A Review of Criticality Accidents A Review of Criticality Accidents

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27. First cycle extraction line equipment. The accident occurred in the lower disengagement section of the H-100 column ................................................................... 45 28. Storage container .............................................................................................................. 47 29. A simplified layout of Glovebox 13 ................................................................................. 47 30. Intended sequence for the transfer of ingots from and to Glovebox 13 ........................... 48 31. Actual order of ingot transfers from and to Glovebox 13. The solid lines represent the actions of operator A and the dotted lines the actions of operator B .......................... 49 32. Major components of the chemical-etching process ........................................................ 50 33. Sequence of alarms and duration that the radiation levels exceeded the alarm level (36 mR/h) ................................................................................................................. 52 34. Authorized and executed procedures ................................................................................ 54 35. The precipitation vessel in which the process criticality accident occurred..................... 55 36. The ratio of cylindrical to spherical critical masses of U(93)O F solutions, unreflected 2 2 and with water reflector, as a function of cylinder height to cylinder diameter ratio ....... 59 37. Critical masses of homogeneous water moderated U(93.2) spheres. Solution data appear unless indicated otherwise. The accidents are shown by numbered circles.......... 60 38. Critical masses of water-reflected spheres of hydrogen-moderated U(93), U(30.3), U(5.00), U(3.00), and U(2.00). The accidents are shown by numbered circles ............... 61 39. Critcial masses of homogeneous water moderated plutonium spheres. The points suggesting an intermediate curve apply to water reflected Pu(No ) solution with 3 4 1 N HNO and 3.1% 3 240Pu content. The accidents are shown by numbered circles ......... 62 40. The Oak Ridge National Laboratory uranium solution assembly showing the normal and detached positions of the central poison rod.............................................................. 71 41. Plutonium sphere partially reflected by tungsten-carbide blocks..................................... 74 42. Configuration of beryllium reflector shells prior to the accident 21 May 1946 ............... 75 43. Calculated fission rate for the 6.2-kg plutonium sphere ................................................... 76 44. Calculated total fissions vs. time for the 6.2-kg plutonium sphere .................................. 76 45. The Los Alamos Scientific Laboratory aquarium assembly machine employed for measurements of critical separation distances .................................................................. 77 46. FKBN and assembly involved in the 9 April 1953 accident ............................................ 78 47. Building B floor plan ........................................................................................................79 48. The Los Alamos Scientific Laboratory Lady Godiva assembly (unreflected enriched-uranium sphere) in the scrammed configuration ............................................... 81 49. Lady Godiva after the excursion of 3 February 1954 ....................................................... 82 50. Burst rod and several sections of Lady Godiva showing oxidation and warpage that accompanied the second accident, 12 February 1957 ...................................................... 83 xvi
51. MSKS and assembly involved in the 11 March 1963 accident ........................................ 84 52. Building B floor plan ........................................................................................................85 53. Approximate accident configuration of the FKBN vertical lift assembly machine and core............................................................................................................................. 87 54. FKBN-2M building layout ............................................................................................... 90 55. FKBN-2M experimental layout ........................................................................................ 90 56. Accident configuration ..................................................................................................... 91 57. Calculated power history for the accident ........................................................................ 92 58. Removal of the main core of the assembly from the lower copper hemishell reflector ... 92 59. The destructive excursion in BORAX, 22 July 1954 ....................................................... 96 60. Photograph of the SF-7 control and experimental rooms where the first accident occurred ............................................................................................................ 100 61. Mockup of the accident configuration for the 26 May 1971 accident............................ 102 62. The LASL Honeycomb assembly machine. The movable section (right) is in the withdrawn position and the aluminum matrix is only partially loaded .......................... 105 63. Energy model computation of power and energy release vs time. The initial reactivity is 1.2 $ above delayed critical. Neutron lifetime values are 10-8 , 10-6 , and 10-4 seconds. The bottom panel shows the corresponding curves of reactivity vs time ....................... 108 64. Energy model computation of power vs time. The initial reactivity is 1.0 $ above delayed critical. Neutron lifetime values are 10 -8 , 10 -6 , and 10 -4 seconds. The bottom panel shows the corresponding curves of reactivity vs time .......................................... 109 xvii
Page 1 and 2: LA-13638 Approved for public releas
Page 3 and 4: A Review of Criticality Accidents 2
Page 5 and 6: PREFACE This document is the second
Page 7 and 8: Tom Jones was invaluable in generat
Page 9 and 10: C. OBSERVATIONS AND LESSONS LEARNED
Page 11: FIGURES 1. Chronology of process cr
Page 15 and 16: A REVIEW OF CRITICALITY ACCIDENTS A
Page 17 and 18: 3 Black Sea Baltic Sea Obninsk Norw
Page 19 and 20: North Atlantic Ocean Irish Sea Wind
Page 21 and 22: 1. Mayak Production Association, 15
Page 23 and 24: time of the accident. However, the
Page 25 and 26: determined by a radiation control p
Page 27 and 28: consequences of this accident, the
Page 29 and 30: Figure 10. Drum in which the 1958 Y
Page 31 and 32: The entire plutonium process area h
Page 35 and 36: During the next shift, radiation sa
Page 37 and 38: 9. Siberian Chemical Combine, 14 Ju
Page 39 and 40: The accident investigation determin
Page 41 and 42: 10. Hanford Works, 7 April 1962 18,
Page 43 and 44: heater and stirrer were turned off
Page 45 and 46: vessel 64-A was added. The dissolut
Page 47 and 48: additional reflection afforded by t
Page 49 and 50: 15. Electrostal Machine Building Pl
Page 53 and 54: ased on a radiation survey, that th
Page 55 and 56: 0.5 m 0.5 m 0.5 m 0.5 m 3.0 m 1.4 m
Page 57 and 58: The investigation identified severa
Page 59 and 60: 19. Idaho Chemical Processing Plant
Page 61 and 62: 20. Siberian Chemical Combine, 13 D
Page 63 and 64:
To Glovebox 6 7 8 6 From Glovebox 6
Page 65 and 66:
on a 0.4 m square pitch grid. The b
Page 67 and 68:
competing reactivity effects proved
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Figure 35. The precipitation vessel
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B. PHYSICAL AND NEUTRONIC CHARACTER
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Material Fissile Mass: Fissile mass
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235 U Spherical Critical Mass (kg)
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Table 10. Accident Fission Energy R
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• Accidents in shielded facilitie
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• Senior management should be awa
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Table 11. Reactor and Critical Expe
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3. Oak Ridge National Laboratory, 2
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5. Oak Ridge National Laboratory, 3
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eflector of 236 kg when he noticed
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3. Los Alamos Scientific Laboratory
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At the equatorial plane, the two ha
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Figure 48. The Los Alamos Scientifi
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Figure 50. Burst rod and several se
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On 11 March 1963, the facility chie
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13. Chelyabinsk-70, 5 April 1968 57
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14. Aberdeen Proving Ground, 6 Sept
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completed the construction of the l
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C. MODERATED METAL OR OXIDE SYSTEMS
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63,65,66, 67 4. Chalk River Laborat
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7. Centre dÉtudes Nucleaires de Sa
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a technician prescribing the loadin
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the room to drain the water out of
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In the final experiment, the critic
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III. POWER EXCURSIONS AND QUENCHING
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Figure 64. Energy model computation
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References 1. Stratton, W. R. A Rev
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50. Paxton, H. C. “Godiva Wrecked
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92. Stone, R. S., H. P. Sleeper, Jr
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criticality accident: The release o
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prompt criticality: State of a fiss
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1. Mayak Production Association, 15
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Page 139 and 140:
Page 141 and 142:
Page 143 and 144:
9. Siberian Chemical Combine (Tomsk
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13. Siberian Chemical Combine, 2 De
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15. Electrostal Machine Building Pl
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Page 153 and 154:
19. Idaho Chemical Processing Plant
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21. Novosibirsk Chemical Concentrat
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