05000424/LER-2003-002
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| 4242003002R00 - NRC Website | |
U.S. NUCLEAR REGULATORY COMMISSION FACILITY NAME 11) Vogtle Electric Generating Plant - Unit 1 � 05000-424 -`-TEXT ill mole space is requited. use addition& copies of NRC Foffn 366A) 117
A. REQUIREMENT FOR REPORT
This report is required per 10 CFR 50.73 (a)(2)(iv) because an unplanned actuation of an engineered safety feature (ESF) occurred when the main steam line isolation function was manually initiated.
B. UNIT STATUS AT TIME OF EVENT
At the time of this event, Unit I was in Mode 2 (Startup) at 2% of rated thermal power, coming out of a refueling outage.
C. DESCRIPTION OF EVENT
On October 22, 2003, personnel had entered both the North and South Main Steam Valve Rooms to vent the bonnet cavities and equalize pressure on either side of the main steam isolation valves (MSIVs) per procedure 13601-1, "Steam Generator and Main Steam System Operation." In the South Main Steam Valve Room (SMSVR), a high pressure hose was connected to piping outside of double isolation valves for the Loop 4 Train B MSIV drain line. The inside drain line isolation valve was fully opened, the outside drain line isolation valve was partially opened, and a rubber seal at the first hose coupling blew out. Steam exiting from this connection blocked the doorway to the room and also prevented the drain line isolation valves from being closed. Personnel phoned the control room and asked that the MSIV be closed. Due to the background noise, the Unit Shift Supervisor (USS) was unsure which loop was involved, but understood a steam leak was occurring. In addition, the USS knew that closing only the one valve would allow back leakage to occur. Therefore, at 0256 EDT, the USS ordered a manual main steam line isolation (MSL1) which closed all MSIVs and bypass steam isolation valves (BSIVs), and personnel safely exited the SMSVR.
After recovery from the MSL1, control room personnel opened the BSIVs to equalize the pressure around the MSIVs. Upon attempting to open the MSIVs, all opened successfully with the exception of the Loop 2 Train B MSIV. After bonnet pressure was reduced, this valve was also opened.
D. CAUSE OF EVENT
The cause of this event is that the hose couplings used were not rated for the steam pressure encountered in the valve bonnet.
a, DOCKET � LER NUMBER 16) � PAGE (3)
E. ANALYSIS OF EVENT
All MSIVs and BSIVs isolated as required and the MSLI occurred as designed when actuated. No personnel injuries occurred as a result of this event. Control room personnel responded appropriately to initiate the MSLI to protect personnel. Based on these considerations, there was no adverse effect on plant safety or on the health and safety of the public as a result of this event.
This event does not represent a safety system functional failure.
F. CORRECTIVE ACTIONS
Adequately rated hoses/hose couplings will be procured by February 20,2004, for future use when performing this evolution.
G. ADDITIONAL INFORMATION
1) Failed Components:
'A", 300 psi, hose coupling manufactured by Dixon Valve and Coupling Company, Part # PF16 (male) and Part # PHLI6 (female).
2) Previous Similar Events:
None 3) Energy Industry Identification System Code:
Main Steam System — SB