ML19254D345

Rept Re Sound Surveys Conducted Near Site on 790901 & Estimates of Sound Generated by Major Noise Sources at Plant

ML19254D345
Person / Time
Site:	Sequoyah
Issue date:	09/01/1979
From:	TENNESSEE VALLEY AUTHORITY
To:
References
NUDOCS 7910250371
Download: ML19254D345 (11)

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Introduction This report is based on sound surveys conducted near the Sequoyah Nuclear ' ant on Saturday, September 1, 1979, and on estimates of sound generated by najor noise sources at thc plant. Since construction activities vere not taking place on this day, the data represent pre-operational sound levels at this time.

For purposes of this report we have assumed that both gener ting units would be operating and that the cooling te ers would be operating continuously during the su==er months. However, this is a multimode plant (open, helper, and closed modes) and we anticipate that in actual practice the plant will operate in open mode about 80 percent of the time, helper mode 16 percent, and closed mode about 4 percent of the time.

Noise-Sensitive Land Uses Most of the land areas outside the plant boundary and within a one-mile

adius of the plant appear to be rural residential or undeveloped water-f ront properties. There appear to be 20 to 30 homes within the one-mile radius. Some of these are on lakefront property.

Within the two-mile radius there are over 140 homes, one church, and a peninsula of Harrison Bay State Park. There are no echools or hospitals wit: 'n the three-mile radius.

The nearest residen;ial area to the plant transformers is along Igou Ferry Road west of the site. The nearest residence to the cooling towers seems to be on Chigger Point across the lake to the east.

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Preoperational Sound Survey TVA conducted sound surveys at three sele"cted community locations near the Sequoyah Nuclear Plant site on Friday, August 31, and Saturday, September 1, 1979. The locations of the sampling points are shown on Figure 1.

The August 31 survey data represent the sound environment during construction activities ai the site. These data were not used in impact assessment.

The survey conducted on Saturday, September 1, 1979, provided data which can be used as preoperational or baseline data for impact assess-ment. No construction activity was in progress at the project on September 1.1/ Thus the data represent current, typical summertime environmental sound values in the vicinity when no construction or production noise is occurring at the TVA plant site.

Tape recordings were made at each survey location. The time of day was randomly selected. Recordings lasted 15 minutes at each location. Both daytime (7 a.m. - 10 p m.) and nightnime (10 p.m. - 7 a.m.) recordings were obtained for the preoperational sound surveys (September 1). Only daytime values were obtained for the construction sound surveys (August 31). Tapes were computer analyzed to yield equivalent sound levela for daytime periods (Ld), nighttime periods (Ln) and for the day-night composite (Ldn).

_lf The last work shift ended at 2300 hours0.0266 days <br />0.639 hours <br />0.0038 weeks <br />8.7515e-4 months <br />, Friday, August 31. 1979. In order to avoid shift traffic noise, the baseline surveys did not start until 0015 hours1.736111e-4 days <br />0.00417 hours <br />2.480159e-5 weeks <br />5.7075e-6 months <br />, September 1, 1979.

2) The instrumentation system used in measuring baseline noise levels consisted of a General Radio Model 1982 sound level =eter and a Nagra model E single track, reel to reel, tape recorder.

(continued next page)

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Con't Footnote 2 continued:

The General Radio Model 1982 is a precision sound level meter and analyzer using a 1/2 inch flat randem incidence microphone.

The frequency range is from 10 HZ to 20 KHZ at the 3dB down points.

This instru=ent meets the Ansi Standard Sl.4-1971 for a type 1 instrument. The signal output of the 1982 SLM is fed into the Nagra Model E for data recordings.

The Nagra Model E tape recordgr is a portable unit, single track, with a frequency response of - 2dB from 50 HZ to 15 KHZ using Scotch 212 low noise tape. This component with the GR1982, establishes a system that provides recordings of sound data over a frequency range of 50 HZ to 15 KHZ. Calibration of the system is conducted using a GR1562 microphone calibrator at a level of 114 dB at 1000 HZ.

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While survey crews were at each location they also made baseline octave band sound pressure level readings. These will serve as a basis for identifying and characterizing any operational sounds which may show spectral prominences. The analog tapes will also be preserved for more detailed analyses if needed.

The survey data are su=marized in Table 1. The baseline equivalent sound levels are rather hight. On the west side of the plant site, baseline Ldn values slightly exceed 55 decibel maximum level identi-fled by EPA as requisite to protect public health and welfare (Ref. 1).

The baseline Ldn at Chigger Point, across the lake is only one decibel below the EPA level. This community-generated sound seems to originate from insects, motor vehicles, boats, aircraft, birds, and general community activity such as lawn mowing.

Operational N61se Impacts The two major continuous noise sources considered in this analysis were the switchyard transforme: ,

(two banks of thre2 each) and the two natural draft cooling towers Although the transformers do not emit pure tones, they will have a spectral characteristic which might cause the sound to stand out against a random background. Using published values for noise emission from large cooling towers (Ref. 2) and TVA survey data on transformer noise emission'(Ref. 3), operational sound levels at the survey points were estimated. Data are presented in Table 2.

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In this analysis no consideration is included for attenuation or reflection from nearby surface features such as building, water surfaces, and hills. Obviously, such features can strongly influence propagation of sound waves. For example, the power station buildings will intercept sound traveling from the transformers toward Chigger Point. This will have a lowering effect on operational sounds at Chigger Point. Conversely, operational sound will be reflected by the water surface of Chickamauga Lake as it travels toward Chigger Point. The result could be enhanced sound transmission to Chigger Point.

The effects of the estimated transformer and cooling tower sound levels on the present preoperstional (baseline) sound levels are summarized in Table 3.

The data show that transformer and cooling tower sounds will some-times be audible offsite. Transformer sound will prevail over cooling tower sound at areas on the west side of the plant site, whereas, cooling tower noise will prevail to the east. Due to the high baseline sound levels, the total sound levels during operation will exceed the sound levels identified by EPA as necessary to protect the public with an adequate margin of safety.

Other continuous noise sources not included in this analysis were the building ventilation fans, the intake cooling water pumps, and plant vehicle traffic. TVA experience indicates that these are minor noise sources and should exert little, if any, effect beyond plant boundaries.

Intermittent sound sources will include audible warning systems, plant paging and code-call systems, c7ergency support systems (e.g., generator and ficod pumps), and heavy maintenance equipment. Unfortunately, we do not have a data base on these sources, 120ne 13m7

Two intermittent and infrequent, but significantly loud, noise sources are the air-blast circuit breakers (ACB) and the steam vents.

A one month sample of the ACB records showed that they were exercised approximately 45 times. An ACB underload will generate about 140 decibels of impulse noise at a distance of 50 feet. Sound generated during steam venting is a function of several variables including steam pressure and valve geometry. An estimate of sound emission from the Sequoyah plant vents is not available at this time. We have unofficial data from Or.ario Hydro that a sound level of about 84 dBA might be expected at a distance of 2500 feet from a superheater pressure valve venting to atmosphere under 2300 psi steam pressure. Using these sound levels for circuit breakert and steam vents, we can estimate corresponding sound levels at 'he points of interest around the Sequoyah plant site.

These are shown in Table 4. Sound levels of this magnitude will be distinctly audible offsite and will probably not diminisn to inaudible levels for distances up to several miles.

Conclusions Although baseline sound levels are relatively high, sound from the transformer and cooling towers will sometimes be audible offsite. However, since this is a multimode cooling system (open approximately 80 percent of the time helper approxicately 16 percent of the time, and closed approximately 4 percent of the time) the amount of time that noise will be emitted from the cooling towers should be minimized. These baseline sound levels will be somewhat augmented by sound from lesser, but yet unquantified, plant sources (plant traffic, communication systems, etc.).

Sound from the intermittent and infrequent use of both the air blast circuit breakers and the steam vents will be clearly audible offsite.

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References

1. Information on Levels of Environmental Noise Recuisite to Protect Public Health and Welfare With an Adecuate Margin of Safety, Report No. 550/9-74-004, USEPA, Arlington, I Virginia, March 1974.

2. " Noise Prediction Techniques for Siting Large Natural-Draft and Mechanical-Draft Cooling Tcwers," G. A. Capano and W. E.

Bradley, V. 38, Proceedings of the American Power Conference, 1376, pp. 756-763.

3. " Noise Survey and Impact Report, Volunteer 500 kV Substation Site," C. C. Thornton, TVA Industiral Hygiene Branch Technical Report, IH-76-5, September 24, 1976.

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% TA!!LE 1 SITE Sequ yah Nucle r Plant Pr SUMMER NOISE SURVEY DATA ^ T ' " " " " "' ' i - ) " "" 8 " " '

ENGR. r s ,"t . ) 1970 -- Jr 6 SS LOCATION LEVEL ODSPL- dD- OCTAVE DAND CEf1TER FREOUEtJCY

9 Leg lLdn d8A 3t.S G3 125 250 500 IK 2K 4K 8K 16K Northteest of Site. Approx. 47 43

1. 2400 ft. from switchyard, 4200 ft. Ld 51 49 44 43 40 33 30 33 37 32 5 f'

{ll T 1f44 N f' 1 '

Ln 50 50 49 49 44 44 41 30 46 42 41 35

', tiest of Site. A 2400 ft. _

frc :n. sw it chva rd 48 43 47 49 45 39 36 27 28 2- coo l

, p300

.roxf.!iept.frgm at.,

et --Id 56 -

36 39 37 yg toutrs. ,

50 49 47 0212 o 1416 brs.

M 49 42 34 34 25 44 42 45 49 3- N) h oftN[vi Ndd ISN) [t. from co.

any owers, Sal. ,

1.6 s4 38 40 42 40 37 '14 28 27 31 32 25 Sept. 1, 0015 and 10!3 brs. In 48 47 42 44 42 33 24 16 35 44 43 26

. t.d ,

l.n

• Ne iIt nN I 57 55 52 54 44 39 37 28 28 47 1' nolnai con.c 31, 19/9, 205/ hrs.

ucf(ion.Es .dIrutd'I>, Aug. 49 52

- tn S a r.e location as t.o . / above. 1)ata re pokirement s cond t.d 48 47 57 57 46 ruc tition ionsFri.,

during 43 inal con:,t Aug. 31, 43 33 41 37 41 26 1 1979 2024 hr:- Ln C3 CD O

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Table 2

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Estimated Oncrational Sound Levels Ncrr Secuovan Nuclear Plant

' Cooline Tower and Trans former Scund l

Es timated Oncrational Sound Levels. DEA location of Assessment Point Cooline Towers

• Trans f o rme rs ** Combined No. 1 on map. Residence near

• plant boundary S.W. of site.

2400 feet f rom switchyard,

' 53 55 4200 feet from c.c. 50 No. 2 on map. Residence near plant boundary W. of site.

24C0 feet f rom switchyard, 4300 feet from c.t. 50 53 55 No. 3 on map. Residence on

• Chigger Point S.E. of plant.

5700 feet f rom switchyard, l 3700 feet from c.t. 51 45 52 l

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• However, since this is a multimode cooling system (open mode approxi-I mately 80 percent, helper code approximately 16 percent, and closed mode approximately 4 percent of the time in the summer months), the amount of time that noise will be emitted um the cooling towers should be minimized.

=2The transformers will emit a tone having spectral characteristics :ather i than pure tones.

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Table 3 Operational Sound Impacts From Transformer, and Cooline Towers Su=cr 1979 Baseline Operational Total Decibels Increase Sound Level Sound Level Sound Level Over 3aseline No. 1 on map. N.W. of site Ld 47 55 56 9 2400 feet from switchyard. Ln 50 56 6 4200 feet from c.t. IAn 56 ,

62 6 s

No. 2 on map. West of Ld 48 55 56 3 site. 2400 feet from Ln 50 56 6 switchyard. 4300 feet Ldn 56 62 6 from c.t.

No. 3 on map. Chigger Ld 45 52 53 3 Point 5700 feet from Ln 43 54 6 swtichyard. 3700 Zeet Ldn 54 60 4 to c.t.

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4 1208 137 p 64 * &een

Table 4 Estimated Operational Sound Levels Near Sequoyah Nuclear Plant

, Air Blast Circed t 3reakers (AC31 and Steam Vent Valves

~rtimated Operational Sound Levels, d3A Locatic- of Assessm~ - Point ACb (Impulse Scundl

• ju n~1e S t or- Vent No. 1 o. mp. N,W. plant.

2400 feet frva AC3. 2300 feet from vents 107 S3 No. 2 on map. West of plant #

2400 feet from ACB. 3100 feet from vents. 107 S3 No. 3 on map. Across river at Chigger Point. 5700 feet from AC3, 5400 feet from vents. 99 73

• A random monthly sample of records showed that the ACB's were exercised approximately 45 times.

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