ML20118A231

Forwards Responses to Request for Addl Info as Result of TS Change Request 198 Re Drywell Design Pressure Change, Consisting of Comparisons of Methods Used in Peak Drywell Pressure Analyses & of Contempt Computer Code Versions

ML20118A231
Person / Time
Site:	Oyster Creek
Issue date:	08/19/1992
From:	Devine J GENERAL PUBLIC UTILITIES CORP.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
5000-92-3051, C321-92-2214, NUDOCS 9208260168
Download: ML20118A231 (16)

Text

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GPU Nuclear Corporation yg me Nuclear on. v et e ne e e Parsippany, New Jersey 07054 201 316-7000 TELEX 136 482 WnK(5 Direct Dial Number August 19, 1992 5000-92-3051 C321-92-2214 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, D.C. 20555 Gentlemen:

Subject:

Oyster Creek t'aclear Generating Station (0CNGS)

Docket No. 50-219 L Facility Operating License No. DPR-16 L Oyster Creek Containment Peak Pressure Analysis i

As a result of the NRC staff review of Technical Specification Change Request (TSCR) No.198, the staff verbally requested some additional information. In response are Attach tats I and 11 which provide the requested comparisons of methods and computer codes used to support the TSCR proposed drywell design pressure change.

Attachment I compares the methods used in the recent Oyster Creek peak drywell pressure analyses with the NRC Standard Review Plan, Section 6.2.1.1.0, Rev. 6,

" Pressure-Suppression Type BWR Containments".

Attachment 11 provides a comparison of CONTEMPT computer code versions LT-26 and El-28C. Version El-28C was used to evaluate the Oyster Creek peak drywell design pressure change. The attachment includes a source code review and a comparison of El-28C results with NUREG/CR-1564, " Comparison of CONTEMPT-LT Containment Code Calculations with Marviken, Loft and Battelle-Frankfurt Blowdown Tests".

l If you have any questions or comments on this submittal or require additional l

further assistance, please contact Mr. Michael Laggart, Manager, Corporate Nuclear Licensing at (201) 316-7968.

m

. L '!ery truly yours,

. o ev a lSo ss' CM{LEC J. C. Devine, Jr.

! m.c Vice Presic'ent and Director

$8 Technical Functions ,

'on

' i4 JCD/RZ:lga l& reo cc: Administrator, Region I Senior Resident inspector 250079 s

' " ' ' 0yster Creek NRC Project Manager

/

GPU Nuclear Corporabon is a subseay of Generm Pubhc Um os Corporabon f

l .

ATTACHMiNT 1 SBP COMPARISON FOR THE OYSTER CRLfK_ PEAK DRYWEtt PRE ($URE ANALYSES Section 6.2.1.1.C Pressure-Suppression Type CWR Cont;'.nments Rev. 6 - August 1984

1. Areas of Review for Mark 1. 11 and 111 pressure-suppressior, type boiling water reactor (BWR) plant containments, the CSB review covers the following areas:

1. The temperature and pressure conditions in the drywell and wetwell _

due to a spectrum (including break size and location) of postulated loss-of-coolant accidents.

desnnnig The analyses which constitute the drywell lesign pressure change evaluation are specifically concerned with peak drywell pressure. The bounding break for this parameter is stated in the FSAR to be the double-ended failure of a retirculation loop. Furthermore, previous analyses performed by GPUN have demonstrated that smaller breaks at a variety of locations do not result in peak drywell pressures greater than the recirculation loop break.

2. The differential pressure across the operating deck for a spectrum -

of loss-of-coolant accidents including break size and location (Mark 11 containments only).

Rc3ponse This area is not applicable since Oyster Creek's containment is a Mark I design.

3. Suppression pool dynamic effects during a loss-of-coolant accident or following the actuation of one or more reactor coolant system safety / relief valves, including vent clearing, vent interactions, pool swell, pool stratification and dynamic symmetrical and smnm

A g asymmetrical loads on suppression pool and other containment structures.

Response These issues were all evaluated in a separate analysis (Mark 1 Containment Program). The drywell design pressure analyses results we:e not used to evaluate the dynamic structural issues. The containment pressure response was, i however, compared with that useo to assess the structural issues in order to demonstrate that the original work .

remained bounding.

4. The consequences of a loss-of-coolant accident occurring within the containment (wetwell); i.e., outside the drywell (Mark Ill containments only).

- Epsngnig This area is not applicable since Oyster Creek's containment is a Mark I design.

5. LThe capability of the containment to withstand the effects of steam bypassing the suppression pool.

Responsg Suppression pool bypass was not considered in the original Tech Spec change submittal. For large break LOCAs, the pressure response is not expected to change significantly as a result of suppression pool bypass. However, as part of this SRP evaluation,_we recalculated the containment response to the DBA LOCA using the same CONTEMPT-El input and included the Tech Spec bypass leakage area of 10.5 inz,

-The resulting peak drywell pressure was essentially unchanged.

'In addition, Oyster Creek performs -a quarterly surveillance on' bypass leakage. The surveillance restricts the allowable ,

bypass to 3.14 inz (2" dia. orifice). plant experience-with sneptm

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f this surveillance is that the observed bypass is well below the 3.14 in zacceptance values.

, 6. The external pressure capability of the drywell and wetwell, and systems that may be provided to limit external pressures.

Fesponse The drywell design pressure change has no impact on the containment's external pressure capability. Internal pressure requirements are the sole focus of the evaluation. '

7. The effectiveness of static and active heat removal mechanisms.

Reiponse The peak drywall pressure analysis did not take credit for any heat removal mechanisms. Both the containment structure's heat capacity and the containment spray atmnspheric cooling capability were excluded from consideration.

8. The pressure conditions within subcompartments and acting on system components and supports due to high energy line breaks,

-e.g., the sacrificial shield structure.

Ecsponse The drywell design pressure evaluation is not a subcompartment analysis. The analysis is intended to evaluate the containment atmospheric pressure. The drywell design pressure change will not affect the containment's ability to withstand impingement forces caused by fluid from l a pipe break, h 9. The range and accuracy of instrumentation that is provided to monitor and record containment conditions during and'following an accident.

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4 e I Response The drywell design pressure change has no impact upon the range and accuracy of instrumentation provided to monitor and record containment conditions The containment accident conditions fall within the range of said instrumentation. j In addition, the instrumentation's environmental conditions are based upon a bounding steam line break.

10. The suppression pool temperature limit during reactor coolant system safety / relief valve operation, including the events considered in anelyzing suppression pool temperature response, assumptions used for the analyses, and suppression pool temperature monitoring system.

Rain.qnSn The torus pool temperature response to a DB LOCA is dependt n Jpon the integrated blowdown mass and energy and the decay heat removed by core spray. The pri. nary concern regarding the torus pool temperature response is the peak pool temperature. It is this temperatur. which will be used to evaluate the core spray pump NPSH available.

Neither the integrated blowdown mass and energy nor the decay heat removed by the core spray is changed as a result of this-evaluation. Both of these are dependent upon the initial conditions of the reactor and not the rate of blowdown. The only significant. change to the large break LOCA analysis is the rate at which the mass and energy exits the reactor vessel in the first 30 seconds.' This will nnt affect the peak torus pool temperature since the amount of l_

mass and energy which-enters the pool has not changed.

Moreover, the peak torus-pool temperature occurs long after the. blowdown is completed. Therefore, .no change to the

-torus pool temperature response-presently in the FSAR occurs -

a: a result af this evaluition.

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4 It is important to note that the two cases used to evaluate the peak drywell pressure employed a direct multiplier on the blowdown instead of a break discharge coefficient multiplier. This is a conservative assumption used to evaluate the drywell pressure response. It has the affect of artificially increasing the integrated reactor vessel blowdown r.iass and energy. The use of any multiplier on the l

blowdown is inappropriate when evaluating the torus pool I temperature response.

\

11. The reactor coolant system 1,afety/ relief valve in plant e.onfirmatory test program.

Response The drywell design pressure change will not affect reactor coolant system safety / relief valve operation er in-plant confirmatory tests.

12. The evaluation of anelytical models used for containment analysis.

Entpoms The containment model used (CONTEMPT EI) was compared with the GE containment model M3CPT. This comparison

-demonstrated reasonable. agreement between the codes.

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ATTACHMF.NT 2 EMIEMPT VERSIONS El AND LT DISCUSSI.QN OF DIFFERENCES In order to assess the difference between the two versions of the code, a review of the El 28C source code was conducted, and a comparison of El 28C results and NUREG/CR-1564 analysis results with l_T ?6 were perfo.med. The source code review revealed the following:

A. Spurce Code Revigw

a. Input output changes to El 28C

- Condensed heat structure table printout E Additional parameter plot files

- Summary table of peak compartment conditions

- Improvad plot capability using RETRAN pict routines

b. Various error corrections that had previously resulted in code execution problems

- Vent clearing Integer overflow

c. Code enhancements incorporated in El 28C

- Generalized mass / energy addition /removel to/from any compartment Numerous additional heat structure wall heat transfer correlation options were added while preserving original options

- Automatic time step control logir

d. Machine dependent cnanges Changes necessary tn run under IBM mainframe (N05/BE)

Changes to run on an IBM /PC (all FORTRAN version)

None of these changes will have an affect on the peak pressure analysis owwnw Page 1 of 10

B. HUREG/CR-1564* Comnarison The NUREG evaluates CONTEMPT-LT 26 calculations of the Marviken, LOFT and Hatte11e-Frankfurt blowdown tests.

A number of sensitivity studics on CONTEMPT-LT options were performed in NOREG/CR-1564. These optior.; are the same as those available in the El ,

version of the CONTEMP1 code. A complete list is provided in Table XI of i NUREG/CR-1564. In order to benchmark the El version, the base case (Case 1)  ;

of Harviken Blowdown 14 was run using CONTEMPT El-280. This is the version of CONTEMPT used to evaluate the Oyster Creek peak drywell design pressure change. The teble ar.d figures which follow compare CONTEMPT-LT and El versions for Marviken Blowdown 14. '

As can be seen in the table and in Figures 1 and 2, the calculated drywell and wetwell pressures for the two code versions agree extremely well. This confirms that no changes were made to [I 28C which would impact the Oyster Creek peak pressure analysis in a non-conservative manner. A comparison of all of the other key parameters shown in the attached table and in Figures 3 through 6 are similarly in excellent agreement between both code versions -

a i

NUREG/CR-1564, ' Comparison of CONTEMPT-LT Containment Code Calculations with Marviken, LOFT and Battelle-Frankfurt Blowdown Tests'.

Page 2 of 10  ;

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4 4 MARVIKEN BLOWDOWN 14 l

[.ASE 1 - HUREQ/CR-1564  ;

2 i

t CONTEMPT-LT CONTEMPT-El MARVIKEh 1

Drywell Pressure (psia)* 0 et 14.79 14.79 14.79 (Refer to Figure 1) I sec 23.47 23.47 20.6 10 sec 35.23 35.02 31.47 78 sec 40.25 41.i' 44.09 100 sec 36.39 36.65 39.02 180 sec 36.06 36.32 38.87 Wetwell Pressure (psia) O sec 14.65 14.65 14.65 (Refer to Figure 2) , I sec 14.65 14.65 14.65 10 sec 27.75 27.49 23.79 1 78 sec 32.47 32.46 34.08 I

100 sec 32.47 32.46 34.23 180 sec 32.48 32.47 34.23 DW to WW AP (psi)* O sec 0.14 0.14 0.14 (Refer to Figure 3) I sec 8,82 8.82 5.95 -

10 sec 7.48 8.33 7.69 78 sec 7.78 8.81 - l'0. 01 100.sec 3.92 4.19 ,

4.79 180 sec 3.58 3.85 ,4.64 Vent Flow Rates (1bm/s) 0 sec 0 0 0 (Refer to Figure 4) I scc 0 0 0 10 sec 858 866.2 464 L 78 sec 961 960.2 1022

>100 sec * **

• - Marviken breakroom values listed. ,

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• • Oscillating conditions after about 100 sec, i-l owsm>ws .

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liARVIKEN BLOWDOWN 14 CASE 1 - NUREG/CR-1561 (Cont'd)

(DNTEMPT-LT CON 1EMPT-El MARVIKEN Drywell Atmosphere Temp (*F)* 0 sec 112.3 112.3 116.6 (Refer to figure 5) 1 sec 178.71 178.71 222.8 10 set 251.31 251.93 251.6 78 sec 267.56 269.14 268.79 100 sec 261.59 262.0 262.4 180 sec 261.05 261.47 263.3 Wetwell Pool Temp (*F) O sec 114.40 114.4 114.4 l 1 sec 114.4 114.4 114.4 10 sec 118.91 118.8 115.97 l 78 sec 168.50 168.12 153.21 100 sec 173.22 172.91 160.7 180 sec 184.49 184.17 170.20 Wetwell Atmosphere Temp (*F) O sec 89.2 89.2 89.2 P

(Refer to Figure 6) I sec 89.2 89.2 89.2 10 sec 101.39 101.27 109.22 78 sec 104.55 104.62 137.30 100 sec 104.57 104.63 140.72 180 sec 104.62 104.68 137.84 Peak DW Pressure (psia)* 40.71 41.93 44.09 Peak WW Pressure-(psia) 32.48 32.47 34.23 Max DW to WW Press Diff (psi)* 10.15 10.94 11.17__

Initial,_ Vent Clearing Time (s) 1.0836 1.0836 1.2 l Peak Vent Flow Rate (1bm/s)- 1067 1054 -1022

• Marviken breakroom values listed.

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Marviken Blowdown 14 Drywell Pressure (psia) 50.0 . ., ., ...

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Fig. C-3. )urviken B1cwdawn 14 drywell pressures.

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Marviken Blowdown 14 Wetwell Pressure (psia) 50.0 ,, . ., . -. -

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Pig. C-6. nsrvi. ken Blo<bm 14 wetwel.1 autospheric pressures. 1 FIGURE 2 OW.N%PNH Page 6 of 10

Contornpt-EI28c 20 PDW - PWW 3

0 0.1 TIME 1 1000 3

(sec)

Marviken Blowdown 14 Contain:sont Pressure Difference (psi)

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Fig. C-8. Marviken P . &wn 14 preesure dif f erences between drywell and wetell.

FIGURE 3 ow mw i Page 7 of 10 L .__ ___ _____

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Marviken Blowdown 14 Vent Flow Rate (lb/sec) 1600.0 . .. , ...

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FIGURE 4

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• Contempt-EI28c 400 7

TDW 3'

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(sec)

Marviken Blowdown 14 Drywell Atmosphere Temperature 400.0 , , , , , , , , , , , , , , , , . . . . , , ,, ,

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Fig. C-12. turviken Blen 1; drywel.1 *tmospheric tenperatures.

FIGURE 5 OW-N8C PNH Page 9 of 10

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Marviken Blowdown 14 Wetwell Atmosphere Temperature l

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