ML021900011
| ML021900011 | |
| Person / Time | |
|---|---|
| Site: | Summer  |
| Issue date: | 07/03/2002 |
| From: | Byrne S South Carolina Electric & Gas Co |
| To: | Cotton K Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| BL-02-001, RC-02-0115 | |
| Download: ML021900011 (11) | |
Text
Stephen A. Byrne Senior Vice President, Nuclear Operations 803.345.4622 July 3, 2002 RC-02-0115 A SCANA COMPANY Document Control Desk U. S. Nuclear Regulatory Commission Washington, DC 20555 Attention: Ms. K. R. Cotton Ladies and Gentlemen:
Subject:
VIRGIL C. SUMMER NUCLEAR STATION (VCSNS)
DOCKET NO. 50/395 OPERATING LICENSE NO. NPF-12 RESPONSE TO NRC BULLETIN 2002-01 REACTOR PRESSURE VESSEL HEAD DEGRADATION AND REACTOR COOLANT PRESSURE BOUNDARY INTEGRITY
Reference:
- 1. S. A. Byrne (SCE&G) letter to Document Control Desk (NRC),
RC-02-0055, (Initial 15 day) Response to NRC Bulletin 2002-01, April 3, 2002
- 2. S. A. Byrne (SCE&G) letter to Document Control Desk (NRC),
RC-02-0091, (60 day) Response to NRC Bulletin 2002-01, May 17, 2002 The U. S. Nuclear Regulatory Commission (NRC) issued NRC Bulletin 2002-01 to require that pressurized water reactor (PWR) utilities provide information related to: 1) the integrity of the reactor coolant pressure boundary including the reactor pressure vessel head and the extent to which inspections have been undertaken to satisfy applicable regulatory requirements, 2) the basis for concluding that plants satisfy applicable regulatory requirements related to the structural integrity of the reactor coolant pressure boundary and that future inspections will ensure continued compliance with applicable regulatory requirements, and 3) if an addressee is unable to provide the information or they can not meet the requested completion dates provide to the NRC a written response in accordance with the provisions of 10 CFR 50.54(f).
AkOC15 SCE&G I Virgil C. Summer Nuclear Station
- P. O. Box 88. Jenkinsville, South Carolina 29065 -T (803) 345.5209 ° www.scana.com
Document Control Desk 0-C-02-0703 RC-02-0115 Page 2 of 3 South Carolina Electric & Gas Company (SCE&G) acting for itself and as agent for South Carolina Public Service Authority, submitted the required initial responses through Reference 1 and Reference 2.
SCE&G hereby submits the attached in response to Required Information, Item 2, of the bulletin which mandates submittal of reactor vessel head inspection results within 30 days after plant restart from the next refueling outage. VCSNS restart from Refuel 13 occurred on June 3, 2002.
These statements and matters set forth herein are true and correct to the knowledge, information, and belief.
Should you have questions, please call Mr. Mel Browne at (803) 345-4141.
Very truly yours, Stephen A. Byrne best of my JT/SAB Attachment c:
N. 0. Lorick N. S. Cams T. G. Eppink (w/o Attachment)
R. J. White L. A. Reyes W. R. Higgins D. M. Deardorff A. L. Bennett A. R. Rice C. H. Rice NRC Resident Inspector K. M. Sutton NSRC RTS (IEB 2002-01; O-C-02-0703)
File (815.02)
DMS (RC-02-0115)
Document Control Desk 0-C-02-0703 RC-02-0115 Page 3 of 3 STATE OF SOUTH CAROLINA TO WIT.
COUNTY OF FAIRFIELD I hereby certify that on the 3r14 day of J.tL1 2002, before me, the subscriber, a Notary Public of the State of South Carolina personally appeared Stephen A. Byrne, being duly sworn, and states that he is the Senior Vice President, Nuclear Operations for the South Carolina Electric & Gas Company, a corporation of the State of South Carolina, that he provides the foregoing response for the purposes therein set forth, that the statements made are true and correct to the best of his knowledge, information, and belief, and that he was authorized to provide the response on behalf of said Corporation.
WITNESS my Hand and Notarial Seal My Commission Expires Notary Public Date
Document Control Desk Letter Attachment 0-C-02-0703 RC-02-0115 Page 1 of 8 Results of Reactor Vessel Head Inspections for NRC Bulletin 2002-01 "Reactor Pressure Vessel Head Degradation and Reactor Coolant Pressure Boundary Integrity" for V. C. Summer Nuclear Station Item 2 of the Bulletin requires that PWR licensees provide the following information within 30 days of the plant re-start following the next inspection of the reactor pressure vessel head to identify any degradation:
- a.
the inspection scope (if different than that provided in response to Item 1.D.) and results, including the location, size, and nature of any degradation detected,
- b.
the corrective actions taken and the root cause of the degradation.
SUMMARY
A remote visual examination of the area between the reactor vessel head insulation and the reactor vessel head was performed. Two dry thin film boron deposits and a small amount of debris were identified on the reactor vessel head. The boron traces were judged to have entered from above the insulation through insulation section seams at vessel head penetration (VHP) locations #27 and #47. Each deposit is a thin uniform thickness film indicating that the leakage occurred at relatively low temperatures. Being dry these boron film deposits do not pose a corrosion concern nor an obstacle for future inspection and detection of pressure boundary leakage. The video inspection showed no evidence of recent boric acid leakage from any reactor vessel head penetration.
The small amount of debris noted during this inspection is small in size and poses no safety concern.
There are no indications of material degradation, therefore structural integrity is unaffected.
DISCUSSION Condition Evaluation Report, CER 02-1189 was written documenting Engineering's evaluation of the video inspection performed between the reactor vessel head insulation and the reactor vessel head. Following are the results of this evaluation:
Boron Deposition Comments A close inspection of the reactor vessel head penetrations as listed in the attached table was performed to determine if any boron deposits were present that had a "popcorn" or "stalagmite" appearance as described in sections 6.2.2 and 6.2.3 of Ref. 3. No boron deposits were found to be originating from the penetration-to-head (annulus) area.
Document Control Desk Letter Attachment 0-C-02-0703 RC-02-0115 Page 2 of 8 Traces of boric acid were noted on 20 of the 66 penetrations or on the insulation at the top of the tubes associated with the penetrations. The deposits were very thin films of dried boron that originated from above the reactor vessel head insulation and trickled down the tubes.
Boric acid did reach the vessel head at two locations (penetrations 27 and 47) as evidenced by a thin dry film on the tube and on the vessel head surface. No corrosion was noted on the head surface.
As discussed in Ref. 2, a dry film of boron is not considered to be a corrosion threat to carbon steel materials. Thus there is no concern with leaving this thin film of boron on the head surface. Condition Evaluation Report, CER 02-1189 was written to address this condition and document the Engineering evaluation.
After the video inspection, Quality Control inspection personnel inspected the top surface of the reactor vessel head with particular attention at VHPs #27 and #47. This inspection was performed from the crane looking down on the vessel head assembly. No signs of boric acid residue were found on the top surface of the head insulation or at the top of the CRDM and conoseal housings.
Based on this, it is likely that the leakage occurred between the second and third refueling outages at penetration 47 (conoseal) as noted in our 15 day response (Reference 1).
The conoseal connections were modified in the fourth refueling outage with no leakage observed since.
The boron deposits are all consistent with leakage at relatively low temperatures. Each deposit is a thin film that has uniform thickness, indicating that the leakage was allowed to trickle and dry. This would indicate that the leakage occurred during shutdown conditions where the metal temperatures were relatively low and the boron concentrations were relatively high. In contrast, a leak at higher temperatures would evaporate quickly when contact was made with the hot surfaces, leaving a buildup at that point of contact instead of a uniform film.
Dirt, Debris, and Miscellaneous Comments
- 1. Insulation collars on several unidentified tubes were not fully flush with the bottom of the insulation. This is considered a cosmetic item and no corrective action is needed.
- 2. Small amounts of debris (dust, dirt, etc.) adjacent to several of the tubes and on the general area of the vessel head were noted. This debris is small in size and is not considered to be a concern. Most of this debris had accumulated on the uphill side of the tubes. None of these accumulations are considered large enough to conceal any boric acid deposits.
Document Control Desk Letter Attachment 0-C-02-0703 RC-02-0115 Page 3 of 8
- 3. In addition to this small debris, a nail, washer, bolt, and lock-washer were seen on the video. These items are not a concern due to their size and weight (cannot cause any damage to the head). The area on the top of the head is encapsulated by the insulation with no forced air flow to move the objects.
- 4. No signs of pitting or corrosion were noted on any of the tube surfaces or on the surface material of the vessel head.
Document Control Desk Letter Attachment 0-C-02-0703 RC-02-0115 Page 4 of 8 TABLE REACTOR VESSEL HEAD PENETRATION RESULTS Boric Acid Inspection Remarks Other Remarks 1
Possible evidence of very slight boron deposit
- 1. Small amount of debris around the tube.
(dried trickle) on the tube. Deposit was a dried
- 2. Insulation collar around the tube is not fully thin film that originated from above the flush with the insulation.
insulation and did not reach the vessel head.
2 No boron deposits were observed.
- 1. Small amount of debris around the tube.
- 2.
Insulation collar around the tube is not fully flush with the insulation.
3 Evidence of very slight boron deposit (dried
- 1. Slight amount of debris.
trickle) on the tube. Deposit was a dried thin
- 2.
Washer on vessel head next to the tube.
film that originated from above the insulation and did not reach the vessel head.
4 Evidence of very slight boron deposit (dried No debris noted.
trickle) on the tube. Deposit was a dried thin film that originated from above the insulation and did not reach the vessel head.
5 No boron deposits were observed.
Small amount of debris around tube.
6 No boron deposits were observed.
- 1. Small amount of debris around the tube.
- 2.
Insulation collar around the tube is not fully flush with the insulation.
- 3.
Nail found between this tube and tube 10.
7 No boron deposits were observed.
No debris.
8 Evidence of very slight boron deposit (dried Small amount of debris around the tube.
trickle) on the tube. Deposit was a dried thin film that originated from above the insulation and did not reach the vessel head.
9 Evidence of very slight boron deposit (dried
- 1. Small amount of debris around the tube.
trickle) on the tube. Deposit was a dried thin
- 2. Possible piece of steel wool coming out from film that originated from above the insulation the insulation.
and did not reach the vessel head.
10 No boron deposits were observed.
- 1. Small amount of debris on the uphill side of the tube.
- 2.
Nail found between this tube and tube 6.
11 Evidence of very slight boron deposit (dried Small amount of debris.
trickle) on the tube. Deposit was a dried thin film that originated from above the insulation and did not reach the vessel head.
12 Evidence of very slight boron deposit (dried
- 1. Small amount of debris around the tube.
trickle) on the tube. Deposit was a dried thin
- 2.
Piece of steel wool coming out between film that originated from above the insulation collar and insulation.
and did not reach the vessel head.
13 No boron deposits were observed.
Slight amount of debris on uphill side of tube.
14 Evidence of very slight boron deposit (dried No debris.
trickle) on the tube. Deposit was a dried thin film that originated from above the insulation and did not reach the vessel head.
Document Control Desk Letter Attachment 0-C-02-0703 RC-02-0115 Page 5 of 8 TABLE M=3rAPt"*I:O \\/Ir-ClM LrAM DI*rklr-TIrD TItC'kl *I:*
II T
[I lI./-*../..
I '..JI Vl_..J_,
JI...*
L..
I l._./=*L.
I L..I *4L. I I I/"
I I"'..'I 'I I [ *
.t.Jf-J Boric Acid Inspection Remarks Other Remarks 15 Evidence of very slight boron deposit (dried No debris.
trickle) on the tube. Deposit was a dried thin film that originated from above the insulation and did not reach the vessel head.
16 No boron deposits were observed.
Small amount of debris on the uphill side of the tube.
17 No boron deposits were observed.
- 1. Surface scratch at base of tube.
- 2.
Small amount of debris around tube.
18 No boron deposits were observed.
No debris.
19 Evidence of very slight boron deposit (dried
- 1. Small amount of debris on the uphill side of trickle) on the tube. Deposit was a dried thin the tube.
film that originated from above the insulation
- 2. Insulation collar around the tube does not and did not reach the vessel head.
appear to be flush with the insulation.
20 No boron deposits were observed.
- 1. Small amount of debris around the tube.
- 2.
Possible slight scratch on tube surface.
21 Evidence of very slight boron deposit (dried
- 1. Housing appears to have a slight surface trickle) on the tube. Deposit was a dried thin scratch.
film that originated from above the insulation
- 2.
Small amount of debris around tube and did not reach the vessel head.
22 No boron deposits were observed.
- 1.
Small amount of debris/dust around tube.
- 2.
Brownish stain on head on the uphill side of the tube.
23 No boron deposits were observed.
Small amount of debris around the tube.
24 Evidence of very slight boron deposit (dried Small amount of debris on the uphill side of the trickle) on the tube. Deposit was a dried thin tube.
film that originated from above the insulation and did not reach the vessel head.
25 No boron deposits were observed.
Small amount of debris noted on the uphill side of tube.
26 No boron deposits were observed.
Small amount of debris/dust around tube.
27 Small amount of boron deposit noted at top of Small amount of debris noted on the uphill side insulation, with trickle down the tube. Thin film of tube.
on the head between this tube and tube 47.
The film was dry, nearly transparent, and uniform in thickness. No evidence of any degradation of the reactor vessel head surface.
Document Control Desk Letter Attachment IEB 2001-01 RC-01-0155 Page 6 of 8 TABLE REACTOR VESSEL HEAD PENETRATION RESULTS Boric Acid Inspection Remarks Other Remarks 28 Evidence of very slight boron deposit (dried Small amount of debris around the tube.
trickle) on the tube. Deposit was a dried thin film that originated from above the insulation and did not reach the vessel head.
29 No boron deposits were observed.
Small amount of debris around the tube.
30 Evidence of boron deposit on the tube. Deposit No debris.
was a dried film that originated from above the insulation and did not reach the vessel head.
31 No boron deposits were observed.
Small amount of debris around the tube.
32 No boron deposits were observed.
Small amount of debris around the tube.
33 No boron deposits were observed.
- 1. No debris noted.
- 2. Possible small scratches on the tube.
34 No boron deposits were observed.
35 No boron deposits were observed.
Small amount of debris on the uphill side of the tube.
36 Evidence of very slight boron deposit (dried Small amount of debris on the uphill side of the trickle) on the tube. Deposit was a dried thin tube.
film that originated from above the insulation and did not reach the vessel head.
37 No boron deposits were observed.
Piece of debris (metal sliver) at base of tube.
38 Evidence of very slight boron deposit (dried Small amount of debris on the uphill side of the trickle) on the tube. Deposit was a dried thin tube.
film that originated from above the insulation and did not reach the vessel head.
39 No boron deposits were observed.
Small amount of debris around the tube.
40 No boron deposits were observed.
- 1. Slight amount of debris.
- 2. Lockwasher on vessel head next to the tube.
41 No boron deposits were observed.
Small amount of debris on the uphill side of the tube.
42 Boron noted at top insulation around the tube, No debris.
but no boron noted on tube.
43 No boron deposits were observed.
View was obstructed by insulation. No debris was noted.
44 Not identified on video inspection.
N/A 45 No boron deposits were observed.
Slight amount of debris.
46 No boron deposits were observed.
Dust/debris around tube 47 Small amount of boron deposit noted at top of No debris.
insulation, with trickle down the tube. Thin film on the head between this tube and tube 27.
The film was dry, nearly transparent, and uniform in thickness. No evidence of any degradation of the reactor vessel head surface.
Document Control Desk Letter Attachment IEB 2001-01 RC-01 -0155 Page 7 of 8 TABLE REACTOR VESSEL HEAD PENETRATION RESULTS Boric Acid Inspection Remarks Other Remarks 48 No boron deposits were observed.
Video inspection did not show the bottom of the tube.
49 No boron deposits were observed.
View was obstructed by insulation. No debris was noted.
50 No boron deposits were observed.
View was a distant shot - small amount of debris around the tube.
51 No boron deposits were observed.
View was a distant shot - small amount of debris around the tube.
52 No boron deposits were observed.
Small amount of debris around the tube.
53 No boron deposits were observed. (Conoseal No debris.
tube) 54 No boron deposits were observed.
View was obstructed by insulation.
55 No boron deposits were observed.
No debris.
56 No boron deposits were observed.
View was obstructed by insulation. No debris was noted.
57 No boron deposits were observed.
View was obstructed by insulation. No debris was noted.
58 Evidence of very slight boron deposit (dried No debris.
trickle) on the tube. Deposit was a dried thin film that originated from above the insulation and did not reach the vessel head.
59 No boron deposits were observed.
Video inspection did not show the bottom of the tube.
60 No boron deposits were observed.
No debris.
61 No boron deposits were observed.
No debris.
62 No boron deposits were observed.
View was a distant shot - small amount of debris around the tube.
63 No boron deposits were observed.
View was a distant shot - small amount of debris around the tube.
64 No boron deposits were observed.
View was obstructed by insulation. No debris was noted.
65 No boron deposits were observed.
View was obstructed by insulation. No debris was noted.
Vent Pipe No boron deposits were observed.
Small bolt laying next to vent piping penetration.
Document Control Desk Letter Attachment IEB 2001-01 RC-01 -0155 Page 8 of 8 Reference
- 1.
PWR Materials Reliability Program Response to NRC Bulletin 2001-01 (MRP-48),
EPRI, Palo Alto, CA: 2001. 1006284.
- 2.
Boric Acid corrosion Guidebook, EPRI Report TR-1 02748, November 2000
- 3.
Visual Examination for Leakage of PWR Reactor Head Penetrations on Top of RPV Head, EPRI Report TR-1 006296, Revision 1