ML17310A690
| ML17310A690 | |
| Person / Time | |
|---|---|
| Site: | Palo Verde  |
| Issue date: | 10/04/1993 |
| From: | Faulkenberry B NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| To: | Conway W ARIZONA PUBLIC SERVICE CO. (FORMERLY ARIZONA NUCLEAR |
| References | |
| CAL-5-93-04, CAL-5-93-4, NUDOCS 9310130280 | |
| Download: ML17310A690 (14) | |
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UNITED STATES NUCLEAR REGULATORYCOMMISSION REGION Y 1450 MARIALANE WALNUTCREEK, CALIFORNIA94596-5368 QQT 4 1993 Enclosure 3
Docket:
50-528/529/530 License:
NPF-41, NPF-51, and NPF-74 CAL:
5-93-004 Arizona Public Service Company P. 0.
Box 53999, Station 9082 Phoenix, Arizona
.85072-3999 Attention:
Hr. M. F.
Conway Executive Vice President, Nuclear
SUBJECT:
CONFIRMATORY ACTION LETTER:.
M.
CONMAY LETTER DATED SEPTEMBER 29, 1993
'his letter is to confirm the commitments made by you in your letter dated September 29,
- 1993, (Enclosure
- 1) regarding possible axial indications in the upper. region of the tube bundle in Steam Generator 31.
Me recognize the si gnificant efforts you have taken to keep the NRC informed of the status of your investigations and your ongoing commitment to inform the NRC of your progress and results in a. timely manner.
Me accept these commitments.
Additionally, we understand that you will take the following.actions:
1.
You will shutdown Unit 3 for eddy current testing (ECT) inspection of both steam generators after Unit 1 returns to power operation (breaker closure) following the completion of the refueling outage now in progress in Unit 1, but no later than November 26, 1993.
2.'-
You will continue to review the Unit 3 ECT data to identify indications which were not identified in refueling outage 3R3 by bobbin coil ECT.
Although not documented in your September 29, 1993, letter, you will provide a written summary of the results of =this review, and your basis for disposition of all newly identified indications, to the NRC by October 12, 1993.
This data and the experience of the Unit 1
ECT inspection will be used to define the scope of the inspection in Unit 3.
. The final scope of Unit 3 ECT inspection will-be provided to the NRC prior to commencing the inspection.
3.
You will continue to implement the Unit 1 Steam Generator Inspection Plan as described in your letter of September 17, 1993 (Enclosure 2).
4.
You will complete the commitments made in your letter dated July 30, 1993, concerning changes to Emergency Operating Procedures, operator 1200~v'310130280 931004 PDR ADOCK 05000528 P
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- training, and 1 eakage moni toring as a resul t-of the Unit 2 Steam Generator Tube Rupture (SGTR) event.
5.
You will conduct operation of Unit 3 to take advantage of'some of the preventative measures which can be taken to reduce outer diameter stress corrosion cracking (ODSCC) rates.
Specifically,
~
You will operate the unit primarily at 85 percent power to reduce the potential for dryout in the tube bundle.
~
You will conduct periodic power reductions to promote hideout return and allow removal of corroding species by blowdown.
You will reduce T-cold to approximately 555 degrees' to take advantage of the temperature dependence of ODSCC, after analyses are completed to support the temperature reduction.-
Pursuant to Section 182 of the Atomic Energy Act, 42 U.S.C.
- 2232, and 10 CFR 2.204, you are required to:
1.
Notify me immediately if your understanding differs from that set forth above.
2.
Notify me in writing if for any reason you cannot complete the actions specified in your September 29, 1993 letter as clarified above.
3.
Notify me in writing when you have completed the actions addressed in the Confirmatory Action Letter.
Issuance of this Confirmatory Action Letter does not preclude issuance of an Order formalizing the above commitments or-requiring other actions on the part of the licensee.
Nor does it preclude the NRC from taking enforcement action for violations of NRC requirements that may have prompted the issuance of this letter.
In addition, failure to take the actions addressed in this Confirmatory Action Letter may result in enforcement action.
The responses directed in this letter are not subject to the clearance procedures of the Office of Management and Budget as required by the Paperwork Reduction Act of 1980, Pub.
L. No.96-511.
t In accordance with 10 CFR 2.790 of the NRC's "Rules of Practice,"
a copy of this letter and its enclosures will be placed in the NRC Public Document Room.
Sincerely,
Enclosures:
As stated a
en er Regional Admin strator
ceo Hr. Steve Olea, Chief Engineer, Arizona Corporation Commission Hr. James A. Beoletto, Esq., Assistant Council, Southern California Edison Co.
Hr. Charles B. Brinkman, Combustion Engineering, Inc.
Hr. Aubrey Godwin, Director, Arizona Radiation Regulatory Agency (ARRA)
- Chairman, Maricopa County Board of Supervisors Hr. Jack R.
- Newman, Esq.,
Newman 5, Holtzinger P.
C.
Hr. Curtis L. Hoskins, El Paso Electric Company Hr.
Roy P.
Lessey, Jr.,
Esq., Akin, Gump, Strauss, Hauer and Feld Hr. Bradley W. Jones, Esq., Akin, Gump, Strauss, Hauer and Feld Hr.
Ron Stevens, Director, Nuclear Regulatory 5, Industry Affairs
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BERT C.SIMPSON VICE PRESIDENT NUCI.EAR SVPPORT E
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Arizona /gag $eHice Company PA+ QFRbd RJClVAR GENERATING STATION P.O. BOX 52034
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PHOENIX. ARIZONA85072-2034 102-02710-ECS/RAB/JRP October 27, 1993 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Mail Station P1-37 Washington, D.C. 20555
Reference:
Letter number 102-02647, dated September 17, 1993, from W. F. Conway, Executive Vice PresIdent, Nuclear, APS, to USNRC
Dear Sirs:
Subject:
Palo Verde Nuclear Generating Station (PVNGS)
Unit 1 Docket No. STN 50-528 Revised Unit 1 Steam Generator Tube Inspection Plan
, File: 93-056-026 The referenced letter submitted the Steam Generator Tube Inspection Plan for Unit 1 for the fourth refueling outage as required by NRC letter dated August 19, 1993.
Arizona Public Service Comjany (APS) has revised the criteria for eddy current expansion (MRPC) and enclosed with this letter is the revised Steam Generator Tube Inspection Plan for Unit 1. The revisions. are noted by the use of revision bars in the margins.
Should you have further questions, please contact Richard A. Bernier at (602) 393-5882.
Sincerely, ECS/RAB/JRP/rv Enclosure CC:
W. F. Conway B. H. Faulkenberry B. E. Holian J. A. Sloan
STATE OF ARIZONA
)
)ss.
COUNTY OF MARICOPA )
I, E: C. Simpson, represent that I am Vice President Nuclear. Support, that the foregoing document has been signed by me on behalf of Arizona Public Service Company with full authority to do so, that I have. read such document and know its contents, and that to the best of my knowledge and belief, the statements made therein are true and correct.
E. C. Simpson Sworn To Before Me This ~ 7 Day Of f <- J&%'r, 1993.
~- Notary Public My Commission Expires
ENCLOSURE UNIT 1 STEAM GENERATOR TUBE INSPECTION PLAN (REVISED)
I UNIT 1 STEAM GENERATOR'TUBE INSPECTION PLAN (REVlSED).
The Unit 1 steam generator willbe inspected fortube defects using Eddy Current Testing (ECT) technology as opposed to ultrasonic or other NDE methods.'The inspection scope and criteria for scope expansion are described below:
INITIALSCOPE:
~
100% Full Length Bobbin Coil Eddy Current Inspection.
20% hot leg tube sheet and 01H support with Motorized Rotating Pancake Coil (MRPC)..
MRPC the 08H support to.the first vertical support in highest risk arc of approximately 1800 tubes (highest risk arc is based on the Unit 2 pattern of defects).
See Figure 1
~
MRPC the 08H support to the firstvertical support, approximately 570 tubes outside the arc of 1800 tubes.'
Bases:
100% full length bobbin coil ECT provides assurance that a widespread pattern of flaws does not exist.
The MRPC sample at the tubesheet and 01H support assures circumferential cracks are not forming, and the previously noted cracking at'01H is not progressing.
The 1800 tube arc was empirically determined to be
.the highest risk area from Unit 2 eddy current test data, and ifcracks are developing due to the sarrie phenomenon seen in Unit 2 this is
~
where they are expected to be found.
The sample. of 570 tubes outside the highest risk area provides confidence that cracks are not developing outside the highest risk area.
CRITERIA FOR EDDY CURRENT EXPANSION MRPC:
~
For each tube with a hot leg "I" bobbin indication (NQI, DSI, DTI, BLI, and PLI)', conduct MRPC of the indication area.
A selected portion of these tubes (34 tubes in S/G 11 and 22 tubes in S/G 12) will be examined by MRPC from the 08H support to the first vertical support.
NQI - Non-Quantifiable Indication; DSI - Distorted Support Signal with Indication; DTI-Distorted Top of Tubesheet with Indication; BU - Baseline Indication; PLI - Possible Loose Part with Indication.
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Bases..
MRPC is required to resolve what "I" code indications are.
In the interest of increasin'g the data base each time. an "I" code indication is examined with MRPC, the 08H support to the first vertical support will also be examined in the selected portion to increase the data base at this elevation.
~
Treat the arc of 3800 tubes as the area of interest.
. o lf less than 1% (1-17 tubes) of the MRPC sample has NBI axial midspan flaw(s) conduct a 6% (228 tubes) expansion with MRPC from the 08H support to the first vertical support.
ln all cases a five tube buffer willbe maintained, from the NBI
. tube.
o If1% (18 tubes) or more of the sample has NBI axial midspan flaws MRPC the entire area of interest from the 08H.support to the first vertical support.
Bases:
The Unit 2 ECT data has shown the Unit 2 failure mechanism to be limited to an analytically determined arc of approximately 3800 tubes where thermal-hydraulic conditions can create an aggressive chemical environment.
By treating the susceptible,area separately, we can apply Technical Specification methodology to MRPC. and establish expansion criteria that zeroes in on the area at risk.
e area outside. the arc of 3800 tubes is treated independently.
rg o
If one or more tubes are discovered to have an NBI axial indication, MRPC the 08H support to the first vertical support in a 6% sample of the area outside the arc (433 tubes) including surrounding tubes until a buffer zone of five tubes is established.
Use the results from this sample to define an area of interest and determine what if any further expansions should be done.
o Define areas of interest if a pattern of NBI flaws develops..
Bases:
The selection of a 6% sample expansion is analogous to Technical Specifications Table 4.4-2. The results of the 6% sample will be used to identify if a pattern exists so that the area at risk will be examined.
2 of 4
4
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Any circumferential crack at the tubesheet triggers a 100% MRPC of the tubesheet area.
SECONDARY SIDE INSPECTION:
Avisual examination of one steam generator secondary side willbe conducted by looking through the manway to determine whether resin has entered the generators, with further actions being based on the results of that inspection.
During the current outage, APS will be installing handholes in the secondary side of the Unit 1 steam generators.
An inspection willbe conducted of the accessible areas of the tubesheet in each steam generator, in conjurlction with the handhole installation.
STEAM GENERATOR TUBE PULLING:
Preparations will be made for tube pulling as a contingency.
However, the decision to pull tubes from Unit 1 steam generator(s) will depend on the eddy current test results.
The plans regarding this contingency are presented below.
Tube pulls will only be done to determine the root cause of failure for significant failure mechanisms not consistent with known phenomenon.
lftube pulls occur, up to two tubes will be selected that satisfy as many of
.the following objectives as possible:
h' Tubes which appear to show failure to comply with Regulatory Guide 1.121
, o Confirm burst test'correlation o
Gather ECT detectability data o
Gather growth rate data o
Support MRPC flaw sizing effort.
3of4
ADVANCEDlNSPECTlON TECHNOLOGY:
Conam will be the vendor used to conduct ECT in the Unit 1 outage.
Various technical advances will be used to explore methods to increase the resolution and speed of ECT inspection.
These include:
~
Multiple MRPC probes will be used to allow simultaneous testing of up to four tubes.
~
Rotating field MRPC probe may be tested, but not used for primary data collection.
t' High speed MRPC probes willbe tested, and may be used for primary data collection.
o Bobbin inspection from the cold leg side will be conducted simultaneously with MRPC inspection from the hot leg side.
4of4
Enclosure 5'yle
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O Cp 4p*yW UNITED STATES NUCLEAR REGULATORYCOMMISSION REGION V 1+0 MARIALANE WALNUTCREEK, CAUFORNIA94596-5368 NOVOS <993 Docket:
50-528/529/530 I
License:
NPF-41, NPF-51, and NPF-74 CAL:
5-93-004 (Revised)
Arizona Public Service Company P. 0.
Box 53999, Station 9082 Phoenix, Arizona
'5072-3999 Attention:
Mr. M. F.
Conway Executive Vice President, Nuclear
SUBJECT:
REVISED CONFIRMATORY ACTION LETTER:.
E.
SIMPSON LETTER DATED OCTOBER 27, 1993 This letter is to confirm the revised commitments made in the Arizona Public Service Company (APS) lett'er dated October 27, 1993 '(Enclosure 1).
The ',
October 27, 1993, letter modified the criteria for expanding the eddy current testing of certain tubes in the Unit 1 steam generators.
The criteria for eddy current testing expansion were originally described in your September 17, 1993, letter to the NRC.
'e understand that the other provisions of the September 29, 1993, letter remain in effect, as well as the actions stated in our October 4, 1993,,letter to APS {Enclosure 2 - original Confirmatory Action Letter).
Therefore, our October 4; 1993, letter is'till applicable, with the exception of Item 3,
.which is replaced by the commitment that you will now implement the Unit 1 Steam Generator Inspection PIlan as described in the APS letter of October 27, 1993.
The proposed change to the Unit 1 'nspection Plan was discussed with the NRC staff on October 14 and 15, 1993.
Pursuant to Section 182 of the Atomic Energy Act, 42 U.S.C.
- 2232, and 10 CFR 2.204, you are required to:
1,.
Notify me immediately if your understanding differs from that set forth above.
2.
3.
Notify me in writing if for any reason you cannot complete the actions specified in your September 29, 1993, letter as clarified above.
Notify me in writing when you have completed the actions addressed in the Confirmatory Action Letter.
Issuance of this revised Confirmatory Action Letter does not preclude issuance of an Order formalizing the above commitments or requiring other actions on the part of the licensee.
Nor does it preclude the NRC from taking enforcement action for violations of NRC requirements that may have prompted the issuance of this letter.
In addition, failure to take the actions
-2
~
addressed in this Confirmatory Action letter may result in enforcement action..
The responses directed in this letter are not subject to the.clearance procedures of the Office of Hanagement and Budget as required by the Paperwork
. Reduction Act of 1980, Pub.
L. No.96-511.
In accordance with 10 CFR 2.790 of the NRC's "Rules of Practice,'
copy of this letter and its enclosures will be placed in the NRC Public Document Room.
Enclosures:
As stated Sincerely,
-(xI~y B. H. Feulkenberry Regional Administrator