31
Key Laboratory of Neutronics and Radiation Safety
Institute of Nuclear Energy Safety Technology (INEST)
Chinese Academy of Sciences
Contributed by FDS Team
www.fds.org.cn
Preliminary RAMI Analysis of the
HCCB TBS
Presented by Jin Wang
I. Background
II. RAMI Analysis of the HCCB TBS
III. Future Plan
Contents
Reliability plays a key role in Fusion Engineering
60%
65%
70%
75%
80%
85%
90%
95%
100%
Vac
uum V
esse
l
Mag
nets
(TF, P
F, C
D, C
C)
Therm
al S
hield
s
Cry
osta
t & V
V P
SS
SS E
lect
rica
l Pow
er N
etwork
Inte
rlock
Sys
tem
CODAC
Coi
l Pow
er s
upp. &
Dis
trib
utio
n
Wat
er C
ooling
Cry
opla
nt &
Cry
odis
trib
ution
Vac
uum p
umpin
g
Rad
iolo
gica
l & e
nviro
nmen
tal m
onitor
Fuellin
g & W
all C
onditi
oning
Bla
nket S
yste
m
Div
erto
r Cas
sette
s & P
FCs
Pol
oidal
fiel
d sy
stem
contr
oller
Dia
gnost
ic G
1a
ITEROperationalSystemReliability
OverallMachineReliability
Why Reliability is Required
The availability target of current fusion devices is far from the required value
for a fusion reactor to be attractive for economic aspects (at least 75%)
Both Reliability of components and Maintainability of functions are important
for the Availability of a plant
Challenges
Reliability data of some fusion-
specific components unknown
Lack of probabilistic safety goals for
fusion reactor
TBS must have a high availability
The duty cycle goals require TBS have a high availability
[1] Project Requirement, ITER, 2014
[1]
I. Background
II. RAMI Analysis of the HCCB TBS
III. Future Plan
Contents
Functional Breakdown of HCCB TBS
A-0 The HCCB TBS A1 Tritium breeding and on-line tritium control A11 Produce the tritium in the pebble beds of TBM A12 Extract the bred tritium from the breeder of TBM A13 Isolate the extracted tritium from the purge gas A14 Purification of the tritium A15 On-line tritium control A2 Production and removal of heat
A21 Produce the heat in the beryllium and breeder pebble beds A22 Removal heat from the TBM to the secondary cooling loop A23 Exchange heat from high temperature helium to cold side A24 Exchange heat with Tokamak cooling water system A25 Pressure control A3 Shield and support
A31 Protection of TBM from excessive nuclear heating and radiation
damage A32 Helium supply and storage A4 Monitor and control
A41 Monitoring operation parameters of TBS A42 Adjust the status of equipment A43 Safety relative monitoring
[1] Didier van Houtte, 2008
The IDEFØ is not a software but a method which is based on the SADT (Structured Analysis and Design Technique) approach to model functions (activities, actions, processes, operations), functional relationships and data for a system.
As an analysis tool, IDEFØ assists the modeler in identifying what functions are performed, what is needed to perform those functions, what the current system does right, and what the current system does wrong. It is a hierarchical top down modeling process. Activities (functions) can be described by their Inputs, Controls, Outputs, and Mechanisms (ICOMs).
Top-level diagrams can be decomposed and activities can be refined into greater and greater detail as required for understanding and making decisions.
Function Analysis Tool of IDEFØ Approach (1)
(Not essential)
Function Analysis Tool of IDEFØ Approach (1)
[1] Didier van Houtte, 2008
IDEFØ model for A0
IDEFØ model for A1
IDEFØ model for A2
IDEFØ model for A3
IDEFØ model for A4
Overview of the Functional Breakdown of HCCB TBS
Example of FMECA Results
FMECA for HCCB TBS
System ITEM Basic Function Failure Mode Effect on Main
Function Cause
ITER
operation
availability
Duty Cycle
TBM Set
TBM Module
Tritium
breeding Rupture
Material
defects
99.43%
100%
Heat extracting 100%
TBM Shied
To provide
shielding for
neutrons
Rupture Plasme
disruption
Material
defects 100%
As part of
vacuum
boundaries
VV
pressurisation 100%
HCS
Helium Cooler
To cool the
helium purge
gas coming
from TBM
system
Rupture HTO into glove
box
Material
defects
99.99%
100%
Loss of cooling
function
High
temperature
helium enter
system without
cooling,
100%
Heat exchanger
To cool the
coolant comes
from TBM
Leakage (shell) Material
defects 99.96%
100%
Leakage (tube) Material
defects 100%
0 1 2 3 4 5 6
1
2
3
4
5
6
0
Severity
Occurrence
C=13
C=7
1241
2
12
123
15
0 1 2 3 4 5 6
1
2
3
4
5
6
0
Severity
Occurrence
C=13
C=7
55
2
3
53
8
669
The initial criticality matrix with 196 failures. The expected criticality matrix,
which displays the expected results after implementation of the advocated risk-
reducing actions and mitigating provisions
Criticality Matrix
INITIAL CRITICALITY CHART EXPECTED CRITICALITY CHART
The inherent availability of the
HCCB TBS expected after
implementation of mitigation
actions was calculated to be
94.69% over 2 years.
The availability of Blanket system
needs to be improved.
Function System Availability
All functions of HCCB TBS HCCB TBS 0.94687
Tritium breeding and on-line tritium
control TES 0.950214
Production and removal of high-grade
heat HCS, CPS, 0.921517
Shield and support TBM, 0.996042
Monitor and control I&C 0.979023
Calculation Results
The development of remote handling or remote maintenance technology
could greatly improve the availability of HCCB TBS
I. Background
II. RAMI Analysis of the HCCB TBS
III. Future Plan
Contents
RAMI of DFLL TBS
Function Breakdown
• 4 main functions
• 14 sub-functions
• 52 Basic functions
RBD for DFLL TBS
Failure Mode Analysis (on-going)
• 143 failure modes
Comparison of Two Blankets
Function Comparison (on-going)
Risk Comparison (on-going)
Continue to Conduct RAMI Analysis of DFLL TBS
The initial criticality matrix with 181 failures. The expected criticality matrix, which displays the expected results
after implementation of the advocated risk-reducing actions and mitigating provisions
FMECA for DFLL TBS
Oi/Si 0 1 2 3 4 5 6 Total
0
1 0
2 5 3 8 4 2 22
3 19 18 21 39 1 98
4 22 21 14 2 59
5 2 2
6 0
Total 46 42 43 47 3 0 181
Minor Medium Major
Number 75 101 5
% 41.436464 55.801105 2.7624309
Initial Criticality Matrix
Oi/Si 0 1 2 3 4 5 6 Total
0
1 0
2 5 3 8 4 2 22
3 19 23 21 35 98
4 22 21 16 59
5 2 2
6 0
Total 46 49 45 39 2 0 181
Minor Medium Major
Number 80 101 0
% 44.198895 55.801105 0
Expected Criticality Matrix
Component Op.
St.
Failure
Mode
Freq
Cat
Causes Prev.Action on
Causes
Consequences Corr./Prev. Act. on
Consequence
PIEs Comment
TBM-FSW NO Rupture (1)Material defects;
(2)Impact of heavy
loads (missile inside
VV);
(3)Abnormal
operating conditions
(e.g.: vibrations);
(4)Fatigue;
(5)Arcs due to halo
currents
(1)Test during
manufacturing &
assembly;
(2) In-vessel viewing;
(3) Optimize
maintenance
procedures
(1) Loss of He coolant in VV;
(2) Plasma disruption;
(3) VV pressurisation;
(4) Pressure relief towards VVPSS;
(5) Release of RadP_VV to VVPSS
IVC-1 Missile should not get TBM
because magnetic fields
inside the vessel should
accelerate foreign objects
towards inboard zone and
not towards ouboard zone. In
any case, such remote
cause has to be excluded by
a dedicated analysis
Probabilistic Safety Goals Reflecting the Safety Levels of Reactor
Lack of Fusion Reactor Probabilistic Safety Goals?
Fission Reactor Probabilistic Safety Goals are Not Suitable for Fusion
Reactor
Probabilistic Safety Goals for Fusion Reactor?
Fission Reactor：CDF，LRF
Fusion Reactor：？
Systematically Distributing Reliability
Performance Index?
RAMI and PSA
Technical
Support
• 1. Technical Specification
for Design
• 2. Quantitative Indicators
for Safety Regulation
• 3. Online Maintenance
Technology
• 4. Reliability Test
• ……
Probabilistic Safety Goals
Reliability Index
Reliability Requirements Reliability Index for Fusion
Availability Data
Reliability Data
To support：
The RAMI approach is one of the main stages of the
technical risk control to guide the design of components
Consequences
Technical Risk Control
Dependability
Reliability
0 R(Dt) 1
Probability so that a system is
failure free in the interval (0, t)
Availability
A(t)
Probability so that a
system works
Maintainability
0 M(Dt) 1
Probability so that the
system is repaired in
the interval (0, t)
Safety
Probability so that a
catastrophic event
is avoided
at time t
S(t)
Inspectability
Probability so that the
performance and the
usable lifetime
of an equipment
is monitored
at time t
I(t)
RAMI
[1] RAMI Analysis Approach for ITER, D.Van Houtte 2008
[1]
Main Functions of HCCB TBS
Remove the surface heat flux and the nuclear heating within the
allowable limits for materials temperature and for stress and deformation.
Reduce the nuclear responses in the vacuum vessel structural material
according to ITER fluence goal.
Contribute to the protection of superconducting magnets against
excessive nuclear heating and radiation damage.
Provide a maximum degree of mechanical and structural self-support
to: (1) minimize the loads transmitted to the vacuum vessel, and (2)
decouple the operating temperature ranges between the test blanket
system, and the vacuum vessel.
The inherent availability of the DFLL TBS expected was calculated to be 94.69% over 2 years.
The availability of Blanket system need to be improve.
The development of remote handling or remote maintenance technology could greatly improved the availability of HCCB TBS
Calculation Results for DFLL TBS
Function Inherent
availability（%） Reliability
(%) A0 98.5745 67.8500 A1 99.43 99.9 A2 99.29 71.18 A3 99.82 96.76
System Overview
General Mean Availability (All Events): 0.985745
Std Deviation (Mean Availability): 0.013164
Mean Availability (w/o PM, OC & Inspection): 0.985745
Point Availability (All Events) at 17520: 0.988
Reliability(17520): 0
Expected Number of Failures: 25.765
Std Deviation (Number of Failures): 4.83789
MTTFF (小时): 617.703713
MTBF (Total Time) (小时): 679.992238
MTBF (Uptime) (小时): 670.298623
MTBE (Total Time) (小时): 679.992238
MTBE (Uptime) (小时): 670.298623
Functional Breakdown for DFLL TBS
A-0: Tritium safe-sufficiency and extraction of heat
A1: To produce the tritium and heat power
A2: To Extract the bred tritium and heat by LAS
A2.1 To extracts the bred tritium from TBM
A2.2 To purification the LiPb
A2.3 To drive the circulation of LiPb
A2.4 To support LAS
A3 To exchange heat by Helium
A 3.1 To exchange heat from PHL to TCWS
A3.2 To purification the helium
A3.3 To control the pressure of helium
A 3.4 To exchange heat from SHL to TCWS
DFLL TBS VS HCCB TBS
Oi/Si 0 1 2 3 4 5 6 Total
0
1 0
2 5 3 8 4 2 22
3 19 18 21 39 1 98
4 22 21 14 2 59
5 2 2
6 0
Total 46 42 43 47 3 0 181
Minor Medium Major
Number 75 101 5
% 41.436464 55.801105 2.7624309
Initial Criticality Matrix
Oi/Si 0 1 2 3 4 5 6 Total
0
1 0
2 5 3 8 4 2 22
3 19 23 21 35 98
4 22 21 16 59
5 2 2
6 0
Total 46 49 45 39 2 0 181
Minor Medium Major
Number 80 101 0
% 44.198895 55.801105 0
Expected Criticality Matrix
1. The Risks for HCCB TBS[1]
2. The Risks for DFLL TBS[2]
a. 3 major risks were removed
from the “red zone”.
b. The availability was calculated
as 94.69% .
a. 5 major risks were removed from the “red zone”.
b. The availability was calculated as 98.57% .
Reliability Data Work
Data Collection
• Collect available 5264 information on failures of systems highlighting causes,
consequences of failure and maintenance actions performed.
• Collect all relevant information for carrying out probabilistic analysis on failures, e.g.
operating times/cycles of systems and components, number of components installed in the
plant.
Data Analysis
• K factor method was used to adjust the failure rates of the TES pipes under the different
environments and conditions by combining physics of failure models and a conservative
estimation technique.
Fusion Reactor Components have Higher Reliability Requirements
Lack of Systematic Reliability Performance Index for Fusion
Reactor
Reliability Performance Index for Fusion Reactor
