ML12096A052
| ML12096A052 | |
| Person / Time | |
|---|---|
| Site: | Peach Bottom  |
| Issue date: | 04/04/2012 |
| From: | Jesse M Exelon Generation Co, Exelon Nuclear |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| TAC ME7538, TAC ME7539 NET-332-01 | |
| Download: ML12096A052 (37) | |
Text
Exelon Nuclear www.exeloncorp.com Exelon.
200 Exelon Way Nuclear Kennett Square, PA 19348 10 CFR 50.90 April 4, 2012 U.S. Nuclear Regulatory Commission ATIN: Document Control Desk Washington, DC 20555-0001
. Peach Bottom Atomic Power Station, Units 2 and 3 Renewed Facility Operating License Nos. DPR-44 and DPR-56 NRC Docket Nos. 50-277 and 50-278
Subject:
Response to Request for Additional Information - License Amendment Request for Use of Neutron Absorbing Inserts in Units 2 and 3 Spent Fuel Pool Storage Racks
References:
- 1) Letter from M. D. Jesse (Exelon Generation Company, LLC) to U.S. Nuclear Regulatory Commission, "License Amendment Request - Use of Neutron Absorbing Inserts in Units 2 and 3 Spent Fuel Pool Storage Racks," dated November 3, 2011
- 2) Letter from J. D. Hughey (U.S. Nuclear Regulatory Commission) to M. J.
Pacilio (Exelon Generation Company, LLC), "Peach Bottom Atomic Power Station, Units 2 and 3 - Supplemental Information Needed for Acceptance of Requested Licensing Action RE: Use of Neutron Absorbing Inserts in Units 2 and 3 Spent Fuel Pool Storage Racks (TAC NOS. ME7538 and ME7539),"
dated December 14, 2011
- 3) Letter from M. D. Jesse (Exelon Generation Company, LLC) to U.S. Nuclear Regulatory Commission, "License Amendment Request - Use of Neutron Absorbing Inserts in Units 2 and 3 Spent Fuel Pool Storage Racks," dated December 22, 2011
- 4) Letter from J. D. Hughey (U.S. Nuclear Regulatory Commission) to M. J.
Pacilio (Exelon Generation Company, LLC), "Peach Bottom Atomic Power Station, Units 2 and 3 - Request for Additional Information Regarding License Amendment Request for Use of Neutron Absorbing Inserts in Units 2 and 3 Spent Fuel Pool Storage Racks (TAC NOS. ME7538 and ME7539),"
dated March 12, 2012 In the Reference 1 letter, Exelon Generation Company, LLC, (Exelon) requested a proposed change to modify the Technical Specifications (TS) to include the use of neutron absorbing spent fuel pool rack inserts for the purpose of criticality control in the spent fuel pools at Peach Bottom
Response to Request for Additional Information - License Amendment Request Spent Fuel Pool Rack Inserts April 4, 2012 Page 2 Atomic Power Station (PBAPS), Units 2 and 3. In Reference 2, the U.S. Nuclear Regulatory Commission requested additional information as part of the acceptance review of this License Amendment Request. Reference 3 was our response. In Reference 4, the U.S. Nuclear Regulatory Commission requested additional information. Attached is our response.
Exelon has reviewed the information supporting a finding of no significant hazards consideration and the environmental consideration provided to the U.S. Nuclear Regulatory Commission in Reference 1. The additional information provided in this submittal does not affect the bases for concluding that the proposed license amendment does not involve a significant hazards consideration. In addition, the additional information provided in this submittal does not affect the bases for concluding that neither an environmental impact statement nor an environmental assessment needs to be prepared in connection with the proposed amendment.
There are no regulatory commitments contained in this submittal.
Should you have any questions concerning this letter, please contact Tom Loomis at (610) 765-5510.
I declare under penalty of perjury that the foregoing is true and correct. Executed on the 4th day of April 2012.
Respectfully, Michael D. Jesse Director, Licensing and Regulatory Affairs Exelon Generation Company, LLC Attachments: 1) Response to Request for Additional Information - License Amendment Request to Use Neutron Absorbing Inserts
- 2) NET-332-01, Inspection and Testing of BORAL and Fast Start Surveillance Coupons from the LaSalle County Units 1 and 2 Stations" cc: USNRC Region I, Regional Administrator USNRC Senior Resident Inspector, PBAPS USNRC Project Manager, PBAPS R. R. Janati, Bureau of Radiation Protection S. T. Gray, State of Maryland
ATTACHMENT 1 Response to Request for Additional Information - License Amendment Request to Use Neutron Absorbing Inserts
Response to Request for Additional Information - License Attachment 1 Amendment Request to Use Neutron Absorbing Inserts Page 1 Question:
RAI-06: Please confirm that the qualification testing acceptance criterion for the manufactured panels is greater than 0.0105 g/cm2 given that the qualification testing acceptance criteria is listed as greater than 0.0087 g/cm2 on page 3-5 of NET-259-03 Rev 5 (Attachment 5 of the LAR dated November 3, 2011).
Response
The purpose of NET-259-03 is to demonstrate that aluminum/B4C sheet produced from direct chill (DC) cast rolling billets supplied by Rio-Tinto Alcan Inc. is a suitable material for use as a neutron absorber in spent nuclear fuel storage applications and, in particular, that it is a suitable material from which to fabricate NETCO-SNAP-IN neutron absorber inserts. The first application of this material for a NETCO-SNAP-IN neutron absorber insert was for the LaSalle County Station (LCS) project. Table 3-1, on page 3-5 of NET-259-03 Rev. 5 identifies the LCS project B-10 areal density acceptance criterion (>0.0087 g/cm2).
The NETCO commercial grade dedication process for the Peach Bottom Atomic Power Station (PBAPS) project requires that the measured B-10 areal density meets or exceeds 0.0105 g/cm2.
NETCO Special Engineering Procedure SEP 300019-03, Procedures for NETCO-SNAP-IN Insert Neutron Attenuation B-10 Areal Density Coupon Acceptance Testing for Peach Bottom Units 2 and 3, Rev. 0, identifies the as-manufactured acceptance criterion of greater than or equal to 0.0105 g/cm2.
Question:
RAI-07: Please describe how the 2 rack inserts are selected that will be visually inspected during each insert in-situ inspection per Section 3.9.4.1 of Attachment 1 of the LAR.
How will these 2 rack inserts be representative of all inserts in the SFP?
Response
As described in Section 3.9.4.1 of Attachment 1 of the LAR, two rack inserts will be selected and visually inspected in place for physical material deformities every two years for the first ten years and then every four years. The selection of the two inserts will be based on bounding operating conditions for all pool inserts. The parameters that could affect the material properties of the insert are fuel pool water chemistry, pool temperature, and radiation exposure received due to proximity to irradiated fuel.
The impact of water chemistry variations on the Rio-Tinto Alcan composite material is described in Section 5.3 of NET-259-03, Rev. 5 (Attachment 5 of the LAR dated November 3, 2011). In the PBAPS spent fuel pools, water chemistry and temperature do not vary among the rack locations throughout the pools. Substantial spent fuel pool water mixing is assured by a continuous circulation through each spent fuel pool by the spent fuel pool cooling system.
Therefore, each insert location is exposed to essentially the same water chemistry and water temperature. There is no worst case or bounding fuel cell location for water chemistry or temperature.
Response to Request for Additional Information - License Attachment 1 Amendment Request to Use Neutron Absorbing Inserts Page 2 The inserts chosen for inspection will be those with the highest radiation exposure received from discharged fuel so that the radiation effects will bound all other inserts in the pool. PBAPS will designate two rack cells as test locations so that discharged fuel with the highest burnup can be placed in the cells. Placing discharged fuel with the highest burnup in the test cells after every refueling will ensure they are bounding with respect to radiation exposure. The proposed strategy will not adversely impact B.5.b fuel pool loading requirements. Placing the highest exposed discharged fuel in the test locations will be administratively controlled.
Question:
RAI-08: Please clarify whether the insert that will be removed and inspected every 10 years (per Section 3.9.4.2 of Attachment 1 of the LAR) will be re-inserted in the racks, and how the one rack insert selected is going to be representative of all the inserts in the SFP.
Response
Inserts removed from service for inspection will not be reinstalled. The removal process and handling of inserts creates the potential for insert damage. In addition, once an insert is removed from service for inspection, it is exposed to the ambient air environment and would no longer provide a representative sample for future inspections. Thus, removed inserts will be replaced with new inserts.
As described in Section 3.4.2 of Attachment 1 of the LAR, minimal service wear is expected on the inserts because adequate clearance is ensured by design between the fuel assembly and the insert. Tests with drag gauges in cells that have an insert installed have shown no resistance from contact with the inserts and, therefore, no means of generating additional wear.
To ensure there is no detrimental service wear that could adversely impact the insert function, an insert will be removed from its rack cell location and will be inspected for thickness along its length at several locations (see Section 3.9.4.2 of the LAR). This collection of measurements will then be compared with the as-built thickness measurements along the insert length to determine whether it has sustained uniform wear over its service life.
If service wear on an insert was to occur, it would occur as the result of the insertion and removal of a fuel assembly in and out of the rack cell. The rack cell with the most fuel assembly insert and removal cycles will represent a bounding case for all the pool rack cells. The number of fuel assembly inserts and removals in and out of each rack cell containing a NETCO-SNAP-IN rack insert will be tracked and documented. The insert in the rack cell that has the most fuel move cycles will be the insert chosen for inspection. Inspecting the insert that had the most fuel assembly movements will ensure it is bounding with respect to wear for all inserts in the pool.
Question:
Page 15 of Attachment 1 and page 4-6 of Attachment 5 of the LAR describes an estimated stress relaxation of 50% over 20 years of service for the insert material.
Response to Request for Additional Information - License Attachment 1 Amendment Request to Use Neutron Absorbing Inserts Page 3 RAI-09.1: Please describe how stress relaxation of the inserts will be monitored and the frequency of monitoring. What are the acceptance criteria for stress relaxation?
Describe the maximum amount of stress relaxation allowable.
Response
To monitor the stress relaxation of the inserts, 24 coupons will be installed in the fuel pool along with the inserts. The 24 Bend coupons will be removed and examined for stress relaxation.
As noted in Section 3.9.3 of the LAR submittal, in the first ten years, one Bend coupon will be removed every two years. After the first ten years, one Bend coupon will be removed every four years.
The acceptance criterion for stress relaxation is 50% stress reduction. A relaxation of 50% will maintain greater than 100 lbf retention force.
Per the computation provided in ECR 11-0077, Rev. 3, 40.8 lbf is sufficient to maintain the inserts in their configuration during a seismic event. Accordingly, the maximum stress relaxation allowable is a 79.6% reduction. A relaxation of 79.6% results in a 40.8 lbf retention force.
Question:
RAI-09.2: Please provide the data and justification of the data extrapolation that determined that over 20 years of service would be an estimated 50% stress relaxation.
Response
The basis of the stress relaxation estimate is discussed in Section 4.1 beginning on page 4-6 of NET-259-03, Rev. 5. The data discussed in this section to formulate the basis for stress relaxation is contained in this section and in the following referenced documents:
- 1) K. Farrell, ORNL/TM-13049 Assessment of Aluminum Structural Materials for Service Within the ANS Reflector Vessel, Oak Ridge National Laboratory, August 1995
The data in the Kaufman reference includes time under strain measurements up to 10,000 hours0 days <br />0 hours <br />0 weeks <br />0 months <br />. These data were fitted to a power law model which asymptotically approached 100% as time under strain was increased. The model conservatively predicts the data presented in the reference and was used to extrapolate the expected relaxation at 20 years under strain.
Question:
RAI-10: Please discuss whether the data from the fast start coupon surveillance program at LaSalle (described in Section 3.9.2 of Attachment 1 of the LAR) can be used to inform the use of the Peach Bottom inserts given that the SFP environments may not be identical. Please provide the results of this program.
Response to Request for Additional Information - License Attachment 1 Amendment Request to Use Neutron Absorbing Inserts Page 4
Response
The fast start testing program was intended to identify unanticipated insert material performance issues during the demonstration of the first-of-a-kind use of NETCO SNAP-IN inserts in spent fuel pools. The fast start coupon surveillance program at LCS was intended to ensure that insert material performance was satisfactory prior to full scale project implementation for Exelon.
Based on the satisfactory results at LCS and the similarities of the spent fuel pool water chemistry, the program is not required to be duplicated for PBAPS.
The results of the inspections of the LCS fast start coupons 23 and 24 are contained in report NET-332-01, Rev. 0, Inspection and Testing of BORAL and Fast Start Surveillance Coupons from the LaSalle County Units 1 and 2 Stations" (Attachment 2). There was essentially no change in the Rio-Tinto Alcan composite coupons from their pre-use characterization values.
Report NET-259-03 provides an overall qualification of the insert material for both BWR and PWR spent fuel pool environments at a range of B4C loadings (16-25 volume %) in aluminum which bounds the PBAPS inserts (19% volume).
The LCS and PBAPS spent fuel pool chemistries and temperatures vary day-to-day but, over time, are substantially similar with respect to concentrations of potentially corrosive chemicals and normal operating temperature. The LCS and PBAPS maximum fuel pool temperature licensing limits are 140oF and 150oF, respectively. The normal operating temperature range for the fuel pools at both stations is 70oF-110oF. The chemistry program that governs spent fuel pool chemistry for both plants is the same. The requirements for the Exelon BWR plant spent fuel pool chemistry control program are defined in Exelon procedure CY-AB-120-300, "Spent Fuel Pool." The spent fuel pool chemistry requirements are in accordance with Table E-4 of BWRVIP-190, "BWR Water Chemistry Guidelines - 2008 Revision."
Table 10-1 below provides a comparison of the significant chemistry parameters between LCS and PBAPS over the past 11 months.
Response to Request for Additional Information - License Attachment 1 Amendment Request to Use Neutron Absorbing Inserts Page 5 Table 10 Peach Bottom / LaSalle Spent Fuel Pool Historical Chemistry Date Chloride (ppb) Conductivity (S/cm) Silica (ppb) Sulfate (ppb)
PB2 PB3 LAS PB2 PB3 LAS PB2 PB3 LAS PB2 PB3 LAS Mar 2011 0.76-0.80 1.72-2.15 0.86-1.45 1.01-1.06 1.03-1.07 0.93-1.03 1520-1620 3480-3630 1875-6235 0.30-2.45 0.30-4.91 0.23-0.24 Apr 2011 0.90-1.05 2.20-2.59 1.05-2.17 0.93-1.03 0.98-1.05 0.91-0.95 1480-1780 2860-3640 4020-4409 0.30-1.75 0.30-5.02 0.23-0.73 May 2011 0.32-1.07 0.30-0.51 1.31-1.76 0.81-0.93 0.89-0.95 0.88-0.95 1700-2280 3060-3710 3879-4749 0.30-1.02 0.30-0.82 0.23-0.32 Jun 2011 0.53-0.64 0.60-0.71 0.71-1.17 0.80-0.83 0.84-0.88 0.65-0.86 2390-2680 3490-3580 4850-5807 0.30-0.44 0.30-0.48 0.23-0.25 Jul 2011 0.30-1.38 0.73-0.91 1.04-1.27 0.74-0.80 0.80-0.85 0.78-0.81 2700-3320 3350-3760 5969-6590 0.30-0.98 0.30-0.30 0.23-0.39 Aug 2011 1.02-1.11 0.58-1.21 0.92-1.35 0.70-0.81 0.75-0.89 0.80-0.84 3690-3860 3450-3920 7076-7748 0.30-0.56 0.30-1.22 0.28-0.42 Sep 2011 1.44-2.51 0.30-0.54 0.62-1.19 0.81-0.88 0.82-0.95 0.65-0.91 3650-3930 810-3710 7644-8989 0.30-2.24 0.30-1.17 0.24-0.67 Oct 2011 0.41-3.32 0.38-0.64 No Data 0.81-0.95 0.80-0.94 No Data 2700-4230 500-870 No Data 0.87-2.42 0.47-1.18 No Data Nov 2011 0.52-0.91 0.58-0.70 0.61-0.81 0.95-0.98 0.93-0.97 0.73-0.96 4000-4130 1020-1200 7301-9368 0.30-0.58 0.30-0.98 0.23-0.24 Dec 2011 0.61-0.93 0.63-0.73 0.61-1.08 0.98-0.99 0.97-0.98 0.87-0.94 3950-4110 1260-1700 9082-9637 0.30-0.57 0.30-0.94 0.23-0.39 Jan 2012 0.30-0.61 0.30-0.81 0.33-1.06 0.96-1.00 0.87-1.03 0.84-0.93 3940-4050 1120-1390 9362-10700 0.30-0.53 0.63-1.03 0.19-0.23 MIN 0.30 0.30 0.33 0.74 0.75 0.65 1480 500 1875 0.30 0.30 0.19 MAX 3.32 2.59 2.17 1.06 1.07 1.03 4230 3920 10700 2.45 5.02 0.73
Response to Request for Additional Information - License Attachment 1 Amendment Request to Use Neutron Absorbing Inserts Page 6 Because the LCS and PBAPS spent fuel pool chemistries are similar and maintained using the same limits, the fast start testing program is not required to be repeated at PBAPS. The long-term coupon surveillance program described in Section 3.9.3 of Attachment 1 of the LAR will provide adequate monitoring of the insert material physical properties.
Question:
RAI-11: Will the coupons be re-inserted into the SFP after being inspected?
Response
No. Coupons will not be re-inserted into the fuel pool after removal for inspection. The removal process and handling of inserts creates the potential for coupon damage and once a coupon is removed from service for inspection, it is exposed to the ambient air environment and would no longer provide a representative sample for future inspections. There will be a sufficient number of test coupons installed in the spent fuel pool so that coupons will not have to be re-used for future required inspections.
Question:
RAI-12: Page 19 of Attachment 1 of the LAR indicates that the areal density will only be measured on select coupons. Please discuss why the areal density measurement is only performed on select coupons as opposed to all of the coupons.
Response
Areal density measurements will be performed on the general and galvanic-couple coupons as part of the surveillance program. The bend coupons will not have areal density measurements performed. The purpose and frequency of testing of the general and galvanic-couple coupons are to confirm acceptable corrosion performance of the material while maintaining acceptable B-10 areal density. The purpose of the bend coupons is to confirm acceptable corrosion performance in the bend section and to monitor relaxation. Due to geometry constraints, the bend section of the coupon cannot be accurately tested for areal density using neutron attenuation methods.
Question:
RAI-13.1: Given that all the inserts may not be installed until 2016, what is the frequency for performing RACKLIFE predictions?
Response
RACKLIFE model projections are currently performed every six months in accordance with existing station procedures. RACKLIFE projections will continue to be performed every six months until all the inserts are installed in a given fuel pool as described in the LAR. Once all inserts are installed in a spent fuel pool and NRC approval of the LAR is granted, the RACKLIFE projections and Boraflex degradation trending for that fuel pool will no longer be necessary because Boraflex will no longer be credited for criticality control. The cessation of RACKLIFE projections will be implemented on a rack module-by-rack module basis as described in Section 3.1.5 the LAR.
Response to Request for Additional Information - License Attachment 1 Amendment Request to Use Neutron Absorbing Inserts Page 7 Question:
RAI-13.2: Given that all the inserts may not be installed until 2016, what is the frequency and sample size of the BADGER measurements?
Response
BADGER testing is currently performed every four years in accordance with existing station procedures. BADGER testing will continue to be performed every four years until all the inserts are installed in a given fuel pool as described in the LAR and NRC approval of the LAR is granted. The schedule for the next BADGER testing is 2013 for PBAPS, Unit 3 and 2014 for PBAPS, Unit 2. The total population size consists of all operable cells in the spent fuel pools.
The sample size of 60 will be used for the future campaigns.
A sample size of 60 is the minimum sample size required to determine a 95/95 minimum areal density via non-parametric statistical methods applied to data that do not follow normal distributions. This is typical of BADGER data, as the selected test panels are typically biased towards those panels that have experienced a more severe service duty in terms of gamma exposure and boron carbide degradation rather than being randomly selected from the entire pool population.
Once all inserts are installed in a spent fuel pool, the BADGER testing and Boraflex degradation monitoring for that fuel pool will no longer be necessary since Boraflex will no longer be credited for criticality control. The cessation of BADGER testing will be implemented on a rack module-by-rack module basis as described in the LAR.
ATTACHMENT 2 NET-332-01, Inspection and Testing of BORAL and Fast Start Surveillance Coupons from the LaSalle County Units 1 and 2 Stations"
NET-332-O1 Inspection and Testing ng of BO RAL and BORAL Fast Start Surveillance Coupons from the LaSalle County Units 1I & 2 Stations September 2009 Prepared for Exelon Generation under Contract No: 00447725 by NETCO, a division of Scientech, a business unit of Curtiss-Wright Flow Control Service Corporation 108 North Front Street UPO Box 4178
- 41 Kingston, New York 12402 12402 Review/Approval Record
__Revision Date Prepared by: I Reviewed by: Approved (QA):
0 I/CQ ;/fr7:?:t5
NET-332-O1 Table of Contents 11.0 Introduction ..... 1I 2.0 Scope of Surveillance Coupon Testing ...... 2 3.0 TestResults .................... 5 3.1 Visual Inspection ............................................. 5 3.2 Coupon Dimensions
, *.-."""I""'l£.'''I'L" ***************************************************************** 13 3.3 DryWeight Dry Weight..... . 16 3.4 SpecIfic Gravity and Density ..... . 18 3.5 Neutron Attenuation Measurements and B-10 B40 Neal Areal Density 20 3.6 Rockwell Hardness .............................................................. 21 3:7 Radloassay ........................................................................ 21 3.8 Corrosion Rates of the Fast Start Coupons . 22 4.0 Conclusions 23 5.0 References 24 Appendix A: Procedures for Measuring and Recording BORAL. BORAL Surveillance Coupon Physical Attributes, SEP-235-01, Northeast Technology Corp.; 415104 4/5/04 Appendix B: Procedure for PosteTest Post-Test Characterization of the Fast Start Surveillance Coupons, SEP-259-13, 6130109 6/30/09 Appendix C: NIST N1ST Traceable Calibration Certificates for the Gage Blocks, Masses and Rockwell Hardness Tester
NET-332-O1 11.0 IntroductIon Introduction One BORAL coupon from Exelons LaSalIe County Unit I Station (LCI1)) and two ALCAN composite coupons from the Fast Start Surveillance program at Unit 2 were were shipped to Sdentechs laboratory facilities at the Pennsylvania State University. The BORAL coupon was Identified as CL205700-24; and the Alcan Coupons were identified as No. 23 and 24. The coupons were subjected to testing and inspection as described SectIon in ....,_. . , ..._, 2.0 of this report The test results are contaIned in Section 3.0 and Scientechs
......:,...,*~I"'\'r~,..I"'\*1:" conclusions with respect to test resultsresults are contained contained in Section 4.0.
4.0.
Appendix A contains a copy of SEP-235-01 Procedures for Measuring and Recording BORAL Surveillance Coupon Physical Attributes," Attributes, which was used as the test procedure for this work. Appendix B contains a copy of SEP-2591 3, "Procedure Procedure for Post-Test Characteriza tion of the Fast Start Surveillance Coupons, Characterization Coupons," the procedure used to test the Alcan composite coupons. Appendix C contains copies of the NIST traceable calibration certifications for the gage blocks, the standard masses and the Rockwell Hardness Tester. The gage bocks and the standard masses were used to verify the dimension and weight measuring instruments.
All coupons were in good overall condItion condition when received by Scientech. No significant deterioration or degradation was evident evident. Comparison with measuremen measurements ts made prior to placement In in the pool (pre-irradiatl on) confirm this. No surface pitting was observed.
(pre-irradiation)
Corrosion of the the BORAL was was limited toto aa more or less uniform, light oxide film film on the coupon surfaces. surfaces. No visible visible evidence evidence of corrosion corrosion was was noted on the the surfaces ofof the the Alcan Alcan coupons. coupons.
I1
NET-332O1 2.0 Scope of Surveillance Coupon Testing The coupons received by Scientech were first subjected to visual inspection and photography followed by cleaning with demineralized water to remove transferable contamination. Weight measurements were then taken and the BORAL coupon was subjected to a four step drying process. After each drying step, the coupon was cooled and again weighed. After the drying sequence, the BORAL coupon was subjected to the following tests:
- . Dimension measurements
- . Specific gravity and density measurements
- . Neutron attenuation testing and B-b areal density measurements
.* Rockwell E hardness measurements rt....,r*"rti.':'lC"C"
.* Radloassay measurements.
The locations for the dimension, attenuation and hardness tests are shown In in Figure 2-
- 1. All testing was conducted in accordance with SEP-235-O1, SEP-235-01, which is included as Appendix A to this report.
The Alcan coupons were dried for 11 hour1.273148e-4 days <br />0.00306 hours <br />1.818783e-5 weeks <br />4.1855e-6 months <br /> at 220° F to remove surface moIsture. moisture. After drying, the coupons were subject to:
- Dimension measurements
- Specific gravity and density measurements
- Neutron attenuation testing and B-1O B-10 areal density measurements
- Acid cleaning and conosion corrosion rate determination The locations for the dimension measurements and neutron attenuation test are shown in Figure 2-2. All testing was 2-2. All was conductedconducted in accordance accordance with with SEP-259-13, SEP-259-13, which which is included as as AppendIx Appendix BB to to this this report.
report.
22
N ET-332-O 1 Li1 L2 L3 1/2 W
_____L_ *-
Wi1 r A ,) -ç B ) -
w1 1/2L W2 J-.--+----~--
) --
W2 W2 W3 H: W3 L1 L2 L3 Thickness, Neutron Attenuation and Hardness Testing at Locations A, B, C, D 0 and E E
Figure 2-1: Locations for the BORAL Coupon Measurements 33
N ET-332-O I LI L2
/ID#
- f__* _
r 4
xx i/e L)
Ti T2 r3 Wi I i/2 TE3 W2j T7 T8 T9 + W3 W3 0
t 1!2 ,: Neutron LI L2 Attenuation Test Figure 2-2: Locations for Fast Start Coupon Tests 44
NET-332.O1 3.0 Test Results 3.11 VIsual InspectIon In this sectIon, the conditIon of the front and back sIdes of the coupons are are described.
The front side is defined as the side of the coupon with the 10 ID number number on on it.
It.
BORAL Coucon CL2O57OO2-3 The notes from the vIsual inspection of Coupon CL205700-2-3 are contained in Table 3-1 The overall condItIon of the coupon was good with no anomalies other than a relatIvely high level of radioactive surface contamination.
relatively contaminatIon. Figures 3-1 31 and 3-2 contain the microphotographs of the front and back sides of the capsule identified IdentIfied as No.2.
FIgures 3-3 and 34 show the front and back sides of Coupon CL205700-2-3. CL205700-24. During dryIng drying at 300 °F, six blisters developed on each side of the coupon. Figures 3-5 and 3-6 show the condition of the front and back sides of the coupon after drying.
Fast Start Couoons Nos. 23 and 24 The fast start coupons are unclad and are attached to each other by stainless links through the two holes in each coupon. The chain of coupons are attached to a head place piece that fits into the upper lead-In lead-in of a storage cell in the pool. The notes from the visual InspectIon inspection of the fast start coupons are contaIned contained in Table 3-2. The fast start coupons were in good condition. There were some minor surface scratches, which likely occurred when the coupon chain was was removed from from the pool. The front and back sides sides of coupon No.23 No. 23 are are shown shown Inin Figures 3-73-7 and and 3-8, 3-8, respectively. TheThe front front and back sides sides of of coupon coupon No.24 No. 24 are are shown shown Inin Figures 3-93-9 and and 3-10.
3-10. The The surface surface appearance appearance & of both coupons was both coupons was similar similar to to that of mill that of mill finish finish aluminum aluminum withwith nono visible visible surface surface oxidation oxidation after after 66 months months residency residency in in the the pool.
pool. WhenWhen comparing comparing the the surfaces surfaces of of coupons coupons 23 23 and and 24 24 with with archive archive material, material, the the coupons coupons taken taken from from the the pool pool appear appear darker darker than than the the archive archive material material as as shown shown In in Figure Figure 3-11.
3-11.
55
N ET-332-O 1 Table 3-1 Visual Inspection of Coupon CL205700-2-3 General: LAS is inscribed in the upper left corner. Just below is the AAR ID number CL205700-2-3. The coupon was received in a stainless steel capsule, which was opened by removing the twelve machine screws that secure the capsule cover plates.
On the front side of the capsule the numerals 02 were inscribed. The coupon is in good overall condition and is intact. Contamination levels are high with Co-60 at about 2lmCi and Fe-55 at O.27mCi. After drying at 300 deg F six blisters developed on each side of this coupon.
Front side: Front surface is covered by a fairly heavy oxide film and the central portion of the film is a light grey. Along the side edges and bottom edge the oxide film is a darker grey. Within these regions there are areas where it looks like the oxide is thinner.
Back side: The central region is covered by a fairly heavy oxide film of a light grey color. The bottom and side edges have a darker color oxide film. Along the top edge there is a region where it looks like the oxide film is not formed formed. Along the top edge there are brown, rust-colored deposits, which could be the source of the high level of contamination. There is no evidence of pitting corrosion on either side of this coupon.
Table 3-2 Visual Inspection of Fast Start Coupons Nos. 23 and 24 General: The numerals F23 are inscribed in the upper right corner of the front side.
The appearance of the surface of the coupon is similar to aa mill finish. There is no visible oxide film on any of the surfaces. Inspection of the surface with aa microscope confirms there is no oxide film.
Front side: There are are random scratches on this side. There are no no other anomalies.
Back Back side:
side: The The appearance appearance is is similar to the front.
General:
General: The The numerals numerals F24 F24 areare inscribed inscribed in in the the upper upper right corner corner ofof the the front side.
side.
The The surfaces surfaces of of the the coupon coupon appear appear as as mill mill finish; finish; that that is, is, there there are are no no visible visible signs signs of of an an oxide film. Inspection of the surface with a microscope oxide fHm. Inspection of the surface with a microscope confirms confirms thethe absence absence of of an an oxide oxide film.
film.
Front Front side:
side: There There areare various various scratches, scratches, which which most most likely likely occurred occurred when when the the coupons coupons were were removed removed from from the the pool.
pool. There There are are no no anomalies anomalies on on the the front front side.
side. There There appears appears to be some to be some marking marking ink on the ink on the upper upper left left edge edge fromfrom when when the the sheet sheet was was rolled.
rolled.
Back Back side:
side: Appearance Appearance of of the the back back side side isis similar similar to to the the front.
front.
66
NET-332-01 z
rnH rJ C
-n cr C
CD Cf C) V Cl)
C CD CD U)
(0 D
CD a
U)
C > CD C)
CD CD a
-n Figure 3-1: Capsule Designated as 02 As-Received: Front Side C
D cr1 a
CD C) fl CD Cl)
(0 C
CD Cf k) cu V
Cl) CD CD Cl)
(0 D 0. C >
Figure 3-2: Capsule Designated as 02 As-Received: Back Side C) CD C-)
CD CD a C-) J) 0 CD 7
NET-332-01 zm C Figure 3-3: Front Side of Coupon CL205700-2-3
-El CD c) w C) CD C C-)
C C C D C)
F.
Figure 3-4: Back Side of Coupon CL205700-2-3 C N)
C 01 C 9 c) 8
NET-332-01 zf-n C) C 41 j\_._
11 CD -n Cl)
C c) 01 - D ci CD 0 C)
Figure 3-5: Front Side of Coupon CL205700-2-3: As Dried
- 0 0 C 0 D C) C CJ1 C 9 >
C,,
CD ci I
-1, 0) 03 Cl) C-)
Figure 3-6: Back Side of Coupon CL205700-2-3: As Dried C
CD C) CD 0 0 C 0 D C) rJ C(.71 C CD? (1) D CD ci rz 9 C)
zm NET-332-01 C
Figure 3-7: Fast Start Coupon 23 Front Side
-n -n cI (0
C CD C?3 0 £1) CD 0 C 0 c)
Figure 3-8: Fast Start Coupon 23 Back Side w
ci)
C) Cl, 0.
CD 10 C
zrn C NET-332-01 Figure 3-9: Fast Start Coupon 24 Front Side C
-n CD C) C r1 Cr) 0) C)
C C D
Figure 3-10: Fast Start Coupon 24 Back Side Cl) 0 3
03 C) a) Cl, CD 11
NET-332-01 N ET-332-O1 Microphotograph of Coupons 23, Figure 3-11: Microphotograph 23. 24 and Archive Material (8X Magnificatio n)
Magnification) 12 12
NET-332-O1 3.2 Coupon Dimensions The dimensions of the BORAL coupon were measured at the locations shown in Figure 2-1 The locations of the coupon dimension measurement for the fast start coupons are
. are shown in Figure 2-2. The measured iength, width and thickness ofof the the BORAL BORAL coupon coupon are summarized in Tabies 3-3 and 3-4. The post irradiation data in these tables are compared with measurements taken when the coupon was prepared and pre characterized. Comparison of the pre and post irradiation measurements indicate no change in dimensions.
The measured dimensions of the fast start coupons are summarized in Tables 3-5 and 3-6. The post irradiation measurements are compared with the measurements taken when the coupons were prepared and pre-characterized in these tables. Comparison of v-..." ......."'-...".
pre and post irradiation measurements shows no significant change in coupon dimensions.
13 13
NET-332-O I Table 3-3 Length and Width Measurements of Coupon CL205700-2-3 Coupon Length, inches Width inches ID No Length I /
Length 2 Length 3 1 L avg Width I I Width 2 1 Width 3 W avg CL20570023_j AsMeasured 6084 1 6084 6083 J 6084 5010 1 5016 1 5016 J 5014 As Manufactured Length As Manufactured Width 6083 6.083 1 6084 6078 1 6082 502 5016 J 5016 5017 Change In Length Change in Width 0001 1 0000 0005 0002 0010 1 0000 1 oooo 0003 Percent Change in Length Percent Change in Width 002 1 001 008 { 004 019 001 j 001 006 Table 3-4 Thickness Measurements of Coupon CL205700-2-3 Coupon Thickness Inches ID No Thickness-Thickness Thickness-Thickness Thickness Thickness Thickness A
A BBCO D E TAvg CL205700 2-3 o0.0799 0799 0 0800 1 o0.0785 0785 1 0 0790 j 0 0788 0 0792 As Manufactured Thickness 0 0800 0 0800 1 0 0780 1 0 0790 1 0 0790 FO 0792 Chan$e In Thickness 0 0001
-0.0001 1 0 0000 1 0 0005 1 0 0000 1 0 0002 I 0 0000 Percent Change In Thickness 019j
-0.19 006j 058j -025j[ oo 144
N ET-332-O I Table 3-5 Length and Width Measurements of Fast Start Coupons 23 and 24 Coupon on 10 LD Length I Length 2 Width4 Width 2 Width 3 Pre-Irradiatio Pre-I rradiationn 3.953 3.975 1.975 1984 1.982 Post-Irradiation Post-Irradiation 3953 3,974 1 .974 1 .983 1.982 F23 Change Chanae f:J. 0.000 -0.001 -0.001 -0.001 0.000 Change %
Chanae -001% -OO3% -003% -0.05% O.O3%
Pre-Irradiation Pre-Irradiation 3.977 3,975 1.975 1.982 1.977 Post-irradiation Post-Irradiation 3.977 3.974 1 .974 1 .992 1.977 F24 Change Chanae f:J. 0.001 0.000 -0.001 0.010 0.000 Change %
Chanae 0M3% -0.01% -OO3% 0.53% -0M3%
Table 3-6 Thickness Measurements of Fast Start Coupons 23 and 24 1=
Coupon ID Thickness I Thickness 2 Thickness 3 Thickness 4 Thickness 5 1 Thickness 6 Th ckness 7 Thri 8 Trc e 9 A Pre Irradiation 0 0670 0 0670 0 0670 0 0670 0 0670 0 0670 0 0670 0 0670 0 0o 0
7 0 uo7U Post- 0.0658 0.0695 0.0663 0.0663 0.0667 0.0670 0.0661 00686 006$9 0.0667 Irradiation, As Change E -0.0011 0.0025 -0.0006 -0.0006 -0.0003 0.0000 -00009 00016 -00001 -00003 F23 Dried Change % -1.68% 3.77% -0.93% -0.93% -048% 0.04% -138% 243% -011% -038%
Post- 0.0675 0.0680 00670 0.0671 0.0670 0.0665 0,0664 0.0663 0.0664 0.0669 Change 0.0005 0.0010 0.0000 0.0002 0.0000 -0.0005 -0.0006 -0.0007 -0.0006 -00001
Wash Change % 0.79% 153% -0.04% O26% -004% -071% -0.86% -1.01% -0.86% -0.10%
Pie-Irradiation 0.0670 0.0670 0.0670 0.0670 0.0670 0.0670 0.0670 0.0670 00670 0 0670 Post- 0.0666 0.0688 0.0668 0.0670 0.0668 0.0675 0.0662 0.0679 00668 00672 IrradiationAs Change1 -0.0004 0.0018 -0.0001 0.0000 -0.0001 0.0005 -0.0007 00009 -00001 00002 Dried F24 Change % -0.63% 273% -0.19% OO4% -O19% 0.71% -tOB% t31% -019% 0.28%
Post- 0.0667 0.0693 0.0667 0.0667 0.0674 0.0671 0.0672 0.0674 0.0673 0.0673 Irradiation, Change 1 -0.0003 0.0023 -0.0003 -0.0002 0.0004 0.0001 0.0002 0,0004 0.0003 00003 After Acid
=
Wash Change % -0.48% 3.40% -O41% -O.33% 0.56% 0.11% O34% 0.64% 0.49% 0.48%
Note: The value of pie-irradiatio Note: pre-irradiation n thiCkness thickness (0.0670)
(0.0670") for coupons
....,_'-41....,_. F23 and F24 was determined based on the average value of eighty-one thickness measuremen measurements ts made on archive coupons taken from the same sheet of rolled ALCAN material.
15 15
NET432-O1 3.3 Dry Weight The as-received dry weight of the BORAL coupon is given inIn Table 3-7. Also given inIn this table Is the weight after each 4 hour4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> drying step, and the change in weight as a result of each drying step. The purpose of the 4-step drying process is to removeremove moisture entrained in porosity in the core of the BORAL. The coupon showed a gain in in weight of 0.92%, relatIve to the coupons as-manufactured weight This is Is likely likely due due to the presence of an oxide film on most of the coupon surlaces.
The dried weights of fast start coupons 23 andand 24 are are given in Table 3-8. Since the the fast start coupons are fully dense (negligible porosity), they they are dried for for 1I hour at 220 FF to to remove surface moisture. The dried coupon weights remove weIghts are compared compared withwfth the weight measurements made when the coupons were prepared and pre-characterized pre-characterlzed in In Table Table 3-8. This shows there has been an insignificant change in coupon weight weight.
Also, shown In in Table 3-8 are the weight losses after two cleanings with nitric acid.
There was no further weight loss after the second add acid wash and Itit is conduded concluded that that any corrosion products present were removed by the first wash. The data in this table table show there is very little weight change due to add acid cleaning (-0.01%)
(-0.01 %) for each coupon.
This confirms the visual and microscopic Inspections, inspections, which conduded concluded there were little or no corrosion products on the coupons.
16 16
NET-332-O I Table 3-7 Weight Measurements of Coupon CL205700-2-3 W':tlaht.
Weight, urams Grams Coupon 10 Coupon ID No.
As After Four Hours Of Drying At As % Change Qoened Opened sSpecified Temperature Manufactured In Weight 17500 FF
! 5OO F 5000 FF 3QQ0 175 Weight crams Weiqht, grams 98 63 98.63 98 55 98 26 97 89 97 87 96 98 0 92 Step Change, CL205700-2-3 I Step Change,
-ms gms 0.08 0.29 0.37 002 Step Change, % 0.08% 029% 0.38% 002%
Table 3-8 Weight Measurements of Fast Start Coupons 23 and 24 Coupon ID D Weight vUUUUlllO (Grams)
=
Pre-irradiation 22.6870 226800 Post-Irradiation, As Change -0.0070 Dried F23 Change % -O.03%
22,6770 Post-irradiation, After Acid Wash Fange -o.oioo
, . I Change % -0.04%
Pre-Irradiation 22.8060 22.8000 Post-Irradiation, As Dried Change i -0.0060 F24 Change % -0.03%
22.7960 Post-Irradiation, After AcadWash Change -0.0100 Acid Wash Change% 004%
177
NET432-O1 3.4 Specific Gravity and Density The coupons were also subjected to specific gravity and density measurements via immersion weighing. The results of the measurements for the BORAL coupon are are summarized in Table 3-9. The pre-irradiation density of the coupon was was reported 1 as 3
2.49 gmslcm
. The measured post irradiation coupon density is 2.53 gms/cm 3 .
3 gmslcm . The difference between the pm and post irradiation measurements is not significant.
significant The results of the density measurements for the fast start coupons are summarized in Table 3-10. Comparison of the densities measured when the coupons were prepared and pm-characterized with the post irradiation values indicates essentially no change in coupon densities.
18 18
NET-332-O1 Table 3-9 Specific Gravity and Density Measurements of Coupon CL205700-2-3 Dry Dry Dry Coupon Weight, immersed Immersed Specific Density Coupon Weight, Immersed Specific Density ID No.
IDNa. yms ms Weight, ams Weiaht yms Gravity glcm3 IDNo.
ID No. gms Weight, gms Gravity glcm3 CL205700-2-3 97.89 5925 59.25 253 2.53 AsBuilt As Built 96.98 5812 1 250 2.49 Properties Water ProDerties Water Properties Temperature deg C 23 dea Temperature 21 deg C Density 0.997567 glcm3 Density 0.99802 g/cmA3 Table 3-10 Specific Gravity and Density IYI,""U~UI Measurements of Fast Start Coupons 23 and 24 Immersed Specific Water CoupanlD Coupon ID Weight, Gravity Density Temp (Grams) gmlcmA3 m/cmJ\3 (0 C) g mIcmA3 Pre-Irradiation 14.2700 142700 2.70 19.0 2,69 Post-Irradiation 142800 270 19.0 2.70 F23 ~~~~~----,r------+---=-:-::?=-+---;:==:-t----I---:~~
ChangeI f). 0.0100 0.005 0.0046 Change % 0.07%
QO7% 0.17%
O17% 0.17%
Pre-Irradiation 14.3500 2.70 19.0 2.69 Post-Irradiation 14.37Q 2.70 19.0 2.70 F24 ~~~~~-----'-----+----=-:-:-:-:=+---=-=:-:::-r---I---:~~
F24 ChangeL 0.0200 0.0076 0.0076 Change % 0.14%
0.14% 0.28%
0.28% 0.28%
199
N ET-332-O 1 35 Neutron Attenuation Measurements and B-1O Areal Density The Boron1O areal density of the coupon was measured via neutron attenuation testing. The test was conducted in the Beam Hole Laboratory at the Pennsylvania State University using the PSU Triga Reactor as a source of thermal neutrons. Table 3-111 contains the results of the B-I 0 areal density measurements.
The Boron-lO areal density was measured at five locations on the BORAL coupon as shown in Figure 2-1 . The average areal density for the coupon is 0.0256 OO256 +/- 0.0003 OOOO3 grams B-1O/cm
. The pre-irradiation areal density for coupon CL205700-2-3 is 2
reported as 00250_._.1..._- gms B-lOIcm
. There is no rtl'l"l'n"''''''II.n 2 difference between the pre and post-irradiation values.
Boron-lO areal density of the fast start coupons was measured at the geometric The Boron-10 center of each fast start coupon. The areal densities of coupons 23 and 24 are 0.0093 OOO93 2
+/- 0.0003 and 0.0095OOO95 +/- 0.0003 grams B-10/cm ,
2 B-lOIcm , respectively. During pre- pre characterization measurements, the areal density for coupons 23 and 24 were each 2
determined to be 0.0092 OOO92 +/- 0.0006 grams B-10/cm .
2 B-1O/cm . Accordingly, it is concluded there has been no change in areal density.
Table 3-11 Neutron Attenuation Measurement Attenuated Count Power Count Unattenuated Aftenuated Attenuated Power Bkgrd, Areal Uncertainty ID Beam, Time, Beam, Time, Beam, eam, earn, Beam, 10 Beam, cps cps Density counts s 5 counts s S cps CS cps CL205700-2-3:A CL205700-2-3:A 37434 30 20321 30 33899 74 1248 677 0.0253 00253 0.0003 00003 CL205700-23:D CL205700-2-3:D 38952 30 20146 30 33899 74 1298 1298 672 0.0248 00248 0.0003 00003 CL205700-2-3:B CL205 7 00 *2*38 37911 30 20231 30 33899 74 1264 1264 674 0.0251 00251 0.0003 00003 CL205700-2-3:E 38316 30 20022 30 33899 74 1277 1277 667 0.0249 00249 0.0003 00003 CL205700-2-3 CL205700-2-3:C 39039 30 20128 30 33899 33899 74 1301 1301 671 0.0248 0.0248 0.0003 00003 F23 270841 270841 30 30 20022 30 30 33899 74 9028 667 0.0093 00093 0.0003 F24 267310 30 30 20152 30 30 33899 74 8910 672 0.0095 00095 0.0003 20
NET-332-O 1 36 Rockwell E Hardness The Rockwell E Hardness was measured at five locations on the BORAL coupon as shown in Figure 2-1. The measured values are summarized in Table 312. The RHE for as-manufactured BORAL is typically 50 to 60 RHE depending on the boron carbide loading. All measured values are within this range indicating acceptable material performance.
Table 3-12 Rockwell E Hardness Location RHE A 52O B
B 55O c__ 5o o
D E 540 E 550 55.0 Average 54.2 542 37 Radioassay The BORAL coupon was subjected to radioassay along the top edge, edge. center and bottom edge. The measurements are recorded in Table 3-1 3. The relatively high activity on 3-13.
the top edge is likely due to crud which has settled out from the pool water. The measurements indicate some water permeation along the porous bottom edge and radioactive pool contamination at that location. The lower level of activity at the center of the coupon is likely due to residual surface contamination.
Table 3-13 Radioassay Beta && Gamma, cpm ~ Gamma, cpm I Beta, cpm Topp ILcenter Center 1 Bottom Top Center IBottom I
[ centJLBottom Top I Center / Bottom 2800 J 400 1950 1950 2000 300 1550 1550 I 800 100 100 400 21
N ET-332-O 1 3.8 Corrosion Rates of the Fast Start Coupons The corrosion rates of coupons 23 and 24 were calculated based on ASTM-G34-72 (Reapproved 2004) and the weight loss data in Table 3-8 that resulted from acid cleaning. The corrosion rates so calculated are 003 mils/year for both Coupons 23 and
- 24. This corrosion rate is extremely low and confirms the visual observation that both coupons were essentially devoid of corrosion products. The measured corrosion rates consistent with the corrosion rates as determined from accelerated corrosion testing are ""1"'\""~tl... t'I"'\I"'t' at 1195° F 2 22
NET-332-O1 40 4.0 ConclusIons BORAL surveillance coupon CL205700-2-3 from the LaSalle . . . . -. .......- Unit Unit 1I spent fuel pool was subjected to nondestrucdve testIng. The tests included measurement of dimensions, dry weight, density, boron-lO areal density, Rockwell E hardness and radloassay. The results of these tests are Indicative of sat:lSTC:lcttDrv satisfactory material performance. Comparison of densities with pre4rradiatlon the post-Irradiation areal """"""'l"'.'W'.""l'" ......."',11""I."'11'."" ..... values v rcl.I.c1~;; ...., further further ,..._.""'+.............-
confirms
..... "".I""'t.............,,, .....,...' and acceptable coupon performance and no no loss of boron carbide.
The coupon showed a weight gain of - 1I .0% relative relatIve to the pre-irradiation pre4rradlation weight weight. This is likely due to a light oxide film which had formed on the coupon surfaces during residency in the spent fuel pool. A small increase in the coupons coupon's dimension tend to confirm this conclusion. The development of small blisters in the dad clad of the BORAL during drying is inconsequential.
The two fast start coupons, Nos. 23 and 24, from the LaSaile LaSalle 2 pool exhibited excellent dimensional stability, insignificant weight or density change, and no change in boron-I boron-10 0
areal density. Corrosion rates were determined per ASTM-G34-72 (Reapproved in 2004). My Any corrosion products present were removed by successive washes in nitric acid and weight changes measured. The corrosion rate for each coupon so determined was 0.03 miislyear, mils/year, which is very low and consistent with the rates measured under accelerated corrosion condlfions.
2 conditions. (2) 23
NET-332-O1 5.0 Refrrncn
- 1) Certificate of Compliance and Data Sheets for LaSalie BORAL Surveillance Coupon, Hoitec Project Number 11240,6125193.
- 2) MaterIal Qualification of Alcan Composite for Spent Fuel Storage, NET-259-03,
.-...*.,...,...1r.n ..... of RevS, Northeast l ' I ..... Technology Corp., 7130109.
I-rnCJk~I:'T Technology 24