ML20066A035
| ML20066A035 | |
| Person / Time | |
|---|---|
| Site: | Browns Ferry  |
| Issue date: | 12/18/1990 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20066A032 | List: |
| References | |
| NUDOCS 9101020394 | |
| Download: ML20066A035 (3) | |
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ENCLOSURE 2 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION SUPPORTING AMENDMENT NO.181 TO FACILITY OPERATING LICENSE NO. DPR-52 TENNESSEE VALLEY AUTHORITY BROWNS FERRY NUCLEAR PLANT. UNIT 2 DOCKET NO. 50-2,60
1.0 INTRODUCTION
By letter from the Tennessee Valley Authority (the lit.ensee) to the NRC dated June B,1990, changes were proposed to the Browns Ferry Nuclear Unit 2 (BFN2)
Technical Specifications (TS) to permit operation with an extended load line limit (ELLL) on the power / flow map. The licensee's submittal included proposed Limiting Safety System Settings (LSSS), limiting Conditions for Operation (LCOs), Figure and Table changes to the BFN2 TS relating to neutror, flux scram trip settings and the limiting power / flow line.
Enclosed with the June 8 1990 letter was a re) ort discussing the technical analyses of the consequen,ces of operation in t1e ELLL to justify the proposed changes. The proposed changes are addressed individually in the following Safety Evaluation (SE) Section 2.0.
2.0 EVALUATION The licensee's submittal proposes an extension of the current allowed operating l
region on the reactor power / flow map via an extended load line limit analysis (ELLLA). The basis for the extension is described in supporting documentation provided by the licensee. Except for changes to the flow-biased neutron flux scram and rod block setpoints for ELLL and some Bases discussion changes, these changes require no other revisions to Cycle 6 TS.
Abnonaal Operation Transients Certain transien' of Chapter 15 of the BFN2 Final Safety Analysis Report (FSAR) were considered for the ELLL. The limiting transients reevaluated were generetor load rejection without turbine bypass (GLRWOB)Ially limiting G
'and feedwater flow controllerfailuretomaximumdemand(FWCF). The potent and FWCF events were evaluated at the power / flow conditions corresponding to the ELLL bounding point (100% power, B7% core flow). The results of the evaluation show that the operating limit minimum critical pwer ratios (OLMCPR) for the limiting transients are equal to or bounded by the current TS limits.
i The NRC finds that no changes to the allowable limits are required.
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. GeneralElectric(GE)hasalsoexaminedothereventsandaffectedsystem components related to the requested extensions. There include overpressure protection,LossofCoolantAccident(LOCA) events,pressuredifferentialsand vibration response on reactor internals and fuel assemblies.
The results show that design limits will not be exceeded. The containment LOCA response was analyzed and the results show no significant impact of the ELLL.
The LOCA analysis performed for the current licensing basis remains applicable.
The NRC review of these various GE examinations has concluded that suitable analyses were perfomed and the results show that operation with the extended load line region is either bounded by the licenser's reload-safety analysis or the results are less than the <lesign safety limits. The licensing safety analysis was approved in License Amendment 125 dated August 9,1986 and updated by Amendment 172 dated September 13, 1989.
Ifodification of Flow. Biased Average Power Range Monitor (APRM) Scram and Rod Block Trip Equations The ELLL proposal changes the APRM flux scram lines on the power / flow map and pemits operation up to the new APRM flux scram line (0.58W + 62%) and up to the intersection with the 100 percent power line occurring at a flow of 87 per-cent. This is a standard change for ELLL. The flow-biased rod block tri) equation is changed to 0.58W + 50% with a maximum value of 108%.
These c1anges are acceptable since they are consistent with the applicable design safety limits.
Technical Specification Changes for ELLL The proposed changes to the BFN2 TS are identified in the licensee's submittal.
The bases for the changes and the NRC conclusions are detailed in the previous SE Sections.
Changes to the Limiting Safety Systems Settings (LSSS) and Limiting Conditions S
for Operation (LCO) were proposed as follows:
(1) TS 2.1.A.1.a Neutron Flux Trip Settings A change is made to identify the proposed APRM flux scram trip setting as less than or equal to 0.58W + 625.
(2) TS 2.1.A.1.c Neutron Flux Trip Settings A change it made to identify the proposed APRM Rod Block trip setting as less than or equal to 0.58W + 50%.
(3) TS Figures 2.1 1 and 2.1-2 Figures are replaced with revised Figures to show the revised flow-biased scram and rod block lines based on e settingsinitems(1)and(2)above.quationsdevelopedfromthetrip (4) TS Table 3.2.c Instrumentation that Initiates Rod Blocks A change is made to identify the proposed APRM Upscale (Flow Bias) trip level setting.
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.3-(5) TS 3.5.L.1 Core and Containment Cooling Systems A revision is proposed to reflect tLe change in setpoint equations identi-fiedin(1)and(2)above.
Forchanges(1)through(5)above,theBasesdiscussionparagraphswere revised for consistency. The changes identified in the licensee's submittal are acceptable as proposed.
We have reviewed the information for operatiSn of the BFN2 with an extended operating region.
Based on this review, we conclude that appropriate documenta-tion was submitted to justify that operation.,under the proposed TS changes will be within existing design limits. T1us, the (proposed TS changes are acceptable.
3.0 ENVIRONMENTAL. CONSIDERATION This amendment involves a changa to a requirement with re:pect to the installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20. The staff has determined that the amendment involves no significant increase in the amour.ts, and no significant change in the types, of any effluents that may be reletsed offsite, and that there is no significant increase in individual or cmoulative occupational radiation exposure. The Commission has previous 1y issued a proposed finding that this amendment involves no significant hazards consideration and there has been no public comment on such finding. Accordingly, the amendment meets the eli criteriaforcategoricalexclusionsetforthin10CFR51.22(c)(9)ghility Pursuant to10CFR51.22(b) no environmental im)act statement nor environmental assess-ment need be prepar,ed in connection wit 1 the issuance of the amendment.
4.0 CONAllS10N The Itaff has concluded, based on the considerations discussed above, that:
1 (1) there is reasonable assurance that the health and safet of the public will not be endangered by operation in the proposed manner,y(2) such activities will be conducted in compliance with the Comission's regulations, and (3) the issuance of the amendments will not be inimical to the common defense and security nor to the health and safety of the public.
Principal Contributor:
M. McCoy Dated: December 18, 1990 l
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