ML20024B955
| ML20024B955 | |
| Person / Time | |
|---|---|
| Site: | Vermont Yankee File:NorthStar Vermont Yankee icon.png |
| Issue date: | 06/09/1983 |
| From: | Vassallo D Office of Nuclear Reactor Regulation |
| To: | Sinclair J VERMONT YANKEE NUCLEAR POWER CORP. |
| References | |
| NUDOCS 8307120045 | |
| Download: ML20024B955 (8) | |
Text
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DIST: Docket File NRC PDR LPDR SNorris DEisenhut BSiegel 0 ELD ACRS-10 ASLAB Gray ORB #2 Rdg JHeltemes, AE00 ELJordan JMTaylor FEltawila VRooney Docket flo. 50-271 Mr. J. B. Sinclair JUN 9-g Licensing Engineer Verront Yankee !!uclear Power Corporation 1671 Worcester Road Franingham, liassachusetts 01701
Dear Mr. Sinclair:
SUBJECT:
l' ARK I C0!!TAIMMEllT LONG TEPd PROGRN! - PLAT:T UNIQUE ANALYSIS REPORT LOADS EVALVATIO!!
Re: Vermont Yankee Nuclear Power Station The NRC staff and its consultant Brookhaven flational Laboratory (BliL) are reviewing the structural aspects of your plant unique analysis report. As a result of our review to date we have prepared the enclosed request for additional infornatten.
To expedite this review it is requested that within three weeks of the date of this letter a meeting between the NRC and our consultants, and you and your contractor be held to discuss your response to these issues. Since it is our intent to resolve these issues at this meeting, it is inperative that you have a representa-tive at this necting that has the authority to nake the decisions necessary to accomplish this goal.
It is suggested that this roeting be held at your contractors office; however, we are anenable to having it wherever it is most convenient. Please notify your project nanager within seven days of receipt of this letter with a proposed necting date.
If you cannot meet the three week schedule, propose an alternative orie.
This request for infornation was approved by the Office of Managenent and Budcet under clearance number 3150-0091 which expires October 31, 1985.
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Sincerely, i
ORIGINAL SIGNED BY Donenic B. Vassallo, Chief 8307120045 830609 Operating Reactors Uranch #2 PDR ADOCK 05000271 Division of Licensing P
Enclosure:
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Mr. J. B. Sinclair Vermont Yankee Nuclear Power Corporation Vermont Yankee Nuclear Power Station cc:
Mr. W. F. Conway W. P. Murphy, Vice President &
President & Chief Executive Officer Manager of Operations Vermont Yankee Nuclear Power Corp.
Vermont Yankee Nuclear Power Corp.
R.D. 5, Box 169 R. D. 5, Box 169 Ferry Road Ferry Road Brattleboro, Vermont 05301 Brattleboro, Vermont 05301 Mr. Louis Heider, V. P.
U.S. Environmental Protection Agency Vermont Yankee Nuclear Pmver Corp.
Region I Office 1671 Worcester Road Regional Radiation Reoresentative Framingham, Massacnusetts 01701 JFK Federal Building Boston, Massachusetts 02203 John A. Ritscher, Esquire Ropes & Gray Public Service Board 225 Franklin Street State of Vermont Boston, Massachusetts 02110 120 State Street Montoelier, Vermont 05602 New England Coalition on Nuclear Pollution Hill and Dale Farm R.D. 2, Box 223 Putney, Vermont 05346 Mr. Walter Zaluzny Vermont Yankee Decommissionirr Chairman, Board of Selectman Alliance P.O. Box 116 5 State Street Vernon, Vermont 05354 Box 1117
.J, P. Pelletier, Pla, nt Mana_aer Montpelier, Vermont 05602 Vermont Yankee Nuclear Power Corp.
Resident Inspector P.O. Box 157 c/o U.S. NRC Vernon, Vermont 05354 P.O. Box 176 Vernon, Vermont 05453 Vermont Public Interest Research Raymond N. McCandless Group, Inc.
Vermont Division of Occupational 43 State Street
& Radiological Health Montpelier, VT 05602 Administration Building 10 Baldwin Street Montpelier, Vermont 05602 Regional Administrator, Region I U.S. Nuclear Regulatory Commission Honorable John J. Easton-631 Park Avenue Attorney General King of Prussia, PA 19406 State of Vermont 109 State Street Mr. Richard Saudek, Commissioner Montpelier, Vermont 05602 Vermont Department of Public Service 120 State Street Montpelier, Vermont 05602
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" REQUEST FOR ADDIT!0 MAL NFM " FIT!
RELATED TO THE MARril PU9R E. h.
20P 1EPf'ONT YAhKEE' z
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W%9 ITEM 1:
PUAR section 2.2.1, AC section 2.13.8.2 & 2.13.9.3 The temperature monitoring system, described in the'PUAR using a total of 10 thermocouples placed at 5 different torus locations differs from
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the Acceptance Criteria in several important: respects.
For iocal tem-perature the criteria state that "For practical purposes, the average water temperature observed in the sector containino the discharge de-Vice at shell locations on the reactory side of the torus downstrean of the quencher centerline at thEsame eN!ivation-as. the quencher device
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ar.d at the quencher support may be considerec 'as the_ ". local tempera-ture".
In Vernant Yankee tha 'thernacpupl ; are orQhe " outboard" side of the torus (side away from;fhe reactor) 'dcoM two of the four SRV w.
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discharge bays qre upstream of the'duencher ceQ4rline.
There are no thermocouples. at or near the cuencbr,3aororts., Therefbabea'dyring -
n local temperature in the sense of 'the,* Accept,ancr Criteria, UnnE De s
, g accomplished by this system.
For bulk temocrmre the cre.eria statds e s that "Each lidensee shall denon' strate that th,& ir a dfficient number
- ~,ns and distribution of cool temperature sensors d., cb, vide.a reahnable means of bulk'~temcerature". The brief descriptidn~aric illustration in
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the PVAR do:not demonstrate that a reasonable 2easure;of the bulk pool t
s-temperature can be obtained from the VernonS Yankee syjtem.
The PUAh,;
- 2 does not make clear whether,tyt,intension ar7.'3rmorG Yankee is to nel -
s-x sure bulk pool temperature Or fNeasure local teaoerature direc+.ly, pr{
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Explain how the local temperature limit is to be determineg { f [
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fron bulk pool measurenent or direct local measurement, and justify th?
adequacy of the corresoonding measurement in light of the aboye com[(
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ments regarding dif ferences from the A,cceptance Criteria.
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ITE'i 2:
PUAR section 3.2.1, A section 2.4 h
JJ' Regarding the pool hell loads on t,he thus shell, describe how the s
longitudinal and azimuthai mul'tipliersdLCR Table 4.3.2-1) were use'd,in
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conjunction with the* submerged oressur$ histork s to perform the torus _,.
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..s shell evaluations.
Previde an exYmph' of 'a bimc history at a carticu-
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lar location (e.g., 9 = 180* at Z/f =,0,0) ;to illust ate their use.
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PUAR section 3.2.3, AC section 2.12.(
Regarding the pre-chuqqing and IBA/CO load analysis, the NIR ~ states.
that results for the symmetric pre-chug load were developed dl*rectly Q
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from the unit-load harmonic analysis done for CO.
Does this mean that the water mass was accounted for as in CO (i.e.,100% water mass), and was this loading applied for the cycle duration stated in the LDR?
ITEM 4: PUAR section 3.2.4, AC section 2.13 The PUAR states that the modeling of the water mass in the SRV load computer model was fraught with difficulty. When the water mass was included in the model, measured outputs could not be reproduced by ap-plying measured input to the computer model.
A dry structure analysis produced acceptable results, however, and therefore, the dry structure analysis method was subsequently used as a basis for ali SRV analysis.
This is a very troublesome point.
Since there is no physical reason cited in the PUAR for using a dry containment in the SRV analysis, one is left with the impression that there is an error somewhere in the modeling which is fortuitously compensated for by introducing a second modelling error, i.e., non-inclusion of the water in the torus. A fur-ther difficulty is the implication these modelling results have for other loads such as CO and chugging for which a fluid-structure comput-er model is also used and where the water was included in the analysis.
Since. no verifying measurements for these loads could be made, the pos-sibility exists that these calculations are badly off the mark.
Justi-
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fy the exclusion of the torus water from the SRV analysis on physical grounds and explain why these physical reasons differ for the CO and chugging loads.
ITD4 5:
PUAR Appendix 1, AC section 2.13.9
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The Acceptance Criteria call for the torus shell to be instrumented with strain gages, accelerometers, and pressure transducers during SRV in-plant tests.
Since no accelerometers were used in the Vermont 4
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Yankee torus,, explain how data from the other instrumentation was used to compensate for the lack of accelerometers.
.li ITPi 6:
PUAR Appendix 1, AC section 2.13.9
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Appendix 1 of the PUAR nentions that calibration factors relating pre-dicted to actual pressures and predicted to actual frecuencies vere P
c obtained by comparing OBUBS02 calculated values with the same quanti-ties measured in the four in-plant tests. This appendix further
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states that verification of the computer model led to a further cali-bration factor for the column loads.
Provide more details on how the calibration factors relating OBUBS and the in-plant tests were ob-tained, especially how the Vermont Yankee method conforms to the model calibration guidelines of the Acceptance Criteria (AC section 2.13.9.2).
Provide information on the actual forcing function used including amplitudes, frecuency content and pressure wave forms. Were separate calibration factors obtained for subsequent actuations? Also provide more detail on the calibration factor for column loads and ex-plain why it is invariant over the frequency range of the loading.
ITP4 7:
PUAR section 4.2, AC section 2.10 The static load magnitude imposed on the vent header deflector in the analysis described in the PUAR seems appropriate if Figure 4.3.9-1 in the PULD accurately shows the initial inpact pressure spike.
Does this figure show the correct impact magnitude or should it be modified as per paragraph 1.
of section 2.10.1 of the Acceptance Criteria?
ITei 8:
PUAR section 4.3.2, AC section 2.'12.2 Regarding the downcomer lateral chugging loads: What is the fenda-mantal tied.down:cter.frecuency? ~What was the, corresponding dynamic load factor? What was the resultant static ecuivalent load used in the stress analysis of the downcaner?
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ITEM 9:
PUAR section 4.3.2, AC section 2.12.1 For synchronized multiple downcomer lateral chugging loads, the Accep-tance Criteria Specification is based on an exceedance probability for 10-4 per LOCA.
The PUAR shows that two load cases were considered for multiple lateral loads. Why were only two load cases necessary and what static loads were applied? To what exceedance probability did these load magnitudes correspond?
ITEM 10: PUAR section 4.3.1.1, AC section 2.6.2 In the calculation of stresses in the downcomers resulting from pool swell water impact, was the virtual nass of water near the downcomer accounted for, and was the 8 psid pressure called for in the Accep-tance Criteria applied over the bottom 50* of the angled portion of the downcomer?
ITEM 11: PUAR section 4.3, AC section 2.14 Were the LOCA bubble drag loads calculated according to Acceptance Criteria specifications as given in section 2.14.2 of the AC7 ITEM 12: PUAR section 5.2 Many of the ring girder loads for Vermont Yankee were analyzed using a computer model constructed for another Mark I plant of "similar" di-mensions. What is the other plant? What are the dimensions of the ring girder and surrounding shell structure of this other plant? Are attachments to the ring girder similar? Were the loads used on this model the Verment Yankee loads or the loads fren the other plant?
ITDi 13:
PUAR section 5.3.2, AC section 2.14 Calculation of ring girder drag loads were not in accordance with the Acceptance Criteria.
Therefore provide the details of a submerged structure load calculation for a given segment the rina girder.
Include numerical values of a VT/D calculation, as well as scurce strength, as a function of frecuency.
In addition, provide the ac-celeration volume, drag coefficient, interference effect nultiplier and pertinent geometric parameters and configuration used in the calculation.
ITEM 14:
PVAR section 5.3.2, AC section 2.14.5 The PUAR states that FSI effects are accounted for in the submerged structure loadings. Additional detail is needed on how this was done.
Is the criteria for including FSI effects the same as that stated in the AC7 How were the FSI loadings obtained?
Is the boundary accele-ration added to the local fluid acceleration as sugcested in the AC or has another method been used?
ITEM 15:
PUAR section 7.1.3 The PUAR states that the catwalk structure stresses were computed without the catwalk grating.
Does this mean that the grating is norm-ally absent and will only be put in place when the catwalk is used?
If the grating is always in place, by what anount will it raise cat-walk stresses?
ITEM 16:
PUAR section 8.1, AC section 2.13.8, NUREG-0783 section 5.1 The use of a loca! tenperature of 210* in the equation for mass flux rate 42 #m/sec-ft2 on p. 105 of the PUAR seems to be based on a misinterpretation of the guidelines in NUREG-0783.
In order to get to 1
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5 210*, the quencher submergence must be'at least 14 ft (14 ft of water corresponds to a total pressure of about 20.8 psi, so the saturation temperature is 230'.
Subtract the 20' subcooling and one gets 210').
Although no exact submergence of the quencher for Vermont Yankee can be found in the PUAR, it can't be much more than 7 ft.
Therefore, the saturation temperature minus the 20' subcooling at that submergence will be not much above 200*F. Also, Fig. 8-1 does not clearly answer the cuestion of maxinum bulk pool temperature. What is the naximum bulk pool temperature reached durino any of the transients recuired fee consideration and does it conform to the Acceotance Criteria in light of the above comments?
ITEM 17: AC section 2.1 Section 2.1 of the Acceptance Criteria states that "as part of the PUA each licensee shall specify procedures (including the primary systen parameters monitored) by which the operator will identify the SBA, to assure manual operation of the ADS within the specified time ceriod.
Longer time periods may be assumed fo" the SBA in any see-cific PUA, provided (1) the chugging load duration is correspondingly increased..(2).the procedures to assure. manual cperation within the, assuned tine period are specified, and (3) the potential for thermal stratification and asymmetry effects are addressed in the PUA."
The PUAR does not specifically address the above requirement.
Cl a r-ification is needed.
ITEM 18:
PUAR section 4.3.1, AC section 2.6 Provide pool swell impact and drag transient histories used in the calculation of pool swell loads on the main vent, vent header and downcomers.
Provide enough detail to show how the load histories ap-plied at the nodal points of the shell and beam models comply with the Acceptance Criteria.
ITEM 19:
PCAR section.A1, AC section 2.14.3 and 2.14.4 Use of SRY test data for submerged structure drag loads represents an exception to the Acceptance Criteria. The method described in Appen-dix 1 of the PUAR needs to be reviewed further, however, several prob-lems which arise immediately are listed here:
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O (1) The frequency content of different SRV load cases have been shown by experience 'to be different - multiple valve actuations show a lower frequency content than single valve tests. The PUAR nethod does not address this problen. Arguments in the PUAR that
" structures involved are responding to a fairly uniform random field" are unconvincing.
(2) Using a uniformly distributed pressure as a way to obtain static loads giving strains equivalent to those measured can lead to nonconservatisms when Figure Al-5 is used to predict static drag pressures on structures whose geometry is different from those on which the strains were measured.
(3) Scaling the static drag pressure upward from test conditions to nore severe SRV cases by the ratic of calculated shell pressures is an oversimplification which uses a global paraneter to scale local effects. The local pressure on a submerged object due to simultaneous multiple SRV actuation can ratio very differently from the torus shell pressures, depending on the phasing and location of the quencher relative to the object.
JTDt 20:
PUAR section 6.0, AC sections 2.14.3 and 2.14.4 The PUAR analysis. of.the_ T-quencher, its support and the subnerged' portion of the SRV line does not mention quencher water jet or bubble drag loads on these structures. Where have these loads been included or why have they been ignored?
IT'Di 21:
Provide the loads that were used in the torus attached piping.
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