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ENS 5558316 November 2021 15:59:00University Of Missouri Research Reactor (MURR) Technical Specification (TS) 6.6.c(1) requires notification to the NRC Operations Center that an Abnormal Occurrence, as defined by MURR TS 1.1, has occurred. MURR was not in compliance with one (1) of the TS Limiting Conditions of Operations. TS 3.2.g states, 'The reactor safety system and the number (N) of associated instrument channels necessary to provide the following scrams shall be operable whenever the reactor is in operation.' Specifically, the reactor safety scram function that occurs when the differential pressure across the reactor pool reflector (PT-917) instrument channel decreases below 2.52 psi minimum in Mode 1 operation was not operable as required by TS 3.2.g.10. On 11/15/21 while the reactor was shut down, Control Room operators shut down the pool coolant system and noticed that the `Reflector Hi-Low Diff Pressure Scram' annunciator alarm did not initiate as pool coolant flow rate decreased to zero. The Control Room operators contacted reactor management, and an investigation was initiated to prove whether or not the safety scram function from the PT-917 instrument channel actuated correctly. Further testing revealed the safety scram signal from the PT-917 instrument channel did not occur due to a failed alarm-meter unit. The alarm-meter unit was replaced with an exact spare, the PT-917 instrument channel was calibrated, and the reactor safety scram functions of the PT-917 instrument channel were retested satisfactorily. In accordance with TS 6.6.c(4), the Reactor Facility Director was briefed and gave permission to restart the reactor prior to the reactor returning to operation later on 11/15/21. Currently, MURR is operating at 10 MW. A detailed event report will follow within 14 days as required by MURR TS 6.6.c(3). The NRC Project manager was notified.
ENS 555689 November 2021 23:50:00This is a required notification per University Of Missouri Research Reactor (MURR) Technical Specification (TS) 6.6.c(1) to report to the NRC Operations Center that an Abnormal Occurrence, as defined by MURR TS 1.1, had occurred. MURR was not in compliance with one Limiting Conditions of Operations (LCO). TS 3.2.f states, 'The reactor shall not be operated unless the following rod run-in functions are operable.' Specifically, the rod run-in function that occurs when water level in the anti-siphon system is greater than or equal to 6 inches above the anti-siphon isolation valves was not operable as required by TS 3.2.f.6. On 11/8/21 while the reactor was shut down for maintenance and conducting surveillance testing on the anti-siphon system high level rod run-in instrument channel, the surveillance testing provided measurement that indicated the rod run-in actuation may not have occurred until water level was slightly greater than 6 inches above the anti-siphon isolation valves. Previously on 4/22/2021, the anti-siphon system high level rod run-in instrument channel activated the rod run-in well below the top of the anti-siphon isolation valves. Troubleshooting revealed the stainless-steel cable that connects the channel's level controller to its suspended displacer (float) had developed loops in it, effectively shortening the cable. The cable with loops made the rod run-in actuation occur at a higher water level than when the cable has no loops in it. The loops in the cable were removed. The instrument channel was retested and documented to be back in compliance with TS 3.2.f.6. On 11/9/21, MURR engineers analyzed the data collected from the 11/8/21 measurement and concluded that prior to removing the loops from the level controller cable, the rod run-in was actuating at a level of approximately 7.3 inches above the anti-siphon isolation valves, which is greater than the maximum of 6 inches above the valves required by TS 3.2.f.6. In accordance with TS 6.6.c(4) before it was known if MURR deviated from TS 3.2.f.6, the Acting Reactor Facility Director was briefed and gave permission to restart the reactor prior to the reactor returning to operation later on 11/8/21. Currently, MURR is operating at 10 MW. A detailed event report will follow within 14 days as required by MURR TS 6.6.c(3).
ENS 5551612 October 2021 13:12:00(This notification is required) per University Of Missouri Research Reactor (MURR) Technical Specification (TS) 6.6.c(1) to report to the NRC Operations Center that an Abnormal Occurrence, as defined by MURR TS 1.1, had occurred. MURR was not in compliance with one (1) Limiting Conditions of Operations (LCO). TS 3.2.g. which states, 'The reactor safety system and the number (N) of associated instrument channels necessary to provide the following scrams shall be operable whenever the reactor is in operation..' TS 3.2.g.6 requires four (4) Primary Coolant Low Pressure reactor safety system instrument channels provide a reactor scram when the primary coolant pressure corresponding to the pressurizer during normal flow drops below 75 psia. Surveillance testing on 10/11/2021 revealed that one (1) of the four (4) channels was not operable. On 10/11/21 while the reactor was shutdown for maintenance and conducting surveillance testing on the reactor core outlet pressure channels, the surveillance testing revealed that the reactor core outlet pressure channel associated with pressure transmitter 944B did not provide a reactor scram at an appropriate TS low pressure setpoint. On 10/11/21, the Primary Coolant Low Pressure reactor safety instrument channel 944B scram setpoint was calculated to be 74.43 psia which is slightly below the required 75 psia minimum. Previously on 4/12/2021, the Primary Coolant Low Pressure reactor safety instrument channel 944B scram setpoint was calculated to be 76.94 psia which is within the TS-required setpoint range. So, sometime between 4/12/2021 and 10/11/2021, the reactor possibly operated while one (1) of the four (4) instrument channels deviated from TS 3.2.g.6. Troubleshooting revealed the component in instrument channel 944B that caused the setpoint deviation. That component was replaced with an exact spare, and the instrument channel was retested and documented to be back in compliance with TS 3.2.g.6. In accordance with TS 6.6.c(4), permission from the Reactor Facility Director was obtained prior to the reactor returning to operation later on 10/11/21. Currently, MURR is operating at 10 MW. A detailed event report will follow within 14 days as required by MURR TS 6.6.c(3).
ENS 5538027 July 2021 13:56:00On July 26, 2021 at 1731 CDT, while the reactor was subcritical during a reactor startup, the University of Missouri-Columbia Research Reactor (MURR) was manually shut down due to the failure of the control rod drive mechanism for shim control blade B. MURR was not in compliance with one (1) Limiting Conditions of Operations (LCO). TS 3.2.a states, 'All control blades, including the regulating blade, shall be operable during reactor operation.' A spare control rod drive mechanism was installed for control blade B, post-installation operability testing was conducted satisfactorily, and permission from the Reactor Facility Director was obtained prior to the reactor returning to operation later on July 26, 2021. Currently, MURR is operating at 10 MW (full power). A detailed event report will follow within 14 days.
ENS 5466010 April 2020 17:30:00On 4/9/20, at 1432 CDT, the University of Missouri-Columbia Research Reactor (MURR) was shut down due to the failure of the geared rotary limit switch assembly to move with corresponding regulating blade drive mechanism movement. This email is a required notification per MURR Technical Specification (TS) 6.6.c(1) to report to the NRC Operations Center that an Abnormal Occurrence, as defined by MURR TS 1.1, had occurred. MURR was not in compliance with one (1) Limiting Conditions of Operations (LCO). TS 3.2.f states, 'The reactor shall not be operated unless the following rod run-in functions are operable.' Specifically, the rod run-in function that occurs when regulating blade position is less than or equal to 10 percent withdrawn was not operable as required by TS 3.2.f.8. The regulating blade drive mechanism was repaired, post-maintenance operability testing was conducted satisfactorily, and permission from the Reactor Facility Director was obtained prior to the reactor returning to operation later on 4/9/20. Currently, MURR is at 10 MW. A detailed event report will follow within 14 days as required by MURR TS 6.6.c(3).
ENS 546539 April 2020 09:35:00On 4/8/20 at 0100 CDT, the University of Missouri-Columbia Research Reactor (MURR) was shut down due to a failure of the regulating blade drive mechanism to move the regulating blade during reactor operation. This email is a required notification per MURR Technical Specification (TS) 6.6.c.(1) to report to the NRC Operations Center that an Abnormal Occurrence, as defined by MURR TS 1.1, had occurred. Specifically, MURR was not in compliance with all Limiting Conditions for Operations (LCOs). MURR was not in compliance with two (2) LCOs: 1. TS 3.2.a states, 'All control blades, including the regulating blade, shall be operable during reactor operation,' and 2. TS 3.2.f states, 'The reactor shall not be operated unless the following rod run-in functions are operable.' Specifically, the rod run-in function that occurs when the regulating blade position is less than or equal to 10 percent withdrawn was not operable as TS 3.2.f.8 requires. The regulating blade drive mechanism was repaired, post-maintenance operability testing was conducted on the regulating blade, and permission from the Reactor Facility Director was obtained prior to the reactor returning to operation later on 4/8/20. Currently, MURR is at 10 MW. A detailed event report will follow within 14 days as required by MURR TS 6.6.c.(3).
ENS 5418730 July 2019 13:47:00The following information was received via email: On July 29, 2019, at 1903 CDT, the University of Missouri-Columbia Research Reactor (MURR) was shut down due to a failure of the regulating blade drive mechanism during reactor operation. This email is a required notification per MURR Technical Specification (TS) 6.6.c(1) to report to the NRC Operations Center that an Abnormal Occurrence, as defined by TS 1.1, had occurred. MURR was not in compliance with all Limiting Conditions for Operations (LCOs), specifically TS 3.2.a, which states, 'All control blades, including the regulating blade, shall be operable during reactor operation.' The regulating blade drive mechanism was removed, repaired, reinstalled, and all its functions were tested satisfactorily. Permission from the Reactor Facility Director was obtained per TS 6.6.c(4) prior to starting up the reactor later on July 29. Currently, MURR is at 10 MW. A detailed event report will follow within 14 days as required by TS 6.6.c(3). The licensee has notified the NRC Research and Test Reactor Project Manager.
ENS 541495 July 2019 09:18:00The following was received via e-mail: On July 1, 2019, sometime between 1100 and 1200 CDT with the reactor shut down and during performance of electrical preventative maintenance, the University of Missouri-Columbia Research Reactor (MURR) deviated from Technical Specification (TS) 3.4 because reactor containment integrity did not exist for approximately ten (10) minutes while the reactor was not secured, as defined by TS 1.26. During this event time, two (2) shim control rod drive mechanisms were not installed because scheduled work was in progress on these drive mechanisms. Therefore, the reactor was not secured per TS definition 1.26, but the reactor was shut down per TS definition 1.27. Also during this time, and unknown to the Control Room operators, an Electronics Technician opened the two (2) electrical motor breakers to the reactor containment system's two (2) automatically-closing doors one at a time for approximately 5 minutes each. Though this event happened on July 1, no NRC-licensed operator knew that the automatically-closing door motor breakers had been opened on July 1 until mid-day on July 3. Once the abnormal occurrence was realized, the Reactor Facility Director was briefed on the situation on the afternoon of July 3, and he gave permission to continue reactor operation in accordance with TS 6.6.c.(4). This email is a required notification per TS 6.6.c.(1) to report to the NRC Operations Center that an Abnormal Occurrence, as defined by TS 1.1.b, has occurred. MURR was not in compliance with all of the Limiting Conditions for Operations as established in TS Section 3.0. A detailed event report will follow within 14 days as required by TS 6.6.c.(3).
ENS 5403429 April 2019 12:19:00On April 28, 2019, at 0633 CDT, with the University of Missouri-Columbia Research Reactor (MURR) operating at 10 MW in the automatic control mode, the Lead Senior Reactor Operator (LSRO) was conducting surveillance Technical Specification (TS) 4.2.a, which states, 'All control blades, including the regulating blade, shall be verified operable within a shift.' During this verification of control blade operability, shim control blades 'A,' 'B,' 'C,' and the regulating blade were verified operable. However, shim control blade 'D' would not move in the inward direction. The LSRO then immediately shut down the reactor by initiating a manual scram by placing Master Control Switch 1S1 to the 'TEST' position. The LSRO completed all immediate and applicable subsequent actions of reactor emergency procedure REP-8, 'Control Rod Drive Mechanism Failure or Stuck Rod,' and verified all shim control blades were fully inserted. This email is a required notification per TS 6.6.c(1) to report to the NRC Operations Center that an Abnormal Occurrence, as defined by TS 1.1.b, has occurred. MURR was not in compliance with all of the Limiting Conditions for Operations (LCOs) as established in TS Section 3.0. The failure of the control rod drive mechanism to insert shim control blade 'D' is a deviation from TS 3.2.a, which states, 'All control blades, including the regulating blade, shall be operable during reactor operation.' In addition, shim control blade 'D' would not have inserted during the activation of any rod run-in function listed in TS 3.2.f - shim control blades 'A,' 'B,' and 'C' would have inserted. All reactor safety system scram functions were unaffected and remained operable during this event. Troubleshooting revealed a broken wire to the inward motor winding of shim blade 'D' control rod drive mechanism. The wire was repaired, and the shim control blade 'D's operability was tested satisfactorily. Permission from the Reactor Facility Director was obtained prior to reactor startup per TS 6.6.c(4), and the reactor returned to 10 MW operation at 1319 CDT on April 28. A detailed event report will follow within 14 days as required by TS 6.6.c(3).
ENS 5384928 January 2019 15:01:00On January 27, 2019, at 1913 CST, with the University of Missouri-Columbia Research Reactor (MURR) operating at 10 MW in the automatic control mode, the Lead Senior Reactor Operator (LSRO) was conducting surveillance Technical Specification (TS) 4.2.a, which states, 'All control blades, including the regulating blade, shall be verified operable within a shift.' During this shiftily verification of control blade operability, all blades were initially verified operable. However, when banking the control blades to their final position after all blades were satisfactorily tested a few seconds earlier, shim control blade 'A' would not move in the inward direction. The LSRO then immediately shut down the reactor by initiating a manual scram by placing the Master Control Switch 1S1 to the 'TEST' position. The LSRO completed all immediate and subsequent actions of reactor emergency procedure REP-2, 'Reactor Scram,' and verified all shim control blades were fully inserted. The inability to manually insert shim control blade 'A' with Control Rod Operate Switch 1S4, which inserts and withdraws the control blade, is a deviation from TS 3.2.a, which states, 'All control blades, including the regulating blade, shall be operable during reactor operation.' Troubleshooting revealed a problem with an electrical contact on Control Rod Operate Switch 1S4, and it has since been replaced. The reactor has not returned to operation at the time of this email. However, permission from the Reactor Facility Director has been obtained to restart the reactor once scheduled maintenance activities have been completed. A detailed event report will follow within 14 days as required by MURR TS 6.6.c(3).
ENS 5384122 January 2019 12:15:00On January 21, 2019 at approximately 1235 CST, with all four (4) shim control rods fully inserted into the reactor core during performance of a pre-startup checklist, the University of Missouri-Columbia Research Reactor (MURR) deviated from Technical Specification (TS) 3.3.a(1) due to test jumpers being installed while electrical power was available to the shim rod drive mechanism electromagnets. Prior to this event, the reactor was shut down for a regularly-scheduled maintenance period. A required notification per TS 6.6.c(1) to report to the NRC Operations Center that an Abnormal Occurrence, as defined by MURR TS 1.1, had occurred. Specifically, MURR was not in compliance with all TS Limiting Conditions for Operations, specifically TS 3.3.a(1). For about ten (10) seconds at approximately 1235 CST, power was available to the shim rod drive mechanism electromagnets while electrical test jumpers, which hold anti-siphon system isolation valves V543A and V543B closed, were inserted. In effect, the anti-siphon system was not operable while the reactor was technically operating for ten (10) seconds per the following definitions: 1. TS 1.23 Reactor in Operation - The reactor shall be considered in operation unless it is either shutdown or secured. 2. TS 1.27 Reactor Shutdown - The reactor is shutdown when: All four (4) of the shim blades (rods) are fully inserted and power is unavailable to the shim rod drive mechanism electromagnets. 3. TS 1.26 Reactor Secured - MURR did not meet the definition of Reactor Secured during the event. Though all four shim rods were fully inserted and a reactor startup had not commenced, electrical power being available to the shim rod drive mechanism electromagnets caused the reactor to technically be in Operation for a very brief period. Though this event happened at approximately 1235 CST, it was not fully identified as an abnormal occurrence per TS 1.1.b until approximately 1625 CST, after a reactor startup was performed to 10 MW operation. Once the abnormal occurrence was realized, the Reactor Facility Director was immediately notified at 1715 CST, and he gave permission to continue reactor operation. A detailed event report will follow within 14 days as required by MURR TS 6.6.c(3).
ENS 532445 March 2018 13:14:00On 3/4/17 at 0308 CST, the MURR (University of Missouri Research Reactor) emergency power generator was switched out of automatic control for approximately 10 to 15 seconds while the reactor was operating due to human error. With the emergency power generator in manual control, the emergency electrical power system is considered inoperable because the emergency electrical power system would not have supplied power in the event of a loss of normal electrical power. This email is a required notification per MURR Technical Specification (TS) 6.6.c.(1) to report to the NRC Operations Center that an Abnormal Occurrence as defined by MURR TS 1.1 happened. Specifically, MURR was not in compliance with the Limiting Condition for Operation TS 3.6.a which states, 'The reactor shall not be operated unless the emergency electrical power system is operable.' When the emergency power generator was switched out of automatic control, a Control Room alarm notified the Console Operator. Another operator placed the emergency power generator back into automatic mode which was the quickest way to regain compliance with TS 3.6.a. The MURR continued to operate at 10 MW. A detailed event report will follow within 14 days as required by MURR TS 6.6.c.(3). The licensee notified the NRC Research and Test Reactor Project Manager (Wertz).
ENS 531422 January 2018 13:16:00On 12/30/17 at 0717 CST, the University of Missouri-Columbia Research Reactor (MURR) was shut down due to the loss of negative pressure in the reactor containment building. Prior to the shutdown, the reactor was operating for a period of time during the loss of negative pressure which is a deviation from MURR Technical Specifications (TS). This email is a required notification per TS 6.6.c.(1) to report to the NRC Operations Center that an Abnormal Occurrence, as defined by MURR TS 1.1, had occurred. Specifically, MURR was not in compliance with all TS Limiting Conditions for Operations (LCOs). MURR was not in compliance with TS's 3.4.b and 3.4.a.(6). TS 3.4.b. states, 'Reactor containment integrity shall be maintained at all times except when: (1) The reactor is secured...' TS. 3.4.a.(6) states, 'For reactor containment integrity to exist, the following conditions shall be satisfied:...(6) The reactor containment building is at a negative pressure of at least 0.25 inches of water with respect to the surrounding areas: and...' While on Routine Patrol on the morning of 12/30/17, an operator noted that the differential pressure gauge between the reactor containment building and the MURR laboratory building was reading zero (0.0) inches of water vacuum. The operator on Routine Patrol radioed the Lead Senior Reactor Operator in the Control Room, and the reactor was shut down. The cause of the loss of negative pressure was the closing of a backup ventilation exhaust door from the reactor containment building. With the backup ventilation exhaust door closed, the ventilation system was only supplying air to the reactor containment building, not allowing a balanced air recirculation to maintain a negative pressure. The backup ventilation exhaust door actuator was found to be inoperable. The backup ventilation exhaust door operation was repaired by melting ice that had formed in the air supply lines to the door's operating air cylinder. Condensation that had formed in the air lines was removed, and heat trace and insulation were installed around all the backup door air supply lines. The compliance procedure for verifying backup ventilation doors' operability was conducted satisfactorily as post-maintenance testing. Permission from the Interim Facility Director was obtained prior to the reactor returning to operation later on 12/30/17. A detailed event report will follow within 14 days as required by MURR TS 6.6.c.(3).
ENS 528415 July 2017 16:19:00On 7/4/17 at 0232 CDT, the University of Missouri-Columbia Research Reactor (MURR) was shut down due to the suspected inoperability of the Source Range Nuclear Instrument Channel during reactor startup. This is a required notification per MURR Technical Specification (TS) 6.6.c.(1) to report to the NRC Operations Center that an Abnormal Occurrence, as defined by MURR TS 1.1, had occurred. Specifically, MURR was not in compliance with all Limiting Conditions for Operations (LCOs). MURR was not in compliance with TS 3.5.a.3. and its associated note (1). TS 3.5.a.3 states, 'The reactor shall not be operated unless the following instrument channels are operable: ...3. Source Range Nuclear Instrument Channel...'. Note (1) clarifies that the Source Range Nuclear Instrument Channel is 'required for reactor startup only.' During the first rod withdrawal of the reactor startup, the Source Range Nuclear Instrument Channel indication was erratic. Therefore, it was decided to shut down the reactor. The Source Range Nuclear Instrument Channel was repaired by replacing two power supplies in its instrument drawer, the required compliance procedures were conducted on the nuclear instrument, and permission from the Facility Director was obtained prior to the reactor returning to operation later on 7/4/17. Currently, MURR is at 10 MW. A detailed event report will follow within 14 days as required by MURR TS 6.6.c.(3).
ENS 5270221 April 2017 11:28:00On 4/20/17 at 1449 CDT, the University of Missouri-Columbia Research Reactor (MURR) was shut down due to a failure of the regulating blade drive mechanism to move the regulating blade during reactor operation. This email is a required notification per MURR Technical Specification (TS) 6.6.c. (1) to report to the NRC Operations Center that an Abnormal Occurrence, as defined by MURR TS 1.1, had occurred. Specifically, MURR was not in compliance with all Limiting Conditions for Operations (LCOs). MURR was not in compliance with two (2) LCOs: 1. TS 3.2.a states, 'All control blades, including the regulating blade, shall be operable during reactor operation' and 2. TS 3.2.f states, 'The reactor shall not be operated unless the following rod run-in functions are operable.' Specifically, the rod run-in function that occurs when the regulating blade position is less than or equal to 10% withdrawn was not operable as TS 3.2.f.8 requires. The regulating blade drive mechanism was repaired, the required compliance procedure was conducted on the regulating blade, and permission from the Acting Facility Director was obtained prior to the reactor returning to operation later on 4/20/17. Currently, MURR is at 10 MW. A detailed event report will follow within 14 days as required by MURR TS 6.6.c.(3). The cause of this event is not related to the cause of the earlier regulating blade drive mechanism failure on 1/17/17.
ENS 525366 February 2017 17:30:00(The following) is a required notification per MURR (University of Missouri Research Reactor) Technical Specification (TS) 6.6.c.(1) to report to the NRC Operations Center that an Abnormal Occurrence as defined by MURR TS 1.1.b occurred on February 3, 2017. Specifically, MURR was not in compliance with the Limiting Condition for Operations TS 3.7.b. On February 3, 2017, MURR released the radioisotope Iodine-131 from the ventilation exhaust stack at a concentration equal to 1.07 times AEC (Air Effluent Concentration) which exceeds the one (1) AEC Maximum Controlled Instantaneous Release Concentration for 'Particulates and halogens with half-lives greater than 8 days'. The Iodine-131 originated from the MURR Iodine-131 Processing Hot Cells, not from the reactor. By February 4, 2017, the ventilation exhaust stack radioisotope concentration was within TS limits. Currently, all Iodine-131 processing activities have ceased and will not resume until corrective actions are implemented and permission from the Facility Director is obtained. MURR has convened an Event Review per MURR procedure AP-RR-026 to identify the causes and corrective actions for this departure from specification. A detailed event report will follow within 14 days as required by MURR TS 6.6.c.(3).
ENS 5249518 January 2017 10:04:00On 1/17/17 at 2130 CST, the MURR (University of Missouri Research Reactor) was shut down due to the failure of the regulating blade to move. This email is a required notification per MURR TS 6.6.c.(1) to report to the NRC Operations Center that an Abnormal Occurrence as defined by MURR TS 1.1 happened. Specifically, MURR was not in compliance with all Limiting Conditions for Operations (LCOs). MURR was not in compliance with the LCO TS 3.2.a. which states, 'All control blades, including the regulating blade, shall be operable during reactor operation.' The regulating blade was repaired, and the required compliance procedure was conducted on the regulating blade prior to the reactor being started up on 1/18/17. Currently, MURR is again at 10 MW. A detailed event report will follow within 14 days as required by MURR TS 6.6.c.(3). The reactor was at 10 MW power when this event occurred. The cause of this event is under investigation. The licensee notified the NRC RTR Project Manager.
ENS 5247910 January 2017 09:56:00On Jan 09, 2017, during movement of a reactor regulating blade, an expected annunciator did not occur. This required entry into Technical Specification 3.2.F.8. The rod run in relay and contact block were replaced and the system tested satisfactorily. Technical Specification 3.2.F.8 was subsequently exited. The licensee will be notifying the Research and Test Reactor Project Manager.
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