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The Waste Disposal System (WDS) Class 1 pi … The Waste Disposal System (WDS) Class 1 piping requires operable seismic supports downstream of the isolation valve class break. Currently, eight (8) INC (International Nuclear Safety, Corp.) snubbers have been degraded to (Non Nuclear System) NNS Class 4 ridged struts. The snubbers original design function was to allow thermal motion but restrain seismic motion. </br>The snubbers have been identified as potential to create an unanalyzed condition that over stresses the safety class 1 drain pipe upstream of the isolation valve if the snubbers on the drain pipe downstream of the isolation valve were in a locked condition (acting as a strut). Per NRC bulletin 81-01, these snubbers are assumed to be frozen and do not allow movement of the pipe; thus, they have been degraded to rigid struts as they are not in the snubber program and are not tested. They still provide a seismic safety function for (class) II/I issues and act as a strut to provide horizontal restraint to the WDS piping. </br> </br>The snubbers were removed from the piping system and tested to determine their performance and if they would have moved to allow thermal growth. Six snubbers failed the test and were either in a locked condition or their movement was dimensionally small relative to the required movement. The (Reactor Coolant System) RCS is within acceptable stress values with the snubbers removed.</br>The 8-hour regulatory reporting time has been exceeded.</br>An initial Reportability Evaluation was completed on March 26, 2012 and had determined the supports were operable. A second Reportability Evaluation later determined the supports have been inoperable since October 6, 2011. The WDS is used to drain the RCS.</br>The licensee will notify the NRC Resident Inspector.</br>* * * RETRACTION ON 9/26/12 AT 1949 EDT FROM ROBERT KROS TO DONG PARK * * *</br>Additional review and testing demonstrated that (there was) no degradation of the RCS from thermal fatigue. The analysis demonstrates adequate past performance of the snubbers with regard to thermal fatigue. The impact of the snubber has been analyzed and determined to have not resulted in an unanalyzed condition that significantly degraded plant safety. Therefore, this event is being retracted. The failure to retract this notification in a timely fashion has been entered into the corrective action system.</br>The licensee will notify the NRC Resident Inspector. Notified R4DO (Werner).sident Inspector. Notified R4DO (Werner).
18:44:00, 6 October 2011 +
47,848 +
18:53:00, 18 April 2012 +
18:44:00, 6 October 2011 +
The Waste Disposal System (WDS) Class 1 pi … The Waste Disposal System (WDS) Class 1 piping requires operable seismic supports downstream of the isolation valve class break. Currently, eight (8) INC (International Nuclear Safety, Corp.) snubbers have been degraded to (Non Nuclear System) NNS Class 4 ridged struts. The snubbers original design function was to allow thermal motion but restrain seismic motion. </br>The snubbers have been identified as potential to create an unanalyzed condition that over stresses the safety class 1 drain pipe upstream of the isolation valve if the snubbers on the drain pipe downstream of the isolation valve were in a locked condition (acting as a strut). Per NRC bulletin 81-01, these snubbers are assumed to be frozen and do not allow movement of the pipe; thus, they have been degraded to rigid struts as they are not in the snubber program and are not tested. They still provide a seismic safety function for (class) II/I issues and act as a strut to provide horizontal restraint to the WDS piping. </br> </br>The snubbers were removed from the piping system and tested to determine their performance and if they would have moved to allow thermal growth. Six snubbers failed the test and were either in a locked condition or their movement was dimensionally small relative to the required movement. The (Reactor Coolant System) RCS is within acceptable stress values with the snubbers removed.</br>The 8-hour regulatory reporting time has been exceeded.</br>An initial Reportability Evaluation was completed on March 26, 2012 and had determined the supports were operable. A second Reportability Evaluation later determined the supports have been inoperable since October 6, 2011. The WDS is used to drain the RCS.</br>The licensee will notify the NRC Resident Inspector.</br>* * * RETRACTION ON 9/26/12 AT 1949 EDT FROM ROBERT KROS TO DONG PARK * * *</br>Additional review and testing demonstrated that (there was) no degradation of the RCS from thermal fatigue. The analysis demonstrates adequate past performance of the snubbers with regard to thermal fatigue. The impact of the snubber has been analyzed and determined to have not resulted in an unanalyzed condition that significantly degraded plant safety. Therefore, this event is being retracted. The failure to retract this notification in a timely fashion has been entered into the corrective action system.</br>The licensee will notify the NRC Resident Inspector. Notified R4DO (Werner).sident Inspector. Notified R4DO (Werner).
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00:00:00, 26 September 2012 +
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195.006 d (4,680.15 hours, 27.858 weeks, 6.411 months) +
18:44:00, 6 October 2011 +
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