Radionuclide and colloid transport in the Culebra Dolomite and associated complementary cumulative distribution functions in the 1996 performance assessment for the Waste Isolation Pilot Plant

Abstract

The following topics related to radionuclide and colloid transport in the Culebra Dolomite in the 1996 performance assessment for the Waste Isolation Pilot Plant (WIPP) are presented:(i) mathematical description of models, (ii) uncertainty and sensitivity analysis results arising from subjective (i.e., epistemic) uncertainty for individual releases, and (iii) construction of complementary cumulative distribution fimctions (CCDFS) arising from stochastic (i.e., aleatory) uncertainty. The presented results indicate that radionuclide and colloid transport in the Culebra Dolomite does not constitute a serious threat to the effectiveness of the WIPP as a disposal facility for transuranic waste. Even when the effects of uncertain analysis inputs are taken into account, no radionuclide transport to the boundary with the accessible environment was observed; thus the associated CCDFS for comparison with the boundary line specified in the U.S. Environmental Protection Agency's standard for the geologic disposal of radioactive waste (40 CFR 191, 40 CFR 194) are degenerate in the sense of having a probability of zero of exceeding a release of zero.

Latin hypercube sampling and the propagation of uncertainty in analyses of complex systems

“…This approximation procedure re-quired evaluating the models in Table 7.1 for a relatively small number of elements of S,, and then using these evaluations to the construct AX,,,+ Xsu) for the large number of sample elements (i.e.. nS = l0,OOO) used in the summation in Eq. (7.5) (see 319,322,323 for numerical details).…”

Radionuclide transport in the vicinity of the repository and associated complementary cumulative distribution functions in the 1996 performance assessment for the Waste Isolation Pilot Plant

“…In the computational implementation of the analysis for transport in the Culebra described in Ref. 9, this results in the same SECOTP2D results being used for both dissolved radionuclides and humic colloids. Values for fCEl and fCE2 are obtained by forming the ratio of corresponding colloidal and total concentrations in Fig.…”

Direct releases to the surface and associated complementary cumulative distribution functions in the 1996 performance assessment for the Waste Isolation Pilot Plant: cuttings, cavings and spallings

“…The construction of CCDFS for the other release modes is discussed in other articles. [10][11][12][13] When the effects of irnprecise~y known analysis inputs are included, the representations for the cuttings, cavings and spallings releases become f~x~~, XJ and~sp [xst, Xsu,fB(xst, xJ], where Xsu is an element of the sample space S.Uassociated with the probability space (S~U, SU, pJ for subjective uncertainty (Sect. 5,Ref.…”

“…30, the shear stresses associated with the laminar helical flow of a non-Newtonian fluid can be expressed as (12) for R~R < p <1, where Ri and R are the inner and outer radii within which the flow occurs as indicated in Fig. 1; T(R, p) is the shear stress (kg m-l S-2) at a radial distance AR beyond the inner boundary (i.e., at p = (Ri + AR)/R); and the quantities C, J and k are fimctions of R that satisfy conditions indicated below.…”