05000263/FIN-2013004-03
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Finding | |
|---|---|
| Title | Loss of Accurate Level Indication During Partial RCS Drain Down |
| Description | A self-revealed finding of very low safety significance and non-cited violation of Technical Specification (TS) 5.4.1.a, Procedures, occurred on June 3, 2013, due to the licensees failure to implement procedures regarding maintenance or operations activities for draining and refilling the reactor vessel. Specifically, the licensee failed to follow Step 10 of Operations Manual B.02.02-05, Reactor Water Cleanup System Operation, Section G.1, Reactor Vessel Draining during Cold Shutdown Conditions, to adequately monitor water levels in the reactor during the reactor pressure vessel (RPV) partial draining process. While relying on a temporary installed level instrument, operators performed an RPV drain down which introduced pressure related inaccuracies into the temporary instrument and prevented operators from adequately monitoring vessel level. This resulted in a loss of positive configuration control of reactor coolant system (RCS) level during an infrequently conducted risk-significant evolution, and for four days thereafter. Corrective actions included transferring from the temporary level instrument to the flood up level instrument and enhancing RPV reassembly and temporary vessel installation procedures. This issue is more than minor because it is associated with the configuration control shutdown equipment lineup attribute of the Initiating Events Cornerstone and impacted the cornerstone objective to limit the likelihood of those events that challenge critical safety functions during shutdown operations. In addition, if left uncorrected, the reliance on inaccurate RPV level instrumentation could lead to a more significant safety issue because it constitutes a loss of positive control of reactor vessel level during a risk significant RCS drain down. Using IMC 0609, Appendix G, for shutdown operations, the inspectors determined that the finding had very low safety significance because it did not represent an inadvertent loss of two feet of RCS inventory or inadvertent RCS pressurization, and it did not adversely affect core heat removal, inventory control, power availability, containment control, or reactivity guidelines. The inspectors determined that this finding was cross-cutting in the Human Performance, decision making area, and involved aspects associated with using conservative assumptions in decision making and adopting a requirement to demonstrate that the proposed action is safe in order to proceed rather than a requirement to demonstrate that it is unsafe. |
| Site: | Monticello  |
|---|---|
| Report | IR 05000263/2013004 Section 4OA2 |
| Date counted | Sep 30, 2013 (2013Q3) |
| Type: | NCV: Green |
| cornerstone | Initiating Events |
| Identified by: | Self-revealing |
| Inspection Procedure: | IP 71152 |
| Inspectors (proximate) | A Dunlop K Riemer T Bilik C Brown K Stoedter P Voss J Corujo-Sandin S Bell D Oliver M Ziolkowski |
| Violation of: | Technical Specification - Procedures Technical Specification |
| CCA | H.14, Conservative Bias |
| INPO aspect | DM.2 |
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Finding - Monticello - IR 05000263/2013004 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Monticello) @ 2013Q3
Self-Identified List (Monticello)
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