05000327/FIN-2011005-02
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Finding | |
|---|---|
| Title | Failure to Maintain Thermal Power Less Than Licensed Limit |
| Description | The inspectors identified a non-cited violation of Unit 1 Operating License DPR-77 Condition 2. (C).1 Maximum Power Level for the licensees failure to take prudent action to ensure that the licensed power limit was not exceeded during a pre-planned evolution which involved manual reactivity manipulations. Prompt action was not taken by operators to reduce power when reactor thermal power exceeded the licensed power limit during a control rod full out position reset activity. Additionally, prudent action to sufficiently reduce power prior to the activity to accommodate the power transient was not taken. This issue was entered into the licensees corrective action program as PER 437068. The finding was determined to be greater than minor because it was sufficiently similar to example 8.a. of IMC 0612 Appendix E, in that: 1) prudent action based on prior performance was not taken to reduce power prior to performing the evolution, and 2) operators did not promptly lower thermal power once the licensed limit was exceeded. Additionally, if left uncorrected the finding would have the potential to lead to a more significant safety concern, since operation above the licensed power limit has the potential to reduce analyzed margins to fuel cladding damage. Using IMC 0609, Significance Determination Process, Attachment 4, Phase 1 - Initial Screening and Characterization of Findings, the finding was determined to be of very low safety significance (Green) under the barrier integrity cornerstone since only the fuel cladding barrier criterion was applicable. The cause of this finding was determined to have a cross-cutting aspect in the area of Human Performance associated with the Decision-Making component. Elements of non-conservative decision making which contributed to this performance deficiency included: (1) Prior to February 2011, station procedures required operators to monitor and maintain the 10-minute average of thermal power below the licensed limit. These requirements were revised and replaced with requirements to maintain the 1-hour average of thermal power below the licensed limit. This was a non-conservative decision made without due consideration of potential consequences or the need for supplemental guidance to maintain an appropriate and conservative approach to controlling thermal power under non-steady state conditions. (2) The decision was made to proceed with the rod withdrawal activity under the non-conservative assumption that there would be negligible reactivity effects, and without considering available data from previous performances. This did not reflect a philosophy of demonstrating that a proposed activity is safe in order to proceed rather than demonstrating that it is unsafe in order to disapprove the action. |
| Site: | Sequoyah  |
|---|---|
| Report | IR 05000327/2011005 Section 4OA2 |
| Date counted | Dec 31, 2011 (2011Q4) |
| Type: | NCV: Green |
| cornerstone | Barrier Integrity |
| Identified by: | NRC identified |
| Inspection Procedure: | IP 71152 |
| Inspectors (proximate) | S Shaeffer C Young M Speck R Baldwin J Hamman W Deschaine |
| CCA | H.14, Conservative Bias |
| INPO aspect | DM.2 |
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Finding - Sequoyah - IR 05000327/2011005 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Sequoyah) @ 2011Q4
Self-Identified List (Sequoyah)
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