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XYLENE POWER LTD.

FAST NEUTRON REACTOR SPECIFICATIONS

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

INTRODUCTION:
Elsewhere on this website Fast Neutron Reactors (FNRs) have been identified as the primary source of energy for meeting mankind's future energy needs. This web page identifies the Specifications for a power FNR capable of electrically displacing a CANDU 6E Nuclear Reactor.
 

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 electrically replace half a CANDU 6E nuclear reactor. Modules to be factory assembled and truck/rail transportable. To the extent possible use existing readily available materials and technology.

RATED OUTPUT POWER: 962 MWt (~ 320 MWe) at 15% linear fuel tube swelling

MAXIMUM FUEL BURNUP FRACTION / FUEL CYCLE: ~ 20%

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, control rod cold shutdown, no high temperature moving parts except for mobile fuel bundles, gamma ray emission sensing for every active fuel bundle, discharge temperature sensing for every active fuel bundle, fuel bundle position sensing for every mobile active fuel bundle, independent positioning for every mobile active fuel bundle, floating steel liquid sodium pool cover for every fuel bundle, 32 independent secondary heat transport circuits for extremely high reliability heat removal, reactor site in naturally dry bedrock sufficiently above local water table for certain liquid sodium containment and water exclusion, natural draft cooling towers for minimum marine environmental impact.

MODULAR CONSTRUCTION: Reactor is field assembled by bolting 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 water table rise or flood water backup;

SITE: Must be suitable for use of 130 m tall natural draft cooling towers;

SITE: Must have sufficient year round continuously available cooling water to remove 551 MWt by water evaporation;

PRIMARY COOLANT: Pure liquid sodium

SECONDARY COOLANT: Pure liquid sodium

TURBINE WORKING FLUID: Pure water

EVAPORATIVE COOLANT: Filtered lake 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: _______

SECONDARY SODIUM MASS: ________

TOTAL SODIUM REQUIREMENT: ______

EXCAVATION CAVITY DIMENSIONS: 35.4 m L X 28.4 m W X 18.5 m D

REACTOR CORE ZONE HEIGHT: 0.35 m

REACTOR CORE ZONE DIAMETER: 10.4 m

REACTOR HORIZONTAL BLANKET THICKNESS: 1.2 m

REACTOR VERTICAL BLANKET THICKNESS: 2 X 0.6 m = 1.2 m

REACTOR HORIZONTAL BLANKET OD: 12.8 m

LIQUID SODIUM NEUTRON ABSORPTION GUARD BAND: 2.8 m

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 MAXIMUM WORKING TEMPERATURE: 445 deg

PRIMARY LIQUID SODIUM BOTTOM TEMPERATURE AT FULL RATED OUTPUT POWER: > 350 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

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

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 top grating + shroud + 4 shroud girders
+ control bundle bottom graiting + control bundle top grating + 4 girders + wall + indicator tube

FUEL BUNDLE WEIGHT: ~ 4 tonnes

NUMBER OF ACTIVE FUEL BUNDLES: 532

NUMBER OF CONTROL BUNDLE VERTICAL ACTUATORS: 532

NUMBER OF PASSIVE FUEL BUNDLES: 272

NUMBER OF FUEL TUBES PER FUEL BUNDLE: 544

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

INITIAL CORE ROD LENGTH: 0.35 m

NUMBER OF CORE RODS: 544 fuel tubes / active bundle X 532 active bundles X 1 core rods / fuel tube = 289,4408

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 544 active fuel tubes / bundle x 532 active bundles)
+ (5 blanket rods / passive fuel tube X 544 passive fuel tubes / bundle X 272 passive bundles)
= 1,157,632 + 739,840
= 1,897,472 blanket rods

FIXED TO HERE

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

INTERMEDIATE HEAT EXCHANGE TUBE LENGTH: 6.1 m

INTERMEDIATE HEAT EXCHANGE TUBE GRID: square, 0.75 inch

INTERMEDIATE HEAT EXCHANGE TUBE MATERIAL: Inconel 600

INTERMEDIATE HEAT EXCHANGE TUBE BUNDLE: 16 X 104 = 1664 tubes

INTERMEDIATE HEAT EXCHANGE TUBE BUNDLE HORIZONTAL LENGTH: 3.45 m

INTERMEDIATE HEAT EXCHANGE TUBE BUNDLE HORIZONTAL WIDTH: 12 inches

INTERMEDIATE HEAT EXCHANGE MANIFOLD WIDTH: 24 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 PIPE FLOW: 32 X 0 to 0.40 m^3 / s______________

MAXIMUM TOTAL INTERMEDIATE SODIUM FLOW: 14 m^3 / s______________

INTERMEDIATE HEAT EXCHANGE BUNDLE EXTERNAL PIPING: 12.75 inch OD, 10.126 inch ID

INTERMEDIATE HEAT EXCHANGER WORKING PRESSURE: 11.25 MPa (test to 18 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 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: 430 C to 445 C

SECONDARY SODIUM LOOP LOW TEMPERATURE: 320 C to 335 C

SECONDARY SODIUM LOOP TEMPERATURE DIFFERENTIAL: 125 deg C to 95 deg 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 MAXIMUM WORKING PRESSURE: 12 MPa

SECONDARY SODIUM LOOP CIRCULATION PUMPS: 32 X Electric induction (No moving parts), 0.0 - 0.35 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 7 m / s_________

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

MAXIMUM STEAM TEMPERATURE (no steam load): 445 C

FNR START FUEL AVAILABILITY FROM EXISTING CANDU SPENT FUEL: Sufficient for 12 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-Ti-Mn fuel tube material is recommended.

INDIVIDUAL FUEL BUNDLE DISCHARGE TEMPERATURE CONTROL: Uses fuel bundle 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 FISSION SHUTDOWN MECHANISMS: control bundle withdrawal, fission shutdown via material thermal expansion, fission shutdown via meltdown preventer.
 

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. With respect to the intermediate heat exchange bundle headers the fabrication steps are similar to fabrication of blocks and heads for large diesel engines.

2) The intermediate heat exchange manifold production technology is similar to production of diesel engine blocks and engine heads;

3) The reactor production is dominated by proper alloy mixes and automated: fuel rod and fuel tube production, quality control, and testing issues. Each FNR has over 894,048 gas tight fuel tube 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) The safety issues are quite different from a water cooled reactor. 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) 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 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 544 fuel tubes, of which 244 form the control bundle. The control bundles must be positioned to regulate each fuel tube bundle's discharge temperature at 445 C. It is important that the control bundle positioning systems be independent of each other so that adjacent 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 sodium pool floor.

10) From a safety perspective this power FNR is a collection of 532 X 1.8 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 the faulty fuel bundle sub-critical regardless of its control bundle position.

11) From a financial perspective the value of one FNR is:
$2 billion in spent CANDU fuel disposal cost savings plus (300,000 kW X 16$ / kW)
= $4.8 billion + $2 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 March 16, 2017

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