Rept for Jul 1997 for Monticello Nuclear Generating Plant ML20196H1081997-07-0808 July 1997 Rev 20 to Operational QA Plan ML20141B9271997-06-30030 June 1997 LOCA Containment Analyses for Use in Evaluation of NPSH for RHR & Core Spray Pumps ML20149E2921997-06-30030 June 1997 Monthly Operating Rept for June 1997 for MNGP ML20148S6341997-06-23023 June 1997 NPSH - Rept of Sulzer Bingham Pump 1999-09-30
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I NORTHERN STATES POWER COMPANY Minneapolis, Minnesota 55401 gY< s1 Q s f DOCKETED September 29, 1970 USAEC (3 _
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Dr. Peter A. Morris, Director /g [4B h.; . ;' p j Division of Feactor Licensing '
W,g United States Atomic Energy domission
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Washington, D.C. 20545 ,
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Dear Dr. Morris:
I MONTICELLO NUCLEAR GENEFATING PLANT 1 Docket No. 50-263 License No. DPR-22 Reporting of Abnormal Occurrences A condition has occurred at the Monticello Nuclear Generating Plant which requires reporting to your office in accordance with provisions of A ppendix A, Technical Specifications, of the Provisional Operating License DPR-22. The {
condition was cir.ssified as an Abnormal Occurrence as defined in Section 1. A.4.
of the Technical Specifications and requires reporting in accordance with Section 6.6.B.3 of the Speci fications. The Region lil Compliance Office has been {
notified in accordance with the requirements of Section 6.6. A of the Technical l Speci fi cati ons.
The occurrence involved a failure in the Standby Gas Treatment System which resulted in the burning of a portion of the charcoal filter in the A circuit of the system. The cause of the problem has been determined and the necessary repairs have been completed. T he details of tFe occurrence are described l in detail in the attached Abnormal Occurrence Report No. 4.
Yours ver truly, hPGA R.O. Duncanson, Jr., P. .
Gen. Supt. of Power Plants-Mechanical Chairman - Monticello Safety Audit Committee ROD / car 9102000495 700929 317va/
CF ADOCK 05000263 CF .
, September 259 1970 MONTICELLO NUCLEAR GENERATING PLANT Abnormal Occurrence Repori No. 4 1
- 1. Sumarv Descriotion of Occurren~
At approximately 1440 hours0.0167 days <br />0.4 hours <br />0.00238 weeks <br />5.4792e-4 months <br />, September 21, 1970, an abnormal occurrence, consisting of a localized fire in a portion of the Standby Gas Treatment Sy stem train A charcoal filter bank, rendered the unit inoperable. An investigation of the occurrence was begun immediately and was concluded on September 22, 1970. !
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- 2. Detailed Descriotion of the Occurrence
- a. Summarv of Condi tions ;
At the time of the occurrence there were 406 fuel elements in the core and conditions were in accordance with Technical Specification 3.7 C such that Secondary Containment integrity was not required. ]
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- b. Account and Ara!vsis of the Occurrenca l
.At approximately 1440 hours0.0167 days <br />0.4 hours <br />0.00238 weeks <br />5.4792e-4 months <br />, September 21, 1970, Standby 3as {
Treatnent System train A was started for the purpose of taking air '
temperature data at the inlet of the air heater and at the inlet of the charcoal filter bank. When the unii was siaried, sparks were' noticed goirig past an inspection port downstream of the charcoal fil ter bank. The unit was immediately shutdown from the control room j and power to SGTS train A was interrupted from a local power panel. l 1 Immediate investigation revealed that three of the charcoal filter '
4 j
uryits had ignited (there are twelve charcoal filter units per filter )
bank). A CO 2 fi re xtinguisher was obtained and C0 w s inje ted upstream' ar.d downstream of the filter bank. 2
' Approximately one hour later the three filter units were removed from the filter bank and i cooled wi th water.
Investigation revealed that the fire was caused by overheating i
one of the four strip heaters (Chr omalox Type SE-48) of which the i
charcoal blanket heater is comprised. The four strip heaters are wired in a series / parallel arrangenent (see the basic elenentary
, . diagram attached). An electrical short across one of the strip heaters
' resulted in a higher voltage drop across the second strip heater which was wired in series with the shorted heater ce.using it to overheat.
The short was cauced by deierioration of the plastic tape applied to the strip heater 1 cads.
! c. Resu14 s of the Occur renca Section 4.7.B.1.b.(2) of the Technical Sp ecification reg; ires the removal efficiency of the charcoal filters to be og;al to or greater than 99 percent. As a result of the fire three of the charcoal filter units needed replacement and train A was c,onsidered inoperable.
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- 3. Corrective Actions ; j i On September 21, 1970, all of the SGTS train B strip heater leads were )
- inspected and where the possibility of a short existed, the leads were j l taped with asbestos tape. B train heater resistances were measured before and after the leads were inspected and no shorts were found to ,
j exist. !
1
- On September 24, 1970, six of the twelve tra;n A charcoal filter units )
were replaced. The filter bank is comprised of two stacks of six filter l units each. The six new filter units replaced the three units which burned 4
and the three remainin i which had overheatedsee (g uniis attached in thefilter stack and adjacent to the stripThe heater diagram). heater lead
. wires to the overheated strip heater were replaced and the strip heater leads were inspected and taped with asbestos tape where possibility of i a short existed. Four temperature switches, each sensing the surface temperature of one of the four train A strip heaters, were installed and will interrupt a control signal to the gewer control unit if any of the strip heater temperatures exceed 400 f. Similar temperature j switches will be installed on train B when received. l On September 25, 1970, Nuclear Containment System (NCS) Incorporated i personnel performed a Freon test on the train A charcoal filter bank and i 1
found the efficiency to be preater than 99.9 percent. NCS also l perforced DOP tests on the $GTS train A HEPA filters at this firm and found their efficiencies to be greater than 99.9 percent.
. Prepared by:
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D. D. Antor'iy Engineer -
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Occurrence , Investigator l
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