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

WIPP RH PSAR DOE/WIPP-03-3174 CHAPTER 5
Specific mitigative features are identified in Appendix C for each postulated deviation as identified in the
HAZOPs, 4,5 and in Table 5.1-10 for each deviation considered for quantitative accident analysis. In
general, the WHB and underground radiation and effluent monitoring systems and HEPA filtration
systems, and the WIPP Emergency Management Program 38 provide this layer of defense-in-depth. In
addition, the WIPP Human Factors Evaluation, 39 determined that well established policies and procedures
are in place ensuring normal and emergency procedures are implemented, adequate directions have been
provided to shift personnel concerning actions to be taken in a potential accident environment, and
adequate procedures are available for follow up response. TSR ACs are derived in Chapter 6 and
required in the WIPP TSR Document (Attachment 1 to the SAR) supporting the second level of
defense-in-depth. Programs supporting defense-in-depth as required by the TSRs, are discussed in
Chapters 7, 8, and 9.
The third layer of defense-in-depth supplements the first two layers by providing protection against
extremely unlikely operational, natural phenomenon, and external events. These events represent
extreme cases of failures and are analyzed in Section 5.2.3 using conservative assumptions and
calculations to assess the radiological and non-radiological effects of such accidents on the MEI,
non-involved worker, and immediate worker to verify that a conservative design bases has been
established. These accidents include fire, waste hoist failure, and breach of waste container.
5.1.7 Protection of Immediate Workers from Accidents
The RH HAZOPs 4,5 identified a number of waste handling process hazards that could potentially lead to
events resulting in immediate worker injury or fatality, or exposure to radiological and non-radiological
hazardous materials. The Total Rank (or risk) for each postulated deviation as identified in Appendix C,
is the qualitative product of the frequency of the event and the potential consequences. As shown in
Appendix C, the consequences of the postulated deviations were dominated by the assumption that a
worker fatality may result without safeguards in place, regardless of dose or dosage received.
Consistent with: (1) 10 CFR 830.205, Technical Safety Requirements; 40 (2) the defense-in-depth
philosophy discussed in Section 5.1.6; and (3) the philosophy of Process Safety Management (PSM), as
published in 29 CFR 1910.119, Process Safety Management of Highly Hazardous Chemicals, 41 reduction
of the risk to workers from accidents is accomplished at the WIPP primarily by identifying controls to
prevent the event from happening. (note: Compliance with 29 CFR 1910.119 is not required by
WIPP. However, the WIPP philosophy of reduction of accident risk is consistent with this standard.)
The TSRs are not based upon maintaining worker exposures below some acceptable level following an
uncontrolled release of hazardous material or inadvertent criticality; rather the risk to workers is reduced
through the reduction of the frequency and potential impact of such events.
Consistent with this statement, in conjunction with the defense-in-depth philosophy, total risk is
evaluated by: (1) performing engineering analyses in the form of event tree/fault tree analysis to identify
systems, structures, components, processes, or controls that contribute most to the accident phenomena
frequency for the purposes of verifying their adequacy or identifying improvements to reduce the
accident frequency and therefore risk, and (2) evaluating human error as an initiating event.
As discussed in Section 5.1.4.1, the HAZOP Teams identified a significant number of existing
preventative safeguards that lower the frequency of occurrence of each deviation, substantially reducing
the risk of injury or fatality to workers. The HAZOP Teams concluded, consistent with the first layer of
defense-in-depth, that safeguards currently exist at the WIPP to prevent or reduce the frequency of such
deviations from occurring. Identified preventative safeguards shown in Appendix C, and Table 5.1-10
include the following:
5.1-20 January 22, 2003