**Author details**

#### Luciano Burgazzi

*Reactor Safety and Fuel Cycle Methods Technical Unit, ENEA, Italian National Agency for New Technologies, Energy and Sustainable Economic Development, Bologna, Italy* 

## **9. References**


[4] United States Nuclear Regulatory Commission's (U.S. NRC) Reactor Safety Study (WASH-1400, 1975).

56 Nuclear Power – Practical Aspects

their reliability. This is a crucial issue to be resolved for their extensive use in future nuclear power plants. Recently, the development of procedures suitable for establishing the performance of a passive system has been proposed: the unavailability of reference data makes troublesome the qualification of the achieved results. These procedures can be applied for evaluating the acceptability of a passive system, specifically when nuclear reactor safety considerations are important for comparing two different systems having the same mission and, with additional investigation, for evaluating the performance of an active and passive system on a common basis. The study while identifying limitations of the achieved results or specific significant aspects that have been overlooked has suggested

 In order to get confidence in the achieved results, the reduction of the so identified level of uncertainty pertaining to the passive system behaviour, and regarding in particular the phenomenological uncertainty. In fact, it's worth noting that these uncertainties are mainly related to the state of knowledge about the studied object/phenomenon, i.e., they fall within the class of epistemic uncertainties, thus suitable for reduction by

The determination of the dependencies among the relevant parameters adopted to

 The study of the dynamical aspects of the system performance, because the inherent dynamic behaviour of the system to be characterized: this translates into the

The comparison against the active system, also to evaluate the economical

Future research in nuclear safety addressing this specific topic relevant to advanced reactors should be steered towards all these points in order to foster and add credit to any proposed approach to address the issue and to facilitate the proposed methods endorsement by the

*Reactor Safety and Fuel Cycle Methods Technical Unit, ENEA, Italian National Agency for New* 

[1] IAEA TEC-DOC-626, 1991. Safety Related Terms for Advanced Nuclear Power Plants.

[2] IAEA TEC DOC-1474, 2005. Natural Circulation in Water Cooled Nuclear power Plants. *Phenomena, models, and methodology for system reliability assessments*, November 2005. [3] IAEA TECDOC-1624, 2009. Passive Safety Systems and Natural Circulation in Water

areas for further development or improvements of the procedures:

competitiveness, while assuring the same level of safety.

*Technologies, Energy and Sustainable Economic Development, Bologna, Italy* 

Cooled Nuclear Power Plants. November 2009

analyze the system reliability.

scientific and technical community.

**Author details** 

Luciano Burgazzi

**9. References** 

September 1991.

development of the dynamic event tree.

gathering and analyzing a relevant quantity of information and data.


[23] Burgazzi, L., 2008b. Incorporation of Passive Systems within a PRA Framework. Proceedings of PSAM9, 9th International Probabilistic, Safety Assessment and Management Conference, Hong Kong, 18-23 May 2008.

**Chapter 0**

**Chapter 3**

**Geological Disposal of Nuclear Waste: Fate and**

Nuclear power plants use nuclear fission for generating tremendous amount of heat for the production of electrical energy. Currently, there are many nuclear power plants in operation worldwide, which produces high-level nuclear wastes at the same time. Nuclear wastes are being produced as by-product of nuclear processes, like nuclear fission (spent fuel) in nuclear power plants, the radioactive elements left over from nuclear research projects and nuclear bomb production. The management and disposal of these previously stored and continuously generated nuclear wastes is a key issue worldwide. A huge amount of radioactive wastes have been stored in liquid and solid form from nuclear electricity/bomb production plants from several decades at different locations in the world. For example, the Hanford Site is a most decommissioned nuclear production complex on the Columbia River in the U.S. state of Washington, operated by the United States federal government as shown in fig 1 [21, 28, 50]. Hanford was the first large-scale plutonium production reactor in the world. The Hanford site represents approximately two-thirds of the nation's high-level radioactive waste by volume

Radioactive/nuclear wastes are specific or mixture of wastes which contain radioactive chemical elements that can not be used for further power production and need to be stored permanently/long term in environmentally safe manner [63]. The ultimate disposal of these vitrified radioactive wastes or spent fuel elements requires their complete isolation from the environment. One of the most favorite method is disposal in dry and stable geological formations approximately 500 meters deep. Recently, several countries in Europe, America and Asia are investigating sites that would be technically and publicly acceptable for deep geological storage of nuclear wastes. For example, a well designed geological storage of nuclear waste from hospital and research station is in operation at relatively shallow level in Sweden and a permanent nuclear repository site is planning to be built at deep subsurface system for nuclear spent fuel in Sweden in order to accommodate the stored and running nuclear waste from ten operating nuclear reactors which produce about 40 percent of Sweden's electricity (In Sweden, the responsibility for nuclear waste management has been

> ©2012 Sharma, licensee InTech. This is an open access chapter distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly

©2012 Sharma, licensee InTech. This is a paper distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

**Transport of Radioactive Materials**

Additional information is available at the end of the chapter

cited.

Prabhakar Sharma

**1. Introduction**

[28].

http://dx.doi.org/10.5772/50391

