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At approximately 2342 on 10/25/2006, while … At approximately 2342 on 10/25/2006, while performing maintenance on the solid state protection system in Mode 5 cold shutdown, Unit 2 received an automatic safety injection signal which resulted in all three ESF Diesel Generators starting and a containment ventilation isolation and containment phase A isolation. All safety injection pumps were in pull-to-lock per plant conditions so that the pumps did not start and no water was discharged into the reactor coolant system. As a result, the ESF Diesel Generators started but did not load as designed. The residual heat removal pumps were stripped from the ESF electrical busses due to the actuation. The first residual heat removal pump was restored within 4 minutes upon the loss of residual heat removal cooling and the second pump was restored within 6 minutes. The residual heat removal system heat exchangers were bypassed at the time of the event and the plant was being allowed to heat up.</br>The cause of the automatic safety injection signal was an inadvertent removal of the block for the low pressurizer pressure safety injection system during the maintenance. Therefore, the signal was a valid signal initiated in response to a parameter satisfying the requirements for initiation of the safety function of the system. </br>Although the actuation was the result of a valid signal, safety injection was not required in this Cold Shutdown Mode of Operation.</br>This notification is being made under 10CFR50.72(b)(3)(iv) as an event that results in valid actuation of any of the systems listed in paragraph (b)(3)(iv)(B) of this section.</br>This actuation was initially determined to be due to an invalid signal. Upon further review, it was determined at 1745 on 10/27/08 that the actuation was due of a valid signal.</br>The licensee notified the NRC Resident Inspector.ensee notified the NRC Resident Inspector. +
04:42:00, 26 October 2008 +
44,605 +
19:21:00, 27 October 2008 +
04:42:00, 26 October 2008 +
At approximately 2342 on 10/25/2006, while … At approximately 2342 on 10/25/2006, while performing maintenance on the solid state protection system in Mode 5 cold shutdown, Unit 2 received an automatic safety injection signal which resulted in all three ESF Diesel Generators starting and a containment ventilation isolation and containment phase A isolation. All safety injection pumps were in pull-to-lock per plant conditions so that the pumps did not start and no water was discharged into the reactor coolant system. As a result, the ESF Diesel Generators started but did not load as designed. The residual heat removal pumps were stripped from the ESF electrical busses due to the actuation. The first residual heat removal pump was restored within 4 minutes upon the loss of residual heat removal cooling and the second pump was restored within 6 minutes. The residual heat removal system heat exchangers were bypassed at the time of the event and the plant was being allowed to heat up.</br>The cause of the automatic safety injection signal was an inadvertent removal of the block for the low pressurizer pressure safety injection system during the maintenance. Therefore, the signal was a valid signal initiated in response to a parameter satisfying the requirements for initiation of the safety function of the system. </br>Although the actuation was the result of a valid signal, safety injection was not required in this Cold Shutdown Mode of Operation.</br>This notification is being made under 10CFR50.72(b)(3)(iv) as an event that results in valid actuation of any of the systems listed in paragraph (b)(3)(iv)(B) of this section.</br>This actuation was initially determined to be due to an invalid signal. Upon further review, it was determined at 1745 on 10/27/08 that the actuation was due of a valid signal.</br>The licensee notified the NRC Resident Inspector.ensee notified the NRC Resident Inspector. +
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00:00:00, 27 October 2008 +
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04:42:00, 26 October 2008 +
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