ML091900426
| ML091900426 | |
| Person / Time | |
|---|---|
| Site: | Oyster Creek |
| Issue date: | 11/11/2008 |
| From: | Conte R NRC Region 1 |
| To: | Richmond J, Darrell Roberts NRC Region 1 |
| References | |
| FOIA/PA-2009-0070 | |
| Download: ML091900426 (14) | |
Text
Sarah Rich From: Richard Conte Sent: Tuesday, November 11, 2008 8:12 PM To: Darrell Roberts; John Richmond
Subject:
RE: Oyster Creek - Do.we need to notify the ASLB?
Attachments: OC PNO-Nov2008_Rev0_Drywell.doc; OC 2008 Outage Comm Plan Rev 1.doc See attached "summary document" in the form of a PN and the associated Comm Plan.
John will be reviewing for accuracy and brevity. Hope this helps for your brief. [ ] areas I am unsure of.
Not sure how much time we have for Wednesday morning but we need to. leave by 900am for Beaver and I will have a cell phone with a speaker on it - we can be a part of brief if you desire.
From: Darrell Roberts Sent; Tuesday, November 11, 2008 10:57 AM To: Richard Conte; John Richmond
Subject:
FW: Oyster Creek - Do we need to notify the ASLB?
FYI, I may be giving a briefing in your absence on Wed. or setup something where I give a briefing and you guys phone in and listen/assist.
I'm putting together high level talking points on Tuesday and will have for your review early Wed. in the event we are asked to brief Bruce then.
Topics:
- 1. Backgroundon concerns w/ drywell
- 2. Purpose of ongoing inspection - a) review license renewal commitments, b) review Amergen's efforts to evaluate the structural integrity of the drywell
- 3. Drywell shell coating issues identified during this outage, including significance and restart implications; implications on license renewal aging mgmt programs and commitments
- 4. Communications challenges/ legal issues
- 5. Next steps DJR From: Sam Collins Sent: Monday, November 10, 2008 7:46 PM To: Bruce Mallett; Darrell Roberts Cc: Marc Dapas
Subject:
FW: Oyster Creek - Do we need to notify the ASLB?
Bruce, we have been coordinating with NRP. LR and OGC on the need for Board Notification and Darrell has the action to bring the decision to resolutior" We are sensitive to not getting ahead of the licensee with external conclusions on the technical issues-. Ve h6e been reviewing'the technical issues with NRR and completed an extensive conference call with 'the licensee this afternoon (Exelon attendees included Ron D. the Sr.
V.P.and Mike G. Lic. Renewal). Not sure how best to meet your needs for more information, but I suggest we provide you a direct briefing rather than going thru Shawn for~efficiency, your call on the options .... we'd be prepared for Wed. morning if it meets your needs. Sam From: Darrell Roberts Sent: Monday, November 10, 2008 7:29 PM
To: Sam Collins; Marc Dapas Cc: Richard Conte; James Clifford
Subject:
FW: Oyster Creek - Do we need to notify the ASLB?
FYI, Sam and Marc.
I just opened Shawn Williams' email below (Jim C. alerted me to it in the hallway outside Sam's office around 6 0 pm tonight)i]*.. Outside of the Scope Ipnoe to setup adcs 31/plan a discussion
- with Shawn to give him an upaate or tme leakage issue. I'd prefer to use a verbal approach rather than a different one until we finalize and implement a communication strategy/plan.
I'll also talk to Brian H. regarding his views on an additional board nofication (including the timing thereof).
I plan to complete these on Wednesday, 11/12.
DJR From: Shawn Williams Sent: Monday, November 10, 2008 2:59 PM To: Kathy Weaver; Leigh Trocine; Harold Chernoff; Ed Miller; Ronald Bellamy; James Clifford; Darrell Roberts
Subject:
Oyster Creek - Do we need to notify the ASLB?
- All, I informed Bruce Mallett of some leakage at the bottom of the refueling cavity for Oyster Creek and he requested:
(1) More information - Region 1 Action (2) NRR Action: Determine if this is an issue that we need to notify the ASLB because they are in the process of reviewing Oyster Creek for a license renewal.
Shawn Williams Sr. Operations Assistant, OEDO 301-415-1009 2
Received: from R1 CLSTR01 .nrc.gov ([148.184.99.7]) by RI MS01 .nrc.gov
([148.184.99.10]) with mapi; Tue, 11 Nov 2008 20:11:41 -0500 Content-Type: application/ms-tnef; name="winmail.dat" Content-Transfer-Encoding: binary From: Richard Conte <Richard.Conte@nrc.gov>
To: Darrell Roberts <Darrell.Roberts@nrc.gov>, John Richmond
<John. Richmond@nrc.gov>
Date: Tue, 11 Nov 2008 20:11:40 -0500
Subject:
RE: Oyster Creek - Do we need to notify the ASLB?
Thread-Topic: Oyster Creek - Do we need to notify the ASLB?
Thread-Index:
AcIDbrTFV1 kDWB7DSUqQKKIBQroawQAIz9FwAAEBWNAAH9LLgAATalfg Message-ID:
<2856BC46F6A308418F033D973BBOEE72AA54602F6D@R1 CLSTR01.nrc.gov>
References:
<2856BC46F6A308418F033D973BBOEE72AA43A24E29@R1 CLSTR01 .nrc.gov>
In-Reply-To:
<2856BC46F6A308418F033D973BBOEE72AA43A24E29@R 1CLSTRO1. nrc.gov>
Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: yes X-MS-Exchange-Organization-SCL: -1 X-MS-TNEF-Correlator:
<2856BC46F6A308418F033D973BBOEE72AA54602F6D@R1 CLSTR01. nrc.gov>
MIME-Version: 1.0
Preliminary Notification DCS No.: 0500021911XX08 Date: November XX, 2008 PRELIMINARY NOTIFICATION OF EVENT OR UNUSUAL OCCURRENCE PNO-1-08-XXX Facility Licensee Emergency Classification AmerGen Energy Company, LLC Notification of Unusual Event Oyster Creek Alert Forked River, New Jersey Site Area Emergency Docket: 50-219 General Emergency X Not Applicable
Subject:
RESULTS OF IMPLEMENTATION OF OYSTER CREEK LICENSE RENEWAL COMMITMENTS RELATED TO THE CONTAINMENT DESIGN FUNCTION The NRC staff conducted an on-site inspection of AmerGen's actions related to license renewal commitments to be implemented during the 2008 refueling outage at the Oyster Creek Nuclear Generating Station (OCNGS). In particular, the NRC review involved a multi-week inspection of AmerGen's three aging management programs associated with the primary containment (drywell): Containment Metallic Liner Inservice Inspection; Structures Monitoring Program; and Protective Coating Monitoring and Maintenance Program. Observable aspects of other aging management programs were also reviewed: Buried Piping; Non-EQ Electrical Cables and Connections and Inaccessible Medium Voltage Cables; Inspection of Water-Control Structures; One Time Inspection Program; and Metal Fatigue of Reactor Coolant Pressure Boundary. In accordance with the NRC's agreement with the State of New Jersey, State Engineers observed portions of the NRC's staff review. Based on the results of the NRC's inspection activities, the NRC staff found: 1) for the areas sampled by the inspectors, the results of aging management program data gathering indicated proper implementation and no significant adverse conditions;
- 2) there were no safety significant conditions with respect to the primary containment that would prohibit plant startup.
[NOT SURE THIS IS NEEDED AS BACKGROUND: In the mid-1980s, GPU Nuclear (as licensee) identified corrosion of the shell of the OCNGS containment drywell in the sandbed region. Initial licensee actions were not effective in arresting corrosion, and in 1992, all sand was removed from the sandbed region and the accessible exterior surfaces of the drywell shell were cleaned and coated with an epoxy paint. Ultrasonic test (UT) measurements of the drywell shell thickness were taken in 1992 and 1996, and indicated that the corrosion had been effectively arrested. This information was confirmed in the outages for 2006 and this year. ]
On October 24, 2008, OCNGS shut down for a refueling and maintenance outage. Scheduled outage work included the implementation of various license renewal aging management programs using various non-destructive testing such as ultrasonic testing (UT) and visual testing (VT).
With respect to the drywell, the NRC staff inspection throughout the outage focused on:
Preliminary Notification
- 1. Non-destructive examination results of the drywell shell and torus and related AmerGen evaluations.
- 2. The condition of the inside of the drywell, including trenches in the floor, and the outside of the drywell shell in the sand bed region.
- 3. The integrity of the epoxy coating in light of four blisters found in Bay No. 11 and the integrity of the seal joint between the drywell and sandbed region floor in light of the seal separation noted in Bay No. 3.
- 4. The potential impact of water leaking by the strippable coating in the reactor refueling cavity and from various repairs to the containment on the design and licensing bases of the drywell.
On a sampling basis, the NRC staff had the following observations as a result of Amergen's implementation of license renewal commitments for the 2008 refueling outage:
- 1. UT measurements on the drywell met the licensee acceptance criteria and the acceptance criteria are based on the current licensing basis.
- 2. Work repair improved the functionality to the epoxy coating on the outside of the drywell shell in the former sandbed region and enhanced the seals between the drywell and sandbed region floor. Amergen reported that the blistering was expected; they are detectable by VT; the cause, although not specifically known, appeared to be related to molecular interactions through penetration of moisture in the atmosphere through the epoxy coating.
- 3. The strippable coating at a portion of the reactor cavity liner had some delamination causing water to enter the cavity trough and sandbed region (moisture not a flood of water). As a result Amergen enhanced its monitoring for water in the sandbed region; delayed closeout of these areas until after the reactor cavity was drained; and they will be factoring in additional actions for the 2010 outage to determine if there is any appreciable corrosion on the side of the drywell effect by water impingement in the 2008 outage.
Through the implementation of Aging Management Programs, Amergen identified and fixed the problems found in Bay No. 11 and Bay No. 3 of the sandbed region. The degradations on the coating and the potentially degrading seals, however slight, were barrier systems used to protect the drywell, the safety related target for which the barriers exist. The problems identified by the implementation of aging management programs appeared to have had minimal impact on the drywell itself or corrosion rate remained very small.
Based on a review of the technical information, the NRC staff determined that AmerGen has sufficient justification to restart OCNGS.
The State of New Jersey has been notified and no further updates are planned.
This PN is being issued for information only and will not be updated.
ADAMS Accession Number: ML .....................
CONTACT: Richard J. Conte John Richmond (Dnrc.Qov 6ýnrc.qov (610) 337-5183 (610) 337-5XXX
(
G:\DRS\Engineering Branch 1\_LicRenewal\Oyster Creek\2008 OutageXA Comm Plan - OC 2008 Outage Rev 1.doc COMMUNICATIONS PLAN Preliminary Results of Oyster Creek Licensee Renewal Commitment Inspection Goal To effectively communicate the preliminary evaluation results of recent Oyster Creek license renewal commitments inspection with particular focus on problems found related to primary containment (drywell) and the imminent reactor restart.
To informing stakeholders of the [document issued - for now preliminary notification] issued by the staff within the ongoing license renewal process.
Key Messages On a sampling basis, the NRC staff had the following observations on the review of the implementation of license renewal commitments for the 2008 refueling outage:
- 1. UT measurements on the drywell met the licensee acceptance criteria and the acceptance criteria are based on the current licensing basis.
2, Work repair improved the functionality to the epoxy coating on the outside of the drywell shell in the former sandbed region and enhanced the seals between the drywell and sandbed
- 3. region floor. coating at The strippable a portion of the reactor cavity liner had some delamination causing water to enter the cavity trough and sandbed region (moisture not a flood of water). As a result Amergen enhanced its monitoring for water in the sandbed region; delayed closeout of these areas until after the reactor cavity was drained; and they will be factoring in additional actions for the 2010 outage to determine if there is any appreciable corrosion on the side of the drywell effect by water impingement in the 2008 outage.
- 4. The problems found during the course of implementation of the various aging management programs for the primary containment had no adverse impact on the structural integrity of the drywell.
- 5. There are no adverse conditions found or as left that precluded restart; and, based on a review of the technical information, the NRC staff determined that AmerGen has sufficient justification to restart the plant.
OF9*CI(XL U(,O 1 $LY - PRW'DECI /NAL INIF 7iMPION
OF 4 Ip U(0/4 Y - PREp(CI U( NAL INIF 1(N Audience / Stakeholders AmerGen (Oyster Creek Nuclear Generating Station)
Senators' DC Offices (Senators Lautenberg & Menendez)
House of Representatives for NJ (Rep. Saxton, Smith, Andrews, Holt, Pallone & Pascrell)
New Jersey Dept. of Environmental Protection Local officials ?
Communication Team Eugene Dacus Office of Congressional Affairs 301.415.3693 Richard Conte Chief, Engineering Branch 1, DRS 610.337.5183 Marjorie McLaughlin State Liaison Officer 610.337.5240 Stephen Pindale Senior Reactor Inspector (acting) 610.337.5116 Diane Screnci Senior Public Affairs Officer 610.337.5330 Neil Sheehan Public Affairs Officer 610.337.5331 Timeline:
Time ACTION Responsible Sequence Organization/Individual T= 0 Hour Document is approved by Region I Management and emailed to RI - Conte Oyster Creek T = 0.5 Hour Call Site VP and Communicate Key Messages RI - Conte/Roberts T = 1 Hour E-Mail Document and communicate key messages to New Jersey RI - McLaughlin T = 1 Hour E-Mail Document and communicate key messages to Local Officials, RI - Bellamy/Alternate if any as determined by DRP BC T= 1 Hour E-Mail Document and communicate key messages to NJ OCA - Dacus Congressional Offices T= 24 Hour + Respond to Media Inquiries - see developed Q&As attached. RI - Screnci/Sheehan OF(ýIcIAIL Uj' OrK* - PREý'CISýbNAIL INIF(RM/UION
O.FIC* A U OpKl- PR ?&CI AL IN/FR ATON License Renewal Background AmerGen submitted a License Renewal Application (LRA) for Oyster Creek on July 22, 2005.
The license renewal team inspection occurred in March 2006; Inspection Report 50-219/2006-007 dated September xx, 2006, documented the inspection results. Among many other areas, the LRA addressed managing the effects of aging for primary containment and in particular for the problem of the the drywell shell corrosion of the shell, primarily in the sand bed region which occurred in the mid-1 980s.
The Atomic Safety and Licensing Board (ASLB) held a hearing on a contention regarding the frequency of planned ultrasonic (UT) inspections of the drywell shell in the sand bed region. On December X, 2007, the ASLB ruled in AmerGen's favor. Citizens (intervenor) appealed this decision to the Commission on January 14, 2008. In May 2008, the Commission requested that the ASLB resolve concerns related to planned 3-D analysis of the drywell shell. The ASLB held oral arguments on September 18, 2008, and responded in a memorandum to the Commission
-on October XX, 2008.
Citizens had another appeal to the Commission related to a July 2008 ASLB decision to deny admitting a new contention on metal fatigue and the issue is under Commission review.
Subsequent Actions Region I issue Inspection Report 50-219/2008-007 - Deadline: December 21?, 2008 NRC Commissioners decide on two ASLB appeals related to renewed license - ?
Region I perform non-outage license renewal inspection - planned for March 9 - 27, 2008 The current operating license for Oyster Creek expires on April 9, 2009.
OFFPC ýIAL USFFyL - PRIEP/kl/ONAL INIFtlee R TIOIN
OFF)X4L U/ $ PREDI,44<AL INF#,4IN Anticipated Questions and Answers Q1: Why issue this document with only preliminary results of an inspection?
Al: Given the continuing interest in the drywell shell, particularly, in the review of the Oyster Creek license renewal application, and the Atomic Safety and Licensing Board (ASLB) hearing and oral argument on this subject, the timely public disclosure of the results of this inspection was determined to be desirable. Also, on November 6, 2008, Amergen and NRC staff made Commission and ASLB board notifications related to problems found during the implementation of certain Aging Management Programs.
Q2: When will the inspection results be final?
A2: The inspection results will be final when issued in Inspection Report 50-219/2008-007. A final exit meeting is planned for November 20, 2008, and the report is due out 45 days from that date on or about January 4, 2008. If possible the report may be issued on or about December 21, 2008.
Q3: What prompted the inspection?
A3: This was a scheduled inspection in accordance with the license renewal process under Inspection Procedure 71003. Generally, the inspection addresses the ability for NRC staff to observe license renewal activities which occur during the refueling outage prior to the period of extended operations and which relate to equipment inaccessible (such as the drywell) during reactor operation.
Q4: How do the preliminary evaluation results affect the license renewal process?
A4: They confirm the completion of commitment made by the applicant (licensee) during the course of the application review and as documented in the NRC's staffs safety evaluation report.
Q5: What are the long term next steps following the inspection, and what is done with the findings?
A5: Preliminarily, there were no findings as defined in our inspection process (NRC Inspection Manual Chapter 0612). A number of observations will be documented as a result of this review.
Q6: Why is the reactor safe to operate with these obervations?
A6: There were no findings of safety significance. Overall the observations comport the fact the commitments were properly implemented by the licensee.
QT. What was found and what are the problems?
37: Two more than minor problems were found that needed to be addressed, evaluated and fxed by Amergen.
First in Bay No. 11, on October 31, 2008, the Amergen reported to the lead inspector that a blister was observed in the epoxy coating in the sand bed region of the drywell in one bay. The blister was very close to the ultrasonic test ("UT") location 11 A (which is on the inside of the OFFIKAL U 076~~-PR iP17 ?ONAL INF 7 M/ION
OF$C* UX(oA§ - PREP(CI/NAL ,NFo 16,ION drywell shell). At the time this was the only blister observed during licensee visual inspection of the coating which appeared to have broken and exhibited a brownish stain. On November 2, 2008, the inspector entered the affected bay and observed the broken blister and three others that were unbroken. Amergen reported that the broken blister was soft to the touch about one quarter of an inch (1/4") in diameter with an approximately six inch long brown stain which was three and one thirty-seconds (3/32) wide and dry to the touch, trailing down from the blister.
Amergen reported that the three (3) other blister were hard and effort was needed to brake them and remove material. [The blisters are akin to paint blisters on an old house some of which look like bumps or bubbles (unbroken) and those peeling away (broken - the epoxy was not exactly peeling away, this is just an analogy).] The material in and around the blisters were removed on November 5 for laboratory analysis; the brownish stain found near the broken blister and inside the unbroken blister was confirmed to be iron oxide or rust from the drywell under the epoxy coating.
Also, as part of the investigation for the observations, Amergen reviewed a videotape taken during the 2006 refueling outage that was taken before returning shielding to the access tunnels specifically cut in the .concrete containment to provide access to the sand bed region of the drywell shell. The same blister with the brownish stain was visible on this videotape taken in 2006 and it was apparently overlooked during that inspection. The video detail was inconclusive as to whether or not the broken blister grew in two years. There was no evidence of coating degradation reported for inspections in 1994 and 1996.
Amergen reported that the blistering was expected; they are detectable by VT; the cause, although not specifically known, appeared to be related to molecular interactions through penetration of moisture in the atmosphere through the epoxy coating. More specifically, they are reviewing causes related to pinholes in the coating allowing moisture in the surrounding atmosphere to penetrate the coating and reach the drywell shell or to osmotic blistering resulting from water at the molecular level traveling through the epoxy and interacting with residual chlorine on the drywell shell from pre-1992 wet sand.
Second, on October 31, 2008, during visual inspections of the moisture seal between the drywell shell and the floor of the sandbed region, AmerGen identified a small area of a brownish stain on the moisture seal [four (4) inch crack in the seal]. Amergen removed the stained section of the moisture seal in order to expose the drywell shell. Only a light coating of corrosion was observed on the seal. AmerGen also identified a number of seal problems during this inspection period in seven of ten bays but this one in Bay 3 had the reddish discoloration near the drywell shell. Behind the seal was apparently "uncured epoxy caulk" which apparently occurred due to improper mixing on initial application. Amergen reported the uncured caulk would have still been able to function as a moisture barrier. The brownish material was later confirmed to be iron oxide or rust and corrosion on the drywell considered by Amergen to be light. The area around the seal including the seal and epoxy coating were repaired.
Q8A: What is the safety significance for these problems?
A8A: Although the coating in the area of the blisters was considered by Amergen to be degraded, it had minimal effect on drywell corrosion based on Amergen calculations on the oxidation rate and UT measurements. Oxidation under the broken blister was estimated to be at 3.4 mils or 0.22 mils per year. For the unbroken blisters, the corrosion rate was estimated at 0.12 mils per year. They also obtained UT information on the thickness of the drywell. near the area of the blisters but on the inside of the drywelL. Amergen reported an average drywell thickness of 750 mils well within the acceptance criteria. The coating is a barrier system designed to protect the drywell, the safety related target for protection from additional substantial corrosion. [A mil is one and one thousandths (1/1000 or .001) of an inch].
OFIXFIL U#'O~KY - PR/EJiECK$ONAL INFOý 4 AIfN
OF14 WAL UXOXY( - PRE4EIPI/ONAL INFy ION All blisters were repaired using compatible epoxy material and the NRC staff had no concerns with the information provided by Amergen and with the left conditions of the epoxy.
The seals that needed to be enhanced and, in particular, the seal in Bay 3 were considered by Amergen to be functional. The brownish stains were confirmed to be iron oxide or rust and the corrosion rate on the drywell appeared to be minimal.
All seals and the epoxy coating were enhanced or repaired using compatible epoxy material and the NRC staff had no concerns with the information provided by Amergen and with the left conditions of the seals.
Q8B: Is there NOT a third problem with the missed observation of a broken blister in 2006 and what is its safety significance?
A8B: Amergen reported that enhanced preparations and training led to the discovery of these problems. While acknowledging the missed observation of a blister in 2006, the NRC staff notes that Amergen exhibited considerable initiative to review their records on the matter and identified the missed observation; and, as noted above, the corrosion rate under a blister broken or not is considered to have a minimal effect on the drywell in between visual inspections.
Q8C: What does this mean for continued operation?
A8C: The size of the blisters was small and evaluated by Amergen to be NOT significant even during the last entire last cycle of operation. The degradations on the coating and the potentially degrading seals, however slight, were barrier systems used to protect the drywell, the safety related target for which the barriers exist. The problems identified by the implementation of aging management programs appeared to have had minimal impact on the drywell itself or corrosion rate remained very small.
Even if one were to view the seal problem and degraded coating involving the blisters as not functional, there was no significant amount of water in the sandbed region during operations (the only source is moisture in the atmosphere surrounding the coating and seals) and during refueling even with leakage past the strippable coating in the refueling cavity as noted during this outage (evidence of moisture NOT a flood).
Q9: What does this mean for license renewal?
A9: The problems found were identified by Amergen through the implementation of several aging management programs which were in place to manage the effects of aging - sand bed region of the drywell shell - this means the programs are effective in identifying important problems before they become more serious.
Commitment 27 in the OCNGS License Renewal Application describes the program for conducting the inspections of the epoxy coating in the sand bed region of the drywell shell.
There will be a 100 percent inspection of the coating in the sand bed region every other refueling outage. The NRC staff has concluded in its SER that the programs in place will provide reasonable assurance that any aging effects will be detected before significant damage occurs to the drywell shell in the sand bed region.
Q10: Why was the coating inspected during this outage?
Q10: As stated above, AmerGen committed to do this inspection in the LRA during this O IALUO /Y-PREEC/ONALINFO ION
OF/1"CýL U*/E O)IiY - PRF_/ECIAONAL INF9( $4 ON outage, which is the last outage prior to entering the period of extended operation.
Qi 1: When will the coating in the sand bed region of the drywell shell be inspected again?
Al 1: The next visual inspection of the coating in the sand bed region of the drywell shell is currently scheduled for every other refueling outage or four years. [ Amergen reports that this frequency will be reviewed and evaluated as a result of observing the blisters during the current inspection. ]
Q12: What has the NRC done in response to these observations?
A12: The NRC Region I staff was on site conducting the license renewal commitment inspection and had been closely following the licensees investigation, including performing an independent inspection of the blister and observation of the removal of the blister. The Region I staff had been in contact with the state of New Jersey and the NRC Headquarters staff. The NRC staff will continue to follow the licensee's investigation.
OFFIlAL U1 OfLY - PRE C*$'NAL INFO! 7 TION
OF*CkIL U# L - PRp/# IONAL INIF( 4N Q13: When will the results of the chemical analysis of the blister be available?
A13: AmerGen obtained some of the lab analysis by November 10, 2008. The requested lab analysis included chemical results on the brownish stain, thickness measurements of each layer of the epoxy coating (e.g., was the coating too thin), volume calculations of the blister cap to back calculate, based on rust volume, how much steel was lost (e.g., how much thinner did the shell get). See the information above in Q 8 A, B and C.
Q14: Can NRC staff provide some context with regard to the blister, i.e., the blister area is a quarter of an inch but the sandbed region of the drywell liner that was coated with epoxy is xx hundred square feet in size?
A14: In Bay-! 1, the total area of surface rust (4 separate spots, very near each other) is about 3/4 inch scquare. Total area of drywell shell steel in sand bed bays is between 600 to 800 feet square; We don't have enough information to estimate the area that's rusted in Bay-3, but the estimate is in units of square inches, not square feet.
Details for Answer # 14 The surface area in the sand bed bays (all 10 bays) is roughly between 600 to 800 square feet (see inspector estimate below). There were 4 small rust spots after excavation, each was no larger than about 1/4 inch in diameter. That equates to a total area of about 3/4 of a square inch.
Areas of sand bed epoxy coating are based on inspector observations and inspector arithmetic (these aren't design numbers). The cavity in the sand bed (when you crawl in and try to stand up) is about 5 ft. the epoxy coating does not go all the way up. The bathtub ring is part way up, then the steel plate surface transitions from very rough (due to previous severe corrosion) to flat. Estimating, there is about 4 vertical feet of coating. The NDE inspection instructions say to inspect each bay from 8 foot to the left to 8 foot to the right, from the tunnel entrance. This allows some inspection overlap between the bays. Once inside a bay, you can crawl around to the next bay, and the next bay beyond, but not all the way around (there is some interference in places). So, each bay is a little less than 16 feet long, times 10 bays, times 4 feet in height.
Q1 5: We understand there was a challenge to keeping water out of the sandbed region. What can you say about that?
Al5: On November 7, 2008, Amergen reported an apparent delamination of the strippable coating applied to the liner of the reactor refueling cavity. It was visually evident over the ensuing weekend in that water did overflow the reactor cavity collection trough and enter the sandbed region (evidence of moisture NOT a flood). There was also increased cavity trough drain leakage estimated at 4-5 gallons per minute.
After the reactor cavity is drained there will be a final inspection of the all 10 sandbed regions for any adverse effects. Amergen confirmed substantial shell thickness margin in the upper regions where some water may have impinged on the drywell surface metal. Amergen plans to add UT measurements in the same area for the 2010 outage to determine if there is any significant corrosion over time (short exposure to water this outage).
Q16: A) Will the UT data collected during this outage regarding the drywell liner will be used as an input for the 3-D finite element analysis AmerGen must perform prior to entering a period of license renewal. Is that the case? B)And, what are the results of this data taken in 2008?
OFFI,IAL U0 O/LY - PRE[OC/#IONAL INFO 1 /TION
oFF,ý(IL U(O" 0N) - PR ED I NAL INFQO O Al 6A: During this outage, AmerGen is taking ultrasonic thickness (UT) measurements of the drywell shell in numerous locations, as required by license renewal commitments. Those UT data values will be used as inputs for the 3-D analysis.
A16B: Independently, the NRC inspection staff is reviewing the technical evaluation reports on the UT data but, based on a review of approved UT data sheets, the measurements were within the established acceptance criteria. The NRC staff also confirmed that the acceptance criteria met the current licensing basis - the 3-D analysis is to confirm margins reflected in the current licensing basis; but, at this point, it is not designed to replace it.
The UT measurements were independent of the on-going coating and moisture barrier seal re-work.
Q1 7: So, what is left to be done on the inspection; why not just exit before startup Al 7: As a part of the inspection process, the inspectors were to review the documentation of results as presented by Amergen. Among documentation for other non-drywell related license renewal commitments, the review is to include a confirmation that:
For Bay 11 Epoxy Coating Problem:
- 1. Amergen visual inspections were adequate to detect blisters by observing rust stains.
- 2. The blistered were repaired
- 3. Inspections performed every four years remain adequate to detect blisters before significant corrosion occurs.
- 4. Current visual inspection procedure, including acceptance criteria, is adequate to perform the intended functions as noted above.
For the Bay 3 Moisture Seal Problem:
- 1. Insignificant amount of material was lost from the drywell shell due to corrosion
- 2. The moisture barrier and drywell coating in the area were repaired
- 3. Current visual inspection procedure, including acceptance criteria, is adequate to perform the intended functions as noted above.
OF(CIAL U; ONY" PREýIC 7 NAL INFOJM(R ON