Note: Descriptions are shown in the official language in which they were submitted.
CA 02708902 2013-04-09
CANDU FUEL BUNDLE LOADED WITH BURNABLE ABSORBER
BACKGROUND OF THE INVENTION
Field of the Invention
The present invention relates to a CANDU (CANada
Deuterium Uranium) fuel bundle loaded with a burnable
absorber, wherein the fuel bundle which is suitable for use in a
CANDU reactor loaded with fuel having an enrichment of 0.7 ¨
3.0 wt% and in which a plurality of fuel rods is arranged in
concentric rings around a center rod is configured so as to have
a negative power coefficient, thereby ensuring inherent safety of
the reactor.
Description of the Related Art
In reactors, the power coefficient (PC) is defined as the
reactivity change which depends on an increase in unit power,
1
CA 02708902 2010-06-30
=
and is an important core physics parameter that dominates the
inherent safety of the reactor.
The power coefficient mainly results from a combination
of the fuel temperature coefficient (FTC) and the coolant
temperature coefficient (CTC). As
such, a negative power
coefficient indicates that the reactivity decreases in
proportion to an increase in power, and a positive power
coefficient indicates that the reactivity increases in
proportion to an increase in power and thus the reactor could
be unstable.
Hence, all reactors should have a negative power
coefficient of an appropriate level in order to ensure
inherent safety. In
the case of CANDU reactors which are
currently available, because the coolant temperature
coefficient is innately positive, the fuel temperature
coefficient should be controlled to be negative while lowering
the coolant temperature coefficient so as to attain the
negative power coefficient.
FIG. 10 schematically shows a conventional 37-rod fuel
bundle, and FIG. 11 schematically shows a conventional 43-rod
fuel bundle.
The fuel used in the CANDU reactor may be the 37-rod fuel
bundle 2 as shown in FIG. 10 or the 43-rod fuel bundle 3 as
shown in FIG. 11, in which a plurality of fuel rods is
arranged in concentric rings around a center rod.
2
CA 02708902 2010-06-30
SUMMARY OF THE INVENTION
Accordingly, the present invention has been made keeping
in mind the problems encountered in the related art and the
present invention is intended to provide a CANDU fuel bundle
loaded with a burnable absorber, wherein the fuel bundle,
which is suitable for use in a CANDU reactor loaded with fuel
having an enrichment of 0.7 - 3.0 wt% and in which a plurality
of fuel rods is arranged in concentric rings around a center
rod, includes the burnable absorber so as to have a negative
power coefficient, thereby improving inherent safety of the
reactor.
A first aspect of the present invention provides a CANDU
fuel bundle loaded with a burnable absorber, the CANDU fuel
bundle including a center rod disposed at its center and
including a burnable absorber and fuel, which are
homogeneously mixed together, and a plurality of fuel rods
arranged in concentric rings around the center rod.
In this aspect, the burnable absorber may be erbium,
erbia (Er203) or erbium carbide (Er2C3).
In this aspect, the burnable absorber may be at a
concentration of 100 wt% or less.
A second aspect of the present invention provides a
CANDU fuel bundle loaded with a burnable absorber, the CANDU
3
CA 02708902 2010-06-30
'
fuel bundle including a center rod disposed at its center and
including a burnable absorber and fuel, which are
homogeneously mixed together, and a plurality of fuel rods
arranged in concentric rings around the center rod, among
which fuel rods arranged in the closest concentric ring to the
center rod include a burnable absorber and fuel, which are
homogeneously mixed together. As such, the burnable absorber
may be erbium, erbia (Er203) or erbium carbide (Er2C3)=
In this aspect, the burnable absorber mixed in the
center rod, and the burnable absorber mixed in the fuel rods
arranged in the closest concentric ring to the center rod,
each of which is mixed with the fuel, may be at the same
concentration. As
such, the burnable absorber may be at a
concentration of 100 wt% or less.
In this aspect, the burnable absorber mixed in the
center rod, and the burnable absorber mixed in the fuel rods
arranged in the closest concentric ring to the center rod,
each of which is mixed with the fuel, may be at different
concentrations. As such, the burnable absorber mixed in the
center rod may be at a concentration of 100 wt% or less, and
the burnable absorber mixed in the fuel rods arranged in the
closest concentric ring to the center rod may be at a
concentration of 100 wt% or less.
A third aspect of the present invention provides a CANDU
fuel bundle loaded with a burnable absorber, the CANDU fuel
4
CA 02708902 2010-06-30
bundle including a center rod disposed at its center and
including a core portion including a burnable absorber and a
cylindrical sheath portion including fuel, and a plurality of
fuel rods arranged in concentric rings around the center rod.
As such, the burnable absorber may be erbium, erbia (Er203) or
erbium carbide (Er2C3).
In this aspect, the radius of the burnable absorber may
be equal to or less than the radius of the fuel rods.
A fourth aspect of the present invention provides a CANDU
fuel bundle loaded with a burnable absorber, the CANDU fuel
bundle including a center rod disposed at its center and
including a core portion including a burnable absorber and a
cylindrical sheath portion including the burnable absorber and
fuel, which are homogeneously mixed together, and a plurality
of fuel rods arranged in concentric rings around the center
rod. As
such, the burnable absorber may be erbium, erbia
(Er203) or erbium carbide (Er2C3). The burnable absorber may be
at a concentration of 100 wt% or less, and the radius of the
burnable absorber may be equal to or less than the radius of
the fuel rods.
BRIEF DESCRIPTION OF THE DRAWINGS
The features and advantages of the present invention will
be more clearly understood from the following detailed
5
CA 02708902 2010-06-30
description taken in conjunction with the accompanying
drawings, in which:
FIG. 1 schematically shows a CANDU fuel bundle loaded
with a burnable absorber, according to a first embodiment of
the present invention;
FIGS. 2A to 2F show changes in the power coefficient at
medium burnup of the CANDU fuel bundle loaded with the
burnable absorber according to the first embodiment of the
present invention;
FIG. 3 schematically shows a CANDU fuel bundle loaded
with a burnable absorber, according to a second embodiment of
the present invention;
FIGS. 4A to 4F show changes in the power coefficient at
medium burnup when the burnable absorber is used at the same
concentration in the CANDU fuel bundle loaded with the
burnable absorber according to the second embodiment of the
present invention;
FIGS. 5A and 5B show changes in the power coefficient at
medium burnup when the burnable absorber is used at different
concentrations in the CANDU fuel bundle loaded with the
burnable absorber according to the second embodiment of the
present invention;
FIG. 6 schematically shows a CANDU fuel bundle loaded
with a burnable absorber, according to a third embodiment of
the present invention;
6
CA 02708902 2010-06-30
FIGS. 7A to 71 show changes in the power coefficient at
medium burnup of the CANDU fuel bundle loaded with erbium,
erbia (Er203) or erbium carbide (Er203) that is the burnable
absorber, according to the third embodiment of the present
invention;
FIG. 8 schematically shows a CANDU fuel bundle loaded
with a burnable absorber, according to a fourth embodiment of
the present invention;
FIGS. 9A and 9B show changes in the power coefficient at
W medium burnup of the CANDU fuel bundle loaded with the
burnable absorber, according to the fourth embodiment of the
present invention;
FIG. 10 schematically shows a conventional 37-rod fuel
bundle loaded with natural U; and
FIG. 11 schematically shows a conventional 43-rod fuel
bundle loaded with natural U, recycled U and low-enriched U.
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a detailed description will be given of
embodiments of the present invention. Throughout the drawings,
the same reference numerals refer to the same or similar
elements, and redundant descriptions are omitted. Also in the
description, in the case where known techniques pertaining to
the present invention are regarded as unnecessary because they
7
CA 02708902 2010-06-30
would make the characteristics of the invention unclear and
also for the sake of description, the detailed descriptions
thereof may be omitted.
FIG. 1 schematically shows a CANDU fuel bundle loaded
with a burnable absorber, according to a first embodiment of
the present invention.
As shown in FIG. 1, the CANDU fuel bundle loaded with the
burnable absorber, according to the first embodiment of the
present invention, includes a center rod 100 and a plurality
W of fuel rods 200 arranged in concentric rings around the
center rod 100.
The center rod 100, which is disposed at the center of
the fuel bundle 1, may include a burnable absorber and fuel,
which are homogeneously mixed together.
As such, the burnable absorber may be erbium (Er), erbia
(Er203) or erbium carbide (Er2C3), and may be at a
concentration of 100 wt% or less.
Meanwhile, the evaluation of the power coefficient may
include lattice calculation using two-dimensional codes and
core calculation using three-dimensional codes.
In the present invention, lattice calculation is carried
out using the HELIOS-1.8 code developed by Studsvik Scanpower,
and the library used is a nuclear cross-section library based
on ENDF/B-VI in 190 neutron groups.
FIGS. 2A to 2F show changes in the power coefficient at
8
,
CA 02708902 2010-06-30
medium burnup of the CANDU fuel bundle loaded with the
burnable absorber according to the first embodiment of the
present invention.
As such, in a 43-rod fuel bundle which is a type of fuel
bundle that is loadable into a CANDU reactor loaded with fuel
having an enrichment of 0.7 wt%, 1.0 wt% or 3.0 wt%, when Er203
or Er2C3 that is the burnable absorber is homogeneously mixed
with the fuel in the center rod 100, changes in the power
coefficient are evaluated.
<TEST EXAMPLE 1-1>
The power coefficient at medium burnup depending on the
amount of Er203 mixed with fuel having an enrichment of 0.7 wt%
is depicted in FIG. 2A.
Specifically, the power coefficient in the absence of the
burnable absorber at 102.5% power is 0.0126 mk/% power, and
the estimated discharge burnup is 6,580 MWd/tU.
Because the power coefficient decreases in proportion to
an increase in the concentration of the added burnable
absorber, the addition of about 1.0 wt% Er203 results in the
power coefficient being 0.0090 mk/% power and the estimated
discharge burnup being 6,200 MWd/tU. Also, when about 2.0 wt%
Er203 is added, the power coefficient is 0.0036 mk/% power, and
the estimated discharge burnup is 5,400 MWd/tU.
As mentioned above, in the case where the burnable
absorber is homogeneously mixed in the center rod 100, the
9
CA 02708902 2010-06-30
concentration of the useful burnable absorber (Er or Er203) may
fall in the range of from 0 wt% to 2.0 wt%.
<TEST EXAMPLE 1-2>
The power coefficient at medium burnup depending on the
amount of Er2C3 mixed with fuel having an enrichment of 0.7 wt%
is depicted in FIG. 2B.
Specifically, the power coefficient in the absence of the
burnable absorber at 102.5% power is 0.0126 mk/% power, and
W the estimated discharge burnup is 6,580 MWd/tU.
Because the power coefficient decreases in proportion to
an increase in the concentration of the added burnable
absorber, the addition of about 1.0 wt% Er203 results in the
power coefficient being 0.0090 mk/% power and the estimated
discharge burnup being 5,780 MWd/tU. Also, when about 2.0 wt%
Er2C3 is added, the power coefficient is 0.0018 mk/% power, and
the estimated discharge burnup is 4,870 MWd/tU.
As mentioned above, in the case where the burnable
absorber is homogeneously mixed in the center rod 100, the
concentration of the useful burnable absorber (Er2C3) may fall
in the range of from 0 wt% to 2.0 wt%.
<TEST EXAMPLE 1-3>
The power coefficient at medium burnup depending on the
amount of Er203 mixed with fuel having an enrichment of 1.0 wt%
CA 02708902 2010-06-30
is depicted in FIG. 2C.
Specifically, the power coefficient in the absence of the
burnable absorber at 102.5% power is 0.0200 mk/% power, and
the estimated discharge burnup is 16,350 MWd/tU.
Because the power coefficient decreases in proportion to
an increase in the concentration of the added burnable
absorber, the addition of about 14 wt% Er203 results in the
power coefficient being -0.0018 mk/% power and the estimated
discharge burnup being 12,040 MWd/tU. Also, when about 100
M wt% Er203 is added, the power coefficient is -0.0344 mk/% power,
and the estimated discharge burnup is 4,400 MWd/tU.
As mentioned above, in the case where the burnable
absorber is homogeneously mixed in the center rod 100, the
concentration of the useful burnable absorber (Er or Er203) may
fall in the range of from 0 wt% to 100 wt%.
<TEST EXAMPLE 1-4>
The power coefficient at medium burnup depending on the
amount of Er2C3 mixed with fuel having an enrichment of 1.0 wt%
is depicted in FIG. 20.
Specifically, the power coefficient in the absence of the
burnable absorber at 102.5% power is 0.0200 mk/% power, and
the estimated discharge burnup is 16,350 MWd/tU.
Because the power coefficient decreases in proportion to
an increase in the concentration of the added burnable
11
CA 02708902 2010-06-30
absorber, the addition of about 14 wt% Er2C3 results in the
power coefficient being -0.0018 mk/% power and the estimated
discharge burnup being 11,900 MWd/tU. Also, when about 100
wt% Er2C3 is added, the power coefficient is -0.0362 mk/% power,
and the estimated discharge burnup is 4,220 MWd/tU.
As mentioned above, in the case where the burnable
absorber is homogeneously mixed in the center rod 100, the
concentration of the useful burnable absorber (Er2C3) may fall
in the range of from 0 wt% to 100 wt%.
<TEST EXAMPLE 1-5>
The power coefficient at medium burnup depending on the
amount of Er203 mixed with fuel having an enrichment of 3.0 wt%
is depicted in FIG. 2E.
Specifically, the power coefficient in the absence of the
burnable absorber at 102.5% power is 0.0053 mk/% power, and
the estimated discharge burnup is 55,450 MWd/tU.
Because the power coefficient decreases in proportion to
an increase in the concentration of the added burnable
absorber, the addition of about 25 wt% Er203 results in the
power coefficient being -0.0071 mk/% power and the estimated
discharge burnup being 51,290 MWd/tU. Also, when about 100
wt% Er203 is added, the power coefficient is -0.0190 mk/% power,
and the estimated discharge burnup is 45,590 MWd/tU.
As mentioned above, in the case where the burnable
12
CA 02708902 2010-06-30
absorber is homogeneously mixed in the center rod 100, the
concentration of the useful burnable absorber (Er or Er203) may
fall in the range of from 0 wt% to 100 wt%.
<TEST EXAMPLE 1-6>
The power coefficient at medium burnup depending on the
amount of Er2C3 mixed with fuel having an enrichment of 3.0 wt%
is depicted in FIG. 2F.
Specifically, the power coefficient in the absence of the
W burnable absorber at 102.5% power is 0.0053 mk/% power, and
the estimated discharge burnup is 55,450 MWd/tU.
Because the power coefficient decreases in proportion to
an increase in the concentration of the added burnable
absorber, the addition of about 25 wt% Er2C3 results in the
power coefficient being -0.0071 mk/% power and the estimated
discharge burnup being 51,120 MWd/tU. Also, when about 100
wt% Er2C3 is added, the power coefficient is -0.0190 mk/% power,
and the estimated discharge burnup is 45,330 MWd/tU.
As mentioned above, in the case where the burnable
absorber is homogenously mixed in the center rod 100, the
concentration of the useful burnable absorber (Er2C3) may fall
in the range of from 0 wt% to 100 wt%.
In addition, according to a second embodiment of the
present invention, a CANDU fuel bundle loaded with a burnable
absorber is specified below.
CA 02708902 2010-06-30
FIG. 3 schematically shows the CANDU fuel bundle loaded
with the burnable absorber according to the second embodiment
of the present invention.
As shown in FIG. 3, the CANDU fuel bundle loaded with the
burnable absorber according to the second embodiment of the
present invention includes a center rod 100, and a plurality
of fuel rods 200 arranged in concentric rings around the
center rod 100.
The center rod 100, which is disposed at the center of
the fuel bundle 1, may include a burnable absorber and fuel,
which are homogeneously mixed together.
As such, the burnable absorber mixed in the center rod
100 may be Er, Er203 or Er2C3.
Among the fuel rods 200, fuel rods 200 arranged in the
closest concentric ring to the center rod 100, namely, fuel
rods 200 of the first ring may include a burnable absorber and
fuel, which are homogeneously mixed together.
The burnable absorber mixed in such fuel rods 200 may be
Er, Er203 or Er2C3, which is the same as the burnable absorber
mixed in the center rod 100.
Furthermore, the burnable absorber mixed in the center
rod 100 and the burnable absorber mixed in the fuel rods 200
of the first ring, each of which is mixed with the fuel, may
be at the same concentration. As such, the concentration of
both the burnable absorber mixed in the center rod 100 and the
14
CA 02708902 2010-06-30
. =
burnable absorber mixed in the fuel rods 200 of the first ring
may be 100 wt% or less.
FIGS. 4A to 4F show changes in the power coefficient at
medium burnup when the burnable absorber is used at the same
concentration in the CANDU fuel bundle loaded with the
burnable absorber according to the second embodiment of the
present invention.
As such, in a 43-rod fuel bundle which is a type of fuel
bundle that is loadable into a CANDU reactor loaded with fuel
M having an enrichment of 0.7 wt%, 1.0 wt% or 3.0 wt%, when Er203
or Er2C3 that is the burnable absorber, which is homogeneously
mixed with the fuel in the center rod 100 and the fuel rods
200 arranged in the closest concentric ring to the center rod
100, namely, the fuel rods 200 of the first ring, is used at
the same concentration, changes in the power coefficient are
evaluated.
<TEST EXAMPLE 2-1>
The power coefficient at medium burnup depending on the
amount of Er203 mixed with fuel having an enrichment of 0.7 wt%
is depicted in FIG. 4A.
Because the power coefficient decreases in proportion to
an increase in the concentration of the added burnable
absorber, the addition of about 0.1 wt% Er203 results in the
power coefficient at 102.5% power being 0.0108 mk/% power and
the estimated discharge burnup being 5,950 MWd/tU. Also, when
CA 02708902 2010-06-30
=
about 0.2 wt% Er203 is added, the power coefficient at 102.5%
power is 0.0036 mk/% power, and the estimated discharge burnup
is 5,190 MWd/tU.
As mentioned above, in the case where the burnable
absorber which is homogeneously mixed in the center rod 100
and the fuel rods 200 of the first ring is used at the same
concentration, the concentration of the useful burnable
absorber (Er or Er203) may fall in the range of from 0 wt% to
0.2 wt%.
<TEST EXAMPLE 2-2>
The power coefficient at medium burnup depending on the
amount of Er2C3 mixed with fuel having an enrichment of 0.7 wt%
is depicted in FIG. 4B.
Because the power coefficient decreases in proportion to
an increase in the concentration of the added burnable
absorber, the addition of about 0.1 wt% Er2C3 results in the
power coefficient at 102.5% power being 0.0090 mk/% power and
the estimated discharge burnup being 5,940 MWd/tU. Also, when
about 0.2 wt% Er2C3 is added, the power coefficient at 102.5%
power is 0.0036 mk/% power, and the estimated discharge burnup
is 5,140 MWd/tU.
As mentioned above, in the case where the burnable
absorber which is homogeneously mixed in the center rod 100
and the fuel rods 200 of the first ring is used at the same
16
CA 02708902 2010-06-30
. =
concentration, the concentration of the useful burnable
absorber (Er2C3) may fall in the range of from 0 wt% to 0.2 wt%.
<TEST EXAMPLE 2-3>
The power coefficient at medium burnup depending on the
amount of Er203 mixed with fuel having an enrichment of 1.0 wt%
is depicted in FIG. 4C.
Because the power coefficient decreases in proportion to
an increase in the concentration of the added burnable
absorber, the addition of about 1.4 wt% Er203 results in the
power coefficient at 102.5% power being -0.0018 mk/% power and
the estimated discharge burnup being 12,120 MWd/tU.
Also,
when about 2.5 wt% Er203 is added, the power coefficient at
102.5% power is -0.0270 mk/% power, and the estimated
discharge burnup is 7,370 MWd/tU.
As mentioned above, in the case where the burnable
absorber which is homogeneously mixed in the center rod 100
and the fuel rods 200 of the first ring is used at the same
concentration, the concentration of the useful burnable
absorber (Er or Er203) may fall in the range of from 0 wt% to
2.5 wt%.
<TEST EXAMPLE 2-4>
The power coefficient at medium burnup depending on the
amount of Er2C3 mixed with fuel having an enrichment of 1.0 wt%
17
CA 02708902 2010-06-30
=
is depicted in FIG. 4D.
Because the power coefficient decreases in proportion to
an increase in the concentration of the added burnable
absorber, the addition of about 1.4 wt% Er2C3 results in the
power coefficient at 102.5% power being -0.0036 mk/% power and
the estimated discharge burnup being 11,960 MWd/tU.
Also,
when about 2.6 wt% Er2C3 is added, the power coefficient at
102.5% power is -0.0325 mk/% power, and the estimated
discharge burnup is 6,190 MWd/tU.
As mentioned above, in the case where the burnable
absorber which is homogeneously mixed in the center rod 100
and the fuel rods 200 of the first ring is used at the same
concentration, the concentration of the useful burnable
absorber (Er2C3) may fall in the range of from 0 wt% to 2.6 wt%.
<TEST EXAMPLE 2-5>
The power coefficient at medium burnup depending on the
amount of Er203 mixed with fuel having an enrichment of 3.0 wt%
is depicted in FIG. 4E.
When about 20 wt% Er203 is added, the power coefficient
at 102.5% power is -0.0461 mk/% power, and the estimated
discharge burnup is 28,820 MWd/tU. Also, when about 40 wt%
Er203 is added, the power coefficient at 102.5% power is -
0.0500 mk/% power, and the estimated discharge burnup is
19,470 MWd/tU.
18
CA 02708902 2010-06-30
As mentioned above, in the case where the burnable
absorber which is homogeneously mixed in the center rod 100
and the fuel rods 200 of the first ring is used at the same
concentration, the concentration of the useful burnable
absorber (Er or Er203) may fall in the range of from 0 wt% to
100 wt%.
<TEST EXAMPLE 2-6>
The power coefficient at medium burnup depending on the
amount of Er2C3 mixed with fuel having an enrichment of 3.0 wt%
is depicted in FIG. 4F.
When about 20 wt% Er2C3 is added, the power coefficient
at 102.5% power is -0.0443 mk/% power, and the estimated
discharge burnup is 28,090 MWd/tU. Also, when about 40 wt%
Er2C3 is added, the power coefficient at 102.5% power is -
0.0517 mk/% power, and the estimated discharge burnup is
18,830 MWd/tU.
As mentioned above, in the case where the burnable
absorber which is homogeneously mixed in the center rod 100
and the fuel rods 200 of the first ring is used at the same
concentration, the concentration of the useful burnable
absorber (Er2C3) may fall in the range of from 0 wt% to 100 wt%.
On the other hand, the burnable absorber mixed in the
center rod 100 and the burnable absorber mixed in the fuel
rods 200 arranged in the closest concentric ring to the center
19
CA 02708902 2010-06-30
rod 100, namely, the fuel rods 200 of the first ring, each of
which is mixed with the fuel, may be at different
concentrations. As
such, the concentration of the burnable
absorber mixed in the center rod 100 may be 100 wt% or less,
and the concentration of the burnable absorber mixed in the
fuel rods 200 of the first ring may be 100 wt% or less.
As such, in a 43-rod fuel bundle which is a type of fuel
bundle that is loadable into a CANDU reactor loaded with fuel
having an enrichment of 0.7 wt%, 1.0 wt% or 3.0 wt%, when Er203
W or Er2C3 that is the burnable absorber, which is homogeneously
mixed with the fuel in the center rod 100 and the fuel rods
200 arranged in the closest concentric ring to the center rod
100, namely, the fuel rods 200 of the first ring, is used at
different concentrations, changes in the power coefficient are
evaluated.
FIGS. 5A and 5B show changes in the power coefficient at
medium burnup when the burnable absorber is used at different
concentrations in the CANDU fuel bundle loaded with the
burnable absorber according to the second embodiment of the
present invention.
<TEST EXAMPLE 2-7>
The power coefficient at 102.5% power and the estimated
discharge burnup depending on the amount of Er203 mixed with
fuel having an enrichment of 0.7 wt% are shown in Table 1
below.
CA 02708902 2010-06-30
. =
TABLE 1
Amount of Er203 Power Coefficient Estimated
____________________________________________ at 102.5% power
Discharge Burnup
Center Rod First Ring (mk/% power) (MWd/tU)
0.0 wt% 0.0 wt% 0.0126 6,580
0.0 wt% 0.24 wt% 0.0036 5,100
0.1 wt% 0.2 wt% 0.0036 5,290
1.0 wt% 0.1 wt% 0.0036 5,140
2.0 wt% 0.0 wt% 0.0036 5,400
As is apparent from this table, when the concentration of
Er203 of the center rod 100 is 0.1 wt% and the concentration of
Er203 of the fuel rods 200 of the first ring is 0.2 wt%, the
power coefficient at 102.5% power is 0.0036 mk/% power and the
estimated discharge burnup is 5,290 MWd/tU.
As mentioned above, in the case where the burnable
absorber which is homogeneously mixed in the center rod 100
and the fuel rods 200 of the first ring is used at different
concentrations, the concentration of the useful burnable
absorber (Er or Er203) may range from 0 wt% to 2.0 Wt% for the
center rod 100, and may range from 0 wt% to 0.24 wt% for the
fuel rods 200 of the first ring.
<TEST EXAMPLE 2-8>
The power coefficient at 102.5% power and the estimated
discharge burnup depending on the amount of Er2C3 mixed with
fuel having an enrichment of 0.7 wt% are shown in Table 2
21
CA 02708902 2010-06-30
below.
TABLE 2
Power Coefficient Estimated
Amount of Er2C3
at 102.5% power
Discharge Burnup
Center Rod First Ring (mk/% power) (mwd/tU)
0.0 wt% 0.0 wt% _________________________ 0.0126 6,580
0.0 wt% 0.24 wt% 0.0036 5,050
0.1 wt% 0.2 wt% 0.0036 5,240
1.0 wt% 0.1 wt% 0.0036 5,080
2.0 wt% 0.0 wt% 0.0018 4,870
As is apparent from this table, when the concentration of
Er2C3 of the center rod 100 is 0.1 wt% and the concentration of
Er2C3 of the fuel rods 200 of the first ring is 0.2 wt%, the
power coefficient at 102.5% power is 0.0036 mk/% power, and
W the estimated discharge burnup is 5,240 MWd/tU.
As mentioned above, in the case where the burnable
absorber which is homogeneously mixed in the center rod 100
and the fuel rods 200 of the first ring is used at different
concentrations, the concentration of the useful burnable
absorber (Er2C3) may range from 0 wt% to 2.0 wt% for the center
rod 100, and may range from 0 wt% to 0.24 wt% for the fuel
rods 200 of the first ring.
<TEST EXAMPLE 2-9>
The power coefficient at medium burnup depending on the
amount of Er203 mixed with fuel having an enrichment of 1.0 wt%
22
CA 02708902 2010-06-30
is depicted in FIG. 5A.
FIG. 5A shows the power coefficient at medium burnup
depending on changes in the concentration of Er203 of the fuel
rods 200 of the first ring under conditions in which the
concentration of Er203 of the center rod 100 is 0.6 wt%.
Because the power coefficient decreases in proportion to
the increase in the concentration of the added burnable
absorber, when the concentration of Er203 of the center rod 100
is 0.6 wt% and the concentration of Er203 of the first ring is
1.4 wt%, the power coefficient at 102.5% power is -0.0018 mk/%
power, and the estimated discharge burnup is 12,460 MWd/tU.
The power coefficient at 102.5% power and the estimated
discharge burnup when Er203 that is the burnable absorber is
homogeneously mixed in the center rod 100 and the fuel rods
200 of the first ring are shown in Table 3 below.
TABLE 3
Amount of Er203 Power Coefficient Estimated
_____________________________________ at 102.5% power Discharge
Burnup
Center Rod First Ring (mk/% power) (MWd/tU)
0.0 wt% 0.0 wt% 0.0200 16,350
0.0 wt% 3.0 wt% -0.0307 6,540
0.6 wt% 1.4 wt% -0.0018 12,460
25.0 wt% 1.0 wt% -0.0325 5,590
100.0 wt% 0.0 wt% -0.0344 4,440 ___
As mentioned above, in the case where the burnable
absorber which is homogeneously mixed in the center rod 100
23
CA 02708902 2010-06-30
_ =
and the fuel rods 200 of the first ring is used at different
concentrations, the concentration of the useful burnable
absorber (Er or Er203) may range from 0 wt% to 100 wt% for the
center rod 100, and may range from 0 wt% to 3 wt% for the fuel
rods 200 of the first ring.
<TEST EXAMPLE 2-10>
The power coefficient at medium burnup depending on the
amount of Er2C3 mixed with fuel having an enrichment of 1.0 wt%
is depicted in FIG. 5B.
FIG. 5B shows the power coefficient at medium burnup
depending on changes in the concentration of Er2C3 of the fuel
rods 200 of the first ring under conditions in which the
concentration of Er2C3 of the center rod 100 is 0.6 wt%.
Because the power coefficient decreases in proportion to
the increase in the concentration of the added burnable
absorber, when the concentration of Er2C3 of the center rod 100
is 0.6 wt% and the concentration of Er2C3 of the first ring is
1.4 wt%, the power coefficient at 102.5% power is 0.00 mk/%
power, and the estimated discharge burnup is 12,310 MWd/tU.
The power coefficient at 102.5% power and the estimated
discharge burnup when Er2C3 that is the burnable absorber is
homogeneously mixed in the center rod 100 and the fuel rods
200 of the first ring are shown in Table 4 below.
24
CA 02708902 2010-06-30
TABLE 4
Power Coefficient Estimated
Amount of Er2C3
at 102.5% power Discharge Burnup
Center Rod First Ring (mk/% power) (MWd/tU)
0.0 wt% 0.0 wt% 0.0200 16,350
0.0 wt% 3.0 wt% -0.0343 5,910
0.6 wt% 1.4 wt% 0.0 12,310
25.0 wt% 1.0 wt% -0.0344 5,110
100.0 wt% 0.0 wt% -0.0362 4,220
As mentioned above, in the case where the burnable
absorber which is homogeneously mixed in the center rod 100
and the fuel rods 200 of the first ring is used at different
concentrations, the concentration of the useful burnable
absorber (Er203) may range from 0 wt% to 100 wt% for the center
rod 100, and may range from 0 wt% to 3 wt% for the fuel rods
200 of the first ring.
<TEST EXAMPLE 2-11>
The power coefficient at 102.5% power and the estimated
discharge burnup depending on the amount of Er203 mixed with
fuel having an enrichment of 3.0 wt% are shown in Table 5
below.
TABLE 5
Amount of Er203 Power Coefficient
Estimated
at 102.5% power Discharge Burnup
Center Rod First Ring (mk/% power) (MWd/tU)
0.0 wt% 0.0 wt% 0.0053 55,450
0.0 wt% 100 wt% -0.0486 13,370
= -
CA 02708902 2010-06-30
20 wt% 80 wt% -0.0522 14,210
40 wt% 60 wt% -0.0503 15,950
60 wt% 40 wt% -0.0499 19,150
=
80 wt% 20 wt% -0.0433 26,800
=
100 wt% 0.0 wt% -0.0190 45,590
As is apparent from this table, when the concentration of
Er203 of the center rod 100 is 80 wt% and the concentration of
Er203 of the first ring is 20 wt%, the power coefficient at
102.5% power is -0.0443 mk/% power, and the estimated
discharge burnup is 26,800 MWd/tU.
As mentioned above, in the case where the burnable
absorber which is homogeneously mixed in the center rod 100
and the fuel rods 200 of the first ring is used at different
M concentrations, the concentration of the useful burnable
absorber (Er203) may range from 0 wt% to 100 wt% for both the
center rod 100 and the fuel rods 200 of the first ring.
<TEST EXAMPLE 2-12>
The power coefficient at 102.5% power and the estimated
discharge burnup depending on the amount of Er2C3 mixed with
fuel having an enrichment of 3.0 wt% are shown in Table 6
below.
TABLE 6
Amount of Er2C3 Power Coefficient Estimated
at 102.5% power
Discharge Burnup
Center Rod First Ring (mk/% power) (MWditU)
0.0 wt% 0.0 wt% 0.0053 55,450
26
CA 02708902 2010-06-30
0.0 wt% 100 wt% -0.0505 12,720
20 wt% 80 wt% -0.0504 13,600
40 wt% 60 wt% -0.0520 15,330
60 wt% 40 wt% -0.0517 18,600
80 wt% 10 wt% -0.0461 26,210
100 wt% 0.0 wt% -0.0190 45,330
As is apparent from this table, when the concentration of
Er2C3 of the center rod 100 is 80 wt% and the concentration of
Er2C3 of the first ring is 20 wt%, the power coefficient at
102.5% power is -0.0461 mk/% power, and the estimated
discharge burnup is 26,210 MWd/tU.
As mentioned above, in the case where the burnable
absorber which is homogeneously mixed in the center rod 100
and the fuel rods 200 of the first ring is used at different
W concentrations, the concentration of the useful burnable
absorber (Er2C3) may range from 0 wt% to 100 wt% for both the
center rod 100 and the fuel rods 200 of the first ring.
In addition, according to a third embodiment of the
present invention, a CANDU fuel bundle loaded with a burnable
absorber is specified below.
FIG. 6 schematically shows the CANDU fuel bundle loaded
with the burnable absorber, according to the third embodiment
of the present invention.
As shown in FIG. 6, the CANDU fuel bundle loaded with the
burnable absorber, according to the third embodiment of the
present invention, includes a center rod 100, and a plurality
of fuel rods 200 arranged in concentric rings around the
27
CA 02708902 2010-06-30
center rod 100.
The center rod 100 includes a core portion 110 and a
cylindrical sheath portion 120, and may be disposed at the
center of the fuel bundle 1.
In the center rod 100, the core portion 110 may include a
burnable absorber, and the sheath portion 120 may include fuel.
As such, the burnable absorber included in the core
portion 110 may be Er, Er203 or Er2C3, and the radius of the
burnable absorber may be equal to or less than that of the
fuel rods.
FIGS. 7A to 71 show changes in the power coefficient at
medium burnup of the CANDU fuel bundle loaded with Er, Er203 or
Er2C3 that is the burnable absorber, according to the third
embodiment of the present invention.
As such, in a 43-rod fuel bundle which is a type of fuel
bundle that is loadable into a CANDU reactor loaded with fuel
having an enrichment of 0.7 wt%, 1.0 wt% or 3.0 wt%, when Er203,
Er or Er2C3 that is the burnable absorber is separately placed
in the core portion 110 of the center rod 100 and the fuel is
placed in the cylindrical sheath portion 120 of the center rod
100, changes in the power coefficient are evaluated.
<TEST EXAMPLE 3-1>
The power coefficient at medium burnup depending on the
radius of Er203 inserted at the core portion 110 of the center
rod 100 under conditions in which fuel having an enrichment of
28
CA 02708902 2010-06-30
0.7 wt% is placed in the sheath portion 120 of the center rod
100 is depicted in FIG. 7A.
Because the power coefficient decreases in proportion to
an increase in the radius of the burnable absorber inserted at
the core portion 110 of the center rod 100, when the radius of
the burnable absorber is 0.10 cm, the power coefficient at
102.5% power is 0.0054 mk/% power, and the estimated discharge
burnup is 5,370 MWd/tU. Furthermore, when the radius of the
burnable absorber is 0.13 cm, the power coefficient at 102.5%
power is 0.0 mk/% power, and the estimated discharge burnup is
2,270 MWd/tU.
As mentioned above, in the case where the burnable
absorber is separately placed in the core portion 110 of the
center rod 100, the radius of the burnable absorber (Er203) may
range from 0 cm to 0.13 cm.
<TEST EXAMPLE 3-2>
The power coefficient at medium burnup depending on the
radius of Er inserted at the core portion 110 of the center
rod 100 under conditions in which fuel having an enrichment of
0.7 wt% is placed in the sheath portion 120 of the center rod
100 is depicted in FIG. 7B.
Because the power coefficient decreases in proportion to
the increase in the radius of the burnable absorber inserted
at the core portion 110 of the center rod 100, when the radius
29
CA 02708902 2010-06-30
of the burnable absorber is 0.10 cm, the power coefficient at
102.5% power is 0.0054 mk/% power, and the estimated discharge
burnup is 5,160 MWd/tU. Furthermore, when the radius of the
burnable absorber is 0.12 cm, the power coefficient at 102.5%
power is 0.0018 mk/% power and the estimated discharge burnup
is 4,560 MWd/tU.
As mentioned above, in the case where the burnable
absorber is separately placed in the core portion 110 of the
center rod 100, the radius of the burnable absorber (Er) may
W range from 0 cm to 0.12 cm.
<TEST EXAMPLE 3-3>
The power coefficient at medium burnup depending on the
radius of Er2C3 inserted at the core portion 110 of the center
0 rod 100 under conditions in which fuel having an enrichment of
0.7 wt% is placed in the sheath portion 120 of the center rod
100 is depicted in FIG. 7C.
Because the power coefficient decreases in proportion to
the increase in the radius of the burnable absorber inserted
20 at the core portion 110 of the center rod 100, when the radius
of the burnable absorber is 0.10 cm, the power coefficient at
102.5% power is 0.0054 mk/% power, and the estimated discharge
burnup is 5,370 MWd/tU. Furthermore, when the radius of the
burnable absorber is 0.13 cm, the power coefficient at 102.5%
25 power is 0.0 mk/% power, and the discharge burnup is estimated
CA 02708902 2010-06-30
to be 2,190 MWd/tU.
As mentioned above, in the case where the burnable
absorber is separately placed in the core portion 110 of the
center rod 100, the radius of the burnable absorber (Er2C3) may
range from 0 cm to 0.13 cm.
<TEST EXAMPLE 3-4>
The power coefficient at medium burnup depending on the
radius of Er203 inserted at the core portion 110 of the center
rod 100 under conditions in which fuel having an enrichment of
1.0 wt% is placed in the sheath portion 120 of the center rod
100 is depicted in FIG. 7D.
Because the power coefficient decreases in proportion to
the increase in the radius of the burnable absorber inserted
at the core portion 110 of the center rod 100, when the radius
of the burnable absorber is 0.33 cm, the power coefficient at
102.5% power is -0.0018 mk/% power, and the estimated
discharge burnup is 11,620 MWd/tU.
Furthermore, when the
radius of the burnable absorber is equal to that of the center
rod 100, the power coefficient at 102.5% power is -0.0344 mk/%
power, and the estimated discharge burnup is 4,440 MWd/tU.
As mentioned above, in the case where the burnable
absorber is separately placed in the core portion 110 of the
center rod 100, the radius of the burnable absorber (Er203) may
range from 0 cm to equal to or less than the radius of the
31
CA 02708902 2010-06-30
fuel rods.
<TEST EXAMPLE 3-5>
The power coefficient at medium burnup depending on the
radius of Er inserted at the core portion 110 of the center
rod 100 under conditions in which fuel having an enrichment of
1.0 wt% is placed in the sheath portion 120 of the center rod
100 is depicted in FIG. 7E.
Because the power coefficient decreases in proportion to
W the increase in the radius of the burnable absorber inserted
at the core portion 110 of the center rod 100, when the radius
of the burnable absorber is 0.3 cm, the power coefficient at
102.5% power is 0.0 mk/% power, and the estimated discharge
burnup is 11,890 MWd/tU. Furthermore, when the radius of the
burnable absorber is equal to that of the center rod 100, the
power coefficient at 102.5% power is -0.0381 mk/% power, and
the estimated discharge burnup is 4,000 MWd/tU.
As mentioned above, in the case where the burnable
absorber is separately placed in the core portion 110 of the
center rod 100, the radius of the burnable absorber (Er) may
range from 0 cm to equal to or less than the radius of the
fuel rods.
<TEST EXAMPLE 3-6>
The power coefficient at medium burnup depending on the
32
CA 02708902 2010-06-30
. =
radius of Er2C3 inserted at the core portion 110 of the center
rod 100 under conditions in which fuel having an enrichment of
1.0 wt% is placed in the sheath portion 120 of the center rod
100 is depicted in FIG. 7F.
Because the power coefficient decreases in proportion to
the increase in the radius of the burnable absorber inserted
at the core portion 110 of the center rod 100, when the radius
of the burnable absorber is 0.30 cm, the power coefficient at
102.5% power is 0.0018 mk/% power, and the estimated discharge
W burnup is 12,080 MWd/tU. Furthermore, when the radius of the
burnable absorber is equal to that of the center rod 100, the
power coefficient at 102.5% power is -0.0362 mk/% power, and
the estimated discharge burnup is 4,220 MWd/tU.
As mentioned above, in the case where the burnable
absorber is separately placed in the core portion 110 of the
center rod 100, the radius of the burnable absorber (Er2C3) may
range from 0 cm to equal to or less than the radius of the
fuel rods.
<TEST EXAMPLE 3-7>
The power coefficient at medium burnup depending on the
radius of Er203 inserted at the core portion 110 of the center
rod 100 under conditions in which fuel having an enrichment of
3.0 wt% is placed in the sheath portion 120 of the center rod
100 is depicted in FIG. 7G.
33
CA 02708902 2010-06-30
Because the power coefficient decreases in proportion to
the increase in the radius of the burnable absorber inserted
at the core portion 110 of the center rod 100, when the radius
of the burnable absorber is 0.30 cm, the power coefficient at
102.5% power is -0.0035 mk/% power, and the estimated
discharge bUrnup is 52,470 MWd/tU.
Furthermore, when the
radius of the burnable absorber is equal to that of the center
rod 100, the power coefficient at 102.5% power is -0.0190 mk/%
power, and the estimated discharge burnup is 45,590 MWd/tU.
As mentioned above, in the case where the burnable
absorber is separately placed in the core portion 110 of the
center rod 100, the radius of the burnable absorber (Er203) may
range from 0 cm to equal to or less than the radius of the
fuel rods.
<TEST EXAMPLE 3-8>
The power coefficient at medium burnup depending on the
radius of Er inserted at the core portion 110 of the center
rod 100 under conditions in which fuel having an enrichment of
3.0 wt% is placed in the sheath portion 120 of the center rod
100 is depicted in FIG. 7H.
Because the power coefficient decreases in proportion to
the increase in the radius of the burnable absorber inserted
at the core portion 110 of the center rod 100, when the radius
of the burnable absorber is 0.3 cm, the power coefficient at
34
CA 02708902 2010-06-30
102.5% power is -0.0053 mk/% power, and the estimated
discharge burnup is 52,010 MWd/tU.
Furthermore, when the
radius of the burnable absorber is equal to that of the center
rod 100, the power coefficient at 102.5% power is -0.0172 mk/%
power, and the estimated discharge burnup is 45,030 MWd/tU.
As mentioned above, in the case where the burnable
absorber is separately placed in the core portion 110 of the
center rod 100, the radius of the burnable absorber (Er) may
range from 0 cm to equal to or less than the radius of the
W fuel rods.
<TEST EXAMPLE 3-9>
The power coefficient at medium burnup depending on the
radius of Er2C3 inserted at the core portion 110 of the center
rod 100 under conditions in which fuel having an enrichment of
3.0 wt% is placed in the sheath portion 120 of the center rod
100 is depicted in FIG. 71.
Because the power coefficient decreases in proportion to
the increase in the radius of the burnable absorber inserted
at the core portion 110 of the center rod 100, when the radius
of the burnable absorber is 0.30 cm, the power coefficient at
102.5% power is -0.0053 mk/% power, and the estimated
discharge burnup is 52,260 MWd/tU.
Furthermore, when the
radius of the burnable absorber is equal to that of the center
rod 100, the power coefficient at 102.5% power is -0.0190 mk/%
_ _
CA 02708902 2010-06-30
=
power, and the estimated discharge burnup is 45,330 MWd/tU.
As mentioned above, in the case where the burnable
absorber is separately placed in the core portion 110 of the
center rod 100, the radius of the burnable absorber (Er2C3) may
range from 0 cm to equal to or less than the radius of the
fuel rods.
In addition, according to a fourth embodiment of the
present invention, a CANDU fuel bundle loaded with a burnable
absorber is specified below.
FIG. 8 schematically shows the CANDU fuel bundle loaded
with the burnable absorber, according to the fourth embodiment
of the present invention.
As shown in FIG. 8, the CANDU fuel bundle loaded with the
burnable absorber according to the fourth embodiment of the
present invention includes a center rod 100, and a plurality
of fuel rods 200 arranged in concentric rings around the
center rod 100.
The center rod 100 includes a core portion 110 and a
cylindrical sheath portion 120, and may be disposed at the
center of the fuel bundle 1.
In the center rod 100, the core portion 110 may include a
burnable absorber, and the sheath portion 120 may include the
burnable absorber and fuel, which are homogeneously mixed
together.
As such, the burnable absorber, which is included in the
36
CA 02708902 2010-06-30
core portion 110 and is mixed in the sheath portion 120, may
be Er, Er203 or Er2C3. The
burnable absorber may be at a
concentration of 100 wt% or less, and may have a radius that
is equal to or less than that of the fuel rods.
FIGS. 9A and 9B show changes in the power coefficient at
medium burnup of the CANDU fuel bundle loaded with the
burnable absorber according to the fourth embodiment of the
present invention.
As such, in a 43-rod fuel bundle which is a type of fuel
W bundle that is loadable into a CANDU reactor loaded with fuel
having an enrichment of 0.7 wt%, 1.0 wt% or 3.0 wt%, when Er203,
Er or Er2C3 that is the burnable absorber is separately placed
in the core portion 110 of the center rod 100 and Er203, Er or
Er2C3 that is the burnable absorber is homogeneously mixed with
the fuel in the cylindrical sheath portion 120 of the center
rod 100, changes in the power coefficient are evaluated.
<TEST EXAMPLE 4-1>
When Er or Er203 that is a burnable absorber is
separately inserted at the core portion 110 of the center rod
100 and Er203 that is the burnable absorber is homogenously
mixed with fuel having an enrichment of 0.7 wt% in the sheath
portion 120 of the center rod 100, changes in the power
coefficient are evaluated.
Specifically, the power coefficient varies depending on
the concentration of the fuel homogeneously mixed in the
37
CA 02708902 2010-06-30
sheath portion 120 of the center rod 100 and the radius of the
burnable absorber separately placed in the core portion 110 of
the center rod 100.
The power coefficient at medium burnup depending on the
radius of Er or Er203 inserted at the core portion 110 of the
center rod 100 is shown in Table 7 below.
TABLE 7
Estimated
Burnable Radius of Power Coefficient
Amount of Er203 at Discharge
Absorber at Core at 102.5% power
Sheath portion Burnup
Core portion portion (mk/% power)
(MWd/tU)_
1 0.0 cm 0.0 wt% 0.0126 6,580
Er203 0.01 cm 2.0 wt% 0.0036 5,390
1 Er203 0.12 cm 0.1 wt% 0.0036 4,740
0.0 cm 0.24 wt% 0.0036 5,100
Er203_ 0.13 cm 0.0 4,540
Er 0.01 cm 0.0 wt% 0.0054 5,160
Er 0.01 cm 2.0 wt% 0.0036 5,380
Er 0.12 cm 0.1 wt% 0.0 4,470
Er 0.12 am 0.0018 4,560
As is apparent from this table, when 2.0 wt% Er203 is
homogeneously mixed with the fuel in the sheath portion 120
and the radius of the burnable absorber (Er203) of the core
portion 110 is 0.01 cm, the power coefficient at 102.5% power
at medium burnup is 0.0036 mk/% power, and the estimated
discharge burnup is 5,390 MWd/tU. Furthermore, when 2.0 wt%
Er203 is homogeneously mixed with the fuel in the sheath
portion 120 and the radius of the burnable absorber (Er) of
the core portion 110 is 0.01 cm, the power coefficient at
38
CA 02708902 2010-06-30
102.5% power at medium burnup is 0.0036 mk/% power, and the
estimated discharge burnup is 5,380 MWd/t0.
As mentioned above, in the case where the burnable
absorber is separately inserted at the core portion 110 of the
center rod 100 and Er203 that is the burnable absorber is
homogeneously mixed with the fuel in the sheath portion 120 of
the center rod 100, the concentration of Er203 may range from 0
wt% to 2.0 wt% and the radius of the burnable absorber (Er or
Er203) of the core portion 110 may range from 0 cm to 0.12 cm.
<TEST EXAMPLE 4-2>
When Er2C3 that is a burnable absorber is separately
inserted at the core portion 110 of the center rod 100 and
Er2C3 that is the burnable absorber is homogenously mixed with
fuel having an enrichment of 0.7 wt% in the sheath portion 120
of the center rod 100, changes in the power coefficient are
evaluated.
The power coefficient at medium burnup depending on the
radius of Er2C3 inserted at the core portion 110 of the center
rod 100 is shown in Table 8 below.
TABLE 8
Estimated
Burnable Radius of Amount of Er2C3 Power Coefficient
Absorber at Core Core at Sheath at 102.5% power Discharge
Burnup
portion portion portion (mk/% power)
(MWd/tU)
0.0 cm 0.0 wt% 0.0126 6,580
39
CA 02708902 2010-06-30
= =
Er2C3 0.01 cm 2.0 wt% 0.0036 5,390
Er2C3 0.12 cm 0.1 wt% 0.0036 4,740
Er2C3 0.0 cm 0.24 wt% 0.0036 5,100
0.13 cm 0.0 4,540
As is apparent from this table, when 2.0 wt% Er2C3 is
homogeneously mixed with the fuel in the sheath portion 120
and the radius of the burnable absorber of the core portion
110 is 0.01 cm, the power coefficient at 102.5% power at
medium burnup is 0.0018 mk/% power, and the estimated
discharge burnup is 4,850 MWd/tU.
As mentioned above, in the case where the burnable
absorber is separately inserted at the core portion 110 of the
W center rod 100 and Er2C3 that is the burnable absorber is
homogeneously mixed with the fuel in the sheath portion 120 of
the center rod 100, the concentration of Er2C3 may range from 0
wt% to 2.0 wt% and the radius of the burnable absorber (Er2C3)
of the core portion 110 may range from 0 cm to 0.12 cm.
<TEST EXAMPLE 4-3>
When Er or Er203 that is a burnable absorber is
separately inserted at the core portion 110 of the center rod
100 and Er203 that is the burnable absorber is homogeneously
mixed with fuel having an enrichment of 1.0 wt% in the sheath
portion 120 of the center rod 100, changes in the power
coefficient are evaluated.
The power coefficient at medium burnup depending on the
-
CA 02708902 2010-06-30
radius of Er or Er203 inserted at the core portion 110 of the
center rod 100 is shown in FIG. 9A and Table 9 below.
TABLE 9
Estimated
Burnable Radius of Amount of Er203 Power Coefficient
Absorber at Core Core at Sheath at 102.5% power Discharge
Burnup
portion portion portion (mk/% power)
(MWd/tU)
0.0 cm 0.0 wt% 0.0200 16,350
Er203 0.29 cm 3.0 wt% -0.0005
11,810
Er203 0.25 cm 5.0 wt% -0.0007
12,080
0.0 cm 25.0 wt% 1 -0.0126 9,580
Er203 0.10 cm 25.0 wt% -0.0119
9,370
Er203 0.30 cm 25.0 wt% -0.0161
8,220 j
Er203 0.63325 cm -0.0344 4,440
Er 0.30 cm 0.0 wt% 0.0 11,890
Er 0.30 cm 5.0 wt% -0.0072
10,910
Er 0.30 cm 25.0 wt% -0.0181
8,050
Er 0.12 cm -0.0381 4,000
When 5.0 wt% Er203 is homogeneously mixed with the fuel
in the sheath portion 120 and the radius of the burnable
absorber (Er203) of the core portion 110 is 0.25 cm, the power
M coefficient at 102.5% power at medium burnup is -0.0007 mk/%
power, and the estimated discharge burnup is 12,080 MWd/tU.
Furthermore, when 5.0 wt% Er203 is homogeneously mixed with the
fuel in the sheath portion 120 and the radius of the burnable
absorber (Er) of the core portion 110 is 0.30 cm, the power
coefficient at 102.5% power at medium burnup is -0.0072 mk/%
power, and the estimated discharge burnup is 10,910 MWd/tU.
As mentioned above, in the case where the burnable
absorber is separately inserted at the core portion 110 of the
41
_ -
CA 02708902 2010-06-30
center rod 100 and Er203 that is the burnable absorber is
homogeneously mixed with the fuel in the sheath portion 120 of
the center rod 100, the concentration of Er203 may range from 0
wt% to 100 wt% and the radius of the burnable absorber (Er or
Er203) at the core portion 110 may range from 0 cm to equal to
or less than the radius of the fuel rods.
<TEST EXAMPLE 4-4>
When Er2C3 that is a burnable absorber is separately
W inserted at the core portion 110 of the center rod 100 and
Er2C3 that is the burnable absorber is homogeneously mixed with
fuel having an enrichment of 1.0 wt% in the sheath portion 120
of the center rod 100, changes in the power coefficient are
evaluated.
The power coefficient at medium burnup depending on the
radius of Er2C3 inserted at the core portion 110 of the center
rod 100 is shown in FIG. 9B and Table 10 below.
TABLE 10
Estimated
Burnable Radius of Amount of Er2C3 Power Coefficient
Discharge
Absorber at Core Core at Sheath at 102.5% power
Burnup
portion portion portion (mk/% power)
(MWd/tU)
0.0 cm 0.0 wt% 0.0200 16,350
Er2C3 0.30 cm 3.0 wt% -0.0036 11,450
Er2C3 0.25 cm 5.0 wt% 0.0 11,900
0.0 cm 25.0 wt% -0.0126 9,580
Er2C3 0.10 cm 25.0 wt% -0.0145 9,150
Er2C3 0.30 cm 25.0 wt% -0.0181 8,020
Er2C3 0.63325 cm -0.0362 4,220
42
CA 02708902 2010-06-30
Specifically, the power coefficient varies depending on
the concentration of the fuel homogeneously mixed in the
sheath portion 120 of the center rod 100 and the radius of the
burnable absorber separately placed in the core portion 110 of
the center rod 100.
When 5.0 wt% Er2C3 is homogeneously mixed with the fuel
in the sheath portion 120 and the radius of the burnable
absorber (Er2C3) of the core portion 110 is 0.25 cm, the power
coefficient at 102.5% power at medium burnup is 0.0 mk/% power,
and the estimated discharge burnup is 11,900 MWd/tU.
As mentioned above, in the case where the burnable
absorber is separately inserted at the core portion 110 of the
center rod 100 and Er2C3 that is the burnable absorber is
homogeneously mixed with the fuel in the sheath portion 120 of
the center rod 100, the concentration of Er2C3 may range from 0
wt% to 100 wt% and the radius of the burnable absorber (Er2C3)
may range from 0 cm to equal to or less than that of the fuel
rods.
<TEST EXAMPLE 4-5>
When Er or Er203 that is a burnable absorber is
separately inserted at the core portion 110 of the center rod
100 and Er203 that is the burnable absorber is homogeneously
mixed with fuel having an enrichment of 3.0 wt% in the sheath
43
CA 02708902 2010-06-30
portion 120 of the center rod 100, changes in the power
coefficient are evaluated.
The power coefficient at medium burnup depending on the
radius of Er or Er203 inserted at the core portion 110 of the
center rod 100 is shown in Table 11 below.
TABLE 11
Estimated
Burnable Radius of Amount of Er203 Power Coefficient
Absorber at Core Core at Sheath at 102.5% power Discharge
Burnup
portion portion portion (mk/% power)
(MWd/tU)
0.0 cm 0.0 wt% ' 0.0053 55,450
Er203 0.30 cm 20 wt% -0.0088 50,150
Er203 0.30 cm 40 wt% I -0.0122 48,400
Er203 0.30 cm 60 wt% -0.0139 47,130
Er203 0.30 cm 80 wt% -0.0139 46,230
Er203 0.63325 an -0.0190 45,990
Er 0.30 cm 20 wt% -0.0070 49,800
Er 0.30 cm 40 wt% -0.0122 48,160
Er 0.30 cm 60 wt% -0.0157 46,960
Er 0.30 cm 80 wt% -0.0138 46,130
Er 0.63325 an -0.0172 45,030
Specifically, the power coefficient varies depending on
the concentration of the fuel homogeneously mixed in the
sheath portion 120 of the center rod 100 and the radius of the
burnable absorber separately placed in the core portion 110 of
the center rod 100.
When 20 wt% Er203 is homogeneously mixed with the fuel in
the sheath portion 120 and the radius of the burnable absorber
(Er203) of the core portion 110 is 0.30 cm, the power
coefficient at 102.5% power at medium burnup is -0.0088 mk/%
44
CA 02708902 2010-06-30
power, and the estimated discharge burnup is 50,150 MWd/tU.
Furthermore, when 20 wt% Er203 is homogeneously mixed with the
fuel in the sheath portion 120 and the radius of the burnable
absorber (Er) of the core portion 110 is 0.30 cm, the power
coefficient at 102.5% power at medium burnup is -0.0070 mk/%
power, and the estimated discharge burnup is 49,800 MWd/tU.
As mentioned above, in the case where the burnable
absorber is separately inserted at the core portion 110 of the
center rod 100 and Er203 that is the burnable absorber is
homogeneously mixed with the fuel in the sheath portion 120 of
the center rod 100, the concentration of Er203 may range from 0
wt% to 100 wt%, and the radius of the burnable absorber (Er or
Er203) of the core portion 110 may range from 0 cm to equal to
or less than the radius of the fuel rods.
<TEST EXAMPLE 4-6>
When Er2C3 that is a burnable absorber is separately
inserted at the core portion 110 of the center rod 100 and
Er2C3 that is the burnable absorber is homogeneously mixed with
fuel having an enrichment of 3.0 wt% in the sheath portion 120
of the center rod 100, changes in the power coefficient are
evaluated.
The power coefficient at medium burnup depending on the
radius of Er2C3 inserted at the core portion 110 of the center
rod 100 is shown in Table 12 below.
CA 02708902 2010-06-30
=
TABLE 12
Estimated
Burnable Radius of Amount of Er2C3 Power Coefficient
Discharge
Absorber at Core Core at Sheath at 102.5% power
Burnup
portion portion portion (mk/% power)
(MWd/tU)
0.0 cm 0.0 wt% 0.0053 55,450
Er2C3 0.30 cm 20 wt% I -0.0088
49,900
Er2C3 0.30 cm 40 wt% -0.0122 48,130
Er2C3 0.30 cm 60 wt% -0.0156
46,840____
Er2C3 0.30 cm 80 wt% -0.0173 45,960
Er2C3 0.63325 cm -0.0190 45,330
Specifically, the power coefficient varies depending on
the concentration of the fuel homogeneously mixed in the
sheath portion 120 of the center rod 100 and the radius of the
burnable absorber separately placed in the core portion 110 of
the center rod 100.
When 20 wt% Er2C3 is homogeneously mixed with the fuel in
the sheath portion 120 and the radius of the burnable absorber
of the core portion 110 is 0.30 cm, the power coefficient at
102.5% power at medium burnup is -0.0088 mk/% power, and the
estimated discharge burnup is 49,900 MWd/tU.
3 As mentioned above, in the case where the burnable
absorber is separately inserted at the core portion 110 of the
center rod 100 and Er2C3 that is the burnable absorber is
homogeneously mixed with the fuel in the sheath portion 120 of
the center rod 100, the concentration of Er2C3 may range from 0
wt% to 100 wt%, and the radius of the burnable absorber (Er2C3)
46
CA 02708902 2010-06-30
of the core portion 110 may range from 0 cm to equal to or
less than that of the fuel rods.
As described hereinbefore, the present invention provides
a CANDU fuel bundle loaded with a burnable absorber.
According to the present invention, the use of the CANDU fuel
bundle loaded with the burnable absorber results in the
negative power coefficient of the CANDU reactor because of the
burnable absorber included in the fuel bundle, thus improving
inherent safety of the CANDU reactor.
Although the preferred embodiments of the present
invention regarding the CANDU fuel bundle loaded with the
burnable absorber have been disclosed for illustrative
purposes, those skilled in the art will appreciate that various
modifications, additions and substitutions are possible,
without departing from the scope and spirit of the invention as
disclosed in the accompanying claims.
47
