Accidents in the Manhattan project
During the Manhattan project there were three fatal
accidents that caused the death of four people for high
exposure to nuclear radiation. These people were brilliant
engineers chemists and scientists who because of poor
security measures ended prematurely their lives and their
contribution to the development of the first atomic bomb.
These are their names:
Peter Newport Bragg Jr. 1920 – 1944
Douglas Paul Meigs 1918 – 1944
Harry K. Daghlian, Jr. 1921 – 1945
Louis P. Slotin 1910 - 1946
The Philadelphia Explosion
On September 2, 1944, three men entered the transfer room of the
liquid thermal diffusion semi-works at the Philadelphia Navy Yard to
repair a clogged tube. The tube they were working on consisted of
two concentric pipes with liquid uranium hexafluoride circulating in
the space between them; the innermost pipe contained highpressure steam. Kneeling on the floor with a Bunsen burner, Bragg
and Meigs worked to free the clogged tube. Without warning, at
1:20 PM, there was a terrific explosion. As the tube shattered, the
liquid uranium hexafluoride combined with the escaping steam and
showered the two engineers with hydrofluoric acid, one of the most
corrosive agents known. Within minutes, both Peter Bragg and
Douglas Meigs, with 3rd degree burns over their entire bodies. Due
to the extreme secrecy surrounding the Manhattan Project in general
and the experimental facility at the Philadelphia Navy Yard in
particular, an immediate veil was drawn down over the incident by
the highest authority available: General Leslie Groves. Due to the
extreme secrecy surrounding the incident, even the Philadelphia
coroner was not made aware of the actual causes of death.
The Philadelphia
Record Philadelphia,
Pa. September 3, 1944
"9 Are Injured; Blast Heard in
Wide Area"
SIDE OF BUILDING RIPPED OUT; FIRE EXTINGUISHED - Two specialists
were killed and nine other men injured late yesterday afternoon
when an explosion, followed by fire, ripped out the side of a building
at the Navy Yard.
Gas was released, burning the lungs of some of the men. They were
given first aid at the scene and then sent to the Naval Hospital. At
least one is in "a very critical condition," the Navy announced.
Two other men, Navy Yard firemen, collapsed while fighting the
blaze. Their condition is not serious.
The two men who died following arrival at the Naval Hospital were:
Douglas P. Meigs, 26, Tacoma Park, Md., an employee of the H. K.
Ferguson Company of Cleveland.
Peter N. Bragg Jr., 24, Fayetteville, Ark., a Navy chemical engineer.
The injured included five U. S. Army first class privates
Peter Newport Bragg Jr.
A brilliant
chemical
engineer, he
volunteered for
a dangerous
assignment
while employed
by the U. S.
Navy Research
Laboratory's
"pilot-plant" at
the
Philadelphia
Navy Yard.
His work was crucial
to the development
of the first atomic
bomb, and in his
own way, his
contribution helped
bring about an early
end to World War II.
Douglas Paul Meigs
A brilliant chemical engineer too, he volunteered for a
dangerous assignment while employed by the H. K. Ferguson
Company of Cleveland, OH.
The dragon bites
In August of 1945 and again, in May 1946, two
Los Alamos scientists were exposed to lethal
doses of radiation while performing
experiments to determine critical mass. These
experiments, performed at the Omega Site,
were commonly referred to as "Tickling the Tail
of the Dragon". Although several months apart,
both accidents occurred on a Tuesday and both
on the 21st of the month...and, both men died
in the same hospital room at the U.S. Engineers
Hospital at Los Alamos.
The first dragon bites
On 21 August, 1945, Daghlian was
involved with a series of experiments
at Omega Site. As he disassembled the
afternoon experiment, Daghlian began
planning the next criticality test and,
after making some final remarks in his
notebook, he decided to construct the
next assembly on a 10-5/8 inch square
base. After dinner, Daghlian began
thinking about returning to Omega Site
that evening to test the third assembly,
rather than the following morning as
originally planned. He was well aware
that this was against "official" safety
regulations on two counts, performing
a potentially hazardous experiment
alone after-hours
Photo of the critical assembly after the accident
and dismantling by Daghlian. A nickel-plated
sphere of 49 metal is shown supported by a WC
(tungsten carbide) cradle and surrounded by a
base of WC bricks.
Entering the laboratory, he found
Private Robert J. Hemmerly, a
Special Engineer Detachment
(SED) guard, seated at a desk and
reading a newspaper. Hemmerly
looked up apprehensively at a
somewhat anxious Daghlian, who
tried to mask his nervousness by
walking directly to the assembly
bench. Daghlian immediately set
about removing the 49 metal
sphere from the vault and
constructing the planned
assembly. As he attempted to
place another brick over the
center of the assembly with
his left hand, the "clicks" alerted him to the possibility that this addition would be
supercritical, and he immediately started withdrawing his left hand when the brick fell
from his grasp into the center of the assembly. Reacting instinctively, he pushed the
brick from the assembly with his right hand, which developed a tingling sensation as it
became enveloped in the blue glow surrounding the sphere.
At the time of the accident, Pvt. Hemmerly of Columbus, OH was 29 years old, married,
and the father of two children. On admission to the hospital, he was confined to bed for
two days of observation. Ten months following exposure, Hemmerly's physical condition
was unchanged and completely normal, and he had no subjective complaints
In contrast, Daghlian's total-body
radiation exposure was estimated to be
480 roentgens of soft x-rays and 110
roentgens of gamma rays, with
additional complications arising from
the non-uniform distribution of
radiation exposure, particularly to the
upper body and, especially, to the left
hand. On the tenth day after exposure,
Daghlian experienced nausea and
abdominal pain after eating. During the
course of his illness, Daghlian's medical
Daghlian's right hand nine days after the accident.
treatment was predicated on alleviating
his symptoms rather than attempting to
halt or reverse the radiation-induced
injuries
Several days prior to his death, he became irrational and slipped into a coma on the
final day of his life. Daghlian died at 4:30 PM on Saturday, 15 September, 1945; he had
survived almost 26 days after the accident at Omega
Harry K. Daghlian, Jr
Information provided in the press release
from Los Alamos led the New York Times
to report that Daghlian had died from
"chemical burns," rather than from the
results of radiation-induced injuries. This
omission, in effect, rendered Daghlian's
service and sacrifice a relatively obscure
footnote to the history of Project Y.
The dragon bites… Again
It happened in an instant. A sudden blue glow momentarily
enveloped the room before evaporating. In that moment, as the
Geiger counter clicked wildly, scientist Louis Slotin knew that he had
received a lethal dose of gama and neutron radiation from the core
of the plutonium bomb he was testing. It was 3:20 P.M. on Tuesday,
21 May 1946, at the secret Omega Site Laboratory. With his left
thumb wedged into a cavity in the top element, Slotin had moved
the top half of the sphere closer to the stationary lower portion, a
micro-inch at a time. In his right hand was a screwdriver, which was
being used to keep the two spheres from touching. Then, in that
fatal moment, the screwdriver slipped. The halves of the sphere
touched and the plutonium went supercritical. The chain reaction
was stopped when Slotin knocked the spheres apart, but deadly
gamma and neutron radiation had flashed into the room in a blue
blaze caused by the instantaneous ionization of the lab's air
particles. Louis Slotin had been exposed to almost 1,000 rads of
radiation, far more than a lethal dose
Slotin had been instructing a
colleague, Alvin C. Graves, who was
to replace him at the Omega Site.
Also present was S. Allan Kline, a
26-year-old graduate of the
University of Chicago, who had
been called over to observe the
procedure. Five other colleagues
were close by as Slotin, a Canadian
physicist from Winnipeg who had
been part of the team that created
the atomic bomb, performed the
action that would bring into close
proximity the two halves of a
beryllium-coated sphere and
convert the plutonium to a critical
state. There is some small variation
in detail about what happened
after Slotin knocked apart the two
beryllium spheres, while using his
body as a shield to protect the
other men.
The sketch was used by doctors to determine the amount
of radiation to which each person had been exposed.
After arriving at the Los Alamos hospital Slotin told Alvin Graves:
"I'm sorry I got you into this. I'm afraid I have less than a 50 per cent chance of
living. I hope you have better than that."
Many volunteers were ready to donate blood for the transfusions doctors deemed
necessary. Sadly, all efforts to save Slotin were futile. He died on 30 May after an
agonizing sequence of radiation-induced traumas including severe diarrhea and
diminished output of urine, swollen hands, erythema (redness) on his body,
massive blisters on hands and forearms, paralysis of intestinal activity, gangrene
and a total disintegration of bodily functions. It was a simple case of death from
radiation, similar to what American scientists and medical personnel saw in Japan
among A-bomb victims.
Dr. Louis Slotin at work, date and
location unknown.
It had been ominously augured by a very similar tragedy six months
earlier. Harry Daghlian, Slotin's friend and laboratory assistant, had
fallen victim to "the invisible killer". Deeply saddened by the mishap,
Slotin spent many hours at his assistant's bedside during the month it
took Daghlian to die. Thomas Brock quotes from a June 1946 letter from
Emily Morrison, Philip Morrison's wife, to a friend. It reveals the "series
of strange coincidences" involved in both mishaps: "Both Louis' and
Harry Daghlian's accidents occurred on Tuesday the 21st; both used the
same piece of material; and both died in the same room in the hospital."
After the 24-year-old Daghlian's death, Nobel Laureate Enrico Fermi
warned Slotin that he wouldn't last a year - "if you keep doing that
experiment." Following the Daghlian accident two tiny spacers were
developed to prevent the beryllium spheres from closing completely
together. It was hoped that this would prevent similar incidents. But
Slotin preferred a hands-on approach to experimentation. Slotin's death
ended all hands-on critical assembly work at Los Alamos. We
immediately started work on a remote control system with the critical
assembly equipment and the operating crew separated by roughly a
quarter mile. We had no more criticality deaths or injuries.
Louis P. Slotin