ML19256A679

LER 78-026/04L-0 (Suppl Info):In Second Quarter 1978,over Two Std Deviations Existed Between Preoperational Study & Operational Study of Animal Abundance of Benthic Sys in Discharge Basin,Due to Natural Variation or Sampling Methods

ML19256A679
Person / Time
Site:	Crystal River
Issue date:	12/27/1978
From:	FLORIDA POWER CORP.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML19256A676	List: ML19256A675 ML19256A679
References
LER-78-026-04L, LER-78-26-4L, NUDOCS 7901090195
Download: ML19256A679 (2)

Text

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SUPPLEMENTARY INFORMATION

1. Report No.: 50-302/78-026/04L-0

2. Facility:

Crystal River Unit #3

3. Report Date: 27 December 1978

4. Occurrence Date: Second Quarter, 1978 (discover.ed 14 December 1978, determined at plant 27 December 1978)

5. Identification of Occurrence:

A difference of more than two standard deviations (>2a> existed between the preoperational study and the operational study of the animal abundance of the benthic system in the discharge basin at Crystal River Unit #3.

6. Conditions Prior to Occurrence:

Crystal River Unit #3 was not operating during the second quarter of 1978.

7. Description of Occurrence:

The preoperational mean Venturi biomass per square meter in the discharge basin was 2.2087 grams for the second quarter and the operational mean Venturi biomass per square meter (0.5261 grams) plus two standard deviations in the discharge basin for the second quarter of 1978 was 1.9674 grams;thus, the preoperational mean was greater than the operational mean plus two standard deviations.

8. Designation of Apparent Cause:

The apparent causes of the greater than two standard deviation change in the Venturi biomass per square meter in the discharge basin could be: 1) the natura) or seasonal variation in bionass; 2) the possible differences in sampling techniques while performing similar sampling methods; or 3) the in-creased thermal output from the site when Crystal River Unit #3 was operating.

However, the data does not allow the designation of Unit #3 as the conclusive cause because the preoperational and operational data for this parameter were within two standard deviations for the first and third quarters of 1978.

9. Analysis of Occurrence:

In the discharge basin, natural or seasonal changes in biomass and/or differe.ces in sampling techniques while performing similar sampling methods in conjuncti T with the possible effect of the Crystal River Unit #3 addition to the site thermal discharge may have caused the reduction in biomass observed in the operational study as compared to the preoperational s tudy. However, since greater than two standard deviation difference did not exist between pre-operational and the operational data for the first and third quarters 1978, the suggestion of cause and effect by Crystal River Unit #3 can only be cor-roborated by the continuance of this study.

10. Corractive Action:

The decrease in biomass in the discharge basin cannot at this time be attributed to either natural phenomenon or a specific man-made cause. Therefore, the present study will be continued to verify, if possible, the cause. Until such time, no corrective ac. ion can be defined.

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50-302/78-026/04L-0 Page 2

11. Pailure Data:

This is the third report for this type occurrence. Refer to:

78-022/04L-0, dated 31 July 1978 78-024/04L-0, dated 19 September 1978

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