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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of Shim Blade Drive Mechanism Occurred.Determined That Mechanism Experienced Intermittent Slippage When Blade Being Withdrawn.Blade Drive Mechanism Assembly Procedure PM 7.1.1.1 Will Be Reviewed ML20086T7571995-07-28028 July 1995 RO 50-20/1995-4:on 950720,operated W/One Shim Blade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
- _ _ _ _ _ _ - _ _ - . . _
1 ybMk{ ,
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.: NUCLEAR. REACTOR LABORATORV -
AN INTERDEPARTMENTAL CENTER OF %)*Ky((
MASSACHUSETTS INSTITUTE OF TECHNOLOGY >
l O K. HARLING 138 Albany Street Cambridge, Mass. 02139 L CLAHX, JA.
Director (617) 253-4 2 1 1 Director of Reactor Operations g
Nove$1ber 19, 1987 l
i U.S. Nuclear Regulatory Commission ,
l i Attn: Document Control Desk Washington, D.C. 20555 Subj ect: Reportable Occurrence 50-20/1987-2, Improper Reactor Reshim Causing an Excessive Power Rise l Gentlemen:
Massachusetts Institute of Technology hereby submits this ten-day report of an occurrence at the MIT Research Reactor in accordance with paragraph 7.13.2(d) of the Technical Specifications. An initial re-port was made by telephone to the NRC Headquarters Operations Of ficer, The occurrence was referred td Mr. Ray Smith on 11 November 1987.
Mr. Ted Michaels by the . Headquarters Office. It was discussed 'with Mr. Michaels on 12 November 1987. A further report of this occurrence was made by' telephone to Region I, Mr. Larry Doerflein, on 13 November 1987.
The format and content of this report are based on Regulatory Guide 1.16, Revision 1.
~>
- 1. Report No.: 50-20/1987-2 , l 2a. Report Date: 19 November 1987.
v 2b. Date of_0ccurrence: 10 November 1987 ,
- 3. Facility: MIT Nuclear Reactor Laboratory ,
138 Albany Street H Cambridge, MA 02139 i
- 4. Identification of Oc_currence:
Improper performance of a reactor restAiro e.o that as a, result of manual withdrawal of a shim blade, , the reactor's peatronic power rose f rom 4.71 MW to 5.18 MW at which level the safety sys-tem caused an automatic shutdown. This occuricL 4t 1523 10 /
November 1987. The reactor's thermal power, which is continunos-ly computed by a calorimetric balance . o r.d recorded, never exceeded 4.71 MWt.
8711250203 871119 '
gDR ADOCK O go i
o - _ - - - - - - - - - - - - - - - --
(
s Reportable Occurrence 50-20/1987-2 Page 2
- 5. Conditions Prior to Occurrence:
The reactor was on analog control at s steady-stacc power of 4.71 MWt with the shim bank at 10.30 inches. Channel #7, the linear flux channel, was indicating 86.0 pa. The eactor had been operating at power for only a few hours and xenoc was build-ing into the core. The regulating rod was therefore ceing gradu-ally withdrawn by the analog automatic controller . fu order to Gompensate for the negative reactivity associated wilb the xenon.
When the regolating rod attained a height of abcut 11.30 inches,
- the console operator decided to reshim the reactor.
- 6. Desegiption of Occurrence:
Reactor reshims are normally performed by first placing the
, nactor on manual control and t. hen ins e r t.ing the regulating rod while maintaining the reactor power to within 1.5% of the desired power level. Each of the reactor's six shim blades are then withdrawn slightly so as to (1) maintain the power within the ope ra t.ing band and (2) maintain an even shim bank height'. The -
pro:ess is continued until the . regulating rod is inserted to
. maut 2.50 inches.
Relative to the reshim in question, the operator placed ' the
' r reactor on manual control and selected the first shim blade (blade #1) with the shim blade selector switch. He then d e two mistakes. First, he turned the pistol-gnp handle of the regu-lating rod's control switch so that the rod moved outward instead of inward. This action had only a smali ef feet on the react or power because the regulating rod's differential reactivity worth at 11.30 inches is relatively low. However, it did cause the neutronic power to exceed the allowed deviation band. Operation i in this manner is contrary to existing written proceduro. The operator's second mistake was more serious. Rather thau fuvestigating the reason for the power deviation being on the positive side of the allowed operating band and co nt ra ry t.o :he normal practice of not withdrawing a blade unless the power is on th' i m side of the band, he began withdrawing the' blade. As a result, the neutronic power rose rapidly. The linear flux channel attained a value of 94.6 pa which corresponds to a powe.'
level of 5.18 MW. Upon reaching that, pwer level, the reactor 's safety system caused an automatic shutdawn on excessive power.
- 7. Descripti3n of Apparent Cause of Occurrence:
The apparent cause of this occurrence was operator error in that O) the operator moved the regulating rod in the wrong direction cad (2) withdrew a shim blade while the power level exceeded the desired value.
- 8. Analysis of_0ccurrence:
The reactor's neutronic power, as measured by the trace recorded on the strip chart f or channel #7 (the linear flux chan-
Reportable Occurrence 50-20/1987-2 Page 3 3
nel)[ reached ' 5.18 W. It exceeded the license limit of 5.0 W f or 2no'saore than 2 or 3 secco.ds. A copy of the relevant portion
- of ' thin strip chart is attached.
Reactor power, as recorded on ]
the dierO1 power strip chart, .did not change f rom its original value of 4.71 W.
It in. not expected inat an excursion to the 5.18 W neutron-ic power le vel reached in this case, which is well below the i authorized limiting eafety system setting of 6 W, would in any j way cause any damage to the reacto r. Nevertheless, immediately following this occurrence, analyses we re made of the primary coolant. No abnormalities were identified. The core purge gas monitor os normal and ' a subsequent visual inspection of the reactor ese revealed no abnormalities. l'hese actions confirmed that no damage occurred to the reactor.
- 9. Correctf.ve Action:
l .
The 'following corrective actions have been taken:
, u ;
(a) The operator involved in this occurrence was suspended from f
, all 1(ceused duties pending further review of the circum-
, stances anii a decision regarding appropriate retraining and/
or disciplinary measures.
(b) This occurtence was re41cwed by the senior reactor staff and by the Chairman of the MIT Reactor Safeguards Committee on f 1
'4 , 13 November 1987. ;
1 !
(c) The reactor staff reviewed the existing written procedures governing the performance of reshims and determined them to ;
be adequate.
(d) This occurrence was discussed with . all licensed operators I
and the importance of properly performing reshims was emphasized. l a
- 10. Failure Data:
l No evend of this exact type has previously occarred. An ]
/ improper reshim did gecur ' on 19 November 1985 but it did not i l .
result in a reportable c event and its causes were very dif ferent
/
I
, f rom those described in this report.
Sincerely,
/s u
'wan S. Kuok s ohn A. Fernard, Ph.D. Lincoln Clark, Jr. ,
. Asst. Superintendent Superintendent Director of Operations l 1
JAB /gw ,
Oopy to: MITRSC USNRC, Region I - Chief, Reactor Projects Section IB USNRC, Region 1 - Project Inspector USNRC - Resident Inspector, Pilgrim Nuclear Station
__.____m_____ _ _ _ . - _ _ _ _ . . _
Reportable Occurrence 50-20/1957-2
. Page 4
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4.71 W 5.18 W 86.0 pA 94.6 pA
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Linear Neutron Power (Ch. 7)