ML22271A800
| ML22271A800 | |
| Person / Time | |
|---|---|
| Site: | Orano USA |
| Issue date: | 10/29/2004 |
| From: | Boyle R, Shaw D Framatome |
| To: | Division of Fuel Management |
| Garcia-Santos N | |
| Shared Package | |
| ML22271A128 | List:
|
| References | |
| A33010, EPID L-2022-DOT-0007 | |
| Download: ML22271A800 (27) | |
Text
A FF/DC/01106 FRAMATOME ANP NUCLEAR FUEL Revision A DESIGN & SALES SAFETY/CRITICALITY STUDY OF FCC3v2 CONTAINERS 14 X 14 "8 FOOT" AND 14 X 14 "10 FOOT"ASSEMBLIES
A Document type:
Design report FRAMATOME ANP 10, Rue Juliette Récamier 69 456 LYON CEDEX 06 Class NUCLEAR FUEL No. of pages: 25 F
DESIGN & SALES No. of annexes:
Title I 7 SAFETY/CRITICALITY STUDY OF FCC3v2 CONTAINERS 14 x 14 "8 foot" and 14 x 14 "10 foot"ASSEMBLIES L _J KEY WORDS: ROD - CONTAINER - CRITICALITY - TRANSPORT - U02 Distribution I I I I I I I I I I Purpose of GED For info. For info. For info. For action distribution No. of copies PDF 1 pdf 1 pdf 1 pdf 1 + 1 pdf 29/10 A I I I I First issue CFC 2004 VALIDITY REV DATE AUTHOR VERIFICATION MODIFICATIONS - OBSERVATIONS APPROVAL STATUS CLASSIFICATION: INTERNAL IDENTIFICATION NUMBER U.D.:
l1 F 11F 11 IWl DC 111 11I 0 1 1 0 6 E0 Non-proprietary version FF010 Rév. 1
A N° FF/DC/01106 E0 FRAMATOME ANP REV. A PAGE 1 / 25 MODIFICATIONS REVISION DATE PAGE PURPOSE A 29/10/2004 First issue FRAMATOME ANP - NUCLEAR FUEL DESIGN & SALES FF018 Rév. 1
A N° FF/DC/01106 E0 FRAMATOME ANP REV. A PAGE 2 / 25 CONTENTS REFERENCES 3 LIST OF TABLES 4 LIST OF FIGURES 5 1 INTRODUCTION 6 2 DEFINITIONS AND CONVENTIONS 7 3 CODES AND QUALIFICATION 9 4 COMPUTATION AND MODELLING HYPOTHESES 10 4.1. Characteristics of the package 10 4.1.1. Package under Normal Transport Conditions (NTC) 11 4.1.2. Package under Accident Transport Conditions (ATC) 11 FRAMATOME ANP - NUCLEAR FUEL DESIGN & SALES 4.2. Characteristics of the neutron absorbing resin 11 4.2.1. Resin under Normal Transport Conditions (NTC) 12 4.2.2. Resin under Accident Transport Conditions (ATC) 12 4.3. Characteristics of the assemblies 12 4.3.1. Assembly under Normal Transport Conditions (NTC) 13 4.3.2. Assembly under Accident Transport Conditions (ATC) 13 5 METHODOLOGY AND RESULTS 14 5.1. Particular non-penalising conditions 14 5.2.Packages considered individually 14 5.2.1. Individual package under Normal Transport Conditions (NTC) 15 5.2.2. Individual package under Accident Transport Conditions (ATC) 15 5.3. An array of packages 16 5.3.1. Array of packages under Normal Transport Conditions (NTC) 16 5.3.2. Array of packages under Accident Transport Conditions (ATC) 17 5.3.3. Impact of the ejection of pellets 17 6 CONCLUSION 18 FF018 Rév. 1
A N° FF/DC/01106 E0 FRAMATOME ANP REV. A PAGE 3 / 25 REFERENCES
[1] 229 K 0302 : Conteneur pour 2 assemblages de combustible UO2 Modle 12 pieds - 14x14 "8 pieds" - 14x14 "10 pieds" Ensemble colis Caractéristiques liées la sûreté
[2] TRANSNUCLEAIRE 10373-B-1 rév 3 : Note de synthse sur la caractérisation de la résine FS69
[3] IPSN/DSMR/96-393 du 22/08/96 : Eléments nécessaires lexpertise des études des études de criticité des emballages chargés de matires fissiles.
[4] TS-R-1 (ST1, révisée) : Rglement de transport des matires radioactives Edition de 1996 (révisée)
Prescriptions Collection Normes de sûreté de lAIEA FRAMATOME ANP - NUCLEAR FUEL DESIGN & SALES
[5] TS-G-1.1 (ST-2) : Advisory Material for the IAEA Regulations for the Safe Transport of Radioactive Material Safety Guide IAEA Safety Standards Series
[6] FF DC 00817 : Etude de Sûreté-Criticité Conteneurs FCC3 et FCC4.
Assemblages 15x15 et 17x17 Assemblages 17x17XL, 16x16 et 18x18.
[7] FFRN/03/0268 : CRISTAL V0.2 Mise en production
[8] FF DC 00561 : Colis de transport de combustibles UO2 neufs Détermination des incertitudes appliquer aux études de criticité réalisées avec CRISTAL.
[9] TFJN DC 1403 : Conteneurs FCC3 et FCC4.
Synthses des Etudes de criticité.
Assemblages 15x15 et 17x17 Assemblages 17x17XL, 17x17XLR, 16x16 et 18x18.
FF018 Rév. 1
A N° FF/DC/01106 E0 FRAMATOME ANP REV. A PAGE 4 / 25 LIST OF TABLES Table 1: Characteristics of the packages 19 Table 2 : Characteristics of the assemblies 20 Table 3 : Composition of the resin 21 FRAMATOME ANP - NUCLEAR FUEL DESIGN & SALES FF018 Rév. 1
A N° FF/DC/01106 E0 FRAMATOME ANP REV. A PAGE 5 / 25 LIST OF FIGURES Figure 1 : Cross-section XY of package under NTC 22 Figure 2 : Cross-section XY of the package under ATC 23 Figure 3 : Half cross-section XY at pad, detail of the neutron cavity under NTC 24 Figure 4 : Cross-section XZ of the neutron cavity under ATC 25 FRAMATOME ANP - NUCLEAR FUEL DESIGN & SALES FF018 Rév. 1
A N° FF/DC/01106 E0 FRAMATOME ANP REV. A PAGE 6 / 25
- 1. INTRODUCTION Fresh UO2 fuel assemblies are transported in packages referred to as FCC3 version 2 for 14x14 "8 foot" and 14x14 "10 foot"design assemblies.
These packages are classified as Type II Fissile Industrial Packages according to the recommendations of the IAEA [4] and, as such, their design must guarantee subcriticality for an individual package and for a plurality of packages under Normal Transport Conditions (NTC) and Accident Transport Conditions (ATC), in compliance with IAEA guidelines [4].
The design of FCC packages consists in confining the fuel in a volume having a known cross-section, as small as possible, and ensuring that this geometry is maintained subsequent to regulatory tests. These tests are performed under Accident Transport Conditions (ATC), which determine dimensions, namely:
- 9 m drop,
- 1 m drop onto a 150 cm diameter spike, FRAMATOME ANP - NUCLEAR FUEL DESIGN & SALES
- thermal test at 800 °C for 30 minutes.
At the design stage, criticality studies were carried out using the APOLLO 1 - MORET III calculation diagram, while observing a subcriticality margin of I I for a plurality of packages. Changing over to the CRISTAL calculation tool and taking IAEA recommendations
[4] and [5] into account lead us to revise the initial studies for the regulatory configurations. The sensitivity studies carried out in study [9] have not been repeated; their conclusions remain applicable and are restated in § 5.1.
The purpose of this study is to verify that the safety-criticality criterion of Keff 0.95 is observed, including all uncertainties, for the transport of FCC3 version2 containers loaded with 14x14 "8 foot" and 14x14 "10 foot" assemblies under NTC and ATC in accordance with IAEA recommendations [4].
Document [8] defines the uncertainties to be applied with regard to the use of the CRISTAL form for the transport of fresh UO2 fuel.
FF018 Rév. 1
A N° FF/DC/01106 E0 FRAMATOME ANP REV. A PAGE 7 / 25
- 2. DEFINITIONS AND CONVENTIONS To make this report clearer and easier to understand, a list of the definitions and conventions is provided below:
Frame:
Fabricated structure with an inverted T-shaped cross-section used to support the assemblies during transport, this sheet-metal structure consists of a vertical core and a lower box section filled with neutron absorbing resin.
Doors:
Fabricated assembly with an L-shaped cross-section hinged on the frame. This sheet-metal structure is filled with neutron absorbing resin. On the inner faces of these doors and facing the assembly grids, there are recesses in which the metal pads used to hold the assemblies during transport, by clamping onto the grids, are located.
Neutron cavity:
Overall volume delimited by the metal sheets on the inside of the doors, the frame and the head FRAMATOME ANP - NUCLEAR FUEL DESIGN & SALES and foot plates.
Co-ordinate system:
The O X Y Z three-dimensional reference system is used (Figure 4 and Figure 5), where:
- origin O: is a point at the intersection of the plane of vertical symmetry of the neutron cavity (middle of the core), of the plane of longitudinal symmetry and of the plane that passes along the lower face of the metal sheet of the frame.
- axis OX: transverse axis, merging with the lower horizontal face of the metal sheet of the frame,
- axis OY: vertical axis passing along the plane of vertical symmetry of the neutron cavity,
- axis OZ: longitudinal axis.
Fissile section:
Square cross-section (plane XY) representing the fuel assembly with a chemical medium resulting from a calculation using APOLLO 2 in which the non-fissile components, other than the fuel rod cladding, are equated with water.
In the case of FCC3v2 packages, under accident conditions, it is the section of the neutron cavity, increased by the volume of the recesses for the pads.
FF018 Rév. 1
A N° FF/DC/01106 E0 FRAMATOME ANP REV. A PAGE 8 / 25 Moderator radius:
Radius of the moderator portion of an APOLLO 2 fissile cell, representing the fissile medium.
The moderator radius is calculated as follows:
I I Differential flooding:
Accident configuration in which only the neutron cavity is immersed in water (density = 1).
Total reflection:
Conditions at the limits (boundary conditions) applied to a computational 3D geometric configuration and which prevents any neutron leakage.
Array:
Three-dimensional arrangement of several packages. The array is surrounded by a 20-cm water FRAMATOME ANP - NUCLEAR FUEL DESIGN & SALES reflector (articles 681 and 682 of [4]). The array is referred to as network X x Y x Z" where:
- X: is the number of packages in direction X,
- Y: is the number of packages in direction Y,
- Z: is the number of packages in direction Z, Infinite array:
X Y Z array where X, Y and Z are infinite. This array is modelled by applying the conditions for total reflection to each of the faces of the package instead of the 20-cm reflector applied to the periphery of a network of finite dimensions.
FF018 Rév. 1
A N° FF/DC/01106 E0 FRAMATOME ANP REV. A PAGE 9 / 25
- 3. CODES AND QUALIFICATION Computation is carried out using:
- CIGALES version v2.0
- APOLLO 2 version 2.4.3
- MORET 4 version 4.A.6 These three codes are part of CRISTAL V0.2 and their use is validated [7].
A brief description of these codes is restated in report [8].
Use of the CRISTAL tool is qualified for the present study by applying an uncertainty of I I to the Keff calculated according to report [8]. In this report, all the reactivity values given take this uncertainty into account FRAMATOME ANP - NUCLEAR FUEL DESIGN & SALES FF018 Rév. 1
A N° FF/DC/01106 E0 FRAMATOME ANP REV. A PAGE 10 / 25
- 4. COMPUTATION AND MODELLING HYPOTHESES 4.1. Characteristics of the package The characteristics of the FCC3 version 2 package are restated below, and are similar to those of the FCC3 version 1 package used for transporting 15x15 and 17x17 assemblies, to which report [6] relates.
The package consists of a cylindrical steel shell with a horizontal axis, housing internal equipment comprising the following main components:
- an inverted T-shaped frame for receiving the assemblies, said T being filled with neutron-absorbing resin,
- two L-shaped doors filled with neutron-absorbing resin, said doors pivoting on axes linked to the frame and closing on the assemblies or on the rod boxes,
- two steel end plates: a two-part head plate and a foot plate, which serve to close the cavities.
FRAMATOME ANP - NUCLEAR FUEL DESIGN & SALES When assembled, the above components form two identical neutron cavities, in which the assemblies or the rod boxes to be transported are placed.
The neutron absorbing resin located inside the doors and the frame limits the interactions between the rods, whether they are from the same package or from different packages.
Furthermore, the resin provides thermal protection for the rods during the thermal test.
The only notable differences between version 2 and version 1 are:
- the section of the cavity: I I (mm x mm) instead of I I (mm x mm),
1111
- the pad recesses: height I I mm instead of I I mm, width I I mm (the 1111 length of the neutron cavity) instead of I I mm,
- the thickness of resin in the doors: I I mm instead of I I mm and I I mm at the longitudinal depression for the pads (resulting in a cavity with an external section identical to that of version 1).
The main characteristics of the package, taken from drawing [1] are restated in Table 1.
For this study, two-dimensional modelling is adopted, i.e. a I I mm long portion of package, including a pad attachment in its centre, and subjected to total reflection conditions at each end. This therefore amounts to modelling a package of infinite length.
FF018 Rév. 1
A N° FF/DC/01106 E0 FRAMATOME ANP REV. A PAGE 11 / 25 4.1.1. Package under Normal Transport Conditions (NTC)
Under normal conditions, the package is cylindrical (see Figure 1) and is modelled as follows:
1111I mm,
- a cylindrical shell with an external diameter of I
- a neutron cavity with an infinite length (see Figure 4).
- the recesses for the pads for holding the grids in place are modelled as a depression in the doors over the entire length of the cavity (see Figure 4),
- attachment of the pads in the resin of the doors is modelled by a steel block located alongside every I1111 I mm, The dimensions taken into account for modelling purposes are given in Figure 1, Figure 2, Figure 3, and Figure 4.
FRAMATOME ANP - NUCLEAR FUEL DESIGN & SALES 4.1.2. Package under Accident Transport Conditions (ATC)
The modelling adopted integrates the results of expert appraisal subsequent to the mechanical tests and the thermal study, i.e.:
- the neutron cavity is entirely detached from the cradle subsequent to one of the drops or the thermal test,
- the shell is radially crushed by I I mm on average over the entire length subsequent to the 9 m drop onto a flat surface, with localised crushing reaching a maximum of I 1111I mm, Therefore, under accident conditions, the package is modelled (see Figure 3) with a box-shaped steel shell, the dimensions of which are calculated so that it is located symmetrically about the neutron cavity so as to have identical neutronic interactions between the packages, irrespective of the faces considered.
We studied a rectangular shell I I mm x I I mm: in this case relatively realistic crushing of the shell, I I mm wide and I I mm high, is taken into account, which leads to clearances between the shell and the cavity of I I mm laterally and I I mm vertically.
The neutron cavity remains dimensionally unchanged relative to the normal conditions, but the composition of the resin is modified as indicated in § 4.2.2.
4.2. Characteristics of the neutron absorbing resin It is a polyester resin with a loading of approximately I I.
FF018 Rév. 1
A N° FF/DC/01106 E0 FRAMATOME ANP REV. A PAGE 12 / 25 4.2.1. Resin under Normal Transport Conditions (NTC)
The characteristics of the resin originate from [2]; the values taken into account in the modelling are restated in Table 3.
4.2.2. Resin under Accident Transport Conditions (ATC)
After the thermal test (800 °C for 30 mn), the characteristics of the resin are modified.
Report [2] gives envelope values to be taken into account in the criticality studies; the modelling adopted is as follows:
- I I,
- I I.
4.3. Characteristics of the assemblies FRAMATOME ANP - NUCLEAR FUEL DESIGN & SALES The characteristics of the assemblies are restated in Table 2. Only the fissile part of the rods is taken into account in the two-dimensional modelling.
The assemblies are modelled complete with all rods identical, possible specific rods (rods treated with gadolinium, depleted uranium rods, stainless steel rods, zirconium alloy rods) are replaced by UO2 rods.
For the computation of moderation, the rods are assumed to be arranged uniformly over the entire fissile section.
The density of the pellets is taken to be equal to 100 % of the theoretical density, i.e.
10.96 g/cm3.
The hollows and the bevels of the pellets are not taken into account, the fissile column is modelled in the form of a cylinder with the maximum diameter of the pellets over the entire fissile height and the cladding is modelled at its minimum diameter, with no clearance between the pellet and the cladding. This modelling is conservative, as demonstrated in report [9], and complies with the guidelines [6].
The material taken into account for the cladding is Zirconium, a material that is neutronically transparent and is therefore conservative, from the safety point of view, relative to the various cladding materials containing isotopes in the Zirconium alloys.
Enrichment equal to 5 % U235 FF018 Rév. 1
A N° FF/DC/01106 E0 FRAMATOME ANP REV. A PAGE 13 / 25 4.3.1. Assembly under Normal Transport Conditions (NTC)
The assembly is modelled as follows:
- the cross-section of the assembly is maintained, the fissile section is the normal cross-section of the assembly,
- the assembly is in contact with the frame, which leaves a II mm clearance relative to the doors, 4.3.2. Assembly under Accident Transport Conditions (ATC)
The modelling adopted integrates the results of expert appraisal subsequent to the mechanical tests and the thermal study, i.e.:
- the cross-section of the neutron cavity remains unchanged,
- the assembly has a compacted cross-section, FRAMATOME ANP - NUCLEAR FUEL DESIGN & SALES
- there may be a slight increase in the cross-section of the assembly on the end fuel stage, at most, in the event of an axial drop.
On account of the above observations, the modelling adopted for verifying the safety/criticality criteria is as follows:
- the cross-section of the assembly is expanded to the cross-section of the neutron cavity (I I mm x I I mm) without expanding into the pad recesses.
However, to verify that the subcriticality of the packages is observed, even with quite unrealistic hypotheses, the case of an assembly, of infinite length, expanded to the entire section of the neutron cavity, including the pad recesses is studied.
The compacting of the cross-section is not taken into account, since it tends to reduce the reactivity of the assembly, but the case of a non-expanded assembly is studied to obtain a very realistic value of the reactivity of the packages.
For the purposes of this report, the three configurations will be identified as follows:
- I I: non-expanded assembly with a I I x I I mm cross-section,
- I I: assembly expanded to I I x I I mm without penetrating into the pad recesses, bounding value resulting from the regulatory tests,
- I I + pads: assembly expanded to I I x I I mm and into the pad recesses, a penalising value taken for information purposes.
FF018 Rév. 1
A N° FF/DC/01106 E0 FRAMATOME ANP REV. A PAGE 14 / 25
- 5. METHODOLOGY AND RESULTS Computation is performed, for each design, for an individual package and a plurality of packages in normal transport configurations (NTC) and accident transport configurations (ATC). In accident configurations, two variants are studied:
- differential flooding,
- water-filled package.
5.1. Particular non-penalising conditions During the criticality studies performed at the design stage [9], we studied the impact of different parameters and particular configurations. We demonstrated the absence of any impact and the non-penalising nature of the following particular configurations:
- mist conditions: no reactivity peak occurs,
- pellets of minimum diameter: this case is covered by pellets of maximum diameter, FRAMATOME ANP - NUCLEAR FUEL DESIGN & SALES
- impact of the reinforcing ribs on doors: no significant impact on the reactivity in comparison to the calculations performed without ribs; therefore, the ribs are not modelled,
- impact of tolerances and geometric shapes: the tolerances of the sheet metal, rounded edges and possible shrinkage during the pouring of the resin do not have a significant impact and therefore shall not be taken into account,
- partial differential flooding: the case of partially immersed assemblies is covered by the case of fully immersed assemblies,
- partial slipping of the rods: this configuration does not have a significant impact on the reactivity of the packages.
The accident configuration in which the neutron cavity is off-centre, thereby coming closer to the neighbouring packages, is dealt with in report [6], which shows that this configuration does not have a significant impact.
Since the above configurations are not penalising, they are not studied further in this report.
5.2. Packages considered individually The individual package, whether damaged or not, must be subcritical with total reflection by a 20-cm layer of water around the containment envelope (articles 677 and 678 of [4]).
The subcriticality margin to be observed for the individual package is 5000 pcm:
Keff 0.95 (appendix VII.38 of [5]), including all uncertainties.
FF018 Rév. 1
A N° FF/DC/01106 E0 FRAMATOME ANP REV. A PAGE 15 / 25 5.2.1. Individual package under Normal Transport Conditions (NTC)
The configuration studied is: the undamaged two-dimensional package (cylindrical modelling) filled with water and surrounded by a reflector consisting of 20 cm of water; modelling of the package is described in § 4, Figure 1, Figure 3 and Figure 4.
The undamaged individual package amply complies with the subcriticality margin of Keff 0.95.
5.2.2. Individual package under Accident Transport Conditions (ATC)
The configuration studied is: the damaged two-dimensional package (rectangular modelling) surrounded by a reflector consisting of 20 cm of water; modelling of the package is described in § 4.
The space between the cavity and the shell is:
- either filled with water: package in water-filled configuration, FRAMATOME ANP - NUCLEAR FUEL DESIGN & SALES
- or empty: package in differential drainage configuration.
The assembly is studied in the 3 configurations described in § 4.3.2.
The results of the calculations, provided in the table below, show that the individual two-dimensional damaged package amply complies with the subcriticality margin of Keff 0.95, I I, even when penalising hypotheses on the expansion of the rod array and an infinite length.
Proprietary table FF018 Rév. 1
A N° FF/DC/01106 E0 FRAMATOME ANP REV. A PAGE 16 / 25 5.3. An array of packages An array of packages must remain subcritical, with the array of packages surrounded on all sides by a 20-cm layer of water (articles 681 and 682 of [4]).
The subcriticality margin to be observed for an array of packages is 5000 pcm:
Keff 0.95 (appendix VII.38 of [5]), including all uncertainties.
5.3.1. Array of packages under Normal Transport Conditions (NTC)
If N is the number of packages to be transported, 5N undamaged packages must be subcritical without there being anything between the packages (article 681 of [4]).
The configuration studied is an infinite array of two-dimensional undamaged packages (cylindrical modelling - the modelling of the package is described in § 4). Conditions of total reflection are applied to all the faces of the package. The space between the cavity and the shell is:
FRAMATOME ANP - NUCLEAR FUEL DESIGN & SALES
- either full of water: package in water-filled configuration,
- or empty: package in differential flooding configuration.
The results of the calculations, provided in the table below, show that an infinite array of two-dimensional undamaged packages amply complies with the subcriticality margin of Keff 0.95, I I. The number N is therefore infinite under normal transport conditions.
Proprietary table FF018 Rév. 1
A N° FF/DC/01106 E0 FRAMATOME ANP REV. A PAGE 17 / 25 5.3.2. Array of packages under Accident Transport Conditions (ATC)
If N is the number of packages to be transported, 2N damaged packages must be subcritical, with moderation between the packages (article 681 of [4]).
The configuration studied is: an array of two-dimensional damaged parcels (rectangular modelling); modelling of the package is described in § 4; in this configuration, two variants are studied:
- I I
- I I The results of the calculations, provided in the table below, show that an array of two-dimensional damaged packages complies with the subcriticality margin of Keff 0.95 with a shell crushed to a realistic extent (920 mm x 677 mm) and even with a very hypothetical total expansion of the rod array.
The number N is infinite under accident transport conditions.
FRAMATOME ANP - NUCLEAR FUEL DESIGN & SALES The I I configuration is a highly penalising configuration that generates an increase in reactivity of about 6000 pcm relative to the I I Proprietary table 5.3.3. Impact of the ejection of pellets As stated in report [6], during the criticality studies carried out at the design stage, the possible ejection of pellets inside the neutron cavity was studied.
The conclusions remain valid, since the studies were carried out applying conservative hypotheses on the expansion of the network over the entire height of the assemblies.
The number of rods per assembly that can eject all their pellets into the cavity is I I rods.
FF018 Rév. 1
A N° FF/DC/01106 E0 FRAMATOME ANP REV. A PAGE 18 / 25
- 6. CONCLUSION In this study, we have verified that the safety/criticality criteria of FCC3 version 2 for the transport of fresh UO2 fuel assemblies:
- 14 x14 "8 foot" enriched to 5 % with U235,
- 14 x14 "10 foot" enriched to 5 % with U235, the main characteristics of which are as follows:
- density 10.96 g/cm3 (100 % of the theoretical density),
- full assembly: the missing UO2 rods must be replaced with rods treated with gadolinium, rods containing depleted uranium or a metal material, or solid rods made of a metal material (materials such as graphite and beryllium are strictly prohibited) so as not to increase moderation of the assemblies, FRAMATOME ANP - NUCLEAR FUEL DESIGN & SALES
- the uranium can originate from reprocessing, since the U234 and the U236 present in RRU are neutron poisons that reduce the reactivity of the assemblies.
The section of the neutron cavity is I I (mm x mm) with two continuous pad recesses I I (mm x mm) in section.
The length of the assemblies is only limited by the length of the cavity.
The longitudinal wedging of the assemblies is not necessary from point of view of criticality.
The packages can only contain one or two assemblies of the same design and maximum enrichment:
The transport of assemblies equipped with clusters is covered by this study, since the clusters contribute a neutron-absorbing poison to the assembly, while reducing the moderation of the assemblies.
The number N of packages, as defined in articles 681 and 682 of [7], that can be transported from the point of view of safety/criticality, serves to determine the SAFETY/CRITICALITY INDEX (SCI), as defined in article 528 of [7], i.e.:
SCI = 50/(min. (NNTC; NATC))
The number N for the transport of 14 x14 "8 foot" and 14 x14 "10 foot" assemblies, is infinite under NTC and ATC, therefore ISC = 0.
FF018 Rév. 1
A N° FF/DC/01106 E0 FRAMATOME ANP REV. A PAGE 19 / 25 TABLE 1 : Characteristics of the packages Proprietary table FRAMATOME ANP - NUCLEAR FUEL DESIGN & SALES FF018 Rév. 1
A N° FF/DC/01106 E0 FRAMATOME ANP REV. A PAGE 20 / 25 TABLE 2 : Characteristics of the assembliess Proprietary table FRAMATOME ANP - NUCLEAR FUEL DESIGN & SALES FF018 Rév. 1
A N° FF/DC/01106 E0 FRAMATOME ANP REV. A PAGE 21 / 25 TABLE 3 : Composition of the resin Proprietary table The minimum density of the resin under Normal Transport Conditions (NTC) is taken to be FRAMATOME ANP - NUCLEAR FUEL DESIGN & SALES I I, value derived from the mean measurement of the product, I I, reduced by 3 standard deviations.
The composition of the resin under Accident Transport Conditions (ATC) is obtained by I I FF018 Rév. 1
A N° FF/DC/01106 E0 FRAMATOME ANP REV. A PAGE 22 / 25 FIGURE 1: Cross-section XY of package under NTC Proprietary drawing FRAMATOME ANP - NUCLEAR FUEL DESIGN & SALES FF018 Rév. 1
A N° FF/DC/01106 E0 FRAMATOME ANP REV. A PAGE 23 / 25 FIGURE 2: Cross-section XY of the package under ATC Proprietary drawing FRAMATOME ANP - NUCLEAR FUEL DESIGN & SALES FF018 Rév. 1
A N° FF/DC/01106 E0 FRAMATOME ANP REV. A PAGE 24 / 25 FIGURE 3: Half cross-section XY at pad, detail of the neutron cavity under NTC Proprietary drawing FRAMATOME ANP - NUCLEAR FUEL DESIGN & SALES FF018 Rév. 1
A N° FF/DC/01106 E0 FRAMATOME ANP REV. A PAGE 25 / 25 FIGURE 4: Cross-section XZ of the neutron cavity under ATC Proprietary drawing FRAMATOME ANP - NUCLEAR FUEL DESIGN & SALES FF018 Rév. 1