ML19308B155

AO-269/74-10:on 740621,gaseous Release Occurrence During Letdown Storage Tank Sampling.Caused by Sampling Sys Leak. Leak Test Performed & Necessary Mods to Be Instituted

ML19308B155
Person / Time
Site:	Oconee
Issue date:	07/01/1974
From:	DUKE POWER CO.
To:
Shared Package
ML19308B151	List: ML19308B150 ML19308B155
References
NUDOCS 7912130808
Download: ML19308B155 (3)

Text

-

(.

m t DuxE POWER COMPANY itegulatory Docket File ~==s - a

>

• 4aa SouTu Cucacu STarzT, CHAR 1DTTE, N. C. 38201 A. C. Tu r es se..o. vicc P.c..oc., P.o. Box cive

==,c,.v.....

July 1, 1974 Mr. Angelo Giambusso Deputy Director for Reactor Projects Directorate of Licensing Office of Regulation U. S. Atomic Energy Commission Washington, D. C. 20545 Re: Oconee Unit 1 Docket No. 50-269

Dear Mr. Giambusso:

Pursuant to Sections 6.2 and 6.6.2 of the Oconee Nuclear Station Technical Specifications, please find attached Abnormal Occurrence Report A0-269/74-10.

Very truly yours,

A. C. Thies ,- g 's

'- t

,.P .

' '\'

ACT:vr .' ' 2 '^

,b Attachment ~/2: 4 Y

' O(fr 'k?h

~ \

cc: Mr. Norman C. Moseley  : 5,f 't

'. h b. ISf

'%::M g~ 9l

+ ,  % w.

79121308C8

s. s DUKE POWER COMPAh"I OCONEE UNIT 1 Report "o.: AO-269/74-10 Report Date: July 1, 1974 Occurrence Date: June 21,1974 Facility: Oconee Unit 1 Identification of Occurrence: Gaseous release during LDST sampling Conditions Prior to Occurrence: Steady-state operation at 100 percent power Description of Occurrence:

On June 21, 1974, Oconee Units 1 and 2 were at 100 percent power. After a technician obtained a sample from the letdown storage tank (LDST) gas space, radiation monitors in the Auxiliary Building alarmed or indicated higher-than-normal levels. The personnel assembly alarm was sounded and the Auxiliary Building was evacuated. Valves in the Unit 1 waste disposal sample hood were closed and the Izak apparently stopped. Soon afterwards the radiation levels returned to normal and the Auxiliary Building was cleared for entry.

Regulatory Operations, Region II, was verbally notified of the occurrence on June 21, 1974.

Designation of Apparent Cause of Occurrence:

The occurrence resulted, following the correct, routine sampling of the LDST, due to leakage from the sampling system. Gas from the sampling system is discharged into the Gaseous Waste Disposal System (GWD) as shown in the attached figure. This piping configuration apparently allowed gaseous activity to leak around the shaf t of the waste gas exhauster into the Auxiliary Building.

Analysis of Occurrence:

The amount of radioactive material released to the atmosphere was calculated based on changes in volume and pressure in the LDST and assuming that all the material that left the LDST was released to the atmosphere. It was calculated that a naximum of 144 Ci was released; 99 percent of this activitzwasattributedtoXe-133. The release rate was approximately -2 1 x 10 - Ci/see, which is 13 percent of the maximtn release rate of 8.4 x 10 Ci/see per Technical Specification 3.10.3. The maximum exposure to any one man was 25 mrem; as read from the dosimeter of the technician involved. A whole body count showed that the technician had absorbed 0.014 pC1 of Xe-135 and 0.416 pCi of Xe-133. Because the maximum release rate was not exceeded

4 i

2-and personnel exposure was less than occupational . limits, it is concluded the occurrence did not adversely affect the safe operation of the unit or the health and safety of the public.

Corrective Action:,

A leak test will be performed on the sampling system to verify that gas did.

indeed leak from the waste gas exhauster. Necessary modifications will be

, instituted prior to returning the sampling system to service.

.I l

l 1

c - . .-, , ,

. , . . . _ . _ _m e . -

7

( D t

e

. Tc l)lJZ T VE tJT A

e O

TQ 6 tu D - 7 AL y Wasr e gas E xan u srs.R

< LDST GAS SA M PL E ZrNE t

G v)D -6 f) 1 s

l y: \