ML20149H294
| ML20149H294 | |
| Person / Time | |
|---|---|
| Site: | River Bend  |
| Issue date: | 02/11/1988 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20149H293 | List: |
| References | |
| NUDOCS 8802190204 | |
| Download: ML20149H294 (4) | |
Text
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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION SUPPORTING AMENDMENT NO.18 TO FACILITY OPERATING LICENSE NO. NPF-47 GULF STATES UTILITIES COMPANY RIVER BEND STATION, UNIT 1 DOCKET N0. 50-458
1.0 INTRODUCTION
By letter dated August 5, 1987, as supplemented November 23, 1987, Gulf States Utilities Company (GSU) (the licensee) requested an amendment to facility Operating License Ao. NPF-47 for the River Bend Station, Unit 1.
The proposed amendment would revise the total predicted structural settlement for two settlement markers.
The licensee has been monitoring the settlement of major Category I structures in accordance with the River Bend Station (RBS) Technical Specifications (TSs). The settlement values specified in the TSs are limits based on assumptions made in the static design of the major safety related structures. Monitoring of the settlement is required to confirm that the limits are not exceeded. The licensee's proposed amendment would change the predicted total settlement values of Marker No. 28 in E-Tunnel and Marker No. 34 in G-Tunnel. The E-Tunnel is adjacent to the Unit I Reactor Building and the G-Tunnel runs from near the Unit 1 Fuel Building to the cancelled. Unit 2 area.
The G-Tunnel was to be used to interconnect the Standby Cooling Tower (SCT) loops of Units 1 and 2.
Since Unit 2 has been cancelled the safety related piping in the G-Tunnel has been terminated near the Unit 1 SCT.
Settlement Marker No. 34 is located near the terminated (west) end of the G-Tunnel at least 150 feet from any safety related equipment.
The total predicted settlements for Marker Nos. 28 and 34 shown in Table 3.7.10-1 of the RBS Technical Specifications are 3.8 inches and 0.4 inch, respectively. Actual measurements at Marker No. 34 have indicated settlement values much higher that the TS limit, while at Marker No. 28 the measured settlement is within the limit. The licensee has now proposed to change the TS settlement limits to 3.3 inches and 1.3 inches respectively at these markers based on the actual measurements and l
theoretical calculations (Ref. 1). This safety evaluation gives the j
results of the staff review of the licensee's submittals (Refs.1, 2, 3 and4). References 2 and 3 are Special Reports on the settlement of Marker No. 34 submitted in accordance with the provisions of the TSs.
2.0 EVALUATION 2.1 Settlement at Marker _ No. 34 Although the original prediction of total settlement at Marker No. 34 was only 0.4 inch, actual measurements at the marker from June 1985 8802190204 800211 PDR ADOCK 05000458
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. through October 1987 have shown settlement values ranging from 0.85 inch to 1.03 inches (Ref. 3). Since the measured values have exceeded the Technical Specification limits, the licensee seeks to change the TS limit to 1.3 inches based on the following factors described in Reference 1:
1)
The original theoretical calculation indicated a total settle-ment of 1.32 inches at the location of Marker No. 34 at the west end of G-Tunnel (Ref. 4). The licensee, however, adjusted this value to 0.4 inch assuming that the G-Tunnel had already settled about 0.9 inch due to loads imposed in adjacent areas before measurements were initiated at this location (Ref. 5, p. 2.5 109a). The value of 0.9 inch is the same as the settlement measured at Marker Nu. 32 (which is the closest to Marker No.
- 34) before readings were initiated at Marker No. 34. The licensee has belatedly recognized that the assumption of prior settlement of 0.9 inch at Marker No. 34 was overly conservative (Ref. 1).
2)
There is no safety related equipment within at least 150 feet of Marker No. 34. Since this marker is located at the west end of the G-Tunnel, which is near the unconstructed Unit 2, the settlement of Marker No. 34 is of no concern with respect to differential settlement.
3)
Since the proposed TS limit of 1.3 inches for the total settlement of Marker No. 34 is within the previously calculated value of 1.32 inches (Refs.1 and 4), it does not involve a design change or physical change in the plant.
The staff's review of the licensee's submittals (Refs. 1, 2, 3, and
- 4) indicates that the settlement readings at Marker No. 34 have been gradually approaching a value of about 1.0 inch and have remained stable near that value for the past two years. The roof of the G-Tunnel was completed in the Spring of 1982 (Ref. 5 Fig. 2.5-106).
During a teleconference with the licensee's staff on December 1, 1987, the NRC staff was informed that a walkdown along the G-Tunnel did not indicate any structural distress in the tunnel except for minor hairline cracks common in concrete structures. The staff also finds that the licensee's original assumption of 0.9 inch prior settlement was overly conservative and that the proposed value of 1.3 inches total settlement is reasonable. This proposed value is less than the 1.32 inches settlement originally calculated by the licensee. Therefore, although the settlement measured by the licen-see exceeds the current TS value of 0.4 inch, the proposed limit of 1.3 inches based on the licensee's original calculations, has not been exceeded. Thus, no adverse impact on G tunnel is anticipated and, to date, none has been observed; hence, the staff finds that there has been no adverse impact on Unit No.1 related to the settlement of G tunnel at Marker No. 34.
Further, because Marker No. 34 has already settled about 1.0 inch., the proposed total settlement of 1.3 inches
ri,
. will limit any additional allowable settlement to 0.3 inch. Because there is no safety related equipment within at least 150 feet of Marker No. 34 it is the staff's judgement that there will not be any adverse impact on Unit No. I should Marker No. 34 settle this additional 0.3 inch. Based on these factors, the staff finds that the licensee's proposed change in the TS limit of total settlement at Marker No. 34 from 0.4 inch to 1.3 inches is acceptable.
2.2 Settlement at Marker No. 28 With regard to the change in the predicted total settlement from 3.8 inches to 3.3 inches at Marker No. 28. the licensee states that the higher figure was erroneously entered in Table 3.7.10-1 of the TSs. The lower value provides a conservative limit compared to the higher value.
The staff finds that this change is acceptable.
3.0
SUMMARY
Based on a review of the licensee's submittals (References 1, 2. 3. and
- 4) justifying its proposed changes in the Technical Specification Table 3.7.10-1, the staff agrees with the licensee's basis for the proposed changes in predicted total settlements for Marker Nos. 34 and 28 in i
G-Tunnel and E-Tunnel, respectively; i.e., from 0.4 inch to 1.3 inches for Harker No. 34 and from 3.8 inches to 3.3 inches for Marker No. 28.
I Accordingly, the staff concludes that the proposed changes are acceptable.
j
4.0 ENVIRONMENTAL CONSIDERATION
This amendment involves a change to a requirement with respect to the installation or use of a f acility component located within the restricted I
area as defined in 10 CFR Part 20 and/or changes to the surveillance requirements. The staff has determined that the amendment involves no significant increase in the amounts, and no significant change in the types, of any effluents that may be released offsite, and that there is no significant increase in individual or cumulative occupational radiation exposures. The Connission has previously issued a proposed finding that the amendment involves no significant hazards censideration and there has been no public comment on such finding. Accordingly. the craendment meets the eligibility criteria for categorical exclusion set forth in 10 CFR j
Section51.22(c)(9).
Pursuant to 10 CFR 51.22(b). no envirordnental impact I
statement or environmental assessment need be prepared in connection with the issuance of the amendment.
5.0 CONCLUSION
The staff has concluded, based on the considerations discussed above, that:
(1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, and (2) such activities will be conducted in compliance with the Commission's regulations, and the issuance of the amendment will not be inimical to the connon defense and security or to the health and safety of tha public.
The staff therefore concludes that the proposed changt.s are acceptable, and they are hereby incorporated into the River Bend Unit 1 Technical Specifications.
6.0 REFERENCES
1.
Letter dated August 5, 1987 from J. C. Deddens, GSU to NRC,
. subject: River Bend Station Unit 1. Docket No. 50-458, Settlement Monitoring.
2.
Letter dated August 10, 1987 from J. C. Deddens, GSU to NRC, subject: River Bend Station Unit 1. Docket No. 50-458, Special Report.
3.
Letter dated November 2, 1987 from J. C. Deddens, GSU to NRC, subject: River Bend Station Unit 1. Docket No. 50-458, Special Report.
4.
Letter dated November 23, 1987 from J. E. Booker, GSU to NRC, subject:
River Bend Station - Unit 1, Docket No. 50-458.
5.
River Bend Station Final Safety Analysis Report (FSAR) Section 2.5.4.13.2.2.
Principal Contributor:
R. Pichuc.ani Dated: February ll, 1988
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