ML20132C915

Advises That Review of Rulemaking for 10CFR60 Amends Completed W/Approval for Continuation of Rulemaking. Rulemaking That Complies W/Legislation Should Not Be Exempt from Review Due to Effectiveness

ML20132C915
Person / Time
Issue date:	03/22/1985
From:	Dircks W NRC OFFICE OF THE EXECUTIVE DIRECTOR FOR OPERATIONS (EDO)
To:	Jennifer Davis NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS)
Shared Package
ML20132C473	List: ML20132C497 ML20132C535 ML20132C549 ML20132C703 ML20132C720 ML20132C915 NUREG-1046, Approves SECY-83-444 Re Proposed Amends to 10CFR60. Rulemaking Package Recommended for Use as Model for Evaluating Procedural Aspects of Proposed Technical Rules. Draft NUREG-1046 & Regulatory Analysis Encl
References
FRN-49FR5934, RULE-PR-60 AB44-2, NUDOCS 8504120465
Download: ML20132C915 (1)

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UNITED STATES 8

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t NUCLE AR REGULATORY COMMISSION WASHINGTON, D. C. 20555 k.....) MAR 2 21985 MEMORANDUM FOR: John G. Davis, Director Office of Nuclear Material Safety and Sefeguards FROM: William J. Dircks Executive Director for Operations SURJECT: CONTROL OF NRC RULEMAKING In a March 15, 1985, memorandum to me concerning control of NRC rulenaking, you requested that I (1) exempt several rulemakings, which comply with the Nuclear Waste Policy Act of 1982 (NWPA), from the review that I established to control rulemaking -(EDO memorandum dated February 13,1984) and (2) expedite or exempt this review for a rulemaking involving the final version of amendments to 10 CFR Part 60 concerning nuclear waste disposal in the unsaturated zone.

Regarding item 2 above, the review of the rulemaking has been completed, and I approven entionation of the rulemaking.

Regarding item 1 above, I .do not believe that rulenakings, which comply with legislation, Comission direction or my direction, should be exempted as a class from the rulemaking review that I established to control rulemaking. As my February 13, 1984 memorandum noted, it is important that (1) candidates for rulemaking are early and promptly identified, screened and thereafter periodically reviewed to determine whether or not to proceed with rulemakirg; (2) rulemakings are assigned priorities commensurate with their importance relative to accomplishing the NRC mission; and (3) rulemakings are timely, effective, efficient and of high quality.

The information required for the review is the same information contained in the Regulatory Analysis that is required to be part of the rulemaking package.

(See NUREG/BR-0058, " Regulatory Analysis Guidelines of the U.S. Nuclear Regulatory Commission," January 1983.)

Accomplishing this review on an annual basis assures that the rulemaking will be reviewed in light of current infornation and circumstances which could be i

significantly different than those existing when the rulemaking was initiated or last reviewed. The involvement of the Office of Research (RES) assures that current research findings are considered in the review of each rulemaking.

Willi 1. Dircks Executive Director for Operations V. Stello J. Roe H. R. Denton J. Taylor -

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March 27, 1985 '% , , , , , * 'f SECY-85-109 RULEMAKING ISSUE (Affirmation) i"jY JP For: The Commissioners From: William J. Dircks Executive Director for Operations-

Subject:

AMENDMENTS TO 10 CFR PART 60--DISPOSAL OF HIGH-LEVEL RADI0 ACTIVE WASTES IN GE0 LOGIC REPOSITORIES

Purpose:

To obtain Commission approval of a notice of final rulemaking.

Category:

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This paper involves a minor policy question.

'Xssue: Should 10 CFR Part 60 contain specific criteria for geologic disposal of high-level radioactive wastes in the unsaturated zone.

Summary: This paper presents final amendments which will assure that NRC regulations address considerations relevant to all geologic repositories whether sited in the sattrated or unsaturated zone. Staff ~ recommends that the Commission approve for publica-tion as final amendments to 10 CFR Part 60 specific technical criteria for geologic disposal of high-level radioactive wastes within the unsaturated zone. Since resource needs to implement 10 CFR Part 60 have been reflected in programmatic budget requests no significant new resource expenditures will be required by

issuance of these amendmeats.

Background:

The Commission published for public comment proposed amendments to 10 CFR Part 60 which contained specific technical criteria related to disposal of high-level radioactive wastes within the unsaturated zone on February 16, 1984 (49 FR 5934). The recom-mended final amendments were developed following consideration of the comments received from fourteen groups and individuals.

The recommended final amendments were presented before the ACRS Waste Management Subcomrgittee on July 11, 1984, and were discussed during the 292nd ACRS meeting, August 9-11, 1984.

Discussion: Regulations which established procedures for licensin, the disposal of high-level radioactive wastes (HLW) in geologic

Contact:

C. Ostro,eski, CS l X74615 eg t\ AY l

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Tha Commissioners 2 repositories were published on February 25, 1981 (46 FR 13971). 1 Proposed technical criteria against which license applications i would be reviewed under 10 CFR Part 60 were published for public comment on July 8, 1981 (46 FR 35280) and final technical criteria were promulgated on June 21, 1983 (48 FR 28194).

In the statement of considerations to the proposed technical criteria the Commission explained that the proposed criteria were developed for disposal in saturated media because the then current plans of the Department of Energy (DOE) called for disposal at sufficient depth to lie solely within the hydrogeologic region called the saturated zone (46 FR 35281).

The Commission further noted that additional or alternative criteria may need to be developed for regulating disposal in the unsaturated zone.

The Commission approach was criticized by several commenters, including DOE and the U.S. Geological Survey. The bases for this criticism were that (1) disposal of HLW within the unsaturated zone was a viable alternative to HLW disposal within the-saturated zone and (2) since the Part 60 technical criteria were generally applicable without regara to the possibility of saturation, their scope and applicability should not be unduly restricted. The NRC staff reviewed the technical criteria in light of the public comments 'and found this criticism to be well-founded. The staff drew the possibility of further rulemaking in this area to the Comission's attention in SECY-83-59.

j In the statement of considerations to the final technical criteria the Commission recognized that although th'e final tech-nical criteria were generally appropriate to disposal in both the saturated and unsaturated zones, some distinctions were needed (48 FR 28203). Rather than promulgating the specific criteria-which would apply to the unsaturated zone at the time the final technical criteria were published in June 1983, the Commission stated that it preferred to issue such criteria in proposed form so as to afford further opportunity for public comment. Proposed amendments developed in response to this Commission decision were published for public comment on February 16, 1984 (SECY-83-444; 49 FR 5934). Enclosure C contains a copy of the proposed amend-ments as published in the Federal Register. The proposed amend-ments contained provisions for new definitions (S60.2) and favor-i able and potentially adverse siting criteria (560.122) related to HLW disposal within the unsaturated zone. Additionally, in the statement of. considerations which accompanied the proposed amend-ments, the Commission particularly sought public comment on ques-tions related to groundwater travel time calculations in unsaturated geologic media (49 FR 5937).

i Ths Commissioners 3 In conjunction with the proposed amendments, NRC_ published draft NUREG-1046 -- Disposal of High-level Radioactive Wastes in the 'l Unsaturated Zone: Technical Considerations for public comment.

The Commission received a total of fourteen comment letters in response to its solicitation of public input on both the proposed amendments and draft NUREG-1046. In general, these commenters

-supported the Commission's proposed action and raised no signifI-cant new issues with respect to this rulemaking action. The com-menters primarily addressed the questions posed by the Commission on groundwater travel time calculations and suggested word changes to the proposed amendments for the sake of clarity and technical

. accuracy.

Current technical criteria governing the post-emplacarunt perform-ance of the particular barriers (i.e. engineered barriers and geologic setting) of the geologic repository system are set forth .

at $60.113 (48 FR 28224). The post-closure performance criteria for the geologic setting (S60.113(a)(2)) require that the geologic repository be located so that pre-waste emplacement groundwater travel time along the fastest path of likely radionuclide travel from the disturbed zone to the accessible environment be at least 1,000 years or such other travel time as may be approved or specified by the Commission (48 FR 28224).

,In the statement of considerations which accompanied the proposed amendments the Commission discussed several reasons why calculations of pre-waste emplacement groundwater travel time along the fastest path of likely radionuclide travel through the unsaturated zone could have large associated uncertainties, and hence could be of questionable value in estimating the capability of the geologic setting to isolate HLW from the accessible environment (49 FR 5936). The Commission stated that-if DOE could demonstrate with reasonable assurance that travel time for groundwater movement through the unsaturated zone can be quantified, then DOE should be allowed to include such travel time when demonstrating com-pliance with 560.113(a)(2). The Commission also recognized that it may be more appropriate to specify another parameter upon which perfonnance may be evaluated for a geologic setting in the unsatu-rated zone, or to utilize the approach set forth in S60.113(b) which provides the Commission with the flexibility to specify variations in the performance objectives on a case-by-case basis, as long as the overall system performance objective is satisfied.

Therefore, to solicit public input on groundwater travel time in the unsaturated zone the Commission posed two questions on this issue in the statement of considerations (49 FR 5937). These

questions requested public comment on

1) how groundwater travel time in the unsaturated zone could be determined with reasonable assurance, and whether or not the existing groundwater travel time performance objective in 660.113(a)(2) should be limited to ground-  !

water movement within the saturated zone; and 2) whether ground- l

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The Commissioners 4 water travel time is an appropriate measure of performance for a site within the unsaturated zone or whether an alternative perform-ance cbjective would be more appropriate. The issues surrounding the groundwater travel time calculations were specifically addressed by seven of the fourteen commenters on the proposed amendments and

. draft NUREG-1046. A discussion of the views expressed by these commenters is contained in Enclosure A (pp.4-14) while the individ-ual comments on groundwater travel time are categorized in Enclo-sure D (pp. 4-16).

Following consideration of the public comments on groundwater travel time calculations, the staff recomends that the Ccamis-sion maintain its original position as set forth at 49 FR 5936 that if DOE can demonstrate with reasonable assurance that travel times'for groundwater movement through the unsaturated zone can be quantified, then DOE should be allowed to include such travel times when demonstrating compliance with S60.113(a)(2). However, the staff recognizes that for the unsaturated zone it may be more appropriate in some cases for the Commission to utilize the approach set forth in 560.113(b) which,-as mentioned above,. pro-

.vides the Commission with the flexibility to specify variations in performance objectives on~a case-by-case basis as long as the overall system performance objective is satisfied.

Although no change was made explicitly to the groundwater travel time provisions of $60.113(a)(2), the proposed definition of the term " groundwater" set forth at $60.2 would clarify that S60.113(a)(2) is equally applicable to geologic repositories within either the saturate.i or unsaturated zone. Similarly, the recommended amend-ment to the Siting Criteria (S60.122(b)(7))-would have the effect of making pre-waste-emplacement groundwater travel time along the fastest path of-likely radionuclide travel from the disturbed zone to the accessible environment which substantially exceeds 1,000 years a favorable condition for HLW disposal within either hydrogeologic zone.

In response to the comments which addressed other provisions of the proposed amendments, several word changes have been made for the sake of clarity and technical accuracy. A detailed discussion of the changes recommended by the staff can be found in the draft Federal Register notice (Enclosure A). In. addition to these changes, new amendments containing modifications to existing pro-

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visions of $560.133 and 60.134 are also included in the recommended final amendments. The provisions of SS60.133(f) and 60.134(b) have been modified to more clnsely identify the concept of a potential for creating a preferential pathway for groundwater to contact the waste packages. This' change was prompted by a com-menter's observation that as originally. worded, these provisions might not be internally consistent with proposed $60.122(b)(8)(iv)

< r The Commissioners 5 which identified a host rock that provides for free drainage as a favorable hydrogeologic condition in the unsaturated zone.

Further, minor word changes were made to these two provisions for the sake of-technical accuracy.

A staff analysis of the public comments on the proposed amend-ments and draft NUREG-1046 is provided in Enclosure D. The staff considered all public comments in developing the recommended final amendments.

The staff has reviewed the provisions of the final 00E Siting Guidelines related to the unsaturated zone against the recom-mended final amendments to 10 CFR Part 60 and has determined that the DOE Siting Guidelines are not in conflict with the 10 CFR Part 60 amendments.

NRC resource needs to implement the provisions of 10 CFR Part 60 have been reflected in programmatic budget requests. Thus, no significant new resource expenditures will be required by issuance of these amendments.

Recommendations: That the Commission:

1. Approve for publication as final amendments to 10 CFR' Part 60 specific technical criteria for geologic disposal of HLW in the unsaturated zone and the accompanying Statement of Considerations, as set'forth in the draft Federal Register notice in Enclosure A.

2. Certify that this rule, if promulgated, will not have a significant economic impact on a substantial number of small entities. This certification is necessary in order to satisfy the requirements of the Regulatory Flexibility Act, 5.U.S.C. 605(a).

3. Note:

a. The changes made to the proposed 10 CFR Part 60 amendments as published in the Federal Register are provided in comparative text in Enclosure 8.

b. Enclosure C contains a copy of the proposed amendments as published in the Federal Register on February 16, 1984.

c. The detailed staff analysis of public comments on the proposed amendments and draft NUREG-1046 is contained in Enclosure D. (Draft NUREG-1046 is currently under review by the staff and will be revised to reflect 1

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The Commissioners 6 changes made in the unsaturated zone amendments. When this draft report has been revised it will be published as a final NUREG report).

d. A regulatory analysis is presented as Enclosure E.

e. A review of a draft version of the recommended final amendments was presented before the ACRS on July 11, 1984. Enclosure F is a copy of the August 14, 1984 letter from J. C. Ebersole, Chairman, ACRS to Chairman Palladino.

f. As provided by Section 121(c) of the Nuclear Waste Policy Act of 1982, no environmental assessment is being prepared'in connection with this action.

g. This rule contains no new or amended recordkeeping, reporting, or application requirement, or any other type of information collection requirement, subject'to the Paperwork Reduction Act (Pub. L.96-511).

h. The Chief Counsel'for Advocacy of the Small Business

~ Administration will be informed by the Division of Rules and Records of the certification regarding economic impact on small entities.

i. The Subcommittee on Energy and the Environment of the House Interior and Insular Affairs Committee, the Sub-committee on Nuclear Regulation and the Senate Committee on the Environment and Public Works, the Subcommittee on Energy, Nuclear Proliferation and Federal Services of the Senate Committee on Government Affairs, and the Subcommittee on Energy and Power of.the House Interstate and Foreign Commerce Committee will be informed of this rulemaking action by a letter similar to Enclosure G.

j. The Office of Public Affairs has determined that'it is not necessary to issue a public announcement on these amendments.

Scheduling: If scheduled on the Commission agenda, the staff recommends this paper be considered at an open meeting. While no specific cir-cumstances require Commission action by a particular~date, the

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The Commissioners 7 Commission should be aware that the Department of Energy is currently considering certain unsaturated geologic media as

. potential repository sites.

J.y -( 4' k \.' l _. .

William J. Dircks i

Executive Director for Operations i

Enclosures:

A. Federal Register Notice Containing Final Amendment's to 10 CFR 60 i B. Comparative Text Version of Amendments C. Federal Register Notice on Proposed Amendments

- D. Staff Analysis of Public Comments E. Regulatory Analysis F. ACRS Comments on Amendments G. Draft Congressional. Letter

• i Commissioners' comments should be provided directly to the Office'of the Secretary by c.o.b. Thursday, April 11, 1985.

J Commission Staff Office comments, if any, should be submitted to the Commissioners NLT Thursday, April 4, 1985, with an information copy to the Office of the Secretary. If the paper is of such a nature that it requires additional time for analytical review and comment, the Commissioners and the Secretariat should be apprised of when comments may be

expected.-

This paper is tentatively scheduled for affirmation at an Open Meeting during the Week of April 15, 1985. .Please refer'to the appropriate Weekly Commission Schedule, when published, for a specific date and time.

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ENCLOSURE B 4

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[7590-01]

PART 60 - DISPOSAL OF HIGH-LEVEL RADI0 ACTIVE WASTES IN GE0 LOGIC REPOSITORIES

1. The authority section for Part 60 continues to read as follows:

Authority: Secs. 51, 53, 62, 63, 65, 81, 161, 182, 183, 68 Stat.

929, 930, 932, 933, 935, 948, 953, 954, as amended (42 U.S.C. 2071, 2073, 2092,2093,2095,2111,2201,2232,2233): secs. 202, 206, 88 Stat. 1244, 1246, (42 U.S.C. 5842, 5846); secs. 10 and 14. Pub. L.95-601, 92 Stat.

2951 (42 U.S.C. 2021a and 5851); sec. 102, Pub. L.91-190, 83 Stat. 853 (42 U.S.C. 4332); sec. 121, Pub. L.97-425, 96 Stat. 2228 (42 U.S.C.

10141).

For the purposes of sec. 223, 68 Stat. 958, as amended (42 U.S.C.

2273). $$ 60.71 to 60.75 are issued under sec 1610, 68 Stat. 950, as amended (42 U.S.C. 2201(o)).

[ir] 2. Section 60.2 is amended by adding two new definitions in proper alphabetical sequence and revising an existing definition:

% 60.2 Definitions.

" Groundwater" means all water which occurs below the [Earthis] land

surface.

" Saturated zone" means that part of the earth's crust beneath the

[ deepest] regional water table in which all voids, large and small, are ideally filled with water under pressure greater'than atmospheric.

" Unsaturated zone" means the zone between the land surface and the regional [ deepest] water table. Generally, [ water] fluid pressure in this zone is [under] less than atmospheric pressure, and some of the voids may contain air or other gases at atmospheric pressure.

Beneath flooded areas or in perched water bodies the [ water] fluid pressure locally may be greater than atmospheric.

1 Enclosure B

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[2r] L Section 60.122 is amended by revising paragraphs (b)(2)(iii) and (c)(9), redesignating paragraph (b)(2)(iv) as (b)(7),

and adding new paragraphs (b)(8), (c)(22), (23) and (24) to read as follows:

6 60.122 Siting criteria.

(b)

(2)***(iii) Low vertical permeability and low hydraulic [petential]

gradient between the host rock and the surrounding hydrogeologic units.

(7) Pre-waste-emplacement groundwater travel time along the fastest path of likely.radionuclide travel from the disturbed zone to the acces-sible environment that substantially exceeds 1,000 years.

(8) For disposal in the unsaturated zone, hydrogeologic conditions that provide--

(i) Low [and-nearly-eenstant] moisture flux in the host rock and in the overlying and underlying hydrogeologic units; i (ii) A water table sufficiently below the underground facility such~that fully saturated voids continuous with the water table do not encounter the underground facility; (iii) A laterally extensive low-pemeability hydrogeologic unit above the host rock that would inhibit the downward movement of water or divert downward moving water to a location beyond the limits of the underground facility; (iv) A host rock that provides for free drainage; or (v) A climatic regime in which the average annual historic precipitation is a small percentage of t'he average annual potential l l evapotranspiration.

r (c) ***

(9) [Fer-disposal-in-the-saturated-monev]Groundwaterconditions in the host rock that are not reducing.

2 Enclosure B

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(22) Potential for the water table to rise sufficiently so as to i cause saturation of an underground facility located in the unsaturated  !

zone.

(23) Potential for existing or future perched water bodies that may

[have-the-effeet-ef-saturating]-saturate portions of the underground facility or [ prev 4 ding] provide a faster flow path [fer-radienwelfde sevement] from an underground facility located in the unsaturated zone to the accessible environment.

(24) Potential for [vaper-transpert-of-radienwelfdes-from-the-under-ground-faeility-leeated-in-the-unsaturated-mene] the movement of radio-nuclides in a gaseous state through air-filled pore spaces of an unsaturated geologic medium to the accessible environment.

4_._ Section 60.133 is amended by revising paragraph (f) to read as follows:

% 60.133 Additional design criteria for the underground facility.

(f) Rock excavation. The design of the underground facility shall incorporate excavation methods that will limit the potential for creating a preferential pathway for groundwater to contact the waste packages or [Padieastive-waste] for radionuclide migration to the accessible environment.

h Section 60.134 is amended by revising paragraph (b)[-(1)-]

to read as follows:

6 60.134 Design of seals for shafts and boreholes.

(b)

(1) The potential for creating a preferential pathway for ground-water-to contact the waste packages or [radfeastive-water] for radio-nuclide migration through existing pathways.

3 Enclosure B

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9 ENCLOSURE A

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NUCLEAR REGULATORY COMMISSION AMENDMENTS TO 10 CFR PART 60 Disposallof High-Level Radioactive Wastes in Geologic Repositories AGENCY: Nuclear Regulatory Commission.

ACTION: Final rule.

SUMMARY

The Nuclear Regulatory Commission (NRC) is amending its regula-tions for the disposal of high-level radioactive wastes in geologic repositories. These amendments will ensure that the rule contains 1

specific criteria for the disposal of high-level radioactive wastes within the unsaturated zone. This action is necessary to assure that NRC regulations address considerations relevant to all geologic repositories, whether sited in the saturated or unsaturated zone.

EFFECTIVE DATE:

FOR FURTHER INFORMATION CONTACT: Dr. Frank'A. Costanzi, Office of Nuclear Regulatory Research, U.S. Nuclear Regulatory Commission, Washington, DC 20555, telephone (301)427-4362.

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1 Enclosure A 7 - ? *

[7590-01] 1 SUPPLEMENTARY INFORMATION:

BACKGROUND ,

On February 25, 1981, the Nuclear Regulatory Commission (NRC) promulgated a rule that' established procedures for licensing the disposal ,

1 of high-level radioactive wastes (HLW) in geologic repositories

-(46 FR 13971). NRC promulgated technical criteria to be used in the evaluation of license applications under those procedures on June 21, 1983 (48 FR 28194). Although these technical criteria are generally appropriate to disposal in both the saturated and unsaturated hydrogeologic zones, some further distinctions need to be made .

for disposal in the unsaturated zone. Consequently, the Commission j expressed its intent to issue specific technical criteria for the l unsaturated zone after promulgating the final technical criteria so as to I

! afford further opportunity for public comment on this issue. Proposed

, amendments to these technical criteria to include HLW disposal within

either the saturated or unsaturated zone were published for comment on-February 16, 1984. These proposed amendments contained provisions for new definitions and favorable and potentially adverse siting criteria.

In addition to the proposed amendments,-the Commission specifically requested public input on two questions related to groundwater travel time calculations within the unsaturated zone. In conjunction with the proposed I 4

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2 Enclosure A i

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amendments, the Commission published for public comment draft NUREG-10461 which contained a discussion of the principal technical issues considered by the Commission during the development of the proposed amendments.

SUMMARY

OF CONNENTS AND CHANGES A total of fourteen groups and individuals commented on the proposed amendments and draft NUREG-1046. There was general acceptance of the Commission's view that disposal of HLW within the unsaturated zone is a viable alternative to disposal within the saturated zone. The commenters addressed the Commission's~ specific questions on groundwater travel time within the unsaturated zone and provided additional comments suggesting word changes to improve the technical accuracy and clarity of the proposed amendments. The principal comments received on the questions and proposed amendments, and the Commission's corresponding responses, are discussed below. Changes and clarifications made in the rule as a result of the Commission's consideration of these comments are also explained in this section. Copies of the individual comment letters and a detailed analysis of these letters by the NRC staff are available in the NRC Public Document Room, 1717 H Street NW., Washington, DC 20555.'

' Draft NUREG-1046 -- Disposal of High-Level Radioactive Wastes in the Unsaturated Zone: Technical Considerations is currently being revised to reflect changes made in the amendments to 10 CFR Part 60 related to HLW disposal within the unsaturated zone. When this revision is completed, a copy of NUREG-1046 will be placed in the Commission's Public Document Room. Upon publication, copies of NUREG-1046 may be purchased by calling (301) 492-9530 or by writing to the Publication Services Section, Division of Technical Information and Document Control, U.S. Nuclear Regulatory Commission, Washington, DC 20555, or purchased from the National Technical Information Service, Department of Commerce, 5285 Port Royal Road, Springfield, VA 22161.

3 Enclosure A

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j (a) . Groundwater Travel Time Calculations.

Technical criteria governing the post-emplacement performance of the particular barriers of the geologic repository system (i.e. engineered j- barriers and geologic setting) are set forth at 860.113 (48 FR 28224; i

June 21, 1983). The post-closure performance critericn for the geologic 4

setting set forth at $60.113(a)(2) requires that the geologic repository be i located so that pre-waste-emplacement groundwater travel time along the t

fastest path of likely radionuclide travel from the disturbed zone to the i

accessible environment be at least 1,000 years or such other travel time as may be approved or specified by the Commission. Although no change was made explicitly to the provisions of $60.113(a)(2) in the proposed j amendments for the unsaturated zone, the proposed definition of the

] term " groundwater" set forth~at $60.2 would clearly make the scope of

{ $60.113(a)(2) applicab,le 'to geologic repositories within eit'her the '

l saturated or unsaturated zone. Similarly, the proposed amendment to the i

, Siting Criteria ($60.122(b)(7)) would have the effect of making

• i

, pre-waste-emplacement groundwater travel time along the fastest path of 1

likely radionuclide travel from the disturbed zone to the accessible environment which substantially exceeds 1,000 years a favorable condition for HLW disposal within either hydrogeologic zone.

In the statement of considerations which accompanied the. proposed amendments, the Commission discussed possible limitations of the pre-

] waste-emplacement groundwater travel time performance objective of

$60.113 when applied to the unsaturated zone. However, the Commission stated that if DOE could demonstrate with reasonable assurance that

travel time for groundwater movement through the unsaturated zone can be I quantified, then DOE should be allowed to include such travel time when s

4 Enclosure A

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[7590-01]

demonstrating compliance with $60.113(a)(2). The Commission also acknowledged that it may be more appropriate to specify another parameter upon which performance may be evaluated for a geologic setting in the unsaturated zone, or t'o use the approach set forth in 560.113(b) which provides the Commission with the flexibility to specify variations in performance objectives on a case-by-case basis, as long as'the overall system performance objective is satisfied. Further, the Commission observed that calculations of pre-waste emplacement groundwater travel time along the fastest path of likely radionuclide travel through the unsaturated zone could involve considerable uncertainty, and thus requested public comment on questions related to the applicability of the existing 10 CFR Part 60 performance objective for the geologic setting to sites located in unsaturated geologic media. In response to this solicitation of public comment, seven of the fourteen commenters specifically addressed the questions on groundwater travel time calcula-tions. These questions and the views expressed by the seven commenters are reviewed below.

The notice of proposed rulemaking first requested comment on how groundwater travel time in the unsaturated zone could be determined with reasonable assurance. Comments received in response to this question were divided nearly equally into two categories. The first group of commenters argued that presently it would be difficult to calculate groundwater travel time in the unsaturated zone with reasonable assurance because of the lack of generally acceptable methodology and the limited scope of research efforts currently devoted to this question. A second group of commenters, comprised predominantly of representatives of other l

l Federal agencies, endorsed the opinion that groundwater travel time could i

l 5 Enclosure A

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be determined with reasonable assurance. 0ne of these commenters indicated that groundwater trav'el time calculations could be made by measuring the amount of natural tritium in the groundwater samples from a 4

vertical profile in unsaturated geologic formations. Two other commenters stated that groundwater travel time could be derived from groundwater flux using measurements of ambient water content, degree'of saturation, matric potential and hydraulic conductivity to determine moisture-characteristic curves relating these parameters to one another.

These curves can be developed so as to predict constitutive relationships over a wide range of conditions. From these relationships and flux j determinations these commenters argued that groundwater velocities and subsequently groundwater travel times could then be estimated. One of these two commenters further stated that reasonable assurance may be gained in estimating groundwater travel time using results of laboratory testing, state-of-the-art direct determinations in the field or laboratory, and bounding estimates developed by indirect methods, while both commenters indicated that reasonable assurance may also be gained by incorporating uncertainty analyses into predictive models.

The Commission recognizes that prior to the commencement of HLW disposal studies most groundwater investigations in unsaturated geologic media were generally limited in scope to issues related to near-surface, highly porous soils and unconsolidated rock types. Efforts to predict i

j groundwater movement through potentially suitable geologic repository I

sites within the unsaturated zone often entail the application of hydrogeologic theories, models and methodologies governing near-surface, porous media to much deeper hydrogeologic environments and different rock properties than they originally were designed for. The Commission 6 Enclosure A

[7590-01]

realizes that given the current state of groundwater investigations there may be difficulties associated with groundwater travel time calculations in both the saturated and unsaturated zones, as one commenter observed.

However, the Commission concludes that groundwater travel time calculations can be determinea in the unsaturated zone, though not necessarily with great precision, provided that the proper level of site

-characterization analysis is conducted. Following a detailed study of the comments received on this question, the Commission believes it is feasible for DOE to demonstrate compliance with the groundwater travel time provision, using existing field and laboratory experiments. Further, as

several commenters indicated, a substantial effort is currently underway to develop new methodologies and to improve existing techniques for measuring the hydrogeologic parameters and flow properties that will provide the necessary input to groundwater travel time calculations. For example, it was noted that in-situ monitoring techniques, including tracer tests, are undergoing development and may broaden the range of rock types and conditions for which it is feasible to estimate groundwater velocity and,

, hence, groundwater travel time.

l The second part of the first question on which the Commission sought i

comment centered on whether or not the existing groundwater travel time l

) performance objective in $60.113(a)(2) should be limited to groundwater movement within the saturated zone. The general consensus among commenters on this issue was that there is no reason to strictly limit the groundwater travel time performance objective to water movement in the saturated zone. Following a review of the discussions presented in these comments the Commission has determined that the groundwater travel l

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[7590-01]

1 time provision ($60.113(a)(2)) can be ~ applied to a geologic setting located in either the saturated or unsaturated zone. The Commissio i

could discern no obvious advantage for developing a parallel pr ision 4 .

for the unsaturated zone as one commenter suggested. Wit respect to '

l another consenter's concern that if the Commission de ded to retain the 1 -

groundwater travel time provision, travel time alo i any segment of the

! flow path, including the unsaturated zone, shou d be creditable, provided j that reasonable assurance has been demonstrat d. The Commission has concluded further that the definition of th term " groundwater" set forth at $60.2 will allow travel time along su urface flowpaths to be considered regardless of the hydrogeologic regime through which the water is moving.

I As defined in $60.2, " groundwater" ans all water which occurs below the  :

, - land surface. The Commission bel ves that the concerns of.one commenter 4

4 that it would be inappropriate limit groundwater travel time to the f saturatAd zorie because such a action would not accurately indicate the t

l ac+.ual radionuclide transpo time from the original location of the I waste to the accessible e ironment will also be largely accommodated by i

j the definition of the t rm " groundwater" in $60.2. With respect to the j view expressed that t e approach set forth in 960.113(b) may be i-

!. particularly appro late in the case of HLW disposal in the unsaturated l zone, it should noted that in those instances when groundwater travel t

t time calculati s cannot be demonstrated with reasonable assurance, the ,

i i

. Commission y prefer to specify or approve alternative performance i

t objective pursuant to $60.113(b).

l I its second question related to groundwater travel time the Come sion sought public comment on whether greundwater travel time  !

j represented an appropriate measure of performance for a site within the i

I

8 Enclosure A

. . (7590-01]

l time provision (560.113(a)(2)) can be applied to a geologic setting located in either the saturated or unsaturated zone. The Comission could discern no obvious advantage for developing a parallel provision l for the unsaturated zone as one comenter suggested. With respect to another comenter's concern that if the Comission decided to retain the groundwater travel time provision, travel time along any segment of the flow path, including the unsaturated zone, should be creditable, provided that reasonable assurance has been demonstrated, the Comission has concluded further that the definition of the tenn " groundwater" set forth at $60.2 will allow travel time along subsurface flowpaths to be considered regardless of the hydrogeologic regime through which the water is moving.

As defined in $60.2, " groundwater" means all water which occurs below the land surface. The Comission believes that the concerns of one commenter that it would be inappropriate to limit groundwater travel time to the saturated zone because such an action would not accurately indicate the actual radionuclide transport time from the original location of the waste to the accessible environment will also be largely accomodated by the definition of the term " groundwater" in 660.2. With respect to the 1

view expressed that the approach set forth in 660.113(b) may be particularly appropriate in the case of HLW disposal in the unsaturated zone, it should be noted that in those instances when groundwater travel time calculations cannot be demonstrated with reasonable assurance, the Connission may prefer to specify or approve alternative performance objectives pursuant to 960.113(b).

In its second question related to groundwater travel time the Comission sought public coment on whether groundwate travel time represented an appropriate measure of performance for a site within the l

8 Enclosure A

[7590-01]

unsaturated zone, or whether an alternative performance objective for the geologic setting would be more appropriate. The views expressed by the commenters were nearly equally divided on this issue. Some of the commenters asserted that, although not ideal, the groundwater travel time provision may, under certain circumstances, represent an appropriate measure of performance for a geologic setting in the unsaturated zone.

Other commenters argued that groundwater travel time was not an appro-priate performance objective for HLW disposal within the unsaturated zone and suggested several alternative performance objectives, as discussed below.-

With respect to alternative performance requirements, one commenter considered it unacceptable to establish an alternative performance measure for unsaturated geologic media while using a different measure for a saturated salt site. The Commission anticipates that the decision to apply the groundwater travel time provision to all geologic settings regardless of the hydrogeologic zone in which the site is located should alleviate this commenter's concern. Another commenter stated that although groundwater travel time substantially exceeding 1,000 years is a favorable condition, it is not appropriate as a totally definitive performance objective for disposal in either the saturated or unsaturated zone. However, in view of 560,113(b), the groundwater travel time performance objective is not such a " totally definitive" objective. The same commenter considered release criteria as the absolute measure of total performance and further argued that realistic estimates of release criteria for the unsaturated zone might not be possible until observations are actually made in shafts and drifts. In response, the Commission would note that the site characterization program would 9 Enclosure A i

?

[7590-01]

include such observations. One commenter indicated that if NRC chose to retain the groundwater travel time performance objective that this

. provision should only be applied if the travel time calculations include j combined travel times in the unsaturated and saturated zones so as to better approximate radionuclide transport. The Commission considers the concerns of this commenter to be. accommodated by_the definition of the

$ term " groundwater" adopted in the final amendments.

Most commenters who argued against the application of the l

groundwater travel time performance objective to unsaturated geologic media generally suggested alternatives based either on the hydrogeologic

concept of flux or upon the case-by-case approach of $60.113(b).

As derived from U.S. Geological Survey Water Supply Paper-1988 the

} tein groundwater " flux" can be defined as the rate of discharge of ground- .

j water per unit area of porous or fractured geologic media measured at right angles to the direction o'f flow. In comparison, the term " groundwater

travel time" used in 10 CFR Part 60 can be interpreted as the length of i

time required for a unit volume of groundwater to travel between two loca-tions. Alternatives suggested by the commenters which were based upon j the con ~ cept of flux included a maximum groundwater flux requirement and a dual "either/or" criterion which would allow the applicant the option of I demonstrating compliance with either a minimum groundwater travel time i

requirement or a maximum groundwater flux requirement. After considering

! the possibility of an alternative performance objective based upon the

! maximum groundwater flux, the Commission has decided to retain the j groundwater travel time requirement for geologic settings regardless of the hydrogeologic zone in which they are located. This decision was based on the Commission's belief that the groundwater travel time l

l 10 Enclosure A

[7590-01]

requirement represents an independent measure of the overall hydro-geologic system performance which may encompass a variety of hydro-geologic parameters including groundwater flux. However, the Commission expects that groundwater flux will be an important factor in the tech-nical evaluation of radionuclide releases in the unsaturated zone, as-well as in the saturated zone.

The Commission does not consider it necessary to specify a dual "either/or" groundwater criterion suggested by one commenter since under the provisions of $60.113(b), the Comission already has the flexibility to' approve or specify some ott;er. radionuclide release rate, designed containment period, or pre-waste emplacement groundwater travel time on a case-by-case basis. Further, the Commission anticipates that areally integrated or averaged groundwater flow velocity referred to by this same commenter will be addressed in the evaluation of uncertainties surrounding the groundwater travel time calculations.

In addition, to a performance criterion based upon groundwater flux, other alternative performance criteria were discussed by commenters.

00E, in its original comment letter on the proposed amendments expressed general support for a performance criterion based upon groundwater flux, but in an addendum to this letter concluded that it would be impractical to define a performance objective for the geologic setting based on flux through a geologic repository located in the unsaturated zone. Instead, 00E took the position that an alternative performance objective developed upon the concept of a minimum time for groundwater travel to the accessible environment based on four separate physical events would be more appropriate for the unsaturated zone. The four physical events con-tained in the suggested 00E alternative performance objective are:

11 Enclosure A 4

[7590-01]

,c (1) the creation of a drying zone around the emplaced wastes,-(2) the subsequent return of moisture to the rock surrcunding the waste canisters, (3) the travel time through the unsaturated zone and finally, (4) the travel time to the accessible environment by groundwater movement through the saturated zone.

The manner in which these or possibly other events may occur within the geologic repository system will. depend upon the interactions of a number of site- and design-specific parameters such as the thermomechanical and hydrogeologic properties of the host rock, thermal loading of the underground facility and waste package design. However, as noted at 48 FR 28203, the Commission believes that it is important to consider both natural and engineered barriers individually and has structured the' technical criteria of 10 CFR Part 60 in a way that requires that the natural and engineered Darriers each make a definite

~

contribution to the overall system performance objective for the geologic repository. To that end the Commission considers it important to maintain a standard of performance for the geologic setting that is a measure of tne quality of the natural barriers and is independent of any interaction between these natural barriers and the engineered barriers.

The existing pre-waste-emplacement groundwater travel time provision (560.113(a)(2)) is such a performance standard since it is characteristic of the area outside of the disturbed zone created by underground facility construction and waste emplacement operations. This parameter is not dependent upon the effects of waste emplacement and is intended to provide assurance of isolation beyond the first 1000 years. The i

Commission prefers the existing groundwater travel time provision, which l

12 Enclosure A

~ _ _ . _ - _ . _ _ _ _. . __ ~_ . _ _ _ . _ . _ _ _ _ _ _

[7590-01]

t t

l is part of its multiple barrier approach, to the alternative performance  ;

objective suggested by DOE since the latter does not offar a measure of performance for the geologic setting that can be evaluated independently l

of design and engineering factors. Further, the physical parameters I needed to evaluate pre-waste-emplacement conditions of the geologic setting can be accurately measured with direct and indirect field methodology.

The DOE suggestion would necessitate that estimates of long-term 1

performance of the geologic setting under post-waste-emplacement conditions be used in the Commission's deliberations on whether the o

I groundwater travel time performance objective is met. The uncertainties

associated with such estimates can be affected by a number of factors, '

includirig the age and nature of the waste and the design of the i

I underground facility. E'aluations v of the performance of the geologic

setting under post-waste-empla' cement conditions-must also take into account predictions of future changes in the thermomechanical, geochemical and hydrogeologic properties of the geologic setting through 4

time as a result of the creation of a non-isothermal environment due to waste emplacement. The Commission's view is that the present emphasis I

on pre-waste-emplacement conditions will provide a' higher degree of 3

confidence in the'c'ontinued isolation capabilities of the natural barriers of the geologic setting over the long term.

The view was also expressed by other commenters that the development of a new alternative performance objective to existing $60.113 (a)(2) may

, .not be necessary since the Commission's approach set forth at i

560.113(b) might be a more appropriate means of specifying alternatives -

13 Enclosure A i

/.

[7590-01]

to the groundwater travel time criterion. The Commission notes that it is essentially following this approach in its decision to retain the existing provisions of $60.113(a)(2) and $60.113(b).

Following a review of the various alternative performance objectives suggested by the commenters, the Commission considers groundwater travel time to represent a more appropriate parameter upon which the performance of the geologic setting can be evaluated than any of the suggested alter-natives because a prescribed groundwater travel time can be generically applied and will provide a conservative estimate of a minimum radionuclide release time to the accessible environment. It should be noted, however, that the Commission still retains the option of applying the provisions of $60.113(b) instead of $60.113(a)(2) to a particular geologic setting when such an action is deemed appropriate.

(b) Definition of Groundwater.

Three commenters addressed the Commission's proposed definition of the term " groundwater" as meaning "all water below the Earth's surface".

Two of these commenters, citing possible confusion among the public and scientific community stated that the Commission should not define

" groundwater" in this manner, but rather should limit the use of the term to water within the saturated zone. In contrast, one commenter commended NRC on this definition, but noted that it may not be consistent with the definition of the term included in the proposed EPA environmental standards -- 40 CFR 191. In its proposed rule EPA defined " groundwater" as " water below the land surface in a zone of saturation" (47 FR 58205, December 29, 1982). While the Commission recognizes that limiting the use of the term " groundwater" to water within the saturated zone may 14 Enclosure A

[7590-01) currently be a more widely accepted practice, the Commission also notes

] that numerous members of the scientific community routinely use the term

, groundwater in the same context as the Commission proposed.

The Commission has carefully reviewed the arguments presented by the commenters on this issue and has decided to retain the definition of groundwater with one minor change--the phrase " Earth's surface" has been replaced by " land surface". This change was made for the sake of clarity and internal consistency with wording in the definition of the term

" unsaturated zone". The Commission's decision was based on the fact that, at present, no ur.ique definition of the term " groundwater" appears to be universally accepted in the technical community. Therefore, the

Commission has not actually redefined the term " groundwater" as one commenter suggest,ed but rather has adopted one of the commonly used 1

definitions of the term that is most consistent with the Commission's i intent concerning the provisions related to' groundwater throughout the Part 60 regulation. With respect to the differences between the definition of the term " groundwater" adopted by the Commission and that

~

proposed by EPA, the Commission. notes that it does not consider the two definitions to be inconsistent since the scope of the definition adopted in $60.2 will encompass water within the zone of saturation as well as water within the unsaturated zone. As noted above, the Commission considers it necessary to adopt a broader definition of the term

" groundwater" in order to maintain consistency with previous Comaission usage of this term and to effectively apply the provisions of i

10 CFR Part 60 to the regulation of HLW disposal within unsaturated as well as saturated geologic media. Further, since EPA has not yet promulgated its final environmental standards, the Commission cannot 15 Enclosure A

[7590-01] i anticipate whether or how " groundwater" will actually be defined in the final EPA regulation.

(c) Definition of the " unsaturated zone."

The Commission's proposed definition was derived from U.S.

Geological Survey (USGS) Water Supply Paper 1988. Two commenters noted that the phrase " deepest water table" introduced confusion into the definition of the term " unsaturated zone" (660.2). The Commission had inferred that the phrase " deepest water table" as used by the USGS referred to the regional water table and hence adopted this same phraseology in the definition of the term " unsaturated zone" set forth in the proposed amendments to 10 CFR Part 60. However, in light of confusion expressed by commenters whicif may be due partially to the incorrect inference by some that the phrase " deepest water table" referred to local rather than regional water tables, the deff'nition of term " unsaturated zone" has been modified. To clarify the Commission's original intent, the phrase " deepest water table" has been replaced by

" regional water table" in the final amendments. (A conforming change has also been made to the definition of the term " saturated zone").

Additionally, the phrase " water in this zone is under less than atmospheric pressure" has been rewritten as " fluid pressure in this zone is less than atmospheric pressure" for the sake of technical clarity.

The Commission has attempted to maintain internal consistency with the definitions of hydrogeologic terms presented in USGS Water Supply Paper 1988 wherever practicable and for this reason has not adopted any of the alternative definitions of the term " unsaturated zone" suggested by the commenters.

16 Enclosure A

l

[7590-01]

l (d) Favorable Siting Conditions. l

$60.122(b)(2). The term " low hydraulic potential" nas been replaced with " low hydraulic gradient" in S60.122(b)(2)(iii) as suggested by one commenter for the sake of technical accuracy.

560.122(b)(7). In addition to coments received in response to the Commission's specific request for input on its questions related to groundwater travel time calculations in the unsaturated zone, the subject of groundwater travel time was also addressed by two commenters on proposed S60.122(b)(7). The issues raised by these two commenters merit discussion here although they have resulted in no change to the rule.

The provisions of $60.122(b)(7) have the effect of identifying pre waste-emplacement gro'undwater travel time along the fastest path of likely radionuclide travel from the disturbed zone to the accessible environment that substantially exceeds 1,000 years as a favorable siting

~

criteria for both the saturated and unsaturated zones. Previously these provisions (formerly designated as $60.122(b)(2)(iv)) applied only to sites within the saturated zone.

One commenter on proposed S60.122(b)(7) opposed the application of this provision to the unsa~turated zone on the grounds that the determina-tion of groundwater travel time in the unsaturated zone may not be neces-sary nor always be possible. Under such circumstances, this commenter argued, inability to demonstrate that groundwater travel time substantially exceeds 1,000 years should not amount to the absence of a favorable condition. The issue of groundwater travel time in the unsaturated zone has already been discussed in detail in the above section on Groundwater Travel Time Calculations and will not be repeated here. With respect to the second part of this comment the Commission 17 Enclosure A l

[7590-01]

reiterates its position set forth in the Supplementary Information to the final 10~CFR Part 60 technical criteria (48 FR 28201) that a site is not i

disqualified as a result of the absence of a favorable siting condition.

A.second commenter on $60.122(b)(7) expressed the view that for a HLW repository within the unsaturated zone, minimizing leachate flux would appear to be at least as important as maximizing groundwater tre el time. -To that end, this commenter felt that it might be more appropriate to specify as a favorable siting condition a dual "either/or" criterion

such.that groundwater travel time is greater than 1,000 years or groundwater flux through the host rock at a proposed site is less than some average rate. This-rate, it was argued, could be based on nuclide solubility, leach rate criteria, and population exposure criteria. The

commenter stated that whichever criterion was ultim'ately selected it should be based upon an areally integrated or averaged calculation, over  !

an area on the order of the cross-sectional area of the repository normal to the direction of expected flux regardless of hydrogeologic zone to help reduce controversy concerning how the " fastest pathway" can be determined. For a discussion of the concept of applying a dual criterion i

) of either groundwater travel time or groundwater flux see the above sec-tion entitled Groundwater Travel Time Calculations.

' Minor corrections have been made to the provisions of $60.122(b)(8) for the sake of clarity and technical accuracy as a result of the comments received. The phrase "and nearly constant" has been deleted from S60.122(b)(8)(i) and a typographical error in the word " overlying" has been-corrected.

1 18 Enclosure A

[7590-01]

(e) Potentially Adverse Conditions.

j. 560.122(c)(9). This provision of the final technical criteria identified groundwater conditions in the host rock that are not reducing as a potentially adverse condition for the saturated zone. One commenter on the proposed amendments stated.that a parallel provision should be provided for the unsaturated zone. The Commission considers this argu-ment to have merit and has modified the final amendments accordingly.

a

.Rather than create an additional provision, the Commission has deleted a

the qualifying phrase "for disposal in the saturated zone" from existing j $60.122(c)(9) to ensure that this provision will be applicable equally to groundwater conditions in the saturated and unsaturated zones.

$60.122(c)(23). Minor editorial changes have been made as suggested by one commenter, for the sake of clarity.

$60.122(c)(24). During the development of the proposed amendments (47 FR 5935, February 16,1984) the Commission's staff identified vapor t transport of contaminants as a potential concern associated with HLW disposal in the unsaturated zone. The Commission noted that in unsaturated geologic media, water is transported in both liquid and vapor i

f phases. The relative contribution of transport via both these phases and their direction of movement with respect to a geologic repository was deemed to directly influence the containment of contamiriants. Vapor transport, particularly when a thermal gradient is imposed, may provide a possible mechanism for radionuclide migration from a geologic repository

in unsaturated geologic media. This issue was discussed at length by the I ' Commission in the proposed amendments and in draft NUREG-1046. The s

comments received on the discussion of vapor transport and on the wording of the proposed amendment 560.122(c)(24) indicated'a need'for the 19 Enclosure A i

e ,...c.. ~.- ., ,., ., ,,_,-.,,_.-r --w. . + , _ . ~ . .,.m. ,,w,

[7590-01] l l

l Commission to clarify its intent with respect to vapor transport.

The issue of vapor transport of contaminants is a relatively new issue that has grown out of scientific investigations of the feasibility of HLW disposal in unsaturated geologic media. Since most scientific studies related to HLW disposal within the unsaturated zone have been initiated very recently, many of the associated issues have not as yet been examined in any great detail. The Commission recognized that vapor formation may not necessarily constitute an adverse condition for a particular geologic repository site, but, given the fact that vapor transport could provide a mechanism for.radionuclide transport within the unsaturated zone, it wanted the opportunity to evaluate whether or not

- vapor transport could adversely affect a geologic repository system. To that end the Commission identified the potential for vapor traniport of radionuclides from an underground facility located in the unsaturated zone to the accessible environment as a potentially adverse condition in the proposed amendments (560.122(c)(24)). The Commission has not reached 1

any conclusions on vapor transport, as one commenter incorrectly inferred, but rather is currently sponsoring research on vapor transport in unsaturated fractured rock in an effort to better understand this subject.

Some confusion was expressed by the commenters with respect to the Commission's use of the term " vapor transport". In particular, one commenter stated that 560.122(c)(24), as written, was ambiguous and meaningless. The term " vapor transport" as used in the proposed amend-ments referred to both water vapor and the gaseous state of some constit-uent contaminants. A second commenter on this issue suggested that tb Commission add quantitative clarifications to this provision since the 20 Enclosure A

[7590-01]

proposed wording allowed no potential vapor transport of radionuclides by molecular diffusion (i.e., transport at a microscopic level due to concentration gradients) or convective transport (i.e., transport due to temperature or density gradients). The same commenter noted that while the flux values associated with these two transport processes might be miniscule, they would not be zero at any u'nsaturated site. The Commission does not consider it appropriate to add quantitative clarifications to S60.122(c)(24) because the movement of radionuclides in the gaseous state is, to a large extent, dependent on site- and design-specific parameters. The Commission considers the movement of radionuclides in the gaseous state may be a potentially important site-and design-related process and will retain the opportunity to evaluate whether or not'such a process will adversely affect the geologic repository system. However, to alleviate the confusion surrounding proposed $60.122(c)(24), the wording of this provision has been extensively modified in the. final amendments. Reference to " vapor transport" has been deleted, and this provision now solely addresses the f potential for the movement of radionuclides in a gaseous state through air-filled pare spaces of an unsaturated geologic medium to the accessible environment as a potentially adverse condition. The Commission believes the revised wording will more accurately convey its original intent and should remove any ambiguity associated with the i

~

previous wording, such as one commenter's query of where the vapor transport is occurring and when it is important.

The Commission agrees with the commenter who indicated that vapor transport may also occur in geologic repositories sited in the saturated I i

zone until resaturation occurs. A temporary, localized, unsaturated i

l 21 Enclosure A

, [7590-01]

region could form around an underground facility within the saturated zone as a result of activities related to construction and operation of a geologic repository (e.g. dewatering of shafts and drifts). To date, the issue of vapor transport has not been raised for a geologic repository within the saturated zone primarily because such a phenomenon would be expected to be encompassed within a much larger saturated region, that is, vapor transport might only be expected to occur in that portion of the host rock where the voids are not completely filled or refilled with groundwater. Further, it is anticipated that the time required for waste package integrity (300-1,000 yrs) will generally exceed the post-closure time required for resaturation of a geologic repository within the saturated zone (assumed by the NRC staff to occur within a few hundred years following permanent closure). Therefore, the Commission does not

• consider it necessary at this time to identify vapor transport as a potentially adverse condition for HLW disposal within the saturated zone. .

4 However,'if future research in the area of vapor transport challenges these current assumptions, the Commission may decide to broaden the provisions of $60.122(c)(24) to include both the saturated and unsaturated zones.

(f)- Desian Criteria.

. Changes were made to provisions of the final technical criteria-related to design criteria. The provisions of $60.133(f) have been modified to more closely identify the concept of a potential. for creating a preferential pathway for groundwater to contact the waste packages.

This change was prompted by a commenter's observation that as originally l worded, this provision might not be internally consistent with'new l

22. Enclosure A i

[7590-01]~

S60.122(b)(8)(iv) which identifies a host rock that provides for free drainage as a favorable hydrogeologic condition in the unsaturated zone.

Similar word changes have been made to the provisions of S60.134(b) for consistency with S60.122(b)(8)(iv). Additionally, the phrase

" radioactive waste migration" has been changed to "radionuclide migration" in both S60.133(f) and S60.134(b) for the sake of' technical accuracy. The changes should ensure that these provisions will be equally applicable to geologic repositories within either the saturated or unsaturated zone, and will more accurately convey the Commission's original intent.

ENVIRONMENTAL IMPACT Pursuant to Section 121(c) of the Nuclear Waste Policy Act of 1982, the promulgation of these criteria does not require the preparation of an environmental impact statement under Section 102(2)(C) of the National Environmental Policy Act of 1969 or any environmental review under subparagraph (E) or (F) of Section 102(2) of such Act.

PAPERWORK REDUCTION ACT STATEMENT The final rule contains no new or amended recordkeeping, reporting

~

or application requirement, or any other type of information collection requirement subject to the Paperwork Reduction Act (Pub. L.96-511).

23 Enclosure A

[7590-01]

REGULATORY FLEXIBILITY CERTIFICATION In accordance with the Regulatory Flexibility Act of 1980 (5 U.S.C.

605(b)), the Commission certifies that this rule will not have a signifi-cant economic impact on a substantial number of small entities. The only entity subject to regulation under this rule is the U.S. Department of Energy, which is not a small entity as defined in the Regulatory Flexibility Act.

LIST OF SUBJECTS IN 10 CFR PART 60 High-level waste, Nuclear power plants and reactors, Nuclear mate-rials, Penalty, Reporting and recordkeeping requirements, Waste treatment and disposal.

ISSUANCE For the reasons set out in the preamble and under the authority of the Atomic Energy Act of 1954, as amended, the Energy Reorganization Act of 1974, as amended, the Nuclear Waste Policy Act of 1982, and 5 U.S.C.

553, the Nuclear Regulatory Commis'sion is adopting the following amend-ments to 10 CFR Part 60.

, ~24 Enclosure A

[7590-01]

PART 60 - DISPOSAL OF HIGH-LEVEL RADI0 ACTIVE WASTES IN GEOLOGIC REPOSITORIES

1. The authority citation for Part 60 continues to read as follows:

Authority: Secs. 51, 53, 62, 63, 65, 81, 161, 182, 183, 68 Stat. 929, 930, 932, 933, 935, 948, 953, 954, as amended (42 U.S.C. 2071, 2073, 2092,2093,2095,2111,2201,2232,2233); secs. 202, 206, 88 Stat.

1244, 1246, (42 U.S.C. 5842, 5846); secs. 10 and 14. Pub. L.95-601, 92 Stat. 2951-(42 U.S.C. 2021a and 5851); sec. 102, Pub. L.91-190, 83 Stat. 853 (42 U.S.C. 4332); sec. 121, Pub. L.97-425, 96 Stat. 2228 (42 U.S.C. 10141).

For the purposes of sec. 223, 68 Stat. 958, as amended (42 U.S.C.

2273), SS 60.71 to 60.75 are issued under sec. 161o, 68 Stat. 950, as amended (42 U.S.C. 2201(o)).

2. Section 60.2 is amended by adding two new definitions in proper alphabetical sequence and revising an existing definition:

S 60.2 Definitions.

" Groundwater" means all water which occurs below the land surface.

A A A A A

" Saturated zone" means that part of the earth's crust beneath the regional water table in which all voids, large and small, are ideally filled with water under pressure greater than atmospheric.

• a a a a 25 Enclosure A

[7590-01]

" Unsaturated zone" means the zone between the land surface and the regional water table. Generally, fluid pressure in this zone is less than atmospheric pressure, and some of the voids may contain air or other gases at atmospheric pressure. Beneath flooded areas or in perched water bodies the fluid pressure locally.may be greater than atmospheric.

~

3. Section 60.122 is amended by revising paragraphs (b)(2)(iii) and (c)(9), redesignating paragraph (b)(2)(iv) as (b)(7), and adding new paragraphs (b)(8), (c)(22), (23) and (24) to read as follows:

S 60.122 Siting criteria.

(b)

(2) ***

(iii) Low vertical permeability and low hydraulic gradient between the host rock and the surrounding hydrogeologic units.

(7) Pre-waste emplacement groundwater travel time along the fastest path of likely radionuclide travel from the disturbed zone to the acces-sible environment that substantially exceeds 1,000 years.

(8) For disposal in the unsaturated zone, hydrogeologic conditions that provide--

(i) Low moisture flux in the host rock and in the overlying and underlying hydrogeologic units; (ii) A water table sufficiently.below the underground facility such that fully saturated voids contiguous with the water table do not encounter the underground facility; 26 Enclosure A 1

[7590-01]

(iii) A laterally extensive low permeability hydrogeologic unit above the host rock that would inhibit the downward movement of water or divert downward moving water to a location beyond the limits of the underground facility; (iv) A host rock that provides for free drainage; or (v) A climatic regime in which the average annual historic precipi-tation is a small percentage of the average annual potential evapotranspiration.

(c)

(9) Groundwater conditions in the host rock that are not reducing.

(22) Potential for the water table to rise sufficiently so as to cause saturation of an underground facility located in the unsaturated zone.

(23) Potential for existing or future perched wat'er bodies that may saturate portions of the underground facility or provide a faster flow path from an underground facility located in the unsaturated zone to the accessible environment.

(24) Potential for the movement of radionuclides in a gaseous state through air-filled pore spaces of an unsaturated geologic medium to the accessible environment.

4. Section 60.133 is amended by revising paragraph (f) to read as follows:

S 60.133 Additional design criteria for the underground facility.

27 Enclosure A

[7590-01]

(f) Rock excavation. The design of the underground facility shall incorporate excavation methods that will limit the potential for creating a preferential pathway for groundwater to contact the waste packages or radionuclide migration to the accessible environment.

5. Section 60.134 is amended by revising paragraph (b)(1) to read as follows:

S 60.134 Design of seals for shafts and boreholes.

• a * * *

- (b)

(1) The potential-for creating a preferential pathway for ground-water to contact the waste packages or (2) for radionuclide migration through existing pathways.

Dated at Washington, DC, this day of , 1985.

For the Nuclear Regulatory Commission.

Samuel J. Chilk, Secretary of the Commission.

't i

1 l

1

! ~28 Enclosure A

O ENCLOSURE C 2

o 8

1 4  : .  :

5934 Proposed Rules _

r* => = + w Vol. e9. No. 33 Thursday. February to.19s4 TNs secnon of the FEDERA1. REGISTER suppi.pasNTaRY INFORM AtoN' contasne notices to me putilic of the Background the site and the geologic repository D'800"o 'esuance at ndes and design are carefully selected, and are regusaiens ne pumose of mese nonces On February 23,1961 the Nuclear is capable of meeting the performance f persons an Regulatory Commission (NRC) p, pubbshed a rule that established objectives of 10 CFR part 60. In reachmg i eng pnor e me sococon of me Ang procedures forlicensing the disposal of this determination. the Commission has mies. exammed the argu'ments presented by HLW in geologic repositones 46 FR the public commenters as well as the

)

13971). NRC published propos(ed analysis of the principalissues technical enteria to be used in the associated with unsaturated zone NUC1. EAR REGULATORY evaluation oflicense applications under disposal desenbed in the NRC staff COMMISSION those procedures on July 8.1981 (46 FR technical support document (draft 35280). In response to solicitation for NREG-1046) prepared in conjunction public commenta on the proposed with the proposed amendments. nis M CFR M M technical entens NRC received 93 document identifies the positive aspects comment letters. The Commission. and possible concerns associated with Disposal of High-level Radioactive considered all public comments in disposalin the unsaturated zone and developing the final technical criteria explains why the Commission has Wastes in ttle Unsaturated Zone which were published on June 21.1983 developed the following pmposed Acancv: Nuclear Regulatory (48 FR 28194).

Commission. Several commenters on the proposed amendments.Otherissues which were discussed by public commenters but Acnow:Preposed rule. rule. including the U.S. Department of which did not result in proposed Energy (DOE). the U.S. Department of changes to the final rule are also the Interior. and se suisesARY:The Nuclear Re'gulatory Geological Survey (parately USGS). the U.S.addressed in the technical support took issue Commission (NRC)is considering with a statement made by the document. Upon publication. a copy of cmending its rules on the disposal f draft NUREG-1046 entitled Disposal of Commission at 46 FR 35281 which High. Level Radioactive Wastes in the high-level radioactive wastes (HLW) in explained that the proposed technical geologic repositories so that the Unsatursted Zone: Technical entens were developed specifically for Considerations" will be placed in the technical enteria for geologic disposalin disposalin saturated geologic media the saturated zone may be equally because DOE plans at that time called Public Document Room.1717 H Street NW Washington. DC 20555. Since this cpplicable to disposal within the for HLW disposal at aufficient depth to document is available to the general unsaturated zone. The amendments are be situated in the hydrogeologic region public.* only a summary discussion of being proposed in response to pubhc termed the saturated zone. The these issues is presented below.

comments on the proposed technical commenters considered disposalin the entena forgeologic disposalin the unsaturated zone i to be a viable Issues Examined by the Commission attemative, and noted that since the saturated zone. Final technical entena The depth to the regional water table adopted by the Commission for disposal technical critena were generally applicable without regard to the vanes throughout the Umted States.

cf HLW in the saturated zone were Potential geologic repository sites within published in the Federal Register on possibility of saturation, their scope and junc 21.1983. applicability should not be unduly unsaturated geologic media may be restricted. DOE. in its comments on this identified in arid to semi. arid geographic ratss: Comment period expires April issue, suggested that since opportunities regions of the country because such 16.1984. Comments received after this may arise for exploratory studies in regions generally are charactenzed by a dite will be considered if it is practical unsaturated geologic media, the deep regional water table and hence. a to do so. but assurance of consideration relatively thick unsaturated zone The Commission should reexamine the rule cannot be given except as to comments and make whatever changes are unsaturated zone in certain and regions received on or before this date. necessary to ensure that the rule will of the United S:ates has been apply to all geologic media. The U.S. documented as extending to depths of moonasses: Send comments or suggestiens to the Secretarf of the Department of the Intenor urged that the approximately 600 meters belew the ground surface. In contrast, the Ccmmission. U.S. Nuclear Regulatory rule be modified because. under Commission. Washington. DC 20535. appropriate conditions. the unsaturated unsaturated zone in humid resions is zone could provide one more natural often only a few meters thick. or en:frely Attention: Docketing and Servic.e non eust'ent.

Branch. Copies of comments received barrier to the movement of radionuclides from the geologic Perhaps the most positive aspect m:y be examined at the NRC Public repository to the water table. associated with disposal of HL% within Document Room.1717 H Street NW the unsaturated zone is that the HLW Washington. DC 20555. The Commission has determined that disposal of HLW within the unsaturated would be emplaced in a relatively dry Pon an mromm comen zone is a realistic alternative to disposal (i.e low moisture content) geo; ope Dr. Colleen Ostrowski. Office of Nuclear within the saturated zone, provided that Regulatory Research. U.S. Nuclear . %g, ,,g m.m % g o Regula tory Commission. Washington. , The definition or rh. i rm un eur i.d son. t. Nb on V

DC. 20555. telephone (301) 427-4343. 4 m.4 gro,e u.s. c,o6., cal s.rverwerer supply cESE:oS$NNeNme.1 information end oocwnent contrat t; s Nuc.,er P.per isse tw ainston. oc. terzt.

a.sul.iery conuni t w..ninsioi. o c. zesss.

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" _- Elc_losure L - -

Federal Regist:r / Vcl. 49. No. 33 / Thursday. February 16. 1984 / Propssed Rules 5033 medium.The Commission considers the with vapor transport in the unsaturated geologic repository within the relatively low moisture content of zone may also be discerned since water unsaturated zone, sealing shafts and unsaturated sediment and rock as a vapor formed-near the geologic positive aspect of HLW disposalin the boreholes tightly to inhibit water repository may flow through air. filled mas ement may be undesirable. The unsaturated zone because the lack of available moisture could reduce openings and partially drained fractures. reasoning behind this view is that resulting in a drying of the surrounding . although shafts and boreholes need to leaching of the waste packages and host rock. This drying zone may extend be carefully sealed in the saturated zone thus. significantly reduce the likelihood hundreds of meters from the geologic so that they do not become future of radionuclide transport by repository, and thus may inhibit the conduits for radionuclide migration. they groundwater 8 migration. Further. It is generally recognized that vertical movement of soluble contaminants. may have an entirely different relation groundwater flux in the unsaturated Therefore. the Commission views vapor transport as another issue which must to an unsaturated zone repository.

zone is very small. A credible pathway be evaluated on a case.by. case basis to Shafts and boreholes would increase the for the migration of water soluble amount of water moving through a determine its effects (whether favorable geologic repository located within the contaminants from a geologic repository or potentially adverse) on a particular located in the unsaturated zone to the site. unsaturated zone only if they diverted a signincant amount of runoff to the Q '"

y "",eMo d probably Other Comments Considered by NRC subsurface.

underlying regional water table. and The Commission has reviewed both subsequently through the saturated ne Commission has reviewed the following six issues related to H!.W the arguments ~of the USGS and the groundwater units to the regional disposal within the unsaturated zone provisions of the Anal rule relating to dischabe points. which were addressed in the u the design of seals for shafts and The mmission has reviewed several comments on tha proposed as rufe,blic well boreholes [I 60.134). The provisions of cther issues that are of general concern i 60.134 appear to be generally as in a recent USGS publication.* and to disposal of Hl.W in geologic applicable to seals of shafts and repositories.regardless of the has determined that the final rule (48 FR 28194) accommodates these concems. boreholes in both hydrogeologic zor.es.

hydrogeologie zone involved. Such Therefore, the Commission does not issues include the effects of climatic More detailed discussion of these issues is presented in draft NUREG-1046. consider it necessary to modify I 60.134 changes on the regionalhydrologic at this time.

systems. the potential for human Minimum 300. Meters Depth for Waste intrusion into the geologic repository. Emplacement . BacxAll Raquirements cnd the effects of geologic processes

! [c.g tectonism) on the structural One commenter on the proposed to Anotherissue which has been stability of the geclogic repository. De CFR Part so technical criteria who identified both in public comments on Commission does not believe that any of advocated applying the rule equally to the proposed technical criteria and in these issues would negate the generic the saturated and unsaturated zones USGS Circular 903 pertains to the concept of HI.W disposal within the considered it necessary to change the necessity of backfillin a g3ologic siting criterion which sets a minimum repositorylocated within the unsaturated zone. However. since the depta of 300 meters for waste relative importance of these issues will unsaturated zone. The USGS expressed emplacement. However, the commenter the view that the role of backfill in the depend upon natural conditions existing et a particular sqe. each must be incorrectly identified this provision (see unsaturated zone would be the oppesite evaluated on a site-by. site basts. i 60.122(b)) as a requirement. rather of that in the saturated zone. BackSil Vapor transport of contaminants.hss than as a favorable condition. The material that would inhibit the flow of been identified by the Commission's Commission notes that favorable water to. and radionuclide migration staff as a potential concern associated conditions are those which may enhance from, the waste packages may be highly with Hl.W disposal in the unsaturated waste isolation potential. Hence, a desirable in the saturated zone. In the zone. In unsaturated geologic media. minimum depth of 300 meters for waste unsaturated zone, however, the water is transported in both liquid and emplacement is considered a favorable designers of a geologic repository may vepor phases. The relative contnbution condition because the deeper the Hl.W wish to promote drainage. The opinion cf transport via Ifquid and vapor phases, is emplaced, the less likely it is to be has been expressed that within the and their direction of movement with disturbed. Viewed in that light this unsaturated zone backfill should allow respect to a geolcgic repository will depth is a favorable condition. groundwater to drain readt'y. rather h:ve a direct influence on the irrespective of hydrogeologie zone. than serve as a barrier to drainage. !t

. containment of contaminants. Vapor Since the unsaturated zone may extend was suggested in USGS Circular 903 that transport. particularly when a thermal to depths of up to 600 meters, the if backfillis necessary to perserve gradient is imposed may provide a Commission considers this favorable structural or waste package integrity, a po,ssible mechanism for radionuclide condition to be a realistic one for both relatively permeable material (e.g migration from a geologic repository. the saturated and unsaturated zones. cobble. sized rock) could be used to However. positive aspects associated Therefore. this provision of the rule has permit continued drainage.

not been modified-The final rule published by the

• The comunw e recognian that the tens Requirements for Sealing Shafts and Commission on June 21,1983 contained

, dween a sener ny applied by me technical comunwuty to w wr which esene tenuih me Boreboles only the general functional statement weiw t.bie tie pareene wetw1 whde me twm In USGS Circular 903 the view was that the engineered barrier system redose wein in more aceweiely apphed to *e (including backfill) be designed to assist sad weier, yevaauonel wetw end cordiny wete, expressed that with respect to a -

which occur in the unnaturced some tame of the geologic setting in meeting the awenen. ,edow senek However. for se uke of

• Rosebeem. F. H. fr.1ses. Disposal of Hish-tavel performance objectives for the period sun,hcity. yewidwein te denned in the proposed Nucker Wate Above the Wetw Toble in And following permanent closure sawndmente es all =eter which occure below the Repone. U.S. Geoloccal Servey Carcular sos.

sers eooge Wahinyon, oc, p. zz. ($ 60:133(h) 48 FR 28227). This provision. as promulgated, should be

5936 i

Feder:1 Registcr / Vol. 49. No. 33 / Thursday. February 16, 1984 / Proposed Rules

, responsive to the concems discussed ~

j above. drier conditions and increasing worker unsaturated zone is generally I

safety by prodding altemative sources Waste Package Design Criteria of ventilation and escape routes. discontinuous and strongly dependent 4

' upon initial conditions (e.g magnitude As defined at i 80.2. the term " waste The number of ventilation shafts and spatial and temporal distributten package

• means "the waste form and included m any geologic tepository will recharge events) and the conductive

be decided by the designer-DOE. No any containers, shielding. packing and properties of the partially saturated j other absorbent materials immediately provtsien of to CFR part to expressly geologic media which vary with

surrounding an individual waste limits the number of ventilation shafts 4

that a geologie repository may contain. moisture content. Reliable calculations container" (48 FR 28219). The point has and predictions of groundwater trave!

Whatis important is that the surface been raised that because of the different facility ventilation systems comply with times and vel 2 cities require knowledge nature of the emplacement environment of these conditions and properties.

designs of waste package components the design enters in i m132(b)(48 FR 23226) and that the underground facility Within the unsaturated zone the i for the saturated and unsaturated zones ventilation system be designed in movement of a given volume of water may be quite different. The Commission over a given distance depends sery recognizes that several charactenstics of accordance with i 60.133(g)(48 FR strongly upon the nature of the recharge the emplacement environment (e.g. 2823).The Commission considers the events. Additionally, the material oxidation conditions, lithostatic design requstements for the ventilation systems set forth in il 60.132 and 60.133 properties (e.g. moisture charactenstic pressure, geochemistry, contact with curves, porosity. irreducible saturation.

to be applicable to both the saturated groundwater. etc.) may very etc.) and the irutial conditions significantly between the two and unsaturated zones. As long as the saturation, capillary pressure, m(e.g.,

ventilation system complies with atric hydrogeologie zones.This variation of potential) may be extremely difficult to prodstons of Il e0.n1(a), e0.132. and emplacement endronment may measure on a representative scale for 60.133 and does not compromise the necessitate that DOE consider unsaturated porous and fractured alternative designs for waste packages integrity of the site to host a geologic geologic media.

(including waste form. canisters. repository. DOE will have broad .

flexibility in designing the system. For these reasons. calculations of pre-overpack etc.) for geologic disposal m, i.asie. emplacement groundwater travel the unsaturated zone. The Commission Explorato'YBoreholes time along the fastest path oflikely has reviewed the performance Provisions relating to site radionuclide travel through the objectives which pertain to the waste characterization are set forth in the final unsaturated zone may have large 3

ekage (i e0.nl and i 80.n3), and associated uncertainities, and may be of rule at i 80.10 (48 FR 28219). Section lieves that the provisions, as currently 60.10(d)(2) requires that the number of quesnonable value in estimating the wntten are equally applicable to weste exploratory boreholes and shafts be capability of the geologic setting to packages emplaced within either the limited to the extent practical. isolate Hl.W from the accessible saturated or unsaturated zone. Similarly, consistent with obtaining the enWmnment.

the specific design criteria for the waste D' "' d' "

package and its components (l 80.135. information needed for site characterization. The view was gro d ce m ission is

( 4a FR 2a23) have been determined to be expressed in USGS Circular 903 that in proposing would have the effect o{

generally applicable to both zones.

! the unsaturated zone,if the host rock expanding the scope of the perfonnance

' Therefore, no changes have been made to the provisions of il 80.111. 80.113. or already has a high vertical permeability. objectives set forth in i 60.113 to 80.135. there is no reason to limit the number of disposal m either the saturated or dnll holes. nus, the USGS noted that if unsaturated zone. Similarly, the Ventilation necessary, a proposed geologic proposed amendment to the Siting The issue of restneting the number of repository could be explored like an ore Critena (I so.122(b)(7)) would have the body or coal bed. with dnll holes every effect of making pre waste-emplacement ventilation shafts associated with a geologic repository was addressed in few hundred feet on a rectangular gnd. groundwater travel time along the The Comnussion's view on the fastest path oflikely radionuclide travel USGS Circular 903. In the case of the saturated zone. the number of importance of not compromising the from the disturbed zone to the ventilation shafts may be kept at a integrity of a site during the site accessible environment which characterization program of testing and substantially exceeds 1.000 years a minimum since the stafts could constitute potential pathways to the exploration has been clearly stated at 44 favorable condition for Hl.W disposal

! FR 7040s. However,if DOE should opt within either the saturated or eccessible envimament. In USGS for a site exploration and 1

Circular 903 it is stated that in the case unsaturated zone.

characterization program which The Commission's current thinking on

~ cf the unsaturated zone additional includes plans for dnlling numerous shafts for ventilation would not this issue is that if DOE can demonstrate compromise the geologic repository's boreholes then DOE would have the with reasonable assurance that travel i burden of showmg the Commission that time for groundwater movement through performance because sealing shafts in th1e ability of the site to isolate Hl.W has the unsaturated zone can be quanti!ie the unsaturated zone is much simpler and ofless consequence thanin the not been compromised during these then DOE should be allowed e to inc activities. such travel time when demonstrating saturated zona. Several potential

' benefits were cited by the USGS to Groundwater Travel Time in the compliance with I 60.113(a)(21 support this view-e.g., reducing the Unsaturated Zone However, such calculations of problem of thermalload in the early groundwater travel times through the The concept of groundwater travel  ;

phases of the geologic repository, unsaturated zone could involve time generally is applied in evaluations removal of any water vapor during the considerable uncertainty. Further. long operationalperiod drawinglarge of saturated flow systems, where flow is groundwater travel time possibly may continuous and temporal fluctuations in be inconsistent with the proposed cmounts of desert air through the geologic repository to promote even the potential of the systems are small. In amendment which identifies a host rock contrast, water movement in the that provides for free drainage as a 1

l l  !

Fed:ral Register / Vcl. 49. No. 33 / Thursday. February 16. 1984 / Propos2d Rules 5937 favorable hydrogeologic condition for IJst of Subjectsla le CFR Part to disposal of HLW within the unsaturated and low hydraulic potentf al between the zone. It may be more appropnate for the High. level weste. Nuclear power host rock and the surrounding maission to specify another plants and reactors. Nuclear materials, hydrogeologic units.

remeter a which performance may Penalty. Reporting and recordkeeping evaluat for a geologic settingin the requirements. Waste treatment and (7) Pre-waste-emplacement disposal. groundwater trave time along the fastest unsaturated zone. or to utilize the epproach set forth in I 80.113(b) which Issuance path oflikely radionuclide travel from provides the Cosuaission with the the disturbed zone to the accessible Sexibility to spectfy variations in For the reasons set out in the environment that substantially exceeds performance objectives on a case-by. pmamble ud unde h auhy h 1.000 yeus.

case basis, as long as the overall system Atomic Energy Act of 1954, as amended. (8) For disposalin the unsaturated performance objective is satisifed. the Energy Reorganization Act of 1974. zone. hydrogeologic conditions that

'Ihrefore, to solicit input in these as amended. the Nuclear Waste Policy Provide-matters the Commission is particularly Act i1982. and S U.S.C. 553. the (i) Low and nearly constant moisture seeking pub!!c comment on the following Nuclear Regulatory Commission is flux in the host rock and in the quesdons. Proposing the following amendments to overlaying and underlying

1. How can groundwater travel time in 2 *" 8 bydrogeologic units:

the unsaturated zone be determmed (ii) A water table sufficiently below with reasonable assurance? Should the PART 00-DISPOSAL OF HIGH-LEVEL groundwater travel time performance the underground facility such that fully RAOlOACTIVE WASTES IN GEOLOGIC objective be limited to groundwater REPOSITORIES saturated voids continuous with the water table do not encour.ter the movement within the saturated zone? Ausherity: Seca. s1. 53. et, e3. es. s1.1e1. underground facility:

2. Does groundwater travel time tas. ta3. as stat. see, sao. s32. s33. ess. see.

represent an appropriate measure of (iii) A laterally extensive low-saa ese. as amended (42 USC 2 ort. 2073. permeability hydrogeologic unit abos e performance for a site within the aos2. 20ss. 20ss. 2111. 220s. 2232. 2233p secs.

unsaturated zone. or would an anz. 2ns. as stat.1244.124a. (42 USC sa42, the host rec'k that would inhibit the clt ti E#rfo# ""#' b'estive I fo# sseet secs. to and 14. Pub. L shot. 92 Stat. downward movement of water or divert the geologic setting. (e.g maximum 2ss1 (42 USC Jo21a and Sasth sec.102. Pub. downward moving water to a location likely volumetric flow rate of L v1-1s0. as stat. ass (42 USC 4332h sec, beyond the limits of the underEround groundwater through the geologic 121. Pub. L 37-42s. se Stat. 2228 (42 USC facility; 1o141 repository) be more appropriate? For the purposes of sec. 223. es Stat. osa, as (iv) A host rock that provides for fr,ee amended (42 USC 2273). Il 80.71 to so.7s d#'5"*8"

EnvironmentalImpact: Negative are issued under sec. teto. es stat. eso, es (v) A c!Imatic regime in which the Declarados amended (42 USC 2201(o)). average annual historic precipitation is Pursuant to Section 121(c) of the Nuclear Waste Po!!cy Act of1982. the

1. Section 80.2 is amended by adding two new def!nitions in , , '[*8',ve tran p rat $on.

promulgation of these cCteria shall not alphabetical sequence: proper require the preparation of an I*I , , ,

i 60.2 Dennmons.

i environmental impact statement under 1

. . . . . [22) Potential for the water table to Section 102(2)(C) of the National rise sufficiently so as to cause saturation Environmental Policy Act of 1989 or any Gr undwater** means all water of an underground facility located in the environmental review under which occurs below the Eanh a surface. unsaturated zone.

subparagraph (E) or (F) of Section 102(2) " Unsaturated zone" means the zone

<f such Act. between the land surface and the (23) Potential for existing or future deepest water table. Generally, water in perched water bodies that may have the

P;perwork Reduction Review this zone is under less than atmospheric effect of saturating portions of the pressure. and some of the voids may unde'8'"und facility or providing a

( De proposed rule contains no new or contain air or other gases at faster flow path for radionuclide .

. cmended recordkeeping, reporting or atmospheric pressure. Beneath flooded movement from an underground faci!ity epplication requirements, or any other areas or in perched water bodies the located in the unsaturated zone to the type ofinformation collection accessible environment, water pressure locally may be greater requirements subject to the Paperwork than atmospheric.

(24) Potential for vapor transport of Reduction Act (Pub. L 96-511). . . . . .

radionuclides from the underground Regulatory Flexibility Act Certification 2. Section 80.122 is amended b facility located in the unsaturated zone rev sing paragraph (b)(2)(iii). des gnating to the accessible environment.

In accordance with the Regulatory paragraph (b)(2)(iv) as (b)(7), and adding Flixibility Act of1980 (5 U.S.C. 605(b)). Dated at washington. D.C. this 13th day of new paragraphs (b)(8). (c) (22). (231 and February 1984.

th2 Commission certifies that this rule if (24) to read as follows:

ad:pted. will not have a significant' For the Eclear Regulator) Comm4ssion.

economic impact on a substantial mmm SMM I number of small entities. De only entity Secretary of the Commission.

subject to regulation under this rule is (b) * *

• tra ow. ee-ems ru -me= ses .=i th2 U 9. Department of Energy. (2) * * " (iii) Low vertical permeability owns caos tsee si-=

_ _ _ . _ _ - , - - - - - < ~ " " - ' ' * ~ ~ ~ ' ^ ~ ' ' ' ~ " ' ' ~ ' " " ~ " ' ' '

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e an ENCLOSURE D l

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TABLE OF CONTENTS Topic Comment Nos. Page General Comments....................................... 1-5 2-4 Groundwater Travel Time Calculations................... 6-14 4-16 Definition of Groundwater.............................. 15-17 16-17 Definition of Unsaturated Zone......................... 18-19 18-19 60.122(b)(7)........................................... 20-21 19-24 60.122(b)(8)........................................... 22-29 24-29 60.122(c)(23).......................................... 30-31' 29-30 60.122(c)(24).......................................... 32-34 30-33 Additional Amendments Suggested by Commenters.......... 35-45 33-39 Comments on draft NUREG-1046........................... 46-47 39-41 3

l 3

h e nam STAFF ANALYSIS OF PUBLIC Co mENTS ON

' THE PROPOSED AMENDMENTS TO 10 CFR PART 60 RELATED TO THE UNSATURATED ZONE AND .

DRAFT NUREG-1046 Prepared by Waste Management Branch DRPES Office of Nuclear Regulatory Research December, 1984 Enclosure D

l l

COMMENT LETTERS Comment No. Commenter Date Docketed 1 B. 0cver....................................... 3-12-84 2 E. Nemethy, Ecology / Alert...................... 3-19-84 3 R. Williams, Williams & Assoc. ................ 3-22-84.

4 J. Bates, Argonne National Laboratory. . . . . . . . . . 4-12-84 5 J. Kleinhans, Wisconsion Radioactive Review Board................................. 4-13-84 6 B. Vild, State of Rhode Island and Providence Plantations........................ 4-16-84 7 J. Kearney, Edison' Electric Institute........... 4-16-84 8 R. Loux and C. Johnson, Nevada Nuclear Waste Project 0ffice.......................... 4-16-84 9- ,M. Lawrence, U.S. Department of Energy.......... 4-16-84 10 J. Patterson, Middle South Services, Inc. ...... 4-16-84 11 A. Hirsch, U.S. Environmental Protection Agency........................................ 4-20-84 12 0. Moos, Washington Department of Ecology....... 4-20-84 13 B..Blanchard, U.S. Department of the Interior... 4-23-84 14 A. Turcan, Jr. , Capital Area Groundwater Conservation Commission....................... 4-27-84

}

11

INTRODUCTION:

On February 16, 1984 the Nuclear Regulatory Commission (NRC) published proposed amendments to 10 CFR Part 60 to assure that its high-level radioactive wastes (HLW) regulations address considerations relevant to all geologic repositories, whether sited in the saturated or unsaturated zone (49 FR 5934). In addition to its request for comment on the proposed amendments, NRC particularly sought public input on several questions related to groundwater travel time calcula-tions in the unsaturated zone (49 FR 5937). In conjunction with the proposed amendments NRC published draft NUREG-1046, which contained a discussion of the technical issues NRC considered during the development of the proposed amend-ments. NRC received a total of fourteen comment letters in response to its solicitation of public input on both the propsed amendments and draft NUREG-1046.

These comments were considered with respect to revising and improv.ing the text of the final amendments. This document presents the individual comments grouped according to subject and a detailed analysis of the comments by the NRC staff.

Copies of the fourteen comment letters.are included as Appendix A. A copy of the Federal Register notice containing the proposed amendments is included as Appendix B.

1 Enclosure 0 A

GENERAL COMMENT

S:

I Comment No.1: B. Dover (1)-

It is extremely important to be aware of the fact that " unsaturated" is NOT synonymous with a low moisture content. The last paragraph beginning on

p. 5934 of the Federal Register notice referred to states that "Perhaps the most positive aspect associated with disposal of HLW within the unsaturated zone is that the HLW would be emplaced in a relatively dry (i.e., low moisture content) geologic medium." This. implies that all unsaturated rocks are dry.

This is patently untrue. Unsaturated merely means that the pore space in the rock is not filled with water. The actual water content depends on the amount of pore space. Thus a rock that has a porosity of 5% and which is saturated has exactly the same amount of contained water as a rock with a porosity of 10%

which is 50% saturated. In fact, many of the rocks to which the USGS refers to as unsaturated have a very high porosity and a relatively high saturation, although less than 100%, and in fact contain much more water than saturated rocks with a lower porosity. Many volcanic tuffs ~in the Great Basin, in fact, contain considerably more water than granites in the more humid regions, even though the granites are saturated and the tuffs are not. Water content and the speed.of the movement.are the important factors; the percentage of " saturation" is really an insignificant factor.

S_taff Response to Comment No. 1:,

The staff generally agre'se with the technical discussion of unsaturated geologic media presented by this commenter. However, the consenter has l incorrectly. inferred that NRC considers all unsaturated rocks to be dry. NRC I used the term "relatively dry" to contrast conditions in saturated rocks. On 4

the commenter's last point the staff notes that NRC has not used the concept of " percentage of saturation" in the amendments, and does not anticipate using the degree of saturation as a parameter.against which sites will be evaluated.

Comment No. 2: E. Nemethy (2)

The discussion in this notice limits itself to waste burial in saturated and

! unsaturated zones.

Has the Commission given any consideratfon to above ground repositories for HLW? Over the past few years, this approach has been written about, a number

! of times.

! Should HLW be entombed in this manner, and if the containment were in the' shape of a pyramid *, it might withstand earthquakes, tornadoes and concussion from bomb blasts.

"(tetrahedron) l i 12/04/84 2 Enclosure 0 i ,

Staff Response to Comment No. 2:

The Department of Energy (DOE) is responsible for developing the methods and technology for the permanent disposal of high-level radioactive wastes (HLW).

Currently, DOE is considering disposal of HLW in mir.3d geologic repositories, and hence, the provisions of 10 CFR Part 60 only address disposal in subsurface repositories. If 00E prcposes disposal in above ground repositories, different considerations would be involved in evaluating the safety and feasibility of such a method.

Comment No. 3: J. S. Kleinhans, State of Wisconsin Radioactive Waste Review Board (5)

The Wisconsin Radioactive Waste Review Board has reviewed the proposed revisions to 10 CFR 60 for disposal of high-level radioactive wastes in the unsaturated zone. This proposed rule appears to have considerable merit since it opens up another alternative for disposal. It also appears the Commission has identified the pertinent technical concerns with disposal in the .

unsaturated zone.

Staff Response to Comment No. 3:

4 No response necessary.

Comment No. 4: R. R. Loux and C. A. Johnson, State of Nevada Nuclear Waste Project Office (8)

The State of Nevada has reviewed the proposed rule and support documents identified in the subject notice. We are satisfied with the intent of the proposed rule and feel it is in line with the State's thinking on disposal in the unsaturated zone. However, we have some comments and suggested changes to improve the proposed rule.

Staff Response to Comment No. 4:

The comments and suggested changes identified by the State.of Nevada are discussed in connection with the specific comments.

Comment No. 5: J. D. Patterson, Middle South Services (10) i Middle South Services, Inc. (MSS) is a technical support company for the Middle South Utilities (MSU) system which serves the electrical requirements of I approximately 1,800,000 customers in portions of Arkansas, Louisiana, 12/04/84 3 Enclosure D

Mississippi and Missouri. MSS has reviewed the proposed amendments and draft NUREG-1046, " Disposal of High-Level Radioactive Wastes ir the Unsaturated Zone:

Technical Considerations" and would like to express our support of the proposed amendment which allows the disposal of high-level radioactive waste (HLW) in the unsaturated geologic zone.

The Middle South System has four nuclear reactors in operation or nearing operational status, therefore Middle South utilities has been closely following the progress being made toward the opening of the first high-level nuclear waste repository. The siting of these repositories must be limited to those geologic areas where the HLW can safely'be disposed of without significant damage to the environment or harm to the public's health. A review of the proposed amendments and its associated NUREG shows that the unsaturated geologic zone is a viable alternative to disposal in the saturated zone. Each site, whether it is located in the saturated or the unsaturated zone, should be judged based on its overall' ability to safely contain HLW. Currently, there is not sufficient technical justification to favor disposal in the saturated zone over the unsaturated zone. As mentioned in NUREG-1046, there are some factors which make disposal of HLW in the unsaturated zone preferable to disposal in the saturated zone.- Two of these factors are: (1) wastes can be emplaced in a geologic medium with low moisture content which would minimize leaching of waste packages; and (2) enhanced retrievability-wastes would be more easily accessible in an unsaturated zone if this need should ever arise. There are factors which make the saturated zone a more desirable location, however, as stated previously, each site must be reviewed based on all relevant factors, not simply on whether the site is located in a saturated'or unsaturated zone.

A balancing of all factors will ensure that the most suitable sites are chosen for the disposal of HLW. .

MSS regrets that we are unable to provide NRC with the technical comments which have been requested. 'However, we appreciate this opportunity to comment on and express our. support of this proposed amendment. The siting and the eventual operation of HLW' repositories are of vital importance to the electric utility industry. MSU enccurages and supports NRC in their endeavor to accomplish this goal withir. the time-frame established in the Nuclear Waste Policy Act.

Staff Response to Comment No. 5:

No response necessary.

COMMENTS ON NRC QUESTIONS RELATING TO GROUNDWATER TRAVEL TIME IN THE 1 UNSATURATED ZONE.

General Staff Response to Comment Nos. 6-14:

The following comments (6-14) were submitted in response to a specific NRC request for public comment on two questions related to groundwater travel time calculations in the unsaturated zone. The staff has considered the arguments i presented by the commenters in developing its recommendations on these issues. j l 12/04/84 4 Enclosure O A

Based on the discussions presented in these comments, the staff recommends that the existing provisions of $60.113(a)(2) be applied to geologic settings located in ei.ther the saturated or unsaturated zone. However, the staff still recognizes that in some cases it may be more appropriate for the Commission to utilize the approach set forth in $60.113(b) which provides the Commission with the flexi-bility to specify variations in performance objectives on a case-by-case basis, as long as the overall system performance objective is satisfied. Since these comments were solicited by NRC, the staff does not believe it is necessary to provide individual responses in this document. A discussion of the concepts presented in these comments is contained in the Statement of Considerations which accompanies the final amendments.

I Comment No. 6: B.' Dover (1)

With regard to the question of whether or not groundwater travel time represents an appropriate measure of performance for a site within the i

unsaturated zone, I feel that it is absolutely essential that the~ same standard of measure be applied to all rock types and all sites, regardless of their setting with respect to the water table. I have no idea how groundwater travel time in the unsaturated zone can be determined; neither do I have any idea how groundwater travel time through salt can be measured. Maximum likely volumetric flow rate of groundwater through the repository might well be a more appropriate measure of performance,.but if so, then this same measure should be -

i applied to all rock types and all sites. It would be absolutely unacceptable to use the alternative performance measure for a rock situated in the unsaturated zone (even though containing a considerable amount of water and, in fact, possibly be "near" saturation) and apply a different measure for a site in a salt host rock, which in fact contains an amount of water almost defying measurement and with a " groundwater travel time" (if that term can even be applied) that is so slow as to be beyond comprehension.

Comment No. 7: B. Vild, State of Rhode Island and Providence Plantations (6)

Most ground water in Rhode Island is drawn from relatively shallow stratified-drift aquifers. Hydrologists in the Division of Land Resources have informed {

us that in many areas the water table is but a few meters below the surface. i While some wells tap water which collects.in rock fractures, such water also is l found relatively close to the surface. According to our Water Resources Board, only a half-dozen or so water supply wells go below 500 feet (150 meters).

This suggests a thin unsaturated zone. It is extremely unlikely, then, based on present evidence, that the Department of Energy could locate a nuclear waste repository in the unsaturated zone in Rhode Island and be able to satisfy its own minimum depth' requirement of 200 meters (DOE siting guidelines, Sec. 960.4-2-5(d)). On the other hand, as-indicated in the proposed rule, unsaturated zones in other areas, particularly those found in arid'or semi-arid regions of the country, may be of sufficient thickness to allow the minimum l depth requirement to be met.

l l

-12/04/84 5 Enclosure D

Regardless.of whether a site is chosen within the saturated zone or the unsaturated zone, our primary concern over the long term should be the isolation of nuclear waste from the accessible environment. Disposal in the unsaturated zone has the advantage of minimizing contact between the implanted waste and ground water. As~ ground water is the most likely pathway for radionuclides to the outside, Rhode Island would support considering such an option for disposal. We have stated on a number of occasions, particularly in regard to DOE's siting guidelines, that the repository should not contaminate 4

ground water of potential use by present or future generations. The relative dryness of a thick unsaturated zone would help reduce the probability that

. contaminated ground water would reach Man.

Mcwever, ground water does flow in the unsaturated zone, and to demonstrate that its repository complies with stated performance objectives, the Department of Energy will have'to assess ground water flow in both liquid and vapor phases. Ground water travel time in the unsaturated zone will be difficult to

! calculate, as the proposed rule indicates,.because of "large associated uncertainties." Some quantification and generalization concerning ground water

travel time will be necessary nonetheless to determine if proposed "potentially 4

adverse conditions" (c)(22) and (c)(23) are present (49 FR 5937). Absent

' another parameter upon which to evaluate performance, DOE will have to attempt a " reasonable" estimate of ground water travel time to be corroborated to the extent possible when the Department characterizes the candidate site. As there may be much debate over which level of data is " reasonable" in the earlier stages of screening, Rhode Island would urge DOE and NRC t'o consult freely with the state geological contacts on this matter.

2 In its considera' tion of ground water flow (however that parameter is to be ,

determined), we would recommend that NRC direct DOE to examine how the rate and direction of ground water flow is affected by withdrawal. Rhode Island's experience indicates that changes do occur in shallow aquifers and in some cases these changes are signficant. This would appear to be a matter of concern in any case where ground water flow is discontinuous and heavily dependent on spatial and temporal events, as in the unsaturated zone.

Comment No. 8: J. J. Kearney, Edison Electric Institute (7) i 1. How can groundwater travel time in the unsaturated zone be. determined with i

reasonable assurance? Should the groundwater travel time performance objective be limited to groundwater movement within the saturated zone?

EEI/UNWMG are not aware of any general, acceptable method for determining groundwater travel time in the unsaturated zone with reasonable assurance.

However, there is no reason to strictly limit the groundwater travel time

performance objective to groundwater movement within the saturated zone. We agree with the Commission's current thinking on this issue, as described in the rulemaking notice, that if DOE can demonstrate in a particular case with

raasonable assurance that travel time for groundwater movement through the unsaturated zone can be quantified, then the Department should be allowed to include such travel time when demonstrating compliance with 10 CFR 960.113(a)(2).

12/04/84 6' Enclosure D

2. Does groundwater travel time represent an appropriate measure of perform-  ;

ance for a site within the unsaturated zone, or would an alternative performance' objective for the geologic setting, (e.g., maximum likely volumetric flow rate of groundwater through the geologic repository) be more appropriate?

EEI/UNWMG believe that groundwater travel time can, in certain circumstances, l represent an appropriate measure of performance for a site within the unsat- -

urated zone. Where it does not, however, we do not believe that an alternative performance objective, such as maximum likely volumetric flow rate, would necessarily be more appropriate. Rather, consistent with one of the alternatives posed by the Commission in the rulemaking notice, we would favor utilization of the approach set'forth in 10 CFR $60.113(b) providing the Commission with the basis to specify variations in performance objectives on.a case-by-case basis, as long as the overall system performance objective is met.

' In this connection, the Commission should specifically note in the statement of considerations accompanying the adoption of a final rule that the approach in section 60.113(b) may be particularly appropriate in the case of disposal in the unsaturated zone.

Comment No. 9: R. R. Loux and C. A. Johnson, State of Nevada' Nuclear Waste Project Office (8)

1. "How can groundwater travel time in the unsaturated zone be determined

• with reasonable assurance? Should the groundwater travel time performance objective be limited to groundwater movement within the saturated zone?"

i In our opinion, it is premature to answer the first part of the question due to

)'

the limited research devoted to the question presently. Groundwater travel time in the unsaturated zone cannot now be determined with any assurance. With time, travel time in the unsaturated zone may prove to be as predictable (with 4

similar levels of uncertainty) as travel times in saturated media. However, groundwater travel time is also subject to considerable uncertainty in the saturated zone, with the uncertainty generally increasing in fractured low permeability rocks. From our perspective, there is-little confidence that determinations can be made with reasonable assurance in either media presently.

In response to the second question, there seems to be no demonstrated basis for establishing unsaturated zone travel time performance. It is acknowledged that ground water travel time is an acceptable performance measure in the saturated zone and may be appropriate for the unsaturated zone, however, presently there is no scientific basis to support a precise number for unsaturated zone travel time performance. The 1,000 year pre emplacement ground water travel time performance objective now' established for the saturated zone cannot be projected with reasonable certainty into the unsaturated zone. We believe this uncertainty does not preclude the use of a 1,000 year travel time, but~that its use should be cautioned by the lack of scientific support to base the number.

If the 1,000 year travel time is selected as a performance measure, the NRC should consider revisiting this performance standard later when a better j understanding of moisture movement in the unsaturated zone is known.

t 12/04/84 7 Enclosure D

o 4

2. "Does groundwater travel time represent an appropriate measure of performance for a site within the unsaturatd zone, or would an alternative performance objective for the geologic setting, (e.g., maximum likely volumetric flow rate of groundwater through the geologic repository) be more appropriate?

Ground-water (unsaturated zone moisture) travel time may be appropriate in the unsaturated zone, and associated time credit to the accessible environment be considered as a measure of performance,.however, the Commission should recognize several'important factors believed to be involved in a travel time consideration of performance.

1. Travel time, and direction, may prove to be different for liquid and vapor phase moisture in the unsaturated zone.

2. Radionuclide transport may prove-more complex in unsaturated flow than in saturated flow, and not closely related to moisture flux.

Performance based upon maximum likely volumetric flow rates may be even more speculative than groundwater travel time. Presently, recharge rates (a measure of volumetric flow rate) cannot be determined with precision, especially during variable climatic conditions. We believe that, although not ideal, ground water travel time in the unsaturated zone may be an acceptable performance measure at the present time, if the factors described previously are ,

considered.

Alternative to a travel time performance standard, it is suggested the EPA standard be the performance measure by which the geologic setting is judged, or the Commission utilize the approach set forth in 60.113(b) of 10 CFR Part 60.

This section provides the Commission with the flexiblity to specify variations in performance objectives on a case-by-case basis. The prime reason for sug-gesting this approach is the current absence of detailed understanding of moisture regimens in unsaturated zone environments, and the associated radio-nuclide transport by both liouids and gases in this type of environment. As more established relationships and techniques of analysis are developed for each site, an appropriate performance objective may be possible.

Comment No. 10: M. J. Lawrence, U.S. Department of Energy (9)

The Department believes the performance objective for a minimum 1,000 year groundwater travel time should only be applied to sites located in the saturated zone. The Department recommends an alternative performance objective, related to the geologic setting, for sites located in the unsaturated zone. The Department will provide a suggested alternative performance objective for NRC consideration by separate letter after the close of the public comment period. The Department will make every effort to provide this information by May 15, 1984.

Ccmment No. 11: M. J. Lawrence, U.S. Department of Energy (9)

Question 1. This question, as stated in the Supplementary Information Section, consisted of two questions which are addressed separately below.

12/04/84 8 Enclosure D

s . .

A. ".How can ground-water travel time in the unsaturated zone be determined with reasonable assurance?"

l Ground-water flux can be determined, using measurements of ambient water content, degree of saturation, matric potential, and hydraulic conductivity to determine moisture-characteristic curves relating these parameters to one 4

another. These curves can be developed so as to predict the constitutive relationships over a wide range of conditions (varying degrees of saturation and different matric potentials). From these relationships and flux determin-ations, velocity and subsequently ground-water travel time can be estimated.

In situ monitoring techniques, including tracer tests, are undergoing develop-ment and may broaden the range of rock types and conditions for which it is i feasible to estimate velocity and ground-water travel time. NNWSI program investigations also presently include exploratory shaft tests on infiltration

^

rates and sampling of intact fractured blocks for laboratory experiments.

These techniques and investigations are state of-the-art and should provide a direct determination, with reasonable assurance, of the ground-water flux used to estimate the ground-water travel time. In addition, DOE believes that reasonable bounds may be developed by less direct methods such as recharge rates determined from water budgets, perturbations of thermal gradients, or in situ monitoring of temporal changes in moisture profiles.

Reasonable assurance, therefore, may be gained in estimating ground-water travel time using results of laboratory testing, state-of-the-art direct deter--

minations in the field or laboratory, and bounding estimates developed by indirect methods. In addition, reasonable assurance may also be gained by incor-

porating uncertainty analysis into predictive models. Although the uncertainty band for a given level of confidence in the calculations may be broad owing to the inability to measure ground-water velocities along all segments of the unsaturated zone travel paths or under all. combinations of moisture conditions and matric potentials, the opportunity to invoke conservatism in the ground-

_ water travel time calculations still exists.

B. "Should the ground-water travel time performance objective be limited to ground-water movement in the saturated zone?"

i For a repository in the unsaturated zone, DOE does not believe the ground-water travel time objective should be limited to the saturated zone because this would not be an accurate indicator of actual radionuclide transport from the original waste locatio'n to the accessible environment (as discussed in the response to Question 2A). DOE has proposed, in discussions with the NRC on the siting guidelines (10 CFR Part 960), that this performance objective be limited to only sites located in the saturated zone, with a separate performance objective developed for the geologic setting for sites situated in the unsaturated zone. (See response to. Question 2b)

Question 2. This question, as stated in the Supplementary Information Section, also consisted of two questions which are addressed separately below:

12/04/84 9 Enclosure D

A. "Does ground-water travel time represent an appropriate measure of performance for a site within the unsaturated zone?"

DOE does not believe that ground-water t?:ael time represents an appropriate measure of performance for a site within the unsaturated zone. The flux i

through the repository, both in the unsaturated and saturated zones, is a more appropriate and direct measure of potential cumulative releases to the

!' accessible env~ironment. The amount of water moving past the wastes is one of the primary factors which set a limit, independent of flow velocity, flow path, or travel time, on the maximum number of curies of a particular radionuclide that can be released from a repository and subsequently be transported by ground water to the accessible environment. DOE notes that Dames & Moore reach essentially the same conclusion in NUREG/CR-3130 when they concluded that flux and the frequency of wetting events were the primary factors in determining releases from wastes disposed in the unsaturated zone.

Should the NRC, however, choose to keep a minimum 1000 year ground-water travel time as the performance objective for the geologic setting, DOE believes it j should logically be applied to sites situated in the unsaturated zone only if the travel time will include the combined travel times in the unsaturated zone i and the saturated zone so as to better approximate radionuclide transport.

This may necessitate a revision to the definition of the term " disturbed zone,"

since the current definition is so vague as to possibly permit defining the .

i disturbed zone as extending downward through the unsaturated zone all the way to the water table or upward through the unsaturated zone all the way to the j ground surface. DOE believes it would be inappropriate to apply the minimum ground-water travel time to only the saturated zone underlying a repository in the unsaturated zone, since such application would conflict with three highly favorable conditions resulting from a highly transmissive (and short travel time) water table aquifer underlying the repository. These are:

1. A highly transmissive aquifer can be expected to transmit any increased throughflow, resulting from increased precipitation during a glacial stage, with less rise in the water table and accordingly less likelihood

~

of saturation of the respository from below.

2. A highly transmissive aquifer can be expected to significantly dilute any i

postulated releases from the repository since the characteristically low flux in the unsaturated zone would be a very small fraction of the j throughflow in the aquifer.

3. A highly transmissive aquifer can be expected to significantly disperse any postulated releases from the repository since the dispersivity of the aquifer would be quite high.

Therefore, although a highly transmissive acuifer underlying a repository f

i situated in the unsaturated zone may not provide a 1000 year ground water

' travel time to the accessible environment, it does not affect the flux through the unsaturated zone (hence it does not affect the cumulative release to the accessible environment over the 10,000 year period of interest). In addition, although the EPA standard is not based on dose, DOE notes a highly transmissive aquifer underlying a repository in the unsaturated zone provides a means of l

l 12/04/84 10 Enclosure D

.-,..-,,,,,,n

,w - , - -- -. --.-- - -. ., .---....-e..._, ..~,---o._~.

4 assuring the reduction of the concentration of (and hence dose received from)

~

1 any postulated releases due to dilution and dispersion (thereby being applicable to both reactive and non reactive radioisotopes without

] consideration of sorption and other retardation processes).

B. "Would an alternative performance objective for the geologic setting (e.g., maximum likely volumetric flow rate of ground water through the geologic repository) be more appropriate?"

' l l

DOE believes an alternative performance objective for the geologic setting for l a repository located in the unsaturated zone is more appropriate. DOE has initiated a concerted effort to develop such a performance objective for prcposal to the NRC. This activity is still in progress,-and DOE will provide an alternative performance objective by separate letter after the close of the public comment period. DOE will make every effort to provide the alternative performance objective by May 15, 1984.

DOE believes that the volumetric flow rate (flux) of ground water through a  !

geologic repository located in the unsaturated zone is the most important factor in determinig the performance of the repository. However, DOE cannot at this time propose or endorse a numerical performance objective on maximum flux

, since the acceptable flux would be site-specific and design-specific.

DOE will continue, however, to consider flux and other factors in its attempt to develop an alternative performance objective for the geologic setting for a repository located in the unsaturated zone.

Comment No. 12: B. C.'Rusche, U.S. Department of Energy (Addendum to Letter 4

No.9)

As noted in the DOE comment letter to the NRC dated April 16, 1984, Dames &

Moore concluded in NUREG/CR-3130 that the flux and the frequency of wetting

events were the primary factors in determining releases from wastes disposed in the unsaturated zone. DOE stated that ground-water travel time does not represent an appropriate measure of performance for a site within the 1

unsaturated zone and that the flux through the repository,.both in the unsaturated and saturated zones, is a more appropriate and direct measure of i

potential cumulative releases to the accessible environment.

Accordingly,- DOE has given considerable effort toward developing a proposed performance objective based on flux through a repository located in the unsaturated zone. Although this effort has reinforced the understanding that flux is the primary factor in determining releases from wastes disposed in the j unsaturated zone, DOE has concluded that it is impractical to specify a minimum amount of flux or to otherwise define a performance objective for the geologic settings based on the flux through the repository. A determination of flux l will be necessary, however, to demonstrate compliance with the EPA Standard.

As a result, DOE reviewed the NRC rationale for the performance objective specifying that the fastest likely path of radionuclide travel to the accessible environment shall be at least 1000 years or euch other travel time as may be approved.or specified by the Commission. This pt:r: 1:6nce objective can be interpreted as specifying a minimum time before relet n of radionuclides to 12/04/84 11 Enclosure D

the accessible environment. DOE concludes, based on this review and inter-action ~s between NNWSI Project staff and the NRC staff, that satisfying this performance objective is meant to provide an independent and redundant barrier to the engineered barrier system during that period of time when the wastes are most hazardous (46 FR 130, p. 35281). DOE notes that, for sites located in the unsaturated zone, this same effect may be derived, either in whole or to a large extent, from the creation of a drying zone around the underground facility during the period of the heat pulse. Therefore, the concept of a minimum time for release of radionuclides to the accessible environment forms a reasonable basis for a site performance objective for the unsaturated zone and is a more appropriate performance objective than ground water travel time for the unsaturated zone.

1 The emplacement of radioactive waste canisters within an unsaturated zone

repository leads to a situation wherein the heat generated by the wastes as they decay causes the moisture in the rock surrounding the waste canisters to 3 migrate away from the waste canisters. Preliminary numerical modeling of this 4

phenomenon 1 indicates that this migration creates a zone around the canisters, extending for a few tens of meters in which there is no water available to either corrode the canisters, dissolve the wastes, or transport any radioactive i

material. The drying phase for a saturated zone repository is expected to last several hundred years before resaturation is complete (NUREG-0804). In an unsaturated zone repository, the time required for moisture to return to the waste packages is expected to be even longer because the rock will return to j initial conditions primarily through capillary effects.

A site performance objective for the unsaturated zone, based upon the minimum time for release of radionuclides to the accessible environment, must consider i four separate physical events. The first event is the creation of the drying zone. The second event, which is closely related to the creation of the drying zone, is the subsequent return of moisture to the rock surrounding the waste canisters. These two events encompass a time during which no water is

! available to either corrode the waste canisters, dissolve the waste material, or transport radionuclides to the accessible. environment. The third event important to the release of radionuclides to the accessible environment is the transport of radionuclides in the unsaturated zone. Finally, the radionuclides are transported to the accessible environment by ground water movement in the saturated zone.

l The minimum time for release of radionuclides to the accessible environment is the sum of times required for each of the four events because they are temporally sequential. The minimum time for release of radionuclides to the accessible environner$ for an unsaturated zone repository is thus the sum of the time during which a drying zone exists around the waste canisters, the time

, it takes for the dry rock to return to initial moisture conditions, the time for ground water to travel through the unsaturated zone and the time for ground water to travel through the' saturated zone to the accessible environment.

28. Travis, H. Hudson, T. Nuttall, T. Cook, and R. Rundberg,1984, j " Preliminary Estimates of Water Flow and Radionuclide Transport in Yucca Mountain," LA-UR-84-40 (in Review), Los Alamos National Laboratory,

, Los Alamos, New Mexico.

I 12/04/84 12 Enclosure D 1

3 It is not inconceivable that the time for drying added to the time for return

! to' initial moisture conditions could encompass the total 1000 year period required for fission products to decay to insignificant levels.' When all four time components are added together, significantly higher confidence in protec-tion of public health and safety is obtained than if only the time when radio-nuclides are actually moving were considered.

The NNWSI Project site characterization activities include studies of the drying

~

phenomenon. In addition to the previously mentioned study of radionuclide transport and the formation of the drying zone, other numerical studies which model the physical responses, in the unsaturated zone, to the emplacement of waste canisters and heat are underway. In situ tests to obtain information )

about moisture migration in response to thermal loads are planned for the exploratory shaft. These tests include bulk permeability tests., canister scale-heater experiments and waste package tests. The waste package tests are reduced scale but are designed.to specifically investigate moisture conditions, particularly moisture movement during thermal and post thermal periods of-storage. High frequency electromagnetic, ultransonic and neutron methods are to be used to establish the moisture content in the area surrounding the simulated canister before and after thermal cycling and to monitor fluid movement during the experiments. These activities should provide the necessary

' and sufficient information. to support demonstration of compliance with the proposed alternative performance objective.

Proposed Alternative Performance Objective DOE proposes that Section 60.113(a)(2) be revised to Section 60.113(a)(2)(i) and a Section 60.113(a)(2)(ii) be added as follows:

For a geologic repository located in the unsaturated zone, the minimum 1000 year travel time to the accessible environment shall include the time of existence of the drying zone around the emplaced wastes, -the time required for rewetting to initial moisture conditions, the time of travel through the unsaturated zone, and the time of travel through the

, saturated zone.

t 4

Comment No. 13: A. Hirsch, Environmental Protection Agency (11) i With respect to the three questions on which the Commission particularly seeks comment:

Question: "How can ground water travel time in the unsaturated zone be determined with reasonable assurance?"

EPA Reply: EPA's Office of Solid Waste will soon publish Procedures for Modeling Flow Through Clay Liners to Determine Required Liner Thickness in its series of Technical Resource Documents. This manual presents a numerical simulation model to estimate travel time of water through unsaturated sediments. Once i

f L

I 12/04/84 13 Enclosure D

copies are available from GPO, we will forward one to Dr. Colleen Ostrowski at the NRC.

Measuring natural tritium (8 H) concentrations in ground water samples from a vertical profile in unsaturated geologic formations may be another technique for estimating travel time. Since the atmospheric testing of nuclear weapons, ground water recharge (i.e. , precipitation) has contained levels of this radio-active isotope above the naturally low levels existing before the testing began. Consequently, tritium may serve.as an indicator or tracer of "rew" water in a geologic profile, and thus may indicate approximate travel times from the recharge point.

Question: "Should the ground water travel time performance objective be limited to ground water movement within the saturated zone?"

EPA Reply: No. To allow DOE to take credit for the delay in water reaching the water table after' passing an unsaturated zone repository (when considering NRC's existing 1,000 year." ground water" travel time requirement), NRC proposes to redefine the term " ground water" to include all water below the land surface, not just water below the water table, in the saturated zone. We do not think it is necessary to change the widely understood meaning of this term to accomplish NRC's objective. EPA agrees that DOE should be able to take credit for any such delays in the unsaturate J :one. However, it would be more appropriate to make the existing section 60.113(a)(2) apply only to repositories in the saturated zone and to add a parallel section for unsaturated zone repositories that allows the Department to add the water travel times in the saturated and unsaturated zones to compare against the 1,000 year time period. Even if NRC redefines the term " ground water" for 10 CFR 60, EPA has no plans or need to make a corresponding change in 40 CFR 191.

Question: "Does ground water travel time represent an appropriate measure of performance for a site within the unsaturated zone, or would an alternative performance objective for the geologic setting be more appropriate?"

EPA Reply: No, it does not. An alternative option should be available. EPA does not believe that such a " water" travel time is appropriate as the only quantitative measure of per > mance for a site within the unsaturated zone.

Instead, we believe that DOE should have the option of meeting a fairly stringent' limit on the average annual flux of water through the repository to the accessible environment instead of the travel time requirement of section 60.113(a)(2). This limit should be chosen so that the corresponding total volume of water reaching the accessible environment within a thousand years would not be capable of transporting a significant amount of radioactivity, taking into account reasonable solubility limits. At a particular site, the Department should have.the option of demonstrating compliance with either the minimum travel time requirement or the maximum water flux requirement.

12/04/84 14 Enclosure D

i Comment No. 14: B. Blanchard, U.S. Department of the Interior (13) l (la) "How can ground-water travel time in the unsaturated zone be determined with reasonable assurance?" While it may not bt possible to define ground water velocities along all segments of unsaturated-zone travel paths with precision, particularly those segments through moderately to highly fractured media, the velocities and travel times in some segments are less elusive. In the case of a relatively uniform, porous medium with low-fracture density, the medium will be capable of transmitting a flux that is ahproximately equivalent to its saturated hydraulic conductivity without rejecting water to fracture flow paths. Further, it is within the state-of-the-art to determine ambient water content and degree of saturation as well as moisture-characteristic curves for such media so that effective conductivity can be predicted for a range of conditions. In-situ monitoring techniques are undergoing development and may broaden the range of rock types and conditions for which it is feasible to estimate velocity and, hence, travel time. On a site-specific basis, certain bounds may be placed by less direct considerations such as recharge rates based on water budgets, perturbations of thermal gradients, or in-situ monitoring of temporal changes in moisture i

proffles by neutron logging. Finally, repository investigations presently include exploratory-shaft tests on infiltration rates and sampling of intact j fractured blocks for laboratory experiments.

" Reasonable assurance" may also be gained by incorporating uncertainty analysis into predictive models. Although the uncertainty band for a given level of confidence in the calculations may be broader for unsaturated-zone cases than for some saturated-zone conditions, the opportunity to invoke conservatism j still exists.

l (1b) "Should the ground-water travel time performance objective be limited to ,

t ground-water movement within the saturated zone?" Assuming that the ground-l water travel time objective and favorable condition remain in the regulation, l the travel time along any segment of the flow path including the unsaturated zone, should be creditable, provided that it can be demonstrated with

" reasonable assurance" as discussed above.

(2) "Does ground-water travel time represent an appropriate measure of performance for a site within the unsaturated zone, or would an alternative performance ob.fectU e . . . (e.g., maximum likely volumetric flow rate of ground water through the geologic repository) be more appropriate?" Travel time substantially exceeding 1,000 years, although a favorable condition, is not appropriate as a totally definitive performance objective for disposal in either the unsaturated or saturated zones. Ground-water travel time probably is the singularly most important element for evaluating the performance of a site; however, release criteria are ultimately the absolute measure of' total performance. The method by which travel time is calculated must account for all elements of the ground-water flow system and must result.in terms that can be used directly for determining transport and concentration of radionuclides in the ground water. Release criteria and radionuclide transport must be concerned with many factors such as' ground-water flux and velocity (travel' time), convective transport, dispersion and diffusion, chemical interaction with rocks along the flow path, and rates and concentrations at which radio-nuclides leached from the solidified waste enter the water. Realistic 12/04/84 15 Enclosure D

estimation of release criteria for the unsaturated zone might not.be possible I until observations are made in the shafts and drifts.

4 While it may be possible to assign a maximum allowable flux rate- e.g., one that would assure the failure of containment under reasonable assumptions of chemistry, corrosion, and dissolution--it would still be more consistent with the multiple-barrier concept to incorporate such considerations only as favorable or potentially adverse conditions.

COMMENTS ON THE PROPOSED DEFINITION OF THE TERM GROUN0 WATER (60.2)

Comment No. 15: R. R. Loux and C. A. Johnson, State of Nevada Nuclear Waste Project Office (8)

Redefining " groundwater" '(ground water) for a regulatory purpose, particularly in view of the fact that the scientific community will make the field and laboratory determination, is not desirable. It would be much better for NRC to define and' adopt a term or phrase that does.not already have a precise meaning in technical community and literature, such as " subsurface moisture."

" Groundwater" already has a widely accepted meaning.which does not include vadose or unsaturated zone water.

Staff Reponse to Comment No. 15:

Presently there does not appear to be unanimity in the scientific community concerning how " groundwater" should be defined. Therefore, the staff has not

" redefined" the term " groundwater," but rather has adopted one of the acceptable definitions of the term currently in use by members of the scientific community. Further, in final' amendments the phrase " Earth's surface" is replaced by " land surface" for the sake of clarity.

Comment No. 16: M. J. Lawrence, U.S. Department of Energy (9)

The NRC is to be commended on the definition of the term " ground water." The NRC definition includes water in both the unsaturated and saturated zones.

This definition is, however, inconsistent with the EPA definition in 40 CFR Part 191, wherein the EPA defines ground water to include only that water in the saturated zone. 00E agrees with the NRC definition. Using the EPA defini-tion, DOE believes the proposed amendments would have to be revisited in their entirety.

12/04/84 16 Enclosure D

i .

Staff Response to Comment No. 16:

In its proposed environmental standards. published in December, 1982 EPA defined the term " groundwater" as " water below the land surface in a zone of saturation" (47 FR 58205). With respect to the differences between the definition of the term " groundwater" adopted by NRC in $60.2 and that proposed by EPA the staff notes that it does not consider the two definitions to be inconsistent since the scope of the NRC definition will encompass water within the zone of saturation as well as water within the unsaturated zone. The staff considers it necessary for NRC to adopt a broader definition of the term so that it can effectively apply the provisions of Part 60 to the regulation of I

HLW disposal within unsaturated as well as saturated geologic media. Further, since EPA has not yet promulgated its final rule -- 40 CFR 191 the staff cannot anticipate whether or how " groundwater" will actually be defined by EPA.

4 Comment No. 17: A. Hirsch, Environmental Protection Agency (11)

NRC proposed to redefine the term " ground water" to include all water in both the saturated and unsaturated zones. This change apparently provides a simple regulatory means for applying existing criteria written several years ago for high level waste repository siting in the saturated zone to the unsaturated zone as well. While this expansion of applicability may be reasonable, EPA would prefer that the NRC retain the standard scientific meaning for the term (i.e., water within the zone of saturation). We are concerned that confusion may eventually arise among the public, particularly in their understanding of the application of methods of ground water monitoring.

Staff Response to Comment No. 17:

See response to Comment No. 15.

12/04/84 17 Enclosure D

COMMENTS ON THE PROPOSED DEFINITION OF THE TERM " UNSATURATED ZONE" Comment No. 18: R. R. Loux and C. A. Johnson, State of Nevada Nuclear Waste Project Office (8)

This is a questionable definition because " deepest water table" has been used.

The definition is taken from Lohman et al. 1972,1 but is not, to our knowledge, widely accepted. In some terrain and climates it may lead to inclusion of extensive' areas of saturation. The following is a more satisfactory definition for the unsaturated zone:

"The unsaturated zone is that region of the earth materials between landsurface and regionally saturated earth materials. There is discontinuous and incomplete saturation of the interconnected voids in the earth materials, and therefore no continuous positive hydraulic continuity with the regionally saturated zone. Perched zones (zones with void saturation and local positive potential and hydraulic continuity) may be present within the unsaturated zone." ,

This follows 0.E. Meinzer's intent in definition, and incorporates local but

not regionally perched water.

Staff Response to Comment No. 18:

In an effort to maintain internal consistency with other Federal agencies, the

~

NRC staff has adopted or modif*ed the hydrogeologic definitions presented in U.S. Geological Survey Water Supply Paper 1988 for use in the NRC regulations related to HLW disposal in geologic repositories whenever possible. To mimimize confusion surrounding this definition minor technical changes have been made in the final amendments to Part 60 including changing the phrase

" deepest water table" to " regional water table." Similar conforming changes to the definition of " Saturated zone" have also been made.

Comment No. 19: A. Hirsch, Environmental Protection Agency (11)

" Unsaturated zone" should be defined as the zone between the land surface and the shallowest free water table, discounting " perched" tables. The definition I

written in the proposed regulation says, " deepest." This is confusing. The definition with " deepest" would be correct, however, if the term " water table" were also defined as the potentiometric surface beneath the. land surface at atmospheric pressure.

l

'Lohman, S.W. et al., 1972, Definitions of Selected Ground-Water Terms Revisions and Conceptual Refinements, U.S. Geological Survey Water Supply Paper 1988, 21 p.

12/04/84 18 Enclosure D

I I

l Staff Response to Comment No. 19:

l See response to Co'mment No. 18. Also, the term " water table" is defined in 10 CFR Part 60 as "that surface in a groundwater body at which the water

pressure is atmospheric." (48 FR 28219) l l

) COMENTS ON PROPOSED 60.122(b)(7)

Comment No. 20: J. J. Kearney, Edison Electric Institute (7)

These comments are being submitted by the Edison Electric Institute (EEI) and the Utility Nuclear Waste Management Group (UNWMG) in response to the above-4 referenced notice. We support amendment of the Commission's regulations in

!' 10 CFR Part 60 so that the technical criteria for geologic disposal in the saturated zone may be equally applicable to disposal within the unsaturated zone. In particular, we support' adoption of the specific amendments presented j in the Commission's notice as appropriate for providing for such disposal with i one exception.

! Proposed $60.122(b)(7) would apply to disposal in both the saturated and i

unsaturated zones. As indicated in the rulemaking notice, however, determining

' groundwater travel time in the unsaturated zone may not be necessary nor always be possible. Under such circumstances, inability to demonstrate a " groundwater travel time along the fastest path of likely radionuclide travel from the disturbed zone to the accessible environment that substantially exceeds l

' 1,000 years" should not amount to the absence of a favorable condition. This is especially so in a case where the conditions prescribed in proposed

$60.122(b)(8) exist. Accordingly, the groundwater travel time identified as a

} favorable condition in proposed $60.122(b)(7) should not apply to disposal in the unsaturated-zone.

l Staff Response to Comment No. 20:

! The staff recognizes that there may be difficulties associated with groundwater 1

l travel time calculations given the current state of groundwater investigations.

j However, the staff has concluded that groundwater travel time calculations can be determined in the unsaturated zone provided that the proper level of site j characterization ana. lyses are conducted by the applicant. Following a detailed study of the public comments submitted on the. Commission's questions pertaining j to groundwater travel time in the unsaturated zone (Comment Nos. 6-14), the i staff believes it is feasible for DOE to demonstrate the implementability of 1

i 12/04/84 19 Enclosure 0

.,-c.. ,,,.- , , - - , - - - , , , - - - - - --

-e --- ,y .---m- -

, - - - - - - . - - , - , , , - . - - - - - + , . - - - - - . - - - - .

4 the groundwater travel time provisions using currently available standard field

{ and laboratory experiments. Further, as'several commenters indicated, a substantial effort is presently underway both to improve existing techniques and to develop new methodologies for measuring the hydrogeologic parameters and flow properties that wi,11 provide the necessary input to groundwater travel time calculations. With respect to the commenter's final point, the staff notes that if, for a particular site, the value for pre-waste emplacement groundwater travel time along the fastest path of likely radionuclide travel

! from the disturbed zone to the accessible environment is deemed to be substantially in excess of,1,000 years so as to enhance the Commission's confidence that the performance objectives will be met, then it can '

appropriately be considered as a favorable condition. The commenter's reasons l for connecting SS60.122(b)(7) and (8) are not clear to the staff. Finally, the

~

staff reiterates NRC's position that it is important to recognize that a site is not disqualified as a result of the absence of a favorable condition (48 FR 28201).

2 Comment No. 21: B. Blanchard, U.S. Department of the Interior (13)

Section 60.122, Siting Criteria, (6), (7): "Prewaste-emplacement around-water travel time along the fastest path of likely radionuclide travel-from the disturbed zone to the accessible environment that substantially exceeds 1,000 years." Add" . . . considering both unsaturated and saturated segments of the flow path." We believe that prewaste-emplacement ground-water travel time is conceptually an appropriate " favorable characteristic" for sites located in the unsaturated zone. However, it is a criterion that will be much more difficult to demonstrate in a legal sense at an unsaturated site than at a saturated site. As currently worded, the criterion is perhaps inappropriate for unsaturated and perhaps some types of saturated sites, such as salt and dense fractured crystalline rocks.

We believe that in' order for the travel-time criterion to be effectively applied, it needs to incorporate a concept of areally and' temporally averaged ground-water flow velocity (rather than the fastest one-dimensional pathway) 1 and/or a flux constraint. Additionally, the current wording makes no provision for the quantity of water moving through the repository to the accessible 12/04/84 20 Enclosure D

environment--only the velocity. It seems inappropriate to reject a site that might have 1 cubic meter of water moving through a repository to the accessible environment in 1,000 years and to accept a site that might have 1 million cubic meters of water moving through it to the accessible environment in 1,500 years.

This example is, of course, hypothetical.

We also realize that there is an exception clause in the criterion for special~

considerations allowing the Commission to consider other factors when appro-pr.iate and when it can be demonstrated that a site would clearly meet EPA standards. However, it is not clear how that exception might be applied or what difficulties would be encountered in gaining acceptance by the technical community or various public interest groups for such an exception. Some of these difficulties might be overcome by one or more of the following options:

Clarify some typical circumstances under which the travel-time criterion might be waived, such as by demonstrating that the flux is likely to be small or nil.

Specify more precisely how the ground-water velocity (or travel time) should be calculated, using specific cross section area or other averaging or integrating conventions.

Use a volumetric flow rate (flux) criterion for ground water in addition to or in place of ground-water travel time.

The principal hydrologic advantage of the unsaturated zone is minimizing or eliminating contact of the waste with flowing ground water. This advantage would most likely be more important than ground-water travel time in reducing total quantity of radionuclides which could potentially escape to the j accessible environment. The rate of release of radionuclides to the accessible environment from a repository in the unsaturated zone is directly related to the nuclide concentration in the leachate, flux of leachate, dilution of leachate in the zone of saturation, and ground-water velocity (plus geochemical retardation and dispersion effects). Minimizing leachate flux would appear to be at least as important as maximizing ground-water travel time.

It might, therefore, be appropriate to specify a dual "either/or" criterion l

' such that ground-water travel time is greater than 1000 years or ground-water flux through the host rock at the proposed site is less than some specified

, average rate. The rate could be based on nuclide solubility, leach rate l criteria, and population exposure criteria (EPA concentration standards).

We believe that either a flux or travel-time criterion should be based upon an areally integrated or averaged calculation, over an area on the order of the cross-sectional area of the repository normal to the direction of expected i flux, for both saturated and unsaturated sites. This would help reduce the j uncertainty'and controversy over how the " fastest pathway" can be determined.

t The fastest pathway for saturated fractured rocks, for unsaturated media, and for other highly heterogeneous media could be virtually impossible to calculate i with reasonable confidence. However, areal averaged or integrated calculations l and bounded estimates can be determined with reasonable confidence, usually by two or more independent methods. Also, qualitative evidence, such as the preservation of archeological artifacts, packrat middens, and other paleo-l 12/04/84 21 Enclosure 0

materials can lend further confidence to long-term estimates of leach rates and water contact in arid unsaturated materials. If ground-water travel time is to l remain a general performance objective criterion for the unsaturated zone, we l believe the rule should specify a simple, straigntforward, and consistent l formula for site determination. We propese the following formula for '

consideration. Use of the formula is with the assumption that movement of water in the unsaturated zone is basically interstitial and that at least a

continuous film of water is present. The formula would have doubtful applica-tion in dominantly fractured rock with very little interstitial effective porosity. -

The vertical ground-water velocity through the unsaturated zone could be determined as the average vertical recharge rate over the approximate area of the repository, divided by the average volumetric moisture content of the subsurface medium. As a hypothetical example, if a site were determined to have an average recharge rate of 10mm per year and an average subsurface moisture content of 10 percent (10 percent of bulk volume contains water), an average velocity would be 10/0.1 or 100mm per year (0.1m per year). If it were 100mm above the water table, the travel time in the unsaturated zone alone would be 1000 years. It becomes o.bvious that a nearly zero moisture content would result in a theoretically infinite velocity. This is absurd', but does emphasize the need for prudent application of any mechanism with which to approximate conditions that defy accurate analysis. Ground-water velocity is

' one important element of performance and although this method is not precise or

highly accurate, the method could form the basis for approximations that could be consistently applied to a variety of sites where unsaturated porous media are part of the flow system.

Staff Response to Comment No. 21:

The additional word changes suggested by the commenter with respect to 60.122(b)(7) have not been adopted since the definition of the term

" groundwater" (60.2) will assure that both the unsaturated and saturated segments of a flow path are considered.

With respect to the commenter's second point, the staff anticipates that temporal and spatial variations in the hydrologic regime will be addressed in the evalua-tion of uncertainties surrounding the groundwater travel time calculations.

The staff considers the fastest pathway criterion to be a more appropriate mea-sure of performance than the suggested averaged velocity criterion. On the issue of flux as an alternative to travel time, the staff believes that 'it may be impractical to specify a minimum amount of flux or to otherwise define a 12/05/84 22 Enclosure 0

performance objective based on flux through a geologic repository. However, the staff notes that flux is an important hydrologic parameter that should be considered in future NRC evaluations of whether or not a site meets the required performance objectives. Finally, on the commenter's last point in the second paragraph, NRC's primary interest is not the quantity of groundwater moving towards the accessible environment per se, but rather the radionuclides con-tained in that groundwater.

The commenter's third point on the exception clause of the groundwater travel time criterion was discussed at length by the Commission at 48 FR 21896-21897.

4 The staff agrees with most of the technical discussion presented in the fourth paragraph. The commenter's statement that minimizing leachate flux would appear to be at least as important as maximizing groundwater travel time has bean addressed in the above discussion.

The staff does not consider it necessary to specify a dual "either/or" ground-water criterion as suggested by the commenter since under the provisions of

$60,113(b) the Commission already has the flexibility to approve or specify some other radionuclide~ release. rate, designed containment period or pre-waste-

, emplacement groundwater travel time on a case-by-case basis.

l With respect the commenter's final point the staff anticipates that groundwater travel time and flux calculations which involve averaging or areal integration will be addressed in the evaluation of uncertainties surrounding groundwater travel time calculations during the licensing review process.

12/05/84 23 Enclosure D

I j

COMMENTS ON PROPOSED 60.122(b)(8)(1)

Comment No. 22: M. J. Lawrence, U.S. Department of Energy (9)

The words "and nearly constant" should be removed so that this section reads

" Low moisture flux in the host rock and in the overlying and underlying hydro-4 geologic units."

DOE notes that recharge is not constant.in either time or space. Rather, recharge is sporadic, occurring in response to individual heavy rainfalls,

extended periods of rainfall (wet season), or snowmelt. Between these recharge

, events, water in the unsaturated zone is held in tension and flux becomes l negligible an obvious advantage of disposal in the unsaturated zone. These i findings led Dames & Moore to conclude in NUREG/CR-3130 that the flux and the frequency of wetting events were the primary factors in determining releases from wastes disposed in the unsaturated zone.

Staff Response to Comment No. 22:

The commenter's point is well taken. The phrase "and hearly. constant" has been

] deleted from the provisions of 60.122(b)(8)(i).

Comment No. 23

B. Blanchard, U.S. Department of the Interior (13) 1 Section 60.122(b)(8)(i): " Low and nearly constant moisture flux in the host-I rock and in the overlaying and underlying hydrogeologic units." This is an improvement over the earlier " low and constant moisture content" in that it

, avoids the erroneous implication that low moisture content necessarily means low flux. However, "nearly ' constant" . . . flux is not necessarily an advantage, as evidenced by the conflict with " free drainage."

Section 60.122(b)(8)(iv). A low, constant rate of flux would seem to offer

, better opportunity for dissolution processes.than would an average low, but

! episodically high flux. There is some evidence also that some materials for l waste canisters may be more resistant to corrosion under episodic wetting and drying. Basically, it seems best to address only a single concept or factor in

[ a singla statement of condition. Also, change " overlaying" to " overlying."

Staff Response to Comment No. 23:

See response to Comment.Nos. 22 and 28. Also, the typographical error in the word " overlying" will. be corrected in the final rule.

j COMMENTS ON PROPOSED 60.122(b)(8)(ii)

Comment No. 24: M. J. Lawrence, U.S. Department of Energy (9)

DOE is concerned with the NRC approach to the concept of capillary fringe as

described in this condition and on page A-1 of Appendix A to NUREG-1046. DOE 4

12/04/84 24 Enclosure D 1

- - - - .-J-.,--- , - - , - . , .- , - . - - ~ . , - , - - -- - - - , , , - , . . . ~ . . n.- - - - - . - ---v- -, n,. ~~ s.----~,,.---

i l l

3 notes that the upper surface of the. zone of tension saturation (capillary fringe) is neither constant nor planar; rather, it is dynamic and at different heights in materials of different pore sizes owing to the higher capillary rise in smaller pores.

The NRC has addressed the DOE concern about the number or percent of fully

saturated. voids continuous with the water table in NUREG-1046, wherein they-

. have suggested a definition of capillary fringe as a planar surface, at which 50 percent of the pore space is filled with water. This suggested definition corresponds with the usage in USGS Water-Supply Paper 1988.

• However, the suggested definition can be interpreted as applying to any material having a degree of saturation of 50 percent or greater. DOE notes that, at a degree of saturation of 50 percent, no pore spaces have to be completely filled with water (and hence it would be above the capillary

fringe). DOE believes the intent of the definition is a planar surface at which 50 percent of all pore spaces are completely filled with water i (50 percent of all pore spaces are not completely filled with water). 00E does

not believe that either approach can be defined by field measurements. ,

00E believes the concept of avoiding waste emplacement in the capillary fringe is valid, though the definition of the capillary fringe will always elude

precision. The capillary fringe is something that everyone knows exists, but

! which no one can adequately define. Even if an unambiguous, non arbitrary j

definition is found, the upper limit of the zone of " fully saturated voids i continuous with the water table" can probably not be defined by field measure-i ments, particulary under conditions of heterogeneous materials and infiltrating

! water. However, in .very few, if any, cases could the upper limit of the capil-t lary fringe be more than a few tens of meters. DOE recommends this section be

{ revised to recognize that it is physically limited to a few tens of meters.

Staff Response to Comment No. 24:

The staff recognizes that the location of the upper limit of the zone of " fully

[ saturated voids continuous with the water table" may be a difficult parameter to determine by field measurements. However, proposed alternatives do not

[ avoid the difficulties both in measuring this zone's top and in determining its hydrologic connection with the water table. Also, the staff does not consider it appropriate to quantify a generic upper limit for this zone due to its site-specific nature. The staff believes that both the extent and nature of the capillary fringe will'be highly site-specific parameters.

l l

l 12/04/84 25 Enclosure D

With respect to DOE's comments in the second and third paragraphs related to

the discussion provided in the definition of the term " capillary fringe" in Appendix A of draft NUREG-1046, of the level at which 50% of the pore spaces are filled with water the staff notes that DOE has misconstrued the intent of the statement "For instance, this limit may be defined as the leyel at which 50 percent of the pore space is filled with water" (pA-1). This statement was j included in the definition of the " capillary fringe" provided in USGS Water 3

Supply Paper 1988 (1972) and appeared to represent an example of how the upper limit of the c=oillary fringe may be more or less defined arbitrarily in some quantitative studies. The NRC staff did not intend this statement to be 2

interpreted in the manner DOE has stated, and notes that no regulatory use

! should be derived from its inclusion in the definitions provided in Appendix A of draft NUREG-1046. To avoid further ambiguity and confusion in this matter the definition of the term " capillary fringe" will be deleted from the final

t. NUREG-1046 report.

Comment No. 25: B. Blanchard,.U.S. Department of the Interior (13)

Section 60.122(b)(8)(ii): "A water table sufficiently below the underground facility such that fully saturated voids continuous with the water table do not encounter the underground facility." This condition has also been improved j over the earlier version, which depended on a rather inappropriate definition of " capillary fringe." However, it still appears to be incumbent on the appli-i cant to prove that there are no continuous paths of water occupying saturated l pores--an impossible task. We suggest changing the favorable condition to read 1

as follows:

"(ii) Conditions that preclude, or limit, capillary rise from -the water

, table to the underground facility;"

4 This directly addresses the concerns expressed by the NRC staff regarding siting a facility in the. capillary fringe but avoids definition of'the term

" capillary fringe."

l Staff Response to Comment No. 25:

The staff can discern no advantage in adopting the suggested wording because the capillary rise would, in many cases, also be difficult to determine.

{

12/04/84 26 Enclosure D i

,v.--~r-- - . - ww--,--,- , - - - - - , - - - , - - - - -,s- ,,,w. - , - - - - - -,- -- en,,

Further, the suggested wording would preclude the consideration of downward moving groundwater. See also staff response to Comment No. 24.

COMMENTS ON PROPOSED 60.122(b)(8)(iii)

Commant No. 26: R. R. Loux and C. A. Johnson, State of Nevada Nuclear Waste Project Office (8)

The NRC stated conditions favorable for an unsaturated zone repository are based on the current level of knowledge of the various transport processes that may operate in unsaturated zones. This level of knowledge is still quite

. limited. One condition in particular, Item 8111 (FR5937), seems more specu-

, lative than others. An overlying low permeability hydrogeologic unit which prevents or impedes downward moving moisture may likewise impede upward moving water vapor. If radionuclides are present in upward moving water vapor driven by strong thermal gradients created by the waste, such water vapor may be forced to move laterally below the hydrogeologic unit until it-condenses. The condensed water vapor, if concentrated in a localized zone of permeability,

, might have the opportunity to flow as perched water to. points of discharge at land surface. Considerable uncertainty exists in terms of radionuclide migration with water vapor, but the above scenario suggests that the low permeability hydrogeologic unit could act to concentrate moisture with radio-nuclides, and permit discharge of this moisture if the hydrogeologic unit intersects land surface in the vicinity of the repository. Therefore, it is not clear that the low permeability hydrogeologic unit would be generally favorable if radionuclides migrate with water vapor driven from the repository i

zone.

Staff Response to Comment No. 26:

The commenter has interpreted the favorable condition in question as a local condition, while NRC's intent was to consider regional hydrogeologic conditions. The staff also notes that conditions which preclude water movement would not necessarily preclude vapor movement. See also staff. response to Comment No. 31.

Comment No. 27: M. J. Lawrence, U.S. Department of Energy (9)

DOE recommends that this section be revised to read "A hydrogeologic condition above the host rock that would inhibit the downward movement of water, divert downward moving water to a location beyond the limits of the underground

~

facility, or divert a significant portion of downward moving water, including that produced by sporadic, intense recharge events, away from the location of waste emplacement."

12/04/84 27 Enclosure D

This rewording addresses the DOE concern that.hydrogeologic conditions other than a low permeability unit, such as a contrast in permeabilities in adjacent hydrogeologic units sufficient to create a capillary break, may result in the desired effect. In addition, the rewording recognizes the favorable effect of vertical flow conduits, even within the boundaries of the underground facility, in diverting water away from the emplaced wastes.

The ability of a hydrogeologic condition, such as a-capillary break, to inhibit water movement (or radionuclide transport) supports the previously recommended revision to the term " barrier." '

Staff Response to Comment No. 27:

The staff considers the wording proposed by DOE to be overly vague and declines to make the suggested change.

Comment No. 28: B. Blanchard, U.S. Department of the Interior (13) ,

Section 60.122(b)(8)(iv): " A host rock that provides for free drainage; or

... " We suggest that "or" should be changed to "and."

Staff Response to Comment No. 28:

The NRC staff declines to make the suggested change since it may prove extremely difficult, if not impossible, for one site to be characterized simultaneously by all five hydrogeologic conditions set forth in 60.122(b)(8).

l The staff considers that the presence of any one of these five hydrogeologic conditions will constitute a favorable siting criteria for unsaturated sites.

Comment No. 29: B. Blanchard, U.S. Department of the Interior (13)

Section 60.122(b)(8)(v): "A climatic regime in which the average annual historic precipitation is a small percentage of the average annual potential evapotranspiration." The term "small percentage" is vague and inappropriate, in our opinion. We suggest specifying an absolute value of average recharge as a maximum, perhaps on the order of 50mm or less.

Staff Response to Comment No. 29:

The qualitative phrase "small percentage" is used in this provision be:ause the average annual historic precipitation and potential evapotranspiration will vary from site to site. Therefore, the staff does not consider a generic quantitative parameter appropriate in this instance.

12/04/84 28 Enclosure D

COMMENTS ON PROPOSED 60.122(c)(23)

Comment No. 30: M. J. Lawrence, U.S. Department of Energy (9)

DOE recommends rewording this section to clarify its meaning as follows:

" Potential for existing or future perched water bodies that may saturate portions of an underground facility or provide a faster flow path from an 1 underground facility to the accessible environment."

Staff Response to Comment No. 30:

The suggested change has been adopted in the final rule.

t j Comment No. 31: A. Hirsch, Environmental Protection Agency (11)

The Commission proposes to amend Section 60.122 by adding new paragraphs (b)(8) and (c)(23). There seems to be a conflict in.the criteria outlined under

. portions of the two respective paragraphs. Paragraph (b)(8)(iii) requires that hydrogeologic conditions in the unsaturated zone' provide for "a laterally extensive, low permeabiltiy unit above" the repository to inhibit downward migration of water into the underground facility. Paragraph (c)(23) presumably calls for the unsaturated zone to be free of the potential for " perched water bodies that may have the effect of saturating portions of the underground facility." It seems that these are in conflict because the laterally extensive, low permeability unit encouraged to be located above the repository as outlined in paragraph (b)(8) increases the potential for the formation of perched water bodies immediately above the unit. Although the low permeability strata may serve to inhibit downward migration, it encourages the possibility of perched water bodies that may result in saturated flow conditions above and

, immediately surrounding the limits of the underground repository. Conversely, I paragraph (c)(23) discourages siting in areas where the potential for existing i

or future perched conditions exists. EPA recommends that this inconsistency be resolved.

I Staff Response to Comment No. 31:

The comaenter has incorrectly identified 60.12N b)(8)(iii) as a requirement, l rather than as a favorable condition. The staff notes that the two provisions in question are not necessarily mutually exclusive. Further, only perched water bodies that may saturate portions of the underground facility or provide a faster flow path from an underground facility in the unsaturated zone to the

. accessible environment would be considered as potentially adverse under

$60.122(c)(23).

i 12/04/84 29 Enclosure D

i COMENTS ON PROPOSED 60.122(c)(24)

Comment No. 32: J. K. Bates, Argonne National Labs (4) i, Proposed Amendment: Potential for vapor transport of radionuclides from the underground facility located in the unsaturated zone to the accessible environ-ment, as a potentially adverse condition.

This is an ambiguous, and as written, meaningless statement that could, under certain conditions, be applied to any repository site. The detailed

explanation in NUREG-1046, pg. II.b.8 is confusing and does little to address the issues. Several points need to be clarified.

) 1. - What is vapor transport? If it is transport of radionuclides in the vapor

phase, then it is not unique to the unsaturated zone for such transport

! will occur at any site until resaturation occurs. If it is transport of radionuclides in water vapor through rock, then it should nut be identified as a separate transport mode because transport by water vapor meets the NRC definition of groundwater. Also, according to the NRC (NUREG/CR-3206, pg. 118), no soluble contaminants will be transported away '

from the repository by water vapor, making the proposed amendment unclear.

2. Where is the vapor transport occurring and when it is important? Vapor i

phase transport might occur in the repository rock. ,However, before such transport could occur, the contaminants have;to get.to the rock. This

, would involve vapor phase transport of contaminants from the waste

! package, across potentially significant void spaces, to the rock.'

Transport in these two diverse media is likely to involve different processes and should be distinguished since the technical references refer only to transport through rock.

1 It makes little sense to mention vapor phase transport in rock unless the terms and concitions are well defined. It could make sense to identify vapor phase transport from the waste package to the rock as an advantage for the i

unsaturated zone, since it is likely far fewer radionuclides (amount and number) would be transported through the " vapor" (unsaturated repository) than 2

would be transported through liquid (saturated repository). This void space is an additional barrier that impedes the movements of many contaminants.

l Certainly this is an area that deserves further attention by the NRC staff.

i Staff Response to Comment No. 32:

I

The discussion provided by this commenter served to illuminate,several areas of ,

i the NRC's treatment of the issue of vapor phase transport which may have caused some confusion. Most of this confusion appears to surround the use of the term

" vapor transport." To clarify its initial intent NRC has modified 60.122(c)(24)

I by deleting the reference to vapor transport. This provision now reads i

12/04/84 30 Enclosure D

, 1 l

" potential for the movement of radionuclides in a gaseous state through the air-filled pore spaces of unsaturated geologic media to the accessible environment." This wording modification is also responsive to the commenter's question of where vapor transport is occurring, Further, NRC notes that draft NUREG-1046 is currently being revised in light of public comments received and subsequent changes in the final amendments. The staff anticipates that a clearer discussion of the movement of radionuclides in a gaseous state can now be provided in this document due to results obtained recently from NRC funded research in this field.

With respect to the issue of when vapor transport is important, NRC recognized in draft NUREG-1046 (p. 15) that vapor formation may not be a potentially

' adverse condition, but that vapor transport of radionuclides away from the underground facility potentially could have an adverse effect on the integrity of the geologic repository. The staff stated that it would like the

), opportunity to evaluate whether or not vapor transport could adversely affect the repository system, i.e. to evaluate the importance of vapor transport at a particular site. Therefore, the question of how important vapor phase transport would be is one issue that NRC expects would be answered during a site review process, when specific parameters such as rock type, backfill design, thermal loading, waste form, etc. can be used to better delimit the potential for transport of radionuclides in a gaseous state.

With respect to the commenter's final point, NRC agrees that vapor phase transport across various barriers may need to be considered, and anticipates that future research in this area will result in a better understanding of i

l' 12/04/84 31 Enclosure 0

i

!i vapor phase transport among different types of birriers within a geologic repository system.

Comment No. 33: B. Blanchard, U.S. Department of the Interior (13)

Section 60.122(c)(24): We suggest adding quantitative clarification to this criterion. As currently worded, it allows no potential vapor phase transport of radionuclides by molecular diffusion or perhaps by convective transport.

Although these fluxes might be miniscule, they would not be zero at any unsaturated site. Therefore, if this criterion is ever considered as a disqualifying factor it will need qualification as regards release rate of nuclides such as 129[ gnd 14C. Related to this question is the. interpretation

! of the boundary for the accessible environment., It is not clear to us from the definition in 10 CFR 60 whether the " accessible environment" includes the airspace immediately above the ground surface directly over the repository or only the atmosphere beyond the boundary.

Differences in these two interpretations could have major impacts on how the vapor transport criterion is tested.

Staff Response to Comment No. 33:

The staff considers it inappropriate at present to add a quantitative statement to the provisions of 60.122(c)(24) because the movement of radionuclides in a i

gaseous state is, to a large extent, dependent upon site- and design-specific parameters. NRC would like the opportunity to examine the potential movement of radionuclides in a gaseous state away from the geologic repository to determine i

if the isolation capability of the geologic setting may be compromised. With respect to the comment on the accessible environment, item (1) of the definition

set forth in 60.2 lists "the atmosphere" as part of the accessible environment

, (48 FR 28217). This would include the airspace directly over the repository.

Comment No. 34: A. N. Turcan, Jr. , Capital Area Groundwater Conservation Commission (14)

There is a discussion of vapor transport in the rules and the need for  ;

consideration on a case by case basis of the problem in the Rules Section,

, " Issues examined by the Commission." Hopefully, the Commission's conclusion is satisfactory or is more in-depth caution required?

12/04/84 32 Enclosure D

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Staff Response to Comment No. 34:

The discussion referred to by the commenter (48 FR 5935) served to raise the issue of vapor transport to public attention at an early stage so that further thought .nay be given to the associated positive aspects and potential concerns.

It l's recognized that more detailed information will be necessary to enable NRC to evaluate the importance of transport of radionuclides in a gaseous state through unsaturated geologic media especially during the licensing review process. To that end, NRC is currently sponsoring research in vapor phase transport in unsaturated fractured rocks.

THE FOLLOWING NEW SITING CRITERIA WERE SUGGESTED BY COMMENTERS ,

Comment No. 35: R. R. Loux and C. A. Johnson, State of Nevada Nuclesr Waste Project Office (8)

Two additional favorable conditions are suggested for NRC's consideration:

1. Thermal characteristics of the hydrogeologic unit, such that exposure to high temperature gradients would not cause compaction or volume changes in the packaging or surrounding media.

If compaction should occur, it could influence the hydraulic conductivity in a negative sense, as well as influence the structural stability of the area around the cannisters. Compaction due to high thermal gradients is suggested in studies by Constantz.*

2. Host rock that is capable of accelerated drying.

Due to temperatures reached in the near field, vapor transport in the unsaturated zone is initiated shortly after waste emplacement. This vapor phase moves outward towards cooler regions where it condenses. The condensed water then moves back towards the cannisters. This sets up a circulation system which is dominated by the vapor phase; that is, the water phase is small compared to the vapor phase. Prolonged circulation tends to reduce the total amount of water in the area surrounding the cannisters because more and more vapor is lost to the surrounding system. Eventually there is no water left as either vapor or condensate; in short, the host medium becomes dry. Therefore, a host rock which encourages this type of behavior to occur before the cannisters begin to deteriorate (and leak) is advantageous. However, accelerated drying after the cannisters begin to deteriorate (and leak) may be "Constantz, Jim, 1983, " Laboratory Analysis of Water Retention in Unsaturated Zone Materials at High Temperature, in The Role of the Unsaturated Zone in Radioactive and Hazardous Waste Disposal, eds. J.W. Mercer, P.S. Rao, I.W.

Marine, Ann Arbor Sciences, 1983, Ann Arbor, Michigan.

12/04/84 33 Enclosure 0 i

a disadvantage to long-term isolation and requires further analysis. This drying behavior is described in work by Pollock.**

An additional comment on conditions for disposal in the unsaturated zone concerns hydrogeochemical considerations. For the saturated zone 10 CFR Part 60 [60.122(c)(9)] identifies a non-reducing environment as an adverse condition. It is probable that the unsaturated zone is an oxidizing environ-ment. An additional condition addressing hydrogeochemical conditions in the unsaturated zone is necessary.

Staff Response to Comment No. 34:

The staff notes that both conditions proposed by the commenter could be either favorable or potentially adverse conditions, depending on the site selected.

These phenomena are not conclusive,'and therefore, the staff has not adopted the suggested wording.

With respect to the commenter's final point, the staff notes that in the final amen'ments, d the qualifying phrase "for disposal in the saturated zone" has been deleted from $60.122(c)(9). This change should ensure that this provision will be equally applicable to geochemical conditions in both the saturated and unsaturated zones.

THE FOLLOWING' PROPOSED REVISIONS TO EXISTING PROVISIONS OF 10 CFR PART 60 WERE SUGGESTED BY THE COMMENTERS Comment No. 36: M. J. Lawrence, U.S. Department of Energy (9) 860.2, Definition of Disturbed Zone With incorporation of the unsaturated zone provisions into 10 CFR Part 60, DOE believes the definition of disturbed zone should be reconsidered. DOE believes the disturbed zone should not include the volume of rock in which changes will occur which will improve the isolation capability of the repository. For example, the Supplementary Information and NUREG-1046 indicate there may be the creation of a drying zone extending hundreds of meters from a repository located in the unsaturated zone. This drying zone (and the accompanying increase in degree of saturation at some farther distance) will create a hydraulic gradient in all directions toward the repository - a favorable condition which will exist throughout the temperature pulse. 00E recommends

""Pc11ock, David Warren, 1982, " Fluid Flow and Energy Transport in a High-Level Waste Repository in Unsaturated Alluvium", Ph.D. Thesis, University of Illinois - Urbana, Champaign, Illinois.

12/04/84 34 Enclosure D

that the NRC revise the definition of the term " disturbed zone" to apply to that volume of rock in which changes will occur which will have a significant adverse effect on the performance of the repository.

Staff Response to Coment No. 36:

The " disturbed zone" concept is currently under review by the NRC staff, and the commenter's cohcerns will be considered during this review.

Comment'No. 37: M. J. Lawrence, U.S. Departicent of Energy (9) 560.2, Definition of Barrier DOE recommends revising the definition to mean any material, structure, or condition that prevents, or substantially delays, movement of water or radio-nuclides. The basis for this recomendation is discussed in the coment on Section 60.122(b)(8)(iii).

Staff Response to Coment No. 37:

See response to Comment No. 27.

Coment No. 38: M. J. Lawrence, U.S. Department of Energy (9)

~

860.122(b)(2)(fii)

The phrase " low hydraulic potential" should be revised to either " low hydraulic gradient" or "small difference of hydraulic potential" to be hydraulically correct.

Staff Response to Coment No. 38:

The phrase " low hydraulic potential" has been replaced by the phrase " low hydraulic gradient" in the final amendments.

Comment No. 39: B. Blanchard,'U.S. Department of the Interior (13)

Section 60.122(b)(2)(iii): To be hydraulically correct, the phrase " low hydraulic potential between" should be " low hydraulic gradient between" or "small difference of hydraulic potential between." This concept is also applicable to the unsaturated zone and is implicit in the wording " Low . . .

moisture flux in the host rock . . ."

Staff Response to Comment No. 39:

See response to Comment No. 38.

l 12/04/84 35 Enclosure D l

b Comment No. 40: M. J. Lawrence, U.S. Department of. Energy (9) 560.122(b)(5)

DOE believes that, although a minimum depth of 300 meters for waste emplacement is a favorable condition, the application of this favorable condition to the unsaturated zone is non-conservative in that it ignores the greater benefit to 1

isolation derived from maximizing the thickness of the unsaturated zone between the underground facility and the water table. Instead, it supports the concept of "the deeper, the better" (see page 19 of NUREG-1046) without consideration of the lesser likelihood of exhumation by erosion, the lesser likelihood of intrusion by deep water well drilling in isolated arid environments, or the advantages of maximizing the thickness of the unsaturated zone between the underground facility and the water table. To achieve a meaningful balance between favorable conditions for the unsaturated and saturated zones, DOE recommends adoption of a favorable condition for the unsaturated zone that acknowledges the favorability of a substantial distance between the underground facility and the water table. Adoption of such favorable condition is consistent with NRC concerns in Section 60.122(b)(8)(ii) and 60.122(c)(22).

4 Staff Response to Comment No. 40:

The staff has not adopted the suggested change because it could result in an 1

underground facility being situated close to the land surface, and hence, close to the accessible environment. The staff does not understand the reasoning behind this suggestion since the staff considers the provisions of 60.122(b)(8)(ii) already accommodate DOE's concerns related to distance between

the underground facility and the water. table.

Comment No. 41: A. N. Turcan, Jr. Capital Area Groundwater Conservation

Commission (14)

The requirement of a minimum depth of 300 meters may minimize to some degree ,

the effects of climatic changes. But there should be a required minimum pre-determined interval between the top of the water. table and the bottom of burial

, depth to prevent water entering the repository.

Staff Response to Comment No. 41:

See staff response to Comment No. 40.

Comment No. 42: M. J. Lawrence, U.S. Department of Energy (9)

$60.133(f) l l

~12/04/84 36 Enclosure D l

This section, now applicable to disposal in either the unsaturated or saturated zone, on rock excavation design criteria states that the. potential for creating a preferential ground-water pathway must be limited. However, in the unsaturated zone, a preferential ground-water pathway may be preferred in order to have a freely draining host rock as contained in the proposed Section 60.122(b)(8)(iv). 00E recommends revising this section to "The design of the underground facility shall incorporate excavation methods that will limit the potential for creating pathways that could compromise the ability of the repository to meet the perfor,mance objectives," to allow internal consistency in the technical rule for the unsaturated zone. This recommended change is consistent with the wording contained in Section 60.133(a).

Staff Response to-Comment No. 42:

The provisions of $60.133(f) have been modified to reflect the fact that it is groundwater contact with the waste packages that is of primary concern. Also, the phrase " radioactive waste migration" has been replaced by "for radionuclide migration" for the sake of clarity. These changes should be responsive to DOE's concerns in this matter.

Comment No. 43: M. J. Lawrence, U.S. Department of Energy (9)

S60.134(b)

As in the preceding ccmment, 00E believes that in the unsaturated zone, it may be beneficial to " seal" boreholes and shafts so as to create a preferential pathway for ground water along at least part of the length of the borehole or shaft. For example, it may be desirable to have a preferential pathway for ground water from an overlying unit where the groundwater may tend to perch naturally, to an underlying unit or completely through the repository horizon (but not in areas of emplaced wastes) to an underlying permeable zone. DOE believes the unsaturated zone offers some interesting opportunities for innovative methods and materials for backfilling and sealing, as noted by G. Roseboom in USGS Circular 903.

00E recommends either revising Section 60.134(b) to be applicable to only the saturated zone, or rewording it to read " Materials and placement methods for seals shall be selected to reduce, to the extent practicable, the potential for creating pathways- that compromise the ability of the repository to meet the performance objectives." This recommended change is consistent with the wording contained in Section 60.134(a).

Staff Response to Comment No. 43:

The provisions of S60.134(b)(1) now refer to creating a preferential pathway for groundwater to contact the waste packages. The wording of 960.134(b)(2) i 12/04/84 37 Enclosure D

has been clarified by referring to radionuclide migration instead of to radio-active waste migration.

Comment No. 44: M. J. Lawrence, U.S. Department of Energy (9)

$60.141(c) ,

Severaloftheminimummeasurementsreqbiredinthissection,particularly

, changes in ground-water conditions and rock pore-water pressures (including those along fractures and joints) may be unnecessary, of limited use, or 4

difficult to measure in the unsaturated zone, especially given the creation of

a drying zone which may reduce moisture contents so low or create such high i negative pressures as to exceed the range of measurement for available instru-

! mentation. DOE recommends revising Section 60.141 to replace the term "as a j minimum" with the term "where practicable." This recommended change is j

consistent with the wording already contained in Section 60.140.

} Staff Response to Comment No. 44:

The NRC staff considers it reasonable for the applicant to monitor ,

perturbations in the hydrologic regiae induced by the construction and i operation of a geologic repository. -In the event that a given measurement is ,-

1 .

technologically unfeasible, the applicant will need to rely on indirect methods to assure compliance with.this section. Therefore, no change has been made to the provisions of $60.141(c).

t Comment No. 45: B. Blanchard, U.S. Department of the Interior (13) i Section 60.122(b)(2)(iv): We endorse extracting this as 60.122(b)(7), as

! proposed, and adding the statement suggested above to make it clear that the j travel time in the unsaturated zone should be creditable.

l DEFINITIONS

~

" Accessible environment." We strongly suggest that aquifers be incorporated in  ;

this definition. '

I- Staff Response to Comment No. 45:

i With respect to the commenter's first point, see staff response to Comment No. 20. On the issue of incorporating aquifers into the definition of the term " accessible environment" the staff notes that aquifers located outside l

l 12/04/84 -38 Enclosure ~D

the controlled area would be included under item 5 of the definition of accessible environment set forth at 48 FR 28217. Item 5 identifies "the portion of the lithosphere that is outside the controlled area" as part of this definition.

COMMENTS ON ORAFT NUREG-1046 In conjunction with the proposed amendments, NRC also published for public comment draft NUREG-1046 which presented an examination of the issues considered by NRC during the development of the proposed amendments. The following comments explicitly addressed draft NUREG-1046. NRC has considered these comments during its efforts to revise the NUREG document, and finds most of the comments to be technically valid. The NRC staff would note that the apparent reliance on NUREG/CR-3158 referred to by one of the commenters was due to the fact that few detailed studies of deep, unsat.urated hard rock existed at the time NUREG-1046 was drafted. There was no intent on the part of the staff to relate this document to any specific site currently under consideration by 00E. Rather, the staff hoped to provide a generic study, based upon existing scientific publications, of the pertinent issues that the Commission might wish to consider in reaching a decision on whether or not to expand the scope of 10 CFR Part 60 to include HLW disposal within the unsaturated zone.

Comment No. 46: R. E. Williams, Williams & Associates, Inc. (3)

This report explains the differences between saturated and unsaturated zones in a clear and concise manner. Comments are presented by page number as follows.

Page 3 - Defining groundwater as the entire volume of water below the earth's surface is a somewhat unusual but very appropriate approach.

Page 4 - Paragraphs 2 and 4 relate to movement due to gravity in the unsaturated zone. However, at the high moisture tensions that occur in arid regions with a deep water table the movement may be vertically upward due to evaporation at the surface. Soil moisture does not necessarily ultimately percolate downward in arid environments.

Page 5 - Top of page - In our opinion the flow into fractured granite would be considerably different than fractured tuff. In some types of tuff, water in the fractures would be " absorbed" into the adjacent ,

intergranular pores. This would not occur in granite because it is-12/04/84 39 Enclosure D

less porous. Therefore, downward movement may not be as rapid in tuff because the fractures would dewater due'to water moving out into the pores. These ideas should be investigated either in the laboratory or in the field as discussed at the bottom of page 6 and top of page 7.

I Pages 7 and 8 - These pages present a good discussion of heat flow from the repository and the formation of,a " vapor envelope" around the repository.

Page 10 - Paragraph 4 - The authors point out that under unsaturated flow conditions the liquid flow occurs only on the surface of mineral i particles wherefore the removal of radionuclides is more likely than at saturated flow conditions. However, according to the heat, liquid ,

and vapor flow analysis, the flow away from the repository is in the form of vapor while the flow toward the repository is in the form of liquid on the particle surfaces. The radionuclides therefore would have to be in the vapor phase, not in the liquid phase.

Pages 14 and 15 -' Vapor and gaseous transport of contaminants.- The discussion of the transport is good but it would be advisable to conduct addi-tional research on this topic by means of physical model that could be used to verify the mathematical model developed at Arizona. A 4

complete analysis of the " vapor envelope" might show that there is no movement of either liquid or vapor from the envelope to the surrounding material. An energy balance of this phenomenon would have the hea.t produced at the repository constitute the energy source for the recirculating flow of vapor away from the repository and flow '

of liquid toward the repository.

Pages 20 and 21 - We agree with the discussion on shafts, boreholes and backfill regarding design. Specifically the proper design may be the opposite of the proper design for such structures under saturated flow conditions.

Comment No 47: D. W. Moos, Department of Ecology, State of Washington (12)

We are fully in agreement with the proposed amendments to 10 CFR 60 which accommodate candidate repository sites in the unsaturated zone.

However, it is apparent that the main body of reasoning and examples covered in the draft applies to the Nevada Test Site. The principal technical reference, in fact, is NUREG/CR-3158, which contains in its title the phrase, " Emphasis on the Nevada Test Site."

We have never been fully satisifed with the pre-NWPA siting decision process which led the U.S. Department of Energy to put its Hanford Reference Repository Location deep in the saturated zone, stratigraphically close to aquifers of great economic importance. As the principal water management agency for a i

state where future water quality and availability are sensitive, highly-charged issues, we are deeply concerned with any risk'of contamination, no. matter how slight.

12/04/84 40 Enclosure D

l The proposed amendments can be interpreted as a signal that the Nuclear Regula-tory Commission,-like the state of Washington, wants to see all reasonable alternatives examined and, where indicated, re-examine before final commitment to a deep, difficult site such as the Hanford location in the saturated zone.

b I

i i

12/04/84 41 Enclosure D l

m~ w , ww 9 a O

e APPENDIX A .

March 6, 1984 Secretary of the Conunission .r;C/li W.T3D

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U.S. Nuclear Regulatory Commission Washington, DC 20555 @* ~ p,_i.' ggge;gia~ _

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84 KAR 12 P1:38  !

RE: 10 CTR Part 60, Disposal of High-Level Radioactive Wastes in the Unsaturated zone,, Proposed amendment of rulesggi-gister, V. 49, No. 33 ,

It is extremely important to be aware of the ((ck that " unsaturated" is NOT synonymous with .a low moisture content. The last paragraph beginning on p. 5934 of the Federal Register notice referred to states that "Perhaps the most positive aspect associated with disposal of HLW within the unsaturated zone is that the HLW would be emplaced in a relatively dry (i.e., low moisture content) geologic medium." This implies that all unsaturated rocks are dry. This is patently untrue. Unsaturated merely means that the pore space in the rock is not filled with water. The actual water content depends on the amount of pore space.

Thus a rock that has a porosity of 57 and which is saturated has exactly the same amount of contained water as a rock with a porosity of 107. which is 507 saturated.

In fact, many of the rocks to which the USGS refers to as unsaturated have a very high porosity and a relatively high saturation, although less than 1007.,

and in fact contain much more water than saturated rocks with a lower porosity..

Many volcanic tuffs in the Great Basin, in fact, contain considerably more water than granites in the more humid regions, even though the granites are saturated .

and the tuffs are not. Water content and the speed of the movement are the in-portant factors; the percentage of " saturation" La really an insignificant factor.

With regard to the question of whether or not groundwater travel time represents an appropriate measure of performance for a site within the unsaturated zone, I feel that it.is absolutely essential that the same standard of measure be applied to all rock types and all sites, regardless .of their setting with respect to the water table. I have no idea how groundwater travel time in the unsaturated zone can be deter =ined; neither do I have any idea how groundwater travel time through salt can be measured. Maximum likely volumetric flow rate of groundwater through the repository might well be a more appropriate measure of performance, but sites.

if so, then this same measure should be applied to all rock types and all It would be absolutely unacceptable to use the alternative performance measure fer a rock situated in the unsaturated zone (even though containing a considerable amount of water and, in fact, possibly be "near" saturation) and apply a different measure for a site in a salt host rock, which in fact contains an amount of water almost defying measurement and with a " groundwater travel time" (if that term can even be applied) that is so slow as to be beyond comprehension.

Thank you for the opportunity to comment.

Sincerely, A

Benjamin Dover .

Geologist 657 Indian Mound Road Columbus, Ohio 43213

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Re: Fed Reg Notice - Feb 16-84 BRANCH HLW Disposal Gentlemen -

The' discussion in this notice limits itself to waste burial in sa.turated ar.d unsaturated f zones. -

Has the Commission given any consideration to above-ground repositories for HDi? Over .

the past few years, this approach nas been *-

written about, a number o1 times. .

Should HLW be entombed in tais manner, and if the contaimment were in the snape of a pyramid,* it miE ht withstand earthquakes, tornacoes and concussion from bomb blasts. ,

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Ackraetkdpd b/ end. 3- m, 14 . crec.ny

WILLIAMS & ASSOCIATES,INC.

P.O. Box 48. Viola. Idaho 83872 C08) 883 0153 C08) 875 0147 00u qt- l Hwdroteolggy e Mineral Resources Weste Managemens e Geologural Engineersnt *

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Division of Waste Management -

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Thio letter constitutes the comments of Williams and Associates.

Inc. on NRC NUREG 1046 entitled " Disposal of _High Level Rcdioactive Wastes in the Unsaturated Zone: Technical Conoiderations". As you pointed out in your note, the NUREG is a draft repcet for comment. We are directing these comments to you with the anticipation that you will transfer them to Tom Nicholson. The primary review of the report was done by Dr.

George Bl oomsburg . I have added some comments of my own and cdited his. The comments are as follows.

Thic report explains the differences between saturated and uncoturated =enes in a clear and concise manner. Comments are l procented by page number as follows.

I i

Pcgo 3 - Defining groundwater as the entire volume of water below the earth's surface is a somewhat unusual but very appropriate approach.

'Pego 4 - Paragraphs 2 and 4 relate to movement due to gravity in the unsaturated zone.. However, at the high moi sture tensions that occur in arid regions with a deep water table the movement may be vertically upward due to evaporation at the surface. Soil moisture does not necessarily ultimately percolate downward in arid environments. .

Pcgo 5 - Top of page - In our opinion the flow into fractured granite would be considerably different than fractured tuff. In some types of tuff, water in the fractures would be " absorbed" .into the adjacent intergranular pores. This would not occur in granite because it is less porous. Therefore, downward movement may not be as

- - L ; . > k Qk

1 2 i rapid in tuff because the fractures would dewater due to  !

water moving out into the pores. . These ideas should be l

investigated either in the laboratory or in the field as '

discussed at the bottom of page 6 and top of page 7. ]

.Pages 7 and 8 --

These pages present a good discussion of heat I flow from the repository and the formation of a " vapor

)

envelope" around the repository.

l Pcge 10 - Paragraph 4 -

The authors point out that' under unsaturated flow conditions the liquid flow occurs only on the surface of mineral particles wherefore the removal of radionuclides is more likely than at saturated flow cm,nditions. However, according to tne heat, liquid and vapor flow analysis, the flow away from the reposi tory is in the form of vapor while the flow toward the repository is in the f orm of liquid on the particle surfaces. The radionuclides therefore would have to be in the vapor phase, not in the li quic phase.

Pages 14 and 15 - Vapor and gaseous transport of centaminants -

The discussion of the transport is good but it would be advisable to- conduct additional research on this topic by means of a physical model that could be used to verify the mathematical model developed at Arizona. A complete analysis of the " vapor envelope" might show that there is no movement of either li quid or vapor f rom the envelope to the surrounding material. An energy balance of this phenomenon would have the heat produced at the repository constitute the energy source f or the recirculating flow of vapor away from the repository and flow of li quid toward the respository.

Pages 20 We agree with the discussion on shafts, boreholes and backfi11 regarding design.- Specifically the proper design may be the opposite of the proper design for such structures under saturated flow conditions.

If you have any questions regarding these comments, please call.

Sincerely, 1,4$b eM;g Roy E. Williams ,  ;

Ph.D. Hydrogeology l Registered in Idaho REW:s1 cc: appropriate NRC offices .

M. D. Mifflin

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' ARCONNE NA"ONAL LABORATORY 6WAEJW@ l 9700 Sourk Cass Aeu:. A%owa. llros 60439 . Telepkre 312N2- 4385 March 30, 1984 Secretary of the Commission U.S. Nuclear Regulatory Commission Washington, DC 20555 .. ..

.;jyf-g.ig Attn: Docketing and Service Branch anANcn Sir:

This is geologic unsaturated a comment to proposed NRC amendments to 10 CFR Part 60 concerning media.

(Ref. Federal Register, Vol 49, No. 33, pg 5934. )

Proposed Amendment:  :

Potential for vapor transport of radionuclides from '

the undergr.ound facility located in the unsaturated zone to the accessible environment, as a potentially adverse condition.

This is an ambiguous, and as written, meaningless statement that could, under certain conditions, be a explanation in NUREG-1046, pg.pplied to any repository site. The detailed the issues. Several points need II.b.8. is confusing and does little to address to be clarified.

l vapor 1) What phase is vapor transport? If it is transport of radionuclides in the will occur a,t any site until resaturation occurs.then If it is transportit is not.ofunique radio-to the uns nuclides in water vapor through rock, then it should not be identified as a s2parate of transport mode because transport by water vapor meets the NRC definition groundwater.

Also, according to the NRC (NUREG/CR-3206, pg.118), no soluble contaminants making the proposed will beamendment transported away from the repository by water vapor, unclear.

2) Where is the vapor transport occurring and when it is important?

phase transport might occur in the repository rock. However, before such Vapor transport could occur, the contaminants have to get to the rock. This would involve vapor phase transport of contaminants from the waste package, across patentially significant void spaces, to the rock. Transport in these two diverse media is likely to involve different processes and should be distinguished since tha technical references refer only to transport through rock.

It makes little sense to mention vapor phase tracsport in rock unless the terms and conditions are well defined.

phase transport from the waste package to the rock as an advantage for theIt co would be transported through the " vapor" (unsaturated repository) transported through liquid (saturated repository). This void space is an additional barrier that impedes the movement of many contaminants. Certainly this is an area that deserves further attention by. the NRC staff.

S er 1, n K. hus JKB:rr Cth!mical Technology Division USDepmTd Ewn Tk,t#.asny of Chemo- gg-- -

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G'MPA 69N) 4 RADIOACTIVE WASTEREVIEWBOARD' ' s2s renneysuinng 110E. Main Street

'84 APR 13 P3 ;11 uawson. wi 537o2 (608)266-0597 April 11, 1984

, , ;,,: _ (606) 267-7615

....r .ithG & SERW.f BRANCH Mr. Samuel J. Chilk, Secretary U. S. Nuclear Regulatory Commission Washington, D. C. 20555 Attn: Docketing & Service Branch Re: Comments on the Proposed Rule for Amending 10 CFR Part 60, Disposal of High-Level Radioactive Wastes in the Unsaturated Zone

'~ . .

6 The Wisconsin Radioactive Waste Review Board has reviewed the proposed revisions to 10 CFR 60 for disposal of high-level radioactive wastes -

in the unsaturated zone. This proposed rule appears to have . ._

considerable merit since it opens up another alternati.ve for ' disposal.

It also appears the Commission has identified the yertinent technical -

~

concerns with disposal in the unsaturated zone.'* -

~

Thank you for the opportunity to comment on this' rule.

Sincerely,

& S. & '_ _ -

~

James S. Kleinhans Executive Director cc: Radioactive Waste Review Board Members Technical Advisory Council Members ,,

Policy Advisory Council Members mhd 6.cknowledit3 Ly to:1.4.. .t.yar.. ,me

. /'

tN0eOSED ft"t!_I N -M._) .

~ $ $$$f COCKEitP

5NRC htste of Ehche deland unb prouibence $1 tut n execunvr enAwarn  ;;,rF'er CF SECddTA

'

- PROVCENCE 000HTTING & SERV'CI BRANCH J. JOSEPH GARRAHY GCvtMNon April 13, 1984 Mr. Samuel J. Chilk Secretary of the commission U.S. Nuclear Regulatory Commission Washington, DC 20555

Dear Mr. Chilk:

I am pleased to submit on behalf of the. State of Rhode Island [,

our comments on the commission's proposed rule regarding disposal of high-level radioactive wastes in the unsaturated zone. -

These comments were drafted with the assistance of$ me'mb.ers of~

the Rhode Island Crystalline Rock Project Review Team, which was ,,

formed last year to respond to the Depart 5 tent'of Energy's h,igh- .

level waste repository program. contributors to this effort w5re Mr. Victor Bell, Chief of the Office of Environmental Coordination, R.I. Department of Environmental Management, and Mr. Daniel Varin, i chief of the office of State Planning.

Any questions regarding our comments may be directed to me at (401) 277-3500.

Sincerely, Bruce vild Project Facilitator

'#'Yh4Cd by ::rd. .Y.$. . X. . . .. .

72 Orange St., _

GOVERNOR'S ENERGY OmCE + M. PROVOENCE M 02903 MUM WO , , ,

l COMMENTS BY THE STATEdOF RHODE ISLAND ON THE PROPOSED RULE REGARDING THE DISPOSAL OF HIGH-LEVEL RADIOACTIVE WASTES IN THE UNSATURATED ZONE Most ground water in Rhode Island is drawn from relatively shallow otratified-drift aquifers. Hydrologists in the Division of Land Resources have informed us that in many areas the water table is  !

but a few meters below the surface. While some wells tap water ,

which collects in rock ' fractures, such water also is found rela-tively close to the surface. According to our Water Resources ,

Board, only a half-dozen or so water supply walls go below 500 feet  !

(150 meters) . This suggests a thin unsaturated zone. It is ,

extremely unlikely, then, based on present evidence, that the Department of Energy could locate a nuclear wasta repository in 4 the unsaturated zone in Rhode Island and be able to satisfy its

.own minimum depth requirement of 200 meters (DOE siting guidelines, -

Sec. 960.4-2-5 (d) ) . On the other hand, as indicated in the pro-posed rule, unsaturated zones in other areas, particularly those found in arid or semi-arid regions of the country, may be of ,suf-ficient thickness to allow the minimqm . depth requirement to- 1pe met.

Regardlass of whether a site is chosen within the saturated zone' cr the unsaturated zone, our primary congern.over:the long term

. accessiblej en-chould be the vironment. isolation Disposal in of nuclear the wastez.one.

unsaturated from the'_he has t advantage of minimizing contact between the implanted waste and gro'und water.. ,

1 As ground water is the most likely pathway for radionucli' des to the outside, Rhode Island.would support considering such-an option for disposal.. We have stated on a number of occasions, particularly in regard to DOE's-siting' guidelines, that the repository should not contaminate ground water of potential use by present or future generations. The relative dryness of a thick unsaturated zone would help reduce the probability that contaminated ground water would

reach Man.

, However, ground water does flow in the unsaturated zone, and to

! demonstrate that its repository complies with stated performance objectives, the Department of Energy will have to assess ground water flow in both liquid and vapor phases. Ground water travel

time in the unsaturated zone.will be difficult to calculate, as the proposed rule indicates, because of "large associated uncer- l tainties." Some quantification and generalization concerning ground water travel time will.be .necessary nonetheless to determine I

if proposed "potentially adverse conditions" (c) (22) and (c) (23) are present (49 FR 5937) . Absent another parameter upon which to evaluate performance, DOE will have to attempt a " reasonable" i estimate of ground water travel time to'be corroborated to the L .. . . .- -- - - . -_. .. . -.

COMMENTS Page Two extent possible when the Department characterizes the candidata site. As there may be much debate over which level of data is.

" reasonable" in the earlier stages of screening, Rhode Island would urge DOE and NRC to consult freely with the state geological contacts on this matter.

In its consideration of ground water flow (however that parameter

~

is to be determined), we would recommend that NRC direct DOE to examine how the rate and direction of ground water flow is affected by withdrawal. Rhode Island's experience indicates that changes do occur in shallow aquifers and in some cases these changes are sig-nificant.. This would appear to be a matter of concern in any case where ground water flow is discontinuous and heavily dependent on spatial. and temporal events, as in the unsaturated zone.

j Y

y

JOHN J. KEARNEY. Senior %ce Present EDISON ELECTRIC oW I N S TI T U T E ** *** "" " ' """ ""'"'

1111 19tn Street. N.W.

Wasnington, D.C. 20036 84 APR 16 P155 D (202)e2sm April 13,.1984.:.u IiGO.GiihGTj& S Wi.

BRANCH Secretary of the Commission U.S. Nuclear Regulatory Commission C-

" O R .,

Washington, D.C. 20555 (,:. K i B W 8

Attention: Docketing and Service Branch Re: Proposed Rule: Disposal of High-Level Radioactive Wastes in the Unsaturated Zoner 10 CFR Part 60 (49 Fed. Reg. 5934)

Dear Mr. Secretary:

These comments are being submitted by the Edison Electric Institute (EEI) and the Utility Nuclear Waste Management Group (UNWMG) in response to the above-referenced notice.. We support amendment of the Commission's regulatidni in 10 CfR Part '60 so that the technical criteria for geologic -dispos.11 in .the 6 '

saturated zone may be equally applicable to disposal within the unsaturated zoned.

In particular, we support adoption of tlg specific amendments presented in the Commission's notice as.

appropriate for providing for such disposal -with one exception.

Proposed 560.122 (b) (7) would apply to disposal in both the ,

saturated and unsaturated zones. As indicated in the rulemaking notice, .however, determining groundwater travel time in the unsaturated zone may not be necessary nor always be possible.

Under such circumstances, inability to demonstrate a " groundwater travel time along the fastest path of likely radionuclide travel from the disturbed zone to the accessible environment that substantially exceeds 1,000 years" should not amount to.the absence of a favorable condition. This is especially so in a case where the conditions prescribed in proposed S60.122 (b) (8) cxist. Accordingly, the groundwater travel time identified as a favorable condition in proposed S60.122 (b) (7) should not apply to disposal in the unsaturated zone.

To . further amplify our position, we offer the following answers to the two questions presented in the Commission's notice.

1. 'How can groundwater travel time in the unsaturated zone be determined with reasonable assurance? Should the -

groundwater travel time performance objective be limited to groundwater movement within the saturated zone?

~ '

-:.: u'L.. ~ . 1.1 ,(e e a

.-- . . . . _ . . . - . _ _ _ = _ . .-

. . i Sacrotory of the Commicsion April 13, 1984 Paga Two )

l EEI/UNWMG are not aware of any general, acceptable method for determining groundwater travel time in the unsaturated zone with reasonable assurance. However, there is no reason to strictly limit the groundwater travel time performance objective to groundwater movement within the saturated zone. We agree with the Commission's current thinking.on this issue, as described in ,

the rulemaking notice, that if DOE can demonstrate in a particular case with reasonable assurance that travel time for groundwater movement through the unsaturated zone can be quantified, then the Department should.be allowed to include such travel time when demonstrating compliance with 10 CFR 560.113 (a) (2) .

2. Does groundwater travel time represent an appropriate measure of performance for a site within the unsaturated zone, or would an alternative performance objective for the geologic setting, (e.g., maximum likely volumetric flow rate of groundwater through the geologic repository) be more appropriate?

EEI/UNWMG believe that groundwater travel time can , - in certain circumstances, represent an- spFropriate ' measure of' -

performance for a site within the unsaturated zone. 'Where is does not, however, we do not belieVe that an alternative performance objective, such as maximum 1,ikely volumetric flgw rate,'would necessarily be more appropriate. Rather, consistment with one of the alternatives posed by the -Commission in the rulemaking notice, we would favor utili.za,tiicn of the approach ~ set _

forth in 10 CFR 560.113 (b) providing the Commission with the' basis to specify variations in performance objectives on a case-by-case basis, as long as the overall system performance objective I is met. In this connection, the Commission should specifically note in the statement of considerations accompanying the adoption of a final rule that the approach in section 60.113 (b) may be particularly appropriate in the case of disposal in the unsatu-rated zone.

We appreciate this opportunity to comment on the proposed rule and hope that this response will be of assistance to the Commission. ,

Respectfully submitted, ed J hn J. earney enior Vice Preside t -

JJK:rsd L

?sc0AA H mRYAN STATE OF NEVADA 000KET ttU:.'gEH p3ggpg3[g gg'g ,

) -

. 1 -

• • " (49FA 59%)

' i 50CX(,TED

. !%nC NUCLEAR WASTE PROJECT OFFICE omcz or me sovraaon _.

Capitol Coinpies Carson City, Nevada 89710

,.},./.-[*hyjy.h ,

SRANCH (702) 885 3744 April 13, 1984 Socretary of the Commission U. S. Nuclear Regulatory Commission Washington, D.C.' 29555 Attention: Docketing and Service Branch .

SUBJECT:

16 CFR Part 68 - Proposed Rule on Disposal in _,

the Unsaturated Zone -

" ~ ~ ~

Daar Mr. Secretary:

The ' February 16, 1984, Federal Register Notic_e (Vol. 49,. 3o. 33, FR 5934 to FR 5937) requested comment on.16 CFR Part- 60 -

Proposed Rule for Disposal of High-Level ,Radi^o. active Westes in the Unsaturated Zone. The State of Nevada has reviewed the ~ _

proposed rule and support documents identified in the subject notice. We are satisfied with the intent of the proposed rule and feel it is in line with the State's thinking on disposal in the unsaturated zone. However, we have some comments and suggested changes to -improve the- proposed rule.

68.2 DEFINITIONS Groundwater:

R defining " groundwater" (gro und water) for a regulatory purpose, particularly will in view of_the fact that the scientific community make the field and laboratory determination, is not dosirable. It would be much better for NRC to define and adopt a term or phrase that does not already have a precise meaning in technical community and literature, such as " subsurface moisture." "Gro und wate r" already has a widely accepted meaning which does not include vadose or unsaturated zone water.

Uncaturated Zone:

This is a questionable ~ definition because " deepest water table" han been used. The definition is taken from Lohman et al.

1973 , but is not, to our widely accepted. In some terrain and, climates it may lead of saturat:,on.

knowledg to [iclusion of extensive areas The following is a more satisfactory definition

- _. . . - . .-_ -- - -. w & ..

l .ecretary of the Commission April 13, 1984 Page Two for the unsaturated zone:

"The unsaturated zone is that region of the earth materials between landsurf ace and regionally saturated earth materials.

There is. discontinuous and incomplete saturation of the interconnected voids in the earth materials, and therefore no continuous positive hydraulic continuity with the regionally caturated zone. Perched zones (zones with void saturation and local positive potential and hydraulic continuity) may be present within the unsaturated zone."

This follows O.E. M e i n = e r's intent in definition, and incorporates local but not regionally perched water.

68.122 SITING CRITERIA The'NRC stated conditions favorable for an unsaturated zone repository are based on the current level of knowledge of the various transport processes that may operate in unsaturated zones. This level of knowledge is still quite limited. _One condition. In particular, Item 8111 ( FR59'37) , seems more specula-tive than others. An overlying. low permeability.hydrogeologic unit which prevents or impedes downward moving moisture may likewise impede upward moving water vapor. If. radionuclides are present in upward ' moving water vapor driven, by strong.1;hermal gradients created by the waste, such water vapor may- be. forced 'to move laterally below the hydrogeologic un,it until it condenses.

The condensed water vapor, if concentrated in a localized zon~e of

~ ,

parmeability, might have the opportunity to flow as perched water to points of discharge at land surface. Considerable uncertainty

exists the above in terms of radionuclide migration with water vapor, but scenario suggests that the low permeability hydrogeolgic unit could act to concentrate moisture with radionuclide, and permit discharge of this moisture if the hydro-goologic unit intersects land surface in the vicinity of the repository. Therefore, it is not clear that the low permeability hydrogeologic unit would be generally , favorable if radionuclides migrate with water vapor driven from the repository zone.

1 1

Lohman, - S.W. et al.,1972,- Definitions of Selected Ground-Water Forms Revision's and Conceptual Refinements, U.S. Geological l Survey Water Supply Paper 1988, 21 p.

Secretary of the Commission April 13, 1984

• Fage Three Two additional favorable conditions are suggested for NRC's con-sideration:

1. Thermal character!stics of the hydrogeologic unit, such that exposure to high temperature gradients would not cause compaction or volume changee in the packaging or surrounding media.

' If compaction should occur, it could influence the hydraulic conductivity in c negative sense, as well as influence the structural stability of the area around the cannisters. Compac-tion due o high thermal gradients is suggested in studies by Constantz j 2. Bost rock that is capable of accelerated drying.

Due to temperatures reached in the near field, vapor transport in the unsaturated zone is initiated shortly af ter waste emplace-ment. This vapor phase moves outward towards cooler regions where it condenses. The condensed water then moves back towards the cannisters. This sets up a circulation system whic.h is dominated by the vapor phase; that is, % water phase is small compared to the vapor phase. Prolonged circulation ~tends Jo

reduce the total amount of water in the area surrounding the l cannisters because more and more vapor is Lost .to the surroundi_ng system. Eventually there is no wa t e r le f t a s e i

th e r..v.a po r ,-o,r condensate; in short, the host medium becomes , dry. " Therefore, a host rock which encourages this type of Aehavior to occur before_ _

the cannisters begin to deteriorato (and leak) is advantageous.

However, accelerated drying after the cannisters begin to deteriorate (and leak) may be a disadvantage to long-term isola-tion and requires further a lysis. This drying behavior is described in work by Pollock An a d'd i t i o n a l, c o m m e n t on conditions for disposal in the unsatursted zohe concerns hydrogeochemical considerations. For the saturated zone le CFK Part 60 (60,122(c)(9)] identifies a non-reducing environment as an adverse condition. It is probable that the unsaturated zone is an oxidizing environment. An cdditional condition addressing hydrogeochemical conditions in the uncaturated zone is necessary.

2 constantz, Jim, 1983, " Laboratory Anclysis of Water Retention in Unsaturated Zone Materials at High Temperature:, in The Role of the Unsaturated Zone in Radioactive and Hazardous Waste

~6Ts po s a l , eds. J.W. MerceI P.S. Rao, I. W. Marine, Ann Arbor Sciences, 1983, Ann Arbor, Michigan.

Secretary of'tho Commission April 13, 1984 Page Four l

NRC QUESTIONS FOR PUBLIC COMMENT (FR 5937)

1. "How can groundwater travel time in the unsaturated zone be determined with reasonable assurance? Should the .

l groundwater travel time performance objective be limited to groundwater movement within the saturated zone?"

In our opinion, it is' premature to answer the first part of the question due to the limited research devoted to the question

., presently. Groundwater travel time in the unsaturated zone cannot now be determined with any . assurance. With time, travel time in the unsaturated zone may prove to be as predictable (with similar levels .of uncertainty) as travel times in saturated

, media. However, groundwater travel time is also subject to considerable uncertainty in the saturated zone, with the

uncertainty generally increasing in fracturated low permeability rocks. From our perspective, there is little confidence that determinations can be made with reasonable assurance in either media presently.

In response to the second qu e s t i o n , ,, tihere seems to be. no demonstrated

• basis for establishing unnaturated zone travel time i

parformance. It is acknowledged that ground water travel time fs an acceptable performance measure in the saturated, zone and may 3 bo appropriate for the unsa.turated zone, however, presentJy there is no scientific basis to support a precise number f.o,r unsaturated zone travel time performance. . The 1,900 ~ year pre-omplacement ground wa.ter travel time . performance objective, now .

ostablished for the unsaturated zone cannot be projected with reasonable certainty into the unsaturated zone. We believe this uncertainty does not preclude the use of a 1,000-year. travel time, but that its use should be cautioned .by the lack of scientific support to base the number. If the 1,000-year travel time is selected as a performance m e a s u r e', the NRC should consider revisiting this performance standard later when a better understanding of moisture movement in the unsaturated zone is knowng:

2. "Does groundwater travel time represent an appropriate measure of performance for a site within the unsaturated zone, or would an alternative performance objective for the geologic setting, (e.g., maximum likely volumetric flow rate of groundwater through the geologic reposi to ry) be more appropriate?

3 Pollock, David Warren,1982, " Fluid Flow .and Energy Transport in a High-Level Waste Repository in Unsaturated Alluvium", Ph.D.

Thesis, University of Illinois - Urbana, Champaign, Illinois, l

l .

Socratary of the Commission l April 13, 1984 . Page Five Ground-water (unsaturated zone moisture) travel time may be appropriate in the unsaturated zone, and associated time credit to the accessible environment be considered as a measure of parformance, however, the Cormission should recognize several important, factors believed to be involved in a travel time i

consideration of performance. ;

1. Travel time, and direction, may prove to be different for liquid and vapor phase moisture in the unsaturated zone. <

2. Radionuclide transport may prove more complex in unsaturated '

flow than in saturated flow, and not closely related to moisture flux.

r I Porformance based upon maximum likely volumetric flow rates may bo even more sp,eculative than groundwater travel time.

Presently, recharge rates (a measure of volumetric flow rate) cannot be determined with precision, especially during variable climatic conditions. We believe that, although not ideal, ground water travel time in the unsaturated zone may be an acceptable parformance measure at the present time,, ..if the factors dese.rtbed previously are considered. .

Alternative to a travel time performance standard, ,it ljp cuggested the EPA standard be the performance' mgasure by which 4

the geologic setting is judged, or the Comarission uti1Tze the approach set forth in 60.113(b) of 10 CFR Par't 60. This,. section provides the Commission with the flexibility to specify varia- -

tions in performance objectives on a case-by-case basis. The prime reason for suggesting this approach is the current absence of detailed understanding of moisture regimens in unsaturated zone environments, and the associated radionuclide transport by l both liquids and gases in this type of environment. As more l

ostabl.ished relationships and techniques of analysis are developed for each site, an appropriate performance objective may ba possible.

I If you have any questions, please do not hesitate to contact me.

! Since iy,

/ eRobert hY/R. Lo x Direc r j arl A. JohYson Technical Manager ~

RRL:CAJ:sk l

..33 , ,

017070529 U E I i\ W (Y f,fh O[.

Department of Energy COCKETED uw:

Washington, D.C. 20585 gg g l U rter : rrerE ; -

APR 161984  :. : ~..- . 0. 9 & S E w-  !

.W NS Mr. Samuel J. Chilk Secretary of the commission Attention: Docketing and Service Branch

, U.S. Nuclear' Regulatory Commission Washington,-D.C. 20555

Dear Mr. Chilk:

The Department of Energy is pleased to respond to the request of the Nuclear Regulatory Commission (NRC) for comments on the proposed cmendments to 10 CFR 60, published on February 16, 1984 (49 Federal Register 5934). The proposed amendments would make the regulation cpplicable to disposal of high-level radioactive wastes in both the caturated and unsaturated zones. Our comments are contained in two cnclosures to this letter: .the first contains specific comments on the- [ ,

proposed amendments with recommended alternative language where .

cppropriater the second contains the Departmeht's response t'o the -

questions posed by NRC in the Supplementary Information section of the _

Federal Register notice. ** *

- ~ - - -

• The Department believes the performance objective for~a minimum 1000-year, groundwater travel time should only be applied to sites located in the,. .

caturated zone. The Department recomends an alternative performance cbjective, related to the geologic setting, for sites located in the unsaturated zone. The Department will provide a suggested alternative performance objective for NRC consideration by separate letter after the close of the public coment period. The Department will make every effort to provide this information by May 15, 1984 The Dtpartment believes that the proposed amendments, as revised to incorporate the Department's coments, will make 10 CFR 60 effective regulation applicable to sites located in the unsaturated or saturated zones. We are available to meet with NRC concerning the enclosed coments.

Sincerely, h . W Michael J. La rence Acting Director Office of Civilian Radioactive Waste Management i Enclosures h C M C'.vl f;;;g !.y ::- 3 , _ . j_,

ENCLOSURE 1. Comunents on Proposed Amendments to 10 CFR Part 60 for,the Unsaturated Zone

1. $60.2, Definition of The NRC is to be commended on the definition Ground Water of the term " ground water." The NRC definition i

' includes water in both the unsaturated and saturated zones. This definition is, however, inconsistent with the EPA definition in 40 CFR

" Part 191, wherein the EPA defines ground water to t include only that water in the saturated zone.

DOE agrees with the NRC definition. Using the

' EPA definition, DOE believes the proposed amendments would have to be revisited in their entirety.

l

2. 560.2, Definition of with incorporation of the unsaturated zone  ;

Disturbed Zone provisions into 10 CFR Part 60, DOE believes the "

definition of disturbed zone should be reconsidered. DOE believes the disturbed zone '

should not include the volume of rock in which changes will occur which will improve the isolation capability of the repositor-- For example, the Supplementary Informatic.' and NUREG-1046 indicate there may be the creation _of

, a drying zone exte,nd_ing. hundreds _ of meters-from a repository locatand in the unsaturated zon~e. This drying zone (and the accompanying increase in? .

degree of saturation at some farther distance) -

will create a hydraulic gradient' in all- ,--

directions toward the repository - a fa~orable.

condition which will , exist throUghout the temperature pulse.,- DOE recommends that th,e SRC _

revise the definition of the term " disturbed -

zone" to apply to that volume of rock in which changes will occur which will have a significant adverse effect on the performance of the repository.

t

3. 560.2, Definition of DOE recommends revising the definition to mean I Barrier- any material, structure, or condition that prevents, or substantially delays, movement of water or radionuclides. The basis for this recommendation is discussed in the comment on 1

Section 60.122-(b)(8)(iii).

. 4. F6'O.122(b)(2)(iii) The phrase " low hydraulic potential" should be

' revised to either " low hydraulic gradient" or "small difference of hydraulic potential" to be hydraulically correct.

l

5. 560.122(b)(5) DOE believes that, although a minimum dept,h of 300 noters for waste emplacement is a favorable condition, the appJication of this favorable condition to the unsaturated zone is non-conservative in that it ignores the greater benefit to isolation derived from maximizing the thickness of the unsaturated zone between the

, underground facility and the water table. )

Instead, it supports the concept of "the deeper, the better" (see page 19 of NUREG-1046) without

, consideration of the lesser likelihood of l exhumation by erosion, the lesser likelihood of intrusion by deep water well drilling in isolated arid environments, or the advantages of  ;

maximizing the thickness of the unsaturated zone between the underground facility and the water table. To achieve a meaningful balance between favorable conditions for the unsaturated and

. saturated -zones, DOE recommends adoption of a favorable condition for the unsaturated zone that acknowledges the favorability of a substantial distance between the underground facility and the water table. Adoption of such favorable.

condition is, consistent with NRC conc _ erns, ,in Sections 60 122(b)(8)(ii) and 60.122(c)(22).

. :7

6. 560.122(b)(8)(i) The words "and nearly constant' should be_ removed so that this section reads 'Lov moisture. flux in the host rock and in the overlying " '

and underlying hydrogeologic units.'. '

DOE notes that recharge is not constint in'either time or space. Rather, recharge is sporadic, occurring in response to individual heavy rainfalls, extended periods of rainfall (wet season), or snowmelt. Between these recharge j events, water in the unsaturated zone is held in i

tension and flux becomes negligible - an obvious i advantage of disposal in the unsaturated zone. l These findings led Dames & Moore to conclude in NUREG/CR-3130 that the flux and the frequency of wetting events were the primary factors in determining releases from wastes disposed in the unsaturated zone. 1 l

7. 560.122(b)(8)(ii) DOE is concerned with the NPC approach to the concept of capillary fringe as described ir. this condition and on page A-1 of Appendia A to l NUREG-1046. DOE notes that the upper surface of

.the zone of tension saturation (capillary fringe) is neither constant nor planar; rather, it is dynamic and at different heights in materials

L dof different pore sizes owing to the higher capillary rise in smaller pores. 6 The NRC has addressed the DOE concern about the (

number or percent of fully saturated voids  ;

continuous with the water table in NUREG-1046, wherein they have suggested a definition of

' capillary fringe as a planar surface, at which 50 percent-of the pore space-is filled with water.

This suggested definition corresponds with the usage in USGS Water-Supply Paper 1988.

However, the suggested definition can be interpreted as applying to any material having a 3 degree of saturation of 50 percent or greater.

DOE notes that, at a degree of saturation of 50 percent, no pore spaces have to be completely filled with water (and hence it would be above the capillary fringe). DOE believes the intent of the definition is a planar surface at which 50 percent of all pore spaces are completely filled with water (50 percent of all pore spaces are not completely filled with water). DOE dogs not believe that- e'itTier approach' can be defined by field measutaments. -

DOE believes the poncept of; avoiding wast,e-emplacement in the capillary fringe. is valid, though the definition of the capillary fringe will always el,ude' precision. The- capillary _

fringe is something that everyone knows exists, but which no one can adequately define. Even if an unambiguous, non-arbitrary definition is found, the upper limit of the zone of " fully saturated voids continuous with the water table' i can probably not be' defined by field l measurements, particularly under conditions of heterogeneous materials and infiltrating water.

However, in very few, if any, cases could the upper limit of the capillary fringe be more than a few tens of meters. . DOE recommends this section be revised to recognize that it is physically limited to a few tens of meters.

8. 560.122(b)(8)(iii) DOE recommends that this section be revised to read "A hydrogeologic condition above the host rock that would inhibit the downward movement of water, divert downward moving water to n location beyond the limits of the underground incility, or divert a significant portion of downward moving.

water, including that produced by sporadic,  !

l l

i I

intense recharge events, away from the location of waste emplacement."

This rewording addresses the DOE concern that hydrogeologic conditions other than a low permeability unit, such as a contrast in

' permeabilities in adjacent hydrogeologic units sufficient to create a capillary break, may result in the desired effect. In addition, the rewording recognizes the favorable effect of

vertical flow conduits, even within the i

boundaries of the underground facility, in diverting water away from the emplaced wastes.

The ability of a hydrogeologic condition, such as a capillary break, to inhibit water movement (or radionuclide transport) supports the previously recommended revision to the term ' barrier."

9. 560.122(c)(23) DOE recommends rewording this section to clarify its meaning as follows: ' Potential for existing or future perched water bodies that may saturate portions of ,an. underground facility or prpyide a

' faster flow path from an underground facility to the accessib@e environment.'" 2?

10. 560.133(f) This section, nowrapplicabl to'disposalA~n, either the unsaturated or saturated', zones!, on rock excavation desi3n criteria' states that the potential for creating a preferential,. .

ground-water pathway must be limited. However, in the unsaturated zone, a preferential ground-water pathway may be preferred in order to have a freely draining host rock as contained in

'the proposed Section 60.122(b)(8)(iv). DOE recommends revising this section to "The design of the underground facility shall incorporate excavation methods that will limit the potential for creating pathways that could compromise the ability of the repository to meet the performance objectives," to allow internal consistency in the technical rule for the unsaturated zone. This recommended change is consistent with the wording contained in Section 60.133(a).

11. 560.134(b) As in the preceding comment, Dos believes that in-the unsaturated zone, it may be beneficial to

' seal' boreholes and shafts so as to create a preferential pathway for ground water along at ~

least part of the length of the borehole or shaft. For example, it may be desirable to have i

1

I a preferential pathway for ground water from an overlying unit where the ground water may tend to l perch naturally, to an underlying unit or completely through the repository horizon (but l

not in areas of emplaced wastes) to an underlying permeable zone. DOE believes the unsaturated

, zone offers some interesting opportunities for innovative methods and materials for backfilling and sealing, as noted by G. Roseboom in USGS Circular 903.

DOE recommends either revising Section 60.134(b) to be applicable to only the saturated zone, or rewording it to read ' Materials and placement methods for seals shall be selected to reduce, to the extent practicable, the potential for creating pathways that compromise the ability of the repository to meet the performance  ;

objectives." This recommended change is consistent with the wording contained in Section 60.134(a).

12. 560.141(c) Several of the. minimum measurements r. equi [ red in this section, particularly changes in .

ground-watef conditions and rock pore-water pressures (including those along fractures and joints) may be unnecessary,"of' limited use, or difficult to measure in the; unsaturated zone, especially given.ths creation of;a drying zone which may reduce moisture contents so.lo,w or- - ,

create such high negative pressures a,s to exceed the range of measurement for available instrumentation. DOE recommends revising Section 60.141 to replace the term 'as.a minimum" with the term *where practicable.' This recommended change is consistent with the wording already contained in Section 60.140. i d

h N

e

, . , , - . ,--r - - , . - . - ,--m- , . .. , . . . . e=.,. ---

- - - - - - -- .- ~ - - .

ENCLOSURE 2. Responses to Specific Questions Raised i

in the Supplementary Information Question 1. This question, as stated in the Supplementary Information I Section, consisted of two questions which are addressed i

separately below.

A. "How can ground-water travel time in the unsaturated zone be determined with reasonable assurance?'

i .

Ground-water flux can be determined, using measurements of ambient water centent, degree of saturation, matric potential, and hydraulic conductivity to d termine moisture-characteristic curves relating these parameters to one cnother. These curves can be developed so as to predict the constitutive relationships over a wide range of conditions (varying degrees of saturation cnd different matric potentials). From these relationships and flux daterminations, velocity and subsequently ground-water travel time can be catimated.

In situ monitoring techniques, including tracer tests, are undergoing dsvelopment and may broaden the range of rock types and conditions for which it is feasible to estimate velocity and ground-water travel time. NNWSI program investigations also presently include explop,atory shaft, tests on.- ' ,

infiltration rates and sampling of intact fract'ured blocks for labor.atory '

{

cxperiments. These techniques and investigations are state-of-the-art and -

chould provide a direct determination, with reasonable assurance, of the  !

ground-water flux.used to estima.te the ground-water travel time. In addition",

DOE believes that reasonable bounds may be developed by-less direct methods! .

cuch as recharge rates determined from water budgets, perturbations of thermal l gradients, or in situ monitoring of temporal changes in moistures pr'ofiles.- , ,

Reasonable assurance, therefore, may be gained in estimating ground-water

. travel time using results of laboratory testing, state-of-the-art direct I

dsterminations in the field or laboratory, and bounding-estimates developed by indirect methods. . In addition, reasonable assurance may also~be. gained by l incorporating uncertainty analysis into predictive models. Although the uncertainty band for a given level of confidence in the calculations may be l broad owing to the inability to measure ground-water velocities along all ecgments of the unsaturated zone travel paths or under all combinations of msisture conditions and matric potentials, the opportunity to invoke

, conservatism in the ground-water travel time calculations still exists, i

l B. "Should the ground-water travel time performance objective be limited to ground-water movement in the saturated zone?'

l For a repository in the unsaturated zone, DOE does not believe the grcund-water travel time objective should be limited to the saturated zone b:cause this would not be an accurate indicator of actual radionuclide trcnsport from the original waste location to the accessible environment (as

! discussed in the response to Question 2A). DOE b ..oposed, in discussions l with.the NRC on the siting guidelines (10 CFR Par *

), that this performance A

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e cbjective be limited to only sites located in the saturated zone, with a

' separate performance objective developed for the geologic setting for sites cituated in the unsaturated zone. (see response to Question 2b)

Question 2. This question, as stated in the supplementary Information

,section, also consisted of two questions which are addressed separately below.

l A. "Does ground-water travel time represent an appropriate measure of

performance for a site within the unsaturated zone?'

DOE does not believe that ground-water travel time represents an cypropriate measure of performance for a site within the unsaturated zone.

i

' The flux through the repository, both in the unsaturated and saturated zones, i

is a more appropriate and direct measure of potential cumulative releases to the accessible environment. The amount of water moving past the wastes is one of the primary factors which set a limit, independent of flow velocity, flow i

path, or travel time, on-the maximum number of curies of a particular rcdionuclide that can be released from a repository and subsequentl ,be transported by ground water to t!.e accessible environment. DOE nott- that ,

Dtmes & Moore reached essentially the same conclusion in NUREG/CR-3130 when, ,

they concluded that flux and the frequency of watting events were the permary '

factors in determining releases from wastes disposed in the unsaturated zone,._ . .

Should the NRC, however, choose to keep a minimum 1000-year ground-water travel time as the performance objective for the geologic setting', DOE - -

bolieves it should logically be applied to sites situated in the unssturated -

zsne only if the travel time will include the combined" travel' times,in the unsaturated zone and the saturated zone so as to tetter approximate .

rcdionuclide transport. This may necessitate a revision to the definition of ,

the term ' disturbed zone," since the current definition is so vague as to

' passibly permit defining the disturbed zone as extending downward through the unsaturated zone all the way to the water table or upward through the unsaturated zone all the way to the ground surface. DOE believes it would be inappropriate to apply the minimum ground-water travel time to only the ssturated zone underlying a repository in the unsaturated zone, since such cpplication would conflict with three highly favorable conditions resulting from a highly transmissive (and short travel time) water-table aquifer underlying the repository. These are:

1. A highly transmissive aquifer can be expected to transmit any increased throughflow, resulting from increased precipitation during a glacial stage, with less rise in the water table and accordingly less likelihood of saturation of the repository from below.

2. A highly transmissive aquifer can be expected to significantly dilute any postulated releases from the repository since the characteristically low flux in the unsaturated zone would be a very small fraction of the throughflow in the aquifer. '

3. A highly transmissive aquifer can be expected to significantly disperse any postulated releases from the repository since the dispersivity of the aquifer would be quite high.

Therefore, although a highly transmissive aquifer underlying a repository situated in the unsaturated zone may not provide a 1000-year ground water travel time to the accessible environment, it does not affect the flux through the unsaturated zone (hence it does not affect the cumulative release to the cecessible environment over the 10,000 year period of interest). In addition, i cithough the EPA standard is not based on dose, DOE notes a highly transmissive aquifer underlying a repository in the unsaturated zone provides o means of assuring the reduction of the concentration of (and hence dose rcceived from) any postulated releases due to dilution and dispersion (thereby b3ing applicable to both reactive and non-reactive radioisotopes without

, consideration of sorption and other retardation processes).

D. 'Would an alternative performance objective for the geologic setting (e.g., maximum likely volumetric' flow rate of ground water through the

, geologic repository) be more appropriate?' l DOE believes an alternative performance objective for the geologic cotting for a repository located in the unsaturated zone is-more appropriate.

DOE has initiated a concerted effort to develop such a performance objective for proposal to the NRC. This activity is still in progress, and DOE will provide an alternative performance objective by separate letter after the close of the public comment period. . DOE will malg,e jvery ef fort to provide- the alternative performance objective by May 15, 1984. ,

DOE believes that the volumetric flow rate (flux) of grou,nd water through a geologic repository located in the unsaturated zone is the most important.--

fsetor in determining the performance of the repository. However, DOS cannot, at this time propose or endorse a' numerical performance objective on maximum flux since the acceptable flux would be site-specific and design-spe'cific. - .

DOE will continue, however-, to consider flux and other factors in its attempt' to develop an alternative performance objective for the geologic setting for a repository located in the unsaturated zone.

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Departrnent of Energy "Ja7ai Washington, D.C. 20585

'84 JUI.12 P2:59 JUL i 119s4 SP- cc. ',..

Mr. Samuel J. Chilk $USf l Secretary of the Comission l Attention: Docketing and Service Branch U.S. Nuclear. Regulatory Commission Washington, D.C. ~ 20555

Dear Mr. Chilk:

The Department of Energy submitted comments on the proposed amendment to 10 CFR Part 60 for disposal in the unsaturated zone in a letter to you dated April 16,1984. In that letter, the Departmerit indicated it would provide a suggested alternative perfomance objective, related to the geologic setting for sites located in the unsaturated zone, by separate letter after the close of the public comment period.

This letter transmits the proposed alternative perfomance objective and the Department's rationale for the proposed performance objective.

As indicated in the Department's letter dated April 16, 1984, we are available to meet with the NRC concerning the previously transmitted comments or the enclosed material.

Sincerely, t

en C. Rusche, Director Office of Civilian Radioactive Waste Management Enclosures Adn::wkcd b/ cud . . . . . . . . . . . . . .

• 1

4 i

4 RATIONALE FOR PROPOSED ALTERNATIVE

, PERFORMANCE OBJECTIVE As noted in the DOE comment letter to the NRC dated April 16,1984, Dames

& Moore concluded in NUREG/CR-3130 that the flux and the frequency of wetting events were' the primary factors in determining releases from wastes disposed in the unsaturated zone. DOE stated that ground-water travel time does not

represent an appropriate measure of performance for a site within the unsaturated zone and that the flux through the repository, both in the unsaturated and saturated zones, is a more appropriate and direct measure of

, potential cumulative releases to.the accessible environment.

i

~

Accordingly, DOE has given considerable effort toward developing a proposed performance objective based on flux through a repository located in the unsaturated zone. Although this effort has reinforced the understanding that flux is the primary factor in determining releases'from wastes disposed in the unsaturated zone, DOE has concluded that it is impractical to specify a

! -minimum amount of flux or to otherwise define a performance objective for the -

geologic settings based on the flux through the repository. A determination of flux will be necessary, however, to demonstrate compliance with the EPA Standard.

As a result, DOE reviewed the NRC rationale for the performance objective

' specifying that the fastest likely path of radionuclide travel to the l accessible environment shall be at least 1000 years ~ or such other travel time l

l 1 -

4 2

l as may be approved or specified by the Commission. This performance objective can be interpreted as specifying a minimum time before release of ,

radionuclides to the accessible environment. DOE concludes, based on this review and interactions between NNWSI Project staff and the NRC staff, that

. satisfying this performance objective is meant to provide an independent and redundant barrier to the engineered barrier system during that period of time when the wastes are most hazardous (46 FR 130, p. 35281). DOE notes that, for ,

sites located in the unsaturated zone, this same effect may be derived, either in whole or to a large extent, from the creation of a dry.ing zone around the underground facility during the period of the heat pulse. Therefore, the concept of a minimum time for release of radionuclides to the accessible environment forms a reasonable basis for a site performance objective for the unsaturated zone and is a more appropriate performance objective than

. ground-water travel time for the unsaturated zone.

t

The emplacement of radioactive waste canisters within an unsaturated zone-repository leads to a situation wherein the heat generated by the wastes as they decay causes the moisture in the rock surrounding the waste canisters to mig' rate away from the waste canisters. Preliminary numerical modeling of this I phenomenon (I} indicates that this migration creates a zone around the

! (IIB. Travis, H. Hudson, T. Nuttall, T. Cook, and R. Rundberg,1984,

" Preliminary Estimates of Water Flow and Radionuclide Transport in Yucca Mountain," LA-UR-84-40 (in Review), Los Alamos National Laboratory, Los Alamos, New Mexico.

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3 canisters, extending for a few tens of meters in which there is no water -,

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y. . available to either corrode the canisters, dissolve the wastes, or transport l

i any radioactive material. The drying phase for'a saturated zone repository is  !

expected to last several hundred years before resaturation is complete 1

(NUREG-0804). -In an unsaturated zone repository, the time required for moisture to return to the waste packages is expected to be even longer because i l

the rock will return to initial conditions primar'ily through capillary effects. '

A site performance objective for the unsaturated zone, based upon the minimum time for release of radionuclides to the accessible environment, must I consider four separate physical events. The first event is the creation of the drying zone. The second event, which is closely related to the creation of the drying zone, is the subsequent return of moisture to the rock l surrounding the waste canisters. These two events encompass a time during which no water is available to either corrode the waste canisters, dissolve the waste material, or transport radionuclides to the accessible environment.

The third event important to the release of radionuclides to the accessible environment is the transport of radionuclides in the unsaturated zone.

Finally, the radionuclides are transported to the accessible environment by ground water movement in the saturated zone.

, The minimum time for release of radionuclides to the accessible i envirornent is the sum of times required for each of the four events because they are temporally sequential. The minimum time for release of radionuclides to the accessible environment for an unsaturated zone repository is thus the g - -. -.. -,,we. , - , , -,

4 sum of the time during which a drying zone exists around the waste canisters, the time it takes for the dcy rock to return to initial moisture conditions, the time for ground water to travel through the unsaturated zone and the time for ground water to travel through the saturated zone to the accessible

environment.

It is not inconceivable that the time for dtring added to the time for return to initial moisture conditions could encompass the total 1000 year

~

period required for fission products to decay to insignificant levels. When all four time components are added together, significantly higher confidence

in protection of public health and safety is obtained tha'n if.only the time

when radionuclides are actually moving were considered.

Th+ NNWSI Project site characterization activities include studies of the drying phenon.nnon. Ic addition to the previously mentioned study of radionuclide tran. ort .'nd the formation of the drying zone, other numerical .

l studies which model 'he physical responses, in the unsaturated zone, to the

! emplacement of waste c 'nisttrs and heat are underway. In situ tests to obtain I

_ information about moistui t asgration in response to thermal loads are planned 1

) for the exploratory shaft. These tests include bulk permeability tests, i

canister 3cale heater experiments and waste package tests. The waste package tests are reduced scale but are dos gned to specifically investigate moisture 3

conditions, particularly moistare we.a.'t J; iring thermal' and post themal periods of storage. High frequency e16 tromagnetic, ultrasonic and neutron methods are to be used to establish the moisture content in the area M

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5 surrounding the simulated canister before and after thermal cycling and to

. ' monitor. fluid movement during the experiments. These activities should g-provide the necessary and sufficient infomation to support demonstration of compliance with the proposed alternative perfomance objective.

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PROPOSED ALTERNATIVE PERFORMANCE OBJECTIVE DOE proposes that Section 60.113(a)(2) be revised to Section 60,113(a)(2)(1) and a Section 60,113 (a)(2)(ii) be added as follows:

For-a geologic repository located in the unsaturated zone, the minimum 1000 year travel time to the accessible environment shall include the time of existence of the drying zone around the emplaced wastes, the time required for rewetting to initial

. moisture conditions, the time of travel through the unsaturated zone, and the time of travel through the saturated zone.

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BRANCP.

April 13, 1984 Secretary of the Commission U.S. Nuclear Regulatory. Commission ,

W2chington, D.C. 20555 Atta: Docketing and Service Branch -

Subject:

NRC's Proposed Rule Concerning the Disposal of High-Level j

Radioactive Wastes in the Unsaturated Zone (49 FR 5934)

Dear Sir:

. . . . .- _~..

Middle South Services, Inc. (MSS) is a technical support company for the Liiddle South Utilities (MSU) System which serves the electrical requireinants of approxi-

~

' matoly 1,800,000 customers in portions of Arkansas, Louisiana, Mississiippi and - ,

Miscouri. MSS has reviewed the proposed amendments and draft NUREG-1046, " Disposal of High-Level Radioactive Wastes in the Unsaturated ~ Zone : Technical Considefat. ions

! cud would like to express our support of the proposed amendment which allows the l dicposal of high-level radioactive waste (HLW) in the unsaturated geologie zone.

The Middle South . System has four nuclear reactors in operation or nearing

cparational status, therefore Middle South Utilities has been closely following the progress being made toward the opening of the first high-level nuclear vaste reposi-tory. The siting of these repositories must be limited to those geologic areas where 4

the 3LW can safely be disposed of without significant damage to the environment or i harm to the public's health. A review of the proposed amendments and its associated

! NUREG shows that the unsaturated geologie zone is a. viable alternative to disposal l in the saturated zone. Each site, whether it is located in the saturated or the

! unsaturated zone, should be judged based on its overall ability to safely contain HLU. Currently, there is not sufficient technical justification to favor disposal in the saturated. zone over the unsaturated zone. As mentioned in NUREC-1046, there  !

cro some factors which make disposal of HLW in the unsaturated zone preferable to l disposal in the saturated zone. Two of these factors are: (1) wastes can be  !

empicced in a geologic medium with low moisture content which would minimize leach- l ing cf waste packages; and (2) enhanced retrievability-wastes would be more easily '

ccescsible in an unsaturated zone if this need should ever arise. There are factors l

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Sacratcry of tha Comission l

April 13, 1984 ,

Page )

which make the saturated zone a more desirable. location, however, as stated previously, each site must be reviewed breed on all relevant factors, not simply en whether the site is located in a saturated or unsaturated zone. A balancing of cil factors disposal will ensure that the most suitable sites are chosen for the of HLW.

l MSS regrets that we are unable to provide NRC with the technical comments which have been requested. However, we appreciate this opportunity to comment i

on cnd express.our support of this proposed amendment. The siting and the eventual '

operation of HLW repositories are of vitalimportance to the electric utility in-ductry. MSU encourages and supports NRC in their endeavor to accomplish this goal <

within the time-frame established in the Nuclear Waste Policy Act. 1 Sincerely, i

, /

Joel D. Patterson Manager of Environmental Affairs

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y Al"A ,g UNITED STATES ENVIRONMENTAL PROTECTION AGENCY J WASHINGTON, D.C. 20460 7

'84 APR 20 P1:09 OFFICE oF

. ... EXTERNAL AFFAIRS

• APR 2 01984 . :-LSN.

Siu.NCH Dr. Colleen Ostrowski .

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pg Office of Nuclear Regulatory Research '

f U.S. Nuclear Regulatory Commission f Washington, D.C. 20555 { .

Dear Dr. Ostrowski:

e In accordance with Section 309 of the Clean Air Act, as amended, the U.S. Environmental Protection Agency (EPA) is commenting on the U.S. Nuclear Regulatory Commission's (NRC) proposed amendment to 10 CFR 60, Disposal of High-level Radioactive Waste in the Unsaturated Zone. EPA generally supports the proposed rule.

EPA is developing Environmental Standards 'for Management and Disposal of Spent Nuclear Fuel, High-level and Transuranic Radioactive Wastes (40 CFR 191). Any disposal of high-level wastes will be subject to 40 CFR 191, and EPA appreciates the assistance NRC and other organi-zations has given us in the development of our rule.

Accordingly, EPA is submitting the enclosed comments to avoid differing regulatory approaches between the NRC and EPA rulemaking efforts. EPA will work with NRC to avoid conflicting approaches on the respective rules of the two agencies.

I appreciate the opportunity to comment on this proposal. If you

, hav.e any questions concerning EPA's comments, please call Dr. W. Alexander Williams (382-5909) of my staff or Mr. Daniel Egan (557-8610) of EPA's Office of Radiat'on Programs.

Sincerely yours,

& bop /&imk-Allan Hirsch, [Iirector

. Office of Federal Activities Enclosure s ..

.*..s.3. ..*..e.e g }

Comments of the U.S. Environmental Protection Agency on the U.S. Nuclear Regulatory Commission's Proposed Rule for Disposal of High-level Radioactive Wastes in the Unsaturated Zone l

1. 10 CFR 660.2 (Definitions)

NRC proposed to redefine the term " ground water" to include all water in both the saturated and unsaturated zones. This c.hange apparently pro-vides a simple regulatory means for applying existing criteria written

, several years ago for high level waste repository siting in the saturated zone to the unsaturated zone as well. While this expansion of applicabil-ity may be reasonable, EPA would prefer that the NRC retain the standard scientific meaning for the term (i.e., water within the* zone of saturation).  !

We are concerned that confusion may eventually arise among the public, par- 1 ticularly in their understanding of the application of methods of ground )

water monitoring. j l

" Unsaturated zone" should be defined as the zone between the land  !

surface and the shallowest free water table, discounting " perched" tables.  !

The definition written in the proposed regulation says, " deepest." This

, is confusing. The definition with " deepest" would be correct, however, if the term " water table" were also defined >as the potentiometric surface beneath the land surface at atmospheric pressure.

2, 10 CFR E60,122 (siting criteria) ~  ;

The Comission proposes to amend Section 60.122 by adding new para-graphs (b) (8) and (c) (23). There seems to be a conflict in the criteria outlined under portions of the two respective paragraphs. Paragraph (b) (8)

(iii) requires that hydrogeologic conditions in the unsaturated zone pro-vide for "a laterally extensive, low permeability unit above" the reposi-tory to inhibit downward migration of water into the underground facility.

Paragraph (c) (23) presumably calls for the unsaturated zone to be free of  ;

the potential for " perched water bodies that may have the effect of saturat- '

ing portions of the underground facility." It seems that these are in conflict because the laterally extensive, low permeability unit encouraged-

' to be located above the repository as outlined in paragraph (b) (8) increases the potential for the formation of perched water bodies inanediately above the unit. Although .the low permeability strata may '

serve to inhibit downward migration, it encourages the possibility of I perched water ' bodies that may result in saturated flow conditions above and immediately surroundin Conversely, paragraph (c) (23) g thediscourages limits of the.siting underground

.in areas repository.

where the potential for existing or future perched conditions exists. EPA rectmmends that this inconsistancy be resolved.

i 4

1

i

3. With respect to the three questions on which the Comission 1 particularly seeks comment: '

Question: "How can ground water travel time in the unsaturated zone be determined with reasonable assurance?"

EPA Reply: EPA's Office of Solid Waste will soon publish Procedures for Modeling Flow Through Clay Liners to Determine Required Liner Thickness in its series of Technical Resource Documents. This manual presents a numerical simulation model to estimate travel time of water through unsaturated sediments. Once copies are available from GPO, we will forward one to Dr. Colleen Ostrowski at the NRC.

Measuring natural tritium (3H) concentrations in ground water .

samples from a vertical profile in unsaturated geologic formations may be another technique for estimating travel time. Since the atmospheric testing of nuclear weapons, ground water recharge (i.e., precipitation) has contained levels of this radioactive isotope above the naturally low levels existing before the testing began. Consequently, tritium may serve as an indicator or tracer of "new" water in a geologic prc'ile, and thus may indicate approximate travel times from the rechargipoint.-

Question

"Should the ground water travel time p,erformance objective be

limited to ground water movement within the saturated zone?"

EPA Reply: No. To allow DOE to take' credit for the delay in water i reaching the water table after passing an unsaturated zone repository l (when considering NRC's existing 1,000 year " ground water" travel time l requirement), NRC proposes to redefine the term " ground water" to i.

include all water below the land surface, not just water below the water tabTe, in the saturated zone. We do not think it is necessary to change the widely understood meaning of this term to accompish NRC's objective. EPA agrees that DOE should be able to take credit.for any such delays in the unsaturated zone. However, it would be more appro-priate to make the existing section 60.ll3(a)(2) apply only to reposi-tor.ies in the saturated zone and to add a parallel section for unsaturated zone repositories that allows the Department to add the water travel times in the saturated and unsaturated zones to compare against the 1,000-year time period. Even if NRC redefines the term

" ground water" for 10 CFR 60, EPA has no plans or need to make a corresponding change in 40 CFR 191. .

Question: "Does ground water travel time represent an appropriate measure of performance for a site within the unsaturated zone, or would an alternative performance objective for j the geologic setting be more appropriate?"

l EPA Reply: .No, it does not. 'An alternative option should be available.

l EPA does not believe that such a " water" travel time is appropriate as the only quantitative measure of performance for a site within the

. e unsaturated zone. Instead, we believe that DOE should have the option of meeting a fairly stringent limit on the average annual flux of water through the repository to the accessible environment instead of the travel time requirement of section 60.113(a)(2). This limit should be chosen so that the corresponding total volume of water reaching the accessible environment within a thousand years would not be capable of transporting a significant amount of radioactivity, taking into account. reasonable solubility limits. At a particular site, the Department should have the option of demonstrating compliance with either the minimum travel time requirement or the rraximum water flux requirement.

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STATE OF WASHLNCTON USIE" DEPARTMENT OF ECOLOGY sw swp ev-n. . w wwwgran eeso: . dS4sRt MO P3;12 ,

April 13, 1984 ;J G.- 3E J t1AR

. C;/.i.il!iG & SERVIC.'s.

SRANCH 00CKET NUMBER

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P.ROPOSED RULE _

(44FA 39%) .'

The Honorable Nunzio J. Palladino Chairman U.S. Nuclear Regulatory Commission 1717 H Street, N.W.

Washington, D.C. 20555-Daar Chairman Palladino:

Ref: NUREG-1046, " Disp 5 sal of High-Level Radioactive Wastes in the Unsaturated Zone... Draft Report for Comment."

WG are fully in agreement with the proposed amendments to 10 CFR 60 which accommodate candidate repository sites in the unsaturated zone.

Mcwever, it is apparent that the main body of reasoning and 1 examples covered in the draft applies to the Nevada Test Site.

The principal technical reference, in fact, is NUREG/CR-3158, which contains in its title'the phrase, " Emphasis on the Nevada Tost S.ite."

' Wo have never been fully satisfied with the pre-NWPA siting docision process which led the U.S. Department of Energy to put its Hanford Reference Repository Location deep in the l

saturated zone, stratigraphically clo.se to aquifers of great economic importance. As the principal water management agency for a state where future water quality and availability are i

sensitive, highly-charged issues, we are deeply concerned with cny risk of contamination, no matter how slight.

The, proposed amendments can be in'terpreted as a signal that tho Nuclear Regulatory Commission, like the state of Washington, .

s l ,:.mmm,m.t..f'.g.v.([R

The Honorable Nunzio J.~Palladino April 13, 1984 Page 2 wants to see all reasonable alternatives examined and, where indicated,' re-examined before final commitment to a deep, difficult site such as the Hanford' location in the saturated zone.

Sincer ,

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Director

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DWM/kh cc: David W. Stevens 1

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[Mh, United States Department of the er o N

= ^ i OFFICE OF THE SECRETARY Efp',ED 77 WASHINGTON, D.C. 20240 W APR 23 Pi:d4 APR 2 01984

CF SECRiiA.*'

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Mr. Samuel J. Chilk RA!iC"W Secretary of the Commission U.S. Nuclear Regulatory Commission Washington, D.C. 20555

Dear Mr. Chilk:

The Department of the Interior has reviewed the proposed rule for Disposal of High-Level Radioactive Wastes in the Unsaturated Zone (10 CFR 60). Our detailed comments are attached.

We appreciate the opportunity to comment on this proposal.

Sincerely,

/jffG. ct" Aruce Blanc ard, Director Environmental Project Reviiew Enclosure

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REVIEW OF PROPOSED RULE FOR DISPOSAL OF HIGH-LEVEL RADIOACTIVE WASTE IN THE UNSATURATED ZONE (ER 84/271) i In commenting on the propcsed unsaturatsd-sone amendments, it is convenient

" to separate discussion into: (1) responses solicited; by NRC (49 FR 5937); (2) comments on the proposed amendments; (3) comments regarding saturated-sone criteria.that are also applicable to the unsaturated rene, and (4) comments ou definitions.

l

! NRC SOLICITATIONS (la) "How can around-water travel time in the unsatursted zone be determined with reasonable assurance?" hile it sty act be possible te define ground-water y_elocities along all segments of unsaturated-zone travel paths with precision, particularly those segments through moderately to highly fractured media, the velocities and travel, times in scene segments are lema elusive. In the case of a relatively unifora,_ porous medium with low-fractura density, the medium will be capable of transmitting a fluz that is apprcxximately equivalent to its saturated hydraulic conductivity without rejecting water to fracture flow paths. Furthsr, it le within the state-of-the art to decernine ambient water content and degree of saturation as well as moisture-characteristic curves j

for such media so that effective conductivity can be predicted for a range of conditions. In,-situ monitoring techniques are undergoing development and may broaden the range of rock types and conditions for which it is feasible te estimate velocity and, hence, travel time. On a site-specific basis, certain bounds may be placed by less direct consideracions such as recharge rates based on water budgets, perturbations of thera.11 gradie'sts, or in-situ monitoring of temporal changes in moisture profiles by seutron logging'.

j Finally, repository investigations presently include exploratory-shaf t tests j

i on infiltration rates and sampling of intact fractured blocks for laboratory experiments.

)

' " Reasonable assurance" may also be gained by incorporating uncertainty analysis into predictive models.' Although the uncertainty band for a given level of confidence in the calculations may be broader for unsaturated-zone cases than for s_oag saturated-sone conditions, the opportunity to invoka conservatism scill exists.

(1b) "Should the around-water travel time performance obiective be limited, to around-water movement within the saturated zone?" Assuming that the ground-water -

travel time objective and favorable condition reania in the regulation, the travel time along any segment of P.he flow path including the unsaturated zone, should be creditable, provided that it can be demonstrated with " reasonable assurance" as discuss 6d above.

'(2) "Does around-water travel time represent as amoropriate measure of .__

l oerformance for s site within the unsaturated zone. or would an alternative performance obiective . . . (e.m.. maximum likely volumetric flow rate of around water through the neolonic repository) be more amoropriate?" Travel time substantially ex:eeding 1,000 years, although a favorable condition, is l not appropriate as a totally definitive performance objective for disposal l in either the unsaturated or saturated zones. Ground-water travel time probably

! is the singularly most important element for evalnating the performance of a

v. . .

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site; however, release criter$a are ultimately the absol.ute measure of total

( performance. The method by which travel time is calculatted must account for l I all elements of the ground-water flow system and must re:sult in terms that '

can be used directly for determining transport and concenntration of radio-  ;

nuclides in the. ground water. Release criteria and 'radionuclide transport i aust be concerned with many factors such as ground-water flux and velocity (travel time), convective transport, dispersion and diff'usion, chemical inter-

' action with rocks along the flow path. and rates and conscentrations at which radionuclides leached from the solidified wasta enter this water. Realistic estimation of release criteria for the unsaturated zona might not be possible until observations are made in the shafts and drifts.

' While it may be possible .to assign a maximum allowable f2ux rate--e.g.,

one that would assure the failure of containment under reasonable assumptions of chemistry, corrosion, and dissolution-it would stillt. be more consistent with the multiple-barrier concept to incorporate such ecrasiderations only l as favorable or potentially adverse conditions.

PROPOSED AMENDMENTS Section 60 122. Sitina Criteria. (6). (7): "Prewaste-enzolacement arounderater travel time alona the fastest path of likely radionuclidie travel from the disturbed zone to the accessible environment that substaintially exceeds 1.000 years." Add " . . . considerian both unsaturated and santurated samments of

, the flow nath." We believe that prewasta emplacement ground

• rater travel time j

i is conceptually an appropriate " favorable characteristice" for sites located I in the unsaturated zone. However, it is a criterion thaat will be much more difficult to demonstrate in a legal sense at an unsaturanted site than at a saturated site.

As currently worded, the criterion is ynerhaps inappropriate i

for unsaturated and perhaps some types of saturated sitees, such as salt and

dense fractured crystalline rocks.

i We believe that in order for the travel-time criterion t:o be ' effectively

] applied, it needs to ' incorporate a concept of areally antd temporally averaged

] ground-water flow velocity (rather than the fastest onemdimensional pathway)

]

' and/or a flux constraint. Additionally, the current woreding makes no provision for the quantity, of water moving through the repository tto the accessible environment--only the velocity. It seems inappropriate :to reject a site that l

~ might have 1 cubic meter of water moving through a repos:itory to the accessible environment in 1,000 years and to accept a site that misiht have 1 million cubic meters of water moving through it to the accessibLa environment in 1,500 years. This ===ple is, of course, hypothetical.

~

We also realize that there is an exception clause in the: criterion for i

special considerations allowing the Commission to considner other factors when appropriate and when it can be demonstrated that a site would clearly

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meet EPA standards. However, it is not clear how that exception might be .

applied or what difficulties would be encountered in gai':ning acceptance i by the technical community or various public interest armops for such an exception. Some of these difficulties might be overcomen by one or more of

the following options

. ~ _ - . - _ . ~ _ , ~ . - - - - + - - . - - - - - - . -- . - - . - _ . - - - - - . _ . , , - . - , --..,--_e. -, ,.-,r.- ._ . - . .. . , . , , . . _ . - - . . _ . -

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3 Clarify some typical circumstances under which the travel-time criterion might be waived, such as by demonstrating that the flux is likely to be small or nil.

Specify~more preciselv how the ground-water velocity (or travel time) should or be calculated, integrating using specific cross section area or other averaging conventions.

Use a volumetric flow rate (flux) critarion for ground water in addition to or in place of ground-water travel time.

The principal hydrologic advantage of the unsaturated zone is minimizing or eliminating contact of the vaste with flowing ground water. This advantage would most likely be more important than ground-water travel time in reducius total quantity of radionuclides which could potentially escape to the accessible environment.

The rate of release of radionuclides to the accessible environment from a repository in the unsaturated zone is directly related to the nuclide concentration in the-leachate, flux of leachate, dilution of leachate in the zone of saturation, and ground-water velocity (plus geochemical retardation and dispersion effects). Kisimizing leachate flux would appear to be at least as important as maximizing ground-water travel time.

It might, therefore, be appropriate to specify a dual "either/or" criterion such that ground-water travel time is greater than 1000 years or ground-water specified fluxaverage through rate.

the host rock at the proposed site is less than some The rate could be based on nuclide solubility, leach rate criteria, and population exposure criteria (EPA concrutration '

standards).

We believe that either a flux or travel-time criterion should be based upon an areally integrated or averaged calculation, over an area on the order of the cross-sectional area of the repository normal to the direction of )

expected flux, for both saturated and unsaturated sites. This would help reduce the uncerf ainty and controversy over how the " fastest pathway" can be I determined.

The fastest pathway for saturated fractured rocks, for unsaturated media, and for other highly heterogenous media would be virtually impossible to calculate with reasonable confidence.

calculations and bounded estimates can be determined with reasonableHowever, areal avera confidence, usually by two or more independent methods. Also, qualitative evidence, such as the preservation of archeological artif acts, packrat middens, and other paleo-materials can lend further confidence to long-term estimates of leach rates and water contact in arid unsaturated materials. If ground-water travel time is to remain a general performance objective criterion for the unsaturated zone, we believe the rule should specify a simple, straightforward, and consistent formula for site determination.

for consideration. Use of the formula is with theWe propose the following formula assumption that movement of water in the unsaturated zone is basically interstitial and that at least a continuous film of water is present. The formula would have doubtful application j in dominantly fractured rock with very little interstitial effective porosity.

The vertical ground-water velocity through the unsaturated zone could be determined as the average vertical recharge rate over the approximate area of the repository, divided by the average volumetric moisture content of the.

subsurface medium. As a hypothetical example, if a site were determined to

4 i '

have an average recharge rate of 10mm per year and an average subsurface noisture content of 10 percent (10 percent of bulk volume contains water), an average velocity would be 10/0.1 or 100mm per year (01m per year). If it were 100m above the water table, the travel time in the unsaturated zone

alone would be 1000 years. It becomes obvious that a nearly zero moisture content would result in'a theoretically infinite velocity. This is absurd, but does emphasize the need for prudent application of any mechanism with which to approximate conditions that defy accurate analysis. Ground water velocity I

is one important element of performance and although this method is not precise or highly accurate, the method could form the basis for approximations that could be consistently applied to a variety of sites where unsaturated porous media are part of the flow system.

Section 60122(b)(8): "For disposal in the unsaturated zove, hydroneologic conditions that provide . . . "

Section 60122(b)(8)(1): " Low and nearly constant moisture flux in the hose j rock and in the overlaying and underlying hydroneolonic units." This is an improvement over the earlier " low and constant moisture content" in that it cvoids the erroneous implication that low noisture content necessarily j ===na low flux. However, "nearly constant . . . flux is not necessarily j an advantage, as evidenced by the conflict with " free drainage."

s Section 60.122(b)(8)(iv): A low, constant rate of flux would seem to offer i

better opportunity for dissolution processes than would an average low, but cpisodically high flux. There is some evidence also that some materials for

waste canisters may be more resistant to corrosion under episodic wetting and drying. Basically, it seems best to address only a single concept or factor in a single statement of condition. Also, change " overlaying" to

" overlying."

Section 60122(b)(8)(ii): "A water table sufficiently below the underground facility such that fully saturated voids continuous with the water table do not encounter the underground facility." This condition has also been improved over the earlier version, which depended on a rather inappropriate definition of " capillary fringe." However, it still appears to be incumbent on the applicant to prove that there are no continuous paths of water occupying saturated pores-an impossible task. We suggest changing the favorable condition to read as follows:

1 Section 60.122(b)(8)(iv): "A host rock that provides for free drainage; or . . . " We suggest that "or" should'be changed to "and."

Section 60.122 (b), (8), (v): "A climatic regime in which the averste rnnual historie precipitation is a small percentage of the average annual ~ ~ '

j potential evapotranspiration." The term "small percentage" is vague and inappropriate, in our opinion. We suggest specifying an absolute value of cverage recharge as a maximum, perhaps on the order of 50mm or less. -

l

-- -w - - , - - - - - - - , . --,r-_ w. ~w--n,,en e-w-,.- - - - - , - - - _ - , , e , - + --- ,-,e- -------w - , , , . - , , . , .nr,-,- ,m~

g - -

• 5 Section 60 122 (e). (24): We suggest adding quantitat&ve clarification to this criterion. As currently worded, it allows no,o potential vapor-phase transport of radionuclides by molecular diffusion or perhaps by convective transport. Although these .fluzes might be miniscule, they would not be sero at any unsaturated site. Therefore, if this criterion is ever considered as a disqualifying fgtor it will need qualification as regards release rate of nuclides such as 9I and l'C.

of the boundary for the accessible environment.Related to this question is the interpretation It is not clear to us from the definition in 10 CFR 60 whether the " accessible environment" includes the airspace immediately above the ground surface directly over the repository or only the atmosphere beyond the boundary.

Differences in these two interpretations could have major impacts on how the vapor transport criterion is tested.

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APPLICA3LE SATURATED-ZONE CRITERIA Section 60122(b)(2)(iii): To be hydraulically correct, the phrase " low hydraulic potential between" should be " low hydraulic gradient between" or "cmall difference of hydraulic potential between." This concept is clso applicable to the unsaturated zone and is implicit in the wording

" Low . .

. moisture fluz in the host rock . . . . "'

Snetton 60.122(b)(2)(iv): We endorse extracting this as 60.122(b)(7),

as proposed, and adding the statement suggested above to make it clear that the travel time in the unsaturated zone should be creditable.

DEFINITIONS

" Accessible environment." We strongly suggest that aquifers be incorporated in this definition.

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c e .; r e m;' g iU m.ted States Department of the Interior

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T. l GEOLOGICAL SURVEY '

RESTON. VA. 2 092 In Reply Refer To: April 30, 1984 WGS-Mail Stop 410 ,

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Cewa,d b.1)

Ms. Colleen Ostrowski, Geologist Office of Nuclear Regulatory Research ~_

Nuclear Regulatory Commission Washington, D.C. 20555

Dear Ms. Ostrowski ,

Thank you for your telephone call,of April 25, 1984. There were indeed two e

, typographical errors in the cornments originating from the U.S. Geological _

Survey contained in the letter from Bruce Blanchard to Samuel J. Chilk of April 20, 1984, concerning review by the Department of the Interior of the

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proposed rule for Disposal of High-Level Radioactive Wastes in the Unsaturated Icne (10 CFR 60). The two errors that you so perceptively found are both on pcge 4 of the letter and can be corrected as found on the enclosed new page 4.

Sincerely yours, l d I) l' b C . "

/( . t,... .

John B. Robertson Chief, Office of Hazardous Waste Hydrology Enclosure I

v - - - -

, , - ~

v- .- - ~

I

4 have an average recharge rate of 10am per year and an average subsurface moisture content of 10 percent (10 percent of bulk volume contains water), an average velocity would be 10/0.1 or 100mm per year (0.la per year). If it were 100m above the water table, the travel time in the unsaturated zone alone would be 1000 years. It becomes obvious that a.nearly zero moisture content would result in a theoretically infinite velocity. This is absurd, but does emphasize the need for prudent application of any mechanism with which to approximate conditions that defy accurate analysis. Ground-water velocity is one laportant element of performance and although.this meth'od is not precise or highly accurate, the method could form the. basis for approximations that could be consistently applied to a variety of sites where unsaturated porous media are part of the flow system.

Section 60.122(b)(8): "For disposal in the unsaturated zone, hydrogeologic conditions that provide . . . "

Section 60.122(b)(8)(i): "Lov and nearly constant moisture flux in the host rock and in the overlaying and underlying hydrogeologic units." This is an improvement over the earlier " low and constant moisture content"uin that it cvoids low the erroneous implication that low noisture content necessarily means-flux.

However, "nearly constant . . . flux is not necessarily an i

1 cdvantage, as evidenced by the conflict with " free drainage," 60 122(b)(8)(iv).

A low, constant race of flux would seem to offer better opportunity for j

dissolution processes than would an average low, but episodically high flux.

! There is some evidence also that some materials for waste canisters may be more resistant to corrosion under episodic wetting and drying. Basically, it oeems best to address only a single concept or factor in a single statement j of condition. Also, change " overlaying" to " overlying."

i Section 60.122(b)(8)(ii): "A water table sufficiently below the underground facility such that fully saturated voids continuous with the water table do i

not encounter the underground facility." This condition has also been icproved over the earlier version, which depended on a rather inappropriate dafinition of " capillary fringe." However, it still appears to be incumbent l'

en the applicant to prove that there are no continuous pathssof water cccupying saturated pores--an impossible task. Ve suggest changing the i

favorable condition to read as follows:

l

"(ii) Conditions that preclude, or limit, capillary rise from the water table to the underground facility;"

I Lj This directly addresses the concerne expressed by the NRC staff regarding oiting a facility in the capillary ~ fringe but avoids definition of the l

tsem " capillary fringe."

Saction 60.122(b)(8)(iv): "A host rock that provides for free drainage; or . . . " We suggest that "or" should be changed to "and." ~

l Scetion 60.122 (b), (8),-(v): "A climatic regime in which the average

~ i canual historic precipitation is a small percentage of the average annual  ;

patential evapotranspiration." The term "small percentage" is vague and ,

i inappropriate, in our opinion. We suggest specifying an absolute value of cverage recharge as a maximum, perhaps on the order.of 50mm or less.

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... _ t, (@7 FL 393'{}

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. Feu.iene y Capital Area Groundwatpr.

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' Conservation Commission ,4 :.. ~

East

• • '*" P. O. Box 64526 i

w. Baton Rouge, Louisiana 70896-4526 '84. Apg 27 A10:52 f* Telephone (504) 924-7420 , . . .

") Oci[nfgyy'p;,,,"

April 23, 1984

BRANCM Sccretary of the Commission U.S. Nuclear Regulatory Commission lbshington, D. C. 20555 Attn: Docketing and Service Branch REF: NRC 10 CFR Part 60 Proposed rule Dace Sir:

Unfortunately my comments are being offered af ter the expiration of the comment period.

However, I believe the following practical comments extracted from U.S. Geological Survey Circular 903 titled, " Disposal of high level nuclear waste above the water cable in arid regions," are pertinent to the rafarenced CFR from the Federal Register of February 16, 1984 (v.49, no. 33).

"A major new concern would be shether future climatic changes could produce significant consequences due to possible -

rise of the water or increased flux of water through the If spent fuel were used as a waste form, a second repository.

new concern would be the races of escape of gaseous iodine-129 and carbon-14 to the atmosphere."

As NRC refer to the circular in the proposed rule, NRC has obviously considered these comments.

There is a discussion of vapor transport in the rules and the need for consideration on a case by case base of the problem in the Rules'Section,

" Issued examined by the Commission." Hopefully, the Commission's conclusion is satisfactory or is more in-depth caution required?

The requirement of a minimum depth of 300 meters may minimize to some l dagrae the effects of climatic changes? But there should be a required minimum prodatermined interval between the top of the water table and the bottom of ,

burici depth to prevent water entering the repository.

NRC has done an excellent job but 1 believe it is important to. reexamine thasa two factors and possibly reemphasize more specific safety criteria.

..y

S cretary of ,the Comission '-

U.S. Nuclear Regulatory Comission April 23,1984 '

Page 2 Thanks for' the opportunity to coment.

Very truly yours,

[

/ tb* -

. urcan, Jr.

Director ANT /ebo l cc: Dr. L. Hall Bohlinger 1

Pat Norton l -

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APPENDIX B b

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s934 Proposed Rules r+is+-

Vol. 49. No. 33 mrsday. February to.19a4 The sectaon of the FEDERAL. REGISTER sWPeLEseENTARY INsOstM ATl08n conta.ns nonces to the puche of the Background the site and the geologic repository D'000**d 'seuence of naes and design are carefully selected, and are

~9***'"'

• 8"'D*** 8' '" " "06C'8 t

On February 25.1981 the Nuclear capable of meeting the performance I Regulatory Commission (NRC)

,, $ 7 *,n*"nj, published a rule that established objectives of 10 CFR Part 60. In reachmg this determination. the Commission has

, aeung pnor to the sooooon of the ans procedures for licensing the disposal of examined the argu'ments presented by ruses.

HLW in geologic repositories (46 FR the public commenters as well as the 139M). NRC published proposed analysis of the principalissues technical enteria to be used in the associated with unsaturated zone evaluation of license applications under disposal desenbed in the NRC staff NUCLEAR REGULATORY those procedures on July g.1981 (46 FR COMMIS$3ON technical support document (draft 35280). In response to solicitation for NREC-1046) prepared in conjunction public commenta on the proposed with the proposed amendments. His

" technical enteria NRC received 93 document identifies the positive aspects comment letters. The Commission. and possible concerns associated with considered all public comments in disposalin the unsaturated zone and Disposal of H4h-Level Radioective developing the final technical criteria explains why the Commission has Castes in the Unsaturated Zone which wm published on June 21.1983 l developed the following proposed (46 FR 28194),

Aossect Nuclear Regulatory amendments. Other issues which were CommissiorL Seseral commenters on the proposed discussed by public commenters but rule, including the U.S. Department of which did not result in proposed Actioec Proposed rule. Energy (DOE), the U.S. Department of

_ changes to the final rule are also the Intenor, and separately the U.S. addressed in the technical support suusaAnn The Nuclear Regulatory Geological Survey (USGS). took issue Jocument. Upon publication. a copy of Commisuon (NRC)is considenns with a statement made by the draft NUREC-1046 entitled " Disposal of cmending its rules on the disposal of Commission at 46 FR 35281 which High Level Radioacta e Wastes in the high.les el radioactive wastes (HLW)in '*PI*i enten.ned that the proposed technical Unsatureted Zone: Technical geologic repositories so that the s were developed specifically for Considerations will be placed in the technical cnteria for geologic disposal in disposal in saturated geologic media Public Document Room. In7 H Street the saturated zona may be equally because DOE plans at that time called NW Washington.DC20555.Since this cpplicable to disposal within the for HLW disposal at sufficient depth to document is available to the general unsaturated zone. ne amendments are be situated in the hydrogeologic region public.: only a summary discussion of being proposed in response to public tenned the saturated zone.The these issues is presented below.

comments on the proposed technical commenters considered disposal in the entena for geologic disposalin the unsaturated zone 8 to be a viable Issues Examined by the Commission saturated zone. Final technical enteria alternative and noted that since the The depth to the regional water table cdopted by the Commission for disposal technical criteria were generally applicable without regard to the varies throughout the United States.

cf HLW in the saturated zone were Potential geologic repository sites within published in the Federal Registee on possibihty of saturation. their scope and applicability should not be unduly unsaturated geologic media may be June 21.1983. identified in arid to semi and geotrraphic restricted. DOE. In its commenta on this regions of the country because such oAtas: Comment period expires April issue. suggested that since opportunities 16.1084. Comments received after this may arise for exploratory studies in regions generally are charactenzed by a date will be considered if it la practical unsaturated geologic media, the deep regional water table and hence, a relatively thick unsaturated zone The ta do so. but assurance of consideration Commission should reexamine the rule cannot be given except as to comments and make whatever changes are unsaturated zone in certain and regions  ;

necessary to ensure that the rule will of the United S:ates has been receised on or before this date. l apply to all geologic media.The U.S. documented as extending to depths of i Aoonesssa: Send comments or Department of the Interior urged that the approximate!y 600 meters below the suggestiuns to the Secretary of the ground surface. In contrast. the Commission. U.S. N uclear Regula tory rule be modified because. under appropriate conditions the unsaturated unsaturated zone in humid reeions is Commission. Washington. DC 20535. often only a few meters thick, or entirely zone could provide one more natural Attention: Docketing and Service non-existent.

Branch. Copies of comments received barner to the movement of radionuclides from the geologic perhaps the most positive aspect may be exammed at the NRC Public repository to the water table. associated with disposal of HLW within Document Room. in7 H Street NW The Commission has determined that the unsaturated zone is that the HLW Washington. DC 20555. would be emplaced in a relatively dry disposal of HLW within the unsaturated zone is a realistic alternative to disposal (i.e.. low moisture content; geo!ag.c Fon runTwan teseonssAfiose costfacT:

Dr. Colleen Ostrowski. Office of Nuclear within the saturated zone, provided that ReIDlato'I Research. U.S. Nuclear e ,,,,,,g ,y ,,,,,,o,g g g % ,, g Regula tory Commission. We shington, 9"'d '*' P* ""***' h r **'""8 '**

8 The defimnon of the term "maseturered sene9ePublicanoe Semees Sect on. Dmaion demed from U s. ceolopui s.rvey wsie, supply of Tectfucal DC. 20535. telephone (301) 427-4343. Paper taas (wesenacea. DC. ter:L tatenenon and Document comerot L's N e.er Resuletory Comasseios, weeluncon D C. Jossa.

o

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1 Feder:1 Register / Vol. 49. Nm. 33 / Thursdty. February 16, 1984 / Proposed Rulis 5035

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medium. The Commission considers the with vapcr transport in the unsaturated geologic repository withm the relatively low moisture content of zone may also be discerned smce water unsaturated zone, sealing shafts and unsaturated sediment and rock as a vapor formed.near the geologic boreholes tightly to inhibit water positive aspect of HLW disposalin the repository may flow through air. filled movement may be undesirable. The unsaturated zone because the lack of openings and partially dramed fractures. reasoning behind this view is that cvailable moisture could reduce resulting in a drying of the surrounding teaching of the waste packages and although shafts and boreholes need to host rock. This drymg zone may extend be carefully sealed in the satursted zone thus, significantly reduce the likelihood hundreds of meters from the geologic c,f radionuclide transport by so that they do not become future repository, and thus may inhibit the conduits for radionuclide migration. they groundwater 8 migration. Further. it is movement of soluble contammants.

generally recognized that vertical may have an entirely different relation Therefore, the Commission views vapor to an unsaturated zone repository.

groundwater flux in the unsaturated transport as another issue which must zone is very small. A credible pathway Shafts and boreholes would increase the be evaluated on a case by. case basis to amount of water moving through a for the migration of water soluble determine its effects (whether favorable geologic repository located within the contaminants from a geologic repository or potentially adverse) on a particular located in the unsaturated zone to the site.

unsaturated zone only if they diverted a

(,', n'Y$",$, *I Other Comments Considered by NRC sigmficant amount of runoff to the subsurface.

underlyms regional water table, and The Commission has reviewed both The Commission has reviewed the subsequently through the esturated following six issues related to HLW the arguments of the USGS and the groundwater umts to the regional disposal within the unsaturated zone provisions of the final rule relating to discharge pomts. the design of seals for shafts and which were addressed in the u The Commission has reviewed several comments on tha proposed as we!! rufe,blic boreholes (i 60.134). The provisions of ether issues that are of general concern as in a recent USGS publication.* and I m34 appear to be gennaHy ta disposal of HLW in geologic applicable to seals of shafts and repositones.regardless of the has determined that the final rule (48 FR 2a194) accommodates these concerns. boreholes in both hydrogeologic zones.

hydrogeologie zone involved. Such Therefore, the Commission does not More detailed discussion of these issues issues include the effects of chmatic is presented in draft NUREG-1Mo. consider it necessary to modify i 60.134 changes on the regional hydrologic at this time.

systems, the potential for human um 30s. Meters Depth for Wsete intrusion into the geologic repository. -

Backfill Requirements and the effects of geologic processes One cornmenter on the proposed to Another issue which has been (03 tectorusm) on the structural CFR Part so technical critena who identified both in public comments on stability of the geologic repository.The advocated spplying the rule equally to the proposed technical criteria and in Commission does not believe that any of the saturated and unsaturated zones USGS Circular 903 pertams to the these issues would negate the generic concept of HLW disposal with2n the considered it necessary to change the necessity of backfillin a geologic siting criterion which sets a minimum repository located within the unsaturated zone. However, since the depth of 300 meters for waste relative importance of these issues will unsaturated zone. The USGS exprermed mnplacement. However, the commenter the view that the role of bacafillin the d; pend upon natural conditions existir:g ct a particular site each must be incorrectly identified this provision (see unsaturated zone would be the opposue evaluated on a site.by. site basis. i eo.122(b)) as a requirement, rather of that in the saturated zone. Backfill Vapor transport of contaminants has than as a favorable condition. The matenal that would inhibit the flow of been identified by the Commission's Commission notes that favorable water to. and radionuclide migration staff as a potential concern associated conditions are those which may enhance from. the waste packages may be highly with HLW disposalin the unsaturated weste isolation potential. Hence, a desirable la the saturated zone. In the zone. In unsaturated geologic media, minimum depth of 300 meters for waste unsaturated zone, however, the emplacement is considered a favorable designers of a geologic repository may water to transported in both liquid and vapor phases. The relative contnbution condition because the deeper the HLW wish to promote drainage. The opinion cf transport via Ifquid and vapor phases. is emplaced. the less likely it is to be has been expressed that within the and their direction of movement with disturbed. Viewed in that light this unsaturated zone backfill should allow depth is a favorable condition. groundwater to drain readily, rather respect to a geologic repository will Itve a direct influence on the irrespective of hydrogeologic zone. than serve as a barner to drainage. it containment of contaminants. Vapor Since the unsaturated zone may extend was suggested in USGS Circular 903 that transport, particularly when a thermal to depths of up to 800 meters, the if backfillis necesesry to perserve gradient is imposed may provide a Commission considers this favorable structural or waste package integrity, a possible mechanism for radionuclide condition to be a realistic one for both relatively permeable material (e.g migration from a geologic repository. the saturated and unsaturated 2nnes. cobble. sized rock) could be used to H: wever, positive aspects associated Therefore. this provision of the rule has permit continued drainage.

not been modified.

The final rule published by the e The comumes.on recoenase mai uw wm Requirements for Sealing Shafts and Commission on June 21.1983 contamed enmndwaw a senecou rereiwd try me techmeal Boreholes com unity to wetw abch owws bewee to only the general functional statement wow tatse ne_ phrunc w wWho me == that the engineered barrier system In USGS Circular 903 the view was gedoge rl (including backfill) be designed to assist gegpypgte ,*e expressed that, wi'h respect to a the geologic setting in meeting the wwen occw in uw wwerwered sone teone of secouen. vedoes seesI Howevw. for uw uke of

• Rosebeest F. R lr.1ses. Dupoul of Hish4ml performance objectives for the penod eunpucity. younJwever 2 denned in the preeeeed Nucleet weete Above the Weter Toble na And following permanent closure amendmente as e2.notot which occws beoew the pessone. LLS. Geoloescal Survey Carmalet so3. li 60133{h)* 48 Fat 28227).This tente ewtems. waameien. DC. p. 21. ,

provision, as promulgated, should be

5936 Feder:1 Regist:r / Vcl. 49. N2 33 / Thursday. February 16, 1964 / Propos:d Rul:s 1

responsise to the concems discussed }

a6cve. drier conditions and increasing worker unsaturated zor.e is generall>

safety by providing alternative sontces discontinuous and strongly dependent Waste Package Design Criteria of ventilation and escape routes. upon initial conditicns (e g.. magnitude As defined at i 60.2. the term " waste ne number of ventilation shafts and spatial and temporal distnbution package" means "the waste form and included in any geologic repositor) will recharge esents) and the conducta e be decided by the designer.--DOE. No properties of the partia!!y saturated any containers. shielding. packing and other absorbent ma tenals ammedia tely provision of to CFR part 80 espressly geologic media whach sary with surrounding an individual waste limits the number of ventilation shafts moisture content. Rehable calculatiuna container"(48 FR 2a:19). The point has that a geologic repository may contain. and predictions of groundwater travel .

been raised that because of the different Whatis important is that the surface times and velocities require knowledge nature of the emplacement environment facility ventilation systems comply with of these conditions and properties the design enters in i 60.13:lb)148 FR designs of waste package components Within the unsaturated zone the

s=6) and that the underground facility movement of a gnen volume of water for the saturated and unsaturated zones ventilation system be designed in may be gaite diffe ent.The Commission over a gisen distance dependa sery accordance with I eo.133(g)(48 FR recognizes that several charactensucs of :32:7).The Commission considers the strongly upon the nature of the recharge the emplacement environment (e.g., desegn reqmrements for the ventilation events. Additionally, the matenal oxidation conditions, lithostatic properties (e.g., moisture charactenstic systems set forth in il 60.132 and 80.133 pressure. geochemistry, contact with to be applicable to both the saturated curves, porosity, irreducible sa turation.

groundwater, etc.) may vary etc.) and the imtial conditions (e.g..

significantly between the two and unsaturated zones. As long as the ventilation system complies with saturation, capillary pressure. matric hydrogeologic zones. This variation of potential) may be extremely difficult to prodstons of Il 60.111(a). 80.132. and emplacement environment may measure on a representative scale for so.133 and does not compromise the necessitate that DOE consider unsaturated porous and fractured integrity of the site to host a geologic geologic media.

alternative designs for waste packages repository. DOE will have broad (including waste form. canisters, For these reasons, calculations of pre-flexibility in designing the system.

overpack, etc.) for geologic disposal in waste. emplacement groundwater traset the unsaturated zone. The Commission Faploretory Boreholes time along the fastest path oflikely has reviewed the performance radionuchde travel through the Provisions relating to site objectives which pertain to the waste charactentation are set forth in the final unsaturated zone may have large package (l 60.111 and I 80.113), and associated uncertaimties, and may be of rule at i 60.10 (48 FR 28219). Section believes that the provisions, as currently 60.10(d)(2) requires that the number of questionable value in estimating t'he westten, are equally applicable to waste exploratory boreholes and shafta be capabil ty of the geologic setting to packages emplaced withm either the limited to the extent practical, isolate HLW from the accessible saturated or unsaturated zone. Similarly. consistent with obtaining the endrcnment.

the spectfic design entene for the waste information needed for site The new definition of the term package andits components [l 80.133. " groundwater" which the Commission is charac*erization. The view was 44 FR :s::7) have been determined to be expressed in USGS Circular 903 that in proposing would have the effect of ee terally applicable to both zones.

the unsaturated zone,if the host rock expanding the scope of the performance Therefore. no channes have been made already has a high vertical permeability, objectives set forth in i 60.113 to to the provisions of Il 60.111,80.113. or disposalin either the saturated or 60.135 there is no reason to limit the number of drill holes. Thus, the USGS noted that if unsaturated zone. Similarly the cecessary. a proposed geologic proposed amendment to the Sitmg The issue of restricting the number of repository could be explored like an ore Cntens (l 60.122(b}[7)) would have the body or coal bed. with drill holes every effect of making pre. waste. emplacement ventilation shafts associated with a geologic repository was addressed in few hundred feet on a rectangular gnd. 8roundwater travel time along the The Commission's view on the fastest path of !ikely radionuclide trasel USGS Circular 903. In the case of the importance of not compromisms the saturated zone. the number of from the disturbed zone to the ventilation shafta may be kept at a integnty of a site during the site accessible environment which charac'erization program of testing and substantially exceeds 1.000 years a minimurn since the shafts could constitute potential pathways to the exploration has been clearly stated at 44 favorable condition for HLW disposal FR 70409. However,if DOE should opt withm either the saturated or eccessible enuconment. In USGS for a site exploration and unsaturated zone.

Circular 903 it is stated that in the case characterization program which cf the unaaturated zone additional The Commission's current thinking on includes plans for dnlling numerous this issue la that if DOE can demonstrate shafts for ventilation would not compromise the geologic repository *s boreholes then DOE would have the with reasonable assurance that travel burden of showing the Commission that time for groundwater movernent through performance because sealing shafts in this ability of the site to teolate HLW has the unsaturated zone can be quantified, the unsaturated zone is much simpler cnd ofless consequence than in the not been compromised during these then DOE should be allowed to melude activtties. such travel time when demonstratmg s turated zona. Several potential benefits were cited by the USGS to Grouodwater Travel Time in the compliance with i 60.113(a)(21 support this view-e.g. reducing the Unsaturated Zone However. such calculations of problem of thermalloed la the early groundwater travel times throueh the The concept of groundwater travel phases of the geologic repository, unsaturated zone could invcls e time generally is applied in evaluations removal of any water vapor durms the considerable uncertainty. Further. long operational period, drawing large of saturated flow systems. where flow is groundwater travel time possibly may continuous and temporal fluctuations in be inconstatent with the propesed amounta of desert air through the geologic repository to promote even the potential of the systems are small. In amendment which identifies a host rock contrast, water movement in the that provides for free dramase as a

. . 1 Federal Registir / Vgl. 49. No. 33 / Thursday. F:bru:ry 16. 1984 / Propos:d Ru!2s 5937 favorable hydrogeologic conditi6n for Ust of Subjects la to CFR Part 80 and low hydraulic potential between the disposal of HLW withm the unsaturated High level waste. Nuclear power st me any the surr undmg zone. it may be more appropnate for the hydrogeologic umts.

Commission to spectfy another plants and reactors. Nuclear matenals.

parameter upon which performance may Penalty. Reporting and recordkeeping be evaluated for a geologic setting in the requirements. Waste treatment and (7) Pre. waste-emplacement unsaturated zone, or to utilize the disposal. groundwater trase time along the fastest cpproach set forth in I ao.113(b) which path oflikely radionuclide travel from Issuance provides the Commission with the the disturbed zone to the accessible flexibihty to spectly variations m For the reasons set out in the environment that substant: ally exceeds performance objectives on a case-by- preamble and under h authority of h 1.000 years.

case basis, as long as th-e overall system Atonue Energy Act of1954. as amended. (8) For disposalin the unsaturated performance objective is satisifed. the Energy Reorganization Act of 1974 zone, hydrogeologic conditions that e P* i as amended. the Nuclear Waste Policy provide-

{to '

C asnisp]c14 Act i1982. and 5 U.S.C. 553. the (i) Low and neatly constar.t moisture seeking public comment on the following Nuclear Regulatory Commission la flu in the host rock and in :he questions. proposing the following amendments to overlaying and underlying

1. How can groundwater travel time in to CFR Part 80. hydrogeologic units; the unsaturated zone be determined (ii) A water table sufficiently below with reasonable assurance? Should the PART 30-DISPOSAL OF HIGH-LEVEL the underground facility such that fully groundwater travel time performance RADIOACTIVE WASTES IN GEOt.OGIC saturated voids continuous with the objective be limited to groundwater OSnomES water table do not encour.ter the movement within the saturated zone? Authority: Secs. 51. 53. 82. 63. 88. 81.181. underground facility:

2. Does groundwater travel time 1s2.183. OS Stat. 929. 93o. 932. 933. 935. 946. (iii) A laterally estensive low.

represent an appropriate measure of 953. 954 as amended (42 U S C. 2 ort. 2073. permeability hydrogeologic unit abos e performance for a site within the m2. m3. 20es. 2111,2m 2232. 2233t ucs.

the host rock that would inhibit the unsaturated zone. or would an 202. m as Stat.1244.124e. (42 U S C. 5842.

downward masement of water or divert citernative performance objective for the geologic setting. (e.3, maximum j'U*

• a* '

l02. downward moving water to a location likely volumetrie llow rate of L 91-190. s3 Stat. as3 (42 U.S C. 4332k sec. . beyond the limits of the underground groundwater through the geologic 121. Pub. L s7-423. 9s Stat. 222s (42 USC. facility:

2014k repository) be more appropnata? For the purposes of sec. 223 es Stat. 954, as (iv) A host rock that provides for free amended (42 USC. 2273). Il a0.71 to 80.73 drainsIe or (v) A climatic regime in which the EnytroamentalImpact Negadve are issued under sec. toto. es Sist. sea, u Declaration amended (42 UAC. 2201(o)). average annual historic precipitation is

1. Section 60.2 la amended by adding a small percentage of the average Pursuant to Section 121(c) of the annual potential evapotranspiration.

Nuc' ear Waste Policy Act of1962. the two new definitions in proper , , , , ,

promulgation of these critens shall not alphabetical sequence:

require the preparation of an ("I (60.2 Dennmons.

environmental impact statement under . . . . . (22) Potential for the water table to Section 102(2)(C) of the National nse sufficiently so as to cause saturation Environments! Policy Act of 1969 or any Groundwater means all water of an underground facility located in the envtronrnental review under which occurs below the Earth s surface. unsatursted zone.

subparagraph (E) or (F) of Section 102(2) " Unsaturated zone" means the zone (23) Potential for existing or future cf such Act. betwevn the land surface and the deepest water table. Generally, water in perched water bodies that may have the P;perwork Reduction Review this zone is under less than atmosphenc effect of saturating portions of the pressure, and some of the vcida may underground facility or providing a The proposed rule contains no new or contain air or other gases at faster flow path for radionuclide

. (mended recordkeeping, reporting or atmospheric pressure. Beneath flooded movement from an underground facility applica tion requirements. or any other areas or in perched water bodies the located in the unsaturated zone to the type of information co!! action accessible environment.

water pressure locally may be greater requirements subject to the Paperwork than atmospheric. (24) Potential for vapor transport of Reduction Act (Pub. L 96-511). . . . . . radionuclides from the underground

• Section 601221s ded b factlity located in the unsaturated zone Regulatory Memy Act Mcados

,,] sing paragEsph (b ( ) i i), des gnating to the accessible environment.

In accordance with the Regulatory paragraph (b)(2)(iv) as (b)(7), and adding Dated at Wuhington. D C tha 13th da> of Flexibility Act of1990 (5 U.S.C. 005(b. new paragraphs (b)(8). (c) (22). [23) and February 1984. j the Commission certifies that this rule. if (24) to read as follows: adopted, will not have a significant For the Nuctur Regulatory Commission. economic impact on a substantial I 60,122 Siung criterte. Samuel I. Chilk. number of small entities. The only entity S*ctary o/she commission. subject to regulation under this rule is (b) ' *

• tre ou una ma s.is.ae us ..l the U.S. Department of Energy. (2) * * * (iii) Low vertical permeability ou.ma caos ree .-=

l

Comments of the U.S. Environmental Protection Agency on the U.S. Nuclear Regulatory Commission's Proposed Rule for Disposal of High-level Radioactive Wastes in the Unsaturated Zone

1. 10 CFR 660.2 (Definitions)

NRC proposed to redefine the term " ground water" to include all water in both the saturated and unsaturated zones. This change apparently pro-vides a simple regulatory means for applying existing criteria written , several years ago for high level waste repository siting in the saturated zone to the unsaturated zone as well. While this expansion of applicabil-  ! ity may be reasonable, EPA would prefer that the NRC retain the standard scientific meaning for the term (i.e., water within the zone of saturation). We are concerned that confusion may eventually arise among the public, par-ticularly in their understanding of the application of methods of ground water monitoring.

                " Unsaturated zone" should be defined as the zone between the land surface and the shallowest free water table, discounting " perched" tables.

The definition written in the proposed regulation says, " deepest." This is confusing. The definition with " deepest" would be correct, however, if , the term " water table" were also defined as the potentiometric surface beneath the land surface at atmospheric pressure.

2. 10 CFR 460.122 (siting criteria)-

The Commission proposes to amend Section 60.122 by adding new para-graphs (b) (8) and (c) (23). There seems to be a conflict in the criteria outlined under portions of the two respective paragraphs. Paragraph (b) (8) (iii) requires that hydrogeologic conditions in the unsaturated zone pro-vide for "a laterally extensive, low permeability unit above" the reposi-tory to . inhibit downward migration of water into the underground facility. Paragraph (c) (23) presumably calls for the unsaturated zone to be free of the potential for " perched water bodies that may have the effect of saturat-ing portions of the underground facility." It seems that these are in conflict because the laterally extensive, low permeability unit encouraged to be located above the repository as outlined in paragraph (b) (8) increases the potential for the formation of perched water bodies immediately above the unit. Although the low permeability strata may serve to inhibit downward migration, it encourages the possibility of perched water bodies that may result in saturated flow conditions above and immediately surroundin t Conversely, paragraph (c) (23) g thediscourages limits of thesiting underground in areas repository. where the  ! potential for existing or future perched conditions exists. EPA recommends t that this inconsistancy be resolved.

                           +

E

3. With respect to the three questions on which the Commission particularly seeks comment:

4 Question: "How can ground water travel time in the unsaturated zone be determined with reasonable assurance?" EPA Reply: EPA's Office of Solid 0aste will soon publish Procedures for Modeling Flow Through Clay Liners to Determine Required Liner Thickness

• in its series of Technical Resource Documents. This manual presents a numerical simulation model to estimate travel time of water through unsaturated sediments. J0nce copies are available from GPO, we will forward one to Dr. Colleen Ostrowski at the NRC.

Measuring natural tritium (3 H) concentrations in ground water samples from a vertical profile in unsaturated geologic formations may be another technique for estimating travel time. Since the atmospheric testing of nuclear weapons, ground water recharge (i.e., precipitation) has contained levels of this radioactive isotope above the naturally low levels existing before the testing began. Consequently, tritium may 1 serve as an indicator or tracer of "new" water in a geologic per'ile, and thus may indicate approximate travel times from the rechargt~ point.- Question: "Should the ground water travel time performance objective be i limited to ground water movement within the saturated zone?" EPA Reply: No. To allow DOE to take credit for the delay in water reaching the water table afte'r passing an unsaturated zone repository. . (when considering NRC's existing 1,000 year " ground water" travel time requirement), NRC proposes to redefine the term " ground water" to include all water below the land surface, not just water below the water table, in the saturated zone. We do not think it is necessary to change the widely understood meaning of this term to accompish NRC's objective. EPA agrees that DOE should be able to take credit for any such delays in the unsaturated zone. However, it would be more appro- . priate to make the existing section 60.ll3(a)(2) apply only to reposi-tor.f as in the saturated zone and to add a parallel section for unsaturated zone repositories that allows the Department to add the water travel times in the saturated and unsaturated zones to compare against the 1,000-year time period. Even if NRC redefines the term 4

         " ground water" for 10 CFR 60, EPA has no plans or need to make a corresponding change in 40 CFR 191.                                         .

Question: "Does ground water travel time represent an appropriate measure of performance for a site within the unsaturated zone, or would an alternative performance objective for the geologi,c setting be more appropriate?" EPA P,eply: No, it does not. An alternative option should be available. , EPA does not believe titat such a " water" travel time is appropriate as the only quantitative measure of performance for a site within the I i

                    - - . - . - -         --   , . - , - - - - . . - , . - - ,        , - , . - , . . ~ , . - . . -n,- - , - --- -   . - - - , - - . --     ----- -.---

• 9 ee 9

ENCLOSURE E y a l

4 . . REGULATORY ANALYSIS 10 CFR PART 60 , 1. Statement of the Problem 10 CFR~Part 60 - " Disposal of High-Level Radioactive Wastes in Geologic Repositories," as currently written (48 FR 28194), was primarily developed for disposal of high-level radioactive wastes (HLW) within the hydrogeologic region termed the saturated zone. The provisions of 10 CFR Part 60 were originally directed towards the saturated zone because at the time they were being developed the licensee -- the U.S. Department of Energy (00E) -- was only considering potential repository sites at sufficient depths to be contained within the saturated zone. The saturated zone, as defined in , existing 10 CFR 60.2 means "that part of the earth's crust beneath the deepest water table in which all voids, large and small, are ideally filled with water under pressure greater than atmospheric" (48 FR 28218). Commenters on the proposed 10 CFR Part 60 technical criteria (46 FR 35280) viewed this limitation as unduly restrictive, and considered geologic disposal within the unsaturated zone to be a realistic alternative to disposal within f the saturated zone. Additionally, in its coment letter on the proposed techr.ical criteria DOE, noting that opportunities may arise for exploratory studies in unsaturated geologic media, requested that NRC ensure that 10 CFR Part 60 will apply to all geologic media. Since DOE may submit site characterization plans to NRC for potential repository sites that may be situated within'the unsaturated zone, it is necessary to modify the appropriate provisions of 10 CFR Part 60 in a timely manner so that the NRC may review license applications that may be submitted for geologic repositories within the unsaturated zone. The term " Unsaturated zone" as used by NRC means ".the zone between the land surface and the regional water table. Generally, fluid pressure in this zone is less than atmospheric pressure, and some of the voids i i 1 Enclosure E

may contain air or other gases at atmospheric pressure. Beneath flooded areas or in perched water bodies the water pressure . locally may be greater than atmospheric." J Existing provisions of 10 CFR Part 60 are generally applicable to disposal 4 within either the saturated or unsaturated zone. However, minor modifications are still necessary to ensure that the rule applies equally to sites in both j hydrogeologic zones. On February 16,1984, NRC published for coment proposed anendments to 10 CFR Part 60 related to the unsaturated zone (49 FR 5934). In response to its solicitation of public input on the proposed amendments NRC received 14 coment letters. These letters represented the views of other Federal agencies, States, representatives of industry ano public interest groups. In general these commenters were supportive of both NRC's decision to consider the licensing of HLW disposal in the unsaturated zone and the provisions set forth in the proposed amendments. The public coment letters l primarily addressed questions posed by NRC on groundwater travel time I calculations in the unsaturated zone, and suggested minor word changes for the sake of clarity and technical accuracy. The final amendments should not result in any additional costs to DOE, and will ! clarify the Comission's regulations concerning the licensing of HLW disposal in unsaturated geologic media.

2. Objectives The objective of the proposed regulatory action is to broaden the scope of 10 CFR Part 60 to cover licensing of the disposal of HLW within the unsaturated zone.

3. Alternatives (1) Leave the final provisions of 10 CFR Part 60 intact. (48 FR 28194)

(2) Develop an entirely separate rule to apply to the unsaturated zone. 2 Enclosure E

(3) Publish proposed guidelines for HLW disposal in the unsaturated zone as a regulatory guide.

4. Consequences

(a) Proposed Action

Publish final amendments to make 10 CFR Part 60 equally applicable to license applications for HLW repositories in both the i saturated and unsaturated zones.

The final amendments would provide NRC with the maximum flexibility with respect to reviewing license applications for HLW disposal with the minimum expenditure of time or money. The amendments were developed after considera-tion of the public comments received on the proposed 10 CFR Part 60 technical criteria (46 FR 35280). Many of the points raised by commenters with respect to modifying .10 CFR Part 60 to apply to both the saturated and the unsaturated zones were accommodated in the final technical criteria (48 FR 28194) in response to comments received on other issues. The final technical criteria were reviewed in light of these comments and the staff considered the minor mcdifications presented as proposed amendments (49 FR 5934) sufficient to make the rule equally applicable to reviewing license applications submitted for HLW ] disposal in either hydrogeologic zone. This view generally was supported by the public commenters on.the proposed amendments relating to the unsaturated ] zone. 1 The impacts associated with this action (i.e., promulgating the final amend-ments) are minimal. The impacts associated with disposal of HLW in geologic repositories within the unsaturated zone should be comparable with saturated zone repositories since the general performance objectives for the natural and engineered barriers apply to each hydrogeologic zone. The addition of the final amendments to 10 CFR Part 60 should result in no changes to the radio-logical safety consequences or to the impacts relating to safeguards, operations, economics, environments or general information collection associated with disposal in the saturated zone. Finally, the cost of the proposed action to NRC would be negligible. I 3 Enclosure E

I (b) Alternative 1: Leave the provisions of the final rule - 10 CFR Part 60 intact. As noted previously, public canments on the proposed technical criteria (46 FR 35280) requested that NRC modify its original decision to limit the technical criteria to HLW repositories within the saturated zone. Further, public comments on the proposed amendments published in February,1984 4 reinforced the view that disposal of HLW within the unsaturated zone should be considered. NRC received comment letters from the U.S. Department of Energy, U.S. Environmental Protection Agency, the U.S. Department of the Interior, and the U.S. Geological Survey supporting the concept of HLW disposal within the unsaturated zone. , Potentially, this alternative would have few associated impacts since it would not represent any change in the status quo. DOE could still file a license application for a geologic repository within the unsaturated zone under the , existing provisions of 10 CFR Part 60. In considering such an application NRC would need to determine if the proposed site conformed with the provisions of the technical criteria set forth in Part 60. However, certain of these

existing provisions may be technically inappropriate for an unsaturated zone 1

site and could result in inappropriate analyses of the site-specific data. l Therefore, this alternative could result in a certain degree of technical ambiguity which could complicate and delay the license review process. (c) Alternative 2: Develop a separate regulation for disposal of HLW within ! the unsaturated zone. 4 It would be possible for NRC to develop a parallel regulation to 10 CFR Part 60 I which would set forth provisions for disposal of HLW within the unsaturated , zone. This alternative would offer no preferred benefits to the proposed action, and would drastically increase the amount of time and money associated with this type of action.

Reviews of 10 CFR Part 60 by both the public commenters and the NRC staff indi-l cated that only minor changes to the final technical criteria are necessary to t

I 4 Enclosure E

                                                                              -,   ,_ -. - ,,-_         -_ -.--     . _ _ , . _ , , _ . _ . , - , ~ . . ~ - - - - _ . _ . - . _ . - - , . - . . -

7 ensure that the rule is equally applicable to HLW disposal in either the satu-4 rated or unsaturated zone. Therefore, the staff considers that there would be no justifiable reason for developing a new parallel regulation. . (d) Alternative 3: Publish additional criteria for disposal in the unsaturated zone as a regulatory guide. If this alternative were adopted, disposal within the saturated zone would still be comprehensively governed by the regulations of 10 CFR Part 60, while disposal in the unsaturated zone would need to receive additional guidance in i the form of a regulatory guide. There would be no legal requirements to be met in the latter instance. Therefore, the regulatory guide approach would not achieve the objective of equally applicable provisions for HLW disposal within both the saturated and unsaturated zones.

5. Decision Rationale The NRC staff has evaluated the proposed action and three alternative courses of action in light of the public comments received on the proposed technical criteria as well as the staff's review of the issues involved in disposal within the unsaturated zone. The staff prepared a technical support document

               -- draft NUREG-1046 which explored pertinent issues and presented a review of the provisions of the final rule - 10 CFR Part 60 with respect to these issues.

The public comment letters on the proposed unsaturated zone amendments (49 FR i 5934) and draft NUREG-1046 were reviewed in detail. Generally, the Commission's approach was favorably viewed by these commenters. Some changes and clarifications were made in the rule as a result of the comments received. Additionally, draft NUREG-1046 will be revised to reflect changes made as a result of public comments, and will be published as a final NUREG report. The final amendments contain provisions for modifying those sections of 10 CFR Part 60 related to the definitions, siting criteria and design requirements. The NRC staff considers the proposed action as the most direct and cost - l effective method of ensuring that the provisions of 10 CFR Part 60 are equally i applicable to HLW disposal within the saturated and unsaturated zone. 2 i j 5 Enclosure E i I

_ m . _ . l e o ENCLOSURE y j

     # on aerg'o,                             UNITED STATES 8         ~ 7,                  NUCLEAR REGULATORY COMMISSION 2    ^

nE ADVISORY COMMITTEE ON REACTOR SAFEGUARDS E [ WASHINGTON, D. C. 20S55  ;

       *****                                       August 14, 1984 honorable Nunzio J. Palladino Chairman                                                                '

U.S. Nuclear Regulatory Comission

                              ~

Washington DC 20555

SUBJECT:

ACRS COMMENTS UN PROPOSED AMENDMENTS TO 10 CFR PART 60,

                            " DISPOSAL OF HIGH-LEVEL RADI0 ACTIVE WASTES IN GE0 LOGIC REPOSITORIES" During its 292nd meeting, August 9-11, 1984, the Advisory Comittee on Reactor Safeguards discussed the amendments proposed by the NRC Staff to expand the coverage of 10 CFR Part 60, " Disposal of High-Level Radioac-tive Wastes in Geologic Repositories," to include disposal             in the unsaturated zone.       This matter was also a subject of discussion during meetings of our Waste Management Subcomittee on July 11 and August 8, 1984.                                                                           ,

In presenting the proposed change to the ACRS the hRC Staff stated that the expansion in the scope of 10 CFR 60 to include disposal within the unsaturated zone should not be interpreted as meaning that they favor the disposal of high-level wastes in this zone. The NRC Staff is simply recognizing that disposal in the unsaturated zone is a possible alterna-tive to disposal in the saturated zone. The only matters on which we had questions were the definitions of certain terms in the proposed amendments. We have been informed that the NRC Staff intenos to modify the proposed amendments to address these matters. We concur in the amendments as modified. Sincerely,

                                                                /

l W ' vbJ Jesse C. Ebersole Chairman

References:

1. Draft memo for the Comissioners from William J. Dircks,

Subject:

10 CFR Part 60--Disposal of High-Level Raoloactive Wastes in Geo-logic Repositories--Final Amendments, transmitted to ACRS July 2, 1984

2. U.S. Nuclear Regulatory Comission, " Disposal of High-Level Radio-active Wastes in the Unsaturated Zone: Technical Considerations,"

Draft USNRC Report for Coment, NUREG-1046, dated February 1984 ctrmanne r

Honorable Nunzio J. Palladino August 14, 1984

3. Note from Colleen Ostrowski, Waste hanagement Branch, Division of Radiation Programs and Earth Sciences, RES, to R. C.-Tang, ACRS,

Subject:

Revisions to Draft 10 CFR Part 60 Final Amendments Related to Disposal of High-Level Radioactive Wastes in the Unsaturated Zone dated August 3, 1984 , i e r ii 2 l \ i l \ f l \

udJ , h e ENCLOSURE G 4 CE c l I t

   -          '~'# % -     _

3 DRAFT CONGRESSIONAL LETTER

Dear Mr. Chairman:

Enclosed for your information is a copy of a notice of rulemaking to be published in the Federal Register. On February 16, 1984 the Commission published for public comment proposed amendments to its regulations on the disposal of high-level radioactive wastes (HLW) in geologic repositories (49 FR 5934). The proposed amendments were developed to ensure that the provisions of 10 CFR Part 60 would be applicable to HLW disposal within either the saturated or the unsaturated zone. The Com-mission received fourteen comment letters in response to its solicitation of public input on the proposed amendments. These commenters generally supported both the Commissidn's decision to expand the scope of.its regulations and the provisions of the proposed amendments. The Commission made several changes and clarifications in the amendments as a result of the comments received. The Commission will continue to keep you informed of future rulemaking actions in the area of HLW disposal in geologic repositories. Sincerely, Robert B. Minogue, Director Office of Nuclear Regulatory Research 4

Enclosure:

As stated t 1 Enclosure G

e f AB44-2 4 Fed:ril Regist;r / Vol. 50. No.140 / Monday. July 22. 1985 / Rules cnd Regul:tions 29M1 l action, request reconsideration of the 9 Part 1421 is amended to add a new an editonal change to the listmg of action and present to the Director. i 1421.5559 to read as follows: transportation lmes. KCCO. in wntmg. information in support in accordance with,5 U.S C. 605(b) the of such request.The Director shall 55 OM " " ' Cornmissioner of Immigration and I ccnsider such information m making a {a2 n P mo em Naturahzation certifies that the rule wi!! 4,t determination and notify the not have a sigmfacant impact on a warehouseman in wntmg of such The information collection substantial number of small entities determination. The warehouseman may, requimments contained in this i This order constitutes a notice to the if dissatisfied with the Director's n'Su!ation (7 CFR Part 1421) have been pubhc under 5 U.S C. 552 and is not a determmation, obta:n a reuew of the approsed by the Office of Management and Budget under provisions of 44 U S C- rule withm the defmitmn of section 1(a) determmation and an informal heanns of E O 12291. thereon by fihng an appeal with the Chapter 35 and have been assigned OMB Numbers 05604009 and 0500-0036 List of Subjects m, 8 CFR Part 238 Deputy Administrator. Commodity Operations. Agncultura! Stabibzation S gned at Washmgton. D C. on lu!) 1 Airhnes. Abens. Gosernrrent [ and Consen ation Senice (hereinafter 1985 contracts. Tras el. Tras el restriction referred to as "ASCS") The time of Eserett Rank. Accordmgly. Chapter I of Title 8 of the g fihng appeals forms for requestmg an Eiecutne %ce President. Commodsr> credst Code of Federal Regulations is amended erpeal. nature of the informal heanng cmo.ut an as follows-g determmation and reopenmg of the p Doc 8517383 Filed *-1%85. 8 45 arr! heanng sha!! be as prescn!'ed in the a m ocoor meas.a. PART 238-CONTRACTS WITH ASCS regulations governmg appeals. 7 TRANSPORTATION LINES CFR 780 When appeahng under such -- - - - - ~

1. The authonty citation for Part 238 reFu!ations the warehouseman shall be DEPARTMENT OF JUSTICE considered as a partic: pant : and continues to read as follows:

(2) In i 1421.5552(c)(21. the immigration and Naturalization Auth nty: Secs 103 and 23a of the w arehouseman's admimstratne appeal tmgran n and Nationality Act. as amended Serv 6ce . r:ghts with respect to suspension and (8 M 1103 and 12:8). l deba ment shall be m accordance with 8 CFR Part 238 g 238.2 ! Amended) i apphcable CCC regulations. After ^ Contracts With Transportation Lines; 38 and 4 i espiration of s penod of suspension or deba ment. a warehouseman may, at Addition of Skystar International, Inc. g '["' "d**[ a any tirne. apply for approval under this ActNcy: Immigration and Naturalization S:gratorylines is amended by Adding

  )r            scbpart Senice. Jus tice.                             in alphabetical sequence. "Skystar 8 Section 1421.5558 is resised to read                                                 International. Inc."

as follows. AcnoN: Fmal rule. i 1a21.sssa contract fees. suvuAmy:This rule adds Skystar Daied lu!y to 19a5 l g , Intemational. Inc. to the hst of carriers Menin i Gibson.

                                                                          '"             8 8" * '          Aerms Assocmre C mmissever, non-Federally bcensed Frain or rice y                                     wtth the Serytce to guarantee the             Encmmations imm:gmtion and
 $                    pe t e        ee en wih      C for     i      ediate and contmuous transit of        p Doc. 6%272?a Filed 7-tus. 8.45 am!

1 warehouse exarnmations must pay an 8 es t gn cmmtm coe, m, ,, annual contract fee to CCC for each . such warehouse which is approsed by ament oATE: July 3.1985. CCC or for which CCC approvalis FoR FURTHER INFORM ATION CONTACT

• sought as follows Loretta J. Shogren. Director. Pohcy NUCLEAR REGULATORY t (1) A warehouseman who has an Directis es and Instructions. Immigration COMMISSION

 )             esist>ng agreement with CCC for the           and Naturalization Service. 4251 Street 3             storage or handimg of CCC-owned              NW Washington. DC 20536. Telephone.            10 CFR Part 60 commodit:es or commodities pledged to        (202) 63b3048.
 >             CCC as loan collateral must pay an           SUPPL 1sstNTAAv INFORMADON:The                 Disposalof High-LevelRadioactive te           annual contract fee for each warehouse       Commissioner of Immigration and                Wastes in Geologic Repoeftories
  ~

approved under that agreement in Naturahzation entered into an Aotwcy: Nuclear Regulatory advance of the renewal date of such agreement with Skystar International. Commission. agreement. Inc. on July 3.1965. to guarantee passage ,,.pg g'

• through the United States in immediate (2) A warehouseman who does not I have an existing agreement with CCC and contmuous transit of abens destined suMMAny:The Nuclear Regulatory for the storage and handhng of CCC. to foreign countries. Commission (NRC)is amendmg its o owned commodities or commodities The agreement provides for the regulations for the disposal of high level 0 pledged to CCC as loan collateral but waiser of certain documentary radioactive wastes in geologic 6 who desires such an agreement must requirements and facihtates the air repositones. These amendments will a pay a contract fee for each warehouse travel of passengers on international ensure that the rule contains specific i for which CCC approval is sought pnor fhghts while passmg through the United enteria for the disposal of high. level
• to the time that the agreement is States. radioactive wastes within the approved by CCC. Compliance with 5 U.S C. 553 as to unsaturated zone. This action is (b) The amount of the contract fee notice of proposed rulemaking and necessary to assure that NRC shall be determined and announced delayed effective date is unnecessary regulations address considerations V annually in the Federal Register. because the amendment merely rr.akes relevant to all geologic repositories.

l l

f

. 29642             Fei$eral Register / Vol. 50, No.140 / Monday. July 22. 1985 / Rules and .Pegulations wh2ther sited in the saturated or              contained a discussion of the prmcipal            from the dicturbed zone to the unsaturated zone.                              techmcalissues considered by the                  accessible environment which EFFECTtVE D Aft July 22.1985.

Ccmmisston dunng the deselopment af substannally exceeds 1.000 years a j the proposed m.cndments. favorable condition for HLW disposal Fon FunTNEA LNFOmatATIO8e CONTACT: w thm either h .drogeologic zone. Dr. Frank A. Costanza. Office of Nuclear Summary of Comments and Changes 3 Rrgulatory Research. U.S. Nuclear . A total of fourteen groups and w cco pan p s Regulatory Commtssion. Washmgton, mdividuals commented on the preposed amendments. the Commission discussed DC 20551 telephone (301) 427-4362. amendments and draft NUREG-1048. possible limitations of the pre-waste-sNwem permTiow-There was general acceptance of the emp acement coundwater trasel time Commission s view that disposal of performance objectise of I 60113 when Background HLW withm the unsaturated zone is a applied to the unsaturated zone. j On February 25.1981. the Nuclear However. the Commission stated that if i

                                                   ' ' "

• c uld demonstrate with reasonable }

Regulatory Commission (NRC) addressed th mm?s n sp cific promulgated a rule that estabhshed ' " ' ' ' ' ' ' * * ' ' ' ' """ I # questions on groundwater travel time <r undwater mosement through the procedures for hcensing the disposal of withm the unsaturated zone and unsaturated zone can be quantified. then high-level radioactive wastes (HLW) m provided additional comments '" ' '" geologic repositones (48 FR 13971). NRC suggestmg word changes to impros e the trasel time when demonstrating promulgated techmcal entena to be technical accuracy and clanty of the used in the esa!uation of heense proposed amendments. The pnncipal " M "" I" #I Commission also acknowledged that it 4pplications under those procedures on comments received on the questions and may be more appropnate to specify luna 21.1963 (48 FR 18194]. Although proposed amendments. and the an ther parameter upon which these techmcal cntena are generally Commission s corresponding responses. , perf rmance may be esaluated for a appropr: ate to disposal in both the are discussed below Changes and ge ! gic setang m the unsaturated zone.  ; saturated aad unsaturated clarifications made m the rule as a rt use the approach set forth in hydtcgeolome zones acme fur'her resuit of the Commission's considerstion i tio 113(b) which presides the l f these comments are also eitplained in I distmctions need to be made for Commission with the fleubility to disposal in the unsaturated zone. this section. Copies of the mdividual specify vananons m performance eners ' 'i' Conse .uet:tly. Se Commission e-pressed its mtent to issue specific Qen , ,, b y NC fa oNectives on a case-by-case basis. as I ng as the oserall system performance as ailable in the NRC Public Document technical cntena for the unsaturated Room.1717 H Street NW.. Washington. biecnve is satisfied. Further. the zone after promJgatmg the final DC 20555. Commission observed that calculations . r echnical cntena so as to afford furder of pre waste. emplacement groundwater opportumty for public comment on this /a/ Crourdwcrer Tras e/ Dme trasel time along the fastest path of

  .ssue. Proposed amendments to these             Calc 2!chon8                                      hkely radionuchde travel through the technical cntena to include HLW                     Techrucal cntena stovernmg the post.          ur. saturated zone could insolve disposal wi$m either the saturated or           emplacement performance of the                    considerable uncertainty, and thus unsaturated zone were pubbshed for              par'icular ba ners of the and geologic            requested public comment on questions comment on February 16.1964. These              repository system (i.e. engmeered                 related to the applicability of the prcposed amendments contamed                    barr:ers and geologic sett:ng) are set            emtmg 10 CFR Part 60 performance prosisions for new definitions and              fcrth at i 60.113 (48 FR 28224. lune 21.          objectne for the geologic settmg to sites 1983). The post closure performance               located in unsaturated geologic media.

favorable and potentially adterse sitmg ct: ten 1 In addition to the proposed cntenon fer the geo!cgic settmg set forth in response to this so!icitation of public at i 60.113:a)(2l requires that the comment. sesen of the fourteen ar endments. the Cornmission commenters specifically addressed the speufically requested pubhc mput on gC gic repositor) be located so that pre waste-emplacerr.ent groundwater quest: ens on groundwater travel time two questions related to groundaater calca!ations. These questions and the travel time al ng the fastest path of tras el time calculations within the siews espressed by the seven likely radionuchde trasel frorn the unsaturated zone. In cortjunction with commenters are resiewed below. disturbed zone to the accessible the proposed amendments. the . environment be at l east 1.Ono years or The notice of proposed rulemakins Commisu t put>hshed for public such other travel time as may be f.rst requested comment on how comment draft NUREG-1046 8 w hich approsed or specified by the groundwater trasel time in the Commission. Although no change was unsa'urated zone could be determmed

      ' Oraft Ni' REG-10 6-Crevsd Mah late /      made elphCitly to the provision 3 of              with redsof'able assurar1Ce. Comments
  &;a .swa a m .o me nsuces zuc.                   I 60113(a)(2iin the proposed                     received .n response to this question r- % c.r,, s, urur, is wmnris s ,.ns r,"*J     amendments for the unsaturated zone,              were daided nearly equally into two o ~%t cNn,. m.de in rhe . men.hrents io to                                                        ca'esories. The first group of the proposed definition of the term r               r s          ,    ,$,4. 1roundwater" set forth at i 60 2 would            commenters antued that presently it 4 mov .2r warc to.e mit de pi.e.,d .n rw,       c!early make the scope of I 60113(a)(2)           would be difficult to calculate cmma , wi< omm,ni n,,om toon                    apphcable to aeologic repositones                 coundwater trasel time in the sucem comes of watc-ta.e mo 8,                  withm either the saturated or                     unsa'urated zone with reasonable r# N*d by c ihre imm mwo >r % anwa o            unsaturated zone. Strru!arly, the                  usurance because of the lack of
  +, uhr emn s,ruce, su i.on om.'"" "'                                                              generally accep'able methodology md preposed amendment to the Siting wh"o        nY s.

y Critena il 60122(b){7]) would hase the effect of makmq pre waste-emplacement the limited scope of research efforts currentl) desoted to this question. A

  ;t'515 vr purdased from de Netoral T= bmral aformemnc rm o,p.r m,nr or om.m-, sas groundwater travel time along the                           second group of commenters. compnsed P rt Nul Road Sortnuf.,6d. VA 2:161.            fastest path oflikely radionuclide travel         predominantly of representatnes of
                                                                                                                                                     ,L

i Feder:1 Regist:r / Vol. 50. No.10 / Monday luly 22. 1985 / Rules and Regulations 29643 other Federal agencies. endorsed the comments received on this question. the accesobic environment will also be g

                ,   opmion that groundwater trasel time       Commission beheves it is feasible for     largel> accommodated by the defimtion could be determmed with reasonable        DOE to demonstrate compliance with        of the term "groun6ater" m ( 60 2 assurance. One of these commenters        the groundw ster travel time provision. With respect to the view espressed that indicated that groundwater trasel time    usmg custmg fiek! and laborator3          the approach set forth m 5 60113(b) ma) calculations could be made by             espenments Further, as several            be particularly appropnate m the case measunng the amount of natural tntium     commenters indicated. a substantial       of HLW disposal m the unsaturated ed                  in the groundwater samples from a         effort is currently underway to deselop   zone. it should be noted that in those s ertical profile in unsaturated geologic new methodologies and to improse          instances when groundwater travel timo formations. Two other commenters          eustmg techniques for measunng the        calculations cannot be demonstrated

=n stated that groundwater travel time hydrogeologic parameters and flow with reasonable assurance. the could be denved from g oundwater flus properties that will proside the Commission may prefer to specif> or if using measurements of ambient water necessary imput to groundwater tras el approse alternatn e performance ble . content. degree of saturation. matnc time calculations For esample. it was oblectnes pursuant to 160113(b} l potential and h3 draulic conductivity to noted that in-situ monitonng techniques. In its second ouestion related to { determine moisture-charactenstic mcluding tracer tests, are undergomg groundwater travel time the Commisuon ten t cunes relatmg these parameters to one deselopmeid and may broaden the sought pubhc comment on whether

h another. These cunes can be deseloped range of rock types and conditions for groundwater trasel time represented an se as to predict constituine which it is feasible to estimate appropnate measure of performance for i relationships oser a wide range of groundwater velocity and hence. a site within the unsaturated zone. or t . conditions From these relationships and groundwater travel time. whether an alternata e performance flus determmations these commenters The second part of the first question objectne for the geologic settmg would argued that groundwater velocities and on which the Commission sought be more appropnate The views subsequent!) g~oundwater travel times comment centered on whether or not the espressed by the commenters were

>e. could then be estimated One of these eusting groundwater travel time nearly equally divided on this issue two-commenters further stated that performance oblective m 9 601131a)p) Some of the commenters asserted that. reasonable assurance may be gained in should be limited to groundwater although not ideal. the groundwater

                  . estimating groundwater trasel time        mosement within the saturated zone.       trasel time provision may. under certam usmg results of laboratory testmg. state- The general consensus among               circumstances. represent an appropnate of-the art direct determmations in the    commenters on this issue was that there   measure of performance for a geologic e                   field or laboratory. and boundmg          is no reason to stnctis hmit the
                                                                                      ~

settmg m the unsaturated zone. Other estimates developed by mdirect groundw ster travel time performance commenters argued that groundwater ss methods. while both commenters objectae to water mosement in the trasel time was not an appropnate er mdicated that reasonable assurance saticated zone. Followmg a review of performance obiective for HLW dispoul may also be gamed by mcorporatmg the discussions presented m these withm the unsaturated zone and uncertamty anailses mto predictive comments the Commission has suggested seseral alternative models determmed that the groundwater trasel performance oblectives. as discussed The Commission rec.gnizes that pnor time prousion (l 60113(a)(21) can be below. a to the commencement of HLW disposal apphed to a geologic settmg located m With respect to alternatne studies most groundwater mvestigations either the saturated or unsaturated zone performance requirements. one m unsaturated geolog:c media were The Commission could discern no commenter considered it unacceptable 25 generally hmited in secpe to issues obuous adsantage for developmg a to estabbsh an alternatne performance l related to near surf sce. highly porous parallel prousion for the unsaturated measure for unsaturated geologw media e i soils and unconsohdated , ock types zone as one commenter suggested. With while usmg a different measure for a Efforts to predict groundwater respect to another commenter's concern saturated salt site. The Commission mosement through potentially suitable that if the Commission decided to retain anticipates that the decision to apply the i geologic repository sites withm the the groundwater tras el time provision. groundwster travel time prousior to all unsaturated zone often entail the trasel time along an.s segment of the geologic settings regardless of the application of hydroseologic theories. flow path. mcludmg the unsaturated hydrogeologic zone m which the site is i models and methodologies goserning zone. should be creditable, prouded located should alleviate this I near. surface. porous media to much that reasonable assurance has been commenter's concern Another deeper hydrogeologic environments and demonstrated. the Commission has commenter stated that although different rock properties than they concluded further that the defmition of groundwater travel time substantially

           .        ongmally were designed for.The            the term " groundwater" set forth at      escredmg 1.000 years is a favorab!c Commission reahzes that given the           i m2 will allow trasel time along        condition. it is not appropnate as a current state of groundwater              subsurface flowpaths to be considered     totally definitn e performance objectn e e         msestigations there may be difficulties   regardless of the h3 drogeologic regime   for disposal m either the saturated or associated with groundwater tras el time tritough which the water is movmg As       unsaturated zone However,in view of e         calculations in both the satura'ed and    defined   m i 60 2. " groundwater" means   I 601131b). the groundwater tras el time
          ;         unsaturated zones. as one commenter       all water which occurs below the land     performance objectne is not such a obsersed Howeser. the Commission           surface The Commission beheses that       ~ totally defmitne" objective. The same j         concludes that g*oundwater travel time     the concerns of one commenter that it     commenter considered release enteria

calculations can be determmed in the would be inappropriate to limit as the absolute measure of total

& , unsaturated zone. though not groundwater trasel time to the saturated performance and further argued that necessanly with great precision. zone because such an action would not realistic estimates of release cntena for e prouded that the proper lesel of site accurately mdicate the actual the unsaturated zone might not be d g charactenzation analysis is conducted radionuchde transport time from the possible until observations are actually Followmg a detailed study of the onginallocation of the waste to the made m shafts and dnfts in response l i t

29644 Federal Register / Vol. 50. No.140 / Mond:y. July 22. 1985 / Rules c.nd Regulations . f" the Commission would note that the site i 80113(bt the Commission already has mdependent of any mteraction between these natural barners and the I charretenzation proteam would include the fleubthry to approve or specify such obsen,at: ens. One commenter some other radionuchde release rate. engmeered barners- i ndicated that if NRC chose to retain the des:gned contamment penod, or pre- The citistinit pre-waste-emp lacement I groundwater travel tune performance waste-emplacemeat groundwater tras el aroundwater travel nme pnmsion C obtectne that ttus provmon should only time on a case-by-cJise basis. Futher, the (l 60.113(a"U)is such a performance i'. be applied if the travel nme calculations Comnusnon anticipates that areally standard smce it is charactensuc of the ' include combtned travel times a the integrated or averaged groundwater area outside of the d:sturbed zone unsaturated and saturated zones so as flow selocity referred to by this same created by underground facility 1 h. to b:tter approumate radionucitde commenter wt!! be addressed m the construction v d wiste emplacement 1 .,' transport. The Commas on conside's es aluation of uncertamnes surroundmg operations. This prameter s :ot  ! i the concerns of this commenter to be the aroundwater travel time calculations. dependent upon the effects of waste [ accommodated by the defimtion of the emplacement ard is mtended to proude c term " groundwater" adopted in the final in add:nca, to a performance ct: tenon assura,ce chso'atmn beyond the first r. amendments. based upon groundwater ilux. other 1000 *, ears The Commisston prefers the a Most commenters who argued agamst a;ternative performance criteria wem eustmp grouadwiter travel time n the application of the groundwater tn its dprovision. which is part of its mdt:ple s discussed by commenters. origmal comment letter on the DOE. propose t-avel time performance obtectne to bart:er approach. to the alternative p unsatura'ed geologic media generally amendmenta npressed general support performance objective suggested by f { suuested alternauves based either on for a pertormance entenon based upon DCE since the latter does not of'er a  : s i the bydrwec!xic ccncept of ihn or groundwater flux. but in an addemdum rneasure of per'ormance for the geolegic 4 gen se case cy-case approach of to this letter conduded that it wetJd be settmg that can be evaluated # t c tt3(b). e practical to define a performance independently of desian and engineering

      \s .ie-n ed fmm l' S. Geolcaical        obtectne for the geeitgic setting based             factors. Further. the ph sical pa'tameters Sme> Water seno!v Paper i e the             on b through a teoiegic repository                  needed to evaluate pre-waste-                            I i      t term g oundwa cr flux" can ce defined       ! cated m the unsaturated zone. Instead. eMament edi: ems of the geciegic as 9e rate ofisct: arse of groundsater      DOE took the positicn sat an                         setting can be acctzrately meast. red with         i i

eematne perfermance objectise direct and mdirect field methodology. ' per umt area of porous or fractured ' 4ealogic media measured at rutht anales desemped upon the concept of a The DOE suggesuon wotdd

  'o se d: rec *mn of ficw. In companscn. ntramum time for poundwater travel to                                                                          +

necesmate dat numatn oMonenn g

  'he term ' groundwater

• ras ei time" used the accessible enuronment based on ped nn nce of the geclocc settmg m to CFR Part 60 can be mterpreted as faa separate physical esents would be more appropnate for the unsaturated eder post.waate4mplacement , ,

the tensth of t:=e requ: red for a urut andati ns be used m the Commission s salune of aroundwater to trasel zone. The four p5)sical e.ents dehberations on whether the between two :ocatmns. 2dte-natn es ccntamed in the suraested DOE groundwater trasel time performance sugested by the ecmmenters wh2ch al'ematne perictmance objective are bjective a met. The uncertainuea were based upon the concept of flax 11; The creation of a drymg zone around , associated with such esuma'es can be included a macinu:n youndwater '!ux the emplaced wastes. p) se subsequent affected by a nwnber of factors. requ:rement and a dual"either/or" return of mo:sture to the rock mcMW 6e age ar.d nam d se  ; cr' tenon which would allow the sar canding the waste canisters. (3) the waste and the design of the underground g apphcant the opt:en of demonseating trasel time through the unsaturated zone facility. Esaluations of the perfctmance i compliance with either a mimmum and finally. [4] the travel time to the accessible erwarrinment by groadwater of de geoicg:c setteg under post-waste- { groundwa'er trasel time requiroT.ent or emplacernent condition must also take t a maximurn poundw ster Cux tr:osernent th*uugh the saturated zone. mto acccunt pretactions of future . t requirement After considenng the The manner in which these or cnanges in the thermemechattical. , possibthtv of an alte:r.at ve performance possib y other events may occur withm ge themical and hyaregeologic s objectne based upon the maumum the geologic repository system will t prepert es of ie aeologic settirg through groundw cer Cux. the Commission has depend upon tne mterscuor.s of a ( decided to retam 'he coundwater trasel numbar of site- and design-specific hme as a roult of the uraat:on of a non-is thermal environment due to waste - r:me requirement ict geologic ,ettmgs parameters such as the thermomechamcal and hydroseologic emplaemeitt. The Cctr:mssion's uew is regardless of the hydrogeologic zone m that the present emphasis on pre-waste-which they ve located. This decision prcperties of the host rock thermal emplacement conditions wdl provide a w as based on the Commissioni behef h>admg of the underground facihty and waste packaae design. However as W bd*"** that the roundwater travel time U".nu*ed cont isolatian capabihties of the requirement represents an independent noted at 48 FR 2.81.03. tne Commission natural barriers of the geologic settmg measure of t! e oserall hydrogeologic beheves tha' tt is smportant to consider sistem performance which may both natural and enameered barriers

                                                                                                    ""     b D **

The siew was also aspressed by other encompass a vanety of hydrogeologic indnidually and has' structured the ccmmenters that the devalopment of a parameters mciuding groundwater flax. technical cr:teria of to CB Part 60 m a new alternatne performance ob lective Howese.. the Carnmission expects that way that requires that the natural and sraundwater ilux will be an important eng.neered barners each make a - to wsta 1 % U MQ may w be necessa y smce me Ccmm:ssicWs factor in tne technical evaluation of deftmte contnbut:on to the overall system performance cb;ecuve for the approach set forth at $ no.h3lbl right radionuchde eleases in the unsaturated be a more appropnate means of zo is. as weil as in the saturated zone. geologic repository. To that end the Commissfon considers it important to specifHng uternanves to the The Commission does not consider it necessary to specify a dual'*etthee/or' mairitain a standard of performance for droundwater travel nme criten. n. The groundwater cntenon sugg !cd by one the geologic settmg that is a measure of Cammission notes that it is essentially followmf th's appaoach m its decismn to commenter smce under the preestons of the quahty of the naturai barners and is

                                                                                                                                          -      - A b-

Fed;ral Registir / Vol. 50. No.1(3 / Monday. July 22. 1985 / Rules end Regulations 29M5 l m t en retam the esistmg provisions of commumty.Therefore. the Commission internalconsistency with the defimtions,

                ,  l CA113(alt 2) and i 60.113(b).             has not actually redefmed the term            of hydrogeologic terms presented m i       Followmg a review of the vanous        " groundwater" as one commenter               USGS Water Supph Paper 19M alternative performance objectives          suggested but rather has adopted one of       whereser practicable and for this reason suggested by the commenters, the            the commonly used defmitions of the           has not adopted any of the alternatne Commission considers groundwater            term that is most consistent with the         defimtions of the term " unsaturated trase! iime to represent a more             Commission's intent concerning the            zone" suggested by the commenters appropntdc parameter upon which the
                                                              .prousions    related   to regulation.

groundwater (d/ Favorchle Siting Cond;twns Wi . th performance of the geologic setting can throughout the Part 60 be esaluated than any of the suggested respect to the differences between the Section (4122(b)(2). The term " low alternatives because a prescribed defmition of the term " groundwater" hy drauhc potential" has been replaced grocndwater trasel time can be adopted by the Commission and that with " low hydrauhc gradient" m

               ,   generically applied and will provide a      proposed by EPA. the Commission notes i 60122(b)(2)(m) as suggested by one de           .

conservative estunate of a minimum that it does not consider the two commenter for the sake of techmcal radionuclide release time to the defmitions to be inconsistent since the accuracy.

 'e                accessible environment. it should be        scope of the defmition adopted in i 60.2         Section i 60122tb)l7). In addition to noted. however, that the Commission         will encompass water withm the zone of comments received in response to the still retains the option of applying the    saturation as well as water withm the         Commission's specihc request for mput provisions of I 60.113(b) instead of        unsaturated zone. As noted abose. the         on its questions related to groundwater i 60113(a)(2) to a particular geologic      Commission considers it necessary to          travel time calculations m the
              '    settmg when such an action is deemed        adopt a broader defimtion of the term         unsaturated zone, the subject of ac                appropriate.                                " groundwater"in order to maintain            groundwater travel time was also consiecy with previous Commission             addressed by two commenters on ng               (b)DefWtion of Groundwater                  usage of this term and to effectivel)         proposed i 60,122(b)(7) The issues vs                     Three commenters addressed the         apply the provisions of 10 CFR Part 60 to raised by these two commenters ment Commission's proposed defmition of the      the regulation of HLW disposal within         discussion here s.lthough they has e c              term " groundwater" as meanmg "all          unsaturated as well as saturated              resulted m no change to the rule.

water below the Earth a surface". Two geologic meda. Further, since EPA has The provisions of i 60.122(b)(7) has e of these commenters. citing possible not yet promul,tated its final confusion among the pubhc and the effect ofidentifymg pre-waste-environmental standards. the emplacement groundwater travel time j scientific commumty stated that the Commission cannot anticipaar whether along the fastest path of hkely Commission should not defme or how " groundwater" will actually be "gmundwater m this manner. but radionuchde trasel from the disturbed

            ,                                                  defined m the f.nal EPA regulation.           zone to the accessible environment that wa er tl in t sa urst d zone l             (c/ Def;mtion of the " Unsaturated 2one" substantially exceeds 1.000 years as a contrast. one commenter commended fasoraMe sitmg cntena b M de The Commission's proposed defmitior satrrated and unsaturated zones NRC on this defimtion. but noted that it    was denved from U.S. Geological may not be consistent with the                                                            Prenoush these prowsons dome %

Surve) (USGS) Water Supply Paper designated as i 60.122(bli2)(n)) apphed definition of the term included in the 1988 Two commenters noted that the proposed EPA environmental phrase " deepest water table" mtroduced onh t sites withm the saturated zone standardM CFR Part 191. In its confusion into the defmition of the term One comrnentu on proposed ed proposed rule EPA defined - i 60.122(b)(?) opposed the apputation of

 *                                                             " unsaturated zone"(160.2) The
                   " groundwater" as " water below the land Commission had inferred that the phrase this provision to the unsaturated zone
                                                               " deepest water table" as used by the         on the grounds that the determination of surface in a zone of saturation"(47 FR
          !        58205. December 29 1982) While the          USGS referred to the regional water           groundwater travel time m the
          ,        Commission recognizes that hmiting the      table and hence adopted this same             unsaturated zone may not be necessar) use of the term " groundwater" to water     phraseology in the derimtson of the term      nor always be possible. Under such within the saturated zone may currently     " unsaturated zone" set forth in the          circumstances, this commer.ter argued.
;th     .i         be a more widely accepted practice, the     proposed amendments to 10 CFR Part            inabihty to demonstrate that Commission also notes that numerous         60. However. in hght of conh. ion             groundaater travel time substantially members of the scientific community         expressed by commenters which may be exceeds 1.000 years should not amount

'si routmely use the term groundwater m due partially to the incorre n inference to the absence of a favorable condition e- the same context as the Commission by some that the phrase " deepest water The issue of groundwater trasel time m

         !         proposed.                                                                                 the unsaturated zone has alread> been i                                                               table" referred to local rather than f              The Commission has carefully           regional water tables. the tiefimtion of      discussed in detailin the abose section reviewed the arguments presented by         term " unsaturated zene" ba a been            on Groundwater Trovel Time i         the commenters on this issue and has        modified. To clanfv the Commission's          Cciculations and will not be repeated decided to retam the defmition of           original intent the' phrase " deepest         here With respect to the second part of or~

groundwater with one minor change- water table" has been replaced by this comment the Commission reiterates the phrase " Earth's surface" has been " regional water table" in the fmal its position set forth in the replaced by " land surface". This change amendments. (A conforming change has Supplementary Information to the fmal f 10 CFR Part 60 technical cnteria (48 FR was made for the sake of clanty and also been made to the defmition of the internal consistency with wordmg in the term " saturated zone"). Additionally, 28201) that a site is not disquahfied as a definition of the term " unsaturated the phrase " water in this zone is under result of the absence of a favorable zone".The Commission's decision was less than atmosphenc pressure" has sitmg condition. I based on the fact that at present. no

• been rewntten as " fluid pressure in this A second commenter on i 60122tb)[7)

{ unique definition of the term zone is less than atmospheric pressure" expressed the view that for a HLW

                   " groundwater" appears to be                for the sake of techmcal clarity. The         repository within the unsaturated zone.

mmimizmg leachate flux would appear gn f' universally accepted in the technical Commission has attempted to maintain

29646 Feder:1 Register / Vol. 50. Ns.140 / Mond:y, July 22. 1985 / Rules and Regulations . I to be at least as important as geologic media, water is transported in prosision since the proposed wording maumizmg groundwater trasel time. To that end. this commenter fleet that it both liquid and vapor phases. The allowed no potential s apor transport of relatne contnbution of tranport sia both radmnuchdes by molecular diffusion [ might be more appropnate to specify as these phases and their direction of (i e.. transport at a microscopic lesel due g a favorable sitmg condition a dual movement with respect to a geologic to concentration gradients)or p "either/or" cnterion such that repository was deemed to directly cons ectn e transport (i e-. transport due c groundwater travel time is greater than influence the containment of to temperature or density gradients). 1.000 years or groundwater flux through contammants. Vapor transport. The same commenter noted that whde 'l, the host rock at a proposed site is less particularly when a thermal gradient is the ilus .alaes associated with these I than some aserage rate. This rate. it was imposed.may provide a possible two transport processes might be argued. Could be based on nuchde mechanism for radionuclide migration m:mscule. they would not be zero at any solubihty, teach rate cntena. and from a geologic repository in unsaturated site. The Commission does [ population esposure cntena. The unsatursted geologic media. This issue not consider it appropr ate to add commenter stated that whichet er was discussed at length by the Commission in the proposed quanti'ative clanfications to i cnterion was ultimately selected it i 60t122(c)(24) because the mosement ~. should be based upon an area!!y amendments and in draf t NUREG-1046. of radionuclides in the gaseous state is. ' mtegrated or aseraged calc 2!aton. over The comments received on the to a large extent. dependent on site. and an area on the order of the cross. discussion of vapor transport and on the design specific parameters.The / sectional area of the repository normal wording of the proposed araendment Commission considers the movement of to the direction of espected thx I 60.122(c)(24) indicated a need for the radionuclides in the gaseous state may regardless of hydrogeologic zone to help Comnussion to clanfy its intent with ' be a potentially important site- and reduce contros ersy concerning how the respect to vapor transport. design related process and will retain

 " fastest pathway" can be determined.          The issue of vapor transport of          the opportumty to evaluate whether or             I For a discussion of the concept of         contanunants is a relatively new issue      not such a process will adversely affect        '

appipng a daal cnterion of either that has grown out of scientific the geologic repository system. I groundwater trasel time or groundwater insestigations of the feasibility of Hl.W l{owever, to alleviate the confusion I flux see the abose section entitled disposal in unsaturated geologic media. ' surrounding proposed i 60.122(c)(24). Cmen6 cte.r Tecvel Lee Calculations. Since most scientific studies related to the wordmg of this prosision has been I Mnor corrections hase been made to ilLW disposal within the unsaturated ' extensively modified in the final the prosis;cns of 160 t:2(bj(8) for the zone hase been initiated very recently, ' amendments. Reference to " vapor sake ef clanty and technical accuracy as many of the associated issues have not transport" has been deleted. and this a result of the comments received. The as yet been exammed m any great I

                                                                                         ,rovision now solely addresses the phrase "and nearly constant

• has been detail. The Commission recognized that potential for the movement of deleted from 160122(bym(il and a vapor formation may not necessanly radionuclides in a saseous state through '

ty pezraphgal e ror m the word constitute an adserts condition for 8

                                                                                                              ~

air-filled pore spaces of an unsaturated os er!ymg ha s been corrected. particular geologic repository site, but' I geologic medium to the accessible

 /g/ Potents!!r Ad erse Con 6tions           given the fact that vapor transport could environment as a potentially adverse                '

provide a mechanism for radionuclide . condition. The Commission believes the i Sect:on 60122lcH9) This prosision of transport within the unsaturated zone. it i

                                                                                         "

• 8 j * " "'"#* iI the final technical.cnteria ident.fied wanted the opportunity to evaluate r

roundwater conditions m the host rock whether or not vapor transport could cnM esmal inn ad doW that are not reducmp as a potentially adversely afftet a geologic repository " Y *

• 8" Y ' ' ' * *'

                                                                                         "* Y'ious the  prev wordmg. such as one adserse condition for th r saturated        system. To that end the Commission zone. One commenter on the proposed         identified the potential for vapor          c mmentgr s query f where the vapor amendments stated that a parallel                                                       transport is occurnng and when it is transport of radionuclides from an                                                             ,

prousion should be prostded for the underground facility located in the I

• P""I' t unsaturated zone. The Commission unsaturated zone to the accessible The Commission agrees with the ,

considers this argument to have ment environment as a potentially adverse commenter who indicated that vapor e and has modified the final amendme'nts condition in the proposed amendments transport may also occur in geologic aCCordingly Rather than create an ($ 60.122(c)(241). The Commission has repositones sited in the saturated zone E

 .idditional prosision. the Commission       not reached any conclusions on vapor        until resaturatton occurs. A temporary.

has deleted the qualtfyng phrase "for transport, as one commenter incorrectly localized. unsaturated region could form disposal in the saturated zone" from inferred. but rather is currently around an underground facility withm exist:ng i 60122(c)(9) to ensure that this sponsoring research on vapor transport the saturated zone as a result of prosision will be applicable equally to in unsaturated fractured rock in an activities related to construction and groundwater conditions in the saturated effort to better understand this subject. operation of a geologic repository (e g.

 ,ind' unsaturated zones.                       Some confusion was expressed by the     dewatering of shafts and drifts). To date.

Section 60.122(c)(23). Minor editorial commenters with respect to the the issue of vapor transport has not changes hase been made as suggested Commission's use of the term"vspor been raised for a geologic repository h) one commemer, for the sake of transport". In particular. one commenter within the saturated zone pnmanly clarity. stated that i 60122(c)(24), as wntren. because such a phenomenon would be Section 601:2fc)(24). During the was ambiguous and meaningless. The espected to be encompassed within a deselopment of the proposed term " vapor transport" as used in the much larger saturated region, that is. amendments (47 FR 5935. February 16. proposed amendments referred to both vapor transport might only be espected 1W) the Commission's staff identified water vapor and the gaseous state of to occur in that portion of the host recu upor transport of contaminants as a some constituent contaminants. A where the voids are not completely potential concern associated with liLW second commenter on this issue filled or refilled with groundwater. d:sposal in the unsaturated zone. The suggested that the Commission add Further. it is anticipated that the time Commission noted that it. unsaturated quantitative clarifications to this required for waste package integrity Jb

a Feder;l Register / Vol. 50. No.140 / Monda). July 22. 1965 / Rules and Restlations 296&

   ,,              (300 -1.00b yrs) will generall) eseced the   Regulatory Flasibility Certification               Unsaturated zone" means the zone f"g                 post-closure time required for a ce        te 8 '

between the land surface and the resaturation of a geologic repository regio al wster table Generally, fluid

     '9 ""         withm the saturated zone lassumed b) p      a]) 9                U         5 I) the Commission certifies that this rule pressure m this zone is less than the NRC staff to occur withm a few                                                         atmosphent pressure. and some of the will n t have a signihcant economic           soids ma) contain air or other gases at g#               hundred years followmg permanent
                 !                                              impact on a substantial number of small       atmosphenc pressure Beneath flooded closure). Therefore. the Commission          ennhes. The only entity subject t
                '                                                                                             areas or m perched water bodies the
   ,#              does not consider it necessary at this regulati n under this rule is the U S         fluid pressure locally mm) be greater time to identify sapor transport as a                                            no a r    to n y            c               than atmosphent j  potentially adserse condition for HLW                      ,                    p any            disposal w;ithm the saturated zone.

l Howeser. if future research m the area Flesibiht) Act' 3 Section 60122 is amended b) of sapor transport challenges these Ust of Subjecta in to CFR Part 80 reusmg paragraphs (b)(2)(m) and (c)(9) current assumptions. the Commission redesignating and rensina paragraph High-level waste. Nuclear power it may decide to broaden the prousions of (b)(2)(iv) as (b)(7). and addmg new plants and reactors. Nuclear matenals. g ,, I 60122(c)(24) to include both the Penalt). Reportmg and recordkeepmg paragraphs (b)(8). (c)(22). (23) and (24) to and saturated and unsaturated zones. read as follows ntt Weste treatment and If) Design Cntena disposal I 60.122 smng criterta. g Changes were made to prousmns of lesuance the fmal techmcal cnteria related t design entena. The provisions of For the reasons set out in the 3 preamble and under the authority of the (2) * *

• or i 60133(f) hase been modified to more Oii) Low sertical permeabiht) and low Atomic Energy Act of 1954. as amended.

ect cl sel) identify the concept of a hydraube gradient between the host the Energy Reorganization Act of 1974 potent 2al for creatmg a preferential r ck and the surroundmg hydrogeologic as amended. the Nuclear Waste Pohey pathwa) for groundwater to contact the "" waste packages This change was Act of and 5 U.S C. 553. the * * * *

• m prompted by a commenter s observation Nuclear Regulatory Commission is (7) Pre-waste-emplacement that as ongmally worded. this provision adoptmg the followmg amendments to to CFR Part 60 groundwater travel time along the might not be internally consistent with fastest path of hkely radionuchde trasel

 ,             ,   new i 60.122(b)(8)Ov) which identihes a     PART go-DlSPOSAL OF HIGH-LEVEL                 from the disturbed zone to the l   host rock that proudes for free drau age RADIOACTIVE WASTES IN GEOLOGIC                    accessible enuronment that t   as a fasorable h)drogeologic condition      REPOSITORIES                                   substanually exceeds 1.000 years ugh               n the unsaturated zone Sumlar word                                                           (8) For disposal in the unsaturated l  changes hase been made to the ted                                                               1. The authonty citation for Part 60        zone, h> drogeologic conditions that provisions of I 60134(b) for consistenc)    contmues to read as follows-                         'd P
.              ,   w;ith l 60122(bl(81bs) Addiconall) the         h          Seca n n 61 n as m in                   Low moisture flux in the host rock the              Parase radioactne waste augration           182163 68 Stat 929 930. 93: 933 935 948        and in the oserlying and underlying j

has bean changed to radionuchde 953 954 as amended H2 U.S C 2o*1. 20'3- hydrogeologic units' 1 migration m both l 80133ff) and 20912003. 2005. 211L 2201,2232. 223R secs I 60134!b) for the sake of techmcal Oi) A wster table sufficientl>. below g" i 20:. :06 se Stat 1:44. 1:46 (4:U S C sa42. the underground faciht) such that fully i accuraev. The changes should ensure S846). secs to and 14 Pub L 9'M01. 92 Siet

              '                                                w 142 U.S C :o:ta and 5a51). sec.10:. Pub      saturated voids contiguous wtth the y                 that these provisions will be equally L 91-190. 83 Stat 853 (4: U S C 4332). sec     water table do not encounter the apphcable to geologic repositones 12t Pub L tr%425 96 Stat 22:e !42 U S C       underground facihty:

withm either the saturated or WU Oii) A laterally extensne low-unsaturated zone. and will more ' accurately convey the Commissien's "fP *" 2 3 88 * permeabihty hydrogeologic unit abose amended (42 U.S C 2273). Il Go 71 to ao 75 the hoy rock that would inhibit the ongmaj intent, a*e issued under sec 161o. 68 Stat 950. as downward movement of water or dnett e i Environmental Impact amended (42 U.S C 22011o11 downward moving water to a location 2 Section 60 2 is amended by addmg beyond the hmits of the underground Pursuant to Section 121(c) of the f.cihty. Nuclear Waste Pohey Act of 1982, the .two new definitions of " Groundwater" and " Unsaturated zone" in proper Ov) A host rock that prmides for free

             ;     prornulgation of these entena does not alphabetical sequence and revismg the         dramage. or require the preparation of an             -

existmg defmition of "Saturatui rone (s1 A chmatic regime in which the environmentalimpact statement under to read as follows as erag- annual histonc precipitation is t Section 102(2)fC] of the National a sma!! percentage of the aserage Environmental Polic) Act of 1969 or an) g e0J Dennmons, annu61 potential evapotranspiration. enuronmental feuew under . . . . .

            !      subparagraph (E) or (F) of Section 102(2)                                                     (c) * * *
            '                                                      .. Groundwater *. means all water             (9) Groundwater conditiens in the R            '      of such Act' which occurs below the land surface           host rock that are not reducir g.

a Paperwork Reduction Act Statement . . . . . . . . . . The final rule contains no new or " Saturated zone" means that part of (22) Potential for the water table to ed the earth's crust beneath the regional e, , amended recordkeeping. reportmg or rise sufhciently so as to cause saturation

            ?

application requirement, or any other water table in which all voids. large and of an underground facihty located m the f type of information collection small. are ideally filled with water under unsaturated zone. requirement subject to the Paperwork pressure greater than atmosphenc (23) Potential for existing or future Reduction Act (Pub L 96-511). perched water bodies that may saturate

6

9643 Federal Regist:r / Vol. 50. No.140 / Mond y luly 22. 1985 / Rules and Regulations portions of the undmround raahty or by mdmdual telegrams.The AD unsafe condition m aircraft. lt has been proside a f uter l'.ow path from ari requires the use of only those f'iels further determined that this document l' underground facility located in the known to perform properly in the Boeing mvahes an emergency regulation under g unsaturated rane to the accessible Model 737-300 fuel sy stem. This action DOT Regulatory Policies and Procedures environment. is prompted by four mcidents of loss of- (44 FR 11034. February 26.1979). If this (24) Potential for the mos ement of power danng chmb wh.le using IP-4 action is subsequently determined to [f i

radionuclides m a gaseous state through fuel. msohe a significant/ major regulation. a ** mr. filled pore spaces of an unsaturated ' oATas: Effective August 6.1985 as to all final regulatoi) evaluation or snalysis. - geologic medium to the accessible persons except those persons to whom it as appropnate. w d be prepared and piaced in the regulatory docket (other 0 environment. was made immediately effectne by telegraphic AD T85-11-52. issued lune 7 wise. en esaluation or analysis is not ' [t

4. Section 60.133 is amended by 1485. which contamed this amendment. required).

resising paragraph (f) to read as follows: Fon runTwaR iNaoAM ATION CoNTACTt I.ist of Subjects in 14 CFR Part 39 A Mr. Stewart Miller. Propulsion Branch. (! l 80J33 Addmonal degn enteda w me Asnation safety. Aircraft. ANM-140s. Seattle Aircraft A f9""" , Certification Office: telephone (206) 431- Adoption of the Amendment 2969. Mailmg address: FAA. Northwest H if) Rock escavation. The design of the Mountam Region.17900 Pacific Highway PART 39-( AMENDEDI ^ underground facility shall mcorporate South. C-+8966. Seattle. Washington A excasation methods that will hmit the 98168. Accordingly, pursuant to the authority a potential for creating a preferential delegated to me by the Admmistrator. - surettisENTARY INFOAMATIOec On June pathway for groundwater to contact the 7.1985 telegraphic AD T85-11-52 was the Federal Aviation Administratiori 5 weste packages or radionuclide issued and made effective immediately amends i 39.13 of Pstt 39 of the Federal n migration to the accessible ensironment. as to all known U.S. owners and Aviation Regulations as follows: r. operators of Boeing Model 737-300 1. The authonty citation for Part 39 C

5. Sect:on 60.134 is amended by senes airplanes. The AD requires the contmues to read as follows: S resisma parag aphs (b)(1) and (6)(2) to use of only certam approved fuels and Authonty:40 U.S C.1354f al 1421 and 1423. "

raad as follows- and appropnate revision to the FAA* 40 ES C. to60ti lRensed Pub. L 97-44th " 1 60.134 Dwgn of seats for shafts and approved Airplane Fhght Manual.The kauary 12.1983): and 14 cnt 11 as. All was prompted by reports from one c

    .              .        .  .   .                   operator of a Boemg Model 737-300               2. By addmg the following new                   g airplane who had expenenced four loss. airworthiness directive:

b) . . . d $anWWmuAngdd4k b (1) The petential for creati: g a ww .wu a Met m-m um preferential pathway for grcundwater to #4 b ' *"* d"# d*W*MD A resulted in a flame out. Two of these present engme flameouts dunng chmb'. contact the waste packages or (2) for a radionuclide migration through existmg mnts occM on 6e same M ad ac m m W m m h 6 4 , affected both engmes at nearly the same accomphshed. ,, pathw.ap' 1. B+ fore further thght ensare that the fuel t me. ' Dated at Washmaton. DC. this t6th day of The manufacturer has confirmed bemg used ts one of the followins types' N!y.1%5 through flight test that use of JP-4 fuel m

• let A or At conformma to specificanon ASTM-D-toss. '-

For the Lc! ear R gulatory Comrmis;on. the system as presently configured can

• lP5 conformmg to MIL-T-5624. O S.muel I. ChA. result ir. engme power rollback during Secretary of me C.cm:ssion. chmi'. This rollback event could tesalt
• Fuela c nfCimin8 to DERD 2494 or 2498:

iFR Doc. 65-t*364 F:!cd 7-19-45. 6 45 aml m engme flameout and could occur

• Fi.ets confarm:na to AIR 3404 or 1405. ,e sw ,3 coog r3.u, , simultaneously on both engines. 2. W:tnm 48 hours .ncorporate the Since it was found that immediate C' ratio.in, ,nfor nancn mto the tam:tanons

                                               .~ corrective action was required notice                                                                  A
                                                                                                   %m o(% gu y yw w and public procedure thereon were           provide to crew s.                                   Et.

DEPARTMENT OF TRANSPORTATION impracticable and contrary to public "The only approsed fuels are let A and At CJ Federal Aviation Administration interest. and good cause existed to make conformmg to Specificanon ASnt-0-m55. B the AD effective immediately by IPS confonrang to MIIeT-5624. fuels n individual telegrams issued June 7.1985. conformmg to DERD 2494 or 2498. and fuels F 14 CFR Part 39 to all known U.S. owners and operators conform ng to AIR 3404 or 3405." F

   ! Docket No. 85-NM-62-AD; Amdt. 39-5 tCSI           of Boemg Model 737-300 airplanes.               3. Alternate means of compliance These conditions still exist and the AD     which provide an acceptable level of                s AirwortNness Directives; Boeing Model 737-300 Series Airplanes                      is hereby published in the Federal          safety may be used when approved by                 P Register as an amendment to l 3913 of       the Manager. Seattle Aircraft                       #

AcaNcV: Federal Aviation Part 39 of the Federal Aviation Certification Office. FAA. Northwest

• Admimstration (FAA). DOT. Regulations to make it effective as to all Mountain Region. "

ACTION: Final rule. persons. . Note.--Comphance with paragraph 2. of U The FAA has determined that this this d:rectne may ba effected by includmg a

SUMMARY

This action publishes m the regulation is an emergency regulation copy of this AD m the Airplane Fhght Manual Federal Register and makes effectne as that is not considered to be major under and Operatms Manual. p to all persons an amendment adoptmg a Executive Order 12291. It is #

This imendment becomes effective August n;w airworthmess directne ( AD) which impracticable for the agency to follow e. taas. It w as effective eerher to eil wcs presiously marie effective as to all the procedures of Order 12291 with ecipients of telegraphic AD 85 3152. issued I known U S. owners and operators of respect to this rule smce the rule must lune 7.1985. which contamed this o Bo;ing Model 737-300 series airplaties be issued immediately to correct an .meridrnent. d

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