ML20012C899
| ML20012C899 | |
| Person / Time | |
|---|---|
| Site: | Vermont Yankee File:NorthStar Vermont Yankee icon.png |
| Issue date: | 03/09/1990 |
| From: | Fairtile M Office of Nuclear Reactor Regulation |
| To: | Tremblay L VERMONT YANKEE NUCLEAR POWER CORP. |
| References | |
| TAC-68216, NUDOCS 9003260083 | |
| Download: ML20012C899 (7) | |
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hyJDocketNo.50-271-MAR 9 919110 Mr.: L.A.L Tremblayf Licensing Engineert
-Vermont Yankee' Nuclear Power Corporation.
,580 Main Street-Bolton, Massachusetts 01740-1398 Deer Mr. Tremblay:.
4
SUBJECT:
RE0 VEST FOR ADDITIONAL INFORMATION - FROSSTEY-2 FUEL PERFORMANCE >
'7
. CODE.(TACNO.68216)
RE: Vermont Yankee. Nuclear Power Station We are reviewing your use of the Frosstey Computer Code for LOCA analysis as described in your letters dated December 16, 1987, and August 4, 1989, and
_the conference call of October 16, 1989.
'Je find that we. need additional' information as described in the enclosed request for additional information to complete our review.. We request that you provide a response to the enclosed
.i request within 30 days of receipt of this letter.
The reporting and/or record keeping requirements contained in this letter affect fewer than ten respondents; therefore, OMB clearance-is not required under P.L.96-511.
Sincerely, j
Original signed by Patrick M.' Sears
[* D'n-Morton B. Fairtile, Project Manager:
. Project Directorate I.3 Division of Reactor Projects I/II so,.:
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Document Name:
VT YANKEE DOCKET NO. 50271 4
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ENCLOSURE 1 REQUEST FOR ADDITIONAL INFORMATION ON FVY-116
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ENTITLED " VERMONT YANKEE LOCA ANALYSIS METHOD:
FROSSTEY FUEL PERFORMANCE CODE (FROSSTEY2)"
(C0t94UNICATED TO VERMONT YANKEE NUCLEAR CORPORATION IN AN OCTOBER 1989 CONFERENCE CALL) i 1.
A more detailed description is needed on how FROSSTEY2 is applied in the loss-of-coolant accident (LOCA) analysis and justification that the FROSSTEY2 output is adequately conservative for input to the LOCA analysis.
If the code is "best estimate," an additional additive factor to the FROSSTEY2 output may be necessary before input to the LOCA analysis.
This description should provide an example FROSSTEY2 calcu-lation used for input to LOCA that includes FROSSTEY2-calculated output L
values of peak volume average temperature, centerline temperature, gap l
conductance, and rod average fission gas release.
In addition, this example calculation should include sufficient code input information that would allow an independent audit calculation to be performed. The l
l conservatisms in code predictions and code input should be identified and, when possible, quantified.
It is suggested that the code com-parisons to measured fuel temperature data be used to quantify the conservatisms in the FROSSTEY2 predictions of fuel stored energy for LOCA.
It is also suggested that only fuel temperature data from fuel l
rods that are typical of today's fuel designs and peak operating con-L ditions typical of those used for LOCA analyses be used for these code i
comparisons.
2.
The following information is required in order to assess the FROSSTEY2 thermal predictions for fuel rod design that are typical of those used in commercial light water reactors (LWRs).
a) A comparison of FROSSTEY2 code predictions to measured centerline temperatures for Rods 1, 2, and 6 from Halden Assembly IFA-513 and Rod 1 from Halden Assembly IFA-432 is needed.
This should be relatively easy because the FROSSTEY2 predicted values of centerline temperatures for these rods were provided by VYNPC in their original responses and, therefore, the comparison to the measured data only needs to be included.
The FROSSTEY2 predicted-to-measured values 1
1 0
should be provided for each of-the thermocouple locations in the c
i above experimental fuel rods in the following manner:
input power histories used to make-FROSSTEY2 predictions predicted minus measured centerline temperatures versus linear-e heat generation rate (LHGR) predicted minus measured centerline temperatures versus burnup-e predicted minus measured centerline temperatures versus
+
measured centerline temperatures, i
b)
The FROSSTEY2 fuel centerline predictions for Rod 3 of IFA-432, compared to PNL estimates of measured temperatures for this rod, indicate that the code overpredicts fuel temperatures early-in-life, but underpredicts fuel temperatures later-in-life. This behavior suggests a potential problem in the FROSSTEY2 estimation of gap conductance with burnup. Does VYN,'C know or suspect which of the many fuel behavior models in FROSSTEY2 that may have caused this underprediction later-in-life?
c)
Fuel performance cede predictions of fuel centerline temperatures in commercial LWRs are dependent on cladding creepdown.
The three FROSSTEY2 comparisons of cladding creepdown predictions to data ll provided in VYNPC's earlier responses are not judged to be suf-L ficient in number nor diverse enough in application to warrant an assessment of the codes ability to predict cladding creepdown in j
today's commercial LWR fuel designs. There is a diversity of cladding creepdown data in the open literature from the U.S.
L Department of Energy's (DOE) Extended Burnup Programs. Those vendor j'
data from these programs that are applicable to Yankee Atomic l
Electric Company reactors should be used for code comparisons.
3.
The following information is required in order to assess the FROSSTEY2 code prediction of rod internal pressures.
a)
Based on the original submittal and additional data comparisons in the responses to questions, it is apparent that the FROSSTEY2 code underpredicts both steady-state and transient fission gas release, 2
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on the average, for specific fuel design parameters and operating conditions.
Steady-state fission gas release is underpredicted for pressurized fuel rods when gas release is greater than 5% and burnup levels are greater than 30 mwd /kgM.
Transient fission gas release is consistently underpredicted for both pressurized and unpressurized rods at all burnup levels when fission gas release is greater than 5%.
This is of concern because it is the high release rods (>5% release) in a core, at higher burnup levels, that are-limiting in the analysis of rod internal pressures. VYNPC has implied that the uncertainty in the fission gas release data is too large to predict-this phenomenon in an accurate manner.
This response is contrary to other fuel vendors and their codes have been able to predict the fission gas release for most of these same rods with reasonable accuracy and with little or no underprediction.
Therefore, VYNPC must resolve this underprediction before the FROSSTEY2 code can be approved for the calculation of rod internal pressures..
b)
The prediction of rod internal pressures is dependent on an accurate prediction of internal rod void volumes.
Please provide a com-parison of FROSSTEY2 predictions of internal void volumes for those fuel rods that have measured internal " cold" void volumes.
The FROSSTEY2 predictions may be corrected to " cold" conditions to match the void volumes data, but the methodology used for the corrections must be defined.
Internal " cold" void volume data is available for many of the fuel rods used by VYNPC for fission gas release data l
comparisons with the FROSSTEY2 code.
Therefore, comparisons of FROSSTEY2 predicted-to-measured " cold" void volumes for these rods should be relatively easy because the fuel rod predictions have already been made with FROSSTEY2.
c)
The methodology used by VYNPC to determine the boiling water reactor (BWR) and pressurized water reactor (PWR) rod power histories, used as input to FROSSTEY2 in the rod pressure calculation, needs to be defined. This methodology needs to account for normal steady-state operation, normal operational transients, e.g., xenon-induced 3
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e transients, and anticipated operational occurrences. The uncertainties in both steady-state and transient rod powers need to be accounted for in these power histories. These power histories may take into account an inherent reduction in power capability of the fuel due to fissile material' burnout, but the assumptions used to determine this power reduction should be stated.
d)
Examples should be provided of FROSSTEY0 calculations of internal pressures for both BWR and PWR fuel rods. These two examples should include the FROSSTEY2 output of rod pressures, rod average fission gas release, hot internal rod volumes, peak centerline temperature, and gap conductance of hot axial node versus rod average burnup.
These example calculations should also include sufficient code input information that would allow an independent audit calculation-to be performed.
I 4.
Based on discussions with VYNPC staff, the FROSSTEY2 code will be applied to evaluate Gd 0 -U02 burnable poison rod performance as well as U02 rod 23 performance.. In order for this code to be used for the analysis of gadolinia rods, the following information needs to be provided for NRC review:
a)
The gadolinia material properties used in the code need to be provided. An example of the V0 -Gd 02 3 material properties that need 2
to be addressed are theoretical density, thermal expansion, thermal L
conductivity, specific heat, and melting temperatures.
b) How the gadolinia rod powers are determined as a function of burnup (including the radial power distribution in the gadolinia pellet) for input to the code for the specific analyses that are to be per-
- formed, c) The maximum gadolinia concentrations (in weight fraction or percent) of the pellets in the burnable poison rods to which the code will be applied need to be provided.
i 4
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,J Mr. L. A. Tremblay Vermont Yankee 1
cc:
Mr. J. Gary Weigand President & Chief Executive Officer Chairman, Board'of Selectman Vermont Yankee Nuclear Power Corp.
Post Office Box 116 R.D. 5, Box 169 Vernon, Vermont 05354 Ferry Road Brattleboro, Vermont 05301 Mr. Raymond N. McCandless Vermont. Division of Occupational Mr. John DeVincentis, Vice President and Radiological Health c
Yankee Atomic Electric Company Administration Building 580 Main Street Montpelier, Vermont 05602 Bolton, Massachusetts 01740-1398 Honorable John J. Easton New England Coalition on Nuc1 car Attorney General Pollution State of Vermont Hill and Dele Farm 109 State Street R.D. 2, Box 223 Montpelier, Vermont 05602 Putney, Verront 05346 Vermont Public Interest Research Group, Inc.
43 State Street
. Montpelier, Vermont 05602 Diane Curran, Eso..
Regioral Administrator, Region I Harmon, Curran & Tousley U.S. !;uclear Regulatory Commission 2001-S Street, N.W., Suite 430 475 Allendale Road Washington, D.C.
20009 King of Prussia, Pennsylvania 19406 James Volz, Esq.
R. I'. Gad, III Special Assistant Attorney Gener'al Ropes & Gray Vermont Department of: Public Service One International Place 120 State Street.
Boston, Massachusetts 02110 Montpelier, Vermont 05602 Mr. W. P. Murphy, Vice President G. Dana Bisbee, Esq.
and Manager of Operations Office of the Attorney General Vermont Yankee Puclear Power Corporation Environmental Protection Bureau R.D. 5, Box 169 State House Annex Ferry Road 25 Capitol Street Brattleboro, Vermont 05301 Concord, New Hampshire 03301-6397 fir. George Sterzinger, Comissioner Atomic Safety and Licensing Board l.
. Vermont Department of Public Service U.S. Nuclear Regulatory Comission L
120 Stcte Street, 3rd Floor Washington, D.C. 20555 Montpelier, Vermont 05602 Public Service Board i
L State of Vermont.
' 120 State Street Montpelier, Vercont 05602
,.~;
g-Hr. L. A. Tremblay Vermont Yankee cc:
fir Gustave A. Linenberger,Jr.
Robert M. Lazo, Chairman Administrative Judge Atomic Safety and Licensing Board Atomic Safety and Licensing Board U. S. Nuclear Regulatory Comission i
U.S. Nuclear Regulatory Comission Washington, D.C. 20555 Washington, D.C.
20555 l
Frederick J. Shon Resident Inspector Administrative Judge Vermont Yankee Nuclear Power Station Atomic Safety and Licensing Board U.S. Nuclear Regulatory Comission U. S. Nuclear Regulatory Comission i
P.O. Box 176 Washington, D.C. 20555 i
Vernon, Vermont 05354 Jerry Harbour R
John Traficonte, Esq.
Administrative Judge Chief Safety Unit Atomic Safety and Licensing Board Office of the Attorney General V. S. Nuclear Regulatory Comission One Ashburton Place, 19th Floor Washington, D.C. 20555 Boston, Massachusetts 02108 Geoffrey M Huntington, Esquire p
Office of the Attorney General Enviremrental Protection Bureau State House Annex 25 Capitol Street Concord, New Hampshire 03301-6397 Charler. Cechhoefer, Esq.
Administrative Judge Atomic Safety and Licensing Board U.S. Iluclear Regulatory Comission Washington, D.C.
20555 Dr. Jaraes H. Carpenter Adrinistrative Judge l
Atomic Saf ety and Licensing Board U.S. Nuclear Regulatory Comission Washington, D.C.
20555 i
Adjudicatory File (2)
Atomic Safety and Licensing Board i
Penel Docket U.S. Nuclear Regulatory Comission
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Washington, D.C. 20555 I
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