Internal hazards

We use the international Hazard road sign A to warn that a skeletal equation is not balanced. Then we balance hydrogen and oxygen atoms ... 

Dangerous goods" is defined in the context of recommended international hazardous material transportation regulations. The UN "Orange Book" should be consulted for further information on the definition of dangerous goods for transportation purposes (UN 2002). 

Radioactivity results when some part of an atom is unstable. The instability exists because the orbital electrons or the nucleus contain too much energy. Radioactive atoms are called radionuclides. They release excess energy by emitting radiation. The type of radiation released (alpha, beta, or gamma particles) may be more or less hazardous to humans, depending on the location of the radioactive materials. Exposure to radioactive materials outside the body poses external hazards. Radioactive materials may also be hazardous when ingested, inhaled, or injected and thus pose internal hazards. The sections below describe the characteristics of radiation particles as external or internal hazards and as they may be encountered after a terrorist attack. Chapter 3 provides additional details and addresses health effects associated with exposure to radiation. 

Alpha (a) particle It is a double positive charge carrying helium nucleus He2+) released spontaneously from a high-atomic mass radioactive element. It has low penetration power and can be stopped by a thin sheet of paper or a layer of air. Has no external hazards has internal hazards. 

Beta (0) particle It is a negatively charged particle equivalent to an electron (e or 0 ). It is emitted by a radioactive material. A beta particle carrying a positive charge is called a positron (0+). May cause skin bums. It is both an external and internal hazard. 

Burcham, P.C., Internal hazards baseline DNA damage by endogenous products of normal metabolism, Mutat. Res., 443, 11, 1999. 

Internal Hazards. In many cases, the primary health hazard from radiation is through internal contamination (usually inhalation). The rate at which contamination may be inhaled is highest during the initial period following the accident when a substantial quantity of contamination... 

Beta particle P 5 meters Several layers of skin Stopped by moderate clothing Possible skin injury. Internal hazard if inhaled or ingested... 

D. The external radiation hazard from exposure to tritium is extremely small, because the beta particles emitted cannot penetrate the dead layer of skin. However tritium is easily internalized through inhalation and absorption through the skin. The low energy beta radiation from the tritium is an internal hazard only (i.e., the isotope must get inside your body to cause damage). 

Beta Particle - An electron emitted from a nucleus during a radioactive decay. Beta radiation is a skin hazard in addition to being an internal hazard. 

The term dangerous goods is used internationally hazardous materials describes the same materials and is used in the United States and other countries. The terms are used interchangeably in the Glossary. 

The Level 1 LPS PSA of Mochovce Unit 1 includes as internal events LOCAs, transients and internal hazards, i.e. fires and floods. External events included seismic events, air craft crashes, influences of external industrial facilities, and extreme meteorological conditions. Operational experience and results obtained from PSA for Bohunice V-2 NPP and Dukovany NPP as Mochovce NPP are used as much as possible. 

According to [8] the operator of a plant does not only have to make provisions against plant internal hazard sources but also against external ones (literally in Germany environmentally caused hazard sources). This concerns impacts from outside the establishment (and hence on the plant) which may jeopardize the function of safety-relevant parts of the plant [27]. Such impacts may originate from ... 

INTERLOCKS ON - Equipment with internal hazards, such as X-ray diffraction cameras, or areas in which the space is rendered unsafe to enter by the presence of a hazard, are often provided with a fail safe circuit, or interlock, which will turn off the equipment representing the problem if the circuit is broken. The sign provides a warning that the interlock is on to prevent access to the hazard. 

Moreover, Level 1 offers the initial protection basis against important external or internal hazards (e.g. earthquakes, fires, floods), even if some additional protection may be necessary at higher defence levels. 

AR59 Design of reactor containment systems for nuclear power plants. Safety guide, NS-G-1.10, 2004. AR60 Protection against internal hazards other than fires and explosions in the design of nuclear power plants. Safety guide, NS-G-1.11, 2004. 

All of the events listed in Table 3B-1 were eliminated from further consideration by using this screening process. (Some events were eliminated based on multiple criteria.) This does not mean they are all eliminated from all further consideration in the HCF SAR. Some external events are considered in Appendix 3C, Preliminary Hazard Analysis," or Appendix 3D, Failure Modes and Effects Analysis," as potential initiators to internal hazard events. 

In nuclear safety there is a clear distinction between internal events (loss-of-coolant accidents and transients) and external events. External events is an umbrella term for internal hazards (e. g. fires) and external hazards. Up to now, most PSAs have focnsed on internal events and internal hazards. With the exception of seismic PSAs, PSAs for external hazards are not yet very common. 

Protection against Internal Hazards other than Fires and Explosions in the Design of Nuclear Power Plants... 

PROTECTION AGAINST INTERNAL HAZARDS OTHER THAN EIRES AND EXPLOSIONS IN THE DESIGN OE NUCLEAR POWER PLANTS... 

An internal hazard is a hazard that is initiated in the operations area of the plant, within the operations boundary of the site. 

Guidance is provided on how to analyse the consequences of PIEs, including the analysis of secondary and cascading effects as well as the corresponding functional analysis. Means of protection against internal hazards are discussed, as well as methods and means of reducing the aforementioned probabilities. 

Section 2 is dedicated to general considerations in dealing with internal hazards it covers the selection of PIEs, considerations on acceptability, analysis of consequences (including cascading and secondary effects) and considerations for protection and safety. In Section 3 the aforementioned internal hazards are reviewed. A section is dedicated to pipe failure, which is an initiating event common to pipe whip, jet effects and flooding. 

Requirements and concepts for the safe design of nuclear power plants are developed in Ref [1], in which PIEs are defined. PIEs can challenge any level of defence in depth and have to be considered in the design process. The PIEs to be considered will include internal hazards. PIEs are defined in appendix I of Ret [1]. 

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