A True Measure of Exposure

The Cecil Kelley Accident The origin of the Los Alamos Human Tissue Analysis Program

n December 30, 1958, an acci- two operators led Kelley to a shower. surrounded by hot water bottles. His dent occurred in the Los Alam- One operator turned the stirrer off as blood pressure and pulse were at first Oos -processing facili- they went by. unobtainable. He had shaking chills, ty, where plutonium was chemically and the uncontroled movement of his separated, or “recovered,” from various Within five or ten minutes, a nurse, su- extremities and torso necessitated re- compounds. In this facility, plutonium pervisors, and radiation monitoring staff straint by the nursing staff. Kelley’s compounds were dissolved and mixed were all on the scene. Kelley was evi- anxiety and restlessness were eased only in a large tank with chemical reagents dently in shock and virtually uncon- by Demerol. After about ten minutes, to concentrate and purify the plutonium. scious, but rather innocently, the nurse the nurses were able to measure Kel- On the day of the accident, Cecil Kel- noted that Kelley had “a nice pink ley’s pulse (160 beats per minute) and ley, an experienced chemical operator, skin.” Because the nature of the acci- his blood pressure (80/40). His body was working with the large mixing tank. dent was unknown at the time, it was emitted a small but measureable amount The solution in the tank was supposed not understood until later that Kelley’s of gamma rays, and his vomit and feces to be “lean,” typically less than 0.1 pink skin was erythema (a redness of were sufficiently radioactive to give a grams of plutonium per liter, but the the skin, like that from a sunburn) positive reading on the detector. concentration on that day was actually caused by his radiation exposure. 200 times higher. In fact, the tank con- One hour and forty minutes after the ac- tained enough plutonium (3.27 kilo- The possibility of a cident, Kelley entered the third stage, grams) in an upper layer of organic sol- had been considered so remote that the which was both the longest and most vent to be very close to criticality—that radiation monitoring staff began their encouraging. Kelley regained coher- is, capable of sustaining a chain reac- investigation by searching for plutonium ence, and although he complained of se- tion. When Kelley switched on the stir- in the work environment with alpha de- vere abdominal cramps and occasionally rer, the liquid in the tank formed a vor- tectors. They found no widespread ac- retched and vomited, he seemed consid- tex, or whirlpool. The lower, aqueous tivity. It was only as Kelley was leav- erably improved overall. He was trans- layer was pushed outward and up the ing in an ambulance, eighteen ferred from the emergency room to a walls of the tank, as if forming a bowl; minutes after the accident, that the cir- private room, placed in a bed that was the upper, plutonium-containing layer cumstances of his accident became on “shock blocks,” and enclosed in an flowed into the center of this “bowl,” clear. The monitoring staff had just oxygen tent. Kelley’s first blood sam- which increased the thickness of the begun gamma radiation measurements. ples were drawn at this time. Because layer. In this new configuration, the When they saw the high level of gamma Kelley had been irradiated with neu- plutonium went critical, releasing a radiation in the vicinity of the large trons, the and other light metals huge burst of and gamma radi- mixing tank (tens of per hour), the in his blood were “activated,” or trans- ation in a pulse that lasted a mere 200 investigators quickly realized what had formed into radioisotopes such as sodi- microseconds. happened. um-24. His average whole-body dose was first estimated by measuring the ra- Kelley, who had been standing on a foot The symptoms Kelley displayed at the dioactivity of his blood. It appeared to ladder peering into the tank through a plutonium-processing facility, character- have been massive—in the range of 900 viewing window, fell or was knocked to ized by collapse and mental incapacita- rad from fast neutrons and 2,700 rad the floor. Confused and disoriented, he tion, were the first stage of his clinical from gamma rays, giving a total of apparently turned the stirrer off and on course (what is now know as the most 3,600 rad—and certainly lethal.1 again, then ran out of the building. The severe form of acute radiation syn- two other operators on duty at the time drome). The second stage began when Six hours after the accident, the lym- saw a bright flash of light, like that of a he arrived in the emergency room of the phocytes virtually disappeared from flash bulb, and heard a dull thud. Los Alamos Medical Center. It was Kelley’s peripheral circulation, which Quickly, they rushed to help, and found dire. Kelley was semiconscious, retch- 1 After his death, Kelley’s radiation dose was bet- Kelley outdoors. He was ataxic (lack- ing, vomiting, and hyperventilating. His ter estimated, again using biological indicators of ing muscular coordination). All he skin was cold and dusky reddish-violet, the dose and inferring the gamma dose. could say to the operators was, “I’m and his lips had a bluish color that indi- The results were somewhat greater than the esti- mate made during Kelley’s period at the hospital: burning up! I’m burning up!” Assum- cated poorly oxygenated blood. He was 900 rad from fast neutrons and 3,000 to 4,000 rad ing he’d had a chemical accident, the immediately wrapped in blankets and from gamma rays, giving 3,900 to 4,900 rad.

250 Los Alamos Science Number 23 1995 A True Measure of Exposure

The origin of the Los Alamos Human Tissue Analysis Program was taken as a grave sign. Twenty-four Kelley’s exposure record included 18 termine relative timescales for the move- hours after the accident, a sternal bone instances of high nose-swipe counts and ment of plutonium through the body and marrow biopsy was performed. The 10 instances of minor exposures, such within organs. This was possible be- marrow appeared watery, rather than as being involved in the cleanup of a cause changes in plutonium production bloody, and no excessive bleeding oc- plutonium spill or getting a slight lacer- methods between Kelley’s first and sec- curred. The marrow was almost com- ation. Urine assays taken during that ond stints as a plutonium worker had pletely acellular, edematous, hemorrhag- period usually showed slight amounts of considerably increased the ratio of pluto- ic fatty tissue. From that observation, plutonium. Analysis of those assays in- nium-238 to plutonium-239 in the mater- along with the rapid onset of lymphope- dicated that Kelley’s plutonium body ial being handled. This fact, coupled nia (depression of the lymphocytes in burden was 19 nanocuries (see “The with the record of nose counts and expo- the bloodstream overall), it was clear Human Plutonium Injection Experi- sures, enabled them to distinguish the that Kelley would not survive long. ments”). Kelley’s records showed that “early” plutonium from the “late” pluto- all of his exposures occurred during his nium and, thus, to trace qualitatively the During the second evening after the ac- early plutonium work (1946-1949) and movement of plutonium from the lungs cident, Kelley entered the fourth stage. it was very likely that most of his pluto- to other organs. They found that pluto- The pain in his abdomen became diffi- nium burden was accumulated during nium cleared relatively rapidly from the cult to control. He became increasingly this period from chronic inhalation ex- lungs compared with the clearance from restless despite medication—so much so posure to low-level airborne plutonium. the bone and lymph nodes. Much of the that the intravenous infusions were inad- plutonium in the lungs migrated to the vertantly interrupted. He began to Autopsy samples were taken from liver whereas only a small percentage sweat profusely, his color became throughout Kelley’s body to measure migrated to the bone and lymph nodes. ashen, and his pulse irregular. About plutonium concentrations. (The acci- Finally, the rate of clearance from the 35 hours after the accident, Kelley died. dent itself, an exposure to neutrons and lungs to the liver must be relatively fast gamma rays, had no impact on the and the retention time in the liver must Kelley had spent about half of his 11.5 amount or distribution of plutonium in be longer than in the lungs. years at Los Alamos as a plutonium- his body.) The tissue analysis showed processing operator (from 1946 to 1949 that Kelley’s total plutonium body bur- A memorandum written by Jean Mc- and, again, from 1955 through 1958). den was 18 nanocuries. This compared Clelland and Bill Moss, chemists in the During that time, he underwent several extremely well with the value of 19 Health Division, presented the results of minor exposures to plutonium, including nanocuries determined from urinalysis. Kelley’s tissue analysis. Those results regular exposure to moderate levels of Wright Langham stated that the above showed that plutonium was retained in airborne plutonium in various chemical agreement “was so very satisfactory that the lungs and pulmonary lymph nodes forms. Therefore, his tragic death be- it is undoubtedly fortuitous.” In addi- much, much longer than contemporary came an opportunity to determine cer- tion, it was found that about 50 per cent models had predicted. Because this was tain factors crucial to the protection of of the plutonium was in the liver, 36 per unexpected, it was decided to collect tis- workers. By analyzing the tissues of his cent in the skeleton, 10 per cent in the sues from other exposed individuals to body, researchers could determine Kel- lungs, and 3 per cent in the respiratory confirm this phenomenon. They also ley’s total plutonium body burden and lymph nodes. Plutonium Injection Ex- stated that tissues from non-occupation- compare it with the result obtained from periments in humans had shown a ally exposed individuals would be col- periodic urine assays during his life. somewhat different distribution: 65 per lected as controls. Thus, the Los Alam- Furthermore, they could determine the cent in the skeleton and 22 per cent in os tissue analysis program was begun. ■ distribution of the plutonium in Kelley’s the liver, for example, most likely the body. Because certain tissues are more result of differences in the chemical and sensitive to radioactivity than others, the physical nature of the plutonium (the Further Readings distribution of the plutonium was im- experiments used a soluble salt of pluto- portant in determining the effective nium whereas Kelley inhaled plutonium T. L. Shipman, C. C. Lushbaugh, D. F. Petersen, dose. That result could be applied dust particles). W. H. Langham, P. S. Harris, and J. N. P. Lawrence. 1961. Acute radiation death resulting broadly to other individuals who were from an accidental nuclear critical excursion. exposed to plutonium largely by inhala- Another interesting factor in Kelley’s Journal of Occupational Medicine: Special Sup- tion over a prolonged period. analysis was that they were able to de- plement. (March 1961): 145-192.

Number 23 1995 Los Alamos Science 251