ML20246F594
| ML20246F594 | |
| Person / Time | |
|---|---|
| Site: | South Texas  |
| Issue date: | 07/07/1989 |
| From: | Rosen S HOUSTON LIGHTING & POWER CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| Shared Package | |
| ML20246F598 | List: |
| References | |
| ST-HL-AE-3157, NUDOCS 8907130317 | |
| Download: ML20246F594 (8) | |
Text
.
The Light company rject ectric Generat gStati n
.O. Box 2 Wadswore, Texas 77m ut exas Houston Lighting & Power July 7, 1989 ST-HL-AE-3157 File No.: G9.01, R5 10CFR50.59 10CFR50.90 10CFR50.92 U. S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, DC 20555 South Texas Project Electric Generating Station Units 1 and 2 Docket Nos. STN 50-498, STN 50-499 Proposed License Ameradment Concerning The Reanalysis of a Design Basis Rod Withdrawal from Sub-Critical Accident 1
Reference:
- 1. NUREG-0781 SAFETY EVALUATION REPORT related to the operation of South Texas Project, Units 1 and 2; Supplement Nos. 1 thru 7
'.3 accordance with 10CFR50.90, Houston Lighting and Power (HMP) submits this application for amendment of the South Texas Project Unit 1 (NPF-76) and Unit 2 (NPF-80) licenses to allow use of the reanalysis of a design basis Rod Withdrawal from Sub-Critical Accident as described in the attached FSAR changes. Approval of this application is required to support the STPEGS Unit I restart following the first refueling.
The results of the reanalysis of a design basis Rod Withdrawal from Sub-Critical Accident show the average fuel clad temperature would increase. With this increase the peak fuel temperature remains considerably less than the design limit and consistent with the basis for acceptance by the NRC as stated in the STP Safety Evaluation Report (SER), NUREG-0781 (ref. 1).
However, the reanalysis does meet the present HMP interpretation of the NRC's criterion for being a change which reduces the margin of safety as defined in the basis for the technical specifications and is therefore considered an unreviewed safety question in accordance with the requirements of 10CFR50.59 and 10CFR50.92. HMP has reviewed the unreviewed safety question and concluded there are no resulting significant hazard considerations.
The description of the changes, safety evaluation, and annotated FSAR pages are attached. HMP will incorporate these changes into an STP FSAR update subsequent to the approval by NRC staff.
pDR9072303j7 890707 F7 ADOCK 0500049s p
PNU goo l
\\
S3/LIC10/89181001 A Subsidiary of Houston Industries incorporated l
l
i Houston Lighting & Power Company ST-HL-AE-3157
' South Texas Pfoject Electric Generating Station File No.:
G09.01, R5 Page 2 l
The South Texas Project Nuclear Safety Review Board has reviewed and approved the attached proposed revision and concurs with the 10CFR50.59 l
determination.
i l
In accordance with 10CFR50.91(b), HL4P is providing the State of Texas I
with a copy of this proposed amendment.
1 If you should have any questions on this matter, please contact 1
Mr. A. W. Harrison at (512) 972-7298.
I l
)
l S. L. Rosen Vice President, Nuclear Engineering and Construction SDP/dw Attachments: 1.
Description of Change 2.
Safety Evaluation 3.
Annotated revisions to FSAR S3/LIC10/89181001
Houston Lighting & Power Company ST-HL-AE-3157 South Texas Project Electric Generating Station File No.
G09.01, R5 Page 3 cc:
Regional Administrator, Region IV Rufus S. Scott Nuclear Regulatory Commission Associate General Counsel 611 Ryan Plaza Drive, Suite 1000 Houston Lighting & Power Company Arlington, TX 76011 P. O. Box 1700 Houston, TX 77001 George Dick, Project Manager U. S. Nuclear Regulatory Commission INPO Washington, DC 20555 Records Center 1100 Circle 75 Parkway Jack E. Bess Atlanta, GA.
30339-3064 Senior Resident Inspector-Unit 1 c/o :1. S. Nuclear Regulatory Commission Dr. Joseph M. Hendrie P. O. Box 910 50 Bellport Lane Bay City, TX 77414 Bellport, NY 11713 J. I. Tapia D. R. Lacker Senior Resident Inspector-Unit 2 Bureau of Radiation Control c/c U. S, Nuclear Regulatory Commission Texas Department of Health P. O. Box 910 110 W.
89th St.
Bay City, TX 77414 Austin, TX.
78756-3189 J. R. Newman, Esquire Neeman & Holtzinger, P. C.
1615 L Street, N.W.
Washington, DC 20036 R. L. Range /R, P. Verret Central Power & Light Company P. O. Box 2121 Corpus Christi, TX 78403 R. John Miner (2 copies)
Chief Operating Officer City of Austin Electric Utility 721 Barton Springs Road Austin, TX 78704 R. J. Costello/M. T. Hardt City Public Service Board P. O. Box 1771 San nntonio, TX 70296 S3/LIC10/89181001 Revised 12/21/88 NL-DISR4 l
)
~
Houston Lighting & Power Company ST-HL-AE-3157 South Texas Pioject Electric Generating Station File No.:
G09.01, R5
(
UNITED STATES OF AMERICA NUCLEAR REGULATORY COMMISSION In the Matter
)
)
Houston Lighting & Power
)
Docket Nos. 50-498 Company, et al.,
)
50-499
)
South Texas Project
)
Units 1 and 2
)
AFFIDAVIT S. L. Rosen being duly sworn, hereby deposes and says that he is Vice President Nuclear Engineering and Construction, of Houston Lightiag & Power Company; that he is duly authorized to sign and file with the Nuc1 car Regulatory Commission the attached proposed revision to the Final Safety Analysis Report to incorporate the reanalysis of a design basis Rod Withdrawal from Sub-Critical Accident into the Units 1 and 2 licensing bases; is familiar with the content thereof; and that the matters set fort.h therein are true and correct to the best of his knowledge and belief.
S. f. Rosen I
Vice President, Nuclear Engineering & Construction STATE OF TEXAS
)
)
)
Subscribed and sworn to before me, a Notary Public in and for the State of Texas this 7Y day of tJ44.y
, 1989.
Iteus d
s k,,e w communn bom 143 93 tMtary Public in and for the State of Texas
,gwa S3/LIC10/89181001
ST-HL-AE-3157 Page 1 of 2 Description of Chance This FS m change incorporates the Reanalysis of the Uncontrolled Rod Cluster Control Assembly Bank Withdrawal from a Sub-Critical or Low Power Startup Condicion.
The Unit 1 Cycle 2 reactor core has been redesigned for a short cycle of 170 full power days. HL&P requested this short cycle to improve the two-unit relord schedules. The short cycle requires less new fuel than the previously planned annual fuel cycle.
Less new fuel results in slightly higher average burnup. The higher burnup reduces the negative Doppler only power defect at beginning of cycle from 1027 pcm for the annual cycle to 984 pcm for the redesigned Unit 1 Cycle 2.
The Doppler power defect is the mechanism that lis.its the peak power for rapid reactivity addition transients at zero power. These transients include the Rod Ejection and Rod Withdrawal from Sub-Critical.
The Rod Ejection accident has been analyzed using a Doppler only power defect of 900 pcm which bounds both the annual and redesigned cores.
Therefore, this change does not impact the results of this accident.
However, the previous analysis for the Rod Withdrawal from Sub-critical assumed a 1000 pcm.
Decreasing the negative Doppler only power defect to a value which bounds the Unit 1 Cycle 2 core design results in higher peak l
powers and a decrease in margin of safety as discussed below.
NUREG-0800, Revision 1, Section 14.4.1 recommends that the FSAR reviewer address the follouing parameters to ascertain the acceptable fuel design as identified in the General Design Requirement 10, 20 and 25:
The thermal margin limits (DNBR for PWRs and MCPR for BWRs) as specified in SRP Section 4.4, subscetion II.1 are met.
Fuel center line temperatures (for PWRs) as specified in SRP Section 4.2, subsection II.A.2 (a) and (b) do not exceed the melting point.
Uniform cladding strain (for BWRs) as specified in SRP Section 4.2, subsection II.A.2(b) do not exceed 1%.
Section 4.4 of the STPEGS FSAR states that the safety analysis DNBR limit is 1.27 using the WRB-1 Critical Heat Flux Correlation.
Section 4.2 states the design fuel center line temperature of 4700'F provides sufficient margin to ensure no fuel melting. Uniform clad strain analysis is not j
applicable to PWRs and therefore is not addressed with rega d to this transient. Therefore, the parameters which determine the margin of safety are the DNBR and fuel center line temperature.
The revised FSAR changes state that minimum DNBR at all times remain above the safety analysis limit. However, the fuel average temperature as shown in Figure 15.4-3A increases.
Fuel temperature increases can impact the fuel clad which is one of the physical barriers to guard against the uncontrolled release of radioactivity.
It is HL&P's position chat any increase in peak clad temperature or fuel temperatures is considered a reduction in margin in accordance with 10CFR50.59.
Therefore, the proposed change reduces the margin of safety as defined in the basis for any technical specification.
}
\\,.
Attachmsnt 1 l
~
ST-HL-AE-3157 Page 2 of 2' The results'of the analysis show that fuel failure does not occur because the peak temperature does not exceed the design limit of 4700'F.
]
Since fuel failure does not occur, there is no increase in radioactive dose j
release. Therefore, there is no increase in consequences, j
s3/LIc10/89181001
\\
h Attachmsnt 2 ST-HL-AE-3157 Page 1 of 1 K
. SAFETY EVALUATION FOR L
SIGNIFICANT HAZARDS CONSIDERATION l
Does:the proposed change:
1.
Involve a significant increase in the probability or consequences of an accident vreviousiv evaluated:
The FSAR changes are a description of changes to a previously analyzed accident.- Therefore, the change does not increase the probability of an accident. The accident analyzed is a Condition II. event. 'The Condition II design criteria prohibits fuel rod failures land RCS and l'
secondary system over pressurization.
Satisfying Condition II event L
design criteria precludes the release of radioactivity. The results of
.the analysis show that the design criteria is satisfied. Therefore',
there is no increase in consequences. This'is consistent with the criteria in FSAR Section 15.4.1.3.
2.
Create the possibility of a new or different kind of accident from any accident oreviousiv evaluated:
The FSAR changes are a description of changes to previously analyzed accidents.
The accident analyzed is a Condition II event. The Condit!.on II design criteria ensure that these events do not propagate
'to.cause a'more serious fault. The results of the analysis show that l
the design criteria is satisfied. Therefore, this change does not create the possibility of a different type of accident or malfunction.
3.
Involve a significant reduction in the marcin of safety:
The FSAR changes show an increase in fuel average temperature.
'NUREG-0800 identifies fuel temperature as a measure of fuel integrity.
Fuel temperature increases can impact the fuel clad which is one of the physical barriers to guard against the uncontrolled release of radioactivity.
It is HL&P's position that any increase in peak clad temperature or fuel temperatures is considered a reduction in margin in accordance with 10CFR50.59. This reduction is not considered significant since it has no effect on the consequences of an accident.
Based on the above, HL&P has determined there is no significant hazard consideration.
1 I
S3/LIC10/89181001 l
4 9
e FSAR CHANGES FOR REANALYSIS OF THE UNCONTROLLED ROD CLUSTER CONTROL ASSEMBLY BANK WITHDRAWAL FROM A SUB-CRITICAL OR LOW POWER STARTUP CONDITION S3/LIC10/89181001
_ _ _ _ _. _ _ _ _____= _ _ _.. _ _ _ _ _ _ _ _ _ _.... _
l