Band 70, Heft 5-6

In the last years several internationally accepted standards such as the ISO 9000 and ISO 14000 series and other function-specific management systems standards have been developed. At the same time, it has become imperative for organisations to continuously improve their overall quality, environmental and safety performance. Therefore, the need to create integrated management systems is of growing importance to enable an easier handling of the different management systems. This paper has two main objectives. The first one is to address the key issues in the underlying theory of integrated management systems including benefits and limits, the second one is to illustrate the importance of an integrated (in particular safety) management system and the experience feedback providing examples from different areas and different organisations in the nuclear field.

A new approach is proposed for the calculation of non-equilibrium deuteron energy distributions in nuclear reactions induced by nucleons of intermediate energies. It combines the model of the nucleon pick-up, the coalescence and the deuteron knock-out. Emission and absorption rates for excited particles are described by the preequilibrium hybrid model. The model of Sato, Iwamoto, Harada is used to describe the nucleon pick-up and the coalescence of nucleons from the exciton configurations starting from (2p, 1h). The model of deuteron knock-out is formulated taking into account the Pauli principle for the nucleon-deuteron interaction inside a nucleus. The contribution of the direct nucleon pick-up is described phenomenologically. The multiple pre-equilibrium emission of particles is taken into account. The calculated deuteron energy distributions are compared with experimental data from 12 C to 209 Bi

The analysis of Group Distribution Header (GDH) blockage events shows that the integrity of several fuel channels could be violated. A best estimate analysis of GDH blockage events in the RBMK-1500 reactor (Large Channel Type Water-cooled Graphite-moderated Reactor) of the Ignalina Nuclear Power Plant is performed. Uncertainties of the initial and boundary conditions as well as ATHLET code models were taken into account during the simulation. The analysis is performed employing the code ATHLET Mod. 1.2 Cycle D and the package SUSA 3.5. In this paper the ATHLET code model of Ignalina NPP, event scenarios and results of the analysis are presented. Analysis results show that GDH blockage events do not lead to severe consequences.

The Accident Localisation System (ALS) of the Ignalina nuclear power plant is a “pressure suppression” type confinement, which protects the population, workers and environment from radiation hazards. According to the safety justification of RBMK-1500 reactors, ∼110 m 3 of hydrogen is released to the ALS compartments during a maximum design basis accident. To prevent the possible hydrogen accumulation and combustion, a hydrogen concentration control system is installed. The main goal of the present paper is to present the ALS model for the COCOSYS code and assess the effectiveness of the hydrogen control system of the Ignalina nuclear power plant. The analysis performed identified locations of possible hydrogen accumulation in the ALS compartments during the transient processes and assessed the mixture combustibility in these locations for a maximum design basis accident scenario.

Neutronic calculations were performed for the new loading configuration of the ETRR-1 research reactor. The MCNP three dimensions Monte Carlo code and the two dimensions CITATION code are used to model the reactor. The power and thermal flux distributions in the reactor core are calculated. The power peak factor and the effect of control rod insertion on both flux and power profiles in the reactor core are determined and analyzed. The partial and total control rods worth are calculated. It was found that the difference between MCNP and CITATION in power distributions is 4 to 8 % and for thermal flux ranges between 3 to 14 %.

The seismic design of a nuclear power plant includes two levels of design earthquake, the safe shutdown earthquake (SSE) and the operating basis earthquake (OBE). The OBE and SSE are considered in the nuclear power plant design as required by the IAEA safety regulations. A typical piping model for the ETRR-2 core cooling system includes ASME-class 1, 2 and 3 piping and was analyzed with regard to both IAEA safety regimes. A load combination, as stated by the IAEA Safety Guide 50-SG-S2, has been considered. The safety guide requires that the OBE should equal to at least one half SSE and that the plant should be shut down if exposed to earthquake intensity greater than the OBE. The results reflect the requirement for the precise design of a supporting system to accommodate for higher seismic peaks more than 0.2 g and the system needs to be more flexible.

The present work is carried out in order to evaluate the cooling process of irradiated topaz at the Egyptian Second Research Reactor (ETRR-2). A mathematical model is developed to simulate the cooling process of a part of the irradiation grid containing one topaz irradiation box. The coolant flow rate distribution through the model channels is estimated taken into consideration the buoyancy effect in each channel. The coolant temperature distributions along the model channels are predicted as well. The COSMOS/M finite element code is used to estimate the temperature distribution through one irradiated topaz stone. The predicted coolant and surface temperature values show the efficient cooling of topaz stones irradiated at the ETRR-2 research reactor.

The H N method is used to calculate the reflection and transmission coefficients for a parallel plane media with linearly anisotropic scattering. The method depends on the use of the angular distributions of the method of elementary solutions. The ortogonality relations of the singular eigenfunctions together with the values of the angular distributions at the boundaries of the given medium lead to the solution of the problem. It is shown that the method leads to concise equations and to fast converging numerical results.

The theory of the autocatalytic burn-wave phenomenon in fertile material for a 1D solitary plane-wave is summerized together with a variety of analytical approximations. It was found that the modified logarithmic product approximates best the fluence- and neutron flux shapes including their skewness – being absolutely necessary for a propagating burn-up wave. Due to the stability of these shapes they propagate isentropically: The deeper reason why we could harness the breeding principle without reprocessing.

For more than 50 years radioactive sources are used beneficially world-wide in medicine, industry, research and teaching. In the early 50ies mainly Ra-226 sources were used especially for medical applications. In the mean time a great number of radio-nuclides with more or less risk to individuals, society and environment are used. The number of these sources is increasing. The available experience with the application of sealed sources in industry, medicine, research and teaching shows that despite the widespread use of such sources a high level of safety can be achieved. One precondition is that the regulatory control of a radioactive source has to be carried out consistently during the life cycle of the sources – “from cradle to grave”. Particular attention has to be given to the so-called orphan sources which are not subject to regulatory control, either because they have never been under control, or because they have been lost, misplaced, abandoned, stolen or transferred without proper authorisation. The concern about orphan sources arising from poor safety and security standards of radioactive material around the world resulted in intensive global actions especially in the light of the security situation after the 11 th September 2001. The improvement of regulatory control is one of the key elements in preventing people, goods and environment from being exposed exceptionally by the misuse of radioactive sources. Important steps toward the improvement of the safety and security of high radioactive sources are the IAEA Code of Conduct on the Safety and Security of Radioactive Sources and the European Directive on the Control of High Activity Sealed Radioactive Sources and Orphan Sources.

The critical slab problem for linearly anisotropic scattering is investigated using the singular eigenfunction method. The third form of the transport equation is considered. The singular eigenfunctions for linearly anisotropic scattering are inserted into the Green's function. This Green's function with the full range orthogonality relations of the singular eigenfunctions together with the appropriate boundary conditions provide the criticality equation. This equation is exact and leads as shown in tables to fast converging numerical results.