ML20106J255

Special Rept:On 840915,PORV 1NC32B Automatically Opened to Relieve Pressure Increase in RCS Due to Nc Pump Start.Cause Unknown.Change Made to Nc Pump Operating Procedure OP/1/A/6150/02A & Shift Operators Made Aware of Change

ML20106J255
Person / Time
Site:	Catawba
Issue date:	10/11/1984
From:	Tucker H DUKE POWER CO.
To:	James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
References
NUDOCS 8411010145
Download: ML20106J255 (3)

Text

r 1

K - .

~ '

? l DUKE POWER GOMPANY P.O. BOX 33189 CHARLOTTE, N,0. 28242 HALB. TUCKER TELEPHONE

.JC."". "J" # ""

• October i g} S l l8 P l I 'IO Mr. James P. O'Reilly, Regional Administrator U. S. Nuclear Regulatory Commission Region II 101 Marietta Street, NW, Suite 2900 Atlanta, Georgia 30323 Re: Catawba Nuclear Station, Unit 1 Docket No. 50-413

Dear Mr. O'Reilly:

Pursuant to Technical Specification 3.4.9.3, Action Statement C, please find attached a Special Report concerning the automatic opening of a pressurizer power-operated relief valve.

Very truly yours, f ,e4 k Hal B. Tucker-RWO: sib Attachment cc: Director Office of Inspection and Enforcement U. S. Nuclear Regulatory Commission Washington, D. C. 20555 NRC Resident Inspector Catawba Nuclear Station Palmetto Alliance 21351 Devine Street Columbia, South Carolina 29205 Mr. Jesse L. Riley Carolina Environmental Study Group 854 Henley Place Charlotte, North Carolina 28207 Mr. Robert Guild, Esq.

Attorney-at-Law ,

P. O. Box 12097 i Charleston, South Carolina 29412 l 0FFICIAL COPY 8411010145 841011 DR ADOCK 05000 f go

c z 4 ,

J .- .

On-September 15, 1984, at 0352 hours0.00407 days <br />0.0978 hours <br />5.820106e-4 weeks <br />1.33936e-4 months <br />, Pressurizer Power Operated Relief Valve (PORV) INC32B automatically opened, and remained.open for 29 seconds to -

relieve a pressure increa'se in the Reactor Coolant (NC) System caused by an NC . Pump start. One PORV was able to relieve the minor. pressure transient. This Catawba . incident is reportable pursuant to Technical Specification 3.4.9.3,

' Action Statement C, which requires submittal of a Special Report pursuant to Technical Specification 6.9.2.

~ A' Power Operated Relief Valve (PORV) opens when necessary to relieve pressure, thereby mitigating system pressure transients by relieving to the pressurizer

relief tank.. The pressurizer PORV's can be placed in the MANUAL or AUTOMATIC

! Mode. In MANUAL, the PORV will open; in AUTOMATIC, the PORV will open when the Reactor Coolant (NC) System Wide Range Pressure Transmitter actuates the Process Control Interlock. While in the AUTO Mode, the PORV's are aligned to

! open at either the upper high . pressure setpoint (2335 PSIG) or'the lower.

[ high pressure setpoint (400 PSIG), selected depending upon system conditions.

! 1NC32B was set to the low setpoint at this time.

I l

At 0352 hours0.00407 days <br />0.0978 hours <br />5.820106e-4 weeks <br />1.33936e-4 months <br /> on 9/15/84, Unit 1 was in Mode 5, Cold Shutdown. Reactor Coolant 2

(NC 140jF. System Reactor pressure Coolant was wasbeingapproximately circulated by 370 thePSIG andHeat Residual TaveRemoval was approximately(ND)

System, Train A. At 0352:03 hours, NC Pump 1B was started. Coincident with the pump start, NC System wide range pressure started increasing. At 0352:38 hours, Pressurizer PORY INC32B began to open, reaching the fully open position in about

, two seconds. The valve stayed fully open for approximately 29-seconds. Valve i INC32B closed at 0353:10 hours, and NC System wide range pressure indicated 371 PSIG. During this incident PORY INC32B was-in the Low Pressure Mode.

The NC System Pressure Strip Chart Recorder was not functioning ~at the time of 2

the incident. Also, Computer Point A0719 (NC System Wide Range Pressure) was set up on temporary alarm at 376 PSIG, providing pressure printout on the Alarm t Typer only when it reached 376 PSIG increasing or decreasing. Therefore, the

, Alarm Typer did not print maximum NC pressure during the transient. However, i the Nuclear Control Operator (NC0) was observing the Operator aid computer at the time of the incident. The maximum NC pressure observed was 397 PSIG.

During this incident a difference of 120F existed between the Reactor Coolant and the secondary side, with the secondary side.being the. higher. When Reactor i Coolant is flowing through the Steam Generators under. this condition, the possi-bility exists for an increase in NC pressure due to thermal expansion. However,

a 120F Delta-T with an NC Pump Start has been evaluated, and the effect on NC pressure due to thermal expansion is considered to be very minimal.

Experiences at McGuire Nuclear Station have indicated that when the first NC

j. Pump is started, NC pressure will often increase 30 to 40 PSIG. The Catawba t

NC Pump Operating Procedure, OP/1/A/6150/02A, did not provide guidance _to the

+

Operator on the potential pressure increases when starting an NC Pump. Minor

pressure transients were expected by Operations, however, specific values had j not been experienced.

! l 4

)

3-

~_ -,2,.,.4 . ~ , - . . - . - , . . , . , ~ . - - - - . _ _ . . . - . - - - -

l

.., l I, -

Work Request 82 LAP was initiated to check the calibration of Loop 1NC5140.

The "as-found" data was within tolerance.

A change was made to the NC Pump Operating Procedure, OP/1/A/6150/02A, inserting the following limits and precautions step:

" Starting an NC Pump when NC System is >350 PSIG may cause a pressurizer PORV to open when in low pressure mode."

The Shift Operators will be made aware of the recent change made to OP/1/A/6150/02A by means of an Operator Update.

Verification of Subsequent Corrective Action was completion of Work Request 82 LAP and Procedure change number 8 to OP/1/A/6150/02A.

Verfication of Planned Corrective Action will be a completed Operator Update.

S_AFETY ANALYSIS Given an NC temperature of 1400 F and a 00F cooldown rate, 675 PSIG is the maximum allowable NC pressure before metal nil ductility concerns are encountered.

this transient was approximately 400 PSIG, never coming Maximum NC pressure near the 675 PSIG limit. during(See Tech Spec, figure 3.4.3.)

All steam relieved through the PORV went directly to and was contained in the Pressurizer Relief Tank. The health and safety of the public was not affected by this incident.