Flexible Conversion Ratio Fast Reactor

Transcription

1 American Nuclear Society Student Conference March 29-31, 2007, Oregon State University, Corvallis, OR Flexible Conversion Ratio Fast Reactor Anna Nikiforova Massachusetts Institute of Technology Center for Advanced Nuclear Energy Systems DOE support through U-NERI program is acknowledged 1

2 Outline FCR project objectives Lead-cooled concept Coolant overview Design approach Reactor physics performance Thermal hydraulic performance Future work Conclusion 2

3 Project Objectives 1. Develop a feasible design for a flexible conversion reactor system for time dependent management of actinides Conversion ratios (same plant) CR near zero to transmute legacy waste CR near unity to operate in sustainable closed cycle Reactor coolants to be explored Lead 2. Compare performance with GFR and liquid salt cooled reactor (under development at MIT) and sodium burner (under development at ANL) 3

4 Project Challenges High power 2400 MW reactor Decay heat removal Tight vessel geometry Self-controllability Large reactivity swing of CR=0 High operating temperature materials 4

5 Why Go Lead? High boiling point (1737 C) and high heat of vaporization No phase change No need to pressurize No chemical reaction with CO 2, air or water Fast spectrum Low neutron absorption 5

6 Lead-Cooled Reactor Materials evolution 1 Yesterday Stainless steel (SS316, SS 304) Maximum temperature 550 C Maximum velocity 2 m/s Very rapid corrosion in lead-coolant environment when the temperatures exceed 550 C 2 Today T-91 and other exotic alloys Max. temperature C Max. velocity 3 m/s Self -passivating alloys in lead-coolant environment due to formation of oxide layers. Composite coatings are also under development. 3 Tomorrow Oxide Dispersion -Strengthened Steels (ODS) Maximum 700 C Excellent corrosion resistance for very high operational temperatures 6

7 Design Approach Attributes One plant two core types Metallic fuel Pool-type Dual-free-level design RVACS Coupled to S-CO 2 cycle Viability Issues Control of corrosion Seismic safety S-CO 2 side performance Passive decay heat removal for high power rating From Nucl. Tech., Sept issue 7

8 Reactor Physics Performance Reactor analysis performed using MCNP4C and MCODE2.2 by E. Shwageraus CR=1 core 3-regions core fueled with metallic U-TRU-Zr (no blankets) (TRU = discharged LWR fuel with 50MWd/kg burnup.) Zr content adjustment to reduce power peaking 2200 EFPD (6.5 years at 90% capacity factor) maximum radial peaking is 1.21 at MOL core average burnup of 100 MWd/kgHM CR=0 core 3-regions core fueled with metallic TRU-Zr (no blankets) 550 EFPD (1.7 years at 90% capacity factor) maximum radial peaking is 1.35 at MOL core average burnup of 400 MWd/kgHM TRU consumption rate is 1282 kg/yr (equivalent to 0.32 kgtru/yr/mwth vs kgtru/yr/mwth of ATW) Doppler coefficient is negative for both cores Reactivity coefficient ratios satisfy ANL self-controllability criteria 8

9 Thermal Hydraulic Performance Peak cladding temperature and maximum velocity below the margin (625 C and 3.0 m/s respectively) 614 C and 2.36 m/s for CR=1 621 C and 2.70 m/s for CR=0 Three-zone orificing was employed to maximize the margin between the limit and the maximum cladding temperature Resultant outlet temperature for both cores is 573 C and power density is 112 kw/l Reactor vessel liner investigated 4 centrifugal pumps RELAP5 model is under development to perform transient reactor TH analysis 9

10 Thermal Hydraulic Performance IHX challenges: High pressure on CO 2 side Limited space within the reactor vessel Temperature constraints Pressure drop constraints to maintain high (45%) efficiency on the S-CO 2 side to retain reasonable pumping power and velocity limits on the primary side Large difference in the heat transfer coefficient between lead and CO 2 4 IHX 600 MWth each Tube-and-shell kidney shaped Enhanced heat transfer using helical ribs on CO 2 side enhancement in heat transfer by a factor of 1.41 provided same CO 2 pressure drop reduction in lead pressure drop due to more compact IHX Heatric Hybrid considered 10

11 Future Work Transient analysis of the reactor system using RELAP5 including, but not limited to: Station blackout Loss of pumping power Reactivity insertion Time-dependent investigation of the fuel cycle using REBUS3 code for fast reactor neutronic analysis TRU content management Time-dependent power distribution k-effective evolution with different cycle patterns Heatric Hybrid evaluation RVACS evaluation Comparison of lead-cooled FCR reactor performance with GFR and liquid salt cooled reactor and sodium burner 11

12 Conclusion Reactor physics analysis of the FCR design was completed and feasibility established. Steady state thermal hydraulic analysis is nearly completed. Reactor systems transient analysis has been initiated. 12

13 Questions?! I would like to thank my colleagues Prof. Neil Todreas Dr. Pavel Hejzlar Dr. Eugene Shwageraus Robert Petroski Joshua Whitman CJ Fong for their support in preparing this presentation 13

14 Extra RVACS Calculations performed by J. Whitman Natural circulation for decay heat removal Enhancements: Liquid metal bond in the gap between the reactor vessel and the guard vessel Perforated plate in the air gap Dimpled guard vessel wall Achievable heat transfer rate is between 15 and 17 MWth 14

15 Extra Dual-Free-Level Liner in the reactor annulus Lead flows through the IHXs, but before entering the lower plenum region, it is directed through the liner CO 2 in IHX is at high pressure (20 MPa), while lead is at atmospheric pressure Liner prevents the ingress of CO 2 in the core region in case of IHX tube rupture From Nucl. Tech., Sept issue 15

16 Extra IHX portfolio Do / P/D / Dh(Pb) Enhanced 14 mm / 1.23 / mm Gas-side source Lead-side source Single junction Single junction 536 Gas-side sink S mt (t = 20 yrs, T max = 570C) Estimated 50 MPa Tube thickness 2.8 ( t+500 µm) Tube length Pressure drop, CO 2 side 6.10 m 0.65 MPa Pressure drop, lead side ~0.46 MPa Heat transfer coefficient ratio (enhanced/smooth) Power = MW Single junction Lead-side sink

17 Extra Enhanced Heat Transfer High Reynold s number on the CO 2 side (outside of the margin for most correlations developed) Correlations developed by Bergles include a wide range of parameters for enhanced heat transfer inside a duct 17