05000374/LER-2001-004

LER-2001-004,

Docket Number
Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2)(iv)(A), System Actuation
3742001004R00 - NRC Website

FACILITY NAME (1) LaSalle County Station, Unit 2 r:TOCKET (2) MOW PLANT AND SYSTEM Identification General Electric - Boiling Water Reactor, 3489 Megawatts Thermal Rated Core Power

A. CONDITION PRIOR TO EVENT

Unit(s): 2 Event Date: 09/07/01 Event Time: 0024 Reactor Mode(s): 1 Power Level(s): 075 Mode(s) Name: Run

E. DESCRIPTION OF EVENT

On September 7, 2001, at 0024 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, during power ascesion from a forced outage, at 75 percent power, LaSalle Unit 2 was manually scrammed due to 2 low pressure heater string isolations. LOA-HD-201 "Heater Preparation for Operation" requires a scram with 2 heater strings isolated. All systems operated as designed. There were no ECCS actuations or primary containment isolations. The lowest reactor water level reached was minus 20 inches. All control rods fully inserted.

The 21A and 21C low pressure heater drains were lined up to use the emergency heater drains instead of the normal heater drains. At high power levels the emergency heater drains can not pass the full condensate flow required. This caused the feedwater heaters to isolate when the high level trip set points were reached. The operating shift was continuing power ascension without these two heater level indication lines filled and vented.

C. CAUSE OF EVENT

The first root cause is that the current valves installed for the emergency heater drains on the 11/21 heaters could not pass 100 percent of the condensate generated when the heater strings were in cascade at 100% power.

The second root cause is the operating shift continued power ascension without heater drain level indication.

The third root cause is that the Control Room operators felt that the emergency drains could handle full flow., The fourth root cause is that the procedures used for the start up of the HD system allowed the 21A and 21C heater drains to be lined up in a manner that would cause high level alarms and HD string isolation when power increased above about 70% power.

D. SAFETY ANALYSIS

This scram was due to loss of feedwater flow at less than 100% power. This transient is bounded by loss of feedwater event even if the event occurred at 100% power.

FACILITY NAME HI

DOCKFT 191 lcR NUMBER (61 PAGE 131

• CORRECTIVE ACTIONS 1. Revisions were made to all associated procedures to insure that the heater drain valves are aligned properly for all reactor power conditions. (ATM# 75007) 2. A design modification will be made to install new valves for the 11/21 emergency drain valves to allow for 100% draining capability through these valves when the drains are in cascade. (ATM# 75007) 3. Training will be provided to all operating shifts to understand the limitations of the heater drain capacities and the potential for errors when increasing power without level indication. (ATM# 75007) ▪ PREVIOUS OCCURRENCES A review of Licensee Event Reports over the previous five years found no previous or similar occurrences.

▪ COMPONENT FAILURE DATA Since no component failure occurred, this section is not applicable.