atw Vol. 60 (2015) | Issue 1 ı January
ENERGY POLICY, ECONOMY AND LAW 28
| | Fig. 1.
Strategy of GSR Development for SFR.
Art. Title Art. Title Art. Title
1 Definition 21 Use of qualified equipment 41 I&C system
2 Radiation Protection 22 Human factors 42 Electric power system
3 Defense-in-Depth 23 Prevention of harmful effects
between systems
4 Interfaces of safety with
security and safeguards
5 Physical Protection / Safeguards
24 Protection against sodium
reactions
6 Proven technologies 26 Inherent protection of
reactor
| | Tab. 1.
General Safety Requirements (Articles of Technical Standards) for SFR.
43 Control room, etc.
44 Alarm devices, etc.
25 Reactor design 45 Optimization of radiation
protection
7 Assessment of Design Safety 27 Suppression of reactor power
oscillation
8 Construction and operating
experiences
46 Radioactive waste processing
& storage systems
47 Radiation protection
provision
28 Reactor core, etc. 48 Fuel handling & storage
facilities
9 Decommissioning 29 Fuel rod and assembly 49 Auxiliary systems
10 Postulated initiating events 30 Protection against flow
blockage
50 Power conversion system
11 Design bases accidents 31 Reactivity control system 51 Emergency response facilities
and equipment
12 Design extension conditions 32 Reactor protection system 52 Intermediate cooling system
13 Safety classes and standards 33 Use of computerized system 53 Liquid sodium handling
system
14 External events design bases 34 Diverse protection system 54 Sodium heating system
15 Fire protection 35 Reactor coolant boundary 55 Protection against sodium
freezing
16 Design bases for environmental
effects
36 Reactor cooling system 56 Purification control of cover
gas and supply
17 Reliability 37 Overpressure protection 57 Operating experiences and
safety research
18 Sharing of facilities 38 Residual heat removal
system
19 calibration / test / inspection/
maintenance
20 Startup, shutdown, and low
power operation
58 Limiting conditions for
operation
39 Ultimate heat sink 59 Initial tests
40 Reactor containment, etc.
new requirements to be added, we
have referenced the international documents
like IAEA SSR-2/1, Safety Design
Criteria of GIF and draft version
of SFR GDC under development by
ANS. Fukushima action items and applicability
of Risk Informed Regulation(RIR)
are also considered. Utilizing
this strategy and process, we have
developed a draft version of SFR GSR
containing 59 articles. The title of the
articles are listed in Table 1.
3. Development of OPT for
SFR reactivity control
safety function
The OPT is a top-down method with a
tree structure for each DID level describing
objectives and barriers, safety
function, challenges to maintain
safety functions, mechanisms of safety
function degradation, and provisions
for each degradation or failure mechanisms
to maintain safety functions.
Reference [2] describes conceptually
how to apply this methodology to development
of safety requirements for
innovative reactors, specifically for
the modular high temperature gas
cooled reactors. In general, we have
three safety functions to fulfill the
safety objectives, i.e., control of reactivity,
core heat removal and containment
integrity. Among these three
safety functions, we have developed
the OPT for the safety function of “reactivity
control”. Because the design of
PGSFR is not mature yet, we have developed
the OPT modelling the KA-
LIMER-600 [4] reactor which is conceptually
designed by KAERI and is an
SFR of 600 MWe size. OPT is a qualitative
methodology whose development
relies mainly on experiences of
experts using the design documents
like probabilistic safety assessment report.
Because the SFR GSR we are developing
is a general one which should
not be reactor or design specific, we
have developed the OPT for KALIMER
even if the target reactor to apply the
GSR in reviewing is the PGSFR. The
detailed description of the system is
not included in this paper since it is not
necessary to understand the developed
OPT. Example of the Level 3
OPT we have developed for the safety
function of “reactivity control” is
shown in Figure 2.
In Figure 2, safety function means
the essential function necessary to ensure
the safety objectives by maintaining
DID and barrier integrity. Challenge
is the phenomenon which
threatens the successful achievement
of the safety function and the possible
challenges to the safety function
Energy Policy, Economy and Law
Assessment of General Safety Requirements for SFR ı Namduk Suh, Moohoon Bae, Yongwon Choi, Bongsuk Kang and Huichang Yang