atw 2015-01


atw Vol. 60 (2015) | Issue 1 ı January


| | 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


6 Proven technologies 26 Inherent protection of


| | 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


7 Assessment of Design Safety 27 Suppression of reactor power


8 Construction and operating


46 Radioactive waste processing

& storage systems

47 Radiation protection


28 Reactor core, etc. 48 Fuel handling & storage


9 Decommissioning 29 Fuel rod and assembly 49 Auxiliary systems

10 Postulated initiating events 30 Protection against flow


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


14 External events design bases 34 Diverse protection system 54 Sodium heating system

15 Fire protection 35 Reactor coolant boundary 55 Protection against sodium


16 Design bases for environmental


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


19 calibration / test / inspection/


20 Startup, shutdown, and low

power operation

58 Limiting conditions for


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

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