ML18065A481

Forwards Preliminary Thermal Annealing Rept,Thermal Annealing Operating Plan Section 1.4,thermal Annealing Operating Conditions & Requalification Insp & Test Program Section 2.1,monitoring Annealing Process

ML18065A481
Person / Time
Site:	Palisades
Issue date:	02/05/1996
From:	Smedley R CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.)
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
NUDOCS 9602120386
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consumers

. Power POWERINii MICHlliAN"S PROliRESS Palisades Nuclear Plant: 27780 Blue Star Memorial Highway, Covert, Ml 49043

• February 5, 1996 U S Nuclear Regulatory Commission Document Control Desk Washington, DC 20555 DOCKET 50-255 - LICENSE DPR PALISADES PLANT PRELIMINARY THERMAL ANNEALING REPORT, THERMAL ANNEALING OPERATING PLAN, SECTION 1.4, THERMAL ANNEALING OPERATING CONDITIONS AND REQUALIFICATION INSPECTION AND TEST PROGRAM, SECTION 2. 1, MONITORING THE ANNEALING PROCESS At a meeting with the staff on June 6, 1995, we discussed our plan to anneal the Palisades reactor vessel (RV) during the refueling outage currently scheduled for the middle of 1998. In support of this effort, we plan to submit the final Thermal Annealing Report (TAR) in the third quarter of 1996 *after the results of the Marble Hill reactor vessel annealing demonstration have been evaluated. The TAR will include the information recommended in Draft Regulatory Guide DG-1027, Format and Content of Application For Approval For Thermal Annealing of Reactor Pressure Vessels. To permit NRC review of the TAR to begin before the Marble Hill results are known, we will make a series of submittals of preliminary TAR sections as they are developed. This letter provides the seventh of those submittals.

Attachment 1 to this letter contains the Thermal Annealing Operating Plan Section 1.4, Thermal Annealing Operating Conditions. Attachment 2 to this letter contains the Requalification Inspection and Test Program Section 2.1, Monitoring the Annealing Process. These sections are presented in the format recommended by Sections C.1 and C.2 of DG-1027.

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SUMMARY

OF COMMITMENTS This letter contains no new commitments and no rJ;ii'sions to existing commitments.

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Richard W Smedley Manager, Licensing CC Administrator, Region Ill, USNRC Project Manager, NRR, USNRC NRC Resident Inspector - Palisades Attachment

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ATTACHMENT 1 CONSUMERS POWER COMPANY PALISADES PLANT DOCKET 50-255 THERMAL ANNEALING REPORT SECTION 1 THERMAL ANNEALING OPERATING PLAN SECTION 1.4 THERMAL ANNEALING OPERATING CONDITIONS 15 Pages

1.4 1.4.A THERMAL ANNEALING OPERATING CONDITIONS Introduction This section describes the proposed annealing parameters that have been selected.

These parameters provide sufficient recovery of the. fracture toughness of the RV materials and are compatible with the design limits of the reactor vessel and any other component or structure affected by the heating of the reactor vessel, except the surveillance capsule wall holders which may deform as discussed in Section 1 . 7. The structural integrity and functionality of the surveillance capsule wall holders will be verified as described in Sections 2.2 and 2.3.

Annealing parameters have been categorized as either administrative limits or as limiting parameters. Table 1.4.A-1 summarizes the administrative limits which are described in detail below. The limiting parameters are discussed in detail in Section 1.8. Limiting parameters are the governing parameters needed to ensure an effective and acceptable anneal without further analysis and testing.

Administrative limits are those bounds that have been identified to maintain a prudent engineering margin such that the limiting parameters in Section 1.8 will not be exceeded. Even if administrative limits are reached, the analyses in Section 1. 7 show margin to limiting parameters exists. When an administrative limit is approached or crossed, action will be taken to return within limits or an engineering evaluation to justify the deviation will be performed if correction is not feasible.

The limiting parameters such as annealing temperature and time at temperature are dictated by the limits of Section 1.8 and by the material recovery goal as described in Section 1 . 1 . The thermal and stress analyses documented in Section 1 . 7 provide the basis for establishing the administrative limits, such as heatup and.

cooldown rates and temperature gradients to ensure that the limiting parameters of Section 1.8 are not reached. If the annealing parameters are satisfied then the evaluation criteria of Sections 1.2 and 1.3 will not be exceeded as shown in Section 1. 7. Section 2.1 identifies the measurements and their locations necessary to monitor the annealing parameters of this section.

1.4.B Annealing Temperature and Time at Annealing Temperature Parameters The primary objective in the Palisades annealing program is the recovery of the fracture toughness for all of the materials in the RV beltline region. The required annealing temperatures and times are based on projections of the annealing recovery and reembrittlement response of the RV beltline materials. The process used to establish the material RT Nor and Charpy upper shelf energy after annealing and during subsequent operation, which is detailed in Sections 1.1 and 3 of this report, utilizes the annealing recovery equation de.scribed in NUREG/CR-6327 and the lateral shift reembrittlement trend curve. Actual measurements on annealing recovery and reembrittlement for the Palisades surveillance materials from the Fracture Toughness Recovery and Reembrittlement Assurance Program (described in Section 3) will be used to validate this approach.

TAR 2/5/96 1.4-1

The target inner diameter annealing temperature and time for the Palisades RV anneal will be 850°F to 900°F for 168 hours0.00194 days <br />0.0467 hours <br />2.777778e-4 weeks <br />6.3924e-5 months <br /> (administrative limits). The 850° to 900°F-temperature range will be monitored based on RV beltline ID corrected measured values. Corrected measured values are determined by applying correction factors or calibration coefficients to the measured value. No uncertainty is included (see Section 1.5.C). These parameters have been included in annealing studies and will provide sufficient material property recovery of the radiation produced embrittlement. The annealing recovery correlations in NUREG/CR-6327 are derived from the existing annealing database and provide a summary of the trends in the data. The effects of annealing temperature and time on the transition temperature recovery for the limiting axial weld were derived from the NUREG/CR-6327 recovery equations and are illustrated in Figure 1.4.8-1. An annealing temperature and time of 850°F for 168 hours0.00194 days <br />0.0467 hours <br />2.777778e-4 weeks <br />6.3924e-5 months <br /> provides a 90% transition temperature recovery of this weld.* Projected RT NDT recoveries for the other RV beltline materials are provided in Table 1.1.C-3. While significant reductions in the annealing time can be tolerated with relatively little decrease in the amount of annealing recovery, the longer annealing time is preferable to increase the reliability in predicting the post annealing embrittlement. This added reliability is attributed to the fact that the bulk of the data compiled on reembrittlement rates has come from materials annealed for 168 hours0.00194 days <br />0.0467 hours <br />2.777778e-4 weeks <br />6.3924e-5 months <br />. But as Table 1.4.8-1 indicates, a shorter period of time at 850 ° F will also yield adequate material recovery.

The minimum annealing temperature and time for the Palisades RV beltline materials will be 800°F for 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br />. This criteria has been identified in Section 1.8 as a limiting parameter. The 800°F lower bounding temperature limit is based upon the NUREG/CR-6327 prediction equations, which indicate a pronounced decline in recovery below 800°F. Therefore, to achieve an adequately high level of recovery, the entire RV beltline volume should be above a temperature of 800°F.

Table 1.4.8-1 indicates 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> at 800°F provides a 81.3% recovery of the limiting axial weld material. If this lower time and temperature bound is maintained, it will be possible to demonstrate adequate post anneal toughness for continued operation through the current EOL plus recovery of the construction period. Table 1.4.8-1 also provides the predicted RT Nor recovery of the limiting axial weld material for other temperature and time combinations. These values are provided to indicate that a contingency plan can be implemented if the target annealing temperature and time (850° to 900°F for 168 hours0.00194 days <br />0.0467 hours <br />2.777778e-4 weeks <br />6.3924e-5 months <br />) cannot be achieved due to unforeseen circumstances.

To determine the predicted material recovery, the corrected measured beltline ID temperatures will be time averaged for each location having operable instrumentation. The predicted recovery for the Palisades RV beltline materials will use the minimum time averaged corrected measured temperature of all the locations. This approach conservatively takes the*,minimum value from many ID temperature measurement locations. Recovery predictions will be based on the best estimate temperature measurements, similar to how the NUREG/CR-6327 correlations were derived. Therefore, inclusion of added instrument uncertainty is not warranted to determine expected recoveries. However, instrument uncertainty TAR 2/5/96 1.4-2

will be considered for conservatism when verifying the annealing recovery limiting parameter of. Section 1.8, which applies to the entire beltline volume. Time periods below 800°F will not be included in the above time averaged values.

• The maximum annealing temperature and time will not exceed 900°F for 300 hours0.00347 days <br />0.0833 hours <br />4.960317e-4 weeks <br />1.1415e-4 months <br /> and the maximum annealing temperature will not exceed 940°F. Again these criteria have been identified in Section 1.8 as limiting parameters and they are consistent with the ASME Code Case N-557 on thermal annealing. These bounding limits are set primarily with regard to limiting the potential for creep and other forms of elevated temperature metallurgical degradation rather than for material property recovery.

One of the other potential forms of elevated temperature metallurgical degradation is temper embrittlement. Although there is no direct evidence that annealing will cause temper embrittlement in the RV steels used in the United States, the effects of this phenomenon were considered. Temper embrittlement (temper brittleness) occurs in low alloy ferritic steels when they are heated to temperatures between 900°F and 1100°F. The diffusion of certain impurity elements (e.g., phosphorus, tin, antimony) to grain boundaries can cause the material to become susceptible to low ductility intergranular fracture. Transgranular fracture is the more normal type of fracture without weakened grain boundaries. The diffusion process is manifested by an increased transition temperature and reduced upper shelf energy.

It has been suggested that significant temper embrittlement is unlikely in materials with phosphorus concentrations less than 0.02% (Pelli and T6rr6nen, 1994). Table 1.2.B-1. indicates that none of the Palisades RV beltline materials exceed this value.

The data generated to date in extensive annealing studies on U. S. RV steels in both industry and NRC sponsored programs (NUREG/CR-6327) show no indication of temper embrittlement. This includes experimental evidence showing a lack of intergranular fracture on irradiated impact specimens that have received an annealing treatment. Temper embrittlement has become an elevated issue as a result of research on thermally induced phosphorus migration to the grain boundaries of a simulated HAZ microstructure. In this study, a uniform coarse grain microstructure was created by heat treating material to 1200°C (2192°F) for

0. 5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br />. A reactor vessel weld should have seen such high temperatures for .

very short time periqds due to the heat sink effect of the heavy wall plate material.

As a result, the coarse grain region of HAZ in the reactor vessel should be very small and nonuniform. The low levels of phosphorus and the small size of the coarse grained HAZ in the reactor vessel will limit the effect of phosphorus migration. The finer grain size of the surrounding material has more surface area for the phosphorus to migrate to and should reduce the effect of monolayer phosphorus coating of the grain boundary of the coarse grains*, which leads to the intergranular fracture and the shift in transition temperature.

Clad sensitization is another consideration impacting the maximum temperature in the reactor vessel. Clad sensitization occurs in stainless steels when chromium carbides are formed along the grain boundaries. This formation occurs when the steel is exposed to temperatures in the range of 800°F to 1500°F (Regulatory TAR 2/5/96 1.4-3

Guide 1 .44). Carbon and chromium diffusion to the carbides leave the region adjacent to, the grain boundaries depleted and potentially susceptible to intergranular attack in corrosive conditions. The fabrication post weld heat treatment (PWHT) of the Palisades reactor vessel was performed within the temperature range where sensitization is a concern. As indicated in Section 1.2.C.2.4 the PWHT was performed at temperatures between 1100°F and 1175°F. This fabrication PWHT plus approximately 20 years of service would likely result in .more transformations than would result from the 168 hour0.00194 days <br />0.0467 hours <br />2.777778e-4 weeks <br />6.3924e-5 months <br />, 850°F annealing treatment. Thus the additional time at temperature (700°F to 940°F) on the stainless steel cladding during annealing should have no further practical effects on sensitization.

1.4.C Heatup and Cooldown Parameters Heating the Palisades reactor vessel involves a continuous rise in the heat exchanger temperatures, and a resultant rise in the RV temperature by a thermal radiation process. The heat exchanger temperature will be controlled to maintain the desired heatup rate. The heatup rate is important in that it affects the temperature distributions within the reactor vessel which dictate stresses. The maximum RV stress and the maximum nozzle stress imposed by the annealing process occur at the end of the heatup period and,near the beginning of the hold period, respectively, as indicated in Section 1. 7. The reactor vessel stresses are dictated by the temperature distributions during this period. Thus, a slower rise in temperature near the end of heatup is more beneficial in that it allows time for the thermal energy to distribute more evenly throughout the reactor vessel and PCS piping.

The heatup rate that will be imposed on the Palisades reactor vessel during the annealing operation will be an average of ~25°F/hr from ambient to 850°F (administrative limit) with a slowdown near the end of heatup. This same criteria was used in the thermal and stress analyses described in Section 1 . 7 and the resultant stresses were found to be acceptable by a large margin. This heatup rate coupled with a slowdown near the end of the heatup* allows the thermal energy to distribute more throughout the reactor vessel and PCS piping and avoids an overshoot that could lead to increased stresses. In addition it allows more flexibility at the beginning of heatup to increase at a faster rate but slow down sooner near the end of heatup to meet the average heatup criteria. The analyses in Section 1. 7 did consider a case of a faster initial heatup (approximately 40°F/hr up to 600°F and then slowing down to a resultant average of 25°F/hr) that resulted in a lower peak stress intensity at the end of heatup than the case with a constant heatup of approximately 25°F/hr. The rate of 40°F/hr from ambient to 600°F will be the maximum heatup rate (administrative limit).

Since the reactor vessel and PCS piping are fully insulated and given the mass of these components, the rate at which heat can be removed is limited. However, the heat exchanger, described in Section 1.6, to be used for the Palisades RV annealing allows for forced cooling. This process effectively reduces the time for TAR 2/5/96 1 :4-4

the reactor vessel and PCS piping to reach a safe temperature for termination of the anneali_ng operation. Thus cooling of the Palisades reactor vessel involves a continuous decrease in the heat exchanger temperature, with a resultant decrease in the-RV temp.erature by a thermal radiation process. The heat exchanger temperature will be controlled to maintain the desired cooldown rate. The cooldown rate of the RV beltline inner diameter surface will be ~ 25°F/hr (administrative limit) down to 210°F. After 210°F has been reached the stresses are sufficiently low to not cause further residual stresses therefore a controlled cooldown limit beyond 210°F is not necessary.

1.4.D Temperature Gradients Section 1 . 7 indicates that the stresses created by the annealing process are dictated by the temperature distribution or gradients within the reactor vessel. The most critical temperature gradient is that running axially across the Palisades RV nozzles. This axial temperature gradient results in variable radial thermal displacements along the length of the reactor vessel cylindrical wall. This axial deformation has been identified as the "Coke Bottle" effect and was seen in a past study (Server, 1985) as well as in the analyses documented in Section 1. 7. The variable axial deformation results in the bending of the RV cylindrical shell. This bending causes higher stresses at the upper shell to intermediate shell transition and to a lesser degree at the intermediate shell to bottom head transition. The most significant effect of the RV rotation is the production of a bending of the PCS piping particularly at the RV nozzle to pipe transition (nozzle extension). For the Palisades RV annealing the "coke bottle" effect is less pronounced due to the larger heating zone than was used in the previous studies, however the bending is still present. The means of minimizing the bending stresses is by minimizing the axial temperature gradient across the RV nozzles. From the bounding thermal and stress analyses described in Section 1 . 7 it was determined that an axial temperature gradient across the RV nozzles of ~ 4 70 ° F (administrative limit) between zones L and M, as defined in Section 2.1, could be tolerated with acceptable margins to the Section 1.8 limiting stress parameter. The analyses predicting the expected conditions, however, predict the temperature gradient will be approximately 280°F.

Azimuthal temperature variations are expected to arise from variability in the heat exchanger wall temperatures and from variations in the effectiveness ot the RV insulation. These are expected to be small since the heat exchanger, by the nature of its design, has shown during proof of principle testing to produce uniform heat circumferentially. Also, the RV insulation performance was measured at several locations following the fall 1 995 outage and was found to be uniform circumferentially. The most critical azimuthal gradient in terms of structural integrity is that around the RV flow skirt. This region has been identified since the thin perforated plate of the RV flow skirt is not as stiff as the RV shell to which it is attached, and as such could undergo significant permanent deformation if this azimuthal temperature gradient is not controlled. Other regions in the reactor vessel being thick solid sections can accommodate larger azimuthal temperature gradients. As described in Section 1 . 7, an azimuthal temperature variation at the TAR 2/5/96 1.4-5

RV flow skirt elevation of :::;; 50°F (administrative limit) can be tolerated with sufficient margins.

The least significant temperature gradient is through-wall. Through-wall variations arise due to time-dependent heat dissipation by conduction in the RV steel and the effectiveness of the RV insulation. Through-wall temperature gradients anywhere in the reactor vessel are not of concern from a stress standpoint in this annealing process because they can be accommodated by the thick RV shell material.

Through-wall temperature gradient administrative limits are primarily identified to compare them with the predictions of the thermal and stress analysis. In the analyses described in Section 1 . 7, assuming worst case insulation properties and low ambient air temperatures, the largest through-wall temperature gradient is approximately :::;; 100°F (administrative limit) at the end of the heatup period in the annealing zone. During the hold period it drops to approximately :::;; 50°F (administrative limit), and it reaches approximately :::;; 70°F (administrative limit) near the beginning of cooldown. These through-wall temperature differentials are illustrated in Figure 1 .4. D-1. These temperature gradients can be tolerated with sufficient margins with* respect to the imposed loads.

The through-wall temperature differentials of less than 50°F during the 168 hour0.00194 days <br />0.0467 hours <br />2.777778e-4 weeks <br />6.3924e-5 months <br /> hold period however will cause a variation of the annealing recovery. The effect of a 50°F through wall temperature gradient, assuming an inner diameter temperature of 850°F, on the annealing recovery for the limiting axial weld is illustrated in Figure 1.4.D-2. In this figure, the initial through wall distribution of .t.RTNoT was calculated using the attenuation factor from NRC Regulatory Guide 1.99 Rev. 2.

Annealing recovery was then calculated assuming that the 50°F temperature drop is linear and applying the NUREG/CR-6327 equations. For the 50°F temperature drop, the through-wall fluence attenuation effect is larger than the through-wall temperature decrease effect on annealing recovery, resulting in the reactor vessel ID remaining limiting after the annealing process.

1.4.E Displacements The Palisades reactor vessel will see greater radial and vertical growth during anneal than it experiences during normal operation. Section 1. 7 shows that the displacements created by the annealing process are acceptable with respect to the reactor vessel and the PCS. Similarly for the PCS piping near the RV nozzle to pipe connections (nozzle extensions) the bending moments due to the axial thermal gradient across the RV nozzles during the anneal will exceed the thermal bending moment during normal operation. However, it was shown to be acceptable. The steam generators were shown to translate on their supports within the normal operating bounds. Table 1.4.E.1 provides the current primary coolant pump travel clearances. For the primary coolant pump lateral supports, the analyses of Section 1.7 assumed that none of the travel clearances would be exceeded. However, an analysis of the primary coolant pump piping and lateral supports showed that even if contact were made the stresses in the piping would be acceptable. Therefore, TAR 2/5/96 1.4-6

the clearances given in Table 1.4.E-1 are not included as administrative limits nor as limiting pC1rameters .

The Section 1 . 7 analyses had to make assumptions on the boundary conditions that impact displacement. Operational monitoring will be performed during the annealing process to validate these assumptions.

The operational monitoring that will be performed will be to verify that the system is displacing during heatup at the nozzle supports and the equipment ends (steam generator and primary coolant pumps). Lack of displacement is indicative of an unassumed constraint condition that could potentially increase stresses.

Displacement of primary coolant system piping will be used for this monitoring.

Increased displacements particularly at the equipment ends (steam generators and primary coolant pumps) can be accommodated given the travel clearances for these components. The steam generator travel clearances are less accommodating than the primary coolant pumps in that the piping is straighter and stiffer. Thus these are listed in Section 1 .8 as limiting parameters. Administrative limits for the displacement of the piping have been chosen for confirming the analyses and to establish a reasonable limit prior to reaching the limiting parameter displacement value in Section 1.8. The radial displacement of the piping will be less than 1.375" (administrative limit) which is based on the expected maximum movement plus allowance for variance in the potential starting point of the initial resting position.

The vertical displacement of the piping run to the steam generators (administrative limit) and the vertical, horizontal, and radial displacements of the piping run to the primary coolant pumps (administrative limit) will be given an administrative range based on prediction from the thermal and stress analysis. These administrative ranges will be included in the annealing procedures after more predictive thermal and stress analyses have been conducted.

Displacement of the RV bottom head (administrative limit) is not as critical since its vertical growth is not constrained. However, if the cold clearance from the RV bottom head to the floor is less than 2 inches then an administrative range will be imposed and included in the annealing procedure based on the results from more predictive thermal and stress analyses. If the cold. clearance is equal to or greater than 2 inches, than the displacement of the RV bottom head is not of concern and will be eliminated as an administrative limit.

1.4.F REFERENCES

1. Eason, E. et al, "Models for Embrittlement Recovery Due to Annealing of Reactor Pressure Vessel Steels", NUREG/CR-6327, February 1995.

2. U. S. NRC Draft Regulatory Guide DG-1027, ."Format and Content of Application for Approval for Thermal Annealing of Reactor Pressure Vessels",

October 1994.

TAR 2/5/96 1.4-7

3. *

• ASME Code Case N-557, "In-Place Dry Annealing of a Nuclear Reactor Vessel~ Section XI, Division 1 ", Cases of the ASME Boiler and Pressure Vessel Code.

4. Pelli, R. and Torronen, K., "State of the Art Review on Thermal Annealing",

AMES Report No. 2, December 1994.

5. U. S. NRC Regulatory Guide 1.44, "Control of the Use of Sensitized Stainless Steel", U. S. NRC, May 1973.

6. Server, W. L., "In-Place Thermal Annealing of Nuclear Reactor Pressure Vessels", NUREG/CR_-4212, April 1985.

7. Regulatory Guide 1.99, Revision 2, "Radiation Embrittlement of Reactor Vessel Materials", U. S. NRC, May 1988.

TAR 2/5/96 1.4-8

• 1 I Parameter I Limit 1 I Comments I

RV Heatup Rate Avg. ~ 25 °F/hr heatup rate from Based on RV beltline ID temperatures ambient to 850°F RV Heatup Rate 40°F/hr maximum heatup rate Based on RV beltline ID temperatures from ambient to 600°F RV Time at Temperature Hold at 850°F to 900°F for 168 Based on RV beltline ID temperat~res hours RV Beltline Through-Wall ~ 100°F/hr Heatup Based on RV beltline ID and OD Temperature Gradient ~ 50°F/hr Hold temperatures

~70°F/hr Cooldown RV Azimuthal Temperature <50°F Based on maximum to minimum OD Gradient temperatures near the flow skirt elevation RV Axial Temperature Gradient ~470°F Nozzle region temperatures on RV ID, between Zones L and M as defined in Section .2. 1 RV Bottom Displacement Displacement rangel 2l If the cold clearance at the RV bottom is greater than 2 inches then this limit will be eliminated Steam Generator Displacement ~ 1.375 inches Based on PCS loop piping radial displacement monitoring Table 1.4.A-1 Administrative Limits For the Palisades Reactor Vessel Anneal (Page 1 of 2)

TAR 2/5/96 1.4-9

I Parameter I Limit 1 I Comments I

)

12 PCS Piping Displacement Displacement range l Based on PCS loop piping vertical displacement monitoring on run to each steam generator 12 PCS Piping Displacement Displacement range l Based on PCS loop piping {x, y, z) displacement monitoring on run to each pump RV Cooldown Rate Avg. surface temperature Based on RV beltline ID temperatures cooldown rate =::;25°F/hr to 210°F Notes: 1. The corrected measured value for the sensors will be used. Corrected measured values are determined by applying correction factors or calibration coefficients to the measured value. No uncertainty is included.

2. Displacement range to be determined prior to annealing.

Table 1.4.A-1 Administrative Limits For the Palisades Reactor Vessel Anneal (Page 2 of 2)

TAR 2/5/96 1.4-10

j f

j Anneal Time lI Annealing Temperature 850°F 48 hrs (2 Days) 86.9%

72 hrs (3 Days) 88.1%

96 hrs (4 Days) 88.9%

120 hrs (5 Days) 89.5%

144 hrs (6 Days) 89.9%

168 hrs (7 Days) 90.3%

800°F 81.3% 82.8% 83.8% 84.5% 85.1% 85.6%

Table 1.4.B-1 Predicted RT NDT Recovery of Limiting Axial Weld Material for Early Termination and/or Reduced Temperature Anneal for Palisades

• TAR 2/5/96 1 .4-11

PCP "A" PCP "B" PCP "C" PCP "D" inches inches inches inches "A" Foot East Lateral 0.364 0.258 0.225 0.528 "A" Foot West Lateral 0.260 0.364 0.425 0.110 "A" Foot Anchor Plate 0.025 0.018 0.044 0.027 "A" Foot Stop 1.855 1.856 1.401 1.545 "B" Foot East Lateral 0.379 0.259 0.171 0.406 "B" Foot West Lateral 0.258 0.330 0.459 0.193 "B" Foot Anchor Plate 0.027 0.036 0.018 0.055

... B" Foot Stop 2.60 1.864 1.519 1.260 "C" Foot Ea.st Lateral 0.303 0.259 0.228 . 0.499 "C" Foot West Lateral 0.297 0.315 0.410 0.140 "C" Foot Anchor Plate 0.017 0.039 0.060 0.042 "C" Foot Stop 1.779 1.665 1.417 1.423 "D" Foot East Lateral 0.408 0.275 0.190 0.450 "D" Foot West Lateral 0.259 0.310 0.450 0.215 "D" Foot Anchor Plate 0.066 0.048 0.040 0.065 "D" Foot Stop 1.923 1.823 1.405 1.178 TABLE 1.4.E-1 Current Primary Coolant Pump Travel Clearances TAR 2/5/96 1.4-12

jl 100 850°F 9 0 --

80 --

, .,../

.,..,,. - ---- ...... __.,. 800°F 7 0 --

6 0 ,_

5 33° F Irradiations Annealing Temperature Noted 50 -

Cu= 0.212%

Flux =3.4x1010 n/cm2 /sec 40 Fluence =1.45x1019n/cm 2 750°F ...

30 20

• f f

10 *.

I I 0 I I I 0 1 2 3 4 5 6 7 Annealing Time (days)

Figure 1.4-B-1 Predicted RTNOT Recovery Rate for an Irradiated Palisades Weld TAR 2/5/96 1.4-13

/i

'1 '

100 Top (Ti - T0 )

- - - Middle (Mi -M 0 )

- - - - - Bottom (Bi - 80 )

-80 0 50 100 150 200 Time (Hours) 250 300 350 400 **

Figure 1.4.D-1 Palisades Annealing Zone Through-Wall Temperature Gradients - Case T1 (20 Analysis)

TAR 2/5/96 1.4-14

300 Axial Weld 0.212 Cu 1.02 Ni 250 Tirr 533°F ID Fluence 1.45x1019 L&..

0 200 150

.....c a:

<:I 100 50 Post Anneal 0

0 2 3 4 5 6 Depth from ID (inches) 7 8 9 10

• Figure 1.4.D-2 Through-Wall Annealing Recovery with Assumed Through-Wall Temperature Gradient 850-8000F .

TAR 2/5/96 1.4-15

ATTACHMENT 2 CONSUMERS POWER COMPANY PALISADES PLANT DOCKET 50-255 THERMAL ANNEALING REPORT SECTION 2 REQUALIFICATION INSPECTION AND TEST PROGRAM SECTION 2.1 MONITORING THE ANNEALING PROCESS 8 Pages

2.

REQUALIFICATION INSPECTION & TEST PROGRAM

2. 1 MONITORING THE ANNEALING PROCESS This section identifies the measurements and locations necessary to monitor the annealing process with respect to the administrative limits of Section 1 .4 and the limiting parameters of Section 1.8. This section specifically identifies the measurement type, measurement locations, operating range, target measurement uncertainty, and recording frequency. The measurement instrumentation to be used during the thermal annealing including the control requirements and recording methodology are described in Section 1.5. The relationship of the administrative limits identified in Section 1.4 and the associated monitoring points is presented in Table 2. 1.A-3. The relationship of the annealing limiting parameters identified in Section 1.8 and the associated monitoring points is presented in Table 2.1.A-4.

2.1.A Monitoring Approach Tables 2.1 .A-1 and 2.1 .A-2 present the attributes for each monitoring point taking into consideration the administrative limits of Section 1 .4 and the limiting parameters of Section 1.8. The planned locations for the measurements, the measurement type, the planned number of measurement locations, the instrument operating range, measurement target uncertainty, and the measurement frequency are given. A more detailed description of the monitoring strategy is provided in Section 1.5. The recording equipment is also described in Section 1.5. Figures 1.5.8-1 and 1.5.8-2 present schematically the measurement location arrangements.

Specific requirements regarding axial, azimuthal, and through-wall temperature gradients, temperature and displacement limits, heatup and cooldown rates, and the required annealing temperature range to be achieved are detailed in Section 1 .4. Table 2.1.A-3 shows how these requirements are to be monitored. Table 2.1.A-4 shows how the specific limiting parameters detailed in Section 1.8 are to be monitored. The data acquisition systems and in general how those systems will be used to monitor temperatures and displacements during the annealing process are described in Sections 1.5.C and 1.5.D.1.

For any measurement, the corrected measured value is determined by applying correction factors or calibration coefficients to the measurement in order to compensate for known measurement methodology bias uncertainty. The total measurement uncertainty is *an estimate of the range of unkn_own error in the corrected measured value. For the Palisades measurement system, the total measurement uncertainties are quantified in Table 2.1.A-1 for internal temperature sensors and Table 2.1.A-2 for external temperature and displacement sensors. It should be noted that these are target uncertainties based on initial uncertainty evaluations and present estimated conditions. As the conditions become more defined for the annealing operation revised uncertainty analyses will be performed to characterize the total measurement uncertainty. The sensitivity of measured TAR 2/5/96 2.1-1

• .l values to various sources of uncertainty will be assessed within. the context of the uncertainty analysis described in Section 1.5.

Since the total measurement uncertainty represents potential error in the corrected measured value, procedural limits will be placed on the limiting parameters of Table 2.1.A-4 as a conservative measure to ensure that they are not exceeded. These procedural limits will use the total measurement uncertainty with corrected measured values. For example, the corrected measured temperature of the RV ID surface will not exceed 91 5°F (limiting corrected measured temperature based on a target uncertainty not to exceed 25°F) as determined by the internal temperature sensors thereby assuring that the metal temperature will not exceed the 940°F limit defined in Section 1 .8. A similar philosophy will be used for all limiting parameter temperature and displacement measurements except stress as defined in Table 2.1.A-4.

Stresses will be monitored during the annealing process using a computer program which simulates the relationship between the computed stresses and the corrected measured temperature gradients between temperature sensors. This is necessitated by the difficulty in accessing key locations for strain gauge sensor placement both from a geometrical and personnel radiation exposure standpoint.

Since the measurements are of temperature differences and not absolute temperatures the corrected measured values will be used. Thus with corrected measured temperature differences between selected sensors a predicted stress can be established and compared against the stress limiting parameter of Section 1.8.

This monitoring will occur essentially on-line.

Displacements being measured at the RV bottom and on the PCS loop piping are intended to serve as an additional confidence factor in ensuring that the stresses are as predicted by the thermal and stress analysis. The criteria for these displacements are described in Section 1.4.E.

For the administrative limits of Table 2.1.A-3 a margin still exists before the limiting parameters are reached, thus adding uncertainty to the corrected measured values is not necessary. Therefore, for the administrative limits the corrected measured values of temperature and displacement will be used.

RV axial temperature gradients across the nozzles will be calculated by comparing RV shell internal temperature sensors in adjacent rows (i.e. lower zone L versus zone M), within a particular column of sensors. Azimuthal temperature gradients will be calculated by comparing the sensors within a particular row of shell temperature sensors. Through wall temperature gradients within the RV beltline a

will be calculated by comparing each shell extern If temperature sensor within the beltline with the nearest shell internal temperature sensor. These calculated temperature gradients along with heatup and cooldown rates will be checked against the administrative limits with the data acquisition system, as described in Section 1.5.D.1. Internal and external temperature sensors within the annealing TAR 2/5/96. 2.1-2

zone itself will also be verified as having obtained the required annealing temperature, for the required duration.

The annealing will be verified by documenting the time-history of temperatures and displacements. A hard copy tabular printout of all measurements will be recorded in accordance with written procedures and will be retained in accordance with Palisades Administrative Procedures for the life of the plant. A summary of the data results will be included in the annealing certification report.

2.1.B Monitoring Contingency Approach Whereas the method of measurement described in Section 1 . 5 and summarized in Table 2.1.A-1 and Table 2.1.A-2 is planned to be implemented, unforeseen circumstances may result in the loss of the operation of installed sensors or an inability to install such sensors. Given the difficulties associated with remote installation, a necessity given the radiation exposure and limited access concerns, such circumstances cannot be ruled out. Thus a monitoring contingency approach has been defined which uses as a basis the redundancy of measurements described in Section 1.5, This redundancy of measurements will ensure no loss of critical data or controllability especially in regard to that described in Tables 2. 1.A-3 and 2.1.A-4.

This is accomplished primarily through the use of backup sensors at measurement locations. Redundancy is also achieved by symmetrically located instruments due to the symmetry of the structure and loads, and by the proximity of one or more other instruments where symmetry does not exist. A minimum number of sensors in each zone, however, is required for this approach to be valid.

Tables 2.1.A-3 and 2.1.A-4 provide the minimum number of operational sensors needed to define the monitoring condition. This minimum number, also satisfies the requirements specified in DG-1027.

2.1.C Test to Verify Monitoring Approach The monitoring approach methodology contained in Sections 2.1.A and 2.1.B above will be validated during the annealing demonstration at Marble Hill or by utilizing the sensor data compiled from the annealing demonstration coupled with the Marble Hill thermal and stress analysis model.

TAR 2/5/96 2.1-3

Zone Number of Instrument Target Recording*

Zone Description 131 Measurement Locations 111 121 Operating Range Uncertainty Frequency 141_

( ~) (minutes)

E Nozzle - Bottom Temperature 6 32 - 950 °F 25 °F 5 .

F Nozzle - Top Temperature 6 32 - 950 °F 25 °F 5 K Reactor Vessel Temperature 30 32 - 950 °F 25 °F 5 Shell -

Annealing Zone L Reactor Vessel Temperature 12 32 - 950 °F 25 °F 5 Shell - Above the Nozzles M Reactor Vessel Temperature 12 32 - 950 °F 25 °F 5 Shell - Above the Annealing Zone N Reactor Vessel Temperature* 6 32 - 950 °F 25 °F 5 Shell - Below the Annealing Zone Notes: 1. A primary and backup sensor are installed at each location.

2. 144 total internal temperature sensors: 72 primary temperature; and 72 backup temperature.

3. Section 1.5 contains more details on location and instrument descriptions.

4. Measurements will be taken throughout the annealing process including heatup, soak or hold period, and cooldown.

Table 2. 1.A-1 Internal Monitoring Points for Palisades Reactor Vessel Annealing Requalification TAR 2/5/96 2.1-4

Number of Instrument Target Recording Zone Zone Description 13> Measurement Locations 121 Operating Range Uncertainty Frequency!4l

( s) (minutes)

A Reactor Vessel - Temperature 31n 32-950 Of 20 Of 5 Bottom Displacement 1 (1) 0 - 3 II 0.1 II B RV Annealing Temperature 3111 32-950 Of 20 Of 5 Zone - Bottom c

D RV Annealing Zone - Middle RV Annealing Zone - Top Temperature Temperature 311) 3111 32-950 Of 32-950 Of 15 Of 20 Of 5

5 G RV Support Temperature 111)32-650 Of 20 Of 5 Structure - Region 2

H Reactor Cavity Temperature 21n 32-500 Of 10 Of 5 Steel Liner -

R~_gion 2 I PCS Loop Piping Displacement 6 0 - 2 II 0.05 II 5 J Reactor Cavity Temperature 211)32-500 Of 10 Of 5 Steel Liner -

Region 3 Notes: 1. A primary and backup sensor are installed at each location.

2. Total external sensors: 19 primary and 1 backup displacement; and 17 primary and 17 backup temperature.

3. Section 1.5 contains more details on location and instrument descriptions.

4. Measurements will be taken throughout the annealing process including heatup, soak or hold period, and cooldown.

Table 2. 1.A-2 External Monitoring Points for Palisades Reactor Vessel Annealing Requalification TAR 2/5/96 2.1-5

Measurement Component I Key Monitoring Monitoring Minimum Number of Sensors Needed for Category Structure Condition 11 >< 31 Zone 171 Monitoring Condition 121 Temperature RV Beltline ID Avg. ~ 25°F/hr K One at each elevation heatup rate from ,,

ambient to 850°F 2

Temperature RV Beltline ID 4.0°F/hr max. heatup K One at each elevation < >

rate from ambient to 600°F 121 Temperature RV Beltline ID Hold at 850°F to K One at each elevation 900°F for 1 68 hours7.87037e-4 days <br />0.0189 hours <br />1.124339e-4 weeks <br />2.5874e-5 months <br /> Temperature RV Beltline ~ 100°F Heatup B,C, D One per zone Gradient, ~ 50°F Hold Through-Wall ~ 70°F Cooldown K One at each elevation Temperature RV Flow Skirt ~5Q°F A Two Gradient, Azimuthal Temperature RV Nozzle ~470°F L One, lower elevation above a nozzle Gradient, Axial M One, aligned vertically with the L sensor 151 141 Displacement RV Bottom Displacement range A One Displacement Steam ~ 1.375 inches I One radial direction on run to each steam Generator generator 161 Table 2. 1.A-3 Administrative Limit Monitoring for the Palisades Reactor Vessel Anneal (Page 1 of 2)

TAR 2/5/96 2.1-6

Measurement Component I Key Monitoring Monitoring Minimum Number of Sensors Needed for Category Structure Condition 11 >< 3 > Zone 171 Monitoring Condition Displacement PCS Piping to Displacement range 151 I One vertical direction on run to each StE!am Steam generator 161 Displacement Generator PCS Piping to Primary Coolant Pump Displacement range 151 I One set (x, y, and z directions) on run to a pump1s1

• Temperature RV Beltline ID Avg. Surface Temp. K One at each elevation 121 Cooldown Rate

~ 25°F/hr down to 210°F Notes: 1. Section 1 .4 contains more details on monitoring condition descriptions.

2. Sensors not all aligned vertically

3. The corrected measured value for the sensors will be used. Corrected measured values are determined by applying correction factors or calibration coefficients to the measured value. No uncertainty is included.

4. If the cold clearance at the RV bottom is greater than 2 inches then this sensor is not necessary.

5. Displacement range to be determined prior to annealing.

6. Manual measurements will provide an adequate means of redundancy.

7. Section 1. 5 contains more details on location and instrument descriptions.

• Table 2. 1.A-3 Administrative Limit Monitoring for the Palisades Reactor Vessel Anneal (Page 2 of 2)

TAR 2/5/96 2.1-7

Limiting Parameter I Location Limiting Parameter I Monitoring Minimum Number of Sensors Needed Condition Condition 121131 Zones 151 for Monitoring Condition Category Time at RV Beltline Soak period of > 48 hours B,C, D One per zone Temperature above 800°F 111 K One at each elevation Time at Reactor Cannot exceed 900°F for M,N One per zone Temperature Vessel greater than 300 hours0.00347 days <br />0.0833 hours <br />4.960317e-4 weeks <br />1.1415e-4 months <br /> K, L One at each elevation per zone 111 Time at Reactor Cannot exceed 850°F for M,N One on each zone Temperature Vessel greater than 1000 hours0.0116 days <br />0.278 hours <br />0.00165 weeks <br />3.805e-4 months <br /> K, L One at each elevation per zone 111 Temperature Reactor Cannot exceed 940°F M,N One per zone Vessel K, L One at each elevation per zone 111 Temperature Biological Cannot exceed 250°F J One per zone Shield Wall Concrete H One at each elevation Stress Reactor Maintain.primary plus A, B, C, D, M, N One per zone Vessel, PCS secondary stress intensities.

Piping below the 3Sm criteria E, F One on either zone, in each nozzle K, L One at each elevation per zone 111 Displacement Notes: 1.

Steam Generators SG "A" displacement limit of 1 .99 in. and SG "B" displacement limit of 1 .41 in.

Sensors not all aligned vertically.

I One radial direction on run to each steam generator 141

2. Section 1.8 contains more details on monitoring condition descriptions.

3. The corrected measured value for the sensors with uncertainty will be used.

4. Manual measurements will provide an adequate means of redundancy.

5. Section 1.5 contains more details on location and instrument descriptions.

Table 2. 1.A-4 Limiting Parameter Monitoring for the Palisades Reactor Vessel Anneal TAR 2/5/96 2.1-8