MASURCA PLUTONIUM FUEL ELEMENTS FABRICATION

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MASURCA PLUTONIUM FUEL ELEMENTS FABRICATION
by R. LESSER, J.F. GUEUGNON, M. MAURICE and J. VAANE
European Atomic Energy Community - EURATOM
Joint Nuclear Research Center - Karlsruhe Establishment (Germany)
European Institute for Transuranium Elements
Brussels, October 1968 - 294 Pages - 49 Figures - FB 400
Between January and October 1966. 2115 Mascurca fuel elements containing 175 kg
plutonium were fabricated in the Institute for Transuranium Elements. Karlsruhe. Two sorts
of plutonium metal were used, containing 8.4 and 3.8% Pu-2-40 respectively. The elements
were required to be 101.6 and 203.2 mm long and have an outer diameter of 12.7 mm.
Each element consists of a fine steel con and a core of a plutonium alloy with depleted
EUR 3663 e
MASURCA PLUTONIUM FUEL ELEMENTS FABRICATION
by R. LESSER, J.F. GUEUGNON. M. MAURICE and J. VAANE
European Atomic Energy Community - EURA 1 OM
Joint Nuclear Research Center - Karlsruhe Establishment (Germany)
European Institute for Transuranium Elements
Brussels, October 1968 - 294 Pages - 49 Figures - FB 400
Between January and October 1966. 2115 Mascurca fuel elements containing 175 kg
plutonium were fabricated in the Institute for Transuranium Elements. Karlsruhe. Two sorts
of plutonium metal were used, containing 8.4 and 3.8% Pu-240 respectively. The elements
were required to be 101.6 and 203.2 mm long and have an outer diameter of 12.7 mm.
Each element consists of a fine steel can and a core of a plutonium alloy with depleted uranium and a little Iron. The composaion of lhe quality with 8.4% Pu-240 is 25 wt. %
Pu. I wt. % Fe and 74 wt. % U. and of the quality with 3.8 %0 24 wt. % Pu.
1 wt. % Fe and 75 wt. % U.
The original metals were first melted together in a vacuum-induction furnace. The
alloy was then cast in rod form in a centrifugal furnace, the rods were machined on a lathe
ana placea tn cens plugged at one end. After decontamination of the open end. insertion
of the second plug and welding with an electron beam unit, various inspections were
carried out Including a lealctightness Inspection with a helltest apparatus and a check on
the fissile material by spontaneous neutron counting.
The finished elements met the specifications. The plutonium losses were about 0.1 %
of the quantity used. A staff of 22 was directly engaged in the fabrication. The labour-
time was 1.79 man/day per element. Special attention was paid to work organization and
radiation protection.
uranium and a little bon. The composition of the quality with 8.4% Pu-240 Is 25 wt. %
Pu. 1 wt. % Fe and 74 wt. % U. and of the quality with 3.8 %0 24 wt. % Pu.
1 wt. % Fe and 75 wt. % U.
The original metals were first melted together in a vacuum-induction furnace. The
alloy was then cast in rod form in a centrifugal furnace, the rods were machined on a lathe
and placed In cans plugged at one end. After decontamination of the open end. insertion
of the second plug and welding with an electron beam unit, various inspections were
carried out Including a lealctightness Inspection with a helltest apparatus and a check on
the fissile material by spontaneous neutron counting.
The finished elements met the specifications. The plutonium losses were about 0.1 %
of the quantity used. A staff of 22 was directly engaged in the fabrication. The labour-
time was 1.79 man/day per element. Special attention was paid to work organization and
radration protection. EUR 3663 e
EUROPEAN ATOMIC ENERGY COMMUNITY - EURATOM
MASURCA PLUTONIUM FUEL ELEMENTS FABRICATION
by
R. LESSER, J.F. GUEUGNON, M. MAURICE and J. VAANE
1968
Joint Nuclear Research Center
Karlsruhe Establishment - Germany
European Institute for Transuranium Elements SUMMARY
Between January and October 1966. 2115 Mascurca fuel elements containing 175 kg
plutonium were fabricated in the Institute for 1 ransuranium Elements. Karlsruhe. Two sorts
of plutonium metal were used, containing 8.4 and 3.8% Pu-240 respectively. The elements
were required to be 101.6 and' 203.2 mm long and have an outer diameter of 127 mm.
Each element consists of a fine steel can and a core of a plutonium alloy with depleted
uranium and a little iron. The composition of the quality with 8.4% Pu-240 is 25 wt. %
Pu. 1 wt. % Fe and 74 wt. % U. and of the quality with 3.8 %0 24 wt. % Pu
1 wt. % Fe and 75 wt. % U.
The original metals were first melted together in a vacuum-induction furnace. The
alloy was then cast in rod form in a centrifugal furnace, the rods were machined on a lathe
and placed in cans plugged at one end. After decontamination of the open end, insertion
of the second plug and welding with an electron beam unit, various inspections were
carried out Including a lealctightness inspection with a helltest apparatus and a check on
the fissile material by spontaneous neutron counting.
The finished elements met the specifications. The plutonium losses were about 0.1 %
of the quantity used. Λ staff of 22 was directly engaged in the fabrication. The labour-
time was 1.79 man/day per element. Special attention was paid to work organization and
radiation protection.
KEYWORDS
WELDING FUEL ELEMENTS
PLUTONIUM ALLOYS ELECTRON BEAMS
IRON ALLOYS LEAK DETECTORS
URANIUM ALLOYS FISSIONABLE MATERIALS
FUEL CANS PROMPT NEUTRONS
STAINLESS STEELS COUNTERS
VACUUM FABRICATION
INDUCTION SAFETY
FURNACES RADIATION PROTECTION
CASTING MASURCA PREFACE
The fabrication of the elements for MASURCA was carried out
by the Metallurgy Section of the European Transuranium
Institute in Karlsruhe. It should, however, be stressed that
colleagues from other sections of the Institute made important
contributions and played a remarkable part in the success of
the work.
Leading European fuel element manufacturing firms sent
engineers; some were present as observers, others cooperated
directly in solving various problems.
The Metallurgy Division of the Argonne National Laboratory was
of valuable assistance during the early work of developing
the centrifugal casting process. INDEX
1. INTRODUCTION II
2. DESCRIPTION OF ELEMENTS AND EXTENT OF DELIVERY 12
2.1 Construction- of Elements 1
2.2 Initial Quantity of Plutonium and Number of Elements 1
2.3 The Uranium-Plutonium-Iron Alloy2
2.3.1 Composition of the alloy
2.3.2 Fissile material content of the alloy 13
2.3.3 Core dimensions 14
2 Λ Various specifications
3. STARTING MATERIALS6
3.1 Plutonium
3.2 Uranium 18
3.3 Iron9
3.4 Cans
3.^.1 Fabrication and pretreatment 1
3.4.2 Tests
3.5 Plugs and Discs 22
4. DESCRIPTION OF THE FABRICATION PROCESS 23
4.1 Preparation of the Starting Materials
4.2 First Casting5
4.3 Secondg9
4.4 Processing of the Cast Rods 38
4.5 Element Assembly 40
4.6 Welding-Seal of Plugs2
4.7 Cap Grinding7
4.8 Density Check
4.9 Spontaneous Neutron Counting4.10 Final Controls and Packing 52
4.11 Waste 53
4.12 Calculation of the Fissile Material Content 54
4.13 Heat Treatment of an Element 56
5. CHEMICAL ANALYSIS 58
5.1 Plutonium Content 58
66 3.2 Iron Content
70 5.3 Carbont
5.4 Impurities 71
5.5 Conclusions 71
5.6 Mass Spectrornetric Isotope Analyses 73
6. RESULTS AND MATERIAL BALANCE-SHEET 75
6.1 Individual Castings Balance-Sheet 75
82 6.2 Material Balance-Sheet
7. PROBLEMS OF WORK ORGANIZATION 87
7.1 Materials and Plutonium Accounting 87
90 7.2 Time and Personnel Requirements
8. RADIATION PROTECTION 95
8.1 The Special Hazards of Plutonium 9
8.2 Responsibilities7
8.3 Safety Regulations and Working Methods8
8.4 Air Sampling . 100
8.5 Dose Measurements2
8.6 Alarm System3
8.7 Doses absorbed by the Personnel IO4
8.7.1 External dose IO
8.7.2 Air sampling results 105
8.7.3 Surface contamination6
8.7.4 Urine sampling7
8.8 Incidents 10
8.9 Determination of Particle Sizes of Active Dust
in Air IO9