Licensing Code of Practice - Technical Objectives
4.2.2 Licensing Objectives ? Technical
4.2.2.1 Value of Measurement
4.2.2.2 Calculational Methods
4.2.2.3 Simplicity
4.2.2.4 Conservatism
4.2.2.5 Regulatory Precedence
4.2.2.6 Completeness and Rigor
4.2.2.7 Standardization and Uniformity
4.2.2.8 Use of Caveats
4.2.2 Licensing Objectives ? Technical
Technical licensing objectives are directed at structuring technical processes and approaches to licensing issue resolution. Their purpose in to minimize the time required for the regulator's review of the license application. Since receipt of a construction authorization is a critical path schedule item, significant cost penalties are involved. Although very important to schedule, failure to achieve these objectives would not necessarily result in program termination.
Of all the ongoing technical activity, among the more important to licensing is performance assessment. Performance assessment will produce the "quantitative proof" that the repository can be constructed, operated, and sealed in accordance with the regulator's performance objectives. The principles that follow, while having broader applicability, are primarily directed at performance assessment and pre?closure safety analysis.
4.2.2.1 Value of Measurement
o Principle 1
During the licensing process, test results provide a firmer basis for issue resolution than calculated numbers.
o Objective 1
Rely on measurement to the extent practical to reduce uncertainty.
o Objective 2
Rely on measurement to eliminate whole classes of accident scenarios that scientific theory would entertain. [For example, crash tests of fuel assemblies might show that cask drop accidents need not be considered since post?crash radionuclides would not exit in the respirable range. Such a finding would have the effect of essentially eliminating pre-closure safety considerations relative to all handling systems, i.e., no QA Level 1 items.]
4.2.2.2 Calculation Methods
o Principle 1
The method upon which the radiological safety evaluation of the facility will rest should be well understood by the applicant, the regulator, and be generally accepted in the scientific community. [Acceptable assessment methodologies are also powerful management tools to be used to justify activities, e.g., site characterization testing, and to optimize design choices.]
o Objective 1
Develop generally acceptable post-closure performance assessment and pre-closure safety assessment methodology, including all relevant assumptions.
o Objective 2
Validate performance assessment models.
o Objective 3
Demonstrate that long-term performance will be no worse than what has been measured during pre-closure performance monitoring.
4.2.2.3 Simplicity
o Principle 1
Simplicity of technique, when bounding, significantly restricts the opportunity of the regulator to engage in peripheral debates not central to licensing. [Development of performance assessment and other analytical models/techniques may be unnecessarily complicated when developed solely from a technical and scientific perspective. While most licensing solutions will be based on technical and scientific principles, rigorous and detailed science does not by itself assist the licensing process and will likely hinder it.]
o Principle 2
Simplicity leads to consensus building among experts. [Agreement that a parameter’s value is "certainly no more than 10" eliminates debates among experts as to whether the value is actually 6.125 vs. 6.126. This can have great utility for licensing.]
o Objective 1
Limit "secondary uncertainties" in the licensing process, i.e., those based on the uncertainties inherent in the complexity of the analytical tools to be used [i.e., the argument over whether a particular model accurately describes a physical phenomenon when most experts would agree that the phenomenon in bounded by another simpler (therefore less technically elegant) model. Models should be as simple as possible, but not simpler.]
o Objective 2
Continue to develop the more complex, more accurate models since they will be necessary to resolve questions that will arise concerning "margin", i.e., the safety factor that is the difference between the applicant's conservative position and what is thought to be the "real" value. [The cumulative magnitude of such margins contributes to "reasonable assurance" findings.]
4.2.2.4 Conservatism
o Principle 1
Sufficient "margin" exists in licensing when, under design basis conditions, the applicant can demonstrate that its facility design will limit radiological releases to a small fraction of regulatory limits. [Because there is no way to know for certain which site is actually better, a better site from a licensing perspective is one about which there is less uncertainty. It is at least feasible that uncertainty will increase as site characterization continues. It is not clear how this uncertainty will eventually be accounted for in design and performance assessment. While the performance allocation process provides a mechanism to account for uncertainties, which overall guidelines are being followed? How much conservative "margin" is being built into the program? What do "high, medium and low" uncertainties, as used in the Site Characterization Plan (SCP), mean? Too much conservatism can increase cost unjustifiably and make performance assessment results seem worse than they actually are. Too little could cause schedule delays, as re?design is necessary to compensate for "surprises".]
o Objective 1
Adopt conservative design goals that are consistent with regulatory precedent.
o Objective 2
Factor conservatism into all relevant activities related to waste isolation and pre?closure safety on a consistent basis, keeping track of the cumulative effect.
o Principle 2
Avoid over-conservatism. [Overly conservative technical models do not necessarily produce conservative results. Such models can actually obscure ongoing physical phenomena, produce non-conservative results and completely undermine the design and licensing efforts. On first read, this would appear counter-intuitive: “How is it possible to be overly conservative?†One example might be if the saturated zone modeler maximizes the amount of water predicted to flow through the repository. Such water flow would accelerate the deterioration of the drip shield, waste package and spent fuel, thus maximizing the predicted public dose. If that predicted dose is still below regulatory limits, the saturated zone modeler could conclude that the work is defensible. However, other modelers who take credit for that water being there, e.g., the igneous modeler crediting the water for absorbing reactive fluorine gas released by magma, can be misled because the best estimate case might be that no water is there. Another example might be how radionuclides leave the repository if the waste packages are breached. The process entails attaching radionuclides to dust particles creating colloids which, with the help of gravity, flow through cracks in the rocks to the saturated zone and then to public receptors. To maximize the predicted dose from this process, the modeler attaches many radionuclides to the dust particle, enlarging it. If that predicted dose is still below regulatory limits, the transport modeler could conclude that the work is defensible. However, when colloids get to be a certain size, they actually could be too large to flow through cracks in the rock, thus getting filtered out. Thus instead of maximizing predicted dose, the dose could actually be minimized.]
o Objective 1
To the extent technically feasible and where appropriate, develop best-estimate models or simple, bounding models. Avoid overly conservative models.
4.2.2.5 Regulatory Precedence
o Principle 1
Use of precedence provides regulators with "reasonable assurance" and helps speed the review process. [Because many scientists and engineers involved with this program may not have worked in a regulated industry before, there seems to be a tendency to believe that "new and innovative approaches" are desired. The tendency to view the program as purely an R&D exercise (i.e., nothing is more important than doing good science) misses the point and will likely be counter?productive for licensing. The regulator's job is made much easier when regulatory case law can be shown to support the applicant's approach. New and innovative approaches require more intense regulatory scrutiny, should be used where necessary, but should be controlled.]
o Objective 1
As a general rule, do not re?invent the wheel. Past regulatory precedence should be cited in all applicable areas.
4.2.2.6 Completeness and Rigor
o Principle 1
The licensing process, including judicial review, will demand the applicant to demonstrate "it has thought of everything." [The risk assessment program for a facility must be able to demonstrate that it has been systematic and thorough in evaluating facility radiological safety, including the search for "System Interactions", i.e., non?obvious physical, spatial, and temporal couplings detrimental to safety.)
o Objective 1
Develop a systematic analysis technique or framework that will be able to demonstrate that the applicant has been rigorous and not arbitrary and capricious in its performance assessment and pre?closure safety analyses.
4.2.2.7 Standardization and Uniformity[1]
o Principle 1
Decisions should be made on as common a basis as the diversity of the sites allows. [The regulations require that the applicant consider alternatives to its selected courses of action and clearly demonstrate the acceptability of its decisions. While appropriate for some applications, non?standardization in areas amenable to uniformity of approach will complicate the selection process. Major efforts are likely to be expended (as with the Environmental Assessments) trying to "normalize" apples and oranges when uniform approaches to many activities can be adopted (e.g., pre-closure safety analysis, socioeconomic modeling, safety?class lists, etc.) The normalization process may appear to an outsider like "cooking the books."]
o Objective 1
Build the applicant's program credibility, save time and manpower, and make selection processes relatively easier by adapting, to the extent practical, sound and transparent decision practices.
4.2.2.8 Use of Caveats
o Principle 1
Avoid unnecessary or premature commitments to the regulator unless a distinct program advantage results.
o Objective 1
Maximize DOE's flexibility in issue resolution by identifying and maintaining program options.
o Objective 2
Avoid unnecessary time-consuming explanations to outside parties as a result of re?adjustment of program goals and/or approaches to issue resolution.
[1] Until the Nuclear Waste Policy Act Amendment is clarified as to whether volunteer states would need to undergo characterization along with the NNWSI Project, this licensing principle is stated as if concurrent site characterizations are possible. However, the principle is equally applicable on an intra-project basis as a means to facilitate project comparisons and decisions on alternatives.