ML19249D636
| ML19249D636 | |
| Person / Time | |
|---|---|
| Site: | Black Fox |
| Issue date: | 08/27/1979 |
| From: | Davis L NRC OFFICE OF THE EXECUTIVE LEGAL DIRECTOR (OELD) |
| To: | |
| References | |
| NUDOCS 7909250125 | |
| Download: ML19249D636 (15) | |
Text
-
.s JtC PUBLIC DOCUMENT R005f
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UNITED STATES OF AMERICA
-, dg7h NUCLEAR REGULATORY COMMISSION b,.
BEFORE THE ATOMIC SAFETY AND LICENSING BOARD
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In the Matter of
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PUBLIC SERVICE COMPANY OF OKLAHOMA, Docket Nos. STN 50-556 ASSOCIATED ELECTRIC COOPERATIVE, INC.
)
STN 50-557 AND
)
WESTERN FARMERS ELECTRIC COOPERATIVE, INC. )
)
(Black Fox Station, Units 1 and 2)
)
NRC STAFF RESPONSE TO LICENSING BOARD ORDER ON ECCS MATTERS I.
Background
On May 9,1979, the NRC Staff filed what it termed " draft" Findings of Fact and Conclusions of Law with the Atomic Safety and Licensing Board in this Although these findings were the last item to be submitted following case.
completion of the Radiological Health and Safety Hearings in February of 1979,1/
the Findings of Fact were designated " draft" by the Staff because, in their view, new information had been received during the pendancy of the hearings which made it unclear whether the Staff's testimony about the conservativeness of the SAFE and REFLOOD ECCS Codes tied for BFS needed to be modified.
In general, the new infonnation concerned the application of the Leibniz Rule, the receipt of results from GE's Two Loop Test Apparatus Program (TLTA),2/. and the magnit.ude of the heat transfer coefficient calculation used to determine the pressure 1/ The State of Oklahoma and Intervenors subsequently have filed motions to reopen the record because of TMI-2.
2/ General Electric is the Applicants' vendor.
7 009250 lE 9 1023 ::.;
transient in the 6AFE Code. The Staff explained that although the general outlines for submission of the data necessary to resolve the uncertainties had been ascertained, it had not received, nor had GE committed to furnishing, the calculations and data needed to confirm or deny the conservativeness of the BFS ECCS analysis.
In its letter of May 9,1979, the Staff committed itself to further discussions with General Electric and promised to report its conclusions in the form of amended findings of fact about these three matters after the necessary data had been submitted. Considerable controversy between the Staff and Applicants then ensued, culminating in a June 15, 1979 Order by the Licensing Board.
In its June 15, 1979 Order, the Licensing Board noted the controversy between the parties and stated that it felt that the present record did not iaflect "either a resolution of the technical disagreements or the alternatives to E ecision, viz., reasonable assurance such resolution offered by River Bend d
that the disagreements will be resolved at an appropriately early stage."
Accordingly, the Licensing Board ordered " Applicants and Staff to confer and advise us jointly and/or individually as to whether there is reasonable assurance that these matters can be resolved before the reactor is put into opera tion. " The instant pleading is the Staff's individual response to that
- mandate, if Footnote added. Gulf States Utilities Co. (River Bend Station, Units 1 and 2), ALAB-414, 6 NRC 760 (1977).
1023 45
. After conferring at length with General Electric and after having received additional submissions, the NRC Staff now believes that the information which has been submitted furnishes a reasonable assurance pursuant to 10 C.F.R. 850.35 that such questions will be s3tisfactorily resolved at or before the latest date stated in the application for completion of construction of the proposed facility.
In addition, the Strff feels that taking into consideration,
tha site criteria listed in Part 100, the proposed facility can be constructed and operated at the proposed location without undue risk to the health and safety of the public.
All 10 C.F.R. H50.35 research needed to resolve these three issues has been identified. The technical bases for this determination which hereby finalizes the Staff's ECCS Findings of Fact, are set forth below.
II.
Discussion As indicated in the attached affidavit by Wayne Hodges, General Electric has provided additional information (references 1, 2 and 3) on the Leibniz Rule concern, the TLTA concern (refs 2, 4, 5, 6) and the magnitude of the heat transfer coefficient used in the calculation of the pressure transisnt with the SAFE computer code (refs. 1, 2, 5, 6). The following is a discussion of the adequacy of that infonnation to satisfy the requirements of 10 C.F.R. 650.35 and the River Bend decision, supra.
1023 J46
A.
Leibniz Rule The Staff concern in the Leibniz Rule application was whether the simplification of the model used by GE to calculate steam flow leaving the core region of a BWR-6 was conservative since the moving boundary velocity of the steam was neglected in GE's application of the Rule.
However, after further study, the information provided on the Leibniz Rule (refs 1 and 2) showed that the effect of this application in the SAFE and REFLOOD codes is a decrease in peak cladding temperature (PCT) of less than 20F for all BWRs evaluated and an increase in peak cladding temperature of 49F over the values which would be calculated for the BWR-6 using the full Leibniz Rule.
For this reason, the approximation to the Leibniz Rule used by GE in SAFE and REFLOOD is clearly conservative and and thus acceptable for BWR-6 calculations in general and for the Black Fox Station in particular.
B.
TLTA The Staff's TLTA concern was based on the preliminary conclusion that the slow depressurization experienced in the TLTA test with ECC injection was due to greater steam generation in the core which could result in a delay of *eflood.,
This consideration led to concern that the vaporization model was in error and non-conservative in its effect on the PCT prediction.
However, upon completion of its review of the data, General Electric reported (ref 2) that its preliminary conclusion was incorrect in that the slower depressurization was actually oue to lower quality break flow (less energy release) and/or additional steam generation external to the core region for the test with ECC injection in comparison to the test without ECC injection.
Break flow density (ref 2) data and a mass and energy 1023
~J7
- balance (ref 6) support the break flow quality argument's explanation of the observed differences in depressurization rate. Also, steam separator pressure drop data (refs 2, 6) support the conclusion that lower flow through the steam separator occurs for the case with ECC injection, hence, the vaporization in the core appears to be less for this case as would be expected.
In addition, a comparison of the peak cladding temperature calculated with the GE ECCS model to that measured in the average power TLTA tests with and without ECC injection is provided in reference (4). The calculated peak cladding temperatures exceed the measured values by approximately 1000F in both cases.
Hence, the calculations indicat7, that the licensing models maintain a large and consistent margin of safety in the prediction of PCT for the two test cases.
Based on the information listed above, paragraph 42 of our Findings of Fact should contain the added wording: "However, subsequent more detailed calculations by GE revealed that the depressurization was due to the difference in the fluid quality at the break flow boundary rather than by the larger vaporization with ECC injection." In addtiion, the last sentence in the second paragraph of section 32 on page 23 of the Staff Findings of Fact should be stricken and the following language substituted: "No model changes found to be required because of TLTA data."
C.
Heat Transfer Coefficient Recent experiments in the two loop test apparatus have demonstrated a significantly higher heat.ansfer coefficient during the early portion of a LOCA transient than are presently used in licensing evaluation models. The NRC Staff questioned 1023
whether the use of these higher heat transfer coefficients would result in a higher calculated PCT for BFS.
Results of analyses as discussed in reference (1) show that use of an increased heat transfer coefficient (h=12 rather than h=4) in SAFE rtsults in a decrease in peak cladding temperature.
In addition, arguments ia ref (6) have also been presented to demonstrate that the heat transfer coefficient values used during transition from nucleate boiling to the core spray cooling regimes are also appropriate. While Staff review of the transition boiling regime is still ongoing, a reasonable assurance exists to believe the risk will be resolved before the OL because the heat transfer coefficients used in the SAFE code evaluation model are comparable to or conservative when compared to those reported in the TLTA data. For this reason, the Staff believes that a reasonable assurance exists that no significant non-conservative variations in PCT could be expected from the use of the heat transfer coefficients found in the TLTA test results.
III.
Summary In summary, the Staff review of the referenced information presented by the Applicants' vendor has progressed to the point where we can make the following findings:
(1) The use of the Leibniz approximation in SAFE is conservative as to PCT and therefore appropriate for the Black Fox Appendix K analysis.
(2) The principal TLTA concern relating to non-conservatism of the vaporization model has also been resolved by showing that slow depressurization during the TLTA tests was not due to greater steam generation in the core.
A comparison of the PCT from TLTA to that obtained from the GE ECCS evaluation model showed a conservative 1000F peak clad temperature difference.
023 s49
. (3) There is reasonable assurance that the concerns regarding the heat transfer coefficient in SAFE can be resolved in the near term since the information on hand indicates that the licensing basis values are conservative with respect to the data.
In addition, General Electric has cocmitted in reference (5) to continue to work with the NRC Staff to resolve the concerns that have been expressed about the TLTA data in regard to heat transfer coefficients.
(4) During the course of the Staff review, all research necessary to resolve questions about the items abon was described by General Electric.
(5) No ECCS evaluation code corrections will be required due to the concerns listed above.
Conclusion For the reasons listed above, the NRC Staff believes that sufficient information has been provided by General Electric to show the conservativeness of the BFS ECCS Appendix K calculations in regard to Leibniz, TLTA and heat transfer coefficient matters to satisfy the requirements of 10 C.F.R.150.34(a)(4).
In addition the Staff finds that there is a reasonable assurance that the matter will be thoroughly explored and resolved at or before the operating license stage of this proceeding and that the requirements for future research and/or calculations have been designated to satisfy the requirements of 10 C.F.R. 650.35 and the River Bend decision, supra.
1023 %0
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. While this pleading suggests two minor revisions of wording contained on pages 23 and 30 of our Radiological Health and Safety Findings of Fact and Conclusions of Law, no need for changes in the final conclusions about ECCS code error: or compliance with Appendix K of 10 C.F.R. Part 50 are required.
Respectfully submitted, dO
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L. Dow Davis Counsel for NRC Staff Dated at Bethesda, Maryland this 27th day of August,1979 1023 151 amw**
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ATTACHMENT A UNITED STATES OF AMERICA NUCLEAR REGULATORY COMMISSION BEFORE THE ATOMIC SAFETY AND LICENSItiG BOARD,
).
, In the Matter of PUBLIC SERVICE COMPANY OF OKLAHOMA, Docket Nos. STN S0-556 ASSOCIATED ELECTRIC COOPERATIVE, INC.
STN 50-557 AND WESTEPJ1 FARMERS ELECTRIC COOPERATIVE, INC.
(Black Fu Station, Units 1 and 2)
AFFIDAVIT OF WAYNE H0DGES The following is a discussion of the Staff investication of the Leibniz Rule application, TLTA test data and heat transfer coefficient use in the General Electric ECCS codes.
A.
Leibniz Rule _
The Staff concern in the Leibniz Rule application was whether the simplification of the model use by GE to calculate steam flow leaving the core region of a BWR-6 'whs conservative since the moving boundary velocity of the steam was neglecter in GE's application of the Rule.
However, af ter further study,.the informat..n provided on the Leibniz Rule (refs 1 and 2) showed that the effect of this application in the SAFE and REFLOOD codes is a decrease in peak cladding temperature (PCT) of less tha,n 20F for all BWRs evaluated and an increase in peaY cladding temperature of 49F over the values which would be calculated for the BWR-6 using the full Leibniz Rule.
For this reason, the approximation to the Leibniz Rule used by GE in SAFE and REFLOOD is clearly conservative and and thus acceptable for BWR-6 calculations in general and for the Black Fox Station in particular.
1023
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. B.
TLTA The Staff's TLTA concern was cased on the preliminary conclusion that the slow depressurization experienced 19 the TLTA test with ECC injection was due to greater st.m generation in the core which could result in a delay of reflood).
This consideration led to concern that the vaporization model was in error and non-conservative in its effect on the PCT prediction.
However, upon completion of its review of the data, General Electric reported (ref 2) that its preliminary conclusion was incorrect in that the slower depressurization was actually due to lower quality break flow (less energy release) and/or additional steam generation external to the core region for the test with ECC injection in comparison to the test without ECC injection.
Break flow density (ref 2) data and a mass and er.ergy balance (ref 6) support the break flow quality argument's explanation of the observed differences in depressurization rate.
Also, steam separator pressure drop data (refs 2, 6) support the conclusion that lower flow through the steam separator occurs for the case with ECC injection, hence, the vaporization in the core appears to be less for this case as would be expected.
In addition, a comparison of the peak cladding temperature calculated with the GE ECCS model to that measured in.the average power TLTA tests with and without ECC, injection is provided in reference (4).
The calculated p.eak cladding temperatures exceed the measured values by approximately 1000F in both cases.
Hence, the calculations indicate that the licensing models maintain a large and co'nsistent margin of safety in the prediction of PCT for the two test cases.
1 1023 s53
C.
Heat Transfer Coefficient Recent experiments in the two loop test apparatus have demonstrated a significantly higher heat transfer ccefficient during the early portion of a LOCA transient than are presently used in licensing evaluation models.
Th NRC Staff questioned whether the use of these higher heat transfer coefficients would result in a higher calculated PCT for BFS.
Results of analyses as discussed in reference (1) show that use of an increased heat transfer coefficient (h=12 rather than h=4) in SAFE results in decrease in peak cladding temperature.
In addition, arguments in ref (6) have also been presented to demonstrate that the heat transfer coefficient values used during transition trom nucleate boiling to the core spray cooling regimes are also appropriate. While Staff review of the transition boiling regime is still ongoing, a reasonable assuranca exists to believe the risk will be resolved before the OL because the heat transfer coefficients used in the SAFE code evaluation model are comparable to or conservative when compared to those report'ed in the TLTA data.
For this reason, the Staff believes that a reasonable assurance exists that no significant non-conservative variations in PCT could
' be expected from the use of the heat transfer coefficients found in the TLTA test results.
'%,4 1023
,54
. In summary, after conferring at length with General Electric and after having recived additionc>l submissions, the information which has been submitted furnishes a reasonable assurance pursuant to 10 C.F.R. 150.35 that such questions will be satisfactorily resolved at or before the latest date stated in the application for completion of construction of the proposed facility.
In addition, the Staff feels that taking into consideration the site criteria listed in Part 100, the proposed facility can be constructed and operated at the proposed location without undue risk to the health and safety of the public. All 10 C.F.R. 950.35 research needed to resolve these three issues has been identified.
Corrections to the NRC Staff Findings of Fact and Conclusions of Law should be made as indicated on the pages listed below:
1.
Page 23, lines 5-7 of para 2:
Delete "As stated in Mr. Hodge's testimony, a comparison of TLTA data with ECCS code analyses may result in code changes due to modeling errors" and add "No model changes were found to be required because of TLTA data" 2.
Page 30, line 13 of para 42:
Add "However, more detailed calculations by GE revealed that the depressurization referenced above was due to the difference in the fluid quality at the break flow boundary rather than by a larger vaporization with ECC injection".
I hereby certify that the information listed above is true and accurate to the best of my knowledge.
f) OMMet Y
Subscribed and sworn to before Rayne fiodges
/
me 3;his 27th day of August,1979.
Notary Public My Commission expires:
1 /
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1023 as
EXHIBIT 1 to ATTACHMENT A References (1) Letter, E. P. Stroupe to R. L. Tedesco, USNRC, "Leibniz Rule On Heat Transfer in LOCA Models," dated May 2,1979 (2) Letter, G. G. Sherwood to Frank Schroeder, "Two Loop Test Apparatus (TLTA)" dated June 15, 1979.
(3) Letter, R. H. Buchholz to Frank Schroeder, "Leibniz Rule in LOCA Models," dated July 13, 1979.
(4). Letter, G. G. Sherwood to Frank Schroeder, "Two Loop Test Apparatus (TLTA)" dated June 29, 1979.
(5) Letter, E. P. Stroupe to Frank Schroeder, "Two Loop Test Apparatus (TLTA) Information, dated July 20, 1979.
(6) Letter, R. H. Buchholz to Frank Schroeder, " Additional TLTA Information,"
dated July 31, 1979.
1023
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UNITED STATES OF AMERICA NUCLEAR REGULATORY COMMISSION BEFORE THE ATOMIC SAFETY AND LICENSING BOARD In the Matter of PUBLIC SERVICE COMPANY OF OKLAHOMA, Docket Nos. STN 50-556 ASSOCIATED ELECTRIC COOPERATIVE, INC.
)
STN 50-557 AND
)
WESTERN FARMERS ELECTRIC COOPERATIVE, INC.
(Black Fox Station, Units 1 and 2)
)
CERTIFICATE OF SERVICE I hereby certify that copies of "NRC STAFF RESPONSE TO LICENSING BOARD ORDER ON ECCS MATTERS" and " AFFIDAVIT OF WAYNE H0DGES" dated August 27, 1979, in the above-captioned proceeding, have been served on the following, by deposit in the United States mail, first class, or, as indicated by an asterisk, through deposit in the Nuclear Regulatory Commission's internal, mail system this 27th day of August,1979.
- Sheldon J. Wolfe, Esq.
Michael I. Miller, Esq.
Atomic Safety and Licensing Board Isham, Lincoln & Beale One 1st National Plaza U.S. Nuclear Regulatory Commission Washington, D. C.
20555 te 240 g
ll1nois 60606
- Mr. Frederick J. Shon, Member M s'. Carrie Dickerson Atomic Safety and Licensing Board U.S.. Nuclear Regulatory Comission Citizens Action for Safe Energy, Inc.
Washington, D. C.
20555 P. 0 B0X 9
],
9 e, lahoma 74107 Dr. Paul W. Purdom Direct.or, Environmental Studies Group yfgn e
Drexel University 9
32nd and Chestnut Street Public Affairs Officer lR Philadelphia, Pennsylvania 19104 ge 00 Joseph Gallo, Esq.
Arlington, Texas 76011 Isham, Lincoln & Beale 1050 17th Street, N.W.
Andrew T. Dalton, Jr., Esq.
Washington, D. C.
20036 Attorney at Law 1437 South Main Street, Room 302 Mrs. Ilene H. Younghein Tulsa, Oklahoma 74119 3900 Cashion Place Oklahoma City, Oklahoma 73112 1023 57
.
- Atomic Safety and Licensing Mr. T. N. Ewing Appeal Board Acting Director U.S. Nuclear Regulatory Commission Black Fox Station Nuclear Project Washington, D. C.
20555 Public Service Company of Oklahoma P. O. Box 201
- Docketing and Service Section Tulsa, Oklahoma 74102 Office of the Secretary of the Commission Dr. M. J. Robinson U.S. Nuclear Regulatory Commission Black & Veatch Washington, D. C.
20555 P.O. Box 8405 Kanst.s City, Missouri 64114
- Atomic Safety and Licensing Board Panel Jan Eric Cartwrigh,, Esq.
U.S. Nuclear Regulatory Commission and Charles S. Rogers Washington, D. C.
20555 Attorney General State of Oklahoma Lawrence Burrell 112 State Capitol Bldg.
Route 1, Box 197 Oklahoma City, Oklahoma 73105 Fairview, Okiahoma 73737 Mr. Gerald F. Diddle Joseph R. Farris, Esq.
General Manager John R. Woodard III, Esq.
Associated Electric Cooperative, Inc.
Feldman, Hall, Franden, Reed and Woodard P.O. Box 754 Springfield, Missourt 65801 816 Enterprise Building Tulsa, Oklahoma 74103 Mr. Vaughn L. Conrad Public Service Company of Oklahoma P.O. Box 201 Tulsa, Oklahoma 74102
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Alan P. Bielawski L. Dow Davi s Isham, Lincoln & Beale unsel for NRC Staff One First National Plaza Suite 4200 Chicago, Illinois 60603 Mr. Maynard Human General Manager Western Farmers Coop., Inc.
P. O. Box 429 Anadarko, Oklahoma 73005 1023 23
.