epr-method (2003) - IAEA Publications - International Atomic Energy ...

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A7 - ASSESSING THE INITIAL PHASE Threat category Responsibility
Elements I II III IV V O L N
In the emergency classification procedures, provide the instrument readings to be used as EALs (see
Element A2.5) in order to indicate the presence of the conditions stated in Appendix 6 warranting
declaration of different classes of emergency. The EALs should be in the units displayed by instruments
available in the control room. The procedures should not rely on a single indicator as the basis for an
assessment and, as much as possible, measurements should be used that are direct indicators of the
condition of interest (e.g. water level in the reactor vessel). The procedures and operator training should
address response of instruments under abnormal conditions, and should include warnings when
instrument readings may be misleading. They should also address the response of area and process
radiation monitoring and of other instrumentation essential during a severe emergency and during
emergency system operations (e.g. recirculation mode following core damage). For reactors, the EALs
should be consistent with Ref. [18].
A7.3 Arrange to assess, during an emergency, radioactive contamination, releases and doses in the
emergency zones to determine or modify urgent protective actions following a release. Arrange for
monitoring of the environment and of the contamination of people (e.g. evacuees) within the zones.
Include designated trained teams and instrumentation and arrange to assess the monitoring results in order
to determine, modify or initiate urgent protective actions to protect workers and the public, using
operational intervention levels (OILs) and making arrangements to revise the OILs to accommodate the
conditions present during the emergency (4.71).
For the predictable environmental release routes (atmospheric and water), provide methods to assess
releases by these routes under emergency conditions. For these release routes, develop EALs for
classification (see Element A5.3, A7.2) that indicate potential off-site doses warranting declaration of an
emergency consistent with Appendix 6. These EALs should be in units directly measured by instruments
(e.g. Bq/s) available in the control room and be calculated in advance assuming realistic (e.g. average)
dispersion conditions. Provisions should be put in place to estimate the radionuclide mixture of releases.
Develop methods to project off-site consequences implied by facility conditions (e.g. for unmonitored or
future releases). This could be precalculated doses for different accident conditions as shown in Ref. [18]
or computer models such as INTERAS [18].