ML19341C099
| ML19341C099 | |
| Person / Time | |
|---|---|
| Issue date: | 02/13/1981 |
| From: | Scarano R NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS) |
| To: | Campbell R ENERGY, DEPT. OF |
| References | |
| REF-WM-39 NUDOCS 8103020029 | |
| Download: ML19341C099 (5) | |
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FEB 13 1981 HMUR:WMS dLUL L
E Richard H. Campbell, Project Manager 6-TED 1 g gggg., Q UMTRAP Project Office
[ p.v.s.e g g ll [ k U. S. Department of Energy Albuquerque Operations Office pJ k
P. O. Box 5400 A
Albuquerque, New Mexico 87115 v
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Dear Mr. Campbell:
In response to your December 4,1980 letter, regarding NRC participation in reviewing DOE's asphalt tailings seal development program, we have completed our review of tne Pacific Northwest Laboratory (PNL) 1980 Annual Report entitled, " Asphalt Emulsion Sealing of Uranium Mill Tailings."
This was forwarded to us directly, as discussed in your reference letter, by J. N. Hartley of FNL.
In connection with this review, it was greatly r
appreciated that PNL, Sandia National Laboratory (SNL), and DOE staff provided a thorough review of FY1980 and planned FY1981 program activities at NRC-Silver Spring, Maryland, on February 3,1981. Our comments, as
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provided in Attachment I, therefore represent our assessment of the program in general as well as being directly applicable to the Annual Report itself.
It seems that while the use of an asphalt emulsion seal system in tailings reclamation is promising, the technique has not been developed sufficiently for application in the near future.
It may however be developed in time to be utilized in the later stages of the UMTRAP or subsequently by the uranium milling industry.
If DOE decides this technique is sufficiently promising to continue its development, we would be pleased to continue to provide technical review support to your staff.
Any questions you may have may be addressed to myself or William M. Shaffer, III (FTS427-4055) of my staff.
Sincerely, Ross A. Scarano, Chief Uranium Recovery Licensing Branch Division of Waste Management
Attachment:
As stated cc:
See next page 810302 0pg9
. 4*
CCs from lott r to R. H. Campbell re PHL 1980 Annual Report cc: William Mott, DOE-HQ Robert W. Ramsey, DOE-HQ Paul O'Brien, SNL-Albuquerque, NM J. N. Hartley, PNL-Richland, WA 9
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i Attachment I NRC STAFF COMMENTS ON DOE UMTRAP ASPHALT TAILINGS SEAL DEVELOPMENT PROGRAM
References:
a.
PNL 1980 Annual Report, " Asphalt Emulsion Sealing of Uranium Mill Tailings," December 1980.
b.
DOE /PNL/SNL Review of Tailings Seal Development Program, February 3, 1981, NRC-Silver Spring, Maryland.
1.
Retalts thus far, of testing seal effectiveness are reported as having already experimentally demonstrated achieved reductions in radon exhalation.
It should therefore be acknowledged and reported that this was determined with the radon measurement system also under development, simultaneously with the development of the seal itself.
2.
The asphalt emulsion seal layer requires the overburden layer covering it to protect the seal from ultraviolet light induced degradation.
It is felt therefore that the program ought to henceforth be scoped as a tailings seal system development program where the system is the asphalt emulsion seal layer in combination with the overburden layer.
3.
The PNL developed radon measurement system, utilized thus far in the program, appears to be a very positive step towards a system haying good field application potential as well as high potential accuracy. We strongly encourage further development of this system with a view to also normalizing its performance against other radon measurement systems under development by DOE and others.
4.
At the meeting it was mentioned that DOE plans to establish a pro'granmntic focal point (possibly at Argonne National Laboratory) for normalization and integration of the various radon measurement systems development programs underway. We strongly support this step and recomend that PNL's system be included as one to be considered by this R&D focusing effort.
5.
The prime NRC staff concern is adequate demonstration of the long-l term performance and stability of a relatively thin synthetic material based radon seal.
"Long-tenn" in our view means thousands of years.
If the DOE feels results thus far have shown adequate progress to warrant further development, we therefore also urge continuation and expansion of the pregram into the comparative side-by-side field test phase on a relatively large scale (i.e.,
l multiple-acre size surface areas per tailings cover system tested) for as long as feasible. This phase should encompass comparison of the three systems noted in the report:
(a) asphalt emulsion / overburden l
sealing system, (b) multilayer soil / rock / vegetation radon barriers, j
i (c) soil overburden only.
i
2-6.
We are encouraged by the extent to which active field evaluation and development of production scale seal application systems is underway.
In this context, we believe that highest priority should be given to the cold-mix payer operating over a stabilized soil base.
If funds are available, other systems may be further developed for comparison; but we agree that the cold-mix paver is the most promising.
7.
We note that some UMTRAP sites are currently sche'duled (Draft 1980 00E Annual UMTRAP Report to Congress) for initiation of remedial action in the CY 1982-83 time frame.
This is probably too early to reasonably expect that asphalt emulsion seal system development will have progressed far enough to be considered for utilization at these sites. Thus, it would appear that only the later scheduled UMTRAP sites could be considered as potential candidates for application of the system.
8.
Assuming that it appears feasible that the long-term performance of this cover system can be demonstrated, compared to the soil / vegetation / rock system currently acceptable to NRC, we believe the system comparative cost / benefit studies, mentioned at the meeting as underway, should be continued as a parallel high priority program element.
9.
It is felt that the report itself states too strongly that the program has determined that the asphalt emulsion seal system possesses properties required for long-term effectiveness.
We believe that results to date point in that direction (apparent "self-healing" of the seal for example), but feel that much more needs to be done to
" determine" that those properties are in fact retainable over the long term. Significant artifically induced tailings dislocations under a field test seal system, for example, would help to establish to what extent "self-healing" is practically achievable.
10.
It is felt prudent to give low priority to further tests utilizing tailings themselves as the seal aggregate material unless it can be shown that the heterogeneous nature of tailings piles will not have a detrimental effect on long-tem seal system effectiveness. We believe this will be extremely difficult to demonstrate since, in effect, one would have to be able to definitively characterize every square foot of tailings surface to be sure of the degree and type of non-homogeneity present. This is one of the prime reasons that mine wastes are prohibited from use in "near surface" (top three meters) tailings cover materials by current NRC regulations applicable to uranium mill licensing.
- 11. A program element should be implemented to characterize radon exhlation anomalies, if any, at the edges of the completed seal system.
, 12. At many tailings sites, self sustaining revegetation may not prove practicable. Thus, the effect of rock covering n r the soil overburden layer should be investigated.
- 13. Utilization of the asphalt emulsion seal system must ultimately be considered on a site-specific basis.
Thus, as discussed at our meeting, the seal system would have to be tailored to each site.
The Grand Junction Site is however a logical choice for the field test program, and we support continuation of that' part of the program at that site.
14.
In the Conclusions section of the report (page not numbered, 5th item on that page), we do not agree that the asphalt emulsion seal system has been developed to the point where one can say that it "should last 1000 years."
In accordance with current NRC regulations, the NRC staff would express this, even on a judgmental rather than conclusive basis, as "for long time periods (i.e., thousands of years)." However, we only take note of this point on wording, and do not suggest a wording change.
- 15. Appendix B, the Long-Term Stability Research Plan referenced in the 1ecommendations section of the report, is in our judgement the most important element of the overall future plan to demonstrate the potential acceptability of this type of tailings cover system.
However, Appendix B does not currently present an integrated plan to do this, but rather a group of isolated efforts related to it.
i We suggest that Appendix B Le recast to reflect a milestone referenced integrated set of individual R&D objectives leading to an overall milestone at which long-term stability will have been demonstrated to DOE's satisfaction, timed such that the asphalt emulsion seal system concept could be proposed to NRC for utilization at one or more UMTRAP sites.
- 16. We strongly support the field characterization of interactions betweer the seal ystem and tailings below it.
- 17. We strongly support the reconinendation that the development of basic system engineering specifications suitable for use by an A-E firm, be one of the overall progra7 objectives.
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