05000302/LER-1978-027-01, /01T-0:on 780511,B&W Found to Apply to CR-3 Incore Instruments Sys.Caused by Insufficienct Data from Prototype Studies.Corrective Actions Will Be Forwarded in Revision 1 to LER

/01T-0:on 780511,B&W Found to Apply to CR-3 Incore Instruments Sys.Caused by Insufficienct Data from Prototype Studies.Corrective Actions Will Be Forwarded in Revision 1 to LER

ML19319D067
Person / Time
Site:	Crystal River
Issue date:	05/12/1978
From:	Cooper J FLORIDA POWER CORP.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML19319D049	List:
References
LER-78-027-01T, LER-78-27-1T, NUDOCS 8003040981
Download: ML19319D067 (6)

LER-1978-027, /01T-0:on 780511,B&W Found to Apply to CR-3 Incore Instruments Sys.Caused by Insufficienct Data from Prototype Studies.Corrective Actions Will Be Forwarded in Revision 1 to LER

Event date:
Report date:
3021978027R01 - NRC Website

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lThis will confirm a report made to Mr. R. H.Wess=mn of your off4r.. s t-I o

r.u ni i 1515 on 11 May 1978.

At 1400. it was determined that a letter received I

from B&W on 8 May 1978 concerning uncertainties associated with incore g

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instruments does apply to CR-3.

Redundancy NA.

No hazard to the nealth j

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,, i iand safety of the plant or public as plant is defueled.

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m I prototype incore instrument studies. Corrective Actions are presentiv i

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(SEE ATTACllED SUPPLEMENTAP.Y INFOPETION S11EET)

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SUPPLEMENTARY INFORMATION 4

1.~

'rt No.:

50-302/78-027/01T-0 Y

2.

viility:

Crystal River Unit #3 3.

Rep:rt Date:

12 May 1978 l4 Occurrence Date:

11 May 1978

, 5.

Id:ntification of Occurrence:

The values stated in Technical Speicifcation 3.2.1, Figure 3.2-1 & 3.2.4, Table 3.2-2 are believed to be non-conservative, as determined by B&W instituted program.

6.

Conditions Prior to Occurrence:

Mode 6 refueling.

7.

D:scription of occurrence:

b At 1400 it was determined that a letter received from B&W on 8 May 1978 does apply to CR-3 incore instruments systems.

The letter states in part:

S The initial error analysis for quadrant tilt and imbalance values derived from incore detector system signals was performed by B&W in 1974 based upon data obtained from

]

prototype detectors.

The results of the study were used to develop a tilt and imbalance error analysis for operating limits. As a result of concern expressed about these un-certainties based upon observed operational characteristics, B&W instituted a program early in 1978 to reevaluate the uncertainties using operating data.

Based upon incore detector performance at B&W operating plants, particularly in terms of quadrant power tilt measurement, it was proposed that the present uncertainty allowances for tilt and' imbalance might be insufficient.

Thus, the individual detector uncertainty value from currently available data was used in statistical analyses to determine the uncertainties which should be applied to the limiting quadrant tilt and imbalance values.

i The reinvestigation of the quadrant power tilt uncertainty found that the previous uncertainty values are too small and should be increased. The new uncertainty values are too small and should be increased.

The new uncertainty values are a function of both the individual incore detector signal uncertainty and the tilt limits. Table 1 gives the new tilt alarm limits corresponding to the existing actual Tech Spec limits for Crystal River #3.

The reinvestigation of uncertainties also led to increased uncertainties associated with imbalance. Tables 2 and 3 give the new imbalance alarm'setpoints for B&W operating plants corresponding to the approved technical specification limits for the current cycle of operation.

8.

Dasignation of Apparent Cause:

Cause of this event is due to insufficient data from prototype studies.

19.

ysis of occurrence:

d No hazard to the health and safety of plant or public as plant is defueled.

1

4 Supplementary Information

<tt No. 50-302/78-027/01T-0

~

1 2

10.

Corrective Action

Corrective actions are currently being formulated by CR-3 plant staff and B&W. Upon

.w.letion, a revision to the report will be forwarded, 11.

Fa11urt Data:

First occurrence of an event of this' type, i

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TABLE 1 y

quadrant Tilt Lirrilts and Setpoints Alarm Setooints

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Tech Spec Full Symmetric Minimum Symrretric Ou t-o f-Co re Plant Limit (Actual Tilt)

System System System Crys tal River-3*

4.92 2.27 f.90 1.85 11.07 7.77 4.40 6.85 4

Changes required in Technical Speci fication. Table 3.2-2.

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- _ _.a TAOLE 2 s.

f CRYSTAL RIVER-3 CYCLE 1 FR.0M 269 TO 40 3 EFP D

• ERROR ADJLSTED LOCA LIMITS POWER IMBALANCE LIMIT ALARM SETPOINTS

% OF 2452MW TECH SPECS FULL INCORE MINIMUM INCORE OUT-OF-CORE 0

- 34.00

- 25 00

- 23.33

- 22.75 68.

- 34.00

- 25 00

- 23.33

- 22.75 80.

- 3 0.* 0C

~ -22 43

- 19.55

- 19.33 92.

- 24.00

- 18.00

- 14.09

- 14.27 i f, 2.

- 2 4.00

- 18.96

- 13.74

- 14.45 102.

6.00 1.20

- 2. 4 0.

- 3.12 92.

8.00 2'.20

.27

- 1.34 84.

'17.00 9.59 7.65 6.75 70.

30.GG 20.77 19 20 13.45 0.'

3G.0:

20.77 19.23 13.45

• Assumes no changes necessary for Cycle 1-B ope ration.

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TABLE 3 s

CRYSTAL RIVER-3 CYCLE 1 FROM 400 EFPO TO EOC *

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ERROR ADJUSTED LOCA LIMITS POWER IMSALANCE LIMIT AL ARM SETp0INTS

% OF 2452MW TECH SPECS FULL'INCORE MINIMUM INC CR E OUT-OF-CORE

- 3.4.03

- 24.54

- 23.13

- 22.34 j

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68.

- 3 4.00

- 24.54

- 23 13

- 22.3'4 80.

- 30.00

- 22.12

- 19.35

- 19 01 92.

- 1 5.02

- 9.47

- 6.33

- 5.81 102.

- 15.00

- i c. 5 6

- 5.9S

- 6.06 iC2.

6.00 1.17

,2.60

- 3.20 92.

5.00 2.04

.47

- 1.49 54.

17.C]

9.63 7.45 6.63 7C.

30.07 20.34 19.00 1S.35 3.

30.00 2G.34 19.03 18.86

• Assumes no changes necessary for Cycle 1-B Operation.

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