Dynamic-Testing-Of-Model-Reactor-Core-Bricks-That-Can-Crack-During-Shaking-Table-Tests-

DEPARTMENT OF CIVIL ENGINEERING
The work described in this report is our own unaided effort, as are all the
text, tables and diagrams except where clearly referenced to others.
Dynamic Testing Of Model
Reactor Core Bricks That Can
Crack During Shaking Table Tests
Vladimir Djuric
Leo Youngman
Supervisor: Dr Adam Crewe

Dynamic Testing Of Model Reactor Core Bricks That Can Crack During Shaking Table Tests
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Dissertation presented as part of, and in accordance with, the requirements for the Final
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.
Author
Leo Youngman
Vladimir Djuric
Title Dynamic Testing Of Model Reactor Core Bricks That Can Crack
During Shaking Table Tests
Date of submission 23/04/15
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1
ABSTRACT
At the University of Bristol, research is being conducted to experimentally validate computer
models that predict the behaviour of nuclear reactor cores when subject to seismic events.
Degradation of the graphite within these cores can lead to a number of cracked or weakened
components. These computer models take into account the effects of cracked components on
the core. However, they fail to take into account that components could crack during a seismic
event.
This research project developed a prototype lattice fuel brick component that could crack on
demand during a dynamic test. This brick was introduced into a model of an AGR (Advanced
Gas-cooled Reactor) core on the shaking table at the University of Bristol. It was tested
dynamically to determine its performance and the effect it had on the model. The brick could
crack on demand and appeared to provide repeatable results, however not enough repeat tests
were conducted to establish its reliability.
From these findings it was determined that cracking the brick during a dynamic test led to an
increase in displacement of the array components in its proximity. Additionally, a reduction in
the displacement of components in other parts of the array was observed when the brick was
triggered to break.

2
TABLE OF CONTENTS
1 INTRODUCTION.............................................................................................................3
2 LITERATURE REVIEW ................................................................................................6
3 EQUIPMENT....................................................................................................................8
4 DEVELOPMENT OF THE COD BRICK ...................................................................13
5 INTACT ARRAY TESTS..............................................................................................20
6 INTRODUCING THE COD BRICK INTO THE ARRAY........................................23
7 DATA PROCESSING ....................................................................................................26
8 RESULTS AND DISCUSSION .....................................................................................29
9 CONCLUSIONS .............................................................................................................40
10 REFERENCES................................................................................................................41
11 ACKNOWLEDGEMENTS ...........................................................................................43
12 APPENDICES.................................................................................................................44

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1 INTRODUCTION
1.1 Background
EDF energy operate eight nuclear power stations
across the UK with Advanced Gas-cooled Reactor
(AGR) cores (EDF, 2015). These cores have
undergone degradation and fatigue over their lifetimes,
and as a result all but one of these power stations are
scheduled to close in 2023 (EDF, 2015). In 2010, EDF
introduced the Plant Life Extension (PLEX) scheme
with the aim of extending the operational life of seven
of these power stations by five years in order to safely
allow energy production to continue until 2028 (EDF,
2015). This scheme is of vital importance to the UK energy supply as the power generated
from these stations constitutes over a tenth of the UK’s total energy consumption (EDF, 2015).
If the operational lives of these stations cannot be extended, there will be a significant drop in
supply as replacement AGR cores are unlikely to be operational by 2023.
The cores consist of components made out of polygranular graphite (Neighbour, 2007: 91).
The purpose of the graphite is to moderate the flow of neutrons in order to slow down and
stabilise nuclear reactions. Additionally, these graphite bricks (Figure 1.1) direct flows of
coolant gases and must not impede the movement of the control or fuel rods through the core
(Neighbour, 2007: 19). Graphite is continually exposed to neutron irradiation and CO2 gas at
high temperatures and pressures; this causes changes within the microstructure and can lead to
degradation (Burchell, 2015). This degradation is in the form of cracks within the material. If
these cracks continue to propagate they can induce ‘through thickness full length axial cracking
of the fuel bricks’ (Neighbour, 2007: 240), which may cause certain parts of the structure to
collapse or distort. As a result, there is potential for the components to prevent control rods that
moderate reactions from moving in and out of the core. This could cause the reactor core to
overheat or possibly meltdown because the reaction cannot be controlled.
Research is being conducted at several institutions to assess whether the five-year extension
target set out by EDF is achievable. At the University of Bristol, a team of engineers are
working together to validate two computer-based models, GCORE (developed by Atkins) and
Figure 1.1 – AGR core
components (Dalrymple, 2013)

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SOLFEC (developed by the University of Glasgow), which predict the behaviour of nuclear
reactor cores during seismic events. These models also take into account the effects of cracking
on the graphite cores. However, it is possible that the competency of these models will need to
be increased in order to model the behaviour of the AGR cores with higher levels of
degradation then currently considered (Dihoru et al, 2014a).
In order to validate both models, three different physical models have been created and tested
on the six-axis shaking table in the laboratory at the University of Bristol. The first of these,
the multi-layer array (MLA), is an eight layer, 20x20 brick, quarter scale model of the AGR
cores used in power stations owned by EDF. This model consists of hollow cylindrical lattice
fuel bricks held together by interstitial bricks and keys. Some of these bricks contain
instrumentation in the form of accelerometers, hall sensors and potentiometers. This
instrumentation permits the measurement of acceleration, change in magnetic field, and
vertical displacement respectively during a dynamic test. Additionally, some of the lattice fuel
bricks in the array have a single crack i.e. ‘singly cracked,’ or are split axially into two halves
i.e. ‘doubly cracked’. Both cases represent potential cracking within the core. All of the
remaining bricks in the array are fully intact.
The two other models are a small 4x4x8 brick array known as the ‘Minicore’ and the single
layer array (Dihoru et al, 2014a). The single-layer array (SLA) is a 20x20 brick, single layer
model that consists of lattice fuel bricks which are a third of the height of the fuel bricks used
in the MLA. The configuration is almost identical to the MLA, with lattice bricks being held
together by interstitial bricks and keys; however there is no in-built instrumentation. The SLA
demonstrates the surface movement of the lattice bricks without the inter-layer effects of the
bricks below it, which is the case with the MLA. Beneath the array of bricks the entire surface
is covered in glass beads; their purpose is to create a surface that has the least possible friction
(see Section 3.3). Both the Minicore and the SLA support the MLA component design
validation (Dihoru et al, 2014a).
The aim of this research project was to develop a brick that could crack on demand during a
seismic event and observe how it behaved in the core. This was required to model the
possibility that during a seismic event, cracks which were already present within the graphite
could propagate further under seismic loading. As a result, a previously intact brick could
transform into a singly or doubly cracked brick, causing unexpected changes to the reactor core

5
structure. Incorporating this into the GCORE and SOLFEC models could provide a clearer
indication of how these AGR cores behave during seismic events.
A previous research project introduced the concept of a crack on demand (COD) brick that
could be used for repeatable testing of this scenario. The research outlined in this report
developed a prototype brick with electromagnets and an external trigger to change the brick
from an intact state to a doubly cracked state. The SLA alone was selected to test this brick
because of the simplicity of the system to assemble. Additionally, the displacements of the
bricks were much greater than in the MLA and there were no inter-layer interaction effects, as
was the case with the MLA (Brasier, 2014). This was due to the loose key arrangement of the
SLA and the absence of lattice bricks below it, which restricted their movement in the MLA.
Without these inter-layer effects, it was possible to exclusively observe the movement of the
individual bricks, and hence observe more clearly the effect that the crack on demand brick
had on the array.
1.2 Research objectives
1. Construct and develop a crack on demand (COD) brick with necessary additional
electronics and hardware that would allow desired functions of the brick to be used
during tests.
2. Develop a code that would enable the use of three different functions to control the
COD brick:
- A trigger mode which would crack the brick at a certain time during a test
- A force mode which would crack the brick at a certain load during a test
- A mode which will allow the code to be debugged via a serial monitor
3. Conduct a series of fully intact array tests on the shaking table:
- Using infra-red markers to monitor displacements
- And/or using a high speed vision system to monitor displacements
4. Utilise the intact array test methods to develop an understanding of how to conduct tests
when introducing the COD brick.
5. Conduct a series of tests introducing a brick that could crack on demand:
- Using a high speed vision system to monitor displacements
6. Demonstrate repeatability of the results of the tests.
7. Develop a code using MATLAB that could analyse data collected from tests.
8. Analyse the data and draw conclusions from the observed results.

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2 LITERATURE REVIEW
2.1 Initial sources
An initial understanding of how AGR cores operate was established from a number of online
sources, principally Neighbour (2007). In addition, an article on the history of AGR reactors
and their ownership in the UK presented a broad historical context and the possible cost
benefits of extending the lifetimes of these reactors (Dalrymple, 2013). Atkins (2011) produced
a brochure summarising a case study on the wider research programme with EDF. It outlined
why the company decided to introduce the PLEX programme and how the data from the
research with Atkins assisted in achieving the objectives of PLEX.
ONR (2012) defined the UK nationwide programme of research in the field of AGR cores.
This document described the statement of need and expected outcomes for each area of
research, and included a section on the seismic response of AGR cores. The resource provided
a clear understanding of why the research was conducted and why it was necessary to
understand the effects of cracking of components in reactor cores during seismic events (ONR
2012: 29). However, an understanding of this wider context did not provide enough
information on what research had been achieved so far in the programme with Atkins and EDF.
In order to understand this, the review also had to delve into the previous work that had been
conducted at the University of Bristol.
2.2 Previous work
As the current study's methodology was relatively novel, there were few relevant books
published on the subject. The majority of the literature review involved assessing recent
research projects or journal articles about the programme of research at the University of
Bristol. There were also some internal correspondence documents with Atkins, Brasier (2014)
and Dihoru et al. (2014b) that were provided for the project. These statements provided a useful
template for the research test schedule and highlighted the importance of providing clear aims
for testing. Each test had a clearly justified purpose and breakdown of the required results.
A previous year’s research project Benton & Pelmore (2014), and a journal article on the
University of Bristol’s experiment programme Dihoru et al. (2013a), were used to define the
research objectives and develop an understanding of prior achievements at the University of
Bristol. The experimental programme discussed the configuration of the SLA model, the

7
earthquake table loading and measurement systems. This information was important in order
to learn how to configure the single layer array and how to assemble the testing equipment.
2.3 Arduino literature
Another area of the review focused on developing an understanding of the Arduino platform
and the associated hardware. With no prior knowledge of this microcontroller programming
platform it was necessary to understand possible uses for Arduino, how to programme the code
for Arduino and why it was relevant to our project. Two sources of information, ARDX (n, d.)
and Banzi (2011), were predominantly used as a general introduction to the Arduino platform.
In addition, AMTEL (2009) and Shirriff (2009) were used to learn how to code Pulse Width
Modulation (PWM). This was achieved by utilising internal Arduino functions. PWM was used
to control the supply of voltage to the electromagnets and is explained in further detail in
Section 4.4. Benton & Pelmore (2014) did not entirely achieve the aim of developing a COD
brick that could be immediately used in a dynamic test. However, some of the more complex
PWM code was already developed in their research, which was important groundwork for fully
developing the COD brick.

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3 EQUIPMENT
3.1 Shaking table
BLADE (Bristol Laboratory for Advanced Dynamic
Engineering) at the University of Bristol contained a six-
axis shaking table capable of conducting a variety of
precise dynamic tests including sine-dwells and
simulating seismic events. The table was three by three
metres and powered by eight hydraulic actuators. The
table was capable of carrying up to fifteen tonnes.
3.2 Single Layer Array (SLA) restraint
The SLA restraint was a bespoke steel structure that
supported the array on the shaking table and weighed
two tonnes. The restraint had a ring of interstitial bricks
(see Section 3.11) that were bolted in place to form a
fixed restrained edge around the array. This interlocked
with the array but the components in the array were free
to move.
3.3 Glass beads
The surface of the single layer restraint was level and
covered in 0.5mm diameter glass beads. The purpose of
the beads was to create a surface that was as frictionless
as possible. A frictionless surface was desirable because
friction is difficult to model and requires complex non-
linear analysis due to phenomena such as stick-slip
friction (Urbakh, 2004).
3.4 Infra-red reflective markers
Infra-red markers were placed on the surface of the
bricks using tape as shown in Figure 3.4. These markers
were reflective and there were a variety of sizes for
different requirements.
Figure 3.1 – The shaking table
Figure 3.2 - SLA restraint
Figure 3.3 – Glass beads
Figure 3.4 – Reflective
markers on a brick

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3.5 Qualisys infra-red Vision System (VS)
The hardware was in the form of a single infra-red
camera mounted over the shaking table, with four other
infra-red cameras mounted around the table on a steel
frame (Figure 3.5). The infra-red cameras identified
markers placed on the bricks and tracked their
displacements in three-dimensional space through the
process of triangulation (see Section 5.5).
3.6 Qualisys High Speed Vision camera (HSV)
The hardware was in the form of a single high speed
vision camera, very similar to the camera shown in
Figure 3.5, mounted directly over the shaking table. It
recorded a video of the array at 25 frames per second
during a dynamic test.
3.7 Intact lattice fuel bricks
These were the primary components of the array. They
were made out of acetal plastic rather than graphite.
This material was chosen because it could be machined
precisely and possessed a low coefficient of friction.
Acetal was also used in favour of graphite because the
latter was brittle and could disintegrate, making it
unsuitable for use in the SLA. Lattice bricks were black
(Figures 3.6 to 3.8) while interstitial bricks (Figure
3.11) were white. This was so they could be easily
distinguished from each other by LabVIEW, which
required a high contrast image (see Section 7.1.2).
3.8 Singly cracked lattice fuel bricks
These bricks were identical to the intact bricks in size,
shape and material except they contained a crack only
on one side rather than a full width crack. They were
not used in this research project.
Figure 3.7 – Side elevation
Figure 3.5 – Qualisys
camera and frame
Figure 3.6 – Plan view of
intact lattice fuel brick
Figure 3.8 – 3D view

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3.9 Doubly cracked lattice fuel bricks
These bricks (Figure 3.9) were identical to the intact
bricks in size, shape and material. They were split into
two equal parts along their vertical axis. The inside face
surfaces are smooth.
3.10 Loose keys
Keys were 64x16x5mm white acetal cuboids which
contributed to the key locking system of an AGR core.
In combination with the interstitial bricks, the loose
keys locked the components in the correct positions.
3.11 Interstitial bricks
These acetal interstitial bricks allowed the array to
maintain its shape by connecting the lattice bricks
together with integral keys. Integral keys were built into
the interstitial brick (see Figure 3.11). In an AGR core,
control rods pass through the holes in the centre of these
bricks. The bricks were identified in video recordings by
the LabVIEW software using a reference marker (see
Figure 3.14), which was in the shape of an interstitial
brick (see Section 7.1.2).
3.12 Crack on demand brick (COD)
The COD brick was a modified doubly cracked lattice
brick with built in electromagnets and metal contacts
connected to an Arduino microcontroller, which
controlled the voltage supplied to the electromagnets.
When the electromagnets and metal contacts were
supplied with a voltage, they held the two halves of the
doubly cracked lattice brick together. When the voltage
was removed, they reverted to the cracked state, thereby
creating a brick that could ‘crack on demand’.
Figure 3.9 – Doubly cracked
lattice bricks
Figure 3.10 – Loose key
Figure 3.12 – Crack on
demand brick
Figure 3.11 – Interstitial
brick with integral keys

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3.13 Accelerometers
The purpose of the accelerometers was to measure the
acceleration of the table in the X, Y and Z direction.
There were accelerometers on three corners of the
table. In addition, the acceleration data permitted the
assessment of the table displacement, in each of the
three directions.
3.14 Reference marker
The reference marker was attached on to the single
layer restraint. This allowed LabVIEW to identify
those bricks in the array that were the same shape. In
turn, this permitted LabVIEW (see Section 7.1.2) to
calculate the position, and therefore displacement, of
those shapes in space. In the case of the tests outlined
in this report the reference marker was in the shape of
an interstitial brick, and hence the displacement data
collected was for interstitial bricks only.
3.15 Cardboard circles
Cardboard circles were cut out and taped over the
holes of the bricks in the centre of the array. This was
to prevent light reflecting off the glass beads from
interfering with the identification of the infra-red
markers, of which there were a high concentration in
the centre.
3.16 Qualisys Track Manager Software
The Qualisys Track Manager software was used in
order to track the displacements of the infra-red
markers and process videos of the dynamic tests.
Figure 3.14 – Reference marker
Figure 3.15 – Cardboard circles
to aid marker identification
Figure 3.13 - Accelerometers
Figure 3.16 – Qualisys control
computer

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3.17 Lighting system
LED lights were used to illuminate the
shaking table. These were selected so that the
identification of the reflective markers by the
Qualisys software was not affected by
flickering light. The blinds were also closed
to decrease light interference from the
external environment.
3.18 Control room computer
Dynamic tests were conducted using the
shaking table, with parameters being
controlled via the control room computer.
3.19 SLA configuration
The single layer array configuration is shown
in Figure 3.19. White interstitial bricks were
surrounded by four black lattice fuel bricks.
There were loose keys in the gaps between
adjacent lattice fuel bricks, which locked the
fuel bricks together. Figure 3.20 shows the
assembly diagram of the SLA. The final
assembled single layer array is shown in
Figure 3.21.
Figure 3.17 – Lighting system
Figure 3.18 – Control room computer
Figure 3.20 – Diagram of SLA configuration
(IAEA, n,d.)
Figure 3.19 – Actual configuration
Figure 3.21 – Fully assembled
SLA on shaking table

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4 DEVELOPMENT OF THE COD BRICK
4.1 Introduction
In order to develop a prototype COD brick, it was
necessary to review a previous research project at
the University of Bristol that was responsible for
the initial development of the brick (Benton &
Pelmore, 2014). This project focused on creating
a COD brick with a cracking mechanism that
would provide ‘repeatability and accuracy’ in
order to ensure further experimental work was
valid (Benton & Pelmore, 2014: 4). In order to
achieve this, two electromagnets and two metal
plates were attached flush against the inside faces
of the bricks. This allowed the two halves of the brick to be held together when a voltage was
supplied to the electromagnets. However, human and mechanical error was present when
changing the voltage manually (Benton & Pelmore, 2014: 32). Therefore a solution was
developed where an Arduino microcontroller was used to accurately and repeatedly supply the
required voltage to the electromagnets, thereby removing human error. Benton & Pelmore
(2014) also discovered that a hysteresis effect in the electromagnets would hold the two halves
of the brick together after the voltage was removed. This coercive force would stop the brick
from cracking and therefore a solution was required to remove this effect. This section of the
report describes the development process and how the hardware was adapted for the purposes
of this research project.
4.2 Suggested developments
In order to increase the capability of the COD brick to be used experimentally, Benton &
Pelmore (2014) suggested that some additional hardware should be integrated into the brick.
These suggestions were discussed along with some additional proposals. The evaluation of the
final proposals and the equipment required to enable these developments are recommended in
Table 4.1.
Figure 4.1 – Prototype COD brick as
initially developed by Benton &
Pelmore (2014)

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4.3 Development of the hardware
One issue with the original development of the breadboard was that the microcontroller was
coded so the user could only change the EM voltage by connecting it to a computer every time
it was necessary to do so (Figure 4.2). In order to safely access the testing area, the table had
to be shut down and put into the parked position. Changing the voltage between tests would
have required access to the testing area and as a result this process would have been time
consuming.
Proposed development Evaluation of proposal Suggested equipment
A trigger switch that
could manually crack
the brick.
This was crucial to creating a
trigger mode for the brick. It
was important to be able to
precisely time the trigger and
it was necessary to coordinate
it with the shaking table
control room computer.
This was designed to
coordinate with the shaking
table by connecting a signal
wire to an analog input on the
Arduino that received a trigger
from the signal. This provided
a signal to the Arduino to crack
on demand at a specified time
during a dynamic test.
A controlling circuit
for the electromagnets,
which could be
calibrated to vary the
voltage supplied to the
electromagnets.
This was required in order to
vary the force holding the two
halves of the brick together.
The proposal was used in
order to model bricks of
differing strengths.
The Arduino code and
hardware were developed in
order to allow the brick to
crack at different forces.
Switches were suggested that
could be manually changed to
vary the voltage required.
A release mechanism
that would allow the
brick to reverse the
coercive force that held
the brick together even
if the power supply was
switched off.
The two halves of the brick
may have remained intact
even with no voltage supplied
to the electromagnets due to
the coercive force. Therefore
this was critical in order to
reliably crack the brick.
This could be integrated into
the Arduino code. No
additional hardware was
necessary.
A sensor to measure
displacement of the
bricks as they moved.
This was required to create a
force mode that cracked the
brick, when it was subjected
to a force that caused a
movement of the two halves
of the brick.
Hall sensors were suggested as
displacement sensors because
they were sensitive to small
displacements. This was
important for the accuracy of
the experiment.
Table 4.1 - Evaluation of possible hardware developments to COD brick

15
In order to solve this issue, the breadboard had male header jumpers soldered into digital input
pins 4, 5, 6, 10, 11 and 12 (see Figure 4.4). Each header jumper was then connected to the
ground wire. The Arduino was coded to have these digital input pins as input pull-up resistors
(see Appendix 12.4 for code). These header jumpers, shown in Figure 4.3, could be put in the
on/off positions in different combinations to change the voltage across the electromagnets.
Switching the jumpers on or off varied the ‘holdvalue’ that controlled the EM voltage (see
Figure 6.4 for code excerpt). This approach was much faster at changing the EM voltage as it
could be done without connecting to the computer. It also allowed for future changes in
functions of the header jumper switches depending on the requirements. A current amplifier,
see Figure 4.4, was necessary as the Arduino microcontroller was not capable of transmitting
the large current required for the electromagnets. The current direction was switched using an
H-bridge component.
It was decided that for testing purposes, the
important and useful modes were modes 2 and
3 shown in Figure 4.6. In order to simply switch
between these modes, digital pin 4 (Figure 4.4)
was coded to select one of these modes
depending on whether the header jumper
(Figure 4.3) was in a closed or open position.
Pin 4 ‘Open’ or ‘LOW’ = 0, turned on the
trigger mode and pin 4 ‘Closed’ or ‘HIGH’ = 1,
turned on the force mode. See Section 6.2.1 for
more details.
Figure 4.2 - Connecting Arduino via serial
port for uploading new code and debugging
Figure 4.3 – Existing and developed
hardware in COD brick
Key:
Mounted hall sensors
Header jumper
Metal plate
Electromagnet
Breadboard
Arduino Microcontroller
H-bridge

16
The hall sensors that were selected operated by measuring changes in magnetic field. They
were utilised here as displacement sensors by sensing when a magnet mounted on the other
half of the brick had moved position. The two sensors were connected into two analog input
ports A0 and A2 and also connected to power and ground on the breadboard (see Figure 4.4).
The hall sensors were mounted onto the inside walls of one brick and two small magnets
mounted onto the inside walls of the other
half of the brick (see Figure 4.3).
Both the magnets and the hall sensors were
attached to small orange plastic supports
(Figures 4.3 and 4.5) using an epoxy resin
glue. The plastic supports were positioned
so that the hall sensors were flush with the
inside face of the doubly cracked brick.
Figure 4.5 – Mounting the hall sensors
and magnets
Figure 4.4 – Diagram of the Arduino microcontroller and associated hardware
D4
D5
D6
D10
D11
Digital Inputs Analog Inputs
A0
A2
D12
Microprocessor
Current
Amplifier
Current
Amplifier
PWM 1 PWM 2
Power Ground
Current: 50mA
Current: 1A
Current: 50mA
Electromagnet Electromagnet
Header Jumpers
Hall Sensor
Hall Sensor
D9
Connected to shaking
table trigger output

17
The hall sensors were coded to display values on the Arduino serial monitor during the
debugging process. The North Pole of a magnet produced values from 0 to 600 and the South
Pole produced values from 600 to 1200 on the Arduino serial monitor. The magnets were both
fixed in place with the North Pole exposed at the surface, which meant that the readable range
was from 0 to 600. When the hall sensors were mounted on the opposite side of the brick, it
was important to check that their distance from the magnets corresponded with a value halfway
between 0 and 600 on the serial monitor. This was to ensure that the hall sensors were calibrated
to read positive and negative change. Therefore a value of 300 on the monitor was the target
for positioning the magnets correctly.
4.4 Development of the Arduino code
The basic architecture of the original Arduino code limited the ability of the user to use the
COD brick in an actual experiment. This was because the code was not initially developed with
the required testing functions in mind. It was initially developed by Benton & Pelmore (2014)
to create a working repeatable release mechanism. In order to develop the electromagnetic
release mechanism for experimentation, the possible functions that were useful to have during
the experimentation were discussed.
The selected functions were as follows:
 The ability to change the EM voltage, which would allow the force at which the brick
cracked to vary. This was necessary to model the influence of different strengths of the
COD bricks under impact; this allowed modelling of bricks of varying strengths due to
varying levels of degradation (similar to the real life scenario).
 The ability to trigger the brick to crack at specified times during a dynamic test.
 To have sensors that monitor the displacements of the two halves of the bricks and
which can be calibrated and coded to trigger the release of the brick once a force has
impacted it.
The restructuring of the Arduino architecture that is outlined in Figure 4.6 allowed the user to
achieve these functions by providing switches that could be turned on or off depending on the
mode required. Once selected, each mode had a test requirement that was run in a loop by the
microcontroller. If the criteria for that test were met, it caused an action to be completed by the
microcontroller using functions which controlled the Pulse Width Modulation (PWM). This in
turn controlled the voltage of the electromagnets (see Figure 4.4).

18
PWM was required to transform the digital
voltage output from the Arduino into a variable
voltage output to the electromagnets. Digital
signals are either fully on, ‘HIGH’, or fully off,
‘LOW’. However in order to vary the voltage
the signal needed to be able to output all of the
numbers between HIGH and LOW. In order to
vary a digital output between these extremes,
PWM was used to vary the proportion of the
period where the pulse was HIGH rather than
Figure 4.6 - Architecture of the developed Arduino code
Initialisation
Setup procedure: Arduino input integers, Pulse Width Modulation and pin modes
Selection of mode
In order to determine desired function, select a mode:
Mode 1: Use serial monitor to change electromagnet voltage
Mode 2: Trigger mode to allow timed cracking of brick during testing
Mode 3: Hall sensor mode to crack the brick at a certain impact force
Actions
Functions that conduct desired action of
microcontroller:
1. SetCurrent: Function with input
argument of required voltage. The function
writes the voltage to the electromagnets.
2. BreakBrick: Uses SetCurrent function to
ensure the cracking of the brick. Reverses
voltage to a low negative voltage to remove
coercive force for a few milliseconds. This
then returns the voltage to zero.
Mode tests
Tests in current mode to determine
action of microcontroller:
Mode 1 test: Read serial monitor and
set EM voltage to serial value using
SetCurrent function
Mode 2 test: If TriggerPin = on,
then run BreakBrick function
Mode 3 test: If Δ Hall Sensor reading
> calibrated value then run BreakBrick
Loop
Pass Test
Figure 4.7 – Varying duty cycles with Pulse
Width Modulation (Protostack, 2011)

19
LOW (see Figure 4.7). The cycle had a very high frequency and as a result the voltage output
was smoothed from an oscillating square wave into a constant value. This was how a digital
output was made to simulate an analog output. PWM was achieved in the Arduino code by
utilising the internal clock functions built into the microcontroller; the duty cycle was changed
by writing a value to the OCR1A Register in the Arduino code (AMTEL, 2009: 136). This was
done in the initialisation procedure of the Arduino code (see Figure 4.6).
The process of debugging the code is shown in Figure 4.2. It was achieved by connecting the
serial port on the Arduino via a USB port to a computer. This allowed values that were
produced in the loop to be printed on the computer screen so that the user could understand
and check the operation of the Arduino.
4.5 Final developments to enable experimentation
There were a few final hardware changes that were
necessary in order to facilitate the planned
experimentation. Firstly, the existing wires connecting
the Arduino to the power supply were too short to reach
outside the shaking table from the array. It was necessary
to solder a new reel of three wires into the breadboard.
They needed to be roughly 3m long and connect the
ground and live wires to a power supply. The third wire
connected the signal trigger wire from a digital input pin
to the signal wiring of the shaking table (see Figure 4.8).
This would allow the control room computer to trigger
the cracking of the brick at a specified time during a test
(refer to Section 6.2.1 for further detail).
Secondly, the Arduino microcontroller needed to be mounted either inside the COD brick or
on the edge of the SLA restraint in order to protect the fragile electronic components from
damage during a dynamic test. Mounting the Arduino inside the brick was a more sensible
solution, and it allowed the Arduino to be connected to a laptop easily for debugging. In order
to secure it to the COD brick a hole was drilled and a thread tapped with a die through the
breadboard and into the COD interior wall. This allowed a screw and spacer to be threaded
through both to secure the assembly tightly in place inside the brick (see Figure 4.8).
Figure 4.8 - Final completed
hardware ready for testing with
Arduino microcontroller mounted
in place inside the COD brick

20
5 INTACT ARRAY TESTS
5.1 Objectives and test justification
The primary objective of the intact array tests was to develop an understanding of how to
conduct dynamic tests on the shaking table and how to assemble the single layer array. Being
familiar with the instrumentation and understanding the data transfer procedure were vital in
order to replicate the process later for the COD brick tests.
A secondary objective of these tests was to compare the results of simulation shakes run in
SOLFEC to the actual response of the same shakes using the intact SLA model. This
comparison allowed analysis of the SOLFEC model to determine whether some of the required
input parameters that were selected and introduced into the model were providing realistic
simulations of the actual response (Brasier, 2014). This was done independently of this
research project as a part of the ongoing programme of research at the University of Bristol.
5.2 Installation process
Firstly, glass beads were homogeneously spread across the SLA restraint surface after it had
been cleaned thoroughly. The SLA restraint was then transferred onto the shaking table and
the array components were assembled inside the restraint. The gantries in Figures 5.1 and 5.2
were used to safely reach all areas of the array. The reflective markers were arranged on the
array according to the configuration in the method statement (Dihoru et al, 2014b) and a
positioning guide tool was used to locate the reflective markers in the same place on each brick.
Figure 5.1 – Installation of glass beads and
SLA on shaking table using access gantries
Figure 5.2 - Gantries over rig with
ladder to install cameras

21
5.3 Issues identified during experimentation
Identification of the reflective markers was necessary before the testing could commence.
However there were incorrect markers being identified by the Qualisys system. This was
attributable to a number of causes. The glass beads and reflective metal surface of the SLA
restraint were causing interference below the level of the markers. The SLA restraint had a
number of additional reflective surfaces (see Figure 5.3) that could have been reflecting light
and causing light interference. The cameras were also set at a further distance from the SLA
than they would have been for MLA tests. As a result, the software found the correct
identification of markers more difficult.
5.4 Solutions
Most identification errors occurred near the centre
of the array where a high concentration of
reflective markers and glass beads were present.
There were identification errors due to light
interference. In order to reduce this interference,
tape was used to conceal reflective surfaces on the
SLA restraint. Cardboard circles were also cut out
and placed over bricks in the centre of the array to
hide the glass beads. In some cases, larger
reflective markers were used in place of the
standard markers and they were spaced further
apart to make it easier for the vision system to
identify them.
5.5 Instrumentation
5.5.1 Infrared Vision System (VS)
(+/- 0.5mm precision)
Five VS cameras (Figure 5.4), were mounted to the steel
frame surrounding the shaking table. They were located at
the four corners of the SLA restraint and one above the
array to ensure that the entire volume of space was tracked
by multiple cameras at all times. A minimum of three
Figure 5.4 - Vision System
camera mounted on steel
frame using a ladder
Figure 5.3 – Assembled intact array
with arrows pointing to reflective
bolts which held the restraint edge
bricks securely in place

22
cameras were required for the system to be able to perceive depth. Ladders were used (Figures
5.2 and 5.4) to install the cameras and the full details of the installation process are outlined in
(Dihoru et al, 2013b). A signal cable in series connected each camera in a daisy chain and the
output was connected to a computer with Qualisys software installed on it.
In order to calibrate the system, a T shaped wand (Figure 5.5), was moved through the air above
the SLA whilst being rotated. The precision of this process was governed by the number of
positions of the wand that were captured by the VS cameras. The more positions that were
captured, the more precisely the software could triangulate the positions of the cameras. The
wand had reflective markers at its tips and the coordinates of these markers were tracked and
recorded by the cameras. The system triangulated from these coordinates in order to precisely
define the location of each camera in three dimensional space. Subsequently, the cameras could
then find the positions of infra-red markers on the array via the same process. The SLA was
covered with flysheets (Figure 5.6), so that the VS only tracked the markers on the tips of the
wand during the procedure and not the markers on the bricks.
5.5.2 High-Speed Video system (HSV)
(+/- 1mm precision)
The HSV hardware comprised of a single camera that was mounted directly above the centre
of the shaking table. In order to safely place a ladder against the steel frame, two gantries shown
in Figure 5.2 were placed across the SLA restraint to allow the ladder to be mounted. The HSV
camera was also connected to the same Qualisys system as the VS cameras.
Figure 5.6 - Calibration process with
calibration wand being waved above the
rig, and white flysheets used to cover the
reflective markers
Figure 5.5 - Calibration wand showing T
shaped end with reflective markers

23
6 INTRODUCING THE COD BRICK INTO THE ARRAY
6.1 Assembly and instrumentation
Once the COD brick was fully developed, debugged, and prepared for testing, the SLA was re-
assembled on the shaking table with the same procedures described in Section 5.2. The COD
brick was inserted into the array within arm’s reach for ease of access, and replaced an intact
lattice fuel brick (see Figures 6.1 and 6.2).
There were a few initialisation procedures to go through in order to prepare the COD brick for
the tests. The first tests, T1-T3 (see Appendix 12.6), were used to check the high-speed video
camera (HSV) system was recording properly and that the camera was in the right position to
record the full array. For the purposes of these tests it was regarded as unnecessary to use the
infrared vision system (VS) and the reflective markers. The objective of this research project
was to integrate the COD brick successfully into the array, and be able to collect repeatable
results of the tests in order to see the effects of introducing the COD brick. The level of
accuracy provided by the HSV system was enough to meet the objectives. The extra
computational time the VS required for an incremental improvement of precision was
unnecessary. As discovered in the intact array tests, the set up process of the VS cameras with
Qualisys was far more time intensive and problematic.
Qualisys was set up to record the videos using the HSV camera with a recording time of 30
seconds at 25 frames per second. It was ensured that each recording captured a portion of video
at the start and the end of the shake when the array was stationary.
Figure 6.2 – Close up of intact array
with crack on demand brick
Figure 6.1 - Crack on demand
brick in the array

24
6.2 Test descriptions
6.2.1 Timed trigger function
This mode was selected by setting the pin 4 header
jumper on the Arduino to zero (see Figure 4.4). In
order to trigger the brick to crack at a chosen time,
the brick was connected to the control room
computer to synchronise the trigger with the shake.
The Z-axis movement of the table was used as a
trigger for the brick by ramping up through a Havertriangle waveform input (Figure 6.3). This
was a triangular waveform that was set to lift the table in the Z-axis and then return it to the
staring position. An output voltage was set to follow the amplitude of the Z-axis motion. An
output wire with that voltage was then connected to the Arduino through digital input pin 9
(see Figure 4.4).
The Arduino microcontroller had code written to it that read a voltage from pin 9, named
triggerPin (Figure 6.4). As the voltage increased with the table amplitude, if/when the pin read
the voltage as ‘1’ instead of ‘0’, it ran the ‘BreakBrick’ function to crack the brick (see Figure
6.5). A frequency of 0.05Hz was selected for the Havertriangle so that the trigger occurred at
five seconds into the shake (Figure 6.3). Five seconds was selected as the trigger time because
by that point the array was
expected to have settled down into
a relatively consistent response to
the shake.
6.2.2 Force function
Some of the experiments focused
on testing the force mode of the
COD brick. This mode was less
successful in achieving the objectives. An issue was discovered with the hardware in the COD
if (mode==2){ //if trigger mode is selected with header jumper connected to pin 4
pinState = digitalRead(triggerPin); //read the state of the trigger pin
if (pinState == 1) { //if the trigger pin connected to the table output reads a HIGH value
BreakBrick(); }} // this is the signal to run the BreakBrick function to trigger the brick
Figure 6.4 - Excerpt from Arduino code for trigger mode with explanatory comments
void BreakBrick() { // function to break the brick.
// assumes the brick was held with a positive current
SetCurrent(-10, verbose); //reverse EM current to
// break hysteresis loop of electromagnets
delay(200); // pause
SetCurrent(0, verbose); } // set EM current to zero
Figure 6.5 – BreakBrick function - Excerpt from
Arduino code with explanatory comments
Figure 6.3 - Havertriangle
waveform
Amplitude (mm)
Time (s)5
3.3

25
brick. The COD brick had header jumpers that were used to change the duty cycle of the PWM
and therefore the EM voltage (see Section 4.4). For the purposes of experimentation, any duty
cycle below 64% produced voltages that were too weak to hold the brick together and so it was
not useful in a dynamic test. The header jumpers (Figure 4.4) used as switches were coded to
vary the ‘holdvalue’ variable (see Figure 6.6). Changing the duty cycle from 64% to 100%
varied the EM voltage from 2.56V up to a maximum of 4V depending on those switches.
It was discovered during testing that a region in this range of voltages was not working with
the force mode. The brick would crack a few seconds after it was reset. This implied that the
hall sensors were being incorrectly triggered to run the ‘BreakBrick’ function. This could have
been due to noise in the sensors, although this was unlikely as the ‘breakvalue’ was calibrated
to be large enough so that the noise would not trigger the bricks to crack. Therefore the issue
was with the sensor values being recorded by the hall sensors (see Figure 6.7).
This was debugged by printing those ‘sensorValues,’ (Figure 6.7) for the two hall sensors to
the serial monitor of the Arduino microcontroller. The reason that the brick repeatedly cracked
was that one of the hall sensor values was changing rapidly at the start of each test before
settling down to a constant reading. There may have been some electronic interference between
the hall sensor and either the circuit board or the electromagnets. It was possible that each time
the brick was reset, the interference changed the value that one of the hall sensors was
producing and caused the brick to crack immediately.
This hardware issue limited the range of forces at which the brick could be used. Despite this
the force mode was not entirely unsuccessful. It was still possible to vary the EM force but the
range of usable values was restricted. This problem could be solved by shielding the hall
sensors from interference or using a different type of sensor that would not receive interference
from the electromagnets or the circuit board.
holdvalue=(163+(digitalRead(iPin10)+digitalRead(iPin11)*2+digitalRead(iPin12)*4+digi
talRead(iPin6)*8+digitalRead(iPin5)*16)*3); //change switches to vary the holdvalue
Figure 6.6 - Excerpt from Arduino code that reads the state of the header jumper switch
and changes the PWM ‘holdvalue’ to change the duty cycle
if (abs(sensorValue1-InitSensorValue1)>breakvalue || abs(sensorValue2-
InitSensorValue2)>breakvalue) { // if the absolute change in either of the two hall sensors
BreakBrick(); // sensorValue is larger than the threshold breakvalue, run BreakBrick
Figure 6.7 - Excerpt from Arduino code for reading either hall sensor and triggering
the break to occur when a large enough change in the sensor reading is recorded

26
7 DATA PROCESSING
7.1 Data processing procedure
In order to analyse the data, several steps were taken to convert the raw data to the stage where
it could be manipulated. A series of computer programmes allowed this processing to be done
quickly with plenty of scope for changing the desired output for analysis. The full flow chart
of the procedure for processing the data from the tests is described in Figure 7.1.
Figure 7.1 – Flow chart of data processing procedure
DYNAMIC TEST
High-speed video camera recorded test
and it was saved by the Qualisys
software as an .avi file
LabVIEW identified and labelled
interstitial bricks in each video frame
LabVIEW produced a Text file with X
and Y coordinate data in pixels
MATLAB code converted from pixels
to millimetres and processed data
Relative displacement-time graphs Contour and Surf plots
Comparison of tests
Video Files (.avi format)
0 5 10 15 20 25 30 35
-6
-5
-4
-3
-2
-1
0
1
2
3
4
T4 - Y Displacement of IB No.4 Relative To SLA Restraint
Time (Seconds)
RelativeDisplacement(millimetres)
0 5 10 15 20 25 30 35
-6
-5
-4
-3
-2
-1
0
1
2
3
4
Peak (mm) =3.7102
Trough (mm) =5.122
Range (mm) =8.8322
T12 - Y Displacement of the SLA Relative To SLA Restraint, Frame No. 295
YCoordiante
X Coordiante
0
100
200
300
400
500
600
700
800
900
1000
0 100 200 300 400 500 600 700 800 900 1000
-5
-4
-3
-2
-1
0
1
2
3
4

27
7.1.1 Qualisys Track Manager
During each dynamic test, a video of the array moving was recorded using the high-speed
vision camera mounted directly above the shaking table. The frame rate of the video was
controlled using the Qualisys Track Manager software, and for all of the tests it was set to 25
frames per second and recorded for 30 seconds. The software then processed the video and
saved it as an .avi video file.
7.1.2 LabVIEW
LabVIEW (Laboratory Virtual Instrument Engineering Workbench) was the software platform
programmed used to recognise the shape of the reference marker on the SLA restraint in a
video frame. It then recognised, labelled and tracked the movements of shapes in the array
which were the same shape as that marker. In this series of tests, the reference marker was the
shape of an interstitial brick. In every video frame, LabVIEW measured the location in space
of every recognised interstitial brick. It then produced a four-column text file for each test. The
four columns displayed the frame number,
the label number of the brick, and its X
and Y coordinates in pixels for every
video frame (Figure 7.2).
7.1.3 MATLAB
MATLAB is a programme that allows the user to produce a code with the ability to perform
computational tasks. It operates using matrices and a variety of in-built functions, and is able
to produce a range of visual data plots. This made it suitable for managing large text files such
as the ones obtained from LabVIEW, as well as analysing data.
Figure 7.3 – Offset removal process to get relative displacement from total displacement.
Brick A is an interstitial brick in the SLA, Brick B is the SLA reference marker
0
0
0
0
0
Y- displacement
relative to the SLA
restraint for brick A
t
y
t
y
t
x
t
t
y
y
Y- displacement
A - B =
Offset removed Y- displacement
A
B
Figure 7.2 – Snapshot example of a text file
Frame No. Label No. X Co-ord. Y Co-ord.

28
The MATLAB code imported a text file produced by LabVIEW and separated it into four
individual columns. Initial input parameters such as the label number of the reference marker
on the SLA restraint and the number of labels recognised were entered as variables manually.
Following this, the displacement in millimetres was found by applying a pixel conversion
factor (x2.16) to the displacement of all the interstitial bricks relative to the reference marker
on the SLA restraint.
7.2 Output
7.2.1 Displacement-time graphs
The actual and relative displacements in X and Y over time of every brick in the array could
be plotted in MATLAB. The 3D visual representation of the array using surface plots was
useful in order understand the SLA response as a whole, as there was a large amount of data to
interpret. However, displacement-time graphs showed the responses of individual bricks in the
array, which was useful for quantitative comparison of different tests. The peak displacements
of bricks could be calculated and also the exact timing of the cracking of the COD brick could
be verified. This was crucial to demonstrating the repeatability and reliability of the prototype
brick.
7.2.2 MATLAB Surface plots
Surface plots provided a clear visual representation of what was occurring in the array. Red
regions represent positive displacement and blue areas represented negative displacement, as
shown in Figure 7.1. Each frame of a test produces a surface plot figure of relative displacement
and then every figure was stitched together into an .avi video file. The video format was very
useful to qualitatively interpret the behaviour of the array. They provided a 3D view of the
relative displacements over time of the interstitial bricks.
7.2.3 MATLAB Contour plots
The contour plots produced in MATLAB plotted a 2D image of the relative displacements at
any particular time frame. The areas of positive displacement had red contours, with areas of
negative displacement having blue contours, similar to the surface plots. Contour plots
provided an aerial view of the surface plots. If a test was conducted where a crack on demand
brick cracked, it was possible to find the time frame when this happened and see exactly what
changes occurred in the array before and after the brick cracked.

29
8 RESULTS AND DISCUSSION
8.1 Introduction
The analysis of the data was simplified by
selecting four interstitial bricks (IB) in the
array in order to compare different tests. The
objective of the analysis was to assess the
performance and determine the repeatability of
the COD functions. Brick 4 was selected as it
was closest to the COD brick, and the greatest
effect was assumed to be located here (see
Figure 8.1). Bricks 1 and 2 were selected for
analysis to see if the COD had any effect
further away from the array. Brick 3 was not
used for the analysis. For each test the IB’s
were given different label numbers by
LabVIEW. The label numbers for each of the
four bricks in each test can be found in Appendix 12.7. The test (e.g. T4 or STU_A6)
descriptions and outcomes are outlined in Table 8.1 in this section. Surface and contour plots
were also analysed before and after a crack had occurred in order to assess what effect this had
on the array.
8.2 Performance of the crack on demand brick
8.2.1 Intact function (No cracking) (T7, T8, T9)
Although the creation of an intact function was not a primary objective of this research project,
it was necessary to demonstrate that the COD brick could behave like an intact lattice fuel brick
in the array. This analysis was required to indicate that the COD brick was a good
representation of an intact lattice fuel brick before cracking. Prior to inserting the COD brick
into the array for tests T7-T9, a 100% duty cycle firmly held the two parts of the brick together.
A significant amount of force was required to manually separate them. As a result, every test
where this function was deployed, the brick remained successfully intact for the full duration.
Through visual observations the brick was deemed to perform this function very successfully
and could be relied upon to repeatedly mimic the response of a standard intact lattice fuel brick.
1
2
3
4
Reference
Marker
COD
Figure 8.1 – Position in the array of the
reference marker, the four selected
interstitial bricks and the COD brick.
Label numbers in red.

30
8.2.2 Timed trigger function (T4, T12)
The COD brick was triggered through the shaking table using a Z-axis ramp that enabled the
brick to crack five seconds into a dynamic test (see Section 6.2.1). Three timed trigger crack
tests were conducted, T4, T10 and T12. Test T10 produced impractical data with extremely
high displacements for most interstitial bricks in the array. It is unclear why this happened and
the data was excluded. However the video for test T10 showed that the brick cracked at roughly
five seconds as expected. The data from tests T4 and T12 clearly demonstrated that the timed
trigger function worked successfully during a dynamic test. Interstitial brick number 4 (IB 4)
was compared in order to identify any clear changes during a test.
In all of the displacement-time graphs the time axis represents the length of the video recording.
The displacement-time graphs for tests T4 and T12 (Figures 8.2 and 8.3 respectively) show
that there is a sudden increase in the displacement of IB 4 relative to the restraint occurring
about five seconds into the shake (seven seconds into the video). It is not possible to be certain
whether the crack occurred at exactly five seconds as the graphs do not indicate the exact start
of the shake. However, the videos of these tests suggested the trigger function operated
successfully and accurately. Furthermore, human error was not a factor as the shaking table
controlled the voltage supplied to the electromagnets. As a result only mechanical error could
affect the accuracy of the timing.
During the series of force function tests, three doubly cracked bricks were introduced into the
array as shown in Figure 8.4. An X-axis motion was introduced to the shaking table. The force
settings were changed using the header jumpers (see Section 6.2.2) to vary the strength of the
hold of the brick. Three different scenarios were investigated using the same table settings (see
0 5 10 15 20 25 30 35
-6
-5
-4
-3
-2
-1
0
1
2
3
4
Time (Seconds)
0 5 10 15 20 25 30 35
-6
-5
-4
-3
-2
-1
0
1
2
3
4
Peak (mm) =3.7102
Trough (mm) =5.122
Range (mm) =8.8322
Figure 8.2 – T4, IB4 relative Y displacement
0 5 10 15 20 25
-6
-5
-4
-3
-2
-1
0
1
2
3
4
Time (Seconds)
0 5 10 15 20 25
-6
-5
-4
-3
-2
-1
0
1
2
3
4
Peak (mm) =3.3436
Trough (mm) =5.6723
Range (mm) =9.0158
Figure 8.3 – T12, IB4 relative Y displacement

31
Appendix 12.6). These scenarios were high force
(100% duty cycle), medium force (89.8% duty
cycle) and low force (72.2% duty cycle).
8.2.3.1 High force (STU_A5/A6/A7)
A 100% duty cycle was used for the high force tests
and for the intact tests T7, T8 and T9 as mentioned
in Section 8.2.1. Although the table had a larger
amplitude during the high force tests than the intact
tests, the COD brick remained intact as expected. In
test STU_A7 the brick was left in a pre-cracked
state.
8.2.3.2 Medium force (STU_A11/A12/A13/A14)
From test STU_A11 through to test STU_A14 the amplitude of the shaking table was gradually
increased (see Appendix 12.6). Test STU_A11 was conducted under the shaking table settings
used in all of the earlier STU tests, and the brick remained intact for the duration of the test.
The amplitude was increased by five millimetres in X and Y for test STU_A12, producing the
same result. The brick did not crack until the number of cycles were doubled in X and Y in test
STU_A13. The cracking occurred almost immediately as shown by the peak roughly one
second into the shake (Figures 8.5 and 8.6), with an almost identical result for test STU_A14.
The brick required a rapid shake at a high force to cause the brick to crack at the medium force
level. The brick was expected to crack when the table reached the selected amplitude, which
was at the beginning of a test. The immediate cracking implied that the force mode was working
as expected. A suggestion for further work would be to increase the amplitude of the shake
gradually and see if there is a relationship between the amplitude of the shake at the point of
cracking and the PWM duty cycle that determines the hold force.
Figure 8.4 – Location and
orientation of the three pre-cracked
bricks (green) and Crack on Demand
brick (yellow)
Figure 8.6 – STU_A13, IB4 relative Y
displacement
Figure 8.5 – STU_A13, IB4 relative X
displacement
0 5 10 15 20 25
-4
-2
0
2
4
6
8
STU-A13 - X Displacement of IB No.4 Relative To SLA Restraint
Time (Seconds)
0 5 10 15 20 25
-4
-2
0
2
4
6
8
Peak (mm) = 6.3151
Trough (mm) = 3.6555
Range (mm) = 9.9706
0 5 10 15 20 25
-2
-1
0
1
2
3
4
5
6
STU-A13 - Y Displacement of IB No.4 Relative To SLA Restraint
Time (Seconds)
0 5 10 15 20 25
-2
-1
0
1
2
3
4
5
6
Peak (mm) = 5.3327
Range (mm) = 7.0524

32
8.2.3.3 Low force (STU_A8/A9/A10)
Three low force tests were conducted in succession with identical shaking table input
conditions. Two of the three tests, STU_A9 and STU_A10, resulted in the brick cracking at a
particular load, while the brick remained intact in test STU_A8. The displacement range of the
displacement-time graphs was better at indicating the similarities between tests than the peaks
and troughs. This was because the same interstital brick in two repeat tests could have started
in different postions and therefore could have had different positive or relative displacements
to the frame.
A comparison between the displacement-time graphs for intact test STU_A8 and the force
crack test STU_A9 for IB 4 clearly indicated that the brick successfully cracked during the
STU_A9 test. There is a noticeable difference in the range of displacements in the two tests
and a visible change in the shape of the displacement-time graphs two seconds in to the shake
or roughly seven seconds into the video (see Figures 8.7 to 8.10).
displacement
displacement
0 5 10 15 20 25
-4
-3
-2
-1
0
1
2
3
Time (Seconds)
0 5 10 15 20 25
-4
-3
-2
-1
0
1
2
3
Peak (mm) = 2.6335
Trough (mm) = 3.853
Range (mm) = 6.4865
0 5 10 15 20 25
-4
-3
-2
-1
0
1
2
3
4
5
Time (Seconds)
0 5 10 15 20 25
-4
-3
-2
-1
0
1
2
3
4
5
Peak (mm) = 4.0527
Trough (mm) = 3.881
Range (mm) = 7.9337
displacement
displacement
0 5 10 15 20 25
-4
-3
-2
-1
0
1
2
3
4
5
6
Time (Seconds)
0 5 10 15 20 25
-4
-3
-2
-1
0
1
2
3
4
5
6
Peak (mm) = 5.4906
Range (mm) = 8.6033
0 5 10 15 20 25
-5
-4
-3
-2
-1
0
1
2
3
4
5
Time (Seconds)
0 5 10 15 20 25
-5
-4
-3
-2
-1
0
1
2
3
4
5
Peak (mm) = 4.1472
Trough (mm) = 4.631
Range (mm) = 8.7782

33
8.3 Repeatability of the crack on demand tests
8.3.1 Intact function (No cracking)
As concluded in Section 8.2.1, tests T7, T8 and T9 were conducted in succession and the brick
remained successfully intact for the full duration of each test. IB 1 and 2 were compared to
determine the repeatability of the intact function. The displacement-time graphs for IB 1 and 2
during tests T7, T8 and T9 are almost identical. The results from T7 and T8 are shown in
Figures 8.11 - 8.14. As well as the profile of the graph, the displacement ranges of the bricks
in the repeat tests are very similar. This suggests that the intact function is repeatable.
8.3.2 Timed trigger function
The IB 4 in tests T4 and T12 were compared to determine whether the timed trigger function
tests were repeatable. The results from the displacement-time graphs of IB 4 in Figure 8.2 and
8.3 clearly indicate that at five seconds into the two tests, the COD brick cracked when it was
triggered. The range of displacements of 8.8322mm and 9.0158mm for tests T4 and T12
respectively show that the brick is behaving almost identically across the two repeat tests. This
implies that the timed trigger function test is repeatable. However, due to time constraints in
0 5 10 15 20 25
-4
-3
-2
-1
0
1
2
3
Time (Seconds)
0 5 10 15 20 25
-4
-3
-2
-1
0
1
2
3
Peak (mm) =2.5852
Trough (mm) =3.3678
Range (mm) =5.953
0 5 10 15 20 25
-4
-3
-2
-1
0
1
2
3
Time (Seconds)
0 5 10 15 20 25
-4
-3
-2
-1
0
1
2
3
Peak (mm) =2.8372
Trough (mm) =3.213
Range (mm) =6.0502
0 5 10 15 20 25
-2
-1
0
1
2
3
4
5
Time (Seconds)
0 5 10 15 20 25
-2
-1
0
1
2
3
4
5
Peak (mm) =4.2243
Trough (mm) =1.2059
Range (mm) =5.4302
0 5 10 15 20 25
-2
-1
0
1
2
3
4
5
Time (Seconds)
0 5 10 15 20 25
-2
-1
0
1
2
3
4
5
Peak (mm) =4.0373
Trough (mm) =1.0236
Range (mm) =5.0609
Figure 8.13 – T8, IB1 relative Y displacement Figure 8.14 – T8, IB2 relative Y displacement
Figure 8.11 – T7, IB1 relative Y displacement Figure 8.12 – T7, IB2 relative Y displacement

34
the test schedule, it was not possible to conduct additional repeat tests to show statistical
significance of this result. It is expected that these additional tests would produce a comparable
result.
Tests STU_A8, STU_A9 and STU_A10 were conducted consecutively with the expectation
that the COD brick, using the low force setting, would crack under a particular load during the
test. However as shown Section 8.2.3.3, the brick failed to crack during STU_A8 and remained
intact. STU_A9 and STU_A10 were therefore compared to investigate the repeatability of this
test function. Again, IB 4 was considered as it was affected the greatest amount by changes to
the COD brick. This would enable simple identification of differences.
The displacement-time graphs for IB 4 for tests STU_A9 and STU_A10 display obvious
similarities in the profile of the graphs. Figures 8.15, 8.16 and 8.18 display a clear change at
seven seconds. Figure 8.17 is less clear but the overall response suggests that these were
repeatable tests.
0 5 10 15 20 25
-5
-4
-3
-2
-1
0
1
2
3
4
5
Time (Seconds)
0 5 10 15 20 25
-5
-4
-3
-2
-1
0
1
2
3
4
5
Peak (mm) = 4.1472
Trough (mm) = 4.631
Range (mm) = 8.7782
displacement
0 5 10 15 20 25
-6
-4
-2
0
2
4
6
Time (Seconds)
0 5 10 15 20 25
-6
-4
-2
0
2
4
6
Peak (mm) = 5.4184
Range (mm) = 9.9878
displacement
0 5 10 15 20 25
-4
-3
-2
-1
0
1
2
3
4
5
6
Time (Seconds)
0 5 10 15 20 25
-4
-3
-2
-1
0
1
2
3
4
5
6
Peak (mm) = 5.4906
Range (mm) = 8.6033
displacement
0 5 10 15 20 25
-3
-2
-1
0
1
2
3
4
5
6
Time (Seconds)
0 5 10 15 20 25
-3
-2
-1
0
1
2
3
4
5
6
Peak (mm) = 5.7828
Range (mm) = 8.586
displacement

35
Test Name Test Description and settings COD brick result
T1, T2, T3 Setting up video recording instrumentation -
T4 Z axis trigger - Set to crack after 5 seconds TRIGGER CRACK – 5 SECONDS INTO TEST
T5 Incorrect table settings -
T6 Z axis not enabled to trigger, should stay intact Did not stay intact due to loose wiring, hardware problem solved
T7 Z axis not enabled to trigger, should stay intact Stayed INTACT
T8 Repeat T7, Z axis not enabled to trigger, should stay intact Stayed INTACT
T9 Repeat T8, Z axis not enabled to trigger, should stay intact Stayed INTACT
T10 Z axis trigger - Set to crack after 5 seconds TRIGGER CRACK – 5 SECONDS INTO TEST
T11 Same settings but leaving cracked in array PRE-CRACKED
T12 Resetting brick, repeat of T10 to crack after 5 seconds TRIGGER CRACK – 5 SECONDS INTO TEST
T13 Same settings but leave cracked, repeat of T11 PRE-CRACKED
T14 Introduce Force function Stayed INTACT
T15 Force function Stayed INTACT
testing paused to fix force mode noise problem (see Section 6.2.2)
Change of orientation of brick at 45 degree angle to X and Y
STU_A1 Incorrect video settings -
STU_A2 Leave cracked PRE-CRACKED
STU_A3 Force function FORCE CRACK, broke roughly 12 seconds in to video
STU_A4 Force function, High force Stayed INTACT
3 Pre-cracked Bricks introduced
STU_A5 Low table amplitude, Force function, High force Stayed INTACT
STU_A6 Increased table amplitude, Force function, High force Stayed INTACT
STU_A7 COD Brick left cracked PRE-CRACKED
STU_A8 Force function, low force Stayed INTACT
STU_A9 Force function, low force FORCE CRACK, roughly 8 seconds in to video
STU_A10 Force function, low force FORCE CRACK, roughly 7 seconds in to video
STU_A11 Force function , medium force Stayed INTACT (noise problem if pin 10 closed)
STU_A12 Force function , medium force Stayed INTACT
STU_A13 Force function , medium force FORCE CRACK, higher frequency, longer cycles / cracks
STU_A14 Force function , medium force FORCE CRACK, attack changed to 13secs / cracks
Table 8.1 –Test Names, Test Description and settings, and outcomes of tests

36
0
500
10000 100 200 300 400 500 600 700 800 900 1000
-2
-1
0
1
2
3
4
5
6
Y Coordiante
X Coordiante
YDISPLACEMENTRELATIVETOTHESLARESTRAINT(mm)
Peak (mm) = 3.7641
YCoordiante
X Coordiante
0
100
200
300
400
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600
700
800
900
1000
0 100 200 300 400 500 600 700 800 900 1000
-5
-4
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Figure 8.20 - T12 Surface and Contour Plots, Frame No. 155
YCoordiante
X Coordiante
0
100
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300
400
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600
700
800
900
1000
0 100 200 300 400 500 600 700 800 900 1000
-5
-4
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500
10000 100 200 300 400 500 600 700 800 900 1000
-2
-1
0
1
2
3
4
5
6
Y Coordiante
X Coordiante
Peak (mm) = 4.2018
STU-A10 - Y Displacement of the SLA Relative To SLA Restraint, Frame No. 163
YCoordiante
X Coordiante
0
100
200
300
400
500
600
700
800
900
1000
0 100 200 300 400 500 600 700 800 900 1000
-5
-4
-3
-2
-1
0
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5
0
500
10000 100 200 300 400 500 600 700 800 900 1000
-2
-1
0
1
2
3
4
5
6
Y Coordiante
X Coordiante
Peak (mm) = 5.6671
Figure 8.24 - STU_A10 Surface and Contour Plots, Frame No. 163
0
500
10000 100 200 300 400 500 600 700 800 900 1000
-2
-1
0
1
2
3
4
5
6
Y Coordiante
X Coordiante
Peak (mm) = 5.7507
YCoordiante
X Coordiante
0
100
200
300
400
500
600
700
800
900
1000
0 100 200 300 400 500 600 700 800 900 1000
-5
-4
-3
-2
-1
0
1
2
3
4
5
Figure 8.26 – STU_A10 Surface and Contour Plots, Frame No. 310
0
500
10000 100 200 300 400 500 600 700 800 900 1000
-6
-5
-4
-3
-2
-1
0
1
2
Y Coordiante
X Coordiante
Peak (mm) = 4.9756
YCoordiante
X Coordiante
0
100
200
300
400
500
600
700
800
900
1000
0 100 200 300 400 500 600 700 800 900 1000
-5
-4
-3
-2
-1
0
1
2
3
4
0
500
10000 100 200 300 400 500 600 700 800 900 1000
-6
-5
-4
-3
-2
-1
0
1
2
Y Coordiante
X Coordiante
Peak (mm) = 5.1063
YCoordiante
X Coordiante
0
100
200
300
400
500
600
700
800
900
1000
0 100 200 300 400 500 600 700 800 900 1000
-5
-4
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-2
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3
4
YCoordiante
X Coordiante
0
100
200
300
400
500
600
700
800
900
1000
0 100 200 300 400 500 600 700 800 900 1000
-5
-4
-3
-2
-1
0
1
2
3
4
5
0
500
10000 100 200 300 400 500 600 700 800 900 1000
-6
-5
-4
-3
-2
-1
0
1
2
Y Coordiante
X Coordiante
Peak (mm) = 4.9798
0
500
10000 100 200 300 400 500 600 700 800 900 1000
-6
-5
-4
-3
-2
-1
0
1
2
Y Coordiante
X Coordiante
Peak (mm) = 4.0799
YCoordiante
X Coordiante
0
100
200
300
400
500
600
700
800
900
1000
0 100 200 300 400 500 600 700 800 900 1000
-5
-4
-3
-2
-1
0
1
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4
5

37
8.4 Effect of the crack on demand brick on the SLA
Surface and contour plots were also used to assess the effect of the COD brick on the rest of
the array. These plots enabled clearer 3D visualisation of the effects rather than observing the
displacement-time graphs of individual interstitial bricks. The SLA restraint reference marker
was located near to the coordinates (80, 180) on the surface and contour plots. In order to assess
the effect of the COD brick in a timed trigger test, four frames from test T12 were compared.
Figures 8.19 and 8.20 represent the relative displacement of the array before the crack occurred,
while Figures 8.21 and 8.22 display the relative displacement of the array after the COD brick
had cracked. In each of the before and after cases, one of the surface plots demonstrates the
positive relative displacements at a maximum point while the other represents the negative
relative displacements at a maximum point. Figures 8.20 and 8.22 reveal that the effect of the
cracking on the positive relative displacements is negligible. However, Figures 8.19 and 8.21
demonstrate that the negative relative displacement of the bricks in the array are affected by
the cracking of the brick.
Figure 8.21 shows that the cracking of the COD brick caused an increase in the negative peak
displacements in the area around it. Figure 8.21 also indicates a visible reduction in the relative
displacements of the opposite side of the array. Additionally the displacements of the array
further away from the COD brick, near to the SLA restraint, were less affected by the
introduction of the COD brick. A very similar result is visible in the surface plots for test T4
(Figures 8.27 and 8.28). There was approximately a 5% increase in the negative relative
displacement around the COD brick after cracking in test T4. Tests T4 and T12 were very
similar experiments, which therefore established that these results were not anomalous. A
Figure 8.27 – T4, relative Y displacement
surface plot – frame 203
Figure 8.28 – T4, relative Y displacement
surface plot – frame 303
0
500
10000 100 200 300 400 500 600 700 800 900 1000
-6
-5
-4
-3
-2
-1
0
1
2
Y Coordiante
X Coordiante
Peak (mm) = 4.4212
0
500
10000 100 200 300 400 500 600 700 800 900 1000
-6
-5
-4
-3
-2
-1
0
1
2
Y Coordiante
X Coordiante
Peak (mm) = 4.6576

38
sharper peak is observed at the location of the COD brick in test T4 and T12 before cracking
had occurred. This could possibly have been due to the mass of the COD brick being greater
than an intact lattice brick which resulted in larger displacements in that area.
Figures 8.23 to 8.26 display the relative displacement in the Y direction before and after the
brick cracked for test STU_A10 (medium force). The shaking table was also moving in the X
direction for this test, and as a result the array was moving diagonally towards the reference
marker and then back towards the area where there COD brick was located. As the array moved
towards the reference marker, the displacement relative to the frame was positive (Figure 8.24).
The majority of bricks in the array then returned approximately to their starting positions once
the table had reversed its direction, as shown by the shallow contours in Figure 8.23 denoting
small relative displacements. However, the area where the COD brick and three doubly cracked
bricks were located continued to move away from the restraint marker. This behaviour is
exhibited by the steep contours in Figure 8.23. Once the brick had cracked, the size of both the
negative and positive peaks were amplified (see Figures 8.25 and 8.26 respectively).
The changes to the array, before and after a crack, appeared to be more obvious during timed
trigger function tests where no doubly cracked bricks were present (see Section 8.2.2). During
the force function tests, where they were present, the differences between the relative
displacements before and after cracking were less pronounced (Figures 8.23 – 8.26). The
doubly cracked bricks reduced the locking effect of the keys in the array. Reduced locking
caused the array to move more as a whole. Therefore the effect of the COD brick cracking was
reduced. This was due to a smaller proportion of the total changes in relative displacements
being attributable to the COD brick.
There were some problems with the STU test results which mean that important information
about specific areas of the array was lost. This was due to some of the interstitial bricks
displaying NaN values, while others in the array exhibited extremely high displacement values.
This was usually concentrated in one area near the COD brick, although this was also visible
in other minor cases in the array. It is unclear what caused these anomalies.
8.5 Further Work
The main limitation of this research project was the reliability of the force function which
appeared to be temperamental, even after the initial issues with the hall sensors (see Section

39
6.2.2) were resolved after test T15. Demand for the shaking table at the University of Bristol
meant that a limited number of repeat tests could occur. The results suggested that the low
force function could produce the same result repeatedly (see Section 8.2.3.3). However, in
order to confirm this, more tests would need to be conducted as only two were successful.
Additionally, the COD brick remained intact when using
higher duty cycles in other tests. Consequently it was difficult
to measure the reliability of this function with limited data of
successful crack on demand tests. It is recommended that
future tests should be conducted with the brick set to lower
duty cycles, and conduct them a minimum of five times to
ensure the repeatability of this function.
It is also recommended that the COD brick is set to the force
function without any doubly cracked bricks so that the isolated effects of this function can be
observed. This could be compared against the timed trigger function. Furthermore, while
keeping the same shaking table input setting, every possible brick orientation should be tested
during a series of repeat tests at the same duty cycle. This is recommended in order to see what
the effect of just the orientation of the brick would have on the COD brick breaking.
Once the force mode and timed trigger mode are deemed fully functional, much smaller and
lighter boards should be manufactured, with grooves built into the bricks like the instrumented
bricks used in the MLA (Figure 8.29). The hall sensors and magnets could be mounted inside
the inside faces of the bricks when manufactured. Eventually, mulitple COD bricks could be
introduced in to the array. Using the force function, it would be interesting to observe whether
placing a series of COD bricks in a line in the array would induce a cascade of cracks in the
COD bricks during a dynamic test. Cracking causes larger localised displacements in the array,
thereby increasing the possibility of a nearby COD brick cracking. This could occur in a real
life AGR core during a seismic event. Furthermore, the instrumentation from the COD brick
could be inserted into the MLA doubly cracked bricks in order to see the effects on the MLA.
Finally, there were some problems with all of the STU tests as mentioned at the end of Section
8.4. If this is a recurring problem in future tests then tests should be repeated until the correct
result is achieved. This is recommended in order to retain valuable information about the
interstitial brick displacements.
Figure 8.29 – MLA
instrumented brick

40
9 CONCLUSIONS
The purpose of this research project was to develop a prototype lattice fuel brick that could
change from an intact to a cracked state during a shaking table test, and then to integrate it into
the SLA and observe the behaviour of the brick and the array. This was proposed because
previous work identified the possibility that weakened bricks could crack during seismic
events. However, current computer models of cracking in AGR cores do not take this into
account. Therefore there was a need to investigate this unknown effect and its implications.
In order to create a functioning COD brick, some development was required before it could be
introduced to the SLA. The brick had a timed trigger function coded into the microcontroller
and synchronised with the control room computer. By doing this the brick could be triggered
to crack on demand during a dynamic test. Repeat tests showed that this function was reliable.
The brick performed well at simulating the behaviour of an intact brick and then fully cracking
during dynamic tests. The displacement-time graphs of interstitial bricks near the COD brick
show an increase in relative displacements after cracking.
In addition, a force function to vary the strength of the brick was designed. The motivation for
this was to be able to model weakened bricks in an AGR core that could crack under a certain
load. This was less successful due to problems with the electronics that made the function
unreliable during tests. However, it was possible to vary the voltage in the electromagnets and
therefore the force holding the two halves of the brick together. Two repeat tests did suggest
some repeatability but further tests are required to confirm this at different EM duty cycles.
The surface and contour plots produced in MATLAB indicated an increase in displacements
near to the COD brick after cracking. A reduction in displacements in the other half of the array
after cracking were observed. This was possibly to be due to the fact that the bricks around the
COD brick were moving more, thereby reducing the amount of movement required elsewhere
to dissipate the energy added to the SLA by the dynamic motion. Another explanation of this
observation was that after the cracking of the COD brick, the contact forces between array
components and the COD brick would be smaller. Reduced contact forces applied by the COD
brick would cause the displacements in the other half of the array to reduce. The extra
movement around the COD brick after cracking was likely to be due to a reduction in the
locking effect of the keys when the COD brick cracked.

41
10 REFERENCES
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me [accessed on 23rd March 2015].

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Dihoru, L. et al, (2013b), Technical Note: EDF1201_TN20_v1 Graphite Core PLEX: Rig
Work for Seismic Behaviour with Cracked Bricks, Method Statement for the Single-Layer Rig
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Dihoru, L. et al, (2014a), Multi-Layer Array Rig Work For Seismic Behaviour With Cracked
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March 2015].
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PLEX: Rig Work for Seismic Behaviour with Cracked Bricks, Method Statement for the
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20Graphite%20in%20the%20UK%20Nuclear%20Industry.aspx [accessed on 14th
April
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11 ACKNOWLEDGEMENTS
We would like to thank and acknowledge our supervisor Dr Adam Crewe for his greatly
appreciated assistance on this project. His expertise with Arduino code and electronics and
earthquake engineering were invaluable as well as the regular assistance in encouraging and
guiding our research direction, report writing and learning valuable skills.
We would also like to thank all the research associates working in the department who helped
with the project by answering our questions. Special thanks to Dr Luiza Dihoru for her time
and assistance with Labview, Qualisys and data transfers and explaining and discussing the
complex laboratory equipment with us. Similarly thanks to Dr Olafur Oddbjornsson for his
assistance in running the control room computer that was vital to our experimentation.
Also many thanks to the laboratory technician, Dave, for his time and resources in sourcing
equipment in the laboratory and help with development and construction of the hardware in
COD brick.
Finally we would like to acknowledge EDF for the provision of funding towards the wider
research programme and for allowing the use of testing equipment e.g. SL restraint and array
and other equipment for our research purposes.

44
12 APPENDICES
12.1 Risk Assessment
Department Civil Engineering, University of Bristol
Room/Building Earthquake Lab, Queen’s Building
Students Vladimir Djuric and Leo Youngman
Supervisor Dr. Adam Crewe
Principal Activities
 Transfer of single layer rig on to shake table
 Constructing single layer array
 Calibration and installation of instruments including lighting rig
and camera systems
 Carrying out tests on the shake table using the single array for
uncracked and pre-cracked bricks and measurements
 Processing and transferring data via microDAQ
 Using a power supply and Arduino© boards to crack single layer
bricks on demand via built in electromagnets
 Working in queens building on research and write up of project
Risks Actions Taken To Mitigate Risks
Use of a power supply
A voltage of less than 25 volts must strictly be used when using a power
supply to avoid a serious electric shock. For the work undertaken only 4 volts
will be necessary. Care must be taken to ensure that the supply is switched
off when touching any components which conduct electricity. Time must
also be allowed for the capacitors to dissipate their stored charge.

45
Use of Arduino©
Boards and
microDAQs
The power will be switched off before touching the boards in case of
overheating. The voltage must not go above 6 volts for the Arduino board
otherwise there is a risk that the board can overheat and/or explode.
Sharp edges on
bricks/trapping fingers
The bricks being used have very sharp edges. Ensure that care is taken to
avoid trapping/cutting hands and fingers, especially when the magnets
connect together.
Use of soldering iron
The tip of the soldering iron is at an extremely high temperature and can burn
through skin with ease. Ensure that soldering iron is used carefully and
operator is fully aware of where the tip is at all times. Must be placed
correctly in the holder when not in use. If burnt, run affected area under a
cold tap for at least 10 minutes and seek medical attention.
Inhaling fumes from
solder
Fumes from the solder iron contain harmful toxics such as lead. Using a
solder fume extractor in the lab can mitigate the risk from exposure to the
fumes.
Standing on the shake
table
The table can only be stood on and the gated area surrounding it entered
when that table is completely switched off and then deemed safe to use.
Falling off the shake
table in to space below
There is no barrier preventing falling from the table into the maintenance
area below. The distance from the base of the area to the top of the table is
roughly over two metres. In order to mitigate the risks when working on the
table care must be taken at all times to maintain balance. If an activity is
considered dangerous it strictly must not be undertaken. Comfortable
footwear with grip must also be worn to avoid slipping.
Using the access
bridge
The access bridge will be place over the single layer rig in order to replace
uncracked bricks with pre-cracked bricks. Same procedures to those
mentioned on “Falling of the shake table” must be followed. Be very careful
to position feet correctly and keep your balance when you
Manhole cover
A manhole cover exists near the shake table for access to the maintenance
area below. Yellow and black safety tape has been taped around the area to
make all personnel aware of the area. It must be closed at all times.
Using the shake table Ensure that the table is operated by an appropriately trained member of staff.

46
Tripping on tubes and
cables and ratchet
straps around the
shaking table
Be aware of all cables and tubes in your vicinity whilst working in the
laboratory. Check where to place your feet when you are working in the very
confined spaces around the shaking table. Be aware of the trip hazard posed
by the ratchet straps used to hold the walkway extensions in place.
Cutting fingers on the
sharp edges of the
walkway extension
when erecting
Use gloves when putting up or taking down the walkway extensions. This is
a high risk activity and you should be very aware of your surroundings when
manoeuvring the walkways into place.
Glass beads getting in
your eye
Wear eye protection when handling the glass beads or vacuuming up the
glass beads.
Damage to eyes from
infra-red light
exposure
Ensure that personnel do not look into the bright lights used to light up the
shaking table.
Carrying heavy loads
Ensure that any heavy loads, such as the crates containing the bricks, are
carried in pairs. Take a safety awareness course on appropriate method for
lifting heavy loads.
Tripping over
Ensure that comfortable footwear with grip is worn, and care taken to avoid
walking on uneven ground surfaces. Be aware of your surroundings in the
laboratory whilst moving.
Tripping on Glass
Beads
Glass beads are almost invisible to the naked eye. The lab must be
thoroughly vacuumed frequently to try and ensure that they glass beads to
not become a hazard to personnel. Take special precaution not to drop these
anywhere in the lab.
Dust Exposure Ensure that the rig is covered with a tarpaulin or protective cover so that
smaller electrical components do not get damaged over time.
Fire and other
emergencies
Ensure that all personnel are familiar with fire exits within the lab and the
quickest exit from any area. Ensure that all personnel are aware of
emergency telephone numbers in case of an accident.
Signed Vladimir Djuric
(Student)
Leo Youngman
(Student)
Adam Crewe
(Supervisor)
Date 14/11/14 14/11/14 14/11/14

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