Interventions levels

There are the following intervention levels for use of the different preventive measures 1) person under study 2) enterprise or children cohort in... 

FDA Protective action goals and derived intervention levels by age group (Bq/kg) FDA 1998... 

Figure 8.9 Interpolated distribution of quasi-total elemental concentrations of Pb (A), Zn (B) and Cu (C) in the soils of the main cities of the Campania region ofltaly (Albanese, 2008), based on aqua regia concentrations, compared with the bioavailable (ammonium acetate-EDTA) concentrations (dots). The data were reclassified by means of the intervention levels established by Italian law D.M. 152/99 (Ministero dell Ambiente, 2006).

Table 4 offers the information on the above radionuclides, which was used in calculations and analysis of the results (half-life periods, levels of initial activity, yearly ingress limits (YIL), intervention levels (IL), migration parameters). 

In 1991 a comprehensive review of available data resulted in the maximum tolerable blood level for children being reduced to 100 pg/litre in the USA. The Centers for Disease Control in the USA state that above this level there is a risk of adverse developmental effects in children such as reduced IQ, growth retardation, and lower hearing acuity. Lead levels above this in the blood in adults was associated with an increased risk of hypertension. The equivalent intervention level for blood lead in the UK has been set at 250 pg/litre, but, apparently, cognitive deficits have been detected at levels below this. Such effects are often difficult to measure, and three bodies (the Medical Research Council, a Royal Commission, and the Department of Health) which separately evaluated the data in the UK found that studies on this effect of lead have been inadequate and that the case was not proven. Studies are still being pubhshed which purport to... 

In large-scale facilities such as reactors, hot laboratories and accelerators, area monitors are installed in the controlled area to detect abnormal increments of radiation dose rate and to inform the workers of abnormalities by sound or light to prevent unnecessary exposure. Abnormal levels are previously defined as investigation level and/or intervention level. 

Clark, R.H., Principles for the establishment of intervention levels for the prediction of the public in the event of serious nuclear accidents, Emergency planning and preparedness for nuclear facilities (Proc. Symposium Rome, 1985), IAEA, Vienna, pp. 373-384, 1986. 

Potassium is primarily an intracellular ion and, consequently, decreases in whole-body potassium may not be detected by plasma measurements (Muylle et al 1984). Although erythrocyte potassium content has been used to estimate whole-body potassium (Muylle et al 1984), its accuracy has not been validated. Moreover, the extracellular potassium concentration (reflected in the plasma) is critical for neuromuscular transmission and is, therefore, more relevant to clinical signs than whole-body potassium stores (Rose 1994). The intervention level for treatment of hypokalemia has not been established. In postoperative colic and proximal enteritis, where the prevention of ileus is a primary goal, it may be prudent to supplement if the plasma potassium concentration falls to <3.5mEq/l. In other situations, especially those being fed enterally, it may not be necessary to treat if the plasma potassium concentration is >3.0mEq/l. 

The Food and Drug Administration (FDA) develops standards for radioactive material concentrations in food (FDA 1998), and medical devices used in radiation therapy (FDA 1997). The FDA recently updated its guidance document that presents recommended action levels for radionuclides in foods, both domestic and imported (FDA 1998). These derived intervention levels (DILs) are estimated levels in food that could lead to individuals receiving a radiation equivalent dose equal to the FDA protection action guide (PAG) that is set as the more limiting of either 0.5 rem (5 mSv) for committed effective dose or 5 rem (50 mSv) committed dose equivalent to any individual tissue or organ. Table 8-2 presents the most restrictive DILs for strontium. 

Derived intervention levels (DIL) are concentrations of radioactivity in food whose consumption would deliver a committed effective dose equivalent equal to the most limiting of the protection action guides (PAGs) developed by FDA (1998). 

The Food and Drug Administration has developed derived intervention levels (DIL) for food. A DIL is the concentration in food that equals the PAG if ingested over the relevant period of time. 

DIL = derived intervention level Bq/kg PAG = protective action guideline, mSv F = fraction of food assumed contaminated Food intake = quantity of food consumed kg DC = dose received per unit of activity mSv/Bq Sv = Seivert =100 rem... 

During Saturday 26 April 1986, air activity and ground deposition measurements in the towns of Pripyat and Chernobyl were such that inhabitants were advised to shelter in their homes with windows and doors shut. Potassium iodate tablets were distributed to protect them from accidental intake of Iodine-131. Later in the day radiation levels in Pripyat reached 10 mSv/h (1 rem/h) in some areas, such that the lower intervention level for whole body dose, 250 mSv (25 rem), would be exceeded in 12 h. It was decided to evacuate the town s population (45000), and this was completed during Sunday afternoon, using public transport vehicles from the state capital of Kiev, 120 km away. Figure 5.3 shows the area around the Chernobyl nuclear power plant. 

The upper intervention levels are five times the lower levels of dose. It is desirable to initiate countermeasures at the lower intervention levels. At the upper intervention levels action must already have been taken. 

This uncertainty is exacerbated by the varying standards which different countries have adopted in determining intervention levels, as discussed in detail in sub-section 8.5 on the European Economic Community and illustrated by some examples in Table 8.2. Thus, although the international regime on compensation provisions is not directly linked to harmonisation of intervention standards, it is nevertheless important to the functioning of this regime that a solution be found . ... 

The Article 31 Group had meanwhile been working on proposals for permanent intervention levels to apply to commodities traded within and across the Community border. It recommended identification of two reference levels for radiation exposure protection—a lower level below which action is unlikely to be justified and an npper level at which it is almost certain that action shonld be attempted. For the first year after an incident, the Group recommended adoption of ICRP lower and upper limits of 5 mSv and 50 mSv and levels of 10 mSv and 10 mSv for subsequent years. These subsequent year figures were proposed because after one year there will have been time to organise effective and economic means of control should these still be necessary . ... 

The Group noted the problems in translating these radiation protection limits into intervention levels based on the specific activity of foodstnffs bnt in September 1986 recommended new limits, listed in Table 8.3. The Group proposed intervention limits for I and Sr isotopic contamination and for Pn, as well as Cs. These proposals did not find favonr with the Commission which discussed internally its own recommendations in autumn 1986 (see Table 8.3). 

The Commission never came forward with specific recommendations to the Council of Ministers meeting in early 1987. Instead, it decided to organise an international scientific discussion meeting on the subject in April 1987. At the same time, the Article 31 Expert Group reconsidered their recommendations and came forward with simplified limits. The Commission decided that even these were pitched at an unacceptably high level and advanced in support the disagreement on appropriate intervention levels which had become apparent at the April 1987 scientific discussion meeting. 

The transfrontier impact of nuclear installations has been too readily dismissed in the past and it is now necessary to reinforce environmental monitoring and to provide the possibility of independent verification. Chernobyl has revealed the Community s inability to respond in a coordinated way to a major accident... " The action taken over foodstuff intervention levels was taken as much in an attempt to prevent economic chaos from the disruption of markets as it was to establish human health protection. Concerted action over intervention levels has fallen foul of uncertainty about dose-response patterns at low levels of radiation exposure and the different philosophies adopted in member countries about how to handle environmental pollution, in particular whether to take immediate action on a reasonable basis of presumption about effects or to delay action until certainty has been scientifically established. 

The situation in other countries does not appear to have been better. The intervention levels used in different countries, even within the EEC, often allowed accusations of danger to the public health to have greater credence than the figures justified. There seems little doubt that the whole area of monitoring and publishing of data needs review and it is encouraging to note that discussions have started on this within the EEC. 

When the reactor pressure exceeds a certain value, the relief valve (9) is automatically actuated. This valve is located on the upper part of the pressurizer and discharges steam in a discharge collecting tank (10), partly filled with cold water and provided with an emergency rupture disc (11), which avoids its excessive pressurization. When the pressure within the tank reaches the intervention level of the rupture... 

Category 4 Severe deterioration - intervention level of concern. This condition should not occur very frequently on the motorway and the all-purpose trunk road network as earlier maintenance should have prevented this state from being reached. At this level of deterioration, more detailed (scheme level) investigations should be carried out on the deteriorated lengths at the earliest opportunity and action should be taken if and as appropriate. 

Decision criteria relates to the safety critical deterioration level. It is necessary to determine this level to be able to make appropriate decisions regarding further action. Usually a first basic intervention level is defined according to relevant codes, standards or internal company requirements. A minimum required wall thickness is usually determined due to a stress criterion and depends on allowable stress, design pressure, pipe dimensions and material strength. When deterioration beyond this basic intervention level is revealed through inspection, further actions must he decided. When the basic intervention level is reached, there may... 

LRUs will be recorded at the intervention level. If two tasks are performed leading to two LRU replacements (for instance), then in FRACAS two interventions will be opened for one assessment. In case of two different assessments, two assessments will be opened for a given event. 

Principles for Establishing Intervention Levels for the Protection of the Public in the Event of a Nuclear Accident or Radiological Emergency (being revised)... 

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