ML20132C535

Concurs W/Final Rule Amending 10CFR60, Disposal of High Level Radwaste in Unsaturated Zone, Subj to Mods Indicated on Encl marked-up Copy

ML20132C535
Person / Time
Issue date:	11/05/1984
From:	Felton J NRC OFFICE OF ADMINISTRATION (ADM)
To:	Ostrowski C NRC OFFICE OF NUCLEAR REGULATORY RESEARCH (RES)
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 8509270081
Download: ML20132C535 (23)

Text

[ A344.2 8 'jo UNITED STATES '

4

.! n NUCLEAR REGULATORY COMMISSION

$ $ WASHINGTON, D. C. 20555

%, ...../

NOV 51984 MEMORANDUM FOR: Colleen Ostrowski Office of Nuclear Regulatory Research FROM: J. M. Felton, Director Division of Rules and Records Office of Administration

SUBJECT:

REVIEW 0F FINAL RULE AMENDING 10 CFR PART 60 The Division of Rules and Records has reviewed the final rule and concurs'

. subject to the modifications contained in the enclosed marked copy.

Specifically, note that throughout the Supplementary Information section, reference is made to other Federal Register (FR) publications. The full FR cite, which includes the FR page number and date of the publication, is needed in several places for these references.

A statement concerning environmental impact is inserted to reflect the Commission's recent revisions to 10 CFR Part 51. You should check with ELD'or 0GC to ensure that this statement is appropriate for this final rule.

We forwarded a copy of this rule to Steve Scott of TIDC for review of reporting and recordkeeping requirements. That Office will contact you regarding the paperwork statement.

Additionally, the Regulatory Flexibility Act Certification and. amendatory instruction number three are slightly revised.

If you have any questions about our comments, please contact John Philips, Chief, Rules and Procedures Branch, on extension 7086.

. M. Felton, Director Division of Rules and Records Office of Administration

Enclosure:

As stated 8509270001 850925 6 4 5934

I [7590-01] ;

NUCLEAR REGULATORY COMISSION 10 CFR PART 60 Disposal of High-Level Radioactive Wastes j in the Unsaturated Zone

-) AGENCY: Nuclear Regulatory Comission.

y.

b i5 ACTION: Final rule.

p o J q $ P h

he Nuclear Regulatory Comission is-731i:h;ng :::ndeents SUMARY j'*g) relate ou t$ disposal of high-level radioactive wastes in geologic d

. .9 t r itorie w ith*n the unsaturated zone. Th::: ::"-* 2ddit4n 4

.} j t ,te th: : !: ting p.vvisivu , ..ioure sa1. 1.ne ruie wrri epply t: ;::h;k

, ."- ~^^ ^'

' -sted ur unsetsreted ;;ra. This action is

}p necessary to assure that NRC regulations are applicable to all geologic 4 j : repositories, whether sited in the saturated or unsaturated zone.

sqd  !

'9[*

k W EFFECTIVE DATE:

$m-*9D FOR FURTHER INFORMATION CONTACT: Dr. Colleen Ostrowski, Office of i

. Nuclear Regulatory Research, U.S. Nuclear Regulatory Comission, Washingto C[0555, telephone (301)427-4580.w_

SUPPLEMENTARY INFORMATION:

Background

On February 25,1981,the Nuclear Regulatory Comission (NRC) promulgated a rule that established procedures for licensing the disposal 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 the final technical criteria as written i 1 Enclosure A

2 [7590-01]

were generally applicable to disposal in both the saturated and g unsaturated hydrogeologic zones, their scope was limited to HLW disposal j ,,

within saturated geologic media for the reasons discussed atp FR 28203)"p $ <

h The Commission recognized that this approach might be g 7 considered unduly restrictive and expressed the intent of issuing M,M technical criteria for the unsaturated zone shortly after promulgating'#

fa cJaA..

the final technical criteria so as u W fford fu a u,.n w w n public comment on this issue .(48 rg 2000,0)q Proposed amendments which e.nkther 4,g opp a t I>r <<(w. .

i would have the effect of broadening the scope of the technical criteria ( ,

t to include HLW disposal within either the saturated or unsaturated zone g were published for comment on February proposed amendments contained provisions for new definitions 16, 1984.%)[.* and

~

~ThW C w.

.'avorable 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.-(10 0 033D; *In conjunction with the proposed amendments the [ommission published for public comment draft NUREG-1046'

• which contained a discussion of the principal technical issues considered 4 by the Commission during the development of the proposed amendments.

i Comments and Changes A total of fourteen groups and individuals commented on the proposed

, OU j amendments and draft NUREG-1046.Y 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

~ ~

p IDraft NUREG-1046 is cur7Lently being revised to reflect changes made in

~

• 1. the final amendments to 10 CFR Part 60 relate to HLW disposal within t-

1. g'" /j"'T nd'#pthefpiacea Unsaturated Zone.jiU;rPublic in tne commission's ;3'4ML a copyRoom.

Document of NUREG-1046 will be Copies of HUREG-1046

1. " W'*'aj L may be purchased by calling (301) 492-9530 or by writing to the Publica-

~

tion 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

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of Commerce, 5285 Port Royal Road, Springfield, VA 22161.

4 2 Enclosure A

- - . _.._,--~-.-.,.-~,-,_.--._....,-,.,.y-- -

. , . ~ -. -

[7590-01]

within the unsaturated zone and provided additional comments suggesting  ;

word changes to improve the technical accuracy and clarity of the 4 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.

(a) Groundwater Travel Time Calculations.

Technical criteria governing the post-emplacement performance of the , ,.

particular barriers of the geologic repository system (i.e. engineered .,

barriers and geologic setting) are set forth at'$60.113 (48 FR 28224 h 4 A The post-closure performance criterion for the geologic setting set forth # .

at $60.113(a)(2) requires that the geologic repository be located so that N p -

pre-waste-emplacement groundwater travel time along the fastest path of ,y likely radionuclide travel from the disturbed zone to the accessible Q-environment be at least 1,000 years or such other travel time as may be T i

p$

approved or specified by the Commission. Although no change was made explicitly to the provisions of $60.113(a)(2) in the proposed amendments i for the unsaturated zone, the proposed definition of the term

" groundwater" set forth at 560.2 -(" TR would make the scope of 560.113(a)(2) applicable to geologic repositories within either the saturated or unsaturated zone. Similarly, the proposed amendment to the Siting Criteria ($60.122(b)(7)) would have the effect of making pre-waste-emplacement groundwater travel time along the fastest path of l

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

i provisions applied only to HLW disposal in the saturated zone since, as mentioned above, the scope of the final technical criteria was specifically limited to geologic disposal in saturated geologic media.

.In the statement of considerations which accompanied the proposed amendments, the Commission discussed possible limitations that might be 3 Enclosure A l

o

[7590-01]

placed upon the pre-waste-emplacement groundwater travel time performance objectiveof$60.113whenappliedtotheunsaturatedzonej('?T";;;O.

However, 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 denonstrating compliance with 1 560.113(a)(2). The Commissior 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 to A D . - %

the approach set forth in $60,113(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 j objectivefortggeologicsttingtositeslocatedinunsaturated goggicmediaf(AQ " 5% j, n response to this solicitation of public tapet,' seven of the fourteen commenters specifically addressed the questions on groundwater travel time calculations. These questions and the views expressed by the seven commenters will be reviewed here before turning to other considerations.

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 l

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 Federal agencies, endorsed the opinion that groundwater travel time could j be determined with reasonable assurance. One of these commenters I indicated that groundwater travel time calculations could be made by I

4 Enclosure A l

l . --- ---- - ---

[7590-01]

measuring the amount of natural tritium in the groundwater samples from a vertical profile in unsaturated geologic formations. Two other commenters stated that groundwater travel time could be derived from groundwaterfluxusingmeasurementy,fambient3atercgotengde,greejf g ,

saturation, matric potential and hydraulic conductivities,and then ti -

@ A couldbeusedtopredictconstitutivgrelationshipsoverawiderangeof conditions. From these relationships k N 'a'r^g d Nat groundwater ,[

g g db velocities and travel times could then be estimated. One of these two qv3 $d 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 groundwater movement through potentially suitable geologic repository 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 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 determined in the unsaturated zone provided that the proper level of site characterization analyses is conducted by the l applicant. Following a detailed study of the comments received on this questionf the Commission believes it is currently feasible for DOE to demonstrate the implementability of the groundwater travel time provisions using existing standard field and laboratory experiments.

I Further, as several commenters indicated, a substantial effort is

} currently underway M develop new methodologies and to improve 5 Enclosure A

[7590-01]

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.

The second part of the first question on which the Comnission sought comment centered on whether or not the existing groundwater travel time 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 time provision (560.113(a)(2)) can be applied to a geologic setting located in either the saturated or unsaturated zone. The Commission could discern no obvious advantage for developing a parallel provision for the unsaturated zone as one commenter suggested. With respect to another commenter's concern that if the Commission decided to retain the ok groundwater travel time provision Athen travel time along any segment of Dl' the flow path, including the unsa)turated zone, should be creditable A provided that r ponableassurancehasbeendemonstrated, e Commission has concluded htihedefinitionoftheterm" groundwater"setforthat

$60.2 will allow travel time along subsurface flowpaths to be credited regardless of the hydrogeologic regime through which the water is moving.

The Commission 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 be largely accommodated by the definition of the term " groundwater". With respect to the view expressed that the i approachsetforthin$60.113(b)maybepartglarlyappropriateinthe case of HLW disposal in the unsaturated zonefit should be noted that in those instances when groundwater travel time calculations cannot be I

1 1

6 Enclosure A

- = - -_. -

[7590-01]

determined with reasonable assurance, the Commission may prefer to specify variations in performance objectives pursuant to $60.113(b).

In its second question related to groundwater tra'el v time the Commission sought public comment on whether groundwater travel time represented an appropriate measure of performance for a site within the 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 appropriate 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. 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. One commenter indicated that if NRC hose to retain the groundwater travel time OV.

performance objectiv s brovision should only be applied if the travel time calculations include combined travel times in the unsaturated and saturated zones so as to better approximate radionuclide transport. The l Commission considers the concerns of this commenter to be accommodated by the definition of the term " groundwater" adopted in the final amendments.

7 Enclosure A l

[7590-01]

Most commenters who argued against the application of the 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). U ce, se -

As derived from U.S. Geological Survey Water Supply Pape -1988< the l term " flux" can be defined as the rate of discharge of groundwater per

) unit area of porous or fractured geologic media measured at right angles

to the direction of flow. In comparison, the term " groundwater travel I time" used in 10 CFR Part 60 can be interpreted as the length of time required for a unit volume of groundwater to travel between two loca-

, tions. Alternatives suggested by the commenters which were based upon

{ l'.he concept of flux included a maximum groundwater flux requirement and a I

dual "either/or" criterion which would allow the applicant the option of i demonstrating compliance with either a minimum groundwater travel time 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 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 requirement represents an independent measure of the overall l hydrogeologic system performance which may encompass a variety of hydrogeologic parameters including groundwater flux. However, the Commission expects that groundwater flux will remain an important factor l ,

in the technical evaluation of'radionuclide releases in the unsaturated zone, w oi J " Y 'N 0**

The Commission does not consider it necessary to specify a dual l "either/or" groundwater criterion suggested by another commenter since under the provisions of 560.113(b),the Commission already has the A /

i flexibility to approve or specify some other radionuclide release rate, .

(

cw # '

designedcontainmentperiodjorpre-waste-emplacementgrundwater ravel <

• H v2 d time on a case-by-case basis. Further, the Commission

! oo tous advantage to ircorporating a concept of are k integrated or averaged y groundwater flow velocity into the dual "e ther/or" criterion proposed by f' l

! this commenter since the Commission considers the fastest pathway y

, ' e dre kest is, il y /r w t

hd.~.r P

! 8 Enclosure A l

O

[7590-01]

criterion to be more conservative than averaged flow criteria. The primary interest of the Commission is not the quantity of groundwater moving towards the accessible environment per se, but rather the radionuclides contained within the groundwater. The fastest pathway concept is preferred because it will allow estimates to be made concerning when radionuclides may first reach the accessible environment. 0tc.

6"Tl#4

.stimates would not be apparent if an areal or temporal averaging of groundwater flow were introduced. The Commission anticipates that temporal and areal variations in the hydrologic regime will be addressed in the evaluation of uncertainties inherent to groundwater travel time calculations.

In contrast to the commenters who supported a performance criterion based upon groundwater flux, DOE 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, DOE took the position that an alternative performance objective developed I

upon the concept of a minimum time for release of radionuclides to the accessible environment based on four separate physical events would be 4

more appropriate for the unsaturated zone. The four physical events contained in the suggested DOE alternative performance objective were:

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

The Commission has reviewed the suggested DOE alternative performance objective and has concluded that it offers no obvious advantages to the performance objectives set forth in $60.113. The Commission notes that DOE has selected four of many possible physical events that can be anticipated to occur within the geologic repository environment, but has not provided a clear basis for why those four events were preferred among others. Further research and verification of both the underlying theory and the data collection techniques and methods are deemed necessary by the Commission before specific events and their sequences for groundwater flux and subsequent radionuclide transport in a 9 Enclosure A

[7590-01]

i*

j deep, low-saturated, hydrogeologic environment could be identified and

. modeled with confidence. However, it should be recognized that the l r

l likelihood of specific physical events occurring at a geologic repository l 1s dependent.upon a number of factors such as the specific hydrogeologic

! and thermal characteristics of a particular site, thermal loading,  !

l canister design and complex interactions and couplings among the thermal, l

mechanical, hydrogeologic and chemical. properties of the geologic j setting. Although DOE indicated that related studies are both currently

underway and planned as future site characterization activities3 the CL #

Commission is not familiar with any scientific basis currently in the ,

published literature to support the assertion that these four physical l- events will, in fact, occur in the manner and sequenc anticipateddy)e6 ,

l The performance objectives of $60,113 are generally applicable to a i number of potential physical events while the alternative performance l objective suggested by DOE is limited to four, sequential physical events  !

l

! which may or may not occur. Further, the Commission considers that two of these events--the formation of a drying zone and the rowetting i phenomenon are not well understood at present, and therefore, should not be included explicitly within performance requirements. The Commission f

j also notes that the existing groundwater travel time provision of $60.113 directly encompasses two of the four physical events--time of travel through the unsaturated zone and time of travel through the saturated zone. Therefore, the Commission has not adopted this DOE alternative j performance objective for tne unsaturated zone.

The view was also expressed that the development of a new l alternative performance objective to existing 560.113_(a)(2) may not be necessary since the Commission's approach set forth at $60,113(b) might i be a more appropriate means of specifying alternatives to the groundwater i travel time criterion. The Commission notes that it is essentially ,

e s

l following this approach in its decision to retain the existing provisions

! of $60.113(a)(2) and $60.113(b).

I Following a review of the various alternative performance objectives i suggested by the commenters, the Commission considers groundwater travel l time.to represent a more appropriate parameter upon which the performance of the geologic setting can be evaluated than any of the suggested alter-i 10 Enclosure A l

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[7590-01]

. l 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 geolgic 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 y definition of the term included in the proposed EPA environmental . (fg standards -- 40 CFR 191. In its proposed rule EPA defined " groundwater //

as"waterbelowthelandsurfaceinazoneofsaturation"(47FR58205) .

While the Commission recognizes that limiting the use of the term ground-water to water within the saturated zone may currently be a more widely accepted practice, the Commission also notes that numerous members of the y u scientific community routinely use the term groundwater in the same g context as the Commission proposed.

The Commission has carefully reviewed the arguments presented by th'e 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 unique 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 suggested but rather has adopted one of the commonly used definitions of the term that is most consistent with the Commission's intent concerning the provisions related to groundwater throughout the l

l 11 Enclosure A

[7590-01]

Part 60 regulation. Further, the Commission historically has used the term " groundwater" in referring to subsurface water. 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 S60.2 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 internal consistency with previous Commission usage of this term and to effectively apply the provisions of 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 anticipate whether or how " groundwater" will actually be defined in the final EPA regulation.

(c) Definition of the " Unsaturated zone."

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

Geological Survey (USGS) Water Supply Paper 1988. Two comenters noted that the phrase " deepest water table" introduced confusion into the definition of the term " Unsaturated zone" (960.2). The Comission 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 comenters which may be due partially to the incorrectinferencebysomethatthephrase"deepesgatertable" referredtolocalratherthanregionalwatertablephedefinitionof term " Unsaturated Zone" has been modified. To clarify the Comission'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 Comission has attempted to maintain internal consistency with the l 12 Enclosure A

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[7590-01]

i

[ 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. 3 l (d) Favorable Siting Conditions. /,.f I

$60.122(b)(2). The term " low hydraulic' pot tial" has been replaced j with"lowhydraulicgradient"in$60.122(gb)( i) as suggested by one commenter for the sake of technical accu. racy ob i 560.122(b)(7). In addition to comments received in response to the l Commission's specific request for input on its questions related to groundwater travel time calculations in the unsaturated zone, the subject I of groundwater travel time was also addressed by two commenters on proposed 560.122(b)(7). The issues raised by these two commenters merit e

discussion here although they have resulted in no change.to the rule.

l The provisions of $60.122(b)(7) would have the effect of identifying ,

-pre-waste-emplacement groundwater travel time along the fastest path of likely radionuclide travel from the disturbed zone to the accessible l environment that substantially exceeds 1,000 y' ears as a favorable siting I criteria for both the saturated and unsaturated zones. Previously these l

provisions (formerly designated as 560.122(b)(2)(iv)) applied only to I

sites within.the saturated zone.

One commenter on proposed $60.122(b)(7) opposed the application of

[ this provision to the unsaturated zone on the grounds that the determina-l tion of groundwater travel time in the unsaturated zone may.not be neces-l sary nor always be possible. Under such circumstances, this commenter j argued, inability to demonstrate that groundwater travel time substantially exceeds 1,000 years should not amount to the absence of a l

j favorable condition. The issue of groundwater travel time in the j 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 reiterates l its position set forth'at 48 FR 28201 that a site is not disqualified as

a result of the absence of a favorable siting condition.

I 1

i .

13 Enclosure A L._____._.

[7590-01]

A second commenter on $60.122(b)(7) expressed the view that for a

HLW repository within the unsaturated zone 3 minimizing leachate flux would v l

-appear to be at least as important as maximizing groundwater travel time. &

To that end, this commenter felt that it might be more appropriate to l 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 ultimately selected it should be based upon an areally integrated or averaged calculation, over an area on i the order of the cross-sectional area of the repository normal to the i direction of expected flux regardless of hydrogeologic zone to help 4

reduce controversy concerning how the " fastest pathway" can be determined. For a discussion of the concept of applying a dual criterion of either groundwater travel time er groundwater flux see the above section 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

l. comments received. The phrase "and nearly constant" has been deleted from $60.122(b)(8)(i) and a typographical error in the word " overlying"

} has been corrected.

(e) Potentially Adverse Conditions.

g g 0 % 22(c)(9). This provision of the final technical criteria s w -t (June,1983) dentified groundwater conditions in the host rock that are i S* N not ing as a potentially adverse condition for the saturated zone.

l j

[

pg jo[

ht One commenter on the proposed amendments stated that a parallel provision should be provided for the unsaturated zone. The Commission considers y* this argument to have merit and has modified the final amendments

!o pM?

u k i / p .o w ikf*7,

- accordingly. Rather than create an additional provision, the Commission nas deleted the qualifying phrase "for disposal in the saturated zone" from existing $60.122(c)(9) to ensure that this provision will be i applicable equally to groundwater conditions in the saturated and i

i unsaturated zones.

, 14 Enclosure A i

i

f' [7590-01] l

- i 60.122(c)(23). Minor editorial changes have been made as suggested I

by one commenter, for the sake of clarity.

4 60.122(c)(24). During the development of the proposed amendments  ;

p the Commission's staff identified vapor transport of contaminants as a  ;

j potential concern associated with HLW disposal in the unsaturated zone.

The Commission noted at 47 FR 5935 that in unsaturated geologic media water is transported in both liquid and vapor phases. The relative

! contribution of transport via both these phases and their direction of l

movement with respe toageologicrepositorywasdeemed$irectly r

• M l ~ influence containmen of contaminants. 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 Commission at f 49 FR 5935 and in draft NUREG-1046. The comments received on the s discussion of vapor transport at 49 FR 5935 and on the wording of the '

i proposed amendmen 60.$22(c)(24)indicatedaneedfortheCommissionto l clarify its intent with respect to vapor transport.

I The issue of vapor transport of contaminants is a relatively new waste management issue that has grown out of recent scientific investi-gations of the feasibility of HLW disposal in unsaturated geologic media.

Since most scientific studies related to HLW disposal within the l unsaturated zone have been initiated very recently, many of the asso-ciated issues have not as yet been examined in any great detail. The Commission recognized that vapor formation may not necessarily be a l

j potentially adverse condition but, given the fact that vapor transport could provide a alistic mechanism for radionuclide transport within the

unsaturatedzone[wantId'theopportunitytoevaluatewhetherornotvapor O

! transport could adversely affect a geologic repository system. To that l end the Commission identified the potential for' vapor transport of radionuclides from the underground facility located in the unsaturated

zone to the accessible environment as a potentially adverse conditien in

the proposed amendments (660.122(c)(24)). The Commission has not reached any conclusions on vapor transport as one commenter incorrectly inferred, f l

but rather is currently sponsoring research on vapor transport in l

I 15 Enclosure A

. _ . . . _ _ _ _ _ . _ _ . _ _ _ _ . _ - _ _ _ . _ _ _ _ . ~ . _ . _ . _ . , _ . . _ _ . . _

[7590-01] ,

1 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 $60.122(c)(24), as written, was ambiguous and meaningless and could, under certain conditions, be applied to any i geologic repository site. The term " vapor transport" as used in the <

proposed amendments referred to both water vapor and the gaseous state of

! some constituent contaminants. A second commenter on this issue suggested that the Commission add quantitative clarifications to this provision since the proposed wording allowed no potential vapor transport

, of radionuclides by molecular diffusion (i.e. the process whereby solutes are transported at the microscopic level due to variations in tracer concentrations within the liquid phase) or convective transport (i.e.

3 heat transported along with flowing groundwater). The same commenter noted that while the flux values associated with these two transport j processes might be miniscule, they would not be zero at any unsaturated site. The Commission does not consider it appropriate to add i

! quantitativeclarificationsto$60.122(c)(24)becausethemovementof VE l radionuclides in the gaseous state is, to a large extent, dependent on t site- and design- specific parameters. However, to alleviate the confu-i sion surrounding proposed $60.122(c)(24), the wording of this provision has been e.xtensively modified in the final amendments. Reference to

{

vapor transport has been deleted, and this provision now identifies the potential for the movement of radionuclides in a gaseous state through i

air-filled pore 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 j transport is occurring and when it is important.

i The Commission agrees with the commenter who indicated that vapor transport may occur in geologic repositories sited in the saturated zone until resaturation occurs. A temporary, localized, unsaturated region

] could form around an underground facility within the saturated zone as a j 16 Enclosure A

. . . . . _ , . . , . . - _ . . . - _ , , _ . - . , , _ _ . . _ _ . _ _ _ _ . . ,.,,_--._m,__ _ _ _ _ . _ _ . _ , , , _ _ , - . , .--_m., - , . . . _ . _ , _ _ , . _ , ,

[7590-01]

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 2

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.

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) Design Criteria.

Changes were made to provisions of the final technical criteria

! related to design criteria. The provisions of 60.133(f) have been l modified to more closely identify the concept of a preferential pathway for groundwater flow towards the waste package. This change was prompted I

by a commenter's observation that as originally worded, this provision might not be internally consistent with new $60.122(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 l

have been made to the provisions of $60.134(b) for consistency with

$60.122(b)(8)(iv). Additionally, the phrase " radioactive waste

! migration" has been changed to ."radionuclide migration" in both

! $60.133(f) and $60.134(b) for the sake of technical accuracy. The changes should ensure that these provisions will be applicable to I geologic repositories within either the saturated or unsaturated zone, and will more accurately convey the Commission's original intent.

~

17 Enclosure A i

[7590-01]

J.

ENVIRONMENTAL IMPACT- / e'd M --

h L@ +9 (yFh 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 REVIEW W- -

Je f j 's &

The final rule contains no new or amended w w kt. 7 70 C cor eep ng, reporting or application requirement, or any other type of information collection requirements subject to the Paperwork Reduction Act (Pub. L.96-511).

REGUL'ATORY FLEXIBILITY ACT 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-t 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 Energyp/.</ 4s n4 a 1" * // 'a "// ##

de.fe}inJAt $rS+l'~ N ' 7 ?lN'hN OL LIST OF SUBJECTS IN 10 CFR PART 60 High-level waste, Nuclear power plants and reactors, Nuclear materials, Penalty, Reportin requirements, Waste treatment and disposal.

Oca Wec d b JrWn)

ISSUANCE l 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 Commission is adopting the following amend-ments to 10 CFR Part 60.

18 Enclosure A

[7590-01)

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

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)J secs. 202, 206, 88 Stat. p,(

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). i 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.161o, 68 Stat. 950, as #

^

amended (42 U.S.C. 2201(o)). D V-

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

, S 60.2 Definitions.

A A A A A

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

i " 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.

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

i * * * *

• q 3

OU ed 1

.y 3. Section60.122isamendedbyrevisingparagraphI(b)(2)(iii)[n Tedesignating paragraph (b)(2)(iv) as (b)(7), and adding new paragraphs (b)(8), (pKil),$22), (23) and (24) to read as follows:

S60.122Sitingcrit5ria.

i i

19 Enclosure A

ENVIRONMENTAL IMPACT: CATEGORICAL EXCLUSION The NRC has determined that this proposed regulation is' the type 73J3 kadd '

r~ ' e.93-of action described in categorical exclusion 10 CFR 51.22(c)( ). Therefore, 4

neither an environmental impact statement nor an environmental assessment has been prepared for this proposed regulation.

<t& W-4

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[7590-01]

a a * * *

(b) *** ggy re ayrapA (2. ) O b

ii) 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 continuous with the water table do not encounter the underground facility; (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 ,

precipitation is a small percentage of the average annual potential

, evapotranspiration. . p.

) ( * * * "Mj/

i (c) ***

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

1 * * * * *

(22) Potential for the water table to rise sufficiently so as to cause saturation of an underground facility located in the unsaturated 1 zone.

(23) Potential for existing or future perched water 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, l

20 Enclosure A i

\

I

[7590-01]

(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.

(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 flow towards the waste package 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.

(b)

(1) The potential for creating a preferential pathway for radio-groundwater flow towards the waste package or (2) et.dionuclide migration through existing pathways.

Dated at Washington, D.C., this day of , 1984.

For the Nuclear Regulatory Commission.

Samuel J. Chilk, Secretary of the Commissiun.

21 Enclosure A

- , . _ _ .