ML19262A084

Trojan Cooling Tower Plume Study Summary Topical Report

ML19262A084
Person / Time
Site:	Trojan File:Portland General Electric icon.png
Issue date:	10/23/1979
From:	PORTLAND GENERAL ELECTRIC CO.
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ML19262A083	List: ML19262A082 ML19262A084
References
NUDOCS 7910260316
Download: ML19262A084 (9)

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{{#Wiki_filter:. TROJAN COOLING TOWER PLUME STUDY

SUMMARY

TOPICAL REPORT I. BACKGROUND The Trojan Cooling Tower Plume Study was conducted in accordance with Section 4.3.1 of Appendix B of the Environmental Technical Specifications for the Trojan Nuclear Power Plant.1 The technical specifications require a topical summary report on the program to be submitted two years af ter the initiation of full power operation. This report is submitted in fulfillment of that requirement. This study was initiated in response to concern over possible adverse impacts of the cooling tower plume on the surrounding area. The purpose was to semiquantitatively determine characteristics of the plume. Of particular interest were plume length, vertical thickness, density, and ground impingement. The effect on surface visibility adjacent to the plant on U.S. Highway 30, downwind of the plant and in relation to the major industrial sites in the Kelso-Longview area, was to be determined. In addition, the behavior of the plume under various seasonal conditions was to be examined. Time-lapse photography was used to monitor plume behavior. Photographs were taken at five-to six-rd nute intervals on Kodachroce Super-8 film using Nizo S-8 movie cameras equipped with wide-angle lenses. A small LED date/ time readout was placed in each camera's field of view to pro-vide a timing record. These cameras were located at two different sites in Washington (see Attachment A). One camera was located at the City of Kalama water treatment plant. This camera took photographs centered i216 334 7910260 316

Page Two on the Trojan cooling tower. Two additional cameras were located at the Beck farm approximately five miles north of Trojan. These took photographs both upstream and downstrea= of the plant, pro-viding a 120* panoramic view. The downstream camera monitored the Kelso-Longview area. While the program has provided meaningful, valid results, it has not been without its conceptual and operational problems. Selection of worthy sites proved no small problem since sites had to be readily accessible and had to have or be capable of having a reliable power

• supply and of supporting a shelter for the camera equipment. The shelter, of course, needed space conditioning to avoid major extremes of temperature and consequent effects on film image quality.

Finding intervalometers to operate the photographic equipment proved extremely difficult. There were no units available that would adapt to the Super-8mm movie cameras that would trigger the equipment on long time periods (5 to 15 minutes). Final selection of the camera /intervalometer combination was made by a Portland company that was then supplying equipment for photographic counting of fish in Northwest hydroelectric project fish passage facilities. The inter-valometers were bulky and overly complex by present microcircuit standards. While they operated the equipment ef fectively in the early and middle phases of the program, the excessive heat generated in certain of their components resulted in continual equipment outages in the latter phases of the program. The original units have been )}\\

Page Three replaced by much simpler microcircuit and mechanically timed systems. The LED readouts providing date/ time information in the original units were out of focus under low-light conditions such as those prevailing early and late in the day. The replacement equipment uses a standard digital clock which is placed far enough in front of the lens to always be in focus. Early phases of the preoperational program were used to test various ASA film speeds and varying picture frequencies. It was obvious from these earlier phases that longer times (e.g.,15 minutes) between frames were not acceptable. Higher speed films such as Ektachrome 100 were not acceptable because of poor resolution of the projected image. Co:e.equently, the five-minutes per-f rame timing was selected, and Kodachrome II film was selected to maximize resolution in the projected image. Major equipment outages were not anticipated, and consequently when the Kalama site was vandalized and the camera itself was stolen, there was no immediately available replacement equipment. Replacement eq ui p-ment was obtained, but not until af ter a loss of eight months of data at that site. The stolen camera and lens were eventually recovered but were irrepairable because of water damage. Two factors which were, in essence, beyond the control of the experimental design were the fact that the Trojan plant has not been operational as 12i6 336

Page Four much as expected and that low clouds and fog obscured the cameras' views of the plant during many fall, vinter, and early spring days. Observations made in photographs taken from fixed-wing and helicopter aircraf t flights above the fog and low-lying clouds has shown that the Trojan cooling tower plume penetrates these layers into the free air above. Visibility at the plant site was continuously monitored by MRI Model 1580A visiometers. These were placed at 25-and 500-foot levels of, the Trojan meterological tower. It was anticipated that the visibility measures could be compared semiquantitatively to photographic records. The photo monitoring program was initiated three years prior to plant operation. Film covering approximately 530 days prior to cperation was collected from the Kalama site starting from November 1972. At the Beck site, 941 days of preoccupational data from the upstream camera and 977 days from the downstream camera were collected. Operational data from the Kalama camera amounts to approximately 82 days or 8,600 frames of film showing the cooling tower plume. From the Beck upstream camera, approximately 126 days or 5,000 frames were collected showing the cooling tower plume. The film collected from the downstream Beck camera corresponds to approximately 105 days of plant operation. Q\\h b k L

Page Five Visibility data at the meteorological tower was collected hourly. A nearly continuous record of the visibility parameter Sscat at the 25-and 500-foot levels was collected starting from June 1976. II. RESULTS Film obtained from the Kalama camera provided the best records of plume behavior. At the Beck residence site, the camera monitoring the upstream area provided some useful footage of film. The downstream camera, however, was of little use, as the plume did not extend far enough downstream so as to come into the camera's field of view. The camera did, however, monitor plumes from the major industrial sites in the Kelso-Longview area. The cooling tower plume dimensions were found to vary considerably with weather conditions. Plume length ranged from 1,000 feet to approximately 7,000 feet. The plume tends to be very short on sunny days and lengthens on overcast days. Maximum height observed was approximately 6,000 feet. The maximum plume width was approximately 3,000 feet. The plume was generally opaque throughout its length and tended to disperse suddenly at its end. No occurrence of ground impingement was observed. Only one 2-hour occurrence of plume impingement on the 500-foot level visiometer was obs erved. During this event, the 8 levels indicated visibility scat was reduced to a minimum of 600 feet. No impingement was detected at .the 25-foot level. 1216 33B

Page Six No plume impact was observed on the major industrial sites in the Trojan area nor was the plume observed mixing with plumes originating at these sites. The plume was not observed over the Kelso-Longview area. No evidence was found indicating that the plume causes or contributes to ground fog. During fog conditions, the plume has been observed to rise and dissipate above the fog level. As no ground impingement was observed, no plume-caused visibility or icing problems on U.S. Highway 30 were seen. During periods of low cloud cover, the plume could be seen entsring the clouds. This would cause a darkening of the existing cloud cover at the plume's entrance point. It did not, hewever, appear to signi-ficantly contribute to cloud formation. III. CONCLUSIONS Results of the Trojan Cooling Tower Plume Study indicate that the plume has little impact on the surrounding environs. The plume tends to rise and dissipate rapidly. No impact on surface visibility or other adverse surface effects, such as icing, were seen. The results were generally in agreement with those obtained by Smith-Singer Meteorologists in a study of natural draf t cooling towers operated by the American Electric Power Service Corporation ( AEPS). The Smith-Singer Meteorologists' study found that plume length is strongly related to ambient humidity. This ager..s with photographs of 1216 339

Page Seven the Trojan cooling tower plume showing longer plumes on overcast days. Other points of agreement between the two studies were the absence of cooling tower-induced fog and ground impingement. One major difference between plume measurements in the two studies was in plume length. No Trojan cooling tower plume has been observed near the magnitude of the 20-mile maximum length measured at an AEPS plant. The moct useful records of the plume were provided by the time-lapse camera at the Kalama site. Visiometers on the Trojan meteorological tower were not found to be very useful in monitoring the plume due to very infrequent impact in their vicinity. The Trojan Environmental Technical Specifications require ~an evalua-tion of this program after two years from the start of full power operation. Full power operation began in May 1976. Based on the results of the evaluation, the program is to be terminated or modified as required to more closely scrutinize impingement areas. The objectives of determining the plume characteristics and impact have been satisfied. No impingement areas were observed which would require further scrutiny. As no adverse impacts have been seen and the plume characteristics have 1,een adequately recorded, it is concluded that this element of the Trojan cavironmental monitoring program can be termininated. 3Y8

Page Eight IV. REFERENCES 1. " Environmental Technical Specifications for the Trojan Nuclear Plant, Columbia County, Oregon, Docke: No. 50-344," Appendix B to Operating License NPF-1 for the Trojan Nuclear Power Plant, United States Nuclear Regulatory Commission, Office of Nuclear Reactor Regulation, pages 4-21. 2. Kramer, M. L., et al., " Cooling Towers and the Environment," Journal of the Air Pollution Control Association, 26, 582 (1976). RH/2ren83Al 1216 341 gs ., rv

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