atw - International Journal for Nuclear Power | 2.2024

54
Environment and Safety
In 2015, NuScale Power developed a method for
establishing the technical basis for plume exposure EPZ
at NuScale SMR facilities and drafted a Licensing Topic
Report (LTR), however this method therein described
in this LTR is redacted in the filed version. The LTR
presents the design-specific EPZ sizing method for
the NuScale SMR, and this method is based on the
NEI risk- informed EPZ method and extends it to
address the issue of assessing the appropriate accident
sequences to be considered [61] . A safety evaluation of
this report was performed later in 2022 by the
USNRC and subsequently, the LTR was approved by
the USNRC [62] .
The criteria for determining the EPZ for SMRs is
typically defined by regulatory authorities and
considers various factors to ensure the safety and protection
of the public in the event of an emergency.
Some of the criteria and corresponding approaches
that are commonly considered for determining the
EPZ for SMRs are shown in the following Table 9 [63] .
Several researchers have also worked on EPZ methodology
for SMRs, and their work is summarized in the
following Table 10 and 11.
Criteria
Safety Analysis
System analysis
Accident Analysis
Atmospheric
Dispersion Models
Atmospheric conditions
Dose figure of merit
Approach
Deterministic or Probabilistic
Reference SMR consideration
Worst case scenario
Diffusion of Plume
Site specific, plant specific
conditions plus atmospheric
stability classes
Total Effective Dose Equivalent
(TEDE)
Tab. 9.
Guiding criteria for EPZ determination methods [63]
Author (s) and Title Year Code Reactor type Methodology Main area of focus
K. Kim et al,
A study for establishment
of Korean SMR EPZ Based
on US SMR Approach [64], [65] 2021 MACCS2 SMART NEI EPZ setup
methodology.
PSA of source term
categories
J.C. de la Rosa Blul,
Determination of
Emergency Planning Zone
Distances and scaling based
criteria for downsized
nuclear power plants [63] 2021 N/A iPWR SMR Scaling based criteria
Use of plant specific data
for dose consequence
calculation
Inverse method of extrapolating
EPZ distances of
reference, large NPP down
to the SMR
Plume pathway and it focused
on accident analysis and PSA
Comparison of radioactive
releases from a large reactor
and a small modular reactor
T.S. Carless et al,
Risk and regulatory
con siderations for small
modular reactor emergency
planning zones based on
passive decontamination
potential [66] 2018 RASCAL
Monte Carlo
simulations
iPWR
Surry
AP1000
Radionuclide Inventory
and Plant specifications
Decontamination factors
in containment
Atmospheric dispersion
This study focused on
comparison of radioactive
release from different reactor
types and their overall impact
to the environment
U.S. NRC
Performance-based
emergency preparedness
for SMRs, Non-Light-Water
Reactors, and Non-Power
Production or utilization
facilities [67] 2020 N/A SMR
Non LWR
D.W. Hummel et al.
Radiation dose consequences
of postulated
limiting accidents in small
modular reactors to inform
emergency planning zone
size requirements [68] 2019 ADDAM code HTGR
MSR
LFR
iPWR
Regulatory guide
Radiation dose
consequences
Identifies methods and procedures
the staff of the USNRC
considers acceptable for SMR to
demonstrate compliance with
performance-based emergency
preparedness requirements.
Radiation dose conse quences
arising from limiting accidents
of various types of SMRs and
study the dispersion of radionuclides
to the atmosphere
H. Ding et al.
Development of Emergency
Planning zone for high
temperature gas-cooled
reactor [55] 2017 MACCS-
MELCOR
Accident
Consequence
Code System
HTR-PM
Based on
NUREG-0396 RG1.145
The principles that should be
applied during EPZ development
are deter mined by considering
regulations and practice.
the methodology follows
NUREG-0396
Ausgabe 2 › März