ML19262C509
| ML19262C509 | |
| Person / Time | |
|---|---|
| Issue date: | 02/08/1980 |
| From: | Robbins G NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS) |
| To: | White L NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS) |
| Shared Package | |
| ML19262C506 | List: |
| References | |
| REF-WM-12 NUDOCS 8002140118 | |
| Download: ML19262C509 (14) | |
Text
NOTE TO:
Larry White, Section Leader, Regulatory Cevelocment High-level Waste Technical Development Branch RCM:
Gary Robbins, Project Geologist Hign-level Waste Technical Development Brancn SUS ECT:
NOTES ON KEYSTONE TRIP, CCTOBER 21-25, 1979 As requested, enclosed are my notes on the Keystone meeting for incorporation into a trio report. My notes are divided into the following sections:
(A) Notes on the general meeting; (3) Notes on the NRC sponscred meeting on Part 60; (C) Extracted comments - specifically bearing on Part 60; (D) A listing of handouts and documents received at the meeting.
A.
NOTES CN THE GENERAL MEETING 1.
CCT. 22. 1979 Charles Fairhurst ocenec the meeting describing the Kejstone objectives.
These are to air all views on subjects and make recommendations to pertinent government agencies.
This meeting was one third cn waste management.
The first dealt witn the cacabilities of geochysical tecnniques.
The second examined site selection criteria using an overlay method.
As of yet, neither meeting has resulted in reports (see Sectier D for draft documents resulting from tnese meetings-1,2).
The objective of this meeting was to look at modeling in relation to deriving site suitability criteria (see Section D, for Agenda-6).
Opening remarks were followed by presentations of moceling by J. Bartlett, TASC; H. Burkholder, CCE (CWNI) and S. Scareurs, NRC (see Section D for hancouts-3,4,5).
The most significant points raised in :ne presentations bearing on criteria were:
(1) using a total system approach requires a consistent total performance; (2) present models are useful in identifying in a qualitative way important ozrimetes for criteria; (3) there are many factors and comoinations involved and, as such, it will be difficult to use mocels in cecisionmakina (i.e., there are many ways via calculations to achieve performance criteria and, as such, the models may not be heloful in determining wnat is an acceptable path); (4) in many areas models do not as of yet exist; (5) muca of the data needed for input is questionable; (6) given performance object.s 'i' may be possible to work backwards using models to derive criteria; (7) a possible approach to camcensate for uncertainties and to add engineering margins is to make the overall performance cbjects~very conservative; (3) there will be difficulty in modeling scme site selection factors because they are not technically cuantifiable; and (9) to use medeling really recuires a significant kncwledge of a site.
During discussicrs, it was noted tnat COE will scon put out criteria for site sele: tion-c' 80 09140 llo
2 Fred Donath (Univ. of Ill.) and Anthony 5tarfield (Univ. of Minn.)
formally responded to presentations.
Points emphasized here and in general discussion were:
(1) must look at the dynamics of a system, (2) criteria shculd ce set using sets of parameters; (4) multiple tests should be used to determine data for models; (5) in situ data bear only on the short term - natural analogues could be useful for extrapolations over the long term in consideration of spacial and temporal variations and for setting limits on carameters; (6) comparing sites should involve comoaring systems; (7) simoler models are better; (3) need connection between modeler and decisionmaker; (9) mcdels are helpful in identifying uncertainties and data to be collected but do not provide complete answers, and (10) moda.ls are best used in comparative assessments.
Discussions turned to thermcmecnanical interactions.
The most significant point raised here is that calculations for heat diffusion v ary.
This may be a result of whether one assumes thermal parameters are temoerature dependent or not.
A numcer of in situ heater tests are being or have teen conducted, e.g., Stripa, Climax, Cornwall, Eng., and in shale at several sites.
A numcer of thermomecnanical uncertainties were identified including questionable transferability of information, whether laboratory tests are representative, wnether models are apolicable at high temperature, wnether fracture distributions can be modeled (it was suggested that analyses include deterministic and stochastic assessments of fracture cistributions and mocels use worst case paraceters).
Discussions turned to waste / rock interaction.
Significant coints raised were:
(1) backfill can be used to control the geochemical environment, (2) cackfill can be used to control hydrolcgy, (3) atestions were raised as to what nearfield retardation buys you, (4) modeling nearfield is in oreliminary stages, and (5) nearfield is more amenable to testing than modeling.
Discussions turned to grouncwater transport and general tooics.
Otto Strack (Univ. of Minn.) discussec scme mcceling efforts using grachics to describe and illustrate ' low.
His metned a:: pears to be very suited for medeling fracture flow.
His modeling efforts acpear to be aole to handle cnanges in fractures with time and a variety of fracture gecmetrics. General discussions ijentified major questions:
validating models is a substantial problem, assessing fracture systems generally and on a site soecific basis is a substantive problem, when are data adequate (when is enough, enougn), a major problem in experiments is scaling, fracture ficw assessments are in preliminary stages.
It was noted that neterogenities tend to make path lengths longer.
2.
OCT 23. 1979 The meeting opened witn C. Fairnurst summari:ing the previous day.
Also, there was general discussion of the goals of the meeting.
It
3 was noped that out of the meeting would come suggestions for criteria.
Two significant questions raised wera:
whether one can subdivide a repository system, and how can one deal witn tne future in terms of making assessments.
Don Metley (Univ. of Ind.) spoke on error correcting institutions with regard to institutional approaches to siting.
E. Varanini (Cal. Energy Comm.) spoke on the California perspective of HLW disposal (see Section 0-7).
A major point made was that modeling analyses are not convincing and that there is a need for test facilities.
C. Heatn (COE) described ne 00E program.
Majo points here:
(1) a means has to be estaclished to close the process in a reasonable time, i.e., wnat we have to know and when do we have enough information to close an issue; (2) the 00E HLW program has grown dramatically (1976-54M; 1980-517CM): (3) a good deal of testing in tne US and elseshere is underway; (4) an international Kd data bank is being set oc.
J. Martin (NRC) gave a presentation on the progress being made on NRC criteria.
He amplified the Strawman nature of the tecnnical rule, i.e., numcers are not cast in concrete but are incluced to focus attention.
The meeting was open to generai discussion.
Major points raised were:
(1) tests are needed to validate models to get the degree of confidence necessary; (2) models can only be validated to a limited extent by short term tests; (3) models will have uncertainty and limitations in predictions over the long term; (4) models to assess future climate change are being develoced at CCE; (5) rather than viewing tests as to whether they validate a model one can assess whetner tney disprove a model; (6) assessments must be tased on the preponderance of evidence; (7) acceleratec testing nas a problem sita respect to cnanges in mechanisms; (3) modeling of human activities is perraps one of the most difficult modeling assessments; (9) a means of validating models is to assess one mocel vs. another model (tnis may De useful in assessing whether the math is correct);
(10) there are severe limitations in using models to derive criteria; and (11) questions of how to deal with resources and human intrusion must be resolved generically and early-on.
P. Romig (Col. Sch. of Mines) discussed results of the previous meeting on geophysical techniques (see Section 0-1).
Majorpoints raised here were:
(1) for a particular site the technology is available to assess a site by geophysical means; (2) geophysical techniques because they are remote and inferential do not give a comolete answer; (3) to decide on technictes to use requires site specific consideratiors; and (4) one can use resistivity to assess heat flow.
4 Discussions turned to a variety of topics.
These included:
(1) engineered barriers tend to increase the concentration of waste (It was noted that it might be preferential to allow some dispersion--30 meters may result in reducing concentrations down to an ore nody).
A letter was passed out oy P. Montague ouestioning the valiaity of the ore body comparison (see Section 0-3); (2) it was suggested that a repository be designed in a modular fashion; (3) engineered barriers should be assessed in context of natural analogues (how do natural barriers stop motion of material); (4) questions were raised regarding the assumption that a respository will ce saturated.
This was thougnt to be a valid conservative assumption.
C. Hollister presented an overview of the ocean discosal efforts.
3.
OCT. 24. 1979 The meeting opened with C. Hollister oresenting an overlay acoroach to site selection (see Section 0-2).
Points noted were:
(1) At the 1979 Tucson, Arizona meeting, ONWI oresented a similar approach; (2) proolems with overlays are grid si:e and dealing with areas that I ack information; (3) California r.as used the method to identify Cower plant sites; (4) there is a proolem with tradeoffs - how should they be made in a credible fashion, how do you weigh factors; (5) hcw should states be involved.
The meeting turned to discussions of a diversity of topics.
(1) Program for repository development - It appears that an operating recository won't be established until at least 1996; (2) Costs for excloration and site characteri:ation range (00E estimates apoear to be 30-100 million per site); (3) Relationship between modelling and criteria - discussion centered on estaclishing subsystem p'rformance objectivas and how it could be done; (4) engineered design - succort for doing a lot with engineering was expressed; (5) Modeling - There is a need for modelers and everyone else to start talking; suggestions for small worksnop. were endorsed; (6) need for criteria for testing, careful planning of tests and ex::eriments.
Conclusions drawn at the meeting were:
(1) we have to cepend on models; (2) multiple barriers are needed; (3) the NRC criteria shculd make allowance for change resulting frca technology advancing over the next 20 years; (4) there is a need for increasing communication between all those involved in HLW disposal and (5) there is a need to apply models at specific sites.
As a note, several other documents were distributed.
See Section D, Reference 10 (whether salt repositories are valid), llA and B papers by :t. Nelson on groundwater mcdeling, 9A and B attendees.
5 E.
NOTES CN THE NRC SPONSCRED MEETING 1.
OCT. 24, 1979 - Afternoon Session (See attendees list, Section 0-12 [ note not all attendees on list were present at the Oct. 24 meeting - just those with asteristics]).
The meeting opened with L. White describing rule.
General comments received were:
(1) Subsequent drafts should emphasi:e civil structure; (2) Present draft rule has no rationale as to wny go uncergrounc pnysical isolation; (3) Minimum depth of burial should include consiceration of botn natural crecesses and potential for human intrusion; (4) Distance for investigation (100Di) should be chosen on affects on repository performance; (5) Minimum distance was preferred: (5) There was a suggestion to defi:e distances on the casis of grouncwater basin anc acc cn affects due to other preesses; (7) There is a need for numerical quantities, particular minimums to describe the order of magnitude; (3) The criteria need traceacility anc rationale fully described - there was a suggestion for an in-depth paper to accompany rule (NUREG); (9) Rationale snould state system performance affect that is avoidec; (10) From now on rule should not be considered strawman; (11) It is hard to assess the intent of pcrtions of the rule; (12) The rule snould specify criteria to be met by any site, shouldn't have to compare sites.
Tecnnic'.1 rating will be difficult and may cause problems; (13) All agreed tnat cnaracterization at depth is needec; (14) BNL 1904 - Contained rationale why several sites need to be characteri:ed; (15) The idea that tecnnology is only acvanced for salt is invalid, other countries are anead on different media; (16) In terms of ccmoaring sites, there is a need to consicer probablistic assessments (e.g., salt and granite sites may meet deterministic criteria but the probacility of human penetration in salt is nigher); (17) It was suggested to put scenarios in rule; (13) Eacn site should meet safety criteria then assess environmental considerations; (19) Exclusion criteria - Definition of 'ault should include adverse nydrologic conditions of f ault; (20) More details on geochemistry in the rule is neeed particularly exclusion or avcidance criteria - J. Winchester said he would provide ideas (see
~
Section C-13); (21) Geochemical criteria snould apply to sih anc engineering barriers; (22) Geochemical in situ tests are needed including fluid ficw, stable isotope transport, injection tests, assessment of fluid and mineral chemistry, water dating; (23) A multiplicity of gecchemical tests are neeced - these include tests as to what conditions make nuclides move and wnat conditions hold them up; (24) Geochemical criteria should require siting where retardation is hign, and that waste forms not aggravate site retention -
capability; (25) A question was raised whether the NRC snculd ask for an NAS report en testing.
It was suggestec, to be timely, tne NRC could go directly to indivicuals.
These present sere pcsitite with regard to develocing a report en testing; (26) The 250 meter minimum may be tco s! allow in consiceration of ::enetrations.
6 2.
OCT. 25, 1979 A USGS letter in support of site characteri:ation was handed out (see Section 0-13).
L. 'nhite summarized previous day.
Consensus was reached on: (1) there is a need for site characteritation at depth; (2) several sites should be assessed, and (3) a repository snould be viewed as a civil structure, not a mine.
The day's discussion began with an iteration of the performance objectives.
Comments centered on performance objectives for the civil structure, as to whether criteria should be set on waste form or unether the waste form should be thougnt of as cart of the civil structure.
Comments reiterated the need for rationale behind numcers and the connection :etween subsystem per#crmance and overall performance.
Suggestions were made with regard to setting criteria on troublesome nuclides.
A suggestion was made that the rule rationale be in the EIS rather than in a separate report.
A1:a a suggestion was mace to allcw flexibility and variance from criteria in the rule. With regard to saturation, it appeared mest agreed tnat one should assume i t.
Most agreed that the civil structure should be tne place on ahich engineered performance criteria should ce set.
Also, suggestion was made that subsystems within a civil structure could nave minimum types of criteria.
Also, one could have combinations of criteria on civil structure subsystems.
There was confusion expressed on tne definition of waste package, particularly in light of the civil structure concept.
It was recommended that a acod criteria'would be ccmpability of system components.
The boundary of the civil structure was considered to be the limit of engineered structures.
The discussion turned to retrievability.
Questions were raised such as:
Uncer what conditions would you retrieve, having requirements regarding the ease of retrieval is questionable because it could always be mined out, the objective here is mine stacility and tne criteria should fccus on this. Also a suggestion was mace to separate retrievable versus recoverable.
Retrieving should focus on the operational period and taking waste out in the same form you put it in.
It was noted that retrievability has two implications:
(1) the waste fore maintains integrity; (2) the site is stable enough to rec 0ver the waste. Questions turned to what do you do once you have retrieved.
Is retrievability a resource or safety question?
It was suggested.that retrievability be part of emergency clans.
As a note a reference on retrievability was noted:
ERDA-7643.
A suggestion was made that the title of the rule be changed to excavatd continental repositories to dis'.inguish it from seabed and injection discosal.
Also the word "mineo" in the purpose and bases should be deleted.
The discussion turned to the siting requirements.
The questicn was raised as to whethea requirements recuire absolute oroof, particularly with regard to fault movement and paiechydrologic insta:ili.y.
Regarding fault'ng, the criterian should include adverse hydrologic
7 characteristics.
Concerning the time span of significance, tne question was raised as to snat do you do if you don't nave strati-graphy.
All agreed that the siting criteria need numerical require-ments, tnat the level of specificity must be increased and that requirements should relate to affects on site performance.
In terms of the exclusion criteria, it was suggested they should be applied depending on wnether some features or processes constitute a serious hazard.
Also, the criteria should be applied on a feature by feature basis.
The meeting turnec to resources.
It was suggested that resources clearly useful today and in the near future should be avoided.
Suggestions for criteria included, no high concentration of materials near a site, no monomineralic material near a site, materials at the site should have low concentration and be widespread.
A specific recommendation regarding P. 18, L,fii (word change) "have been known to be found." It was suggested resource criteria focus on three elements:
(1) concentrations should be below average crustal abundances; (2) consideration should be given to changes in accessibility with time, and (3) consideration should be given to comoetition with resources elsewnere.
The discussion turned to tne intruder.
It was suggested the criterica consider the frequency of penetrations with deoth.
Geoth reduces the pr0bability of intrusicn.
Also, consideration should focus not just on the encounter scenario but tne near miss.
For the intentional intruder, it was suggested the waste be spreac out.
The meeting ended with a suggestion that the staff tackle the major issues and send to Keystone refinements in our thinking.
C.
EXTRACTED C:MMENT5 SPECIFICALLY ON THE RULE
'he follcwing is a reiteration of a numoer of points directly related to ne further cevelopment of the rule.
The points are assemoled in a way to focus en their consideration.
1.
GENERAL RULE DEVELOPMENT a.
General Considerations (1) There must be an increase in communication between our modelers and rule developers particularly *ith regard to wnether the rule focuses on those parameters needed for modeling (See Section D-a).
(2) We must use our models to help set a consistent set of subsystem criteria.
8 (3) The 00E soon to be pub',ished site selection criteria should be obtained.
(4) We should expedite resolving as many generic issues as we can early-en.
These incluce, now we will handle the intruder (accidental and intentional) and resources near a site.
(5) The multiple barrier concept is f avored and should be stressed.
(6) We must expedite developing a cetailed rationale for requirements.
The idea of having a NUREG whicn explains tne rationale I believe is a good one and could be referencec in the EIS.
It was suggested we move to a draft rule and drop the strawman.
(7) Most support the concept of in situ testing at depth.
(3) To derive generic criteria abolicable to all media, we should assess work in other countries.
b.
Civil Structure Conceot (1) We should give consideration to tne tradeof f between confining waste vs. dispensing waste.
(2) Consideration should be given to a modular design.
(3) Engineering barriers snould be assessec with regard to natural analogues innibiting the motion of material.
(4) Most agreed with the idea of assuming saturation.
This assumotion should be exoanded.
(5) A good deal of succort was expressed for the civil structure concept.
The present rule should ce modified to reflect this concept more explicitly.
(6) Criteria should be considered on:
geochemical compatibility between engineered material and the site.
c.
Comoiring sites (1) Consideration should te given to comparing systems.
(2) We should consider all sites meeting minimum requirements.
(3) We must expedite developing car. king criteria to weigh sites.
9 (4) We should assess using probalistic analysis along with deterministic requirements in comparing sites, d.
Site Characterization (1) We should touch base with P. Romig (Col Sch. of Mines) on geophysical techniques for site characteri:ation and monitoring.
(2) BNL 1904 should be checked with regard to the need to do in death characterization at several sites.
e.
Testino and Investications (1) We snould consider requiring multiple tests for important carameters.
(2) We should consider usiig natural analogues for setting limits and for assessing tests over the long term.
(3) We should begin looking hard at fractures and describing their distribution.
Fractures appear to te very significant in assessing thermomechanical response.
We should consider botn deterministic and stochastic assessments be required.
(4) We shouid give a good deal of attention to nearfield analysis through testing.
(5) For site c5aracterization testing a lot of work is being done outs': e the US and snould be assessed.
(6) Our requirements on model validation should consider tests not only to validate but which may disprove mcdel.
(7) We should establish criteria on tne clanning of tests.
f.
Climate Chance The 00E moceling efforts on climate change should be assessed.
2.
SPECIFIC ELEMENTS fN RULE a.
Title Consideration should be given to changing the title and using
" continental excavated repositories."
b.
Purcose and Bases (1) The word " mined" should ce deleted and replaced by continental excavated repositories.
10 (2) The rationale for having continental excavated repositori".3 should be expressed, i.e., to increase physical isolation.
c.
Performance Cbjectives (1) We should consider setting performance objectives on the entire engineered system and subsystem criteria on comoinations which are minimums.
(2) We should consider requirements on troublesome nuclides.
(3) Comcatibility between engineered features and the site should ce assessed as a performance objective.
d.
Retrievability (1) This should be refinec in consideration of retrieving anc recovering.
The concept of ease of retrievability needs to be assessed in lignt of recoverability (mining tne whole thing out).
A possiale performance cojective nere is mine stability.
(2) The rule doesn't appear to be clear regarding the need for surface storage.
ERDA-7 93 should be cnecked on retrievability.
e.
Siting It would apoear we have to develop more specific and numerical criteria.
It appears it is preferred to nave minimums, develop criteria for extending minimums, and any variances.
Much more work is needed on gecchemical criteria.
(1) Exclusion Criteria (a) Faulting - definition should incluce adverse hycrolcgic characteristics.
(b) Adverse geochemical criteria are needed (see Section 0-13).
(c) The exclusion criteria should te refined to focus on individual processes and conditions.
(d) Criteria en resources should be assessed:
resources identified as clearly useful tcday and in the near future should be avoided, there shoulc be no high concentration of materials near a site, no menomineralic material near a site, materials at the site should have lower than average crustal abundance and be widespread.
Consideration should also be given to changes in accessibility witn time and c:mpetition with resources elsewnere.
11 (e)
P. 13, 1, iii should read " nave been known to be found."
(f) Exclusion criteria on potential penetrations should focus on frequency vs. depth and potential encounters and near misses.
(2) General Technical Recuirements (a) Distance for investigations (100KM) - we should consider the degree of affect of processes and factors on establishing distance. We should conside. tarting with groundwater basin and then add on distances depencing on affects.
(b) Time spans of significance - this needs to be refined in terms of wnat do you do in the absence evidence of more recent geologic processes.
(3) Preferred Criteria (a) Minimum depth 250M - the minimum depth c.iterion should be refined with reg 3rd to:
(1) combinations of processes (uplif* and erosion) and (2) the frequency of penetrations vs. depth.
(b) We should consider adding criteria on:
Sites where retarcation is hign and where ergineered structures will not aggravate retention.
(4) Site Characterization (a) More details are needed on geomechanical in situ tests.
(b) We should have a requirement en using multiple testing.
(c) We should consider tests directed at both conditions which may inhibit and accelerate the movement of nuclices.
D.
LISTING OF HANOCUTS AND OCCUMENTS OBTAINED AT MEETING 1.
Oraft letter from P. Romig to C. Hollister summarizing Keystone meeting on Geophysical Techniques.
2.
Oraft paper (for submission to science) cy C. Hollister and C. Fairhurst:
A Process for Selection of Sites for Radioactive Waste Repositories.
3.
J. Bartlett, handout: Generation of Site Suitability Criteria from Analytical Models.
12 J.
H. Burkholder, handout:
The Determination of Site Specifications by Isolation System Performance Modeling.
5.
- 5. Schreurs, handout:
Systems Models and Criteria Derivation.
6.
Agenda for Meeting.
7.
E. Vararini, handoct-Applying the Scientific Method to the Geologic Disposal of High-Level Nuclear Waste.
3.
Letter handout by P. Montague:
J.P. Holdren - to members of CONAES on Radioactive Waste Management.
9A.
Attendees list.
98.
Updated attendees list.
10.
R.O. Pohl, handout Nuclear Waste Discosal.
Can Salt be the Answer.
IlA+B.
R. Nelson:
Pacers on grounawater modeling accearing in June 1973 Water Resources Researcn, v.
14, #3, and in a BCS Richland, Inc.
Recort.
12.
(NRC Soonsored meeting attendees list).
13.
J. Winchester (and C. Fairnurst):
Suggested Rules Changes in Geochemical Area and on Isolation.
INPUT TO KEYSTOME TRIP REPORT - WM. MARK GRAYSON "y analysis of the Keystone meetings indicated that 'n general, thc 1RC attempt at developing criteria was well received. There appeared to be a consensus, however, that the efficacy of our approach would now be dependent on our ability to support the numbers and regulatory approaches identified in the str3wman regulation. Tre message which should come home loud and clear is: that it is alright to sat up strawman performance requirements and criteria to focus dis-cussions, but it is absolutelv necess3rv to orovide 3 triceable trail of docu-mentation wnich relates the reculatory recuirements to safety.
This should not te underestimated as many wnicn supported our acproaca at Keystone and likely elsewhere, will not provide continued support of our approach if we do a poor job of technically defending our criteria, performance objectives, or the basis for the multibarrier approach.
To provide the type of sup0crt needed, I feel it will be necessary to (1) care-fully layout what must be supported; (2) identify the type of effort needed to sup; ort the numbers or issues; (3) identify the outside contractual sup; ort necassary and in-house personnel needed to deveico the technical basis 3: d pro-vide traceabl9 documentation; and (4) most importantly, to carefully plan the length of time it will take to provide a defensible basis for our approach and technical requirements.
We shculd develop a plan and schedule for development of the needed documentation and technical support. This schedule would 3ddress on an issue by issue basis when the NRC anticipates providing the technical supoort and documentation, which we agreed to provide at the Keystone Conference.
The potential exists that our entire philosophy and approach will be called into question if we do 3 poor job of technically supporting our approach or performance recuirements.
Scme of the key activities which I feel are necessary to provide this support include:
Weneedtodetermineanddocumgnttherepositoryfailuremechanismswnichwe 1.
3 of 10 years, discuss the orobabilities of feel could exist over the first 10 those events occurring and relate them to our regulatory accroach 2.
Must identify the standardized set of scenarics across wnich tha 1RC will be analy:ing repository performance. This standardi:ed set of scanarics has :een needed for some time and will provide consideracle cuidance as to the focu: and intent of our regulatory requirements.
3.
Need to quantify the uncertainties in our ability to analyze repository system perfornance and discuss them in the context of those identified by EPA and OCE.
4 We need to utilize our systems model to lcok at the importance of various site features on repository performance. This will be necessary to pr0 vide a basis for our exclusion criteria and other numerical siting requirements. This must be done across the NRC's set of standardized scenarios and not just f:r a baseline case!
2 5.
We aill need to execute our systems model to evaluate the reduction in risk and uncertainties afforded by our regulatory re;uirements for the engineered facets of the re:ository system. This analysis would relate s;ecifically, the numerical require.nents on waste package performance and the #acilit/ design requirements to re ository system performance. This must also be evaluated across the standardized set of scenarios discussed atove, to avoid to the maxim.um extent practicable, scenario or assu.nption dependent results.
Having these results we can discuss the basis and rationale for our a oroach.
Scme discussions will be more cualitative tnan others but will still provide a logical framework for our regulatory a:;rcach.
My analysis of the Keystone meetings as well as the reccemendations are concurred in by Steve Schreurs.
.