The raison d'etre of research reactors is based on their role in a number of research fields, including radiochemistry. Inversely, it is in the interest of a healthy development of radiochemistry that a sufficient number of reactors will remain in operation and that the downward trend is in this reversed. In this paper, directions for further developments in reactor based radiochemistry are discussed, taking into account also relevant developments in competing fields. The discussion is focused on neutron activation analysis as well as tracer applications and environmental radiochemistry. Moreover, the consequences for reactor operations will be indicated.
Results are presented of the performance of INAA and RNAA when compared with other spectrometric methods for trace element analysis. Indications are given for further developments aiming at exploiting the advantage and reducing the drawbacks of these two analysis technique.
Policy and program of activities are described of the Interfaculty Reactor Institute (IRI) in Delft. Underlying considerations are discussed, including factors such as direct public interests and political appreciation of the activities. Attention is paid particularly to the further development of the reactor associated experimental facilities.
Since the 1970's, an appreciable number of research reactors at universities as well as national institutes has been closed down. If this trend is further continued, it will become detrimental for the future development in scientific areas that largely depend on the reactor, such as radiochemistry and n-beam research. Therefore, the facilities still in operation have to develop strategies aiming at assuring their activities and at further development of reactor and associated experimental facilities. Key aspects of such strategies will be discussed, with particular attention for the possible role of radiochemistry.
Data are presented on the number of publications per year for the last 25 year, dealing with activation analysis. From these
data it can be concluded, that the role of activation analysis is declining both in absolute terms and relative to the total
of activities in analytical chemistry. A policy is described aimed at stoppnig this decline.
The measuring system described in this paper, developed for non-destructive neutron activation analysis, consists of a semiconductor
detector gamma-ray spectrometer and a sample changer coupled to a PDP-9 computer via a CAMAC interface system. CAMAC modules
implemented in this system are an ADC interface, a sample changer control, display unit, a timer and a time-of-the-year clock.
The spectra are accumulated in a section of the computer memory. The computer is further used for experiment control and for
the analysis and interpretation of the measured gamma-ray spectra.
Contamination of rabbits during transfer in a fast irradiation facility has been reduced by development of a rabbit system containing no metal parts, and only plastic and carbonfiber. As a result, this system could be automated and has been equipped with a sample changer. Flexibility and versatility in the operation of this new system was attained by a combination of software and hardware control. With this new system, large-scale analysis can be performed with a considerable saving in man-power of the users.
Contamination of rabbits with activities induced in the metal parts live of an irradiation facility constitute a major source of problems for INAA using short-lived nuclides. If the half life of the nuclides of interest is longer than about 10 sec, it is possible to unpack the sample without appreciable loss of information. But for shorter half lives, automatic unloading devices for rabbits have to be used. Such systems are complicated and can not be used for cyclic activation procedures. At IRI, a fast rabbit system is being installed consisting of polyethylene tubing and a carbonfiber end point at the core position. Carbonfiber combines a good mechanical stability under in-core conditions with a very high purity. It can be expected that as a result of the use of this material, contamination by the rabbit will become negligible, so that samples can be counted directly without unpacking. Results obtained with this new system are presented, and compared with results obtained with an aluminium rabbit system used until now.
The procedure in use at our institute for the extraction of the desired element concentrations in a sample from the peak data
obtained by a spectrum analysis program, is described in detail. The method is based on the use of zinc as a single comparator
and takes into consideration primary activation products as well as their daughter isotopes. After assigning isotopes to spectrum
peaks on the basis of γ-ray energies, the list of possible isotopes is reduced to a list of present isotopes with their concentrations
using criteria based on half life, specificity and intensity of γ-rays. For elements not observed, detection limits are estimated.
The procedure has been used extensively during the last two years and has shown to produce reliable results.