Nuclear accidents on military vessels in canadian ports
This paper reports a quantitative, site-specific analysis of two nuclear accident scenarios aboard military vessels in a Canadian port. Conventional methodology used by the U.S. Nuclear Regulatory Commission (NRC) to regulate the U.S. civilian nuclear industry is combined with generally conservative assumptions (that is, assumptions that tend to understate the likely impact of an accident) to evaluate the consequences of hypothetical nuclear accidents aboard military ships in the port of Esquimalt and the adjacent city of Victoria, British Columbia, Canada. The results are used as a basis for policy evaluations on the issue of port visits. The results also bear upon the proposed acquisition by the Canadian Armed Forces of 10 to 12 nuclear-powered submarines. Although this analysis has been undertaken for a U.S. military propulsion reactor, comparable effects would be anticipated from a similar accident entailing a British Trafalgar class or a French Rubis class submarine.
The first accident scenario analyzed is incineration of a single nuclear warhead in a ship-board fire. Such an accident would produce a radioactive cloud containing plutonium-239 , which would be carried toward the northeast, directly over Esquimalt/Victoria, by the most probable prevailing winds.
- The plutonium concentration in the cloud would exceed U.S. federal (NRC) limits for air contamination (10 CFR 20) by up to ten thousand times.
- Ground contamination from fallout would exceed U.S. federal (NRC) limits for unrestricted public use by up to one million times.
- Radiation exposure from inhalation of the plutonium would exceed U.S. federal limits for "routine" releases by up to one hundred thousand times.
- Latent cancer fatalities incurred during the accident would range from 15 to 3,413 depending on thermal lofting, atmospheric stability and the radiation risk factor used, with
- an equal number of additional fatalities from severe genetic defects.
The second accident scenario analyzed is a hypothetical nuclear-reactor accident aboard a ship berthed at Esquimalt. The core inventory of a 100 megawatt (thermal) naval propulsion reactor fueled by highly enriched uranium metal is derived from calculations on research reactor fuel performed with the ORIGEN computer code. Release fractions consistent with existing accident histories and radionuclide properties are assumed, and consequent releases to the atmosphere are calculated for 15 radionuclides comprising an estimated 94.8 to 98.1 percent of the projected health detriment for three exposure pathways (cloudshine, inhalation exposure and groundshine). Ingestion and resuspension pathways are ignored under the assumption of early evacuation and decontamination.
Calculated downwind air concentrations of the radionuclides following a four hour propulsion reactor accident, as well as ground deposition, exceed the aforementioned federal U.S. NRC limits by hundreds to thousands of times. Prompt casualties are possible close to the accident but have not been considered here.
- Total latent cancer fatalities incurred during the accident range from 2 to 422 , depending on assumptions, and are concentrated in the first 5 kilometers from the accident site.
- An equal number of additional fatalities from severe genetic defects would be anticipated.
- Additional casualties incurred from 1 week of habitation of contaminated urban regions would range from 69 to 636 latent cancer fatalities, with an equal number of casualties from severe genetic defects, highlighting the need for immediate evacuation.
- Additional casualties incurred from 1 year of further habitation range from 254 to 1,562 latent cancer fatalities and an equal number of casualties from severe genetic defects.
- Additional casualties in each subsequent year would approximate 250 to 1,500 latent cancer fatalities initially, declining to half within approximately 30 years.
Although SHORT-TERM casualties under the generally conservative assumptions of this analysis are relatively low, both accidents modeled would cause from hundreds to thousands of LONG-TERM casualties unless the contaminated urban areas were both evacuated and decontaminated. Rapid evacuation would appear impossible in the absence of effective emergency response plans (see below). The most significant impact, however, could be economic. U.S. Government studies indicate that decontamination could cost tens of billions of U.S. dollars and take months to complete, during which time the local economy would be largely terminated. These cost estimates omit the on-site costs of clean-up, and they omit "indirect" losses from the termination of local economies and ripple effects on provincial and national economies. The ecological and economic impacts of such an accident on surrounding salt water bodies have not been considered here but could also be significant.
The risk to the Canadian public from these accidents is the product of the CONSEQUENCES and PROBABILITY of the accident. Although the consequences can be estimated under idealized accident conditions as assumed above, the probability of each accident requires information that is not within the public domain. Such information includes the number of nuclear warheads aboard ships in port, the frequency and intensity of shipboard fires, the fire resistance of nuclear warheads, and the accident history and operating characteristics of naval propulsion reactors, In the absence of this is information, the probability of the accidents modeled cannot be calculated, and hence the risk associated with port visits or stationing of nuclear powered submarines cannot be assessed accurately.
Emergency preparedness for a nuclear accident in Canadian ports is inadequate to cope with the scale of possible accidents analyzed here. Civilian regulatory bodies exercise no licensing nor oversight authority over the technical aspects of U.S. military reactors and weapons. Port visits by U.S. nuclear-powered or nuclear-capable vessels are conducted under the U.S. General Statement of Assurances (Appendix I). This document does not mention emergency preparedness, is ambiguous on the issues of liability/compensation in the event of an accident, and omits any consideration of nuclear weapons accidents, even though such accidents have occurred and are featured in U.S. military emergency preparedness plans. Emergency preparedness for nuclear accidents is allocated to Canadian authorities, who have assigned such responsibility to the Department of National Defence (DND). DND emergency preparedness plans are not, however, in the public domain. Without public knowledge of emergency preparedness plans, it is therefore not clear how public participation in a time of actual emergency could be implemented. U.S. studies indicate that emergency preparedness is effective only when specific plans adequate to real emergencies are designed, publicized and exercised periodically.
Publicly-available information on DND emergency procedures suggest:
- evacuation zones extend only to 609 meters from the accident site;
- Nuclear Emergency Response Teams (NERTs) are responsible for seeking information about the type of hazard and containing any radioactive material released; and
- responding to nuclear weapons accidents is not a part of NERT planning.
- contamination and casualty zones could extend to several kilometers from the accident site, as demonstrated in the present analysis, rendering a 609 meter evacuation zone meaningless;
- the U.S. General Statement of Assurances explicitly prohibits the boarding of U.S. military vessels for the purpose of obtaining technical information, and
- U.S. Department of Defence directive 5230.16 permits concealing nuclear weapons accidents when they occur.
The findings of this report provide a technical basis for seven policy recommendations. The principle recommendation is:
- 1) Prospective costs and benefits of port visits by nuclear capable and nuclear propelled warships, as well as those associated with the acquisition of nuclear powered submarines, deserve careful weighing, incorporating quantitative assessments of possible costs of accident scenarios such as those reported here.
- 2) Emergency evacuation ought to be extended to at least 5 kilometers from the accident site for densely populated urban areas such as Esquimalt/Victoria;
3) Evacuation plans should be established, coordinated and rehearsed periodically;
4) Decontamination plans in the event of an accident should likewise be formulated;
5) The data needed to ascertain empirically the probability of nuclear accidents should be obtained from the U.S. military so that the risk to the Canadian public can be estimated as closely as possible;
6) Detailed liability and indemnity regimes in the event of an accident should be negotiated in advance;
7) Existing emergency response institutions, procedures and documents should be evaluated in light of accident analyses such as the present one.