|
---|
Category:REPORTABLE OCCURRENCE REPORT (SEE ALSO AO LER)
MONTHYEARML20205A6551999-03-19019 March 1999 Ro:On 990310,main Ventilation Damper Failed to Close on Receipt of High Radiation Test Signal.Cause Indeterminate. Relays Associated with Main Exhaust Damper/Fans & Main Intake Damper Were Replaced ML20206P5321999-01-0606 January 1999 Ro:On 981229,only One Nuclear Safety Period Scram Channel Was Operable,For Period of Five Minutes.Caused by Placement of Nuclear Safety Sys Channel 1 Input Signal Cable on Wrong Bnc Connector.Placed Channel on Correct Bns Connector ML20217E8071998-03-23023 March 1998 Ro:On 980127,containment Integrity No Longer Existed & Key Switch Was Still 'On' for One of Test & Calibr Procedures. Caused by Retrieving Tool Box from Truck Air Lock.Discussed Occurrence W/Personnel & Will Consider TS Rev Re Key Switch ML20092K8281995-09-22022 September 1995 Corrective Action for RO 50-20/1995-4,re Abnormal Situations Which Occurred on 950711 ML20091K3091995-08-18018 August 1995 Ro:On 950809,malfunction of Shim Blade Drive Mechanism Occurred.Determined That Mechanism Experienced Intermittent Slippage When Blade Being Withdrawn.Blade Drive Mechanism Assembly Procedure PM 7.1.1.1 Will Be Reviewed ML20086T7571995-07-28028 July 1995 RO 50-20/1995-4:on 950720,operated W/One Shim Blade Fully Inserted.Caused by Failure of Licensed Operators to Follow Written Procedure for Investigating Mismatch.Failed Proximity Switches Replaced ML20082B8551995-03-30030 March 1995 RO 50-20/1995-2:on 950320,operation of Reactor in natural- Circulation Mode W/O Required Two Operable Nuclear Safety Level Channels Set to Scram at or Less than 100 Kw,Mitr TS 3.7 ML20078S2241995-02-17017 February 1995 Reportable Occurrence 50-020/95-01:on 950206,voltage & Specific Gravity Measurements of Cell of Emergency Battery Bank Recorded at Less than Specified Weekly SR in TS 4.3.5. C/A Will Modify SR to Monthly ML20058Q2371993-12-17017 December 1993 RO 50-20/1993-1:on 931207,operation W/Fewer than Required Number of 100 Kw Nuclear Safety Sys Level Channels Identified.Caused by Faulty four-segment Relay in low-range Amplifier of Channel 5.Amplifier Replaced ML20094K0721992-03-12012 March 1992 RO 50-020/1992-2:on 911030,three Fission Chambers Missing During Annual Inventory of SNM Matl.Search for Missing Chambers Completed on 920311 W/O Locating Chambers.Snm Inventory for 1991 Has Been Amended ML20090D6661992-03-0202 March 1992 RO 50-20/92-1 on:920218,malfunction Occurred in Reactor Analog Controller Due to Improper Performance of Increase in Reactor Power.Caused by Operator Error.Analog Automatic Control Sys Investigated & Temporarily Repaired ML20082K5911991-08-22022 August 1991 RO 50-20/1991-1:on 910813,fission Product Gas Levels Rose from Normal Operating Levels to Max of 15% of Mpc.Caused by Small Blister on One of Element MIT-17 Fuel Plates. Corrective Action Consisted of Removing MIT-17 from Core ML20248C7111989-08-0404 August 1989 RO 50-20/1989-2:on 890726,console Operator Received Abnormal Bldg Alarm.Leak Test Revealed Crack on Sys Ref Line Which Senses Atmospheric Pressure Outside Containment.All Polyethylene Tubing in Sys Replaced ML20246P3071989-03-17017 March 1989 RO 50-20/1989-1:on 890308,operation W/Fewer than Required Number of Nuclear Safety Channel Level Scrams Due to Lack of High Voltage Power Supply (Hvps) to Channel 5.Reactor Shut Down & Hvps Energized to Supply Channel 5 ML20154M6501988-05-26026 May 1988 RO 50-20/1988-1:on 880511,incipient Fuel Clad Defect Detected.Caused by Small Blister on One Element MIT-12 Fuel Plate.Element MIT-12 Removed from Core ML20236S4931987-11-19019 November 1987 RO 50-20/1987-2:on 871110,improper Performance of Reactor Reshim Resulted in Excessive Power Rise.Caused by Operator Error.Operator Suspended from All Licensed Duties Pending Further Review of Circumstances & Disciplinary Measures ML20213G0601986-11-0606 November 1986 RO 50-20/1986-3:on 861027,shim Blade 6 Could Not Operate at full-out Position Due to Mechanical Interference.Caused by Misalignment of Blade Proximity Switch Tube.Switch Tube Reinstalled Properly ML20214V9001986-10-17017 October 1986 Revised RO 50-20/1986-2:on 861008,elevated Levels of Fission Gases Discovered in Primary Containment.Cause Undetermined. Refueling Initiated & Element MIT-19 Removed.All in-core Elements Sipped.No Abnormalities Found ML20214H9541986-10-17017 October 1986 RO 50-020/86-02:on 861008,elevated Levels of Fission Gases in Primary Containment Observed.Cause Unknown.Element MIT-19 Removed from Core & All in-core Elements Sipped ML20154S4591986-02-28028 February 1986 RO 50-20/1986-1:on 860219,fission Product Gas Levels Rose from Normal Operating Levels.Caused by Blister on Surface of Outer Fuel Plate of Element MIT-11.Element MIT-11 Removed from Core ML20137G3661985-07-23023 July 1985 RO 50-20/1985-2:on 850715,defect in Fuel Element Cladding Observed.Caused by High Rate of Outgassing from Fuel Element MIT-32.Defective Element Removed ML20137G3531985-04-18018 April 1985 RO 50-20/1985-1:on 850408,main Intake Valve Failed Light Test Maint Procedure.Caused by Excessive Wear of Valve Gasket.Gasket Replaced ML20081H8191983-09-15015 September 1983 RO 50-20/1983-2:on 830906,fission Product Gas Levels Rise from 2.8% Max Permissible Concentration in Jul 1983 to 4.57% in Aug Noted.Caused by Excessive Outgassing of Fuel Element MIT-08.Element Removed from Core ML20074A7521983-04-29029 April 1983 RO 50-20/1983-1:on 830419,main Intake Valve Closed & Could Not Be Reopened.Caused by Piston Rod Rupture Near Rod Eye, Leaving Valve in Closed Position.Defective Hydraulic Cylinder Shaft Replaced ML20063B9221982-08-17017 August 1982 Ro:On 820809,slight Increase Found in Levels of Fission Products in Reactor Primary Sys.Cause Under Investigation. Criterion for Operation W/Possible Faulty Core Element Per RO 50-20/79-4 Will Be Observed 1999-03-19
[Table view] Category:TEXT-SAFETY REPORT
MONTHYEARML20209C9331999-07-0808 July 1999 Vols 1 & 2 to SAR for Ma Institute of Technology Nuclear Reactor Lab ML20196K0331999-06-30030 June 1999 Quality Mgt Program for Generation of MITR-II Medical Therapy Facility Beams for Human Therapy, Reflecting Change to Provision 14 ML20205A6551999-03-19019 March 1999 Ro:On 990310,main Ventilation Damper Failed to Close on Receipt of High Radiation Test Signal.Cause Indeterminate. Relays Associated with Main Exhaust Damper/Fans & Main Intake Damper Were Replaced ML20206P5321999-01-0606 January 1999 Ro:On 981229,only One Nuclear Safety Period Scram Channel Was Operable,For Period of Five Minutes.Caused by Placement of Nuclear Safety Sys Channel 1 Input Signal Cable on Wrong Bnc Connector.Placed Channel on Correct Bns Connector ML20199H2371998-12-31031 December 1998 Revised SER for Fission Converter Facility ML20196B7541998-06-30030 June 1998 Mit Research Reactor Nuclear Reactor Lab Ma Inst of Technology,Annual Rept to Us NRC for Period 970701-980630. with ML20217E8071998-03-23023 March 1998 Ro:On 980127,containment Integrity No Longer Existed & Key Switch Was Still 'On' for One of Test & Calibr Procedures. Caused by Retrieving Tool Box from Truck Air Lock.Discussed Occurrence W/Personnel & Will Consider TS Rev Re Key Switch ML20217G2181997-10-0303 October 1997 SER for Fission Converter Facility ML20198P8071997-06-30030 June 1997 Annual Operating Rept for Jul 1996 - June 1997 ML20137L5901997-04-0303 April 1997 Safety Evaluation Supporting Amend 30 to License R-37 ML20129B3201996-06-30030 June 1996 Annual Rept to Us NRC for Period 950701-960630 ML20092K8281995-09-22022 September 1995 Corrective Action for RO 50-20/1995-4,re Abnormal Situations Which Occurred on 950711 ML20091K3091995-08-18018 August 1995 Ro:On 950809,malfunction of Shim Blade Drive Mechanism Occurred.Determined That Mechanism Experienced Intermittent Slippage When Blade Being Withdrawn.Blade Drive Mechanism Assembly Procedure PM 7.1.1.1 Will Be Reviewed ML20086T7571995-07-28028 July 1995 RO 50-20/1995-4:on 950720,operated W/One Shim Blade Fully Inserted.Caused by Failure of Licensed Operators to Follow Written Procedure for Investigating Mismatch.Failed Proximity Switches Replaced ML20092K2301995-06-30030 June 1995 Mit Research Reactor Annual Rept to NRC for Period Jul 1994 - June 1995 ML20082B8551995-03-30030 March 1995 RO 50-20/1995-2:on 950320,operation of Reactor in natural- Circulation Mode W/O Required Two Operable Nuclear Safety Level Channels Set to Scram at or Less than 100 Kw,Mitr TS 3.7 ML20078S2241995-02-17017 February 1995 Reportable Occurrence 50-020/95-01:on 950206,voltage & Specific Gravity Measurements of Cell of Emergency Battery Bank Recorded at Less than Specified Weekly SR in TS 4.3.5. C/A Will Modify SR to Monthly ML20072T3041994-06-30030 June 1994 Annual Rept for Mit Research Reactor for 930701-940630 ML20058Q2371993-12-17017 December 1993 RO 50-20/1993-1:on 931207,operation W/Fewer than Required Number of 100 Kw Nuclear Safety Sys Level Channels Identified.Caused by Faulty four-segment Relay in low-range Amplifier of Channel 5.Amplifier Replaced ML20056G8011993-06-30030 June 1993 Mit Research Reactor Nuclear Reactor Lab Mit,Annual Rept to NRC for Period 920701-930630 ML20128P4371993-02-16016 February 1993 Safety Evaluation Supporting Amend 27 to License R-37 ML20073H1451992-12-0909 December 1992 Study of MITR-II Core Tank Aging for Relicensing Consideration ML20114D9261992-06-30030 June 1992 Mit Research Reactor Nuclear Reactor Lab Mit,Annual Rept to NRC for 910701-920630 ML20094K0721992-03-12012 March 1992 RO 50-020/1992-2:on 911030,three Fission Chambers Missing During Annual Inventory of SNM Matl.Search for Missing Chambers Completed on 920311 W/O Locating Chambers.Snm Inventory for 1991 Has Been Amended ML20090D6661992-03-0202 March 1992 RO 50-20/92-1 on:920218,malfunction Occurred in Reactor Analog Controller Due to Improper Performance of Increase in Reactor Power.Caused by Operator Error.Analog Automatic Control Sys Investigated & Temporarily Repaired ML20082K5911991-08-22022 August 1991 RO 50-20/1991-1:on 910813,fission Product Gas Levels Rose from Normal Operating Levels to Max of 15% of Mpc.Caused by Small Blister on One of Element MIT-17 Fuel Plates. Corrective Action Consisted of Removing MIT-17 from Core ML20082L8451991-06-30030 June 1991 Mit Research Reactor Annual Rept to NRC for Jul 1990 to June 1991 ML20058N5741990-08-10010 August 1990 QA Program for MITR-II Spent Fuel Shipment ML20059G4331990-06-30030 June 1990 Mit Research Reactor Annual Rept to NRC for Jul 1989 - June 1990 ML20012D9651990-03-22022 March 1990 RO 50-20/1990-1:on 900312,incorrect Calculation of Estimated Critical Position (ECP) Attained During Reactor Startup. Caused by Failure to Check Second Portion of ECP Calculation Performed by Individual in Training ML20012C2771990-03-0909 March 1990 SER for BWR Coolant Chemistry Loop to Be Installed & Operated in Mitr ML20248C7111989-08-0404 August 1989 RO 50-20/1989-2:on 890726,console Operator Received Abnormal Bldg Alarm.Leak Test Revealed Crack on Sys Ref Line Which Senses Atmospheric Pressure Outside Containment.All Polyethylene Tubing in Sys Replaced ML20247H7041989-06-30030 June 1989 Mit Research Reactor Annual Rept for Jul 1988 - June 1989 ML20246P3071989-03-17017 March 1989 RO 50-20/1989-1:on 890308,operation W/Fewer than Required Number of Nuclear Safety Channel Level Scrams Due to Lack of High Voltage Power Supply (Hvps) to Channel 5.Reactor Shut Down & Hvps Energized to Supply Channel 5 ML20195K1161988-10-24024 October 1988 Suppl to PWR Loop Ser:Use of Large Circulating Pump ML20154J6221988-08-29029 August 1988 Revised Mit Research Reactor Annual Rept to NRC for Jul 1987 - June 1988 ML20153F5591988-06-30030 June 1988 Mit Research Reactor Annual Rept to NRC for Jul 1987 - June 1988 ML20154M6501988-05-26026 May 1988 RO 50-20/1988-1:on 880511,incipient Fuel Clad Defect Detected.Caused by Small Blister on One Element MIT-12 Fuel Plate.Element MIT-12 Removed from Core ML20151R7341988-04-19019 April 1988 Sser for PWR Coolant Chemistry Loop (Pccl) MITNRL-020 ML20236S4931987-11-19019 November 1987 RO 50-20/1987-2:on 871110,improper Performance of Reactor Reshim Resulted in Excessive Power Rise.Caused by Operator Error.Operator Suspended from All Licensed Duties Pending Further Review of Circumstances & Disciplinary Measures ML20237K6121987-06-30030 June 1987 Mit Research Reactor Annual Rept to NRC for Jul 1986 - June 1987 ML20151R7271987-02-13013 February 1987 SER for PWR Coolant Chemistry Loop (Pccl) MITNRL-020 ML20213G0601986-11-0606 November 1986 RO 50-20/1986-3:on 861027,shim Blade 6 Could Not Operate at full-out Position Due to Mechanical Interference.Caused by Misalignment of Blade Proximity Switch Tube.Switch Tube Reinstalled Properly ML20214V9001986-10-17017 October 1986 Revised RO 50-20/1986-2:on 861008,elevated Levels of Fission Gases Discovered in Primary Containment.Cause Undetermined. Refueling Initiated & Element MIT-19 Removed.All in-core Elements Sipped.No Abnormalities Found ML20214H9541986-10-17017 October 1986 RO 50-020/86-02:on 861008,elevated Levels of Fission Gases in Primary Containment Observed.Cause Unknown.Element MIT-19 Removed from Core & All in-core Elements Sipped ML20148B3011986-06-30030 June 1986 Mit Research Reactor Annual Rept to NRC for Period Jul 1985 - June 1986 ML20154S4591986-02-28028 February 1986 RO 50-20/1986-1:on 860219,fission Product Gas Levels Rose from Normal Operating Levels.Caused by Blister on Surface of Outer Fuel Plate of Element MIT-11.Element MIT-11 Removed from Core ML20214R3811986-01-31031 January 1986 Rept of Educational & Research Activities for Academic/ FY84-85 W/Selected Data from Previous Yrs ML20137G3661985-07-23023 July 1985 RO 50-20/1985-2:on 850715,defect in Fuel Element Cladding Observed.Caused by High Rate of Outgassing from Fuel Element MIT-32.Defective Element Removed ML20133H4081985-06-30030 June 1985 Mit Research Reactor Annual Rept to Us NRC for Jul 1984 - June 1985 1999-07-08
[Table view] |
Text
. - _ _ _ _ _ _ _ _ _ _ _ _ - - _ _ _ __
,0 I" 9 n - s;e, f e' , . . A; C
- cCb NUCLEAR REACTOR LABORATORY iO' AN INT ERDEPARit/E Nl AL CENT E R OF nMSSt.OHUSETlS INSTITUlE Of TLCHNOLOGY h 'I Oh.HARUNG 13J Attaany SPt+t C3 rudge. fAass fIL J A M RNAHD JR Director Teo ebi Na 317 W 7300 D"e c. tor of He e ty Op ' Ao"s Twi tb 501473 t/;T-CAM Te? Na 10m253 4202/4211 August 22,1991 U. S. Nuclear Regulatory Commission Washington, D.C. 20555 Attn: Document Corwol Desk
Subject:
Reportable Occurrence 50-20/1991-1, Detection of an incipient Fuel Element Failure Gentlemen:
Massachusetts Institute of Technology hereby submits this ten-day report of an occurrence at the MIT Research Reactor in accordance with paragraphs 7.13.2(d) and 1.15.4 of the Technical Sp-cifications. An initial report was made by telephone to Region I (Mr. Thomas F. Dragoun) on 13 August 1991, The format and content of this repon 're based on Regulatory Guide 1.16, Revision 1.
- 1. Renort No.: 50-20/1991 1 2a. Renon Date: 22 August 1991 2b. Date of Occuntnce: 12 August 1991
- 3. Facility: MIT Nuclear Reactor Laboratory 138 Albany Street Cambridge,MA 02139
- 4. Identification of Occurrence:
Slightly elevated levels of fission product gases in the air purge that is maintained across the surface of the primary coolant were observed following startup of the reactor to full power at 1722 on 5 August 1991. A sample of the purge gas was then drawn and analyzed. The preliminary analysis indicated that fission product gas levels were approximately 5-10% higher than normal and it was noted that these levels were decreasing 9108300133 910822 V
DR ADOCKOSoogo g %; h -
gtg9 l
~
Reportable Occurrence 50-20SI-l Page 2 toward the nonnal background level which was about 5% of MPC. It was decided to keep the reactor operating in order to generate enough activity so as to be detectable by the fuel element " sipping" process that is used to identify incipient fuel element failures. The reactor was shutdown at 1804 on 9 August 1991 with there having been no further indications of increased air purge activity. All fuel elements were sipped on 12 August 1991. This consists of drawing a quan of coolant through each element and then counting that liquid for activity. Element MIT-17 was identified as having an abnomially high rate of outgassing in that the activity in the water sample drawn through that element dunng the sipping procedure was a factor of two above the average. Subsequcnt visual inspection identified this element as having an occlusion. A refueling was then initiated and element MIT-17 was removed from the core. Reactor operation was resumed later on 12 August 1991 in accordance with the normal operating schedule and fission product gas release levels were observed to be normal.
- 5. Conditions Prior to Occurrence:
Element MIT-17 was first inserted in the reactor's B-Ring on 29 March 1982. It remained in core continuously until 9 August 1982 when it was removed. It was inserted in the B Ring for one operating week in September 1987. Regular use resumed on 29 August 1988 when it was agam placed in the B-Ring and kept there until 9 July 1990.
Element MIT-17 was next placed in the C Ring on 9 May 1991, it remained there until removed as part of the corrective hetion for this occurrence.
- 6. Description of Occurrence:
The fission product gas levels obtained in accordance with standard sampling procedt.res rose from normal operating levels to a maximum of 15% of MPC. This level was observed for less than a minute. It occurred about twenty minutes after the reactor startup on 5 August 1991. The level then rapidly decreased to about 10% of MPC and then over an hour to the current background level. All increases were well below pennitted concentrations (even without averaging over time).
- 7. Description of Anoarent Cause of Occurrence:
The apparent cause of this occurrence is a small blister on one of element MIT-17's fuel plates. This can only be seen when the element is backlighted with Cerenkov radiation. As shown in the attached Figure One,it is located near the center of either the 6th or 71h fuel plates. It is approximately one inch below the top of the element. (Note: ,
There is some possibility that it is a foreign inclusion, not a blister, llowever, this is unlikely given its location near the top of the element and the upward flow of coolant through the core.)
l
Reportable Occurrence 50-2(W1-1 .
Page 3
- 8. Analvsis of Occum nce:
Quality assurance records on the manufacture of element h!IT-17 do not indicate any deviations from h1ITR element specifications. Element htIT-17 had been in-core while 42197.27 hiWH of energy were produced. It has 403.59 grams of its original 506 gram loading of U-235 remaimng. The point of peak burnup on hilt-17 was 49.35% of the allowed fission density (1.8x101 2 fissions /cc). Primary coolant chemistry is carefully monitored. 'the three parameters measured (pil, chloride, conductivity) have generally been as specified. The few deviations that have occurred were too brief and of too low a magnitude to have caused this occurrence.
- 9. Corrective Action:
The immediate corrective action consisted of removing element hilt 17 from the core. Fission aroduct gas levels were normal prior to the occurrence and have remained normal. The c ad failure was detected and addressed during its incipient stage.
- 10. Fr.ilum Data:
A cladding failure occurred to a "4ht" series element in June 1979. Refer to ROR
- 50-20n9-4 dated 2 July 1979 and #50-20n9-4A dated 26 November 1980. Excess outgassing occurred in an " hilt" series element in September 1983, in July 1985, in February 1986, in October 1986, and in hiay 1988. Refer to ROR #5D-20/83 2,
- 50-20/85-2,50-20/86-1,50-20/86-2, and 50-20S81. The current failure is not the most severe of those noted. ("h11T" series fuel was made by Atomics International. The "4ht" series was made by Gulf Atomic. Currently, fuel is being procured from Babcock and Wilcox.)
Operating experience with fuel from all ncnufac'arers has been good, except as noted below. Of 43 elements made by Gulf Atomic,42 elements (630 plates) have been permanently discharged from the core after peak burnup approached the license limit. *lhe other 4h1 series element failed in 1979 as reported earlier, at an average bumup of 32.5%.
' Average burnups on the Gulf Atomic fuel are in the range 42-44%. Of the 39 elements made by Al and subsequently used in the hilTR core,26 elements (390 plates) have achieved the maximum permissible burnup and have peak fission densities of 1.58x1021 fissions /cc and average burnups of 37.4%. The thirteen other Al series elements (195 plates) now in use or awaiting reuse have peak fission densities in the range 0.057 to 1.52x101 2 f ssior,s/cc. As previously reported, five other Al series elements were previously discharged due to excess outgassing.
Reportable Occurrence 50-20N1-1 Page 4 Th failure of this sixth Al element means that six plates from a total of 585 plates have now exhibited excessive outgassing. Because of the sensitivity of MITR Il monitoring equipment, radiation releases have been insignificant.
Fuel for the MIT Research Reactor is currently being manufsetured by the Babcock and Wilcox (B&W) Company. Twelve B&W clements (180 plates) are curn:ntly in-core with the most utilized of those elements currently having achieved a peak fission density of 2
0.96x101 f ssions/cc. There have been no failures of B&W fuel to date.
Sincerely, M
Kwan S. Kwok, Ph.D.
[L Superintendent MIT Research Reactor
<k Ci b4 ohn A. Bernard, Ph.D.
Director of Reactor Operations MIT Research Reactor JAB /KSK:gw
Attachment:
Figure One cc: MITRSC USNRC - Region 1 - Chief, Reactor Pmjects Section No. 3A USNRC - Region I- Reactor Engineer, Reactor Projects Section No. 3A USNRC - Senior Resident Inspector, Pilgrim Nuclear Station USNRC - Project Manger, Standaniization and Non-Power Reactor Project Directorate USNRC - Region I- Chief, Effluents Radiation Protection Branch
r i
Reponable Occurrence S20/1991 1 Attachment j i
i l
i i
)
Elemerit Bale ;
N !
y Blister A Fuel Plate ;
xx y./
N s i
i k
i
- Figure One
- Horizontal Cross Section of MITR Fuel Element Showing Blister Location !
,e--- - -