E.15.0 VITRIFY WITH TANK WASTE ALTERNATIVE
The Vitrify With Tank Waste alternative for Cs and Sr capsules would involve the continued operation of WESF until a HLW vitrification facility was completed. The capsules would then be removed from the basin, placed in overpacks, and transferred by truck to the HLW vitrification facility where they would be cut up and blended with the HLW from the tank farms. This section analyzes potential construction, operation, and transportation risks resulting from accidents associated with this alternative.
E.15.1 CONSTRUCTION ACCIDENTS
The construction activities associated with the Vitrify with Tank Waste alternative are discussed in Appendix B of the EIS. It should be noted there are no radiological or chemical consequences associated with construction accidents. Occupational injuries, illnesses, and fatalities resulting from potential construction accidents are calculated in the following text.
The number of construction personnel was estimated at 1.00E+02 person-years (Jacobs 1996). The number of total recordable injuries and illnesses, lost workday cases, and fatalities for the 8 years of construction are calculated using the incidence rates from Table E.1.2.1 of this Appendix as follows:
Total Recordable Cases = (1.00E+02 person-years) · (9.75E+00 incidences/100 person-years) = 9.75E+00
Lost Workday Cases = (1.00E+02 person-years) · (2.45E+00 incidences/100 person-years) = 2.45E+00
Fatalities = (1.00E+02 person-years) · (3.2E-03 fatalities/100 person-years) = 3.20E-03
E.15.2 TRANSPORTATION ACCIDENTS
Transportation activities associated with this alternative are:
- Transporting construction material from offsite to modify WESF;
- Transporting the overpacked capsules from WESF to the HLW vitrification facility;
- Transporting vitrified HLW to a national HLW repository; and
- Employees commuting to work each day.
E.15.2.1 Radiological Cancer Risk
Radiological exposures resulting from accidents during transport of the capsules to the HLW vitrification facility were analyzed (Green 1995), the methodology of the analysis is discussed in Section E.6.2.1. The results of the analysis are summarized in Tables E.15.2.1 and E.15.2.2.
It is most likely there would be no fatal cancers attributable to this exposure.
The receptor dose and LCF risk resulting from the accident analysis for transporting vitrified HLW to an offsite geologic repository is presented tn Table E.15.2.3 for the integrated population and urban population. Since the capsules could be mixed and vitrified with any of the ex situ tank remediation alternatives, Table E.15.2.3 presents the LCF Risk for each of the alternatives.
E.15.2.2 Chemical Exposure
Chemicals would be transported to the Hanford Site in support of vitrifying the Cs and Sr capsules with the tank waste. An analysis was performed to identify the hazardous chemicals that could result in the largest toxicological impacts and evaluate the toxicological impacts of the bounding scenario accidents involving the highest hazard chemicals (Green 1995). A preliminary screening analysis was performed to identify the chemicals representing the highest potential toxicological hazard. The highest hazard chemicals in terms of toxicity were determined to be nitric acid and sulfuric acid. The chemical concentrations resulting from the bounding case scenario accident at 100 m (330 ft) (3.28E+02 ft) and the frequency of the accidents as postulated (Green 1995) are summarized in Table E.15.2.4.
Table E.15.2.5 compares the respirable concentration of the postulated chemical releases to acute exposure criteria (ERPGs) discussed in Section E.1.1.7. For the MEI general public, no ERPGs would be exceeded.
E.15.2.3 Occupational Fatalities and Injuries
Table E.15.2.6 provides a summary of the expected distance to be traveled by truck to support the construction and capsule transport activities.
Table E.15.2.6 Summary of Transportation Activities for the Vitrify with Tank Waste Alternative
Construction Material Transport
There would be modifications to WESF to support overpacking operations. Construction materials would be transported by truck from the Tri Cities 70 km (43 mi) and would require an estimated 200 trips.
Capsule Transport
The 1,929 capsules would be transported by truck to the HLW vitrification facility. Capsule transport would require 184 trips. The number of injuries and fatalities are calculated by multiplying the total distance traveled in each zone, shown in Table E.15.2.7 , by the appropriate unit risk factors shown in Table E.1.3.1.
Table E.15.2.7 Distance Traveled in Population Zones for the Vitrify with Tank Waste Alternative
The expected injuries and fatalities resulting from transportation accidents associated with the Vitrify With Tank Waste alternative are summarized in Table E.15.2.8.
In addition to transporting materials and supplies to and from the Hanford Site by truck, site workers and other personnel required to support the various activities will be driving to the site in their vehicles. The total person-years to support the alternative was calculated to be 241 (Jacobs 1996). Each person is assumed to work 260 days of the year. The round-trip distance traveled to work from the Tri-Cities area is estimated at 140 km (87 mi) with an estimated 1.35 passengers per vehicle (DOE 1994a).
The total personnel vehicle distance was therefore calculated as follows:
(241 person-years) · (260 days/year) · (140 km/day) · (1/1.35 person) = 6.50E+06 km (4.0E+06 mi)
The expected number of injuries and fatalities resulting from employee vehicle accidents was calculated as follows:
Injuries = (6.50E+06 km) · (7.14E-07 injuries/km) = 4.66E+00
Fatalities = (6.50E+06 km) · (8.98E-09 fatalities/km) = 5.97E-02
The cumulative noncancer injuries and fatalities incurred as a direct result of traffic accident impacts are summarized in Table E.15.2.9. It is most likely there would be four injuries and no fatalities resulting from traffic accidents.
E.15.3 OPERATION ACCIDENTS
The potential exists for accidents resulting from operation activities. These operations are discussed in Appendix B. The operations are separated and analyzed according to the following modes of operation:
- Pool cell storage at WESF - Cs and Sr capsules would remain stored in water-filled basins until they are transported to HLW vitrification facility.
- Capsule overpacking at WESF - Cs and Sr capsules would be removed from the basin and placed in overpacks.
- Vitrification preparation - Cs and Sr capsules would be cut up and blended into the HLW from tank farms.
E.15.3.1 Pool Cell Storage Accident at the Waste Encapsulation and Storage Facility
The dominant pool cell storage accident at WESF is the earthquake previously discussed in the No Action alternative in Section E.12.2.1 and is summarized as follows:
Source-Term - The source-term presented in Section E.12.2.1.1 resulting from the breached canisters for the non-involved worker receptor was 1.2E-01 Ci based on 8 hours exposure. The general public was calculated to be 3.5E-01 Ci based on 24 hours exposure. In addition to the source-term the loss of the water shielding the capsules would result in high direct radiation doses to the receptors. It was assumed that all the workers would die in the building from the collapsed roof.
Probability - The annual exceedance frequency of the earthquake in Section E.12.2.1.2 was 2.5E-04 per year. The Vitrify with Tank Waste alternative was based on 19 years of operations; therefore, the probability was calculated to be 4.8E-03.
Radiological Consequences - The radiological consequences presented in Table E.2.2.2 are reproduced in Table E.15.3.1.
TableE.15.3.1 Dose Consequence for Pool Cell Storage Accident
Radiological Cancer Risk - The LCFs calculated in Section E.12.2.1.4 are the same for the Vitrify with Tank Waste alternative; however, the LCF point estimate risk is not the same due to the difference in probabilities. The LCFs and the LCF risk are calculated in Table E.15.3.2. Aside from the 10 workers dying from the collapsed roof, the calculations show there would be no fatal cancers.
Table E.15.3.2 Latent Cancer Fatality Risk from Pool Cell Accident
Chemical Consequences - Chemical consequences presented in Section E.12.2.1.5 concluded there would be no exposure that would exceed the cumulative ratio of 1.0 to ERPG-1 values for toxic or corrosive/irritant chemicals.
The dominant overpacking accident at WESF is the crushed Sr capsule previously discussed in the Onsite Disposal alternative in Section E.13.3.2 and is summarized as follows:
Source-Term - The source-term presented in Section E.13.3.2.1 resulting from the breached canisters was 38.5 Ci.
Probability - The frequency of the accident in Section E.13.3.2.2 was 1.0E-02 per year. The Vitrify with Tank Waste alternative was based on 19 years of operations; therefore, the probability was calculated to be 1.9E-01.
Radiological Consequences - The radiological consequences presented in Section E.13.3.2.3 are reproduced in Table E.15.3.3.
TableE.15.3.3 Dose Consequence from Crushed Strontium Capsule
Radiological Cancer Risk - The LCFs calculated in Section E.13.3.2.4 are the same for the Vitrify with Tank Waste alternative and are reproduced in Table E.15.3.4.
Table E.15.3.4 Latent Cancer Fatality Risk from Crushed Strontium Capsule
Chemical Consequences - Chemical consequences presented in Section E.13.3.2.5 concluded there would be no exposure that would exceed the cumulative ratio of 1.0 to ERPG-1 values for toxic or corrosive/irritant chemicals.
E.15.3.3 Vitrification Preparation Accident
Types of potential accidents associated with vitrification preparation include sprays, spills, leaks, and explosions. The DBA accident identified in Table E.15.3.5 as having the highest risk is Accident 3.3.3.1 "Cs ion exchange column explosion". It was postulated that a fully loaded ion exchange column over pressurizes and explodes.
Table E.15.3.5 Accident Screening Table for the Vitrify with Tank Waste Alternative
E.15.3.3.1 Scenario and Source-Term Development for Cesium Ion Exchange Column Explosion
It was postulated that after the column was loaded with Cs, undiluted nitric acid was inadvertently used to dilute the Cs from the column instead of diluted nitric acid. The nitric acid reacts with the resin giving off gas and heat. The gas over pressurizes the column and explodes. A 10 percent airborne release fraction was assumed. It is also assumed that the facility in which the ion exchange would be performed would be equipped with two stages of high-efficiency particulate filters with a LPF of 2.0E-06. The source-term was calculated to be 1.27E+06 Ci.
E.15.3.3.2 Probability of Cesium Ion Exchange Column Explosion
This was considered to be an unlikely event with a frequency range of 1.0E-02 per year to 1.0E-04 per year. For conservatism the frequency of 1.0E-02 was assumed for calculating risk. Based on 19 years of operation the probability was calculated to be 1.9E-01.
E.15.3.3.3 Radiological Consequence from Cesium Ion Exchange Column Explosion
The radiological dose to the receptors from the previous source-term was calculated by the GENII computer program using the methodology previously discussed in Section E.1.1.6. The results are summarized in Table E.15.3.6 (WHC 1995k).
Table E.15.3.6 Dose Consequence from Cesium Ion Exchange Column Explosion
E.15.3.3.4 Radiological Cancer Risk from Cesium Ion Exchange Column Explosion
Based on a dose-to-risk conversion factor of 4.0E-04 LCF per person-rem for the worker and noninvolved worker and 5.0E-04 LCF per person-rem for the general public, the LCF risk is calculated for the receptors in Table E.15.3.7.
TableE.15.3.7 Latent Cancer Fatality Risk from Cesium Ion Exchange Column Explosion
The calculations show there would be no fatal cancers attributable to this exposure. Because the accident would occur in a canyon and the release would be from the stack, the workers would not receive a dose.
E.15.3.3.5 Chemical Consequences from Cesium Ion Exchange Column Explosion
Chemical exposures resulting from accidents at the vitrification facility are addressed in the Ex Situ Intermediate Separations alternative in Section E.6.
E.15.3.4 Occupational Fatalities and Injuries
The number of operation personnel was estimated at approximately 1.41E+02 person-years (Jacobs 1996). The number of total recordable injuries and illnesses, lost workday cases, and fatalities are calculated as follows:
Total Recordable Cases = (1.41E+02 person-years) · (2.2E+00 incidences/100 person-years) = 3.10E+00
Lost Workday Cases = (1.41E+02 person-years) · (1.1E+00 incidences/per 100 person-years) = 1.55E+00
Fatalities = (1.41E+02 person-years) · (3.2E-03 fatalities/100 person-years) = 4.51E-03
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