ML20058N916
| ML20058N916 | |
| Person / Time | |
|---|---|
| Issue date: | 10/13/1993 |
| From: | Thoma J NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS) |
| To: | Rowland T ENERGY, DEPT. OF |
| References | |
| REF-PROJ-M-32 NUDOCS 9310210189 | |
| Download: ML20058N916 (10) | |
Text
{{#Wiki_filter:. L ' Project M-32 / 'Mr. Thomas P. Rowland, Director West Valley Project Office %)CT 13 gg3 U.S Department of Energy P.O. Box 191 West Valley, New York 14171
Dear Mr. Rowland:
SUBJECT:
REQUEST FOR ADDITIONAL INFORMATION FOR " WASTE FORM QUALIFICATION PROGRAM FOR CEMENT SOLIDIFICATION OF SLUDGE WASH LIQUID" CONCERNING SOLIDIFICATION WITH TYPE V PORTLAND CEMENT The Nuclear Regulatory Commission staff and its contractor, Brookhaven National Laboratory (BNL), have conducted a technical review of the information contained in Volume 3 of the qualification program _(QP) notebook, specifically the process control plan and the qualification report. We have concluded that the QP must be supplemented by additional information, as specified in the enclosed request for additional information (RAI), before-additional review and consideration of NRC approval can proceed. In respond!ng to the RAI, West Valley Nuclear Services (WVNS) is requested to discuss the questions with NRC through correspondence and/or discussions prior to initiation of any testing programs resulting from the questions. Additionally, WVNS is requested to provide formal responses to the questions, or a detailed schedule for responding to the questions (if additional testing is required), no more than 60 days from the date of this letter. NRC will consider the responses and also forward them to the BNL reviewer. Sincerely @;inal Signed by ) John 0. Thoma, Section Leader Technical and Special Issues Section Low-Level Waste Management Branch Division of Low-Level Waste Management and Decommissioning Office of Nuclear Material Safety and Safeguards
Enclosure:
As stated DISTRIBUTION: Central File LLWM r/f JGrreves JAustin JKennedy PLohaus J. Holonich MTokar HMSS r/f MagSmal1[B. oxes?inTConduf}$ C6~pKMf5Fsn'ch In small Box on "0FC" line e}'i5)Q16W46[DdffnelDlHFili0tl1o(losure; N = No Copy nter: C = cover; E = cover ik Enc 0 SEE PREVIOUS CONCURRENCE OFC LLWB E FCLB E LLWB E LLWB E NAME RLewis* GComfort* JThoma* 7 07 MBefi/ A DATE 10/12/93 H 10/12/93 H 10/13/93 H /4 /R/93 / /93 S:/LLWMTYPE/T'VPE5RAllJL OFFICIAL RECORD COPY In small Box on "DATE" line enter: M = E-Mail Distribution Copy; H = Hard Copy PDR: YES X NO Category: Proprietary or CF Only ' M h )p, ACNW: YES N0 )_L Mt IG: YES NO X Delete file after distribution: Yes X No _ OAADOA !!$"M' [ NBC RE CETEfi89P
/
- Project M-32
'Mr. Thomas P. Rowland, Director West Valley Project Office U.S. Department of Energy P.O. Box 191 West Valley, New York 14171 Dear Mr. owland:
SUBJECT:
REQUEST FOR ADDITIONAL INFORMATION FOR " WASTE FORM QUALIFICATION PROGRAM FOR CEMENT SOLIDIFICATION OF SLUDGE WASH LIQUID" CONCERNING SOLIDIFICATION WITH TYPE V PORTLAND CEMENT The Nuclear ReguTgtory Commission has contracted review of the. subject qualification progr4m (QP) notebook, submitted by the U.S. Department of Energy (D0E) in final form in August 1993, to Brookhaven National Laboratory (BNL). The technical \\ review included information contained in Volume 3 of the QP notebook, specifically the process control plan and the qualification report. N NRC staff and BNL have conc uded that the QP must be supplemented by additional information, as spe\\jfied in the enclosed request for additional information (RAI), before additib al review and consideration of NRC approval can proceed. In responding to the RAI, West Valley (uclear Services (WVNS) is requested to discuss the questions with NRC through bqrrespondence and/or discussions prior to initiation of any testing programs res lt_ing from the questions. Additionally, WVNS is requested to provid(e Yormal responses to the questions, or a detailed schedule for responding to the uestions (if additional testing is required), no more than 60 days from the da of this letter. NRC will consider the responses and also forward them to he BNL reviewer. Sincerely, John 0. Thoma, Sec on Leader Technical and Specia NIssues Section Low-Level Waste Manageiirent Branch Division of Low-Level Wa e Management and Decommissioning Office of Nuclear Material 5 fety and Safeguards
Enclosure:
As stated DISTRIBl) TION: Central File LLWM r/f JGreeves JAustin JKennedy PLohaus J. Holonich MTokar NMSS r/f tiillGSsillf@isWCbhjiigihEi3@46}Difth(DMjlhiWo@losu)re; NT Ni(c@opy j igsf'We In small Box on "0FC" line enter: C = Cover; E = Cover & Enc 4-SfE"PRfv!005-{0NCURREEN OFC LLWB E FCLB 6 LLWB E LLWB NAME RLewis /A A GComfortNC JThoma W MBell DATE 10/12/93 M 4 / /2/93 N lo /$/93 H / /93 / /93 S:/LLWMTYPE/ TYPE 5RAI.RJL OFFICIAL RECORD COPY In small B x on "DATE" line enter: M = E-Mail Distribution Copy; H = Hard Copy PDR: YES NO Category: Proprietary or CF Only ACNW: YES NO W IG: YES NO.1. Delete file after distribution: Yes N No __
4 e REQUEST FOR ADDITIONAL INFORMATION NUMBER 1 WASTE FORM OUALIFICATION PROGRAM FOR SOLIDIFICATION OF SLUDGE WASH LIQUID IN TYPE V PORTLAND CEMENT Submitted By: West Valley Nuclear Services Through: United States Department of Energy As part of their West Valley Decommissioning Project (WVDP) activities, West Valley Nuclear Services (WVNS) has prepared the title document. Review of the waste form qualification report (referred to as the report below) and a process control plan (PCP) led to the following questions. The Nuclear Regulatory Commission based its review for stability against the requirements of 10 CFR 61.56 and the guidance of the Branch Technical Position on Waste form, Rev. 1 (BTP). Brookhaven National Laboratory (BNL) is providing technical assistance in this review at the request of NRC. WASTE FORM OVALIFICATION REPORT Sec. 3.0 Waste Characterization Nominal properties of the decontaminated sludge wash solution are presented. Table 2 summarizes the chemical composition of the actual sludge wash solution (before ion exchange). Table 3 shows major radionuclide constituents in a 27 wt percent Total Dissolved Solids (TDS) sample, and Table 4 lists minor radionuclides detected in a 20 wt percent TDS sample. Radionuclide measurements were for decontaminated sludge wash solution. (1) What is the chemical composition of the decontaminated sludge wash solution? Since WVDP wants the solidification process approved for a range of compositions, the expected range of compositions for the wash should be described in this section. Data reflecting measurements should indicate number of samples and uncertainties (standard deviation) in the measurements. (2) Why are the samples' wt percent TDS different for tables 3 and 4? i Does this reflect the possible range of composition differences ] downstream of the ion-exchanger? Will the racionuclide composition j change as the ion-exchange beds are depleted? Are there process controls in place to prevent breakthrough of radionuclides that will exceed class C limits? Section 4.0 Minimum Requirements of 10 CFR Part 61.56(a) This section lists the minimum requirements of 10 CFR Part 61.56(a), and describes how the cement solidification process meets each one. All the minimum requirements are fulfilled by the process. Section 4.8, on requirements affecting " hazardous, biological, pathogenic, or infectious material," presented data from Environmental Protection Agency (EPA)- mandated Toxic Characteristic Leach Procedure (TCLP) tests. The report j Enclosure l
s concludes that the solidified waste can be classified as non-hazardous according to the test results. (3) Are the results acceptable under the land disposal restriction requirements contained in 40 CFR Part 2687 i Section 6.0 Testing with Decontaminated Sludge Wash Section 6.1 describes a separate test program that was conducted to establish process limits according to decontaminated sludge wash characteristics. Ten drums of decontaminated sludge wash at 30 wt percent TDS were prepared and tested. A sulfate solution was added to the original solution to increase sulfate concentration from 10 wt percent to 11 wt percent. The spiked samples were prepared in anticipation of chemical compositional changes in subsequent sludge wash operations. Eleven drums of the spiked sludge wash were prepared and tested. No test data are reported in Section 6.1. Section 6.2 describes concentration of solutions for solidification in the evaporator. The preparation of 25 wt percent, 30 wt percent, and 33 wt percent TDS solutions for solidification was apparently sequential, starting with the lowest TDS the starting point. Sulfate spiked solutions were prepared by adding sulfate solution and demineralized water to the 33 wt percent solution. Salt composition changes from evaporator operations are given in Table 5. (4) Have any tests been conducted to show whether subsequent sludge washing operations will have higher percentages of sulfate? What changes are expected in the percentages of other chemical components? Will radionuclide composition change? Any available data should be reported or referenced. (5) Table 5 should indicate the accuracy (uncertainties) in the measured percent salt values. Why was sodium not recorded? (6) The description of samples prepared for BTP testing should be presented so that it can clearly be seen what process limits are anticipated and what samples provide the data for those process i limits. A Figure and/or Table summarizing the limits and samples corresponding to the limits would be appropriate. 7.0 Requirements of 1991 Technical Position on Waste Form This section presents the results of qualification test results. The tests and acceptance criteria used were those recommended in the 1991 Technical Position on Waste Form (BTP). Core samples for testing were obtained from full-scale waste forms prepared as described above. Characteristics of the five full-scale waste forms used for samples are contained in Table 7 of the report. Table 7 also lists compressive strength results for cylindrical core samples, 2-inch cube samples, and 90-day immersion compressive strengths. (7) Four of the full-scale samples tested were spiked with sulfate; one was not. Why choose only one drum that corresponds to the actual (anticipated) sludge wash conditions? i 2 i 4--
i 7.'l Compressive Strength Results from compressive strength testing are presented (Table 7). The average strength of thirty core samples was reported to be 1230 psi. The thirty cores were obtained from the five full scale waste forms mentioned above. Waste compositions in the five forms covered a range of total dissolved solids (26.1 wt percent to 33.1 wt percent) and water-to-cement ratios (W/C = 0.49 to 0.55). Four of the five waste forms had been " spiked" with additional sulfate solution. The reported compressive strength average includes the results for all waste compositions. (8) Averaging compressive strength values for different compositions confuses the issue of the full range of waste compositions to be covered in the qualification test program. The data for each composition qualifies that composition only, and should not be averaged with data for other compositions. The range of compositions to be qualified should be explicitly stated, with data for the limits of composition reported as qualifying that limit. (9) Two drums, #83212 and #84894, were prepared with identical w/c (0.52) and waste TDS content (30 wt percent). Data from these drums are repeated in Table 8 and plotted in Figure 5 to show that the compressive strength increases with time. The data are averaged to get a " recipe average." If the point of this table is to show time dependence, then the data should np1 be averaged. If anything, the data show the variability in the compressive strength from one drum to the next, and that the compressive strength is decreasing with time. At the end of Section 7.1, it is concluded that "near-maximum strength has been obtained for this waste form." What is the maximum strength achievable? How do these data show it? (10) Another way of presenting the Table 8 data is shown below. -Two possible interpretations are: (1) compressive strength can vary as much as 400 psi (or 25 percent to 36 percent) from one waste form to the next, (2) different forms' strength variations are negligible, and the maximum strength (about 1600 psi) is reached before 120 days curing, with a subsequent decline in strength. What interpretation should be applied to this data? The interpretation given on page 7 may be acceptable, but the justifying arguments are inadequate. (11) Which factor (s) affect compressive strength and thus should be monitored in a PCP most carefully: waste composition (sulfates, organics, TDS, Ph, etc.), water / cement ratio, cement composition, process parameters, or others? These should be discussed at some point. t 3
V 1 Compressive Strength Results (psi) Drum No. Cure Time Position Strength Average (days) in Drum (psi) Strength (psi) 83212 93 Top 980 1150 f140 Middle 1230 Bottom 1230 83212 97 Top 1360 1170 i200 Middle 1190 Bottom 960 84894 105 Top 1550 1580 1044 Middle 1630 Bottom 1560 e 84894 120 Top 1280 1223 1098 Middle 1280 Bottom 1110 Section 7.2 Radiation Resistance No radiation testing was performed, because "only trace quantities of organic materials" are present. (12) What are the " trace" quantities? Considering how these affected supernatant solidification, it is surprising these are not discussed more. Has an analysis been conducted for total organic carbon? What levels were found? Section 7.3 Biodegradation Resistance No biodegradation testing was performed, bera"-a "only trace quantities of organic materials" are present. Section 7.5 Immersion Resistance Immersion test results are summarized in Tables 7 and 9. The samples tested covered the range of compositions tested for compressive strength. Four of the 15 samples immersed were cracked or spalled enough so as to be unacceptable for testing. One sample was broken accidentally. The remaining 10 samples tested for compressive strength showed higher compressive strengths compared to " pre-immersion test" values. (13) Why does the cement used for the sample without a sulfate spike (drum #83552) have a lower C A content than all the spiked samples (see Table 7)? A sample with lower C A might be expected to perform 3 better against sulfate attack during immersion. What is the range 4 O I
e f of compositions that is specified for the cement to be used in the process? (14) Three of the six samples made with the 30 wt percent TDS sludge wash I solution failed the immersion test by cracking during immersion. One sample made with 26 wt percent TDS sludge cracked during j capping, before compressive strength could be measured. It was postulated that the coring operation "might have created hairlir.e fracture (s) in the sample during coring and removal from the drum that was not noticed at that time." What evidence justifies this hypothesis? Confirmatory tests, for example, samples prepared from small-scale molds, rather than coring, would verify the hypothesis. Did any leach test samples exhibit cracks? Were the leach test samples left in water for longer than five days? Section 7.8 Full-scale Specimen Test Results This section discusses the homogeneity of the waste forms prepared under full-scale conditions. The main argument is that " compression [ test] results of the 30 cores tested (Table 7) were found to be statistically from the same population and showed no visible inhomogeneities." (15) What range of compressive strength values represent the limits of the " statistically same population"? (16) What would WVl;S consider a visible inhomogeneity? Some of the cores appear to exhibit some inhomogeneities, such as bubbles (photographs AP-7, AP-11) or non-uniform discolorations (AP-17, AP-18). Section 7.10 Process Control Program (PCP) This section summarizes the PCP under two subject areas: 1) process parameters, and 2) verification and surveillance specimens. 7.10.1 Four variables are identified as important process parameters. Their respective limits are: f I l 5 l i
Parameter Lower Limit Upper Limit W/C Ratio 0.45 0.64 Sludge Wash TDS 19 wt% 33 wt% S0 level none 11.5 wt% of dry salts 1 sludge Wash pH 12.0 none W/C and TDS are actually limited according to the following relationships: Wt% TDS W/C 19 to 21 0.58 to 0.64 25 to 27 0.51 to 0.59 29 to 30 0.48 to 0.58 31 0.48 to 0.56 32 0.46 to 0.55 33 0.45 to 0.55 The TDS ranges below 29 wt percent are proposed so that process parameters can be gradually changed from those used in earlier production runs with Portland Type I cement, lower TDS sludge wash solutions, and higher W/C ratios. The intent is to monitor processability and production characteristics carefully as the changes are made. (17) The discussion on p. 16 describes the effects of variations in cement and other additives. The "need to broaden the water-to-cement ratios slightly" is mentioned as being necessary to increase gel times. Short gel times result in buildup of solidified wastes in the cement mixer. What data from the qualification test program show that W/C affects gel time? What is the minimurti cube gel time required for successful operation of the Cement Solidification System? (18) What evidence is there that the Portland V waste forms made with sludge wash solutions containirg less than 26 wt percent TDS will meet the stability requirements in the same way as the solutions with higher TDS? 7.10.2 Verification and Surveillance Specimens j The verification specimens for the WVDP cement process consist of 2-inch cubes that are prepared and tested for compressive strength after 24 hours and before a production run is made. This section describes tests on a series of cubes conducted to establish lower compressive strength limits for verification specimens made during full-scale waste form production. Gel times, free liquid, slurry density, and compressive strengths are recorded for four wt percent TDS nominal values: 20, 26, 30, and 32 in Tables 12, 13, 14, 15, respectively. 6
e .~ (19) Why is slurry density different for apparently identical compositions? (20) Is gel time an important process parameter? If so, why is acceptability of a recipe confirmed with compressive strength as stated on P. 167 (21) The data in Table 12, for 20 wt percent nominal TDS wastes, show that there is a complex relationship between composition, gel time, and compressive strength. The general trend seems to be that shorter gel time and higher strength correlate with lower W/C. If shorter gel time is to be avoided, then why include in the average value for the nominal 20 wt percent TDS compressive strength values for samples which have short gel times? For example, 7 samples had gel times greater than 1 min. The average compressive strength of these 7 samples is 609 psi and the standard deviation is 96 psi. Thus, the minimum process centrol compressive strength should be 417 psi. (22) The last paragraph (pg. 21) states that long-term testing of the 30 to 32 wt percent TDS waste forms will be conducted; the plan for this test program will be prepared at a later date. What date? Why is the long-term program restricted to this reduced composition range? The long-term testing program will have to be described and reviewed prior to NRC approval of the process. PROCESS CONTROL PLAN (PCP) The PCP describes the Cement Solidification System (CSS) and the procedures followed during waste form production that are intended to verify and maintain waste form acceptability. Section 3.1.3 Chemical Additive systems (Product Requirement) This section notes that "only the sodium silicate addition is varied depending on the particular sludge wash waste batch being processed...." (23) How is the amount of sodium silicate determined? Section 3.4 Drum Fill (Product Requirement) (24) How many drums were inspected for each process Tank SD-15A1 or 50-15A2 during supernatant operations and during sludge-wash operations to-date? Section 3.7 CSS Data Acquisition System (DAS) Paragraph 5 on p. 14 states that sodium silicate is measured out by weight, and that approximately 8 liters are required per batch. 7
6 (25) What is the density of the sodium silicate solution? Is the quantity of water in the solution included in determining W/C for the waste form? (26) How does the sodium silicate affect gel time? In other words, does increasing the silicate increase gel time? Section 4.0 Requirements for Sample Verification (27) What is the " correlation per ACH-2401" that is used to measure total dissolved solid content? Section 4.3 Cube Acceptance Criteria One of the acceptance criteria is that gelatior time not exceed 90 minutes. (28) How is gelation defined and determined? (29) Is there a minimum time for gelation, which, if exceeded, could cause waste to solidify in the CSS mixer? Section 5.0 Sample Verification Procedure Section 5.3 references 1986 measurements for obtaining isotope ratios for I-129, Ni-59, Ni-63, Cm-242, and C-14. (30) What evidence is there to show that these ratios have not changed significantly as a result of supernatant removal and sludge washing procedures? (31) Is the cube mold (Section 5.6) for curing in the oven a sealed container? The shift Engineer completes Attachment f (Figure 7, Section 5.9.3) to determine " preliminary waste classification." l (32) Figure 7 (p. 29) indicates that "there are no maximum values for Cesium and Strontium." 10 CFR 61.56 has Class C limits for both cesium and strontium. While it is unlikely that the sludge wash solution will approach these limits, it is incorrect to state that there are no maximum values. "The gel time of the first full-scale drum... will be verified by visual inspection." (Section 5.10) (33) What characteristics are observable visually that can verify gel time? References 1. W. J. Dalton, " Waste Form Qualification Report: WVDP Stabilized Sludge Wash Cement-Waste with Type V Portland Cement," WVNS-TR-70-023, Rev. No. 1, 8/13/93. 2. M. N. Baker, " Process Control Plan for Cement Solidification of Decontaminated Sludge Wash Liquid Using Portland Type V Cement," WVNS-PCP-004, Rev. No. 2, 8/9/93. 8 a ..}}