10 CFR 50.65 (a)(4) requires that before performing maintenance activities (including but not limited to surveillance, post-maintenance testing, and corrective and preventative maintenance), the licensee shall assess and manage the increase in risk that may result from the proposed maintenance activity. Contrary to this on September 26, 2009, with the unit in mode six the licensee inadvertently isolated the only boration flowpath by danger tagging and isolating power to 1HV8835, safety injection to the
RCS cold legs. This resulted in an unplanned Outage Risk Assessment Monitoring (ORAM) RED condition for reactivity control. This condition lasted for approximately
36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> before being discovered by operators performing an outage risk assessment. Licensee immediately suspended all
core alterations and restored the boration flowpath by manually opening 1HV8835. This finding is of very low safety significance due to the fact that the reactor cavity was completely flooded with 2600 ppm borated water from the refueling water storage tank when the issue was recognized. Licensee has documented this event in condition report 2009109416
