ML20070M006
| ML20070M006 | |
| Person / Time | |
|---|---|
| Site: | Clinch River |
| Issue date: | 01/07/1983 |
| From: | Longenecker J ENERGY, DEPT. OF, CLINCH RIVER BREEDER REACTOR PLANT |
| To: | Check P Office of Nuclear Reactor Regulation |
| References | |
| HQ:S:83:177, NUDOCS 8301120203 | |
| Download: ML20070M006 (4) | |
Text
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.5 Department of Energy Washington, D.C. 20545 Docket No. 50-537 HQ:S:83:177 ggg3
.l Mr. Paul.S. Check, Director CRBR Program Office Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, D.C.
20555
Dear Mr. Check:
ADDITIONAL INFORMATION: REACTOR VESSEL AND EX VESSEL STORAGE TANK (EVST) NON-DESTRUCTIVE EXAMINATION Enclosed is additional information regarding non-destructive examination of the Clinch River Breeder Reactor Plant reactor i
vessel and EVST. This information was requested of Dr. C. H. Fox, Assistant Director for Engineering on December 29, 1982.
Sincerely, dLa
-JMnR.Longen er Acting Director, Office of Breeder Demonstration' Projects Office of Nuclear Energy Enclosure cc: Service List Standard Distribution Ol Licensing Distribution gO B30112O203 830107 PDR ADOCK 05000537 A
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Enclosure
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During.f abrication Volumetric examinations.were performed on all category A, B, C.and D pressure boundary welds in the' Reactor Vessel and Core Support Structure Cone in accordance
~
with ASME code, Code Case 1594 and RDT Standards.
The
.following is a listing of the effective Codes and Standards.
ASME Code, 1974 Edition with Winter 1974 addenda Code Case 1594-1, June 30,.1975-RDT F306, December 1974 RDT E-15-2NB-T, November 1974 with Amendment 1, 1
January 10,1975 I
The ASME Code requires radiography (R ).and dye penetrant T
(T
. P ) checks of I.D. and 0.D. as a base requirement.
These requirements are supplemented by the requirements imposed by Code Case 1594-1.
CC1594 requires additional volumetric 4
inspection be performed in elevated temperature areas.
One of the acceptable methods is to perform radiography at~two different angles (one within 150 of perpendicular to the surface and the other at some angle appropriate for revealing lack of fusion and cracking defects at the weld / base metal interface near the root pass).
The double i
angle X-ray technique was adopted for use on the designated elevated temperature areas of the reactor vessel pressure boundary.
4 B&W designed and fabricated the reactor vessel to meet the l
specification requirements for low as well as elevated temperature areas.
All welds designated as high temperature
[
(>8000F) received double angle X-rays with the remainder using single angle with two exceptions, the bi-metallic i
The bi-metallic weld between the Inconel 600 and the SA-508 received a double angle X-ray followed by a normal X-ray.
The 304 stainless to Inconel 600 weld received a normal X-ray followed by four angle shots.
All X-rays for f
the reactor vessel are available for inspection.
B&W performed volumetric examination in accordance with the ASME Code and RDT Standard requirements.
In addition, radiographic angle shots were taken for information on the bi-metallic welds.
The double angle X-rays are used to iook along the fusion line for closed cracks.
(The reactor vessel used ship-lap type welds which result in the entire area of the root pass being machined away, eliminating the need to look in the root pass for defects with double angle X-ray.)
Use of the double angle X-rcy and fabrication l
= '
s'
': methods results in a level of confidence equivalent to that obtained for ultrasonic inspection.
An additional UT examination was not performed because the vessel material is primarily stainless steel.
The difficulties in connection wit 4 ultrasonic testing of austenitic welds and parent metals are well known.
The problems are connected with metallurgical microstructure which dominates the UT wave propagation response.
The elastic anisotropy of the different grains leads to scattering coupled with mode conversion problems.
Further research on the testing of strongly attenuating structures and on-signal analysis is necessary before UT can be used as meaningful baseline mapping of stainless steel weldments for heavy wall pressure vessels.
During fabrication EVST vessel welds received the following examinations per ASME Section III - Class 2 Code Requirements.
Stainless Steel Welds RT and PT Carbon Steel Welds RT and MT Dissimilar Metal Weld RT and PT An additional UT examination was not performed because.the vessel material is primarily stainless steel.
UT examination of stainless steel welds which use filler material is not a reliable method for inspection, because of large grain sizes in the weld metal.
The same is true in the Inconel 600 dissimilar metal weld joint.
There is only one carbon-to-carbon steel weld joint making up the carbon steel support forging subassembly which subsequently is welded to the stainless steel shell course via the above dissimilar joint.
It was determined that a UT inspection of the carbon-to-carbon weld was not necessary because of low stresses at this location.
All as built X-rays for the EVST are available for inspection.
NOTE:
Code Case 1594-1, June 30, 1975, does not apply to the EVST whose design temperature is 6500F.
The Project Office feels that the NDE comp:.eted during the fabrication of the two vessels is sufficient to provide a high confidence level in the structural integrity of the
- walds, However the Project Office has confirmad that a ultrasonic examination of the ferritic welds and the ferritic side of the bi-metallic welds can be performed and is re-evaluating the usefulness of performing a UT examination of these welds.
.. All Reactor' Vessel X-rays including those showing the indications that were repaired are available for review.
T 1
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