First Results from the Programme of Action Following the Palomares Accident

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FIRST RESULTS FPOM THE PROGRAMME OF ACTION FOLLOWING THE PALOMARES ACCIDENT. Junta de Energla Nuclear - Madrid - Spain. US DOE ARCHIVES SYMPOSIUM ON RADIOLOGICAL PROTECTION OF THE PUBLIC IN A NUCLEAR MASS DISASTER itgliedagesellschaft der International Radiation Protection Interlaken 26 May - 1 June 1968

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FIRST RESULTS FROK! THE PROGRAMME OF ACTION FOLLOWING THE PALOMARES ACCIDENT ■we would like to give an idea of the work which is being carried out in connection with the wellknown Palomares accident, and give indica tions of some of the general results obtained, with the idea that in the Symposium on nuclear accidents which is to be held in Madrid next year, organised jointly by the I.A.E.A., F.A.O., and W.H.O., we shall present more detailed studies on each of the sections we shall briefly refer to here. BEST AVAILABLE COPY As a consequence of the air crash which caused, on the 17th Janua ry 1966, the explosion of part of the conventional explosive, which was a constituent,of two thermonuclear bombs, an aerosol of plutonium and uranium was created which caused the contamination of a total area of approximately 226 hectares, of which 2.2 hectares had en alfa contamination of more than 700,000 d.pm./tOO cm , being the areas closest to the . points of impact of ihe two bombs, which were 2,600 m. apart in a line drawn through the air. An area of approximately 17 hectares showed contamination between 700,000 and 70,000 d.p.m./lOO cm , and the rest, some 207 hectares, showed contaminations of less than 70,000 d.p.m./lOO cm , rather more A great proportion of the houses of the town were either well out of the contaminated area, or in the parts where contamination levels were lowest. The number of persons who were in the town at the time of the accident was approximately 1,000 - 1,200.

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In another communication presented to this Symposium, it has been ex plained how the limits oi the said zones were fixed, the decontamination operations carried out, and steps taken with people and vegetation at a time soon after the accident. Here we are going to deal with, although in a somewhat summarised form, the work plan devised for the vigilan ce of the people and the area, and the deduction of the consequences which might, in the future, result from such an accident and the measu res which were taken. Our greatest worry, as is logical, was to determine whether or not there was internal contamination by plutonium-239 of the persons present in the area during the moments following the accident, what possibilities there were of contamination during the period of time when the operations of limit-fixing and decontamination were being carried out, and whether there was any risk from the measures which it had been decided would be taken in the areas where contamination levels were lower than 700,000 BEST AVAILABLE COPY This risk might be dexived from: a) inhalation of plutonium if, as a consequence of the tilling of the land, and the winds which eic present, an aerosol, contaminated with the said element, }«> ’ ci eated, which reach a definite diffusion. b) contamination as a concequence of tilling operations on ground where a certain quantity of plutontum-239 was left. c) contamination by contact with or ingestion of vegetable products which are cultivated in the area, in the case of these showing external contamid) contamination of vegetable products used as foodstuffs in the case of their producing, during their growth, an absorption of plutonium-239 or

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We make ihe reservation that there is no risk of contamination through drinking water, since the water existing in the said area has such a high concentration of salts that it is completely undrinkable, and ihe drin king water which the public consumes is brought from a distance of 50 As a consequence of these considerations, we summarise below the deductions obtained during the first year of work in connection with the contamination of persons, ground,air and. vegetation. CONTAMINATION IN PERSONS The study of the determination of possible internal contamination of the people of Palomares, both in the case of those who went there afterwards, and especially those who walked through contaminated areas during the first moments, was planned under the following two aspects: 1) Determination of the Plutonium-239 excreted in urine, in orden to de termine the fraction which could have passed the pulmonary and lymphauc limit. BEST AVAILABLE COPY 2) Determination of the quantity of plutonium-239 present in the lungs. To obtain this information, after the analysis of plutonium-239 and total alfa activity in urine had been carried out soon after the accident, on the persons who at that time were considered those most likely to have been internally contaminated, a selection was made from the people of Paloma res, with respect to the following considerations: t>0E 'ARCHIVES* 1) Situation nearest to the points of impact of the fractional bombs, and the areas of greatest contamination at the moment when the accident occu rred, therefore with the greatest possibilities of inhaling the aerosol crea ted in the conventional explosions. 2) Stay in sones of highest contamination during the day of the accident

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3) Residence, at the time of the accident and the days following it, in houses and areas of the town vdiere a higher contamination had been found, within the lower limits where contamination was produced in the town, as may be seen from the plan of the contaminated area. 4) Situation during the accident and following it, in houses and areas of the town v&ere contamination was nil, so that they could serve as controls, and at the same time we could find out with certainty whether a mistake had been made in not considering evacuation of the people of that area as necessary in the operations of contamination limit fixing and decontamination. Taking the above factors into account, a total number of 100 persons were selected, of which 49 were males over 14 years of age, 32 were females over 14 years of age, 10 were males under 14 years, and 9 were fema les under 14 years. BEST AVAILABLE COPY They were taken to Madrid for the said tests to be carried out in the la boratories of the Dlvisidn de hiedicina y Proteccidn de la Junta de Energfa Nuclear. They first underwent a complete medical examination, in order to find out their state of health and take it into account in the study and subsequent epidemiological control. In order to determine the concentration of plutonium-239 excreted in urine, three complete 24-hour samples of urine were taken from each one of the said persons, on three consecutive days. These samples were submitted to a chemical treatment in order to determine the content of the said ele ment, by alfa spectrometry, on the final electrodeposit following a separa tion by ion exchange resins. DOE ARCHIVE? The result of this analysis showed that in 71 per cent of cases there was no indication of the existence of plutonium-239, 18 per cent showed, in so‘^, me analyses, contents of less than 0.1 disintegrations per minute in the urine of 24 hours, 9 per cent showed contents of between 0.2 and 0.1______

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disintegrations per minute over 24 hours, and finally, 2 per cent showed a content of between 0.2 and 1 d.p.m. in the urine of 24 hours. Bearing in mind .what these values represent on the alfa spectrum corres ponding to the 1000-minute measurements taken, we have taken a delibe rately pessimistic view, although in almost all cases they could be consi-. In order to determine the pulmonary content of plutonium-239, measure ments were taken on all ihe previously-mentioned persons, with propor tional pulmonary counters, considering the region between 10 KeV-28 KeV, where the XL rays of uranium are found of 13.6, 17.4 and 20.2 KeV in an abundance of 4% per disintegration. These counters consist of two gas flow proportional chambers, with a capacity of 14 litres and a sensitive~?^etection surface of 17.4 x 30.1 cm each, whch work with a mixture of argon (90%) and methane (10%) and which have been designed in the "Los Alamos National Laboratory"by Mr.P. Dean. The calibra tion of the said chambers was effected with a point source of plutonium239, and two sheets of metyl metacrylate 2.54 cm thick to simulate the the -ho"* BEST AVAILABLE COPY Taking into account the background of the chambers, the counting time and their efficiency, it was found that the minimum detectable value of plUtonium-239 was 40 x 10 Ci. In the test made under these conditions, all the values obtained were on the order of background, which indicates that the amount of plutonium-239 which might be found in the lungs, if any, would be less than 40 nanocuries, a value which is quite encouraging, as the maximum permissible pulmonary burden is 16 nanocuries. DOE ARCHIVES A certain modification was made in the chambers which permitted the lowest value detectable to' be reduced to 16 x 10 Ci. The measurements taken under these conditions with some of that people showed that in no

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case did ihe values obtained exceed this figure. CONTAMINATION OF THE GROUND As has already been mentioned, the contamination of the ground surface was not homogeneous. In order to determine the degree of distribution, and what this distribution was on the surface, as well as its depth, after ihe operations of decontamination, and those planned to eliminate surface contamination in areas required, a study has been planned in order to find out which these are. We hope that it will permit us, as years go by, to discover the dynamics of plutonium-239 in cultivated land, both as re gards its dinamics parameters, and those introduced by tilling and cultivauon method.. BEST AVAILABLE COPY For this purpose, six areas have been chosen of 50 m each, two from each of the 3 zones into which the total contaminated area was divided, . corresponding to the two areas where the bombs fell and broke into frag ments, and the intermediate zone where the town is situated. These areas were chosen in places which had remained most contaminated after the removal of a layer of earth on the areas which had contaminations higher than 700,000 d.p.m./lOO cm . Those in zones 2 and 3 comprise areas where total alfa contaminations were found to be between 700,000 d.p.m./ 100 cm ; area 2-1 belongs to a part where the upper layer of earth was also removed during decontamination operations. The areas in zone 5 shoIn order to find the average background of total alfa activity on the ground of the zone, two similar areas ha\e been chosen, with similar geological characteristics and situated at 1,000 m. and 7,000 respectively from the . DOE ARCHIVESzero line of the contaminated zone. In each of the areas, and in accordance with its diagonals, during the first year, .1966, nine samples were taken which were divided into frag- 57 ments, corresponding to depths of 0-5, 5-15, 15-25,25-35 and 35-45 cm.

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Of the homogenised samples corresponding to each fragment, two fractions of 0.50 gm. were taken, which were submitted to chemical treatment and alfa counting, in order to determine the total alfa activity. At present we are continuing to do this, and in successive years samples will continue to be taken at points in the same areas and following a pre planned distribution order in order to obtain complete knowledge of the dy namics of the contamination, as well as to deduce the contamination factors of the vegetable products which are cultivated in them. In 1967 the number of samples taken was higher, with a factor of two, than that of the pre With these Iasi samples, the tests have been not only to measure the total alfa activity, and consecuently, through its relationship with the values ob tained in the background sampling places, and the high specific activity of plutonium-239, deduce what amount is due to the said plutonium-239. Besides radiochemical separations are being carried out for each of the The alfa activity of the soil in the region of Palomares (Almeria) is one of the highest in Spain, as has been shown in the comparison of results obtained from the background areas, situated far enough away to be cer tain that they were not contaminated, and those from other provinces and types of soil, as may be seen from Table I. In order to give you an idea of the results we ere obtaining, in Table II may be seen the average values of alfa activity from the samples taken in 1966 from each one of the zones, and iu relation to depth. From these values it may easily be deduced that: 1) In zone 2-1, where a 5 cm layer of soil was removed, the remaining contamination is nil.. BEST AVAILABLE COPY D0E chives 2) As a result of ploughing and breaking up of the ground, a distribution of contaminating elements have been obtained to a depth of 30 cm. Genera-

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lly highest conlamination levels are found in layers between 15 and 25 cm 3) The maximum average value of alfa activity found in the areas studied is approximately 50 times higher than the minimum value oi natural alfa ac tivity found in the background soil of the zone, which in turn is two times higher than the minimums found in the aieas studied. The unhomogeneous distribution of the contaminating particles, even after the ploughing operations carried out in order to dilute the radioactive ele ments, plutonium and uranium, on a layer 30-35 cm deep, is perfectly clear from the values obtained, as might logically" have been expected. Even results from different samples from the same point and fragment, after the greatest homogenisation possible in the laboratory, show quite a considera ble dispersion, as may' be seen from Table 111. On this table may be seen the values from all the analyses corresponding to each one of the fractions of ground which gave the highest alfa activity values, in area 2-2, one of those of greatest contamination. BEST AVAILABLE COPY Considering that the alfa activity levels higher than the natural background are due to contamination by particles of plutonium oxide, and bearing in mind that the specific activity' of plutonium—239 is such that 1 microgram of the same is equal to 0.064 microcuries, it may be deduced that the contaminating particles, taken as being of spherical shape, have diameter-s of between 0.01 and 0.1 micron, as a spherical particle of 0.1 micron diameter would be the equivalent to 11,716 disintegrations per minute. CONTAMINATION OF THE AIR doe archives A network of aerosoles sampling has been set up in order to discover what possibilities there might be of internal contamination of the people who live in the zone and cultivate the fields, as an isolated or related consequen ce of the ploughing operations on the ground and the climatological characte-^

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This netwoik coii"i.-ts oi four sair.pling stations, and two for the study of the …