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XYLENE POWER LTD.

FNR 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 with a thermal power output that is continuously variable from 80 MWt to 1000 MWt. Modules to be factory assembled and truck/rail transportable. To the extent possible use existing readily available materials and technology. Design the nuclear power plant for installation on a property 114 m X 114 m (one square city block) with 20 m wide perimeter roads. Hence the minimum site size including perimeter roads is 154 m X 154 m.

MAXIMUM REACTOR BUILDING HEIGHT ABOVE GRADE: 27.5 m

MAXIMUM DEPTH BELOW GRADE: 19 m

MAXIMUM NATURAL DRAFT COOLING TOWER HEIGHT ABOVE GRADE: 50 m

RATED OUTPUT POWER:
1000 MWt (~ 300 MWe)

AVERAGE PRIMARY SODIUM DISCHARGE TEMPERATURE:
462 deg C at full load
450.5 deg C at no load

FUEL BURNUP FRACTION / FUEL CYCLE:
~ 15%

FEATURES:
Metallic U-Pt-Zr core fuel rods, metallic U-Zr blanket fuel rods, primary sodium natural circulation, secondary sodium induction pump assisted natural circulation, passive high temperature fission reaction shutdown, passive cool shutdown on equipment failure, cold shutdown on loss of station power, two independent safety shutdown systems, few moving parts, 945 active fuel bundles, gamma ray emission and temperature sensing for each mobile fuel bundle, vertical position sensing for each mobile fuel bundle, independent vertical position control for each mobile fuel bundle, floating steel covers for primary liquid sodium pool, 8 independent secondary heat transport/electricity generation subsystems for high heat removal reliability, reactor site sufficiently above local flood level for certain exclusion of flood water from sodium, four independent on-site dry cooling towers for safety and minimum environmental impact, 12 remote cooling towers.

MODULAR CONSTRUCTION:
Reactor is field assembled from truck transportable modules. A fuel bundle inside its biosafety transportation container can be transported by a conventional 18 wheel flat deck truck. Apart from the gantry rail and tracks, the longest steel beams and pipe sections are less than 15.8 in overall length for ease of transport. Deeep penetration stainless steel field welding is required to assemble the primary liquid sodium pool.

SITE:
Must have a bedrock base;

SITE:
Local water table must always be below the bottom of the primary sodium pool;

REACTOR SITE:
Must have sufficient natural drainage to ensure no possibility of flooding; Must be suitable for siting of 4 X 50 m high dry cooling towers;

REMOTE SITES:
There must be 12 remote sites, each 40 m X 40 m for accommodating 50 m high remote cooling towers.

COOLING TOWERS:
Each cooling tower is 25 m in diameter at the base, 17 m in diameter at the throat and is served by 24 inch OD supply and return pipes with variable speed pumped flow control. Each cooling tower has variable air flow dampers for freeze protection.

PRIMARY COOLANT:
Pure liquid sodium

SECONDARY COOLANT:
Pure liquid sodium

TURBINE WORKING FLUID:
Pure water

PRIMARY LIQUID SODIUM POOL INSIDE DIMENSIONS:
20 m diameter X 16.0 m deep

PRIMARY LIQUID SODIUM NOMINAL DEPTH:
15.0 m

PRIMARY LIQUID SODIUM VOLUME:
~ 4712 m^3

PRIMARY LIQUID SODIUM MASS:
4712 m^3 X 0.927 tonne / m^3 = 4368 tonnes

SECONDARY LIQUID SODIUM VOLUME:
~ 200 m^3__________

TOTAL LIQUID SODIUM REQUIREMENT:
~ 4700 ________tonnes

REACTOR CORE ZONE HEIGHT:
~ 0.30 m to 0.60 m

REACTOR BLANKET TOP AND BOTTOM THICKNESS:
1.5 m - 1.8 m

REACTOR BLANKET EDGE THICKNESS:
4 X 21 X (5 / 8) inch = 52.5 inch = 1.3335 m

COOLING ZONE THICKNESS:
42 X (5 / 8) inch = 26.25 inch = 0.66675 m

FUEL TUBE ASSEMBLY MAXIMUM OUTSIDE DIAMETER:
16.6 m

CORE ZONE APPROXIMATE OUTSIDE DIAMETER:
16.6 m - 4.0 m = 12.6 m

GADOLINIUM NEUTRON ABSORPTION SKIRT DIMENSIONS:
Thickness ~ 4 mm _____
Height = ______
Bottom elevation above floor = _______
Diameter = 16.6 m

LIQUID SODIUM POOL THERMAL INSULATION:
Low density fire brick, 2.0 m thick

FIRE BRICK VOLUME REQUIREMENT:
Pi[((12 m)^2 X 18.0 m) - ((10 m)^2 X 16.0 m)]
= 3117 m^3

PRIMARY LIQUID SODIUM POOL SURFACE TEMPERATURE:
460 deg C at full load, 450 deg C at no load

LIQUID SODIUM POOL BOTTOM TEMPERATURE:
340 deg C

PRIMARY LIQUID SODIUM CIRCULATION:
Natural circulation

PARASITIC HEAT LOSS VIA THERMAL CONDUCTION THROUGH FIRE BRICK:
~ 0.13 MWt

BRICK CONDUCTED HEAT REMOVAL:
Forced air through 1 m wide air cooling channel underneath and around the primary sodium pool

Air cooled surface area of primary liquid sodium pool outer wall:
Pi [(12.0 m)^2 + 24 m (18.0 m)]
= Pi [12.0 m (48.0 m)]
= 1809.6 m^2

OUTER POOL WALL SURFACE HEAT FLUX:
= 130,000 W / 1809.6 m^2
= 71.8 W / m^2

RATED CORE FUEL TUBE WALL TEMPERATURE DROP:
8 C

FUEL TUBE INITIAL DIMENSIONS:
0.500 inch OD, 0.035 inch wall, 6.0 m long,
ID = 0.43 inch = 10.922 mm

FUEL TUBE DIAMETERS AT MAXIMUM PERMITTED 15% LINEAR SWELLING:
0.575 inch OD, 0.4945 inch ID

ACTIVE TUBE FILL:
1 core rods, 10 blanket rods

PASSIVE TUBE FILL:
12 blanket rods, 1 spacer rod

FUEL TUBE GRID:
Square, 0.625 inch center to center

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

FIXED FUEL BUNDLE:
fuel tubes + bottom grating + outer shroud + 4 outer corner girders
+ reinforcing diagonal plates + inlet filter + indicator tube

NUMBER OF FUEL TUBES PER FIXED FUEL BUNDLE:
384

NUMBER OF FUEL TUBES PER MOVABLE FUEL BUNDLE:
248

FIXED FUEL BUNDLE MASS:
~ 4 tonnes____

MOBILE FUEL BUNDLE MASS:
~ 3 tonnes____

TOTAL NUMBER OF FUEL BUNDLE POSITIONS:
1689

NUMBER OF ACTIVE FUEL BUNDLES:
945

NUMBER OF MOVABLE ACTIVE FUEL BUNDLES:
464

NUMBER OF FIXED ACTIVE FUEL BUNDLES:
481

NUMBER OF ACTIVE FUEL TUBES:
481 (384) + 464(248) = 184,704 + 115,072
= 299,776 active fuel tubes

THERMAL LOAD / ACTIVE FUEL TUBE:
10^6 kWt / 299,776 active tubes = 3.336 kWt / active fuel tube

NUMBER OF CORE FUEL RODS / FNR:
1 rods / active fuel tube X 299,776 active tubes
= 299,776 core fuel rods

CORE FUEL ROD AT START OF FUEL CYCLE:
9 mm OD X 60 cm long, U-238 = 70%, Pu-239 = 20%, Zr = 10%

70% U-238, 20% Pu, 10% Zr

CORE FUEL BURN-UP:
15% / fuel cycle

CORE ROD ALLOY AT END OF FUEL CYCLE:
62.3% U-238, 12.7% Pu, 10% Zr, 15% fission products

INITIAL CORE ROD OD:
9.00 mm

INITIAL CORE ROD DENSITY:
16.006 gm / cm^3

INITIAL CORE ROD LENGTH:
0.60 m

INITIAL CORE ROD VOLUME:
38,170 mm^3 = 38.170 cm^3

CORE ROD MASS:
38.170 cm^3 / core rod X 16.006 gm / cm^3
= 610.954 gm = 0.610954 kg / core rod

TOTAL CORE ROD MASS:
299,716 core rods X 0.610954 kg / core rod = 183,113 kg
= 183.113 tonnes

PLUTONIUM MASS:
183.113 tonnes X 0.2 = 36.622 tonnes

NUMBER OF PASSIVE FUEL BUNDLES:
516

NUMBER OF PASSIVE FIXED FUEL BUNDLES:
268

NUMBER OF PASSIVE MOVEABLE FUEL BUNDLES:
248

NUMBER OF PASSIVE FUEL TUBES:
268 (384) + 248 (248) = 102,912 + 61,504
= 164,416 passive fuel tubes

NUMBER OF BLANKET FUEL RODS:
= 299,776 active tubes X 10 blanket rods / active fuel tube
+164,416 passive fuel tubes X 12 blanket rods / passive fuel tube
= 2,997,760 + 1,972,992
= 4,970,752 blanket fuel rods

INITIAL BLANKET ROD ALLOY:
90% U, 10% Zr

BLANKET ROD DENSITY:
15.884 gm / cm^3

BLANKET ROD OD:
10.0 mm

BLANKET ROD LENGTHS:
0.350 m, 0.355 m, 0.360 m, 0.365 m, 0.370 m

0.360 m BLANKET ROD VOLUME:
28,274.33 mm^3 = 28.274 cm^3

BLANKET ROD MASS:
28.274 cm^3 X 15.884 gm / cm^3 = 449.1095 gm
= 0.44911 kg

TOTAL BLANKET ROD MASS / REACTOR:
0.44911 kg / rod X 4,970,752 blanket fuel rods
= 2,232,414 kg
= 2,232 tonnes

NUMBER OF COOLING FUEL BUNDLE POSITIONS:
228

NUMBER OF FIXED COOLING FUEL BUNDLE POSITIONS:
112

NUMBER OF MOVEABLE COOLING FUEL BUNDLE POSITIONS:
116

INTERMEDIATE HEAT EXCHANGE BUNDLE WALL TEMPERATURE DROP:
10 C

INTERMEDIATE HEAT EXCHANGE TUBE SIZE:
0.500 OD, 0.065 inch wall

INTERMEDIATE HEAT EXCHANGE TUBE LENGTH:
6.0 m

INTERMEDIATE HEAT EXCHANGE TUBE GRID:
square, 0.70 inch

INTERMEDIATE HEAT EXCHANGE TUBE MATERIAL:
Inconel 600

INTERMEDIATE HEAT EXCHANGE TUBE BUNDLE:
800_______ tubes

INTERMEDIATE HEAT EXCHANGE TUBE BUNDLE MANIFOLD LENGTH:
______

INTERMEDIATE HEAT EXCHANGE BUNDLE TUBED DIAMETERS:
24 inches OD, 38 inch manifold OD and 5.5 inch flange width allowance

INTERMEDATE HEAT EXCHANGER CIRCLE = 18 m diameter. Distance from outer edge of manifold to pool wall = 0.7 m

NUMBER OF SECONDARY SODIUM LOOPS:
56

NOMINAL THERMAL FLUX THROUGH EACH INTERMEDIATE HEAT EXCHANGE BUNDLE:
1000 MW / 56 = 17.86 MWt

NUMBER OF STEAM GENERATORS:
56

NUMBER OF CONDENSATE INJECTION PUMPS:
56

NUMBER OF SECONDARY SODIUM INDUCTION PUMPS:
56

TURBOGENERATORS:
8 X 4 X 5.4 MWe = 8 X 21.6 MWe
8 X 3 X 5.4 MWe = 8 X 16.2 MWe
Total = 56 X 5.4 MWe = 302.4 MWe

INTERMEDIATE HEAT EXCHANGE BUNDLE DESIGN:
counter flow, single pass

MAXIMUM SECONDARY SODIUM FLOW:
56 X (0 to 0.153 m^3 / s = 8.56 m^3 / s_____

SECONDARY SODIUM INDUCTION PUMP THROAT PIPE:
16 inch OD

SECONDARY SODIUM EXTERNAL PRESSURE PIPING:
12.75 inch OD, Schedule 80, 10. ________ inch ID

INTERMEDIATE HEAT EXCHANGE BUNDLE OPERATING PRESSURE:
0.1 MPa gauge, (vent argon and hydrogen at 4.6 MPa, test to 6.9 MPa, material SMYS = 39 MPa at 800 degees K)

REACTOR THERMAL POWER CONTROL:
Variable speed induction sodium pumps control the secondary liquid sodium flow rate through the intermediate heat exchanger and steam generator tubes. At low induction pump flow rates the heat extraction rate is low. At high induction pump flow rates 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.

SECONDARY SODIUM LOOP HIGH TEMPERATURE AT FULL LOAD:
450 C

SECONDARY SODIUM LOOP LOW TEMPERATURE AT FULL LOAD:
330 C

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

STEAM GENERATOR LIQUID TO LIQUID 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:
0.2 MPa absolute

MAXIMUM ALLOWABLE TRANSIENT STEAM WORKING PRESSURE:
11.5 MPa

MAXIMUM SECONDARY SODIUM TRANSIENT WORKING PRESSURE:
4.6 MPa

SECONDARY SODIUM LOOP CIRCULATION PUMPS:
56 X Electric induction (No moving parts), 0.0 - 0.153 m^3 / s _____. These pumps control the rate at which heat is extracted from the reactor and hence indirectly control the reactor thermal power. The normal pumped fluid working temperature is 330 deg C.

SECONDARY SODIUM LOOP PRESSURE CONTROL:
Compressed argon in each secondary sodium loop dump tank keeps secondary sodium in heat transport loop. This argon pressure is contrlled by a liquid sodium level sensor at the top of each secondary sodium loop.

DRY STEAM TEMPERATURE AT NO LOAD:
460 C - 10 C = 450 C

DRY STEAM TEMPERATURE AT FULL LOAD:
450 C - 40 C = 410 C

SATURATED STEAM TEMPERATURE:
320 C

FNR START FUEL AVAILABILITY FROM EXISTING CANDU SPENT FUEL:
Sufficient for 7 _____X 300 MWe FNRs

MATERIAL SWELLING CONSTRAINT:
Fuel tube linear diameter swelling should be kept to less than 15% to maintain the specified reactor output power and fuel bundle safety margins. 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 mobile fuel bundle positioning to keep all fuel bundle primary sodium discharge temperatures the same irrespective of uneven fuel bundle fissionable atom concentration and uneven fuel tube swelling. As a fuel bundle ages its thermal output power will gradually decrease due to reduced primary liquid sodium flow.

FOUR INDEPENDENT FISSION SHUTDOWN MECHANISMS:
Mobile fuel bundle red group withdrawal, mobile fuel bundle black group withdrawal, fission shutdown via fuel thermal expansion, fission shutdown via fuel disassembly.

MELTDOWN PREVENTION:
Mechanical mobile fuel bundle insertion rate and insertion range limits, disassembly of fuel inside sealed fuel tube, shutdown due to local high temperature or local high gamma output, primary sodium floor cover configured to prevent critical mass accumulation if fuel melts.

EARTHQUAKE PROTECTION:
Top surface of primary sodium is not confined. In an earthquake the intermediate heat exchangers move with the pool wall. The fuel assembly remains nearly statioary. Earthquake induced transient liquid sodium level changes of up to 10 m are tolerable without exposing reactor core zone.
Primary liquid sodium waves are partially attenuated by the intermediate heat exchange bundles and the assembly of fuel bundles and gadolinium skirt. The earthquake protection system allows for earthquake induced horizontal pool wall accelerations of up to about 1.25 g._____
 

COMMENTS:
1) 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.

2) 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 rod fabrication, fuel tube and fuel bundle assembly and testing.

3) The reactor fabrication is dominated by proper alloy mixes and automated: fuel rod, fuel tube and fuel bundle production, heat exchange bundle assembly, quality control, and testing issues. Each FNR has over 900,000 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) Moving this project forward likely requires an alliance between an existing 0.500 inch OD steel tube producer, an existing tube and shell 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.

5) There are 945 active fuel bundles of which 464 are movable fuel bundles. The movable fuel bundles must be positioned to keep each movable bundle's full load discharge temperature at 460 C. It is important that the movable fuel bundle position control systems be independent of each other.

6) The FNR design must safely tolerate intentional acts of sabotage intended to cause either fuel melting or prompt neutron criticality. If fuel melting does occur it must not lead to a critical mass accumulating on the primary liquid sodium pool floor. Any approach of the reactor toward prompt neutron criticality must trigger a reactor cool shutdown.

7) From a control and safety perspective this power FNR is a collection of 464 small reactors inside a common enclosure. The system must be fault tolerant. A fault in one movable fuel bundle must not prevent safe shutdown of adjacent fuel bundles. Shutdown of the 4 nearest neighbor movable fuel bundles should make a faulty mobile fuel bundle sub-critical regardless of its insertion position.

8) From a financial perspective the value of one 300 MWe FNR is:
$4 billion in spent CANDU fuel disposal cost savings plus (300,000 kWe X $10,000/ kWe)
= $4 billion + $3.0 billion
= $7.0 billion

9) A FNR will likely be a reasonable financial investment provided that the full automation of the fuel recycling system is resolved.

10) Major near term Ontario political considerations are future FNR siting and related electricity transmission and district heating piping planning.

This web page last updated July 15, 2021

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