ML22277A740
| ML22277A740 | |
| Person / Time | |
|---|---|
| Site: | 07103097 |
| Issue date: | 08/03/2022 |
| From: | Boyle R, Shaw D TN Americas LLC |
| To: | Division of Fuel Management |
| Garcia-Santos N | |
| Shared Package | |
| ML22277A716 | List:
|
| References | |
| A33010, L-2022-DOT-0008 | |
| Download: ML22277A740 (18) | |
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 FCC4 Checked by Identification : DOS-19-021166-003-NPV Vers. 2.0 Page 1 / 18 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 11
- 5. Performance from the standpoint of radiation protection 13
- 6. Performance from the criticality safety standpoint 13
- 7. Conditions of use 16
- 8. Periodic maintenance programme 17
- 9. Quality assurance programme 18
- 10. References 18 Non-proprietary version
Formulaire : PM04-4-MO-6 rev. 03 Unrestricted Orano Orano NPS Identification : DOS-19-021166-003-NPV Vers. 2.0 Page 2 of 18 Status of revision English French I
Date Purpose and record of revisions Prepared by / Verified by version version Old reference: DOS-13-00081779-050 0 0 04/2012 First issue Appendix 2.5-4 added 1 1 09/2012 I Proof of the increase in cavity section from x mm² to x mm² 2 2 10/2016 Document re-write New reference: DOS-19-021166-003 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 2.0 of the mechanical properties depending on the temperature of half-shells and See 1st screws; addition of the analysis justifying the absence of half-shells separation 3.0 page - Thermic in accidental conditions §4.3: addition of sensitivity analyses on thermo-fluid 3D models
- Sub-criticality §6.2: deletion of the study case without rods spacing in rod boxes (case not authorised anymore)
- Formal changes This document and the information which it contains are the property of Orano NPS and cannot be disclosed, reproduced or used without its prior written authorization.
Formulaire : PM04-4-MO-6 rev. 03 Unrestricted Orano Orano NPS Identification : DOS-19-021166-003-NPV Vers. 2.0 Page 3 of 18
- 1. Purpose The aim of this chapter is to detail the performance characteristics of the FCC4 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 Regulation, 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 FCC4 package can be 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 Lower shell lifting boxes This document and the information which it contains are the property of Orano NPS and cannot be disclosed, reproduced or used without its prior written authorization.
Formulaire : PM04-4-MO-6 rev. 03 Unrestricted Orano Orano NPS Identification : DOS-19-021166-003-NPV Vers. 2.0 Page 4 of 18 The overall general dimensions of the package are:
length = 5748 mm; width = 1134 mm; height = 1297 mm.
The FCC4 packaging is designed for the transportation of the following contents:
assemblies with a nominal active length of 14 feet, with or without clusters; non-assembled rods for assemblies with a nominal active length of 8, 10, 12 and 14 feet.
The FCC4 packaging is available in two versions, depending on the content considered:
version 1: for fuel assemblies composed of a 17x17 square fuel rod array (XL, XLR, EPR and GAIA) or for non-assembled fuel rods grouped in rod boxes (channels);
version 2: for fuel assemblies composed of a 16x16 or 18x18 square fuel rod array.
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 FCC4 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 liners and gusset plates together with vertical flats, each with a hooking point for handling the packaging. 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:
a support frame whose rigid structure in the form of an inverted "T" 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 control 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.
This document and the information which it contains are the property of Orano NPS and cannot be disclosed, reproduced or used without its prior written authorization.
Formulaire : PM04-4-MO-6 rev. 03 Unrestricted Orano Orano NPS Identification : DOS-19-021166-003-NPV Vers. 2.0 Page 5 of 18 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 - 16x16, 17x17 or 18x18. 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 FCC4 packagings, which can be used to transport 14, 12, 10 and 8-foot and EPR versions. 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 certain 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 235U enrichment rate of 5%;
the maximum density (100 % of the theoretical density of UO2);
the cladding material in M5Framatome alloy or Zircaloy-4.
When the version 1 FCC4 package only includes one fresh 17x17 EPR fuel assembly in a configuration with a cluster, it is possible to complete the empty cavity with a ballast, either an EPR assembly model, or a dummy assembly with smooth walls.
A maximum of 5 g of glycerine may be present in each of the assemblies or on the assembly model.
The presence of desiccant is permitted outside of the cavity.
This document and the information which it contains are the property of Orano NPS and cannot be disclosed, reproduced or used without its prior written authorization.
Formulaire : PM04-4-MO-6 rev. 03 Unrestricted Orano Orano NPS Identification : DOS-19-021166-003-NPV Vers. 2.0 Page 6 of 18 2.4. Containment system In the FCC4 package design, fissile material containment 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:
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 the 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 FCC4 package in transport is 5,550 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 authorized 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 combined 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 FCC4 packagings.
The acceptability of the lifting arrangements for 14-foot containers is verified in accordance with the RCC-MR code. The results show that the structure meets the criteria for excessive 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.
This document and the information which it contains are the property of Orano NPS and cannot be disclosed, reproduced or used without its prior written authorization.
Formulaire : PM04-4-MO-6 rev. 03 Unrestricted Orano Orano NPS Identification : DOS-19-021166-003-NPV Vers. 2.0 Page 7 of 18 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.
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 in 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; The possible damage to bolted connectors of the top and bottom shells: flat drop of 9 m and vertical drop of 9 m; The possible damage to shell shock absorbers: vertical drop of 9 m.
Drop sequence for Prototype 1 (FCC3 for 12-foot assemblies)
The 1st 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 2nd 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 is designed to apply a maximum load to the door of the internal fitting.
The 3rd drop is a free-fall drop of 9 m, in a vertical position along the centreline of the top end of the packaging, aimed at testing the shell shock absorber and the bolted connections of the shells.
The 4th drop is a free-fall drop of 9 m, flat, with a whiplash effect, with the initial impact at the top end to ensure the bottom end target hits with maximum velocity.
No failure or strain in the door/frame connecting pins for the internal fitting are observed for the 1st drop of 1 m onto a bar.
This document and the information which it contains are the property of Orano NPS and cannot be disclosed, reproduced or used without its prior written authorization.
Formulaire : PM04-4-MO-6 rev. 03 Unrestricted Orano Orano NPS Identification : DOS-19-021166-003-NPV Vers. 2.0 Page 8 of 18 Bar A dent is observed in the upper plate of the internal fitting door, with no tearing, for the 2nd drop of 1 m onto a bar.
Bar The protruding part on the top side of the packaging of the lower shell and the flange are crushed and all of the bolted connections stay in position during the 3rd drop of 9 m along the centreline of the packaging.
Crushed flange and Mating surface for protruding part the two shells All of the bolts in the upper and lower shells and the doors are in position for the 4th flat drop of 9 m.
This document and the information which it contains are the property of Orano NPS and cannot be disclosed, reproduced or used without its prior written authorization.
Formulaire : PM04-4-MO-6 rev. 03 Unrestricted Orano Orano NPS Identification : DOS-19-021166-003-NPV Vers. 2.0 Page 9 of 18 View of packaging top View of the packaging bottom At the end of the drop sequence, the radioactive content does not disperse and the assembly has not suffered from general longitudinal buckling and bears no marks opposite the bar impact area.
The results of the vertical drop test carried out on prototype 1 of the FCC3 packaging are extended to the FCC4 packaging by analysing the impact of the differences between the two packaging models on the behaviour of the absorbers and the strength of the bolted connections of the shells.
Drop sequence for prototype 2 (FCC4 for 14-foot assemblies)
The 1st drop is a free-fall drop of 1 m onto a bar, near to a door bolt on the internal fitting. This drop applies loads to the doors and the door hinges.
The 2nd drop is a free-fall drop of 1 m onto a bar, at the same impact point, but from a different drop angle to the 1st drop. This drop is designed to apply a maximum load to the door of the internal fitting and maximize the risk of perforation.
The 3rd drop is a flat drop with whiplash effect, with the initial impact at the bottom end to ensure the top end target hits with maximum velocity.
A dent is observed in the door plate, with no tearing, and the door hinges are intact, for the 1st drop of 1 m onto a bar.
Bar A dent is observed in the upper door plate and the door is torn for the 2nd drop of 1 m onto a bar.
This document and the information which it contains are the property of Orano NPS and cannot be disclosed, reproduced or used without its prior written authorization.
Formulaire : PM04-4-MO-6 rev. 03 Unrestricted Orano Orano NPS Identification : DOS-19-021166-003-NPV Vers. 2.0 Page 10 of 18 Bar All of the bolts connecting the two shells stayed in position for the 3rd flat drop of 9 m.
At the end of the drop sequence, the radioactive content does not disperse and the assembly has not suffered from general longitudinal buckling. The assembly is deformed in the areas facing the impact zones for the different drops performed, particularly in the impact zone for drops onto a bar.
Finally, a calculation performed on the rod boxes validated satisfactory behaviour for a bounding radial load of the maximum value observed during the drop tests for prototype 2 and for an axial drop on the top side of 9.25 m with a deferred impact for the internal fitting and with no consideration of the shock absorber.
The condition of the package on completion of the regulatory tests, under ACT as mentioned above, is as follows: the package enclosure suffers localised deformation, which has no effect on 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 package, 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 and by extension of the FCC4 packaging. 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.
An analysis of the impact of mechanical properties variations, of the shells and the closing screws, on the operating range of the packaging is also performed and enables the validation of the packaging drop behaviour.
There is no dispersal of the radioactive content on completion of the regulatory tests for accident conditions of transport.
This document and the information which it contains are the property of Orano NPS and cannot be disclosed, reproduced or used without its prior written authorization.
Formulaire : PM04-4-MO-6 rev. 03 Unrestricted Orano Orano NPS Identification : DOS-19-021166-003-NPV Vers. 2.0 Page 11 of 18 Behaviour of the fuel assemblies cladding for regulatory drops In a drop, the deformation in the assemblies rods is limited by the strength of the surrounding packaging structures. The longitudinal drop generates greater loads as it leads to larger strain amplitudes.
The results of the satisfactory behaviour of the Zircaloy-4 rods in the fuel assemblies prototypes during drops (cladding leak-tightness maintained) are extended to the zirconium M5Framatome alloy rods.
The scope of this proof is established considering:
the minimum properties of the claddings in the temperature ranges under normal conditions of transport, the strain rate of the claddings during drops, the dynamic properties of the M5Framatome claddings for strain rate during drops.
The results of the calculations demonstrate that the maximum plastic strains for the M5Framatome claddings in the fuel assemblies during regulatory drops remain well below the allowable plastic rupture elongation limit. This analysis covers the loading of non-assembled fuel rods in fuel rod boxes.
- 4. Performance from the thermal standpoint 4.1. Routine conditions of transport The temperatures reached by the package in routine conditions of transport are identical to those reached in normal conditions of transport.
4.2. Normal conditions of transport A transient numerical calculation is performed for a package model section in regulatory ambient conditions, i.e.:
maximum regulatory ambient temperature of 38°C, regulatory solar radiation applied 12h/24h.
The maximum temperature reached by the package in normal conditions of transport is used in the various sections of the report.
The maximum temperature reached by the package remains below the limit operating temperature of the neutron-absorbing resin in the doors of the internal fitting.
4.3. Accident conditions of transport Thermal-fluid numerical calculations on a half-model section of the package loaded with a fuel assembly are performed to determine the kinetics of the maximum temperatures reached by the rods in the fuel assemblies during and after the regulatory fire test. Sensitivity analyses on thermal-fluid 3D models are also performed in order to determine the kinetics of the maximum temperatures at the assemblies ends.
Key packaging parameters used in the study On a conservative basis, the external shell is not considered during the fire phase; it is modelled during the cooling phase in order to minimize heat loss and thereby minimize package cooling; the size of the air inlet and outlet openings in the cavity of the internal fitting are taken as the maximum of the values obtained in the drop tests on a conservative basis; packaging orientation.
This document and the information which it contains are the property of Orano NPS and cannot be disclosed, reproduced or used without its prior written authorization.
Formulaire : PM04-4-MO-6 rev. 03 Unrestricted Orano Orano NPS Identification : DOS-19-021166-003-NPV Vers. 2.0 Page 12 of 18 Key fuel assemblies parameters used in the study The presence as close as possible to the air inlets for the array of fuel rods is considered; the array of rods with the lowest heat inertia is considered. A 17x17 array of PWR rods is therefore modelled in the plenum section (without the UO2 pellets).
Analysis method The initial temperature field of the package corresponds to the maximum temperature reached by the package in normal conditions of transport.
During the 30-minute regulatory fire period, the following are integrated:
- a. a regulatory ambient air temperature of 800 °C;
- b. a coefficient of convective exchange between the flames and the exposed external walls of the model equal to the coefficient recommended in regulations of 10 W/m²/K representative of forced convection within a full-scale 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 are integrated:
- d. an ambient air temperature equal to the maximum temperature reached by the package in normal conditions of transport;
- e. regulatory solar radiation applied to external surfaces at all times.
Results of the study The study is used to determine the kinetics of the temperature field of the hottest rods (variation in mean temperature and circumferential gradient) during and after the regulatory fire tests.
4.4. Behaviour of fuel rod claddings with respect to creep during regulatory fire tests A complementary study on the thermal-mechanical behaviour of the hottest claddings is carried out using the temperature fields obtained in accident fire conditions.
The mechanical strength of the Zircaloy-4 alloy and M5Framatome rod claddings is checked on completion of the regulatory fire test based on the creep laws for Zircaloy-4 alloy and M5Framatome claddings, qualified over the temperature ranges found in regulatory fire conditions.
The mechanical behaviour of fuel rods subject to fire tests is modelled integrating:
the cladding geometry, the geometry of the fuel pellets and the presence of the plenum, initial internal pressure in the cladding, the kinetics of the temperature field of the rods resulting from heat calculations in regulatory fire conditions.
The study is carried out on the hottest rods and demonstrates that the risk of bursting by creep of the Zircaloy-4 alloy and M5Framatome claddings is excluded.
4.5. Impact of cladding strain following combination of the regulatory fire and drop tests The temperatures reached by the claddings during the regulatory fire test and the duration of these temperatures lead to the relaxing of residual stresses in the claddings due to strain during the regulatory drop tests prior to the fire test.
This document and the information which it contains are the property of Orano NPS and cannot be disclosed, reproduced or used without its prior written authorization.
Formulaire : PM04-4-MO-6 rev. 03 Unrestricted Orano Orano NPS Identification : DOS-19-021166-003-NPV Vers. 2.0 Page 13 of 18 On this basis, the conclusions of the thermal-mechanical study of resistance to creep for the Zircaloy-4 alloy and M5Framatome claddings are not modified by the cladding strains during the previous regulatory drop tests.
- 5. Performance from the standpoint of radiation protection The dose equivalent rate criteria adopted to cover regulatory transport conditions and 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 is performed considering the package loaded with ERU type fuel assemblies, with the maximum radioactive content defined as 235U enrichment of 4.95 % and 50 ppb 232U.
Packaging and internal fitting parameters important to the study The shortest distance between the assembly and the external surface of the shell is considered.
Calculation method Dose equivalent rates were determined using a computer code based on a straight line attenuation deterministic method.
Result of the study 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 The types of damage caused during a regulatory drop test of 0.9 m, which can affect the maximum radiation level are the external shell strain and internal fitting cradle strain.
Strain after the drop test of 0.9 m is calculated on the basis of shell strain after the drop of 9 m for the FCC4 type prototype 2 (see section 3.3).
On the basis of the maximum strain for a regulatory drop of 0.9 m, it is proved that the criterion for the maximum increase in dose equivalent rate in contact with the package is satisfied.
- 6. Performance from the criticality safety standpoint Depending on regulations, criticality safety must be assured, for:
the isolated package, under routine conditions of transport (that is to say, how it is to be found during transportation);
the isolated package, under normal conditions of transport (that is to say, resulting from the regulatory testing for normal conditions of transport);
the isolated package, under accident conditions of transport (that is to say, resulting from the cumulative tests for both normal and accident conditions of transport);
the configuration of 5N packages (where N is the number used to define the regulatory Criticality Safety Index (CSI) coefficient) under normal conditions of transport; the configuration of 2N packages under accident conditions of transport.
This document and the information which it contains are the property of Orano NPS and cannot be disclosed, reproduced or used without its prior written authorization.
Formulaire : PM04-4-MO-6 rev. 03 Unrestricted Orano Orano NPS Identification : DOS-19-021166-003-NPV Vers. 2.0 Page 14 of 18 The number (N) of packages, as defined by Articles 681 and 682 of [1], which can be transported from a criticality-safety standpoint is used to determine the Criticality-Safety Index (CSI) by the formula:
CSI = 50 / (min. (NNCT; NACT)).
The sub-criticality criterion adopted for the isolated package and multiple packages is as follows:
Keff 0.95, including all uncertainties.
The damaged package is defined as that resulting from all of the tests representing normal conditions of transport and accident conditions of transport.
The non-damaged package is defined as resulting either from routine conditions of transport or from drops in normal conditions of transport with regard to the minor potential damage to the packaging shells.
6.1. FCC4 packaging loaded with assemblies Content parameters important to the study The geometry of the array of fuel rods, particularly resulting from the regulatory tests; the assemblies are modelled as complete, with all identical rods; guide tubes are replaced with water on a conservative basis; when calculating moderation, the rods are presumed to be spaced homogeneously across the fissile section; the density of fresh UO2 fuel is equal to 100% of the theoretical density; 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 are not taken into account in the criticality safety assessment; the fissile column is modelled as a cylinder with the maximum pellet diameter over the entire fissile height, and the cladding is modelled at its minimum diameter with no gap between the pellet and the cladding; the packages may only contain one or two assemblies of the same type, with a maximum enrichment of:
5% 235U for assemblies in a 17x17 array 4.5% 235U for assemblies in a 16x16 and 18x18 array.
Packaging parameters important to the study The geometry of the packaging; the non-damaged packaging is modelled with its external shell. The damaged packaging is modelled without its external shell; the section of the packaging and the neutron cavity remain unchanged after the regulatory tests; the composition of the neutron-absorbing resin mainly resulting from the regulatory fire conditions for the damaged package.
Assumptions important to the study Isolated package The isolated package is modelled in a sectional model in the central part of the package; the non-damaged package is filled with water and surrounded by a reflector with 20 cm of water; the damaged package is surrounded by a reflector with 20 cm of water. The space between the cavity and the external shell is:
This document and the information which it contains are the property of Orano NPS and cannot be disclosed, reproduced or used without its prior written authorization.
Formulaire : PM04-4-MO-6 rev. 03 Unrestricted Orano Orano NPS Identification : DOS-19-021166-003-NPV Vers. 2.0 Page 15 of 18 either full of water (the package is also filled with water),
or filled with vacuum (differential draining of the package is considered).
Multiple packages The configuration of 5N packages in normal conditions of transport is considered, with an infinite array of non-damaged packages. Total reflection conditions are applied for all of the external surfaces of one single package modelled in three dimensions. The space between the cavity and the shell is:
Either filled with water, Or filled with vacuum: package with differential drainage; The configuration of 2N packages in accident conditions of transport is considered with an array with a finite number of damaged packages in contact and modelled in three dimensions; a reflector with 20 cm of water at the edge of the array is integrated; two variants are studied in this configuration:
the inside of the package is drained of water, except the fuel moderated by water: this applies for differential drainage, the interior of the package is filled with water, the fuel is moderated by water.
The model adopted for the damaged package incorporates the expansion of the array of fuel rods over a bounding length resulting from the conclusions of the combined regulatory drop tests.
Calculation method:
The calculations were conducted using the APOLLO2-MORET4 code (standard for the CRISTAL formula) for the transportation of fresh UO2 fuels.
Results of the study Isolated package The isolated package satisfies the Keff 0.95 sub-criticality margin, including all uncertainties.
Multiple packages The configuration of an infinite number of packages in normal conditions of transport satisfies the Keff 0.95 criterion, including all uncertainties, even with differential drainage.
The configuration of 2N packages in accident conditions of transport satisfies the Keff 0.95 criterion, including all uncertainties (where N = 6 or 80 depending on the type of assembly).
Criticality safety is ensured for FCC4 packagings loaded with 17x17 XL, 17x17 XLR, 17x17 EPR type, 17x17 GAIA type assemblies with CSI = 0.625.
The criticality safety criterion is met for the FCC4 packagings loaded with type 16x16 and 18x18 assemblies with CSI = 8.33.
6.2. FCC4 packaging loaded with fuel rods in rod boxes or channels Non-assembled rods are transported in large numbers, wedged in boxes, which replace the fuel assemblies.
Content parameters important to the study The geometry of the fuel rods that remain intact; maximum enrichment: 5% 235U; This document and the information which it contains are the property of Orano NPS and cannot be disclosed, reproduced or used without its prior written authorization.
Formulaire : PM04-4-MO-6 rev. 03 Unrestricted Orano Orano NPS Identification : DOS-19-021166-003-NPV Vers. 2.0 Page 16 of 18 the density of 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 section 6.1.
Assumptions important to the study Identical to those defined in section 6.1 with an isolated package or multiple packages; the fuel rod box is not modelled. The radial wedging is modelled by water or by air, whichever is the most conservative.
Results of the study The isolated package satisfies the Keff 0.95 sub-criticality margin, including all uncertainties; the configuration of an infinite number of packages in normal conditions of transport and in accident conditions of transport satisfies the Keff 0.95 criterion, including all uncertainties.
The number N for transportation of the rods is infinite in NCT and ACT; we therefore have CSI = 0.
Gadolinium-bearing rods with a minimum gadolinium content on a matrix with a maximum of 5% 235U enrichment can be transported, regardless of the number and type of packaging used, as the K of these rods is less than 1.0, irrespective of their moderation.
The maximum allowable increase, from a criticality safety standpoint, of the section of the FCC4 packaging cavity in accident conditions of transport, is determined.
- 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 non-assembled fuel rods intended for shipment must respect all of the technical characteristics defined for authorized contents; the packaging must comply with the periodic checks required.
checking of the different packaging components to verify that any defects comply with the provisions of the chapter of the safety report concerning specifications on the packaging; checking for the absence of water or unauthorised foreign objects in the bottom of the lower shell; checking for the absence of flaking paintwork on the uninterrupted sections of the packaging; verification of the positioning of the internal locking system; verification of rod wedging and the maximum number of rows of fuel rods loaded into the fuel rod boxes; verification of the correct position and closing of the lid; verification that the intensity of the contact radiation and the contamination of the external surface are below the criteria for radiation intensity and contamination defined in the regulations; measurement of radiation intensity at a distance of 1 m for determining the transport index; verification of the regulatory compliance of labels and markings on the packagings; package wedging and tie-down must satisfy the criteria and requirements of the safety analysis report; This document and the information which it contains are the property of Orano NPS and cannot be disclosed, reproduced or used without its prior written authorization.
Formulaire : PM04-4-MO-6 rev. 03 Unrestricted Orano Orano NPS Identification : DOS-19-021166-003-NPV Vers. 2.0 Page 17 of 18 verification that the mode of transport is compatible with the transport index, the criticality safety index and the activity of the contents; for loads beyond the 5-year period after the last periodic maintenance operation, a verification of the good general condition of bolting, with no dismantling.
- 8. Periodic maintenance programme 8.1. Version 1 FCC4 packaging series 400 or version 2 FCC4 The packaging is subject to the periodic maintenance programme, which is defined based on two frequency types, whichever is most restrictive: the number of transport cycles completed and the duration of use.
Notably, the maintenance programme includes:
checking the good general condition of the packaging and replacing any non-compliant components; inspecting safety welds subjected to stresses during transportation, checking the condition of the components of screwed or bolted systems, the condition of hinge pins, hinges, pin locks, connections, locking systems in general and the vertical blocking system of the internal fitting. All of the connecting bolts on the 2 half-shells are replaced based on a number of transport cycles specified in the safety analysis report; detection of defective paintwork and rework if necessary; checking of the good appearance of shock absorbers; checking of the absence of defects on absorber welds after a number of transport cycles or a duration of use specified in the safety analysis report in order to check that safety functions are fulfilled.
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 if a complementary analysis shows that the conclusions of the Safety Analysis Report are not called into question. If this is not the case, the component must be replaced.
8.2. Version 1 FCC4 packaging, series 600 The packaging is subject to the periodic maintenance programme, based on whichever is most restrictive: the number of transport cycles completed and the duration of use.
8.2.1. Basic maintenance The basic maintenance program includes all of the checks on the version 1 FCC4 packaging, series 400 or version 2 FCC4 from section 8.1, excluding checks for the absence of defects on absorber welds, which must be performed for the version 1 FCC4, series 600, as part of each basic periodic maintenance operation.
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 if a complementary analysis shows that the conclusions of the Safety Analysis Report are not called into question. If this is not the case, the component must be replaced.
This document and the information which it contains are the property of Orano NPS and cannot be disclosed, reproduced or used without its prior written authorization.
Formulaire : PM04-4-MO-6 rev. 03 Unrestricted Orano Orano NPS Identification : DOS-19-021166-003-NPV Vers. 2.0 Page 18 of 18 8.2.2. Intermediate maintenance The packaging is subjected to intermediate maintenance for each rotation completed after the maximum time between two basic maintenance operations on version 1 FCC4 packagings, series 400, or version 2 FCC4 from section 8.1, which notably includes:
checking the good general condition of the packaging and replacing any non-compliant components; the visual inspection of the paint on safety welds in accessible areas of the two half-shells, including the detection of defects if blisters, cracks or areas without paint exist; checking the condition of the pin locks, connections and the vertical blocking system of the internal fitting, without dismantling; detection of defective paintwork and rework if necessary; 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 if a complementary analysis shows that the conclusions of the Safety Analysis Report are not called into question. If this is not the case, the component must be replaced.
- 9. Quality assurance programme The transport regulations in force on the date of this document require the application of quality assurance programmes for:
the design, the manufacturing and testing, the use, the maintenance, and transport, of packages containing radioactive materials.
These activities are undertaken by various parties (designer, owner, project management, 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.
This document and the information which it contains are the property of Orano NPS and cannot be disclosed, reproduced or used without its prior written authorization.