ML19220C325
| ML19220C325 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 04/12/1978 |
| From: | Mcgurren H NRC OFFICE OF THE EXECUTIVE LEGAL DIRECTOR (OELD) |
| To: | Johnson W, Rosenthal A, Sharfman J NRC ATOMIC SAFETY & LICENSING APPEAL PANEL (ASLAP) |
| References | |
| NUDOCS 7904300404 | |
| Download: ML19220C325 (5) | |
Text
-.
April 12,1978 5 &,!rd Alan S. Rosenthal, Esq.
Dr. W. Reed Johnson Atomic Safety and Licensing Atomic Safety and Licensing Appe:u Panel Appeal Panel U. S. Nuclear Regulatory Commission U. S. Nuclear Regulatory Commission Washing ton, D. C. 20555 Washington, D. C.
20555 Jerome E. Sharfman, Esq.
Atcmic Safety and Licensing Appeal Panel U. S. Nuclear Regulatory Commission Washington, D. C.
20555 In the Matter of Metropolitan Edison Company, elal.
(Three Mile Island Nuclear Station, Unit 2)
Docket No. 50-320 Gentlemen:
During the course of the Staff's continuing studies of ECCS performance charactenstics, the Staff has identified certain aspects of accumulator delivery which should be considered further. This matter is discussed in the attachment to this letter.
For reasons outlined in the a?.achment, the Staff does not believe that this matter has an adverse effect on this proceeding.
Sincerely, Henry J. McGurren Counsel for NRC Staff Attachment as stated cc: See page 2 7804300'to'{
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Edward Luton, Esq.
Mr. Gustave A. Linenberger Dr. Chancey R. Kepford Karin W. Carter, Eaq.
Gt.orge F. Trowbridge, Esq.
Ms. Judith H. Johnsrud Atomic Safety and Licensing Board Panel Atomic Sciety and Licensing Appeal Panel Docketing and Service Section DISTRIBUTION H. Silver S. Varga J. Norris W. Regan H. McGurren G. Fess S. Treby H. Shapar T. Engelhardt M. Grossman H. Smith ELD Formal File NRC Central File LPDR o,
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'icGurren: dh h$by 4/ d /73 J 4// k78 NRc FORM 313 (9 76) NRCM 02+0 W u.
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h ACCUMULATOR iiLIVERY 1.
Concern:
Actual accumulators mt. deliver ECCS nater to the reactor cochnt nstem faster than is predicted oy some ccmputer programs used to predict ECCS perfor-ance. This cculo mean that sufficient accumulator water would not be available at the time it is needed. Attention was focused on :nis probieri 'then comparisons of accumulator delivery calculations were made between RELAPA (NRC) anc SATAN VI (Westingnouse) as part of the Upper Head Injection (UHI) review. Ccmoarisons to the L')FT experimental data indicated that tne Westingnouse model mient be undarpredicting accumulator delivery ficw water.
The key factors influencing delivery rates are the gas expansion medel and the effective delivery line resistance.
2.
Safety Signi rirwce: There is no specific reference to cur current licensing position.
Each reactor vendor proposed a different model in 1074 for compliance with Accendix K.
These models are described in :ne coprocriate topical reports. ' e did not consicer tnis an issue at that time so imolicitly accepted each model for accumulator delivery.
..e do not believe tnat this issue poses a significant safety problem and can ultimately be handled within the scoce of present ECCS design capability. An example of the influence that the gas model can make on integrated accumulator delivery is shown on Figure 2 enclosed. Test data are from full-scale accumulator discharge.
3.
Evaluation: He are uking our consultants (Sandia Laucratories) to continue their analytical evaluation of this issue. We have requested Hestinghouse to provice comoarisons of their mocel with protetypic accumulator delivery data for UHI plants. As part of the Standard Problem Program we have requestec all participants to provide analytic ccmoarisons to available da ti (see memo Ross to Standarc Problem Participants, enclosed).
It is conceivable that after our review of this issue is complete, changes in scme vencor mcdels for scme plants may be required. The effect of these cnances en calculated ECCS performance is not likely to be large for any plant except UHI plants.
In any case, simple adjustments in accurulator water volume could most likely ccm::ensate for an'. rodel change.
This issue should be completely rescived by August of this year 4.
Interim Accnunting:
It is recommended that nc change is required until our evaluation is comolete.
Since we nave notific reactor vendor, by mail of the need to do additional calculations, we should consicer informinc
')j sitting boards in the post-SER space.
It is applicaole to all such PWPs.
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4 PENCRANLUi' !n: U.S. Standard Frcolem Participants b
1-RICH :
Oe':wcod F. Ross, Jr., Assistant Director for Reactor Safety, by r
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MCU4ULATCR DELI'!ERY COMPAR15CNS C
L RELAP 4 comparisons of LOFT tests L1-3A and L1-4 (U.S. Standard Preblem #7) t.
L' have highlight.ed certain aspects of 'ccumulator delivery wnich should be
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considerq<i in the s tandard problem i,., gram.
The RELAP-4 program througn t'
version 2 of MnD. A used an isotnermal gas emnsion model for nitrogen in ti the accumulltors.
Pos t t2s t analysis of L1.M l'y INCL indicated that the f.'
actual Hs expansion is somewhere between isothe - al and isentropic (Y"I'l.2 h L1 4 1 elf" valysis used an interm=diate value for I and after correctinc f
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loss coef ficient?,tas able to match ;;res sure and delivery driving the esi1 E'
portinn 7f accumulater delivery.
After 35 seconds of injection the data ~b she.ts flow spi' es v.nich are not predicted by RELAP.
It has been suggested h that this is related to ni tregon in the delivery lines end may cause h
exhaustion of the accumulators soCner than predicted.
We believc that accumulator delivery behavior can have an imcortant effectT cn ECCS perfom?nce.
incimP: a. cui. nl a tor del i ver y.
In the past tnis iidormation has not been f
providcl by all carticicants.
Please provide pressure and ficw c:moarisonc !$
Mr all out md future synd3rd croDiems where applicable.
For L1-4 dis: "
tne cv, ariws, inciuding the following:
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Ja m.re sion model C4h lw b.)
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Loss coef ficients d.) :li
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Lori typic 311ty c.vpored to 12rge scale accumulater data 7
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Particip ints hwing approved licensing nmir:lsiprhvide any additional compa-M to experiment er other information certinent to assessing tnc validity of f g 3CCU;vul a to e de1 i iery medel s.
4..
E Sincerely, b
k' Cerreioed F, Rocs, Jr., Assistant Direct- [
for Ieactor Safety g
Division of Systems Safety h*
g Office of Nuclear Reactor Regulaticn g
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