296 Propellants, Explosives, Pyrotechnics 26, 296 301 (2001)
Review on the Assessment of Safety and Risks
Carl-Otto Leiber*
Fraunhofer-Institut f�r Chemische Technologie (ICT), D-76327 Pfinztal (Germany)
Ruth M. Doherty
Naval Surface Warfare Center, Indian Head, Maryland (USA)
Dedicated to Dr. Axel Homburg on the Occasion of his 65th Birthday
Summary be controlled by sensitivity data. From this conclusion it is
inferred that very insensitive explosives should not be prone
Historically explosion accidents are linked with energetic materials.
to unwanted explosion catastrophes. But explosion hazards
There is the further belief, that the proneness to accidents and their
of chemicals that are not considered to be explosives teach us
severity is linked with the sensitivity of these explosives. Conse-
that this assumption is misleading. Also explosives sensiti-
quently there exist seemingly very insensitive materials for which it is
believed that their accidental explosion can be ignored, so that safety vity testing shows that current methods cannot predict such
distances can be reduced to those that apply to materials for which the
explosion hazards. Therefore, the instruments for safety
hazard is assumed to be mass fire rather than mass detonation. Evi-
show great value, but can fail completely in some cases.
dence is presented here that shows these assumptions to be invalid.
Whereas the explosion of explosives is an experience over
Reports of explosion accidents are gathered here for substances that
are not generally considered to be explosives (non UN-class 1 sub- hundreds of years, explosion accidents not based on explo-
stances, like ammonium nitrate (AN), neat alkali metal chlorates, and
sives was experienced very late in the last decades. Never-
even hypochlorites and nitromethane). In most of these cases the
theless these had been present in nature allover the lifetime of
proneness of accidents had not been foreseen by testing.
the universe.
The basic explosion mechanisms are of a more general nature than
simply those that apply to high explosives. Explosion is not solely a
Never it had been attempted to consider all these explosion
matter of energy, but of any physical power conversion. In order to
events under a common view. It is challenging, therefore, to
prove this, a survey of explosion events is given: Natural events, like
search for possibly joint elements. One only knows, that any
the impacts of celestial bodies and volcanic eruptions. Fuel=liquid
understanding is too poor to allow prediction of these events.
interactions in nature are industrial risks too, which occur at very
different occasions and sites: Cellulose processing, the oil industry,
If the dimensions in nature or in the technical world get large,
foundries, power stations, explosions of hot cinders, chemical pro-
mostly effective help is not possible if such catastrophes
cessing, fire extinguishing, and (most common) in the kitchen, and
result.
(most catastrophic) in nuclear reactors. Explosions of similar type are
Hydraulic Transients, Bubble resonance explosions with the possibility
of associated chemical room explosions (BLEVE), Rollovers. Second
order effects are sorption=desorption resonance explosions, which
2. Early Experiences with Explosives
most powerful also occur in nature (Nios Lake (CO2-release), Kivu
Lake, Monoun Lake, 1984, Tanganjika Lake, all in Africa, and the
Ocracoke in the Gulf of Mexico (CH4-release) and at the lowest end
While explosions have occurred with black powder over
shaken champagne bottles.
the centuries, the discovery and industrialization of nitrocot-
All these explosions are   low probability high risk  explosive
phenomena, which are scarcely coverable by risk studies with the pre- ton by Sch�nbein, and nitroglycerine by Sobrero and Nobel
sent day scientific tools on explosion phenomena. Up to now only in the
in the second half of the last century was a bloody success
nuclear branch a quantitative risk of explosion was brought to attention,
story. Nearly all possible failures leading to catastrophes with
therefore, the validity of this approach was carefully examinated.
these materials have been experienced. It was learned that
heat, shock, friction, chemical compatibility, phase transi-
tions, all kind of sparks and so on can cause for explosions. At
1. Introduction
the time of this development, the influence of viscosity and
the heterogeneity of the explosive on its sensitivity had been
Classical explosions of usual explosives are attributed to
recognized (blasting gelatin) but the general applicability of
stimuli and threats, which beyond a certain sensitivity level
these principles was not too widespread.
(can) lead to explosions. Therefore, explosion events seem to
Nitrocotton powder, poudre B, and picric acid were used in
military applications after their commercial development,
and military use was based on civil practice. Considering the
* Corresponding author; e-mail: [e-mail], formerly
member of WIWEB, Swisttal-Heimerzheim. consumption of military and commercial explosives over 100
# WILEY-VCH Verlag GmbH, D-69469 Weinheim, 2001 0721-3115/01/0612 0296 $17.50�:50=0
Propellants, Explosives, Pyrotechnics 26, 296 301 (2001) Review on the Assessment of Safety and Risks 297
years, this was a good deal. It is less widely known that the detected phenomena that we attribute today to Low Velocity
amount of commercial explosives consumed exceeds at least Detonation phenomena, the officially adopted reason was
by an order of magnitude that of military explosives (exclud- that, most probably, the double salt (ammonium nitra-
ing the time of the world wars). This is also the reason why te=ammonium sulfate) demixed. But a regulation was
there is considerable feedback of experiences regarding the issued: Do not blast ammonium nitrate containing mixtures.
safety of commercial explosives, which is usually not present Even after the Oppau experience, no instrumentation was
to such an extent for military articles. Therefore, with respect developed that could predict such a hazard. More cata-
to explosion phenomena and irregularities, we get the most strophes of the same (Tessenderloo, Belgium, 1942) or
input from the commercial side, see Table 1. similar kind resulted. Examples are Texas City (1947),
Brest (1947)(9), the Black Sea, and Japan for ammonium
nitrate initiated by external fires. None of these accident
investigations resulted in a means of evaluating the risk
3. Catastrophic Interaction between Theory and
associated with these materials. But we must keep in mind
Safety
that the most common response of ammonium nitrate to an
external fire is burning.
Explosion accidents in which the cause can be found in
Other explosion hazards have been observed around the
classical threats occur with military as well as industrial
world with non UN-class 1 substances. Some of these have
explosives. But there are also accidents for which the cause is
occurred spontaneously (by marshaling i.e., handling in
less obvious, or is not explainable in current terms. For any
railway yards), but usually they are caused by external fires.
assessment of the cause, an insight into explosives behavior,
Examples are nitromethane explosions, 1958(13), MMAN-
usually provided by a model or theory, is necessary.
explosions(14) (marshaling), and explosions of pure chlo-
The physical phenomenon of the detonation of gases was
rates, perchlorates and even bleaching powders by external
discovered in 1882 by Mallard and Le Chatelier, and also
fires. These have been known since 1899. The latter sub-
Berthelot and Vieille. In 1893 Schuster(12) made a discussion
stances do not show any indication of an explosion hazard by
note to Dixon s lecture on gas detonation. This discussion
classical testing. One can speculate, therefore, on what is the
note just contained in principle the current detonation theory.
point of such tests, which cannot even predict the cratering
It is remarkable, that Schuster also pointed out the weakness
risk if a drum falls from the table to the floor.
of this theory. But this theory, known as the piston model of
The most insensitive explosives and articles are assigned
detonation, was so successful for gases that it was also applied
for condensed explosives. A plane piston in motion com- to UN-class 1.5 and 1.6, defined by appropriate testing(15). It
is stipulated that the probability of any accidental explosion
presses and heats up the material until by thermal means a
is negligible. Therefore, reduced safety distances based on
decomposition occurs, which drives this piston, and plane
the expectation of mass fire rather than mass detonation, are
detonation waves result. This was the origin of the thermally
thought to be adequate. Serious consideration should be
driven detonation.
given to whether such a conclusion is really acceptable. For
In accordance with this theory, supported by   appropriate 
the following reasons it really is not. Originally, the UN-class
testing, at the beginning of the last century it became
1.5 had been created for ANFO- and slurry-explosives, which
common practice, approved by authorities, to loosen heaps
are used as explosives, but in hazard classification tests show
of ammonium nitrate (AN) by blasting procedures. After the
no apparent explosive properties. Nevertheless, the compar-
first accidents, the ammonium nitrate was desensitized
ison of explosion hazards shows that there are a greater
(Oppau-salt), until the first large industrial catastrophe of
number of explosion hazards on 1.5-substances compared to
the last century resulted. Even after this catastrophe by
explosives like TNT and others(16). (In order to remain honest,
classical testing also applied nowadays this risk could
we should note that much larger quantities of commercial
not be evaluated. In spite of the fact that Poppenberg, who
explosives are produced than classical 1.1-explosives.)
was not officially involved in the accident investigation,
Table 1. Major Explosion Accidents Contributing to Safety Science
Year Location Kind and amount Consequence estimate
1920 Stolberg(1,2) AN, all induced by Civil explosion
1921 Kriewald(1,2) blasting 19 died, 23 injured
1921 Oppau(1,2,5) 25 t AN, 561 died, >1991 injured
4500=750 t AN � sulfate
1942 Tessenderloo, Belgium(1) 150 t AN, the same as in Oppau 100 killed
happened
1944 Port Chicago, USA(4,7) 2100 t ammunition 320 killed, 390 injured
1947 Texas City (2 x)(4,8) 2300=962 t AN 450 died, 4000 injured
Fire ) explosion
1967 (4) Fire ) explosion 134 killed, 162 injured
1899- Many Chlorate explosions(10,11) Fire ) explosion Many victims, serious damages
also mechanical impacts
298 C.-O. Leiber and R. M. Doherty Propellants, Explosives, Pyrotechnics 26, 296 301 (2001)
4. Regulations 5. Case Histories of Non-Chemical Based Explosions
(Physical Explosions)
Explosives safety has been evaluated by accidents that
have occurred. All these experiences have been con-
5.1 Nature
densed into rules and laws describing what is proper
and what is not. Since the railways were the first motor
All over the times celestial bodies impacted the earth with
of progress, these early experiences have been interna-
gigantic effects, where the explosion by itself was not the
tionally written into legal rules for transportation, which
most serious. As example, in 1994, the impacts of parts of
still apply today. These rules have also been adopted
Shoemaker-Levy on Jupiter demonstrated such events from a
successively by other responsible agencies, which added
safe distance, where the impacts on Jupiter resulted in
their own points of view. Contrary to the classical
  craters  of the dimensions of the earth.
explosives regulations, which prescribed the means of
The Tunguska-Event demonstrated, that such celestial
achieving safety goals, the modern approach in nuclear
body impacts should be taken into considerations for risk
and chemical safety regulations is to set general legal
studies. So in 1908 a celestial body (probably a meteor) with
goals for safety and leave the means of achieving them to
an estimated size of 30 m in diameter and a velocity of
be determined. Nevertheless all regulations have not only
between 50 and (near the surface) 3 km=s destroyed about
a real scientific and=or technical basis, but also many
1200 km2 of the Siberian taiga. The pressure waves were
other combined interests, may be from practicability or
recorded even in Germany.
from economic interests. Therefore, the regulations also
As models for the nuclear winter volcanic explosions have
differ, sometimes greatly, depending on the interests of
been considered in the past. Within historical times the most
the user.
powerful event had been 1815 with the Tambora eruption of
An early answer for safe distances was given by the
about 150 180 km3, and Krakatoa in 1883 with   only  about
New Jersey tables of distances with respect to storage and
18 km3 erupted mass. It is a characteristic of such events, that
manufacturing. Whereas the old New Jersey and German
the number of immediate victims can be (as in the case of
distances, based on actual accidents, used larger distances,
Tambora) of the order of 12 000, but in time this number
the later NATO distances were reduced according to a
increased to much more than 80 000 due to famine in the
reasonable risk with respect to defense(24). The K-
immediate neighborhood, and much more all over the world.
pffiffiffiffi
3
factors are defined as K ź D �in m�= m �in kg�; where D
Many social changes positive and negative resulted.
is the distance in meters, and m is the applicable weight of
As a natural forerunner of industrial explosions appear the
explosive (TNT) in kg. Whereas the NATO-criteria
Crater Lake Formations, where hot magma interacts with
expect a safe distance at K ź 22.2 for a normal house,
water. Powerful steam explosions result in the formation of
K ź 55.5 for hospitals and other most sensitive buildings,
crater lakes (German word:   Maare  , creation about 30 000
we know from real accident experiences (Port Chicago,
years ago). In the spring 1977, the formation of two such
1944) that the limit for injured persons can be K ź 157,
crater lakes within 11 days was observed in Alaska (Ukinrek
and that of glass fracture K 300. One reason for this is
crater lakes).
that in the military, field damage criteria are in use. But it
cannot be concluded that at distances beyond   a guaran-
teed damage level  safety is present. Since tables of 5.2 Industrial Catastrophes
distances cannot be easily evaluated in a civil world, the
NATO-table of distances was adopted in many civil Classical examples of industrial physical explosions are
regulations as a scientific result. cavitating hydraulic Joukowski shocks, the fuel=liquid inter-
Regulations can also have an adverse effect on safety. actions (FLI), which are more commonly known as vapor
The density of regulations by various responsible agen- explosions. These appear in many types of industry, such as
cies has increased to such an extent, that it has now manufacturing of cellulose, oil industry, foundries, power
become easy to attribute an accident that occurs to the stations, explosions of hot cinders, in chemical processing,
violation of a rule, and more detailed explorations are by fire extinguishing, and most often in the kitchen. The most
often not felt to be necessary to the detriment of real catastrophic case is in nuclear reactors.
safety. Explosion probabilities could not be determined until
Another misleading input both from theory (piston nuclear reactor safety claimed the numerical evaluation of
model of detonation) and the regulations is the definition the probability of such a risk for the first time. What was the
of an explosion as the consequence of the gas production procedure? They defined that any vapor explosion is caused
rate by a chemical decomposition. This definition erro- by a melt fragmentation only(25). This was also brought into
neously suggests that only chemically reactive substances an official definition of a physical explosion(26). An estimated
can be sources of explosion hazards. Due to this definition, probability of an explosion was attributed to a given core
more general explosion hazards have been completely meltdown. Then, as a solution, the risk of a core meltdown is
excluded from any safety considerations. But there are quantitatively downcalculated. It is therefore a real matter of
many examples of explosion hazards that do not involve safety science to verify or disprove such a masterpiece since
chemical decomposition. up to now explosion risks had been quantified only in the
Propellants, Explosives, Pyrotechnics 26, 296 301 (2001) Review on the Assessment of Safety and Risks 299
nuclear branch, but never in the fields of industrial explosions exploding monergol tanks is around 2 GPa at the low end
and even not in explosives safety. The following case (LVD), and more than 10 GPa at the upper end.
histories demonstrate that this criterion is not adequate.
Explosions occur also without any fragmentation. 5.2.4 Explosion of Liquid Carbon Dioxide Tanks
It was therefore   luck  that in the past several explosions
5.2.1 Hydraulic Transients
occurred with liquid pressurized carbon dioxide vessels
(1.5 MPa, 30 C), well below the superheat limit. These
Hydraulic transients are well known as Joukowski shocks,
accidents are of value for the following reasons:
but if these are cavitating, a powerful pressure augmentation
can take place. An improper release of water in the Tarbela
The superheat theory is invalidated.
dam, 1974, Pakistan, resulted in a powerful explosion.
Furthermore, according to the Mollier phase diagram,
with isenthalpic depressurization to atmospheric pres-
5.2.2 Vapor Explosions
sure, at 0.52 MPa, 50 weight % of the carbon dioxide
condenses to   dry ice  (i.e., solid CO2). Therefore, any
5.2.2.1 Quebec Foundry Accident
hypothetical propelling gas phase is drastically reduced.
45 kg molten steel of 1560 C dropped into 295 l water. By
By simple shock wave considerations one gets from the
calculation only 16 l water evaporated, but the explosion that
maximum detected fragment width of 350 m in this case a
occurred had the effect of about 5.4 kg TNT. Cratering and
condensed phase pressure of the order of 700 MPa, which
explosive devastation were observed, and up to 53 m away
is attributable to an explosive event.
brick walls were affected; more than 6000 windows were
Without any chemical reaction, such types of explosions
broken(27).
can occur spontaneously (Brooklyn, 1971, liquid oxygen
It is unlikely that this is the result of evaporated water
accident), by weak mechanical impacts (or even in their
driving a pressure piston. Even if 1 cm3 water is evaporated at
absence) as in marshaling, or by stronger impacts like derail-
constant volume, at 1200 C only 7.325 bar can result�, far
ment, and finally by external fires as for example the Crescent
from any cratering capability.
City, and Challenger(32), 1986, events demonstrate. Some-
times there are observed indications of build-up to such an
5.2.2.2 Reynolds Metal Co., McCook, USA, 1958
explosion: unusual noises in the tank, or repeated safety valve
Moist or possibly wet scrap aluminum was inserted in a
clearances, but this is no reliable rule.
melting furnace. An explosion caused 6 victims, and 40
The dimethyl ether accident in Ludwigshafen(33) (1948)
injured. The damage was of the order of 1 million US$(28).
demonstrates that there may also be political aspects of
This accident shows, that the explosion damage does not
explosive accidents. A witness saw that the tank car dis-
correlate with the mass of the water that can be evaporated.
mantled, and after the sudden and violent dispersion of the
contents a room explosion followed, causing widespread
5.2.3   Boiling Liquid Expanding Vapor Explosions
devastation, 207 victims, 3800 injured people, damages at
(BLEVE) 
3200 buildings, and 9450 flats. After World War II it was
rumored even from explosives authorities that Germany
Liquid (pressurized) gas explosions of any kind (LNG, O2,
again was working on miraculous explosives. It was lucky
NH3, CH4, C2H6. . . , vinyl chloride, etc.) demonstrate best,
that an international committee, with such prominent
that a fragmentation process is not required for any explosive
members as Stra�mann (nuclear researcher), Professor
event. A foaming up (by superheat in the case of a depressuri-
Richard, Nancy, and mining engineer Stahl, Washington,
zation) and=or evaporation=condensation- or sorption=
testified that the explosion was not the result of a super
desorption-resonances activated by mechanical means
explosive. But they did not recognize the reason, and
(shaking of a champagne bottle) or thermal transfer processes
speculated on a thermal overfill, and a concatenation of
is postulated to be the cause. Since Rayleigh we have known
misfortunes, ignoring thereby very similar accidents before
that the pressure in the condensed phase of a collapsing
(1943). Other accidents of the same type followed therefore.
cavity is of the order of 2 GPa. But current accident
investigations have concluded, erroneously, that the highly
5.2.5 Shocks in Silos
increased gas pressure ruptures the vessel at the site of any
(assumed or real) embrittlement, and induces fragments. The
For powdered solid materials silo-shocking appears to be
evaporated gas would propel the relatively large fragments,
the equivalent of the bubble resonance explosions of liquids.
which travel an increased distance by virtue of the aero-
This can be produced by a sudden breakdown of so-called
dynamic lift(29 31).
  silo bridges  if a silo is being cleared. An explosive silo
This view is invalidated by comparing the fragment
rupture can result, predominantly if the grains are very
distances and fireball-diameters and -durations (in the case
uniform in size. In performing the Low Velocity Detonation
of combustible gases) with exploding monergol tanks, which
studies on neat chlorates, experiments were also carried out
are approximately the same. The order of the pressure of
on salt (sodium chloride) of very uniform grain size, and sand
of varying grain sizes. The result was that the shock driven
�
Kindly Dr. Volk, ICT, calculated these values. compaction of salt dented a lead ingot, whereas sand did
300 C.-O. Leiber and R. M. Doherty Propellants, Explosives, Pyrotechnics 26, 296 301 (2001)
not(17). Examples of bubble resonance explosions are given The Nios Lake (Cameroon) contained about 4 m3 of
in Table 2. dissolved CO2 per m3 water. It was estimated, that in 1986
150 106 m3 CO2 explosively degassed, and still 250 106 m3
remained in the water. Further explosive degassing occurred
5.2.6 Rolling Over
with methane (Kivu Lake, Monoun Lake, 1984, Tanganjika
Lake, all in Africa, and the Ocracoke in the Gulf of Mexico).
Liquids of different densities (perhaps caused by different
All these eruptions caused many victims by suffocation.
temperatures of the same liquid, or different gas saturation, or
Another effect of degassing is that the original liquid s
completely different and immiscible liquids) can be layered.
density decreases drastically by sparkling and foaming up, so
Such a situation can also result from an external fire, which is
that a normal ship (built for normal water buoyancy) sinks
extinguished. This is not a stable condition. The liquids can
into this foam.
suddenly mix by (an external) mechanical stimulus, or in the
case of different temperatures by thermal conductivity. It was
less well-known that above a critical difference in tempera-
ture, even after long times, a spontaneous onset of fluid
6. Conclusions
convection (Benard-convection) results. This can increase by
several orders of magnitude the thermal conductivity, so that
A great number of victims of explosive accidents have
a whole system can be equilibrated within short times. The
accumulated over the centuries. The most spectacular
result is that volatile products suddenly evaporate, and by
numbers resulted from unforeseen or unexpected explosions.
temperature balancing dissolved gases degas in the liquid. An
(A rough estimate from explosion hazard studies indicates
explosive foaming up, creating damage like explosions, is
that about 1% or less of all explosion accidents resulted in
then possible. But all degrees between quasi-static and highly
about 70% of all victims.) These appear therefore as   low
dynamic events are commonly observed. Examples are given
probability high risk  explosive phenomena, which are
in Table 2.
completely outside of the present scientific considerations.
It seems outmost likely that the understanding of the nature of
explosions is not adequate. In the following article   Physical
5.2.7 Spontaneous Degassing
Model of Explosion Phenomena  this question is focussed in
Tectonic gases can dissolve in any kind of water, where
more detail.
their solubility depends on the static pressure. In the deep
Our personal conclusions are that even if there was a
water the gas concentration is highly increased compared to
predictive capability for all of these types of explosive
the surface layers, and the density reduced, so that a
hazards, there exist real limits to the size of explosive
(gradually) layering results. Mass transfer can be started by
incidents of which the catastrophic consequences can be
any mechanical or thermal instabilities, which can lead to a
managed, controlled, or avoided.
spontaneous, even explosive, degassing(36).
7. References
Table 2. Examples of Bubble Resonance Explosions
LNG-tanks Cleveland, Ohio (1944), La Spezia (1) G. S. Biasutti,   History of Accidents in the Explosives Industry  ,
Vevey, published by the author; J. Pointner,   Im Schattenreich
Liquid gases of all kind LNG, O2, NH3, CH4, CO2,
der Gefahren  , Int. Publikationen, GmbH, Wien, 1994.
propane. . . , vinyl chloride. . . .
(2) R. Assheton,   History of Explosions on which the American
External fire Propane, Crescent City, 1970
Table of Distances was Based  , Bureau for the safe Transpor-
After extinguished Butyl alcohol, Litchfield, 1967
tation of Explosives and other Dangerous Articles, The Institute
external fire Vinyl chloride, Sch�nebeck, 1996
of the Makers of Explosives, 1930.
By mechanical impacts NH4, Crete, 1969
(3) L. Spencer,   Explosive Lessons  , Hazardous Cargo Bulletin,
By mechanical rupture CO2, Haltern, 1976
20 21 (November 1980).
of the vessel
(4) I. M. Korotkin,   Seeunf�lle und Katastrophen von Kriegschif-
Apparently spontaneous
fen  (5th ed.), Brandenburgisches Verlagshaus, Berlin, 1991.
(5) H. Kast,   Die Explosion von Oppau am 21. September 1921 und
Oils Shell-Pernis (1968) (mechanism
die T�tigkeit der Chemisch-Technischen Reichsanstalt  , Son-
first evaluated)(34)
derbeilage zur Zeitschrift f�r das gesamte Schie�- und Spreng-
Triest, Oil tank sabotage, 1972
stoffwesen 20, (1925) and 21 (1926);   Bericht des 34.
Tacoa, Venezuela, 1982, many
Untersuchungsausschusses zur Untersuchung der Ursache des
victims: Burning oil erupted like
Ungl�cks in Oppau  , Zeitschrift f�r das gesamte Schie�- und
from a volcano, and distributed
Sprengstoffwesen 19, 42 46 and 60 63 (1924).
fire simultaneously over a large
(6) L. Spencer,   An Act of Self-Mutilation  , Hazardous Cargo
area(35)
Bulletin (April 1981) pp. 25 26.
(7)   The Port Chicago, California, Ship Explosion of 17 July 1944  ,
Tectonic CO2 in a lake Nios Lake, great amounts
Technical Paper No 6, (1948), Army-Navy Explosives Safety
Tectonic CH4 in a lake or sea of explosively deliberated carbon
Board, Washington, DC, USA.
dioxide produced about 2000
(8) G. Amistead,   The Ship Explosions at Texas City, Texas on April
victims, and many animals died
16 and 17, 1947 and their Results  , Report to John G. Simmonds
by suffocation(36)
& Co Inc., Oil Insurance Underwriters, New York City (1947);
Propellants, Explosives, Pyrotechnics 26, 296 301 (2001) Review on the Assessment of Safety and Risks 301
Elisabeth Lee Wheaton,   Texas City Remembers  , The Naylor (22)   Hazard Studies for Solid Propellant Rocket Motors (Etudes des
Comp., San Antonio, Texas, 1948. Risque pour les Moteurs-Fus�es ą Propergoles Solides)  ,
(9)   Rapport Annuel sur l Activit� du Corps des Sapeurs Pompiers, AGARDograph No. 316, AGARD-AG-316, September 1990,
Ann�e 1947  , Ville de Brest, Archives Municipales; L. Spencer, 191 pp.
  Learning the Hard Way  , Hazardous Cargo Bulletin (Feb. (23) K. Nabert and G. Sch�n,   Folgerungen aus den Untersuchungen
1981), pp. 22 23. �ber die Ursache der Explosionskatastrophe bei Bitburg  , Erd�l
(10) C. O. Leiber,   IHE-2000, Wunsch und Wirklichkeit  , 11. und Kohle 8, 809 810 (1955).
Sprengstoffgespr�ch, 5. 10. 1987, Mariah�tte, in Japanese: (24) NATO=AC 258 documents.
Journal of Industrial Explosives Society 49, 300 304 (1988) (25) F. Mayinger,   Wie sind Dampfexplosionen im Lichte neuerer
(K�gy� Kayaku), Japan. Erkenntnisse zu beurteilen?  , Atomwirtschaft (Feb. 1982),
(11) M. Steidinger,   Die Gefahrklassifizierung von Alkali- und pp. 74 81.
Erdalkalichloraten  , Amts- und Mitteilungsblatt der Bundesan- (26) B. Lafrenz,   Physikalische Explosionen  , Fb 771, Bundesanstalt
stalt f�r Materialforschung und -Pr�fung (BAM) 17, 493 504 f�r Arbeitsschutz (1997).
(1987). (27) S. G. Lipsett,   Explosions from Molten Materials and Water  ,
(12) A. Schuster,   On the Rate of Explosion in Gases  , Note to H. B. Fire Technology 2, 118 126 (1966).
Dixon, Bakerian Lecture, Phil. Trans. Royal Society, London A (28) L. F. Epstein,   Metal-Water Reactions: VII. Reactor Safety
84, 152 154 (1893). Aspects of Metal-Water Reactions  , GEAP-3335 (1960),Valle-
(13) Ex Parte 213,   Accident near Mount Pulaski, Ill.  , Interstate citos Atomic Lab., GE Co, Pleasanton, CA, USA.
Commerce Commission No 305; R. S. Egly,   Analysis of (29) C. O. Leiber,   Explosionen von Fl�ssigkeits-Tanks. Empirische
Nitromethane Accidents  , Symposium on Safety and Handling of Ergebnisse Typische Unf�lle  , Journal of Occupational Acci-
Nitromethane in Military Applications, Monroe, Louisiana, dents 3, 21 43 (1980).
14 15 November, 1984. (30) R. A. Strehlow and W. E. Baker,   The Characterization and
(14)   Monomethylamine Nitrate Explosion, Wenatchee, Wash., Evaluation of Accidental Explosions  , NASA CR 134779 (1975).
August 6, 1974  , NTSB-RAR-76-1 (1976), Railroad Accident (31) K. Gugan,   Unconfined Vapour Cloud Explosions  , Rugby,
Rept., Burlington Northern Inc. Warks, 1978.
(15)   Recommendations on the Transport of Dangerous Goods (Tests (32) Report to the President by the Presidential Commission on the
and Criteria)  , Rev. 1, United Nations, February 1989. Space Shuttle Challenger Accident, 6. 6. 1986, Washington.
(16) J. Prinz, private communication, 18. 11. 1991. (33) B. Schnell,   Erster zusammenfassender Bericht �ber die Unter-
(17) C. O. Leiber,   Detonation Model with Spherical Sources H: Low suchungen zur Aufkl�rung der Ursache der Explosionskata-
Velocity Detonation of Solid Explosives A Summary  , 18th strophe vom 28. 7. 1948 bei der B.A.S.F. Stand vom 4. 9. 1948  ,
Int. Pyrotechnics Seminar (IPS), Breckenridge, CO, 13 17 July Referat vor dem Parlamentarischen Untersuchungsausschu� des
1992, pp. 563 591: Journal of Industrial Explosives Society 48, Landtags Rheinland-Pfalz [Report at the parliamentary fact-
258 271 (1987) (K�gy� Kayaku), Japan. finding committee of the parliament of Rheinland-Pfalz]; Storch,
(18) C. O. Leiber,   On Double Explosions  , 18th Int. Pyrotechnics   Bericht �ber die Explosionskatastrophe in der Badischen Ani-
Seminar (IPS), Breckenridge, CO, 13 17 July 1992, pp. 593 606. lin- und Sodafabrik in Ludwigshafen am 28. Juli 1948  ,
(19) P. Lamy, C. O. Leiber, A. Cumming, and M. Zimmer,   Air Arbeitsschutz 1, 34 35 (1949).
Senior National Representative Long Term Technology Project (34) Brief vom Minister f�r Soziales und Volksgesundheit No 1
on Insensitive High Explosives (IHEs) Studies of High Energy vom 26. 3. 1968 an den Vorsitzenden des Parlaments (der Nie-
Insensitive High Explosives  , 27th Int. Annual Conference of derlande) [Letter of the Minister of Social Affairs and Health,
ICT, Karlsruhe, Germany, June 25 28, 1996, pp. 1.1 1.14; No 1, dated March 26, 1968, addressed to the President of the
  Collaboration on insensitive high explosives  , J. Defence Sci- Parliament (of the Netherlands)].
ence 1, 539 546 (1996). (35)   Boilover im Kraftwerk Tacoa  , Magazin der Feuerwehr 8,
(20) R. Loison,   Propagation d une d�flagration dans un tube recou- 468 474 (1983).
vert d une pellicule d huile  , Comptes Rendus 234, 512 513 (36) K. Tietze,   Gefangene Gase in geschichteten Seen  , Frankfurter
(1952). Allgemeine Zeitung, 10. 9. 1986, Nr. 209, p. 31. Personal com-
(21) C. O. Leiber, P. Steinbei�, and A. Wagner,   On Apparent Irre- munications (as primary investigator).
gularities of Pressure Profiles in Shock Tubes  , EUROPYRO93,
5e CongrŁs International de Pyrotechnie du Group de Travail,
Strasbourg, June 6 11, 1993, pp. 171 178. (Received March 8, 2001; Ms 2001=057)