ML20206H314
| ML20206H314 | |
| Person / Time | |
|---|---|
| Site: | River Bend  |
| Issue date: | 05/05/1999 |
| From: | NRC (Affiliation Not Assigned) |
| To: | |
| Shared Package | |
| ML20206H310 | List: |
| References | |
| NUDOCS 9905110159 | |
| Download: ML20206H314 (5) | |
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UNITED STATES g
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. NUCLEAR RESULATORY COMMISSION WASHINGTON, D.C. asseMeet SAFETY EVA UATION BY THE OFFICE OF NUCI FAR REACTOR REGULATION RELATED TO AMENDMENT NO.106 TO FACILITY OPERATING LICENSE NO. NPF-47 ENTERGY OPERATIONS. INC.
RIVER BEND STATION. UNIT 1 DOCKET NO. 50-458 4
1.0 INTRODUCTION
By application dated October 8,1998, as supplemented by letter dated April 15,1999 Entergy Operations, Inc. (the licensee) requested changes to the Technical Specifications (TSs) for the River Bond Station, Unit 1 (River Bend). The proposed changes would implement the Boiling Water Reactor Owners Group (BWROG) Enhanced Option I-A for the reactor stability long-term solution to the neutronic and thermal hydraulic instability that is documented in NEDO 32339, Revision 1," Reactor Stability Long-Term Solution, Enhanced Option I-A." The amendment would delete the limits on power and flow conditions in the specification on recirculating loops operating, add two new specifications to the TSs to establish limits for fraction of core boiling boundary and the period based detection system, modify the surveillance requirements for reactor protection instrumentation, and add the NEDO document to the core operating limits report. The associated Bases pages are also revised to reflect the TS changes. By letter dated April 15,1999, the licensee provided additional information that did not change the initial proposed no significant hazards consideration determination originally published in the Federal Register on November 18,1998 (63 FR 64112).
I 2.0 EVALUATION j
i The proposed revisions are described as folle 4:
2.1 TS 3.2.4, Fraction of Core Boiling Boundary (FCBB)
The proposed change is to add a new TS 3.2.4, Fraction of Core Boiling Boundary (FCBB), and
. Its associated Bases to the sectiori under TS 3.2, Power Distribution Limits. The proposed new TS and Bases are consistent with those described in the BWROG Reactor Stability Long-Term Solution: Enhanced Option I A (Reference 2). However, modifications to the BWROG Bases in i
the proposed new Bases for River Bond include: (1) delete references to " Simulated Thermal
. Power High" on page B 3.2-14 under Applicability; (2) delete the wording " recirculation pump run back" on page B 3.2-15 under Actions B.1 and B.2, and on pages B 3.2-17 and B 3.2-18 under Surveillance Requirement (SR) 3.2.4; and (3) add the following wording to Actions B.1 and B.2 on page B 3.2-15, and to SR 3.2.4.1 on page B 3.2-17: 'This action to exit the Restricted Region is required following unplanned events that occur while operating in the region and can result in significant loss of stability margin. During such unplanned events, adherence to the FCBB limit cannot be assured. Therefore, continued operation in the restricted region is not appropriate."
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The FCBB is the ratio of the power generated in the lower fourth of the active reactor core to the power required to produce bulk saturated boiling of the coolant entering the fuel channels (Reference 2). The boiling boundary limit is established to ensure that the core remains stable during normal reactor operations in the Restricted Region of the power and flow operating domain, otherwise, the core may be susceptible to neutronic/ thermal hydraulic instability.
The associated operating limit, FCBB, is required to be met during operation in the Restricted Region and meets Criterion 2 of Title 10 of the Code of Federal Regulations.
Section 50.36(c)(2)(ii). Therefore, it la necessary to add a new specification (TS 3.2.4) to the Power Distribution Limits section of the TSs. In addition, the modifications to the BWROG generic EIA Bases are required for River Bend because: (1) River Bend will use the control rod block upscale alarm to define when it has entered the restricted region. This alarm is located on the control room front panel, in contrast to the simulated thermal power - high located at the back of the control room; (2) Recirculation pump run back is not applicable to River Bond; and (3) The action statement provides guidance to the operator to exit the restricted region following unplanned events that occur while operating in the region and can result in significant loss of stability margin. The staff has reviewed these proposed changes and finds them acceptable.
2.2 TS 3.3.1.1, Reactor Protection System Instrumentation The proposed changes to the SRs are (1) to renumber SR 3.3.1.1.18 as SR 3.3.1.1.3; (2) to 4
add Note 3 to SR 3.3.1.1.11 Function 2.b to exclude the digital components of the flow control trip reference (FCTR) card from the Channel Calibration; (3) to revise footnote (b) of Function 2.b in Table 3.3.1.1-1 to relocate the Allowable Value of the Average Power Range Monitor (APRM) flow biased scram function to the Core Operating Limits Report (COLR); and (4) to revise Bases B 3.3.1.1 including Applicable Safety Analyses, LCO [ limiting condition for operation), and Applicability 2.b, SR 3.3.1.1.3, SR 3.3.1.1.11, SR 3.3.1.1.13, and SR 3.3.1.1.17.
The proposed changes are based on two approved methodologies - NEDO-32339-A, Supplement 4, Revision 1, April 1998 (Reference 3), and NEDC-32339P-A, Supplement 3, Revision 1, " Reactor Stability Long Term Solution EIA: Flow Mapping Methodology," dated April 1998 (Reference 4), which is used to complete initial flow alignment process to establish the initial relationship between core flow and drive flow, then only periodic adjustment to the digital component of the FCTR is required. Furthermore, the use of digital components in the EIA FCTR card also allows the incorporation of self test features and more frequent internal checks, and the digital components used in the EIA FCTR card are highly reliable. The staff has reviewed the proposed change and finds it acceptable.
2.3 TS 3.3.1.3, Period Based Detection System (PBDS)
This proposed change adds a new TS 3.3.1.3, Period Based Detection System (PBDS), and its associated Bases B 3.3.1.3. The Bases includes the sections " Background,"" Applicable Safety Analyses," "LCO," " Applicability," " Actions," " Surveillance Requirements," and " References."
The licensee proposed removing the phrases " simulated thermal power - high" on pages B 3.3-43, -45, -46 and -47, and "which reduce recirculation flow" on page B 3.3-47.
The PBDS is a required feature of the EIA solution. The PBDS uses the neutron flux oscillation period confirmation process of the Period Based Algorithm (PBA) described in NEDO-31960-A
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. and NEDO-31960-A, Supplement 1 (Reference 5). Verification that the High-High Decay Ratio (Hi Hi DR) alarm is valid may be performed in the control room prior to the manual reactor scram using another output from the PSDS card, which generated the Hi-Hi DR alarm. The requirements of the ElA solution PBDS specification include immediate manual reactor scram without delay upon receipt of any valid PBDS channel Hi-Hi DR alarm while operating in regions of the power and flow operating domain potentially susceptible to neutronic/ thermal hydraulic Instability.
The PBA ElA (Reference 6 ) has no safety function and is not credited during any design-basis accident or transient analysis. However, during operation in regions of the operating domain potentially susceptible to instability under any operating conditions, the PBDS provides an indication that conditions consistent with a significant degradation in the stability performance of the reactor has occurred and the potential for imminent onset of neutron / thermal hydraulic instability may exist.
The staff has reviewed the proposed change and found it acceptable because the addition of this TS and its associated Bases is based on an approved methodology stated in the BWROG reactor stability long-term solution EIA (Reference 3) and deletion of the phrases listed would meet the River Bend's plant-specific application and match the actual design features of the APRMs.
2.4 TS 3.4.1, Recirculation Loops Operating These proposed changes include: (1) elimination of LCO 3.4.1.A.2, LCO 3.4.1.B.2 and 3, Actions C, D, E, F and G, SR 3.4.1.2 and their associated Bases; and (2) addition of NUREG-1434 /,ctions A and B as Actions C and D.
The staff has reviewed the proposed changes and found them acceptable. An approved methodology (Reference 3) and NUREG 1434 was used to implement the BWROG reactor stability EIA long term solution for RBS. Also, the elimination of the limits on power and flow conditions of the current TS 3.4.1 and the guidance of the BWROG Interim Corrective Actions (ICAs) is justified by the licensee based on several attributes of the EIA long term solution.
Operation in the region of the power and flow operating domain most susceptible to neutronic/ thermal hydraulic instabi.lity is automatically excluded from the licensed operating domain (Exclusion Region). Operation in the region of the power and flow operating domain potentially susceptible to neutronic/ thermal hydraulic instability in the absence of stability control (Restricted Region) requires implementation of stability control prior to entry and verification that at least one PBDS card is operable. These regions are established using the NRC accepted EIA methodology and reflect the plant specific design of River Bend.
2.5 TS 5.6.5, Core Operating Limits Report (COLR)
These proposed changes include the addition of items 4,5, and 6 to TS 5.6.5.a, and item 3 to TS 5.6.5.b.
The staff has reviewed the proposed changes and finds them acceptable. Proposed TSs LCO 3.2.4, Fraction of Core Boiling Boundary (FCBB), LCO 3.3.1.1, RPS [ Reactor Protection System] Instrumentation, and LCO 3.3.1.3, Period Based Detection System (PBDS), are
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'cycis specific parameters supported by an approved methodology listed in TS 5.6.5.b (NEDO-32339P A," Reactor Stability Long-term Solution: Enhanced Option I A," including Supplements 1 through 4 (April 1998)). Reference to this methodology was modified on TS page 5.0-19 to include all of its approved revisions.
On the basis of its evaluation, the staff concludes that the proposed changes to the TSs are acceptable for River Bond since the changes are analyzed based on the NRC-approved methodologies and the guidance stated in NUREG-1434. Additionally, the staff may elect to perform an on-site review of this plant-specific implementation of the BWROG reactor stability long-term EIA solution for River Bond.
3.0 STAFF CONCLUSION The staff has reviewed the request by the licenses to revise the River Bond TSs to implement its BWROG EIA reactor stability long-term solution. On the basis of its review, the staff concludes that these revisions are acceptable since approved methodologies were used. In addition, the reference to the approved methodology listed in TS 5.6.5.b was modified to include its approved revisions.
4.0 STATE CONSULTATION
In accordance with the Commission's regulations, the Louisiana State Official was notified of the proposed issuance of the amendment. The State official had no comments.
5.0 ENVIRONMENTAL CONSIDERATION
The amendment changes a requirement with respect to installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20 and changes surveillance requirements The NRC staff has determined that the amendment involves no significant increase in the amounts, and no significant change in the types, of any affluents that may be released offsite, and that there is no significant increase in individual or cumulative occupational radiation exposure. The Commission has previously issued a proposed finding that the amendment involves no significant hazards consideration, and there has been no public comment on such finding (63 FR 64112, November 18,1998). Accordingly, the 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 or environmental assessment need be prepared in connection with the issuance of the amendment.
6.0 CONCLUSION
The Commission 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, (2) such activities will be conducted in compliance with the Commission's regulations, and (3) the issuance of the amendment will not be inimical to the common defense and security or to the health and safety of the public.
Principal Contributor: T. Huang Date: May 5,1999
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REFERENCES Letter (RBGb593) from R. K. Edington to NRC, " River Bond Station - Unit 1, Docket 1.
No. 50-458, License No. NPF-47, License' Amendment Request (LAR) 98-02: " Stability,"
October 8,1998.
2.
NEDO-32339, Revision 1, Licensirag Topical Report, " Reactor Stability Long-Term Solution: Enhanced Option I A," GE Nuclear Energy, December 1998.
3.
NEDO-32339-A, Supplement 4, Revision 1, " Reactor Stability Long Term Solution:
Enhanced Option I-A Generic TSs," April 1998.
4.
NEDC-32339P-A, Supplement 3, Revision 1, " Reactor Stability Long Term Solution EIA:
Flow Mapping Methodology," GE Nuclear Energy, April 1998.
5.
NEDO-31980-A, Supplement 1, "BWR Owners' Group Long Term Stability Solutions Licensing Methodology," November 1995.
8.
NEDC-32339P-A, Supplement 2, Revision 1, " Reactor Stability Long-Term Solution:
Enhanced Option I-A: Solution Design," April 1998.
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