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

WIPP RH PSAR DOE/WIPP-03-3174 CHAPTER 5
The next step was to define the deviations from the intended function that could occur at each study node
or process step. A combination of application of guide words and the knowledge based approach (see
Section 3.1 of DOE/WIPP-99-2303 4 and WSMS-WIPP-00-0006 5 ) was used to identify the deviations.
The HAZOP Teams agreed that with the exception of the natural phenomena and external events for
which specific frequencies had already been determined, event initiators would be considered to occur
with a frequency in the "anticipated" range (see Table 5.1-4). The frequencies for the natural phenomena
events and external events were listed as identified in DOE/WIPP-95-2065. 24 The deviations identified
for each study node are listed in Appendix C.
Following identification of the deviations, causes and unmitigated consequences of those deviations were
listed. As part of the qualitative determination of the consequences of each event, credit was taken
initially only for the confinement and/or shielding expected to be provided by the road casks, the
canisters, the drums, the facility cask, the Hot Cell and the WHB. No other preventive or mitigative
features were assumed to be in place for determination of consequences.
The consequences that were listed for each deviation identified in the HAZOPs were then "ranked"
qualitatively using two sets of criteria. The first ranking was a "total rank" which included both
radiological and non-radiological consequences. This ranking process used a two number system
consisting of a qualitative unmitigated consequence based on the criteria given in Table 5.1-5, and a
frequency ranking based on the levels given in Table 5.1-4. As stated previously, the frequency for all
event initiators, with the exception of natural phenomena and external events, was considered to be in the
"anticipated" range. This resulted in the "total rank" which is recorded in Appendix C.
The "total" ranking for each deviation included both the resultant non-radiological and radiological
consequences to the workers, the facility, and the offsite public. The possibility of worker fatality from a
non-radiological accident resulted in the assignment of the highest possible consequence ranking of four.
The purpose of this initial ranking was to provide an indication of those areas where there was a potential
to improve the level of general industrial safety for facility workers.
The purpose of the second ranking was to identify those accidents that would pose the greatest
radiological risk to the public, onsite workers, and the environment. This second ranking was based on
the "radiological rank" consequence criteria given in Table 5.1-6. The radiological ranking was
qualitatively estimated for each of three receptors: 1) the immediate worker, 2) the non-involved worker,
and 3) the offsite maximally exposed individual (MEI).
The ultimate intent of the radiological ranking was to provide a means to select those potential accidents
that would be of sufficient concern to be carried forward for quantitative accident analysis. For selection
of candidate events for quantitative analysis, the consequences of each deviation were examined to focus
only on risk posed by the accidental release of radiological material to the offsite individual. The results
of this ranking are listed in Appendix C using the same two number system and format as that used for
the total rank: consequence first, frequency second.
5.1-12 January 22, 2003