ML20207N156
| ML20207N156 | |
| Person / Time | |
|---|---|
| Issue date: | 07/01/1987 |
| From: | Kane J, Tokar M NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS) |
| To: | |
| Shared Package | |
| ML20205F142 | List:
|
| References | |
| FOIA-88-361 NUDOCS 8810180532 | |
| Download: ML20207N156 (20) | |
Text
'..,
h Update on NRC Staff Position Regarding Engineered Alternatives
- by Joseph D. Kane and Michael Tokar Technical Branch Division of Low-Level Waste Management and Decommissioning Office of Nuclear Material Safety and Safeguards G
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Update on NRC Staff Position Recardina Encineered Alternatives by Joseph 0. Xane and Michael Tokar ABSTRACT This paper provides an update on NRC activities and strategy for dealing with alternative methods of disposal of low-level radio-active' waste.
Three principal areas are addressed:
(1) Activities involved in meeting Amendments Act milestones; (2) A conceptual design approach for a Mixed LLW disposal facility; and (3) The 00E/RAE conceptual design study.
With regard to the Amendments Act January 1988 milestone, the NRC is developing technical review criteria that will be incorporated into the Standard Review Plan.
Examples of draft review criteria are provided.
A conceptual design for a Mixed LLW disposal facility, consisting of an abovegrade tumulus with a double liner leachate detection and collection system, is discussed.
With regard to the DOE /RAE conceptual design study, some comments and observations are provided.
I. BACXGROUND As indicated by the title, "Update on NRC Staff Position Regarding Engineered Alternatives," this paper is intended to provide a status report on NRC's efforts on alternative methods of discosal of low-level radioactive waste.
In particular, the following three areas will be addressed:
- 1. Activities involved in meeting the Amendments Act Milestones;
- 3. Comments on the DOE /RAE Cenceptual Design Report.
However, as a first step in providing an update on the NRC "Staff Position" on engineered alternatives it is necessary to explain what that position has been and how i; evolved.
An earlier staff position was provided in the Branch Technical Position entitled, "Licensing of Alternative Methods of Disposal of Lcw-Level Radioactive Waste " which was published as an NRC NUREC report (Ref.
in December 1986 That report, wnich was originally published in draft form 1) with a Feceral Register Notice (Ref. 2) in March vf 1986, had as its primary objectives (1) the ideatification of alternative methods of disposal consicered to be within the framework of regulatory requirements of 10 CFR Part 61 (Ref.
3),
and (2) the publication of general guidance on various components of the alternative disposal systems.
The guidance satisfied a part of the requirements in Section 8(a) of Public Law 99-240 (Ref.
4), commonly known as the Amencments Act of 1985.
The NUREG report summarized the results of a study performed
2 in conjunction with the Army Corps of Engineers (COE).
That study had resulted in a multi volumed report (Ref. 5) and had identified five basic types of alternative disposal facilities:
1.
Aboveground Vaults 2.
Belowground Vaults 3.
Earth-Mounded Concrete Bunkers 4
Augered Holes (Shaft Disposal) 5.
Mined Cavities Some further details on the NRC staff posjtion on alternatives are contained in a paper entitled, "NRC Perspective on Alternative Otsposal Methods" (Ref. 6), which was delivered at the DOE 8th Annual Forum on Low-Level Waste in Denver in September 1986.- In that paper the following two points were emphasized:
1.
Although all five alternative methods of disposal identified in the COE study are workable and licensable under Part 61, the NRC will focus primarily on soil-covered options such as belowground vaults and earth-mounded concrete bunkers.
(Thus, aboveground vaults and mined cavities will receive minimal attention for the present.)
2.
The NRC will encourage standardization of designs, a
The focus on soil-covered options was founded on the realization that engineered structures for low-level waste disposal facilities would be required to perform on the order of 300 to 500 years.
Such structures will likely be constructed of Portland, cement-based concrete, which from a long-term materials durability standpoint requires protection from the deleterious effects of various climatological phenomena such as normal erosional forces, freeze / thaw cycles, and acid rain.
Thus, the earthern cover would provide protection for the concrete from adverse climatological effects and would also provide an additional barrier for radionuclide release and intruder protection.
The emphasis on stanoardization is intended to foster a uniform approach to the national program.
It also recognized that technical resources are limited and that it is not possible to provide guidance on all conceivable options and still meet the milestones and schedules established by the Amendments Act.
II. MEETING THE AMENOMENTS ACT MILESTONES As noted earlier, the Technical Position (Ref. 2), published as a NUREG report in December 1986, met the Amendments Act milestone that required the identifiestion of alternative disposal methods and the publication of technical guidance on such methods by January 1987.
NRC was also required to establish procedures and to develoo the technical capability to complete the review of a
3-license application within 15 months after receipt.
This requirement has been met by the NRC (for disposal by trench-type burial) through the issuance (in January 1987) of two guidance documents:
(1) a Standard Format and Content Guide (SF&C)(Ref. 7); and (2) a Standard Review Plan (SRP)(Ref. 8).
The SF&C is intended to show an applicant what types of information should be submitted with an application for a license for a disposal facility, while the SRP is intended to provide a staff reviewer with guidance on how to review the information provided.
Because the versions of the SF&C and SRP that were published in January 1987 primarily address Part 61-type trench burial, they must be augmented with further information concerning engineered structures and barriers.
To satisfy a third milestone of the Amendments Act, this process of augmentation must be complete by January 1988.
III. DEVELOPMENT OF REVIEW CRITERIA Updated versions of the Standard Review Plan and the Standard Format and Content Guide will thus serve as vehicles for establishing the technical infor-mation that must be provided by January 1988 on alternative disposal methods, and they will be tha means by which the NRC will satisfy the third nillestone of t.ke Amendments Act of 1985.
How will this be accomplished? To fully comprehend the answer to that question, one must have some basic understanding of the make up of the Standard geview Plan.
The SRP actually consists of several mini-review plans, each one of w;11ch addresses a particular review area.
There are. for example, several SRP sections that address the geotechnical characterization of the site.
Other sections deal with design and operations, financial assurance, quality assurance and so on.
At the heart.of each of these separate "Review Plans" is a subsection called "Acceptance Criteria."
It is in this subsection that the standards used to measure the acceptability of a system, component, or feature of a facility are listed.
While the Review Plans that currently exist do not contain acceptance critaria for engineered alternatives, the NRC staff will develop new criteria for appropriate portions of the SRP by January 1988.
The NRC staff is receiving assistance from the Corps of Engineers (COE), Brookhaven National Laboratory (BNL), and Battelle Pacific Northwest Latsratories (PNL) in the drafting of the new criteria.
As an aid in conceptualizing the issues that the acceptance criter)4 should address, the NRC staf f turned to a portion of the Code of Federal Regulations that was developed for reactors; viz., Appendix A to 10 CFR Part 50 (Ref. 9).
In that appendix are contained a set.of "General Design Criteria" (GCCs) that are intended to estaolish the minimal requirements for the Principal Design Criteria that are proposed by the applicant.
In an analogous fashion, the NRC staff, with the assistance of the COE, BNL, and PNL contractor staf f, is developing a set of GCCs for soil covered alternative disposal methods.
Like their reactor counterparts, the GOCs for alternative discosal facilities should provide valuable guidance tc both the designer and the regulator by establishing general principles of design that should ce followed in meeting the Performance Objectives of 10 CFR Pirt 61.
IV. EXAMPLES OF REVIEW CRITERIA Basically, the General Design Criteria can be regarded as an outline or framework upon which the specific acceptance criteria can be organized and l
shaped.
In other words, the accycance criteria, which will be incorporated into the Review Plans, will provide the specificity for the principles of design that are called out in the GDCs.
The discussion provided below is intended to demonstrate how this will be accomplished.
Eight major categories of criteria have been identified, and Ganeral Design Criteria have been developed for each of those areas.
Tea categories are as follows:
1.
Loads and Load Combinations 2.
Structural Design and Analysis 3.
Construction M.terials Quality and Durability 4.
Construction and Operations 5.
Quality Assurance t
6.
Structural Performance Monitoring l
7.
Filter and Drainage Systems 8.
Waste Cover Systems It is clear that this list of criteria categories is oriented toward the stryctural aspects of the disposal facility design.
It do45 not address other potential issues that c6uld be pursued by the facility designer, such as t
l potential trade-offs or changes that might be desired in regard to waste form or packaging.
The reason for this is that, as explained in the Denver paper (Ref. 6), the primary concern of the NRC is that there be reasonable assurance that the engineered structure will meet the Performance Obiectives of Part 61.
In particular, the use of an engineered structure should not introduce some new f actor that could compromise the capability of the facility to meet the Performance Objectives.
Of special concern in this regard is the capability of the engineered facility to satisfy the requirements for structural stability (for 300 years) and to contribute to the protection of the public from off-site j
releases (the 25/75 mrem dose limit).
i In considering the ability of the engineered structure to provide structural stability and to serve as a barrier to radionuclide migration, it is the opinion of the COE and NRC staff that a major concern that needs to be addressed is the likelihood for cracks to form in the concrete.
I/ crack formation can be minimized and mitigated, the concrete would retain strength, and pathways for water ingress into the structure and radionuclide egress out of the structure would be minimized.
Accordingly, most of the review criteria that have been drsfted for the engineered structures to date are concerned with ways to ensure the adequacy of design, quality of construction, and long-term durability of the concrete structure.
Some examples of draft review criteria are provided below for areas related to (1) structural loads and load comoinations. (2) construction material quality and durability, and (3) for filter and drainage systems.
5-ORAFT GENERAL DESIGN CRITERIA FOR LOADS AND LOA 0 COMBINATIONS, Structures, structural systems, and components essential for safe operation and closure should be designed to withstand anticipated actual loads and load coabinations.
Tine loads to be considered should include dead and live loads and loads resulting from naturally occurring events i
such as earthquakes, storms, tornadees, floods, tsunamis, hurricanes, and seiches, without failure or loss of capability of the structures, tystems, and components to perform their required functions.
The loads and load combinations used in the design of structures, systems and components that are essential for safe operation and closure should include consideratio.' of appropriate load factors and safety factors, as specified by the codes 2nd standards applicable to such designs. khere such codes and standards are not available, or may be inappropriate, i
designs should be based on sound engineering judgment and accepted practice.
The rationale for and justification of deviations from existing codes and standards should be fully documented in writing.
ORAFT GENERAL DESIGN CRITERION FOR CONSTRUCTION MATERIAL QUALITY AND O Structures, systems, and components should be composed, fabricated, and l
erected using materials which have been tested and shown to meet standards of quality and durability and which orovide reasonable assurance of long-term stability and integrity.
The testing methods and procedures from accepted and recognized codes and standards should be identified and evaluated to determine their applicability and adequacy.
ORAFT GENERAL DESIGN CRITERION FOR FILTER AND ORAINAGE SYSTEM Filter and drainage systems, including ma'terials, should be selected, i
designed and constructed to allow collection, monitoring. and removal of water that has infiltrcted through the waste cover system or otherwise entered the belowground vault interior.
1 As shown, these General Design Criteria are simple statements.
They, in a manner similar to that for the GOCs in Appendix A of Part 50, are intended to be straightforward, logical, and clear statements of the design, i
construction, testing and performance needs for the structural components.
j The specificity for these GCCs will be provided by specific design review 1
criteria similar to those that follow:
l
)
e ORAFT SPECIFIC DESIGN REVIEW CRITERION FOR LOA 0 COMBINATIONS The strength design method should be used for reinforced concrete structures.
The following load combinations should be used, where the required strength (U) is at least equal to the greatest of the following:
3 1.
U = 1.40 + 1.4F + 1.7L + 1.7H + 1,7E 2.
U = 1.40 + 1.4F + 1.7L + 1.7H + 1.7W 3.
U=0+L+H+T+E 4
U=0+L+H+T+W 0 = Oead Loads L = Live Loa s v
W = Wind Loac-E = Design Bas ' Earthquake T = Loads Resulting from Temperature Dit'ferences H = Lateral Earth Pressure
{
F = Lateral and Vertical Pressure of Li, aids
- i l
DRAFT SPECIFIC OESIGN REVIEW CRITERION FOR PORTLAND CEMENT CONC Portland cement concrete should be air-entrained and composed of Type v Portland cement, water, coars'a. and fine aggregate, and viitable 1
admixtures such as silica fume and other mineral fillers, that will enhance the quality and durability.
Water reducing admixtures (WRA) that i
reduce the water-cement ratio (W/C) and still produce a workable slump should be considered.
The unconfined compressive strength, f' should be t
t aminimumof3000PSIat28daysageandthemixedconcreteshfsldhavea l
slump within the range of 3 to 6 inches without WRA, Concrete mixed with j
WRA should have a slump within 6 to 9 inches.
i ORAFT SPECIFIC OESIGN REVIEW CRITER!ON FOR REINFORCING STEEL i
i Reinforcing steel should meet the requirements of ASTM standards A615, A616 and A617 and be epoxy coated in accordance with the requirements i
of ASTM A775.
i 1
i l
l "The presence of liquids in contact with the structure is not anticipated 4
in view of 10 CFR Part 61 siting and design requirements.
The term for j
liquid pressure is added for engineering conservatism.
l I
i.
ORAFT SPECIFIC OESIGN REVIEW CRITEPION FOR FILTFR AND ORAINAGE SYSTEM The exterior filter and drainage system should surround the belowground vault and be desi overlyirq cover. gned to prevent internal erosion and piping of the Collected liquids in the drains should be monitored to detarmine inflow quantities and be sampled and tested to establish chemical constituents and for radioactive contamination.
Treatment, if required, and discharge operations of collected liquids must meet applicable federal, state and local government requirements.
The above draft specific design review criteria are but a few of those that have been proposed by the Corps of Engineers as part of their technical assistance to the NRC.
As noted earlier, the specific criteria are intended to be used by the NRC staff in the review of the engineered structure and are intended to complement the General Oesign Criteria, which are directed primarily toward the designer and architect-engineer.
These review criteria are to be accompanied oy a report from the COE that describes the rationale cod basis for each criterion.
FairPy complete sets of criteria for the belowground vault and earth-mounded concrete bunker are expected by mid-August, in time to be distributed and discussed at the August 00E LLW Forum in Denver.
V.
CONCEPTUAL DESIGN APPROACH FOR MIXE0 LLW As is well known, there has been considerable interest of late in another type of alternative disposal facility; viz., one that would be suitable for disposal of "mixed easte."
The tenn "Mixed LLW" is the common name for I
low-level radioactive waste that contains not only source, byproduct, or special nuclear materials, but also chemical constituents which are hazardous I
under the Environmental Protection Agency (EPA) regulations in 40 CFR Part 261 (Ref. 10).
Because applicable NRC regulations exist to control the byproduct, i
source, and special nuclear material components of the Mixed LLW, while EPA has regulations for the control of the hazardous components, all of the individual constituents of Mixed LLN are subject to either NRC or EPA regulations.
However, when the components are combined to become Mixed LLW, neither Agency has exclusive jurisdiction under current Federal Law.
This has led to a situation where both Agencies, NRC and EPA, regulate the same waste.
I Inasmuch as the two Agencies have somewhat different approaches to the design of facilities for the long-term disposal of wastes, it has been a difficult task to develop a design concept that would satisfy the requirements of both Agencies simultaneously.
l, Nevertheless, there has been considerable progress in the develo9 ment of 4 conceptual design.toproach which demonstrates the integration of NkC and EPA requirements.
The approach is currently under management review in both Agencies.
The main hurdle that had to be overcome was the fact that the EPA regulations require the installation of two or more liners and a leachate detection, collection, and removal system above and between the liners. *hereas the NRC regulations in Part 61 recuire assurancs of long-term stability, minimization of contact of water with the waste, and avoidance of long term
maintenance.
The primary objective of the NRC regulations, in f act, is to preclude the development of the so-called "bathtub effect," where the waste could become immersed in liquid (e.g., from infiltration of surface water runoff) within a disposal unit excavation having a icw permeability bottom surface.
i In the design approach (Figure 1), the double liners and leachate l
collection and removal. system are contained within a layer whose placement precedes the emplacement of the Mixed LLW and the cover system.
The leak detection tank and leachate collection tank are encircled by a barm that controls surface water runoff from precipitation that would fall directly on the waste facility site.
The drainage pipes in the upper primary collection system would collect any leachate that could possibly develop above the top flexible membrane liner and below the emplaced wastc.
Any leachate collected would drain through the pipes to the primary leachate collection tank where i
the leachate would be tested and treated, if required.
The integrity and proper functioning of the primary leachate collection system would be checked i
j and verified by the lower collection system which would have pipes draining to the 1%ak detection tank.
The development of significant amounts of leachats i
from the solidified waste after closure would not be anticipated, however, because of the low-permeability waste cover system and final slope and surface i
grading that would minimize water infiltration.
It is anticipated that the area shown in Figure 3 oetween the slope of the final cover and the run-on i
i control berm beyond where the tanks are located would be regraded and the I
tanks removed following the 30 year post closure care period (required by EPA) i when leachate development and collection was shown by monitoring not to be a 4
problem.
Figure 2 provides the details required by EPA regulations for the double liners and leachate detection, collection and removal system.
The perimeter I
berm for leachate runoff control would assure that all leachate is collected belcw the waste and safely contained and transported through the drainage layers and pipes to the tanks located outside the final cover slope.
l j
.NRC's l
regulations requiring minimiting contact of the waste with water would be fulfilled by requiring tha waste to be placed above the level of the highest i
water table fluctuation and above the drainage layers where any leachate would collect.
The bottom elevation of the solidifled Mixed LLW would be required i
j in all instances to be at elevations above the top of the perimeter berm.
In the Section A-A on Figure 3 and on Figure 4, the design concepts for the i
i final cover over the solidified waste zone and the perimeter berm are presented.
l The actual zone for placement of solidified Mixec LLW may consist of different options, depending on the licensee's selection.
Options that could be considered include use of stable, high-integrity waste containers (HICs) that have the spaces between containers filled with a cohesionless, low-compressibility fill material or placement of the waste in an engineerec structure, such as a reinforced concrr.te vault.
A typical cover system over the saste is shown in Figure 4 The cover tystem would consist of (1) an 1
1 i
)
t
-9 outer rock or vegetative layer to resist erosion and provide for long-term stability, (2) a filter and drainage layer that permits a material transition to the underlying low permeability layers, (3) an impervious flexible membrane liner (FML) overlying a compacted low permeability clay layer, and (4) a filter and drainage layer beneath the compacted clay layer.
If the solidified waste zone does not consist of an engineered vault structure with a top roof, an additional compacted clay layer should be placed immediately above the emplaced waste to direct any water infiltration away from the waste zone.
Mixed LLW that contains Class C waste is designated by NRC's regulations would need to provide sufficient thickness of cover materials or an engineered intruder barrier to ensure the required protection against inadvertent intrusion.
Other variations on the previously described design approach could include placement of the Mixed LLW in an engineered reinforced concrete vault or in a steel fiber, polymer-impregnated concrete vault or in double-lined, high-iategrity containers that are hermetically sealed.
If proposed by license applicants, such alternatives would be reviewed by both the EPA and NRC on a case-by-case basis to evaluate their acceptability and confermance with established Federal regulations.
It is important to note that the earth-mounded, above grade waste pile disposal concept was developed for Mixed Waste as a result'of the dual rerJ1ation requirement.
It is a design concept th3t is intended to meet both NR0 and EPA criteria and thus it results in a complex design approach for disposal of a special waste category.
Otner, simpler design approaches may be developed by potential licensees.
The staff is concerned that some may assert that if this concept is good for Mixed LLW than it should apply to all low-level radioactive waste.
For normal low-level radioactive waste the NRC considers the design objectives of limiting contact of the waste with water, ensuring structural stability, and minimizing the need for long-term maintenance to be of paramount importance.
In the opinion of the NRC staff, those objectives can be met without the use of complex designs which include double liners or leachase collection systems that are necessary because of dual Experience shows that simple systems are more reliable and should regulation.
be used where permitted by the regulatory authority.
[
VI. THE 00E/RAE CONCEPTUAL DESIGN REPORT L
L The thrust of this meeting is centered on the COE/RAE Conceptual Design study and report.
Two of the primary objectives of this meeting are to (1) compare characteristics of variouc 0 sosal concepts and (2) develop an
-i understanding of the design and evaluation process for LLW disposal technologies.
Because of the complexity of the issues and cetails of the analyses, it will not be mossible to provide a very detailed discussion of the NRC review of the report nere in this paper, but some comments of a general nature are provided below.
1
~
f.
~
. First, both the Department of Energy and Rogers and Associates are to be commended for this ef fort and for providing this opportunity and forum for performing the activities listed above as the primary objectives of this
" semi na r. "
The report obviously has been and will cuntinue to be, extremely useful in' establishing dialogue on approac,hes that can be pursued.in meeting 10 CFR Part 61 Performance Objectives for land disposal of low-level radioactive waste.
The study and report are particularly useful in providing insight on (1) the types of features and components that a given design concept will have and (2) the funct'.cnal requirements that those design features and concepts must meet over designated design lifetimes.
Unfortunately, this is not where much of the att6ntion has been placed.
Instead, the primary focus has been placed on the comparison of disposal methods with one another, primarily on the basis of projecteo radiological doses and costs of construction and operation.
These comparisons are fine so long as it is understood that the results of these analyses are totally dependent on the assumed values of the input parameters and modeling assumptions used in the study.
in the text of the DOE /RAE report, "The comparisons... provide a basis forAs noted in improving the disposal concepts, designs, performance and costs and they illustrate the suggested primary areas of focus for these improvements.
As with any generic design, location or evaluation, the results should be used with caution, particularly where applying them to a specific sitJation which is different from t, hose stated in this report." The NRC is in total agreement with this statement.
The report provides a good starting point for a host 3
state considering alternatives; however, specific waste stream projections and siting parameters must be considered by the host state in its decision process.
Second, the NRC staff has few comments on the cost analyses performed as i
part of this stuoy.
There are two reasons for this.
One reason is that, as a regulatory Ager.cy, the NRC's primary mission is to protect public health and safety.
The Agency has determined that "improved trench-type shallow land burial" (of the type that meets Part 61 Perforinance Objectives) is adequate to protect public health and safety.
Therefore, it is not appropriate for the NRC to comment on cost aspects of disposal methods that incorporate more
)
expensive materials and facility design features.
As stated above (Ref. 6),
the primary responsibility of the NRC with regard to alternative methods of disposal is to determine that there is reasonable assurance that the particular i
method chosen will truly enhance performance and will not create a condition that could compromise the ability of the site to meet the Part 61 Performance t
Objectives.
It is for that reason that the NRC staff is especially concerned with the long-term durability of the concrete that would be used in the j
construction of an engineered structure, for if the structure fails, it could i
compromise the ability of tht facility to meet the stability, intrucer protection, and the 25/75 mrem off-site dose limit Performance Objectives.
3 i
k
Another reason '. hat the staff has few comments to offer on the cost projections is that the report does not provide much detail on how the projections were made.
For example, while it is interesting to note that the aboveground vault is estimated to cost about a third more than a belowground vault, the report does not provide the basis for the incremental cost.
Intuitively, one would anticipate the opposite relationship because an aboveground vault would not require excavations and presumably would not have additional cover either.
And, while some of the cost disparity might ce associated with certain more rigorous quality assurance requirements for an aboveground facility, it is not obvious that the level of quality assurance required for an aboveground unit would necessarily be much greater than for a belowground unit.
Third, a significant observation from the study is that the abovegrouno vault appears to be in a category of its own with regard to projected off-sito doses, costs, and required development time.
Notwithstanding the earlier remarks concerning the need for host states to be cautious in making comparisons from tnese analyses, it is somewhat comforting to see that the results of this study tend to support the NRC's decision to focus on soil-covered options such as belowground vaults.
A fourth comment is related to some differences that exist between the loac ccabinations listed on Page 4-20 of the DOE /RAE Conceptual Design Report and NRC's criterion for load combinations for reinforced concrete structures that was previously provided in Section IV of this paper.
The differences include (1) HRC does not require loading from tornado generated missiles or general aircraft missiles, (2) the loading from the design basis earthquake and wind are to be developed following the guidance in SRPs 2.3.2 and 2.2 (D.ef 8), respectively, rather than using the Uniform Building Code, and (3) the NRC requires consideration of loads resultir.g from temperaturw differences (during normal operating and closure conditions) that are not addressra by 00E/RAE load combinations.
There is agreement on load combinations that address dead and live loading and loads that include lateral earth pressures and pressure of liquids.
A fifth comment results from an observation made by the NRC staff when reviewing an earlier draf t of the DOE /RAE Conceptual Design Report.
The staff noted that a quality level assessment for major systens and ccmoonents of a disposal facility would be made on a case Dy-case basis after an evaluation of (1) the apolicant's cescription of the principal design criteria and (2) the technical ar.slyses that ould be performed to demonstrate compliance with the Performance Objectives of 10 CFR Part 61, Subpart C.
Based on the information provided on Table 5 +. page 5-21, of the DOE /RAE report, the staf f still considers this approacn to be necessary because some of the major systems and components wnich are listed as Quality Level Non-Q on Table 5-4, could more correctly be classified as Quality Level Q cecause of their potential importance for assuring safe operation and closure of a oisposal facility.
For example, 1
- 12 -
specific systems and comoonents on Table 5-4 that could be Quality Level Q might include the fill material, engineered surface for waste pla ement, drainage control system, contaminated water treatment facility and the envirvnmental monitoring system.
A final comment acknowledges and concurs with the statements in the 00E/RAE report relative to the difficulty in demonstrating the integrity and long-ter'n stability of reinforced concrete structures for a 300 to 500 year timeframe.
Through its technical assistance contracts with BNL and the COE, the NRC is addressing this problem by assessing the potential range of adverse internal and external environments of chemical attack.
. Based on this information, the NRC is requiring the best available techniques and construction materials to reoist this deterioration in the specific design review criteria.
The requiring of sulfate resisting Type V Portland cement, aomixtures, and epoxy-coated reinforcing steel are but a few of the examples on how this effort is being incorporated into the design requirements for the alternative methods.
It is the consensus of the NRC staff and its consultants that the serviceability, reliability, and long-term performance of reinforced concrete structures can be reasonably demonstrated. Alternative methods of disposal utilizing concrite structures would be acceptable when properly sited and designed in accordance with 10 CFR Part 61 requirements and in compliance with the high standards anc level of quality that are reflected in the review criteria that are currently being developed by the NRC.
VII.
SUMMARY
With the assistance of the Army Corps of Engineers, Brookhaven National Laboratory, and Battelle Pacific Northwest Laboratories, the NRC is developing technical review criteria for alternative methods of disposal of low-level radioactive waste.
The review criteria will be incorporated into the NRC's Standard Review Plan for low-level waste diseosal facilities.
The criteria will address technical areas of concern for soil-covered alternatives such as below ground vaults and earth-mounded concrete bunkers.
The criteria will be in place by January 1988, thus meeting an Amendments Act milestone.
The.NRC plans to meet with interested parties to discuss the draf t criteria and to get feedback that can be used to improve the criteria prior to the January milestone issuance date.
The NRC has been.orking with the Environmental Protection Agency (EPA) to develop a mutually acceptable conceptual design for disposal of Mixed LLW.
A desi.;.n concept that integrates the EPA requirement for two or more liners and a leachate detection, collection, and removal system as well as the NRC requirements for long-term stability, minimization of contact of the waste with water, and avolcance of active maintenance after site closure has teen ceveloped by the tecnnical staffs of both Agencies and is currently uncer management review.
The cesign concept is based on an above ground tumulus with a double liner leacnate detection / collection system and a berm around the perimeter of the facility for leachate runoff control.
NRC's regulations
for minimizing contact of the waste with water would be fulfilled by requiring the waste to be placed above the top of the perimeter berm.
i This conceptual dest n is being considered for Mixed LLW only and is not recommended for 10 CFR Part 61 disposal of low-level radioactive waste.
The DOE /RAE conceptual design study and report have been extremely useful in analyzing characteristics of various design concepts and developing understanding of the design and evaluation process for LLW disposal technologies.
In the opinion of the NRC staff, comparisens of the relative costs and ability of the metnods of disposal to meet Part 61 performance objectives should be performed with caution and a full understanding of the effects of assumptions used in the analyses.
VII.
REFERENCES i
1.
ll L. B. Higginbotham, et al., "Licensing of Alternative Methods of Disposal NUREG-1241, December 1986.of Low-Level RadioecITve Waste." U.S. Nuclee J
2.
"Branch Technical Position Statement on Licensing of Alternative Methods of Disposal for Low-Level Radioactive Waste," Federal Recister,
Vol. 51, No. 44, pp. 7806-7810, March 6, 1986.
3.
Nuclear Regulatory Commission, Code of Federal Regulations, Title 10 Part 61, "Licensing Requirements for Land Disposal of Radioactive Waste," 1982.
4 Public Law 99-240, Low-Level Radioactive Waste Policy Amendments Act of 1985.
)
5.
a.
R. D. Bennett, et al., "Alternative Methods for Disposal of Low-Level Radioactive Wasie,"NUREG/CR-3774, Volumes 2-5, October 1985.
i b.
C. C. McAneny, Vol. 6. October 1986.
i 6.
4 C. L. Pittiglio and M. Tokar, "NRC Perspective on Alternative Disposal Methods," presented at the 8th Annual 00E Low 5.evel Radioactive Waste
]
Forum, Denver, September 1986.
[
7.
Nuclear Regulatory Commission, "Standard Format and Content for a License l
Application for a Low-level Radioactive Waste Otsposal Facility,"
NUREG-1199, Januaty 1987.
8.
Nuclear Regulatory Comission, "Standard Review Plan for the Review of 1
a License Aoptication for a t.ow t.evel Radioactive Waste Disposal
{
Facility," NUREG-1200, January 1987.
i
}
a
-*' * * ~
4 14 -
r.
9.
Nuclear Regulatory Comission, Code of Federal Regulations Title 10, Part 50, Appendix A - General Design Criteria for Nuclear Power. Plants.
10.
Environmental Protection Agency, Code of Federal Regulations. Title 40, -
Part 261, "Identification and Listing of Hazardous Waste."
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