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5S C.J. Wool) (I) -The removal of formate at the conclusion of the decontamination process requires additional anion-exchange resins. (2) The addition of NaOH to neutralize the excess formic acid to adjust for proper pH prior to the decontamination requires additional cation-exchange resins to remove the Na- at the conclusion of the decontamination. The vanadous supplier was able to reduce the formate to vanadous ratio from 8:1 to as low as 2.5:1 by adding a suspension of strong base anion resin beads to the vanadous formate solution (II). By reducing the amount of formate in the LOMI solution, it was possible to reduce the volume of Ion-exchange resins by one half. Laboratory tests established that the decontamination performance and thermal stability were unchanged from the original LOMI formulation. In fact, long term storage tests indicated that the low- formate reagent had storage properties at least as good as the original high-formate formulation (49). 6.4 Introduction of an improved anion resin Further improvement of the LOMI process was realized when a new, weak base anion exchange resin was used in field applications, loner A-365 has a capacity of 2.5 mlllIequlvalents per milliliter of volume, which is a factor of 2.5 times the capacity of the previous anion resin beads. The combination of reduced formic acid and use of loner A-365 in the LOMI process, resulted in waste volumes comparable to those produced by CAN-DECON and CITROX processes (ii). A comparison of resulting waste volumes in recent decontamination projects Is shown in the table below. Table 5. Resin requirements at recent BWR RWR decontaminations Plant Vermont Dresden Brunswick Quad Cities Peach Bottom Yankee Unit 3 Unit 2 Unit 1 Unit 3 Decontamination Dilute LOMI Dilute LOMI** LOMI Process CITROX CITROX NP NP Utilized HYDROLASE LOMI LOMI Cubic Feet *** Resin 192 163 225 168 240 Generated Overall System DF 8.0 12.4 12.5 8.1 15.2 Total Decontamination ii* 9 19 8 **** Time (Days) *Includes 6 days for hydrolaslng **RRS Discharge had a three-step process while Suction and RWCU experienced on a one-step LOMI ***Quantity includes both RRS and RWCU decontaminations .... Due to plant delays total length of time not relevant. From initial chemical injection to final cleanup required approximately 3.5 days Data taken from Reference (IO). 6.5 Future potential Improvements in waste volume reduction Laboratory and pilot tests indicate additional potential improvements that may in time be adopted to reduce waste volumes arising from dilute chemical decontaminations. Possibilities include:
Chemical decontamination technology 59 Ca) Spent resin destruction using wet oxidation techniques (50). (b) (c) Substitution of potassium permanganate oxidation processes by the use of ozone to produce gaseous decomposition products (I_!I). Use of strong acid, hydrogen form cation exchange resins to lower pH and to effectively replace the addition of HNO 3 during permanganate destruction and thus reduce waste volumes (I!I). 6.6 Disposal of solidified wastes The spent resin must be solidified for disposal according to NRC Regulations 10CRF61, and the U.S. NRC Branches Technical Position (BTP) on Waste Form (1983), which establishes the procedures, criteria and terms upon which NRC issues licenses for handling radioactive wastes destined for landfill burial. The form to be buried must possess structural stability such as to satisfy the 300-year criteria required by Part 61. For resins, the most commonly used form of solidification is mixing and setting into a homogeneous cement monolith (51,52). To obtain process approval for a given waste stream, the solidified mixture must be subjected to a series of "stability" tests, producing data to be included tn a topical report for review and approval by NRC 46-48). Additional special criteria have been imposed by the burial sites and these will be discussed in subsequent paragraphs of this report 446-48). 6.7 Stablllt~ tests Stability of waste forms must be established by means of a formal process control program (PCP) which must include the following components: Compressive strength 450 psi) Biodegradatlon resistance Resistance to leaching in specified solutions 490 days) Demlnerallzed and sea water immersion for 90 days followed by a compressive test (50 psi) Resistance to thermal degradation in structure Integrity after exposure to gamma radiation (10E8 fads) Contains less than 0. SZ (volume) of free standing liquid. The results from the stability tests must be provided in a topical report, and waste stream stability test results must specify the content of chelating agents. 6.8 Requirements of disposal sites Because of differences in hydrological conditions, the licensed disposal sites have placed specific requirements for waste burial. In addition to the chelate concentration limitation mentioned above, wastes buried at Baruwell must be separated from other class B and C wastes by I0 feet, and an extra charge is assessed (4_~8). Although there is no upper limit to chelate concentrations for disposal at the Hartford, Washington disposal site, there is a segregation requirement for wastes that contain chelates exceeding 0. I percent by weight. A 10-foot soll separation is required, either by separating trenches or segregation within a given trench, usually resulting in doubling the burial volume when compared to waste containing less than 0.1Z by weight. The Hanford/Richland burial site considers "chelated" waste only when the chelate exceeds 0.1Z by weight, before pretreatment. Segregation is required if the chelate concentration exceeds 0.1% after treatment. Each waste stream must be certified as to its compliance to 10CFR61 stability tests, but different plants can utilize the same PCP (vendor qualified) and be certified for disposal. A new certification is required when the formulation of the decontamination reagent changes significantly. Shipment of solidified liners is performed according to U.S. Department of Transportation regulations that stipulate container radiation limits and the use of strong, tight containers. Upon arrival at the burial sites, inspection techniques consist of drilling the cemented liner at random locations, with at least one of the core samples taken from the bottom perimeter of the cylindrlcal containers. The acceptance criteria are that no free standing lfquld is found and homogeneity of core samples is apparent upon visual inspection. Drilled holes are then plugged and liners are buried in appropriate trenches. Liners that fall to pass inspection are returned to the originating site for repackaging, along with an imposition of a fine to be paid by the shipper according to regulations.
Page 1 and 2: Prt~res.~ io .'~uclear Energy. Vol.
Page 3 and 4: Chemical decontamination technology
Page 5 and 6: ,4. O~¢I~NTAMiNATION Oi I Mfql SYS
Page 7 and 8: Chemical de¢ontaminamm technology
Page 17 and 18: 1.000E-06 1.000E-O7 1.000E-08 Chemi
Page 19 and 20: Types of corrosion testing of decon
Page 23: Chcmic~tl dccontuminution tcchnolo~
Page 29 and 30: Chemical dccontamim~tion technology
Page 35 and 36: Chcmic~l decontamination technology
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Page 39 and 40: ul n- < .,J .J O iA. O 01 z o ..J ,
Page 41 and 42: 50- 40. 30, 20 ¸ 10 ¸ Chemical de

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