1 / 25

MEDICAL ASPECTS OF CRITICALITY ACCIDENT IN SAROV, RUSSIA

MEDICAL ASPECTS OF CRITICALITY ACCIDENT IN SAROV, RUSSIA. Module XIX. What is a criticality accident?. An unplanned event, when the neutron balance at fission is distorted and the nuclear chain reaction becomes uncontrolled. Neutron balance. Neutrons released in fission may be lost by

glynn
Download Presentation

MEDICAL ASPECTS OF CRITICALITY ACCIDENT IN SAROV, RUSSIA

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. MEDICAL ASPECTS OF CRITICALITY ACCIDENT IN SAROV, RUSSIA Module XIX

  2. What is a criticality accident? • An unplanned event, when the neutron balance at fission is distorted and the nuclear chain reaction becomes uncontrolled Module Medical XIX-24

  3. Neutron balance • Neutrons released in fission may be lost by • escaping the container or • being absorbed by non-fissile materials Module Medical XIX-24

  4. 1 - fixed part 2 - fissionable material (U) 3 - reflector (copper) 4 - moving mechanism Scheme of critical assembly Module Medical XIX-24

  5. Accident circumstances in Sarov, 17 June 1997 • 10:50: during construction of critical assembly, component from upper copper reflector suddenly slipped from technician’s rubber gloved hand and • fell onto lower part of assembly, already constructed and containing enriched uranium core Module Medical XIX-24

  6. Accident circumstances • Point of criticality exceeded, flash of blue light and wave of heat • 10.52: technician informed supervisors and colleagues • he thought his exposurewould be fatal Module Medical XIX-24

  7. Accident consequences • First few minutes after criticality excursion he was fully conscious and active • 10.59: initial direct measurements of neutron induced gamma radiation emitted by radionuclides in his body (mainly by 24Na) indicated a whole body dose of about 10 Gy Module Medical XIX-24

  8. Accident management • 11.00-11.09: building evacuated • 11.10: nurse arrived - Accident Report Card completed • 11.20: ambulance to local hospital Module Medical XIX-24

  9. Medical management • 11:45: Technician arrived at hospital of Sarov Occupational Medical Service within one hour of accident • experiencing nausea and began to vomit • Vomiting more frequent over two hours. Given antiemetic drugs, and vomiting stopped around 14:00 Module Medical XIX-24

  10. Rapid development of early symptoms • In 3-4 hrs patient’s general condition poor - fatigue, dizziness, headache, pallor, shivering, confusion, excessive perspiration • Rapidly invasive erythema appeared on hands with invasive oedema • Known hypotony progressed very quickly. In 3-4 hrs decreased to 70/50 and did not respond to treatment • No diarrhoea Module Medical XIX-24

  11. Typical early haematological parameters of very severe exposure Module Medical XIX-24

  12. Transfer to specialized clinic at Biophysics Institute, Moscow • On admission to this hospital, 10 hours post-exposure, patient still active, could walk and was stable in vertical position. Fully conscious but persistent fatigue and headache • First night (17–18 June), swelling of hands worsened, pain intolerable • Swelling extended to forearms Module Medical XIX-24

  13. Monitoring victim’s radioactivity in Moscow • 10 hrs post-exposure, dose rates from induced activity in victim’s body: • 30 µGy/h at head, 45 µGy/h over chest • 35–40 µGy/h over abdomen • 17–19 µGy/h in left leg • At this stage dose to whole body estimated 8-11 Gy, to hands 200-300 Gy • The 24Na activity concentration in blood was 290 Bq/mL, corresponding to mean whole body neutron dose of 14 Gy Module Medical XIX-24

  14. Biological dose assessmenta) haematology • In local Sarov Hospital, detected severe lymphopenia increased quickly: • 0.9 x 109 L-1 at 1 hour, 0.6 x 109 L-1 at 3 hours, and 0.18 x 109 L-1 at 5 hrs (Normal range: 1.5-4.3 x 109 L-1) • data indicate a dose at least 12 Gy. Suggest an extremely poor prognosis with fatal outcome Module Medical XIX-24

  15. Biological dose assessmentb) cytogenetics fromblood lymphocytes • Chromosome aberration analysis could not be performedon circulating blood lymphocytes because of deep lymphopenia at time of sampling • Also, surviving lymphocytes damaged, making culturing of cells impossible • Therefore, bone marrow cells used for assessing chromosome aberrations by direct method not requiring cell culturing Module Medical XIX-24

  16. Biological dose assessmentc) sampling BM for cytogenetics • Samples of bone marrow were taken from: • sternum • left anterior iliac crest • right posterior iliac crest • fourth thoracic vertebra • to characterize spatial dose distribution, important for treatment decisions Module Medical XIX-24

  17. Biological dose assessmentd) doses estimated for BM sites • at least 15 Gy to sternum (no metaphases seen, damaged, fully fragmented chromosomes) • 10–15 Gy to left anterior iliac crest (analysis of 12 metaphases: half had aberrations and rest fragmented chromosomes) • 6–7 Gy right posterior iliac crest (50 metaphases: 48 had multiple aberrations, two fragmented chromosomes) • about 6 Gy to fourth thoracic vertebra (three metaphases: two had fragmented chromosomes) Module Medical XIX-24

  18. Treatment in specialized hospital linics of Institute of Biophysics, Moscow • Because of drop in pressure in femoral vein, steroids administered and volume of infused fluids increased to 200 mL/h • Oligouria persisted and worsened, fluid infusion reduced to 100 mL/h • Total volume of fluid infused on second day 2800 mL, compared with urinary output 1200 mL Module Medical XIX-24

  19. Drugs and dosages for preventive treatment in specialized hospital • To prevent infection: irrigation of both hands with Lioxazol, special drug developed by pharmaceutical laboratory of Biophysics Institute (administered 1x 1-2 hrs), Acyclovir (6 mg per kg of body weight over 8 hrs), Ketoconazole (200 mg 2x day); and Ciprofloxacin (250 mg 2x day) • To prevent thrombosis: continuous perfusion of sodium heparin (20 000 IU per day) with plasma infusion • To prevent necrosis: Aprotinin (1 million IU per day) Module Medical XIX-24

  20. Oedema !!! Module Medical XIX-24

  21. Module Medical XIX-24

  22. 3rd day: terminal stage • Vascular damage --> hypoalbuminaemia, hypocalcaemia, progressive acidosis, lung oedema, hypoxaemia • 03:20, 20 June 97 (66.5 hrs after exposure) dramatic drop in blood pressure, bradycardia and death due to heart failure Module Medical XIX-24

  23. Summary of dose assessments by measurement and calculation Module Medical XIX-24

  24. Dose calculation by Monte Carlo method • Technician estimated distance of his hands from surface of critical assembly as about 5 cm and calculations were made accounting for known neutron and photon fluxes and their spatial distribution around assembly • Total dose to hands could lie between 800 and 2000 Gy. Final estimates were 1700 kerma (Gy) for neutron and about 120 Gy for gamma components Module Medical XIX-24

  25. Lessons • High n-doses may result in moderate early clinical signs, but do not necessarily indicate good prognosis • Patient died before clinical symptoms of gastrointestinal or bone marrow syndrome could develop • Death occurred within three days of exposure, not due to effects on central nervous system but on vascular system • Observe radiation safety rules! Module Medical XIX-24

More Related