ML20236X124
| ML20236X124 | |
| Person / Time | |
|---|---|
| Site: | River Bend  |
| Issue date: | 10/26/1987 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20236X123 | List: |
| References | |
| NUDOCS 8712080437 | |
| Download: ML20236X124 (4) | |
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NUCLEAR REGULATORY COMMISSION
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SAFETY EVALUATION BY'THE OFFICE OF NUCLEAR REACTOR REGULATION SUPPORTING AMENDMENT NO. I3 TO FACILITY OPERATING LICENSE NO. NPF-47 GULF STATES UTILITIES COMPANY RIVER BEND STATION, UNIT 1 DOCKET NO. 50-458
-1.O INTRODUCTION By letter dated July 31, 1987, Gulf States Utilities Company (GSU) (the licensee).
submitted proposed system modifications to the River Bend Station Unit I required to meet the rule on Anticipated Transients Without Scram (AWS),10 CFR 50.62. This submittal addressed paragraphs 10 CFR 50.62(c)(3), (c)(4),
and (c)(5) which are applicable to boiling water reactors such as River: Bend-Station, Unit 1.
These paragraphs of the rule describe requirements for alternate rod insertion, standby liquid control system, and reactor o
recirculation pump trip.
In addition, by letter dated August 24, 1987, GSU requested an amendment to Facility Operating License No. NPF-47 for. River Bend Station, Unit 1.
The proposed amendment would modify the-River Bend Station Unit 1 Technical Specifications as a result of system modificat'.ons regarding 1
the use of boron, enriched in the isotope boron-10 (B-10), in the Standby
' Liquid Control System (SLCS).
This safety evaluation addresses the licensee's conformance with the requirements for the standby liquid control system and the proposed August 24, 1987 license amendment.
The staff's evaluation of alternate rod insertion and reactor recir-culation pump trip will be the subject of a separate safety evaluation.
2.0 EVALUATION o.
M.
The ATWS rule requires that the SLCS be equivalent in control capacity to a system with an 86 gpm injection rate, using 13 weight percent unenriched
,1 sodium pentaborate solution, in a system with a 251 inch diameter reactor vessel.
The 86 gpm injection rate in a 251 inch diameter vessel plant is equivalent to 66 gpm in a 218 inch diameter vessel. Of the several proposed approaches presented in the General Electric report (Ref.1) and approved in
.the NRC evaluation (Ref. 2), GSU has chosen to use enriched-(in B-10) boron.
Using the calculation methods of Reference 1 results in a minimum concentration of 6.5 weight percent sodium pentaborate when using an enrichment of 65 percent B-10 and a pump flow rate of 41.2 gpm and an equivalent required flow rate of 66 gpm for a 218 inch diameter vessel.
The concentration will be limited to a maximum of 9.5 percent by weight.
Instead of creating enriched sodium pentaborate by mixing boric acid and borax in water, the solution at River Bend will be 1
prepared by mixing enriched granular sodium pentaborate in water. This is 1
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w ~ The proposed change'to the Technica1' Specification surveillance requirements have been made to reflect the revised SLCS as-follows:
- 1.
The surveillance-requirements related to precipitation of sodium
'pentaborate including heat tracing and tank heaters as wel1~as Figure 3.1.5-1 illustrating saturation, temperature. have been deleted.
Also, the~
sodium pentaborate concentration in solution is limited to 9.5. weight percent.
Since the maximum concentration has been decreased to 9.5 weight percent, precipitation.of the sodiuo pentaborate will not occur at. normal ambient temperatures.
The saturation temperature of sodium pentaborate is less than 39 F which is less than the minimum ambient temperature of the SLC' tank room and therefore heat tracing. is not ' required and the deletion of the surveillance requirements is acceptable.
uirements have been changed and Figure The solution volume. surveillance req / concentration requirements has been 2.
3.1.5-2 illustrating solution' volume deleted. This is acceptable since the minimum volume is determined by calculation once per 31 days as a function of both concentration-and enrichment and the available volume of solution is verified to be greater
. than or equal to this minimum available. volume.
3.
The available weight of sodium pentaborate has been put in terms of B-10.
This is acceptable since B-10 is the isotope which provides reactivity control by neutron absorption.
4.
Surveillance requirements have been added to demonstrate compliance with 10 CFR 50.62 by calculations once per 31 days using analyzed concentration and enrichment values.
The B-10 enrichment of the solution will be determined anytime boron is added to the solution as this is the only way by which the enrichment would vary.
These additions are acceptable to the staff.
The NRC staff concludes that the licensee's proposed design for the SLCS and the associatedighnical Specification modifications meet the requirements of 10 CFR 50.62 anFtre acceptable.
3.0 ENVIRONMENTAL-CONSIDERATION This amendment ibvolves a change to a requirement with respect to the installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20 and/or changes to the surveillance requirements. The staff has determined that the amendment involves no l-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 signif-icant increase in individual or cumulative occupational radiation exposure.
The Commission has previously issued a proposed finding that this amendment involves no significant hazards consideration and there has been no public comment on such finding.
Accordingly, this amendment meets the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9).
Pursuant to 10 CFR 51.22(b), no environmental impact statement nor environ-mental assessment need be prepared in connection with the issuance of this amendment.
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L 4.0.' CONCLUSION The: staff has concluded, based on the. considerations. discussed'above, that:.(1) there is reasonable assurance.that.the health and. safety 1of the'public wil.1 not be endangered by operation in 'the proposed manner. and-
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.(2);such activities will be' conducted in compliance with the Commission's:
. regulations and,the issuance of this amendment will not be inimical to the
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common defense and security or to the. health.and.. safety'of the public.
~The. staff therefore concludes that the proposed changes are acceptable,,
and they are hereby incorporated into the River' Bend Unit 1 Technical Specifications.
- 9 Principal Contributors:
L. Kopp; j
Dated:-' October 26.1987 f
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5.0 REFERENCES
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1.
Anticipated Transients-Without Scram, Response. to. NRC ATWS Rule,~.10.CFR
,50.62,. NEDE-31096-P, General Electric-; Company, December '1985;.
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'" Acceptance for-Referencing of; Licensing Topical Report'NEDE-31096-P,i
- ' Anticipated' Transients,Without Scram; Response.to'NRC ATWS Rule,:110 CFR l50.62,'". letter from Gus Lainas to Terry A.' Pickens,' dated October.21, :
1986.
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