Responses to Small Break Loss of Coolant Accidents for SMART

Conference · Thu Jul 01 04:00:00 EDT 2004

OSTI ID:21160676

Bae, Kyoo Hwan; Kim, Hee C; Chang, Moon H; Zee, Sung Q; Kim, Si-Hwan ^[1]; Lee, Un-Chul ^[2]

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1. Korea Atomic Energy Research Institute (KAERI), 150, Deokjin-dong, Yuseong-gu, Daejeon, 305-353 (Korea, Republic of)
2. Seoul National University (SNU) San 56-1, Sillim-dong, Kwanak-gu, Seoul, Korea 151-742 (Korea, Republic of)

The SMART NSSS adopts the design characteristics of containing most of the primary circuit components, such as the reactor core, main coolant pumps (MCPs), steam generators (SGs), and N{sub 2} gas pressurizer (PZR) in a single leak-tight Reactor Pressure Vessel (RPV) with a relatively large ratio of the primary coolant inventory to the core power compared to the conventional loop-type PWR. Due to these design characteristics, the SMART can fundamentally eliminate the possibility of Large Break Loss of Coolant Accidents (LBLOCAs), improve the natural circulation capability, and assure a sufficient time to mitigate the possibility of core uncover. Also, SMART adopts inherent safety improving features and passive engineered safety systems such as the substantially large negative moderator temperature coefficients, passive residual heat removal system, emergency core cooling system, and a steel-made leak-tight Safeguard Vessel (SV) housing the RPV. This paper presents the results of the safety analyses using a MARS/SMR code for the instantaneous guillotine ruptures of the major pipelines penetrating the RPV. The analysis results, employing conservative initial/boundary conditions and assumptions, show that the safety systems of the SMART basic design adequately remove the core decay heat without causing core uncover for all the cases of the Small Break Loss of Coolant Accidents (SBLOCAs). The sensitivity study results with variable SV conditions show that the reduced SV net free volume can shorten the time for reaching the thermal and mechanical equilibrium condition between the RPV and SV. Under these boundary conditions, the primary system inventory loss can be minimized and the core remains covered for a longer period of time without any makeup of the coolant. (authors)

• Research Organization: American Nuclear Society, 555 North Kensington Avenue, La Grange Park, IL 60526 (United States)
• OSTI ID: 21160676
• Country of Publication: United States
• Language: English

Related Subjects

42 ENGINEERING
AFTER-HEAT REMOVAL
BOUNDARY CONDITIONS
COOLANTS
DESIGN
ECCS
LOSS OF COOLANT
MODERATORS
NATURAL CONVECTION
PIPELINES
PRESSURE VESSELS
PRIMARY COOLANT CIRCUITS
PWR TYPE REACTORS
REACTOR CORES
RHR SYSTEMS
SAFETY ANALYSIS
STEAM GENERATORS
STEELS
TEMPERATURE COEFFICIENT