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XYLENE POWER LTD.

FAST NEUTRON REACTOR SPECIFICATIONS

By Charles Rhodes, P.Eng., Ph.D.

PRELIMINARY POWER FNR SPECIFICATION SHEET
This specification sheet summarizes the results of the FNR Design set out at www.xylenepower.com/FNR%20Design.htm

PURPOSE: Provide a modular power FNR that can supply thermal power of up to 940 MWt in 1.77 MWt increments. Modules to be factory assembled and truck/rail transportable. To the extent possible use existing readily available materials and technology.

RATED OUTPUT POWER: 820.51 MWt (~ 273.5 MWe) at 15% linear fuel tube swelling

RATED FUEL BURNUP FRACTION / FUEL CYCLE: ~ 15%

FEATURES: Metallic U-Pt-Zr core rods, metallic U-Zr blanket rods, primary sodium natural circulation, intermediate sodium induction pump circulation, passive high temperature fission reaction shutdown, passive cold shutdown on loss of control power, two independent active shutdown systems, few moving parts, 532 active fuel bundles, gamma ray emission sensing for every active fuel bundle, control portion vertical position sensing for every active fuel bundle, independent control portion vertical position control for every active fuel bundle, floating steel liquid sodium pool cover for every fuel bundle, 32 independent secondary heat transport circuits for high heat removal reliability, reactor site sufficiently above local flood level for certain exclusion of flood water from sodium, dry cooling towers for minimum environmental impact.

MODULAR CONSTRUCTION: Reactor is field assembled by connecting together truck and/or rail transportable modules. A fuel bundle inside its lead biosafety transportation container can be transported by a conventional 18 wheel trailer truck. The longest steel beams and pipe sections are less than 20 m in overall length. Some stainless steel field welding is required to achieve gas tight seals around the liquid sodium pool.

SITE: Must have igneous or shale bedrock at 18 m below grade;

SITE: Local water table must always be at least 20 m below grade;

SITE: Must have sufficient natural drainage to ensure no possibility of adverse water table rise or flood water backup;

SITE: Must be suitable for use of dry cooling towers;

SITE: Must have sufficient stored water for fission prodict decay heat removal;

PRIMARY COOLANT: Pure liquid sodium

SECONDARY COOLANT: Pure liquid sodium

TURBINE WORKING FLUID: Pure water

EVAPORATIVE COOLANT: Filtered water

LIQUID SODIUM POOL INSIDE DIMENSIONS: 25.4 m L X 18.4 m W X 13.5 m D

LIQUID SODIUM NOMINAL DEPTH: 12.5 m

PRIMARY LIQUID SODIUM VOLUME: 25.4 m L X 18.4 m W X 12.5 m D = 5842 m^3

PRIMARY SODIUM MASS: 5842 m^3 X 0.927 tonne / m^3 = 5415.5 tonnes

SECONDARY SODIUM VOLUME: ~ 200 m^3

TOTAL SODIUM REQUIREMENT: 5600 tonnes

EXCAVATION CAVITY DIMENSIONS: 35.4 m L X 28.4 m W X 17.5 m D

REACTOR CORE ZONE HEIGHT: 0.35 m

REACTOR CORE ZONE DIAMETER: 10.4 m

REACTOR BLANKET THICKNESS: 1.2 m

REACTOR BLANKET HORIZONTAL OD: 12.8 m

LIQUID SODIUM NEUTRON ABSORPTION GUARD BAND: 2.8 m wide

LIQUID SODIUM POOL THERMAL INSULATION: Low density saw cut lava rock blocks, 3.0 m thick below primary sodium pool bottom and around 4 primary sodium pool walls

SAW CUT LAVA ROCK BLOCK REQUIREMENT:
(31.4 m X 24.4 m X 16.5 m) - (25.4 X 18.4 m X 13.5 m)
= 6332.28 m^3

PRIMARY LIQUID SODIUM POOL SURFACE WORKING TEMPERATURE: 440 deg

PRIMARY LIQUID SODIUM POOL BOTTOM TEMPERATURE AT FULL RATED OUTPUT POWER: 340 deg C

PRIMARY LIQUID SODIUM CIRCULATION: Natural circulation

MAXIMUM PARASITIC HEAT LOSS VIA THERMAL CONDUCTION THROUGH LAVA ROCK: 0.6 MWt

LAVA ROCK CONDUCTED HEAT REMOVAL: Forced air through 1 m wide cooling channel

Air cooled surface area of primary liquid sodium outer wall:
2 (31.4 m X 16.5 m) + 2 (24.4 m X 16.5 m) + (31.4 m X 24.4 m) = 1036.2 m^2 + 805.2 m^2 + 766.16 m^2
= 2607.56 m^2

OUTER POOL WALL SURFACE HEAT FLUX = 600,000 W / 2607.56 m^2
= 230.1 W / m^2

RATED FUEL TUBE WALL TEMPERATURE DROP: 15 C

FUEL TUBE INITIAL DIMENSIONS: 0.500 inch OD, 0.37 inch ID , 6.0 m long

FUEL TUBE DIMENSIONS AT MAXIMUM PERMITTED 15% LINEAR SWELLING: 0.575 inch OD, 0.4255 inch ID

FUEL TUBE GRID: square, 0.625 inch center to center

FUEL TUBE INITIAL MATERIAL: HT-9 (85% Fe + 12% Cr), Mn < 1.5%, C = 0, Ni = 0

FUEL TUBE MATERIAL AT END OF TUBE LIFE: 60% Fe, 24% Cr, 16% Ti

FUEL BUNDLE: fuel tubes + surround bottom grating + surround portion top grating + shroud + 8 corner girders
+ control portion bottom grating + control portion top grating + 4 corner girders + indicator tube + indicator tube diagonals + bottom plate + piston push rod

ACTIVE FUEL BUNDLE WEIGHT: 3.868 tonnes

NUMBER OF ACTIVE FUEL BUNDLES: 532

NUMBER OF FUEL BUNDLE CONTROL PORTION ACTUATORS: 532

NUMBER OF PASSIVE FUEL BUNDLES: 272

NUMBER OF FUEL TUBES PER ACTIVE FUEL BUNDLE: 532

NUMBER OF FUEL TUBES PER PASSIVE FUEL BUNDLE: 556

CORE ROD ALLOY: 70% U-238, 20% Pu, 10% Zr

INITIAL CORE ROD LENGTH: 0.35 m

NUMBER OF CORE RODS: 532 fuel tubes / active bundle X 532 active bundles X 1 core rod / fuel tube = 283,024 core rods

TOTAL CORE ROD WEIGHT: ~ 80 tonnes

TOTAL Pu REQUIREMENT: ~ 16 tonnes

BLANKET ROD ALLOY: 90% U, 10% Zr

BLANKET ROD OD: 8.5 mm

BLANKET ROD LENGTH: 0.60 m

NUMBER OF BLANKET RODS: (4 blanket rods / active fuel tube X 532 active fuel tubes / bundle x 532 active bundles)
+ (5 blanket rods / passive fuel tube X 556 passive fuel tubes / passive bundle X 272 passive bundles)
= 1,132,096 + 756,160
= 1,888,256 blanket rods

INTERMEDIATE HEAT EXCHANGER WALL TEMPERATURE DROP: 10 C

INTERMEDIATE HEAT EXCHANGE TUBE DIAMETER: 0.500 OD, 0.37 inch ID

INTERMEDIATE HEAT EXCHANGE TUBE LENGTH: 6.0 m

INTERMEDIATE HEAT EXCHANGE TUBE GRID: square, 0.75 inch

INTERMEDIATE HEAT EXCHANGE TUBE MATERIAL: Inconel 600

INTERMEDIATE HEAT EXCHANGE TUBE BUNDLE: 16 X 103 = 1648 tubes

INTERMEDIATE HEAT EXCHANGE TUBE BUNDLE HORIZONTAL LENGTH: 3.0 m

INTERMEDIATE HEAT EXCHANGE TUBE BUNDLE HORIZONTAL WIDTH: 12.0 inches

INTERMEDIATE HEAT EXCHANGE MANIFOLD WIDTH: 32.5 inches

INTERMEDIATE HEAT EXCHANGE TUBE BUNDLE CENTRE TO CENTRE SPACING = 1.0 m

NUMBER OF INTERMEDIATE HEAT EXCHANGE BUNDLES: 32

INTERMEDIATE HEAT EXCHANGE DESIGN: baffled, counter flow, single pass

INTERMEDIATE HEAT EXCHANGE SODIUM FLOW: 32 X 0 to 0.25 m^3 / s______________

MAXIMUM TOTAL INTERMEDIATE SODIUM FLOW: 8 m^3 / s

INTERMEDIATE HEAT EXCHANGE BUNDLE EXTERNAL PIPING: 16.0 inch OD, 12.8 inch ID

INTERMEDIATE HEAT EXCHANGER WORKING PRESSURE: 11.5 MPa (test to 18 MPa), SMYS at 36 MPa

REACTOR THERMAL POWER CONTROL: Variable speed secondary liquid sodium pumps control the secondary liquid sodium flow rate through the intermediate heat exchange bundles. At low pump speeds the heat extraction rate is low. At high pump speeds the heat extraction rate is high. The secondary liquid sodium return temperature to the intermediate heat exchange bundle is ~ 320 C to 330 C due to the action of the steam generator PRV. The steam generator must tolerate a wide range of liquid sodium flows.

SECONDARY SODIUM LOOP HIGH TEMPERATURE AT FULL LOAD: 430 C

SECONDARY SODIUM LOOP LOW TEMPERATURE AT FUL LOAD: 330 C

SECONDARY SODIUM LOOP TEMPERATURE DIFFERENTIAL AT FULL LOAD: 100 deg C

STEAM GENERATOR TUBE WALL TEMPERATURE DROP AT FULL LOAD: 10 C

WATER TEMPERATURE IN STEAM GENERATOR: ~ 320 C (608 F)

SATURATED STEAM WORKING PRESSURE IN STEAM GENERATOR: = 11.25 MPa

SECONDARY SODIUM NORMAL WORKING PRESSURE: 11.5 MPa

MAXIMUM ALLOWABLE TRANSIENT STEAM WORKING PRESSURE: 12 MPa

MAXIMUM TRANSIENT INTERMEDIATE SODIUM WORKING PRESSURE: 12 MPa

SECONDARY SODIUM LOOP CIRCULATION PUMPS: 32 X Electric induction (No moving parts), 0.0 - 0.25 m^3 / s _______. These pumps control the rate at which heat is extracted from the reactor and hence indirectly control the reactor thermal power.

SECONDARY SODIUM PIPE FLOW VELOCITY: 0 to 3.2 m / s

SECONDARY SODIUM LOOP PRESSURE CONTROL: Argon injection into each secondary loop expansion tank tracks the steam pressure in the corresponding steam generator

MAXIMUM POSSIBLE STEAM TEMPERATURE (no steam load): 440 C

MAXIMUM POSSIBLE STEAM TEMPERATURE AT FULL LOAD: 420 C

FNR START FUEL AVAILABILITY FROM EXISTING CANDU SPENT FUEL: Sufficient for 12 X 800 MWt FNRs

MATERIAL CONSTRAINT: Fuel tube linear diameter swelling should be kept to less than 15% to maintain the specified reactor output power and fuel bundle safety margin. In this respect use of HT-9 or similar Fe-Cr fuel tube material with low Ni and low C is recommended.

INDIVIDUAL FUEL BUNDLE DISCHARGE TEMPERATURE MONITORING: Uses fuel bundle control portion positioning to keep all fuel bundle primary sodium discharge temperatures the same irrespective of uneven fuel bundle reactivity and uneven fuel tube swelling. As a fuel bundle ages its thermal output power will gradually decrease due to reduced primary liquid sodium flow.

THREE INDEPENDENT FISSION SHUTDOWN MECHANISMS: active fuel bundle red group control portion withdrawal, active fuel bundle black group control portion withdrawal, fission shutdown via material thermal expansion;

MELTDOWN PREVENTION: primary sodium floor cover configured to prevent critical mass formation if a fuel melt down occurs;
 

COMMENT:
The FNR design parameters have been set out in sufficient detail on this web site that a team of competent engineering technologists should be able to proceed with initial CAD drawings.

An important issue is automation of the fuel rod, fuel tube and fuel bundle fabrication and recycling steps as they repeat hundreds of thousands of times per reactor.

The next step is to meet with persons who have hands on experience with high volume 0.5 inch Fe - Cr steel tube production, welding and quality control to identify the provisions that must be made for automated fuel tube and fuel bundle assembly and testing.

3) The reactor fabrication is dominated by proper alloy mixes and automated: fuel rod and fuel tube production, quality control, and testing issues. Each FNR has:
566,048 + 302,464 = 868,512
gas tight fuel tube end plug welds. This welding must be highly automated. The economics of FNRs is entirely dependent on this manufacturing automation.

4) Each intermediate sodium loop is independent and operates at a high pressure. This pressure is controlled by injection of argon into each intermediate loop's expansion tank.

5) FNRs provide the only route to sustainable displacement of fossil fuels.

6) A major near term Ontario political consideration is future FNR siting and related transmission planning.

7) The safety issues are quite different from a water cooled reactor.

8) Moving this project forward likely requires an alliance between an existing 0.500 inch OD steel tube producer, an existing tube type heat exchanger producer and an existing producer of automated tube welding equipment. To be economic the automated weld rejection rate must be very low. Achieving that yield will require good control of the heat exchange manifold casting quality.

8) There are 532 active fuel bundles, each with 532 fuel tubes, of which 244 tubes form the control portion. The active fuel bundle control portions must be positioned to keep each fuel tube bundle's discharge temperature at 440 C. It is important that the control portion positioning systems be independent of each other so that adjacent bundle control system failures are extremely rare.

9) The FNR design must safely tolerate intentional acts of sabotage that might lead to fuel melting. If fuel melting does occur it must not lead to a critical mass accumulating on the primary liquid sodium pool floor.

10) From a safety perspective this power FNR is a collection of 532 X 1.7 MWt reactors inside a common enclosure. The system must be fault tolerant. For safety a fault in one fuel bundle must not prevent safe shutdown of adjacent fuel bundles. Shutdown of the 8 nearest neighbor fuel bundles should make a faulty fuel bundle sub-critical regardless of its control portion position.

11) From a financial perspective the maximum value of one 300 MWe FNR is:
$2 billion in spent CANDU fuel disposal cost savings plus (300,000 kW X $16,000/ kW)
= $2 billion + $4.8 billion
= $6.8 billion

A FNR will likely be a reasonable financial investment provided that the assembly automation issues are resolved with certainty.

This web page last updated September 3, 2017

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