05000339/LER-1980-072-03, /03L-0:on 801008 & 20,boron Injection Tank & Boric Acid Storage Tank Were Sampled & Found to Contain Boron Concentration Below Tech Spec Limit.Caused by Leakage Past Water Shutoff Valve.Valves Readjusted

/03L-0:on 801008 & 20,boron Injection Tank & Boric Acid Storage Tank Were Sampled & Found to Contain Boron Concentration Below Tech Spec Limit.Caused by Leakage Past Water Shutoff Valve.Valves Readjusted

ML19339B916
Person / Time
Site:	North Anna
Issue date:	11/03/1980
From:	Cartwright W VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML19339B915	List: 05000339/LER-1980-072, Forwards LER 80-072/03L-0 05000339/LER-1980-072-03, /03L-0:on 801008 & 20,boron Injection Tank & Boric Acid Storage Tank Were Sampled & Found to Contain Boron Concentration Below Tech Spec Limit.Caused by Leakage Past Water Shutoff Valve.Valves Readjusted
References
LER-80-072-03L-01, LER-80-72-3L-1, NUDOCS 8011100434
Download: ML19339B916 (3)

LER-1980-072, /03L-0:on 801008 & 20,boron Injection Tank & Boric Acid Storage Tank Were Sampled & Found to Contain Boron Concentration Below Tech Spec Limit.Caused by Leakage Past Water Shutoff Valve.Valves Readjusted

Event date:
Report date:
3391980072R03 - NRC Website

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U.S. NUCLEAR REGULATORY COMMISSION LICENSEE EVENT REPORT

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(PLEASE PRINT OR TYPE ALL REQUIRED INFORMATION)

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

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On October 8 and 20, 1980 while operating at 50% and 29% thermal power respec- /

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tively, the Boron Injection Tank and the units's Boric Acid Storage Tank ("C"

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BAST) were sampled and found to contain a baron concentration below the Tech- /

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nical Specification limit of 20,000 ppm.

Redundant systems vere operable and /

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had the required capability for reactor control. Therefore the health and

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safety of the general public were not affected.

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suant to T.S. 6.9.1.9.b.

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SYSTEM

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

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ACTION FUTURE EFFECT SHUTDOWN ATTACHMENT NPRD-4 PRIME COMP. COMPONENT TAKEN ACTION ON PLANT METHOD HOURS SUBMITTED FORM SUB. SUPPLIER MANUFACTURER [Ef (18) /Z/ (19) /Z/ (20) /Z/ (21) /0/0/0/0/ (22) [Y/ (23) /N/ (24) /A/ (25) /G/2/5/5/ (26)

CAUSE DESCRIPTION AND CORRECTIVE ACTIONS (27)

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The decrease in tank boron concentrations is believed to have resulted from

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leakage past a PG water shutoff valve to the suction of one of the boric acid /

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transfer pumps. The leakage acted to dilute the BIT solution which was on re- /

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cire with the "C" BAST. Each of the PG valves were adjusted to ensure complete /

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closure and upstream valves were closed to provide a double isolation.

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NRC USE ONLY

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

80I1-200 I

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h Virginia Electric and Power Company North Anna Power Station, Unit 2 Attachment: Page 1 of 2 Docket No.~50-339 Report No. LER 80-072/03L-0 l

Description of' Event On October 8 and 20,1980, while operating at 50% and 29% power respectively,.the-Boron Injection Tank (BIT) and "C" Boric Acid Storage Tank (BAST) were sampled and found to contain less than the Technical Specification requirement of 20,000 ppm boron. The applicable ACTION Statements were entered and the requirements observed. This event is contrary to T.S. 3.5.4.1.b and 3.1.2.8.a.2 and reportable pursuant to j

T.S. 6.9.1.9.b.

Probable Consequences of Occurrence 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 inlet isolation valves open.

To prevent cold spots and stratification within the tank during normal operation, the contents 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 ppm, a' sufficient negative reactivity to counter-.

act the increase in reactivity caused by RCS cooldown may not be.provided' i

during the injection phase following a main steamline break.-

Because redundant systems were operable _and adequate capability for reactor control was available at all times, the health and safety of the general public were not'affected.

Cause of Event

The decrease in tank boron concentrations is believed to have resulted from leakage past a PG water isolation valve to the suction of one of the boric acid transfer pumps. The inleakage of primary grade (PG) water diluted the contents of the BIT which was on recire with the "C" Boric Acid Storage Tank.

Immediate Corrective Action

1 At first, when.the cause was not known, the BIT was placed on recire with the "B" Boric' Acid Storage Tank and boric acid was batched to "C" Boric Acid Storage Tank until the boron concentration was within spec. Operations investigated and adjusted each of the boric acid transfer pump PG diaphram valves to ensure full closure. The upstream j

valves were also closed to provide a double isolation of the PG lines.

These actions appear to have corrected the problem since an acceptable boron concentration is~now being maintained.

t p

-.en.-7g p.

y-

,.%-y g-%e.-y-

..yA g.

4 Page 2 of 2 Scheduled Corrective Action To ensure correct boron concentrations, sample analysis of the BIT and "C" BAST will continue on a periodic basis.

Actions Taken to Prevent Reccurrence No further actions are required.

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

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