fuel channels

272 Pages·2008·4.36 MB·English

Fuel Performance Meeting
April 8-9, 2008
Lynchburg, VA
AREVA NP Inc.
AREVA NP INC. Fuel Performance Meeting Slides –April 8, 2008 2
Meeting Agenda
> Introductions
> NRC Notification – Letter Objectives
(cid:138) Describe events and current status
• Description of occurrence of fuel rod bow at North Anna
• Definition of actions taken
(cid:138) Provide Apparent Cause Analysis overview
• Technical and programmatic causal factors
• Extent of condition
(cid:138) Provide overview of governing topical
(cid:138) Discuss potential problem (difference between occurrence
and topical)
(cid:138) Action Plan Overview/Status
> Preliminary water channel measurements – North Anna 1
> Summary
> Q&A
AREVA NP INC. Fuel Performance Meeting Slides –April 8, 2008 3
Description of Fuel Rod Bow
Occurrence History of Events
AREVA NP INC. Fuel Performance Meeting Slides –April 8, 2008 4
Rod Bow
> Alters design pitch dimensions, or water
channel gap, between adjacent rods within a
Advanced Mark-BW fuel assembly array
which affects:
> Local nuclear power peaking
> Local heat transfer to coolant
> Consequence
(cid:206) local excessive over-heating
of fuel rod cladding which may lead to failure
AREVA NP INC. Fuel Performance Meeting Slides –April 8, 2008 5
Rod Bow Occurrence
AREVA NP INC. Fuel Performance Meeting Slides –April 8, 2008 6
Advanced Mark-BW
3 Leaf Holddown Spring
Fuel Assembly
Asssembly (Inconel)
Top Nozzle
Fixed Top End Grid
(Inconel) M5TM Guide Thimbles
3 Mid-Span Mixing Grids
M5TM
5 Floating Vaned
Intermediate Grids
M5TM
Lower 3 spans observed
with elevated rod bow
M5TM Fuel Rod
Floating Vaneless
Cladding
Intermediate Grid M5TM
Fixed Bottom End
Grid (Inconel)
Coarse Mesh Debris Filter
Seated Fuel
Bottom Nozzle
Rods
AREVA NP INC. Fuel Performance Meeting Slides –April 8, 2008 7
North Anna Unit 2 EOC 18 Fuel Rod Bow
AREVA NP INC. Fuel Performance Meeting Slides –April 8, 2008 8
AREVA NP INC. Fuel Performance Meeting Slides –April 8, 2008 9
AREVA NP INC. Fuel Performance Meeting Slides –April 8, 2008 10