atw - International Journal for Nuclear Power | 2.2024

Environment and Safety
51
According to a report by Fermi Energia, Estonia’s
approach to nuclear EPZs is based on the following
regulations [53], [54] :
⁃ EPZs are defined by the Prefect, based on the recommendations
of the IAEA, ASN, and IRSN, and they
are based the characteristics of the SMRs, the potential
consequences of an accident, and the local
specificities.
⁃ EPZs are divided into two sub-zones: the immediate
response zone (ZRI), where urgent protective
actions are planned and implemented without
delay in case of an emergency, and the extended
response zone (ZRE), where additional protective
actions are prepared and implemented as needed,
depending on the evolution of the situation.
⁃ The ZRI covers a radius of 1 km around the SMR,
and the ZRE covers a radius of 5 km. These distances
may be adjusted according to the local context and
the results of probabilistic safety studies.
⁃ EPZs are regularly reviewed and updated, considering
the feedback from exercises, the changes in
the SMRs, and the advances in the scientific and
technical knowledge.
5. Methods used to determine the Emergency
Planning Zone
The simulation of SMR EPZ detection necessitates the
utilization of a variety of instruments and methods to
guarantee the safety and readiness of the surrounding
regions. A variety of equipment and approaches are
used in the computerized simulation of SMR EPZ
detection to guarantee the (pre-incident) integrity and
(existing) resilience of the surrounding areas. The
following instruments and methods could be applied
in this situation. Various studies have been done in line
with the EPZ size determination and most researchers
have focused on the “NEI methodology”; this is a
generic method that can be adopted and used by the
SMR developers and plant operating license applicants
for establishing design specific and site-specific technical
basis for SMR-appropriate EPZ [59] . The NEI proposed
methodology stems from the NUREG-0396 sizing rationale
and was utilized to determine the generic distance
for plume exposure EPZ for existing plants [23] . In 2018,
the SMR Regulators’ Forum worked on a two-year
project to identify general principles that govern the
size of the EPZ of SMRs. In addition to the EPZ, the
group also identified principles that govern the siting
criteria of SMRs with novel design considerations [46] .
The IAEA working group reviewed the IAEA methodology
in establishing EPZ size and found it sufficient in
their own scope to be used to determine the size of the
EPZ around a SMR [60]. The IAEA identified four
different regions around a nuclear power plant that
require preparation of emergency response planning
procedures in advance - two emergency planning zones
(EPZs) and two emergency planning distances (EPDs).
These regions are described in the Table 6 below [42] .
The IAEA also suggested distances for each EPZ as
shown in the subsequent Table 7.
The SMR working group gives detailed information regarding
each of the steps involved in the generalized
approach to determine EPZ distances summarized in
the flow chart in Figure 4. The detailed description describes
differences that may or may not exist among
member states and factors that must be considered in
each step of the approach. The steps are explained and
broken down chronologically in the following Table 8.
Emergency zone/distance
Precautionary Action Zone
(PAZ)
Urgent Protective Action
Planning zone (UPZ)
Extended Planning Distance
(EPD)
Ingestion and Commodities
Planning Distance (ICPD)
Description in summary
In this zone, comprehensive arrangements are made at the preparedness stage to
notify the public and have the public start to take urgent protective actions and
other response actions within one hour of the declaration of a General Emergency
by the shift supervisor of the nuclear power plant.
In this zone, comprehensive arrangements are made at the preparedness stage to
notify the public and have the public start to take the urgent protective actions and
other response actions within about one hour of the declaration of a General
Emergency by the shift supervisor of the nuclear power plant.
The distance to which arrangements are made at the preparedness stage so
that upon declaration of a General Emergency: (a) instructions will be provided
to reduce inadvertent ingestion; and (b) dose rate monitoring of deposition
conducted to locate hotspots following a release which could require evacuation
within a day and relocation within a week to a month.
The distance to which arrangements are made at the preparedness stage so
that upon declaration of a General Emergency instructions will be provided to:
(a) place grazing animals on protected (e.g. covered) feed, (b) protect drinking water
supplies that directly use rainwater (e.g. to disconnect rainwater collection pipes),
(c) restrict consumption of non-essential local produce, wild-grown products (e.g.
mushrooms and game), milk from grazing animals, rainwater and animal feed, and
(d) stop distribution of commodities until further assessments are performed.
Tab. 6.
EPZ zones/distances [60]
Vol. 69 (2024)