ML20138E360

SE of Topical Rept NTH-TR-01, Retran Model Qualification, Decrease of Heat Removal by Secondary Sys. NRC Discontinued Review

ML20138E360
Person / Time
Site:	Turkey Point, Saint Lucie
Issue date:	04/19/1994
From:	FLORIDA POWER & LIGHT CO.
To:
Shared Package
ML20136C539	List: IR 05000335/1994009 IR 05000335/1996002 L-96-227, Forwards LER 96-S01 Re Tampering W/Key Switches on Hot Shutdown Control Panels ML20136D672 ML20136D791 ML20136D807 ML20136D826 ML20136E425 ML20136E584 ML20136E630 ML20136E877 ML20136F036 ML20136F141 ML20136F193 ML20136F245 ML20136F260 ML20136F319 ML20136F524 ML20136F542 ML20136F548 ML20136F555 ML20136F561 ML20136F567 ML20136F575 ML20136F583 ML20136F590 ML20136F595 ML20136F604 ML20136F608 ML20136F623 ML20136F647 ML20136G031 ML20136G074 ML20136G089 ML20136G115 ML20136G254 ML20136G294 ML20137D404 ML20137D421 ML20137D436 ML20137D457 ML20137D508 ML20137D737 ML20137D744 ML20137D777 ML20137D818 ML20137D837 ML20138D105 ML20138D113 ML20138D124 ... further results
References
FOIA-96-485 NUDOCS 9404260382
Download: ML20138E360 (2)

Text

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ENCLOSURE 1 l

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NUCLEAR REGULATORY COMMISSION i

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jj SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGUL NTH-TR-01 "RETRAN MODEL QUALIFICATION: DECREASE OF HEAT RE 1

e i i BY THE SECONDARY SYSTEM" FLORIDA POWER AND LIGHT i

1 INTRODUCTION i

By letter dated October 2,1989, Florida Power and Light, the licensee for the Turkey Point Units 3 and 4 and the St. Lucie Units 1 and 2 nuclear power plants, submitted the topical report NTH-TR-01, "RETRAN Model Qualification, i.

Decrease in Heat Removal by the Secondary System" for staff review.

j Additional information was submitted on May 2, 1991, May 19, 1992, and September 25, 1993.

In NTH-TR-01, the licensee presented comparisons of 3

RETRAN analyses of plant operational transient data in order to demonstrate j

the adequacy of the RETRAN model for both the Turkey Point and the St. Lucie plants.

The licensee developed one model for both Turkey Point Units and one 1

_ each for the St. Lucie plants.

Two sets of benchmark analyses against i

operational transient data involving decreased heat removal by the secondary i

system were reported.

i Modeling features were also part of the topical report.

The licensee's objective was to obtain NRC approval for their use of RETRAN-02 i

in licensing actions involving transient events with decreased secondary heat removal.

In Generic Letter (GL) 83-11, the staff took the position that each-licensee must demonstrate technical competence and develop its own analytical capability to perform plant transient estimates.

The staff review of NTH-TR-

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01 and related information sought to establish that the licensee met the recommendations in GL 83-11.

j 2 EVALUATION Review of the submitted information, including responses to staff requests for ii{!

additional information, indicate that the licensee has not justified its steam generator nodalization for either Turkey Point or St. Lucie.

The

! i licensee developed a two-loop nodalization model for each plant site including i

multinode steam generator models.

However, no analytical justification or demonstration of the accuracy or sufficiency of such models were presented, though the licensee re i

nodalization changes. ported that they compared the results of the The non-equilibrium option was used in the upper dossicomer and the bubble rise model in the separator volume but no justification was presented.

For both models, the pressurizer was modeled as a single node non-equilibrium 4

volume.

Heat transfer between the pressurizer wall and the liquid was ignored,'without justification.

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i The following transients were considered:

loss of external load, turbine trip, loss of condenser vacuum, main steam valve closure, steam pressure regulator failure, loss of non-emergency AC power to station auxiliaries, loss of normal feedwater and feedwater line break.

Comparisons to plant data were given which, in most cases, did not justify the use of the proposed models.

For instance, comparison of the RETRAN results and the FSAR analysis for the loss of non-emergency AC power to pressurizer water volume is 280 ft}he station auxiliaries indicated that the less than computed in the FSAR and the predicted timing of this pressurizer water volume was 720 seconds into the transient, while it was 3720 seconds in the FSAR prediction. The differences were attributed by the licensee to Code differences but no effort was made to assure accuracy or convergence of the proposed RETRAN model.

Similarly, in the steam generator level computation, the licensee did not present a convincing case to demonstrate that the requirements of GL 83-11 were satisfied.

The staff accepts the single node steam generator nodalization for transients with decrease in heat removal by the secondary system for which: depletion of the secondary side mass inventory is not expected, heat transfer degradation is not expected due to inventory loss and accurate tracking of the secondary side mixture is not required for actuation of safety functions.

For the staff to accept the NTH-TR-01 in its entirety for licensing applications, Florida Power and Light should justify:

(1) the steam generator nodalization for both Turkey Point and St. Lucie and-(2) the RETRAN models for the individual plants regarding: steam generator nodalization, steam generator mixture level computation algorithm, and the use of the slip model.

3 CONCLUSION This issue has been under NRC review for over 4 years.

Repeated requests for information to complete the review yielded no new information; therefore, the staff has discontinued its review. The staff will consider further review when substantive information has been submitted on steam generator nodalization and steam generator water level, as described above and in the 4

attached technical evaluation report.

Principal Contributor:

L. Lois Date:

i 3