ML20086L184

AO 74-21:on 740411,pressure Switches PS-2-5-14C & PS-2-5-14D Found Inoperable.Caused by Sensing Line Not Delivering Proper Pressure Signal.Pressure Sensing Lines Traced Back to Turbine & Checked to Be Free of Obstruction

ML20086L184
Person / Time
Site:	Peach Bottom
Issue date:	04/21/1974
From:	Cooney M PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC
To:	Giambusso A US ATOMIC ENERGY COMMISSION (AEC)
References
AO-74-21, NUDOCS 8402070451
Download: ML20086L184 (2)

Text

.

0 0

• ' CD PHILADELPHIA ELECTRIC COMPANY

. es c) 2301 MARKET STREET /

PHILADELPHIA. PA.19101 8" f 9 '**'

(215) 841-4ooo g N l/

\4 ll-April 21,1974 lD; ... A)$

M Mr. A. Giambusso Deputy Director of Reactor Projects United States Atomic Energy Commission Directorate of Licensing Washington, D.C. 20545

Subject:

Abnormal Occurrence

Dear Mr. Giambusso:

The following occurrence was reported to Mr. R. A. Feil, A.E.C. Region I Regulatory Operations Office on April 12, 1974.

Writte.n notification was made to Mr. James P. O'Reilly, Region I Ranisla rn ry Onaca ti nns Of fica nn A n ri l I ?; IQ7h. in aceneciance with Section 6.7.2.A of the Technical Specifications, Appendix A of DPR-44 for Unit 2 Peach Bottom Atomic Power Station, the following report is being submitted to the Directorate of Licensing as an Abnormal Occurrence.

Reference:

License Number DPR-44, Amendment Number 1 Technical Specification: Note 4 to Table 3.1.1 Report No.: 50-277-74-21 Report Date: April 21,1974 Occurrence Date: April 11,1974 Faci li ty: Peach Bottom Atomic Power Station R. D. 1, De1 +a, Pennsylvania 17314 Identi fication of Occurrence:

Inoperability of PS.2-5-14C and PS-2-5-14D Conditions Prior to Occurrence:

Plant at 25% power.

Description of Occurrence:

b During the plant start-ups to greater than 30% power, the q operability of the pressure switches which sense turbine first stage pressure were moni tored. It was noted that all the pressure swi tches k./g

,4

/t 8402070451 740421 3 PDR ADOCK 05000277 COPY SENT REGION 3660 I

r Mr. Q. Giambusso Waga 2 l April 21,1974 g3 V (V^) .

Description of Occurrence: (continued) failed to operate at the 30% power Icvel. Before proceeding up in power above 30%, the setpoints on the switches were adjusted to provide the proper logic input to the. RPS system. During the subsequent shutdown, these pressure switches were recalibrated in accordance with a new curve of first stage turbine pressure versus power based on data obtained during the previous operation. During the next start-up, the C and D pres-sure switches failed to operate at the correct turbine power Icvel and were again readjusted to provide proper logic input before exceeding 30%

power. Subsequent investigation determined that the sensing line from the turbine was not delivering the proper pressure signal to these two swi tches. Because plant conditions prevented access to portions of the sensing line, the wires to the proper logic relays were lifted to pro-vide the proper RPS logic inputs.

Designation of Aoparent Cause of Occurrence:

The turbine first stage pressure sensing line for PS-2-5-14C and PS-2-5-14D was found to have i ts root valve closed. This valve was inaccessible at the time of the occurrence.

Analysis of Occurrence:

There was no safety implications associated with this occurrence because the inputs to the RPS syst'em were always in the safe direction. Supervisory personnel ensured proper position of the turbine trip scram bypass relays prior to proceeding above 30% power.

Corrective Action:

The turbine first stage pressure sensing lines were traced back to the turbine. All instrument isolation valves and root valves were checked in the open posi tion. The sensing lines were backfilled with condensate and check to be free of obstruction. At the time of the occurrence, when proper relay operation did not occur, setpoint adjust-ments were made or leads were lif ted to provide proper inputs to the RPS logic. These actions were conservative in that they ensure a reactor scram from turbine trip at any power level (not only above 30% power).

Failure Data:

None.

Very truly yours, r) .

lA

/ <s ,

M. J. Cooney '/

Ass' t Gen 1. Superintendent Generation Division cc: Mr. J. P. O'Reilly Director, Region i United States Atomic Energy Commission 631 Park Avenue King of Prussia, PA 19406

_