ML22271A458
| ML22271A458 | |
| Person / Time | |
|---|---|
| Site: | Orano USA |
| Issue date: | 08/18/2022 |
| From: | Shaw D Orano USA |
| To: | Division of Fuel Management |
| Garcia-Santos N | |
| Shared Package | |
| ML22271A128 | List:
|
| References | |
| A33010, L-2022-DOT-0007 | |
| Download: ML22271A458 (16) | |
Text
Unrestricted Orano 0
Orano NPS SAFETY ANALYSIS CHAPTER 1.5 REPORT PACKAGE PERFORMANCE CHARACTERISTICS Formulaire : PM04-4-MO-6 rév. 03 orano Prepared by FCC3 Checked by Identification : DOS-19-021165-003-NPV Vers. 2.0 Page 1 / 16 Table of contents Status of revision 2
- 1. Purpose 3
- 2. Descriptions and definitions 3
- 3. Performance from the mechanical standpoint 6
- 4. Performance from the thermal standpoint 9
- 5. Performance from the standpoint of radiation protection 11
- 6. Performance from the criticality safety standpoint 12
- 7. Conditions of use 15
- 8. Periodic maintenance programme 15
- 9. Quality assurance programme 16
- 10. References 16 Non-proprietary version
Formulaire : PM04-4-MO-6 rev. 03 Unrestricted Orano Orano NPS Identification : DOS-19-021165-003-NPV Vers. 2.0 Page 2 of 16 Status of revision English French Date Purpose and record of revisions Prepared by / Verified by version version Old reference: DOS-13-00081779-050 0 0 04/2012 First issue 1 1 09/2012 Updated safety criticality performances Inclusion of the potential presence of a maximum of 5 g of glycerine on the fuel 2 2 12/2015 assemblies.
3 3 10/2016 Document re-write New reference: DOS-19-021165-003 I 1.0 1.0 02/2019 Added possibility to define the package as type A I 2.0 04/2019 Addition of Zircaloy-4 cladding
- Update of the applicable regulation, in particular the 2018 IAEA
- Addition of the analysis of ageing mechanisms (§2.7)
- Mechanics in accidental conditions §3.3: addition of the analysis of the variations of the mechanical properties depending on the temperature of half-shells and 2.0 screws; addition of the analysis justifying the absence of half-shells separation See 1st - Thermic in accidental conditions §4.3: addition of sensitivity analyses on thermo-3.0 page fluid 3D models
- Radiation protection §5.2: correction of the drop height in normal conditions of transport
- Sub-criticality §6.2: deletion of the study case without rods spacing in rod boxes (case not authorised anymore)
- Formal changes Non-proprietary version
Formulaire : PM04-4-MO-6 rev. 03 Unrestricted Orano Orano NPS Identification : DOS-19-021165-003-NPV Vers. 2.0 Page 3 of 16
- 1. Purpose The aim of this chapter is to detail the performance characteristics of the FCC3 packages, designed for road, rail or maritime transportation of either fresh fuel rod assemblies or fresh, non-assembled fuel rods, as an IP-2 class or type A package containing fissile material in terms of the regulation in reference [1].
The applicable regulations are based on the design and testing rules in the 2018 edition of the IAEA Regulations, and are listed below:
European Agreement concerning the International Carriage of Dangerous Goods by Road (ADR);
Regulations concerning the International Carriage of Dangerous Goods by Rail (RID);
European Agreement concerning the International Carriage of Dangerous Goods by Inland Waterways (ADN);
International Maritime Dangerous Goods (IMDG) code, from IMO; Order of May 29th, 2009 modified concerning the carriage of dangerous goods by terrestrial Routes (TMD order);
Order of November 23th, 1987 modified concerning the Safety of Shipping, division 411 of the attached regulations (RSN order).
- 2. Descriptions and definitions 2.1. Description of the package The fresh nuclear fuel for use in powering PWR nuclear power plants is made up of fuel rods assembled to form an array. These products need to be transported between various production sites (factories) and/or points of use (nuclear power plants) either in the form of fuel assemblies or in the form of non-assembled rods. The FCC3 package is used for these transport operations.
With a general cylindrical form, the package is shown in the figure below, as it is found during transport, in a horizontal position.
Upper shell Upper shell lifting boxes Lower shell The overall general dimensions of the package are:
Non-proprietary version
Formulaire : PM04-4-MO-6 rev. 03 Unrestricted Orano Orano NPS Identification : DOS-19-021165-003-NPV Vers. 2.0 Page 4 of 16 length = 4931 mm; width = 1145 mm; height = 1217 mm.
The FCC3 packaging is designed for the transportation of the following contents:
fuel assemblies with a nominal active length of 8, 10 and 12 feet. Fuel assemblies with a length of 12 feet may or may not be provided with rod clusters; non-assembled fuel rods with a nominal active length of 8, 10 and 12 feet.
The FCC3 packaging is available in two versions, depending on the content considered:
version 1: for fuel assemblies composed of a 17x17 or 15x15 square fuel rod array or for non-assembled fuel rods grouped in rod boxes (channels),
version 2: for fuel assemblies composed of a 14x14 square fuel rod array (8 or 10-foot).
The rods in either of these versions can be made from Enriched Natural Uranium (ENU) or from Enriched Reprocessed Uranium (ERU).
2.2. Description of the packaging The FCC3 packaging is generally made up of:
a cylindrical, horizontally aligned enclosure, comprising two half-shells linked by flanges in a diametrical plane:
the upper shell is equipped with 4 storage stands each fitted with an upper shell and/or package handling point. At the ends, the plates are fitted with axial shock absorbers; the lower shell comprises reinforcements in the form of radial angle bars, associated with vertical gusset plates and flat bars. The lower shell also includes stringers and angle bars to allow the enclosure to be placed on the ground using metal skids; a metal cradle consisting of two stringers and suspended by means of shock mounts from the lower half-shell. The cradle supports the internal equipment frame when the latter is in the horizontal position; Internal equipment mounted on the cradle and designed to accommodate one of the content types defined in this report. To facilitate its loading it is able to pivot relative to the cradle and thus be placed in the vertical position. It is made up of the following components:
Support frame whose rigid structure in the form of an inverted "T" is designed to hold the contents horizontally. The fabricated part of the frame contains neutron-absorbing resin; a bottom plate screwed to the frame and supporting the fuel assemblies during loading and unloading when the frame is in the vertical position. This bottom plate can be adapted to ensure axial clamping of the assembly by its bottom nozzle; a two-part top plate for closing off the cavities and wedging the contents at the other end. This top plate is adapted to provide axial clamping of the fuel assembly or the control cluster by means of a pad mounted at the centre of the top plate and which bears on the upper nozzle or the hub of the control cluster by means of a threaded rod. In the event that the assemblies are fitted with clusters, shock absorbers are fitted to each of the two top plates; two L-shaped doors containing neutron-absorbing resin. These doors pivot on hinge pins connected to the frame and close to seal off the contents.
Non-proprietary version
Formulaire : PM04-4-MO-6 rev. 03 Unrestricted Orano Orano NPS Identification : DOS-19-021165-003-NPV Vers. 2.0 Page 5 of 16 2.3. Description of the Content 2.3.1. Description of fuel assemblies The various types of assemblies to be transported differ notably by number, diameter and the length of the rods they contain.
To nozzle The outline diagram opposite illustrates the U rgrid composition of a fuel assembly for a PWR fuel Guide tube assembly.
It is made up of fuel rods, in an incomplete square-pitched array - 14x14, 15x15 or 17x17. The array positions without fuel are fitted with tubes, used both as spacers between the end nozzles and guides for the control rods.
Grids are attached to these tubes to ensure the transverse and longitudinal positioning of the fuel Intermediate rods.
grid Lowerg~
Bottom nozzle 2.3.2. Description of non-assembled rods Fuel rods are constituted of zirconium alloy tubular cladding, filled with sintered UO2 uranium oxide pellets and/or fuel pellets composed of a mixture of UO2 and material acting as neutron poison.
The non-assembled rods are grouped together in rod boxes, in the place of assemblies inside the Version 1 FCC3 packagings, which allow the rods of the 12, 10 and 8-foot versions to be transported. The box is filled with full rows of rods. Where a row of fuel rods is incomplete, the row is made up with inert rods or solid steel or Zirconium alloy bars having the same diameter.
2.3.3. Authorised content The authorised content limits the parameters important for safety, which are used in the Safety Analysis Report; in particular:
The isotopic ENU vector (for package type A or IP-2)
The isotopic ERU vector (for package IP-2)
The physical state (in the form of pellets) and chemical form (UO2 and/or mix of UO2 and material acting as neutron poison);
The maximum U235 enrichment rate of 5%;
The maximum density (100% of the theoretical density of UO2);
The cladding material made of M5Framatome or Zircaloy-4; A maximum of 5 g of glycerine may also be present in each of the assemblies.
The presence of desiccant bags is permitted outside of the cavity.
2.4. Containment system In the FCC3 package design, fissile material confinement is provided by the fuel rods cladding and the zirconium alloy welded plugs.
2.5. Isolation system The isolation system for the packaging is provided by the container structure which is made up of the following components:
Non-proprietary version
Formulaire : PM04-4-MO-6 rev. 03 Unrestricted Orano Orano NPS Identification : DOS-19-021165-003-NPV Vers. 2.0 Page 6 of 16 The internal fitting whose components make up two neutron cavities, which help to restrict the neutronic interaction between assemblies or rod boxes and between packages; The neutron-absorbing resin inside the doors and frame; The upper and lower shells, which contribute to restricting interactions between packages; In the case of fissile materials, the isolation system is formed by the following elements:
The physical form of the fissile material: sintered UO2 pellets and/or a mix of UO2 and material acting as neutron poison; The cladding tubes assuring fissile material confinement; During transportation of fuel assemblies:
The fuel assembly structure, which outlines and limits the volume occupied by the fissile material; The completeness of the assemblies, where any missing fissile rods are replaced by inert rods; For the transportation of rods in a rod box, the rod box as well as the axial and longitudinal wedging system.
2.6. Mass balance Maximum authorised weight for the FCC3 package in transport is 4,385 kg.
2.7. Ageing mechanisms It is verified that, through the design of the package model, its periodical maintenance and its conditions of use, the packaging and its internal fittings can be used for a duration of 37 years since the commissioning. The content is not subjected in a significant way to ageing mechanisms over the regulatory duration of 1 year of transport.
- 3. Performance from the mechanical standpoint 3.1. Routine conditions of transport The tie-down configurations are evaluated by numerical calculation to validate the stress levels reached in the outer shells for each tie-down mode and in each direction. The stress levels are cumulative with the unit longitudinal and transverse accelerations due to transportation and demonstrate the absence of damage to the package model. These stresses are used as input data for the fatigue analysis which considers the cumulative stresses associated with transportation, handling and stacking. This study shows that the minimum service life is consistent with the service life of the FCC3 packagings.
The acceptability of the container lifting arrangements is verified in accordance with the RCC-MR code. The results show that the structure meets the criteria for deformation and plastic instability for the weld seams and for the bolts. A fatigue analysis was also performed, showing a cumulative damage well below 1 for the structure and the welds. For the bolts, a permissible number of tightening-lifting-loosening cycles was obtained, well above the replacement criterion adopted for maintenance purposes.
3.2. Normal conditions of transport The state of the package after the regulatory tests relating to NCT (spraying, free fall drop, stacking and penetration) is as follows: the enclosure of the package sustains only localised deformations with no impact on the spacing between packages and the state and distribution of the contents within the enclosure remain unchanged.
There is no dispersal of the radioactive content on completion of the regulatory tests for normal conditions of transport.
Non-proprietary version
Formulaire : PM04-4-MO-6 rev. 03 Unrestricted Orano Orano NPS Identification : DOS-19-021165-003-NPV Vers. 2.0 Page 7 of 16 3.3. Accident conditions of transport The drop tests are carried out on full-scale prototypes of the packaging, representative of the packaging model. The fuel assemblies prototypes used during the drop tests are dummy assemblies, with cladding made of Zircaloy-4, therefore the structural and geometric characteristics are identical to those of the production assemblies. They are filled with a material whose mechanical characteristics are representative of the fuel pellets.
All drop tests studied:
The possible free-fall drop configurations, of 9 m and of 1 m onto a bar, are studied. The drop tests selected were those that maximised:
The possible damage to the closing system of the internal fitting (doors, frame, top and bottom plates, door-frame connections, top/bottom plate connections to the frame or doors):
9 m flat drop, vertical drop of 9 m, 1 m drop onto a bar; Possible damage to bolted connectors on the top and bottom shells: flat drop of 9 m and vertical drop of 9 m; Possible damage to shell shock absorbers: vertical drop of 9 m.
Drop sequence for Prototype 1 (FCC3 for 12-foot assemblies)
The first drop is a free-fall drop of 1 m onto a bar, against an edge of the door of the internal fitting. This drop places loads on the door-frame connections.
The second drop is a free-fall drop of 1 m onto a bar, against an upper face of the door of the internal fitting. This drop aims to apply maximum load on the door of the internal fitting.
The third drop is a free-fall drop of 9 m, in a vertical position along the centreline of the top end of the package, aimed at testing the shock-absorber of the shell and the bolted connections in the shells.
The fourth drop is a free-fall drop of 9 m, flat, with a whiplash effect, with the initial impact at the top end to hit the bottom end target with maximum velocity.
During the 1st drop, of one metre onto a bar, no break or distortions of the pins connecting the doors to the frame of the internal fitting are noted.
Bar During the second drop of 1 m onto a bar, we note an indentation in the upper plate of the door of the internal fitting, without any tears in the plate.
Non-proprietary version
Formulaire : PM04-4-MO-6 rev. 03 Unrestricted Orano Orano NPS Identification : DOS-19-021165-003-NPV Vers. 2.0 Page 8 of 16 Bar During the third drop, of 9 m along the centreline of the packaging, the protruding section, on the packaging top end side, of the lower shell and the flange are crushed and all bolted connections remain in place.
Protruding section Mating surface and flange crushed between the two shells During the fourth drop of 9 m, flat, all the bolts on the upper and lower shells, and the doors, remain in place.
View of the top of the packaging View of the bottom of the packaging At the end of the sequence of drops, there is no dispersion of radioactive contents, and the assembly shows no sign of generalised longitudinal buckling or any traces facing the bar impact zones.
Finally, a calculation on the rod boxes validated the correct behaviour for a radial loading encompassing the maximum value noted during the drop tests on Prototype 2 and for an axial Non-proprietary version
Formulaire : PM04-4-MO-6 rev. 03 Unrestricted Orano Orano NPS Identification : DOS-19-021165-003-NPV Vers. 2.0 Page 9 of 16 drop onto the top, of 9.25 m, with deferred impact of the internal fitting and without taking into account the shock absorber.
The condition of the package, on completion of the regulatory drop tests for ACT, as mentioned above, is as follows: the enclosure of the package suffers localised deformations which in no way brought into question the safety of the package.
An analysis of the impact of mechanical properties variations, of the shell and the closing screws, on the operating temperature range of the packaging, enables the validation of the packaging drop behaviour.
Furthermore, a comparative numerical analysis of stresses in closing screws of the FCC3 packaging half-shells and of the prototype 1 enables the justification of the separation absence of the FCC3 packaging half-shells. This analysis takes into account the accumulation of NCT and ACT regulatory drops, the possible variations of the mechanical properties of the packaging materials depending on the temperature and the possible variations of the tightening torques.
There is no dispersal of the radioactive contents on completion of the regulatory tests for accident conditions of transport.
Behaviour of the fuel assemblies cladding under regulatory drop tests Under an axial drop, the deformation of the fuel rods in the assemblies is restricted by the strength of the surrounding packaging structures. The longitudinal drop is more severe, as it creates the highest deformation amplitudes.
The results of the correct behaviour of the Zircaloy 4 rods in the prototype fuel assemblies during the drops (conservation of cladding leak-tightness) are extended to the rods made of Zirconium and M5Framatome.
These justifications are carried out while taking into account:
The minimum properties of the claddings over the range of temperatures encountered during NCT, The strain rate of the fuel claddings during the drop tests, The dynamic properties of the M5Framatome claddings for the strain rate during the drop tests.
The results of calculations show that the maximum plastic strains of M5Framatome claddings in fuel assemblies, during the regulatory drop tests, remain well below the permissible plastic rupture elongation. This analysis covers the cases of non-assembled rods in rod boxes.
- 4. Performance from the thermal standpoint 4.1. Routine conditions of transport The temperatures reached by the package under Routine Conditions of Transport (RCT) are identical to those during NCT.
4.2. Normal conditions of transport A transient numerical calculation of a section of the package model is carried out in regulatory ambient conditions, that is:
Maximum regulatory ambient temperature of 38°C, Regulatory sunlight exposure: 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> per day.
The maximum temperature reached by the package during NCT is used in the various sections of the report.
Non-proprietary version
Formulaire : PM04-4-MO-6 rev. 03 Unrestricted Orano Orano NPS Identification : DOS-19-021165-003-NPV Vers. 2.0 Page 10 of 16 The maximum temperature reached by the package remains below the service temperature limit of the neutron-absorbing resin inside the doors of the internal fitting.
4.3. Accident conditions of transport Thermal-fluid numerical calculations on a half-section model of the package, loaded with fuel assemblies, are carried out to determine the kinetics of the maximum temperatures reached by the fuel rods of the assemblies during and after the regulatory fire test. Sensitivity analyses on thermo-fluid 3D models are also performed in order to determine the kinetics of the maximum temperatures at the assemblies ends.
Important packaging parameters chosen for the study For a worst case scenario, the outer shell is ignored during the fire phase; it is modelled during the cooling phase in order to minimise the thermal losses and therefore the package cooling; The sizes of the air inlet and outlet openings in the internal fitting cavity are taken, as a worst case scenario, to be the maximum values from the drop tests; The orientation of the packaging.
Important fuel assemblies parameters chosen for the study The fuel rod array is considered to be as close as possible to the air inlets; The rod array with the lowest thermal inertia is assumed. Thus, the PWR 17x17 rod array is modelled in the plenum section (without the presence of UO2 pellets).
Analysis method The initial package temperature field is the maximum temperature reached by the package under normal conditions of transport; During the 30 minutes regulatory fire duration, the following is taken into account:
- a. Regulatory ambient air temperature of 800 °C;
- b. A coefficient of convective exchange, between the flames and the outer exposed walls of the model equal to the coefficient recommended in regulations of 10 W/m²/K, representative of forced convection within an encompassing fire;
- c. Flame emissivity of 0.9 and an absorptivity of the external surfaces of 0.8, as per regulations.
After the fire, the following assumptions are made:
- d. An ambient air temperature equal to the maximum temperature reached by the package under normal conditions of transport.
- e. Regulatory sunlight exposure applied constantly to the outer surfaces.
Results of the study The study is used to determine the kinetics of the temperature range of the hottest rods (evolution of mean temperature and circumferential gradient) during and after the regulatory fire test.
Non-proprietary version
Formulaire : PM04-4-MO-6 rev. 03 Unrestricted Orano Orano NPS Identification : DOS-19-021165-003-NPV Vers. 2.0 Page 11 of 16 4.4. Creep behaviour of the fuel rod claddings during regulatory fire tests Using the temperature ranges obtained for accidental fire conditions, an additional study of the thermal-mechanical behaviour of the hottest claddings is carried out.
Using the creep laws for claddings made of Zircaloy-4 and M5Framatome, qualified for the temperature ranges encountered during regulatory fire conditions, the mechanical strength of the fuel rod claddings made of Zircaloy-4 and M5Framatome is verified on completion of the regulatory fire test.
A model of the mechanical behaviour of the fuel rods when subjected to a fire test is built, taking into account:
the geometry of the cladding, the geometry of the fuel pellets and the presence of a plenum, the initial internal pressure of the cladding, the kinetics of the temperature range of the fuel rods, taken from thermal calculations for regulatory fire conditions.
The study is carried out on the hottest rods, and shows that the risk of creep-induced bursting of the Zircaloy-4 and M5Framatome claddings is excluded.
4.5. Impact of cladding deformation after the cumulative regulatory drop and fire tests.
The temperatures reached by the claddings during the regulatory fire test and the duration of these temperatures leads to a relaxing of the residual stresses in the claddings caused by deformations of the latter during the regulatory drop tests prior to the thermal fire test.
Thus, the conclusions of the thermal-mechanical study on the creep strength of claddings made of Zircaloy-4 and M5Framatome are unchanged by the deformation of claddings during the previous regulatory drop tests.
- 5. Performance from the standpoint of radiation protection The chosen dose equivalent rate criteria covering the regulatory transport conditions applicable to industrial type packages loaded with fissile materials are as follows:
Routine conditions of transport: 2 mSv/h in contact with the package, Normal conditions of transport: less than 20% increase in the maximum radiation intensity in contact with the package.
5.1. Routine conditions of transport Content parameters important to the study The study considers the package loaded with ERU type fuel assemblies, with an enrichment of 4.95% in 235U and a proportion of 232U of 50 ppb defining the maximum radioactive content.
Parameters for the packaging and internal fitting important to the study The shortest distance between the assembly and the external surface of the shell is used.
Calculation method The dose equivalent rates were determined by means of a design code using a deterministic straight line attenuation method Result of the study Non-proprietary version
Formulaire : PM04-4-MO-6 rev. 03 Unrestricted Orano Orano NPS Identification : DOS-19-021165-003-NPV Vers. 2.0 Page 12 of 16 Compliance with the dose equivalent rate criterion for routine conditions of transport is guaranteed for the maximum radioactive content.
5.2. Normal conditions of transport Damage modes caused by the regulatory drop of 1.2 m, which might have an impact on the maximum radiation levels, are: deformations in the outer shell and deformations of the cradle for the internal fitting.
Deformations after the drop test of 1.2 m are calculated using the deformations in the shell following the 9 m drop test on the FCC4 packaging Prototype 2 of the safety analysis report
[2] ; the FCC4 packaging has a similar design to the FCC3 packaging but it enables the transportation of longer assemblies (14 feet).
Based upon the maximum deformations due to the regulatory drop test of 1.2 m, it is proven that the criterion for the maximum increase in dose equivalent rate, in contact with the package, is respected.
- 6. Performance from the criticality safety standpoint Depending on regulations, criticality safety must be assured, for:
The isolated package, under routine conditions (as submitted for transportation),
The isolated package, under normal conditions of transport (resulting from the regulatory testing for normal conditions of transport);
The isolated package, under accident conditions of transport (resulting from the cumulative tests for both normal and accident conditions of transport);
An arrangement of 5N packages (where N is the number used to define the regulatory Criticality Safety Index (CSI)) coefficient value under Normal Conditions of Transport, An arrangement of 2N packages under accident conditions of transport.
The number (N) of packages, as defined by Articles 681 and 682 of reference [1], which can be transported from a criticality-safety standpoint is used to determine the Criticality-Safety Index (CSI) by the formula: CSI = 50 / (mini (NNCT ; NACT)).
The sub-criticality criterion selected for a single package and multiple packages is as follows:
Keff 0.95, all uncertainties included.
The damaged package is defined as being the outcome of the cumulative tests representative of NCT and ACT.
The undamaged package is defined as resulting either from routine conditions of transport or from drop tests in normal conditions of transport with regard to the slight damage possible to the shells of the packaging.
6.1. FCC3 packaging loaded with fuel assemblies Content parameters important to the study The geometry of the fuel rod array resulting, notably, from the regulatory tests; Assemblies are modelled in their entirety with all-identical fuel rods; to assume a worst case scenario, the guide tubes are replaced by water; When calculating moderation, the rods are presumed to be spaced homogeneously across the whole fissile cross section.
The density of the fresh UO2 fuel is equal to 100% of the theoretical density; Non-proprietary version
Formulaire : PM04-4-MO-6 rev. 03 Unrestricted Orano Orano NPS Identification : DOS-19-021165-003-NPV Vers. 2.0 Page 13 of 16 The uranium may originate from reprocessing as the 234U and the 236U present in enriched reprocessed uranium (ERU) are poisons which reduce the reactivity of the assemblies and which are not taken into account in the criticality-safety assessment.
The fissile column is modelled in the form of a cylinder, with the maximum diameter of the pellets throughout the full fissile height, the cladding is modelled at its minimum diameter, without a gap between pellets and cladding; The packages may only contain 1 or 2 assemblies of the same type and a maximum 235U enrichment of 5% for 14x14, 15x15 and 17x17 assemblies:
Packaging parameters important to the study The geometry of the packaging: the undamaged packaging is modelled with its outer shell.
The damaged packaging is modelled without the outer shell; The cross sectional area of the packaging and neutron cavity remain unchanged following the regulatory tests; The composition of the neutron-absorbing resin, caused notably by regulatory fire conditions for damaged packages.
Assumptions important to the study Isolated package The single package is modelled in a sectional model of the central section of the package; The undamaged package is filled with water and surrounded by a reflector of 20 cm of water; The damaged package is surrounded by a reflector of 20 cm of water. The space between the cavity and the outer shell is:
either full of water (the package is also in water),
or filled with void space (differential draining of the package is considered).
Multiple packages An arrangement of 5N packages under NCT is taken into account by assuming an infinite array of undamaged packages. Total reflection conditions are applied to all outer surfaces of a single package, modelled in three dimensions. The space between the cavity and the shell is:
either filled with water, of filled with empty space: differential draining of the package; An arrangement of 2N packages under ACT is taken into account by assuming an array with a finite or infinite number (depending on the case) of damaged packages in contact, modelled in 3D; a reflector of 20 cm of water around the outside of the array is taken into account; in this configuration, two variations have been studied.
The inside of the package is empty of water, with the exception of the fuel, which is moderated by water (case of differential draining),
The inside of the package is full of water, the fuel is moderated by water; The model used for the damaged package takes into consideration an expansion of the fuel rod array over a bounding length, resulting from the conclusions drawn from the combined drop regulatory tests.
Calculation method:
The calculations were conducted using the APOLLO2-MORET4 calculation scheme (standard for the CRISTAL formula) for the transportation of fresh UO2 fuel.
Non-proprietary version
Formulaire : PM04-4-MO-6 rev. 03 Unrestricted Orano Orano NPS Identification : DOS-19-021165-003-NPV Vers. 2.0 Page 14 of 16 Results of the study Isolated package The single package respects the sub-criticality margin Keff 0.95, all uncertainties included.
Multiple packages The layout of an infinite number of packages under Normal Conditions of Transport, respects the criterion of Keff 0.95, all uncertainties included, even in the event of differential drainage.
The layout of 2N packages under Accident Conditions of Transport, respects the criterion of Keff 0.95, all uncertainties included, with N=80, for 15x15 and 17x17 assemblies The layout of an infinite number of packages under Accident Conditions of Transport, respects the criterion of Keff 0.95, all uncertainties included, for 14x14 assemblies.
Criticality safety is ensured for the FCC3 packagings loaded with type 15x15 and 17x17 assemblies with a CSI = 0.625.
Criticality safety is ensured for the FCC3 packagings loaded with type 14x14 14x14 assemblies with a CSI = 0.
6.2. FCC3 packaging loaded with rods in rod box or channel The non-assembled rods are transported wedged, in quantity, in rod boxes which replace the assemblies.
Content parameters important to the study The geometry of the fuel rods resulting, notably, from the regulatory tests; maximum enrichment: 5 % 235U; The density of the fresh UO2 fuel is equal to 100% of the theoretical density; Any number of rods.
Packaging parameters important to the study Identical to those defined in § 6.1.
Assumptions important to the study Identical to those defined in § 6.1 as a single package or a number of packages; The rod box is not modelled. The radial spacer is modelled by water or air whichever is the more conservative case.
Results of the study The single package respects the sub-criticality margin Keff 0.95, all uncertainties included; An arrangement of an infinite number of packages under NCT and ACT respects the criterion Keff 0,95, all incertainties included.
The number N for transportation of the rods is infinite in NCT and ACT; we therefore have CSI = 0.
The gadolinia rods with a minimum content of gadolinium on a matrix of a maximum enrichment of 5% 235U can be transported, regardless of number and type of packaging used as the K of the rods is below 1.0, regardless of moderation.
The maximum permissible increase, from a criticality safety point of view, for the cross section of the cavity of the FCC3 packagings under ACT is determined.
Non-proprietary version
Formulaire : PM04-4-MO-6 rev. 03 Unrestricted Orano Orano NPS Identification : DOS-19-021165-003-NPV Vers. 2.0 Page 15 of 16
- 7. Conditions of use The packaging is designed to be loaded and unloaded when dry.
The safety analyses detailed above require, notably, that the following steps and verifications must be carried out and the criteria met, before the package is shipped:
The fuel assemblies or unassembled fuel rods for shipment must respect all technical characteristics defined for the authorised content; The packaging must comply with the periodic inspections to be completed.
The verification of the various packaging elements in order to verify the potential faults, comply with the requirements of the chapter in the Safety Analysis Report covering the specifications relating to the packaging; The checks for the absence of water or unauthorised foreign objects in the base of the bottom shell; The checks for the absence of flaking paintwork on the uninterrupted sections of the packaging; Verification of the installation of the system used for internal locking; Verification of the wedging of rods and the maximum number of rod rows loaded into the rod box; Verification of the correct positioning and closure of the lid; Verification that the contact radiation intensity and contamination of the external surface are below the criteria for radiation intensity and contamination defined in the regulations; Measurement of the radiation level at 1 m for determination of the transport index; Verification of the regulatory compliance of labels and markings on the packagings; The wedging and tie-down of packages must respect the criteria and requirements laid out in the Safety Analysis Report; Verification that the mode of transport is compatible with the transport index, the criticality safety index and the activity of the contents.
- 8. Periodic maintenance programme The packaging is subject to a periodic maintenance programme, defined according to two frequency types, depending on which is the most restrictive: the number of transport cycles completed and the duration of use.
The maintenance programme includes:
Verification of the general condition of the packaging and replacement of any non-compliant components; Verifications of the safety welds loaded during transport; Verifications of the condition of bolted or screwed components, the condition of hinge pins, hinges, pin locks, connections, locking systems in general and the system for vertical restraint of the internal fitting. Replacement of all the connecting bolts on the two half shells is completed after a given number of transport cycles, defined in the Safety Analysis Report; The search for paintwork faults and repair work is carried out as required; A verification of the correct appearance of the shock absorbers; The verification of the absence of faults on the shock absorber welds after a number of transport cycles or a specific duration for use as specified in the Safety Analysis Report, in order to verify the maintaining of their safety functions.
Non-proprietary version
Formulaire : PM04-4-MO-6 rev. 03 Unrestricted Orano Orano NPS Identification : DOS-19-021165-003-NPV Vers. 2.0 Page 16 of 16 All packagings with one or more components not meeting the criteria specified in the maintenance programme must be withdrawn from service until the appropriate corrective action is applied.
All components which have become non-compliant may be fixed or accepted in this state as long as a complementary analysis shows that the situation does not bring into question the conclusions of the Safety Analysis Report. If this is not the case, the component must be replaced.
- 9. Quality assurance programme The transport regulations in force at the date of this document stipulate the application of quality assurance programmes for the:
Design, Manufacturing and testing, The use, Maintenance, Transportation of packages containing radioactive materials.
These activities are undertaken by various parties (designer, owner, project manager, manufacturers, users, consignors, carriers, maintenance companies, etc.) who must all draw up suitable quality assurance plans and produce and conserve records of their activity.
- 10. References
[1] Regulations for the Safe Transport of Radioactive Material - International Atomic Energy Agency - Requirements SSR 6 (Rev. 1) - 2018 edition;
[2] Safety analysis report Orano NPS DOS-19-021166-000 vers. 2.0 of the FCC4 packaging.
Non-proprietary version