ML20196E134

Cement Solidification of Decontaminated Supernatant Waste for West Valley Project, Technical Evaluation Rept

ML20196E134
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Issue date:	11/29/1988
From:	NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS)
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ML20196E067	List: ML20196E061 ML20196E134
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REF-PROJ-M-32 NUDOCS 8812090277
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n. ,_ ._____ ______ _

>s TECHNICAL EVALUATION BY THE OFFICE OF NUCLEAR MATERIAL SAFETY AND SAFEGUARDS

SUBJECT:

CEMENT SOLIDIFICATION OF DECONTAMINATED SUPERNATANT WASTE FOR WEST VALLEY PROJECT Originating Organization: 'J. S. Department of Energy Reviewed by: Technical Branch (LLTB)

Division of low-Level Waste Management and Decommissioning (LLWM)

1.0 INTRODUCTION

The purpose of this Technical Evaluation Report (TER) is to summarize the efforts of the U. S. Department of Energy (00E) in attempting to demonstrate that the cement solidification of the waste generated during supernatant processing at the West Valley site will meet the long-term (300 yea.rs) structural stability provisions of 10 CFR Part 61.56 and the relevant portions of the May 1983 NRC staff Technical Position on Waste Form (Ref. 1). NRC's role, as provided for in the September 1982 Memoranda of Understanding between NRC and 00E, is to review and provide consultation to 00E on any potential radiological danger to the public health and safaty which may be presented by the West Valley Demonstration Project.

The hWC and its contractors, Brockhaven National Laboratory (BNL) and the National Institute of Standards and Technology (NIST), have reviewed several docu*ents describing the cement solidification of various waste streams resulting from the treatment of high-level waste at the West as12090277 001129 PHUd pDR Djp

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, Valleyprojectsite. The wasto streams considered for cement solidification at West Valley included spent ion-exchange resins, sludges, used filter media and the decontaminated supernatant waste. In March of 1988, at a meeting in NRC's Rockville office, DOE informed the NRC for the first time of its plans to focus its attention on solidification of the decontaminated supernatant. This TER therefore, addresses only the solidification of the decontaminated supernatant. Input into this TER was provided in part by the evaluation memorandum originated by Brookhaven National Laboratory (Ref. 2).

The supernatant is a waste product from the spent fuel reprocessing plant attheWestValleyprojectsite. The supernatant is decontaminated by an

' ion-exchange process using zeolite to remove most of the dissolved cesium from the liquid waste. Themajorityofthereprocessingliquidwaste, approximately 600,000 gallons, is contained in Tank 802 and consists of water and dissolved solids, predominantly sodium nitrate and sodium nitrito. Tank 802 also contains a hard bottom sludge layer, about

21-inches in depth, th d is high-level waste. Removal, treatment, and ,

I processing of the bottom sludge layer into borosilicate glass is not anticipated to begin until 1992 following completion of the solidification of the decontaminated supernatant waste. The supernatant is chilled from

) 180*F to 62 F and diluted prior to passing it through the zeolite beds in the Supernatant Treatment System (STS). After the process of dilution and

decontamination, the supernatant is sent to the Liquid Waste Treatment System (LWTS) where it is concentrated to 39 weight percent (wt%) in an evaporator. The 39 wt% decontaminated supernatant is then sent to the Cement Solidification System (CSS) to be mixed with Portlano Type I cement and selected additives in a high shear mixer. The resulting waste cement '

, mixture is then pumped into square carbon steel 71 gallon drums that are transferred into a shielded truck for transportation and eventual storage in the constructed drum cell facility. The number of drums of solidified waste to be produced is not expected to exceed 15,000 drums. The ultimate ,

permanent disposal of the solidified decontaminated supernatant waste is to be decided following completion of the Environmental Impact Statement (EIS) by DOE for the West Valley Demonstration Project.

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JK/ TECHNICAL EVALUAT.NMSS o 2. 0 6ACKGROUND The NRC staff has been involved for several years with technical considerations related to the waste cement solidification efforts at West Vali.j. Appendix A of this TER has been developed to summarize and j provide relevant details of NRC's efforts in this area.

3.0 SVlHARY OF PERTINENT DOCUMENT SUBMITTALS -

The documents that are briefly summarized in this section of the TER are limited to considerations with cement solidification of the 39 wt% l supernatant waste. Many other reports dealing with the full range of I

' waste cement solidification considerations at West Valley have been reviewed by the NRC and its consultants over the past several years. A l more complete list of such reports is orovided in Table 2 of Reference 2. I However, those reports are not covered here, either because their contents are not directly applicable to the NRC's staff and consultant's evaluation on the acceptability of the cement solidified 39 wt% supernatant waste, or because the other reports have been superseded by information and data that are provided in the pertinent documents that are addressed in this TER.

l 3.1 Topical Report on Waste Form Qualification The Topical Report Draf t, July 1988. (Ref. 3) by C. W. McVay, et al, is a summary of the work performed by DOE and its consultant, WVNS, to develop a cement-based low-level waste formulation suitable for solidification of the decontaminated supernatant. This Topical Report describes in

( detail the development of the cement waste formulation that began with the I use of only Portland Type I cement, up to the final formulation which uses special additives with Type I cement to eliminate problems that were shown to develop because of the effects of certain chemicals in the supernatant waste and bet.ause of differences in lab-scale and production-scale equipment.

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. The Topical Report briefly describes the processing systems and equipment that were developed by 00E at West Valley to treat and solidify both the high-level and low-level radioactive wastes. A summary is provided in the report that describes DOE's extensive efforts to characterize both the chemical and radiochemical composition of the supernatant waste that is contained in Tank 802. The report discusses the results and experiences derived from the early formulations and DOE's decision to limit cement solidification of waste to the 39 wt% total solids content supernatant.

The remedial steps taken by 00E are described in addressing the considerations and problems in going from lab-scale testing to full-scale testing in the CSS. The results of the supplementary qualification testing are provided and include compressive strength, leach resistance,

' thermal cycling, immersion and full-scale compression strength testing.

Additional testing to evaluate the effects of curing conditions on compressive strength were also performed and are provided in the Topical Report. The. results and discussions in the Topical Report are intended to demonstrate that the ceaent solidification of the deconta.ninated supernatant waste meets the applicable waste form stability requirements and criteria of 10 CFR Part 61 including the provisions given in the May 1983 TP(Ref. 1).

3.2 Process Control Plan The Process Control Plan (PCP) provided by 00E (Ref. 4) describes the equipment, functions and subsystems of the CSS. This document covers the sampling procedures to be followed for radiochemical analysis and verification of the composition of the supernatant waste to ensure satisfactory solidification even before the waste is transferred from the LWTS to the Waste Dispensing Vessel. The PCP describes the computer programs that have been developed to automatically control the amount and the order of addition of the decontaminated supernatant waste and mixture additives, and the mix time and the data checking activities that are intended to ensure that each batch will be mixed within acceptable proportion limits as established by the qualified formulation parameters.

Process controls on the solidified final product are also described and include visual inspection of the waste drums and the monitoring of the

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percent filling. In addition, monitoring for the presence of any free liquid and the correlation of penetration resistance with a minimum compressive strength are described in the PCP for weekly auditing of production operations. An attachment to the PCP expands on the procedures, equipment and controls that are necessary to properly operate the CSS and includes guidance on preventive maintenance (e.g. flushing of high shear mixer to prevent excessive cement build-up) and a Flow Diagram for the CSS. The information and data provided in the PCP and attachment are intended to show that the provisions in the TP relative to the PCP have been met and that there is reasonable assurance that the solidification process at West Valley will consistently produce an acceptable product for disposal.

3.3 Short-Term Testing DOE has proposed a short-term testing program for the solidified full-scale cement waste forms (Ref. 5). The purpose of the short-term testing program is to parmit correlation of the characteristics of the actual full-scale solidified product in the CSS with those f rom small, simulated laboratory-scale specimens that were tested in the supplementary qualification testing program. This correlation between small-scale and full-scale specimens is recommended in the TP, The testing to be performed in the short-term program includes compressive strength, leach resistance, and radionuclide homogeneity (which would be assessed by the measurement of Cs-137 concentration). Following leach testing, the compressive strength of each test specimen will be measured as agreed to at the September 20, 1988 meeting (Ref. 6). One drum, to be taken from storage after an approxim:tely 30-day cure period in the drum cell, will be selected for testing. Cores will be drilled at six locations for the full length of the solidified waste product in the drum.

Core specimens will be tested from three different levels in the drum.

JK/ TECHNICAL EVALVAT.NHSS 3.4 Long-Term Testing In an effort to demonstrate the homogeneity and long-term stability of the final full-scale solidified product, DOE has proposed (Ref. 7) a long-term confirmatory (5 year) testing program. The program proposed by DOE conservatively goes beyond the provisions of the TP for demonstrating long-term stability of the waste form.

The inspection and testing to be performed in this program includes (1) visual inspection for signs of cracking or spalling of the  !

solidified product, (2) the photographing of specimens, and '

(3) compression strength tests. Twenty drums will be set aside from an actual production run. One drum will be opened, cored and

' specimens taken for inspection and compressive strength testing after an initial cure period of 6 months. Core specimens will be tested from three different levels in the drum. This same inspection and testing procedure will be repeated at six month intervals for a new drum that is taken from the original 20 selected drums. The ten drums that would not be coened during the five year program would be stored in the drum cell atd would be available for confirmatory testing, if needed. The drums that will be cored will be placed into J

an overpack drum and also placed back into the drum cell for storage.

i j 4.0 TE;HNICAL EVALUATION I The NRC's staff technical evaluation separately addresses the information and data provided by DOE in the four previously identified pertinent r I

documents. The determination of the acceptability of the submitted j j information is based upon a comparison with the applicable regulatory i requirements of 10 CFR Part 61 and the guidance in the TP related to structural stability of the waste form. (

4.1 Topical Report on Waste Form Qualification i

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4.1.1 Characterization of Waste Composition I Description of the chemical composition of the decontaminated supernatant

) waste that was used in qualification testing is provided in the Draft I ,

JK/ TECHNICAL EVALVAT.NMSS Topical Report (Ref. 3). More detailed discussions on DOE's consultants efforts to characterize the waste are reported in other documents that are referenced in the Draft Topical Report. The testing to date on the chemical and radiochemical constituents of the decontaminated supernatant waste show it to be relatively homcgeneous. The staff considers DOE's efforts to characterize the supernatant waste to be excellent and finds the information and data to be acceptable.

l 4.1.2 Stability Requirements The waste form is required under 10 CFR 61.56(b) to exhibit structural stability under exp'.ced disposal conditions. This requires the waste form to maintain its physical dimensions and form after disposal.

, Guidance is provided in the TP for performing qualification testing that would demonstrate structural stability of the waste form. The testing covered in the TP includes compressive strength, maintaining stability after being exposed in a radiation field, resistance to biodegradation, resistance to leeching, maintaining strength after immersion, resistance to thermal degradation, measurement of free liquid on the surface of the solidified waste volume, correlation of the characteristics of full-scale solidified products with simulated laboratory-scale specimens and the testing of full-scale specimens. The results of DOE's qualification testing are subsequently discussed and evaluated in this section of the  !

TER with the exception of the correlation between full-scale and lab-scale i testing and the testing of full-scale specimens. The latter aspects of j qua'lification testing are described in the later sections related to short and long-term testing.

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) 4.1.2.1 Compression Strength  !

i  !

The results of compressive strength testing of waste specimens solidified  !

using the modified formulation have been provided in the Draft Topical

Report (Ref. 3) and are summarized in BNL's evaluation report (Ref.2), f After a 40 day curing period the test specimens were shown to have l compressive strengths greater than 750 psi and ranging up to 1220

] psi. These result'. are highly favorable and fulfill the TP i

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JK/ TECHNICAL EVALVAT.NMSS recommendation that maximum practical compressive strengths be achieved, not simply the minimum acceptable compressive strength of 60 psic At the September 20, 1988 meeting with 00E (Ref. 6), the staff and its consultants sought and received a commitment from 00E to establish specific limits on compressive strength that would be used in process control to assure that the effort to achieve the maximum practical strength were maintained during the remaining full production operations. The staff and its consultant expect to review the results of DOE's statisticc', analysis and the specific limits on compressive strength that are established. The follow-up actions by DOE on these limits are further discussed in the conclusion section of this TER.

4.1.2.2 Irradiation and Biodegradation Testing for compressive strength of specimens that were solidified using the original formulation was performed by DOE after exposure of the specimens to a radiation field. The solidified simulated supernatant waste forms were irradiated to 100 Mrads prior to compression testing. The results of irradiation testing on specimens solidified with the original formulation demonstrated compliance with the applicable TP criteria, as the resulting compression strengths

! averaged 660 psi after radiation exposure. The procedures for biodegradation testing that were performed followed ASTM G-21 and ASTM G-22 standards. A departure from the TP guidance was conservatively

] made when the sample tested for biodegradation consisted of slices taken from 2-inch cube samples to optimize the surface area of the biodegradation test speciment. The slices were not then suitable for compres: ion strength testing as suggested by the TP. In April 1988, DOE presented several reasons why, in the opinion of their consultants, repetitive testing for irradiation and biodegradation were not necessary when the change was made to the modified formulation. Based on DOE's request and on the experience of the NRC staff and its consultants that indicated cement-based waste forms were not seriously impaired when exposed to irradiation and biodegradation, the NRC accepted the deletion of these tests for the modified formulation. The NRC staff concludes that 1

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. the results using the original formulation are sufficient to demonstrate acceptable performance of the waste form in resisting the effects of irradiation and biodegradation.

4.1.2.3 Leach Testina For leach testing, cylindrical 1-inch diameter by 3-inch high test samples were prepared using the modified formulation arid actual decontaminated waste. The samples were cured for 28 days. As specified inANS16.1,thespecimensweresubjectedto90daysofleaching. Leach indices for Cs-137, Sr-90, Tc-99 and total plutonium (Pu-238, 239 and 240) were measured. The average leach index for each isotope exceeded TP

' requirements, with the lowest leach index of 7.1 being reported for Cs-137. In comparison to results using the original formulation, the resistance to leaching was observed to increase for the isotopes when samples using the modified solidification forr.ulation were tasted for leaching. Based on the test results, the NRC staff concludes that there  !

is an acceptable level of resistance to leaching for waste that is solidified using the modified formt.lation.

4.1.2.4 Immersionlestino Immersion tests were performed on 2-inch cubes that were prepared using the modified formulation ar:d actual decontaminated supernatant waste. The cubes had been cured at room temperature for a 28 day period prior te immersion. Following immersion in deionized water for 90 days, compression strength tests wera performed. The compression strengths ranged from approximately 630 psi to 750 psi.

A series of tests evaluating the effects of varying ano.ints of water immersion and ambient cure times on compression strength were performed. Six experimental variations of air cure tiet with time of i innersion in deionized water were established with the total time of the six variations held constant at 91 days. Sets of three cylinders  ;

(3 inch diameter by 6-inch high), cored from full-scale production i drums, were tested for compression strength after air curing and i

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. water immersion. The results reflect relatively uniform high

, compression strength values with the average strength ranging from 930 psi to 1070 psi. No surface cracking or deterioration was observed after detailed visual examination of each core prior to compression testing.

Based on the favorable results from the immersion testing, the NRC staff concludes the decontaminated supernatant waste solidified with the modified formulation is stable after immersion and exceeds the TP requirements.

l 4.1.2.5 Thermal Cycling l Thermal cycle testing was performed on 2.75-inch diameter i cyclindrical cores taken from full-scale drums produced in the CSS using the modified formulation and the simulated 39 wt%

l decontaminated supernatant. Before thermal cycle testing, the core samples had been air cured for 40 days. The samples tested for thermaldegradationweresubjectedtothirtycyclesbetween temperature extremes ranging from 60'C to -40'C. Following thermal cycle testing, the core samples were tested for compression strength.

The average compressive strength of the six cores tested was 977 psi.

Onecorefromthesamefull-scaledrumproductthatwasnotsubjected to thermal cycling was also tested for compressive strength and indicated a strength of 1100 psi. Based on the test results, the NRC I

staff concludes that TP requirements for demonttrating resistance to thermal degradation have been exceeded for the supernatant waste that is soIidifiedwiththemodifiedformulation.

4.1.2.6 Free Liquid Since changing to the modified formulation and the elimination of the problem with retarding the setting of the waste cement mixture, the presence of free liquids in the solidified waste has not been detected.

DOE in the PCP has established requirements to check for the presence of free liquids on the surface, both in the verificatien 'J forts of the sample acceptance criteria and in the full-scale solidification testing procedures. To verify that the drums of the solidified supernatant waste

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meet minimum TP requirements, the PCP requires the setting aside of one ,

waste drum per week of production. After approximately two days of j

curing, the drum is tilted 100 degrees from the vertical, allowed to stand i for 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, and then inspected for free liquid. The NRC staff concludes  !

that the measures proposed by DOE in the PCP are reasonable and will f

previde assurance that 10 CFR Part 61 and TP requirements for limiting the amount of free liquids will be met. f l

4.2 Process Control Plan The contents of the PCP developed by DOE and its consultant have l previously been described in Section 3.2 of this TER. During the

[

' course of NRC's review of DOE's efforts to solidify the supernatant I waste, the NRC staff and its consultants made several suggestions to clarify and improve the PCP. ThemajorareasofthePCPaddressedby I NRCcommentscovered(1)theprocesscontrolsincheckingforchanges i in the chemical composition of the supernatant waste and measures to  !

be taken in response to observed changes, (2) the representativeness f or statistical reliability of the originally proposed sample verificationprocedure,and(3)theestablishmentofspecificprocess  ;

control lir.its below which actions would be taken to establish the  !

cause for any significant drop from the qualification test results provideo in the Topical Report. In response to NRC's comments, 00E exhibited a willingness to seriously consider and responsibly respond f to the concerns that had been expressed. As a result, it is the  !

conclusion of the NRC staff that the final West Valley PCP for the supernatant cement solidification is acceptable. The staff also concludes l

that the PCP provides a good example for other waste solidification l vendors to emulate because it fulfills the intent of the TP, that of l assuring the process will consistently produce a stable waste form prcduct that is acceptable for disposal. ,

l 4.3 Short-Term Testina l f

L The short-term testing program proposed by DOE to meet the TP l

reconsendation for addressing differences between laboratory-scale i I1 i l t

JK/ TECHNICAL EVALUAT.NMSS and full-scale production has previously been described in

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Section 3.3 of this TER. In some respects, DOE has already initiated i testing to address this concern by having tested core samples that were drilled from full CSS production drums in its qualification testing program. The staff expects to review the results of the DOE proposed short-term test program and anticipates the results will provide additional assurance of the capability of the modified formulation to produce stable waste cement produ:ts. -

4.4 Long-Term Testing CortainfeaturesoftheWestValleyprojectareuniquebecausethey

' offer opportunities to observe the stability performance of the cement solidified waste form for relatively long periods before the solidified waste is placed in its permanent disposal location. The staff considers the DOE proposed long-term confirmatory testing pregram that is described in Section 3.4 of this TER to be important and an exceptional opportunity to confirm and gain confidence in the long-term stability behavior of the solidified waste. At the September 20, 1988 l meeting (Ref. 6) 00E indicated that it was its intention to keep the NRC fully informed of the results from the proposed long-term confirmatory (

testing F ogram as the results become available. t

5.0 CONCLUSION

Based on the staff's review of (1) the qualification test results provided  !

in the Draft Topical Report, (2) the Process Control Plan provisions, and l (3) the short and long-term testing programs that are intended to confirm and provide additional assurance on waste form stability, the NRC staff concludes that there is reasonable assurance that the cement solidification of the 39 wt% decontaminated supernatant waste will meet the waste form stability requirnents of 10 CFR Part 61 and fulfills the provisions of NRC's Technical Position on Waste form. This conclusion on reasonable assurance is predicated in part on the expectation that there will be acceptable test results from the short-term and long-term confirmatory testing programs described in this TER. These tests are expected to i

JK/ TECHNICAL EVALVAT.NMSS continue to confirm favorable compression strengths and stability performance of the cement solidified supernatant waste. The NRC staff endorses DOE's plans for proceeding with full production operations to solidify the re.saining 39 wt% decontaminated waste on the expectation that DOE will provide (1) agreed-torevisionstotheattachaentsof Reference 8,(2)specificacceptablelimitstobeusedinprocess control, based upon statistical analysis of available testing data (as 00E committed to provide at the September 20, 1988 meeting),and(3) written acknowledgement as previously requested in Reference 9 th t proceeding with full-scale production will not foreclose the undertaking and the completion of practicable alternative methods of waste disposal.

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. REFERENCES

1. U.S. Nuclear Regulatory Comission, Technical Position on Waste Form, May 1983.

2. Brookhaven National Laboratory, B. S. Bowerman and B. Siskind

Subject:

StaffEvaluationMemorandumontheSolidificationofDecontaminatedTank 802SupernatantatWestValleyDemonstrationProject, November 1988.

3. Draft WestValleyNuclearServicesCo.lification,CementWasteFormInc.

Topical Report on Waste Form Qua , C.' W. Mc Qualification Report; - WDP PUREX Decontaminated Supernatant, July 1988.

4. ---

M. N. Baker et al,

Subject:

West Valley Demonstration Project Draft Process Control Plan for Decontaminated Supernatant Cement

, Solidification,Rev.No.1, August 1988.

5. -- , WNS Short Term Testing of Cement Waste Form, Oraft D, Aug. 15, 1988.  ;

6. U. S. Nuclear Regulatory Commission, J. D. Kane memorandum to J. J. Surmeier (NRC),

Subject:

DOE-NRC Meeting on September 20, 1988, at the West Valley site, September 29, 1988, t

7.  ;

WestValleyNuclearServicesCo.58.Inc.,

Waste Form, Oraft 0, Aug. 15, 19 WNS Long Term Testing of Cement

8. Department of Energy, E. Haestas note to M. Tokar (NRC),

Subject:

L Low-level' Cement Waste Form Produced at the WDP, August 19, 1988. -

9. U. S. Nuclear Regulatory Commission, M. R. Knapp letter to W. W. Bixby .

(DOE), June 16, 1988. l l

l l

l l

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APPENDIX A i BACKGROUND AND HISTORY OF NRC REVIEW CEMENT SOLIDIFICATION OF DECONTAMINATED SUPERNATANT WASTE I FOR WEST VALLEY DEMONSTRATION PROJECT l

BACKGROUND AND HISTORY 1

In January 1988, (Ref. 1) NRC notified DOE of staff technical concerns related to the characteristics of cement waste forms being proposed by DOE. The con-cerns resulted from the review of documents identified in Reference 2 and included the following needs: (1) the developroent of supporting test data for I the 'upernatant s waste stream containing 42 wt% solids; (2) the clear identi-fication of all of the waste streams by DOE that would require stabilization, and the submittal of appropriate leach test data; (3) the verification in the

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process control program that free standing liquid would not be present in the i final produced waste drums; (4) the determination of the potential long-term  !

effects of high waste loadings in causing tracking and spalling of the cemented waste products; (5) the submittal of process control plans for NRC review for all the waste streams intended to be processed through the CSS; and (6) the identification of the quality control provisions that would assure a proper waste classification assessment. In a follow-up letter of March 17, 1988 I (Ref. 3), the NRC provided additional comments and questions upon further review of the waste streams proposed to be processed in the CSS. The addi-tional review comments and questions were related to NRC concerns for the ,

following: (1) the level of radionuclide concentrations for the uranyl nitrate  !

waste stream in the CSS product; (2)thelong-tersstorageandcuringcon-(

ditions to be experienced by the CSS product; and (3) the test results  !

intenced to demonstrate compliance with the NRC Technical Position on Waste Form (TP) (Ref. 4) for waste streams that included the decontaminated supernatant, uranyl nitrate and Tank 802 sludge washes.

l On March 24, 1988, a meeting (Ref. 5) was held between the DOE and the NRC in l Rockville, Maryland. At this meeting DOE provided an overview of the waste l cement solidification efforts at West Valley and indicated it was DOE's inten-l tion to now concentrate on the cement solidification of the 39 wt% decontaminated supernatant waste. DOE's consultant, West Valley Nuclear Services Co., Inc.,

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s.

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. A-2 (WVNS),describedrecentprojectdevelopmentsthatresultedinadoptionofa modified formulation for the 39 wt% decontaminated supernatant. The enhanced recipe included several new additives (calcium nitrate, antifoam agent and sodium silicate) that were shown to be necessary to address foaming and low compressive strengths that developed during full-scale testing of the simulated 39 wt% supernatant and to address the slow setting and bleed water problems that resulted when the actual decontaminated supernatant waste was used in lab-scale solidification efforts. It was DOE's position at the March 24, 1988 meeting, based on limited test results which indicated that a better solidified waste product would result with the modified formulation, that the qualification testing recommended by the TP (Ref. 4) would not be necessary for the modified formulation. This position was founded on the fact that the difference in the waste cement mixtures, on a chemical element basis, was less than 1.3 percent.

At the March 24 meeting, the NRC staff and its consultants agreed to consider DOE's request for reduced qualification testing on the modified formulation but expressed reservations on the basis of the information that had been presented at the meeting. 00E also requested the NRC staff to provide comments on a draft of ths. Process Control Plan (PCP)(Ref. 6) for the solidification of the 39 wt% decontaminated supernatar t waste that was provided by DOE at the meeting and on a long-term testing program that had previously been proposed to the NRC.

NRC responded to DOE's request for review comments in an April 13, 1988 letter (Ref. 7). Because the performance sensitivity of certain test results provided by 00E showed significant changes in the behavior of the solidified waste with extremely small changes in proportions of the constituents of the mixture, NRC recommended that additional (supplemental) qualification testing be performed by 00E. The supplemental testing was directed at providing reasonable assurance that t.he cement waste form product resulting from the new formulation would possess long-term (300 years) structural stability as required by Part 61 for Class B and C low-level radioactive wastes. NRC also notified 00E in the April 13, 1988 letter that staff review comments on the draft PCP would be forwarded to 00E by late April, prior to an anticipated visit of WV0P facilities by the NRC staff and consultants in May.

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A-3 i

l Following the March 24, 1988 meeting, but prior to receipt of NRC's April 13, 1

1988 letter, DOE had reconsidered the scope of its qualification testing program in <esponse'to the reservations expressed by the NRC. Supplemental qualifica-tion testing was proposed by DOE to demonstrate that the moriified formulation l

would acceptably perform and meet TP requirements. The testing program proposed by DOE included the following tests: (1)aseriesofcompressivestrength tests on core samples after immersion in demineralized water for varying cure l times with the cores to be obtained from drums produced in full-scale operations l using simulated waste; (2) compressive strength tests on 2-inch cubas and 3-inch diameter by 6-inch high core samples from a full-scale production run using simulated waste after 7 and 40 day cure periods; (3) thermal cycle I

testing with cylindrical core samples produced during full-scale operations using simulated waste; and (4) leach resistance tests on 1-inch diameter by 3-inch high samples using actual supernatant waste that had been decontaminated in a small zeolita bed. Based on previous favorable test results with products from the original formulation and the exoerience and knowledge of DOE's con-sultants in the fi lde of organic chemistry, DOE proposed that testing for biodegradation and irradiation not be repeated for solidified products using the new modified formulation. DOE's proposal for additional qualification testing was ultimately discussed with the NRC staff and its consultants at the May 3 and 4, 1988 meeting at West Valley.

On May 3 and 4, 1988 the NRC staff and its consultants visited the West Valley projectsitetomeetwith00Eanditsconsultantsandtowitnessalaboratory demonstration of the modified formulation using simulated waste and to tour the l treatment facilities (Ref. 8). On April 29, 1988, the NRC staff had fo marded f

a draft copy of comments and questions developed by the staff and its consultants on the previously furnished draft PCP. The draft comments and questions were to serve as a basis for meeting discussions in addressing and resolving NRC's review concerns on the PCP. The major categories covered by the NRC coments included questions on (1) tM characterization of the supernatant waste, (2) the modified formulation, (3) the documentation of test data, (4)the correlation of laboratory and field testing, (5) the composition and charac-terization of the solidified product, and (6) acceptance criteria and action levels. The extensive list of draft comments and questions provided by the

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NRC prior to the meeting were widely discussed. The discussions allowed clarification of many review items and permitted the staff to describe the specific information and data that would typically be needed in a regulatory review to be able to reach a conclusion on the acceptability of a solidified waste product. .

The meeting summary (Ref. 8) describes the agreements, conclusions and the

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commitments reached at the May meeting. These were is follows: (1) the i conclusion of the NRC staff and its consultants that (a) the revised supple- ,

mental qualification testing proposed by DOE on the modified formulation was appropriate and (b) the results of testing required by the TP that were available at the meeting were satisfactory and were reflecting increases in comp'ressive strengths over the results from the original formulation; (2)a comitment by DOE to provide a description of DOE's plan to develop a Topical Report on the final waste cement formulation that would present all of the test [

results from the on going supplementary qualification testing program and also include the information previously furnished to the NRC as Attachment A to the t PCP; '3) commitments from DOE to check for organics in the supernatant waste  ;

constituents by testing, if changes in the process chemistry and radiochemistry l were observed, and to revise and resubmit the provisions of the long-term test plan for the 39 wt% supernatant based on meeting discussions; and (4)a proposal from DOE suggesting a three-stage approach to final waste qualifica-  ;

tion that included hot checkout testing (i.e., limited p oduction-scale opera- '

tions as stage one); completion of the ramaining qualification testing followed by full-scale solidification operations (as stage 2) and then addressing and  !

resolving all remaining disposal issues (as stage 3), j 1

NRC for.aally transmitted its review commants and questions on the draft PCP to j DOE in a May 13, 1988 letter (Ref. 9). This letter also enclosed two additional comments of the staff related to verification of the supernatant's composition .

that were developed upon further consideration of the May 3 - 4, 1988 meeting [

discussions. DOE provided written responses to NRC's comments and questions  !

that had been discussed at the May 3 - 4, 1988 meeting in a submittal dated May 16, 1988 (Ref. 10). DOE's May 16 submittal also included an interim report of L j the up-to-date results of the supplementary qualification testing program and i further clarification of the previously proposed three-step approach to final i

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• A-5 waste qualification. DOE also provided notice to the NRC of its intention to begin limited production-scale operation nn June 1, 1988 using actual decon-taminated supernatant waste to demonstrate the suitability of the final l

solidified product. '

NRC responded to DOE's May 16 submittal on June 16, 1988 (Ref. 11) and con-cluded, based on the information and data provided, that there was a good i technical basis for proceeding with limited production-scale operations as proposed by 00E. NRC also indicated in the June 16 letter that DOE should t complete certain actions before proceeding with full production operations. i Those actions wsre as follows:. (1) the successful completion of a!1 remaining supplemental qualification testing; (2) a revision of the PCP that would satisfactorily address and resolve past coments by the NRC staff and its consultants; (3) the testing of the full-scale solidified waste form that would provide additional assurance of adequate homogeneity and compressive strength in the final waste product; and (4) attainment of an agreement in principle i between DOE and NRC on a suitable long-term (5 year) confirmatory test program for the solidified supernatant waste. The long-term confirmatory test program I

description would need to cover the specific curing conditions to be imposed, the procedures for evaluating the compressive strength results over time, allowing for normal variations in test results, and the identification of criteria for determining when surface degradation (spalling and cracking) would I be excessive and unacceptable. NRC also recommended that DOE provide written statements on DOE positions that had been verbally stated in the past relative to acknowledgement that proceeding with full scale operations would not l foreclose the undertaking and completion of practicable alternative methods of (

disposal along with a description of the viable alternatives (such as the f

overpacking of the cement solidified wastes in high-integrity containers). [

In a letter dated August 5, 1988 (Ref. 12), NRC followed up on its June 16, l 1988 letter (Ref. 11) and forwarded to DOE the staff and consultant's review [

l coments on DOE's responses to previous NRC review comments (Ref.10). The NRC I comments provided in the attachments to the August 5, 1988 letter did not raise  !

new review issues, but rather focused in on responses by DOE where there  !

appeared to be technical differences of opinion or where the DOE responses were I not considered sufficiently complete to alleviate the review concerns. The l 1 i

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majorareasofconcernincluded(1)theadequacyoftheprocesscontrolmea-  ;

i sures to be imposed in responding to potential changes in the chemical  !

composition'of the supernatant waste and (2) the adequacy of process controls {

l in checking on the homogeneity and quality of the solidified product. To best '

address and expedite the resolution of the unresolved issues, NRC suggested an additional meeting to be held in its Rockville office. At DOE's request the  !

l meeting was arranged to be held at the West Valley site because of the advantages l

) in visually observing operational features that are under discussion. The i meeting was scheduled for September 20, 1988. I i

On September 13, 1988 the NRC staff appeared before the Advisory Committee on I 1

Nuclear Waste (ACNW) to provide an update on the status of cement waste form '

j solidification. At that meeting the low-level waste (LLW) activities at West l

Valley were described to the ACNW including the modifications in the waste  !

]' cement formulation that were necessary to address (1) the unanticipated prob-lems with foaming, (2) low compressive strengths and (3) slow setting which  ;

was caused by a very small proportion of organics in the supernatant waste stream.

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1 The staff also briefed the ACNW on the remaining NRC review items that j i needed to be resolved. ACNW expressed keen interest in the lessons that were  !

learned to reach development of the final formulation and expressed appreciation j to the staff for the technical presentation, i l Prior to the September 20, 1988 meeting at the West Valley site between 00E and

the NRC, DOE had prepared draft responses to address and resolve NRC's review l

j comments contained in the attachment to the August 5, 1988 letter (Ref. 12). l

] DOE'sdraftresponses(Ref.13)servedasthemajoritemsofdiscussionatthe I

) September 20 meeting. Additional enclosures that were provided by 00E in f 1

Reference 13 included (1) a draft copy of the new Topical Report on Waste Form  !

Qualification with the final results of the qualification testing program, (2) a revised PCP, (3) a revised CSS Run Plan and (4) the provisions proposed

] by DOE for short and long term testing of the cement waste form, i

i Following the September 20 meeting a summary was prepared by the NRC staff in a memorandum dated September 29, 1988 (Ref. 14) and included a listing of the l I agreements that were reached at the meeting. Themajoragreementitemsthat i were reached between the NRC and the 00E included (1) a commitment by DOE to ,

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JK/ TECHNICAL EVALUAT.NMSS A-7 l

revise the five attachments of Reference 13 to reflect the results of the l l September 20 meeting discussions, (2) a commitment by DOE to complete a

statistical analysis and evaluation of the available testing data for com-(

! pressive strengths on the two-inch cube specimens and to establish specific

) limits based on the available test results that DOE will recommend be used in I

process control during full-scale production operations, (3) a commitment by DOE to perform compressive strength testing on the leach test specimens ,

identified in the short-term testing program, and (4) NRC's acceptance of the f j provisions for the short and long-term testing programs as proposed by DOE.  ;

t The NRC indicated in Reference 'i4 that with the fulfillment of the above i

,! commitments by DOE on the above items and the favorable evaluation of that  !

information by the NRC, the staff would be prepared to endorse DOE's plans for !

l proceeding with full production operations to solidify the remaining

' l decontaminated supernatant waste.

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REFERENCES l

1. U. S. Nuclear Regulatory Comission, M. R. Knapp letter to W. W. Bixby, (DOE),-January 22, 1988.

f

2. Brookhaven National Laboratory, B. S. Bowerman and B. Siskind

Subject:

StaffEvaluationMemorandumontheSolidificationofDecontamInstedTank 802 Supernatant at West Valley Demonstration Project, Novetaber 1988.

3. U. S. Nuclear Regulatory Comission, M. R. Knapp letter to W. M. Bixby  !

(DOE), March 17, 1988. .

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4. -- , Technical Position on Waste Form, May 1983.

5. -- , D. A. Widmayer memorandum to J. J. Surmeier(NRC'- S DOE-NRC  !

MeetingonWestValleySolidifiedWaste, March 25,IN.ubject:

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6. .Oraft Process Control Plan for Oecontaminated Supernatant Cement Solidification,WestValleyDemonstrationProject, April 1988.

7. U. S. Nuclear Regulatory Comission, M. R. Knapp letter to W. W. Bixby, (00E), April 13, 1988. {

8. -- , J. D. Kane memorandum to J. J. Surmeier (NRC), Sub'e DOE-NRC i Meu.ing on May 3-4, 1988 attheWestValleysite,Mayll,ct: 1988. l

9. -- , R. L. Rangart letter to W. W. Bixby (00E), May 13, 1988. f

10. W. W. Bixby letter to M. R. Knap Department of Enerbleation SupplementaryQual Testing of WV0P Low-Level ha(NRC)

Subject:

ste Formulation, May 16, 1988.

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11. U. S. Nuclear Regulatory Comission, M. R. Knapp letter to W. W. Bixby I (DOE), June 16, 1988.

12. -- , M. R. Knapp letter to W. W. Bixby (00E) August 5, 1988, f

13. Department of Energy E. Maestas note to M. Tokar (NRC),

Subject:

l Low-Level Cement Waste Form Produced at the WVDP, August 19, 1988. J l

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14. U. S. Nuclear Regulatory Comission, J. D. Kane memorandue to J. J.

Surmeier(NRC),

Subject:

DOE-NRC Meeting on September 20, 1988, at the l West Valley site, September 29, 1988.

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