ML19319C958

LER 78-022/04L-0:on 780713 & 31,difference Found to Exist Between Preoperational & Operational Study of Benthic Sys Animal Abundance.Probably Caused by Seasonal Variation & Sampling Technique Differences.Exact Cause to Be Verified

ML19319C958
Person / Time
Site:	Crystal River
Issue date:	07/31/1978
From:	FLORIDA POWER CORP.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML19319C943	List: ML19319C942 ML19319C958
References
LER-78-022-04L, LER-78-22-4L, NUDOCS 8003040894
Download: ML19319C958 (2)

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SUPPLEMENTARY IN70RMATION J

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1. 50-302/78-022/04L-0 l (vptNo.: ,

1. Fec111ty: Crystal River Unit #3

3. Report Date: July 31, 1978

4 Occurrence Date: First Half, 1977 (discovered 13 July 1978)

(determined at plant 31 July 1978)

5. Idcntification of Occurrence:

A difference of more than two standard deviations ('>2r) existed between the preoperational study and the operational study of the animal abundance of the benthic system at Crystal River-Unit 13.

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6. Conditions Prior to Occurrence: I The site generation capacity factor for the first quarter of 1977 was 45% and for the second quarter of 1977 it was 53%.

7. Dancription of Occurrence:

The preoperational mean number of individuals per square meter in the control basin (intake area) was 75 for the first quarter and the operational mean number m f individuals per square meter was 332 for the first quarter of 1977. The

'erational

mean less two standard deviations was 96. Thus, the preoperational (danfellbelowtheoperationalmeanlesstwostandarddeviations. The preoperational mean number of individuals per square meter in the discharge basin was 52 for the second quarter and the operational mean number of individuals per square meter (16) plus two standard deviations in the discharge basin for the second quarter of 1977 was 38. Thus, the preoperational mean was greater than the operational mean plus two standard deviations.

3. Dssignation of Apparent cause:

The apparent causes of the greater than two standard deviation change in the number of individuals per square meter in the control basin could be the natural or seasonal variation in animal abundance, and the possible differences in sampling techniques while performing similar sampling methods.

The apparent causes of the greater than twn standard deviation change in the number of individuais per square meter in the discharge basin are the possible variations noted above in conjunction with the increased thermal output from the site due to Crystal River Unit #3. However, the data does not allow the designation of Unit 13 as a conclusive cause because the preoperational and operational data were within two standard deviations for the remaining three quarters of 1977.

9. Analysis of Occurrence:

a the control basin, both the preoperational and the operational data show large g iriations. These variations may have been caused by natural or seasonal changes in ani=al abundance and/or by difference in sampling techniques while performing similar sampling methods. The thermal discharge of the site cannot be a factor in this difference as the control basin is removed from the area of influence of the site.

8003040hf

Supplementtry Information 50-302/78-022/04L-0

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9. Analysis of Occurrence (Cont'd)

In the discharge basin, the possible variations as noted above in con-junction with the possible effect of the Crystal River Unic #3 addition to the site thermal discharge may have caused the reduction in animal abundance ob-served in the operational study as compared to the preoperational study. However, since greater than two standard deviation difference did not exist between pre-operational and the operational data for the third and fourth quarters, the suggestion of cause and effect by Crystal River Unit 13 can only be corroborated by the continuance of this study.

10. Corrective Action:

The decrease in animal abundance in the discharge basin cannot at this time be  !

attributed to either natural phenomenon or a specific san-made cause. Tnerefore, the present study will be continued to verify,1f possible,the cause. Until such time, no corrective action can be defined. l L1. Failure Data:

1 This is the first repcre for this type occurrence. '

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