Graphite Component Assessment for TMSR Samantha Yong, Derek Tsang, Maoyuan Cai.
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Transcript of Graphite Component Assessment for TMSR Samantha Yong, Derek Tsang, Maoyuan Cai.
Graphite Component Assessment for TMSR
Samantha Yong, Derek Tsang, Maoyuan Cai
Contents
1. Introduction of ASME and KTA-3232
2. The numerical result from ASME and KTA-3232
3. Effect of maximum grain size on probability of
failure finally
TMSR graphite core
16 graphite components Top and bottom reflector Side reflector Dowel Key
To show the designs are safe There are two standards
ASME USA KTA-3232 German
1. Introduction of ASME and KTA-3232
Determi ni st i c
ASME HHA
Graphi te reactor
assessment
KTA-3232
Probabi l i ty theory
Probabi l i ty theory
Determi ni st i c
Assess wi th stress l i mi ts
Assess wi th POF l i mi ts
Stress l i mi ts i s to be cal cul ated usi ng Two-parameter Wei bul l di stri buti on
POF l i mi ts i s to be cal cul ated usi ng three-parameter Wei bul l di stri buti on
Same
Di ff erent
Stress l i mi ts i s to be cal cul ated usi ng two-parameter Wei bul l di stri buti on
POF l i mi ts i s to be cal cul ated usi ng two-parameter Wei bul l di stri buti on
Probability of Failure flow chart in ASME
Convert compressi ve stress to equi val ent
tensi l e stress
Rank the i ntegrati on poi nts i n decreasi ngorder of equi val ent stress
Cal cul ate S0
El i mi nate i ntegrati on poi nts bel ow i ntegrati on
poi nts
Cal cul ate Xi
Start fi rst group
Sel ect fi rst hi ghtest stress
Add i ntegrati on
poi nt
I s the vol ume of group l arger than (10× mgs)3
Does di ff erence between max(Xi )and mi n(Xi )
exceed 7%Any i ntegrati on
poi nt l ef t
End current group and cal cul ate probabi l i ty
of survi val
Start new group
End l ast group
Cal cul ate probabi l i ty of survi val
For enti re component Cal cul ate POF
YES
NO
YES
YES
NO
NO
Sel ect next i ntegrati on
poi nt
stress limit
In process , equivalent stress is calculated as
Xi is the index of Weibull distribution calculated as
Convert compressi ve stress to equi val ent
tensi l e stress
Rank the i ntegrati on poi nts i n decreasi ngorder of equi val ent stress
Cal cul ate S0
El i mi nate i ntegrati on poi nts bel ow i ntegrati on
poi nts
Cal cul ate Xi
Start fi rst group
Sel ect fi rst hi ghtest stress
Add i ntegrati on
poi nt
I s the vol ume of group l arger than (10× mgs)3
Does di ff erence between max(Xi )and mi n(Xi )
exceed 7%Any i ntegrati on
poi nt l ef t
End current group and cal cul ate probabi l i ty
of survi val
Start new group
End l ast group
Cal cul ate probabi l i ty of survi val
For enti re component Cal cul ate POF
YES
NO
YES
YES
NO
NO
Sel ect next i ntegrati on
poi nt
probability of failure procedure in KTA-3232
main difference between ASME HHA and KTA-3232 is as follows:
components are grouped in ASME, do not need to be grouped in KTA-3232
The difference between ASME and KTA-3232
Probability models
ASME : Weibull three parameter model
KTA-3232 : Weibull two parameter model
Calculate method
ASME : group the integration points, Group Conditions :
The group volume is bigger than (10×mgs)3
In the group , max(Xi) is greater than min(Xi) 7%
KTA-3232 : do not group the components
m
SS
Sx
cF
0
0
exp1
m
S
x
cF
exp1
ASME HHA POF Limits
The POF limits of ASME HHA and KTA-3232 are same .
KTA-3232 POF Limits
Boundary conditions: a. The model is symmetry by the XY, XZ
plane, ¼ model is to be calculated.b. Calculation software :ABAQUS,
element type C3D20, element number 11786.
600 700 800 900 1000 1100 1200 1300 1400 15000
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
(mm)堆芯径向距离
(10
辐照
剂量
20 n
/cm
2E
DN
D )
原 始 数 据拟 合 数 据
the irradiation distribution under normal operation as shown in Figure 1.
2. The calculate result of ASME and KTA-3232
Finite element model
Table 1. POF of 2 different modelThe POF of ASME is more conservative
The stress of component after 20 years
POF(ASME HHA)
POF (KTA-3232)
model 1 2.8E-3 1.8E-8
model 2 5.4E-5 1.6E-8
Model 1 keyway root radius=2mmModel 2 keyway root radius=5mm
Maximum grain size: the maximum filler particle grain size that is used in the
graphite formulation.
Each graphite has different MGS, however MGS is one of the most important
factors to affect POF, so we have analyzed the effect of MGS on POF.
NG-CT-10EGCR-TYPE
AGOT[1]NBG-18[2] H451[1]
MGS/mm 0.025 0.78 1.6 1.6
[1]A modified weibull theory for the strength of granular brittle material[2] A numerical stress based approach for predicting failure in NBG-18 nuclear graphite components with verification problems
Table 1. different MGS for different graphite
3. Effect of maximum grain size(MGS) on probability of failure
The POF of Graphite component of NBG-18
Table 2. POF of same model for different MGS
Table 1. Parameter of three parameters Weibull distribution
• MGS is one of grouping criterion in ASME.
• The grouping criterion is based on
experiment of NBG-18.
• The grouping criterion is suitable for the
graphite has the same or similar MGS.
• The method to calculate POF maybe
conservative (or too conservative) if the
MGS is small when assess the fine grade
graphite.
• The group criterion should be remark for the
fine coarse graphite.
MGS/mm POF
0.025 1.5E-2
0.17 2.8E-3
0.48 1.1E-4
0.78 2.3E-5
1 1.1E-5
1.6 2.8E-6
In order to analysis the effect of MGS,
NBG-18 is chosen to calculate POF.
14
Conclusions
Described the differences between ASME and KTA-3232, compared the POF of the two standards, The POF of ASME is more conservative.
The effect of MGS on POF has been analyzed, ASME standard is based on coarse grain graphite, for fine grain graphite the grouping criterion should be modified for the fine grain graphite.
Thank you