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

WIPP RH PSAR DOE/WIPP-03-3174 CHAPTER 5
5.2.3.5 RH4-B Loss of Confinement in the Underground (Waste Movement)
Scenario Description - The HAZOP 28 postulated a LOC of the waste material in the Underground. The
HAZOP 28 postulated four hazardous waste movement events (9-5, 10-1, 10-5, and 10-6) that could result
in a LOC of the waste material in the Underground. The LOC event could cause a significant release of
radioactivity.
Hazardous event 9-5 postulates a drop of the facility cask by a forklift during transfer of facility cask in
the Underground. The cause of this event is human error, forklift collision, equipment failure forklift
hydraulic system, or structural failure of fork tines. The potential consequences of this event are: breach
of a waste canister, significant radiological exposure to personnel, major release of radioactive materials,
considerable impact offsite, and worker fatality. The potential breach of a waste canister could cause a
significant release of radioactivity to the environment.
Hazardous event 10-1 postulates a loss of control where the forklift drops the facility cask onto the
HERE. The cause of this event is human error, or equipment failure. The potential consequences of this
event are: breach of a waste canister, major damage to the HERE, significant radiological exposure to
personnel, major release of radioactive materials, and considerable impact offsite. The potential breach
of a waste canister could cause a significant release of radioactivity to the environment.
Hazardous event 10-5 postulates a closure of a facility cask shield valve on a waste canister
(mispositioned shield valve or movement sooner than desired) while it is being emplaced. The causes of
this event are control loop failure and mechanical failure on the emplacement equipment. The potential
consequences of this event are: damage or breach of a waste canister, release of radioactive material,
direct radiological exposure, and adverse impact offsite. The potential breach of a waste canister could
cause a significant release of radioactivity to the environment.
Hazardous event 10-6 postulates misalignment of waste canister as it is moved into the borehole. The
causes of this event are: human error and equipment failure - HERE settles and results in misalignment or
level indicator malfunctions. The potential consequences of this event are: damage or breach of a waste
canister, damage to HERE, release of radioactive material, direct radiological exposure, and adverse
impact offsite. The potential breach of a waste canister could cause a significant release of radioactivity
to the environment.
Preventive and Mitigative Features - General preventive and mitigative measures identified in the
HAZOP for this specific scenario are listed in Table 5.1-10. For the no mitigation case, automatic or
manual shift of the underground ventilation system to HEPA filteration is assumed to not respond to
mitigate a release for this scenario.
Estimated Frequency - The HAZOP Team qualitatively estimated the frequency of LOC in the
Underground to be in the anticipated range (10 -1 $frequency >10 -2 ) for all the hazardous events.
The hazardous event 10-5, closure of shield valve on waste canister, is prevented by the following
passive design feature:
C
Design of the shield valve motor (torque limiter) is such that an inadvertent closure of shield
valve will not affect the containment integrity of the waste canister during its emplacement in
the borehole
Hazardous event 10-6, misalignment of waste canister as it is moved into the borehole, is prevented by
the following passive design feature:
5.2-35 January 22, 2003