Low Cross-linked Resin Reduces Iron, Maintains Low Reactor Water Sulfate

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1 Case History Low Cross-linked Resin Reduces Iron, Maintains Low Reactor Water Sulfate Site Information Location New York, USA Purpose Reduce feed water iron from 2-3 ppb without increased sulfate concentration levels Comparative Performance Final feed water iron 1. ±.5 ppb Reactor water sulfate concentration 2 ppb Constellation Energy s Nine Mile Point LLC Unit Two turned to DOWEX* GUARDIAN* CR-1 cation exchange resin to reduce reactor water iron levels while maintaining safe levels of sulfate. (Photo courtesy of Constellation Energy) In the nuclear power industry, finding an ion exchange system that provides just the right feed water and reactor water chemistry can be a delicate balancing act. Plant engineers at Constellation Energy s Nine Mile Point LLC Unit Two found that DOWEX GUARDIAN CR-1 cation exchange resin reduced feed water iron levels by more than 95% while maintaining safe reactor water sulfate levels. Page 1 of 5 * Trademark of The Dow Chemical Company Form No

2 Introduction Constellation Energy s Nine Mile Point LLC Unit Two is located in central New York. The power plant employs a boiling water reactor (BWR) with deep-bed condensate polishers to help control primary cycle chemistry. Engineers at the plant were looking for water-treatment alternatives that would enable the plant to meet stringent industry guidelines for feed water iron. At the same time, the station was experiencing a period of increased condenser iron loading due to the loss of moisture separator/reheaters (MSRs) at the end of one of its operating cycles. Although reducing feed water iron was of prime importance, Constellation Energy did not want to risk increased sulfate levels in the reactor water coolant. After researching the data from a previous project evaluating low-cross-linked resin, senior plant engineer Mark Becker conducted laboratory evaluations of DOWEX GUARDIAN CR-1 cation exchange resin for reducing feed water iron while maintaining acceptable reactor water sulfate levels. Based on the results of these evaluations, the Nine Mile plant chose the new Dow resin to help meet the iron guidelines. Background Excessive feed water iron can cause two major problems for a nuclear power plant: Heat transfer reduction Iron buildup on the cladding of the nuclear fuel reduces heat-transfer efficiency and can lead to nuclear fuel cladding failures. Shutdown dose rates High feed water iron levels affect the transport of activated corrosion products, increasing radiation dose rate on the reactor piping and increasing worker exposure. When cation resins used for iron removal degrade by thermal or mechanical means, sulfate levels typically increase in the reactor water coolant. This increased sulfate can accelerate corrosion in nuclear fuel rods and other internal components, which can greatly reduce power generation economics. To meet guidelines set by the Institute of Nuclear Power Operations (INPO) and the Electric Power Research Institute (EPRI), the Nine Mile plant needed to reduce feed water iron from 2-3 ppb with MSRs in service, or 5 ppb with MSRs out of service, to 1 ±.5 ppb. DOWEX GUARDIAN CR-1 Resin DOWEX GUARDIAN CR-1 resin is a unique, low-cross-linked cation exchange resin that Provides enhanced particulate iron removal versus conventional cation resins Maintains a minimal release rate of organic sulfonates due to unique manufacturing technology Consists of uniform size beads with smaller average diameter and lower true hydrated density to minimize the separation of the cation/anion resin during transfer back to the service vessel Improves influent copper removal versus conventional cation resin Dow researchers developed DOWEX GUARDIAN CR-1 resin specifically for the nuclear power industry using proprietary new technology for stabilizing low-cross-linked resin. Page 2 of 5 * Trademark of The Dow Chemical Company Form No

3 Plant Laboratory Tests To qualify the DOWEX GUARDIAN CR-1 resin, Becker devised a series of laboratory tests to assess the risk of sulfate leakage in the presence and absence of iron and copper impurities. He also assessed the impact on the kinetic properties of the anion resin. DOWEX HGR-W2 cation resin was used as the control system in these laboratory tests. Encouraged by the laboratory results and the evaluation of previous testing of low-cross-linked resin, the Nine Mile plant then proceeded to a full-scale plant trial. Plant Trial In January 1998, the plant converted one of its 1 conventional deep-bed condensate polishing resin beds (DOWEX HGR-W2/DOWEX SBR-C resin) to GUARDIAN CR-1 resin, rounding out the mixed-bed system with DOWEX MONOSPHERE* 55A anion exchange resin. In July 1998, a second resin bed was converted to the DOWEX GUARDIAN CR-1/ DOWEX MONOSPHERE 55A mixture. The chemistry department at Nine Mile sampled and analyzed the condensate demineralizer influent (CDI), polisher bed effluent, and final feed water streams. The reactor water coolant was also monitored for sulfate levels. The plant completed six 3- to 4-day service cycles (January 1998 to April 1999) with the beds containing low-cross-linked resin, comparing their results to the performance of the control resin bed. Plant Performance During the first two service cycles (with MSRs out of service), effluent iron averaged about 4 ppb (an 85% removal rate) from the beds containing DOWEX GUARDIAN CR-1 resin versus about 8 ppb (a 6% removal rate) from the control bed. After the moisture separator reheaters were returned to service (cycles 3 6), the effluent iron averaged about 1 ppb (a 97% removal rate) from the beds containing DOWEX GUARDIAN CR-1 resin versus about 4.5 ppb (an 8% removal rate) from the control bed. The plant's full-scale trial confirmed that DOWEX GUARDIAN CR-1 resin provided improved iron removal without increasing reactor water sulfates, even through the hot summer months (the average was about 1.5 ppb). In addition, after ultrasonic cleaning, sulfate spikes were not observed after the cleaned beds containing DOWEX GUARDIAN CR-1 resin were placed back into service (Figures 1 and 2). Figure 1. Effluent iron comparison. 18 Iron Concentration (ppb) GUARDIAN Resin (Charge #9) DOWEX HGR-W2 Control Resin Bed GUARDIAN Resin (Charge #3) 2 2/9/99 12/21/98 11/1/98 9/12/98 7/24/98 6/4/98 4/15/98 2/24/98 1/5/98 5/2/99 3/31/99 Page 3 of 5 * Trademark of The Dow Chemical Company Form No

4 Figure 2. Reactor water sulfate profile. Sulfate Concentration (ppb) Arrows indicate when DOWEX GUARDIAN resin beds were placed back into service after backwashing. Reactor Water Sulfate % Reactor Power Hotwell Temperature ( C) Reactor Power/Hotwell Temperature 1/28/98 3/28/98 5/28/98 7/28/98 9/28/98 11/28/98 1/28/99 3/28/99 Based on the favorable iron and sulfate results, the Nine Mile plant converted two more condensate polishing beds to the DOWEX GUARDIAN CR-1/ MONOSPHERE 55A resin mixture during the remainder of fuel cycle 7, leaving the other five beds operating with the conventional DOWEX HGR-W2 cation resin. This allowed the plant to further reduce its iron level to about 1. ppb - well within industry guidelines - and still maintain plant economics (1). To finalize the optimization, the two original beds containing low-cross-linked resin were replaced (after about 13, h of service) with new charges of DOWEX GUARDIAN CR- 1/MONOSPHERE 55A resin, plus an additional bed was converted during a spring 2 refuel outage. The Nine Mile plant also reduced its total number of resin beds from 1 to 9 to provide each bed with its own dedicated service vessel to prevent cross-contamination. Becker reports that the early results (after about 3 days) of fuel cycle 8 with five low-crosslinked resin and four conventional beds were exceptional, with an integrated weekly iron average of.6 ppb and sulfate concentration less than 1.5 ppb. Nine Mile Point LLC Unit Two is committed to continue using and analyzing GUARDIAN CR-1 resin for iron removal, reactor water sulfate, anion resin sulfate kinetics, and moisture content, Becker said. Since that time he has presented updated information about the power station s experiences with the DOWEX GUARDIAN CR-1 resin at the June 2 and February 22 EPRI Condensate Polishing Workshops (2,3). Conclusions GUARDIAN CR-1 cation exchange resin has been used in the deep-bed condensate polishers at Constellation Energy Nine Mile Unit II since Since that time, the plant has met their goals for Final feed water iron = 1. ±.5 ppb Reactor water sulfate concentration 2 ppb GUARDIAN CR-1 resin typically provides 9, service-hours without the need for anion resin replacement. The plant continues to use five charges of the combination of GUARDIAN CR-1 and MONOSPHERE 55A. Today, the plant still benefits from optimal feed water iron control while maintaining safe reactor water sulfate levels. Page 4 of 5 * Trademark of The Dow Chemical Company Form No

5 References 1. Becker, Mark W., Requalification of Low Cross-linked Resin for Iron Control, EPRI Workshop, February 23-25, Becker, Mark W., Requalification of Low Cross-linked Resin for Iron Control, EPRI Workshop, June 26-28, Becker, Mark W., Low Cross-linked Resin for Iron Control, EPRI Workshop, February 6-8, 22. For more information about DOWEX resins, call the Dow Liquid Separations business: North America: Latin America: (+55) Europe: (+32) Japan: (+81) Australia: (+61) Notice: Oxidizing agents such as nitric acid attack organic ion exchange resins under certain conditions. This could lead to anything from slight resin degradation to a violent exothermic reaction (explosion). Before using strong oxidizing agents, consult sources knowledgeable in handling such materials. Notice: No freedom from any patent owned by Seller or others is to be inferred. Because use conditions and applicable laws may differ from one location to another and may change with time, Customer is responsible for determining whether products and the information in this document are appropriate for Customer s use and for ensuring that Customer s workplace and disposal practices are in compliance with applicable laws and other governmental enactments. Seller assumes no obligation or liability for the information in this document. NO WARRANTIES ARE GIVEN; ALL IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE ARE EXPRESSLY EXCLUDED. Page 5 of 5 *Trademark of The Dow Chemical Company Form No