05000461/LER-1996-016, :on 950402,residual Water Observed Covering Portion of Disc/Seat Area.Caused by Plant Design Not Allowing Complete Draining of FW Lines.Drain Valves Installed on Bottom of Isvs & Rev of Test Procedures

:on 950402,residual Water Observed Covering Portion of Disc/Seat Area.Caused by Plant Design Not Allowing Complete Draining of FW Lines.Drain Valves Installed on Bottom of Isvs & Rev of Test Procedures

ML20137J885
Person / Time
Site:	Clinton
Issue date:	03/27/1997
From:	Rohrscheib R ILLINOIS POWER CO.
To:
Shared Package
ML20137J861	List: 05000461/LER-1996-016, :on 950402,residual Water Observed Covering Portion of Disc/Seat Area.Caused by Plant Design Not Allowing Complete Draining of FW Lines.Drain Valves Installed on Bottom of Isvs & Rev of Test Procedures 05000461/LER-1996-016-01, Forwards LER 96-016-01:re Residual Water Covering Portion of Disc/Seat Area During Testing Due to Design Not Allowing Complete Draining Results in Invalid Local Leak Rate Testing of Feedwater Containment Isolation
References
LER-96-016, LER-96-16, NUDOCS 9704040172
Download: ML20137J885 (4)

LER-1996-016, on 950402,residual Water Observed Covering Portion of Disc/Seat Area.Caused by Plant Design Not Allowing Complete Draining of FW Lines.Drain Valves Installed on Bottom of Isvs & Rev of Test Procedures

Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2)(i) 10 CFR 50.73(a)(2)(viii) 10 CFR 50.73(a)(2)(ii) 10 CFR 50.73(a)(2)(x) 10 CFR 50.73(a)(2)(iii) 10 CFR 50.73(c)(2)(v) 10 CFR 50.73(a)(2)(vii), Common Cause Inoperability 10 CFR 50.73(a)(2)(1)
4611996016R00 - NRC Website

text

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NRC FORM 366 U.S. NUCLEAR REZULATORY COMM2SiON APPROVW SY OMS No.3160 4104 (4-95)

ExnRa$ Ott32cs i

ESTIMATED BURDEN PER RESPONIE TO COMPLY WITH TH18 MANDATORY sNFORMATION COLLECTION REOUEST: 60.0 HRS.

REPORTED LESSONS LICENSEE EVENT REPORT (LER)

LEARNQ ARE INCORPORATQ INTO THE UCENSING PROCESS AND FED BACK TO INDUSTRY. FORWARD COMMENTS REGARDING BURDEN ESTIM ATE TO THE INFORMATION AND RECORDS MANAGEMENT BRANCH (T-a F331, U.$.

NUCLEAR REGULATORY COMMISSION. WASHINGTON. DC 206664001, AND (see reverse for required number of TO THE PAPERWORK REDUCTION PROJECT (3160-0104). OFFICE OF digits /choracters for each block)

MANAGEMENT AND SUDGET. WASHINGTON. DC 20603.

F AC8UTY NAME (1)

DOCKET NUMBWL(2)

PAOg (33 Clinton Power Station 05000461 1 OF 4 TITLE It!

R:sidual Water Covering Portion of Disc / Seat Area During Testing Due to Design Not Allowing Complete Draining Results in invalid Local Leak Rate Testing of Feedwate Containment Isolation Valves EVEllT DATF 151 LER Ni M ER181 F*rPoitT DATH 171 OTHER FACit ITIES INV SLVED (St MONTH DAY YEAR YEAR sEoVEN TiAL Revision 90 NTH DAY YEAR FACiuTY NAME DOCKET NUMBER NUMBER NUMSER None 05000 04 02 95 96 016 01 03 27 97

" "^"'

None 05000 OPERATING THIS REPORT IS SUBMITTED PURSUANT To THE REQUIREMENTS oF 10 CFR S: (Check one or rnore) (11)

MODE 19) 5 20.2201(b) 20.2203(a)(2)(v)

X 50.73(a)(2)(i) 50.73(a)(2)(viii)

POWER 20.2203(a)(1) 20.2203(a)(3)0) 50.73(a)(2)(ii) 50.73(a)(2)(x)

LEVEL (10) 000 20.2203(a)(2Hi) 20.2203(a)(3)(ii) 50.73(a)(2)(iii) 73.71 j

20.2203(aH2Hii) 20.2203(a)(4) 50.73(aH2Hiv)

OTHER 20.2203(aH2)hii) 50.36(C)(1) 50.73(c)(2)(v)

Specify in Abstract below or in NRC Fonn 366A 20.2203(aH2Hiv) 50.36(c)(2) 50.73(a)(2)(vii)

EICENBEE CONTACT FOR THis LEp (121 NAME TELEPHONE NUMBER (incluse Area Codel R.

G.

Rohrscheib, Local Leak Rate Testing Coordinator (217) 935-8881, Extension 3571 COMPLETE ONE LINE FOR EACH COMPONENT FAlt.URE DESCRIBED IN THIS REPORT (13) i

CAUSE

SYSTEM COMPONENT MANUFACTURER RE PORTABLE

CAUSE

SYSTEM COMPONENT MANUFACTURER REPORTABLE TO NPRDS n

SUPPLEMENTAL REPORT EXPECTED (14)

EXPECTED MONTH DAY YEAR SUBMISSION DATE (15) l YES X

NO tif yes, complete EXPECTED SUBMISSION DATE).

l ABSTRACT (Limit to 1400 spaces,i.e., approximately 15 single-spaced typewritten lines) (16)

During repair of an A loop reactor feedwater (FW) containment isolation valve (ISV) which failed local leak rate testing, plant personnel observed residual water in the body of the valve covering a portion of the disc / seat area and concluded that the valve was probably leak rate tested in that configuration during the current and a previous refueling outage. Performing the air leakage rate test with water covering a portion of the disc / seat area made the test invalid and does not meet the primary containment leakage rate testing and the total secondary containment bypass leakage rate testing provisions of Technical Specification (TS) Surveillance Requirements. The B loop FW ISV was also susceptibia to containing residual water covering the disc / seat area during leakage rate testing. The cause of this event is attributed to original plant design which did not allow complete draining of the FW lines.

Corrective action includes installing drain valves on the bottom of the ISVs to allow them to be drained, revising test procedures, and reviewing other containment penetrations for similar water draining issues.

9704040172 970327 PDR ADOCK 05000461 S

PDR NRC FORM 366 (4-95)

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NRP FORM 366A U.S. NUCLEAR REsULATORY COMMISSION j

(1 95)

LICENSEE EVENT REPORT (LER) i j

TEXT CONTINUATION j

FAest fTY M

• fil DocKFT LER Nt " ""It011 PAGE (31 YEAR SEQUENTIAL maim NUMBfR i

Clinton Power Station 05000461 96 016 01 2

OF 4

1 TEXT (If more space is required, use additional copies of NRC form 366A) (11)

DESCRIPTION OF EVENT

1 On October 24, 1996, the plant was in Mode 5 (REFUELING) with the reactor [RCT) coolant tcmperature being maintained between 80 and 90 degrees Fahrenheit (F) and pressure atmospheric. The sixth refueling outage (RF-6) was in progress and plant personnel were preparing to repair reactor feedwater (FW) system [SJ) loop "A" containment isolation valve (ISV) 1B21-F032A of containment penetration [ PEN) 1MC-009 because it failed to meet local losk rate testing (LLRT) requirements.

(The failure of the ISVs in containment penetrations 1MC-009 and IMC-010 to meet LLRT requirements is reported in Licensee Event J

R: port 96-013.)

At about 0015 hours1.736111e-4 days <br />0.00417 hours <br />2.480159e-5 weeks <br />5.7075e-6 months <br />, while disassembling ISV 1B21-F032A, maintenance personnel observed 1

w:ter in the body of the valve covering a portion of the disc / seat area and notified their cupervision of that observation.

On October 31, 1996, at about 1155 hours0.0134 days <br />0.321 hours <br />0.00191 weeks <br />4.394775e-4 months <br />, plant engineering personnel determined that the l

ISV was probably leak rate tested with some amount of residual water covering a portion of ths disc / seat area during performance of the periodic leakage rate testing on October 16, 4

1996, in the current refueling outage and during acceptance testing on April 10, 1995 in j

ths fifth refueling outage (RF-5).

The Operations shift supervisor was notified of the

~

condition at about 1230 hours0.0142 days <br />0.342 hours <br />0.00203 weeks <br />4.68015e-4 months <br />. Condition report 1-96-10-446 was initiated to track an ovaluation of the cause and corrective action for the condition. On April 10, 1995, the plcnt was in ' ode 5 and reactor coolant temperature was about 98 degrees Fahrenheit and prcosure was atmospheric.

j I

American National Standard ANSI /ANS 56.8-1994, " Containment System Leakage Testing j

R:quirements," requires that systems containing water during normal operation but not docigned to be water filled following a design basis accident, shall be drained to expose the barrier under test to the test medium. Therefore, performing the air leakage rate tests with water covering a portion of the disc / seat area makes the tests invalid, and does l not meet the primary containment leakage rate testing provisions of Technical Specification (TS) b,crveillance Requirement (SR) 3.6.1.1.1 and the total secondary containment bypass 1sakage rate testing provisions of SR 3.6.1.3.8.

Th3 condition of residual water covering a portion of the disc / seat area during leak rate tacting also applies to FW loop "B" ISV 1B21-F032B.

ISV 1B21-F032B of containment pcnetration 1MC-010 was tested in the same manner as ISV 1B21-F032A, on October 15, 1996, during the current refueling outage, and on April 2, 1995, during acceptance testing in RF-5.

On April 2, 1995, the plant was in Mode 5 and reactor coolant temperature was about 88 degrees Fahrenheit and pressure was atmospheric.

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 th2 start of this event to the extent that their inoperable condition contributed to this Ov3nt.

eU.S. NUCLEAR RE2ULATORY COMMISSION I4 95)

LICENSEE EVENT REPORT (LER)

TEXT CONTINUATION FactiITV NAM fil DocKFT LER NI-CR fill PAGF (3)

YEAR SEQUENTIAL NUMRrR Clinton Power Station 05000461 96 016 01 3

OF 4

TEXT lit more space is required, use additional copies of NRC form 366A) (11l 4

i

CAUSE OF EVENT

Th3 cause of this event is attributed to the plant's original design which did not allow complete draining of the valves.

Investigation of the cause of this event identified that i

th3 segment of the feedwater lines that penetrate the containment are sloped at about 0.5 d:grees from the inboard ISVs (1B21-F010A and 1B21-F010B) to the outboard ISVs (1821-F032A cnd 1821-F032B) in accordance with plant design, resulting in water being trapped by the outboard ISVs.

Valves used to drain the leak rate test volume do not drain the 1B21-F032A cnd 1B21-F032B valves sufficiently to expose the complete disc / seat areas to the test medium.

Previous as-found leakage rate testing of the 1B21-F032A and 1B21-F032B valves is not effected by this event since that testing identified unacceptable leakage rates, gross leckage and/or inability to pressurize the test volume.

Previous leakage rate testing cceepting the valves is only adversely affected for testing performed during RF-5.

Significant maintenance activities have been performed on both the 1B21-F032A and 1821-F032B valves during every refueling outage completed to date.

Prior to RF-5, all testing accepting the valves or testing performed following maintenance was performed with the test volume adequately drained to expose the complete disc / seat area to the test medium (any y

racidual water was removed during maintenance).

During RF-5, following the unacceptable as-found leakage rates, the leakage rate testing j

mithod for ISVs 1B21-F032A and 1B21-F032B was revised in ar. effort to use flow to seat the velve disco during the draining process. The revised test method was referred to as the "w;tted condition". Using the revised test method, water was introduced into the test volume in preparation for the test, then the water was drained to allow the ISV to shut with reverse FW system flow. The draining completed using the revised test method did not drain the test volume to expose the complete disc / seat area to the test medium.

Tho slight slope of the FW lines and potential to trap water in the bottom of ISVs 1B21-F032A and 1B21-F032B were not recognized by personnel responsible for developing and implementing the site 10CFR50, Appendix J, Type C testing program during development of the tact procedure.

Following as-found testing of ISVs 1B21-F032A and 1B21-F032B during RF-5, and during preparations to repair the valves, CPS personnel observed residual water in the bottom of tha valves. However, at that time, the water was thought to be a result of an incorrect lineup of drain valves that prevented complete drainage of the test volume.

The residual weter was not associated with a piping line design issue.

CORRECTIVE ACTION

A new drain valve, 1B21-F518A, was installed on the bottom of ISV 1B21-F032A in accordance with Engineering Change Notice (ECN) 29920 to allow the ISV to be drained for proper leak

)

rete testing. A new drain valve, 1B21-F518B, was installed on the bottom of ISV 1B21-F032B in accordance with ECN 29921 to allow that ISV to be drained for proper leak rate testing.

'e

.U.S. NUCLEAR RE;ULATORY COMMISSION (4 95)

LICENSEE EVENT REPORT (LER)

TEXT CONTINUATION FAcilITV NAME fil DOCKFT LER NUMRFR idi PAGE 131 YEAR SEQUENTIAL W S*"

NUMBFH Clinton Power Station 05000461 96 016 01 4

OF 4

TEXT ll1more space is required, use additionst copies of NRC form 366A) l11)

Surveillance test procedures for leakage rate testing ISVs 1B21-F032A and 1B21-F032B, CPS No. 9861.02D002, "LLRT Data Sheet for 1MC009," and CPS No. 9861.020003, "LLRT Data Sheet for 1HC010," have been revised to include new drain valves IB21-F518A and 1B21-F518B.

Other containment penetrations that are subject to 10CFR50, Appendix J, Type C testing will b3 reviewed to ensure that a test volume draining issue similar to this event does not sxist.

ANALYSIS OF EVENT

This event is reportable under the provisions of 10CFR50.73(a)(2)(1)(B) due to the failure to meet the leakage rate testing provisions of TS SR 3.6.1.1.1 and SR 3.6.1.3.8.

An assessment of the safety consequences and implications of this event identified that this event was not nuclear safety significant.

ISVs IB21-F032A and IB21-F032B are required to close to isolate the containment in the ovant of a Loss of Cooling Accident (LOCA).

A valid leak rate test was not performed for ths valves during RF-5 for fuel cycle 6 operation due to water covering a portion of the dicc/ seat areas of the valves during the RF-5 LLRT.

The as-left leakage rate for valve 1B21-F032A during the RF-5 testing was 1100 standard cubic centimeters per minute (secm) cnd the as-left leakage rate for valve 1B21-F032B during RF-5 was 900 secm. Although the co-left leakage rates are not conservative due to water covering a portion of the valve disc / seat areas, the leakage rates are still extremely low, indicating tight, well repaired velves, in good working order.

During an accident scenario, the feedwater lines will initially be filled with water. Therefore, the water trapped in front of the valve seats during the RF-5 leak rate testing, while it may have produced non-conservative test recults, would have been more closely representative of post-accident conditions and would not have impeded the valves from performing their safety function in an accident situation.

ISVs 1B21-F032A and 1B21-F032B did not meet Technical Specification provisions for leakage rate testing during fuel cycle 6.

ISVs 1B21-F032A and 1821-F032B were tested and accepted with some water covering the dise/ seat areas on April 10, 1995, and April 2,

1996, roepectively. This event was discovered on October 24, 1996.

ADDITIONAL INFORMATION

Ranctor feedwater ISVs IB21-F032A and 1B21-F032B are 20-inch, air assisted, non-slam type tilting disc check valves, model number 15204, manufactured by the Anchor Darling Valve Company.

On the basis of the discussion provided in the ANALYSIS OF EVENT portion of this report, Illinois Power does not consider the invalid leakage rate testing to be indicative of ISV

component failures

Clinton Power Station has not reported similar events discussing invalid testing caused by plent design in recent history.

For further information regarding this event, contact R. G.

Rohrscheib, Local Leak Rate Tacting Coordinator, at (217) 935-8881, extension 3571.-