ML20214N857
| ML20214N857 | |
| Person / Time | |
|---|---|
| Issue date: | 05/30/1987 |
| From: | NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS) |
| To: | |
| Shared Package | |
| ML20214N848 | List: |
| References | |
| REF-WM-81 NUDOCS 8706030106 | |
| Download: ML20214N857 (27) | |
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I United States Nuclear Regulatory Conslission Office of Nuclear Materials Safety and Safeguards Washington, D.C. 20555
. STAFF EVAltlATION REPORT related to the Topical Report covering the STEEL FIBER POLYMER IMPREGNATED CONCRETE-HIGH INTEGRITY CONTAINER manufactured by Chichibu Cement Co., LTD.
, _ Docket No. WM-81 Prepared by: Engineering Branch Division of Wast.: Manageveent June 1986 Revised: May 1987 8706030106 870520 pop WASTE PDR i
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. A85 TRACT This Staff Evaluation Report has been prepared by the Office of Nuclear Material Safety and Safeguards of the U.S. Nuclear: Regulatory Commission for the Topical Report filed by Chichibu Cement Co. , LTD., covering its Steel Fiber Polymer Impregnated Concrete (SFPIC) High Integrity Container. The container is proposed for use as a means of containing low-level radioactive waste and meeting the' structural stability requirements for waste in 10 CFR Part 61. The staff concludes that the SFPIC high integrity container meets the structural stability requirements of Part 61 and may be used for the disposal of low-level radioactive waste that requires disposal in a stable form. Limiting conditions for use of the container may be specified by the regulati'ng authority for a particular disposal, site.
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k TABLE OF CONTENTS-Pag j '
A8STRACT .............. .................................... 11 2
1.0 BACKGROUND
.................................................. 1 i 1.1 Regulations............................................. 1 1.2 Topical Report Submitta1s............................... 2 1.3 Steel Fiber Reinforced Polymer Impregnated Concrete HIC Description.................
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l- 2.0
SUMMARY
OF TOPICAL REP 0RT................................... 4 1 3.0
SUMMARY
OF REGULATORY EVALUATION............................ 5-1 3.1 Maj o r Areas o f Revi ew. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 1 3.2 Chemical Resistance.................................... 5 l 3.3 Mechanical Analysis.................................... 7 3.4 Gas Generation and Internal Pressurization............. 8
! 3.5 - Prototype Testing...................................... 10 r 1
3.5.1 . Drop Test.................................... 10
- 3.5.2 Type A Package Criteria...................... 11 2
3.6 Radiation Stability.................................... 13 3.7 The rma l S tab i l i ty. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
, 3.8 Quality Assurance and Inspection....................... 16
! 3.9 Free Liquids........................................... 17 3.10 B i odeg rada ti on. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 3.11 O the r Con s i de rat i o n s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 i
!' 3.11.1 Creep........................................ 19 l j 3.11.2 Water Retention.............................. 19 3.11.3 Inspection................................... 20
- 3.11.4 Positive Sea 1................................ 21 l 3.11.5 Miscellaneous Tests........................ . 21
} 4.0 REGULATORY P0SITION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 i
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5.0 REFERENCES
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1.0 BACKGROUND
1.1 Regulations By Federal Register Notice dated December 27, 1982 (47 FR 57446), the United States Nuclear Regulatory Commission (NRC) amended its regulations to provide specific requirements for licensing of facilities for the land disposal of low-level radioactive waste. The majority of these requirements are now contained in Part 61 to Title 10 of the Code of Federal Regulations (10 CFR 61) entitled " Licensing Requirements for Land Disposal of Radioactive Waste" (Ref.
1). Minor modifications, mostly of a procedural nature, have been made to other parts of the Commission's regulations, such as 10 CFR 20 (" Standard for Protection Against Radiation"). These regulations are the culmination of a set of prescribed procedures 'for low-level radioactive waste disposal that were proposed in the Federal Register on July 24, 1981.
The effective date for the implementation of 10 CFR 20.311, which requires waste generators to meet the waste classification and waste form requirements in 10 CFR 61, was December 27, 1983. As set forth in 10 CFR 61.55, Class B and Class C waste must meet structural stability requirements that are established under 10 CFR 61.56(b). In May 1983, the NRC providad additional guidance by means of a Technical Position on Waste Form (Ref. 2) that indicated that structural stability could be provided by processing (i.e., solidification) the waste form itself (as with large activated steel components) or by' emplacing the waste in a container or structure that provides stability (i.e., a high integrity container (HIC)).
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. . 1 WM-81 STAFF EVALUATION RPT
. a 1.2 Topical Report Submittals 8y letter, dated June 29, 1984 (Ref. 3) the Chichibu Cement Co., LTD.,
submitted fifteen copies each of a proprietary and non-proprietary version of a topical report on a Steel Fiber-reinforced, Polymer Impregnated. . Concrete (SFPIC) high integrity container. At the time of submittal, Chichibu stated that the HIC's meet or exceed all disposal conditions of the Nuclear Regulatory Commission, Department of Transportation, and the States of South Carolina and Washington. Shortly after the initial submittal, errata information on both the p'roprietary and non-proprietary version was submitted (Ref. 4), as well as an affidavit for the withholding of proprietary information (Ref. 5).
A preliminary technical review, involving primarily members of (a) the Materials Section of NRC's Waste Management Engineering Branch, Division of Waste Management, (b) the Waste Technology Section of NRC's Waste Management
. Branch, Office of Research, and (c) the Transportation and Certification Branch of NRC's Division of Fuel Cycle and Material Safety, resulted in the generation of numerous comments on the SFPIC HIC topical report. As a result of early discussion of these comments with the vendor, during the summer and fall of 1984, additional submittals containing additional tests results and data were made on December 13, 1984 (Ref. 6) and February 25,1985(Ref.7).
The NRC technical review produced a set of draft comments which were sent to Chichibu on April 23, 1985 (Ref. 8). After receiving input from the States of South Carolina and Washington, a request for additional information (RAI #1)
>w-tT-81 STAFF E'iALUATION RPT on the report was transmitted to Chichibu, through their U.S. agent, the Mitsubishi International Corporation, en October 30,1985(Ref.9). By letter dated, February 25, 1986, Chichibu submitted their responses (Ref. 10) to the HRC's request for additional information. After the subsequent review these responses were found to adequately address the NRC questions. Following final approval of the Topical Report a request was received on April 23,1987(Ref.
- 19) to modify the method of preventing water accumulation of the HIC top. The request was evaluated and approved on May 7, 1987 (Ref. 20).
4 1.3 Steel Fiber Reinforced Polymer Impregnated Concrete HIC Description i
The Chichibu SFPIC high integrity container is a right circular cylinder of concrete fabricated within a carbon steel drum. The two sizes of HIC's described in this topical report have 200 litre (55 gal.), and 400 litre (110 gal.) nominal volumes. The 200 litre has an available internal volume of 143 litres while the 400 litre HIC possesses 285 litres of available voluo. The j 200 litre SFPIC unit is approximately 82 cm high and 57 cm in diameter. The SFPIC side wall, excluding the steel drum, is at least 27 mm thick, while the
- lid and bottom are a minimum of 38 mm thick. For the 400 litre SFPIC unit, the height is approximately 104 cm with a diameter of 71 cm. The wall thickness is increased to 37 mm and the lid and bottom to 45 nm. The SFPIC '
high integrity container is fabricated by casting a mixture of Portland Cement, aggregates, water, mixing agents, and steel fibers into the appropriate steel i drum. Subsequently, an organic monomer is impregnated into the cement and polymerized to eliminate the porosity within the concrete. The lid is fabricated from the same SFPIC material as the rest of the container. The lid is sealed to the drum walls with a layer of epoxy resin.
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WM-81 STAFF EVALUATION RPT The carbon steel drums which facilitate transportation and handling are i -designedtomeettheJapanesestandard-JIS-Z-1600(Ref.10),whichis !
. equivalent to the DOT 17H and 17C steel drums.
1 2.0
SUMMARY
OF TOPICAL REPORT
! The generic topical report on the Chichibu SFPIC high integrity container is !
j intended to demonstrate that the HIC meets.(a) all the applicable stability ,
I requirements and criteria of 10 CFR 61 (using guidance provided in the May 1983 l Technical Position on Waste Fom), (b) 10 CFR 71 sections dealing with Type A 4
Packaging (as the Part 71 requirements apply to HICs), (c) 49 CFR 173 Type A i Packaging related areas, and (d) special testing and design conditions i requested by the Agreement States.
The SFPIC HIC was designed to be certified as a DOT Type A container that would
- pass all U.S. 00T and U.S. NRC transportation requirements for a Type A container. The HIC is intended to contain the following types of wastes from nuclear power plants
- (1)dewateredbead, powdered,andzeoliteionexchange ;
l material;-(2)filtrationmaterialssuchassand,activatedcharcoal,and i diatomaceousearth;(3)compressiblesolidwaste;(4)non-compressiblesolid I waste; (5) filter elements in cartridges; (6) solidified resins and sludges; and 1 (7) solidification media including cement, vinyl ester styrene, and bitumen.
The topical report is divided into five technical sections which address the
! following: an analysis of the structural integrity of the HIC under burial l 2
conditions; fabrication procedures and quality assurance; handling and loading procedures; material characteristics, including chemical, radiation, creep, j impa,ct and blodegradation resistance; and prototype testing.
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WM-81 STAFF EVALUATION RPT 5-3.0
SUMMARY
OF REGULATORY EVALUATION 3.1 Major Areas of Review The basic objective of this staff technical evaluation of the topical report was to confirm that the Chichibu SFPIC HIC meets the structural stability requirements of 10 CFR 61. The NRC's Technical Position on Waste Form (May 1983), which addresses various details including certain transportation and testing requirements that are presented in 10 CFR 71 and 49 CFR 173, provides guidance on how to satisfy Part 61. Major areas of review that are addressed in the Technical Position and which received particular attention in this review, because they were deemed to be the most critical with regard to influencing the structural integrity of the HIC, included the following:
- 1. Chemical Resistance
- 2. Mechanical Analysis
- 3. Gas Generation and Internal Pressurization
- 4. Prototype Testing
- 5. Radiation Stability
- 6. Thermal Stability
- 7. Quality Assurance
- 8. Free Liquids
- 9. Biodegradation
- 10. Remaining Technical Position and Other Considerations 3.2 Chemical Resistance Concrete has been in use for over a century as a structural material and has demonstrated significant durability. However, research on concrete performed in the last fifty years has identified many substances which are incompatible with concreto (Ref. 12). These substances, which are typically man-made, may
attack either the aggregate particles or the binding cement resulting in a deterioration of the concrete's mechanical properties and jeopardizing the overall integrity. In addition, some organic compounds.may have degrading effects on the impregnated polymeric material. Investigations of the environments found in trenches of two pre-Part 61 disposal sites (Ref. 13 and
- 14) indicate the presence of a wide variety of chemical compounds which may degrade either the concrete, the polymer or the epoxy resin employed to seal the HIC's. i The chemical compatibility tests performed by Chichibu consisted of exposures of the SFPIC to extremes in pH, 0.4 to 13.5, produced by dilute solutions of H2504 and NaOH, respectively. Althou0h the material performed adequately in these tests, it is not sufficient proof that the material is immune to degradation by the myriad rJ chemicals that may be found in a burial trench.
Therefore, Chichibu was ask'ed to supply evidence that the materials utilized in their HIC would be resistant to chemical environments which may exist within the HIC as a result of the contained waste or external to the HIC as a result
- of other waste within the burial trench. Chichibu responded by performing a I
series of chemical compatibility tasts utilizing solutions of five additional classes of chemicals which have been identified to exist within power plant waste and eight chemicals which have previously appeared in burial trench environments. The test results indicate that, for all the chemicals tested, essentially no loss of compressive strength occurred during the 1000 hour0.0116 days <br />0.278 hours <br />0.00165 weeks <br />3.805e-4 months <br /> test exposure for oither the SFPIC material, the epoxy or the sintered ceramic which is used as the vent.
The staf f concludes, on the basis of the data presented in the SFPIC Topical Report and responses to staff questions that the materials of the SFPIC HIC can resist degradation from environments found within burial trenches and the l
WM-81 STAFF EVALUATION RPT wastes, if the chemical variability of the waste is maintained within the recommended range of pH of 4 to 11.
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3.3 Hechanical Analysis The maximum burial depth at the Hanford, Washington site was increased from 45 to 55 feet in December 1985, which corresponds to an external pressure of 45.8 psi. The Barnwell, South Carolina site has a maximum depth of 25 feet or 20.8 psi. Although the original structural analysis of the SFPIC HIC was based on the previous Hanford burial depth of 45 feet, Chichibu has shown by revised calculation that the SFPIC HIC can tolerate the increase in pressure and still maintain an adequate margin of safety (Ref.10).
Chichibu has demonstrated the structural stability of the SFPIC HIC both experimentally and analytically. Experimentally, full size HIC's (with the steel drum removed) were tested to failure in a hydrostatic test chamber.
Initial failure, for both size HIC's, occurred in the lid and the failure pressure was between 1.7 to 1.9 times the pressure produced at the maximum burial depth. The bodies of the HIC were also tested to failure by replacing the lid with a steel lid. For the 200 litre HIC, the body withstood a pressure 18% greater than the lid, while 400 litre withstood the maximum pressure that the chamber could generate without failure, i.e., 114 psi.
Analytically, Chichibu calculated the compressive and bending stresses exerted on the 200 and 400 litre HIC's for three different placing configurations (horizontal, vertical and 45') at the maximum burial depth. These stresses were then compared to an experimentally derived " allowable stress value". The allowable stress values for compressive and bending strengths were determined by tabulating the test results from one hundred specimens from more than thirty i
-C-batches of SFPIC concrete. The lower 3 sigma distribution values were determined and designated the " guaranteed strengths", i.e., essentially all (99.8%) of the specimens exhibit strengths greater than this value. The allowable stress values were then determined by taking 60% of the guaranteed strengths, i.e., the allowable stress will be no more than 60% of the failure stress of 99.8% of all specimens tested. In all cases the calculated burial stresses were below the allowable values by at least 17%. Therefore, the calculated burial bending stresses were in no case greater than 50% of the experimentally determined guaranteed strengths. The allowable compressive stresses were many times greater than the calculated stresses.
Based on the data and calculations presented, the staff concludes that there is reasonable assurance that a SFPIC HIC will not suffer loss of integrity over its design life as a result of mechanical failure.
3.4 Gas Generation and Internal Pressurization One of the design changes made to the SFPIC HIC's during the review process involved the incorporation of a passive vent system to allow relief of pressure generated by gases, resulting from possible blodegradation or radiolytic decay.
The concern about internal gas generation originated from experience with a few i
polyethylene containers that exhibited symptoms of excessive gas generation (for example, one had become stuck in its transportation cask due to the swelling resulting from gas generation and internal pressurization). This had resulted in a request by the State of South Carolina Department of Health and Environmental Control for consideration of a passive ventilation system as a design feature that would alleviate the prob 1cm.
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After due deliberation, the NRC Staff concluded that the installation of vents, in all HICs, not just polyethylene ones, would be a prudent way to address the potential symptoms of the problem with gas generation. The State of South Carolina then issued a letter describing the requirement along with design criteria intended to help meet the requirement (Ref. 15). The approach thus provides a means to minimize the effects of gas generation (e.g.,
over pressurization of the HIC) on handling, personnel safety, and long-term inte0rity of the container. The use of vents is intended to be an interim measure, which would address the symptoms and preclude any serious effects of gas generation,' while allowing a long-term solution to be arrived at via a study that would identify the specific cause of the gas generation.
Accordingly, the passive vent system that Chichibu proposes to use in the SFPIC HIC's would consist of a sintered ceramic rod emplaced in the lid of the HIC using the same epoxy used to seal the lid onto the HIC body. The vent will be emplaced in such a manner that it is flush with the surfaces of the lid. The sintered ceramic was chosen based on its chemical stability, radiation resistance, and its ability to permit the passage of gases while minimizing the ingress of water. Samples have been tested for the flow of water and air and have been shown to perform satisfactorily. Other relevant physical properties of the vent material are discussed in the appropriate section within this staff evaluation. The staff concludes that there is reasonable assurance that the passive vent system will provide an adequate means to allow for the release of pressure due to gas generation resulting from or radiolytic decay or biological action.
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WM-81 STAFF EVALUATION RPT 3.5 Prototype Testing 3.5.1 Orop Tests i
The HIC should be capable of meeting the requirements for a Type A package as l specified in 49 CFR 173 and 10 CFR 71, as applicable to concrete containers I (Ref.2). With respect to the drop test requirements, the applicable criteria are prov'ided in 10 CFR 71.71. For the 200 litre SFPIC HIC the maximum gross weight will be under 920 lb, while the 400 litre size will weigh less than 1830 lb. Free drop tests for both size HIC's, loaded to the maximum weight with sand and water, were performed from a height of 4 feet onto an unyielding surface, from five different orientations, viz, flat top, bottom, and side and top and bottom corner. Although cracks were found on some of the HIC's after l
the steel drums were removed, no leakage of water or sand was observed during a 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> monitoring period or during subsequent handling.
Results obtained from the drop tests performed from 25 feet onto compacted sand, as required by the States of Washington and South Carolina, indicated that some hairline cracks were produced, although fewer in number than were
- observed in the Type A drop test. Once again the HIC's could be safely handled and no leakage was observed. However, it is Chichibu's position that in order i to ensure 300 year integrity is provided any SFP!C HIC that experiences a drop, similar to either of these two tests, should be placed, in its entirety, into a larger compatible HtC. In addition, Chichibu performed a series of drop tests in which a dowater9 J device was emplaced into the HIC before it was filled with sand and water. The results obtained were similar to the previous tests.
The staff therefore concludes, on the basis of the information submitted, that for a SFPIC HIC which is subject to an accidental drop, the short-term integrity is maintained so that the HIC can be safely handled and repackaged without any additional exposure.
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l WM-81 STAFF EVALUATION RPT 3.5.2 Type A Package Criteria A high integrity container for low-level radioactive waste should be capable of meeting the " normal conditions of transport" criteria for Type A packages in 49 CFR 173 and 10 CFR 71, as applicable to concrete containers (Ref. 2). Criteria used are those contained in Section 71.71(c), 10 CFR Part 71. Of the Type A package test criteria, the results of drop tests are addressed in Section 3.5.1, above. Other tests, or analyses performed in lieu of tests, are addressed in the following sections.
4 Pressure Testing The conditions for the reduced external pressure and increased external pressure test contained in 10 CFR 71.71(c)(3) and (4) were simulated by Chichibu by increased internal and decreased internal pressure tests, respectively. The criteria for the reduced external pressure test f corresponds to a pressure differential of 11.2 psi. Chichibu simulated this differential by hydraulically increasing the internal pressure until failure. For both the 200 and 400 liter HIC's failure occurred at a pressure differential of greater than 25 psi, which are more than twice the required value.
The criteria for the increased external pressure corresponds to a pressure differential of 5.3 psi, which was simulated by reducing the fitternal pressure with a vacuum pump. Both size SFPCI H1C's withstood full vacuum (pressure differential of 14.7 psi) for the duration of the thirty minute test with no loss of integrity. It should be noted that Chichibu l
subsequently performed a hydrostatic test of full size H!C's in response to questions on mechanical stability. These tests consisted of applying
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WM-81 STAFF EVALUATION RPT external hydrostatic pressure to the HIC until failure. For both the 200 l and 400 litre HIC's the initial failure occurred in the lid at a pressure of approximately twice the maximum burial pressure (see Section 3.3).
Transportation Vibration Test Ira order to demonstrate compliance with the transportation vibration re,quirement,10 CFR 71.71(c)(5), each size HIC was filled with moist sand and, attached to a fork lift truck, in both the vertical and horizontal orientations, and driven over 4 cm square timbers spaced 0.5m apart.
During the test, the HIC's were subjected to accelerations up to 1.5-2.0g.
These tests produced no visible effects on the integrity of either sized HIC. ,
Water Spray Test ,
i Each sized HIC was subjected to a simulated rainfall of 5 cm of water per l hour for one hour, as required by 10 CFR 71.71(c)(6). The water spray test produced no visible ef fects on either sized HIC. ,
Compression Test ,
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Criteria for compression tests are addressed in 10 CFR 71.71(c)(9). The l compressive load to be applied to the HIC's during these tests must be l either the equivalent of five times the weight of the package or 1.85 psi multipliedbytheverticallyprojectedareaofthepackages,whicheveris j greater. However, as discussed in Section 3.3 of this staff evaluation, the SFPIC HIC is designed to withstand burial pressure of at least 45.8 psi (corresponding to the 55 foot burial depth at Hanford). This corre- ,
sponds to a pressure which is more than three times the resultant i
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WM-81 STAFF EVALUATION RPT i t pressures produced by taking five times the gross package weights of 950 and 1875 pounds for the 200 and 400 litre HIC's distributed across the projected area. The staff concludes that since both HIC's were tested in ;
l untaxial compression as well as in hydrostatic compression and withstood ,
pressures in excess of the burial pressure, the intent of the compression test has been satisfied.
Penetration Test The criteria for the penetration test, 10 CFR 71.71(c)(10), requires that I a steel cylinder,1-1/4 inches in diameter and weighing 13 pounds with a i hemispherical head, be dropped from a height of 40 inches onto the exposed
- surface of the package. This test was conducted on fully assembled HIC's l of both sizes on the top, bottom, and side surfaces with no visible j cracking or failure. .
! 3.6 Radiation Stability ;
The radiation stability of the proposed container materials as well as the radiation degradation effects of the wastes, should be considered in the design of the HIC. No significant changes in material design properties should result following exposure to a total accumulated dose of 10 8 rads (Ref.2). :
i i For the SFPIC HIC, the basic materials of construction consist of the steel
} fiber polymer impregnated concrete, the epoxy resin and the sintered ceramic l vent. Specimens of the SFPIC material, manufactured with the same ingredients and under the same conditions as the HIC units, were exposed to integrated gamma doses of up to 1.5 X 810 rads. At the 108rad level the compressive and bending strengths of the SFPIC specimens were reduced by 10 to 20% of the I
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WM-81 STAFF EVALUATION RPT original strengths. Correlating the reduced strength values to the guaranteed strength for the SFPIC still results in a strength value in excess of the maximum calculated burial stress.
The epoxy sealant material was likewise tested to 1.5 x 108 rad. The results of the tests indicate an increase in both compressive and bending strengths of 5% over that of the unirradiated specimens. The greater strengths are the likely, result of an increase in crosslinking within the resin.
The sintered ceramic vent has been exposed up to 108 rads by the manufacturer and no visual changes or changes in the physical properties, e.g., mechanical strength or permeability, have been noted.
An evaluation of the effects of radiolytic gas generation from the SFPIC material was performed in the initial submittal. The res.ults indicate that a 200 litre HIC (assuming a 30% void volume and no outward diffusion of gas) would, after a 300 year exposure of 108 rads undergo an internal pressurization of about 8 psig. This would be the total gas evolution from the SFPIC material, of which less than one-third is hydrogen. This calculation does not, however, include gas generated from the waste material. The recent requirement of vents on all HIC's (Ref. 13) reduces the concern of gas generation, frcm the standpoint of preserving HIC integrity, to ensuring that the internal gas generation rate does not exceed the flow rate of the vent (see Section 3.4). However, if in the future the option of non vented HIC's is again permitted, an examination of the gas evolution from proposed wastes will require further examination for the SFPIC HIC.
m WM-81 STAFF EVALUATION RPT The resistance of SFPIC to ultraviolet (UV) light was also examined experimentally. The SFPIC specimens were exposed to a 3000_ hour cyclic exposure test. The exposure produced a small-decrease in both the compressive.
strength and molecular weight. Although very long term exposure to UV light may produce a significant decrease in strength to bare SFPIC material, the HIC will be protected by the steel drum during transportation and storage and should generally not be exposed to UV light for any significant length of time.
. The staff concludes that there is reasonable assurance the the effects of radiation have been adequately considered in the design of the SFPIC HIC.
3.7 Thermal Stability The proposed container materials should be designed considering the thermal loads from processing, storage, transportation and burial. No significant changes in material properties should result from thermal testing.
Two experimental procedures were performed to verify the stability of the SFPIC material to thermal changes. The first test examined the. thermal cycling resistance of SFPIC specimens in air following essentially the same procedures as described in ASTM B553. Post-test examination revealed no visual changes in the external appearance of the specimens and only an insignificant decrease in compressive strength (less than 2%).
The second, more rigorous, test examined the SFPIC's resistance to freezing and thawing in water. This test compared the resistance of plain concrete, steel fiber reinforced concrete (SFC) and steel fiber polymer impregnated concrete (SFPIC) in a freeze-thaw environment. The specimens were immersed in water a_ _-
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WM-81 STAFF EVALUATION RPT then subjected to a thermal cycling consisting of 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> at -30 C and 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> at 60*C. A total of 230 cycles were performed. The plain concrete disintegrated in 40 cycles. The SFC showed partial surface deterioration at the conclusion of the test while the SFPIC showed no visual surface changes and only a slight decrease in compressive strength (less than 4%).
Of the waste streams proposed for use with the SFPIC HIC, the potential for large tempera,ture increases is greatest for the in situ solidification of bitumen.
Based on information from the bitumen vendors, the maximum temperature of the bitumen as it enters the HIC will be approximately 350*F (177*C). Heat-resistance testing, reported in the topical, was performed on SFPIC specimens by exposing them to temperatures from 122*F (50*C) to 842*F (450*C) followed by compression testing. The results indicated that no change in strength occurred below 392 F (200*C). Therefore, the SFPIC HIC should be capable of receiving bitumenized waste directly from process equipment with no adverse eff.ects on the integrity of the HIC.
Based on the information submitted, the staff concludes that there is reasonable assurance that thermal variations due to processing or the environment have been adequately considered and are not expected to adversely influence the performance of the SFPIC HIC.
3.8 Quality Assurance and Inspection The high integrity containers should be fabricated, tested, inspected, prepared for use, filled, stored, handled, transported, and disposed of in accordance with a quality assurance program. Because the assurance of proper procedures for container fabrication, testing, transportation, storage and use is critical, the NRC Staff questioned Chichibu on this subject (Ref. 8). Chichibu
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, provide'd a detailed response and flowchart describing the quality control of C - the HIC's during fabrication and testing, including requirements for the k
- incoming materials, concrete mix, polymer impregnation, vent performance, leak tightness, mechanical strength, and dimensional checks.
s For those operations that the vendor has no control over; such as waste
, loading, storage, transport, handling and disposal, Chichibu has prepared a Users Manual (Ref. 16) describing procedures and restrictions to be observed c s' The HIC users will have the responsibility of certifying that all required procedures and' restrictions have been. satisfied. The staff concludes that ;
there is reasonable assurance that quality assurance requirements have been adequately addressed for the SFPIC HIC.
3.9 Free Liquids The maximum allowable free liquid in a high integrity container should be less '
a than one percent of the waste volume. Furthermore, a process control program should be developed and qualified to ensure that the free liquid requirements of 10 CFR Part 61 will be met upon delivery of the wet solid material to the disposal facility considering effects of transportation.
Since some of the waste types proposed for use with the SFPIC HIC may exceed the free liquid requirements when loaded into the HIC, e.g., ion exchange resins, Chichibu developed a dewatering system and process control program by which to satisfy the free liquid requirement. The dewatering device was designed to be chemically compatible with the HIC and not.to adversely affect aspects of the HIC performance (see Section 3.5.1). A process control procedure was developed and demonstrated, experimentally, which satisfactorily
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4 showed that-less than one percen't of free standing liquid would remain, even
!. considering the vibratcry loads of transportation. The staff. concludes that I there is reasonable assurance that the free liquid requirement can be: met and
.that no adverse consequences should arise through the-use of the internal
! dewatering device.
-3.10 Biodegradation The high integrity container design'should consider the biodegradation
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, properties of the proposed materials, wastes and disposal media-(Ref. 2). The l SFPIC material was tested in accordance with the two recommended ASTM tests, j i.e., ASTM G21 a'nd G22.~ During the post-test examination, the specimens'were -
! rated zero for.both fungi and bacteria. Furthermore, no decrease in compressive strength was found. Therefore the SFPIC was' judged to be resistant to l' ' biological attack. .Likewise, the epoxy was tested in accordance with the-ASTM tests and no growth of either type was observed. The staff concludes that-
- reasonable assurance has been provided that no adverse effects on the performance of.the HIC's will result due to biodegradation.
3.11 Other Considerations t
The-preceding' sections of this Staff Evaluation Report address the technical areas that received the most attention during the course of the review of the ;
SFPIC HIC topical report. These items received the most attention'because they
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I W -81 STAFF EVALUATION RPT 3.11.1 Creep Design mechanical strengths for polymeric material should be conservatively extrapolated from creep test data (Ref. 2). Although the SFPIC HIC contains up to 5% polymer, the structural support is provided by the concrete matrix.
Nevertheless, Chichibu examined the long-term deformation behavior of the SFPIC material by performing a constant load creep test. The equivalent pressure applied to the test specimens was two orders of magnitude greater than the pressure at the maximum burial depth. The results of the test indicated that.
only a slight creep deformation and residual strain were produced, although both were less than the corresponding effect produced on plain concrete.
Therefore, the staff concludes that the SFPIC will undergo no significant changes as a result of material creep.
3.11.2 Water Retention The high integrity conta'ner should be designed to avoid the collection or retention of water on its top surfaces in order to minimize accumulation of trench liquids that could result in corrosive or degrading effects (Ref.2).
Although this aspect was initially not addressed (Ref. 3), an approach-(Ref.
- 10) was provided which prevented liquid accumulation by filling the steel drum lid with mortar. Subsequently it was requested (Ref.19) that drainage holes be provided in the wall of the steel drum at the level of the SFPIC lid as an improvement and substitute to the mortar filling operation. The NRC staff concludes that the use of drainage holes reduce ALARA considerations compared to the mortar filling while maintaining the integrity of the SFPIC HIC and that the procedure adequately considers the prevention of top surface water retention.
. ,- r WM-81 STAFF EVALUATION RPT 3.11.3 Inspection The HIC closure should be designed to allow inspections of the contents to be conducted without damaging the integrity of the container (Ref. 2). This aspect was not considered in the initial submittal (Ref. 3) but as a result of frequent, early communications, this issue was resolved early in the review period (Ref. 7).
The nature of the SFPIC HIC closure does not provide a ready means by which to perform an inspection. However, a procedure has been developed which would enable the inspection of waste contents to be performed and the HIC to be resealed in such a manner as to preserve the integrity of the HIC for disposal purposes. The detailed procedure can be found in the Chichibu Users Manual (Ref. 16). Briefly, to inspect the contents of a SFPIC HIC, a core is drilled through the SFPIC lid. This inspection hole permits visual inspection or access to obtain a waste sample. After the inspection is complete a second SFPIC lid is sealed in place over the original lid, now containing the inspection hole.
As a result of performing an inspection and resealing the HIC with a second SFPIC lid, the steel lid from the outer drum can no longer be used, due to lack of adequate clearance at the top of the drum. However, since an inspection would typically occur' at the disposal site after the steel drum has performed its purpose of facilitating handling, transportation and any extended storage period, the replacement of the steel lid is not considered a necessity.
Furthermore, no credit is taken for the steel drums in any burial analyses.
The staff concludes that inspection of the HIC contents and re-closure can be accomplished without jeopardizing the long-term integrity or performance of the HIC.
i WM-81 STAFF EVALUATION RPT 3.11.4 Positive Seal The high integrity container closure should be designed to provide a positive seal for the design lifetime of the container.
Two tests were performed which demonstrate the ability of the closure to maintain a positive seal. The leak tightness test (see Pressure Testing, Section 3.5.2) was described earlier in this report. The second test examined the adhesive strength of the SFPIC lid seal. This test consisted of placing.a hydraulic jack inside a sealed HIC in such a configuration that the jack was
, imparting on upward force on the circumferential area of the underside of the lid, i.e, the force was concentrated near the epoxy seal. The load necessary to fail the seal was 10 times greater than the maximum waste load produced within a filled HIC. The staff concludes that reasonable assurance has been demonstrated that a positive seal will be maintained for'the life of the SFPIC HIC.
3.11.5 Miscellaneous Tests Fatique Test In order to determine the fatigue behavior of SFPIC and to compare it to that of plain concrete, a series of fatigue tests were performed by varying the maximum stress level. The tests indicated that almost no increase in residual strain and elastic strain was observed until failure, nor was there a decrease in elastic modulus. The fatigue strength for SFPIC equaled or exceeded that of plain concrete.
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WM-81 STAFF EVALUATION RPT Impact Test Data was presented comparing the impact resistance and toughness of SFPIC, SFC and plain concrete. The data was referenced from journal articles (Ref.17 and 18) in which the amount of steel fibers in the reinforced concrete was varied. The data on the test composition, which most closely approximated the Chichibu formulation, indicated that SFPIC possesses an impact resistance (obtained from Charpy tests) an order of magnitude greater than that of plain concrete. In terms of the relative toughness between plain concrete and SFPIC, the SFPIC exhibited a toughness value, that was 70 times greater. Toughness is defined as the ability of a material to absorb energy and deform before fracturing and can be measured by the area under the stress-strain curve. Therafore, the impact resistance and material toughness for SFPIC is significantly greater than it is for plain concrete.
Fire Test The SFPIC HIC was subjected to a fire test as described in 10 CFR 71.73(c)(3), i.e., hypothetical accident conditions. After the test the HIC maintained its integrity and its ability to be handled. Further examination consisted of removing the steel drum and inspecting the SFPIC surface. The HIC was essentially unchanged, although, some cracks were observed on the bottom of the HIC.
4.0 REGULATORY POSITION NRC Staff has completed its review of the topical report that is' intended to serve as the referential document that describes the design of the Chichibu .'
SFPIC high integrity container (HIC) for low-level radioactive waste and provides the basis for determining the adequacy of the HIC design. In its I
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evaluation, staff primarily focussed on (1) applicable sections of 10 CFR 61, 10 CFR 71, and 49 CFR 173 and (2) additional requirements proposed by state agencies. Based on the evaluation of the information provided in (a) the topical report (original submittal plus revisions), (b) written responses by Chihcibu to NRC Staff questions and comments, and (c) meetings and telephone discussions with Chichibu representatives and consultants, the staff concludes that there is reasonable assurance that, considering the proposed use of the Chibcibu SFPIC HIC, the HIC meets the structural stability requirements of Part 61 and is consistent with the guidance presented in the NRC Staff Technical Position on Waste Form.
This approval of the SFPIC HIC and topical report is predicated on completion and issuance of the final topical report (proprietary and non-proprietary versi'ans) according to review agreements and the followin,g conditions:
(1) That the SFPIC HIC shall be used in accordance with the Chichibu Use Manual, dated June 1986.
(?) The SFPIC HIC shall be used in accordance with all restrictions and requirements specified by the burial site operators and governing state agencies.
(3) Users of the SFPIC HIC shall certify that all restrictions and required procedures have been adhered to.
(4) Users of the SFPIC HIC shall certify that the HIC's are used only for nuclear power plant, a) dewatered bead, powdered and zeolite ion exchange material, b) filtration media including sand, activated charcoal and diatomaceous earth, c) compressible solid wastes, d) non-compressible solid wastes, e) filter cartridges, f) cement ano vinyl ester styrene solidified resins and sludges, and g) bitumen solidified wastes and that the HICs do not contain proscribed chemicals ur waste materials.
' - WM-81 STAFF EVALUATION RPT
5.0 REFERENCES
- 1. 10 CFR 61, Licensing Requirements for Land Disposal of Radioactive Waste, U.S. Government Printing Office, January 1,1985.
- 2. Technical Position on Waste Form, Rev. O, U.S. Nuclear Regulatory Commission, May 1983.
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- 3. Kanjiro Ishizaki (Chichibu), letter to Leo B. Higginbotham (NRC), June 29, 1984.
- 4. Osamu Suzuki (Chichibu), letter to Leo B. Higginbotham (NRC), July 12, 1984.
, 5. Osamu Suzuki (Chichibu), letter to Leo B. Higginbotham (NRC),
Subject:
Affidavit of Osamu Suzuki Concerning the Withholding of Proprietary Information in the _Chichibu Cement Co. , LTD. Topical Report on High i Integrity Containers, September 19, 1984.
- 6. Gordon Epstein (Mitsubishi International Corp./Chichibu), letter to Leo B. Higginbotham (NRC), December 13, 1984.
- 7. Gordon Epstein'(Mitsubishi/Chichibu), letter to Leo B. Higginbotham (NRC), February 25, 1985.
- 8. Thomas L. Jungling (NRC), letter to Gordon Epstein (Mitsubishi), Draft
. Comments on Chichibu's SFPIC High Integrity Container, April 23, 1985.
- 9. Thomas L. Jungling (NRC), letter to Gordon Epstein (Mitsubishi/Chichibu),
Subject:
Request for Further Information on Chichibu's SFPIC High i Integrity Container, October 30, 1985.
- 10. Gordon Epstein (Mitsubishi) for Kanjiro Ishizaki (Chichibu), letter to Leo B. Higginbotham (NRC), Proprietary and Non-Proprietary Responses to NRC Comments of 10/30/85, February 25, 1986.
- 11. Japanese Industrial Standard (JIS) - Z - 1600, Full Removable Head Steel Drums (2001), Japanese Standards Association, 1977.
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EM-81 STAFF EVALUATIO!! PPT
- 12. American Concrete Institute Committee 515, "A Guide to the Use of Waterproofing, Damproofing, Protective and Decorative Barrier-Systems for Concrete," No. ACI 515.IR-79, American Concrete Institute, 1979.
- 13. Veiss, A.J. and P. Colombo, " Evaluation.of Isotope Migration - Land Burial: Water' at Commerically Operated Low'-Level Radioactive Waste Disposal Sites," Brookhaven National Laboratory, NUREG/CR-1289, March' 1980.
la. General Research Corporation, " Study of Chemical Toxicity of low-level Wastes," NUREG/CR-1793, Volume 1, November 1980.
- 15. Heyward G. Shealy (South Carolina), letter to'Leslie Poppe (Chem-Nuclear Systems, Inc.), " Requirements for Passive Ventilatio.n," June 20, 1985.
- 16. Chicibu Cement Co., LTD., High Integrity Container Use Manual, June 1986.
- 17. Ohgishi, S., The Cement Concrete, No. 355, September 1976.
- 18. Araki, et al., The Journal of Materials Science, Vol. 25, No. 273,1976.
- 19. Osamu Suzuki (Chichibu), letter to Malcoln R. Knapp (NRC), April 23, 1987.
- 20. Michael Tokar (NRC), letter to Osamu Suzuki (Chichibu), May 7, 1987.
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