ML18058A208
| ML18058A208 | |
| Person / Time | |
|---|---|
| Site: | Palisades  |
| Issue date: | 02/14/1992 |
| From: | Slade G CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NUDOCS 9202250149 | |
| Download: ML18058A208 (6) | |
Text
con*sumers Power POWERIN&.
lllllCHl&AN*s PRO&RESS Palisades* Nuclear Plant: : 27780 Blue Star Memorial Highway, Covert. Ml 49043 Febiuary 14, 1992 Nuclear Regulatory Commission Document Control Desk Washington, DC 20555 DOCKET 50-2.55 - LICENSE DPR-.20 - PALISADES PLANT MODIFICATION.ENGINEERING INSPECTION FOLLOW-UP ACTIO~S - UPDATE
. GB Sla_de.
General Manager.
An NRC Special Asse~sment ~ranch engineering team i~spection wa~ conductea at the Palisades Plant from June 10, 1991 through June. 21, 1991. _During the inspection, the team reviewed various aspects of the plant's mo.dification.and
~ngineering programs including the Steam Generator Replacement Ptoject.
- The
- team reviewed their inspecfion findings at an exit.meeting held on Friday',
- °'
June 21,*1991.
After* reviewing the team's observations, Cons~mers Powe~ Cpmpany proposed six.
attions to improve the performance in the are~s of modification engin~ering
- and engineering practices in gene~al. These actions ~eie: committed to the NRC
- in 6ur July 9, 19~1 l~tter. Since then, many of the a~tions have been completed or have evolved such that an ~pdate on the status i~ warranted.
- TiStecrbe low* are tlie--ori gTna r attfons foll owed by the* curre*nt* status~*
7 *-
---~--
- f.
FSAR REVISIONS Original Action The FSAR, Sections 5.7 and 5.10, will be revised to clarify pipe.and pipe support design criteria ~nd reduce ambiguity.
This revi~ion will addre~s design criteria such as faulted and test. allowables..
It is expected that a draft FSAR revision will be available on or before July 19, 1991. At that time we will transmit the draft rev1s1on for NRC staff review.
We have.scheduled a ~orking me~ting with NRR for August 7, 1991, for *discussions on the revision.
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2 Updated Status The proposed revisions to FSAR Sections 5.7 and *5:10 w~re_made during the summer of 1991 and presented to the. NRC for review and discussion at the August 7, 1991, meeting at White Flint.
The revi s-i o'ns resulted* from NRC inspection observations.and recommendations and include revisions or :clarifications to the plant FSAR.in the areas -Of faulted stress allowables, br6adening of response spectra, use* of ab~olute sum rather than square root sum of squares (SRSS), friction 1 oads from thermal expansion, seismic anchor movements _
(SAMs), new response *spectra;_ anchor bolt allowables*, sµpport steel.
verses supplementary steel design, and. other FSAR clarification~. - Staff comments not resolved on August ?were discussed in an* August 15, 1991, teleconference and these.04t~t,nding comments were resolved.
During th~
August. 7, 1991, meeting, the p~oposed FSAR revisions were discussed to
- d~termine if they were clarifications.of existing FSAR criteria or actual chang~s. in plant design criteria reql!iring NRC review and :
.approval.
. It was determined jo.i.~tly between the NRC and* CPCo that of all of the items' reviewed at the*meeting, only the change ~tress allowables for p-ipi.ng would need to b.e approved by the NRC prior to implementation by t.he_ 'pl arit... - :
~ :
- .Cqnsumers Po~er Company's* October 7, 1-9~1, 1 etter _proposed a *change in the piping stress all~wable li~its and requested NRC written concurrence with the change.* T.he-_NRC's __ JanuaryJQ,: 1992, letter transmitted the
. Safety "Evalu.atj_on which approved: the cr.iteria.change:
Ii. *SPtCIFICATION C-173 AND M:-195 UPGRADES Original Action Sp:ec+fi cafi ons. C-i-73,-- "-Techni*ca l Requirements- -fo*r: the **Ana lys.i s -and Design of Safety Related Pipe Supports" and M-195, "Requirements.for the Design and Analysis of-Palisades Plant Safety Related Piping and _
Instrument Tubing," will be. upgraded to.reflect.the FSAR revised.
criteri~ discussed in Item I, aboye.
- It is expected that revisions to C-173 and M-195 will be drafted by July 19, 1991,.and implemented follo\\.iing review *with the-NRC.
Updated Status Draft upgrades of both specifications were completed,.and the specifications were approved for use oh September 17, 1991, for C-173, and on October 22, 1991, for M~l95. The FSAR changes ~iscu~sed above are incorporated in both specifications. Only M-195 contains reference to piping stress allowabfe criteria that required NRC approval.
M~195,
- _Revision 2 was viewed as preliminary _until NRC approval was obtained.
By letter, dated January 30,.1992, the NRC transmitted a Safety
- Evaluation which approved the piping stress allowable c~iteria change.
Based on this approval, designs which used this specificatipn as preliminary can now be made final.
III.
UMBRELLA DOCUMENT Original Action 3
An umbrella document will be written and issued to tie specification and procedural requirements together. This document will be in commentary
~format and each individual ~ithin the Nuclear Engineering and
_Construction Organization (NECO) who performs piping and pipe ~~pport analyses will receive-training to its content: Training will be completed_ by December I~ 1991.
Updated Status Although originally scheduled for completion by December l; 1991, we have concluded that the umbrella document which ties sp~cifications and proc~dural requirements together should not be completed until a better -
- definition bf what needs to be included is a~ailable: We have determin~d that it should be drafted concurrent with a technical -
training program scheduled for the second quarter of 1992 involving both
-the System Engineering and the Nuclear Engineering and Construction Or~anization. (NECO) staff.
As a result, the umbrella document is no~
planned to be drafted by July 31, 1992.
IV.
ASSESSMENT OF.PIPE AND PIPING SUPPbRT ENGINEERING Original Action An assessment of pipe and pipe support' engineering by a contractor-
-commenced on June 3, 1~91. -The purp6se -of th~s assessment ~s to:
- Identify design engineering strengths and weaknesses-.
- Identify root causes of engineering design. weaknesses._
- Suggest improvem~nts to *people, processes. and equipment ~o address root causes of identified weak_nesses.
_Currently, the assessment is scheduled to be complete by July 31,. 1~91.
Upon receipt of the final report, an a~tion pl~n arid schedule will be developed for implementation of the assessment recommendations.
Updated Status The assessment was presented to the Palisades Plant staff on August 16~
1991.
Updates of the assessment were discussed at the October 15, 1991 Enforcement Conference.
Plans for implementing the suggestions in the asses$ment have been consblidatedcwith those plans as~ociated with the Plant's earliei Design Engineerin~ Self Assessment.
The implementation program is ongoing and evolving.
V. CURRENT MODIFICATIONS Original Action Un~il such time as It~ms I and II are completed, no safe{y related modifications involving pipe and pipe support analyses will be implemented.
Upon completion of the FSAR revision ~nd. revisions to specifications C~l73 and M-195, a third party review of all NECO initiated pipe and pipe-supp6rt arialyses will be performed.
Analyses performed by contractors wi 11 recei v.e an in-depth review by NECO engineering prior to impl~mentation. The third party review of NECO
. analyses will".continue until the results of the contractor assessment ar~ rec~ived and an action plan is developed and implemented.
Ba~ed on
- the act fon pl an and schedule, a mil es tone wi 11 be established for termination of the thir_d party review of NECO initiated pipe and pipe
.support analyses.
Exact timing of termination of third party review will be discussed with NRC staff at a later date.
- Updated Status 4
- a.
Preliminar~ analysis~ desi~ns and drawings have been dev~loped b~sed upon the completed C-173, the proposed FSAR change,* and preliminary M~l95.
No safety related*pipe and pipe support*..
modific~.tions have been made between. July 1991 and January 1992.
- Now that we have received the NRC's SER on the FSAR changes (discussed in Item I above), we plan to go forward with a number
. of pipe* and *pipe* support modifications-. -
- b.
The third party review program is in place.
Calculations for review now exist and the review began January 13, 1992..
- We
. recognize this review was implemented 6 months following our commitment letter date; however, this is due to little pipe and pipe support analysis being generated during the intervening period.
- The analyses that were generated have been held preliminary, pending letting of the third party review contract.
- c.
NECO (or its designated contractor) is performing the owner's review of analysi~ completed by contractors.
The scop~ of that review has been proceduralized for ongoing projects and has been in the process of being implemented for a number of month~.
That procedure was -formally incorporated as Attachment A to
5 --
Engineering Manual Procedure 18-03 (which relates to the
-engineeririg'documentation requirements for Palisades Plant piping stress package in~terial) in January 1992; A plan for the termination of these reviews ;will be made when they. no Joriger are shown to be benefici~l.
VI.
MAIN STEAM LINE REANALYSIS
~'
Original Action
\\
As discussed during the NRC Special *Assessment Branch engineering team.-.
inspection exit, the main steam line design will be reanalyzed.. after the -
FSAR *and design specjfi.cations are rev_ised. _ Consumers Power will al igri
_with NRC staff on th_e* details of the *re analysis durfog the August 7;.
- 1991, m~eting and *expect* to be able to complete the work by the end of*
November.
Updated Status :
--_.The reanalysis of the main.steam Jines' ins"ide contai.nment was iititiated.
-in-September of 1991.
A cri.teri~- change in *spe<;:ification M-195*,
- Revision 2,: ass_ociated wi_th spectra broaden_ing h_ad a significant impact.
- on~the analy~~s ~ssociated with th~ steam generator repla~ement project._-
The broadening o,f the.response *spectra had the impact of making-the seismic loads ~ssociated with the ~riginal plant seismic an~lysii.method and: the ASME,.Se<;:tion>>lILCode Case N-411.method siln.ilar in magnitude.
Therefore,._ the Code Ca*s*e N-411 method was adopted for 'subsequent _
- analy~is ~nd design for the main ste~m line and its supports. 'The Code
_Case N-411' method is associated wi~h a.more complete set of response spectra than the original seismic analysis_ method.
Thus, *issues with-
- regard to spectra ~x!:apolation.and e_nvelopi~g no longer become a concern.
The;* results of the'-pipihg -reanalys;.s associated with the ~xisting:,des*ign i.ndicated that an additional pipe support was required.
That additional support-can be provided -by-changing ~the uppermost main--st-eam-1 ine-whip----
restraint atta'ched,to-the.containment shell to a pipe support.' This*
~onversion wil] be achieved by shimming the pipe to the whip restraint -
- to provide lateral.restraint in th~ perpendicular directions.
This modificati*on, also,. *resolves the pipe stress and steam generator nozzle load concern.
- Puring the design and analysis associated with'th.e conversion of the*
whip re~traint into~a pipe support, _a calculational error was found in the analysis of *that restraint.
The analysis was performed during the steam generator replacement project.
The error involved the use of an
_ incorrect.~adius of gyration for the back-to-back angle sets which support the weight of the whip restraint from underneath.
These angles may also share the constant hanger load* supported by the *whip restraint*
with sol fd rods.attached to the top side of.the whip restraint.. The Steam Generator Replacement Project used the-larger (rather than*
,--.f
~
6
- smaller) radius of gyration when computing critical buckling capacity.
The result of the error ii an overestimate of the back-to-back angle support buckling strength and a margihal design of the whip restraiht.
with regard to*whip restraint self weight and constant support hanger
- loads.
The angles become overloaded when seismic self weight excitation is added to static loads as it must be for the analysis of a new support.
The repair of the condition involves the use of a span brace back to the whip restraint (new suppo~t) to. cut down the unsupported length and increase buckling capacity.
- Additional support design concerns were i dent ifi ed with. two constant support hangers, on~ on each of the ~ain stea~ lines.
One concern 6n
. these supports focuses on the potential interference of a washer plate
=With a hanger rod where th~ pipe is subject to large lateral deflections.
The interference could place the rod in local bending
. which is not permitted by the-pipe sup~ort design sp~cification.* A second concern on these supports *is with the capacity of a weld made during the steam generator replacement.project.
The interaction ratio calculated for the weld.during the project was 0.97.. A more appropriate
.,calculation of the interaction ratio, assuming*the drawing wel.d size, yields a ratio greater thah unity. -The welds, washer plate ~nd rod
. condition need to be inspec~ed before a repair decis~on is made.
If the drawings are correct, the weld w.i ll have to be enlarged and the washer plate repaired.
Any modifi~~tions to resolve these identified discrepancies are.planned to be completed during the 1992 refueling
. outage.
- We have determined that the interim operabi 1 ity criteria are met for the
- piping system despite the ~asher plate, support weld; and back-to-back angle discrepancies.
We will be contacting the contractor, who completed this work, for an explanatiQn and justification of methods used in calculations for these discrepancies to resolve our concerns.
Once we reach resolutibn on those identified issues we will review the results and determine if any additional reviews of the contractor's work are needed.*
~µ~_
Gerald B Slade