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LER 90-003-00:on 900212,determined That 13 safety-related Transmitters Inoperable Due to Housing Covers Found W/Torque Values Less than Required to Meet Environ Qualification. Corrective Actions Program enhanced.W/900409 Ltr
	ML20042E158
Person / Time
Site:	Clinton
Issue date:	04/09/1990
From:	Chitester T, Spangenberg F; ILLINOIS POWER CO.
To:	; NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
	LER-90-003, LER-90-3, U-601641, NUDOCS 9004200296
	Download: ML20042E158 (8)
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1A5-90(04 09)-LP i 20.220 t ILLIN0/8 POWER COMPANY IP CLINTON POWER STAfl0N. P.O. BOK 678. CLINTON. ILLIN0l$ $1727 l

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April 9, 1990 l i

l 10CFR50.73 [

l, Docket No. 50-461- -

U.S.' Nuclear Regulatory Commission o' Document Control Desk

- Washington, D.C. = 20555 l - Subj ect:- Clinton Power Station - Unit 1 Licensee Event Reoort No; 90 003-00 l

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Dear Sir:

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Please find enclosed Licensee Event Report No. 90 003 00:- i Inonerability of 13 Ro'memount Transmitters due to ' loose Covers and a , *

(; Broken Neck Seal. This report is being submitted in4 accordance.with:the -r requirements of.10CFR50.73. .;

Sincerely yours, l

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F. A. Span jenbe 'III. ;

Manager Dicens g and S fety-DAS/alg l

Enclosure .,

cc: NRC Resident Office :

NRC Region III, Regional Administrator i INPO Records ' Center- t Illinois Department of Nuclear Safety NRC;Clinton Licensing Project Manager i

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On March 8, 1990, with the plant.in cold-shutdown, it was determined that 13 safety related transmitters in various systems had been inoperable due to a failure to meet environmental qualification requirernnts. Twelve of the affected transmitters were inoperable because.their housing covers <

were found with torque values less than CPS requires in order to-meet their environmental qualification requirements. The remaining transmitter was inoperable due to a broken neck seal. Seven of these-13 transmitters are required to be operable per the plant's Technical Specifications and four are required to be operable to satisfy the requirements of Regulatory Cuide 1.97 for post-accident monitoring. The remaining two transmitters are provided for monitoring of safety-related systems. The length of time these transmitters were inoperable is indeterminate; however, redundant instrumentation or instrumentation of other parameters remained available to fulfill the safety functions of these transmitters. The operability of these transmitters was restored during the plant shutdown. Additionally, a preventive maintenance task has been generated to periodically _ check the cover torque and neck seal integrity of the 206 environmentally qualified Rosemount transmitters.

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. DESCRIPTION OF EVENT on March 8, 1990, with the plant in cold. shutdown (Mode 4), it was determined that thirteen safety related transmittero [PDT) had been inoperable in various systems due to a failure to meet environmental r qualification requirements. Twelve of the affected transmitters were- 2 ,

inoperable'because their housing covers were. found with- torque values less-than what CPS requires in order to meet their environmental J l qualification requirements. The remaining transmitter was inoperable due i

to a broken neck seal. ,

g On February 12, 1990, the plant was'in Mode 1 (power operation) at }

approximately 100 percent reactor [RCT) power. At approximately 0830 hours0.00961 days 0.231 hours 0.00137 weeks 3.15815e-4 months ,-during a routine plant walkdown, an Illinois Power Company (IP)

Quality Verification (QV)' inspector identified that- the housing cover of L

transanitter 1LT-CH260D-[LT) was loose. This' cover is required _to be tight in order to provide a' seal to prevent noisture from entering the 1 electronics head during Loss of Coolant Accident -(IDCA) conditions.

Transmitter ILT CH260D.is required to be environmentally qualified and is one of twelve transmitters used to measure' wide range-suppression pool level (IK). The'QV inspector initiated a plant condition report and Maintenance Work Request' (HUR) D06747 ' to tighten the housing cover. . -

Because of events unrelated to this report (reference LER 90-001), the plant was placed in' hot shutdown (Mode 3) at 0524 hours0.00606 days 0.146 hours 8.664021e-4 weeks 1.99382e-4 months on' February 13, '

1990. The plant achioved cold shutdown at 2134 hours0.0247 days 0.593 hours 0.00353 weeks 8.11987e-4 months on February 13, 1990.

On February 15, 1990, with the plant in cold shutdown, IP determined that a quantitativo check of the environmentally qualified Rosemount transmitters should be performed as a result of the identification of the loose housing cover on ILT-CM260D and because of a similar condition identified in November 1989 which affected the operability of three different transmitters. (Based upon the systems and functions affected, the condition of these three transmitters in November 1989 was determined not to be reportable pursuant to 10CFR50.73.) MWRs'D15049 and D15054 were initiated to check the . cover torque, cover gap, neck seal integrity, and conduit plug installation on the 206 environmentally qualified Rosemount transmitters.. Any loose covers found during these inspections were retorqued to the required 200 inch-pounds. These MWRs were completed during the plant shutdown and the results of these inspections were forwarded to the Clinton Power Station-(CPS) Nuclear. Station Engineering Department (NSED) for evaluation. The'results of the i evaluation performed by NSED are presented below.

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. As a result of the checks performed under the above MVRs, twelve additional transmitters were determined to have been inoperable because they did not meet their environmental' qualification requirements (eleven because of loose housing covers, and one due to a broken neck seal).

These twelve additional transmitters consisted of 1833-N024A and D [FI)

(which provide reactor recirculation [AD) loop "B" flow input to two channels of the Reactor Protection System (RPS) [JC) flow biased high thermal power scram actuation logic), ILT-CM030 and ILT-SM013 [LT) (which

[' provide suppression pool level input to the Division I Suppression Pool Makeup [BT) system' actuation logic), IE12 N062A [PT) (which provides- ,

containment ~ [NH) pressure input to the Division I' actuation logic for the l , containment spray function of the Residual Heat Removal (RHR) [BO) ,

system), 1PT CM035 [PT) (which provides input to a containment pressure recorder [PR) in the main control room), IPT-CH257 [PT) (which provides input to a high range containment pressure recorder in the main control-room), 1PT-CM064 [PT) (which provides input to a drywell pressure recorder in the main control room), IE12 N015B [FT) (which provides input ,

to the RHR loop *B" flow indicator [FI) in the main control room), 1C41-N004 [PT) (which provides input to the Standby Liquid Control [BR) system i pump [P) discharge header pressure indicator [PI) in the main control' .

room), IPT-IA081 [PT) (which provides input to the Division.II Automatic ,

Depressurization System (ADS) [RV) backup air bottle [LE) header pressure indicator in the main control room), and IPDT-HC052 [PDT) (which provides input to a Containment and Drywell Atmosphere Mixing [BB) system compressor [ CMP) differential pressure indicator [PDI) in the main i control room). j These conditions affected the operability of at least one train or ;

t channel in multiple systems needed for safe shutdown of the plant and to ;

mitigate the consequences of an accident. However, based upon the :

results of the inspections performed in February 1990, redundant !

instrumentation or instrumentation of other parameters for fulfilling each of these safety functions remained available. This determination was made on March 8, 1990 following NSED review of the results of the -

inspections performed under MWRs D15049 and D15054. The affected transmitters were not required to be operable per the plant's Technical Specifications at the time that these conditions were identified (i.e.,

cold shutdown); therefore, no action per the plant's Technical Specifications was required to be taken.

In addition to loose housing covers, other conditions were identified for other transmitters during the performance of HWRs D15049 and D15054 that were subsequently determined not to affect transmitter operability.

These conditions consisted of three additional transmitters with broken neck seals and two additional transmitters with missing conduit seals.

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. No automatic or manually initiated safety system responses were necessary to place the plant in a safe and stable condition. No other equipment-or components were inoperable at the start of this event such that their inoperable condition contributed to this event.

CAUSE OF EVENT L

The root cause of these conditions is indeterminate. However, the

[ corrective action taken following the identification of loose transmitter housing covers in November 1989 was inadequate in that only a qualitative check of cover tightness (i.e., hand-tight) was performed. Further-investigation into the root cause of the loose housing covers is being performed. This investigation will include a review of previous a

maintenance and testing performed on the affected transmitters which required removal of the housing covers. Additionally. the possibility of.

, housing covers loosening over time is being investigated. If any L significant information is determined from this review, a supplemental report will be provided.

CORRECTIVE ACTION As noted above, the corrective action taken in November 1989 was-determined to be inadequate to prevent recurrence. Subsequent.to that event, and due to other actions that'IP has taken to enhance the corrective action program in general, CPS Procedure 1016.01, CPS

j. Condition Reports, has been revised to require a more structured approach l

to co,rrective actions. Specifically, the procedure now requires correctivo action plans to be approved by the appropriate management staff member with signature agreement of groups responsible for performing tasks in the corrective action plan. Further, Maintenance and Quality Engineering management personnel were briefed on this event and lessons learned.

Loose transmitter covers that were identified during the performance of MWRs D15049 and D15054 were retorqued to the required 200 inch-pounds !

during these checks. The scope of MWRs D15049 and D15054 included 206 environmentally qualified Rosemount transmitters. MWRs were initiated to-rework the four neck seals that were found broken. These MURs have been completed. The two transmitters that were found with missing conduit seals will be deleted from the equipment qualification program since they are associated with the steam condensing mode of the RHR system which is not used at CPS and this RHR operating mode is being deleted from the CPS design.

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. The current surveillance procedures reference the maintenance procedures i which require transmitter housing covers to be torqued to the required 1 200 inch. pounds any time they are removed (these covers may be removed

[ during transmitter calibration). In order to determine if the covers are ;

becoming loose over time, an MUR has been initiated to check the l- breakaway torque of-ten transmitters approximately three months after l

having been torqued to the required 200 inch-pounds. Five of these ,

transmitters will be selected from those that were found with a breakaway ;

torque less than 200 inch pounds during the performance of MWRs'D15049 and D15054'and the: remaining five will be selected from those that were found tight. Similarly, ten different transmitters will be checked approximately six months after having been torquod to the required-200 ;

inch. pounds. Further, a preventive' maintenance task has been initiated

- to verify the cover torque and neck seal integrity of the 206~

environmentally qualified Rosemount transmitters. The initial frequency for this preventive maintenance task is 18 months. . The results of the checks performed after.three months'and six months will be used, as ,

i - appropriate. to revise -the initial frequency of this preventive i

maintenance task. Additionally .an MWR has been. initiated to apply ,

i " Torque Seal" to the neck seals of the 206 environmentally qualified r l Rosemount transmitters. This will facilitate-future neck seal integrity inspections.

ANALYSIS OF EVENT This event is reportable under the provisions of 10CFR50.73(a)(2)(vii)

I because this condition affected the operability of at least one train cr channel in multiple systems required for safe shutdown of the-plant and +

to mitigate the consequences of an accident.

This event is not considered to be safety significant. Seven of the l thirteen inoperable transmitters identified (1B33-N024A and D, ILT-CM030, ILT-SM013, IE12-N062A, IPT-CM035, and 1PT-CM064) are required to be~

l operable by the' plant's Technical Specifications. -Four additional transmitters (1E12-N015B, 1PT-CH257, 1PT-IA081, and'1C41-N004) are required to be operable in order to satisfy the requirements of Regulatory Guide 1.97 for post-accident monitoring capability. The remaining two transmitters (1PDT-HC052 and 1LT-CH260D) are provided for monitoring of safety-related systems. Failure.of these thirteen transmitters alone would not have prevented any safety function from being performed. Based upon the results-of the' inspections performed in February 1990, redundant instrumentation or instrumentation of other parameters for fulfilling each of these safety functions remained available.

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ven* #**MP iiii2 Clinton Power Station o l5 yo go yo dg { 6g l 90 O0 0l6 y O'; 0l 3 g or 0l 7 mi a -* w =. -mc e mew nn s The length of time _ that this condition had existed is indeterminate. The affected transmitters.were not required to be operable per the plant's Technical Specifications at the time these conditions were identified. -

Operability of.the 206 environmentally qualified Rosemount transmitters ,

was restored prior to.startup from the March 1990 plant outage.. (

ADDITIONAL INFORMATION The thirteen environmentally qualified' transmitters -identified above are model 1153 transmitters manufactured by Rosemount. .Inc.

CPS has not previously reported inoperability of Rosemount 1153 transmitters due to loose housing covers, or broken neck seals.

For further information regarding this event, contact T. R. Chitester, ,

Director-Design and Analysis Engineering, at (217) 935-8881, extension '

, 3981.

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Dear Sir:

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