ML032720357
| ML032720357 | |
| Person / Time | |
|---|---|
| Site: | Robinson  |
| Issue date: | 09/25/2003 |
| From: | Chandu Patel NRC/NRR/DLPM/LPD2 |
| To: | NRC/NRR/DLPM |
| References | |
| TAC MC0315 | |
| Download: ML032720357 (30) | |
Text
NRC FORM 658 U.S. NUCLEAR REGULATORY COMMISSION (91999)
TRANSMITTAL OF MEETING HANDOUT MATERIALS FOR IMMEDIATE PLACEMENT IN THE PUBLIC DOMAIN This form is to be filled out (typed or hand-printed) by the person who announced the meeting (ie., the person who issued the meeting notice). The completed form, and the attached copy of meeting handout materials, will be sent to the Document Control Desk on the same day of the meeting; under no circumstances will this be done later than the working day after the meeting.
Do not Include proprietary materials.
DATE OF MEETING The attached document(s), which was/were handed out in this meeting, is/are to be placed O9M/25n03 In the public domain as soon as possible. The minutes of the meeting will be issued in the near future. Following are administrative details regarding this meeting:
Docket Number(s) 50-261 PlantlFacility Name H. B. Robinson Steam Electric Plant, Unit No. 2 TAC Number(s) (if available)
MC0315 Reference Meeting Notice September 15, 2003 Purpose of Meeting (copy from meeting notice)
To discuss CP & L request for relaxation from the NRC order for establishing interim inspection requirements for reactor press. vessel heads at PWRs NAME OF PERSON WHO ISSUED MEETING NOTICE Chandu P. Patel Project Manager OFFICE NRR DMSION Division of licensing Project Management BRANCH Project Directorate II Distribution of this form and attachments:
Docket File/Central File PUBLIC D
)
l NRC FORM 658 (9-1999)
PRINTED ON RECYCLED PAPER This form vas desigrwd using InForms
rip
.4 H. B. Robinson, Unit No. 2 September 25, 2003 e
na Cush" f.aWSW Nuclear i Generation I Group
@~W Progress Energy
- 1.
~~~~~~~~~~~~~~~~~~~~~~~L Agenda
- Introduction
- Historical Perspective And Summary Of Relaxation Request
- Overview Of Technical Basis
- Closing Remarks 2
Progress Energy
,X Introduction
vowel UN I 0.0" 0 Chris Burton Director - Site Operations wC.wfau&
d a"b Progress Energy 3
Historical Perspective And Summary Of Relaxation Request Chuck Baucom Licensing Supervisor 020K..SI AUh
&IT&
&,,Progress Energy 4
Historical Perspective
- Refueling Outage 20 (April 2001)
- Performed qualified bare-metal visual (BMV) examination
- No vessel head penetration (VHP) or head surface degradation identified v Canopy seal leakage identified and repaired
- Reasonable assurance of structural integrity provided until next scheduled inspection
- Actions pre-date issuance of NRC Bulletin 2001 -01 in August 2001 5
i Progress Energy
Historical Perspective
- Refueling Outage 21 (November 2002)
- Performed qualified BMV examination; no VHP or head surface degradation identified v Canopy seal leakage identified and repaired Performed NDE of VHP nozzles v Eddy current of 69 J-groove welds and penetration tube outer diameter surfaces v Eddy current and UT of 17 open penetration tubes from inner diameter surfaces v Eddy current of 45 penetration tubes with thermal sleeves and 7 penetration tubes with part length drive shafts from inner diameter surfaces 6
0 Progress Energy
H1storical Perspective
- Refueling Outage 21 (Continued)
X No evidence of VHP nozzle leakage or PWSCC O
One recordable indication (surface manufacturing process) away from anomaly from high stress area
- BMV and NDE consistent with NRC Bulletins 2001-01 and 2002-02 WActions pre-date issuance EA-03-009 of NRC Order
- Examination coverage evaluated against Order requirements i,.-.
I/N' -6
^I Progress Energy 7
Summary Of Relaxation Request NRC Order EA-03-009 Requires The Following Every Refueling Outage:
- BMV examination of 1 00% of the head surface, AND
- Either:
v UT of each nozzle and an assessment for leakage into the interference fit zone, OR v Eddy current or dye penetrant testing of wetted surface of each J-groove weld and penetration nozzle base material 8
A? Progress Energy
Summary Of Relaxation Request
- Order Response Dated March 3, 2003
- Reviews were in progress to determine if sufficient technical basis existed for relaxation of Order requirements
- Request For Relaxation Of Order Requirements Dated August 15, 2003
- Relief requested for NDE of VHP nozzles and J-groove welds only for Refueling Outage 22 (April 2004) 9 a
Progress Energy
Summary Of Relaxation Request
- Proposed Alternative Applicable Only For Refueling Outage 22 (April 2004)
- BMV examination of visible portions of RPV head surface
- NDE from Refueling Outage 21 with detailed technical analyses supporting operation until RPV head replacement
- RPV Head Replacement During Refueling Outage 23 (October 2005)
(k; 10 4 Progress Energy
Summary Of laxaton Request
- Good Cause For Relaxation Is Based Upon 4Successful examinations from two prior refueling outages oDetailed probabilistic and deterministic analyses support two cycles of operation with known condition of RPV head
- Pressure Boundary Integrity will be maintained until RPV Head Replacement FIJI 11 C Progress Energy
Overview Of Technical Basis II Chris Church Engineering Manager e0
_^mV&
iUsa d
- Progress Energy 12
Technical Basis I H.
B. Robinson Reactor Pressure Vessel Head H. B. Robinson Materials and Fabrication Industry Experience Statistical Analysis of Differential Susceptibility Deterministic Evaluations Probabilistic Evaluations H. B. Robinson Leak Detection Capability Conclusions (FOG 13 4 Progress Energy
H. B. Robinson Reactor Pressure Vessel Head I Cooling air is drawn down through mechanisms and out through ducts
- Head is low-alloy steel 148.9" ID
~4 7.75" base metal thickness 0.218" clad thickness
- 69 VHP nozzles Alloy 600 (SB-1 67)
Alloy 182 Welds 4.001"OD 2.75" ID 14
@ Progress Energy
H. B. Robinson Reactor Pressure Vessel Head 69 VHP nozzles 45 CRDM
/A) 7 Part length CRDM
/
/
0 \\
1 Partlengthremoved&capped
/0
/
o0 0 e 0
11 Capped dummy can 0o 0
0
\\
assemblies 0
0 5 Thermocouple columns 0
0 e
0 0
0 ~0 0
0O0 O
0 52 full and part length 0
0 0 of e0 0
0
/
0 CRDMs have thermal
\\° Goo 0 0 0 0
0 sleeves 00 0
Q Remaining 17 nozzles are 0
a open 000 Head vent nozzle design 0D Ns 0
Part Length Nozzles 0
Capped Nozzles (0 Theamocouple Nozzles
(* 15 By Progress Energy
H. B. Robinson Materials and Fabrication Review of performed materials and fabrication processes was by Westinghouse and DEI Purpose was to identify differences in the materials and fabrication processes that could explain why Robinson has not seen PWSCC even though it is categorized as "high susceptibility" based on EDY x The materials processing and fabrication reviews showed no unusual processes or repairs that would be expected to increase PWSCC susceptibility of the RPV head penetrations or welds FAG Progress Energy 16
H. B. Robinson Materials and Fabrication Some material and fabrication processes used in the construction of the H. B. Robinson RPV head allows good ability to detect leakage during BMV exam, may contribute to lower residual stresses, and lower PWSCC susceptibility Use of a minimum interference fit, individual nozzle/bore size matching, and acetone/dry ice bath shrink fit techniques Smaller weld sizes in Robinson head relative to some other heads
- o Thicker nozzle tube walls compared to some other PWR closure heads Tubes were produced using a process that is expected to produce large grain size and predominantly intergranular carbides. This material would be expected to have lower PWSCC susceptibility than material with small grain size and predominantly intragranular carbides 17 agrd
Industry Experience I Evaluation of nozzle inspection results compiled by the MRP shows that there is a significant difference in frequency of PWSCC for different fabrication and material categories
- Reactor vessels fabricated by CE with CRDM nozzles fabricated from material supplied by Huntington Alloys showed best performance against other reactor vessels and nozzle materials H. B. Robinson RPV head fabricated by CE with Huntington CRDM nozzle material Good industry performance in this category is consistent with lack of PWSCC detected by RO-21 nozzle and weld inspection There has been only I plant (Millstone 2) with PWSCC reported in a vessel fabricated by CE with Huntington Alloys material Three operating plants have Robinson heats of Huntington material with no reported problems (Salem 1, Indian Point 2, Diablo Canyon 1). Note that Millstone 2 has a different heat than Robinson (g&
18 I Progress Energy
Industry Experience I
Only 0.7% of CE penetrations have shown reportable indications 18.72% of non-CE penetrations have shown reportable indications Only 9 of 1332 penetrations in CE-fabricated vessels inspected by UT/ET have shown reportable indications No detected leaks or weld cracks in CE vessels
- Leaker
- Cracked (not leaker)
- UT/ET wI No Cracks 1400{
CRDMICEDM Inspection Results 1200 Co C.2 CD z
1000 800 600 400 200 0
CE Vessels Non-CE Vessels d ib Inspection results through Spring 2003 mi4 Progress Energy 19
Industry Experience Only 0.6% of Huntington nozzles have shown reportable indications 6.0% of non-Huntington nozzles have shown reportable indications Only 4 of 642 Huntington material nozzles inspected by UT/ET have shown reportable indications
- Leaker N Cracked (not leaker)
- UT/ET w/ No Cracks 140 0,
CRDM/CEDM Inspection Results 03 4 1200 1000 0
z z
800 600 400 No detected leaks from Huntington material nozzles 200 0
Huntington Tubes Non-Huntington sea Inspection results through Spring 2003 Progress Energy 20
Statistical Analysis of Differential Susceptibility 1,
I Is mg I
The fact that RPVs manufactured by CE with Huntington Alloys nozzle material appear less prone to PWSCC than other vessel heads with similar operating history was statistically assessed B&W designs, CE fabricated non-B&W designs, and plants that have neither, in addition to EDY, were analyzed The results indicate the H. B. Robinson head at current EDY is 10% less likely to leak than the "neither' category and 35% less likely to leak than B&W designs This analysis shows that may lead to substantially PWSCC in plants with H.
d ib ignoring other factors beyond EDY overestimating the likelihood of B. Robinson-like attributes 21 3 Progress Energy
Deterministic Evaluations Westinghouse and DEI performed deterministic evaluations of flaw propagation and crack growth in H. B. Robinson VHPs and associated J-groove welds Conservative cases analyzed demonstrate incipient leakage is not predicted to occur in less than 3 years Exception was DEI analysis of J-groove welds Probability of leak remains low Deterministic evaluations for boric acid wastage also concluded that BMV examinations performed every refueling outage preclude rapid boric acid wastage of the low-alloy steel material of the RPV head 22 C
Progress Energy
Probabilistic Evaluations Both Westinghouse and DEI evaluations utilize conservative assumptions for probability of detection, pre-existing flaws, and flaw propagation Westinghouse concluded that the probabilistic analysis provides quantitative confidence that; Leaks and critical flaws will not be generated Projected plant risk increase will be within acceptable limits over the proposed interval between inspections DEI concluded the analytical resulting maximum increment to core damage frequency (CDF) of 1 E-7 per year is an order of magnitude lower than the 1 E-6 criterion recommend by Regulatory Guide 1.174 for risk-informed decision making 23 a
Progress Energy
Probabilistic Evaluations I The resultant estimates for leakage show there is a low probability (on the order of 5% per year) that a leak will occur Additionally, a probabilistic head wastage model shows that the potential for boric acid corrosion of the low-alloy steel head material, given the BMV examination to be performed in RO-22, has an insignificant effect on CDF In summary, two independent probabilistic analyses conclude the proposed relaxation is within regulatory guidelines for ensuring no undue risk to the health and safety of the public 24
@ Progress Energy
H. B. Robinson Leak Detection Capability H. B. Robinson has several programs to detect leaks Boric Acid Control Program RCS inspections at the start and end of each refueling outage RCS leakage surveillance every 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> v Indication of leakage is provided by several factors, including reactor coolant drain tank level, pressurizer relief tank, containment air particulate and noble gas monitors, and containment sump level v Investigation commences if the identified leak rate exceeds 0.3 gpm or the unidentified leak rate exceeds 0.1 gpm Heightened sensitivity to leaks by maintaining the rate of unidentified leakage very low v The average unidentified leak rate after RO-21 (Fall 2002) was 0.03 gpm and it is currently negligible 25
§ Progress Energy
Conclusions N
Two successive qualified bare metal visual examinations showed no evidence of penetration leakage
-*Comprehensive NDE exams of CRDM penetrations and J-groove welds performed in RO-21 identified no reportable indications due to PWSCC A review of H. B Robinson's materials and fabrication techniques indicate several factors which may provide a lower susceptibility to PWSCC Experience to date with vessels fabricated by CE and with Huntington Alloys nozzle material has been excellent 26 O
Progress Energy
Conclusions
- Statistical analysis demonstrates that factors in addition to time and temperature significantly influence the likelihood of PWSCC Deterministic and probabilistic analyses indicate the likelihood of any PWSCC-induced damage to the RPV head during the extended inspection interval is extremely low, and well within the bounds of Reg. Guide 1.174 RCS leak rates are currently very small. Any change in leak rate is carefully evaluated and actions are taken to resolve these changes Bare metal visual examination during the next refueling outage (RO-22) will detect through wall leaks before head wastage can occur
%ungi 27 i
Progress Energy
Conclusions RPV head replacement is scheduled for RO-23
- Taken together, these complementary approaches support the conclusion that the one-time extension of the non-visual NDE inspection will not result in any measurable impact to operational safety Based upon the above, good cause is demonstrated for relaxation of Order requirements 28
§ Progress Energy
Closing Remarks Chris Burton Director - Site Operations d
- Progress Energy 29