Outline Of Pwr Mox Fuel Assembly

All fuel rods within a PWR MOX fuel assembly are made of MOX, with the distribution of Pu content of fuel rod to reduce local power peaking at the periphery of the assembly. An example of 17 x 17 type fuel is shown in Fig. 1.

The average Pu fissile content of MOX fuel assembly is designed so that the reactivity of MOX fuel is equivalent to that of current standard U02 fuel for Japanese PWR's whose enrichment is 4. lwt%. Typical plutonium fissile and total content as a function of fissile isotope fraction is shown in Fig.2. The Pu fissile content is evaluated approximately 6wt% for the Pu isotopic composition described in Fig.2, which is considered typical of Pu recovered from PWR spent fuel. Maximum assembly average burnup of U02 fuel is 48GWd/t, while that of MOX fuel assembly is designed lower to be 45GWd/t. It is due to large peak to average burnup ratio in MOX fuel assembly.

The other structure of MOX fuel assembly is almost same as that of U02 fuel assembly to be compatible with U02 fuel assemblies in the core. And also, from a view point of keeping reliability as

US

m

4

*

*

*

m

s

m

4

*

*

*

m

-

X

X

X

+

X

X

X

X

X

X

X

*

X

X

Xj

X

X

X

X

X

X

X

*

X

X

X

X

X

m

*

m

m

*

+

*

*

if

imi

[ [ High Pu Content p%(j Instrumentation Thinble

Med ¡am Pu Content fXl Cotrol Rod Gude Thimble

Low Pu Content

FIG. 1. Pu Content Distribution in PWR MOX Fuel Assembly

OJ 03 CO

"1

1 -

\Pu Content

-

\Pu-fissle Content

__

Typical Pu Isotopic Compositon

Pu-238 — 1.9wtX

Pu-239 — 57. 5wtX

Pu-240 — 23. 3wtX

— -

Pu-241 — 10. OwtX

=

Pu-242 — 5.4wt%

Am-241 — 1.9wtX

-

(67. 5X)

. i

»

Was this article helpful?

0 0

Post a comment