ML21210A300

Relief Request 67 - Request for Alternative Frequency to Containment Unbonded Post-Tensioning System Inservice Inspection

ML21210A300
Person / Time
Site:	Palo Verde
Issue date:	07/29/2021
From:	Rash B Arizona Public Service Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
102-08286-BJR/TNW
Download: ML21210A300 (38)

Text

10 CFR 50.55a BRUCE J. RASH Vice President Nuclear Engineering/Regulatory 102-08286-BJR/TNW Palo Verde July 29, 2021 Nuclear Generating Station P.O. Box 52034 Phoenix, AZ 85072 U.S. Nuclear Regulatory Commission Mail Station 7602 Tel 623.393.5102 ATTN: Document Control Desk Washington, DC 20555-0001

Subject:

Palo Verde Nuclear Generating Station Units 1, 2, and 3 Docket Nos. STN 50-528, 50-529, and 50-530 Renewed Operating License Number NPF-41, NPF-51, and NPF-74 Relief Request 67 - Request for Alternative Frequency to Containment Unbonded Post-Tensioning System lnservice Inspection Pursuant to Title 10 of the Code of Federal Regulations (10 CFR) 50.55a, Codes and Standards, paragraph (z)(1), Arizona Public Service Company (APS) requests Nuclear Regulatory Commission (NRC) approval of the enclosed request for relief from the requirements of Section XI, Subsection IWL of the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel (BPV) Code. Per the ASME BPV Code, the periodic visual examination and physical testing of containment building concrete are required in accordance with Table IWL-2500-1 (L-A), as well as physical testing of unbonded post-tensioning systems in accordance with Table IWL-2500-1 (L-B).

Examination and testing to date have indicated the post-tensioning system at Palo Verde Nuclear Generating Station (PVNGS) will continue to maintain its safety-related function through the period of extended operation. Therefore, APS proposes to extend the post-tensioning system examination and testing interval from 10 years to 20 years for Units 1 and 3. For Unit 2, the NRC approved a delay in performing the Unit 2 test for one year due to COVID-19 in Relief Request 66. The due date was extended from February 8, 2021, to February 8, 2022. As a result, the potential for an alternative examination schedule for the Unit 2 post-tensioning system examinations and tests will be evaluated after this data has been collected.

APS also proposes an alternative for PVNGS Units 1, 2, and 3 to limit the scope of tendons required to be detensioned for wire removal and examination, elongation measurement, and to eliminate the requirement of IWL-2523.2(b) to perform tendon wire tension testing.

The proposed alternatives are requested for the third and subsequent fourth intervals.

A pre-submittal meeting was held between APS and the NRC staff on June 16, 2021.

APS requests approval of the relief request by June 30, 2022.

A member of the STARS Alliance, LLC Callaway

• Diablo Canyon

• Palo Verde

• Wolf Creek

102-08286-BJR/TNW ATTN: Document Control Desk U.S. Nuclear Regulatory Commission Relief Request 67 - Request for Alternative Frequency to Containment Unbonded Post-Tensioning System lnservice Inspection Page 2 No new commitments are being made to the NRC by this letter. Should you need further information regarding this letter, please contact Matthew S. Cox, Licensing Section Leader, at (623) 393-5753.

Sincerely, Digitally signed by Rash, Rash, Bruce Bruce (Z77439)

DN: cn=Rash, Bruce (Z77439)

(Z77439) Date: 2021.07.29 09:11:15

-07'00' BJR/TNW/mg

Enclosure:

Relief Request 67 - Proposed Alternative in Accordance with 10 CFR 50.55a(z)(1) for Inservice Inspection of the Containment Post-Tensioning System Components cc: S. A. Morris NRC Region IV Regional Administrator S. P. Lingam NRC NRR Project Manager for PVNGS L. N. Merker NRC Senior Resident Inspector for PVNGS

Enclosure Relief Request 67 Proposed Alternative in Accordance with 10 CFR 50.55a(z)(1) for Inservice Inspection of the Containment Post-Tensioning System Components

Enclosure Relief Request 67 Arizona Public Service Company Palo Verde Nuclear Generating Station - Units 1, 2, and 3 Proposed Alternative in Accordance with 10 CFR 50.55a(z)(1) for Inservice Inspection of the Containment Post-Tensioning System Components

1. ASME CODE COMPONENTS AFFECTED:

Components: Units 1, 2, and 3 Concrete Containments Code Class: Class CC Examination Category: Category L-B, Unbonded Post-Tensioning System Code Item Numbers: L2.10, L2.20, L2.30, L2.40, and L2.50

Description:

Examination of Concrete Containment Unbonded Post-Tensioning System Components

2. APPLICABLE CODE EDITION AND ADDENDA:

The applicable edition and addenda of the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code (BPV),Section XI for the third 10-year Containment Inservice Inspection Interval (IWL) is identified below.

Applicable ASME Code, Interval Start Interval End Plant/Unit(s) Section XI Date(1) Date(2)

Palo Verde Units 1, 2, and 3 2013 Edition 08/01/2021 07/31/2031 Notes:

1. Inservice inspection plans for the third 10-year Containment Inservice Inspection Interval (IWL) are currently under development.

2. The inspection interval end date may be extended by as much as one year and may be reduced without restriction in accordance with IWA-2430(c)(1).

3. APPLICABLE CODE REQUIREMENTS:

3.1 IWL-2420 specifies scheduling requirements for unbonded post-tensioning systems. IWL-2421(b) provides alternative scheduling requirements for examination and testing of post-tensioning systems at sites with multiple plants that have met the conditions specified in IWL-2421(a), as follows:

(b) When the conditions of (a) are met, the inspection dates and examination requirements may be as follows.

(1) For the containment with the first Structural Integrity Test, all examinations required by IWL-2520 shall be performed at 1, 3, and 10 years and every 10 years thereafter. In addition, the examinations required by IWL-2524 and IWL-2525 shall be performed at 5 and 15 years and every 10 years thereafter.

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Enclosure Relief Request 67 (2) For each subsequent containment constructed at the site, all examinations required by IWL-2520 shall be performed at 1, 5, and 15 years and every 10 years thereafter. In addition, the examinations required by IWL-2524 and IWL-2525 shall be performed at 3 and 10 years and every 10 years thereafter.

Note: Attachment 1, Tables 1 and 3 show the schedules for IWL-2520 examinations during the Second (current) Containment Inservice Inspection Interval. Table 3 also shows the schedules for performing containment concrete examinations in accordance with IWL-2410, for which an alternative is not being requested.

3.2 IWL-2523.1 requires tendon detensioning and wire sample removal, as follows:

One sample tendon of each type shall be completely detensioned. A single wire or strand shall be removed from each detensioned tendon.

3.3 IWL-2523.2(b) requires that tension tests be performed on each removed wire or strand, as follows:

Tension tests shall be performed on each removed wire or strand: one at each end, one at midlength, and one in the location of the most corroded area, if any. The following information shall be obtained from each test:

(1) yield strength (2) ultimate tensile strength (3) elongation Palo Verde Nuclear Generating Station (PVNGS), Units 1, 2, and 3 currently perform physical and visual examinations of the post-tensioning system in accordance with the schedules specified in IWL-2421(b).

Table IWL-2500-1, Item Number L2.10 requires that selected tendon force and elongation be measured.

Table IWL-2500-1, Item Number L2.20 requires that tendon single wire samples be removed and examined for corrosion and mechanical damage as well as tested to obtain yield strength, ultimate tensile strength, and elongation on each removed wire. The selected tendons are subsequently retensioned as required per IWL-2523.3 because wire removal requires detensioning in order to safely obtain wire samples.

Table IWL-2500-1, Item Number L2.30 requires that a detailed visual examination be performed on selected tendon anchorage hardware and adjacent concrete extending 2 feet from the edge of the bearing plate. The quantity of free water released from the anchorage end cap as well as any which drains from the tendon during examination shall be documented.

Table IWL-2500-1, Item number L2.40 and L2.50 require that samples of selected tendon corrosion protection medium (CPM) and free water be obtained and analyzed.

4. REASON FOR REQUEST:

ASME Section XI, Subsection IWL requires periodic visual examination of Containment Building concrete as well as physical testing and visual examination of post-tensioning systems. The required schedules for these examinations and tests are shown in Tables 1 and 3, and comply with the requirements of the ASME BPV Code,Section XI, IWL-2410 and IWL-2421.

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Enclosure Relief Request 67 Post-tensioning system examinations and tests performed to date have indicated that the post-tensioning systems are expected to maintain their safety-related function through the period of extended operation for PVNGS Units 1, 2, and 3. For this reason, this relief request proposes to perform visual and physical examination of the Units 1 and 3 concrete containment post-tensioning systems in accordance with the schedules identified in Tables 2 and 4. For Unit 2, the NRC approved a delay in performing the Unit 2 test for one year due to COVID-19 in Relief Request 66. The due date was extended from February 8, 2021, to February 8, 2022. As a result, the potential for an alternative examination schedule for the Unit 2 post-tensioning system examinations and tests will be evaluated after this data has been collected.

While this relief request is based on maintaining an acceptable level of quality and safety, there are additional benefits to the proposed examination schedule. Physical testing requires exposing the test personnel to industrial safety hazards. Removing the tendon end caps and load testing or detensioning/retensioning the tendons also unnecessarily cycles the tendons and exposes the system to an unsealed environment during testing. Below are specific hazards and undesirable conditions that would be reduced by this proposed request:

1. Most tendons are located at heights well above ground level that require working at heights and the inherent risks associated with such work.

2. This work is often performed from hanging platforms open to outside weather conditions. The platform must be moved to a parked location in order to exit the platform safely.

3. Some areas are located in difficult-to-reach locations that have limited access.

4. The testing requires working with high pressure hydraulics.

5. Some areas are located in the vicinity of high energy plant systems.

6. The testing requires working with solvents and hot petroleum products and associated fumes.

7. The testing requires working with containers and pressurized lines filled with heated CPM.

8. The testing requires working in the vicinity of high levels of stored elastic energy in the tendons. Sudden rotation during force measurement has resulted in high-speed shim ejection.

9. The work includes handling of heavy loads (i.e., test equipment) that exposes test personnel and equipment to hazards.

10. While tendon testing is most often not performed in radiation areas, there are occasionally some tendons tested in areas that involve radiation fields.

Performing examination/testing on a reduced frequency reduces the repetitive loading required for force measurement or detensioning and retensioning. Reducing the population of tendon end caps removed will minimize tendon hardware exposure to environmental conditions and will reduce environmental waste (e.g., solvents, used CPM, other consumables).

This request also includes alternatives for PVNGS Units 1, 2, and 3 to limit the scope of tendons required to be detensioned for wire removal and examination, elongation measurement, and to eliminate the requirement of IWL-2523.2(b) to perform tendon wire Page 3

Enclosure Relief Request 67 tension testing. Performing wire tension tests to confirm tendon wire material properties continue to meet the wire specification requirements is not warranted, based on examination results obtained since plant construction. Tendon wire visual examinations and elongation measurements should be limited to tendons that have detectable conditions (i.e.,

loss of effective wires in excess of that permitted by the design, or other conditions) that would justify performing these examinations.

5. PROPOSED ALTERNATIVES AND BASES FOR USE:

5.1 Alternative Proposed for Units 1 and 3:

In lieu of the requirement of IWL-2421(b), the following alternative is proposed for Units 1 and 3:

1. Unit 1 - For the containment with the first Structural Integrity Test (S.I.T),

examinations required by IWL-2520 shall be performed at 50 years following completion of the S.I.T and every 20 years thereafter. Examinations required by IWL-2421(b)(1) to be performed in accordance with IWL-2524 and IWL-2525 at 45 years following completion of the S.I.T and every 10 years thereafter.

Containment concrete examinations shall continue to be performed in accordance with IWL-2410.

2. Unit 3 - For the containment with the third S.I.T, examinations required by IWL-2520 shall be performed at 45 years following completion of the S.I.T and every 20 years thereafter. Examinations required by IWL-2421(b)(1) to be performed in accordance with IWL-2524 and IWL-2525 at 40 years following completion of the S.I.T and every 10 years thereafter. Containment concrete examinations shall continue to be performed in accordance with IWL-2410.

Use of this alternative shall be discontinued for any tendon group (vertical, wall hoop, or dome hoop)1 in a unit if any of the following conditions occur:

• The tendon mean force for the tendon group is predicted to be less than the specified minimum required value (MRV) within 40 years following the required completion date of the previous surveillance in which Table IWL-2500-1, Examination Category L-B, Item L2.10 examinations were performed on that unit.

• Replacement of tendon load bearing components (i.e., anchorheads, shims, or complete tendons) in any tendon within a tendon group is required as a result of unacceptable conditions detected during IWL-2520 examinations or plant operation.

Use of this alternative shall also be discontinued for any unit if containment concrete repairs requiring pressure testing in accordance with IWL-5000 are performed on that unit as a result of unacceptable conditions detected during IWL-2510 examinations or plant operation.

The above proposed alternative relates only to pre-stressed tendon tests and the associated examinations that require close-in access to tendon end anchorage areas.

Visual examination of the exposed areas of the containment concrete surface, 1

The PVNGS concrete containments contain both vertical tendons (inverted U tendons) and hoop tendons. Hoop tendons include those located in the containment cylindrical shell (designated wall hoop tendons) and those located in the containment dome (designated as dome hoop tendons).

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Enclosure Relief Request 67 exposed areas of the tendon bearing plates, and tendon end caps will continue to be performed at 5-year intervals in accordance with ASME Section XI, Subsection IWL, Examination Category L-A.

The reduced frequency of physical testing of the Units 1 and 3 post-tensioning systems will continue to provide an acceptable level of quality and safety based on projected performance and implementation of physical testing should visual examination results indicate a need for such testing.

PVNGS Units 1, 2, and 3 shall continue to perform a General Visual examination and Detailed Visual examination (when required) of accessible concrete and exposed steel hardware as required by ASME Section XI, Table IWL-2500-1, Item Numbers L1.11 and L1.12, as modified by 10 Title 10 of the Code of Federal Regulations (10 CFR) 50.55a. The examination and physical testing requirements of ASME Section XI, Table IWL-2500-1, Item Numbers L2.10, L2.20, L2.30, L2.40, and L2.50 will also be performed if the General Visual examination and Detailed Visual examination identify conditions where observations indicate there could be degradation of tendon hardware, as documented by the Responsible Engineer in an engineering evaluation.

Example conditions that could require removal of the tendon end cap and further examination per Item Numbers L2.10, L2.20, L2.30, L2.40, and L2.50 are:

• Evidence of possible damage to the enclosed post-tensioning hardware as indicated by conditions such as end cap deformation found during external visual examination. Conditions observed by removal of the end cap would determine the extent of additional examinations per Item Numbers L2.10, L2.20, L2.30, L2.40, or L2.50.

• Active corrosion on a bearing plate or end cap that requires further investigation as determined by the Responsible Engineer in an engineering evaluation.

• Evidence of corrosion protection medium leakage will be evaluated, and a plan developed that requires further investigation and corrective actions as defined in an engineering evaluation documented by the Responsible Engineer.

5.2 Additional Alternatives Proposed for Units 1, 2, and 3:

1. In lieu of the IWL-2523.1 requirement that one sample tendon of each type be completely detensioned and that a single wire or strand be removed from each detensioned tendon, APS proposes to detension a tendon and remove a single wire for examination only if a tendon anchorage visual examination in accordance with IWL-2524 detects a number of ineffective wires (i.e.,

broken/protruding wires or missing buttonheads) in excess of that permitted by the design, or if required as a result of an engineering evaluation performed in accordance with IWL-3300. Tendons with broken or unseated wires (or detached buttonheads) not documented and accepted during a previous examination shall be evaluated in accordance with IWL-3222.

2. In lieu of the IWL-2523.2(b) requirement to perform tension testing to determine the yield strength, ultimate tensile strength, and elongation of tendon wires, APS proposes to eliminate these test requirements. Visual examinations of tendon wires in accordance with IWL-2523.2(a) shall continue to be performed on any tendon requiring detensioning and elongation measurement in accordance with Page 5

Enclosure Relief Request 67 the alternative proposed above.

5.3 The bases for use of the proposed alternatives are provided below, and are supported by the excellent examination history for these units. A summary of the examination history is provided below.

5.3.1 Summary of IWL-2522 Tendon Force and Elongation Measurements Tendon Prestress Force Figures shown in Attachment 2 illustrate the tendon force measurement history.

• Figures 1 through 5 illustrate the tendon force measurement history for Unit 1.

• Figures 6 through 10 illustrate the tendon force measurement history for Unit 3.

• Figure 11 illustrates the tendon force measurement history for the dome hoop tendons in Units 1 and 3. Because of the relatively small number of dome hoop tendons that have been examined on each unit, this figure is provided to show how the dome tendons are performing collectively in Units 1 and 3. Force measurements from Unit 2 are not included in this figure because dome hoop tendons were not in the selected at random from among the hoop tendons examined during the Unit 2 year 20 and year 25 surveillances.

• Figure 12 illustrates the tendon force measurement history for the wall hoop tendons in Units 1, 2, and 3. Force measurements from Table 7 (Unit 2) are included in this figure. This figure is provided to show how the wall hoop tendons are performing collectively in Units 1, 2, and 3.

• Figure 13 illustrates the tendon force measurement history for the vertical (inverted U) tendons in Units 1, 2, and 3. Force measurements from Table 7 (Unit 2) are included in this figure.

This figure is provided to show how the vertical tendons are performing collectively in Units 1, 2, and 3.

One tendon (Unit 3 H21-005) has detected a lift-off force lower than the predicted lower limit for its tendon group. The measured force in this tendon was 98.6% of the predicted lower limit. Lift-off forces were measured in the adjacent tendons, and these measurements, along with those in tendon H21-005, met the applicable acceptance standards.

Tendon H21-005 was then retensioned to an acceptable force.

The data shows that tendon force measurements have remained above the MRV, and that the predicted average tendon forces for each type of tendon will remain above the required minimum design prestress force well beyond the end of the plant life.

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Enclosure Relief Request 67 Tendon Elongation Measured tendon elongations have either met the applicable acceptance standards, or have been evaluated to confirm that significant changes from previous examinations were not the result of broken tendon wires.

5.3.2 Summary of IWL-2523 Examination Results Tendon Wire Visual Examinations Visual examination of all wires removed from tendons in Units 1, 2, and 3 since initial tendon installation have shown no signs of corrosion or physical damage, demonstrating that the post-tensioning system corrosion protection medium (CPM) has continued to protect tendon wires from corrosion. There have been a few instances where CPM leakage has been identified on containment concrete surfaces, but these conditions have been evaluated and accepted, and the amount of grease loss from tendon sheathing has been minimal. CPM leakage has been attributed to thermal expansion, which has resulted in CPM leakage through construction joints in the containment concrete.

Tendon Wire Tension Testing Results of tension tests on all wires removed from tendons in Units 1, 2, and 3 have met material specification requirements for ultimate tensile strength ( 240 ksi) and elongation ( 4% at failure).

These results support the proposed alternative not to require these physical tests on tendon wires. APS believes that continued testing of tendon wires is unnecessary and that visual examinations performed on wires removed from tendons is sufficient to determine if tendon wire degradation has occurred in that tendon.

5.3.3 Summary of IWL-2524 Examination Results Tendon Anchorage Area Concrete Examinations Tendon anchorage concrete examinations have been performed on anchorage areas of hoop tendons. Cracking of concrete adjacent to bearing plates has been observed, and crack mapping has been documented when such cracking has been detected. These conditions have been accepted by engineering. In a few locations, grout has been performed to fill voids or larger cracks that have been identified. These conditions are considered typical in structures of this age and do not represent evidence of abnormal degradation of the containment or its post-tensioning system.

Concrete surfaces at vertical tendon anchorage areas are covered by permanent steel plates that prohibit access for performing anchorage area concrete examinations.

Tendon Anchorage Hardware and Bearing Plate Examinations The results of visual examinations of tendon anchorage hardware (anchorheads, shims, and buttonheads) and bearing plates have demonstrated that the condition of anchorage components remains acceptable. A limited number of undocumented missing buttonheads Page 7

Enclosure Relief Request 67 have been detected during examinations performed to-date, indicating that corrosion and loss of wires has not been significant. With one exception, corrosion levels of level C or better have been detected in all examinations, with the majority of anchorage components found to have either corrosion level A or B. The single exception was noted on shims at the field end of Unit 1 Tendon H13-019, which had level D corrosion noted. This tendon was refilled with corrosion protection medium to prevent further corrosion.

Corrosion levels for tendon anchorage components have been defined as follows:

A - EXCELLENT CONDITION Bright, uniformly colored wire, but may be somewhat blackened; no foreign matter, visible rust, no pitting.

B - GOOD CONDITION Partial loss of color; little foreign matter and a small quantity of light rust may be present; no pitting.

C - FAIR CONDITION Major loss of color; much foreign matter and a large quantity of light rust may be present; no pitting.

D - USABLE CONDITION Almost total loss of color; much foreign matter and small quantities of heavy rust in the form of a red oxide dust; no pitting.

E - REJECTED CONDITION Areas of hard, crusty, scaly red oxide, when cleaned show definite signs of pitting. Pits are defined as indentations of a depth of 1/64 or deeper and a minimum of 1/32 in diameter.

Protruding buttonheads have been detected following tendon retensioning at Units 1, 2, and 3, but the number of effective wires in these tendons was reduced by no more than two (in addition to any wire removed from a tendon for examination), with the exception of the tendons identified below. Protruding buttonheads observed following retensioning have been attributed to friction forces in the tendon that prevented reseating of the buttonheads. Broken wires were not detected in these tendons, and no broken wires have been detected in any tendon as a result of conditions that have occurred since tendon installation.

Unit 1 Tendon V-40 (Year 10 Surveillance)

Shop and field end visual examinations detected 186 effective wires, prior to detensioning. Following retensioning, seven protruding wires were found at the shop end. Tendon elongation measurements were performed and were evaluated as acceptable. All other examination/test results were acceptable.

Unit 3 Tendon V-28 (Year 1 Surveillance)

Shop and field end visual examinations detected 186 effective wires, prior to detensioning. Following retensioning, three protruding buttonheads were detected at the shop end, and five protruding buttonheads were detected at the field end. All other examinations/tests were acceptable.

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Enclosure Relief Request 67 Unit 3 Tendon H21-005 (Year 3 Surveillance)

Shop and field end visual examinations detected 186 effective wires, prior to detensioning. Following retensioning, 12 protruding buttonheads were detected at the shop end (See Note).

Elongation measurements were evaluated and were found to be acceptable. The prestress force in this tendon was measured to be 98.6% of the prescribed lower limit, and examinations of adjacent tendons was performed that confirmed that the tendon forces remained acceptable. Tendon H21-005 was subsequently retensioned to an acceptable force. All other examinations/tests for this tendon were acceptable.

Note: A wire was not required to be removed from this tendon during this surveillance.

5.3.4 Summary of IWL-2525 Examination Results Tendon Corrosion Protection Medium Analyses Results of tendon CPM tests at PVNGS Units 1, 2, and 3 have met acceptance standards during all examinations, except as noted below.

The results of CPM testing for several surveillances early in the plant life were not located.

Tendon Free Water Collection and Analysis Free water has not been detected during surveillances of vertical and hoop tendons at PVNGS Units 1, 2, and 3.

5.3.5 Summary of IWL-2526 Requirements IWL-2526(b) requires that the total amount of CPM replaced in each tendon sheath be recorded following surveillance activities, and the difference between the amount removed and the amount replaced shall be documented.

There have been a few instances where the difference in the amount of CPM installed and that removed from a tendon exceeded 10% of the tendon net duct volume. In these cases, an evaluation was performed to document the acceptability of this condition, and these tendons have been refilled to ensure that tendon wires and anchorage components continue to be adequately protected from corrosion.

5.3.6 Additional Information Tendon Corrosion Protection Medium (CPM) Leakage Tendon CPM leakage has not been a significant issue at PVNGS. CPM leakage from tendon end caps has been insignificant, and only a few instances of grease leakage have been detected on exterior surfaces of the containment concrete shell, primarily at construction cold joints.

Tendon sheathing is not impermeable, and cracking in concrete can allow for propagation of tendon CPM to leak from tendon sheaths, especially during CPM installation by pumping at high temperature and pressure, or as a result of thermal expansion during periods of extremely hot weather (not atypical for Arizona).

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Enclosure Relief Request 67 Unit 2 Post-tensioning System Examinations Unit 2 post-tensioning system examinations shall continue to be performed in accordance with IWL-2421. In the event that unacceptable conditions are detected during future post-tensioning system examinations performed on any unit (including Unit 2), an engineering evaluation shall be performed in accordance with IWL-3310 and shall address the applicability of the identified condition to other plants at the same site, as required by IWL-3310(b). Additional examinations, tests, or evaluations shall be performed if specified as a result of the engineering evaluation.

Prior to the 20th year surveillance, only visual examinations were performed on Unit 2. As a result, sufficient data has not yet been obtained to support seeking an alternative to the tendon examination frequency for Unit 2.

Selection of Hoop Tendons for Examination (Units 1, 2, and 3)

APS has established two tendon types for implementing requirements of Subsection IWL. These tendon types include vertical tendons (inverted U tendons) and hoop tendons (located in the containment cylindrical shell and dome).

Dome hoop tendons are included in the population of hoop tendons selected at random for examination during surveillances in accordance with Table IWL-2521-1. Using Table IWL-2521-1, Note (2), the required hoop tendon sample size is three, based on a total population of hoop tendons equal to 150 (approximately 30 dome hoop and 120 wall hoop tendons). In the event that the random selection does not include at least one dome hoop tendon, a dome hoop tendon shall be selected at random and shall be added to required hoop tendon sample. In the unlikely event the random selection does not include at least two hoop tendons located in the cylindrical shell, additional wall hoop tendons shall be selected at random and added to required hoop tendon sample. This will ensure that both dome and wall hoop tendons will be selected for examination, allowing APS to obtain data for trending future prestress losses in each of these tendon groups.

Alternative to the requirement of IWL-2523.1 Targeting the IWL-2522 and IWL-2523 examinations and elongation measurements to those tendons whose visual examinations have detected an unacceptable number of ineffective wires, or when required as a result of an engineering evaluation, is appropriate because IWL-2522 and IWL-2523 examinations performed to-date have not detected unacceptable conditions at PVNGS. If unacceptable conditions are detected as a result of anchorage visual examinations, these conditions would require an engineering evaluation, and detensioning of a tendon for wire removal and examination may be required by the engineering evaluation to aid in the evaluation of the tendon condition.

5.4 The results of the inservice examinations conducted at PVNGS, Units 1, 2, and 3 have demonstrated that the post-tensioning systems are continuing to perform their intended function. These post-tensioning systems can be expected to continue to perform the Page 10

Enclosure Relief Request 67 specified design functions until well past the June 1, 2045 (Unit 1), April 24, 2046 (Unit 2),

and November 25, 2047 (Unit 3) expiration of the extended operating licenses. Visual examinations performed every five years in accordance with ASME Section XI, Table IWL-2500-1, Item Numbers L1.11 and L1.12 will be adequate to determine if additional physical testing and examination per Examination Category L-B is required. For these reasons, APS requests authorization to use the proposed alternatives pursuant to 10 CFR 50.55a(z)(1) on the basis that the proposed alternatives provide an acceptable level of quality and safety.

6. DURATION OF PROPOSED ALTERNATIVES:

The proposed alternatives are requested for use during the PVNGS Units 1, 2, and 3 third 10-year containment Inservice Inspection Interval and during the fourth 10-year containment Inservice Inspection Interval, provided the edition of the ASME BPV Code,Section XI required to be used during the fourth Inservice Inspection Interval does not impose requirements that are more stringent than those of the alternatives approved by the NRC in this relief request.

7. PRECEDENTS 7.1 Agencywide Documents Access and Management System (ADAMS) Accession Number ML20287A471. NRC approved dated October 20, 2020. Millstone Power Station, Unit 2, Proposed Alternative Request RR-05-05, Containment Unbonded Post-Tensioning System Inservice Inspection Requirements, dated December 17, 2019 (ML19352B898).

7.2 ADAMS Accession Number ML19182A077. NRC approved dated July 11, 2019. Vogtle Electric Generating Plant, Units 1 and 2, Proposed ISI Alternative VEGP-ISI-ALT-19-01 for Tendon Inservice Inspection Extension, dated February 18, 2019 (ML19049A017).

7.3 ADAMS Accession Number ML19226A023. NRC approved dated September 19, 2019.

Three Mile Island Nuclear Station, Unit 1, Submittal of Relief Request RR-18-01 Concerning Containment Unbonded Post-Tensioning System Inservice Inspection Requirements, dated October 16, 2018 (ML18289A363).

7.4 ADAMS Accession Number ML20206L135. Submittal of Relief Request I4R-11 for Braidwood Station, Units 1 and 2, and Relief Request I4R-18 for Byron Station, Units 1 and 2, Concerning Containment Unbonded Post-Tensioning System Inservice Inspection Requirements, dated July 24, 2020.

8.

REFERENCES:

8.1 ASME BPV Code,Section XI, Subsection IWL, 2013 Edition 8.2 Palo Verde Unit 1, 2nd Inspection Interval Containment Inservice Inspection Program, Subsection IWL, Program No. 2INT-IWL-1 8.3 Palo Verde Unit 2, 2nd Inspection Interval Containment Inservice Inspection Program, Subsection IWL, Program No. 2INT-IWL-2 8.4 Palo Verde Unit 3, 2nd Inspection Interval Containment Inservice Inspection Program, Subsection IWL, Program No. 2INT-IWL-3 Page 11

Enclosure Relief Request 67 Attachment 1 (Tables)

Enclosure Relief Request 67 Attachment 1 Table 1 Post-Tensioning System Examination Schedules (Using IWL-2421) 2nd Interval 3rd Interval 4th Interval Unit 1 30th 35th 40th 45th 50th 55th Year Year Year Year Year Year All IWL-2520 Exams/Tests Required(1) Yes(3) Yes Yes Only IWL-2524/IWL-2525 Exams/Tests Required(2) Yes(3) Yes Yes 2nd Interval 3rd Interval 4th Interval Unit 2 30th 35th 40th 45th 50th 55th Year Year Year Year Year Year All IWL-2520 Exams/Tests Required(1) Yes Yes Yes Only IWL-2524/IWL-2525 Exams/Tests Required(2) Yes(3) Yes Yes 2nd Interval 3rd Interval 4th Interval Unit 3 25th 30th 35th 40th 45th 50th Year Year Year Year Year Year All IWL-2520 Exams/Tests Required(1) Yes(3) Yes Yes Only IWL-2524/IWL-2525 Exams/Tests Required(2) Yes(3) Yes Yes Notes:

1. Includes all examinations and tests required by IWL-2522, -2523, -2524, -2525, and -2526 (Table IWL-2500-1, Examination Category L-B).

2. Includes only those examinations and tests specified in Table IWL-2500-1, Examination Category L-B, Item Number L2.30 (Visual Examination Tendon Anchorage Hardware and Concrete), Item Number L2.40 (Examination of Corrosion Protection Medium) and Item Number L2.50 (Examination of Free Water).

3. These examinations have been completed.

Page 1

Enclosure Relief Request 67 Attachment 1 Table 2 Post-Tensioning System Examination Schedules Using IWL-2421 for Unit 2 and Proposed Alternative Schedules for Units 1 and 3 2nd Interval 3rd Interval 4th Interval Unit 1 30th 35th 40th 45th 50th 55th Year Year Year Year Year Year All IWL-2520 Exams/Tests Required(1) Yes(4) No Yes Only IWL-2524/IWL-2525 Exams/Tests Required(2) Yes(4) Yes Yes 2nd Interval 3rd Interval 4th Interval (3)

Unit 2 30th 35th 40th 45th 50th 55th Year Year Year Year Year Year All IWL-2520 Exams/Tests Required(1) Yes Yes Yes Only IWL-2524/IWL-2525 Exams/Tests Required(2) Yes(4) Yes Yes 2nd Interval 3rd Interval 4th Interval Unit 3 25th 30th 35th 40th 45th 50th Year Year Year Year Year Year All IWL-2520 Exams/Tests Required(1) Yes(4) No Yes Only IWL-2524/IWL-2525 Exams/Tests Required(2) Yes(4) Yes Yes Notes:

1. Includes all examinations and tests required by IWL-2522, -2523, -2524, -2525, and -2526 (Table IWL-2500-1, Examination Category L-B).

2. Includes only those examinations and tests specified in Table IWL-2500-1, Examination Category L-B, Item Number L2.30 (Visual Examination Tendon Anchorage Hardware and Concrete), Item Number L2.40 (Examination of Corrosion Protection Medium) and Item Number L2.50 (Examination of Free Water).

3. The Unit 2 schedule will continue to follow the schedule required by IWL-2421 in the 2013 Edition during the 3rd Interval.

4. These examinations have been completed.

Page 2

Enclosure Relief Request 67 Attachment 1 Table 3 Palo Verde Units 1, 2, and 3 Containment Concrete and Post-Tensioning System Examination Schedules Using IWL-2410 and IWL-2421 2019 2020 2021 2022 2023 2024 2025 2026 2027 2028 2029 2030 2031 2032 2033 2034 2035 2036 2037 2038 2039 2040 2041 2042 Unit 1 (S.I.T. Date: 12/25/1982) 40th yr 45th yr 50th yr 55th yr All IWL-2520 IWL-2524/2525 All IWL-2520 IWL-2524/2525 Exams Exams Only Exams Exams Only 12/25/2021- 12/25/2026- 12/25/2031- 12/25/2036-12/25/2023 12/25/2028 12/25/2033 12/25/2038 IWL-2410 IWL-2410 IWL-2410 IWL-2410 Concrete Exams Concrete Exams Concrete Exams Concrete Exams 09/04/2020 - 09/04/2025 - 09/04/2030 - 09/04/2035 -

09/04/2022(1) 09/04/2027 09/04/2032 09/04/2037 Unit 2 (S.I.T. Date: 02/08/1985) 35th yr 40th yr 45th yr 50th yr 55th yr All IWL-2520 IWL-2524/2525 All IWL-2520 IWL-2524/2525 All IWL-2520 Exams Exams Only Exams Exams Only Exams 02/08/2019- 02/08/2024- 02/08/2029- 02/08/2034- 02/08/2039-02/08/2022(2) 02/08/2026 02/08/2031 02/08/2036 02/08/2041 IWL-2410 IWL-2410 IWL-2410 IWL-2410 IWL-2410 Concrete Exams Concrete Exams Concrete Exams Concrete Exams Concrete Exams 09/06/2020 - 09/06/2025 - 09/06/2030 - 09/06/2035 - 09/06/2040 -

09/06/2022(1) 09/06/2027 09/06/2032 09/06/2037 09/06/2042 Unit 3 (S.I.T. Date: 09/16/1986) 35th yr 40th yr 45th yr 50th yr All IWL-2520 IWL-2524/2525 All IWL-2520 IWL-2524/2525 Exams Exams Only Exams Exams Only 09/16/2020- 09/16/2025- 09/16/2030- 09/16/2035-09/16/2022 09/16/2027 09/16/2032 09/16/2037 IWL-2410 IWL-2410 IWL-2410 IWL-2410 Concrete Exams Concrete Exams Concrete Exams Concrete Exams 09/07/2020 - 09/07/2025 - 09/07/2030 - 09/07/2035 -

09/07/2022(1) 09/07/2027 09/07/2032 09/07/2037 Notes:

(1) IWL-2410 examination schedule is based on the initial IWL-2410 examinations having been completed in September, 2001.

(2) Date extended from 02/08/2021 to 02/08/2022, ADAMS Accession No.: ML21089A010.

Page 3

Enclosure Relief Request 67 Attachment 1 Table 4 Palo Verde Units 1, 2, and 3 Containment Concrete and Post-Tensioning System Examination Schedule Using Proposed Alternative to IWL-2421 (Units 1 and 3 Only) 2019 2020 2021 2022 2023 2024 2025 2026 2027 2028 2029 2030 2031 2032 2033 2034 2035 2036 2037 2038 2039 2040 2041 2042 Unit 1 (S.I.T. Date: 12/25/1982) 40th yr 45th yr 50th yr 55th yr No IWL-2520 IWL-2524/2525 All IWL-2520 IWL-2524/2525 Exams Exams Only Exams Exams Only 12/25/2021- 12/25/2026- 12/25/2031- 12/25/2036-12/25/2023 12/25/2028 12/25/2033 12/25/2038 IWL-2410 IWL-2410 IWL-2410 IWL-2410 Concrete Exams Concrete Exams Concrete Exams Concrete Exams 09/04/2020 - 09/04/2025 - 09/04/2030 - 09/04/2035 -

09/04/2022(1) 09/04/2027(1) 09/04/2032(1) 09/04/2037(1)

Unit 2 (S.I.T. Date: 02/08/1985) 35th yr 40th yr 45th yr 50th yr 55th yr All IWL-2520 IWL-2524/2525 All IWL-2520 IWL-2524/2525 All IWL-2520 Exams Exams Only Exams Exams Only Exams 02/08/2019- 02/08/2024- 02/08/2029- 02/08/2034- 02/08/2039-02/08/2022(2)(3) 02/08/2026(3) 02/08/2031(3) 02/08/2036(3) 02/08/2041(3)

IWL-2410 IWL-2410 IWL-2410 IWL-2410 IWL-2410 Concrete Exams Concrete Exams Concrete Exams Concrete Exams Concrete Exams 09/06/2020 - 09/06/2025 - 09/06/2030 - 09/06/2035 - 09/06/2040 -

09/06/2022(1) 09/06/2027(1) 09/06/2032(1) 09/06/2037(1) 09/06/2042(1)

Unit 3 (S.I.T. Date: 09/16/1986) 35th yr 40th yr 45th yr 50th yr No IWL-2520 IWL-2524/2525 All IWL-2520 IWL-2524/2525 Exams Exams Only Exams Exams Only 09/16/2020- 09/16/2025- 09/16/2030- 09/16/2035-09/16/2022 09/16/2027 09/16/2032 09/16/2037 IWL-2410 IWL-2410 IWL-2410 IWL-2410 Concrete Exams Concrete Exams Concrete Exams Concrete Exams 09/07/2020 - 09/07/2025 - 09/07/2030 - 09/07/2035 -

09/07/2022(1) 09/07/2027(1) 09/07/2032(1) 09/07/2037(1)

Notes:

(1) IWL-2410 examination schedule is based on the initial IWL-2410 examinations having been completed in September, 2001. An alternative to this schedule is not being requested.

(2) Date extended from 02/08/2021 to 02/08/2022, ADAMS Accession No.: ML21089A010.

(3) The Unit 2 post-tensioning examination schedule shall continue to be performed in accordance with the schedule established during the Second Inspection Interval that complies with IWL-2421.

Page 4

Enclosure Relief Request 67 Attachment 1 Table 5 Palo Verde Unit 1 Hoop Tendon Force Data (See Notes 2 and 3)

Structural Integrity Test (S.I.T.) Date: 12/25/1982 Shop End Field End Average Length of Time Since Initial Time Since Initial Surveillance Initial Surveillance Measured Measured Measured Time Since Tensioning Tensioning Tendon Year Tensioning Date Date Tendon Group(1) Force (kips) Force (kips) Force (kips) S.I.T. (Days) (Days) (Years)

H21-044 Year 01 (1984) 3/10/1981 2/28/1984 Dome Hoop 1517 1508 1513 430 1085 2.97 H13-007 Year 01 (1984) 1/25/1982 1/27/1984 Wall Hoop 1366 1393 1380 398 732 2.00 H21-037 Year 01 (1984) 12/15/1981 2/28/1984 Wall Hoop 1453 1471 1462 430 805 2.20 H13-021 Year 01 (1984) 12/11/1981 3/1/1984 Wall Hoop 1446 1496 1471 432 811 2.22 H32-016 Year 01 (1984) 4/13/1981 3/7/1984 Wall Hoop 1370 1387 1379 438 1059 2.90 H32-030 Year 01 (1984) 3/25/1981 3/7/1984 Wall Hoop - Common 1492 1502 1497 438 1078 2.95 H21-042 Year 03 (1985) 3/11/1981 1/3/1986 Dome Hoop 1468 1622 1545 1105 1759 4.82 H32-009 Year 03 (1985) 1/27/1982 12/18/1985 Wall Hoop 1483 1464 1474 1089 1421 3.89 H13-025 Year 03 (1985) 12/11/1981 1/2/1986 Wall Hoop 1410 1486 1448 1104 1483 4.06 H32-030 Year 03 (1985) 3/25/1981 1/2/1986 Wall Hoop - Common 1487 1516 1502 1104 1744 4.77 H32-033 Year 03 (1985) 12/18/1981 1/2/1986 Wall Hoop 1402 1505 1454 1104 1476 4.04 H21-011 Year 03 (1985) 1/21/1982 1/6/1986 Wall Hoop 1440 1451 1446 1108 1446 3.96 H32-044 Year 05 (1988) 2/27/1981 3/26/1988 Dome Hoop 1486 1557 1522 1918 2584 7.07 H32-023 Year 05 (1988) 12/21/1981 3/26/1988 Wall Hoop 1442 1458 1450 1918 2287 6.26 H32-030 Year 05 (1988) 3/25/1981 3/26/1988 Wall Hoop - Common 1479 1493 1486 1918 2558 7.00 H21-028 Year 05 (1988) 3/13/1981 4/18/1988 Wall Hoop 1462 1419 1441 1941 2593 7.10 H13-019 Year 05 (1988) 1/22/1982 4/26/1988 Wall Hoop 1364 1420 1392 1949 2286 6.26 H21-003 Year 05 (1988) 1/22/1982 4/26/1988 Wall Hoop 1507 1419 1463 1949 2286 6.26 H32-041 Year 10 (1992) 12/18/1981 8/14/1992 Dome Hoop 1413 1466 1440 3520 3892 10.66 H32-030 Year 10 (1992) 3/25/1981 8/14/1992 Wall Hoop - Common 1465 1483 1474 3520 4160 11.39 H13-008 Year 10 (1992) 6/10/1981 8/27/1992 Wall Hoop 1380 1389 1385 3533 4096 11.21 H32-015 Year 15 (1998) 1/27/1982 6/2/1998 Wall Hoop 1367 1442 1405 5638 5970 16.34 H32-030 Year 15 (1998) 3/25/1981 6/2/1998 Wall Hoop - Common 1463 1463 1463 5638 6278 17.19 H21-006 Year 15 (1998) 6/11/1981 6/11/1998 Wall Hoop 1303 1484 1394 5647 6209 17.00 H32-026 Year 25 (2008) 3/26/1981 9/13/2008 Wall Hoop 1333 1414 1374 9394 10033 27.47 H32-030 Year 25 (2008) 3/25/1981 9/13/2008 Wall Hoop - Common 1424 1413 1419 9394 10034 27.47 H13-014 Year 25 (2008) 6/10/1981 9/16/2008 Wall Hoop 1399 1426 1413 9397 9960 27.27 H13-043 Year 30 (2013) 12/8/1981 1/28/2013 Dome Hoop 1304 1405 1355 10992 11374 31.14 H32-030 Year 30 (2013) 3/25/1981 1/31/2013 Wall Hoop - Common 1426 1416 1421 10995 11635 31.85 H21-001 Year 30 (2013) 1/22/1982 2/13/2013 Wall Hoop 1396 1457 1427 11008 11345 31.06 Notes: 1. APS treats the dome hoop and wall hoop tendons as a single group and has selected a Common Tendon from this group of tendons.

2. Tendon sample sizes for surveillances in years 25 and 30 were determined in accordance with Table IWL-2521-1, based on a population of 150 hoop tendons. Tendon sample sizes for earlier surveillances were determined in accordance with plant Technical Specifications.

3. Relief from the performance of the Year 20 examination was granted by the NRC via Relief Request, ADAMS Accession No. ML003758134.

Page 5

Enclosure Relief Request 67 Attachment 1 Table 6 Palo Verde Unit 1 Vertical Tendon Force Data (See Notes 1 and 2)

Structural Integrity Test (S.I.T.) Date: 12/25/1982 Shop End Field End Average Length of Time Since Initial Time Since Initial Surveillance Initial Surveillance Measured Measured Measured Time Since Tensioning Tensioning Tendon Year Tensioning Date Date Tendon Group Force (kips) Force (kips) Force (kips) S.I.T. (Days) (Days) (Years)

V-32 Year 01(1984) 11/2/1981 1/9/1984 Vertical 1338 1462 1400 380 798 2.18 V-75 Year 01 (1984) 10/29/1981 1/10/1984 Vertical - Common 1438 1468 1453 381 803 2.20 V-62 Year 01 (1984) 10/26/1981 1/12/1984 Vertical 1453 1468 1461 383 808 2.21 V-43 Year 01 (1984) 8/20/1981 1/20/1984 Vertical 1391 1517 1454 391 883 2.42 V-75 Year 03 (1985) 10/29/1981 2/7/1986 Vertical - Common 1474 1471 1473 1140 1562 4.28 V-18 Year 03 (1985) 8/25/1981 2/9/1986 Vertical 1473 1355 1414 1142 1629 4.46 V-55 Year 03 (1985) 9/26/1980 2/10/1986 Vertical 1445 1462 1454 1143 1963 5.37 V-02 Year 03 (1985) 7/23/1981 2/15/1986 Vertical 1495 1440 1468 1148 1668 4.57 V-11 Year 05 (1988) 9/2/1981 2/26/1988 Vertical 1452 1477 1465 1889 2368 6.48 V-75 Year 05 (1988) 10/29/1981 2/26/1988 Vertical - Common 1468 1454 1461 1889 2311 6.33 V-36 Year 05 (1988) 11/2/1981 2/29/1988 Vertical 1363 1515 1439 1892 2310 6.32 V-86 Year 05 (1988) 6/23/1981 4/12/1988 Vertical 1492 1474 1483 1935 2485 6.80 V-75 Year 10 (1992) 10/29/1981 9/16/1992 Vertical - Common 1461 1442 1452 3553 3975 10.88 V-53 Year 10 (1992) 9/26/1981 9/17/1992 Vertical 1390 1416 1403 3554 4009 10.98 V-40 Year 10 (1992) 9/14/1981 9/18/1992 Vertical 1538 1533 1536 3555 4022 11.01 V-75 Year 15 (1998) 10/29/1981 7/16/1998 Vertical - Common 1409 1448 1429 5682 6104 16.71 V-72 Year 15 (1998) 10/27/1981 7/17/1998 Vertical 1390 1402 1396 5683 6107 16.72 V-37 Year 15 (1998) 11/4/1981 7/24/1998 Vertical 1376 1434 1405 5690 6106 16.72 V-15 Year 25 (2008) 9/3/1981 1/25/2008 Vertical 1403 1332 1368 9162 9640 26.39 V-08 Year 25 (2008) 8/24/1981 2/22/2008 Vertical 1405 1385 1395 9190 9678 26.50 V-75 Year 25 (2008) 10/29/1981 2/22/2008 Vertical - Common 1422 1421 1422 9190 9612 26.32 V-54 Year 30 (2013) 9/10/1981 2/14/2013 Vertical 1420 1304 1362 11009 11480 31.43 V-75 Year 30 (2013) 10/29/1981 2/19/2013 Vertical - Common 1388 1384 1386 11014 11436 31.31 V-29 Year 30 (2013) 11/3/1981 2/20/2013 Vertical 1373 1441 1407 11015 11432 31.30 Notes:

1. Tendon sample sizes for surveillances in years 25 and 30 were determined in accordance with Table IWL-2521-1, based on a population of 90 vertical tendons. Tendon sample sizes for earlier surveillances were determined in accordance with plant Technical Specifications.

2. Relief from the performance of the Year 20 examination was granted by the NRC via Relief Request, ADAMS Accession No. ML003758134.

Page 6

Enclosure Relief Request 67 Attachment 1 Table 7 Palo Verde Unit 2 Tendon Force Data (See Notes)

Structural Integrity Test (S.I.T.) Date: 02/08/1985 Shop End Field End Average Length of Time Time Since Initial Time Since Initial Surveillance Initial Surveillance Measured Measured Measured Since S.I.T. Tensioning Tensioning Tendon Year Tensioning Date Date Tendon Group Force (kips) Force (kips) Force (kips) (Days) (Days) (Years)

V-26 Year 20 (2005) 8/13/1982 9/8/2005 Vertical 1380 1298 1339 7517 8427 23.07 V-67 Year 20 (2005) 8/16/1982 8/30/2005 Vertical 1479 1338 1408 7508 8415 23.04 V-75 Year 20 (2005) 8/24/1982 9/1/2005 Vertical - Common 1400 1430 1415 7510 8409 23.02 H21-040 Year 20 (2005) 5/3/1982 7/7/2005 Wall Hoop 1402 1368 1385 7454 8466 23.18 H32-012 Year 20 (2005) 6/15/1982 7/1/2005 Wall Hoop 1351 1301 1326 7448 8417 23.04 H32-030 Year 20 (2005) 5/20/1982 7/1/2005 Wall Hoop - Common(4) 1297 1358 1328 7448 8443 23.12 V-08 Year 25 (2011) 8/19/1982 9/14/2010 Vertical 1517 1406 1461 9349 10253 28.07 V-15 Year 25 (2011) 8/8/1982 9/13/2010 Vertical 1483 1419 1451 9348 10263 28.10 V-75 Year 25 (2011) 8/24/1982 9/13/2010 Vertical - Common 1416 1426 1416 9348 10247 28.05 H13-014 Year 25 (2011) 6/15/1982 9/9/2010 Wall Hoop 1440 1403 1422 9344 10313 28.24 H32-026 Year 25 (2011) 5/21/1982 9/1/2010 Wall Hoop 1411 1345 1378 9336 10330 28.28 H32-030 Year 25 (2011) 5/20/1982 9/2/2010 Wall Hoop - Common(4) 1325 1342 1334 9337 10332 28.29 Notes:

1. Prior to the Year 20 Surveillance, Unit 2 post-tensioning system examinations were performed in accordance with plant licensing requirements, which did not require physical testing of Unit 2 tendons.

2. Unit 2 examinations performed during the Year 20 surveillance included tendon force measurements. Following this baseline inspection, the alternative requirements of IWL-2421 were implemented.

3. Tendon sample sizes for surveillances in years 20 and 25 were determined in accordance with Table IWL-2521-1, based on a population of 90 vertical tendons and 150 hoop tendons.

4. APS treats the dome hoop and wall hoop tendons as a single group and has selected a Common Tendon from this group of tendons.

Page 7

Enclosure Relief Request 67 Attachment 1 Table 8 Palo Verde Unit 3 Hoop Tendon Force Data (See Note 3)

Structural Integrity Test (S.I.T.) Date: 09/16/1986 Shop End Field End Average Length of Time Time Since Initial Time Since Initial Surveillance Initial Surveillance Measured Measured Measured Since S.I.T. Tensioning Tensioning Tendon Year Tensioning Date Date Tendon Group(1) Force (kips) Force (kips) Force (kips) (Days) (Days) (Years)

H13-044 Year 01 (1987) 10/18/1983 10/15/1987 Dome 1457 1490 1474 394 1458 3.99 H13-010 Year 01 (1987) 3/28/1984 10/13/1987 Wall Hoop 1415 1471 1443 392 1294 3.54 H13-036 Year 01 (1987) 10/21/1983 10/17/1987 Wall Hoop - Common 1392 1401 1397 396 1457 3.99 H21-007 Year 01 (1987) 4/9/1984 12/15/1987 Wall Hoop 1414 1442 1428 455 1345 3.68 H32-013 Year 01 (1987) 4/5/1984 10/20/1987 Wall Hoop 1466 1433 1450 399 1293 3.54 H32-021 Year 01 (1987) 4/3/1984 10/20/1987 Wall Hoop 1448 1453 1451 399 1295 3.55 H13-036 Year 03 (1989) 10/21/1983 1/6/1990 Wall Hoop - Common 1363 1375 1369 1208 2269 6.21 H21-004 Year 03 (1989) 3/30/1984 1/24/1990 Wall Hoop 1403 N/A(2) 1403 1226 2126 5.82 H21-005 Year 03 (1989) 4/10/1984 1/2/1990 Wall Hoop 1349 1392 1371 1204 2094 5.73 H21-006 Year 03 (1989) 3/29/1984 2/22/1990 Wall Hoop 1352 1434 1393 1254 2156 5.90 H21-009 Year 03 (1989) 4/9/1984 1/2/1990 Wall Hoop 1387 1431 1409 1204 2095 5.73 H32-018 Year 03 (1989) 3/11/1984 12/16/1989 Wall Hoop 1483 1453 1468 1187 2106 5.77 H32-029 Year 03 (1989) 11/1/1983 12/16/1989 Wall Hoop 1444 1410 1427 1187 2237 6.13 H32-042 Year 05 (1992) 10/20/1983 8/5/1991 Dome 1468 1500 1484 1784 2846 7.79 H13-009 Year 05 (1992) 4/9/1984 8/9/1991 Wall Hoop 1361 1469 1415 1788 2678 7.33 H13-036 Year 05 (1992) 10/21/1983 8/9/1991 Wall Hoop - Common 1368 1394 1381 1788 2849 7.80 H21-004 Year 05 (1992) 3/30/1984 8/9/1991 Wall Hoop 1394 1314 1354 1788 2688 7.36 H21-025 Year 05 (1992) 3/30/1984 8/14/1991 Wall Hoop 1370 1396 1383 1793 2693 7.37 H13-016 Year 05 (1992) 3/27/1984 8/19/1991 Wall Hoop 1354 1479 1417 1798 2701 7.39 H13-036 Year 10 (1997) 10/21/1983 12/11/1996 Wall Hoop - Common 1342 1371 1357 3739 4800 13.14 H13-024 Year 10 (1997) 3/26/1984 12/11/1996 Wall Hoop 1314 1458 1386 3739 4643 12.71 H21-010 Year 10 (1997) 3/28/1984 12/11/1996 Wall Hoop 1324 1313 1319 3739 4641 12.71 H21-043 Year 15 (2002) 10/27/1983 8/16/2002 Dome 1408 1456 1432 5813 6868 18.80 H21-022 Year 15 (2002) 3/26/1984 8/16/2002 Wall Hoop 1317 1345 1331 5813 6717 18.39 H13-036 Year 15 (2002) 10/21/1983 8/16/2002 Wall Hoop - Common 1330 1315 1323 5813 6874 18.82 H13-042 Year 25 (2012) 10/20/1983 5/21/2012 Dome 1404 1473 1439 9379 10441 28.59 H21-020 Year 25 (2012) 3/27/1984 5/15/2012 Wall Hoop 1334 1406 1370 9373 10276 28.13 H13-036 Year 25 (2012) 10/21/1983 5/24/2012 Wall Hoop - Common 1334 1363 1349 9382 10443 28.59 Notes:

1. APS treats the dome hoop and wall hoop tendons as a single group and has selected a Common Tendon from this group of tendons.

2. Data obtained only from tendon shop end.

3. Tendon sample sizes for surveillances in years 15 and 25 were determined in accordance with Table IWL-2521-1, based on a population of 150 hoop tendons. Tendon sample sizes for earlier surveillances were determined in accordance with plant Technical Specifications.

Page 8

Enclosure Relief Request 67 Attachment 1 Table 9 Palo Verde Unit 3 Vertical Tendon Force Data (See Note 2)

Structural Integrity Test (S.I.T.) Date: 09/16/1986 Shop End Field End Average Length of Time Since Initial Time Since Initial Surveillance Initial Surveillance Measured Measured Measured Time Since Tensioning Tensioning Tendon Year Tensioning Date Date Tendon Group Force (kips) Force (kips) Force (kips) S.I.T. (Days) (Days) (Years)

V-28 Year 01 (1987) 2/9/1984 12/10/1987 Vertical 1428 1485 1457 450 1400 3.83 V-49 Year 01 (1987) 1/20/1984 10/24/1987 Vertical 1353 1527 1440 403 1373 3.76 V-07 Year 01 (1987) 12/19/1983 11/3/1987 Vertical 1520 N/A(1) 1520 413 1415 3.87 V-09 Year 01 (1987) 1/23/1984 10/24/1987 Vertical 1442 1533 1488 403 1370 3.75 V-15 Year 01 (1987) 1/17/1984 11/3/1987 Vertical 1491 N/A(1) 1491 413 1386 3.79 V-16 Year 01 (1987) 2/3/1984 10/26/1987 Vertical - Common 1404 1558 1481 405 1361 3.73 V-20 Year 01 (1987) 2/3/1984 12/12/1987 Vertical 1574 1486 1530 452 1408 3.85 V-16 Year 03 (1989) 2/3/1984 10/31/1989 Vertical - Common 1379 1550 1465 1141 2097 5.74 V-39 Year 03 (1989) 12/20/1983 11/1/1989 Vertical 1398 1471 1435 1142 2143 5.87 V-59 Year 03 (1989) 1/16/1984 10/31/1989 Vertical 1387 1485 1436 1141 2115 5.79 V-66 Year 03 (1989) 2/7/1984 11/1/1989 Vertical 1435 1481 1458 1141 2094 5.73 V-71 Year 05 (1992) 2/9/1984 9/12/1991 Vertical 1468 1558 1513 1822 2772 7.59 V-16 Year 05 (1992) 2/3/1984 9/13/1991 Vertical - Common 1410 1543 1477 1823 2779 7.61 V-33 Year 05 (1992) 2/16/1984 9/18/1991 Vertical 1456 1598 1527 1828 2771 7.59 V-48 Year 05 (1992) 12/22/1983 9/18/1991 Vertical 1305 1445 1375 1828 2827 7.74 V-16 Year 10 (1997) 2/3/1984 7/31/1996 Vertical - Common 1366 1524 1445 3606 4562 12.49 V-82 Year 10 (1997) 12/22/1983 8/2/1996 Vertical 1394 1478 1436 3608 4607 12.61 V-13 Year 10 (1997) 2/6/1984 8/14/1996 Vertical 1405 1507 1456 3620 4573 12.52 V-57 Year 15 (2002) 2/7/1984 7/10/2002 Vertical 1378 1520 1449 5776 6728 18.42 V-16 Year 15 (2002) 2/3/1984 7/11/2002 Vertical - Common 1367 1517 1442 5777 6733 18.43 V-41 Year 15 (2002) 1/24/1984 7/16/2002 Vertical 1419 1542 1481 5782 6748 18.48 V-02 Year 25 (2012) 12/21/1983 6/4/2012 Vertical 1445 1428 1437 9393 10393 28.45 V-87 Year 25 (2012) 1/25/1984 6/5/2012 Vertical 1363 1387 1375 9394 10359 28.36 V-16 Year 25 (2012) 2/3/1984 6/12/2012 Vertical - Common 1338 1495 1417 9401 10357 28.36 Notes:

1. Data obtained only from tendon shop end.

2. Tendon sample sizes for surveillances in years 15 and 25 were determined in accordance with Table IWL-2521-1, based on a population of 90 vertical tendons. Tendon sample sizes for earlier surveillances were determined in accordance with plant Technical Specifications.

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Enclosure Relief Request 67 Attachment 2 (Figures)

Enclosure Relief Request 67 Attachment 2 Figure 1 Palo Verde Unit 1 Wall Hoop Tendons 1550 1500 1497 1502 1474 1486 1471 1454 1474 1462 1463 1463 1427 1448 1450 Measured Tendon Force (kips) 1450 1444 1421 1419 1446 1400 1405 Tendon Mean Prestress 1392 1413 Force Trendline 1385 1394 1380 1379 1374 1350 1300 MRV = 1248 kips 1250 1200 1 10 100 Years From Initial Tensioning Page 1

Enclosure Relief Request 67 Attachment 2 Figure 2 Palo Verde Unit 1 Wall Hoop Common Tendon H32-30 1550 1500 1497 1502 1486 1474 1463 Measured Tendon Force (kips) 1450 1419 1421 1400 Tendon Prestress Force Trendline 1350 1300 MRV = 1248 kips 1250 1200 1 10 100 Years From Initial Tensioning Page 2

Enclosure Relief Request 67 Attachment 2 Figure 3 Palo Verde Unit 1 Dome Hoop Tendons 1650 1550 1545 1522 Measured Tendon Force (kips) 1513 1450 1440 1350 1355 Tendon Mean Prestress 1250 Force Trendline MRV = 1167 kips 1150 1 10 100 Years From Initial Tensioning Page 3

Enclosure Relief Request 67 Attachment 2 Figure 4 Palo Verde Unit 1 Vertical Tendons 1600 1461 1536 1473 1483 1500 1468 Measured Tendon Force (kips) 1453 1461 1465 1452 1454 1454 1429 1414 1422 1407 1400 1400 1439 1403 1405 Tendon Mean Prrestress 1386 Force Trendline 1396 1395 1362 1368 1300 1200 1100 MRV = 1016 kips 1000 1 10 100 Years From Initial Tensioning Page 4

Enclosure Relief Request 67 Attachment 2 Figure 5 Palo Verde Unit 1 Vertical Common Tendon V-75 1600 1500 1473 Measured Tendon Force (kips) 1453 1461 1452 1429 1422 1400 Tendon Prestress 1386 Force Trendline 1300 1200 1100 MRV = 1016 kips 1000 1 10 100 Years From Initial Tensioning Page 5

Enclosure Relief Request 67 Attachment 2 Figure 6 Palo Verde Unit 3 Wall Hoop Tendons 1500 1468 1451 1450 1450 1443 1427 1409 1417 1415 Measured Tendon Force (kips) 1418 1400 1403 1397 1381 1393 1386 1371 1383 1370 1350 1369 1354 1357 1349 1331 1323 1319 1300 Tendon Mean Prestress Force Trendline MRV = 1248 kips 1250 1200 1 10 100 Years From Initial Tensioning Page 6

Enclosure Relief Request 67 Attachment 2 Figure 7 Palo Verde Unit 3 Wall Hoop Common Tendon H13-036 1450 1400 1397 Measured Tendon Force (kips) 1381 1369 1357 1350 1349 1323 1300 Tendon Prestress Force Trendline MRV = 1248 kips 1250 1200 1 10 100 Years From Initial Tensioning Page 7

Enclosure Relief Request 67 Attachment 2 Figure 8 Palo Verde Unit 3 Dome Hoop Tendons 1550 1500 1501 1484 1474 1450 Measured Tendon Force (kips) 1439 1432 1400 Tendon Mean Prestress Force Trendline 1350 1300 1250 1200 MRV = 1167 kips 1150 1 10 100 Years From Initial Tensioning Page 8

Enclosure Relief Request 67 Attachment 2 Figure 9 Palo Verde Unit 3 Vertical Tendons 1600 1530 1527 1520 1491 1465 1513 1488 1456 1481 1500 1477 1449 1445 1481 1442 1458 Measured Tendon Force (kips) 1437 1453 1435 1400 1440 1436 1417 Tendon Mean Prestress 1436 1375 Force Trendline 1375 1300 1200 1100 MRV = 1016 kips 1000 1 10 100 Years From Initial Tensioning Page 9

Enclosure Relief Request 67 Attachment 2 Figure 10 Palo Verde Unit 3 Vertical Common Tendon V-16 1600 1500 1481 1477 1445 1442 Measured Tendon Force (kips) 1465 1400 1417 Tendon Prestress Force Trendline 1300 1200 1100 MRV = 1016 kips 1000 1 10 100 Years From Initial Tensioning Page 10

Enclosure Relief Request 67 Attachment 2 Figure 11 Palo Verde Units 1 and 3 Dome Hoop Tendons (Combined) 1600 1550 1545 1522 1513 1500 1501 1484 Measured Tendon Force (kips) 1474 1450 1440 1439 1432 1400 1350 1355 Tendon Mean Prestress Force Trendline 1300 1250 1200 Unit 1 Dome Hoop Tendons MRV = 1167 kips Unit 3 Dome Hoop Tendons 1150 1 10 100 Years From Initial Tensioning Page 11

Enclosure Relief Request 67 Attachment 2 Figure 12 Palo Verde Units 1, 2, and 3 Wall Hoop Tendons (Combined) 1600 1550 1497 1502 1471 1474 1486 1500 Measured Tendon Force (kips) 1474 1451 1454 1468 1463 1462 1422 1427 1463 1450 1450 1450 1448 1444 1421 1446 1427 1417 1405 1443 1419 1418 1415 1400 1403 1413 1397 1409 1394 1385 1392 1378 1380 1393 1386 1381 1385 1374 1379 1371 1383 1350 1331 1370 1369 1357 1349 Tendon Mean Prestress 1354 Force Trendline 1328 1334 1300 1319 1323 1326 MRV = 1248 kips Unit 1 Wall Hoop Tendons 1250 Unit 2 Wall Hoop Tendons Unit 3 Wall Hoop Tendons 1200 1 10 100 Years From Initial Tensioning Page 12

Enclosure Relief Request 67 Attachment 2 Figure 13 Palo Verde Units 1, 2, and 3 Vertical Tendons (Combined) 1600 1530 1483 1527 1520 1473 1513 1536 1491 1481 1461 1488 1465 1452 1481 1465 1449 1451 1500 1468 1456 1477 1442 1437 1461 1445 1422 1461 1436 1421 1454 1453 1429 1458 Measured Tendon Force (kips) 1453 1417 1400 1440 1439 1403 1407 Tendon Mean Prestress 1400 1405 1415 1386 Force Trendline 1414 1435 1395 1408 1375 1396 1454 1436 1362 1300 1368 1339 1375 1200 1100 Unit 1 Vertical Tendons Unit 2 Vertical Tendons MRV = 1016 kips Unit 3 Vertical Tendons 1000 1 10 100 Years From Initial Tensioning Page 13