Appendix A: Guidelines for Acceptable Methods to Meet NPH Acceptance Criteria

DOE-STD-1023-95

APPENDIX A - Guidelines for Acceptable Methods to Meet NPH Acceptance Criteria

Appendix A provides additional guidance on acceptable methods, approaches, and references related to

NPH assessment criteria. The section numbers in Appendix A correspond to the exact section numbers in

the main section of the standard, when additional guidance is provided.

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As an example of the type of data available for other hazards, there are studies commissioned

by the USNRC for nuclear power plant evaluation which may be applicable to DOE facilities.

See, for example, MacGorman, et al. (1984) and Changery (1981) for data applicable to

lightning hazard definition.

A3.1.1-d.

While not a formal part of the seismic hazard assessment, other earthquake-induced ground

failure modes should also be considered during site characterization and modeling, such as

potential for liquefaction, slope instability, lateral spreading, or subsidence. If such potential is

found, it should be noted in the assessment report.

A3.1.2.1-a. When the mean hazard curves from EPRI (1989a) and LLNL (Savy, et al., 1993 and Sobel,

1994) are directly averaged, the average should be based on averaging the mean annual

probabilities at a given peak acceleration or spectral acceleration, computing the average at

enough ground motion values to draw the entire hazard curve.

A3.1.2.2-c For sites with facilities in PC 3 or less, a simplified PSHA is acceptable. Simplifications are

not in the methodology itself, but rather in the extent to which the general principles of the

methodology are fulfilled. In practice, the simplification is obtained by reducing the effort of

new data collection, reducing the number of experts elicited or the level of peer review and by

reducing the sampling and testing in the geotechnical field for the site-specific characterization

(see SSHAC, 1997).

The following elements shall be included in the methodology to conduct a new PSHA: (1)

Basic Hazard Model; (2) Data Used in the Hazard Modeling; (3) Characterization of

Uncertainty in Parameters of the Hazard Model; and (4) Quantifying Uncertainty. Each of

these elements is discussed below.

Basic Hazard Model

At a given site, the hazard function SH(g) is defined by the probability P(G g) that the ground

motion parameter G, e.g., the PGA or the pseudo response spectral velocity (PSV), exceeds

some value g in t years for all earthquakes greater than a value Mo contributing to the hazard,

i.e.,

SH(g) = P (G g, for m Mo).

For well-engineered structures (built to modern seismic standards) such as commercial nuclear

power plants, a lower bound magnitude (Mo) of 5 shall be used (EPRI, 1989b). For those

DOE facilities which cannot be classified as built to modern seismic standards, such is not

necessarily the case and the analyst should provide estimates of the hazard for Mo = 5 and Mo

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