ML19329A554
| ML19329A554 | |
| Person / Time | |
|---|---|
| Site: | Oconee  |
| Issue date: | 04/18/1972 |
| From: | Peltier I US ATOMIC ENERGY COMMISSION (AEC) |
| To: | Deyoung R US ATOMIC ENERGY COMMISSION (AEC) |
| References | |
| NUDOCS 8001070526 | |
| Download: ML19329A554 (4) | |
Text
_
r/
,N
,, i ',.. (.-
( ~ [
/
j UNITED STATES
'[ - [ /.
E
') %
ATOMIC ENERGY COMMISSION I
- WASHINGTON. D.C. 20545
% n@,,,, 9 ra 1 a a E
R. C. DeYoung, Assistant Director, PURs, DRL THRU:
A. Schwencer, Chief, PWR Branch 4, DRL TELECON BETWEE'i DRL, DRS, CO, B&W AND DUKE POUER COMPANY COMCEPSING INVESTICATION, EVALUATION AND CORRECTION OF PROGLEMS ON OCONEE A.
Field Insnection 1.
36W reported that its field inspection is 90% complete and no new dara2ge has been found.
2.
The next seco is to remove the thermal shield, examine the dowel pins, bolt torques, spacers and par's, and flange between core barrel and shield. All parts renoved will be indexed for orienta-tion and removed in accordance uith written procedures. Photos will also be taken. This work will start next week with the actual shield lif t being made about Thursday.
3.
Primary cumps appeared to be in good condition based on a visual in-place examinatien perforced by crawling throuPh the pipes.
A ther=ocouple wire is all that s as found in one of the pumns.
4.
Investiration has accounted for most of the mass. The equivalent of 1 1/2 stub tubes (2 pounds) r still unaccounted for.
Inconel u
flakes were beaten down f-
"or steam generator tube sheets and
~
could account for some ol
- nissing mass. The high pressure injection line was inspeci.ed and foi ud to be clean; the let down line had some fine deposits but no p. Mees. The low oressure injection line has not been inspected yet.
5.
Dye-penetrant checks have revealed nothing new.
B.
Failure Mcde Investi<tation 1.
Pieces removed from oconee were taken to Alliance for examination.
Evidence points toward high cycle fatigue failure. There is definite striation due to 50 cycles per second or greater fatigue.
B&W has duplicated the inconel failure on rods in 2000F water with the results being similar in appearance to the tube failures at Oconee.
2.
The crack initation site on the stub tubes was on the high veld side (within 900) and within an inch above the weld.
It was
- possible to match un some of the broken tubes with their original positions.
8001070 [ M 4l l
}
- 3.
B&W is going to test a welded mockup of the stub tubes to evaluate whether cold straighteningtof the Oconee tubes af ter stress relieving could have produced significant strain.
C.
Hydraulic Studies 1.
The 1/6 scale model data was reexanined and prooosals for additional tests are expected to be developed by April 17.
2.
Processing of the flow data from Oconee has not been completed.
3.
A 3 dimensional map of presss. a and. flow from inlet no::le to core internals is in process and will be used to look for local hich velocity sites. There is evidence of circumferental flow variations coming down into the vessel.
D.
Vibration Testing at Barberton 1.
Nearly all of the vibration data from Ocones has been analyzed.
A.
comparison of the data obtained before and af ter discovery of the problem has been ende.
Data indicates that on February 28 something may have loosened up and on March 3 inpact on core support structure was indicated by all four accelerometers.
2.
Alliance tests show that the accelerometer tube could have failed by pure fatigue.
3.
Darberton vibration tests on the SMUD internals shes an order 3 mode shape at 48 cycles /sec., order 4 at 69 cycles /sec. and order 5 at 93 cycles /sec. This is consistent with 45 cycles /sec. order 3 mode measured at Oconce. The order 3 sada could be dus to flexibility in the pad spacer blocks (nine in all). The natural frequency measured for the instrument guide tubes was 80 to 250 cycles /sec.
4.
The accelerometer recordings show random snikes (off scale) indicating impact in both r.he radial and vertical directions.
5.
Oconee data will be compared with the Barberton data and an attempt will be made to force the same bell modes at Barberton.
6.
B&W fadicated that the thermal shield supports both top and bottom may have to bc ::edesigned.
7.
They acknowledr.ed also that the vibration monitorine program will have to be revised.
~
. E.
Fabrication Process 1.
A review of the fabrication process and the chemistry history of the vessel and its internals revealed nothing unusual. The cold straightening of the stub tubes after heat treatment will be studied further as noted above.
F.
Steam Generator Repair 1.
Procedures have been written and approved.
2.
Work started (April 4,1972) on S.G. A but some of the tools were delayed arriving at the site.
3.
No work has been done on the tubes in the A generator yet but smoothinn up the head has proceeded well and dye-penetrant checks on the head have been completed.
4.
Dye-checking in B renerator tubes and some grinding has been completed. About 5000 cubes have been done.
Progress is very good. No welding has started but will begin near the end of the week of April 17.
People participating in this conference call were:
B&ti AEC pnye G. Xulynych G. Reinnuth, CO S. Blackley R. Edwards J. llenderson, CO K. Kennedy T. Taylor D. Lano.c, DRS A. Lazar J. Walker I. Peltier, DRL D. Aabye G. Snyder A. Schwencer, DRL N. liooker J. Walker 3 wnd hY
- 3, I'dliS I. A. Peltier Dis trib st
- f on:
See a:tached 4
n-
- T?
d
=
4-DISTIIBUTIC'R E. illoch, DR S.11anatier, DR P. A. !!arris, DRL F..
- F. Schroeder, DRL
-R. Engelken, CO (4)
DRL Assistant Directors DRS Assistant Directors PWR Branch Chiefs R. K1ceker, DRL I. Peltier,' DRL (2)
J. 'Mrphey, DRL
- 11. Schierlinr., DRL R. F. Fraley, ACRS
{. Shaw, RDT A. Pressesky, RDT Docket DRL Readinr.
PWR-4 Re.1dinr, pgg e--p g i
f 4
9
.T i
l-I r
I-d l
.. -