05000390/FIN-2012005-01
From kanterella
Jump to navigation
Jump to search
Finding | |
|---|---|
| Title | Engineering Justification for Design of Control Building Watertight Hatches |
| Description | The inspectors reviewed Final Safety Analysis Report (FSAR), Section 3.8.4.1.1, which requires the two equipment hatches at elevation 708.0 in the control building to be watertight. Design Criteria WB-DC-20-21, Miscellaneous Steel Components for Category I Structures, Revision 13, covers the requirements for the equipment and, according to TVA Drawing 48N1306, the hatches are designed to be watertight. Drawing 48N1306 notes: 9. Seals and gaskets by Heavy Equipment Group, and 13. Gaskets shall be affixed to cover plates with waterproof cement or equal to assure that they remain attached to covers when covers removed. There is no information on the drawing regarding the material specifications of the gaskets, only the thickness: 1/8 gasket. Design Criteria Document WB-DC-40-60, Special Hatches and Manways, Revision 6, Section 3.12.2.2, states that the hatches must withstand a pressure of 1.3 psi from topside (water to El. 711.0 due to a turbine building flood resulting from a rupture in the CCW system). Service Request (SR) 427917 (initiated September 5, 2011) reported Water leaking down into the EBR Chiller Room Water leaking through the equipment hatch (WBN-2-EQH-271-0008) seals and dripping down into the EBR Chiller room and pooling in front of the door. Repair/replace leaking hatch seals and the seals around the coffer dam. The source of water appears to be from rain water entering the TB around the Steam & Feed line penetrations in the NE corner elevation 729 Unit-2 side. Cover/close/or seal these penetrations to prevent rain water from entering TB. This SR was closed to WO 112678945 and the WO was cancelled on May 9, 2012. It is unlikely that the hatches are capable of being watertight at a pressure of 1.3 psi from topside (water to El. 711.0) if they leak rain water from the 708.0 El. floor. Calculation WCG-1-1591, Seismic Evaluation of Watertight Equipment Hatches in Control Building at El. 708.0, provides some evaluation of structural elements of the hatches. This calculation does not provide any evaluation of the shear stress in the connecting screws due to hatch deflection/elastic deformation nor does the calculation evaluate the design adequacy of the mounting frame attached to the concrete opening under a live load (22,500 lbs.). Pending additional information from the licensee which can verify that there was adequate engineering justification for the design of floor hatches (WBN-1-EQH-271-0008 and WBN-2-EQH-271-0008) in the 708.0 El. of the control/turbine building, this item is identified as unresolved item (URI) 050000390/2012005-01, Engineering Justification for Design of Control Building Watertight Hatches. |
| Site: | Watts Bar  |
|---|---|
| Report | IR 05000390/2012005 Section 1R06 |
| Date counted | Dec 31, 2012 (2012Q4) |
| Type: | URI: |
| cornerstone | Mitigating Systems |
| Identified by: | NRC identified |
| Inspection Procedure: | IP 71111.06 |
| Inspectors (proximate) | J Bartley K Miller R Monkj Bartleyj Laughlin K Miller R Monkd Faillae Patterson J Hamman K Miller M Speck R Baldwin R Lanyi R Monk S Shaeffer |
| INPO aspect | |
| ' | |
Finding - Watts Bar - IR 05000390/2012005 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Finding List (Watts Bar) @ 2012Q4
Self-Identified List (Watts Bar)
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||