ML20247K458

Forwards Comments & Questions on Review of Us Ecology,Inc Rev 0 to USE-61-001-P, Stability of NS-1 Solidified W/High Strength Asphalt

ML20247K458
Person / Time
Issue date:	09/18/1989
From:	Tokar M NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS)
To:	Wong O U.S. ECOLOGY, INC. (FORMERLY NUCLEAR ENGINEERING
References
REF-WM-100 NUDOCS 8909210174
Download: ML20247K458 (17)

Text

y ^8J/RAIIMEM0 C- 'Mr. Oscar P. Wong .

Vice Prekident US Ecology, Inc.

Technologies Division 212 South Tryon street, Suite 300 #q p '1 y eu

Charlotte, North Carolina 28281

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Dear Mr. Wong:

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Subject:

US Ecology Report, " Stab' ility of NS-1 Solidified with High Strength Asphalt, Report No. USE-61-001-P,JRev. O. - Request for Additional Information. ,

1 The NRC has reviewed the subject topical report and has a need for additional ,

information. You are requested to provide the additional information as a response to the questions /consnents enclosed with this letter. The report was  !

L reviewed by NRC staff and consultants. Earlier we had as a courtesy sent you an advance informal set of ccmments/ questions prepared by NRC consultants. The enclosure to this letter is the official set of questions / comments on the subject topical report. Although you may have provided some information in response to our earlier informal questions, you are requested to provide a formal response to this formal request for additional information.

After the staff has an opportunity.to review your responses to these questions, we will arrange a meeting to resolve any out standing concerns on this topical report.

If you have any questions on this, please call me or Dr. Banad Jagannath  !

of n1y staff.

Sincerely, l Crisinni signed By Michael Tokar, Section Leader Technical Branch Division'of Low-Level Waste Management ,

and Decommissioning, NMSS  !

Enclosure:

as stated Distribution:

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.e PDR No: g / Reason: Proprietary / g / cr CF Only / /

.a g ACNW Yes:/ X / No:/ /

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Comments and Questions Review of U S Ecology, Inc. Topical Report on Stability of NS-1 Solidified with High Strength Asphalt Report No. USE-61-001-P, Rev. O, July 1988 WM-100

1. Section 2, last paragraph, page 2 What type of evaporator is in the TVR-III system that will be used for waste solidification at Nuclear Power Plants in U.S.A.? How does the waste form that will be produced by this system compare with the waste form that was produced using the LUWA evaporator in France? Provide justification for the applicability of the results from the LUWA produced waste form to those which will be produced using the TVR-III system. What are the controlling parameters that will establish the correspondence of these two products?

2. Section 4.0, page 4 What is meant by "high strength asphalt" ? Is this a generic name for a special product? It is difficult to identify or " finger print" asphalt based on a few properties of the material. If this is a special product identified by a manufacturer's code number and has product and manufacturing process specifications, then the results of this topical report review is applicable to use of only this particular product. US Ecology, Inc.(USE) should obtain assurances from the manufacturer that the product formulation will not be changed in the future. If the manufacturer changes the formulation, USE should be notified of such change. At that time USE should notify NRC and state regulatory agencies and cease to market the stabilization of NS-1 solidified with high strength asphalt until the use of new formulation is qualified through the testing and topical report evaluation process.

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3. Section 5.0 - Description of Waste, page 5 (a) USE should provide the chemical characteristics of the NS-1 solvent, as it l

is part of the information required in this review. If the composition of the NS-1 solvent is considered proprietary by the manufacturer and is thus not available to USE assurance must be obtained that the chemical l composition will not be altered in the future (should USE wish to continue to market its formula of NS-1 solidified with high strength asphalt).

Alternatively, if the manufacturer of the NS-1 solvent wishes to retain the option of altering the formula at some future date, assurance must be provided that USE will be notified of the changes. At that time USE is required to notify the NRC and the state regulatory bodies and to cease marketing the NS-1 solidification with high strength asphalt until the new formulation is qualified through testing and topical report evaluation process.

(b) The Dresden Nuclear Station Decontamination waste that contains NS-1 solvent used in the process is the reference waste in this topical report.

Would this Dresden waste be identical to decontamination wastes at other plants using the same process? If so, provide information/ data to justify that claim so that the results of this topical report review for Dresden NS-1 wastes can be shown to be generically applicable to wastes from other plants.

(c) What are the chemical characteristics of the decontamination waste including that of NS-1? The chemical characteristics of both this actual ,

waste and the NS-1 solvent used in the decontamination process that resulted in this waste should be reported. Provide information on the total organic carbon, inorganic oxides, pH, and total solids content of the actual waste. This data would be useful in demonstrating that the simulated waste corresponds to the actual waste.

(d) What is the chromate content of the actcal waste? According to NRC/ EPA joint guidance on mixed waste, Cr-51 does not cause the waste to be a mixed waste, since it is a radioactive isotope covered by NRC regulations.

However, the stable isotopes of chromium may be present if the

n, decontamination were conducted on Cr-rich steels. If they are, they could cause the waste to be EP Toxic, a mixed waste, and subject to EPA's RCRA regulations. An analysis is necessary to show otherwise. If the actual waste is determined to contain hazardous waste for which the vendor or the waste generator is legally responsible under RCRA, it is the responsibility of the waste generator and vendor to notify EPA and to satisfy EPA and state requirements.

_(e) USE should demonstrate that the simulated waste corresponds to the actual waste by documenting the characteristics of both actual waste (that has l been sitting in storage tanks for six years) and simulated waste (designed by IT Corporation). Provide details of all the ingredients added to the unused NS-1 to simulate the actual waste. Your response should address how the corrosion products and degraded chelating agents, which may or may not have deleterious effects on the final waste form, are considered in the simulated waste. The negligible effects of the full range of actual waste components on the stability of the simulated waste form need to be demonstrated before the results using simulated wastes can be considered representative of actual waste.

4. Section 5.0 - Description of Waste, page 6, last paragraph According to USE's analysis the NS-1 waste has an average of 30.37 % solids, and to obtain a 40% solid content approximately 40 / 30.37 = 1.317 volumetric units of waste should be solidified with asphalt to yield 1 volumetric unit of bitumen (High Strength Asphalt) stabilized waste form. As per Table 5.1 of the Topical Report, 1.317 units of the waste will have a 0.562 x 1.317 = 0.7306 total fraction of long-lived nuclides. This long-lived nuclides content (0.7306) of the solidified waste form is very close to the stated desirable upper limit of 75% of the Class C limit of I for a total fraction of long-lived nuclides. If the waste loading is higher, it could result in a situation where the waste form exceeds Class C limits. What is the degree of accuracy (+ or -) in your ]

estimation of the long-lived nuclides content of the waste, solids content of the waste, and control of the waste loading in the solidification process? How can you assu e that for a worst combination scenario of the above variables, the

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• I long-lived nuclide of the solidified waste will not exceed Class C limits?

Provide calculations to justify your position. ]

5. Section 6.1 Specimen Preparation - page 7, para 1 Explain the retreatment of the simulated waste and how this will simulate the retreatment of the actual waste as per the plant PCP. Provide a copy of the l

PCP that you will be using for this waste form. Identify the key parameters of this waste form that will be controlled by PCP during solidification. How do you control the percent bound moisture content of the waste form during solidification of actual waste?

6. Section 6.1 Specimen Preparation - page 7, para 2 (a) The two ways of processing wastes are not clearly explained. A brief description of the Luwa thin-film evaporator and the Guedu evaporator / mixer is requested, including their operational principles and operating temperatures. What type of processor will be used in full scale production? Describe the method of combining NS-1 and high strength asphalt in both the full scale and bench scale evaporators.

(b) All test samples, except the cubical samples prepared for biodegradation tests, were prepared at the CEA Laboratory in France. Explain in detail how the samples were prepared and how they were molded. Was the waste form coming out of the evaporator / mixer poured directly in to the specimen molds or was the product reheated / melted again to enable pouring the waste form into the molds? If this information is not available, please get the information from the CEA Laboratory which prepared the samples. However, all the tests were performed in the U.S.A.. Were these samples reheated / melted again in U.S.A to enable molding them into proper specimen size? The waste form scooped out from the split 50-gallon drum was reheated in the laboratory to mcld it into cubes. Was similar reheating done on any other test specimens? If the test data were obtained on reheated / remolded material, while actual wastes in the field are heated ,

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only once, explain how the test data can be applied to the prediction of real waste form properties.

(c) What was the temperature of the " hot bitumenized product" ? Was this temperature measured at the surface of the product or at the core of the product?

(d) How is the bound moisture content of the waste form determined? The average moisture content of the Guedu specimens was 2.0% whereas the average moisture contents of the Luwa specimens were 8.5% for samples from i

upper and middle portions of the drum and 1.25% for samples from the bottom portion of the drum (Tables 7.9.1 and 7.10.1 of Topical Report). Since the compressive strength drops from an approximate value of 600 psi for 2%

moisture content to an approximate value of 265 psi for 8.5% moisture content, the moisture content of the full scale solidified waste form is an important indicator of the compressive strength. How do you ensure that the moisture content of the full scale product in the drum will be close to 2% and that the moisture content will be relatively uniform throughout the full scale waste form product?

7. Section 6.1 - Specimen Preparation, page 7, para 3 (a) What was the original sample size in the molds before they were trimed?

How were the samples trimed? When the samples cooled to the room temperature, was there any shrinkage noticed, and if so, what is the order of magnitude of percent shrinkage? This shrinkage raises some questions about void spaces in the disposal containers. How much shrinkage occurs in full-scale drums, i.e., what is the percent fill of a drum cooled to ambient temperature and ready for disposal? After disposal in the burtal facility when the ambient temperature drops further to 55 degree Fahrenheit, how much further shrir,kage can be expected?

(b) Laboratory testing data presented in the appendices to the Topical Report list specimen dimensions as " average original diameter (in)", " average original height (in)", and " average height (in)." It is unclear as to how

the average values were obtained and if the " original" corresponds to the mold size. ASTM D-1074 states that the sample height shall be equal to the diameter within + or - 2.5%. In numerous samples, this requirement is not met (seesamplesizesofthermaldegradationtests). Provide an explanation for these deviations from the standard and the possible effect they may have upon the compressive strength of these samples. Provide justification for using these data in this report.

8. Section 6.2 - Compressive Strength Testing, page 8, As per the ASlN D.1074 test, the compressive strength should be determined at 77 degree Fahrenheit. Provide a justification for determining the compressive strength at 55 degree F. Is 55 degree Fahrenheit temperature an average ground temperature or equilibrium temperature of the waste form? Address the effect of the absorption of radioactivity by the bituminous material on the temperature of the solidified waste form. A few compressive strength tests should be performed at 77 degree Fahrenheit to provide information on the potential drop in compressive strength when the test temperature increases from 55 to 77 degree Fahrenheit, and also to demonstrate that the compressive strength at 77 degree Fahrenheit is higher than 60 psi. The test data sheets presented in the appendices to the report state the compressive strength test temperature to be 50 to 55 degree Fahrenheit. Was the test temperature 50 or 55 degree Fahrenheit? What is the estimated increase in compressive strength when the test temperature drops from 55 to 50 degree Fahrenheit?

! 9. Section 6.2.2 - Leach Testing / Immersion Testing, page 8, para 3 Nickel tracer is mentioned here but not in the sample preparation section.

Provide the details on how much nickel was added in sample preparation.

10. Section 6.2.2 - Leach Testing / Immersion Testing, page 8, para 4 What analytical method was used to determine total solids?

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11. Section 6.2.2 - Leach Testing / Immersion Testing, page 9, para 1 The NRC Technical Position on Waste Form requires the leach test samples to be similar in size' as those used for compressive strength tests (ASTM D1074).

'What size sample was used for the leach tests? Justify any variations from the suggested standards.

12. Section 6.2.3 - Radiation Testing, page 9, para 2 Why were samples wrapped as described? Does radiation induced deformation occur? If so, how much swelling occurred? The amount of swelling will be dependent on waste type and loading, as well as the binder material. If less swelling occurs at a lower dose rate, this should be stated.

13. Section 6.2.5 - Thermal Degradation Testing, page 10, para 2 What was the size of the samples before the test was conducted? How were the samples " trimmed"? The thermal cycling test does not conform to the ASTM procedure exactly. ASTM B553 specifies that the samples should be maintained at the high and low temperatures for an hour. The vendor should explain why this was not followed and justify the deviation from the standard procedures.

14. Section 6.2.7 - Free Liquids / Homogeneity ,

The test for free liquids and homogeneity were made on a 55 gallon drum of NS-1/high strength asphalt product produced at CRC in France. 1/ere the conditions and procedures for making the specimen identical to those that would be used in the U.S.A.? Is the Luwa LN-0050 thin-film evaporator, used in France to prepare this 55 gallon drum waste form, identical to that in use at Commonwealth Edison? If not, explain how the French test results are applicable to the process in the U.S.A..

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i y q - 15. Section 7.2 - Compressive Strength Testing, Table 7.2.1 Provide the average and standard deviation for the compressive strength test.

L results. In general; statistical data should be provided when more than one test result for a particular test is being reported.. Statistical data are

important in deciding if a process is well-controlled. This connent is

. applicable to all the test results presented in'the report.

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16. Section 7.2 - Compressive Strength Testing, page 12, para 2 (a) What is the justification for excluding the compressive strength result for specimen No. 13? It had a compressive strength of less than 82 psi at 10%

deflection.

'(b) Sample No. 21 demonstrated a brittle behavior by failing at 8.7% deflection whereas other samples failed at much larger deflections and did not

' demonstrate this behavior. Discuss the reason and consequences of this.

behavior on the long-term performance of the waste form.

17. Section'7.3 - Leach Testing, page 12 -13 (a) The leach test specimens were a non-standard geometry, being more disc-shaped than cylindrical. Explain why this geometry was chosen although the NRC guidance on testing recommends a sample size similar to that for compressive strength tests. Justify the validity and applicability' of these results.

(b) Appendix A-3, which presents the raw data for leach tests, mentions that samples 19A and 198, tested in demineralized water, were " concave on the bottom". In contrast, samples in synthetic sea water were "almost unchanged in appearance". Were the concavities for the specimens in demineralized watter caused by some sort of dissolution / degradation mechanism? Measurements of sample dimensions and a picture of each should be provided to show that degradation of the sample did not occur and that

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swelling was not severe enough to affect the calculation of the leach index.

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18. Section 7.4 - Immersion Testing, page 14, Table 7.4.1 (a) Appendix A-3 does not present any documentation of the immersion test but only presents compressive strength test data. Provide the documentation of observations made during the immersion test, particularly on observed degradation and swelling, if any. Was the water used in the test discolored after the test was completed? If so, does it indicate that a soluble material is being leached from the specimen? What were the sample dimensions before and after the test? Did any of these samples exhibit degradation, for example swelling, surface cracking or pitting ? If swelling was observed, what was the atnount of swelling and what are its implications on the long-term stability of the waste? Would the swelling continue indefinitely, or would it stop and at what point? Similar concerns apply for surface sof tening effects also. Were the bottom surfaces of most of the samples concave at the end of the immersion test, and if so, how did the concave surface affect the results of the compression strength tests. Pictures of the specimens before and after the immersion tests should be provided.

(b) There is a significant effect of imersion on compressive strength; viz., a drop to about one-third of the original strength (from 739 psi to 250 psi).

Although the post-immersion strength is higher than the minimum strength stipulated in the staff technical position on waste form stability, the effect of this on satisfying the long-term stability requirements of the regulations should be discussed. Evidence should be provided that the compressive strength will not continue to decline with longer periods of immersion (beyond 90 days).

19. Section 7.5 - Radiation Testing, page 14,

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(a) Provide data on the swelling measured and percentage swelling for all samples tested under this Irradiation Testing program.

" (b). Seven holes were drilled through the entire length of Sample No. 12, and it showed less swelling than other samples. Do you have any observations / conclusions on the effect of these holes on the results obtained in the laboratory test? 'In addition, all the ramples~ failed at between 4 to 8 percent deflection and exhibited brittle behavior. What is I the combined effect of this brittle behavior and swelling tendency on the j long-term stability of the waste forms?

20. Section 7.6 - Biodegradation Testing, G-21 Test, page 15-16, Although no fungal growth was observed on the tops and sides of the specimens, some was observed attached to the bottom and sides of the specimen. Was there a boundary, a small distance away from the surface, at which the growth began to occur? The argument about a "leachate" supporting the growth is reasonable, and probably tree. The leachate is expected to contain NS-1 and nitrate salts, both of which support biological activity when combined with the nutrient salts agar.

The lack of growth st the top and sides could be due'to the lack of essential salt nutrients which are provided in the agar suspension. However, the TP specifically states that "some visible culture growth from contamination, additives or biodegradable components on the specimen surface which do not relate to overall substrate integrity may be present. For these cases, additional testing should be performed." The last paragraph of page 16 states "the presence of Microban... had no effect on fungal growth since the growth seen on the bottom edges of the specimens .... were comparable in the three evaluations." From this it can be concluded that growth did indeed occur on the surface of the specimen. Photographs submitted with the report do not definitively resolve this issue. Additional testing in accordance with the Technical Position recommendations appears to be warranted.

21. Section 7.6 - Biodegradation Testing, 3-22 Test, page 17 l

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' The same conclusion as for the G21 test results applies, that further testing is required. The presence of growth in the agar adjacent to the specimens means-that the specimen component; i.e., leached component of the waste form, has l supported the growth, and therefore, that the specimen failed the test.

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22. 'Section 7.7 - Thermal Degradation Testing, page 17 l l

The results of the compressive strength tests should be tabulated. Also provide j the averages and standard deviations for this data. Data including width, height, and weight of the samples before and after the thermal cycling test is ,

given in Appendix A-6. Data for the compression testing, namely, average  ;

1 diameter and average tnight, do not correspond to the same data before or after the thermal cycling test. Also, the heights of the test samples for the compressive testing are well over 2 in., while the diameters are approximately 2 ,

in. As per ASTM D 1074, the saeple height should be equal to the diameter I within 2.5 %, and these samples do not comply with these standards. The effects of the sample height increase on the results of the compressive  !

strengths should be discussed.

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23. Section 7.8 - Solids Content and Tracer Content, page 18 )

Why are the data from test 3 (CEA, France) is missing W Table 7.8.1 ?

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24. Section 7.9 - Free Liquids / Homogeneity, page 18 (a) What recipe was used for preparing the 55-gallon drum of simulated waste? ]

How were the 2-inch by 2-inch specimens for compressive strength testing  !

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" extracted" from the 55-gallon drum and molded? Was the bound moisture content determined on the material chiseled from the drum or from the i 2-inch by 2-inch samples after the compressive strength test?

(b) The correlation between bound water content and compressive strength suggest that the process must minimize bound water content to " achieve the

I maximum practicable compressive strengths" and thus be consistent with the intent of the TP. Is this reflected in the PCP? Will the PCP ensure that the bound moisture content of the bitumen stabilized waste will be less than 2 percent?

(c) Why are the data on solids content and bound moisture content in Table l

7.9.1 presented as a range? Provide the actual values for individual samples rather than as a range. Note that similar data for Guedu' specimens in Table 7.10.1 are presented as actual test values. Are the bound l moisture content data available for other samples tested in this program?

If so, provide them.

(d) How does the 7-10 % moisture content product behave on immersion? If a corresponding decrease of compressive strength occurs as noted earlier, tests should be conducted to demonstrate that the higher water content product will also pass the immersion test criterion.

(e) There was a variation of moisture content in the 55-gallon drum product because the parameters were varied during molding. Once the parameters that would yield the desirable product with a moisture content of 0.5 - 2.0 percent were fixed, was another 55-gallon drum sample prepared, and if so, what was the pattern of distribution of misture content in that drum?

(f) Table 7.9.1 indicates that the bounded moisture content and compressive strength at various locations within the drum varied significantly. How then can there be a claim that the product is homogeneous by virtue of the compressive strength being higher than 60 psi? In fact the compressive strength varied from a low of 255 psi to a high of 620 psi.

(g) When the samples from the drum were extracted, melted and then molded to the compressive strength test samples, the material taken from the drum should have lost some bound moisture. It is possible that the actual bound moisture content of the compressive strength test samples may be lower than the moisture content of the mixture in the drum. If there is a direct correlation between the moisture content and compressive strength, the compressive strength of the mixture in the drum may be lower tht.n the

L strength determined from remolded samples taken from the drum. Are there data on the distribution or variation of moisture contents of mixtures in drums where the mixture has not been reheated to mold samples?

25. Section 7.10 - Correlation of Luwa Specimens and Guedu Specimens, page 19 (a) The table on page 20 should be numbered correctly as 7.10.1.

(b) Why are solids and bound moisture contents for the Luwa specimens reported as a range of values rather than a specific value? How is the bound moisture content determined?

(c) For the test data presented in Tables 7.9.1 and 7.10.1, there are two

" average dimensions" listed for each sample. Please explain.

26. Appendix A-1, Compressive Strength Data, The compressive strength test data sheets indicate the compressive strength as compressive load. Is there any difference between the two or is it a case of terminology?

27. Appendix A-2, Leach Test Data (a) A-2 is incomplete in that some of the data that belongs in this Appendix is contained in A-3. Present all the Leach test data in the appropriate section.

(b) With reference to the data sheets describing leach tests (now in A-3), the two samples tested in detonized water were both " concave on the bottom" after the test was completed. USE should provide before and after test sample dimensions and a sketch if pictures are not available.

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(c) Cursory checking of the leach index calculations revealed a discrepancy in the calculation of S/V for sample 19A. This will not significantly change i calculated. leach indices, but it does raise questions about the index calculations in general. Please comment on the accuracy of your leach

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index calculations.

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28. Appendix A-3, Immersion Test Data l USE should provide before and after photographs of the immersion test specimens, I and the sample dimensions before and after the test as well. The shape of the  :

stress-strain curve is very different for the immersed samples; provide an explanation for this. l l

29. Appendix A-4, Irradiation Test Data (a) USE should verify that the samples which had lower than 60 psi strength were different formulations other than NS-1 in high strength asphalt. (All other samples are identified in other test result reports)

(b) Some data on the amount of swelling observed as a result of radiation ,

damage is needed, e.g. pictures or measurements. The radiation-induced swelling is disturbing. Are there data to show that a lower dose will  ;

result in less swelling? What do the changes in sample height indicate about the waste behavior over long-term?

I (c) The' assumption that hydrogen gas is the cause for swelling is open to I question, since the waste form is a mixture of bitumen, NS-1, and nitrate l salts. Is there generation of any other gases (with lower diffusion rates through bitumen) that could be causing swelling? l l-

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30. Appendix A-5, Biodegradation Test Data

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c. 1 (a) The weight of the samples changed durir.g these tests. Provide an explanation for this change in weight. Was similar phenomenon observed in i 1

immersion and leach tests?

(c) What was the shape of the samples? The data sheets suggest cubical samples l

were used. ASTM D1074 specifies cylindrical samples be used; otherwise, comparisons with other sample geometry test results are invalid. What is the effect of change of the specimen shape on-the measured compressive strength? The shape of the stress-strain curve for both the cylindrical and cubical specimens should compared to support their comparable behavior.

Provide a justification to support the use of this data.

31. Appendix A-6, Thermal Degradation Tests (a) It is interesting to note that two of the three test samples lost weight and became longer, even though they were wrapped with tape. Explain the weight loss and elongation of the sample. Also, all three of the pure asphalt samples expanded along the cylindrical axis. Is there an explanation for this permanent volume change?

(b) The xerox copy of the picture in the report is dark and unclear. Provide a clear copy of the picture with a caption explaining the picture.

(c) The results of compressive strength testing (since they are not tabulated in the main section of the report) should be presented in a tabular form.

32. Appendix A-8, Free Liquids / Homogeneity Data (a) Notes on the testing laboratory's summary report state that the " samples were melted and remolded from submitted specimens." What did the submitted samples look like and what were their dimensions? What were the dimensions of the molded samples? Was there a reduction in the bonded moisture content when the sample was melted for molding? If so, what is the effect

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i of this on the measured strength and behavior (i.e. viscoelastic or brittle nature) of the material? {

33. - Appendix A-9, Correlation of Luwa and Guedu Specimens Data Again, these samples were " melted and remolded" into cubes. However, these l specimens exhibited brittle / fracture behavior. Do you expect all waste forms produced as per the PCP to result in relatively hard specimens that would l exhibit fracture-failure type stress-strain relationships? How many samples tested in this program exhibited similar behavior? Discuss the effects of melting and remolding on the physical / mechanical properties or the waste form.

How can melted and remolded specimen be considered to be representative of the actual waste form, which will not be subjected to this reheating / melting process?

34. Appendix B-1, Waste Analysis Was the sample filtered before analysis?

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