05000305/LER-2006-003

LER-2006-003,

Docket Number
Event date:	05-05-2006
Report date:	07-05-2006
Reporting criterion:	10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications 10 CFR 50.73(a)(2)(v)(B), Loss of Safety Function - Remove Residual Heat
Initial Reporting
ENS 42557	10 CFR 50.72(b)(3)(v)(B), Loss of Safety Function - Remove Residual Heat
3052006003R00 - NRC Website

FACILITY NAME (1) DOCKET NUMBER (2) LER NUMBER (6 PAGE (3)

Event Description:

On May 5, 2006 at 1600 CST in intermediate shutdown, the Kewaunee Power Station declared both trains of the residual heat removal (RHR) system inoperable due to internal flooding vulnerability caused by the possibility of non-seismically qualified pipe [PSP] breaks during a seismic event. The RHR pumps [P] are not protected from non-seismically qualified pipe breaks in the auxiliary building. The specific design criteria is stated in the Updated Safety Analysis Report Section B.5 'Protection of Class I Items' and states that "Class I items are protected against damage from Rupture of a pipe or tank [TK] resulting in serious flooding or excessive steam release to the extent that the Class I function is impaired." The two RHR trains are not separated in a manner that would prevent simultaneous damage to both trains from a failure of a non­ seismically qualified pipe.

The RHR pumps were declared inoperable when Kewaunee Power Station received the results of a Task Interface Agreement (TIA) from the Nuclear Regulatory Commission office of Nuclear Reactor Regulation titled, "Final Response to Task Interface Agreement 2005-10 Relating to Impact of Flooding on Residual Heat Removal (RHR) Pumps at Kewaunee Power Station (Task Interface Agreement (TIA) 2005-10)(TAC No.

MC8937)." Dominion Energy Kewaunee (DEK) continues to assess this TIA to determine its applicability.

This event was reported under Event Number 42557 in accordance with 10CFR50.72(b)(3)(v)(B), "Any event that at the time of discovery could have prevented the fulfillment of the safety function of systems that are needed to remove residual heat.

Event Analysis and Safety Significance:

This is being reported in accordance with 10 CFR 50.73(a)(2)(v)(B), "Any event or condition that could have prevented the fulfillment of the safety function of structures or systems that are needed to remove residual heat" and 10 CFR 50.73(a)(2)(i)(B), "Any operation or condition which was prohibited by the plant's Technical Specifications.

The station was in intermediate shutdown (average reactor coolant temperature greater than 200 degrees and less than 540 degrees Fahrenheit and zero percent fission power) when the condition was identified. Although both trains of residual heat removal pumps were inoperable, the Technical Specification requirement for decay heat removal capability was being met with two steam generators operable to remove decay heat.

The safety significance of this event is being assessed. DEK is continuing to review the TIA to determine its applicability to the station's design basis.

This is being reported as a safety system functional failure as an event or condition that could have prevented the fulfillment of the safety function of structures or systems needed to remove residual heat.

Cause:

When the results of the review of the TIA are completed this LER will be updated.

FACILITY NAME (1) DOCKET NUMBER (2)� LER NUMBER (6 PAGE (3)

Corrective Actions:

1. A design change was completed to install residual heat removal pump flood barriers.

2. DEK is continuing to review the TIA to determine its applicability to the station's design basis.

Similar Events:

Inadequate Design.