Operational intervention levels

A process for calculation of clear operational intervention levels based on the criteria (see Section 5 for details on intervention levels)... 

Initial Accident Assessment and Classification. First responders will base their initial assessment and actions on the placards, UN numbers and other observables (fire or signs of a spill). Radiological monitoring will be needed if a ruptured package is suspected. Operational intervention levels (see Section 9.5.1) for transportation accidents must be developed in advance in order to be able to interpret monitoring results. 

Evacuation and relocation decisions will be based on environmental monitoring and operational intervention levels (see Section 9.5.1). People should be monitored for both external and internal contamination. When an individual is externally contaminated, his or her home and workplace must also be monitored. Monitoring for external contamination is done with hand-held contamination monitors or portal monitors. Portal monitors have the advantage of processing a large throughput. 

Default operational intervention levels should be calculated in advance for the various types of releases that could occur. These default values would be used initially to assess environmental data. Some of the IAEA default OILs for a nuclear power plant release are shown in Table 9.12. As soon as possible, operational intervention levels should be recalculated based on the actual composition of the release and these values should replace the default operational intervention levels if appropriate. Examples of the detailed procedures used to calculate operational intervention levels are provided in (IAEA, 1997b). This reference also provides generic operational intervention levels for a nuclear power plant release and the IAEA generic intervention levels. 

Operational intervention levels are not restricted to power-reactor emergencies. They can be calculated for all other types of activities based on the radionuclides present, the exposure pathways and the types of measurement instruments available. 

In summary, each country that could be impacted by major atmospheric release or contaminating event should have established intervention and action levels to be used as a basis for implementation of protective actions. Default operational intervention levels should be established for the mixture of radionuclides that may be released during an emergency. These levels can then be used promptly during an emergency to determine whether environmental measurements indicate that protective actions should be taken. 

TABLE 9.12 Example of Default Operational Intervention Levels for a Reactor Accident... 

In the second case, only gamma dose-rate instruments and operational intervention levels are needed to determine where actions are needed. The first category of accidents, however, is much more difficult to assess. For such events, protective action must be taken before or shortly after a very severe release to be effective in reducing the risk of severe deterministic health effects near the facility. The strategy for taking protective actions for severe reactor accidents is discussed above under Public Protective Actions. 

As previously discussed, operational intervention levels should be calculated that would indicate when different types of protective actions are needed. These operational intervention levels will be actual readings that can be obtained by environmental monitoring instruments. The values and the instruments used are determined by the nature of the radioactive release. For example, operational intervention levels based on gamma dose rates can be used to determine whether evacuations and relocations are warranted following a major release from... 

For example, the iodine operational intervention level for immediate restrictions on food consumption (e.g., milk from grazing cows) is 10 kBq/m. The dose-rate conversion factor for external exposure from a uniformly contaminated surface is 1.33 10 mSv/h/(kBq/m ). Therefore, for a ground contamination equal to the operational intervention level, the dose rate at 1 m from the ground would be 13.3 10 mSv/h. This is much lower than the typical background of 10 " mSv/h and would not be detectable using hand-held gamma dose-rate meters. 

It is important to note that the EPA s PAGs cannot be used directly to interpret environmental measurements. For this purpose, derived response levels (DRLs, another name for operational intervention levels) have been established for environmental survey instruments indicating when protective actions should be taken to meet the PAGs. The DRLs will be different for different types of releases and different times during the emergency. Default DRLs for nuclear power plant release are shown in Table 9.22. 

Process control instrumentation controls the FCC unit in a safe, monitored mode with limited operator intervention. Two levels of process control are used ... 

These results do not have any diagnostic meaning. The dynamics of the ACU values after an operative intervention could be taken into account regarding the existence of metastases. As demonstrated in Figure 12, prognostic relevance can be ascribed to ACU. The rise in ACU value is caused in this case by increase of the bilirubin level under the conditions of the life-threatening inflammatory processes [1],... 

The precursor was identified in the maintenance sub-process. In practice, the operators from technical support observed the presence of substances inside the packaging machines. Subsequently, they consulted the chief operator on how to remove the substances from the machines and perform the most suitable intervention. These actions correspond with the control elements on the operational control level. The actions were performed in order to resume production quickly, and adhere to planned schedules. Additionally, experience and training provided the operators with guidelines on how to perform the maintenance effectively. In practice the production manager, responsible for any preventive solutions was not aware of the existence of this precursor and consequently had no overview of these deviations even though the company s quality and safety standards required an overview of all deviations and... 

A policy of a three level safety design was also adopted. This includes the use of utilities and safety devices. An orthogonal design was used such that interruption of any part of these services would not affect the remaining sections. Manual bypasses were also provided in order to permit operator intervention at any point in the process. Finally, any releases of material from any of the relief devices were directed into secondary holding vessels in order to prevent releases into the atmosphere. 

In order to remove the endogenous toxicosis, we have applied various methods of detoxification in 22 patients. In 14 cases, one or two sessions of plasmapheresis were performed. Biochemical markers used for determining the level of toxemia were middle molecules . In six cases, against the background of intensive care, oral sorption (enterosorption) was administered 2-3 days after operative intervention. 

A final example of totally automated HPLC (although it isn t for pesticides) will demonstrate how many different unit operations can be done in a single system to take the tedium out of repetitive analyses. The drug analyzer depicted in Figure 14 was designed to determine therapeutic levels of theophylline in human serum (8). The sampler (in the center) aspirates 50 uL of serum into the analytical cartridge, then to the EDM, and finally to the LC module. The following series of operations takes place at the rate of 20 samples per hour without operator intervention unmeasured, untreated sample is aspirated, diluted with buffer, and mixed with an internal standard the system then precipitates the protein, removes the particulates, extracts the analyte (and internal standard) into... 

Due to the above limitations, an energy balance control scheme such as scheme 16.7 is not recommended, but some situations exist where this scheme can offer better product composition control than many other alternatives. Superfractionators with a reflux to distillate ratio of 10 to 1 or more are one example. Here, distillate flow may be too small to satisfactorily control either accumulator level or column temperature. The author has experienced a satisfactory operation of scheme 16.7 in a propylene-propane splitter, with intermittent operator intervention to ac ust the material balance. The cycles in reflux and reboil (see above) could be tolerated, as the column was not operating close to its limits. In this column, scheme 16.7 gave tighter composition control than scheme 16.4d. 

Duplicate and triplicate measurements of pressure and temperature of critical pieces of equipment are common in order to ensure safe operation. When a reading exceeds a certain threshold value, an alarm might sound or a reading may appear on the console for the operator to take action. Generally, there are different levels of alarms as well as interlocks. Alarms generally require operator intervention while an interlock condition usually will shut the process or equipment down automatically. 

Steady-state procedures that require routine operator intervention can be either event- or time-based. Event-based procedures are usually performed in response to a system change or condition. For example, with regard to the cooling tower example, the facility may have event-based procedures to handle issues such as adding chemicals to the water, or controlling the temperature of the water. Time-based procedures are those that are to take place at a specified time interval. For example, the operator may have to catch a sample of the cooling water every 4 hours in order to check the chemical concentrations in the water. Many maintenance-related activities, such as checking the lube oil level in pumps, are time based. 

The passive system for residual heat removal is intended to remove residual heat from the core foUowing complete loss of power supply when the reactor operates at any power level. The system consists of two loops and operates without power sources to complete cool down without operator intervention. 

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