ML19323C367

Exposure Sensitivity Study for ENC XN-1 Reload Fuel at Prairie Island Unit 1 Using ENC WREM-IIA PWR Evaluation Model, Revision 1,nonproprietary Version

ML19323C367
Person / Time
Site:	Prairie Island
Issue date:	04/11/1980
From:	Cooke G, Morgan J, Sofer G SIEMENS POWER CORP. (FORMERLY SIEMENS NUCLEAR POWER
To:
Shared Package
ML19323C360	List: ML19323C359 ML19323C362 ML19323C365 ML19323C367
References
XN-NF-79-018, XN-NF-79-018-R01, XN-NF-79-18-R1, NUDOCS 8005150411
Download: ML19323C367 (20)

Text

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e XN-NF-79-18(NP)

Revision 1 04/11/80 EXPOSURE SENSITIVITY STUDY FOR ENC XN-1 RELOAD FUEL AT PRAIRIE ISLAND UNIT 1 USING THE ENC WREM-IIA PWR EVALUATION MODEL l

Prepared By:

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9[lfl0 G. C. Cooke, Manager Fuel Response Analysis Approved:

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C%W J.6N. Morgan, MaMger Licensing & Safety Engineering Approved:

k t % /p, G. A. l60fer, Manager Nuc ear Fuels Engineering E(ON NUCLEAR COMPANY,Inc.

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NUCLEAR REGULATORY COMMISSION DISCLAIMER IMPORTANT NOTICE REGARDING CONTENTS AND USE OF THIS DOCUMENT PLEASE READ CAREFULLY This technical report was eferived through research and development programs sponsored by Exxon Nuclear Company, Inc. it is being sub-mitted by Exxon Nuclear to the USNRC as part of a technical contri-bution to facilitate safety analyses by licensees of the USNRC which utilize Exxon Nuclear fabricated reload fuel or other technical services provided by Exxon Nuclear for liaht water power reactors and it is true and correct to the best of Exxon Nuclear's knowledge, information, and belief. The information contained herein may be used by the USNRC in its review of this report, and by licensees or applicants before the USNRC which are customers of Exxon Nuclear in their demonstration of compliance with the USNRC's regulations.

Without derogating from the foregoing, neither Exxon Nuclear nor any person acting on its behalf:

A.

Makes any warranty, express or implied, with respect to the accuracy, completeness, or usefulness of the infor-mation contained in this document, or that the use of any information, apparatus, method, or process disclosed j

in this document will not infringe pr;vately owned rights; or B.

Assumes any liabilities with respect to the use of, or for derrages resulting from the use of, any information, ap-paratus, method, or process disclosed in this document.

XN-NF-F00, 766

i i

XN-NF-79-18(NP)

Revision 1 TABLE OF CONTENTS Section Page_

l.0 SUP9tARY.......................

1 2.0 MODEL AND ASSUMPTIONS................

2 3.0 ANALYSIS RESULTS 4

4.0 REFERENCES

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11 XN-NF-79-18(NP)

Revision 1 LIST OF TABLES Table g

i Prait le Island Unit 1 ECCS Analysis Parameters......

6 2

Prairie Island Unit 1 Pin Pressure Uncertainty......

7 3

Prairie Island Unit i Exposure Sensitivity Results....

9 LIST OF FIGURES Figure Page 1

Prairie Island Unit 1, F Versus Peak Pellet Burnup 10 q

2 Clad Temperature During Heatup For Beginning-of-Life...

11 3

Clad Temperature During Heatup for 3380 MWD /MTM.....

12 4

Clad Temperature During Heatup for 29750 MWD /MTM.....

13 5

Clad Temperature During Heatup for End-of-Life......

14

' XN-NF-79-18(NP)

Revision 1 1.0 SUPMARY Th.

provides the results of the ECCS exposure sensitivity study for Exxon i uclear Company (ENC) XN-1 reload fuel at Prairie Island Unit I.

The results of the ENC LOCA analysis for Prairie Island Unit I and identifict.*. ion of the 0.4 DECLG pipe break as the limiting accident have been reportad in XN-NF-78-46(I)

The analysis presented in Reference 1 was for *e ENC XN-1 reload fuel at beginning-of-life (BOL) without consideration of uncertainties in fuel rod interna", pressure.

This report provides detailed fuel analyses for the limiting break (I) with consideration of pin internal pressure uncertainties as a function of fuel rod exposure.

Figure 1 provides the allowable total peaking, F, versus peak pellet q

burnup determined by the analyses. The allowable Fg versus exposure curve for the Prairie Island Unit I fuel design is a constant F value of g

2.21 (14.03 kw/ft total; 13.66 kw/ft heat release in the fuel) to a peak pellet burnup of At higher exposures, up to a maximum exposure of The reduction of F is necessary to offset the adverse effects of fission g

gas release at high burnup on predicted clad rupture and flow blockage in the postulated LOCA. The reduction in Fg occurs at a sufficiently high burnup that it is not anticipated to be restrictive for projected core operation.

4

. XN-NF-79-18(NP).

Revision 1 2.0 MODEL AND ASSUMPTIONS The present ECCS heatup analysis is an extension of the break spectrum analyses reported in Reference 1.

These analyses provide for the effect of fuel rod exposure on the Loss-of-Coolant-Accident (LOCA) for the 0.4 DECLG pipe break at Prairie Island Unit I, the limiting break (I)

The analyses also include consideration of uncertainties in fuel rod internal pressure, and hence, rupture pressure in accordance with the models de-tailed in References 2, 3, and 4 and as approved in Reference 5.

The NRC enhanced (high burnup) fission gas release model(6) has been incorporated into the calculations. The analysis is in accordance with ENC's WREM-IIA PWR Evaluation Model(7).

The computer models used in performing the analysis are the RELAP4-EM/

HOT CHANNEL and T00DEE2/H0T R0D models. The impact of the Swedish updates on the steam cooling model in T00DEE2 have been included in the heatup results reported here. These updates have been detailed in Reference 8.

In the course of making the Swedish updates, other coding modifications in the ENC T00DEE2 steam cooling model were identified and incorporated.

These code updates are also described in Reference 8.

A sensitivity calculation showed the net effect of all T00DEE2 code changes to be a PCT increase of less than 8F.

The present calculations also include two minor input changes that were made to the base analysis reported in Reference 1.

First, in the HOT CHANNEL calculations, the total peaking factor was reduced from 2.24 to 2.21 to be consistent with the final T00DEE2 heatuo results. The corresponding PCT impact is a reduction of 14F. Secondly, the delay times for containment spray and fan coolers were changed to be consistent I) with the FSAR for Prairie Island Unit I The impact of this change

. XN-NF-79-18(NP)

Revision 1 was a slight increase in reflood rate and a reduction in PCT of 19F.

Table 1 summarizes the key parameters of the analysis. The core boundary conditions for the BOL and exposed fuel HOT CHANNEL calculations are from the limiting break primary system blowdown calculation reported i

in Reference 1.

The final heatup calculation results reported herein for each exposure case reflect all the code updates described in the Appendix.

Finally, the present analysis results include the effects of the interim UPI model discussed in Reference 1.

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. Xft-flF-79-18(flP)

Revision 1 3.0 ANALYSIS RESULTS Table 2 provides the results of the fuel rod int'rnal pressure uncertainty analysis. The net uncertainty bound for each exposure case is incorporated into the final T00DEE2 heatup calculations and the re-sults of these final T000EE2 heatup calculations are given in Table 3.

The F value in each case corresponds to the limit curve given in q

Figure 1.

The IF increase associated with the interim UPI model is in-cluded in the PCT results reported in Table 3.

This model and its associated PCT impact was discussed in Reference 1.

Table 3 shows that a margin exists between the calculated PCT and the limiting PCT of 2200*F in all' Cases.

For the BOL exposure case, it can be seen (Table 3) that with the upper-bound pin pressure uncertainty taken into account, the flow blockage is This blockage versus the blockage when pin pressure un-certainties are not considered, results in a PCT increase of 3F (i.e.

from 2173 F to 2176 F).

The 3380 MWD /MTM peak pellet burnup case is the exposure for which the bounding rupture pressure is a minimum. The occurence of this minimum in rupture pressure is associated with fuel densi-fication and the uncertainty corresponding to maximum densification.

The exposure is sufficiently low that the potentially offsetting effects of fission gas release and fuel swelling are insignificant.

In this case, the limiting (lower) bound on rupture pressure is This rupture j

pressure results in a subchannel flow blockage of The corresponding PCT is 2129 F.

The reduction in PCT relative to BOL, despite higher blockage,is a consequence of the reduction in initial stored energy that occurs with fuel exposure. Figure 3 provides the corresponding heatup transient for the 3380 MWD /MTM exposure case.

l

. XN-NF-79-18(NP)

Revision 1 At high exposure, the effects of fuel swelling and fission gas re-lease result in a marked increase in rupture pressure. This is particularly true after 20,000 MWD /MTM when fission gas release includes a burnup en-hancement factor. The corresponding increases in calculated subchannel flow blockage become so large that after F must be q

reduced to avoid exceeding 2200 F PCT. An example is the exposure case, where F has the value of The associated flow g

blockage is The corresponding heatup transient is shown in Figure 4.

The calculated PCT is 2148'F.

Figure 5 provides the heatup transient for the end-of-life exposure case where F has the value of where g

the calcolated PCT is 2193 F.

. XN-NF-79-18(NP)

Revision 1 TABLE 1 Prairie Island Unit 1 ECCS Analysis Parameters Reactor Power, MWt 1683.0 (102%)

Reactor Pressure, psia 2250.

Heat Release in Fuel 97.4%

Nominal Hot Assembly Radial Peaking, F 1.4904 r

Nominal Hot Rod Local Peaking, F 1.04 j

Nominal Engineering Factor, F 1.03 e

Nominal Axial Peaking, F 1.3843 a

Nominal Total Peaking, F

=F xF x F, x F, 2.21 q

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Limiting Break-0.4 DECLG Axial Power Peak Location, X/L 0.5 m

d TABLE 2 Prairie fsland Unit 1 Pin. Pressure Uncertainty Beginning of Life to 27,000 MWD /MTM Peak Pellet Burnup e Peak Pellet Burnuo, MWD /MTM 3380 16500 27000 4

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Prairie fsland Unit 1 Pin Pressure Uncertainty 29,750 i1WD/MTM to 41,850 MWD /MTM Peak Pellet Burnup e Peak Pellet Burnuo, MWD /MTM 29,750 36,350 41,850 I

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TABLE 3 Prairie Island Unit 1 Exposure Sensitivity Results Peak Pellet Burnup (GWD/MTM)

BOL 3.38 16.5 27.0 29.75 36.35 41.85 Total Peaking, Fq Peak Clad Temperature (PCT), UF 2176 2129 2044 2161 2148 2178 2193 Max. Local Zr/H O - Reaction, percent 7.0 6.0 5.0 6.0 6.0 7.0 7.0 2

Hot Rod Burst Time, sec 35.0 92.5 69.0 63.0 66.5 92.5 92.5 Hot Rod Burst Location, ft 6.0 7.0 6.75 6.75 6.75

.7.25 7.25 Rupture Pressure, psid Subchannel Flow Blockage, %

Time of PCT, sec PCT Location, ft Max. Zr/H 0 Reaction Location,.ft 2

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. XN.4F-79-18(NP)

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Revision 1 l'

4.0 REFERENCES

1.

Exxon Nuclear Company, ECCS Large Break Spe;trum Analysis For Prairie Island Unit 1 Using ENC WREM-IIA PWR Evaluation

@e_i_,XN-NF-78-46, November 1978.

2.

Exxon Nuclear Company, Flow Blockace and Exposure Sensitivity For D. C. Cook Unit 1 Reload Fuel t sing ENC WREM-II Model, l

XN-76-51, Supplement 1, January 1977.

3.

Exxon Nuclear Company, Flow Blockage and Exposure Sensitivity Study For D. C. Cook Unit 1 Reload Fuel using ENC WREM-II Model, XN-76-51, Supplement 2, January 1978.

4.

Exxon Nuclear Company, Flow Blockage and Exposure Sensitivity For D. C. Cook Unit 1 Reload Fuel Using ENC WREM-II Model, XN-NF-76-51 Supplement 3 [NP], April 1978.

5.

Supplement 1 to Safety Evaluation Report on the Exxon Nuclear Company WREM-Based Generic PWR-ECCS Evaluation Model Updste ENC-WREM-II for Conformance to Requirements of Appendix K to 10 CFR 50 By the Office of Nuclear Reactor Regulation, May 1978.

6.

Letter' D. F. Ross to W. S. Nechodom, Fission Gas Release From Fuel at High Burnup, January 1978.

l 7.

Exxon Nuclear Company, Exxon Nuclear Com)any WREM-Based Generic PWR ECCS Evaluation Model Update ENC WREM-IIA, XN-NF-78-30, August 1978.

8.

Letter, G. F. Owsley (ENC) to D. F. Ross (USNRC), Update of T000EE2 Per Recommendations from NRC Staff, April 1,1980.

i 9.

NSP Prairie Island Nuclear Generating Plant Units 1 and 2, Red Wing, Minnesota, Final Safety Analysis Report, Docket Numbers 50-282 and 50-306,1971.

l l

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