ML20086B221
| ML20086B221 | |
| Person / Time | |
|---|---|
| Site: | Fort Saint Vrain  |
| Issue date: | 11/05/1974 |
| From: | Reader J, Swart F DUKE POWER CO., PUBLIC SERVICE CO. OF COLORADO |
| To: | |
| Shared Package | |
| ML20086B210 | List: |
| References | |
| 50-267-74-19A, AO-50-267-74-19, ROB-74-3, NUDOCS 8311170102 | |
| Download: ML20086B221 (3) | |
Text
._.
O e
REPORT DATE: November 5, 1974 ABNORMAL OCCURRENCE
' FORT ST. VRAIN NUCLEAR GENERATING STATION PUBLIC SERVICE COMPANY OF COLORADO P. O. BOK 361 PLATTEVILLE. COLORADO 80651 REPORT NO. 50-267/74/19A FINAL IDEITTIFICATION OF OCCL'RRENCE:
As requested in AEC DRO BULLETIN NO. 74-3, Public Service Company of Colorado and General Atomic Company have conducted on inspection of the Class I support structure at Fort St. Vrain.
The results of the inspcetion program indicated that design problems existed on 24 of the'238' Class I support structures at Fort St. Vrain.
f This condition is considered reportable under Paragraph B-3 of AEC DRO Bulletin No. 74-3.
CONDITIONS PRIOR TO 00CL'RRENCE:
Steady State Power Routine Shutdown Hot Shutdown Routine Load Change I
Cold Shutdown Other (specify) l Refueling Shutdown Routine Startup The major plant, para =cters at the time of the ew:nt were as follows:
Power
- PTR, O
MWth
- ELECT, O
MWe Secondary Coolant Pressure N/A psig
}
Temperature N/A
- F 8311170102 741114 PDR ADOCK 05000267 S
PDR Flow 0
- /hr.
Primary Coolant Pressure O
psig Temperature 100
- F Corc. Slet 100
- F Core Atiet
- Elow 0
f/hr.
O o.
- v. 2 DESCRIPTION OF
' OCCURRENCE:
~
The results of the inspection program of the Class I support structures indicated that a prob 1cm existed regarding the seismic design of some Class I support structures. The problem related to the support structure natural vibrational frequency and the design carthquake vibrational frequency on 24 Class I support structures.
The specific types of support structures found to have problems were:
1.) Heat Exchanger Support Structures 2.)
Filter Support Structures 3.) Varicus Tank Support Structures APPARANT CAUSE OF OCCURRENCE:
X Design Unusual Service Cond.
Including Environ.
Manufacture Component Failure Installation /
Construction Other (specify)
Operator Procedure ANALYSIS OF OCCURRENCE:
The analysis of this problem consisted of a visual inspection of CJ cs: I support structures by General Atomic Company engineers to verify that the field configurcticn was accurately reflected in the seismic calculations; and where incorrect assu=ptions were made, further analysis cnd structural additions were specified.
General Atomic Company elected to'have the Sargent & Lundy Structural Engineering Department perform the additional analysis where required.
CORRECTIVE
-ACTION:
, Additioncl. structural:. steel. bracing.and reinforcement has been added to those structures (24 in all) found to have scis=ic design problems.
The physical work has been co:pleted and scismic calculations have been forwarded to Public Service Company for review.
Public St vice Company is currently in the process of performing an in-dependent review of all calculations and "as-built" configuration for those l
structures requiring additional reinforcement.
i
~
O o
s.. -(
Page 3 During Public Service Company's review of the scismic calculations submitted by General Atomic Company an error was found on one (1) structure calculation regarding an assu=ption made in the General Atomic /Sargent &
General Atomic Company concurred that the error existed, Lundy calculations.
and the additional structural steel bracing indicated has been installed on this support structure.
FAILURE DATA /SIMILIAR REPORTED OCCURRE';CES:
None of the Class I support structures have evidenced any sign of Also, there has not been any similiar reported occurrences actual failure.
at Tort St. Vrain.
-PROGRA301ATIC IMPACT:
None CODE IMPACT:
None Approved by:
Prepared by:
OS-ELt
/)/
/
J1 N
Fr'ederic E. Swart
'~
~
J II.' Reader SherintendentNuclearProduction Resident Engince.
Fort St. Vrain Nuclear Generating Station