and storage of plutonium

Transcription

1 IAEA-TECDOC-766 Safe handling, transport and storage of plutonium Proceedings of a Technical Committee meeting held in Vienna, October 1993 INTERNATIONAL ATOMIC ENERGY AGENCY /A> October 1994

2 The IAEA does not normally maintain stocks of reports in this series. However, microfiche copies of these reports can be obtained from INIS Clearinghouse International Atomic Energy Agency Wagramerstrasse

3

4 FOREWORD Plutonium inventories and utilization rates worldwide are growing. It is important for nuclear power programmes everywhere that no incidents or accidents with plutonium occur.

5 In preparing this document EDITORIAL NOTE

6 CONTENTS Summary of the Technical Committee meeting.. Some safety aspects related to MOX fuel fabrication in Belgium... 11

7 SUMMARY OF THE TECHNICAL COMMITTEE MEETING INTRODUCTION The IAEA estimates that

8 Ongoing efforts with new processes and improved procedures continue to reduce radiation exposure. This

9

10 SOME SAFETY ASPECTS RELATED

11 TABLE II. TYPICAL ISOTOPIC COMPOSITIONS 0F Pu (w/o) Isotope A B (gas-graphite reactor) C (LWR) D (LWR) E (LWR recycled) Pu Pu Pu O.O Pu Pu Taking into account

12 TABLE III. TYPICAL ISOTOPIC COMPOSITION Pu ± 0.5 Pu ± 0.9 Pu ± 1.2 Pu ± 0.5 Pu ± 0.5 Am ± 0.4 the materials, due to the high temperature of the articles or packages and containers to be manipulated. On the other hand, the n-activity coming not only from spontaneous fissions, but also from alpha-n reactions with the oxygen present in the oxides, has increased, thus generating higher neutron dose rates. In order to protect the personnel, more shielding is necessary and special attention has to be paid to neutron dosimetry. From Tables II and III it can also be seen that the 241 Pu content is raised, giving a faster growth

13 Silo Dust collecting unit Vibrating tube Transfer

14 25 r VI 4\J J5 U * " 1 10 c o "3 ' n - ; / e _ ' / \ 1

15

16 IS E 14?- -S c c re - % 13 Ï" y Delivery nr FIG.

17 water-

18

19 SAFETY PRINCIPLES FOR PLUTONIUM FACILITIES IN FRANCE J.P. MERCIER Institut

20 French experience

21 protection from ionizing radiation

22 originate from

23 Furthermore, plutonium dioxide storage container drop tests have been carried out; these tests have made it possible to demonstrate that the container and its jacket remain leaktight after

24 4.2. Experience relating

25

26 5. CONCLUSION In France, the plutonium facilities in operation or under construction are relying on a very extensive experience accumulated over the past 35 years. Feedback is considered to be very important in the design, the surveillance and the control of the process, with a view to the continuous improvement of safety. Reduced average exposure of staff and reduced releases of liquid and gaseous effluent demonstrate the effectiveness of this safety feedback.

27 FRENCH ENGINEERING DESIGN RULES FOR SAFE HANDLING

28 In practice,

29 2.2. Ventilation The ventilation design will take into account

30 If a criticality accident may occur because of simultaneous occurrence of two anomalies, it must be shown that: the two anomalies are strictly independent,

31

32 Primary containment crossing operations Primary containment may be crossed or removed for: introducing material into process equipment and evacuating process products and byproduct

33 contamination monitoring of the exhaust air detection of radioactive material in the cooling or heating networks. Mechanical process equipment Mechanical process equipment or unwelded chemical equipment (containing liquid, gaseous or powder radioactive material) may have a limited tightness. Complementary devices (air current, etc.) will

34 that

35 To these ventilation families correspond ventilation networks with

36 Contamination hazard

37 Surface contamination control The alpha, beta/gamma emitting nuclides will

38 Provisions for design Provisions

39 Tanks with unsafe geometry

40 Hydrazine Reagent vessel containing hydrazine

41 no safety related incident has been reported; performances of process are very satisfactory; irradiation

42 OPERATIONAL SAFETY

43 conversion into Pu0 2 powder by oxalic precipitation and calcination in oxygen, conditioning the powder in packaged units then in welded cases and containers for interim storage, placing in transportation casks and plutonium shipping. These processing steps are accompanied by entry and exit accountancy statements, as well as contractual analyses of final product quality. Plutonium's physical properties (radioactivity, fission capacity, calorific strength, radiolysis

44 monitored continuously (activity, flow rate), for both main process ventilation stack and ventilation outlet of zones accessible to personnel. Also, non-stop monitoring

45 All classed workers on the Site are equipped with this case. The site's dosimetry laboratory

46

47 6. CONCLUSION Applying the principles developed above at La Hague enables production at the nominal throughput

48 SAFETY OF PLUTONIUM SHIPMENTS IN AND FROM FRANCE' C. RENARD, F. MATHIEU Institut de protection et de sûreté nucléaire, Fontenay-aux-Roses B. DESNOYERS Cogéma, Vélizy-Villacoublay P. MALESYS Transnucléaire Paris France Abstract Plutonium extracted from irradiated fuel at reprocessing plants is used in the manufacture of fresh fuel

49 Plutonium fuel production centres supplied with plutonium produced in France are located

50 For maritime shipment, France applies the International Maritime Dangerous Goods code (IMDG)

51 execution

52 For

53 AA-227 container AA-303 cartridge can SS5S5SH3

54 all

55 Orifice SECTION Orifice

56 Under these conditions, the maximum weight on the ground contributed by the cask is 1.1 t/m 2 in a vertical utilization position. Safety principles

57 Over FS-67

58 empty packaging loaded packaging 2

59 maximum weight

60 empty packaging

61 RD-26 packaging (Fig. FIG. 7. RD-26 packaging.

62 all gaskets of this containment are doubled in order to allow the checking of leaktightness after loading (testing

63

64 outer envelope. These layers are maintained by a steel framework including ISO standard corners for tie-down on trailer. At each end, the packaging is protected by 40 cm thick shock absorbing covers.

65 addition to these facilities, the SCPRI (Central Service for Protection against Ionizing Radiation}

66 CRITICALITY ACCIDENTS

67 The most obvious and significant characteristic of the criticality accidents that have occurred

68 (1) chemical form: uranyl nitrate solution (93%

69 2.9. LASL, Dec When

70 3. DERIVATION OF A SIMPLIFIED MODEL TO ESTIMATE THE MAXIMUM TOTAL FISSION NUMBER

71 p add f 10" \ ) -X 5^^Sr^ JX_X T ö = 10 -u 5X ZX ' " Vs (cm3) Fig-1 Relation between reactivity

72 The following

73 figure are also shown the conventional evaluation curves obtained from other researchers' publications [7-9].

74 CIVIL PLUTONIUM HANDLING EXPERIENCE

75 ^-m f>

76 DIMENSIONS IN HM POS. DESIGNATION I 2 3 HEAD BEAM 4

77 CHLORINE POWDER OXIDES NaCJ-CsCl SALTS CHLORINATION IN MELT NaCl-CsCl REGENERATION SALT MELT CONCENTRACE (FOR STORAGE) OXIGEN4CHLORINE*ARGON ELECTROLISIS WASTE GASES GA:.SES SALTS

78 U-Pu OXIDE GRANULATED FUEL CLADDING ASSEMBLED WEIGHING OF EMPTY CLADDING MAKING FUEL PORTION FOR FE, CHARGING INTO CLADDING WEIGHING

79 WRAPPER WITH TAIL 1 BOX WITH 36 PERIPHERAL FE 3 BOXES WITH 91 CENTRAL FE MOUNTING

80 In general these goals were achieved. About 1 tonne of granulated fuel with Pu of different isotopic composition

81 BOR-60, BN-600 reactors

82 8. O.V.Skiba, Yu.P.Savochkin, A.V.Bychkov et al. Technology of Pyroelectrochemi- cal Reprocessing and Production

83 PLUTONIUM PRODUCTION AND STORAGE AT BNFL SELLAFIELD, UNITED KINGDOM B. LEIGH British Nuclear Fuels pic, Sellafield, Cumbria, United Kingdom Abstract Plutonium has been safely produced and stored at BNFL Sellafield for over 40 years. Although the basic chemical processes have not significantly changed throughout that time, the designs of

84

85 A decision was taken to replace the facility with a continuous process plant capable of operating until

86

87 interference fit stainless steel lid which was then welded using an overlapping resistance weld method. Proof testing

88 all air movement in the stores. Spare fan units and motors are also held separate from the store

89 conditions

90

91

92 2.4. The environment - disposal The regulation of matters involving the return of plutonium to the environment is the responsibility

93 Assessment Principles

94

95 expected that special training would

96 and

97 post-war weapons programmes when safety priorities were different to those expected now. De-commissioning of such facilities is fraught with difficulties, particularly when there is the possibility that old ventilation systems may be disturbed. It will often be necessary to re-engineer systems to modern standards before work can proceed.

98 Appendix 1 A TYPICAL LICENCE CONDITION 1. The licensee shall make and implement adequate arrangements for the periodic and systematic review

99 Appendix 2 LICENCE CONDITION OBJECTIVES CONDITION 1 INTERPRETATION The purpose

100 CONDITION

101 ensure that the licensee justifies safety during design, construction, manufacture, commissioning, operation,

102 CONDITION

103 CONDITION 32 ACCUMULATION OF RADIOACTIVE WASTE The purpose of this licence condition is to ensure that the production rate and accumulation

104 PLUTONIUM TRANSPORT: THE

105 In general the products of reprocessing, like irradiated fuel flasks require the most stringently designed packagings, plutonium requires packages which have

106 cylinder

107 transport package outers. It was recognised that these packages were therefore capable of sustaining much greater damage, even though it is clear that packages tested to the IAEA Regulations will ensure that the radiological consequences of the majority of potential accidents will

108 package and designed and constructed a 4500 te target of steel and reinforced concrete. A special track was built, enabling the prototypes to be carried by a rocket-powered sled. Following a successful side-on impact at the prescribed speed at full scale, the package was then subjected to the rest of the NRC criteria of crush, punch and slash tests, fire and immersion, and BNFL are satisfied with the results so far. Further development has been suspended because of the uncertainties in the final regulatory position regarding these shipments although it is worth noting ACTRAM's comment "the NRC tests were likely to prove unduly severe,

109

110 During road transports

111 (total radiation from plutonium for example is in the order of two thirds neutrons and one third gamma),

112 by BNFL does take pride in its enviable safety record for the transportation of plutonium

113 LIST

114 Leigh,