ML17299B333

Relief Request 57 - Request for Alternative to American Society of Mechanical Engineers Code Case N-729-4 for Replacement Reactor Vessel Closure Head Penetration Nozzles

ML17299B333
Person / Time
Site:	Palo Verde
Issue date:	10/26/2017
From:	Lacal M Arizona Public Service Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
102-07611-MLL/TNW, RR-057
Download: ML17299B333 (16)

Text

10 CFR 50.55a Oaps 102-0761 I-MLL/TNW October 26, 2017 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 MARIA L. LACAL Senior Vice President, Nuclear Reguiatory & Oversight Palo Verde Nuclear Generating Station P.O. Box 52034 Phoenix, AZ 85072 Mali Station 7605 Tel 623.393.6491

Subject:

Palo Verde Nuclear Generating Station Unit 1 Docket No. STN 50-528 Relief Request 57 - Request for Alternative to American Society of Mechanical Engineers Code Case N-729-4 for Replacement Reactor Vessel Closure Head Penetration Nozzles Pursuant to 10 CFR 50.55a(z)(2), Arizona Public Service Company (APS) requests Nuclear Regulatory Commission (NRC) approval of the enclosed request for an alternative for the Palo Verde Nuclear Generating Station (PVNGS) Unit 1, based upon the specified Code Case requirements representing a hardship or unusual difficulty without a compensating increase in the level of quality and safety. The enclosure identifies the affected components, applicable American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code (Code) Case requirements, reason for request, proposed alternative and basis for use.

The alternative is proposed to be applied during the next operating cycle and will conclude in the Spring of 2019 refueling outage.

APS scheduled visual examinations (VE) of the replacement reactor vessel closure head (RRVCH) nozzle penetrations during the current Unit 1 refueling outage (1R20) because a spill emanating from the RRVCH vent valves had occurred on the RRVCH during the previous refueling outage (1R19) just prior to startup. In 1R20, the RRVCH nozzle penetrations were examined and 14 penetrations were determined to have relevant conditions pursuant to Code Case N-729-4, paragraph 3141(c).

The relevant conditions were not initially considered to be indicative of possible nozzle leakage based upon the combined factors of the analysis of the VE results, streak markings on the RRVCH and nozzles that were in the spill zone, nondestructive VE training for ASME Code Case N-729-4, primary water stress corrosion cracking resistant material used in the RRVCH, crack growth and crack initiation studies of Alloy 690 material, and radioisotope analysis of the residue. However, it could not absolutely be refuted that the relevant conditions are indicative of possible nozzle leakage. Code Case N-729-4, paragraph 3142.2, requires nozzles with relevant conditions indicative of possible nozzle leakage to have a supplemental examination consisting of a volumetric examination of the nozzle tube and a corresponding weld surface examination in accordance with paragraph 3200(b).

As described in the enclosure, APS is requesting an alternative to the specified requirements of Code Case N-729-4, paragraph 3142.2, pursuant to 10 CFR 50.55a(z)(2), as the provisions that require a supplemental examination represent a hardship or unusual difficulty without a compensating increase in the level of quality and safety.

A member of the STARS Alliance LLC Callaway

• Diablo Canyon

• Palo Verde

• Wolf Creek

102-07611-MLLyTNW ATTN: Document Control Desk U. S. Nuclear Regulatory Commission Reiief Request 57 - Request for an Aiternative to ASME Code Case N-729-4 for Replacement Reactor Vessel Closure Head Penetration Nozzles Page 2 APS requests approval of this relief request by November 2, 2017, to support restart (Mode

2) from the current Unit 1 refueiing outage.

No new commitments are being made in this submittai.

If you have any questions about this request, piease contact Matthew Cox, Licensing Section Leader, at (623) 393-5753.

Sincerely, Lacal, Maria Si'.?"""'"'""'

ON: cn=Lacal, Maria UZ06149)

L(Z06149)

MLI7MDD/MSC

Enclosure:

Relief Request 57 - Request for an Alternative to ASME Code Case N-729-4 for Replacement Reactor Vessel Closure Head Penetration Nozzies cc:

K. M. Kennedy S. P. Lingam M. M. Watford O'Banion C. A. Peabody NRC Region IV Regional Administrator NRC NRR Project Manager for PVNGS NRC NRR Project Manager NRC Senior Resident Inspector for PVNGS

Enclosure Relief Request 57 Request for an Alternative to ASME Code Case N-729-4 for Replacement Reactor Vessel Closure Head Penetration Nozzles

Enclosure Relief Request 57 Arizona Public Service Company Palo Verde Nuclear Generating Station - Unit 1 Proposed Alternative in Accordance with 10 CFR 50.55a(z)(2)

Request for an Alternative to ASME Code Case N-729-4 for Replacement Reactor Vessel Closure Head Penetration Nozzles

1. ASME CODE COMPONENTS AFFECTED Component:

Replacement Reactor Vessel Closure Head (RRVCH) Nozzles Code Class:

Class 1 Examination Category:

Code Item Number:

==

Description:==

American Society of Mechanical Engineers (ASME) Code Case N-729-4, Alternative Examination Requirements for PWR Reactor Vessel Upper Heads with Nozzles Having Pressure-Retaining Partial-Penetration Welds,Section XI, Division 1 B4.40 Control Element Drive Mechanism (CEDM) Nozzles - Specifically, nozzles 22, 41, 46, 54, 55, 64, 73, 74, 81, 82, 86, 89, 90 and 97 Size:

4.275 Inch (Nominal Outside Diameter)

Material:

RRVCH - SA-508 Grade 3 Class 1 Nozzles - SB-166 N06690 (Alloy 690)

Buttering and Weld Material - ERNiCrFe-7 / ERNiCrFe-7A /

ENiCrFe-7 (Alloy 52/152)

There are 97 CEDM nozzles and 1 vent nozzle welded to the inside surface of the RRVCH with partial penetration J-groove welds.

2. APPLICABLE CODE EDITION AND ADDENDA The third 10-year ISI interval Code for Palo Verde Nuclear Generating Station (PVNGS) is the 2001 Edition through and including the 2003 Addenda of ASME Code,Section XI, Rules for Inservice Inspection of Nuclear Power Plant Components. Examinations of the RRVCH penetrations are performed in accordance with ASME Code Case N-729-4 (Reference 1), as conditioned by Title 10 of the Code of Federal Regulations (10 CFR) 50.55a(g)(6)(ii)(D).

Manufacturing Code for PVNGS Unit 1 RRVCH: 1998 Edition through and including the 2000 Addenda of ASME Boiler and Pressure Vessel (BPV) Code,Section III, Rules for Construction of Nuclear Power Plant Components

3. APPLICABLE CODE REQUIREMENT 10 CFR 50.55a(g)(6)(ii)(D)(l) requires:

(D) Augmented ISI requirements: Reactor vessel head inspections(1) Implementation.

Holders of operating licenses or combined licenses for pressurized-water reactors as of or 1

Enclosure Relief Request 57 after August 17, 2017 shall Implement the requirements of ASME BPV Code Case /V-729-4 Instead ofASME BPV Code Case N-729-1, subject to the conditions specified in paragraphs (g)(6)(ii)(D)(2) through (4) of this section, by the first refueling outage starting after August 17, 2017.

Paragraph 3141 of Code Case N-729-4 states, regarding inservice visual examinations (VE):

(a) The VE required by -2500 and performed in accordance with IWA-2200 and the additional requirements of this Case shall be evaluated by comparing the examination results with the acceptance standards specified in -3142.1.

(b) Acceptance of components for continued service shall be in accordance with -3142.

(c) Relevant conditions for the purposes of the VE shall include evidence of reactor coolant leakage, such as corrosion, boric acid deposits, and discoloration.

Paragraph 3142.1 Acceptance by VE of Code Case N-729-4 states:

(a) A component whose VE confirms the absence of relevant conditions shali be acceptable for continued service.

(b) A component whose VE detects a relevant condition shall be unacceptable for continued service until the requirements of (1),(2), and (c) below are met.

(1) Components with relevant conditions require further evaluation. This evaluation shall include determination of the source of the leakage and correction of the source of leakage in accordance with -3142.3.

(2) All relevant conditions shall be evaluated to determine the extent, if any, of degradation. The boric acid crystals and residue shall be removed to the extent necessary to allow adequate examinations and evaluation of degradation, and a subsequent VE of the previously obscured surfaces shall be performed, prior to return to service, and again in the subsequent refueling outage. Any degradation detected shall be evaluated to determine if any corrosion has impacted the structural integrity of the component. Corrosion that has reduced component wall thickness below design limits shall be resolved through repair/replacement activity in accordance with IWA-4000.

(c) A nozzle whose VE indicates relevant conditions indicative of possible nozzle leakage shall be unacceptable for continued service unless it meets the requirements of -3142.2 or

-3142.3.

Paragraph 3142.2 Acceptance of Supplemental Examination of Code Case N-729-4 states:

A nozzle with relevant conditions indicative of possible nozzle leakage shall be acceptable for continued service if the results of supplemental examinations [-3200(b)] meet the requirements of -3130. (Emphasis added)

Enclosure Relief Request 57 Paragraph 3142.3 Acceptance by Corrective Measures or Repair/Replacement Activity of Code Case N-729-4 states:

(a) A component with relevant conditions not indicative of possible nozzle leakage is acceptable for continued service if the source of the relevant condition is corrected by a repair/replacement activity or by corrective measures necessary to preclude degradation.

(b) A component with relevant conditions indicative of possible nozzle leakage shall be acceptable for continued service if a repair/replacement activity corrects the defect in accordance with IWA-4000.

Paragraph 3200(b) Supplemental Examinations of Code Case N-729-4 states:

(b) The supplemental examination performed to satisfy -3142.2 shall include volumetric examination of the nozzle tube and surface examination of the partial-penetration weld, or surface examination of the nozzle tube inside surface, the partial penetration weld, and nozzle tube outside surface below the weld. In accordance with Fig. 2, or the alternative examination area or volume shall be analyzed to be acceptable in accordance with Mandatory Appendix I. The supplemental examinations shall be used to determine the extent of the unacceptable conditions and the need for corrective measures, analytical evaluation, or repair

/replacement activity.

4. REASON FOR REQUEST APS scheduled visual examinations (VE) of the RRVCH nozzle penetrations during the current Unit 1 refueling outage (1R20) because a spill emanating from the RRVCH vent valves had occurred on the RRVCH during the previous refueling outage (1R19) just prior to startup. The spill occurred due to a RRVCH vent valve misalignment and was terminated when the vent valves were closed.

During 1R20, the RRVCH head nozzle penetrations were examined in the as-found condition using ASME Code Case N-729-4 and 14 penetrations were determined to have relevant conditions pursuant to Code Case N-729-4, paragraph 3141(c). See Attachment 1 of this enclosure for nozzle and vent valve locations.

The APS qualified examiner concluded that the relevant conditions were the result of the previous spill as the condition did not have active leakage characteristics (a part of the VE-729 qualification process). Therefore, APS pursued cleaning these nozzles with a carbon dioxide (CO2) spray in preparation for the final VE prior to return to service and again in the subsequent refueling outage as required by paragraph 3142.1(b)(2). The final VE results were acceptable as no relevant conditions remained.

During interaction with the NRC ISI inspector, APS was questioned as to how they were able to discern whether the residue in the annulus of the relevant 14 nozzles could not possibly have originated from a leak in the nozzle as opposed to resulting from the overhead spill from the RRVCH vent valves that had occurred in the previous outage. Although the pattern of residue on the nozzles was not consistent with the traditional patterns seen in CEDM nozzle leaks and there were visible streak marks on the RRVCH and nozzles indicative of an overhead spill, it could not absolutely be refuted that the relevant conditions are indicative of possible nozzle leakage.

Once it is determined that the possibility of nozzle leakage exists. Code Case N-729-4, paragraph 3142.2, requires nozzles with relevant conditions indicative of possible nozzle leakage undergo supplemental examinations consisting of a volumetric examination of the nozzle tube and a corresponding surface examination in accordance with paragraph 3200(b). In order to perform the examinations in accordance with Code Case N-729-4, paragraph 3200(b), it will be necessary

Enclosure Relief Request 57 to mobilize qualified personnel to the site on an emergent basis. It is estimated that mobilization of personnel and completion of the required supplemental examinations will take approximately five weeks depending upon availability of resources.

In addition, the supplemental examination requires access to the underside of the highly contaminated RRVCH which would expose personnel to elevated dose rates. The additional dose is estimated to be approximately 0.75 to 1.0 person-rem for this work.

Adding this extra time duration to the outage and increasing the personnel dose for performing these supplemental examinations represents a hardship or unusual difficulty without a compensating increase in the level of quality and safety, pursuant to 10 CFR 50.55a(z)(2).

The specific CEDM nozzles that are within the scope of this relief request are:

Nozzles 22, 41, 46, 54, 55, 64, 73, 74, 81, 82, 86, 89, 90 and 97 Each of these nozzles was deemed a relevant condition pursuant to Code Case N-729-4, paragraph 3141(c). The initial disposition of these nozzles was that the conditions were deemed relevant, but not indicative of nozzle leakage. This conclusion was reached due to the streaking from above, the pooling in the annulus region, as well as the location of the vent valve (RCNV007 and RCNV212, see Attachment 1) spill which occurred at the end of 1R19. Each nozzle was cleaned with CO2 to perform an adequate examination of the base metal and to ensure there were no indications of degradation or corrosion. of this enclosure, entitled. Nozzles Identified with Debris Removed After Cleaning Efforts, itemizes nozzles that were determined to have no relevant conditions and are not within the scope of this relief request. This additional information is provided based upon a conference call with NRC staff on October 24, 2017.

An effort was made to determine the source of the identified debris. A review of the baseline images that were taken of the RRVCH, prior to being installed in the unit, indicates that the debris noted in the current as-found images during 1R20 is similar to that noted in the May 2010 baseline which would indicate the source of the debris is from the RRVCH prior to installation in the unit. The configuration of the head ventilation system is another potential source of debris as air is drawn in from the surrounding containment atmosphere, across the RRVCH and expelled above. This circulation of air has a potential to draw in dust/debris and deposit it on the RRVCH. of this enclosure, entitled. Nozzles Identified with Debris Remaining After Cleaning Efforts, itemizes nozzles that were determined to not have relevant conditions but were not able to be fully cleaned so that all debris was removed. This additional information is provided based upon a conference call with NRC staff on October 24, 2017.

Nozzles 27, 39, 62 and 84 show white debris in their noted quadrants but is not relevant and cannot be removed by using the industry accepted CO2 cleaning methodology (dry ice). The foreign material (nozzle 16) and remaining debris do not obscure the examination area and adequate VE can still be performed in the future. This information is provided independent of the scope of the relief request.

Enclosure Relief Request 57

5. PROPOSED ALTERNATIVE AND BASIS FOR USE APS proposes an alternative of performing a bare metal VE of the 14 applicable RRVCH nozzles within the scope of this relief request at the next refueling outage in accordance with Code Case N-729-4.

Previous Examinations The replacement partial-penetration welded nozzles of the Unit 1 RRVCH were examined prior to service. During fabrication, there were no indications detected by dye penetrant examination (PT),

i.e. PT white. Ultrasonic examination (UT) and eddy current examination (ET) of 100% of the nozzles was performed following hydrostatic testing with no unacceptable indications.

The Unit 1 RRVCH was installed in refueling outage 1R15, in May 2010.

A VE was performed on the PVNGS RRVCH for Unit 1 in 2014 in accordance with ASME Code Case N-729-1, Table 1, item B4.40. This VE was performed by qualified examiners on the outer surface of the RRVCH inciuding the annulus area of the penetration nozzles. This examination did not reveal any relevant conditions that would be indicative of nozzle leakage.

MRP-375 Information Regarding the Structurai Adequacy of the RRVCH Ailoy 690 Nozzles Evaluations were performed and documented in MRP-375 (Reference 2) to demonstrate the acceptability of extending the inspection intervals for ASME Code Case N-729-1, item B4.40 components. Based on plant service experience, factor of improvement (FOI) studies using laboratory data, deterministic study results, and probabilistic study results, MRP-375 documented extended inspection intervals. This information documents the structural suitability of the RRVCH for extended periods of time.

Per MRP-375, much of the laboratory data indicated an FOI of 100 for Alloy 690/52/152 versus Alloy 600/182/82 (for equivalent temperature and stress conditions) in terms of crack growth rates (CGR). In addition, laboratory and plant data demonstrate an FOI in excess of 20 in terms of the time to primary water stress corrosion cracking (PWSCC) initiation. This reduced susceptibility to PWSCC initiation and growth supports elimination of all volumetric examinations throughout the plant service period, and by extension, supports not performing volumetric examinations this refueling outage.

Deterministic calculations demonstrate that the alternative volumetric re-examination schedule of MRP-375 (15 years) is sufficient to detect any PWSCC before it could develop into a safety significant circumferential flaw that approaches the large size (i.e., more than 300 degrees of circumferential extent) necessary to produce a nozzle ejection. The deterministic calculations also demonstrate that any base metal PWSCC would likely be detected prior to a through-wall flaw occurring. Probabilistic calculations based on a Monte Carlo simulation model of the PWSCC process, including PWSCC initiation, crack growth, and flaw detection via ultrasonic testing, show a substantially reduced effect on nuclear safety compared to a RRVCH with Alloy 600 nozzles examined per current requirements.

As documented in MRP-375, the resistance of Alloy 690 and corresponding weld metals Alloy 52 and 152 is demonstrated by the lack of PWSCC indications reported in these materials, in up to 24 consecutive years of service for thousands of Alloy 690 steam generator tubes, and more than 22 consecutive years of service for thick-wall and thin-wall Alloy 690 applications. This operating experience includes service at pressurizer and hot-leg temperatures higher than those on the

Enclosure Relief Request 57 RRVCH and includes Alloy 690 wrought base metal and Alloy 52/152 weld metal. This experience includes ISI volumetric or surface examinations performed in accordance with ASME Code Case N-729-1 on 13 of the 41 replacement reactor vessel heads currently operating in the United States nuclear power plant fleet. This data supports a factor of improvement in time to detectable PWSCC flaw initiation of at least five to 20 when compared to service experience of Alloy 600 in similar applications worldwide.

The PVNGS Unit 1 RRVCH was fabricated by Doosan Heavy Industries using Alloy 690 nozzle material produced by Doosan Heavy Industries per ASME SB-166. The nozzle J-groove welds were produced using Alloy 52 (ASME SFA-5.14 ERNiCrFe-7), Alloy 52 (ERNiCrFe-7A to ASME Code Case 2142-2 requirements), and Alloy 152 (ASME SFA-5.11 ENiCrFe-7) weld material. There are no similarities that indicate any specific concern for elevated PWSCC susceptibility of the RRVCH nozzles at PVNGS in comparison to other RRVCHs with Alloy 690 nozzles.

Recent RCS Operational Leakage Performance From the operational data for Unit 1 cycle 20, the following information provides support for the conclusion that there is no evidence of an active nozzle leak; The surveillance test data from procedure 40ST-9RC02, ERFDADS (Preferred) Calculation of RCS Water Inventory, shows Reactor Coolant System (RCS) unidentified leakage rates were nominal.

The containment atmosphere radiation monitor particulate channel RU-1 was nominal and constant.

Containment tritium levels were nominal and constant.

There was an increase in the containment east sump in-leakage levels which were attributed to secondary system leaks from the steam generator wet-layup pump seals.

Chemistry samples taken of the residue in several locations on the RRVCH during 1R20 show that there is no evidence of short-lived radionuclides that must be present if there were a recent RCS leak.

The ISI and boric acid program examinations, evaluations, and reports do not show evidence of a recent RCS leak.

The PVNGS Technical Specifications (TS) require monitoring of operational leakage. TS 3.4.14, RCS Operational Leakage, contains the following limits for RCS leakage:

a)

No pressure boundary leakage b) 1 gallon per minute (gpm) unidentified leakage c) 10 gpm identified leakage; and d) 150 gallons per day primary to secondary leakage through any one steam generator This specification is applicable in operating Modes 1, 2, 3, and 4.

APS implements these requirements with station operating procedures; specifically, procedure 40ST-9RC02, ERFDADS (Preferred) Calculation of RCS Water Inventory, which is used to determine the leakage rates on a routine basis.

Enclosure Relief Request 57 RCS leak rate results are used to Implement specific operationai actions based on action level criteria or leakage trend data. Procedure 400P-9RC03, RCS Leakage Source Determination, specifies the RCS unidentified ieakage action leveis and their required actions as foiiows:

Action Levei 1 is reached when the roliing average of the last seven performances of the unidentified RCS leak rate exceeds 0.1 gpm, or the last nine consecutive unidentified RCS leak rates are greater than the baseline mean. Required actions are to document the event in a condition report, establish increased monitoring frequency of leakage indicators by daiiy performance of RCS water inventory performance, or as designated by the Shift Manager/Control Room Supervisor, and request assistance from the reactor coolant system engineer.

Action Level 2 is reached when the last two consecutive unidentified RCS leakage rates are greater than 0.15 gpm, or two of three consecutive unidentified RCS ieak rates are greater than the mean unidentified RCS ieakage pius two standard deviations. Required actions are to ensure action ievei one response is completed, review recent plant evaluations to determine any suspect sources, evaiuate changes in ieakage detection indications, check any components or flowpaths whose condition has recentiy changed and check for recent maintenance activities.

Action Level 3 is reached when the unidentified RCS leak rate is greater than 0.3 gpm, or greater than the mean pius three standard deviations. Required actions are to ensure action levei one and two responses are completed, initiate pianning for a containment entry per piant procedure 40DP-9ZZ01, Containment Entry in MODE 1 thru MODE 4, obtain a containment sump sampie, chemistry to anaiyze the containment sump sample, evaluate other systems for indications of leakage, obtain a containment atmosphere sample for indications of RCS leakage, monitor containment sump east and west level, monitor reactor cavity sump ievei, monitor area radiation monitors, other containment parameters, identify the source of the ieakage, determine the ieakage rate, and initiate a plan to correct the leak.

Based upon the VE performed on the RRVCH and the operating time of the RRVCH, it has been determined that there is no leakage from any of the nozzles or partial penetration weids. The nozzle penetrations with relevant conditions were known to have been subjected to a prior spiii emanating from the RRVCH vent valves, that radiochemistry resuits indicated no short haif-life radioisotopes present (which indicates no active nozzle leak), and there was no evidence of carbon steel oxidation in the annulus of the nozzle penetrations with reievant conditions.

Therefore, performing the stipuiated emergent suppiementai examinations of the nozzles would represent a hardship or unusuai difficulty without a compensating increase in the level of quality and safety. APS proposes an alternative of performing a bare metal VE of the 14 applicable RRVCH nozzles within the scope of this relief request at the next refueling outage in accordance with Code Case N-729-4.

6. DURATION OF PROPOSED ALTERNATIVE The proposed alternative will be utilized until the end of operating cycle 21.

7. PRECEDENT NRC letter regarding approval of Relief Request (RR) 14 for Fort Calhoun Station, Unit No. 1,

Subject:

Fort Calhoun Station, Unit No. 1 - Request for Relief RR-14, From Certain Requirements ofASME Code Case N-729-1 for Reactor Vessel Head Penetration Nozzle Welds, dated August 21, 2015 (ADAMS Accession number ML15232A003)

Enclosure Relief Request 57

8. REFERENCES

1. ASME Boiler and Pressure Vessel Code Case N-729-4, Alternative Examination Requirements for PWR Reactor Vessel Upper Heads With Nozzles Having Pressure-Retaining Partial-Penetration WeldsSection XI, Division 1

2. Materials Reliability Program: Technical Basis for Reexamination Interval Extension for Alloy 690 PWR Reactor Vessel Top Head Penetration Nozzles (MRP-375), EPRI, Palo Alto, CA: 2014

Enclosure Relief Request 57 Area of Identified RRVCH Vent Valve Spill HEW urr LiKs

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Enclosure Relief Request 57 Nozzles Identified with Debris Removed After Cleaning Efforts Item Nozzle Comment Disposition Debris Disposition Method 1

12 Slight debris on bare metal of the head in 0-90 image Debris was removed during 60 psig air blowing on 10/21/17.

Air 2

13 Debris noted in 0-90 and 270-360 images Debris was removed during 60 psig air blowing on 10/21/17.

Air 3

17 Debris noted in 270-360 image After 60 psig air blow, the debris was deemed non-relevant through visual examination because it does not have an apparent path below. A successful attempt was made to remove the debris utilizing CO2 on 10/23/17.

Air, visual examination, CO2 4

25 0-90 image shows indications of residual debris after 60 psig air on 10/21/17 After 60 psig air blow, the debris was deemed non-relevant through visual examination because it does not have an apparent path below. A successful attempt was made to remove the debris utilizing CO2 on 10/23/17.

Air, visual examination, CO2 5

29 Slight debris noted in the images After 60 psig air blow, the debris was deemed non-relevant through visual examination because it does not have an apparent path below. A successful attempt was made to remove the debris utilizing CO2 on 10/23/17.

Air, visual examination, CO2 6

35 Debris noted in the 270-360 images on 10/13/17 Debris was removed during 60 psig air blowing on 10/21/17.

Air 7

36 Debris was noted in 0-90 and 270-360 images on 10/13/17 Debris was removed during 60 psig air blowing on 10/21/17. Non-relevant adjacent vessel stain with no accumulation was removed with CO2 on 10/23/17.

Air 8

40 Debris noted in 0-90 and 270-360 images on 10/13/17 Debris was removed during 60 psig air blowing on 10/21/17. Non-relevant adjacent vessel stain with no accumulation was removed with CO2 on 10/23/17.

Air 9

45 Debris noted in 0-90 and 270-360 images on 10/13/17 Debris was removed during 60 psig air blowing on 10/21/17.

Air 10 47 Debris noted in 0-90 and 270-360 on 10/13/17 After 60 psig air blow, the debris was deemed non-relevant through visual examination because it does not have an apparent path below. A successful attempt was made to remove the debris utilizing CO2 on 10/23/17.

Air, visual examination, CO2 11 48 Debris noted in 180-270 and 270-360 on 10/13/17 Debris was removed during 60 psig air blowing on 10/20/17.

Air

Enclosure Relief Request 57 Nozzles Identified with Debris Removed After Cleaning Efforts Item Nozzle Comment Disposition Debris Disposition Method 12 49 Debris noted in 0-90 and 270-360 on 10/13/17 After 60 psig air biow, the debris was deemed non-relevant through visuai examination because it does not have an apparent path below. A successful attempt was made to remove the debris utilizing CO2 on 10/23/17.

Air, visual examination, CO2 13 52 Debris noted in 0-90 and 270-360 on 10/13/17 As-left image from 10/17 of 0-90 does not show indication of debris, debris on 270-360 was removed with 60 psig air on 10/20/17.

Air 14 53 Debris noted in aii images on 10/13/17 Debris was removed inadvertently during the CO2 cleaning on 10/17/17. The nozzle was not directly blown on by CO2; however, it is near the vicinity of the locations that were cleaned, and the deposits were removed.

Air 15 57 Debris noted in 90-180, 180-270 and 270-360 on 10/13/17 The debris was removed from the 90-180 and 180-270 locations utilizing 60 psig air. The debris that was in the 270-360 area was deemed non-relevant through visual examination after 60 psig air because it does not have an apparent path below. A successful attempt was made to remove the debris utilizing CO2 on 10/23/17.

Air, visual examination, CO2 16 58 Debris noted in 270-360 image on 10/13/17 After 60 psig air blow, the debris was deemed non-relevant through visual examination because it does not have an apparent path below. A successful attempt was made to remove the debris utilizing CO2 on 10/23/17.

Air, visual examination, CO2 17 59 Debris noted in 0-90 and 270-360 images on 10/13/17 As-left image from 10/17/17 of 0-90 does not show indication of debris. Debris on 270-360 was not removed with air, but deemed non-relevant through further visual evaluation. The non-relevant condition was removed using CO2 on 10/23/17.

Air, visuai examination, CO2 18 63 Debris noted in the 0-90 image on 10/13/17 After 60 psig air blow, the debris was deemed non-relevant through visual examination because it does not have an apparent path below. A successful attempt was made to remove the debris utilizing CO2 on 10/23/17.

Air, visual examination, CO2

Enclosure Relief Request 57 Nozzles Identified with Debris Removed After Cleaning Efforts Item Nozzle Comment Disposition Debris Disposition Method 19 65 Debris noted in 0-90 and 270-360 images on 10/13/17 After 60 psig air blow, the debris was deemed non-relevant through visuai examination because it does not have an apparent path below. A successful attempt was made to remove the debris utilizing CO2 on 10/23/17.

Air, visual examination, CO2 20 69 Debris noted in 0-90 and 270-360 images on 10/13/17 Debris was removed during 60 psig air blowing on 10/20/17 Air 21 72 Debris noted in 0-90 and 270-360 images on 10/13/17 After 60 psig air blow, the debris was deemed non-relevant through visual examination because it does not have an apparent path below. A successful attempt was made to remove the debris utilizing CO2 on 10/23/17.

Air, visual examination, CO2 22 77 Debris noted in 0-90 image on 10/13/17 After 60 psig air biow, the debris was deemed non-relevant through visual examination because it does not have an apparent path below. A successful attempt was made to remove the debris utilizing CO2 on 10/23/17.

Air, visual examination, CO2 23 80 Debris noted in 270-360 image on 10/13/17 After 60 psig air blow, the debris was deemed non-relevant through visual examination because it does not have an apparent path below. A successful attempt was made to remove the debris utiiizing CO2 on 10/23/17.

Air, visual examination, CO2 24 93 Debris noted in 270-360 image on 10/13/17 After 60 psig air biow, the debris was deemed non-relevant through visual examination because it does not have an apparent path below. A successful attempt was made to remove the debris utilizing CO2 on 10/23/17.

Air, visual examination, CO2 25 96 Nozzie staining from above noted in 1R18, still present in 1R20 Cieaned non-relevant indications with CO2.

Visual examination, CO,

Enclosure Relief Request 57 Nozzles Identified with Debris Remaining After Cleaning Efforts Item Nozzle Comment Disposition Debris Disposition Method 1

16 Slight debris in annuius in the 0-90 image. The debris is at the top of the annuius with no apparent path down below.

After 60 psig air, debris was deemed non-relevant and an attempt was made to remove it utilizing CO2 on 10/23/17. In the process a piece of foreign material was pushed up from the annulus below. It appears to be a bristle from a wire brush.

Air, visuai examination, CO2 - foreign materiai remains 2

27 Debris noted in 0-90 and 90-180 as-found images. Vessei stain noted on 270-360 image from 10/20/17 At 0-90 and 90-180 debris biew away with 60 psig air, but the adjacent vessei staining with no accumulation of depth was stiii present after 10/21/17 attempt. Vessel stain was deemed non-reievant and removed with CO2 on 10/23/17. At the conclusion of the CO2 cieaning, a non-relevant condition was noted in the 270-360 image and an unsuccessfui attempt to remove it was made. A smaii, non-reievant white debris remains in the annuius of the 270-360 image.

Air, visuai examination, CO2 - siight non-reievant debris remains 3

39 Debris noted in 0-90 image on 10/13/17 Debris was not removed with air and further evaluated visually to determine that it is not reievant. An attempt was made to remove the non-reievant condition with CO2 on 10/23/17, but was unsuccessfui. A non-reievant condition is stiii present in 0-90 after CO2 on 10/23/17.

Air, visuai examination, CO2 - slight non-relevant debris remains 4

62 Debris noted in 0-90 image on 10/13/17 Debris was not removed with air and further evaluated visually to determine that it is not relevant. An attempt was made to remove the non-relevant condition with CO2 on 10/23/17, but was unsuccessfui. A non-reievant condition is stiii present in 0-90 after CO2 on 10/23/17.

Air, visuai examination, CO2 - slight non-relevant debris remains 5

84 Nothing noted in 1R20 inspection, siight debris in 1R18 inspection Debris was not removed with air and further evaiuated visually to determine that it is not reievant. An attempt was made to remove the non-reievant condition with CO2 on 10/24/17, but was unsuccessfui. A non-reievant condition is still present in 90-180 after CO2 on 10/23/17.

Air, visual examination, CO2