05000277/LER-1981-046, Forwards LER 81-046/01T-0.Detailed Event Analysis Submitted

From kanterella
(Redirected from ML20039D906)
Jump to navigation Jump to search
Forwards LER 81-046/01T-0.Detailed Event Analysis Submitted
ML20039D906
Person / Time
Site: Peach Bottom Constellation icon.png
Issue date: 12/21/1981
From: Cooney M
PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC
To: Haynes R
NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML20039D907 List:
References
NUDOCS 8201060329
Download: ML20039D906 (3)
v • d • e


LER-1981-046, Forwards LER 81-046/01T-0.Detailed Event Analysis Submitted
Event date:
Report date:
2771981046R00 - NRC Website
v • d • e

text

T PHILADELPHIA ELECTRIC COMPANY 2301 M ARKET STREET P.O. BOX 8699 1881 -1981 PHILADELPHIA. PA.19101 (215)0414000 December 21, 1981

' k,,

\\\\

b x ;

y y

Mr.

R.

C.

Haynes, Director f'l i

Region I J/\\N 5 ICE?:

'~

Office of Inspection and Enforcement

- Q u r

/

L/

US Nuclear Regulatory Commission R

L.

.i 631 Park Avenue j

King of Prussia, PA 19406 SUBJECT: LIC, ENS,EE E, VENT,_RE,PO,R,T P,R,OMPT _NO,TIFICA,TIO,N

Dear Mr. Haynes:

The following occurrence was reported to Mr.

R.

Blough, Region I, Office of Inspection and Enforcement on December 5, 1981.

Reference:

Docket No. 50-277 Report No.:

2-81-46/1T Event Date:

December 5, 1981 Report Date:

December 18, 1981 Facility:

Peach Bottom Atomic Power Station RD 1, Delta, PA 17314 T,ggh,n,1,qa,1,,,S,ggg(({ga,g{gn,,,R,e,{e,ggn,qq,,

Technical Speci ication Table 3.2.A defines the setpoint for the Main Steam Line Leak Detection High Temperature instruments at "less than 200 degrees P."

The action required if this cannot be met is to " initiate an orderly shutdown and have Main Steam Lines isolated within eight hours" (Tech Spec Table 3.2.A, note 28).

D,e,s,q[{gg{gn,,,qf,_thg,,,E,v,gn,g Unit 2 was operating at about 95% power when a Channel A Group I i

Isolation occurred and the " Main Steam Line (MSL) Tunnel High Temperature Trip" alarm annunciated.

"8201060329 811221 DR ADOCK 05000 g

/!/

Mr..R. C. Haynes Pago 2 The Main Steam Line temperature on the

'A' Channel was 195 degrees F, one

'B' Channel was about 190 degrees F, about 5 degrees F below the actual trip point.

These high temperatures were the result of a loss of the normal reactor building ventilation.

Based on previous occurrences of this. type, it is known that an immediate restoration of ventilation flow will carry hot air past the temperature switches and cause a Group I Isolation.

To prevent this significant reactor vessel pressure transient, the Main Steam Line temperature setpoints uere raised prior to restoration of normal ventilation.

After the ventilation was restored and the Main Steam Line temperatures returned to normal, the setpoints were reset to about 195 degrees F.

During the 20 minute period that the setpoints were above the normal setpoint, the indicators were constantly monitored to ensure that any unusual temperature increase would be detected.

The actions that were taken were the

- same as those taken in January 1981 as authorized by an Emergency Technical Specification change.

The Shift Superintendent on duty knew of that occurrence and that a permanent revision to the Tech Specs had been submitted.

He believed that the Tech Specs had been revised to allow the setpoints to be increased for a short time.

Immediately following the event, he consulted the Tech Specs but could not find authority for this action.

Telephone Conversation with a staff engineer, the Assistant Station Superintendent, and a corporate licensing engineer determined that the revision was still pending.

P,r,,gb,a,b,1,g,,,gqqs gqqqn,qqs,,,gf,,gh,g,,,E,,gggg Before the instrument setpoints were increased, it was known that a main steam line break did not exist.

While the setpoints were above normal, the temperature was constantly monitored to detect any unusual temperature increase.

The setpoint change was made to prevent the significant reactor vessel pressure transient that would have resulted from a Group I Isolation.

ga,ggg,,,gf,,,,gh,g,,,E,ggn,g The Main Steam Line temperatures increased and caused an

'A' Channel Group I Isolation because normal reactor building ventilation flow was lost for a period of about two hours.

The ventilation flow was lost as a result of valving done to transfer equipment cell ventilation from the reactor building ventilation system to the standby gas treatment system.

This is routinely L

Mr.

R.

C. Hnynna Page 3 done to prevent a small radtoactive gas release from the Reactor Building Exhaust Ventilation Stack during the regeneration of a Reactor Water Cleanup Demineralizer.

The loss of normal reactor building ventilation flow was not detected until about two hours later when the

'A' Channel Group I isolation occurred.

The loss of normal ventilation occurred because of operator error during the transition to the standby gas treatment system.

That error was not discovered until after the event, during the investigation conducted by the operator on shift.

I mm,gd,i,a,(g,,C,o,ggge gi,,v,g,,Ac,g{gn s The Main Steam Line setpoints were restored to less than 195 degrees F as soon as the Reactor Building ventilation had been recovered and the Main Steam Line temperatures had been returned to normal.

These instruments were recalibrated within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> and the setpoints were within Technical Specification limits.

Very truly yours, QT

/'

9 M.,J/ Cooney 1perintendent eneration Division / Nuclear cc:

Resident Inspector Director, NRC - Office of Inspection and Enforcement Mr. Norman M.

Haller, NRC - Office of Management &

Program Analysis e

Retrieved from "https://kanterella.com/w/index.php?title=05000277/LER-1981-046,_Forwards_LER_81-046/01T-0.Detailed_Event_Analysis_Submitted&oldid=4561572"