ML20210D700

Forwards Comments on Sser License Condition 2.C(11), Including Info Re Small Bore Piping Supports Reanalyzed & Requalified by Computer Analysis & Cases in Which Rigid Supports Are Placed in Close Proximity to Other Supports

ML20210D700
Person / Time
Site:	Diablo Canyon
Issue date:	07/10/1984
From:	Yin I NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
To:	Vollmer R Office of Nuclear Reactor Regulation
Shared Package
ML20210D653	List: ML20210D649 ML20210D658 ML20210D663 ML20210D675 ML20210D700 ML20210D709 ML20210D716 ML20210D726 ML20210D749
References
FOIA-86-197 NUDOCS 8609190305
Download: ML20210D700 (9)

Text

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July 10, 1984 MEMORANDUM FOR: Richard H. Vollmer, Director, Division of Engineering, Nuclear Reactor Regulation FROM: I. T. Yin, Senior Mechanical Engineer, Division of Reactor Safety, Region III

SUBJECT:

COMMENTS ON SSER LICENSE CONDITION 2.C.(11) PREPARED BY THE DIABLO CANYON PIPING PEER REVIEW PANEL The draft SSER License Condition 2.C.(11) Items 1, 4, 5, 6, and 7 were telecopied to Region III on July 3,1984. Items 2 and 3 were received o'n July 9, 1984. Provided herewith are my comments.

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I.' T. Yin Senior Mechanical Engineer Division of Reactor Safety Region III 8609190305 860916 PDR FOIA HOLMES86-197 PDR

SSER for License Condition 2.C.(11), Item 1 PG&E shall complete the review of all small bore piping supports which were reanalyzed and requalified by computer analysis. The review shall include consideration of the additional technical topics, as appropriate, contained in License Condition No. 7 below.

Comments The following data is required before any meaningful comments can be provided:

1. Subsequent to the OCP's review of all computer analyzed small bore piping supports, how many (among the 358 total population) will require hardware adjustment, modification or rework?

2. In conjunction with 1 above, how many were unable to meet the Code and FSAR requirements after the first rerun in the computer?

These supports required alternative or additional computational effort in orde'r to meet the design criteria.

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3. Peer Review Panel (PRP) identified that OPEG design judgement (design

. basis and criteria presumably) was not documented in some of the calculations. What PRP action,.if any, was initiated to determine that these were just a few isolated cases? If the situation was determined to be generic, was there any license program upgrade mandated by the PRP?

4. PRP identified calculational deficiencies consisting of erroneous STRUDL input assumptions of structural member properties and geometry. Was there a licensee procedure that had included avantitative or cualitative acceptance criteria for accepting these types of deficiencies?

If not,'what are the PRP's criteria in determining that no further action is reauired?

SSER for License Condition 2.C.(11), Item 2 The licensee shall identify all cases in which rigid supports are placed in close proximity to other rigid supports or anchors. For these cases, the lic-ensee shall conduct a program that assures loads shared between these adiacent supports and anchors result in acceptable piping and support stresses. Upon completion of this effort, the licensee shall submit a report to the NRC staff documenting the results of the program.

Comments

1. The SD and 10D criteria was established by Peer Review Panel (PRP) on June 20, 1984 at Cloud office with my concurrence. One week later the NRR staff telephoned me stating that the licensee had requested some exemption on the 100 proximity criteria for the snubber-anchor pair.

Decoupled branch connections designed by the span rule were requested to be excluded for the review because it will require excessive effort, and that may delay licensing process. The NRR staff honored the reouest based on. the reason that the decoupling branch connections are less important to safety. Plesse .p'rovide tectinical justification on exempting .

the PRP criteria. 'I reme.mber clearly. that.Dr. Cloud had stated, during various hearings and meetings, that the only small bore piping that will be overstressed during seismic event would be those located at the connections to the large bore piping.

2. The SSER states, "If unacceptable, the actual manufacturer's test reports on lost motion were reviewed for the unique snubber." Please explain why snubber displacements under load were not a concern to the PRP in deter-mining snubber operability?

3. The SSER stated, "The plant site inspection provided the NRC staff (PRP presumably) an opportunity to inspect the affected components on a first hand basis.", and that three snubbers installed in proximity to the equipment nozzle and rigid restraints "were viewed" by PRP. Please discuss the purpose and scope of the viewing, and what hardware attri-butes had been checked and verified by PRP.

4. Among the 95 " proximity" snubbers, please provide the following technical information:

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a. Install tion of the snubber is iustified because of excessive (1/16" thermal movement at the location. How many belong in this category?

b. How many snubbers, subsequent to the evaluation, were determined to be inoperable at either DE, DDE, or Hosgri seismic condition based on the 0.06" deflection criteria?

SSER for License Cnndition 2.C.(11), Item 3 The licensee shall identify all cases in which snubbers are placed in close proximity to rigid supports and anchnrs. For these cases, utilizing snubber lockup motion criteria acceptable to the staff, the licensee shall demon- ,

strate that acceptable piping and piping support stresses are met. Upon '

completion of this effort, the licensee shall submit a report to the NRC staff documenting the results. .

Comments

1. The SD and 10D criteria was established by Peer Review Panel (PRP) on June 20, 1984 at Cloud office with my concurrence. One week later the NRR staff telephoned me stating that the licensee had requested some exemption on the 100 proximity criteria for the restraint-anchor pair.

Decoupled branch connections designed by the span rule were requested to be excluded for the review because it will require excessive effort, and that may delay licensing process. The NRR staff honored the request based on the reason that the decoupling branch conne'ctions are less important tol safety. Please provide technical justifiyation.on exempting:

the PRP criteria. 'I remember clearly that Dr. Cloud had stated, during- -

various hearings and meetings, that the only small bore piping that will- -

be overstressed during seismic event would be those located at the '

connections to the large bore piping.

2. Among the 423 rigid restraints, how many required shimming?

3. In conjunction with 2 above, if shimmings are not provided, will the conditions cause over-stress on the supports or piping systems? -

4. In conjunction with 3 above, if extensive potentially over-stress condi- .

tions did exist without proper structural shimming having been performed, 1 would it be a 10 CFR 50.55(e) reportable item that had never been reported?

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l SSER for License Condition 2.C.(11), item 4 .

PG&E shall identify all pipe supports for which themal. g6ps have 'been specifically included in the piping thermal analyses. For there cases the _i licen's ee shall develop a program for periodic inservice inspect-icn to assure that these gaps are maintained throughout the operating life of the plant.

PGSE shall submit to the NRC staff a report containing the gap monitoring program.

Comments _

The licensee measures taken and proposed future actions are considered to be ,

acceptable.

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S$6R.for 1.icense Cor.dition 2.C.(ll), Item 5 PG&E shall provide to the hRC the procedures and schedules for :.he hot walkdowns of the main steam system piping. PG&E shall document the main steam hot walkdown results in e reocrt to the !!RC Staff.

Ccmments

1. The objective failed to describe inspection cf spacings provided for piping compcnent seismic (DE, DDE, and Mosgrf) movements at operating (hot) positions. The program did not provide neasures to inspect for:

(1) piping components that nay doma electricalpanelshndcabletrays,fepotentiall'nterferencessuchas2)c6mponents.thatm by closely spaced structures, and (3) interference th-+. could change the p9 ping ratural frequencies thus caused redistributi.on f support loads, or shif ting cf bia' nce loadings to the r. ore criticil .es tpment nozzle connections.

2. Fricticn.of the s)iding type support.wes observed by th. .lidensee to be a ,

problem in meetiog the Code, and, it wa.s ~ replaced by a sway strut. It.can reasonably be assen,ed that ccetain type's of sliding s.upports installed at Diable Canyon ccald causs exce:sive frictional force. Did PRP inquire into the licer.see measure to review the issue en a generic basis?

3. There appears to be a larx of en orderly and systematic presentation on the PRP performance of their, assignmer.t at the site. Please provide the following technical information:

a. Temcerature sersus mecsurement 'inatrix of all data points.

b. P& yds, piping isometrf ts. support details, and pertinent structura) drawings and skettbes.

c. Record of pretest walldownt including review of maximum thermal plus seis.nic movements, and jespection of possible locaticrs that -

cculd be in violation of the above review data conclusions. .

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SSER for Licente Condition 2.C.(11), Item 6 PG&E sha'il conduct a review of the ' Pipe Support Design Tolerance Clarifica-tion" (PSDTC) Program and the "D$ablo Problem" (DP) System activities. The review shall include specific identification of the following:

1. Support changes which deviated from the defined PSDTC Program scope

2. Any significant deviations between as-built and design configurations stencing from the PSDTC or OP activities ,

3. Any unresolved matters idertified by the DP system ,

The purpcse of this review is to ensure that.all design changes and modifica-tions have been resolved and documented in an appropriate manner. Upon completion, PG&E shall submit a report to the 11RC staff documenting the results of this review, Comments ,

1. PDSTC

a. Approximately 15,000 TCs were written since the inception of the program. This means that about 70% of all the large bore and small bore support design including calculations had been "quickly fixed (or more appropriately - deviated)" by few site engineers. It was inconceivable tnat the licensee management was unaware of a 0A program breakdown of this magnitude. .Did PRP investigate whether or -

not there had been any DCP management's predetermined decision to bypass QA program commitments relative to design change control (FSAR commits to 10 CFR 50 Appendix B QA criteria)?

b. The SSER stated that, "Upon completion of construction of the support, the complete as-built package, including any PSDTC forms associated with that support, was forwarded by Construction to ,

Engineering for final acceptance in accordance with project engineering procedures." The PRP conclusion was contrary to the evidence provided by an anonymous alleger during the staff interview ccnducted on May 22, 1984. The documentational evidence showed that some of the TCs were not included in the as-built packages. These TC items included abandoned concrete expansion anchor bolt drilled holes, and added on wing plates to the original base plates.

c. Many rather significant engineering concerns were brought forth during the May 22, 1984 meeting with the anonymous alleger. The trEnscript was still in confidential status. The staff stated in J the transcript that due to the lateness of tre day, a followup on the meeting could probably be scheduled in two weeks. The SSER j should address specific reasons for which the followup meeting was i not Scheduled. j 4

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d. Four of the scpport installations were examined by the PRP team,,

the team consisted of one NRR Branch chief, one consultant from Battelle, and two consultants fr0m EG&G Jdaho, fly concerns are:

(1) the sample si:e selected for Consideringappeared observation the sizetoofbethe group,ly small judging by thra NRC unusual ,

regional inspection standard.

(2) Have any or all of the team members had any prior hands :ce hardware inspection experience?

t J (3) Please provide sufficient detail descriptions on how the ,

supports were inspected, and what attributes have been checked -

and verified.

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The licensee measures taken, and the PRP review and evaluation effort are considered to be acceptable.

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S5ER for License Corditfon E.c.(11), Ite.n 7 ,

DGAL sfiell conduct a program to' demonstrate f.het the Pclim:ing tecnnical topict have been tidequately addressed in the design of cmall and large bere piping supports:

(a) 'inclusi.or of werping normal and shear stresses due to torsfon f n those 1 open sedtions where yarping effects are significa G.

(b) Fesblution of differences betweet, the AISC Cod,e and Becht;l criteria with regard to allowable lengt.hs of unbeaced angle sectient in fending.

h) Consi6eration of 'iteraf/torsibnal buckling under axiaI lodding of Sngle ineabert.

(d) Irclusion of axial and torsional loads due to soad 2.'ccentricity where appropriate.

(e) Correct cticulatleo of pipe support fur.damental frequgrey by Rayleigh's

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(f) Consideration of ficre bevel weld effective throat thickness as used on struct~ure,1 steel tubing with an outside radius of loss than 2T.

PS6E shall submit a report to the NRC Staff documenting the results of the prograra.

Cearnen ts Above allegation items were not astigned to me for followup ections.

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