St. Lucie Pressurizer Nozzle DM Weld Examination Project 

Internal Office Report 

St. Lucie Pressurizer DM weld examinations 

The scope of this project for EPRI was to oversee the examination of six dissimilar metal 

(DM) welds associated with the Combustion Engineering Pressurizer vessel that was 

recently removed from service from the St. Lucie Nuclear Power Station. The 

examinations were to include surface and volumetric examinations, specifically visible 

liquid dye penetrant (PT) examinations of both the outside (OD) surface and inside (ID) 

surface of each DM weld, and Phased-Array ultrasonic (UT) examination of the volume 

of each DM weld. The examination area and volume were to be the same as for a normal 

Inservice Inspection (ISI) examination of these welds. 

EPRI contracted Structural Integrity Associates, Inc.(SIA) to perform the NDE, which 

also required a procedure expansion of the SIA phased-array UT procedure SI-UT-130. 

Initial Visit to the Memphis Facility: 

I first met with Kevin Butler and David Jennings, at the Studsvik/Race facility on 

President’s Island in Memphis on January 25th, in order to look at the Pressurizer heads 

and to give the facility instructions on how to prepare the 6 associated dissimilar metal 

welds for examination. The as-found condition of the nozzles was that they were fully 

intact and in the same condition as they had come from the plant. The lower head piece 

contained one nozzle, which was the 14” Surge nozzle. This nozzle had a screen/filter 

associated with it, which was located on the inside surface of the head. The upper head 

piece contained five nozzles, which were the 3” Spray nozzle, the 4” Relief nozzle, and 

three 4” Safety nozzles. The Spray nozzle also had a nozzle associated with it on the 

opposite surface of the head, which had been internal to the Pressurizer during operation. 

Each of the 6 nozzles appeared to have end caps welded on them, and the external surface 

of both head pieces appeared to be coated with some sort of paint or protective coating. 

Upper Head Piece showing five nozzles and the internal portion of the Spray nozzle 

 Cut line 
St. Lucie Pressurizer Nozzle DM Weld Examination Project 

Internal Office Report 

Lower head containing the Surge nozzle Internal portion of Surge nozzle 

 Cut line 

During the initial visit to the facility, I explained a little bit about the examinations that 

we were going to be performing on the nozzles and why. I requested that the two internal 

nozzles be cut off of the head pieces, and that each end cap be completely removed, so 

that we would have access to the ID of each nozzle. I instructed them to remove any 

internal thermal sleeves that would interfere with our access to the inside surfaces of the 

welds, as well. I also requested that all paint, coatings, rust and scale be removed from all 

surfaces of the pieces, down to the bare metal. At that time, they expressed concern for 

their ability to remove the end cap from the Surge nozzle, due to the size of the weld. We 

discussed that it should only involve cutting along the weld at the edge of the cap, and 

that the cap should come off fairly easily. They also asked me if it would be a problem if 

the flanges on the Safety nozzles were damaged during the cutting, and I said that it was 

not a concern as long as the weld area of the nozzle was not affected. 

The February 4th Week at the Memphis Facility:

Upon arrival to the facility on Monday, February 4th, we received radiation worker 

training and facility safety training and were then allowed to dress out and enter the 

Sectional Shop, where the pieces were staged. The as-found condition of the upper head 

piece, at this time, was that the internal nozzle and end caps had been completely 

removed and the surfaces had been bead blasted with some sort of carbon steel metallic 

material, which had removed all paint and coatings but left the surface in a rough rusty 

looking condition. Even the stainless and inconel surfaces were rusty. Our assumption 

was that this was caused from carbon steel blast material being embedded into the 

surfaces. The flanges at the ends of the three Safety nozzles were completely removed 

along with the end caps. On the lower head piece, the DM weld on the Surge nozzle was 

actually damaged from the cutting and there were portions of the end plug still in place. 

When I inquired about this, they told me that the end cap had actually been a plug and 

that it had been very difficult to remove. I took one of the facilities cutting technicians 

out to the nozzle and showed him the portions of the plug that were still in place and 

asked him to carefully remove the weld around the edge of it, and that it would come out. 

He followed these instructions and was able to remove the remaining portion of the plug. 
St. Lucie Pressurizer Nozzle DM Weld Examination Project 

Internal Office Report 

An assessment of the Surge nozzle, after complete plug removal showed that a great deal 

of the ID of the weld had been damaged by flame cutting. 

Upper Head after initial prep work Safety nozzle after flange removal 

Surge nozzle after initial prep work (note ID damage caused by flame cutting) 

Portions of the end plug still in place Flame cut hole in the DM weld 
St. Lucie Pressurizer Nozzle DM Weld Examination Project 

Internal Office Report 

We had brought our own side grinder and flapper wheels, so we proceeded to prepare the 

outside surfaces of the nozzle weld areas to remove the rust and smooth out the rough 

surfaces. By the end of the first day, we had managed to adequately prepare the outside 

surfaces of the welds for PT and UT examinations. 

 Upper head after flapping Surge nozzle after flapping and plug removal 

On Tuesday, we set up and performed liquid dye penetrant (PT) examinations of the OD 

surface of each DM welds. There were two small rounded indications noted during the 

OD PT exams. One was on the Relief nozzle, in the DM weld surface area. And the other 

was on the “C” Safety nozzle, also in the DM weld surface. 

 Relief Nozzle OD PT indication “C” Safety nozzle OD PT indication 
St. Lucie Pressurizer Nozzle DM Weld Examination Project 

Internal Office Report 

Tuesday afternoon, we began Phased-Array UT examination on the “A” Safety nozzle 

DM weld, using longitudinal ultrasonic sound beams projected from 0° to 80° angles. We 

immediately noted a large number of planar reflectors in the weld, which were stacked on 

top of each other and appeared to extend from the ID surface of the weld up to 

approximately 0.325” from the OD surface of the weld, at the deepest point. These 

reflectors were numerous and were present 360° around the circumference of the weld. 

When scanning across the tops of these indications, the UT sound beams that were 

projected normal to the surface (straight beams) did not pick up the indications, as you 

would expect them to if the indications were caused by internal inclusions. Under normal 

field examination conditions, these types of indications would have to be recorded and 

evaluated as one continuous linear planer flaw, seen 360° around the weld. 

Screen shot of these stacked UT indications, as seen at the 3 o’clock position 

On Wednesday, we continued UT examination of the remaining nozzles. The two other 

Safety nozzle DM welds also contained 360° linear planar indications. The “B” Safety 

DM weld indication was measured from the ID surface to within 0.396” of the outside 

surface. The “C” Safety nozzle DM weld indication was measured from the ID surface up 

to 0.495” of the outside surface. These indication exhibited the same features as that of 

the “A” Safety nozzle DM weld. 

Stacked indications 

Backwall 
St. Lucie Pressurizer Nozzle DM Weld Examination Project 

Internal Office Report 

The Spray nozzle DM weld was found to contain one embedded planar indication that did 

not appear to be connected to the ID surface, and was indicative of a lack of fusion type 

flaw located along the upper bevel of the weld to base material interface. The Relief and 

Surge nozzles did not contain any recordable indications. 

Wednesday evening, we purchased a die grinder and some abrasive wheels in order to 

prepare the ID surfaces of these DM welds for PT examination. On Thursday, we were 

able to use these new tools to prepare a suitable ID surface for examination on each 

nozzle DM weld. The PT of the inside surfaces the “A” and “C” Safety nozzles produced 

several aligned dotted indications within the weld material, which were very defined and 

easy to interpret as surface connected flaws. The “B” Safety nozzle had three very faint 

indications in one area of the weld inside surface, which were reproducible, but were not 

as definitive as on the other two Safety nozzles. Surprisingly, the Spray and Surge 

nozzles also had recordable PT indications on the ID surfaces, in the area of the DM 

weld. They, too, were aligned. The Surge nozzle indications were somewhat small and 

faint, similar to that of the “B” safety nozzle. However, the Spray nozzle indications were 

very defined and sizeable. We re-examined the Surge and Spray nozzle DM welds after 

the ID PT examinations, but were still unable to record UT indications associated with 

the PT indications. 

Typical Safety nozzle aligned ID PT indications 

Spray nozzle aligned ID PT indications 
St. Lucie Pressurizer Nozzle DM Weld Examination Project 

Internal Office Report 

Faint ID PT indications on the Surge nozzle 

Summary of NDE findings:

All six nozzle DM welds on the former St. Lucie Combustion Engineering Pressurizer 

vessel were successfully examined from both the OD and ID with liquid dye penetrant, 

and were volumetrically examined by the Phased-Array UT method, using Structural 

Integrity Associates PDI qualified procedure SI-UT-130. The only limitations to these 

examinations were on the Surge nozzle, where initial attempts to remove the end plug by 

flame cutting had resulted in extensive damage to the ID surface and in one area had 

resulted in a hole through the middle of the DM weld. 

The OD surface PT examinations of these six nozzle welds resulted in two recordable 

indications. One small rounded indication was recorded in the Relief nozzle DM weld 

crown surface. One small rounded indication was recorded in the “C” Safety nozzle DM 

weld crown surface. Both of these indications were indicative of porosity-type 

indications, which may have been uncovered during the bead blasting and flapping 

processes. Further surface preparations were not performed in the areas of these 

indications to see if they could be removed. 

The phased-array UT examinations of the nozzles resulted in multiple stacked planar 

indications being recorded in all three of the Safety nozzle DM welds, which under 

normal field NDE conditions would likely be reported as 360° linear planar flaws. The 

approximate through-wall depths of these indications at the deepest points were 80% on 

the “A” Safety nozzle, 75% on the “B” Safety nozzle, and 69% on the “C” Safety nozzle. 

Additionally, one non-surface connected indication, indicative of lack of fusion was 
St. Lucie Pressurizer Nozzle DM Weld Examination Project 

Internal Office Report 

recorded on the Spray nozzle. No recordable indications were noted on the Relief or 

Surge nozzles, during the UT examinations. 

The ID surface PT examinations of the nozzles resulted in multiple, well defined, aligned 

surface indications being recorded in the weld root area of the “A” and “C” Safety 

nozzles and the Spray nozzle. The “B” Safety nozzle and Surge nozzle each showed a 

few faint indications in the weld root area, which were not as well defined, but were 

recordable. The Relief nozzle did not reveal any ID surface indications. As with the OD 

surface indications that were noted, all of these ID connected indications could have been 

uncovered during the surface preparation activities. Further surface preparations were not 

attempted in the areas of any of these ID indications to see if they could be removed. 

Conclusions 

The two rounded indications recorded during the OD PT examinations are not unusual, 

during normal ISI surface examinations. Additional grinding would normally be 

prescribed to attempt to remove these indications. Surface Eddy Current examination 

could also be utilized to determine if these indications become linear underneath the 

surface. 

The UT indications recorded on the three Safety nozzles contained multiple planar 

reflectors, which appear to be vertically stacked and extend from the ID surface to a 

significant through-wall depth. These indications are indicative of corrosion cracking, but 

could also be attributed to multiple stacked inclusions in the weld material, left over from 

construction. Performing automated UT on these three nozzle welds would allow for 

better flaw mapping and analysis. However, under normal field NDE conditions, these 

three welds would certainly be reported as containing 360° linear planar flaws of 

significant through-wall depth, which would require immediate repair. 

The aligned ID PT indications noted on several of these nozzles could also be indicative 

of corrosion cracking. During many recent PT examinations of Reactor Upper Head 

penetration welds, PWSCC flaws were initially recorded as small aligned “snake bite” 

indications in the surface of the weld, which upon further surface grinding revealed linear 

cracking. However, it is also possible that the initial surface preparation of these welds 

uncovered inclusions in the weld material, which may have been removed upon further 

surface preparation. Surface Eddy Current examination could also be used to determine 

whether or not these indications are linked.