MANUAL OF NATO SAFETY PRINCIPLES FOR THE STORAGE OF MILITARY AMMUNITION AND EXPLOSIVES (May 2010) - page 2
AASTP-1
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Section IV - Sensitivity Groups
1.2.4.1.
General Principles
a) In certain storage or operational situations, for example, where walls are used to
prevent, or at least substantially delay, transmission of explosion between stacks of
ammunition on opposite sides of the wall, initiation by either fragment impact or direct
shock can be disregarded. In such situations, however, prompt acceptor detonation
reactions may still occur because of mechanisms such as kinetic trauma—the initiation of
acceptor munitions due to impacts with other acceptor munitions or with portions of the
structure itself.
b) Sensitivity group is a classification category used to describe the susceptibility of HD
1.1 and HD 1.2 Articles and Explosives to sympathetic detonation (SD).
1.2.4.2.
Determination of Sensitivity Groups
On the basis of the definitions in paragraph 1.2.4.3. ammunition and explosives are
formally grouped into five Sensitivity Groups SG1, SG2, SG3, SG4, and SG5.
1.2.4.3.
Definitions of Sensitivity Groups (definitions taken from AASTP 3 Edition 1):
SG1 Robust
SG2 Non-robust
SG3 Fragmenting
SG4 Cluster bombs/dispenser munitions
SG5 SD Sensitive
1.2.4.4 Guidance on the practical procedure for classifying an item in Sensitivity Groups is given
in AASTP-3.
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CHAPTER 3 - ABOVEGROUND STORAGE IN DEPOTS
Section I - Principles of the Quantity-Distances
1.3.1.1.
General
PES such as buildings, stacks and vehicles (trucks, trailers and railcars) present an obvious
risk to personnel and property. Such sites are located at carefully calculated distances from each other
and from other buildings and installations to ensure the minimum practicable risk to life and property
(including ammunition). These distances are called Quantity-Distances and are tabulated in Annex I-
A, Section II.
1.3.1.2.
Basis of Quantity-Distances
The quantity-distances are based on an extensive series of trials and a careful analysis of all
available data on accidental explosions in different countries. However, quantity-distances are subject
to uncertainty owing to the variability of explosions. These quantity-distances are generated by
distance functions subject, in certain cases, to fixed minimum or maximum distances. The fixed
values are independent of the NEQ because they are based on the projection hazard from individual
rounds or operational factors (see Annex I-B). As regards the rounding of values of quantity-
distances, see Annex I-A, paragraph A.1.2. Criteria and formulae for quantity-distances are given in
Annex I-B.
1.3.1.3.
Kinds of Quantity-Distances
a)
There are two kinds of Interior Quantity-Distances for each hazard
division/SsD:
1)
Inter-Magazine Distances (see paragraphs 1.3.1.8. - 1.3.1.11)
2)
Explosives Workshop Distances (see paragraphs 1.3.1.12. - 1.3.1.13)
b)
There are two kinds of Exterior Quantity-Distances for each hazard
division/SsD:
1)
Public Traffic Route Distances (see paragraph 1.3.1.14)
2)
Inhabited Building Distances (see paragraph 1.3.1.15)
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1.3.1.4.
Quantity-Distances for Hazard Division 1.1
Annex I-A, Tables 1 A-C give QD Matrices and Table 1D Interior and Exterior Quantity-
Distances for ammunition and explosives of Hazard Division 1.1. The Inter-Magazine Distances
should not be used for packages of primary explosives and other very sensitive explosive substances
like blasting gelatine which require individual assessment when at an ES.
1.3.1.5.
Quantity-Distances for Hazard Division 1.2
a)
General
Annex I-A, Tables 2 A-F give QD Matrices and Table 2G Interior and Exterior Quantity-
Distances for ammunition and explosives of SsDs 1.2.1 and 1.2.2. Before appropriate
quantity-distances can be selected there are three factors to be considered. The first
factor is the range of fragments and lobbed ammunition which are projected from a PES.
The second factor is the total number of projections likely to hazard an ES. If
comprehensive data are available for a particular item, then the quantity-distances for
Hazard Division 1.2, which are based on trials with individual rounds considered to be
representative, may be replaced by this more appropriate data taking into account the
vulnerability of the ammunition, explosives and buildings at the Exposed Sites under
consideration (see Part II, Chapter 5, Section II.). The third factor is the behavior of some
types of HD 1.2 ammunition. Large NEQ items of SsD 1.2.1 (NEQ < 244 kg) in certain
packaging configurations, may react in a manner more typical of an HD 1.1 event. When
located in structures that stop primary fragments, but which generate a secondary debris
hazard (e.g., certain ECM and other hardened structures), the structural damage and
debris hazards produced from these events are more characteristic of an HD
1.1
explosion, rather than the progressive nature of an SsD 1.2.1 event. In these situations, it
is appropriate to apply more restrictive quantity-distances.
b)
Fragments and Lobbed ammunition from Rounds greater than 0.73 kg individual NEQ.
This, the most hazardous part of Hazard Division 1.2 comprises those rounds and ammunition
which contain a high explosive charge and may also contain a propelling or pyrotechnic
charge. The total explosives content of these rounds, etc will be greater than 0.73 kg. It is
impractical to specify quantity-distances which allow for the maximum possible flight ranges
of propulsive items but the likely range of packaged items, if involved in an accident during
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storage, is typical of this part of Hazard Division 1.2. Munitions which explode during an
accident will rarely detonate in their design mode. In a fire situation explosive fillings may
melt and expand, breaching their casings and then explode via cook-off or burning to
detonation reactions. These explosions may involve anything from 100% to very little of the
fill dependent on the amount of the filling that has escaped through the breach. The
fragmentation produced by such reactions is totally different to that generated in a design
detonation. The case splits open producing large (for a 105mm shell, for example 2-3kg) but
comparatively few fragments with velocities of 100-500ms-1. These are likely to be projected
further than the smaller fragments from the full detonation of similar munitions in a HD 1.1
reaction. Quantities of unexploded munitions, sub-assemblies or sub-munitions also may be
projected to considerable ranges and will, due to thermal or mechanical damage, be more
hazardous than in their pristine state. Data on individual round characteristics obtained from
tests and accidental explosions may be used to determine the validity of including a specific
round in this category or to reduce it to the lesser category described in Paragraph c) below.
These items are hereafter called rounds of SsD 1.2.1.
c)
Fragments and Lobbed Ammunition from Rounds less than or equal to 0.73 kg individual
NEQ.
This less hazardous part of Hazard Division 1.2 comprises those rounds and ammunition
which contain a high explosive charge and may also contain a propelling or pyrotechnic
charge. The total explosives content of these rounds, etc will be less than or equal to 0.73 kg.
It will also typically comprise ammunition which does not contain HE and will include
pyrotechnic rounds and articles, inert projectile rounds. Tests show that many items of this
type produce fragments and lobbed ammunition with a range significantly less than that of
items in b) above but of course greater than that of ammunition and explosives of Hazard
Division 1.4. These items are hereafter called rounds of SsD 1.2.2.
d)
Subdivisions for Storage
It is important not to exaggerate the significance of the value of 0.73 kg used in b) and c)
above. It was based on a break point in the database supporting the Quantity Distance
relationships and tables and the NEQ of the rounds tested. If comprehensive data is available
for a particular item, then the item may be placed in that category of HD 1.2 supported by the
data and allocated the relevant Quantity Distances. It may also be necessary to take into
account the vulnerability of ammunition, explosives and buildings at the ES under
consideration, see Part II, Chapter 5, Section II.
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e)
Number of Fragments and Lobbed Items at an Exposed Site
Following the initiation of an event in storage there will be a delay before there are any
violent events and projections. This delay will be highly dependent on the nature, dimensions
and packaging of the items involved. For 40mm HE rounds it can be as short as two or three
minutes and for 105mm HE rounds 15-20 minutes. Once ammunition starts to react the rate
of reactions increases rapidly and then decreases more slowly. Reactions may still occur
hours after the event. The ability of the storage structure at the PES to contain the fragments
etc will determine both in time and density the effects at the exposed site. For medium and
lightly constructed PES where, at some stage, walls and/or roofs will be destroyed, the
modifying effect of the building on the fragmentation is not taken into account. In the light of
the indeterminacy of the fragmentation effects both in time and quantity, fire fighting will, in
general, be inadvisable. However the installation of automatic fire-fighting arrangements
could be invaluable from the stock preservation and event containment points of view.
Evacuation from PTR and beyond may be possible. However the quantity-distances given at
Annex I-A assume no amelioration from fire-fighting or evacuation. They are based on the
total fragmentation at the exposed site from the event at the PES.
f)
Arrangements for Fire-Fighting
The levels of protection afforded by the Inter-Magazine Distances in Annex I-A are
based on the fragment density at the Exposed Site for the total incident and the degree of
protection afforded by the structure at the Exposed Site. It is assumed that an incident
involving Hazard Division
1.2 cannot be promptly curtailed by fire-fighting. It is
considered unlikely that any significant attempts could be made to fight a fire involving
Hazard Division 1.2 explosives as it is anticipated that such efforts would have to be
made from such a distance and from behind protective cover so as to make those efforts
ineffective. In addition some storage areas are too remote from professional fire-fighting
services, and other lack suitable protective cover from behind which firemen could even
attempt to attack a fire involving ammunition of Hazard Division 1.2. The levels of
protection take into account the fact that the Explosives Area is endangered by firebrands,
projections and lobbed ammunition which would most likely propagate fire or explosion
if the quantity-distances were insufficient. The available fire-fighting effort should be
directed at preventing the spread of fire and the subsequent propagation of explosions.
Fuller recommendations are given in Chapter 4, Part II of the Manual.
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g)
To advise on Maximum Credible Event (MCE) calculation
The MCE for SsD 1.2.1 is the NEQ of an item times the number of items in three
unpalletized, outer shipping packages, unless a different MCE is demonstrated by testing or
analogy. The MCE for SsD 1.2.3 is the NEQ of one item.1
h)
To advise situations which require structural debris distances
When located in structures that stop primary fragments, but which generate a secondary debris
hazard, D2 for IBD and D6 for PTR from Table 2 will be used.
i)
Situations which require no QDs
Where either the PES or the ES is an earth covered building or a building which can contain
the effects generated in an accidental explosion of the HD 1.2 then, in general, no Q-Ds are
necessary. The separation to other explosive storehouses, explosive workshops, public traffic
routes or inhabited buildings will be dependent on constructional details, access for rescue and
fire-fighting personnel or other administrative arrangements. For public traffic routes and
inhabited buildings consideration should be given to the use of fixed distances of 30 m for
ammunition of SsD 1.2.2 or 60 m for SsD 1.2.1. However where there is an aperture such as a
door in the PES and the ES has either an unprotected and undefined door pointing towards the
PES or offers little or no protection to its contents then the higher Q-Ds shown in the HD 1.2
Tables should be applied.
j)
The Quantity-Distances for ammunition and explosives of SsD 1.2.3 is as follows:
The inhabited building distance for SsD 1.2.3 is determined using D4 of Annex I-A, Table
3G, for the NEQ of the rounds present, but with a minimum inhabited building distance
determined as follows: If the SsD 1.2.3 items are situated such that primary fragments will
not be interrupted, the minimum inhabited building distance is the hazardous primary
fragment distance based on the hazardous fragment density criteria (1 per 55.7 square meters)
applied to the worst single SsD 1.2.3 item at the PES. The public traffic route distance in this
case is equal to inhabited building distance in high traffic density areas and equal to 67% of
inhabited building distance where the traffic density is low. Unbarricaded open or light
structure storage
(intermagazine) and process building
(workshop) distance is
67% of
inhabited building distance and barricaded process building distance is 36% of inhabited
1 For Change 3: MCE concept is accepted but not applied in current Table 2G for HD 1.2.1.
PFP(AC/326-SG5)(UK)IWP/3-2005 dated 18 March 2005 “Inconsistencies between HD
1.1 and 1.2” would imply a D7 and a D8 column for applying MCE. This IWP and its
implications will be dealt with in the next Change.
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building distance, both with a minimum distance equal to the intermagazine distance of 31 m
for items with a single-round NEQ equal to or less than 0.73 kg or 92 m for items with a
greater NEQ. The intermagazine distance from a PES containing only SsD 1.2.3 items to an
ES containing other than SsD 1.2.3 is based on the NEQ of a single round of the largest
(greatest NEQ) SsD 1.2.3 item in the PES. If the SsD 1.2.3 items are situated such that
primary fragments can be interrupted, the specific minimum separation distances (inhabited
building, public traffic route, workshop, and intermagazine) are dictated by practical
considerations. For any specific quantity or distance determination, as an alternative to the
preceding SsD 1.2.3 QD criteria, when an increase in the allowable quantity or a reduction in
the required distance will result, items hazard classified as SsD 1.2.3 may be treated as
follows: If the single-round NEQ is greater than 0.73 kg, consider the items as SsD 1.2.1 (use
the total NEQ present). If the single-round NEQ is equal to or less than 0.73 kg, consider the
items as SsD 1.2.2, based on the total NEQ present.
1.3.1.6.
Quantity-Distances for Hazard Division 1.3
a)
General
Annex I-A, Tables 3A-F give QD Matrices and the Table 3G gives Interior and Exterior
Quantity-Distances for ammunition and explosives of Hazard Division
1.3 but the
selection of appropriate quantity-distances requires separate consideration of two types of
explosives, namely propellants (classified as SsD 1.3.1 - Compatibility Group C) and
other items (classified as SsD 1.3.2 - Compatibility Group G). Although many hazardous
effects are common to both types, the dominant hazards used, as the bases of certain
quantity-distances are different in the two cases hence there are two tables.
b)
Explosives producing a mass fire effect
The explosives producing a mass fire effect are likely to be propellants, which produce a
fireball with intense radiant heat, firebrands and some fragments. The firebrands may be
massive fiery chunks of burning propellant. (The effect of quite normal winds may
augment a calculated flame radius by 50 %. A building with marked asymmetry of
construction such as an igloo or building with protective roof and walls, but with one
relatively weak wall or a door, induces very directional effects from the flames and the
projection of burning packages.). These items or substances are called items or
substances of SsD 1.3.1.
c)
Ammunition and Explosives not Producing a Mass Fire Effect
Items other than propellants produce a moderate fire with moderate projections and
firebrands. The projections include fragments but these are less hazardous than those,
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which characterize Hazard Division 1.2. These items or substances are called items or
substances of SsD 1.3.2.
1.3.1.7.
Distances for Hazard Division 1.4
Separation distances from ammunition and explosives of Hazard Division 1.4 are not a
function of the NEQ. Separation distances prescribed by fire regulations apply.
1.3.1.8.
Inter-Magazine Distances - General Considerations
a)
These distances are the minimum permissible distances between PES and storage sites
containing ammunition or explosives. These distances are intended to provide specified
degrees of protection to the ammunition and explosives at the ES. The degree of protection
is highly dependent upon factors such as sensitiveness of explosives, type of ammunition,
type of packaging, and type and construction of building at the PES or ES or both. In
general the provision of stronger buildings allows the use of smaller quantity-distances for a
given degree of protection, or achieves a better standard of protection at a given distance,
especially in the case of a PES containing ammunition and explosives of Hazard Division
1.1 or 1.2.
b)
The selection of the optimum combination of types of construction of the buildings,
quantity-distance and degree of protection involves a balance between the cost of
construction, the availability and cost of land, and the value of the stocks of ammunition
and explosives which might be rendered unserviceable at ES in the event of an accident at
the PES. The hazard divisions and compatibility groups of the ammunition and
explosives and the need for flexibility in the use of the sites should be taken into account.
c)
The following paragraphs describe the levels of protection corresponding to common
combinations of buildings or stacks and quantity-distances for each hazard division as a
guide for decisions on the optimum solution. These levels of protection are incorporated
in the Inter-Magazine Distances in Annex I-A, Tables 1 to 3. Some entries in the tables
show only one level of protection owing to a lack of information at the present time. In a
few cases it is not possible to predict the level of protection as it depends on the type of
structure at the ES and the sensitiveness of its contents. An indication of the full range of
possibilities is given in Part II, Chapter 5.
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1.3.1.9.
Inter-Magazine Distances for Hazard Division 1.1
a)
Protection of Stocks
The observed damage to stocks at an Exposed Site from an accidental explosion varies
widely and, although detailed prediction of such effects is outside the scope of this
Manual, a measure of guidance is given here. Since an igloo is designed to resist external
blast, primary fragments or secondary projections, the design ensures that the stocks
survive and would be expected to generally remain serviceable. However, at the D3-
distances the ground shock may render unserviceable sensitive electrical and electronic
components of guided missiles, etc. For open stacks and buildings, other than those
covered with earth, a general assessment is that for distances less than D5-distances it is
probable that, even though propagation may not have taken place, the stocks are likely to
be unserviceable and covered by debris from the collapsed building. Stocks at D7-
distances and greater are only likely to be serviceable if the building has not suffered
serious structural damage although some structural damage at the D7-distances,
dependent on the type of building, can be expected.
b)
Alternative Levels of Protection at an ES
As described above, the igloo design affords extremely good protection to its contents.
Weaker buildings and open stacks would not be expected to give such good protection
although concrete structures are considered to be superior generally to brick from an
Exposed Site point of view. The level of protection also depends on the vulnerability or
robustness of the ammunition stored at the Exposed Site and the type of traversing used.
The following paragraphs describe the three levels of protection which are incorporated in
Annex I-A, Table 1 and which are intended to provide an adequate basis for the selection
of a particular quantity-distance. Some entries in the table show only one level of
protection due to a lack of data. The three levels of protection are:
1)
There is virtually complete protection against practically instantaneous
propagation of explosion by ground shock, blast, flame and high velocity
projections. There are unlikely to be fires or subsequent explosions caused by
these effects or by lobbed ammunition. The stocks are likely to be serviceable.
However, ground shock may cause indirect damage and even explosions
among specially vulnerable types of ammunition or in conditions of saturated
soil. These exceptional circumstances require individual assessment rather than
use of the quantity-distances in Annex I-A.
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2)
There is a high degree of protection against practically instantaneous
propagation of explosion by ground shock, blast, flame and high velocity
projections. There are occasional fires or subsequent explosions caused by
these effects or by lobbed ammunition. Most of the stocks are likely to be
serviceable although some are covered by debris.
3)
There is only a limited degree of protection against practically instantaneous
propagation of explosion by ground shock, flame and high velocity
projections. There are likely to be fires or subsequent explosions caused by
these effects or by lobbed ammunition. The stocks are likely to be heavily
damaged and rendered unserviceable; they are sometimes completely buried by
debris. This level of protection is not recommended for new construction.
1.3.1.10.
Inter-Magazine Distances for Hazard Division 1.2
The Inter-Magazine Distances for Hazard Division 1.2 relate essentially to three levels of
protection of ammunition and explosives at an ES:
1)
There is virtually complete protection against immediate or subsequent fires and explosions
caused by blast, flame, firebrands, projections and lobbed ammunition. The stocks are likely
to be serviceable.
2)
There is a high degree of protection against immediate or subsequent propagation of
explosion by blast, flame, projections and lobbed ammunition. The larger the donor
event the lower will be the degree of protection given, particularly where ammunition
with NEQ greater than 0.73 kg is involved, propagation becoming more likely the longer
the event continues. Local fire fighting measures may reduce stock losses. It is likely
that stocks at the ES will not survive as a result of subsequent propagation.
3)
There is only a limited degree of protection against immediate or subsequent propagation
of explosion by blast, flame and projections and lobbed ammunition. The protection
afforded may be minimal when the donor event involves large quantities of ammunition
and continues for a prolonged period. Local fire fighting measures will be essential to the
preservation of stocks. The stocks at the ES are not likely to survive as a result of
subsequent propagation.
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1.3.1.11.
Inter-Magazine Distances for Hazard Division 1.3
The Inter-Magazine Distances for Hazard Division 1.3 relate essentially to two levels of
protection of ammunition and explosives at an ES:
1)
There is virtually complete protection against immediate or subsequent fires among the
contents of an ES by flame, radiant heat, firebrands, projections and lobbed ammunition.
There may be ignition of combustible parts of the building but this is unlikely to spread to
the contents even if it were not possible to provide prompt and effective fire-fighting
services.
2)
There is a high degree of protection against immediate propagation of fire to the contents
of an ES by flame, radiant heat, firebrands, projections and lobbed ammunition. There is
a considerable risk that one or more of these effects, especially lobbed ammunition, is
likely to ignite the contents directly or as the result of ignition of combustible parts of the
building unless effective fire-fighting is able to prevent such consequences.
1.3.1.12.
Explosives Workshop Distances
a)
General Considerations
These distances are the minimum permissible distances between Potential Explosion Sites
and explosive workshops. The distances are intended to provide a reasonable degree of
immunity for personnel within the explosives workshops from the effects of a nearby
explosion, such as blast, flame, radiant heat and projections. Light structures are likely to
be severely damaged, if not completely destroyed. These distances also provide a high
degree of protection against immediate or subsequent propagation of explosion.
b)
Explosive Workshop Distance for HD 1.1
1)
For HD 1.1 the standard Explosive Workshop Distance should be the D10
distances prescribed in Annex I-A Tables 1A-C. At this distance the major
effects to be considered are the peak side-on overpressure, which is anticipated
to be no greater than 20 kPa (3 psi) and debris, which is extremely difficult to
quantify, but would be a very significant effect.
2)
When siting and designing explosive workshops the following effects should
be borne in mind amongst others. A person in a building designed to
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withstand the anticipated blast loading and without windows would be merely
startled by the noise of the explosion at an adjacent site whereas a person in a
brick building with windows might suffer eardrum damage or suffer indirect
injuries through his translation by blast and subsequent impact on hard objects
or through possible collapse of the building upon him.
3)
Where the quantity-distance tables specify a Explosive Workshop Distance
less than
270 m this may not give protection to personnel in explosive
workshops having light roofs from debris projected from the Potential
Explosion Site. Therefore consideration should be given to maintaining this
270 m distance as the minimum separation from the nearest storage site
containing explosives of HD 1.1, in order to provide additional protection from
debris.
c)
Explosive Workshop Distance for HD 1.2
1)
Since debris and/or fragmentation hazards are considered to be dominant for HD
1.2 and the Inhabited Building Distance is based on an appreciation of this hazard
then the Explosive Workshop Distance is generally determined as 36% of the IBD.
2)
However where the PES is an earth covered building or a building which can
contain the effects generated in an accidental explosion of the HD 1.2 then no Q-
Ds are necessary to adjacent explosive workshops although the separation between
them and the explosive storehouses will be dependent on constructional details and
access for rescue and fire-fighting personnel.
3)
Where the PES is an earth covered building or a building which can contain the
effects generated in an accidental explosion of the HD 1.2 but has a door or other
aperture in the direction of the ES then the Explosive Workshop Distance is
determined as 36% of the IBD.
4)
Where the explosive workshop is protected by a barricade and has a protective
roof it is considered that the occupants are afforded a high degree of protection
which decreases to limited if the building is either not barricaded or does not have
a protective roof. In the absence of any protective features, such as a barricade or
a protective roof, not only is the level of protection limited but it is recommended
that such explosive workshops should only be sited at an increased separation
equivalent to PTR.
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d)
Explosive Workshop Distance for HD 1.3
1)
For the substances or items classified SsD 1.3.1, the D2 distances prescribed at
Annex I-A Tables 3A-C should be used.
2)
For the substances or items classified SsD 1.3.2, the distances are fixed values
given in Annex I-A Tables 3D-F.
1.3.1.13.
Separation of Explosives Workshops from Storage Sites
The D10-distances in Annex I-A, Table 1 less than 270 m may not give protection to
personnel in Explosives Workshops having light roofs. If greater protection is required against
projections than that provided by D10-distances for example to protect personnel and valuable test
equipment, then the workshop must be provided with a protective roof. If there is a possibility of a
serious fragment hazard then consideration should be given to observing a minimum separation
distance of 270 m between Explosives Workshops having light roofs and storage sites containing
ammunition and explosives of Hazard Division 1.1 as is already required in certain circumstances.
1.3.1.14.
Public Traffic Route Distances (PTRD)
a)
General Considerations
1)
These distances are the permissible distances between a Potential Explosion Site
and routes used by the general public, which are generically referred to as Public
Traffic Routes, subject to the fragment minimum distances detailed at para 1.3.7.3.
These routes include :
Roads
Railways
Waterways, including rivers, canals and lakes, and
Footpaths
2)
Where debris or fragmentation hazards are considered to be dominant and the
Inhabited Building Distance is based on an appreciation of this hazard then the
PTR is determined as 67% (or 2/3) of the IBD. This rule is applied to both HD 1.1
and HD 1.2 situations. Attempts have been made within AC/258, which preceded
AC/326, to determine a relationship between debris hazards for IBD and PTR
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without success primarily because the variation of hazard with distance is too
dependent on the specific hazard generator.
3)
It is important to appreciate that PTR’s or common access areas should not be
treated independently of each other or of any other constraints around an
explosives site. They should be viewed within the overall picture and the above
guidelines used to indicate whether a particular situation is likely to be worth
consideration. Ideally a full risk analysis should be conducted to ascertain how
these additional risks would fit into the overall risk picture. Only then can
informed decisions be made regarding the soundness of a particular license.
b)
Traffic Density Considerations
1)
Since the exposed sites presented by public traffic routes are so diverse three
alternatives are provided as follows :
The use of full IBD protection for heavily used routes
The use of a reduced Public Traffic Route distance, generally 2/3 of the
appropriate IBD for less heavily used routes, and
The use of a lower distance for routes which are used intermittently or
infrequently by low numbers of people.
2)
The dominant factors which determine the number and severity of road casualties
are the traffic speed and density, the width of traffic lanes and their number, the
presence of crash barriers, the surface condition and the radius of any curves.
Factors of less importance are the presence or absence of roadside trees and
ditches and of separated carriageways for opposing traffic. For other types of
routes it is essentially the density and speed of the “traffic” which are the critical
factors.
3)
Because of the variety of waterway borne traffic some cognisance may need to be
taken of special factors, e.g. passenger carrying ferries which, although traversing
the hazarded area much quicker than other craft, may merit special consideration
because of the number of passengers carried.
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1.3.1.15.
Inhabited Building Distances
a)
General
These distances are the minimum permissible distances between PES and inhabited
buildings or assembly places. The distances are intended to prevent serious structural
damage by blast, flame or projections to ordinary types of inhabited buildings or
caravans/mobile homes and consequent death or serious injuries to their occupants.
b)
Inhabited Building Distances for Hazard Division 1.1.
1)
The distances for Hazard Division 1.1 are based on tolerable levels of damage
expected from a side-on overpressure of 5 kPa. They are intended to ensure
that the debris produced in an accidental explosion does not exceed one lethal
fragment (energy > 80 J) per 56 m² at the Inhabited Building Distance. They
are not sufficiently large to prevent breakage of glass and other frangible
panels or cladding used in the three types of buildings of vulnerable
construction. This broken glass, cladding etc. can cause injury to occupants
and those in the immediate vicinity of the buildings. Such buildings of
vulnerable construction should be situated as follows:
(a)
Types 1 and 2: are considered to be of similar vulnerability and such
buildings should normally be situated at distances not less than two
times Inhabited Building Distances (i.e. > 44.4 Q1/3) (see paragraph
1.3.7.6.). However, such buildings, but probably not schools or
hospitals, may be acceptable within the
44.4 Q1/3 distances,
particularly if the population outside the building
(on whom the
displaced glass etc. would fall) is small or virtually nil. When
vulnerable buildings have been allowed within the 44.4 Q1/3 distances
on these grounds, it will be necessary to check at regular intervals that
the original conditions (i.e. area around building free of people) have
not changed.
(b)
Type 3: presents a difficult problem and it is intended to cover the
multiplicity of new construction types which have been introduced
since the curtain wall concept was first thought of. Each such building
has to be treated on its merits, the hazard assessed and an appropriate
quantity-distance selected. It is likely, however, that this will be in the
44.4 Q1/3 region.
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2)
The Australian/UK Stack Fragmentation trials in the late
1980s have
demonstrated that, for a Net Explosives Quantity of less than 5 600 kg, if the
Potential Explosion Site is of light construction, typically 230 mm brick or
equivalent or less, and barricaded, then the hazard from projection is tolerable
at D12-distances subject to a minimum of 270 m. However, if a medium or
heavy walled construction, typically 200 mm concrete or greater, is employed
at the Potential Explosion Site, then the hazard from projection requires a
minimum separation distance of 400 m. For a Net Explosives Quantity greater
than 5 600 kg, the prescribed Inhabited Building Distance D13 will provide an
acceptable degree of protection from both blast and projections. These trials
also demonstrate that the hazard from projections is not constant and shows a
marked directional effect. Basically, there is a very low density of projections
in directions directly away from the corners of the structure. The projection
density rises almost as an exponential function to a maximum in the direction
normal to any face of the structure. This is repeated on all sides of the structure
irrespective of whether the structure is barricaded or not. It is extremely
difficult to interpret the results to give general guidelines and it is advised that
where it is considered that siting of the Exposed Site with respect to the
Potential Explosion Site might be beneficial, then the Stack Trial results should
be considered in detail for each specific case.
3)
A 400 m minimum Inhabited Building Distance is required to protect against
structural debris from igloos, other earth-covered structures or unbarricaded
buildings.
4)
The distances for explosives of Hazard Division 1.1 are based on the behaviour
of typical packaged military explosives. They take account of trials using bulk
demolition explosives in wooden boxes or pallets in open stacks. In certain
special circumstances, for Net Explosives Quantities of less than 4 500 kg,
these distances would be unduly conservative, since hazardous projections
cannot arise. Such circumstances may occur at test sites and factories where
bulk explosives, devoid of metal casing or components, are in fibreboard
packagings, not on pallets, and are either in open stacks or in light frangible
buildings. In these special circumstances use D13-distances, as appropriate,
without any overriding minimum distance for projections.
5)
There is a significant hazard even at 270 m from ammunition and explosives of
Hazard Division 1.1 due to fragments and a considerable amount of debris
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unless these projections are intercepted by structural protection. This hazard
may be tolerable for sparsely populated areas, where there would be a small
expectation of damage and injury from such projections, but in densely
populated areas considerations should be given to the use of a minimum
Inhabited Building Distance of 400 m. This distance is required for earth-
covered magazines and for heavy-walled buildings.
c)
Inhabited Building Distances for Hazard Division 1.2.
The distances for Hazard Division 1.2 are based on an acceptable risk from fragments.
Under normal conditions, for non-earth covered magazines, D1- or D2-distances given in
Annex I-A, Tables 2 A-F must be used for inhabited buildings. For earth covered
magazines 30m and 60m fixed distances may be applied as advised in Tables 2A and 2D.
d)
Inhabited Building Distances for Hazard Division 1.3.
1)
The distances for Hazard Division 1.3 are based on a thermal flux criterion of
1.5 cal per cm². It is anticipated that occupants of traditional types of inhabited
buildings would not suffer injury unless standing in front of windows; such
persons and other in the open are likely to experience reddening of any
exposed skin areas.
2)
If venting from the Potential Explosion Site is directed towards the Exposed
Sites at Inhabited Building Distances, then a minimum distance of 60 m should
be employed.
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Section II - Determination of Quantity-Distances
1.3.2.1.
Quantity-Distances Tables
a)
The quantity-distances required for each hazard division are given in tables in Annex I-A,
Section II.
b)
For an intermediate quantity between those given in the tables, the next greater distance
in the tables should be used when determining a quantity-distance. Conversely the next
lesser quantity in the tables should be used when determining an explosives quantity limit
for a given intermediate distance, alternatively, the distances corresponding to an
intermediate quantity may be either calculated from the distance function shown in the
tables of Annex I-A or found by interpolation and then rounded up in accordance with
Annex I-A, Section I, paragraph A.1.2.
c)
Quantity-distances for a quantity of explosives greater than 250 000 kg are determined by
extrapolation using the appropriate formula in Annex I-B, as far as the explosives safety
factors are concerned, but adequate consideration should be given to the economic and
logistic implications of such a large quantity in a single storage site.
d)
The tables in Annex I-A provide quantity-distances for an earth-covered magazine up to
250 000 kg NEQ. However, certain designs of earth-covered magazines require a lower
limit in the case of Hazard Division 1.1. The reason is that the blast load from an
exploding earth-covered magazine is a function of the NEQ, whereas the blast resistance
of an exposed earth-covered magazine depends on its design. The limitation for a
particular earth-covered magazine must be obtained from the design authority.
1.3.2.2.
Measuring of Quantity-Distances
a)
Quantity-distances are measured from the nearest point of the PES to the nearest point of
the ES. Distances are measured along a straight line without regard to barricades.
b)
Where the total quantity of ammunition and explosives in a storage site or explosives
workshop is so separated into stacks that the possibility of mass explosion is limited to
the quantity in any one stack, distances are measured from the outside of the wall
adjacent to the controlling explosives stack to the nearest outside wall of another
structure. If the separation to prevent mass explosion is provided by one or more
substantial dividing walls, then the distances are measured from these walls, if
appropriate, instead of from the outside walls of the building. Where not so separated the
total quantity subject to mass explosion is used for quantity-distance computations.
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1.3.2.3
Net Explosives Quantity
a)
The total Net Explosives Quantity of ammunition in a single PES is used for the
computation of quantity-distances unless it has been determined by testing or analogy to
testing that the effective quantity is significantly different from the actual NEQ.
b)
Where two or more PES are not separated by the appropriate Inter-Magazine Distances,
they are considered as a single site and the aggregate NEQ is used for determining
Quantity-Distances. If two or more hazard divisions are involved the principles in
paragraph 1.3.2.5. apply.
c)
The total explosives content of rounds or ammunition classified as HD 1.2 is used in the
computation of the NEQ for quantity-distance purposes.
d)
The NEQ does not include such substances as white phosphorous, chemical agents,
smoke or incendiary compositions unless these substances have been shown to contribute
significantly to the explosion hazard. Any other energetic materials such as liquid fuels
should be aggregated with the explosives NEQ unless it has been determined by testing
that they do not contribute to the overall hazard.
1.3.2.4.
Determination of Quantity-Distances
a)
The location of buildings or stacks containing ammunition or explosives with respect to
each other and to other ES is based on the total NEQ in the individual buildings or stacks
unless this total quantity is so subdivided that an incident involving any one of the
smaller concentrations cannot produce a practically instantaneous explosion of the whole
contents of the building or stack.
b)
The quantity-distances required from each of two or more nearby storage sites or
explosives workshops to contain ammunition and explosives of one hazard division are
only determined by considering each as a PES. The quantity of explosives permitted in
the storage sites or explosives workshops is limited to the least amount allowed by the
appropriate table for distances separating the storage sites or explosives workshops
concerned.
c)
The quantity-distances required from each of two or more nearby storage sites to contain
given quantities of ammunition and explosives of different hazard divisions at different
times are determined as follows:
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1.
Consider each building or stack, in turn, as a PES.
2.
Refer to the table of each hazard division which can be stored in the building
or stack considered as a PES.
3.
Determine the quantity-distances for each hazard division as the minimum to
be required from the building or stack.
4.
Record the quantity-distances in terms of each hazard division in each instance
as those to be required from the building or stack.
d)
Alternatively calculate the permitted quantity of each hazard division based upon the
available distances.
1.3.2.5.
Reserved (Original content “Required Quantity-Distances of Ammunition and Explosives
of more than one Hazard Division in a Single Site” deleted). Refer to Part I, Section III
for guidance.
1.3.2.6.
Reserved (Original content “Permissable Quantities of Ammuniton or Exposives of more
than one Hazard Division ina Single Site” deleted). Refer to Part I, Section III for
guidance.
1.3.2.7.
Relaxation of Quantity-Distances
a)
Interior Quantity-Distances
1)
Relaxation of Inter-Magazine Distances may result in the total loss of stocks in
other buildings or stacks or at least their being rendered unserviceable.
Furthermore, a much larger explosion may result than that used as basis for
Exterior Quantity-Distances. Disastrous damage to property and injury to the
general public may be the consequence.
2)
Relaxation of Explosives Workshop Distances may be permitted when a
specially constructed building is available to protect against blast and debris or
where the number of persons in the workshop is small.
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b)
Exterior Quantity-Distances
Relaxation of Exterior Quantity-Distances may increase the hazard to life and property.
Relaxation should therefore be permitted only with the written consent of the appropriate
authorities (see also subparagraph 1.1.0.1.d)).
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Section III - Quantity-Distances for Certain
Types of Ammunition and Explosives
1.3.3.1.
Barricaded Stacks of Ammunition
a)
Stacks (Modules) of Bombs etc.
D1-distances up to 30 000 kg and D2-distances from 30 001 to 120 000 kg as shown in
Annex I-A, Section II, Table 1 may be used between unboxed bombs of Hazard Division
1.1 under the following conditions:
1)
The stacks are to be separated by effective earth barricades.
2)
The bombs must be relatively strong so as to withstand intense air shock
without being crushed.
3)
There should be the minimum of flammable dunnage etc., which could catch
alight and lead to subsequent mass explosion of a stack.
4)
When the D1-distances are used then the stacking height must not exceed 1 m.
In the event of an explosion in one stack the distances will provide a high degree
of protection against simultaneous detonation of bombs in adjacent stacks. Some
of the bombs in the ES may be buried and not immediately accessible, some may
be slightly damaged. There may be occasional fires and delayed low order
explosions, particularly if the bombs are stacked on concrete storage pads.
b)
Other Unpackaged Ammunition of Hazard Division 1.1
In principle, the foregoing distances and conditions may be applicable to other kinds of
unboxed ammunition of Hazard Division 1.1 and Compatibility Group D. An example is the
155 mm shell M107 which has a robust steel casing and a relatively insensitive high
explosive filling. Each case must be judged on its merits, using ad hoc tests or analogy with
existing test data as requisite.
c)
Cluster Bomb Units
Tests have shown that certain packaged cluster bomb units (CBU) may be stored safely in
accordance with subparagraph a) above. In this case, it is the robust containers rather than
the heavy casings which prevent sympathetic detonation between stacks. Each type of
bomblet and container must be carefully assessed to ensure a satisfactory combination for
the application of this modular storage.
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d)
Buffered Storage
1)
Tests have shown that stacks of certain types of bombs can be stored in the
same facility in such a manner separated by using buffer materials
(ammunition as well as inert materials), that even though a high order
detonation will propagate through one stack it will not propagate to the second
stack. Storage under these conditions presents the risk of explosion of a single
stack only, rather than a mass risk involving all the stacks in one module, cell,
or building. Hence, the Net Explosives Quantity (NEQ) of the larger stack plus
the NEQ of the "buffer" material, if any, may be used to determine the
quantity-distances requirement for each entire module or building so used.
2)
The storage of bombs using the buffered storage concept and basing the NEQ
of storage on the NEQ of the largest stack plus the buffer material is authorized
provided nationally approved storage arrangements are used. See Part II,
Chapter 3, Section I.
1.3.3.2.
Unbarricaded Stacks of TNT or Amatol Filled Shell
Certain types of TNT or Amatol filled projectiles of Hazard Division 1.1 may be stored in
stacks which comply with the principle that, although a high order detonation would propagate
throughout a stack, it would be unlikely to propagate from stack to stack. Storage under these
conditions presents the risk of explosion of a single stack only, rather than a mass risk involving all
the stacks in one module or building. Hence the NEQ of the appropriate single stack may be used to
determine the quantity-distances for each entire module or building so used. The special types of
projectiles and the conditions are given in Part II, Chapter 3, Section I.
1.3.3.3.
Unbarricaded Storage of Fixed Ammunition with Robust Shell
Trials show that ammunition comprising robust shell with an explosive content not exceeding
about 20 % of the total weight (excluding propelling charges, cartridge cases and weight of packages)
and with shell-walls sufficiently thick to prevent perforation by fragments produced by ammunition
of Hazard Division 1.1 may be stored without barricades without the risk of practically instantaneous
explosion provided an increased quantity-distance is used.
1.3.3.4.
Propulsive Rockets
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Rockets stored in a propulsive state (i.e. unpackaged propulsive rockets and missiles in the
assembled condition, waiting to be placed upon a tactical launcher or vehicle) present special
problems in which the flight range of the rocket is the main safety criterion rather than the explosive
content. Consequently the rockets should be stored in special buildings or held by devices to prevent
their flight (see Part II, Chapter 3, Section II). The quantity-distances for the appropriate hazard
division apply only when these conditions are met, except for the special case of missiles on the
launchers at a missile installation (see Part IV, Chapter 3). Rockets or missiles in either an assembled
or unassembled condition, when packaged as for storage and transport, do not in practice present the
risk of significant flight.
1.3.3.5.
Storage of Very Sensitive Explosives
It is possible for the blast at an ES to cause practically instantaneous initiation of packaged
primary explosive substances and certain other very sensitive explosive substances like blasting
gelatine even when barricaded at the D4-distances in Annex I-A, Table 1. Storage conditions for such
explosives are assessed individually taking account of the protection afforded by packaging and the
building at the ES.
1.3.3.6.
Storage of Depleted Uranium (DU) Ammunition
Quantity-distances will, in general, be those appropriate to the Hazard Classification of the
particular ammunition stored. In some cases a special radiological safety distance may be required
between a storehouse and the nearest point of public access if it is estimated that the adverse
radiological/toxic effects of an atmospheric dispersion of DU could give rise to a possibility of injury
to a member of the public comparable to that caused by the explosive components of the ammunition.
In such a case the more restricted of the two distances, the radiological safety distance or the
explosives quantity-distance, shall be the one applied.
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Section IV - Quantity-Distances for Certain
Exposed Sites
1.3.4.1.
Separation of Miscellaneous Occupied Buildings and Facilities
in an Explosives Area
Buildings containing empty packages or other inert materials should be separated from a
PES by a distance based on the risk to the ammunition and explosives from a fire in the empty
packages or other inert materials (minimum distance 25 m). Special consideration should be given to
the separation of high value packages from a PES.
1.3.4.2.
Criteria for Siting of Holding, Marshalling and Interchange Yards
a)
Holding Yards
Each holding yard is considered to be a PES. Quantity-Distances and/or explosive limits
are determined as for storage sites.
b)
Marshalling Yards
1)
Appropriate Inter-Magazine Distances must be applied to protect a marshalling
yard from external explosions.
2)
It is not necessary to treat a marshalling yard as a PES provided the vehicles
are moved expeditiously (within 4 hours) from the yard. If a yard is used at any
time for purposes other than marshalling, e.g. holding, it is considered to be a
PES and appropriate quantity-distances as for storage site applied.
c)
Interchange Yards
It is not necessary to treat an interchange yard as a PES, provided the vehicles are moved
expeditiously from the yard. However, if a yard is used at any time for a purpose other
than interchange, it is considered to be a PES and appropriate quantity-distances applied.
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1.3.4.3.
Separation of Pipelines etc from an Explosives Area
a)
Aboveground Facilities
For the separation of POL facilities: see Chapter 5.
b)
Underground Pipelines
For the separation of underground pipelines: see Chapter 5.
1.3.4.4.
Separation of Electric Supply and Communications Systems from an
Explosives Area
There may be mutual hazards created by siting an explosives area near to high voltage
transmission lines, powerful transmitters, vital communications lines etc. Each case must be assessed
individually to take account of the voltage and power involved, the importance of the transmission
lines, the time for the necessary repairs and the consequences of losing communications at a time
when assistance may be required following an explosion. The assessment should be based on the
following factors:
1)
Hazard from the Ammunition or Explosives
The Public Traffic Route Distance is a reasonable separation to protect public service or
military emergency communication lines and overhead electrical power transmission
lines exceeding 15 kV or associated substations. Particularly important installations
such as the lines of a supergrid network should be given greater protection from
fragments and debris by affording them one or even one and a half times the Inhabited
Building Distance. This increased separation is also appropriate for microwave, ultra
high frequency (UHF) reflectors which would be vulnerable to damage by air shock or
debris and fragments. Minor transmission and communication lines such as those
serving the buildings of the explosives area, may be sited in accordance with
subparagraph 2) below.
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2)
Hazard to the Ammunition or Explosives
The quantity-distances determined on the basis of 1) above should be reviewed in the
light of a possible hazard from electrical lines and transmitters to the ammunition and
explosives themselves. If any overhead transmission line approaches nearer to a building
containing ammunition or explosives than one span between the poles or pylons,
consideration should be given to the consequences of mechanical failure in the line.
Arcing and large leakage currents may be set up before the supply could be isolated. An
overriding minimum separation of 15 m is prudent. Generating stations and substations
should be at least 45 m from any building containing ammunition or explosives in view
of the small but real risk of fire, explosions or burning oil in such electrical equipment.
Powerful transmitters of electromagnetic energy may hazard electrically initiated
ammunition. See Chapter 6.
1.3.4.5.
Explosives Storage Site/Depot Safety
a)
Protective Zones Around a Depot or Storage Site.
Subject to national regulations it is advisable that any depot or Potential Explosion Site
be surrounded by zones, out to the distance at which the hazard is considered tolerable,
within which construction is controlled or made subject to special authorization.
b)
Procedures for Safety Site Plans.
1)
Since all explosives areas require quantity-distance (QD) separations, a safety
site plan is necessary to demonstrate these separation distances are provided
before construction commences, or explosives are deployed into any given
area. Maps and drawings will demonstrate graphically that separation distances
are in compliance with appropriate tables in this Manual. The damaging effects
of potential explosions may also be altered by barricades and specialized
construction features. Site plan submissions will also demonstrate when these
features exist and provide details for review by safety authorities. The
following kinds of information constitute a safety site plan:
(a)
A Q-D schedule providing the hazard division and net explosive
quantity (NEQ) assigned to each potential explosion site (PES).
(b)
A map of the explosives area in relation to other internal facilities and
buildings, surrounding villages, highways and cities (exterior Q-D).
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(c)
Drawings showing the location of explosives buildings in relation to
one another (interior Q-D).
(d)
Drawings showing details of construction features which affect
quantity-distances
2)
The NATO force sponsoring the new facility should require the preparation of
a safety site plan and its submission through appropriate military and national
authorities for review and approval. Normally, the military command planning
to use the new facility will provide the specific details to support preparation
of the site plan document. However, administrative details are the business of
individual member nations. The intent of this requirement is to ensure that
documentation is provided for competent review before funds are committed.
1.3.4.6.
Levels of Protection
A more detailed examination of the levels of protection afforded by the quantity-distances
given in Annex I-A Tables 1A to 3G and of the structures and activities considered acceptable at each
protection level is given in Part I, Chapter 3, Section VII for Hazard Division 1.1.
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Section V - Storage Buildings: General Principles and
Influence on Quantity-Distances
1.3.5.1.
General
a)
It is not considered practicable to construct surface buildings which withstand direct
attack by hostile activities but in order to reduce the hazards and the quantity-distances as
far as practicable, certain precautions in building construction should be observed.
b)
The construction of buildings for one hazard division only is uneconomic. Buildings may
be used for storage of different hazard divisions because storage requirements vary in the
course of time.
c)
The distances in Annex I-A, Tables 1 to 3 are based on explosives safety. They do not
take account of structural requirements, space for roads and access for fire-fighting.
These practical considerations may require greater distances than given in the tables.
Guidance on structural requirements is given in Part II, Chapter 3, Section II.
1.3.5.2.
Igloos
a)
A storage site comprising igloos gives the simplest and safest set of Inter-Magazine
Distances when it is a rectangular array with the axes of the igloos parallel and the doors
all facing in one direction. A front-to-front configuration should be avoided since this
requires a very large separation of the igloos. It may be expedient to arrange the igloos
back-to-back in two rows, but this configuration may be less flexible for further
development of the storage area.
b)
Igloos which conform to the minimum design criteria in Part II, paragraph 2.3.2.2.
qualify for reduced Inter-Magazine Distances compared with other types of aboveground
magazines and open stacks. Igloos of a strength exceeding the minimum prescription may
warrant further reductions in Inter-Magazine Distances. Conversely, the other earth-
covered buildings depicted in the Annex I-A PES-ES matrices require larger Inter-
Magazine Distances. It is for the National Authority to balance the cost of various types
of construction against the cost and availability of real estate and to determine the
optimum balance in any particular situation.
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