ML20084C623

AO 251-74-8:on 740627,0701 & 02,boron Injection Tank Boron Concentration Found Below Tech Specs Limit.Caused by Insufficient Recirculation Coupled W/Minor Leakage. Investigation Continuing

ML20084C623
Person / Time
Site:	Turkey Point
Issue date:	07/05/1974
From:	Schmidt A FLORIDA POWER & LIGHT CO.
To:	Oleary J US ATOMIC ENERGY COMMISSION (AEC)
Shared Package
ML20084C609	List: ML20084C608 ML20084C623
References
AO-251-74-8, NUDOCS 8304080127
Download: ML20084C623 (4)

Text

c.o. tax mo mm, uc:m A nm

(

O)

\ LJ (U %,

v* -

. 1, [

/ ..

July 5, 1974 b l ,~

a l b! r . John F. O' Leary, Director . \.1 Di rectorate of Licensing Ci Of fice of Regula tion , -

U. S. Atomic Energy Commission ' '

Washington, D. C. 20545 '

Dear bir. O' Leary:

l ABNORMAL OCCURRENCE No. 251-74-8 JULY 5, 1974 OCCURRl!NCE DATE. JUNE 27, 1974; JULY 1, 1974; JULY 2, 1974 TURKEY POINT UNIT NO. 4 BORON 1NJECTION TANK HORON CONCENTRATION BELON LIMl'1ING CONDITION FOR OPERATION A. CONDITION PRIOR TO OCCURRENCE Ih: TC'iCl^,7 iJa:, in soniine pi nw r iipo rn r i nn nr m ; p e t-te r .

B. DESCRIPTION OF OCCURRENCE l At 1:00 p.m. on June 27, 1974, the routine boron analysis of the l boron injection tank (BIT) contents was completed and the re-l

' sults indicated a boron concen t ration of 19,300 ppm. This is below the 20,000 ppa lower Technical Specification limit. An additional sample was analyzed and it confirmed the low concen-tration. At this time a reactor shutdoun was commenced and the boron injection tank was lined up with the boric acid storage tank so that the contents of the BIT tould be recirculated to i

l bring the boron concentration to a value within the allowable operating limits. However, when reci rculation was initiated.

l flow could not be verified because the flowmeter in the recir-culation line was inoperable. Even though flow could not be verified recirculation was still attempted. At approximately 30 minutes from the start of recirculation, a sample was taken l

which showed the concentration to be 20,100 ppm. Even though this is within the allowable limits, the contents of the BIT continued to be recirculated. One hour a f ter the fi rs t sample was taken a second sample showed the concentration to be 20,300 PPM-r .-

(}')

)'

LI f.'

%' /

L, ,-[ / .;

.o 8304080127 740711 /

PDR ADOCK 05000251 I S PDR QpI. MT REGIO -

y

(D 0

Mr. John F. O ' IMIt ry

-Page ? -

July 5, 1974 For three consecutive days, the boron concentration in the boron injection tank remained within allowable limits. IIou-ever, at 3:30 p.m. on July 1, 1974, a sample taken frem the boron injection tank indicated a boron concentration of 19,600 ppm. Another sample was taken and it verified the low concentration. At this time a reactor shutdown was initiated. Even though recirculation flow could not be verified because the flowmeter was still inoperable, the contents of the boron injection tank were recirculated with the contents of the boric acid storage tank. At 3:45 p.m.,

. 15 minutes after the recirculation was initiated, another sample was taken and indicated a boron concentration of 20,000 ppm.

The third occurrence was on July 2, 1974. At 10:30 a.m.,

the contents of the boron injection tank were again sampled and indicated a boron concentration of 19,400 ppm. Another sample was taken and again verified the low concentration.

Once again a reactor shutdown was commenced and the contents of the boron injection tank were recirculated to return the boron concentration to allowable limits. Iloweve r , 30 minutes after the start of recirculation another sample was taken which indicated a baron concentration of 19,500 ppm. To deter-m uu li tMs was i c,,. wen ta tive o f thc concentra tion la the boron injection tank, a sample was also taken from the suction side of the tank which is located at the bottom. This sample indicated a concentration of 21,000 ppm.

Further attempts at recirculating the contents of the boron injection tank via the normal method failed to increase the concentration. At this point it was decided to connect the discharge of the boron injection tank to the boric acid batching tank using temporary connections. With this connection, the B1T contents could be recirculated through the boric acid tanks via the batching tank. Recirculating the contents of the boron injection tank via this method successfully increased the boron concentration. At 7:00 p.m., another sample was taken which indicated a boron concent ra tion of 20,800 ppm.

C. CAUSE OF OCCURRENCE The investigation to determine the cause of the occurrence has revealed that the dilution is due to i nsu f fici en t recir-culation coupled with minor inleakage. The contents of the boron injection tank could not be sufficiently recirculated because of a blocked or partially blocked recirculation return line to the boric acid storage tank.

~

Mr. JohnF.O'LOrr O I! age 3 '

July 5, 1974 ,

D. ANALYSIS OF Tile OCCURRENCE The role of the boron injection tank is to provide a source of negative reactivity to alleviate the consequences ofThe thesafety post-ulated steam break accident described in the FSAR.

analysis is conservative in that credit is only taken for the amount of boron in the boron injection tank itself and no credit is taken fcr the amount of boron-in the safety injection system piping. In addition, the actual rate of boron injection, in the unlikely event of a steam break, would be greater than utilized in the FSAR because actual safety injection flow rates would be higher than those analy cd in the FSAR. These factors

~

coupled with the amount of dilution that occurred indicate that the consequences of a steam line break would have been within the limits presented in the FSAR. Therefore, neither reactor safety nor the health and safety of the public were jeopardized by this occurrence.

E. CORRECTIVE ACTION The immediate corrective action taken following each occurrence consisted of: 1) initiating an orderly reactor shutdown, and

2) initiating routine recirculation of the contents of the boron injection tank through one of the boric acid storage tanks toHow-return the bcron concentration to within allowable limits.

ever, f oli o. ling edLit vcLui t unu. Lhc hGrG;i cOncOntrOtlen '*? F returned to within allowable limits prior to reaching cold shut-down and the reactor was returned to normal power operation.

Since the first occurrence, the sampling of the boron injection-tank was increased to once per day, which will continue until it has been determined that no further dilution is occurring.

The investigation to determine where the blockage in the recir-culation return line to the boric acid storage tank is located is continuing. Until the blockage has been found, the contents of the boron injection tank will be recirculated by lining up the suction of the boron injection tank to one of the boric acid storage tanks and discharging the boron injection tank to the batching tank. The batching tank will then be pumped to the boric acid storage tank.

The permanent corrective action will consist of: 1) replacing the flowneter in the recirculation line and assuring that any further failure is promptly investigated and corrected, and

2) eliminating the blockage in the recirculation line. As long as the contents of the boron injection tank are sufficiently recirculated, any minor inleakage into the tank will not result in diluting the baron concentration.

k

Mr. John F. O'L ry

s. Page 4 July 5, 1974 i I

{ In addition we are performing an ev$1uation of the method by j which the boron inj te tion tank is normally recirculated. The I i results of this evaluation should provide an improved nethod j of sanpling the boron injection tank te obtain a more repre-

} sentative saaple of the tank contents.

1 i F. FXILURii DATA i

l This is the first abnormal occurrence at Turkey Point resulting l from a blockage in the recirculation line.

Very truly yours, I , g

,&ffg,$ku~'dh' i A. D. Schmidt Director of Power Resources f Dh'R/ kaw 1

i cc: Mr. Norman C. Moseley j Jack R. Newman, Esquire i

J G

i i

I I

i l

l )

l l

l i

,,m ,,, , , _ . . , ,. , ,_ , _ _ , _ . . , , , _ , _ , ,, , , _ _ _ _ _ , . , , . , , , _