ML19347D590

LER 81-021/03L-0:on 810217,boron Injection Tank Found to Contain Boron Concentration Below Tech Spec Limit.Caused by Leak in Check Valve in Boric Acid Supply Line to Blender 2-CH-155,allowing Primary Grade Water to Backflow

ML19347D590
Person / Time
Site:	North Anna
Issue date:	03/18/1981
From:	Cartwright W VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML19347D589	List: ML19347D588 ML19347D590
References
LER-81-021-03L, LER-81-21-3L, NUDOCS 8103260760
Download: ML19347D590 (3)

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LICENSEE EVENT REPORT U.S. NUCLEAR REGULATORY CGMMISSION CONTROL BLOCK / / / / / / / (1) (PLEASE PRINT OR TYPE ALL REQUIRED INFORMATION)

/0/1/ /v/A/N/A/S/2/ (2) /0/0/-/0/0/0/0/0/-/0/0/ (3) /4/1/1/1/1/ (4) / / / (5)

LICENSEE CODE LICENSE NUMBER LICENSE TYPE CAT 0/1/ RE 0 'R [L/ (6) /0/5/0/0/0/3/3/9/ (7) /0/2/1/7/8/1/ (8) /0/ 3/1/8/8/1/ (9)

DOCKET NUMBER EVENT DATE REPORT DATE EVENT DESCRIPTION AND PROBABLE CONSEQUENCES (10)

/0/2/ / On February 17, 1981, while operating at 100% power, the Boron Injection Tank /

/0/3/ / (BIT) was sampled and found to contain a boron concentration below the /

/0/4/ / Technical Specification limit of 20,000 pps. With the BIT only slightly below /

/0/5/ / the limit at 19,499 ppm boron it would still have performed its intended /

/0/6/ / function, as a result the health and safety of the general public were not /

/0/7/ /__ affected. This event is reportable pursuant to T.S. 6.9.1.9.b.

/0/8/ / /

SYSTEM CAUSE CAUSE COMP. VALVE CODE CODE SUBCODE COMPONENT CODE SUBCODE SUBCODE

/0/9/ /S/F/ (11) /E/ (12) /B/ (13) /V/A/L/V/E/X/ (14) /C/ (15) /A/ (16)

SEQUENTIAL OCCURRENCE REPORT REVISION LER/R0 EVENT YEAR REPORT NO. CODE TYPE NO.

(17) REPORT NUMBER /8/1/ [-/ /0/2/1/ [l/ /0/3/ /L/ /-/ [0/

ACTION FUTURE EFFECT SHUTDOWN ATTACHMENT NPRD-4 PRIME COMP. COMPONENT TAKEN ACTION ON PI).NT METHOD HOURS SUBMITTED FORM SUB. SUPPLIER MANUFACTURER

/X/ (18) /D/ (19) /Z/ (20) [Z/ (21) /0/0/0/0/ (22) /Y/ (23) /N/ (24) [N/ (25) /E/0/9/5/ (26)

CAUSE DESCRIliION AND CORRECTIVE ACTIONS (2/)

/1/0/ / Leakage past check valve 2-CH-155, located in the boric teid supply line to the /

/1/1/ / blender, allowed PG water to backflow and dilute the EIT via the recire line. /

/1/2/ / Tank chemistry was restored by batching boric acid to "C" BAST. 2-CH-155 will /

/1/3/ / be repaired during the next Mode 5 outage, in the interim, backflow through /

/1/4/ / the check valve is being isolated by closing the upstream flow control valve. /

FACILITY METHOD OF STATUS  % POWER OTHER STATUS /

ON DHCOM ESCRMM (32)

/1/5/ [E/ (28) /1/0/0/ (29) / NA / '30) [B/ (31) / Routine Sample Analysis /

ACTIVITY CONTENT RELEASED OF RELEASE AMOUNT OF ACTIVITY (35) LOCATION OF RELEASE (36)

/1/6/ /Z/ (33) /Z/ (34) / NA / / NA /

PERSONNEL EXPOSURES NUMBER TYPE DESCRIPTION (39)

/1/7/ /0/0/0/ (37) [Z[ (38) / NA /

PERSONNEL INJURIES NUMBER DESCRIPTION (41)

/1/8/ [0/0/0/ (40) / NA /

LOSS TYPE OF OR DAMAGE TO FACILITY (43)

DESCRIPTION

/1/9/ /Z/ (42) / NA /

PUBLICITY ISSUED DESCRIPTION (45) NR: USE ONLY

/2/0/ /N/ (44) / NA /////////////

NAME OF PREPARER W. R. CARTWRIGHT PHONE (703) 894-5151

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8103 26o 71629 .

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Virginia Electric and Power Company North Anna Power Station, Unit #2

Attachment:

Page 1 of 2 Docket No. 50-339 Report No. LER 81-021/03L-0 Description of Event On February 17, 1981, while operating at 100% power, the Boron Injection Tank (BIT) was sampled and found to contain less than the Technical Specifi-cation requirement of 20,000 ppm boron. Since the. BIT is continuously recir-culated with the boric acid storage tanks, the "C" storage tank was also out of spec. low on boron concentration. This event is contrary to T.S. 3.5.4.1,b and 3.1.2.8.a and reportable pursuant T.S. 6.9.1.9.b.

Probable Consequences of Occurrence 3

The boron injection tank contains a nominal 12-weight percent of concentrated boric acid solution (21,000 ppm boron) and is connected to the discharge of the centrifugal charging pumps. Upon actuation of a safety injection signal, the charging pumps provide the pressure and flow capacity necessary to inject the boric acid solution into the Reactor Coolant System (RCS) when the BIT isolation valves open. To prevent cold spots and stratification of boric acid within the tank during normal operation, the 'ontents of the boron injection tank are continuously recirculated with the boric acid storage tanks via a boric acid transfer pump.

With the boron concentration in the boron injection tank below the required limit of 20,000 ppa, a sufficient negative reactivity to coun-teract the increase in reactivity caused by RCS cooldown may not be provided during the injection phase following a main steamline break.

Because the BIT was still capable of performing its intended function with a boron concentration only slightly below the limit at 19,499 ppe, the health and safety of the general public were not affected.

Cause of Event A leaking check valve in the boric acid supply line to the blender (2-CH-155) allowed blender primary grade (PG) water to backflow via the recire line into the Boron Injection Tank diluting its contents.

Immediate Corrective Accion Boron Injection Tank chemistry was restored to within spec by batching boric acid to its assigned Boric Acid Storage Tank ("C" BAST).

Scheduled Corrective Action A maintenance report has been submittu to repair check valve 2-CH-155 during the next Mode 5 outage. In the mean time, backflow of PG water into the 5 7 is being isolated by closing the boric acid flow control valse.(FCV-2113A) directly upstream of the leaking checa valve.

Actions Taken to Prevent Recurreuce No further actions are required.

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Attachment:

Page 2 of 2 Generic Implications There are no generic implications associated with this event.