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

WIPP RH PSAR DOE/WIPP-03-3174 CHAPTER 5
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During waste processing in the Hot Cell, any sparks generated from the waste handling equipment
and a drum (metal to metal contact) would occur external to the drum and would not have the
energy to penetrate the drum lid or vent filter to ignite the flammable gases in the drum headspace.
If the vent filter was not present, then flammable drum gases would not accumulate.
Source Term Development - Considering hazardous event 9-2 cannot occur there will be no release of
radioactivity.
5.2.3.15 NC6 Fire Followed by Explosion in the Underground
According to Section 5.2.3.6 (RH5), the fire followed by explosion in the underground that causes a
release of hazardous materials from the facility cask or from a 72B canister is not credible. Therefore, a
fire followed by explosion during processing of the waste from a 10-160B cask in the facility cask or
facility canister would not cause a release of hazardous materials. The design features and controls
credited in RH5 will be applicable to the processing of 10-160B cask waste.
5.2.3.16 NC7 Seismic Event
Scenario Description - The HAZOP 56 for the 10-160B RH operations postulated a LOC in the RH Bay
due to a seismic event (20-1) that could lead to a breach of a drum or multiple drums. Hazardous event
20-1 postulates a seismic event that occurs during the period of time that the 10-160B cask lid is loose
that causes a breach of one or more waste drums.
The HAZOP 56 for the 10-160B RH operations also postulated a full facility fire that involves the Hot Cell
or other RH facilities and which could cause a breach of one or more waste drums. Hazardous event 20-2
postulates a full facility fire that causes the breach of one or more waste drums. The possible cause of the
fire is an earthquake.
Preventative and Mitigative Features - General preventative and mitigative measures identified in the
HAZOP process for this specific scenario are listed in Table 5.1-10.
Estimated Frequency - The HAZOP 56 for 10-160B RH operations ranked the frequency of a DBE event
as "unlikely" (10 -2 /yr $ frequency > 10 -4 /yr). The DBE is based on a 1,000 year return interval. The
frequency of the DBE event is 1E-3 per year and the frequency bin is "unlikely".
The HAZOP 56 ranked the likelihood of the hazardous event Full Facility Fire as "unlikely"
(10 -2 /yr $ frequency > 10 -4 /yr). However, this event postulates a fire involving the entire RH facility
resulting from a DBE. The conditional probability of a fire resulting from the DBE ranges from about
3E-02 to 3E-03, depending on the specific structure design and the intensity of the seismic event 57 . The
frequency of a fire resulting from a DBE is in the range of 3E-05 to 3E-06 per year or the "extremely
unlikely" range (10 -4 /yr $frequency.> 10 -6 /yr).
Additionally, the waste may be in several areas of the RH facility at the time of the earthquake and fire.
The RH bay can contain up to two 10-160B casks. The WHB and the RH bay crane are seismically
qualified to survive a DBE. Therefore, the 10-160B casks in the RH bay would not be damaged by
falling structures. The 10-160B casks should remain intact during any realistic fire that resulted from the
DBE. The waste drums in the road casks would be protected from the effects of a fire that resulted from
the DBE as long as the cask was intact and sealed. The drums would only be at risk from the fire during
the period of time the cask is being transferred to the CUR by the RCTC with its lid un-bolted. The DBE
could dislodge the un-bolted lid and expose the drums to the effects of a seismically induced fire.
5.2-69 January 22, 2003