IR 05000461/1990008
| ML20034C196 | |
| Person / Time | |
|---|---|
| Site: | Clinton  |
| Issue date: | 04/26/1990 |
| From: | Danielson D, James Gavula NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | |
| Shared Package | |
| ML20034C187 | List: |
| References | |
| 50-461-90-08, 50-461-90-8, NUDOCS 9005020158 | |
| Download: ML20034C196 (5) | |
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5 U. S. NUCLEAR REGULATORY COMMISSION-REG 10N^111
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Report No.:, 50-461/90008(DRS)-
Docket No;:',.50-461.
JLicense No.:
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Licensee: '111inois Power Company =
500-South 27th Street:
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.Decatur, IL: 62525 Facility Name: 1Clinton Power Station
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Inspection.At: -Clinton Site, Clint'on,.ll: 61727:
l Inspection: Conducted: April-10-12, 1990-n
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M#6/96 J. A. Gavula.
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Approved By: Mb2t M
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D. H. Danielson, Chief Date
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Materials & Processes Section Inspection Summary inspection on. April'10-12, 1990 (Report lNo. 50-461/90008(DRS))
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Areas-Inspected:
Routine safety inspection-of licensee's snubber surveillance and functionaT testing program-(70370) and' actions associated With the snubber
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reduction program (37701). -
Results:
No violations or deviations were11dentified.
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The licensee appears to be properly applying. lessons, learned from the-first refueling outage functional test results.-
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The snubber reduction program :is-still. in the :very early= stages but :
appears to be adequately coordinated and organized.
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DETAILS
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Persons Contacted'
Illinois Power Compa'ny (IP)
- J. G. Cook; Plant Manager
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- J.~A. Miller Manager,cNuclear Station Engineering Department
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- R. T.: Kerestes,: Director,iNuclear-Station Engineering Department-
- S. R.l Bell, SupervisorW Inservice Inspection, Nuclear Station?
Engineering' Department:
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_ *R.'P. Bhat, Supervisor,' Mechanical Design and Analysts Sargent and' Lundy Engineers (S&L):
M. Callahan, Senior Project. Engineer
- Denotes those. attending the exit meetin'g on April 12,;1990.
2.
Snubber Surveillance and Functional Testing (30370)
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Background
=The Clinton Power' Station (CPS) has-approximately-823fsnubbers--ini the Te ^ ical Specification testing program.:.:These are-divided into six tc
'aasedLon size classification ~with four types of mechanical snubbe., and two types of hydraulic: snubbers. ~ One of 'the-types: of mechanical snubbers.'is~ a. compensating strut type which limits the
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amount: of displacement under load. The other.three categories'of mechanical snubbers are the typical shock arrestor type of>various sizes. The two hydraulic snubber categories are:various sizes:of a pressurized reservoir type unit.
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Procedure Review l
.i Relevant portions of the following procedures were reviewed to
determine compliance with NRC requirements and licensee commitments:=
(1) CPS No. 8160.4, " Snubber Removal and Installation". Revision 6,-
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dated May. 10, 1989.
(2) CPS-No. 9275.01, " Snubber Visual Inspection", Revision:24,
dated October 24, 1988.-
l (3) CPS No. 9275.02,." Snubber Functional Test",-Revision'23.-dated February 1, 1989.
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EP-4, " Preparation of Snubber Lists", Revision 1, dated--
j January 3,1989.
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EP-5, " Evaluation of NDE, VT, Functional Test and EC UT Inspection Results", ACN No. 3/1, dated March 19, 1990.
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(6)' Procedure No OSS-QAP-llil, " Functional.TesO ng of Pacific-Scientific: Shock Arrestor", Revision B.
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(7) Procedure No. PA92792, " Field Functional Test Procsdure for-E-System Snubber", Revision B.-
(8) Procedure'No. PA93038, " Fun.ctional Testing;of PS Compensatory Struts", Revision 0.~.
Itwasnotedforitem(5)above,thatadditionaldirectionshouldbe-supplied with regard to declaring hydraulic-snubbers operable if'the:
reservoirs =are less than.70% full.< Based on the procedure, a' snubber with an empty reservoir could sstill' be declared operable. This contradicts Technical-Specification-statements. None of the hydraulic snubber-reservoirs were found empty.during the~ visual inspection.,
Based on discussions.with the licensee, it was well.-known that an empty reservoir causes the snubber to be' inoperable; however, the-procedure will be upgraded to provide additional guidance.
No' violations or deviations were identified.
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' Test Results
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'During the first refueling outage snubber test effort, all of the
snubbers were. visually inspected and found operable..However,.during:
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functional testing, 27 snubbers failed to meet the" licensee's.
acceptance criteria and as a result, 413l snubbers were requit'ed to be functionally tested.
In-26 of these cases,-the failure was a:
high drag value in tension, compression, or both.. In the other case, the failure was a-low bleed rate for a hydraulic-snubber. 'A11' oft the deficient snubbers were replaced with spare snubbers and engineering evaluations performed for each case found-no'significant i-effect on the piping system, i
The following calculations were reviewed to determine.if the effects-i of the failed snubbers-had been properly. evaluated.
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(1) S&L Calculation'EMD-065467, Revision 00, dated April 24, 1989,
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" Engineering Evaluation of Subsystem 1MS31 for Exceedance of
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Snubber Drag Test Acceptance. Criteria".
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(2) S&L Calculation EMD-065597, Revision 00, dated April-24. 1989,.
j Engineering Evaluation of Subsystem 11S01A for Exceedance of j
Snubber Drag Test Acceptance Criteria".:
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For the first calculation, snubber 1MS31002S was modeled as a' rigid-
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restraint and the thermal mode analysis was rerun.
For the second I
calculation, partial models were used to evaluate high drag values
'l for snubbers 11S-1016S, 11S-01020S and 11S-010745. The snubbers were modeled as a rigid restraint of a force corresponding to the:
l as-found drag load which was applied to the piping at the snubber-
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location.
In both calculations, the pipe stresses were found to be less than the allowable and any support load increases were determined to be acceptable.
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During the review of the hydraulic snubber test results, it was noted that in one case a load correction factor was applied to a bleed rate which allowed the snubber to meet the low bleed acceptance criteria.
'he load correction factor was based on the ratio of the snubber rated load to the actual test load.
Using this approach, a bleed rate lower than the acceptonce criteria was justified as being acceptable.
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This correction f actor, however, was not applied to any of the high end bleed rate values. Using this approach, a bleed rate toward the upper end of the acceptance criteria may not be acceptoble based on applying the load correction factor.
Additional reviews conducted by the licensee during the inspection concluded that application of the load correction f actor would not cause any of the snubbers with acceptably high bleed rates to exceed the acceptance criteria.
Based
on discussions with the licensee, this aspect will be considered during the next functional test performance.
One enhancement to the snubber functioncl testing program being implemented by the licensee is the generation of Inservice Inspection Schematic Drawings.
These ore basically operational schematics which show the analytical boundaries of each piping model.
Using these drawings, the coordination between plant operations and snubber functional testing will be greatly simplified and will clearly show
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specifically what parts of the plant systems are affected analytically
by removing a snubber for functional testing.
These drawings may l
be useful for other aspects of engineering and operational interfaces
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as well.
3.
Snubber Reduction a.
Background Snubber reduction efforts at C tinton are in relatively early stages of development. To date, o pilot program has been performed demonstrating the feasibility and effectiveness of the methodology.
Reanelysis of five subsystems containing 26 snubbers concluded that 25 of the snubbers could be completely removed.
While this removal percentage is probably high due to the choice of low stressed subsystems, an overall removal rate of 70% to 80% is potentially ottainable.
The full scale snubber reduction program was initiated early in 1990.
The intent is to have three phases addressing inside containment,
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auxiliary building, and all other areas during 1990 through 1992.
l Implementation of the snubber removal is scheduled for the first
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quarter of 1993.
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Procedure Review The following project instructions were reviewed with regard to
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compliance with NRC requirements and licensee commitments:
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_(1) Sargent and Lundy, PI-CP-241',1" CAD Generation of Isometric m
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-Analytical Drawings for SnubbergReduction:Activ_ities",
> Revision 1, February 281990..
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(2) Sargent and Lundy, PI-CP-24?, " Snubber R' eduction: Analysis",.-
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Revision 0; February 29,L1990.
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Na a'dverse comments were made1as a result of this review.
'It was noted that-S&L-ir, performing the major scope of_ work, with
-General Electric (GE) having only' aismall part based on:the: original-
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scope of analysis. As a-result, the design interfacescare.mainlyx l
within S&L and should be well established and controlled. The'S&L:
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and GE interface has-already been recognized by the-licensee as requiring additional attention.: Based on this=, as well as-the scope e!
of work residing within the original design. organizations, the-
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. program should experience minimum problems: compared,to others noted.
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' Calculation Review-One of the snubber reduction pilot program. analyses-was reviewed by J
the NRC inspector for compliance with'NRC requirementstandithe'.
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licensee's commitments. Calculation No. EMD-065297, " Reactor Water l-Cleanup", Revision 4, dated December 15, 1988',._was reviewed with'
no adverse' comments.
L No-violations or d.sviations were identified..
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4.
-Exit. Interview f
The Region Ill inspector met with licensee representativesL(denoted in i
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Paragraph 1) at the conclusion of the~ inspection'on'. April.12P 1990.J The-inspector summarized the purp"se and findings of;theLinspections The
licensee representatives acknowledged this.informatio_n.' 1The-inspector.
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also discussed the likely informational:contentiof; the inspection-report
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i with regard to_ documents or processes reviewed-during the' inspection.
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i-The licensee representatives did not identify any such documents / processes-
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as proprietary, r
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