ML20029E470

LER 94-001-00:on 940412,discovered That Total Pressure Offset Constant in Error.Caused by Technician Error. Procedure Will Be Revised to Prevent recurrence.W/940512 Ltr

ML20029E470
Person / Time
Site:	Prairie Island
Issue date:	05/12/1994
From:	Richard Anderson, Hunstad A NORTHERN STATES POWER CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-94-001-02, LER-94-1-2, NUDOCS 9405180357
Download: ML20029E470 (5)

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Northem States Power Company 414 Nicollet Mall l Minneapolis, Minnesota 55401 1927 j Telephone (612) 330-5500  !

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May 12, 1994 10 CFR Part 50 l Section 50.73 U S Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555 PRAIRIE ISiAND NUCLEAR GENERATING PLANT Docket Nos. 50-282 License Nos. DPR-42 50-306 DPR-60 Inoperability of one Train of Post-Accident Containment Hydrogen Monitoring r

The Licensee Event Report for this occurrence is attached. In the report, we made one new NRC commitment:

The subject surveillance procedures will be revised to record as-left containment data explicitly, provide technicians better instructions on critical steps, and provide cautions in steps that could corrupt calibration constants.

Please contact us if you require additional information related to.this event. ,

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trp, Ande o Director Licensing and Management Issues c: Regional Administrator - Region III, NRC NRR Project Manager, NRC Senior Resident Inspector, NRC Kris Sanda, State of Minnesota Attachment

,n-9405180357 940512 PDR ADOCK 05000306

6 KRC FORM 366 U.S. BiUCLEAR REGULATORY CDutSSICN APPROYED BY (MB Wo. 3150-0104 (5 92) EXP!RES 5/31/95 ESTIMATED BURDEN PER RESPONSE TO COMPLY WITH THIS INFORMATION COLLECTION REQUEST: 50.0 HRS.

LICENSEE EVENT REPORT (LER) FORWARD COMMENTS REGARDING BURDEN ESTIMATE TO THE INFORMATION AND RECORDS MANAGEMENT BRANCH (MNSB 7714), U.S. NUCLEAR REGULATORY COMMISSION, (See reverse for required ruber of digits / characters for each block) WASHINGTON, DC 20555-0001, AND TO THE PAPERWORK REDUCTION PROJECT (3150 0104), OFFICE OF

[ MANAGEMENT AND BUDGET, WASHINGTON, DC 20503.

FACILITT KAME (1) DOCKET MUMBER (2) PAGE (3)

Prairie Island Nuclear Generating Plant U2 05000 306 1 OF 4 TITLE (4)lnaperability of One Train of Post-Accident Contairacnt Hydrogen Monitoring EVtWT DATE (5) I ER NtMBER (6) REPORT DATE (7) OTHER FACILITIES INVDtVED (8)

SEQUENTIAL REVISION FACILITY NAME DOCKET NUMBER MONTH DAY YEAR YEAR """ ^ "

NUMBER WUMBER Prairie Island U1 05000 282 04 12 94 94 --

01 --

00 05 12 94 0 0 OPERATING THIS REPORT IS SLMiNITTID PURSUANT TO THE Rf0VIRIMENTS OF 10 CFR i: (Check one or more) (11)

MUDE (9)

N 20.402(b) 20.405(c) 50.73(a)(2)(iv) 73.71(b) payg g 20.405(a)(1)(1) 50.36(c)(1) 50.73(a)(2)(v) 73.71(c)

LEVEL (10) 20.405(a)(1)(ii) 50.36(c)(2) 50.73(a)(2)(vil) OTHER 20.405(a)(1)(tii) X 50.73(a)(2)(i) 50.73(a)(2)(vi i i)( A ) (Specif y in 20.405(a)(1)(iv) 30.73(a)(2)(ii) 50.73(a)(2)(viii)(B) ",D*

nd 20.405(a)(1)(v) 50. 73( a)(2)( i i i ) 50.73(a)(2)(x) NRC Form 366A)

LICENSEE CONTACT FOR THIS L ER (12)

NAME TELEPHONE NUMBER (include Area Code)

Arne A Hunstad 612-388-1121 COMPLETE ONE llNE FOR FACH COMPONENT FAllURE OFSCRIBFD IN THIS REPORT (13)

CAUSE SYSTEM COMPOWENT MANUFACTURER CAUSE SYSTEM COMPONENT MANUFACTURER TO S g SUPPlf MTNTAL RFPORT EXPf CTED (14) EXPECTED MONTH DAY YEAR YE S S'JBMISSION No (if yes, com lete EXPECTED SUBMISSION DATE). DATE (15)

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

On April 12, 1994 an I&C Technician was performing a routine surveillance test of the Unit 2 containment hydrogen monitors. When taking as-found readings, the technician noticed that the containment pressure reading on Train B was significantly out of specification. The calibration constants were read, and it was then discovered that the Total Pressure Offset constant was in error. The technician entered the correct value, as directed by the procedure, and notified the system engineer. At the conclusion of the test, the technician and the system engineer reviewed the procedure and calibration card data. Based on review of previous surveillance data and discussions with several technicians, it was determined that the Train B hydrogen monitor had probably been inoperable ,

since March 15, when the monthly test had last been performed. The '

technician that performed the March 15 test apparently had made an erroneous keystroke while displaying containment data. After the Total Pressure Offset was read, the technician should have pushed the ENTER key to move on to the next calibration constant. Instead, it appears the technician pushed the NEW CONSTANT key inadvertently, and then when the ENTER key was pushed, the incorrect calibration constant was entered. i Procedures will be revised to prevent recurrence.  ;

i NRC FORM 366 (5 92)

CRC FORM 366A U.S. C3) CLEAR REEJLATQ3Y CDPMISSICJ APPROVED BY OMB CD. 3150-0104 (5-92) EXPIRES 5/31/95

, ESTIMATED BURDEN PER RESPONSE TO COMPLY WITH THIS INFORMATION COLLECil0N REDUEST: 50.0 HRS.

FORWARD COMMENTS REGARDING BURDEN ESTIMATE TO LICENSEE EVENT REPORT (LER) THE INFORMATION AND RECORDS MANAGEMENT BRANCH TEXT CONTINUATION (MNBB TM4), U.S. NUCLEAR REGULATORY COMMISSION, WASHINGTON, DC 20555-0001, AND TO THE PAPERWORK REDUCTION PROJECT (3150-0104), OFFICE OF MANAGEMENT AWD BUDGET, WASHINGTON, DC 20503.

FACILITY kAMF (1) DOCKET NtMBf R (?) LER NAMR (6? PAGE (3)

YEAR SEQUENTIAL REVISION NUMBER HUMBER Prairie Island Unit 2 05000 306 94 __ 91 __ 00 TEXT (if more space is rewired, use additional copies of NRC Form 366A) (17)

EVENT DESCRIPTIOli On April 12, 1994 Unit 2 was at 100% power. An Instrument & Controls Technician was performing routine surveillance procedure SP1226A, Containment Hydrogen Monitor Monthly Test. The procedure verifies that correct calibration constants are being used in the post-accident containment hydrogen monitor computer. When taking as-found readings, the technician noticed that the containment pressure reading on Train B was 42.1 atmospheres, significantly out of specification. A normal reading is 1.0 atmospheres. The as-found data were recorded. The calibration constants were read, and it was then discovered that the Total Pressure Offset constant had a value of 41.0. Comparison of the data against the results of the latest calibration revealed that the offset should have been

-0.0426. The technician entered the correct value, as directed by the procedure, and notified the system engineer. At the conclusion of the test, the technician and the system engineer reviewed the procedure and calibration card data to determine the reason for the incorrect calibration constant.

The vendor was consulted to assist in determining operability of the monitor. The vendor confirmed that an additional 41.0 atm of pressure would be added, offsetting actual measured containment pressure, so that indicated hydrogen concentration would be significantly lower than actual.

Based on a review of previous surveillance data and discussions with several technicians, it was determined that the Train B hydrogen monitor had probably been inoperable since March 15, 1994 when the monthly test had last been performed.

The technician that performed the March 15 test was also interviewed. The last step in the channel test is to verify that containment data are displayed normally. The technician completed this step, but then read the calibration constants again, which is incorrect. After the Total Pressure Offset was read, the technician should have pushed the ENTER key to move on to the next calibration constant. Instead, it appears the technician i pushed the NEW CONSTANT key inadvertently, and then when the ENTER key was l pushed, the incorrect calibration constant was entered. I i

CAUSE OF THE EVENT l The surveillance procedure is deficient in some areas. It is not clear about which data is required to verify operability. It could easily be l misconstrued that verification of calibration data is required in addition l to the containment data. Also, the procedure requires observation but not I

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• l I;RC FORM 366A U.S. RTJCLEAR REGULATG2Y CIM(ISSIC;I APPROVED BY CNB C:0. 3150-0104 (5-92) EXPIRES 5/31/95

' ESTIMATED BURDEN PER RESPONSE TO COMPLY WITH

. THIS INFORMATION COLLECTION REQUEST: 50.0 HRS.  !

FORWARD COMMENTS REGARDING BURDEN ESTIMATE TO I LICENBEE EVENT REPORT (LER) THE INFORMATION AND RECORDS MANAGEMENT BRANCH l TEXT CONTINUATION (MNBB 7714), U.S. NUCLEAR RECULATORY COMMISSION, WASHINGTON, DC 20555-0001 AND TO THE PAPERWORK REDUuTION PROJECT (31!IO0104), OFFICE OF MANAGEMENT AND BUDCET, WASHINGTON, DC 20503.

FACitITY NAMF (1) DOCETT WlMRTR (?) (ER MlMBER (6? PAGE (3)

YEAR SEQUENTIAL REVISION Prairie island Unit 2 NUMBER NUMBER 05000 306 94 __

oi __ 00 i

TLxi (If mere space is reauired, use additional cocies of WC Form 366A) (17) recording of as-left containment readings. l 1

Calibration data was corrupted when accessed improperly and not checked l afterwards. Accessing the calibration constants followed from a l misunderstanding of the verification requirements. The procedure could  !

have prevented the event that caused improper calibration constants to be l introduced had the procedure provided the technician more specific l direction on verification requirements, provided explicit cautions at certain key points in the procedure prior to accessing any calibration data, and recorded as-left containment data.

The installed equipment has some limitations that require careful censideration when maintaining the system. For example, calibration constants cannot be read directly without introducing the possibility of altering them.

ANALYSIS OF THE EVENT The event is reportable pursuant to 10CFR50.73 (a) (2) (1) (B) since one train of post-accident hydrogen monitoring was inoperable for more than 7 days, in violation of Technical Specification 3.15.A.1. Train B of Unit 2 post- l accident hydrogen monitoring was inoperable from March 15 to April 12, l 1994. Train A was operable throughout the period. Unit 1 was unaffected I by this event.

The error in Total Pressure Offset would have caused the hydrogen monitor to read lower percent volume of hydrogen than actual. The error varies with containment pressure, such that the hydrogen concentration read at low I containment pressure would be about 1/40th of actual and at high j containment pressure would be about 1/2 of actual. '

Recalibration of the monitors is required about 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> after the postulated accident. Recalibration would have corrected the error.

Venting of containment gases based on hydrogen concentration does not occur until at least 10 days after the accident. Likewise, operation of the hydrogen recombiners based on hydrogen concentration is not required until several days after the accident. For the above reasons, health and safety of the public was not affected.

CORRECTIVE ACTION The surveillance procedures will be revised to record as-left containment data explicitly, provide technicians better instructions on critical steps, and provide cautions in steps that could corrupt calibration constants.

This event will be reviewed by I&C engineers, supervisors, technicians and

e tRC FORM 346A U.S. 53UCLEAR REQJLATC2T C099t!SSICa APPROVED BY OMB to. 3150-0104 (5 92) EXPIRES 5/31/95

. ESilMATED BURDEN PER RESPONSE TO COMPLY WITH THis INFORMATION COLLECTION REQUEST: 50.0 HRS.

FORWARD COMMENTS REGARDING BURDEN ESilMATE TO LICENSEE EVENT REPORT (LER) THE INFORMATION AND RECORDS MANAGEMENT BRANCH (MNas 7714), u.S. NUCLEAR REGULATORY COMMIS$10N, TEXT CONTINUATION WASHINGTON, DC 20555-0001, AND TO THE PAPERWORK REDUCTION PROJECT (3150 0104), OFFICE OF MANAGEMENT AND BUDCET, WASHINGTON OC 20503.

FACillTY NAME (1) DOCKET NUMBER (2) LER WUMRTR (6? PAGE (3)

YEAR SEQUENTIAL REVISION NUMBER NUMBER Prairic Island Unit 2 4 4 05000 306 94 __ oi __ 00 TEXT (if more space is required, use additional copies of NPC Form 366A) (17) trainers.

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FAILED COMPONENT IDENTIFICATION None.

PREVIOUS SIMILAR EVENTS There have been no previous similar events reported at Prairie Island. As i followup to Unit 1 LER 93-003 describing instrument miscalibration, a generic review of I&C activities was done and several procedures were identified for potential enhancements to help prevent recurrence of such events. SP1226A was one of those procedures identified, but revisions had not been fully implemented.

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