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During performance of a preventive mainten … During performance of a preventive maintenance check of (Item Relied On For Safety) IROFS 3526 (Uranium Dioxide steam supply system), it was determined to have failed, that is, blocked preventing it to perform its safety function as a vacuum breaker. This vacuum breaker is in a steam line from an unfavorable geometry steam boiler to process service subsystems. This vacuum breaker is designed to prevent backflow from Tank TK-102 when the heat exchanger E-102 leaks internally and the steam supply is off, Accident Sequence 2.13, in E04-NCSA-070 version 11 for the ADU (Ammonium Diuranate) process. This vacuum breaker is also used in Accident Sequence 5.4, E04-NCSA-120 version 16 for the UNH (Uranal Nitrate Hydroxide) reprocessing Integrated Safety Analysis (ISA). This sequence is the transfer of UNH from uranium powder dissolver to the unfavorable geometry steam boiler when the loss of its heat source causes a vacuum in the steam boiler. Additionally this IROFS is used in Accident Sequence 7.5, E04-NCSA-190 version 10 for the UO2 pellet dissolution process. The IROFS prevents UNH to backflow into the unfavorable geometry steam boiler. The UO2 steam boiler was shut down at the time of the finding and remains shutdown. The other IROFS 3527 in these sequences remained available during the time. This was verified when performing the PM.</br>This determination was completed at 1055 PDT on 10/27/2013. The extent of condition to evaluate other potential uses of this type of vacuum breaker is underway. The safety significance is low as the independent IROFS 3527 was verified to be available and reliable via the testing. The system was shut down and remains shutdown for further evaluation, the failed vacuum breaker has been replaced and verified operable.</br>The licensee will notify Region II.rable.
The licensee will notify Region II. +
17:55:00, 27 October 2013 +
49,475 +
14:16:00, 27 October 2013 +
17:55:00, 27 October 2013 +
During performance of a preventive mainten … During performance of a preventive maintenance check of (Item Relied On For Safety) IROFS 3526 (Uranium Dioxide steam supply system), it was determined to have failed, that is, blocked preventing it to perform its safety function as a vacuum breaker. This vacuum breaker is in a steam line from an unfavorable geometry steam boiler to process service subsystems. This vacuum breaker is designed to prevent backflow from Tank TK-102 when the heat exchanger E-102 leaks internally and the steam supply is off, Accident Sequence 2.13, in E04-NCSA-070 version 11 for the ADU (Ammonium Diuranate) process. This vacuum breaker is also used in Accident Sequence 5.4, E04-NCSA-120 version 16 for the UNH (Uranal Nitrate Hydroxide) reprocessing Integrated Safety Analysis (ISA). This sequence is the transfer of UNH from uranium powder dissolver to the unfavorable geometry steam boiler when the loss of its heat source causes a vacuum in the steam boiler. Additionally this IROFS is used in Accident Sequence 7.5, E04-NCSA-190 version 10 for the UO2 pellet dissolution process. The IROFS prevents UNH to backflow into the unfavorable geometry steam boiler. The UO2 steam boiler was shut down at the time of the finding and remains shutdown. The other IROFS 3527 in these sequences remained available during the time. This was verified when performing the PM.</br>This determination was completed at 1055 PDT on 10/27/2013. The extent of condition to evaluate other potential uses of this type of vacuum breaker is underway. The safety significance is low as the independent IROFS 3527 was verified to be available and reliable via the testing. The system was shut down and remains shutdown for further evaluation, the failed vacuum breaker has been replaced and verified operable.</br>The licensee will notify Region II.rable.
The licensee will notify Region II. +
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00:00:00, 27 October 2013 +
SNM-1227 +
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14:16:00, 27 October 2013 +
-0.152 d (-3.65 hours, -0.0217 weeks, -0.005 months) +
17:55:00, 27 October 2013 +
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