ML20041C278

LER 82-001/01T-0:on 820107,determined That Six RCS Resistance Temp Detectors Did Not Meet Required Response Time.Caused by Couplant Used in Wells Drying Out & Not Providing Adequate Contact or Coupling

ML20041C278
Person / Time
Site:	Arkansas Nuclear
Issue date:	01/14/1982
From:	Rogers P ARKANSAS POWER & LIGHT CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
Shared Package
ML20041C275	List: ML20041C274 ML20041C278
References
LER-82-001-01T, LER-82-1-1T, NUDOCS 8203010029
Download: ML20041C278 (5)

Text

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(VE N, D.,E 7. 'S Hf ,0s. , 0. .g 3 8 60 6 DOCA t r huv.t. I EVENT DESCRIPTION AND PROSAOLE CONSEQUENCES h'd ITTTI IWhile in Mode 1 operation at 100 per cent full power, at 0920 hours0.0106 days <br />0.256 hours <br />0.00152 weeks <br />3.5006e-4 months <br /> on I o i January 7,1982, a determination was made that six (6) reactor coolant i lo i. I Isystem (RCS) resistance temperature detectors (RTD's) did not meet the i n s irequired response time of 6. 0 seconds as per T.S. Table 3.3-2 per T.S.4. i o a l'3.1.1.3 surveillance requirements. A total of 32 RTD's were tested of i go iq sw hich 24 RTD's are inputs to the reactor protective system (RPS). Six of; I

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CAUSE Of SCRiPTION AND CORRECitVE ACTIONS 17 i o l The couplant used in the RTD wells dried out during oneration and con- I g i sequently did not provide adequate contact or coupling between the RTD i

, , i and thennowell wall. At 0940 hours0.0109 days <br />0.261 hours <br />0.00155 weeks <br />3.5767e-4 months <br /> on 1/7/82. a shutdown was initiated I g i per T.S.3.0.3. The RTD's were removed and cleaned. All RCS RTD thermo-i

, . i wells were visually inspected and cleaned, (continued on attached sheet)

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. ATTACHMENT LER N0. 50-368/82-001/0lT-0 EVENT DESCRIPTION AND PROBABLE CONSEQUENCES'(cont'd) time test requirements, and 2 of the remaining 8 RTD's (these RTD's do not input to the RPS) did not meet the response time test requirements. The 6 RTD's which did not meet the response time per T.S.4.3.1.1.3 surveillance requirements affected all reactor protective system channels making their responses to transients and other abnormal conditions questionable. Con-sequently .the reactor was shutdown for evaluation and corrective action.

This occurrence is reportable per T.S.6.9.1.8.e. This occurrence is similar to LER 50-368/81-017/0lT-1.

CAUSE DESCRIPTION AND CORRECTIVE ACTIONS (cont'd) new couplant was installed and the RTD's were reinstalled into the thermowells.

Response time testing on all affected RTD's will be performed and acceptable results confirmed prior to criticality. A test program will be established to monitor RTD performance.

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g I-Reportabic Occurrence Report No. 50-368/82-001/0lT-0 l 2. Report Date: January 14, 1982 3.

Occurrence Date: l/7/82 4

) Facility: Arkansas Nuclear One - Unit 2 Russellville, Arkansas

5. Identification of Occurrence:

Six (6) Reactor Coolant System (RCS) resistance temperature detectors (RTD's) did not meet the required response time as per Technical Specifications (TS) Table 3.3-2 per T.S.4.3.1.1.3 surveillance require-ments. This occurrence is reportable per T.S.6.9.1.8.e.

6 Conditions Prior to Occurrence:

Steady-State Power X 2815 Reactor Power MWth ilot Standby Net Output 857 Mwe Cold Shutdown Percent of Full Power 100S.

Refueling Shutdown Load Changes During Routine Power Operation Routine Startup Operation Routine Shutdown Operation Other (specify)

7. Description of Occurrence:

While in Mode 1 operation at 100% full power, at 0920 hours0.0106 days <br />0.256 hours <br />0.00152 weeks <br />3.5006e-4 months <br /> on January 7, 1982, a determination was made that 6 RCS RTD's did not meet the required response time of 6.0 seconds as per TS Table 3.3-2 per T.S.4.3.1.1.3 sur-veillance requirements. The response time data were collected on 11/21/81.

Due to the complexity of the test and the data analysis, the testing and data analysis was contracted with Analysis and Mea. .irement Services (AMS)

Corporation.

The test results were not received un il 1/7/82 at which time

' the determination was made. The 6 RTD's which did ri)t meet the response time requirements affected all Reactor Protective System (RpS) channels.

This occurrence is similar to LER 50-368/81-017/0lT-1. o

2- .

Reportable Occurrence iteport No. 50-368/82-001/0lT-0

8. Designation of Apparent Cause of Occurrence:

Design Procedure tenu facture Unusual Service Condition Including Environmental Installation /

Const ruction Component Failure (See Failure Data)

Operator i

Other (specify)

The couplant compound ('Never-Seez') used in the RTD wells dried out j during operation leaving a powdery residue. This caused inadequate

coupling between the RTD and t

,e thermowell wall. 'Never Seez' was recommended by the Nuclear Steam System Supplier (NSSS) vendor. to improve heat transfer between the thermowell andsensor(RTD).

9. Analysis of Occurrence:

A total of 32 RTD's were tested of which 24 RTD's are inputs to the RPS. Six of these 24 RTD's did not meet the response time per T.S.4.3.1.1.3 surveillance requirements, and 2 of the remaining 8 RTD's (These RTD's do not input to the RPS) did not meet the~ response time test requirements but are not subject to this specification. When first analyzed, a determi-nation was made that the 6 RTD's which did not meet the response

.ments of 6.0 seconds affected all Reactor Protective System (RPS) time reauire-channels making their responses to transients and other abnormal conditions question-able. Subsequent analysis of how the Core Protection Calculators (CPC's)

use the inputs from the RCS RTD',1, indicates that the RPS would have actuated early enough to protect against loe DNBR or high local power density occur-rences. However, the trend toward degradation indicates that the response time of the RPS would have been degraded unacceptably in the near future with-l 'out corrective action.

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Reportabic occurrence Report No. 50-368/82-001/0lT-0

10. Cctrective detion:

At 0940 hours0.0109 days <br />0.261 hours <br />0.00155 weeks <br />3.5767e-4 months <br /> on 1/7/82 a shutdown was initiated per T.S.3.0.3. All RCS RTD's were removed and cleaned. All RCS RTD thermowells were visually inspected and cleaned. New couplant was installed, and the RTD's were reinstalled into the thermowells. Response time testing will be performed and analyzed prior to criticality. A test program will be established to monitor RTD performance with a frequency sufficient to detect degradation prior to unacceptable RPS response times. Also a review of the analysis requiring a 6.0 seconds time response will be evaluated.

11. Failure Data:

This is a failure of the 'Never-Seez' couplant rather than equipment.

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