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

WIPP RH PSAR DOE/WIPP-03-3174 CHAPTER 5
The release from the waste drums in the loaded facility canister is bounded by the release from a dropped
waste drum carriage. 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 ten drums are impacted is equivalent to assuming that
the one drum containing all of the radiological material is damaged. Therefore, for the radiological
source term analysis, it will be assumed that only one waste drum is breached by a dropping the waste
drum carriage while lifting it from the 10-160B cask in the CUR, resulting in a release of the radiological
material (CD = 1). The MAR for this event is 20 PE-Ci (CD x CI).
In determining the non-radiological MAR it is assumed that ten waste drums in the CUR are subject to
the effects of dropping a waste drum carriage during lifting. Since this event postulates dropping a
loaded waste drum carriage (containing five drums) onto the second waste drum carriage (also containing
five drums), it is assumed that the non-radiological MAR is the content of ten waste drums (CD = 10).
The non-radiological MAR is limited to the hazardous material content of ten waste drums or 2430
pounds.
The DR in this case is based on the amount of damage the waste drums receive as a result of the impact
and how much of the contents are exposed as a result. The waste drums are DOT Type A containers. The
drop in this event is from the lifting fixture on the crane during unloading operations in the CUR. The
height of the drop is assumed to be greater than four feet. From section 5.2.1.1, the DR for drops greater
than five feet but less than or equal to ten feet is 0.025. The DR for this event is 0.025.
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-34 and E-35) of NC3-D 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-36 and
E-37).
Assessment of Immediate Worker Consequences - No immediate worker consequences are calculated for
NC3-D because no workers are in either the CUR, Hot Cell or Transfer Cell where the event occurs.
NC3-E Puncture of Drum in Hot Cell Accident Scenario:
NC3-E consists of hazardous event 10A-1 which postulates a puncture of a drum with the PAR
manipulator caused by human error and/or equipment failure. The potential consequences of this event
are: breach of drum, spread of contamination, offsite and onsite consequences, release of hazardous waste
and operational down time. Breach of a drum could cause a significant release of radioactivity to the
environment.
The frequency of event 10A-1 is a function of the number of waste drums handled using the PAR
manipulator per year, the probability of an error by the operator while using the PAR manipulator such
that the arm strikes a waste drum, and the probability that the drum is breached given that it is struck by
the arm. As discussed above, 2080 waste drums will be processed through the Hot Cell each year. It is
assumed in this analysis that the human error of striking a drum with the PAR manipulator arm is
equivalent to the failure to follow a clear, unambiguous procedure. From Table D-1 of the WIPP CH
SAR, 6 the probability of failing to correctly follow a clear, unambiguous procedure is 1E-03 per demand.
Note that it is also possible that an equipment failure could result in the PAR manipulator striking the
drum. However, given the extensive preventative maintenance program and requirement for preoperational
checks of the manipulator at the beginning of each shift, it is assumed that the failure is
dominated by human error and the equipment failure probability is not included. ANL/EAD/TM-29 63
provides the conditional probability of drum puncture given that it is struck by equipment during
5.2-60 January 22, 2003