ML17221A552

Safety Evaluation Supporting Relief from ASME Code Re Inservice Insp Requirements

ML17221A552
Person / Time
Site:	Saint Lucie
Issue date:	12/12/1987
From:	Office of Nuclear Reactor Regulation
To:
Shared Package
ML17221A553	List: ML17221A552 ML20237D570
References
NUDOCS 8712240043
Download: ML17221A552 (12)

Text

~g AK0y,fp

~4 0

Cy nO I

0

/yn +**4+

UNITEDSTATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D. C. 20555 FNCLOSURE SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO THE INSERVICE INSPECTION (ISI) PROGRAM FLORIDA POWER AND LIGHT COMPANY ST.

LUCIE UNIT 1

DOCKET NO.: 50-335

1.0 INTRODUCTION

,r Paragraph 10 CFR 50.55a(g)(4) states that throughout the servfce life of a pressurized water-cooled nuclear power facility, components which are classified as ASHE Code Class 1,

2 and 3 shall meet the requirements set forth fn certain referenced editions and addenda of ASME Section XI to the extent practfcal within the limitations of design; geometry and materials of construction of'he components.

Some plants were designed fn conformance to early editions of this Code, consequently certain requfrements of later editions and addenda of Section XI are impractical to perform.

Pursuant to 10 CFR 50.55a(g)(5),- the licensee identified fn a letter dated October 29, 1986 that certafn ASHE Code requirements are not practical for hfs facility and pro-vided supporting information.

After evaluation of the licensee's determination, pursuant to 10 CFR 50.55a(g)(6)(f), the Commission may grant relief and impose alternative requirements as ft determines are authorized by law and which will not endanger life or property or the common defense and security and are other-wise fn the public interest giving the due consideration to the burden upon the licensee that could result if the requirements were imposed.

2.0 STAFF EVALUATION The staff has evaluated the fssues for which the licensee requested written relief in the following paragraphs.

Unless otherwise indicated, the applicable ASIDE Code fs the 1974 Edition including Addenda through Summer 1975 based on the regulations and the 1971 Edition including Addenda through Winter 1972 based on the plant Technical Specifications.

A.

Interior Clad Surfaces of Reactor Vessels (Examination Cate or an Tn ter or a

ur aces o

esse s

er an eac or esse s

xam na on a e or e

e e ues o.

Code Re ufrements l.

Item Bl.13 -'Vfsual and surface, or volumetric examination of the reactor vessel closure head cladding, fs required of at least six

patches, evenly distributed during each inspection interval.

87<moooei 87iaia PDR,;ADOC< 05000335 P- '.,',

PDR,",

'/

2.

Item B2.9 and 83.8 - Visual examination of vessels other than reactor vessel (pressurizer and steam generators) cladding examination of patches may be deferred to the end of the inspection interval.

Code Relief Re uest The licensee requests relief from performing the Code examination requirements of the interior clad surfaces.

Basis for Re uest 2.

Analysis has shown that flaws which may initiate in the reactor vessel cladding, at locations other than nozzles, are not likely to propagate through the clad-base metal interface.

Because of this data, the need to confirm the initiation of clad fissures is not considered relevant.

Accordingly, the ASYiE-Code has completely eliminated the B-I-1 and B-I-2 Examination Categories from the later editions of Section XI.

Performing these cladding examinations constitutes needless radiation exposure to personnel with no compensating increase in safety or quality.

Current surveys have recorded levels of radiation ranging from 15 rad to 35 rad in the applicable areas of

. examinations of components subject to these requirements.

3.

Pursuant to 10 CFR 50.55a(g)(4)(iv)., the licensee opts to update to the requirements of the 1977 Edition thru Summer 1978 Addenda which deletes the examination requirement.

Staff Evaluation Paragraph 10 CFR 50.55a(g)(4)(iv) states:

"Inservice examinations of components, tests of pumps and valves and system pressure

tests, may meet the requirements set forth in subsequent editions and addenda that are incorporated by reference in paragraph (b) of this section, subject to the limitations and modifications listed in paragraph (b) of this section and subject to Coomission approval.

Portions of editions or addenda may be used provided that all related requirements of the respective editions or addenda are met."

The licensee proposes to use provisions from a later approved ASYiE Code.

The staff has determined that the licensee's proposal

conforms, with the requirements of the regulation that "all related requirements of the respective editions or addenda are met" and, therefore, is acceptable.

Therefore, the staff concludes that relief may be granted as requested by the licensee to eliminate the examination of the clad patches.

Su ort Members for Pi in, Valves and Pum s (Examination a eaor e

e e uest o.

Code Re uirements:

1.

Item B4.9 - Piping integrally welded supports 2.

Item B5.4 - Pump integrally welded supports 3.

Item B6.4 - Valve integrally welded supports Volumetric examinations of support attachments shall cover 25'f the integrally welded supports during each inspection interval.

Code Relief Re uest The licensee proposes to conduct surface examinations in lieu of volumetric examinations of integrally welded support members for piping, valves and pumps for Examination Category B-K-1 (Items B4.9, B5.4 and B6.4).

Basis for Re uest 1.

Volumetric examinations on numerous integrally welded support members are impractical.

The design and

, configuration of these welds are not conducive to meaningful nor conclusive ultrasonic or radiographic examinations.

2.

Pur suant to 10 CFR 50.55a(g)(4)(iv), the licensee opts to update to the examination requirements of the 1977 Edition thru Sutwer 1978 Addenda which permits the licensee to'ubstitute surface for volumetric examination.

Alternative Examinations Surface examinations on integrally welded supports (Category B-K-1) will be performed to ASME 1977 Code Edition thru Summer 1978 Addenda.

The examinations include only those attachments whose base material design thickness is 5/8 inch and greater.

The examinations shall include the component supports of the piping required to be examined by Category B-J, and the component support of pumps and valves integral to such piping.

Essentially 100% of weld length is included.

The examinations during the inspection interval shall cover 25'A of the integrally welded supports.

Staff Evaluation The licensee proposes to use provisions from a later approved ASME Code pursuant to 10 CFR 50.55a(g)(4)(iv).

The staff has determined that the licensee's proposal conforms with the requirements of the regulation that "all related requirements of the respective editions or addenda are met" and, therefore, is acceptable.

The staff concludes that relief may be granted as requested by the licensee to use the nondestructive examination methods in the later Code.

C.

Pressure Containin Welds In Pi in (Examination Cate ory B-J,

~ee e ues o.

~

Code Re uirement Item B4.5, Piping Circumferential and Longitudinal Melds.

Volumetric examination of the circumferential welds and the base metal is required for one wall thickness beyond the edge of the weld.

Code Relief Re uest The licensee proposes to conduct surface examinations in lieu of volumetric examinations of the piping circumferential welds and base metal beyond the edge of the welds within the limitations of existing configurations for Examination Category B'J (Item B4.5).

A sketch of a "Typical Configuration" was provided.

The specific welds involved are as follows:

SYSTEM WELD IDENTIFICATION SAFETY INJECTION 6" -SI-112-2 SAFETY INJECTION 6" -SI-112-2a SAFETY INJECTION 6" -SI-113-2 SAFETY INJECTION 6" -SI-113-2a SAFETY INJECTION 6SI-ll0-2 SAFETY INJECTION 6" -SI-111-2 Basis for Re uest DESCRIPTION TEE TO PIPE PIPE TO VALVE CV-3124.

TEE TO PIPE PIPE TO VALVE CV-3114 TEE TO VALVE CV-3144 TEE TO VALVE CV-3134 I

2.

3.

Volumetric examinations of the piping circumferential welds and base metal beyond the edge of the welds are found to be impractical.

The design and configuration of these welds are not conducive to ultrasonic examination and do not lend themselves to good radiographic examination technique.

The Code (Examination Category B-J, Item B4.>) permits surface examination of branch pipe connection welds six (6) inches in diameter and smaller.

This is somewhat typical and consistent with the pipe-to-tee welds which are six (6) inch nominal pipes in diameter described in the sketch of the "Typical Configuration."

Conduct of the volumetric examinatiops to meet the Code would constitute undue hardship or unusual difficultywithout a compensating increase in the level of quality and safety.

~

~

e Alternative Examinations Perform surface examinations on the piping circumferential welds and base metal beyond the edge of the welds within the limitations of existing configurations for Examination Category B-J (Item 84.5).

The examinations shall cover 258 of the circumferential joints during the inspection interval.

Staff Evaluation e

s a'.

a

~g, D.

The staff has evaluated the sketch of the "Typical Configuration" and determined that the Code-required volumetric examination beyond the edge of the weld is impractical.

The staff determined that the surface examination proposed by the licensee will provide an acceptable level of quality and safety.

Therefore, the staff concludes that relief may be granted as requested by the licensee provided that the alternative surface examinations are performed.

Pressure-Retainin 1'elds In Pressure

Vessels, Examination

~ate or -,

e e

e oes o.

Code Re uirement Item.C'l.1, Steam Generator Staywell Dome to Staywell Cylinder l<elds..

A v'olumetric examination is required'f at least 205 of each circumferential weld, uniformly distributed among three areas around the vessel circumference.

Code Relief Re uest The licensee requests relief from the volumetric examination of the staywell dome-to-cylinder weld.

Basis for Re uest The examination of the staywell dome-to-staywell cylinder weld in both steam generators is not conducive to any meaningful results due to its geometry and accessibility.

The ultrasonic examination of the weld produces meaningless results because of the ultimate stop of the permanent track installation, the clearance of the transducer, and the limited area for the weld and base metal scan.

In the transverse configuration of the module there is 3/4 inch area of base. metal that ideally can be examined.

But the root of the weld is not a smooth area and, therefore, the transducer module cannot ride over the weld smoothly.

Hence, the examination is obstructed by this factor, and also by the curvature of the staywell cylinder dome.

~

~

'L).( gg('gJ'g,~

~

t

An attempt to cover the weld from its bottom side will not be successful due to the tube sheet thickness.

The beam cannot be bounced on a back wall to cover the root of the weld, and again, due to the area geometry, only partial scanning of the weld crown and approximately the upper third of the weld can be performed.

Transverse examination is not meaningful due to the tube sheet thickness and tube configuration.

Therefore, the ultrasonic examination of the weld cannot meet Code requirements and the limited examination that can be performed is not enough to produce any meaningful or conclusive results.

Radiography,

surface, or visual examinations cannot be performed due to inaccessbility of the weld because of the stationary track installed for the ultrasonic examinations of. the rest of the staywel 1 cylinder welds.

Alternative Examination Other welds in the staywell are volumetrically examined by mechanized ultrasonics.

The welds will be subjected to a hydrostatic test in accordance with IWC-5000 of Section XI..

~Staff Evaluation The staff determined that it is impractical to perform the required volumetric or a direct visual or surface examination of the weld and base metal because of the weld inaccessibility and geometry.

Other welds in the staywell are volumetrically examined by mechanized ultrasonics.

In addition, the weld will be subjected to a hydrostatic test in accordance with the requirements of IWC-5000 of Section XI.

The staff finds that monitoring the condition of the other welds in the staywell and performance of the hydrostatic test and checking for leakage will provide assurance of the structural integrity of the staywell dome-to-staywell cylinder weld.

Therefore, the staff concludes that relief from the examination requirement may be granted as requested.

Ett

\\

E*

1 tt EEEEECd C1 1

d 2~Cd e

e e ues o.

Code Re uirement ASIDE Code Section XI (1974 Edition), Paragraph IVA-2232, Ultrasonic Examination:

"Ultrasonic examination shall be conducted in;accordance with the provisions of Appendix I.

Where Appendix I (I-1200) is not applicable, the provisions of Article 5 of Section V shall apply."

ASHORE Code Section Y (1974 Edition), Paragraph T-537, Evaluation of Indications:

"All indications which produce a response greater than 20 percent of the reference level shall be investigated to the extent that the operator can evaluate the shape, identity, and location of all such reflectors in terms of the acceptance-rejection standards of the referencing Code Section."

Code Relief Re uest The licensee requests relief from evaluating indications that are greater than 20K of the reference level.

Licensee Basis for Relief The 20 percent DAC (distance-amplitude correction) criteria of paragraph T-537 of Section V is impractical.

The primary reference level (100 percent DAC) criteria for the ultrasonic (UT) examination of piping welds provides a level of safety comparable to the Section V

standards.

Recording and evaluating indications at 20 percent DAC is impractical for the following reasons:

l.

The welded joints in nuclear piping'frequently contain Code allowable wall thickness differences (12 percent of normal thickness),

as well as some weld dropthrough, counterbore

taper, crown height, etc.

These conditions generate an extremely large number of geometric reflectors which produce UT indications greater than 20 percent DAC.

2.

Meld metal in stainless steel piping contains reflectors due to the metallurgical structure which produce a large number of UT indications.

3.

'All examination personnel experience radiation exposure during inservice examinations.

The Section V requirement'to record and evaluate UT indications at the 20 percent DAC places an unnecessary burden on the limited number of experienced and qualified examiners available to the owner.

Alternative Examination As an alternative examination, the licensee proposes the following.

Indications 50 percent of DAC or greater shall be recorded.

2.

An indication 100 percent of DAC or greater shall be investigated by a Level II or Level III examiner to the extent necessary to determine the shape, identity, and location of the reflector.

3.

Any non-geometric indication, regardless of DAC, discovered during the ultrasonic (UT) examination of piping welds and base metal materials shall be recorded and investigated by a Level II or Level III examiner to the extent necessary to determine the shape, identity, and location of the reflector.

4.

The owner shall evaluate and take corrective action for the disposition of any indication investigated and found to be other than geometric in nature.

Staff Evaluation

'n rn The staff finds the licensee's alternative examination procedure adequate for the detection of cracks warranting evaluation.

The Code requirements involve the recording and reporting of indications at a very low amplitude level.

Based on the alternative examinations, the licensee will perform the required examinations, evaluate a11 non-geometric indications that could be potential flaws and take corrective action.

The licensee will record all indications 50'A of DAC or greater.

The staff finds that the licensee's alternative acceptable and the staff concludes that relief may be granted as requested.

F.

Valve Bodies, Relief Re uest No. 7 Code Re uirement Item B6.7 - A visual examination of the internal pressure boundary sur faces is required of valves exceeding 4 inch nominal pipe size.

One valve in each group of valves of the same constructional design shall be examined.

Code Relief Re uest The licensee requests relief from the requirement to disassemble the valves.

Basis for Re uest Disassembly of these valves for the sole purpose of performing a visual examination is not practical.

The process of disassembling these components will result in considerable exposure of personnel to radiation and signifi-cantly increase the risk of component damage or failure without providing a compensating increase in the level of quality and safety.

Alternative Examination 1.

Periodic inservice testing per subarticles IWV-3400 and/or IMV-3520 (valves).

2.

Periodic system leakage test per Category B-P, table IWB-2500; 3.

Per form the required visual examinations, in accordance with the sampling criteria of table IMB-2500, Category

'-Yi-2 in the event the components are disassembled for maintenance or repair; 4.

The alternative tests and examinations provide an assurance of acceptable quality and safety.

Staff Evaluation The staff has determined that the disassembly of functioning valves for the sole purpose of performing a visual examination of the internal surfaces is impractical.

The staff finds tha't the system pressure tests and periodic inservice tests will provide an acceptable level of quality and.

safety.

Therefore, the staff concludes that relief may be granted as requested.

In the event that a valve subject to visual examination is disassembled for repair or maintenance-to a degree that the Code requirement is practical, the staff will require that the visual examination be performed and documented.

G.

Technical and Administrative Issues In the letter dated October 29, 1986 the. licensee identified the fol.lowing outstanding issues related to the first inspection interval.

Licensee's Re uest 1.

As required by 10 CFR 50.55a(g),

FPL has updated the ISI Program for St. Lucie Unit 1 to the requirements of the f974 Edition through Summer 1975 Addenda of.Section XI of the AShE Boiler and Pressure Vessel Code.

This is still applicable for the first 10-year Inspection Interval which ends February 11, 1988.

The program was submitted to NRC by FPL letters L-77-203 (July 1, 1977) and L-77-291 (September 16, 1977).

Interim NRC approval was granted on December 20, 1977, but final NRC approval is still pending.

2.

On April 22, 1983 (L-83-254),

FPL requested relief from schedular requirements for mechanized examinations, as a

result of the thermal shield problems which necessitated removal of the reactor internals.

The relief request also included FPL's intent to conduct the vesse1 examinations to the ASME 1977 Edition through Summer 1978 Addenda, and Regulatory Guide 1. 150, Revision 1, with the exception of those examinations conducted during the first inspection period per the St. Lucie Unit 1 Technical Specifications and ASHE 1974 Edition through Suamer 1975 Addenda.

Although the schedular relief became unnecessary due to the extended

outage, NRC approval is still needed for FPL to take credit for the vessel examinations conducted as described above.

Staff Evaluation 1.

The staff determined that the technical review that resulted in the December 20, 1977 approval is the final'decision and the staff considers this issue closed.

2.

The staff concludes that the reactor vessel examination scheduled and performed before the end of the inspection interval based on a later referenced Code edition is acceptable and the staff considers this issue closed.

3.0 CONCLUSION

S Paragraph 10 CFR 50.55a(g)(4) requires that components (including supports) which are classified as ASHE Code Class 1,

2 and 3 meet the requirements, except design and access provisions and preservice requirements, set forth in applicable editions of ASIDE Section XI to the extent practical within the limitations of design, geometry and mater ials of construction of the components.

Pursuant to 10 CFR 50.55a(g)(5)(iii), the licensee determined that conformance with certain Code requirements is impractical for his facility and submitted supporting information.

The staff concludes that relief may be granted f'r the issues described in Relief Request Numbers 2, 3, 4, 5, 6 and 7 subject to the conditions described in this evaluation.

Dated:

Princi al Contributor:

N.

Hum

0 J

~'

'i 1