ML12096A052

Response to Request for Additional Information - License Amendment Request for Use of Neutron Absorbing Inserts in Spent Fuel Pool Storage Racks

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 200 Exelon Way Kennett Square, PA 19348 April 4, 2012 www.exeloncorp.com Exelon.Nuclear 10 CFR 50.90 U.S.Nuclear Regulatory Commission A TIN: 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 and3-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 and3-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 Exelon Nuclear 200 Exelon Way Kennett Square, PA 19348 April 4, 2012 www.exeloncorp.com Exelon.Nuclear 10 CFR 50.90 U.S.Nuclear Regulatory Commission A TIN: 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 and3-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 and3-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 4 th 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/cm 2 given that the qualification testing acceptance criteria is listed as greater than 0.0087 g/cm 2 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/B 4C 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/cm 2). 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/cm

2. 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/cm

2. 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

2) John Gilbert Kaufman, "Properties of Aluminum Alloys, ASM International," 1999 (page 15)

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 B 4 C 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 140 o F and 150 oF, respectively. The normal operating temperature range for the fuel pools at both stations is 70 oF-110 o F. 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 DateChloride (ppb)Conductivity (S/cm)Silica (ppb)Sulfate (ppb) PB2 PB3 LAS PB2 PB3 LAS PB2 PB3 LAS PB2 PB3 LASMar 20110.76-0.80 1.72-2.15 0.86-1.451.01-1.06 1.03-1.07 0.93-1.031520-1620 3480-3630 1875-62350.30-2.45 0.30-4.91 0.23-0.24Apr 20110.90-1.05 2.20-2.59 1.05-2.170.93-1.03 0.98-1.05 0.91-0.951480-1780 2860-3640 4020-44090.30-1.75 0.30-5.02 0.23-0.73May 20110.32-1.07 0.30-0.51 1.31-1.760.81-0.93 0.89-0.95 0.88-0.951700-2280 3060-3710 3879-47490.30-1.02 0.30-0.82 0.23-0.32Jun 20110.53-0.64 0.60-0.71 0.71-1.170.80-0.83 0.84-0.88 0.65-0.862390-2680 3490-3580 4850-58070.30-0.44 0.30-0.48 0.23-0.25Jul 20110.30-1.38 0.73-0.91 1.04-1.270.74-0.80 0.80-0.85 0.78-0.812700-3320 3350-3760 5969-65900.30-0.98 0.30-0.30 0.23-0.39Aug 20111.02-1.11 0.58-1.21 0.92-1.350.70-0.81 0.75-0.89 0.80-0.843690-3860 3450-3920 7076-77480.30-0.56 0.30-1.22 0.28-0.42Sep 20111.44-2.51 0.30-0.54 0.62-1.190.81-0.88 0.82-0.95 0.65-0.913650-3930 810-3710 7644-89890.30-2.24 0.30-1.17 0.24-0.67Oct 20110.41-3.32 0.38-0.64 No Data0.81-0.95 0.80-0.94 No Data2700-4230 500-870 No Data0.87-2.42 0.47-1.18 No DataNov 20110.52-0.91 0.58-0.70 0.61-0.810.95-0.98 0.93-0.97 0.73-0.964000-4130 1020-1200 7301-93680.30-0.58 0.30-0.98 0.23-0.24Dec 20110.61-0.93 0.63-0.73 0.61-1.080.98-0.99 0.97-0.98 0.87-0.943950-4110 1260-1700 9082-96370.30-0.57 0.30-0.94 0.23-0.39Jan 20120.30-0.61 0.30-0.81 0.33-1.060.96-1.00 0.87-1.03 0.84-0.933940-4050 1120-1390 9362-107000.30-0.53 0.63-1.03 0.19-0.23MIN0.30 0.30 0.330.74 0.75 0.651480 500 18750.30 0.30 0.19MAX3.32 2.59 2.171.06 1.07 1.034230 3920 107002.45 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 per formed 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" Inspection and ng BO RALand Start Surveillance Coupons from the LaSalle County Units12 Stations a division Flow Control North Front Street UPO Box 41 Kingston, New York 12402 Review/Approval Record 1.....1......2....................

5.............................................

5 ,*.-."""I""'l£.'''I'L"*****************************************************************

13 Dry Weight.....

.16......18 and B-10 Areal Density 20..............................................................

21........................................................................

21 Start Coupons.Appendix A: Procedures for Measuring and Recording BORAL Surveillance Coupon Physical Attributes, SEP-235-01, Northeast Technology Corp.;4/5/04 Appendix Procedure for Post-Test Characterization of the Fast Start Surveillance Coupons, SEP-259-13, 6/30/09 Appendix C: N 1ST Traceable Calibration Certificates for the Gage Blocks, Masses and Rockwell Hardness Tester 1 Introduction1)2 were as No.in....,_...,..._, inspection as conclusions with to test results are contained in Section 4.0.Appendix A contains a Measuring and Recording BORAL Surveillance Coupon Physical Attributes," which was used as the procedure for this work.Appendix B contains a copy of"Procedure for Post-Test Characterization of the Fast Start Surveillance Coupons," the procedure used to test the Alcan composite coupons.Appendix C contains copies of the NIST traceable for the blocks, the masses and the Rockwell Hardness The gage bocks and the standard masses were used to verify the dimension and weight measuring instruments.

All coupons were in good overall condition when received by Scientech.

No significant deterioration or degradation was evident.Comparison with measurements made prior to placement in the pool (pre-irradiation) confirm this.No surface pitting was observed.Corrosion of the BORAL was limited to a more or less uniform, light oxide film on the coupon surfaces.No visible evidence of corrosion was noted on the surfaces of the Alcan coupons.1 was following**gravity*Neutron attenuation testing and*Rockwell E rt....,r*"rti.':'lC"C" density measurements

• The locations for the dimension, attenuation and hardness are shown in Figure 1.All testing was conducted in with SEP-235-01, which is included as Appendix A to this report.The Alcan coupons were dried for 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> drying, the coupons were subject to: F to remove surface moisture.After*Dimension measurements

• Specific gravity and density measurements

• Neutron attenuation testing and B-10 areal density measurements

• Acid cleaning and corrosion rate determination The locations for the dimension measurements and neutron attenuation test are shown in Figure 2-2.All testing was conducted in accordance with SEP-259-13, which is included as Appendix B to this report.2 1 1 W2 L1 L2 L3 Thickness, Neutron Attenuation and Hardness Testing at Locations A, B, C, 0 and E Figure 2-1: Locations for the BORAL Coupon Measurements 3

Figure Locations for Fast Start Coupon 4 ,: Neutron Attenuation 1 are 10 number on it.relatively high level of the of of Coupon are contained in Table was with no anomalies other than a contamination.

Figures 3-1 and 3-2 contain back of the capsule identified as No.2.Coupon CL205700-2-3.

During drying blisters developed on of the coupon.Figures 3-5 and 3-6 show the condition of the front and back sides of the coupon after drying.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 piece that fits into the upper lead-in of a storage cell in the pool.The notes from the visual inspection of the fast start coupons are 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 removed from the pool.The front and back sides of coupon No.23 are shown in Figures 3-7 and 3-8, respectively.

The front and back sides of coupon No.24 are shown in Figures 3-9 and 3-10.The surface appearance of both coupons was similar to that of mill finish aluminum with no visible surface oxidation after 6 months residency in the pool.When comparing the surfaces of coupons 23 and 24 with archive material, the coupons taken from the pool appear darker than the archive material as shown in Figure 3-11.5 is by a fairly Along the side and bottom are areas it thinner.Back side: central region is covered by a fairly heavy film of a light grey color.and have a darker color oxide film.Along the top there is a it looks like the oxide film is not formed Along there are brown, rust-colored deposits, which could be the source of the high level of is no of pitting on of coupon.Visual Inspection of Table Start Coupons Nos.and General: numerals are inscribed in the upper right corner of the front side.The appearance of the surface of the coupon is similar to a mill finish.There is no visible oxide film on any of the surfaces.Inspection of the surface with a microscope confirms there is no oxide film.Front side: There are random scratches on this side.There are no other anomalies.

Back side: The appearance is similar to the front.General: The numerals F24 are inscribed in the upper right corner of the front side.The surfaces of the coupon appear as mill finish;that is, there are no visible signs of an oxide fHm.Inspection of the surface with a microscope confirms the absence of an oxide film.Front side: There are various scratches, which most likely occurred when the coupons were removed from the pool.There are no anomalies on the front side.There appears to be some marking ink on the upper left edge from when the sheet was rolled.Back side: Appearance of the back side is similar to the front.6 Figure 3-1: Capsule Designated as 02 As-Received:

Front Side NET-332-01 Figure 3-2: Capsule Designated as 02 As-Received:

Back Side 7 NET-332-01 Figure 3-3: Front Side of Coupon CL205700-2-3 Figure 3-4: Back Side of Coupon CL205700-2-3 8

Figure 3-5: Front Side of Coupon CL205700-2-3:

As Dried Figure 3-6: Back Side of Coupon CL205700-2-3:

As Dried 9 NET-332-01 NET-332-01 Figure 3-7: Fast Start Coupon 23 Front Side Figure 3-8: Fast Start Coupon 23 Back Side 10 NET-332-01 Figure 3-9: Fast Start Coupon 24 Front Side Figure 3-10: Fast Start Coupon 24 Back Side 11 NET-332-01 Figure 3-11: Microphotograph of Coupons 23.24 and Archive Material (8X Magnification) 12 are of the BORAL coupon irradiation in these are when the coupon was prepared and irradiation measurements no of the start coupons are summarized in Tables and irradiation measurements are compared with the measurements taken were prepared and pre-characterized in these tables.Comparison of irradiation measurements shows no significant change in coupon when the v-..."......."'-...".pre and 13 6.083 Thickness-Thickness-ABO 0.0799 0.0785-0.0001-0.19 4 E on 10 Chanae f:J.Chanae Chanae Chanae f:J.Post-Irradiation Post-Irradiation Pre-Irradiation Pre-I rradiation F24 F23 Note: The value of pre-irradiation thickness (0.0670")for....,_'-41....,_.

eighty-one thickness measurements made on archive coupons F23 15 in in remove in is likely due of and are given in the (negligible porosity), they are dried for 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> at F to remove moisture.The dried coupon weights are compared with the weight when the coupons were prepared and pre-characterized in Table shows there has been an insignificant change in coupon weight.Also, shown in Table 3-8 are the weight losses after two cleanings with nitric acid.was no further weight loss after the second acid wash and it is concluded that any corrosion products present were removed by the first wash.The data in this table show there is very little weight change due to acid cleaning (-0.01%)foreachcoupon.

This confirms the visual and microscopic inspections, which concluded there were little or no corrosion products on the coupons.16 Coupon 10 No.Weiqht, crams CL205700-2-3 I Step Change,-ms As Qoened 98.63 s 175 0 F W':tlaht.urams At F F23 F24 Acid Wash vUUUUlllO 7 coupon are coupon was irradiation coupon density is gms/cm 3.is not significant.

and coupon for coupons are summarized in of the measured when the coupons were prepared with the post irradiation values indicates essentially no change in 18 Coupon IDNa.CL205700-2-3 Dry Weight, ms 97.89 Immersed Weiaht ams 59.25 Water ProDerties 23 dea C 0.997567 IDNo.As Built Pre-Irradiation 14.2700 2.70 m/cmJ\3 0.07%0.17%0.14%0.28%

f).CoupanlD Pre-Irradiation 14.3500 Specific Gravity and Density F23 F24 9

1 on as shown in reported as irradiation for the coupon is 0.0256+/-0.0003 is is no rtl'l"l'n"''''''II.n between the pre and post-The Boron-10 density of the fast coupons was measured at the geometric of coupons and are 0.0093+/-0.0003 and 0.0095+/-0.0003 grams B-10/cm 2 , respectively.

During pre-characterization the density for coupons 23 and 24 were each determined to 0.0092+/-0.0006 grams B-10/cm 2.Accordingly, it is concluded there has been no change in areal density.Table 3-11 Neutron Attenuation Measurement Attenuated Count Power Count Unattenuated Bkgrd, Attenuated Power Areal Uncertainty 10 Beam, Time, Beam, Time, Beam, cps cps Beam, Beam, Density counts s counts s cps cps CL205700-2-3:A 37434 30 20321 30 33899 74 1248 677 0.0253 0.0003 CL205700-2-3:D 38952 30 20146 30 33899 74 1298 672 0.0248 0.0003 CL205 7 00*2*38 37911 30 20231 30 33899 74 1264 674 0.0251 0.0003 CL205700-2-3:E 38316 30 20022 30 33899 74 1277 667 0.0249 0.0003 CL205700-2-3:C 39039 30 20128 30 33899 74 1301 671 0.0248 0.0003 F23 270841 30 20022 30 33899 74 9028 667 0.0093 0.0003 F24 267310 30 20152 30 33899 74 8910 672 0.0095 0.0003 20 on A B o E Average RHE 55.0 54.2 The BORAL coupon was subjected to radioassay along the top edge.center and bottom are recorded in Table 3-13.The relatively high activity on the top is likely due to crud which has settled out from the pool water.The 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, cpmGamma, cpm I Beta, cpm p Center Bottom Top Center I Bottom I Top I Center Bottom 2800 400 1950 2000 300 1550 I 800 100 400 21 on are

...t'I"'\I"'t' with 1 22 4.0.......-........-Unit 1 was sat:lSTC:lcttDrv material performance.

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,,,.....,...'and no coupon weight gain of-1 relative to the pre-irradiation weight.This is likely due film which had formed on the coupon surfaces during residency in fuel pool.A small in the coupon's dimension tend to confirm this conclusion.

The development of small blisters in the clad of the BORAL during drying The two coupons, Nos.and from the LaSalle 2 pool exhibited excellent dimensional stability, insignificant weight or density change, andnochange in boron-10 areal density.Corrosion rates were determined per ASTM-G34-72 (Reapproved in 2004).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 mils/year, which is very low and consistent with the rates measured under accelerated corrosion conditions.

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Technology 24