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

WIPP RH PSAR DOE/WIPP-03-3174 CHAPTER 5
handling. The probability ranges from 1.0E-02 to 2.0E-03, with one outlier probability reported as 0.25.
The use of a conditional probability of waste drum failure due to being stuck by the PAR manipulator
arm would be highly conservative. It is unlikely that the PAR manipulator is strong enough to actually
puncture a waste drum and most events in which the arm did strike a drum would involve glancing
blows. In addition, slip clutches have been provided at each joint (shoulder, elbow, and wrist) to prevent
a drum from being punctured. As the robotic arm is manipulated, rotated, or extended from any
orientation and contacts the drum lid, the manipulator stops the motion that the operator is directing from
the control console. The operator may still have the controls engaged but the arm will not continue in the
path of travel. One additional event to be considered is a strike while lowering the manipulator arm with
the telescoping tube hoist. The telescoping tube hoist is lowered by cable and has a cable slack limit
switch. The switch is provided to detect cable slack that may occur during full extension or when an
obstruction is encountered. This precludes the hook from being forced into the drum. The smaller
estimate of the probability of 2.00E-03 is divided by 2 because of the slip clutches being used. The
frequency of hazardous event 10A-1 is: 2080 operations/yr * 1.0E-03 * 1.0E-03 = 2.1E-03/yr. The
frequency of NC3-E is in the "unlikely" range (10 -2 /yr $frequency >10 -4 /yr) and its consequences of NC3-
E are compared against the Evaluation Guidelines for the "unlikely" frequency range.
Since this event involves puncturing a single waste drum, the CD equals 1.
Since it is assumed that all of the radiological material from an entire 10-160B cask is located in a single
waste drum, the MAR is 20 PE-Ci (CD x CI). As with the radiological MAR, in determining the
non-radiological MAR it is assumed that one waste drum in the Hot Cell is punctured. Therefore, it is
assumed that the non-radiological MAR is the content of 1 waste drum (CD = 1). Therefore, the
non-radiological MAR is limited to the hazardous material content of 1 waste drum or 243 pounds.
The waste drums are DOT Type A containers. From section 5.2.1.1, the DR for DOT Type A waste
drums that are breached by impact with waste handling equipment is 0.05. The DR for this event is 0.05.
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-38 and E-39) of NC3-E 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-40 and
E-41).
Assessment of Immediate Worker Consequences - No immediate worker consequences are calculated for
NC3-E because no workers are in the Hot Cell where the event occurs.
NC3-F Puncture of Drum or Canister Outside Hot Cell Accident Scenario:
NC3-F is composed of hazardous events 12E-2, 12E-3, 12E-4, and 14B-1.
Hazardous event 12E-2 postulates the Hot Cell shield valve inadvertently closing on a facility canister
and shearing the canister. The causes of this event are mechanical-electrical failure or control system
failure. The frequency of event 12E-2 is a function of the number of facility canisters processed through
the Hot Cell in a year and the probability of spurious closure of the Hot Cell shield valve during
movement of the canister. 693 facility canisters will be processed through the Hot Cell and Transfer Cell
in a year. The PLG1317 38 evaluation of the probability of the shield valve closing on a waste canister is
2.00E-13 per transfer. The frequency of event 12E-2 is: 693 transfers/yr * 2.00E-13 = 1.4E-10/yr or
"beyond extremely unlikely" (10 -6 /yr $frequency).
5.2-61 January 22, 2003