ML20206G641
| ML20206G641 | |
| Person / Time | |
|---|---|
| Issue date: | 06/19/1986 |
| From: | Goller K NRC OFFICE OF NUCLEAR REGULATORY RESEARCH (RES) |
| To: | Browning R NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS) |
| References | |
| NUDOCS 8606250394 | |
| Download: ML20206G641 (3) | |
Text
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a fOL JUN IS 1986 MEMORANDUM FOR: Robert E. Browning, Director Division of Waste Management, NMSS FROM:
Karl R. Goller, Director Division of Radiation Programs and Earth Sciences, RES
SUBJECT:
HYDROCOIN UPDATE As you are aware, we are currently a participating member of HYDROCOIN, an international ground-water modeling study.
To date, the purpose of the study -
to obtain improved knowledge of the implications of various strategies for ground-water modeling for the safety assessment of nuclear waste disposal - is being achieved. The first two levels of the HYDROCOIN effort - comparison of the numerical accuracy of the codes being exercised, and comparison of the capabilities of the codes to conform to data from in-situ measurements - are nearly complete. The third level - the quantitative assessment of impact of various physical phenomena on the rate and distribution of ground-water flows -
is beginning. Current plans for Level 3 call for sensitivity and uncertainty analyses to be performed on seven proposed cases. These analyses will explore appropriate ways of using hydrogeologic models in performance assessments, consider the effect of uncertainties in present and future hydrogeologic conditions, and compare different methodologies for sensitivity and uncertainty analyses.
The three NRC HYDROCOIN Project Teams (NRC staff, Sandia National Laboratories (SNL) and (voluntarily) USGS) have determined that five of the seven proposed Level 3 cases are very relevant to NRC's waste management program. Work on these five cases should provide useful insights to the NRC research and licensing effort. Briefly, these five cases are as follows:
1)
Case 1, Near-Surface Disposal in Argillaceous Media This case is based on shallow disposal of concrete encapsulated waste. Work on case 1 can benefit from and compliment ongoing NMSS and RES work being performed on alternatives to shallow land burial.
This case was proposed by the United Kingdom.
2)
Case 3, Regional Flow for a Bedded Salt Situation Case 3 is a regional ground-water flow problem based on a bedded salt formation. This case offers the type of regional flow problem that 62 4 860619 8606250394 PDR-
O NRC Staff might encounter at the time of licensing a HLW repository in salt. This case was proposed by ONWI.
3)
Case 2, Unsaturated Flow in Tuff Case 2 is an unsaturated flow problem based on field measurements made in a tuff formation. This case will involve sensitivity analysis of hydrogeologic parameters for deep disposal in partially saturated fractured tuff. This case was proposed by DOE.
4)
Case 4, Coupled Ground-water flow and Brine Transport Case 4 is an examination of the process of density-driven flow via a salt concentration. This case is analogous to some thermal problems where the density-driven flow is a result of thermal gradients. This problem may shed some light on the formation of convection cells in a salt HLW repository. This case was proposed by West Germany.
5)
Case 7, Efficiency of Particle Tracking Algorithms This case is designed to provide a means of comparing methods of particle trajectory calculation, independent of the model employed to estimate the potential surface.
Particle tracking is often used to determine potential flow paths and calculate ground-water travel times both of which are important to the demonstration of compliance with the Commisssion's waste regulations. This case was proposed by SNL.
Simulation of the Level 3 cases will provide informatior on:
- 1) the effects of parametric uncertainty, 2) the influence modeling assumptions have on model outputs, and 3) the impact on performance assessment due to different methodologies for sensitivity and uncertainty analysis. Additionally, the project teams will gain insights on modeling strategies and techniques that prove to be successful for a particular hydrologic setting.
It is extremely important to obtain " hands-on" experience for problems encountered in modeling realistic sites in terms of site characteristics, modeling assumptions, and numerical constraints. Work on the first two levels of HYDROCOIN has revealed that setting up and running hydrologic problems is not as direct and straight forward as would be hoped. For example:
the results of calculations are extremely sensitive to grid orientation and discretization; some particle tracking algorithms produce large errors (many algorithms have been modified as a result of HYDROCOIN participation); non-linearity in the numerical simulations for density-driven flow and partially saturated flow are extremely i
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. difficult for current numerical methods to handle (partially saturated flow, level 1, case 3, could not be performed by any project team); finite element and finite difference methods produced similar results even when complex geometries were involved.
Experience and familiarity with the idiosyncracies of modeling issues will be extremely useful in the licensing review.
Thomas Nicholson and Timothy McCartin of my staff are coordinating a meeting with the various project teams to decide which team will work which of the five Level 3 Cases.
In my opinion the benefit of HYDROCOIN to the NRC will be maximized if DWM staff members involved in hydrology, low-level waste disposal alternatives, and both HLW and LLW performance assessment participate in the HYDROCOIN effort. Hence I am requesting that one or two members of your staff be assigned to participate, part time, in the level 3 effort, beginning with participation in the above meeting.
The initial meeting will require about 1-2 days for review of the Level 3 proposals prior to attendance at the meeting. Time required to perform the simulation work depends on the particular cases worked by the NRC staff and will be discussed at this initial meeting, but should be on the order of 10%-20% of a staff year per staff over the next year.
Again, I urge you to have your staff participate in this effort.
Please indicate to me your decision by July 1, and if affirmative the DWM staff who will participate in the meeting and in subsequent HYDROCOIN efforts.
Karl R. Goller, Director Division of Radiation Programs and Earth Sciences, RES cc:
Paul Davis, SNL Richard Voss, USGS Richard Codell, WMGT/NMSS Distribution:
DCS/PDR Dross W0tt Circ /Chron KGoller TNicholson WMB Sbj/Rdg FCostanzi TMcCartin RMinogue W0tt
- Note See Previous Concurrences 0FC: RES:WMB *
- RES:ESB *
- RES:WMB *
- RES:WMB*
- RES:DRPES NAME:TMcCartin/mb:Nicholson :0tt
- FCostanzi
- KRGoller' DATE: 6/ /86
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