13
Quantitative
Risk Assessment
This
section of the EIA presents a summary of the analysis and findings of the Quantitative
Risk Assessment (QRA) study undertaken for the proposed LNG Terminal at Black
Point and associated facilities.
This section is divided into two sub
sections: section 1 relates to the general aspects of the QRA study, and
section 2 relates to the LNG Terminal.
Further details of the analysis
pertaining to the terminal QRA are contained in Annexes 13A1 through 13A7.
Additional
annexes are provided to describe the Safety Management System (Annex 13B) and summarise all the
assumptions adopted in the QRA study (Annex
13C).
13.1
Legislation Requirement and Evaluation Criteria
The
key legislation and guidelines that are considered relevant to the development
of the proposed LNG Terminal and associated facilities are as follows:
·
Gas Safety Ordinance,
Chapter 51
·
·
Dangerous Goods Ordinance,
Chapter 295
·
Environmental Impact Assessment
Ordinance (EIAO), Chapter 499
·
The EIA Study Brief, Section 3.7.9.1
There
is some overlap in the requirements of the various pieces of legislation and
guidelines. The requirement for a Hazard Assessment (HA) study is contained in
the EIAO and HKPSG. Such a study, although not required explicitly in
the Gas Safety Ordinance, is implied in the regulations and has been an
established practice for similar installations in the SAR.
13.1.1
EIAO
Technical Memorandum (EIAO-TM)
The
requirement for hazard assessment of projects involving storage, use and
transport of dangerous goods where risk to life is a key issue with respect to
Hong Kong Government Risk Guidelines (HKRG) is specified in Section 12 of the
EIAO-TM.
The
relevant authority for an QRA study relating to an LNG Terminal and associated
facilities is the Gas Standards Office (GSO) of the Electrical and Mechanical
Services Department (EMSD), as specified in Annex 22 of EIAO-TM.
Annex 4 of EIAO-TM
specifies the Individual Risk and Societal Risk Guidelines.
13.1.2
Risk
Measures and
Individual
risk is the predicted increase in the chance of fatality per year to a hypothetical individual who remains 100% of the time at a given stationary point.
The
individual risk guidelines require that the maximum level of off-site
individual risk associated with a hazardous installation should not exceed 1 in
100,000 per year i.e. 1 x 10-5 per year.
Societal
risk expresses the risks to the whole population. The HKRG is presented
graphically in Figure 13.1.
It is expressed in terms of lines plotting the frequency (F) of N or more deaths
in the population from incidents at the installation. Two FN risk lines are
used in the HKRG to demark “acceptable” or “unacceptable” societal risks. The intermediate region indicates the acceptability of societal
risk is borderline and should be reduced to a level which is “as low as
reasonably practicable” (ALARP). It seeks to ensure that all practicable and
cost-effective measures which can reduce risks will be considered.
Figure
13.1
13.2
Study Objectives and Methodology
The objective of the QRA study is to
assess the risk to life of the general public including the workers of nearby
plants from the proposed facilities during its operational phase. The results
of the QRA are compared with the HKRG.
The detailed requirements of the study
are (see Section 3.7.9.1 of the EIA
Study Brief):
·
To
identify all credible hazardous scenarios associated with storage, handling and
operation of the LNG facility, which has potential to cause fatalities;
·
To
carry out the QRA expressing population risks in both individual and societal
terms;
·
To
compare the individual and societal risks at the proposed development sites
with the HKRG;
·
To
identify and assess practical and cost effective risk mitigation measures as
appropriate;
·
To
identify all LNG leakage scenarios and propose a safety management system for
the operational phase of the project with an aim to contain any accidental
leakage in short notice and to prevent and/or minimise any leakage.
The
elements of the QRA are shown schematically in Figure 13.2.
An
overview of the methodology employed is provided here to briefly introduce the study approach, while the details
are included in the respective sections/ annexes.
Relevant
data on the proposed facilities such as their preliminary layout drawings and
design basis as well as population data in the vicinity were collected and reviewed.
A
Hazard Identification (HAZID) Study was conducted to identify all hazards, both generic and site
specific. A review of literature and accident databases were also undertaken.
These formed the basis for identifying all hazardous scenarios for the QRA
Study.
The
frequencies, or the likelihood, of the various outcomes resulting from an LNG/gas release scenario were derived
from historical databases and, where necessary, these were modified to take
into account local factors.
For
all identified hazards assessed as having a frequency of less than 10-9
per year, their frequency assessment will be documented but no quantification
of consequences will be performed.
For
hazards with frequencies greater than 10-9 per year, the
consequences of each release were modelled.
Hydrocarbon
releases have been modelled using the PHAST
consequence modelling package
developed by Det Norske Veritas,
Inc. (DNV)
The
consequence and frequency data were subsequently combined using ERM’s proprietary software RiskplotTM to
produce the required risk calculations.
Finally,
the results from the risk assessment were compared with the HKRG and found to
be acceptable. No mitigation measures are therefore proposed.
Figure
13.2 Schematic
Diagram of QRA Process
The
QRA study for the terminal includes all planned facilities at the site,
including unloading operations at the jetty, LNG storage tanks, sendout pumps, LNG vaporisers and the boil-off gas system.
This
section presents a summary of the hazard assessment study for the facilities at
the terminal while Annex 13A gives
further details.
As
per the Study Brief, the QRA study for the terminal is also required to include
the marine transit risks for LNG carriers within 500m of the jetty. A separate
Marine Quantitative Risk Assessment (MQRA) study has been conducted by DNV. The
risk results from the MQRA study for the 500m section at the jetty have been
combined with the risk results for the facilities at the terminal to produce an
overall risk result for the terminal, which is presented in this section. For
further details on marine transit risks, DNV’s report
may be referred.
13.3.1
Site
Facilities
The
proposed LNG Terminal and associated facilities will be built to provide a peak
natural gas sendout capacity of 1000 million standard
cubic feet per day (MSCFD).
The
Terminal will comprise the following primary components:
·
one jetty with a berth for LNG
carriers;
·
initially up to two 180,000m3
full containment LNG storage tanks (for Phase I,) followed by one
additional tank (for Phase II);
·
two in-tank LNG single stage
centrifugal pumps for each tank, capable of delivering LNG at about 7 barg;
·
four High Pressure LNG Booster pumps including one spare for Phase I
and three additional pumps for Phase II, to deliver at about 101 barg;
·
four including one spare (plus one
additional for Phase II) open-rack seawater vaporisers.
The
key features of the proposed LNG Terminal are depicted in the preliminary terminal
layout diagram (See Figure 3.1
in Section 3). LNG is transferred by pumps under cryogenic
conditions from the carrier to the tanks, where it is stored at near
atmospheric pressure. LNG from the tanks is pumped to the vaporisers where the
cryogenic LNG is converted into gas phase and the temperature raised to 5 °C
for sendout to the adjoining power station.
Figure
13.3 shows a schematic of the overall process in an LNG
terminal. A more detailed Process Flow Diagram for the Terminal, including
details on the design features and the operating philosophy are included in Annex 13A1. Further details of safety features and the Safety Management System
are provided in Annex 13B.
Figure 13.3 Process
Overview
13.3.2
Land Use
in the Vicinity
The current land use within a 2km
radius of the proposed site at Black Point includes
According
to data provided by Planning Department, Lung Kwu Sheung
Tan and the government land allocated for temporary use are the only areas
assumed to hold population within 2km radius of the Black Point site [1]. The
population in these areas was taken to be 100 persons for both years 2011 and
2021.
Lung Kwu Tan
village is situation 3km form the site and has a population of 753, predicted
to rise to 1,297 by the year 2021. To the north lies Ha Pak Nai
village with a population of 216.
Marine
population in the vicinity has been considered based on the marine traffic data
provided by BMT [2]; approximately 3-5 person/km2 is estimated in
the vicinity of Black Point.
Further details on land use adjoining
the proposed site, as well as the land and marine population surrounding Black
Point, are presented in Annex 13A2.
13.3.4
Weather Data
Weather data for the Black Point site
is based on data from Sha Chau
weather station which is the closest and most relevant. Details are presented
in Annex 13A3.
Hazards associated with the LNG
terminal have been identified based on a detailed review of known incident
records worldwide and experience gained from operations at similar facilities.
In addition, a systematic Hazard Identification (HAZID) process was undertaken to
identify any local or site specific factors.
13.4.1
Hazards
from LNG
LNG
is an extremely cold, non-toxic, non-corrosive and flammable substance. As LNG
is released from a temperature-controlled container, it will likely contact warm surfaces and air that transfer heat into
the liquid. The heat input begins to vaporise some of the liquid, returning
the liquid to the
gaseous phase.
The relative proportions of liquid and gaseous phases immediately following a
release depend on the release conditions. The liquid phase will form an LNG pool on the ground which will begin to “boil”,
due to heat input from the surrounding environment.
Immediately
following vaporisation, the gas is colder and heavier than the surrounding air
and forms a vapour cloud. As
the gas disperses, it mixes with the surrounding air and warms up. The vapour
cloud will only ignite if it encounters an ignition source while concentrated
within its flammability range.
Downstream
of the vaporisers the natural gas will be in the gas phase. A release from this
piping and equipment will result in a gaseous phase release directly.
13.4.2
Hazard
Effects
In the
event of an accidental release of LNG from piping or equipment, the
characteristics of the possible hazardous effects are described below.
Pool Fire
A
pool fire occurs when a flammable liquid is spilt onto the ground and ignited.
A pool formed from the release of liquid LNG will initially spread due to the
gravitational and surface tension forces acting on it. As the pool spreads, it
will absorb heat from its surroundings causing evaporation from the pool
surface. Ignition of this vapour leads to a pool fire.
Jet Fire
Jet
fires result from ignited releases of pressurised flammable gas or
superheated/pressurised liquid. The momentum of the release carries the
materials forwards in a long plume entraining air to give a flammable mixture.
Jet fires only occur where the LNG is being handled under pressure or when
handled in gas phase and the release is unobstructed.
Flash Fire
Following
an LNG release, a large proportion of the liquid will evaporate immediately to
form a cloud of methane, initially located around the release point. If this
cloud is not ignited immediately, it will move with the wind and be diluted as
a result of air entrainment. Similarly, a gas release may not be ignited
immediately and will disperse in the air.
The
dispersing vapour cloud may subsequently come in contact with an ignition
source and burn rapidly with a sudden flash. If the source of material which
created the cloud is still present, then the fire will flash back to the source
giving a pool fire, or if under pressure, a jet fire. Direct contact with the
burning vapours may cause fatalities but the short duration of the flash fire
means that thermal radiation effects are not significant outside the cloud and
thus no fatalities are expected outside of the flash fire envelope.
Vapour
Cloud Explosion
A
flash fire is the most likely outcome upon ignition of a dispersing vapour
cloud from an LNG release. If ignited in open (unconfined) areas, pure methane
is not known to generate damaging overpressures (explode). However, if the gas
is ignited in areas where there is significant degree of confinement and
congestion, such as the process areas, an explosion may result.
Fireball
Immediate
ignition of releases caused by a rupture in a gas piping may give rise to a
fireball upon ignition. Fireballs have very high thermal radiation, similar to
jet fires although the duration of the event is short.
To
summarise, a liquid phase release may result in a flash fire, vapour cloud
explosion, pool fire or jet fire. A gas phase release can result in a flash
fire, fireball or jet fire.
13.4.3
Review
of Industry Incidents
A
review of industry incidents at LNG terminal facilities was carried out.
Incident records over the last few decades show small LNG vapour releases and
minor fires with impact limited to within the plant boundary. These were
associated with leaks from valves and process equipment. There have been no
instances of leaks to the environment from full containment tanks. There have
been no injuries or fatalities recorded outside the plant boundary since 1944.
Other incidents have occurred during the construction and repair of LNG
facilities but no LNG was directly involved.
In
general LNG facilities have shown an exceptionally high safety record due to
the high level of safety features incorporated in an LNG terminal design
including the use of full containment tanks and emergency shutdown systems.
13.4.4
HAZID
Study
A
Hazard Identification (HAZID) Study was conducted in October 2005 involving
representatives from the Project Proponent: CLP and ExxonMobil and their expert
consultants: ARUP, Foster Wheeler and ERM. The
potential hazards posed by the facility were identified based on the HAZID
team’s expert opinion, past accidents, lessons learnt and checklists. The
details of the HAZID study can be found in Annex
13A4.
A
systematic approach was
adopted, whereby the facility was divided into a number of “subsystems” based
on the layout and the process; guidewords from the checklist (see Annex 13A4) were then applied to each subsystem as
relevant.
The Study
considered each area of the LNG Terminal and identified any potential hazards that apply to it. The study output served as a basis for identification of
scenarios for the QRA study.
13.4.5
Scenarios
for QRA Study
Scenarios
for the QRA study were identified based on the HAZID Study as well as a review
of incident records. Loss of containment events have been identified for each
section of the terminal, corresponding to the relevant process conditions, as
listed in Table 13.1.
A
detailed discussion on the hazards, particularly in relation to the LNG storage
tanks, is given in Annex 13A5.
Table
13.1 Scenarios
for QRA Study
|
Plant Section |
Initiating
Event |
Potential
Outcome Scenario |
|
Jetty Area Unloading arm Piping & equipment
at the jetty |
Leak, rupture |
Pool fire/Jet fire, Vapour
dispersion/ Flash fire |
|
Transfer Piping on Trestle Piping |
Leak, rupture |
Pool fire/Jet fire, Vapour
dispersion/ Flash fire |
|
Tank Area Piping on tank
roof Storage Tank |
Leak, rupture Rupture |
Pool fire/Jet fire, Vapour
dispersion/ Flash fire Pool fire, Vapour dispersion/
Flash fire |
|
Process Area (HP Pumps, Recondenser, Vaporisers)
Piping/equipment |
Leak, rupture |
Pool fire/Jet fire, Vapour
dispersion/ Flash fire/Vapour cloud explosion |
|
Process Area (Compressors)
Piping/equipment |
Leak, rupture |
Jet fire, Gas dispersion/Flash
fire, Fireball |
|
Sendout Piping |
Leak, rupture |
Jet fire, Gas dispersion/ Flash
fire, Fireball |
This
includes an assessment of the likelihood or the frequency of events resulting
in a hydrocarbon release from piping and equipment and the subsequent potential
outcomes such as fires. Details of the frequency analysis are provided in Annex 13A6.
Release
frequencies have been derived from generic data on loss of containment events.
Reference has been made to a number of sources. A summary is presented in Table 13.2. Release scenarios include a
range of hole sizes from small leaks to catastrophic rupture.
The
frequency of various outcomes following a loss of containment event is
estimated using an event tree model. The various outcomes considered include pool
fire, jet fire, flash fire and vapour cloud explosions for liquid releases, jet
fire and flash fire for continuous gas releases and fireball and flash fire for
instantaneous gas releases.
Table
13.2 LNG
Release Event Frequencies
|
Equipment |
Release
Scenario |
Release
Phase |
Release
Frequency |
Unit |
Reference |
|
Process
Vessels |
i)
10
& 25mm hole |
Liquid |
1.00E-05 |
per year |
Crossthwaite
et al [3] |
|
|
ii) 50 & 100mm
hole |
Liquid |
5.00E-06 |
per year |
Crossthwaite
et al |
|
|
iii) Full
bore rupture |
Liquid |
1.00E-06 |
per year |
Crossthwaite
et al |
|
Pumps |
i)
Leak |
Liquid |
1.00E-04 |
per year |
COVO Study
[4] |
|
|
ii) Full
bore rupture |
Liquid |
1.00E-05 |
per year |
COVO Study |
|
Unloading
Arm |
i)
Leak |
Liquid/ Gas |
4.05E-03 |
per year |
COVO Study |
|
|
ii) Full
bore rupture |
Liquid/ Gas |
4.05E-05 |
per year |
COVO Study |
|
Pipe size
600mm to 750mm |
i)
10 & 25mm hole |
Liquid/ Gas |
1.00E-07 |
per meter
per year |
Hawksley
[5] |
|
|
ii) 50 &
100mm hole |
Liquid/ Gas |
7.00E-08 |
per meter
per year |
Hawksley |
|
|
iii) Full
bore rupture |
Liquid/ Gas |
3.00E-08 |
per meter
per year |
Hawksley |
|
Pipe size
150mm to 500mm |
i)
10 & 25mm hole |
Liquid/ Gas |
3.00E-07 |
per meter
per year |
Hawksley |
|
|
ii) 50 &
100mm hole |
Liquid/ Gas |
1.00E-07 |
per meter
per year |
Hawksley |
|
|
iii) Full
bore rupture |
Liquid/ Gas |
5.00E-08 |
per meter
per year |
Hawksley |
|
LNG
Storage Tank |
i)
Rupture |
Liquid |
1.00E-08 |
per
tank-year |
“Purple
Book” [6] |
This
section gives a brief summary of the approach adopted to model the consequences
of an LNG/natural gas release. Details are given in Annex 13A7.
A range
of hole sizes from small leaks to full bore ruptures is considered in the
analysis. Discharge rates, dispersion modelling, pool fire modelling, jet fire
modelling, fire ball modelling and vapour cloud explosion modelling are
considered and are all performed using the PHAST
suite of models.
The
plant was divided into twenty three isolatable process sections based on the
provision of emergency shutdown valves. Physical properties of the fluid
(pressure, temperature, density, phase) and equipment dimensions (pipe diameter
and length) for each section were applied from the heat and mass balances to
estimate the maximum release rate and the inventory in each section.
Fire
radiation contours are calculated to 7.3, 14.4, 20.9 and 35.5 kW/m2,
and the fatality to people within each contour calculated. Overpressure effects
from vapour cloud explosions are calculated to 5psi and 2psi contours.
Dispersion of vapour clouds is determined to 0.85 of the lower flammability
limit. A range of weather conditions is also considered, to represent a full
year of conditions that occur within
13.7.1
Individual
Risk Results
The
individual risk (IR) contours associated with the LNG terminal are shown in Figure 13.4. The maximum off-site risk is less than 1 x 10-5
per year at the site boundary, hence meets the HKRG requirements.
Figure 13.4 Individual Risk
Contours
The societal risk for the Black Point site has been
estimated based on the land and marine population in the area. Three cases are
considered: year 2011, year 2021 “no Tonggu” and year
2021 “with Tonggu”. The potential development of the Tonggu Waterway will reduce the marine traffic along
The
societal risk results for the onshore terminal facilities have been combined
with the risk results for the LNG carrier during berthing manoeuvres within
500m of the jetty to produce the
overall societal risk results (Figures 13.5-13.7). The results for
the berthing manoeuvres are taken from the Marine Quantitative Risk Assessment
(MQRA).
The FN Curve for the 2011 case is shown in Figure 13.5.
Most of the points on the curve arise from scenarios involving the catastrophic
failure of the LNG storage tanks, which is a very low frequency event. Because of
limitations in the modelling, these results are likely conservative. For
example, the model is unable to allow for the restrictions in the pool
spreading from the coastline and other obstructions. The models simple assume
an unconfined isotropic spreading on water. Hence, the model predicts a
spreading of the LNG pool towards land populations which is not possible in
reality. In any case, Figure 13.5 demonstrates that the risks
are well within the acceptable region as per HK EIA Ordinance.
The risks from the carrier berthing manoeuvres within
500m of the jetty are small compared to the risks from the terminal and make
negligible contribution to the combined risk.
Compared
to 2011, the risks in 2021 (Figures 13.6 and 13.7) are marginally higher, in line with
the increase in marine traffic.
The
FN curves for 2021 “No Tonggu” (Figure 13.6) and 2021 “With Tonggu” (Figure 13.7) are essentially very similar.
The development of the Tonggu Waterway is not
predicted to have any effect on the marine population but does affect the
collision frequency with the LNG carrier. There are small changes in the
carrier manoeuvring risks as a result of this but since this 500m marine risk
is small compared to risks from the terminal, there is no discernable
difference in the overall risks.
Also
shown in the figures are results for large (215,000m3) and small
(145,000m3) carriers. If LNG is delivered from smaller carriers, the
number of transfers required per year will be higher. The frequency of possible
releases therefore increases, but the consequences would be less severe. Again,
this only affects the berthing risks and there is negligible difference in the
overall risks for large and small carriers.
The
risks for all cases are well within the Acceptable
Region as per HK EIAO.
The Potential Loss of Life (PLL), or equivalent
fatalities per year, are given in Table
13.3. The total PLL for the whole terminal is very low at 6.1 x 10-6
per year, or equivalently, one fatality every 163,000 years.
Table 13.3 Main
Contributors to Potential Loss of Life
|
Section |
2011 |
2021 |
|||
|
|
|
PLL |
% |
PLL |
% |
|
L02 T2 T1 T3 L05 L01 G07 L03 L06 P20 |
Liquid
unloading arm LNG tank 2 LNG tank 1 LNG tank 3 Liquid
unloading line from shore to tank Liquid piping
from tank to HP pump Sendout piping from
metering station to battery limit Liquid
unloading line from jetty to shore Recondenser In-tank pump
discharge piping |
1.21 x 10-6 9.53 x 10-7 9.43 x 10-7 9.18 x 10-7 7.47 x 10-7 6.53 x 10-7 2.94 x 10-7 1.30 x 10-7 7.21 x 10-8 4.5 x 10-8 |
19.8 15.6 15.4 15.0 12.2 10.7 4.8 2.1 1.2 0.7 |
1.33 x 10-6 1.04 x 10-6 1.02 x 10-6 9.93 x 10-7 8.26 x 10-7 7.20 x 10-7 3.25 x 10-7 1.43 x 10-7 7.91 x 10-8 5.05 x 10-8 |
19.9 15.5 15.3 14.9 12.4 10.8 4.9 2.1 1.2 0.8 |
|
|
Total |
6.11 x 10-6 |
|
6.68 x 10-6 |
|
Figure 13.5 FN Curve for 2011
Figure 13.6 FN Curve for 2021
"No Tonggu"
Figure 13.7 FN Curve for 2021
"With Tonggu"
13.8
Risk from Existing Power Plant
As described in Section
13.3, the proposed LNG Terminal at Black Point will be located adjacent to the
existing Black Point Power Station (BPPS). The BPPS is itself classified a Notifiable Gas Installation (NGI) and hence was the subject
of a Quantitative Risk Assessment (QRA) prior to commencing operation. This
section discusses BPPS and the risks from the site.
13.8.1
BPPS Description
The BPPS is a gas-fired power plant. The plant
receives gas via a subsea pipeline from an offshore
platform to a gas receiving station within the premises. The gas receiving
station includes:
· Emergency shutdown valves
· Pig receiver
· Slug catcher
· Heaters
· Filters
· Pressure reducing assembly
· Metering facilities
Gas from the receiving station is fed directly to the
power station. The power station includes the following gas holding equipment:
· Filter separators
· Fuel gas modules
· Turbines
13.8.2
BPPS QRA Study
The BPPS QRA study was conducted by DNV in 1994. The
study considered the gas receiving station and power station separately.
The hazards identified in the QRA study at both the
receiving station and power station were fire hazards due to a loss of
containment of hydrocarbon gas. The study evaluated the scenarios including jet
fires, flash fires and vapour cloud explosions following a gas release.
The gas receiving station QRA performed a quantitative
analysis considering gas leaks. The analysis considered small, medium, large
and full bore ruptures of the major equipment items.
The power station QRA considered small, medium, large
and full bore ruptures of the major equipment items. Risks to the offsite
populations were evaluated.
13.8.3
Risk Levels due to
BPPS
The BPPS QRA reports show no offsite risk posed by the
BPPS.
13.8.4
Offsite Risk Levels Including BPPS
As the BPPS QRA reports there are no offsite risk
posed by the BPPS, the total offsite risk in the vicinity of the LNG Terminal
is not affected by BPPS. The results of this study therefore present the total
offsite risk posed by the power station/LNG Terminal complex.
Based on the above discussion, the combined risk for
the existing Black Point Power Station and the proposed LNG terminal is within
the Acceptable Region as per HK EIAO.
13.9
Conclusions of QRA Study for
Terminal
The results indicate that the societal risks from the
proposed facility are within the Acceptable
Region of the HK EIAO.
The individual risks also meet the requirements of the HKRG.
References
[1] Projected
Hong Kong Resident Population by TPU, Planning Department, Hong Kong SAR, 2004.
[2] Marine Impact
Assessment for Black Point & Sokos islands LNG
Receiving Terminal & Associated Facilities, Pipeline Issues, Working Paper
#3, Issue 6, BMT Asia Pacific Ltd, May 2006.
[3] Crossthwaite,
P.J., Fitzpatrick, R.D. & Hurst, N.W., Risk Assessment for the Siting of Developments Near Liquefied Petroleum Gas
Installations, IChemE Symposium Series No 110, 1988.
[4] Rijnmond
Public Authority, A Risk Analysis of Six Potentially Hazardous Industrial
Objects in the Rijnmond Area – A Pilot Study, COVO,
D. Reidel Publishing Co., Dordrecht,1982.
[5] Hawksley,
J.L., Some Social, Technical and Economic Aspects of the Risks of Large Plants,
CHEMRAWN III, 1984
[6] Committee for the
Prevention of Disasters, Guidelines for Quantitative Risk Assessment – Purple
Book, 1st Edition, 1999.
Sub-Section
3: Black Point and