ML20085D133

Ao:On 730605,erroneous Indication of Containment Vessel Pressure Transmitter PI-950B Reported on Plant Trouble Ticket.Caused by Vent Valves Open to Environ.Plugs Installed in Valves

ML20085D133
Person / Time
Site:	Robinson
Issue date:	06/14/1973
From:	Utley E CAROLINA POWER & LIGHT CO.
To:	Oleary J US ATOMIC ENERGY COMMISSION (AEC)
Shared Package
ML20085D135	List: ML20085D133 ML20085D157 ML20085D167
References
NG-73-99, NUDOCS 8307200565
Download: ML20085D133 (2)

Text

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. .)NU J Carolina Power & Light Company k

June 14, 1973 t 50- 261 l

' FILE: NG-5212 NG-73-99 i

Mr. John F. O' Leary Directorate of Reactor Licensing y [

U. S. Atomic Energy Commission ., ,

i Washington, D. C. 20545 /  :

? . ll H. B. ROBINSON UNIT NO. 2 LICENSE DPR-23 ABNORMAL OCCURRENCE REPORT '

VIOLATION OF TECHNICAL SPECIFICATIONS t

Dear Mr. O' Leary:

In accordance with Paragraph 6.6.2.a. Technical Specifications, an abnormal occurrence which occurred on June 5, 1973, is herein reported.

With the reactor operating at 75% power an erroneous indication of PI-950B

' (Containment Vessel Pressure Transmitter) was reported'^on a plant trouble 4

ticket. The pressure transmitter which supplies the output to this indica-tor was checked and no pressure was evident although a monometer indicated 4 approximately 1 psig containment pressure.

A systematic leck check was begun from the transmitter to the con-tainment penetration and a leak check was also begun in the reverse direction.

-The investigation verified that three (3) 3/8-inch vent valves were open to the environment. These valves were closed and proper transmitter operation was restored. It was later determined that sometime during the refueling ,

outage the vent valves were opened to bleed pressure off the three lines to the transmitters and were never reclosed.

A Plant Nuclear Safety Committee Meeting was held on June 6, 1973, and it was their opinion that these valves being open constituted a Techni-cal Specification violation in three (3) areas:

(1) A Limiting Condition for Operation was' violated in i that containment integrity was not intact.

(2) A safety system probably would not have operated-

! 'at the designed setpoints.

i-(3) Procedural or administrative procedures were violated in that these valves were not listed on the valve line-

up check-off sheet. , f L* G\

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' . . .. O O . l l Mr. John F. O' Leary 2 June 14, 1973 k The safeguards system would have operated on a sudden pressure rise, but at a higher pressure than the setpoints due to some bleed off of pressure ahead of the pressure transmitters.

The three vent valves in question were not on the plant drawings.

This omission from the plant drawings resulted in the failure to include the valves on the check-off sheet.

CORRECTIVE ACTION f

1) The three (3) vent valve's have had plugs installed to prevent .

recurrence of this incident.  !

2) All valves on the system have been assigned numbers and are included on a check off sheet under the Post Accident Hydrogen Sampling System or GP-1E (Containment Integrity).

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3) The updating of present prints or draf ting of new prints, if j

needed, will be accomplished.

4) Other systems will be inspected for similar vent valves.

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It is the opinion of Carolina Power & Light Company that the s '

corrective action taken will prevent the recurrence of this incident.

Yours very truly, s -

~# [ p-E. . Vtley Vice-President Bulk Power Supply JMJ:DBW:pn ec: Mr. C. D. Barham Mr. B. J. Furr Mr. D. V. Menscer Mr. N. B. Bessac Mr. D. B. Waters ,

6 9

9 s.-

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