Design Study of Minor Actinide Bearing Oxide Fuel Core for - PowerPoint PPT Presentation

The 10th OECD/NEA P&T Meeting Mito, Japan 6-10 October 2008 Design Study of Minor Actinide Bearing Oxide Fuel Core for Homogeneous TRU Recycling Fast Reactor System S. Ohki, T. Ogawa, M. Naganuma, T. Mizuno Japan Atomic Energy Agency (JAEA) S. Kubo The Japan Atomic Power Company (JAPC) 1

Contents 1. Introduction 2. Concept of FBR cycle system in FaCT Project 3. TRU composition in the LWR-FBR transition stage 4. Effect of TRU on FBR core and fuel design 5. Design study for MA bearing fuel core � The reference core concept � Design conditions � Core characteristics and necessary core design modifications � MA transmutation performance � Effect on fuel decay heat 6. Conclusion 2

Introduction FBR development program in Japan FS (1999-2005) FaCT Project (2006-2015) Feasibility Study on Fast Reactor Cycle Technology Commercialized Fast Development Project Reactor Cycle System - Clarification of several promising - Establishment of the most prominent candidates for FBR cycle system FBR cycle system technologies The reference concept ◆ The reference core concept: Commercial JSFR MOX fuel core FBR cycle “High internal system conversion” type ◆ TRU recycling mode: Homogeneous 3 JSFR: Japan Sodium-cooled Fast Reactor

4 Concept of FBR cycle system in FaCT Project Homogeneous TRU Recycling

Typical Japanese nuclear installed capacity 70 70 y y t t C apaci C apaci 60 60 After 2030: 58 GWe 50 50 ed ed New New LW Rs LW Rs Exi Exi sti sti ng ng G W e) G W e) constant. 40 40 ( ( 60 60 years) years) l l LW R s LW R s al al nst nst ( ( l l i i f f eti eti m e m e Exi Exi sti sti ng ng 30 30 ( ( extensi extensi on on I I LW R s LW R s ear ear 20 20 60 60 years) years) ( ( 40 40 years years N ucl N ucl operati operati on) on) FBRs FBRs 10 10 0 0 1960 1960 1980 1980 2000 2000 2020 2020 2040 2040 2060 2060 2080 2080 2100 2100 Fi Fi scal scal Year Year After 2050 : 1-GWe LWR replace with FBR / year ◆ TRU composition will change dynamically in the LWR-FBR transition stage. 5

MA content in the LWR-FBR transition stage � MA content in the fuel will vary from 1 wt% to approximately 5 wt%. � Two representative TRU compositions were selected for core design study: � FBR multi-recycle composition � LWR spent fuel composition An example of MA content change after the start of FBR deployment in 2050 6

� FBR multi-recycle composition 241 Am 242m Am 243 Am 244 Cm 245 Cm 238 Pu 241 Pu 242 Pu 237 Np 239 Pu 240 Pu � LWR spent fuel composition - Conditions of LWR spent fuel Reactor type: ALWR, Burnup: 60 GWd/t, Storage period: 40 years - Am and Cm were recovered separately from Pu and Np. [Pu + Np] [Am + Cm] 240 Pu 241 Pu 242 Pu 237 Np 238 Pu 239 Pu 241 Am 242m Am 243 Am 244 Cm 245 Cm - Am and Cm were blended to Pu and Np so that the total MA content in heavy metal would be 3 wt% . (typical content; the first design target) 7

Effect of TRU on FBR Core design core and fuel design ◆ Improvement of burnup characteristics Pu recovered from (burnup reactivity, breeding ratio, power LWR spent fuel mismatch) （degraded） ◆ Influence on safety-related reactivity coefficients (sodium void reactivity, Doppler coefficient) Np Fuel design ◆ Increase of inner gas pressure by Am helium production ◆ Reduction of linear power limit Creation cf. Naganuma, et al., this conference 238 Pu Fuel fabrication and transport ◆ Increase of fresh-fuel decay heat 244 Cm 8

＜ JSFR MOX Fuel Core ＞ “ High Internal Conversion” type core Large fuel pin diameter ( 10.4 mm ) Shielding Inner core (Zr-H) Shielding Increasing fuel volume fraction Outer core (Steel) Increasing internal conversion rate Reducing the amount of blanket Control rod (Primary) Radial Control rod Long Increasing total blanket (Back-up) operation average discharge cycle length burnup (including Core configuration of large- (26.3 month blanket) scale HIC type core (1500 MWe) (800 d)) (90-115 GWd/t) Breeding ratio: 1.03 ~ 1.1 Economical advantages 9

Design conditions for MOX fuel core in the FaCT Project � Safety and Reliability • Sodium void reactivity: less than 6$ • Core specific power: more than 40 kW/kg-MOX • Core height: less than 100 cm • Recriticality-free: FAIDUS type subassembly � Sustainability ( waste management, efficient utilization of nuclear fuel resources ) Current interest • MA contents in the fuel: from 1 to 5 wt% • Breeding ratio: 1.03~1.1 (for low breeding core) 1.2 (for high breeding core) 10

Development Targets for MOX fuel core in the FaCT Project (Continued) � Economic Competitiveness • Operation period: more than 24 months • Average discharge burnup for driver fuel: 150 GWd/t for whole core including blanket: 80 GWd/t (for low breeding core) 60 GWd/t (for high breeding core) � Nuclear Non-Proliferation • Low decontaminated fuel • Options to limit the generation of high-grade Pu 11

Other design conditions for large-scale MOX fuel core � Plant conditions • Power output : 1500 MW e / 3530 MW t • Coolant temperature (outlet / inlet): 550 o C / 395 o C • Shielding region diameter: less than about 7.0 m � Thermal hydraulic condition • Maximum cladding mid-wall temperature: 700 o C • Bundle pressure drop: less than about 0.2 MPa � Fuel integrity limits • Maximum linear power: less than about 430 W/cm • CDF (steady state): less than 0.5 • Maximum fast neutron fluence (E>0.1 MeV): less than about 5 × 10 23 n/cm 2 12

Results of MA bearing fuel core design MA bearing Item Reference core fuel core FBR multi-recycle LWR spent fuel TRU Composition (MA: 1 wt%) (MA: 3 wt%) Core height [cm] 100 100 Axial blanket thickness 20 / 20 15 / 20 (upper / lower) [cm] Gas plenum length 100 / 1100 100 / 1150 (upper / lower) [mm] Pu enrichment (IC / OC) [wt%] 18.2 / 20.6 19.6 / 22.1 Burnup reactivity [%dk/kk’] 2.5 1.8 Breeding ratio 1.1 1.1 Sodium void reactivity (EOEC) [$] 5.2 5.9 The HIC type core enables to accept the typical MA containing fuel (up to 3 wt% of MA content) with slight modifications of 13 core specification.

MA transmutation rate during the LWR- FBR transition stage 50 � MA transmutation M A transm utation rate [% ] rate is about 40 30~40 %/fuel life if the MA content in 30 fresh fuel is 3~5 wt%. 20 � The transmuted MA amount corresponds 10 to the MA from 3~4 LWRs of the same 0 reactor power. 2050 2055 2060 2065 2070 2080 2120 2160 2200 Year MA transmutation rate after the start of FBR deployment in 2050 14

Fresh-fuel decay heat during the LWR-FBR transition stage (an example) 10 � The present results Decay heat of fresh fuel [W/kg-HM] Others 9 have enough Pu-238 8 allowance to the Am-241 7 Cm-244 tentative upper limit 6 (20 W/kg-HM). 5 4 � If the recycle system 3 is designed not to 2 concentrate the heat 1 0 source nuclides on 2050 2055 2060 2065 2070 2080 2120 2160 2200 particular fuel, the Year actinide management Fresh-fuel decay heat after the start of could be feasible. FBR deployment in 2050 15

Conclusion � In the FaCT project, conceptual design studies of sodium-cooled MOX fuel core for JSFR have proceeded with focusing on the TRU composition change during the reactor transition stage from LWRs to FBRs. � The reference “high internal conversion” type core enables to accept a typical MA containing fuel with slight modifications of core specification. � The MA transmutation rate is found to be about 30~40 % per fuel life if the MA content in fresh fuel is 3~5 wt%. � The homogeneous TRU recycling has the advantage that it can provide a feasible solution to the increase of fresh-fuel decay heat due to the source nuclides ( 244 Cm, 238 Pu, etc.). 16

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＜ JSFR MOX Fuel Core ＞ Fuel Assembly with Inner Duct Structure (FAIDUS) Shield Shield Upper Upper - FAIDUS has inner duct installed at a blanket blanket Molten fuel flow Molten fuel flow corner, and a part of upper shielding Core Core element is removed. - At CDA (Core Disruptive Accident), Lower Lower molten fuel enters the inner duct blanket blanket channel and goes out into the Inner duct Inner duct Gas Gas outside through the upper shielding. plenum plenum FAIDUS has superior performance for discharge of molten fuel to prevent compaction of it. 18