ML20059G847

Informs That During ACNW 23rd Meeting on 900829 & 30,draft Version of Rev 1 of Technical Position on Waste Form Reviewed.Committee Concerns on Subj Listed

ML20059G847
Person / Time
Issue date:	09/06/1990
From:	Moeller D NRC ADVISORY COMMITTEE ON NUCLEAR WASTE (ACNW)
To:	Carr K NRC COMMISSION (OCM)
References
NACNUCLE-R-0041, NACNUCLE-R-41, NUDOCS 9009130204
Download: ML20059G847 (3)

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ACN'WR OO41-L I-NUCLEAR REGULATORY COMMISSION J

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ADVISORY COMMITTEE oN NUCt. EAR WASTE i September 6, 1990; The Honorable Kenneth M.

Carr Chairman M

1 U.S.:- Nuclear -Regulatory Commission,

Washington, D.C.

20555:

Dear Chairman Carr:

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SUBJECT:

REVISION 1 OF' DRAFT TECHNICAL POSITION ON WASTE FORM-

-During its 23rd meeting on Augusti29oand'30,-1990,_ the-Advisory O

Committee' on Nuclear Waste' (ACNW). reviewed-a draft version of

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RevisionL1 of theLTechnical Positionfon Waste ~ Form,oprepared by NRC's Division cf Low-LevelLWaste Management.and Decommissioning.

The Committee also had the benefit of fdiscussion with the NRC staff

on this matter.

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s The revision' represents a significabt expansion of theiprevious document on this same subject and reflects many.of the points that were called to.the attention of the'NRC staff during previous ACNW.

and ACRS subcommittee meetings.

Owing to'the importance'to public health and safety that is now prop'erly' attached to the, quality of the low-level waste form, we conclude that this technical position, when fully ~ implemented, 'can serve as a useful1 guide :in ; the -

evaluation of waste forms used in low-level waste disposal.

We 1

believe that the required reporting;of mishaps will be especially useful.

Listed below are several concerns that the Committee has~on this subject.-

However, we believe that publication of: the-Technical Position need not be held up pending resolution of these concerns.

1 To assist in their resolutica, we recommend that ' the NRC staff consider the detailed discussions held during the ACNW. meeting.of August 29, 1990.

1.

The applicable regulation (10 CFR Part 61) places emphasis on.

the physical stabi'lity of the. waste-form (Class B and Class C) with the intent that by this means access'of uater to the waste can be controlled.

There is no requirement in Part 61 for a specified' resistance of the waste form to leaching;of radionuclides by ground water.

We believe that-an important-attribute of the waste form,is its bahavior related to

' migration of radionuclides into the enviranment.

We believe a revision of Part 61 addressing this point is needed, but g) 900912O204 900906 ADVCMNACNigE 9

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The Honorable Kenneth M.;Carr

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. September 6, - 1990 -

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'untili thatf is completed,' t' e !. Tech ! cal Position ~ shouldn be:

L amended;to: reflect moreJdirectly-th

. ion.that leachingt H

resistance Lshould beigiven.

The al-melusive focus' of the:

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' Technical Position on mechanical in- ; ity of the waste; form

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d anditheLeffect of:various phenomena ( e. g.,1thermall cycling,-

c 1b radiation, ' and Limmersion in1 water). on thatj integrity sh'ould.

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. be? supplementod. by. requirements 5 that leach cresistance,; as; measured by a specified separateLtest, should be: maintained:

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^1nU parallel. f with mechanical istrength;(af terJ the i waste 'is-

< subjected tofthese phenomena.

2.

TheM testing requirements ;citedl in the TrevisedRTechnical-

-l PositionJshould be representativefof conditionsilikelyfto be:

encountered ' in fa s shallow! land n buriali site'..... The< primaryf

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moMlizing; agent Lis ground water which: coulebe= more' aggres l

sive in enhancing movement of racidonuclides than the distilled-water,or~ synthetic sea-water,now specified in thenTechnicals Position; We'believe that the' specific test' conditions cited.

n in :the iTechnical* Position,. now i oriented ; only Eto structural ;

. impact, should be complementediby additional conditionstthatJ 4

.relatejto the groundwaterichemistry of!tho'weste.

Further, Siodegrr Ttion tests should ibe specified( fori cementitious-t waste mat. ices using bacteria _ that are likely to affect cement as well as the organic. component of the wastel 3.

We believe that the-provisions for testsJof the radiation i

l resistance of waste forms may not be sufficiently, conservative L

when considering the potential fory hydrogene generation in closed. spaces.

The.NRC staff is : urged,to reexamine this topic l

to ensure ' that slow buildup l off hydrogenr; from water-bearing ?

wastes-in sealed containers does : not; become a problem - for -

l long-term, safe. disposal..

4.

We believe that insufficient attentionihas'been given'to the testing of aged waste forms.

Many of the matrices, including concrete, that are used to contain wastes continue to change chemically and physically long after their: preparation. Owing y

to the longer term focus (i'.e.,

300 L years)! of the waste integrity. requirement, definitionc of the behavior of waste specimens that simulate aged waste formsiappears appropriate.

for inclusion 'in the - Technical -Position' where such testing t

appears. feasible and reasonably reliable.

The Committee notes that a part of the regulatory control over '

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4 low-level waste disposal is-based on Part.20 regulations (10 CFR 20. 311).

We urge that the NRC staff examine the revisions.

in Part 20 that affect low-level waste;and ensure,that'the Technical Position and the updated Part.20'are compatible.

6.

The Committee is aware that the newly. developed criteria for compressive strength of acceptable cementitious waste forms.

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The. Honorable Kenneth M; carr-3?.

September 6, 1990I o

-[500)-psi) ilacks.tstrong.Ltechnical ju'stificationf '. but! > was '

selected'to preclude the use of unstable waste forms.;The.NRC'

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staff should Lincludeiin~ thelTechnical Position recognition 3 tht.t the compressive strength that'is initially called for.mayL not% be.; retained a byh the, wastei form for1.its required.: life.L

.Long-term degradation of compressive strength to lower. levels,.

'but not~.less than the:approximately 60 psi required forJother-

. waste forms,smay beiacceptable.

We hope you will'findithese comments useful.-

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-Sincerely, 1

mr

_ _ Dade'W. Moeller.

Chairman r

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Reference:

Techhical. Position.'. on i

U.S.. Nuclear Regulatory Commission > Draf t; Waste - Form (Revision 1) dated - June 1990, o Prepared ' by ' Technical Branch, ' Division of Low-Level; Waste Management; and Decommissioning, (Predecisional) 2 E.

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