DOE 2000. - Waste Isolation Pilot Plant - U.S. Department of Energy

WIPP RH PSAR DOE/WIPP-03-3174 CHAPTER 5
For this accident scenario it is assumed that the entire 20 PE-Ci inventory is located in a single waste
drum (CI = 20 PE-Ci). This event involves dropping an object on the waste drums in the 10-160B cask
while it is in the CUR. Only one 10-160B cask can be processed through the CUR at one time, therefore
only the ten waste drums contained in the 10-160B cask being processed are subject to the direct effects
of a dropped object. Since it is assumed that all of the radiological material from an entire 10-160B cask
is located in a single waste drum, assuming that all ten drums are impacted is equivalent to one drum
containing all of the radiological material is damaged. For the radiological source term analysis, it is
assumed that only one waste drum is breached by a dropped object, resulting in a release of the
radiological material (CD = 1). The MAR for this event is 20 PE-Ci (CD x CI).
For the non-radiological MAR it is assumed that only the ten waste drums contained in the 10-160B cask
being processed in the CUR are subject to the effects of a dropped object. However, the waste drums in
the 10-160B cask are in two drum carriages, each containing 5 waste drums. Only the waste drum
carriage on the top would be directly impacted by the dropped object. Therefore, it is assumed that the
non-radiological MAR is the content of 5 waste drums (CD = 5). The non-radiological MAR is limited
to the hazardous material content of 5 waste drums or 1215 pounds.
The DR in this case is determined based on the amount of damage the waste drum receives as
a result of the impact and how much of the contents are exposed as a result. As discussed above it is
conservatively assumed that the DR is (4 x 0.025 = ) 0.1 for this event.
Estimated Noninvolved Worker and MEI Consequences and Comparison to Risk Evaluation Guidelines -
Based on the values for the source term variables as presented above, the worst-case, no-mitigation MEI
and noninvolved worker consequences (Appendix E Tables E-26 and E-27) of NC3-B are well within the
radiological and non-radiological risk evaluation guidelines for the unlikely range. The non-radiological
results meet the guidelines (i.e., the sum of ratios < 1) when all the chemicals are added (Tables E-28 and
E-29).
Assessment of Immediate Worker Consequences - No immediate worker consequences are calculated for
NC3-B because no workers are in the CUR where the event occurs.
NC3-C Dropped Drum or Canister in Hot Cell Accident Scenario:
NC3-C is composed of hazardous events 10B-1, 10BF-1, and 11F-1. All of which involve dropping a
waste drum or loaded facility canister inside the Hot Cell.
Hazardous event 10B-1 postulates that while lifting a drum, the drum lid comes off. The causes of this
event are human error, equipment failure and drum lid failure. The frequency of event 10B-1 is a
function of the number of drums lifted for placement in a facility canister each year and the probability of
the drum lid failing during the lift. From examination of the drum and lifting process, it is concluded
that the lid falling off during a lift is not a credible event. The ICC-17C 55 gallon drum has a cable lift
fixture attached below the first rolling hoop prior to initial drum loading as shown in Figure 4.2-11. The
loaded drums were placed in the drum carriage for shipment using the cable lift fixture at the shipping
site. The lift cables are placed over the crane hook and the lift executed. This exerts a force on the drum
lid ring tending to hold the lid in place. The lift cables are symmetric around the drum to ensure there is
no load shift. During the lift, the lift cable forces hold the lid in place.
5.2-57 January 22, 2003