05000333/FIN-2011003-02
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Finding | |
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| Title | Source Range Monitor Operability Requirements during Core Alterations |
| Description | The inspectors identified an unresolved item (URl) associated with the adequacy of Entergy\\\'s bases for a change to the definition of core quadrant as applied to refueling operations that was implemented by the Entergy staff at FitzPatrick in 2004. The inspectors noted that TS Bases 3.3.1.2, Source Range Monitor (SRM) Instrumentation, documented that the primary indication of refueling, shutdown, and low power operations neutron flux levels is provided by the SRMs or special movable detectors connected to the SRM circuits. The SRMs provide monitoring of reactivity changes during fuel or control rod movement and give the control room operators early indication of unexpected subcritical multiplication. The inspectors further noted that the TS Bases documented that the SRMs have no safety function and are not assumed to function during any UFSAR design basis accident or transient analysis. However, the TS Bases describe that the SRMs provide the only on-scale monitoring of neutron flux levels during startup and refueling. The reactor core at FitzPatrick consists of 560 fuel assemblies, arranged symmetrically in an octagonal configuration. Due to this symmetry, the core can be divided into four equal quadrants, using two perpendicular axes (000-180\\\', and 090-270) that cross at the geometric center of the core. The reactor core also contains four installed SRMs, with one in each of the quadrants as described above. The inspectors reviewed station procedures and supporting documentation to evaluate whether the definition of a core quadrant, as defined in FitzPatrick station procedures, was consistent with the intent of TS 3.3.1.2. The core quadrant definition as currently implemented by station personnel indicated that the placement of the axes for a core quadrant was based on the SRM locations. This orientation resulted in quadrant axes that are rotated approximately 18 clockwise from the arrangement that was described above, and resulted in quadrant boundaries that bisect individual fuel assemblies. Entergy personnel determined that such fuel assemblies could be considered to reside in either of the adjacent quadrants. Entergy personnel used this concept to establish two quadrant boundaries, one rotated clockwise by 16\\\' and the other rotated clockwise by 20\\\', such that the SRM would partially reside in both quadrants using either boundary. This created a set of fuel assemblies along a quadrant boundary that could be considered to be a part of either of the adjacent quadrants. Entergy personnel determined that, by selecting the appropriate boundary in the case that a single SRM is inoperable, this quadrant arrangement supported the requirement of TS SR 3.3.1.2.2, while allowing movement of fuel anywhere in the core. The inspectors verified that TS 3.3.1.2 and its associated TS Bases do not provide a description or explicit definition of what is considered a core quadrant. However, the inspectors noted that, as a result of the station\\\'s interpretation, an SRM would be expected to detect reactivity changes that occurred at greater distances from the detector than it would using the 000-180\\\', 090-270\\\' quadrant definition, and therefore, that the approach implemented in 2004 may not be consistent with the current licensing and design bases. The inspectors reviewed the SRM vendor document that was referenced by FitzPatrick personnel as support for the 2004 definition of core quadrant. The inspectors\\\' review determined that the vendor document did not appear to be analytically based to support the definition of core quadrant as implemented by FitzPatrick staff in procedure changes made in 2004. Based on the above information, the inspectors determined that further NRC evaluation is needed to assess the analyses and licensee regulatory screening reviews to support the rotated core quadrants approach to TS requirements for SRM operability during core alterations, and therefore, to determine whether a performance deficiency exists with regards to Entergy\\\'s application of the rotated core quadrant boundary approach. lt should be noted that the inspectors\\\' sampling review in the course of inspection during the 2010 refueling outage did not identify a core alteration from a core quadrant with an inoperable SRM using the standard core quadrant definition (symmetrical, four equal quadrants). (URl 05000333/201 1003-02, Source Range Monitor Operability Requirements during Core Alterations) |
| Site: | FitzPatrick  |
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| Report | IR 05000333/2011003 Section 4OA5 |
| Date counted | Jun 30, 2011 (2011Q2) |
| Type: | URI: |
| cornerstone | Mitigating Systems |
| Identified by: | NRC identified |
| Inspection Procedure: | |
| Inspectors (proximate) | G Meyer S Rutenkroger J Noggle T Fish E Knutson D Robertss Mccarverj Laughlin E Knutson B Sienel A Burritt E Miller |
| INPO aspect | |
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Finding - FitzPatrick - IR 05000333/2011003 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (FitzPatrick) @ 2011Q2
Self-Identified List (FitzPatrick)
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