Los Alamos Incident One (LA-1)

Tales from the Nuclear Age:

copyright © 2009 by Charles Glassmire _________________________________________________________________

Sept. 23, 2009

Los Alamos Incident One (LA-1)…

     The day was August 21, 1945. The event occurred in a small wooden shack known as “Room 49”, although 49 wasn’t the room number. Rather, it was a code designation for the element Plutonium. Nobody at Los Alamos was allowed to mention “Plutonium”, let alone the specific isotope 239. So 94Pu239 was coded as “49” and this location was where experiments were done on the material. It was positioned on the side of a steep hill far from the main lab buildings and concealed in the Sangre de Cristo forest of the Manhattan Engineering District (soon to be known as Los Alamos Scientific Laboratory).

      By this date, the first Plutonium bomb (Fat Man) had already been dropped on Nagasaki, and performed as expected. Consequently, the Empire of Japan had surrendered a few days later. The War in the Pacific was over and the world fell into a fitful peace, but a lot was still unknown about the newly discovered element, and scientists were still probing its secrets.

      Harry K. Daghlian Jr. (pronounced “Dolly-an”) was a 24 year old Armenian-American physicist with the Manhattan Project. He was fresh from an assignment to assemble the plutonium core of the Trinity Shot, which had been tested successfully in July. Now he was assigned the task of gathering more data on Plutonium criticality. Born in Waterbury, CT, Harry was the child of Harry Sr. and Margaret Rose. His father was an X-ray technician at a hospital. His uncle was professor of physics at Connecticut College, and fostered Harry’s interest in math and physics. Harry Jr. studied Mathematics at MIT, and then transferred to Purdue, obtaining a B.S. in Physics in 1942.

      On the day of the incident, Harry attended a concert in the early evening, and then went back to his lonely shack in the woods to continue working; arriving about 9:30 p.m. (The site was called the “Omega Site”.) Inside the 49 room, seated at a desk across the room from the assembly, was Army Private Robert Hemmerly, on guard duty from the Special Engineer Detachment. Whenever Plutonium was in use, a guard had to be present. Hemmerly greeted him with a curious “Hi Harry” and resumed reading his newspaper, with his back to the experimental area. It was against procedure for persons to work alone on critical materials.

      Harry removed the Plutonium core from the vault and began to assemble his apparatus. The core weighed about 6.2 Kg, and it had been enhanced by processing to the enrichment needed for weapons use. This processing had eliminated other isotopes of Plutonium such as Pu 240, which would contaminate the fission process. This sphere was now very highly enriched in the 239 isotope, and was thus capable of thermal neutron fission. This material was of a high enough purity to be classified as “Weapons Grade”, meaning it would sustain a chain reaction, and could be directly used as the core material for an atomic weapon. Under the right conditions, this core could produce a nuclear detonation.

      Harry had been working since the early winter in the drafty makeshift wooden structure, all throughout the snows and finally into the warm summer, each day meticulously filling a hand written notebook with data. He was building a stack of Tungsten Carbide (symbol WC) to surround the metal 49 sphere. Tungsten Carbide had the ability to reflect neutrons back into the core and that would increase the fission rate inside the material. It was called “increasing the criticality” of the assembly. That afternoon in an earlier experiment, he had found the rig went critical after a stack of five layers of WC bricks. Now he was determined to make the stack into a smaller and tighter arrangement, and re-run the test.

      The rig was surrounded with neutron detectors, and gamma counters, measuring released alpha particles, neutrons and gamma radiation flux. Like any good scientist, as each layer of bricks was stacked, the neutron flux and gamma radiation would increase, whereupon, oblivious to any danger, he would dutifully record the new data. Then the reaction would slowly die as the new assembly reached equilibrium. 

       As the stack grew, the Geiger Counters filled the room with audible clicks, which rose to a buzz as the rig approached dangerous levels. Neutron counters were silent, and registered their particles by a flashing light. Harry relied on both of these signals to judge the status of the experiment. Slowly he stacked the heavy bricks around the bomb core. He had completed the fifth layer of bricks when he attempted to add an additional brick to the stack with his left hand. As he lowered the brick toward the core, the detector buzzing and flashing shifted into high gear, alerting the room to approaching Supercriticality. Harry jerked his hand back but the 4.4 Kg heavy brick slipped from his grasp and landed on the top of the 49 sphere.

      This instantly caused a supercritical chain reaction. This was not an atomic explosion, but there was an immediate release of large amounts of energy. Neutrons, gamma rays, other particles and visible light flooded into the air in a huge flash burst. The light was so intense it passed through the wooden walls and lighted the newspaper the guard was reading some distance across the room. Private Hemmerly became the first man in history to actually see a criticality and live to tell the story. He described it as a brilliant blue flash in the air. The blue light was probably Cerenkov Radiation, characteristic of neutron fission.

      Realizing the terrible danger, instinctively Harry grabbed the brick with his right hand and pushed it away. He later described a tingling sensation in his hand as it entered the blue glow surrounding the spherical core. Hemmerly turned from his newspaper to see Harry standing near the core, hands at his side in embarrassment at what he had caused. Standing beside the critical core, Harry received a huge dose of radiation, higher than any man had ever received before. It was later estimated the radiation dose rate at this moment was 10 to the eight roentgen per second near the rig. A mere 600 roentgen absorbed dose is sufficient to kill more than half of those irradiated at that dose.

        Harry explained to Hemmerly what had happened in the accident and haltingly disassembled the rig. A graduate student had just arrived at the site, and she drove Harry to the Los Alamos Hospital. He was given immediate blood transfusions and fluids, and later awakened enough to be coherent and talk to his care givers. All knew he was dying. Hemmerly stayed behind to alert his Sergeant to the accident.

      Sadly, a scientific opportunity presented itself in this most bizarre situation. This was the first casualty in peacetime history to receive a lethal dose of radiation, and the effect of this much radiation on the human body was completely unknown. So for the next days while Harry slowly deteriorated, he methodically related the effects on his body to medical personnel observing his condition. His thoughts, physical symptoms, blood work, gastrointestinal symptoms, radiation burn trauma as a function of time after exposure, were all rigorously documented for the first time in the annals of medicine. This physical distress is now known as the “Acute Radiation Syndrome”.

      This Health Physics criticality accident was later assigned the designation of “LA-1” (for “Los Alamos event one”). Private Hemmerly survived relatively well but was to die 33 years later of blood cancer.

      Neutron radiation has the capability of making other inert materials themselves radioactive. Now Daghlian’s body was neutron activated, and was now emitting gamma radiation and was dangerous to be near. He lived for twenty one days before his body surrendered. He had tickled the tiger’s tail, and was laid to rest in a lead lined casket. The Plutonium core he used was named “The Demon Core”, and was later to cause further death. He died a casualty of World War II who never went near a battlefield; perhaps the first known peacetime victim of the Nuclear Age.

(to be continued)

 

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6 Responses to “Los Alamos Incident One (LA-1)”

  1. Robert Trippett Says:

    Robert Hemmerly is my grandfather and it is good to see that he lives on beyond just memories. As I recall he passed away at Riverside Hospital in Columbus OH in 1978 due to Leukemia. I remember verry well his battles with the cancer that killed him. To bad Dr. Daghlian had had a couple of drinks at his dinner performance that night before he went back in at 9:30. I often wonder if things would have been different if he would have just gone back to his home instead of being the dedicated worker he was. Either way they both made the ultimate sacrifice for thier country and science. Peace.

  2. Billy Williams Says:

    Being an avid student of WWII and associated events much of my life, I am familiar with the incidents involving Daghlian and Dr. Slotin, and with the people who were with them at the time. There is little doubt that Private Hemmerly did lose his life as the result of that accident, even though he passed away years later.I will hit the age of 62 in several days, and am looking forward to several more years of life; I think of his loss from that perspective.

    • Charles Glassmire Says:

      Thank you for your interesting reply to the incident. Your perspective is helpful. I am pushing 72 and am still kicking. Hope you have lots more to come.

      Keep reading!

      Charles Glassmire Tales from the Nuclear Age

  3. Lynn Birch Says:

    I am the daughter of Robert Hemmerly. Yes, it seems Dad gave his life to the service of his country, and I am extremely proud of his contribution to the field of nuclear science. Starting in 1960 and then every 5 years after that, Dr. Hempleman (I think this is the correct spelling of his name – he had been the medical doctor at the site) ran a series of tests on Dad. From these tests, he was able to document the effects of radiation on the human body over a period of time. Because of his work and the work of others much more is now known about radiation and how to protect humans who are exposed to it.
    When I was young, nothing was said at home about the incident, but in 1960 when dad had to go to Rochester, NY to have the tests run, he then talked a little bit about it – explaining the necessity of the trip. On his death bed in 1978 though, he told me about the blue flash, and helping Dr. Daghlian out of the lab. He also told me that he was kept in the infirmary for 2 days where he received a shot every hour on the hour, and then was kept off work detail for a couple of months. During this time he received a shot every day. He didn’t know what the shot was, or I have forgotten what he told me – either way I have no idea what it was.
    I am the first live born child Dad fathered after the incident. I was born in 1948. Mom miscarried a child the year before I was born. I have a younger sister and younger brother too. I am truly glad that Dad was given the chance to finish raising his family, a chance that
    that Harry Daghlian never had.
    Here’s to two great Americans – truly unsung heros of WWII.

    • Charles Glassmire Says:

      Dear Lynn;

      You should be very proud of your father and his noble gift to all of us who went after him. This is one of the more tragic incidents of a heinous war which involved the whole world and in which millions perished. Your father is a great man and a real hero. I hope I did his memory some justice in recalling this terrible incident.

      I wish you and your family all the best in good health and prosperous future!

      Charles Glassmire Tales from the Nuclear Age

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