ML20084F644

AO 251-75-6:on 750422,during Valve & Steam Generator Maint, Containment Integrity Breached.Caused by Procedural Deficiencies.Administrative & Maint Procedures Will Be Revised

ML20084F644
Person / Time
Site:	Turkey Point
Issue date:	05/01/1975
From:	Schmidt A FLORIDA POWER & LIGHT CO.
To:	Rusche B Office of Nuclear Reactor Regulation
References
AO-251-75-6, NUDOCS 8304210209
Download: ML20084F644 (3)

Text

.-

P.O. SOX 3100 MIAM1, FLORIDA 33101

~ *t . .

O O u .

( i a.' w%-

, ' Jl Ji% ., d,.

! J La s~-.m i FLORIDA POWLR & LIGHT COWANY May 1, 1975 I

Mr. Benard C. Rusche, Director l .Of fice of Nuclear Reactor Regulation i U. S. Nuclear Regulatory Commission l Washington, D. C. 20555 I

Dear Mr. Rusche:

! ABNORMAL OCCURRENCE'NO. 251-75-6 l

MAY 1, 1975 l OCCURRENCE DATE: APRIL 22, 1975 TURKEY POINT UNIT NO. 4 BREACH OF CONTAINMENT INTEGRITY .

DURING REFUELING OPERATIONS A. CONDITIONS PRIOR TO OCCURREFCE The reactor was in refueling shutdown condition, reactor coolant temperature was approximately 105 F and the reactor vessel head was removed. The refueling cavity and the refueling canal were filled with borated water with a boron concentration of 2,180 ppm.

All requirements for refueling operations were satisfied and movement of a fuel assembly from the spent fuel pit to the reactor core was in progress.

B. DESCRIPTION OF OCCURRENCE Safety valve number RV-4-1403, located outside containment, was disassembled by maintenance personnel on April 22, 1975. The -,

safety valve seating surface was being lapped with.a lapping block. About the same time, maintenance personnel inside ,

containment were removing steam generator No. 4A secondary sidej manway. When the lapping block was removed.from the safety valve seat, about 11:45 A.M., April 22, 1975, a mixture of air and wat'er. j vapor was observed escaping from the safety valve. Maintenance * .

personnel notified the operators of this condition. . t

? -1 i -

Immediate operator action was to verify the main steam line valve .,

alignment to determine the source of the air and water mixture. '

The valve line-up was verified to be correct .so it was concluded; that the air and water mixture had been trapped in the horizonta'l-  ;

section of the main steam line after the main steam valves were !

~

closed. About the same time, operatingEpersonnel inside j l containment found that steam generator No. 4A secondary side man [-

way had been removed. As soon as it was recognized that containment-integrity had been breached by a flow path through the secondary system, the nuclear plant supervisor ordered refueling operations stopped at 12:30 P.M., April 22, 1975. -i 4 ,Q$2

~

8304210209 750501 PDR ADOCK 05000251 S

-. COPY SENr REGION [a ,-

.PDR HELPING DUILD - FLORID A" ' '

n ma CJ t

• 9 v .

Mr. Benard C. Rusche, Director Page Two May 1, 1975 Steam generator No. 4A secondary side manway was reinstalled and containment integrity reestablished before refueling operations resumed.

C. DESIGNATION OF APPARENT CAUSE OF OCCURRENCE After review, analysis, and evaluation, we concluded that procedure deficiencies were the cause of this occurrence.

Procedures involved did not require that containment integrity through the secondary must be established and maintained during refueling operations.

D. ANALYSIS OF OCCURRENCE i

During this occurrence, fuel handling operations were conducted under water with special fuel handling equipment. Continuous monitoring of reactor core conditions, containment environment gaseous and particulate samples, and background radiation levels would have detected off-normal conditions.

Fue'. handling incidents are analyzed and presented in the Turkey Point Unit Nos. 3 and 4 Final Safety Analysis Report (FSAR) using conservative assumptions. The inventory of noble gas radionuclides and the predominant halogen radionuclides in a fuel assembly were' evaluated and presented in the FSAR assuming 50 hours5.787037e-4 days <br />0.0139 hours <br />8.267196e-5 weeks <br />1.9025e-5 months <br /> for radioactive decay. At the time of this occurrence, the reactor had been subcritical about 520 hours0.00602 days <br />0.144 hours <br />8.597884e-4 weeks <br />1.9786e-4 months <br />. If a fuel handling incident had occurred, the inventory of noble gas radionuclides available for release from a fuel assembly would have been reduced by a factor of nine by radioactive decay.

Similarly, the halogen radionuclides would have been reduced by a factor of seven. Therefore, the calculated exposures presented in t-he FSAR would be reduced b,y the same ratios.

From the review, analyses, and evaluation of conditions during this occurrence, we concluded that neither reactor safety nor the health and safety of the public were jeopardized by this occurrence.

E. CORRECTIVE ACTION Adminstrative and maintenance procedures will be revised to specify that secondary system integrity must be established and maintained when maintenance work on secondary systems is performed during refueling operations.

~

-- O O Mr. Benard C. Rusche, Director Page Three May 1, 1975 F. FAILURE DATA This is the first abnormal occurrence report from Turkey Point Unit Nos. 3 and 4 involving breach of containment integrity during refueling operations.

Very truly yours,

~ L ,!_ # < t 2 6 --

• j.'EA.

Q D. Schmidt Vice President Power Resources VrC/dfl i

cc: Mr. Norman C. Moseley Jack R. Newman, Esquire 1

_ m - . - - - _ - - -