Morning Report for August 26, 2004

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Part 21 - 2004-0019-00 - Narrow Range Water Level Instrument Level 3 Trip


WILMINGTON, North Carolina

License No:

MR Number: H-2004-0016
Date: 08/16/2004

Reviewer: Vern Hodge


Part 21 - 2004-0019-00 - Narrow Range Water Level Instrument Level 3 Trip

On August 16, 2004, General Electric Nuclear Energy (GENE), a vendor of boiling water reactors, reported a potential issue with the Level 3 trip from the narrow range reactor water level instruments that initiate reactor scram. GENE states that if reactor water level drops below the dryer seal skirt, a conservative evaluation indicates that water level instruments may indicate high by as much as 8 inches.

GENE states that if water level were to drop below the variable leg tap without generating a Level 3 trip, it could lead to the water level falling below the top-of-active fuel (TAF) for transients. However, it would not lead to a significant safety hazard due to the multiple automatic and passive protection features of a BWR.

GENE has completed analyses for BWR-2 and BWR-3 plants and determined that these plants do not have a narrow range instrument tap and that the wide range instrument tap is at an elevation far below the dryer skirt. Thus this condition can not occur at these plants.

GENE has not completed the analyses for BWR-4, BWR-5, or BWR-6 plants and has not determined if water level could drop below the narrow range variable leg tap prior to reaching the Level 3 trip setpoint. These plants are being notified of this situation by a GENE Safety Communication letter. GENE is committed to complete the evaluation by October 11, 2004. The affected domestic nuclear power plants are: Clinton, Brunswick Units 1 & 2, Nine Mile Point Unit 2, Fermi Unit 2, Columbia, Fitzpatrick, Grand Gulf, River Bend, La Salle Units 1 & 2, Limerick Units 1 & 2, Peach Bottom Units 1 & 2, Perry, Cooper, Duane Arnold, Susquehanna Units 1 & 2, Hope Creek, Hatch Units 1 & 2, Browns Ferry Units 1 (plant in extended shutdown), 2 & 3.

GENE also informed NRC that it has communicated this matter to foreign GENE-designed BWR plants.

Information for this issue as well as other Part 21s is available at the NRC's Operating Experience web page at:


Name Office Abbrev Phone No E-Mail
HODGE, VERNON NRR (301) 415-1861

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