05000455/FIN-2015004-05
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Finding | |
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| Title | Licensee-Identified Violation |
| Description | On October 23, 2015, during a return to full power after power maneuvering on October 23, 2015, the Unit 2 axial offset (AO) exceeded the procedural limit of the reactivity maneuver guidance sheet (ReMA). AO is an indication used to ensure power distribution and fuel conditioning limits are properly maintained throughout the core during steady state conditions and when maneuvering the plant up or down in power. The Unit 2 reactor operator (NSO) was focused primarily on RCS temperature control, which had stabilized because the reactivity changes from power ascension and poison burnout were offset enough to stabilize temperature control, and did not recognize the AO trend was still becoming more negative. The operator was not monitoring all of the critical parameters specified in the ReMA and, as a result, the AO value dropped to - 4.3% and exceeding the 3% from a target value of -0.5% before the operator took action to correct it. Failure to operate within the procedurally specified limits was a performance deficiency. Technical Specification 5.4.1.a requires, in part, that written procedures be established and implemented covering the procedures recommended in Regulatory Guide 1.33, Revision 2, Appendix A, February 1978. 2BGP 100-3, POWER ASCENSION, states in step E.1.e, the rate of Reactor Power rise shall be limited per NF-AP-440 and refers the operator to the ReMA guidance. In step 5.3.4 of NF-AP-440, PWR FUEL CONDITIONING, operators are directed to maintain AO within 3% of target when increasing power above 75% of rated thermal power. The load following ReMA specified a target value of -0.5% for AO. Contrary to the TS 5.4.1.a requirements specified above, the operator did not implement the actions specified in procedures established for changing power and load following to control the key parameter within the specified control band. The operator identified that AO was outside the specified band and the crew immediately took action to restore AO to within the ReMA limits by withdrawing control rods. The issue was entered into CAP as IR 02575960, and the operating department implanted prompt action to communicate the cause of the error to all operators and qualified nuclear engineers. In addition, additional management observations of power maneuvering activities were put in place. The inspectors determined this issue was more than minor because the performance deficiency impacted the Human Performance attribute of the Barrier Integrity Cornerstone and adversely impacted the cornerstone objective to provide reasonable assurance that the physical design barrier (fuel cladding) protect the public from radionuclide releases caused by accidents or events. Specifically, failure to follow fuel conditioning guidelines to monitor and control key parameters while making reactivity changes could result in fuel clad damage and adversely impact nuclear safety. The inspectors determined that the issue was of very low safety significance (Green) because the axial offset was still within the bounding limits established and analyzed by the core operating limit report and no fuel damage occurred. |
| Site: | Byron  |
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| Report | IR 05000455/2015004 Section 4OA7 |
| Date counted | Dec 31, 2015 (2015Q4) |
| Type: | NCV: Green |
| cornerstone | Mitigating Systems |
| Identified by: | Licensee-identified |
| Inspection Procedure: | |
| Inspectors (proximate) | A Shaikh B Palagi C Thompson G Hansen J Cassidy J Draper J Jandovitz J Mcghee L Smith M Holmberg V Meghani |
| Violation of: | Technical Specification Technical Specification - Procedures |
| INPO aspect | |
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Finding - Byron - IR 05000455/2015004 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Byron) @ 2015Q4
Self-Identified List (Byron)
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