ML19308D274

RO-77-29:on 770416,cooldown Rate in Excess of Tech Spec Limit Occurred During Reactor Shutdown Remote from from Control Ctr.Caused by Pressure Transmitter Out of Calibr. Transmitter Calibr & Trip Feed Pump Procedure Revised

ML19308D274
Person / Time
Site:	Crystal River
Issue date:	04/21/1977
From:	Stewart W FLORIDA POWER CORP.
To:
Shared Package
ML19308D270	List: ML19308D269 ML19308D274
References
NUDOCS 8002270721
Download: ML19308D274 (3)

Text

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@l During the performance of Reactor shutdown remote from the Control Center, an excessive l r u9 60

@ l cooldown race' was experienced contrary to Technical Specification 3.4.9.1. This was pri- l

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@ l marily caused by overfilling of the steam generators contrary to Technical Specification l

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/ U9 l 3.4.5. First occurrence of high level in steam generators. Thih is second occurrence of 09 l

$ l excessive cooldown rate. Fed Reactor Coolant System from borated water storage tank. (77-29)l

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[o] l The cause of this occurrence was ,the overfilling of the OTSG due to out-of-calibration l, 1 09 00 Qjl pressure transmitter not causing start-up feedwater' valves WV-39 and 40 to fully close. l

/ 09 80 f' Calibrated pressure transmitter and revised procedure to trip feed pump when appropriate. l

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SUPPLENENTARY INFORMATION

• I l 1. Report No. 50-302/77-29

( 2. Facility: Crystal River Unit #3

3. Report Date: 21 April 1977 i

4. Occurrence Date: 16 April 1977 l S. Identification of occurrence:

! During the process of performing Reactor shutdown remote from the Con-

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trol Center, an excessive cooldown rate contrary to Technical Specifi-cation 3.4.9.1 was experienced in that the cooldown rate was approximately

! 101 F. in 20 minutes. This was primarily caused by overfilling of the '

i steam generators contrary to Technical Specification,3.4.5 to a level .

! above 360 inches.

6. f.

Conditions Prior to Occurrence:

, Plant was in Mode 3 during test of shutdown from outside the Control Room.

Reactor had tripped.

! 7. Description of Occurrence:

J At approximately 0815, during remote shutdown test, overfilling of the OTSG's past the high level limits was experienced. It was determined that start-up feedwater valves FWV-39 and 40 were not fully seated causing j the overfill. An attempt wat made to throttle the FWP discharge to no

! avail. The steam generator drains and atmospheric dump valves were opened i and excessive cooldown rate was experienced. Reactor coolant temperature i

. decreased 1010 F. in 20 minutes.

l 8. Designation of Apparent Cause of Occurrence:

The cause of this occurrence was the overfilling of the OTSG due to out-

, of-calibration pressure transmitter not causing start-up feedwater valves' FWV-39 and 40 to fully close.

?

9. Analysis of Occurrence:

I At all times, the Reactor coolant temperature / pressure parameters remained within the region of acceptable operation set forth in Technical Specifica-tion 3.4.9.1, Figure 3.4.3. Prior to start-up and power operation, an engineering evaluation was performed to determine the effects of the cool-down on the fracture toughness properties of the Rx coolant system. It l was determined that the RCS remained acceptable for continued operation.

We have been informed by Babcock & Wilcox that the cooldown transient

. which occurred on 2 March 1977 (LER-77-20) "was found to cause no derroga-tory effects". That transient was more severe than the one occurring on 16 April 1977. Therefore, it is determined that this transient did not endanger the safety of the plant.'

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, .Sup'plementary Information (Cont'd.)

10. Corrective Action:

i

' The pressure transmitter has been recalibrated to assure closure of the start-up feedwater valves. In addition, the test and operating

, procedures have been revised to incorporate tripping of the main 4

feedwater pump at the appropriate time to prevent overfilling of' the steam generators. ^

11. Failure Data:

This is the second occurrence of cooldown in excess of 100 F. in one hour (LER-77-20). It is the first occurrence from these causes.

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