ML19308A212

Reportable Occurrence on 780622: Piping Penetrations Not Designed to Be Solidly Grouted Were Found to Be Solidly Grounted.During Subsequent Design Review,Excessive Support or Pipe Stresses Found on 11 Isometrics. Probable DELETE-RO

ML19308A212
Person / Time
Site:	Trojan File:Portland General Electric icon.png
Issue date:	12/26/1978
From:	PORTLAND GENERAL ELECTRIC CO.
To:
Shared Package
ML19289A049	List: 05000344/LER-1978-020, Forwards LER 78-020/03X-3 ML19308A212
References
TAC-07551, TAC-7551, NUDOCS 7901030166
Download: ML19308A212 (4)

Text

.

REPORTABLE OCCURRENCE 1.

Report Number:

78-20 Revision 3 2.

a.

Report Date:

December 26, 1978 b.

Initial Report Date:

July 21, 1978 c.

Revision 1, October 6, 1978 d.

Revision 2, October 16, 1978 c.

Occurrence Date:

June 22, 1978 3.

Facility: Trojan Nuclear Plant, PO Box 439, Rainier, Oregon 97048 4.

Identification of Occurrence:

Pipirg penetrations not designed to be solidly grouted were found to be solidly grouted. During subsequent design review and stress analyses, excessive support or pipe stresses were found on eleven isometrics.

5.

Conditions Prior to Occurrence:

The plant was in Mode 5, cold shutdown, at the time of this event.

Reactor coolant system temperature was 160*F and pressure was 335 psia.

6.

Description of Occurrence:

During late 1977 and estly 1978 while snvestigating independent plant problems, questions arose concerning a so'11dly grouted pipe penetration.

Design stress calculations assumed an unrestricted penetration. A design review, stress analysis, and field survey of selected penetrations for high stress levels was conducted.

In June, 1978, a piping section was calculated to have stress levels above code allowable during design conditions.

Isometrics were selected for the survey as follows:

a.

All isometrics classified as Seismic Category I except most piping in the containment. Piping in the containment was generally not surveyed because:

1.

A review of piping arrangements and isometric drawings depicting accumulator safety-injection systems and com-ponent cooling water lines to containment air coolers demonstrated that piping was routed around biological shield walls or through pipe chases.

2.

The results of a survay including 20% of Nuclear Class 1 piping revealed no discrepancies.

7901030/(,c,

Reportable Occurrence LER 78-20. Revision 3 Page Two 3.

A review of design criteria for in-containment piping indicated an absence of requirements for sealing penetrations for fire, flooding, shielding, H&V separation or for any other reason.

b.

Piping listed on the architectural drawing penetration schedules, l

Other piping which is classified as hanger critical except where c.

grouted penetrations simply were not used.

Of the approximately 700 isometric drawings surveyed, 50 involving Seismic Category I piping required specific stress analysis.

Con-servatively assuming that the grouted penetrations act as an anchor, stress levels were found unacceptable on 11 isometrics.

In some cases, pipe stress exceeded the maximum allowed by ANSI B31.7; in others, the support loads were unacceptable. A summary of the affected piping and the type of stress involved is presented in the attached table.

7.

Designation'of Apparent Cause of Occurrence:

Ef forts to determine the cause of problems identified included the review of various Seismic Category I piping isometric drawings depicting as-built conditions, associated penetration schedules, and appropriate contract documents and correspondence.

In summary, we determined that the selection and installation of penetration details during construction was not part of a controlled process.

8.

Analysis of Occurrence:

This occurrence has had no affect on either the plant nor public safety.

Stress levels the piping has been exposed to are below the minimum ultimate tensue strength. After modification, piping stress levels wili be acceptable for all accident conditions.

9.

Corrective Action:

Grout removal or support modification has been performed as a.

appropriate.

(See attached summary) b.

A thorough review of potential piping penetration problems was performed as described in Section 6, description of the occurrence.

pe'

'T M

SIR 0!ARY OF PIPE STRESSES FOR LER NO. 78-20, REVISION 3 December 26, 1978 Nominal Pipe Type Of Item Diameter Problem Modification Number Pipe Description (Inches)

(1)

(2) 1.

Onrging Pump Common Suction from Volume 8

P 2

Control Tank 2.

Reactor Coolant Pump Seal Water to 4

P 1

Charging Pump Common Suction 3.

Residual Heat Removal Pump Discharge 3/4 P

1 Instrument / Flush Line 4.

Containment Sump to Containment Spray 14 (3) 2 Pump 5.

Component Cooling Water Surge Lines to 4

S 1

Surge Tanks (2 penetrations) 6.

Charging Pump Suction from Refueling 8

S 1

Water Storage Tank (2 penetrations) 7.

Ch.rmical and Volume Control System Letdown /

4 P

1 Recirculation Discharge to Holdup Tanks A&C (2 penetrations) 8.

Evaporator Feed Ion Exchanger Suction 2

P,S 1

9.

Volamo Control Tank Relief 4

S 1

10.

Spent Resin Storage Tank Gas Sample 3/8 P

1 11.

Containment Ventilation Monitoring System 1

S 1

NOTES:

(1) P means pipe stresses exceed ANSI B31.7 allowable limits.

S means support loads are excessive.

(2) 1 means support modifications are required.

2 means grout removal is required.

(3) Pipe stress affects wall loading.

e