ML20198L731
| ML20198L731 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 12/31/1998 |
| From: | Scherer A SOUTHERN CALIFORNIA EDISON CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NUDOCS 9901050104 | |
| Download: ML20198L731 (13) | |
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$O01Hf RN CAWORNI A A. Eduard Scherer EDISON Mbm An CDl50N INTERN 4TIONAL* Company Decen ber 31, 1998
'U. S. Nuclear Regulatory Commission
' Attention: Document Control Desk Washington, D. C. 20555 4
Gentlemen:
Subject:
Docket Nos. 50-361 and 50-362 Development of SER Constraints for Reload Analysis Topicci Report i
San Onofre Nuclear Generating Station Units 2 and 3
References:
1.
November ?.3, 1998 letter from A. E. Scherer (SCE) to Document Control Desk (NRC),
Subject:
Development of SER Constraints for Reload Analysis Topical Report, San Onofre Nuclear Generating Station Units 2 and 3 2.
November 30, 1998 letter from D. E. Nunn (SCE) to Document Control Desk (NRC),
Subject:
Reload Analysis Methodology, 4
San Onofre Nuclear Generating Station Units 2 and 3 Reference 1 provided information to the NRC regarding the approach being followed by Southern California Edison (SCE) to develop a tabulation of NRC Safety Evaluation Report (SER) limitations and/or constraints applicable to the SCE reload analysis methodology described in Reference 2.
The enclosure to this letter provides additional information to supplement Reference 1.
The additional information is a sample of the table format of
(
SER-limitations and/or constraints associated with methodologies cited in the y
SCE reload analysis topical report.
/
\\
Because this sample of the table is currently only partly completed it has been stamped " Draft" to identify that it is being provided to the NRC at this time as a preview of the fit, form, and function of the table. The final and complete table format is being prepared in this form.
If the staff should have any difficulty with the attached format or if it fails to meet your
[dD requirements in this matter, we would appreciate your prompt response.
ADOCK0500034,.D
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9901050104 981231 PDR
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PDR b P. O. Ih 128 San Cir. tente, CA 92674-0128 949-368-7501
-- Fax 949-368-7575
Document Control Desk.
As indicated in Reference 1, we will provide the NRC with the completed tabulation of SER limitations and/cr constraints associated with methodologies cited in the SCE reload analysis topical report in February,1999 in support of the requested April 1,1999 topical report approval date.
If you have any questions regarding the enclosed information, please feel free to contact me or Mr. Jack Rainsberry at (949) 368-7420.
Sincerely, T
Enclosure cc:
E. W. Merschoff, Regional Administrator, NRC Region IV J. A. Sloan, NRC Senior Resident Inspector, San Onofre Units 2 & 3 J. W. Clifford, NRC Project Manager, San Onofre Units 2 and 3 l
l.
ENCLOSURE Southern California Edison i
San Onofre Nuclear Generating Station Units 2 and 3 Sample of Table of NRC SER Limitations and/or Constraints Associated With Methodologies Cited in the SCE Reload Analysis Topical Report (Pages 1 through 10 enclosed)
O
UMERIFJED INFORMATJ_Oli Idsntification of Limitations and/or Conetrcints in NRC SER l.
NRC Safety Evaluation Report
Reference:
Letter, A. C. Thadani(NhC) to A. E. Scherer (CE), "Acceptancefor Referencing C-E Topical Report CEN-372 P. Fuel Rod Afaximum Allowable Gas Pressure (TAC No.
69231)", April 10.1990 i
ll.
Submittal Reference (s):
To Be Determined Ill. Applicable Methodology Documentation:
CEN-372-P-A. "FuelRod Afaximum Allowable Gas Pressure", Afay 1990 IV. Identification of Limitations and/or Constraints in NRC SER:
The attached tables provide a tabulation of limitations and/or constraints contained in the Nuclear Regulatory Commission (NRC) Safety Evaluation Report (SER) cited in Item I, for the methodology referenced in item 111. The methodology documentation was originally submitted to the NRC via the referenced letter given in item II. The first table provides the NRC imposed limitations and/or constraints while the second table provides Non-NRC limitations and/or constraints.
The attached tables are applicable only to the NRC SFR for the associated reference methodology. These limitations and/or constraints are separate from those imposed via i
the methodology documentation itself.
j Originators Name (Print)
Independent Reviewers Name (Print)
Originators Signature Date Independent Reviewers Signcture Date Management Reviewer (Print)
Management Reviewer's Signature Date l
l i
XXX-98-XX Page1 1
1
O UNVERIFIED INFORMATION NRC Imposed Safety Evaluation Report Limitations and/or Constraints in SCE Reload Analysis Methodology SER Reviewed:
Letter A. C. Thachmi(NRC) to A. E. Scherer (CE), "Acceptancefor Referencing C-E Topical Report CEN-372-P, Fuel Roci Alaxhmtm Ailouable Gas Pressure (TAC No. 69231)", April 10, I990 A';sociated Methodo!ogy Documentation:
CEN-372-P-A. " Fuel Rail Afaximmn Allowable Gas Pressure", Afay 1990 No.
NRC Imposed SER Limitation / Constraint"8 Analyzed Event (s)"8 Type"'
Explanatory Comment (s)
Loca ion
Met o o y",
1.
We conclude that the fuel swelling and SER Pg 5 Fuel NRC cladding creep models as used by C-E for Performance evaluating the fuel-cladding gap stability are found to be conservative in relation to this analysis and, therefore, are found to be acceptable.
2.
The C-E methodology for determining SER Pg 5 Fuel NRC bounding power histories for normal and 6
Performance anticipated operation has previously been defined in the review of Reference 1 and approved by the NRC (Reference 2). This previous approval found that the use of the C-E bounding power histories as input to the C-E fuel performance codes (References 7 and
- 8) resulted in a bounding and, therefore, conservativa estimate of rod internal pressures. Use of this same input is found to be acceptable for the determination of the critical rod pressure limit.
A XXX-98-XX Page 2
UNVERIFIED INFORMATION NRC Imposed Safety Evaluation Report Limitations and/or Constraints in SCE Reload Analysis Methodology SER Reviewed:
Letter A. C. Thadani (NRC) to A. E. Scherer (CE), "Acceptancefor Referencing C-E Topical Report CEN-372-P Fuel Rod Alaximwn AIlowable Gas Pressure (TAC No. 69231)". April 10,1990
~
ADsociated Methodology Documentation:
CEN-372-P-A, " Fuel Rod Ataxinnun Allowable Gas Pressure" Afay I990 No.
NRC Imposed SER Limitation! Constraint"8 Analyzed Event (s)W Type Explanatory Comment (s) m Localon*
Met o o o ym 3.
"This proposed analysis methodology for SER Pg 6 Fuel NRC maintaining a stable fuel-cladding gap is found Performance to be acceptable because
- 1) the C-E analysis methods for establishing the critical rod pressure limits are found to be conservative, and
- 2) the C-E analysis methods for assuring that C-E rod pressures for a given fuel design application do not exceed this limit have previously been found to be bounding and conservative (Reference 2)."
4.
C-E has evaluated (references 4 & 6)
SER Pg 7 Fuel NRC masetm cladding tensile hoop stresses that Performance coud be experienced by their fuel designs at the entical pressure limit during normal and anticipated operational events. The maximum tensile hoop stress was found to exist during y
an anticipated system depressurization event.
g This maximum hoop tensile stress was found to be less than that required to initiate hydride reorientation in the radial direction. Therefore, the critical rod pressure limit proposed by C-E is found to be acceptable in terms of preventing hydride radial reorientation during normal or anticipated operational events.
XXX-98-XX Page 3
UNVERIFIED INFORMATION NRC Imposed Safety Evaluation Report Limitations and/or Constraints in SCE Reload Analysis Methodolog'y SER Reviewed:
Letter, A. C. Thadani (NRC) to A. E. Scherer (CE), "Acceptancefor Referencing C-E Topical Report CEN-372-F, Fuel Rod Afaximinn Allontable Gas Pressure (TAC No. 69231)", April 10,1990 Ansociated Methodology Documentation:
CEN-372-P-A, " Fuel Rod Afarinnun Allontable Gas Pressure". Alay I990 N 3.
NRC Imposed SER LimitationtConstraint"8 Analyzed Event (s)"8 Type"8 Explanatory Comment (s)
Loca ion l Met o o o y",
ir 5.
Higher internal rod pressures may impact the SER Pg 7 Fuel -
NRC timing of cladding rupture and, therefore, Performance higher PCTs could occur at higher burnup levels during a LOCA. Consequently, C-E must demonstrate that PCTs continue to remain below the limits required by 10CFR50, Section 50A6 for these rods. C-E has stated that plant specific analyses will be performed for future fuel reloads using the higher calculated rod pressures as input to the LOCA calculation. If the higher rod pressures and their effect on the timing of cladding rupture during a LOCA are calculated to have a negative impact on fuel operating limits C-E has indicated that it will reduce either the LOCA linear heat rate (LHR) or the critical rod
, pressure limit accordingly. This ana!ysis g
approach is found to be acceptable as long as g
approved codes and analysis methods are utilized.
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XXX-98-XX Page 4
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UNVERIFIED INFORMATION NRC Imposed Safety Evaluation Report Limitations and/or Constraints in SCE Reload Analysis Methodology SER Reviewed:
Letter, 4. C Thadani (NRC) to A. E. Scherer (CE), "Acceptancefor Referencing C-E Topical Report CEN-372-P, Fuel Rod Maximum Ailowable Gas Pressure (TAC No. 69231)", April 10,1990 Ansociated Methodology Documentation:
CEN-372-P-A, " Fuel Rod Aktrimwn Allowable Gas Pressure" May 1990 No.'
NRC imposed SER LimitationtConstrainF8 Analyzed Event (s)W Type Explanatory Comment (s) m Locaionm Met o
ym 6.
Therefore, we have concluded that if C-E SER Pg 9 Fuel NRC i
wishes to reference this analysis approach for Performance future reload applications, they must either r
- 1) demonstrate that the number of rods that experience both DNB and have rod internal pressures above RCS pressure during postulated accident is equal to or less than the number of rods assumed in Reference i
6; or
- 2) if the number of rods exceed those assumed in Reference 6, recalculate the additional rods that are assumed to fail
- using this app oach and, therefore, reevaluate th.s radiological consequences of DNB propagation for these postulated accidents in future reload applications.
C-E has concluded that these NRC imposed conditions for approval of this analysis j
t approach are not satisfactory and, therefore, has elected to use the second analysis approach discussed in the following subsection.
XXX-98-XX Pane 5
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' UNVERIFIED INFORMATION NRC Imposed Safety Evaluation Report Limitations and/or Constraints in SCE Reload Analysis Methodology SER Reviewed:
Letter. A. C. Thadani (NRC) to A. E. Scherer (CE), "Acceptancejbr Referencing C-E Topical Report CEN-372-P, Fuel Rod Afaxintunt Allaurable Gas Pressure (TAC No. 69231)", April 10,1990 Associated Methodology Documentation:
CEN-372-P-A, "Ftrel Rod Ahuximtun Allowable Gas Pressure", Alay 1990 N2.
NRC Imposed SER Limitation /Crnstraint"8 Analyzed Event (s)"'
Type Explanatory Comment (s) -
m Loca lon"'
Met o o ym 7.
The second C-E analytical approach has SER Pg 9 Fuel NRC assessed the likelihood of DNB propagation 10 Performance by determining the maximum amount of cladding ballooning in fuel rods that experience both DNB and rod pressures above nominal RCS pressure.
The film boiling coefficient and rupture strain model used in these analyses are acceptable i
when applied in the manner described in C-E's i
responsa (Reference 6).
8.
"..we have concluded that both the calculated SER Pg 10 Fuel NRC strain values and the assumption of uniform Performance cladding ballooning used by C-E are
(
conservative for the analysis of g
DNB propagation. Therefore, we have concluded that this C-E analysis approach is acceptable."
I XXX-98-XX Page 6
UNVERIFIED INFORMATION
.NRC Imposed Safety Evaluation Report Limitations and/or Constraints in SCE Reload Analysis Methodology SER Reviewed:
Letter, A. C. Thadani (NRC) to A. E. Senerer (CE), "Acceptancefor Referencing C-E Topical Report CEN-372-P, Fuel Rod Maximum Allowable Gas Pressure (I'AC No. 69231)", April 10,1990 Arc:ociated Methodology Documentation:
1 CEN-372-P-A, " Fuel Rod Maxinnnn Allowable Gas Pressure", May 1990 A P ca e No.
NRC Imposed SER Limitation / Constraint"8 Analyzed Event (s)H8 Type"8 Explanatory Comment (s) bc in"8 W 9 99 i
9.
We have evaluated C-E's claim and agree SER Pg 11 Fuel NRC that DNB propagation will not occur based on.
Performance their maximum calculated uniform cladding strains and, therefore, their maximum calculated flow blockage into surrounding sutthannels of the 14x14 and 16x16 ballooned rods. We have also evaluated the minimum calculated distance from the ballooned rods to adjacent rods and concluded that sufficient distance remains to prevent DNB propagation to these adjacent i
rods for the limiting postulated accidents.
These conclusions are only applicable to the critical rod pressure limit and the maximum uniform cladding strains calculated in Reference 6. Because the steam line break for 14x14 fuel design provides the largest amount of cladding ballooning and flow blockage, this analysis is the bounding case for DNB propagation at the critical rod pressure limit as defined in Reference 6.
Therefore, if future fuel reload applications have calculated uniform cladding strains or values of percent flow blockage greater than those calculated in this analysis for the bounding 14x14 steam line break, further justification will be required from the licensee on DNB propagation in postulated accidents.
XXX-98-XX Pace 7
UNVERIFIED INFORMATION NRC Imposed Safety Evaluation Report Limitations and/or Constraints in SCE Reload Analysis Methodology SER Reviewed:
Letter, A. C. Thadani(NRC) to A. E. Scherer (CE), "Acceptancefor Referencing C-E Topical Report CEN-372-P, Fuel Rod Afaxinnem Nilowable Gas Pressure (PAC No. 69231)", April 10,1990 A:sociated Methodology Documentation:
CEN-372-P-A, " Fuel Rod Ahiximtun Allowable Gas Pressure", Akiy 1990 No.
NRC Imposed SER Limitation / Constraint"8 Analyzed Event (sP' Type Explanatory Comment (s)-
m Locaionm Met o o o y
10.
We conclude that the C-E critical rod pressure SER Pg 12 Fuel NRC limit will not result in DNB propagation during Performance their limiting postulated cccidents for the 14x14 and 16x16 designs at the limiting conditions defined in Reference 6 and, therefore, this limit is acceptable with respect to these C-E fuel designs. The limiting conditions to prevent DNB propagation are the maximum cladding strains and percent flow blockage calculated for the bounding 14x14 steam line break in Reference 6.
XXX-98-XX Page 8
UNVERIFIED INFORMATION NRC Imposed Safety Evaluation Report Limitations and/or Constraints in SCE Reload Analysis Methodology SER Reviewed:
Letter, A. C. Thadani (NRC) to A. E Scherer (CE), "Acceptancefor Referencing C-E Topical Report CEN-372-P, Fuel Rod Afaxinmm Allouttble Gas Pressure (TAC No. 69231)" April 10,1990 Aosociated Methodology Documentation:
CEN-372-P-A, " Fuel Rod Afaxinnun Allourible Gas Pressure". Afay 1990 No, NRC Imposed SER Limitation / Constraint"8 Analyzed Event (s)W Typem Loca ionm Met o o y",
Explanatory Comment (s) 11.
Based on tue C-E 14x14 and 16x16 fuel SER Pg 13 Fuel NRC design analyses presented in CEN-372-P, we Performance conclude that the critical rod pressure limit proposed by C-E is acceptable for licensing l
applications. However, those licensees referencing this high pressure topical report are require to
- 1) provide plant-specific LOCA analyses to determine the impact of maximum calculated rod pressures on cladding rupture timing and peak cladding temperature, as described in Section 2.3; I
and
- 2) provide analyses for DNB propagation in postulated accidents if the bounding 14x14 steam line break is not applicable for calculating maximum cladding rupture strain and percent flow blockage for the licensees application, as describe in l
Section 2.4.2.
i XXX-98-XX Page 9
w y..
-x I h' 7 UNVERIFIED INFORMATION-L L
(1) NRC Imposed Limitation / Constraint may be either the verbatim SER language or a paraphrase 'where the same limitation and/or constraint is stated in different
- ways in more than one place in the SER. in general a single SER Location citation would indicate " verbatim *, while multiple location entries would indicate a Paraphrase.
- (2) SER Location means the SER page number or section number where the limitation and/or constraint is located.
(3) Apphcable Methodology means the common name of the analysis method. Typically this may simply be the computer code name, e.g., CESEC, R,0CS-DIT..
FATES, etc.
(4) Analyzed Events means the Chapter 15 event (s) evaluated by the subject methodology. In general this means an event evaluated using a system thermair l
hydraulic transient code such as CESEC. Other codes such as physics (e.g., ROCS-DIT) or fuel performance (e.g., FATES 3B) codes are not used to evaluate an event, per se, but are used to provide interface input to the system thermal-hydraulic transient code. In this latter situation, the methodology to which input is -
provided will be listed in this column..
- (5) Type means the nature or origin of the limitation and/or constraint. "ABB* - means self-imposed via methodology documentation. "NRC"- mean imposed by ttk NRC via the methodology documentation SER, *l* - means a implied statement made by the NRC in an SER which was not identified as an imposed limitation '
and/or constraint (see Groundrule #7 for discussion), " Admin"- means an administrative constraint imposed by the NRC; " Accept * - means an NRC statement of
-i acceptance regart'ing individual models, approaches or the overall methodology. Because of the large quantity, by exception, all SER text not categonzed as to a.
" Type" is considered to simply be descriptive text carrying no inherent limitations and/or constraints.
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