Dr. AEBERSOLD. In the Army's program they are interested in storing without refrigeration, and so they give doses of, say, 5 million rads. That is a very large dose.

In our program we are trying to give a minimal dose, around 100,000 to 500,000 rads, which is at least 10 times smaller.

Therefore the type of changes that take place in the food in our programs are very minimal. For example, in the case of fruits, which we have studied, there is not any decrease in vitamin C. You were mentioning oranges. I think the freezing perhaps changes the vitamin content. It may be at that point that the people were questioning the vitamin wholesomeness of frozen oranges, but I am not an expert in that area.

In the case of radiation of citrus fruits we know that vitamin C is not destroved. Neither is it in strawberries. We have also found some very interesting things about radiation of things like pears and peaches. We can delay ripening 3 to 4 weeks which is very important in terms of canning. When all of the products ripen at the same time there is a problem of canning. We can delay ripening and hold some of these products longer.

I think for the amount of money that we are putting into the isotope program we are getting very good results. We have several advisory committees, and a number of people who are extremely interested in this program-such as Dr. Libby-and they feel that a great deal more could be advantageously invested in the isotope program as a practical application of atomic energy outside of the field of power.

COMMERCIAL PRODUCTION OF RADIOISOTOPES

Mr. EVINS, Doctor, one of the trade papers states that major isotope sales campaigns have been opened by General Electric and Union Carbide, serving notice that they will compete with AEC to provide to industry an increasing variety of radioisotopes. Why can't this program be cut back if industry is ready to meet the needs?

Dr. AEBERSOLD. In this budget we do not budget for isotope production. That program has been self-sustaining for many years. The sale of isotopes covers the production costs.

Now, if industry were to take over certain portions of this it would cause us a problem. Industry is interested in those items that are making profit, for example, radioactive iodine, and radioactive cobalt. If they take over those items then we will be operating at an overall loss because of the almost 100 other isotopes which we distribute from Oak Ridge at a loss. We will then have to raise the price, and people who use them for research will have to pay considerably more for them.

Our objectives in the Isotope Division going back 15 or 16 years, has been to encourage private production of isotopes. But first we had to encourage the secordarv distribution. That is we at Oak Ridge acted as wholesaler. We ship out large quantities of radioactive materials to pharmaceutical companies and to secondary nuclear companies, who then process, package, and redistribute the material in small quantities to meet customer needs. The secondary distribution of isotopes has become a very profitable business and has built up to somewhere in the range of $30 million a year for all of the isotope

related business in the United States including equipment and isotope label compound.

Now, General Electric is talking about making isotopes in their own reactors. We encouraged them. However, it is the only private reactor in the country that could make sizable quantities of cobalt, and yet it cannot meet the whole Nation's needs at the present time. A major source of this isotope for the United States is Canada. Mr. EVINS. When private industry goes into this field they are going also into research for commercial purposes, are they not; that is generally to be expected?

Dr. AEBERSOLD. Well, the research program budgeted here is not the type of thing that industry does. If they were doing it we wouldn't be doing it, and we certainly don't want to expend Government money for activities which industry can handle satisfactorily.

A lot of our R. & D. is with other Government agencies to help solve puzzling problems in the area of public benefit.

ISOTOPIC POWER AND HEAT-SOURCE DEVELOPMENT

Mr. EVINS. I was going to ask you about the next one.
Dr. AEBERSOLD. Yes, sir.

Mr. EVINS. This is about double the program in 1964.

Dr. AEBERSOLD. You can look down the list and can see why we have the increase. We are working on quite a few new isotopes. I think one of the most useful isotopes for the future will be curium 242. This was discovered by Chairman Seaborg many years ago, and it was a curiosity until recently. Now we believe we can make fairly large quantities of this istotope. It gives out 140 watts per gram, which is one of the hottest materials thermally that we know. As a matter of fact, we have to dilute it to use it for our space purposes. We are also going to make curium 244. The increase is absolutely essential if we are to meet the demands for power sources for space.

Now, the next item

Mr. EVINS. Is any of this being used after your discovery in the space program?

Dr. AEBERSOLD. If I can just go down a minute

Mr. EVINS. We are asking about this one for the minute, and why is it double?

Dr. AEBERSOLD. Because it is an entirely new isotope and no one has ever produced it in quantity before. We are doing a job that is comparable to the first production of plutonium 20 years ago. To make curium 242 we have to bombard americium, which is a unique item for which we have to pay the costs, extract the fission products and the curium, and reclaim the americium. To do this on a gram quantity with $890,000 is really a very economical production of curium.

Mr. EVINS. I think that I am going to defer to my colleague, Mr. Jensen, at this point.

Mr. JENSEN. All I wanted the doctor to do is this: We put great emphasis on the radioisotopes, which, of course, are very important. I just, as an ordinary common layman, have a pretty good idea of what a radioactive isotope is, after being on this committee for a number of years.

22-502 0-63-pt. 6—23

RADIOISOTOPES

But, for the record, will you explain in as short language as possible, or as short a statement as possible, in layman's language, how an isotope is produced, a radioisotope, and whether or not it comes in liquid or solid form to be useful and the numerous places where radioactive isotopes are used.

Now, I am afraid that would be a list longer than your arm, but just for the record give that.

I am sure that there are a lot of people reading this hearing, and have heard about radioisotopes, and they are wondering just what is a radioactive isotope.

Will you do that? You can do it for the record.

Dr. ÅEBERSOLD. I just have published an article for the American Radium Society which concerns itself with isotope production and radioisotopes source fabrication. It lists all of the important isotopes and the ones that we produced at Oak Ridge. The quantities that Oak Ridge has produced are phenomenal, running into millions of curies. When we were in the old cyclotron days we could get a microcurie and we thought that was something wonderful. Now we are making millions of curies, which is 1 million million times greater than we had available before the reactor days. But we do still make cyclotron isotopes.

We get isotopes from fission of uranium. When uranium fissions, some of the isotopes last for one-millionth of a second, and others, like strontium 90, for the order of 30 years.

Now, one simple way of making isotopes, or radioisotopes, is to put them into the reactor and bombard them with neutrons. What it amounts to is that you are putting nuclear energy into stable atoms. You can have stable atoms of cobalt or iron or nickel and gold.

Mr. JENSEN. Can they be liquid or solid?

Dr. AEBERSOLD. Yes, but generally we put them in solid form. We generally use metal. We can take any ordinary metal around here a copper penny or iron or any substance and put it in the reactor and it becomes radioactive. What you have done is pump a little nuclear energy in it. It is very interesting for cobalt, radioactive cobalt, into a little wafer about the size of a centimeter, a millimeter thick, we can put several thousand curies of strength. That energy will be treating cancer patients for the next 5 years before it comes down to half strength.

Mr. JENSEN. What is the weight of that wafer?

Dr. AEBERSOLD. The weight of the wafer could be 10 or 15 grams. We change only a fraction of the atoms or nuclei from stable cobalt 59, which is in its natural state.

Mr. JENSEN. How do you ship it?

Dr. AEBERSOLD. We make it into radioactive cobalt 60. The increase in weight is not significant, but the amount of nuclear energy put into it is very great.

Isotopes are shipped in lead containers if they give out penetrating radiation. If not, they can be shipped in very simple things. I have here I always carry a source with me because I wouldn't be caught without a radioisotope-some of the element americium. This ele

ment was discovered by Dr. Seaborg. I have here a little Geiger counter and you see there is nothing happening. I will turn it over to switch it on. It wasn't turned on because it would make too much noise around the room when other things are going on.

Now, the source gives off 70,000-volt X-rays, which I can shield like this, and carry around with me. Now there is no significant quantity of radiation coming out. This is exactly the same kind of radiation that we use for taking pictures of hands. This radiation will go through quite a bit of human tissue.

For example, I can go through Dr. Haworth's chest.
Mr. JENSEN. What part is making the noise?

Dr. AEBERSOLD. This part here is making the noise. I thought you might be interested in it. This illustrates the problem of space power. The battery weighs more than the equipment and is why we have difficulty providing power for space-the batteries are too heavy. This little radiation detector has about 50 parts in it and was developed as a personal monitor to help protect people.

Isotopes come in different forms. We can shield them very simply in some cases but in other cases we have to have lead containers. Isotopes range all the way from element No. 1 to element No. 103. These isotopes are used in practically every field of research and in engineering applications.

Mr. EVINS. Can you tell us what other agencies are doing in this field?

Dr. AEBERSOLD. Practically every agency buys isotopes from us; or they buy them from a private supplier.

The total number of users of isotopes in the United States is well over 8,000 different institutions.

We have cooperative agreements with certain other agencies such as NASA, for which we develop isotopic power and demonstrate it. After we make a successful demonstration we expect them to begin to order these things as practical items. At the present time we only have a few isotopic power units that are in long-term use. We have two weather stations, one on the South Pole and one on the North Pole, that have been going for 2 years now without anybody there, giving us weather data every 3 hours. They use strontium 90 power. This is just from the heat of strontium 90. We have going around the earth now TRANSIT IV, that has plutonium 238 in it. As you noticed there is a little increase in the budget for plutonium 238, because the United States wants to put up more TRANSIT satellites.

CAPITAL EQUIPMENT NOT RELATED TO CONSTRUCTION

Mr. EVINS. You are a good salesman, and I want to ask why you are doubling your capital equipment budget for the next year.

Dr. AEBERSOLD. A large part of that is for the hot cell equipment needed for handling such things as cerium 144 and fission products that can be developed as very useful sources of power.

REPORT ON DEVELOPMENTS IN ISOTOPE PRODUCTION AND SOURCE

FABRICATION

Mr. EVINS. Your report may be included in the record.

(The record referred to is as follows:)

RECENT DEVELOPMENTS IN ISOTOPE PRODUCTION AND SOURCE FABRICATION*

TRE

By PAUL C. AEBERSOLD, PH.D.†

WASHINGTON, D. C.

REMENDOUS strides have taken place in the past decade in man's capacity to make radioactive atoms. The number of known kinds of man made radioactive atoms is now close to 1,000. Radium 226, the isotope of radium whose medical use generated this Society, is now just one of hundreds of useful radioactive species. The total activity of radioactive materials produced by nuclear chain reactions, both controlled and uncontrolled, staggers the imagination. The energies and beam intensities of nuclear particle accelerators have increased a thousandfold and more. Thus, man is now in the fortunate technical position of being able to develop production of any desired radioisotope in sufficient amount and purity to meet all demonstrated needs.

Physicians and medical research workers are already making good use of those isotopes that have become readily available.1 Of the potentially available radioisotopes, however, only a dozen or so are used routinely in diagnosis and therapy, and fewer than 100 in medical research. Progress in

radiation instrumentation, isotope scanning techniques, whole body counting, in vitro diagnosis and combined radiation-chemotherapy will assure more extensive uses of presently available radioactive materials. However, for significant advances we must continually seek new isotopic materials and new ways of applying known but little used isotopes.

Steady progress has been made in isotope production toward lower costs, higher specific activities (activity of the desired radioisotope per gram of the total element present), improved radiochemical purity, and greater availability of isotopes having unique half lives and radiation characteristics.

A gross indication of progress in the production, distribution and use of radioisotopes can be obtained from Table 1, A and B. This table lists the number of shipments and totals of the activity of major reactorproduced radioisotopes distributed for all purposes by Oak Ridge National Laboratory from the beginning of distribution through March 1, 1962. Much smaller

* Presented at the Forty-fourth Annual Meeting of the American Radium Society, New York City, April 2-4, 1962, † Director, Division of Isotopes Development, U. S. Atomic Energy Commission, Washington, D. C.