IAEA Nuclear Data Section, Vienna, Austria
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Nuclear and Atomic Data Program of the IAEA

What nuclear and atomic data are

The IAEA has a mandate to accelerate and enlarge the contribution of atomic energy to peace, health and prosperity throughout the world. Today nuclear based technologies are used in many industrial applications both in developing and developed countries. Nuclear and atomic data are required to implement these technologies.

Modern nuclear installations and nuclear instrumentation have reached a high degree of sophistication, their design and safe operation is only possible on the basis of accurate calculations using up-to-date nuclear constants, called nuclear and atomic data, as input. The amount of data needed for such calculations, can be enormous. For example, for the calculation of the physical behaviour of the core of a research reactor and its safe operation (Fig. 1) a collection of data for 130 nuclides with more than 10 000 numbers in it must be used. Another set of data of about the same size is used to calculate the radioactive inventory build up in the reactor and to develop an optimal waste management strategy for the spent fuel of such a reactor.

[Fig.1: Research reactor at BATAN, Indonesia]
Fig.1: Research reactor at BATAN, Indonesia

Even more detailed data are required to design a modern nuclear reactor for electricity production and to make decisions on the fuel cycle for today and for the near future. This design must conform with the strict safety regulations and still remain cost effective. The requirements for the quality and accuracy of data for this purpose are very high.

Another common example of application of nuclear techniques is radiation therapy of cancer patients. Only in the European Community countries there are more than 1 million new incident cases of cancer per year. About 18% of the patients are cured by radiotherapy. Different types of nuclear radiations, e.g. photons, electrons, neutrons and charged particles are used for this purpose. To minimize damage to surrounding normal tissues an accuracy of the dose delivery at the specified location should be better than 5%, Fig. 2. Again, comprehensive atomic, molecular and nuclear data are needed to determine the dose delivery with such precision.

[Fig.2: Cancer treatment with Cobalt-60 gamma rays]
Fig.2 Cancer treatment with Cobalt-60 gamma rays

Another important aspect is standardization of measurment techniques. The Nuclear Data Section maintains and updates several international standard data libraries. For example, in order to perform accurate measurements it is necessary to calibrate instruments. A specialist measuring environmental samples, performing activation analysis or other analytical measurements can immediately check the latest updates of standard data such as half-lives, energies of gamma rays etc., by logging on to the IAEA online database of X and gamma ray standards or by requesting the last version of data to be sent on diskette. This service is essential in supporting the high level of accuracy and consistency of measurements worldwide. These are only a few examples of the use of nuclear and atomic data. To satisfy the current demand in data the Nuclear Data Section of the IAEA maintains and permanently updates databases needed for such areas as

The databases, also called data libraries, should be comprehensive, complete, up-to-date and user friendly.

Generation of nuclear and atomic data

Nuclear and atomic data are produced from results of experimental measurements, nuclear physics model calculations and data evaluations.

The process of measuring atomic and nuclear data requires the use of modern research reactors, neutron generators, charged particle accelerators, spectrometers and other unique scientific devices, see for example Fig. 3.

Such measurements are very costly. Billions of US$ have been spent on construction and operation of these devices and on data measurements in the Member States. But still not all the required data can be measured. For example, data for short lived isotopes must be obtained by theoretical calculations and evaluations.

Nuclear model calculations and evaluations make use of considerable computer resources and the theoretical results obtained require experimental testing and verification.

[Fig.3: Electron linear accelerator, UK AEA for 
high resolution measurements of neutron nuclear data]
Fig.3 Electron linear accelerator, UK AEA for high resolution measurements of neutron nuclear data

Nuclear data are generated in many Member States in a wide variety of research institutions. No single Member State whether developing or developed has enough resources to perform the immense task of providing nuclear and atomic data for applications alone. Recognizing this situation the IAEA initiated a continuing program to collect, analyze, recommend and disseminate such data particularly to developing countries and established the Nuclear Data Section in 1964. It started by developing, in co-operation with established national nuclear data programs, a world-wide systematic collection and exchange of nuclear data, and built up over time the dissemination services to users in the Member States.

The process of nuclear and atomic data generation is cyclic in nature and includes feedback from users on the basis of what the necessary corrections, improvements and additions to the data files are made. This scheme is shown in Fig. 4 as an example for nuclear data. A similar arrangement exists for atomic data.

[Fig.4: Process of generation of the nuclear data

The feedback information from users on the nuclear data needs worldwide is compiled and published as the World Request List for Nuclear Data Measurements (WRENDA) by the IAEA. The last edition of this document, WRENDA 93/94, contains 720 of such requests, including 468 requests which were newly added. In many Member States WRENDA serves as a basis for justification of funding for further nuclear data research.

How the Nuclear and Atomic Data Programs operate

The program is implemented by the Nuclear and Atomic Data Center which, in line with the IAEA statutory function to foster the exchange of scientific and technical information, coordinates generation, collection and distribution of nuclear and atomic data. This is achieved through the establishment and operation of the worldwide International Atomic and Nuclear Data Centers Networks.

The objectives and tasks of these Networks are:

The structure of Atomic and Nuclear Data Networks is very similar. Therefore only the structure of Nuclear Data Center Network is shown below as an example.

This Network consists of four main service centers:

which provide full customer services in their respective geographical area, and include The schematic diagram showing the links between the Nuclear Reaction Data Centers and their customers is shown in Fig. 5.

[Fig.5: The Network of Nuclear Reaction Data 

The Nuclear Structure and Decay Data Network is shown schematically on Fig. 6.

[Fig.6: The Network around the Database of the Evaluated
Nuclear Structure and Decay Data File, ENSDF]

Nuclear and Atomic Data Collection of the IAEA

The IAEA Nuclear Data Center has the most comprehensive collection of nuclear and atomic data worldwide. This collection consists of the following major data bases The IAEA collection includes about 100 nuclear data and atomic data libraries. The most voluminous data library EXFOR contains more than 4 million experimentally measured data points from all over the world. In the period 1979/1990 about 9% of the data were measured in 32 developing countries. Although the boom of experimental nuclear data activities of 1970/1990 is over, there are still more than 1000 new neutron reaction data entries every year, plus hundreds of data entries in other nuclear and atomic data categories, which have to be compiled and made available to data users by means of updated databases.

In areas where the existing data files are not accurate or substantial data is missing, the Nuclear Data Section organizes Co-ordinated Research Programs, Advisory Group and Consultants' meetings to initiate new data mesurements and evaluations. The output of these coordination efforts are international standard data files and data handbooks for specific applications published as the IAEA TECDOC series, Technical Report series or INDC documents. Thus, the data collection maintained by the IAEA is not static but continues to evolve.

Duplication of effort by scientists in different countries is minimized through international cooperation implemented by the NDS/IAEA, thereby maximizing the use of specialized expertise in each of the cooperating Member States.

Services to Member States

The available nuclear and atomic data files and related documents are advertised to interested scientists in Member States through the IAEA Nuclear Data Newsletter and the Atomic and Molecular Data Bulletin. The Nuclear Data Section of the IAEA concentrates on services to developing countries, while the services to developed countries are done through their national data centers or the NEA Data Bank.

In the past years the Agency's Nuclear Data Center received about 800 requests per year from scientists in 93 Member States resulting in an annual shipment of about 300 data files on magnetic tapes and diskettes, 100 related data processing computer codes and 2000 copies of printed materials.

In addition to these conventional request services in 1992 the Agency's Nuclear Data Center started the online access service via Internet. The number of retrievals from the online service is rapidly growing and totaled 4000 in 1995 (see Fig. 7). The distribution of our services by geographical region is shown in Table 1.

The IAEA Atomic Data Center Network publishes an annual supplement to the journal "Nuclear Fusion" on the subject of atomic and plasma-material interaction data for fusion. 350 copies of this document are distributed each year to specialists in the world fusion community.

Bibliographic index of new atomic and molecular data generated in the Member States is compiled by the Section and published by the IAEA biannually in "Atomic and Molecular Data Bulletin". 850 copies of this Bulletin are distributed to specialists in the Member States twice a year.

[Fig.7: The online nuclear data service NDIS]

The Nuclear Data Section is also providing support to the International Thermonuclear Experimental Reactor (ITER) Engineering Design Activities, see Fig. 8, by supplying the required atomic, molecular and nuclear data and developing special data libraries.

[Fig.8:  Model of the fusion device - International Thermonuclear
                   Experimental Reactor (ITER)]
Fig.8: Model of the fusion device - International Thermonuclear Experimental Reactor (ITER)

In the future it is expected that the demand for the online services will grow fast and significant effort is being made to further widen and improve these services. In 1995 the Nuclear Data Section has put into operation an Alpha Server 2100 computer dedicated to nuclear databases and a RISC 6000 computer dedicated to atomic databases and online service.

The online database of the IAEA Nuclear and Atomic Data Center can be contacted on

   the Internet:                 online@IAEAND.IAEA.ORG
   or on the World Wide Web:     http://www-nds.iaea.org/

TABLE 1: Nuclear Data Services in 1990 - 1995 by Geographical Region
Services by mail Online Services
Region No.of countries Perc.of requests No.of countries Perc.of requests
OECD countries 22 24% 17 36%
Former USSR 6 7% 2 17%
East Europe 9 18% 8 40%
Asia, Australia 15 24% 6 1%
Africa and Near East 26 13% 2 3%
Latin America 15 14% 6 3%
TOTAL 93 100% 41 100%

Technology Transfer to Developing Countries

It has been recognized that an adequate nuclear physics infrastructure, including nuclear data measurements is a necessity for a country with strong nuclear interests in energy and industrial applications. In this spirit the Nuclear Data Section together with the Department of Technical Cooperation organized a program of data technology transfer to developing Member States consisting of This activity is directed towards training staff and supplying scientific equipment for laboratories in developing countries which had earlier received accelerators, neutron generators or research reactors through the IAEA Technical Cooperation Projects. One such example is the fast neutron research facility at the Chiang Mai University in Thailand (see Fig. 9) where nuclear data measurements are conducted.

[Fig.9: Fast neutron research facility at Chiang Mai University]
Fig.9: Fast neutron research facility at Chiang Mai University

N.P.Kocherov, kocherov@iaeand.iaea.org