International Nuclear Event Scale

The assessment of integral damage caused by implications of individual accidents was compared with some standard levels determined by the International Nuclear Event Scale (INES). The INES scale, supplemented by expert assessments of economic damages, as applied to typical emergencies with decommissioning objects, is illustrated in Table 1. 

TABLE 19.6. The international nuclear event scale (INES) used for the reporting of nuclear events... 

The failures observed in the plant have not caused the operational safety limits to be exceeded and are of level 0 or 1 on international nuclear event scale. 

Thus, abnormal operation events occurred in the power unit resulted in no radiation impact on residents and environment, since all these events were below the International Nuclear Event Scale (according to off-site impact ), i.e. could be neglected. 

INTERNATIONAL ATOMIC ENERGY AGENCY, The International Nuclear Event Scale (INES) User s Manual, 2001 Edition, IAEA, Vienna (2001). 

INES International Nuclear Event Scale INES is an information system operated by IAEA to inform the public about safety related events in nuclear power plants (IAEA 2001) http //www-news.iaea.org/news/... 

Failure of the sodium coolant circuit and its long exposure to the atmosphere lead to a fire and, consequently, to a 24-h release of Ci accounted for by Na alone. Further Na burning will cause cooling interruption and fuel melting with release of 10 —10 Ci, depending on the reactor power level and the time of fuel irradiation. Such an accident is classed as Level 7 of the International nuclear event scale (INES) and involves inevitable evacuation of the local residents with prolonged isolation of the territory (ISTC 2001 Orlov et al. 2003). 

The emergency classification should not be confused with the International Nuclear Events Scale (INES) (IAEA, 1997c). INES is designed to indicate how serious an event was after it is understood and is not the basis for the response. Determining the INES rating is impossible early in an event and does not form part of the initial response, and determining the rating should not delay any response actions. 

The emergency response classification system should not be confiised with the lAEA/NEA International Nuclear Event Scale (INES). The INES is designed for communicating the severity or estimated severity of an event to the pubhc and cannot be the basis for emergency response actions. 

INES International Nuclear Event Scale Defines the safety significance of an event occurring in a nuclear facility. Scale 0 (least serious) to 7 (most serious). Chernobyl would have been a 7. 

On 20 April 2005, British Nuclear Group Sellalield Limited (BNGSL) discovered a leak from a pipe that supplied highly radioactive liquor to an accountancy tank in a part of the Thermal Oxide Reprocessing Plant (THORP) at Sellafield, known as the feed clarification cell . The incident was categorized by BNGSL as 3 on the International Nuclear Event Scale. 

The reactor equipment failures which took place did not violate safe operating limits and according to the International Nuclear Event Scale were assigned to levels 0 or 1. 

There was no overexposure of the plant personnel and no contamination on or off the site was registered. All this gave grounds for classification of the event as an anomaly, i.e. level 1 to the International Nuclear Event Scale. After completion of the scheduled refuelling and the necessary repair the reactor was returned to power on Oct.24, 1993. 

To date the world has seen the occurrence of a number of major nuclear reactors accidents (rated 5 and above on the International Nuclear Event Scale by the International Atomic Energy Agency). For Fukushima we consider one accident, although more than one reactor was involved, to ensure the list is made of independent accidents. Assuming seven accidents, the historic world average rate of Scale 5-t accidents is 4.75 x 10 " Scale 5+ acci-dent/annum (Table 37.2). 

Hydrogen explosions in units 1, 2 and 4 and pressure venting operations in the reactor vessels caused massive releases of radioactive material to the atmosphere and environment. The prevailing winds transported most of the atmospheric emissions in an easterly direction into the Pacific Ocean region. On the 8 stage International Nuclear Event Scale (INES) the accident was rated as 7, the highest rating on this scale. ... 

The operating organization should provide information on the status of the plant to the public in a regular and timely manner. The pnbUc should be informed of any significant event on the International Nuclear Event Scale (INES) [4] and of any enforcement action taken by the plant. 

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