ML20198P951
| ML20198P951 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 12/24/1997 |
| From: | NRC (Affiliation Not Assigned) |
| To: | |
| Shared Package | |
| ML20198P942 | List: |
| References | |
| NUDOCS 9801220299 | |
| Download: ML20198P951 (4) | |
Text
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NUCLEAR REGULATORY COMMlSSION
'2 WASHINGTON, o.C. 30046-0001
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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULAT10M RELATED TO AMENDMENT NO.155 TO FACILITY OPERATING LICENSE NO. NPF-49 NORTHEAST NUCLEAR ENERGY COMPANY. ET AL.
MILLSTONE NUCLEAR POWER STATION. UNIT NO. 3 DOCKET NO. 50-43
1.0 INTRODUCTION
By "B16624, Application for Amend to License NPF-49,proposing Changes That Will Affect Nominal Trip Setpoints & Allowable Values. Proprietary Rev 5 to WCAP-10991 & non-proprietary Rev 5 to WCAP-10992,encl.Proprietary Rept Withheld,Per [[CFR" contains a listed "[" character as part of the property label and has therefore been classified as invalid..790|letter dated October 15, 1997]], the Northeast Nuclear Energy Company, et al.
(the licensee), submitted a request for changes to the Millstone Nuclear Power Station, Unit No. 3 Technical Specifications (TS). TS Surveillances 4.1.2.3.1, 4.1.2.4.1, 4.5.2, 4.6.2.1, and 4.6.2.2 require the recirculation spray, quench spray, residual heat removal, centrifugal charging, and safety injection pumps to be tested on a periodic basis and after modifications that alter subsystem flow characteristics. The proposed changes to these surveillances include replacing the specific surveillance pump pressure with a statement that the test be conducted in accordance with TS 4.0.5, Inservice Testing (IST) Program. The proposed changes also include a decrease in the required individual safety injection and centrifugal charging pump injection line flow rates, an increase in the allowed individual safety injection pump runout flow rata, and editorial changes to the surveillances.
2.0 BACKGROVND in its "B16624, Application for Amend to License NPF-49,proposing Changes That Will Affect Nominal Trip Setpoints & Allowable Values. Proprietary Rev 5 to WCAP-10991 & non-proprietary Rev 5 to WCAP-10992,encl.Proprietary Rept Withheld,Per [[CFR" contains a listed "[" character as part of the property label and has therefore been classified as invalid..790|letter dated October 15, 1997]], the licensee stated that throttle valves are used in the centrifugal charging and safety injection lines to limit maximum injection flow to preclude pump runout, balance the resistance in the lines, and enrure minimum injection to support design bases analyses.
The licensee stated that nigh velocities through the throttle valves in their current throttled position could cause valve erasion; therefore, the licensee is adding an additional flow resistance, a restricting orifice, to 8 of the 12 injection lines so that the throttle valves can be opened farther. The licensee stated that opening the throttle valve will reduce the velocity through the valves so that valve erosion will not be a concern. The licensee further stated that the sizing of the restricting orifices and the associated rethrottling of the throttle valves will be done in accordance with Regulatory Guide 1.82, " Sumps for Emergency Core Cooling and Containment Spray Systems,"
in that the openings will be larger than the sump screen mesh opening size.
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9901220299 971224 PDR ADOCK 05000423 P
.. 3.0 EVALUATION In its "B16624, Application for Amend to License NPF-49,proposing Changes That Will Affect Nominal Trip Setpoints & Allowable Values. Proprietary Rev 5 to WCAP-10991 & non-proprietary Rev 5 to WCAP-10992,encl.Proprietary Rept Withheld,Per [[CFR" contains a listed "[" character as part of the property label and has therefore been classified as invalid..790|letter dated October 15, 1997]], the licenseo stated, due to the modifications described above, that (1) the requirements of surveillances 4.1.2.3.1, 4.1.2.4.1, 4.5.2.f, 4.6.2.1.b, and 4.6.2.2.b are being replaced with a statement that the test be conducted in accordance with the IST Program, (2) the requirements of surveillance 4.5.2.h are being modified to decrease the required individuF centrifugal charging pump injection line flow rate sum from 339 gallons per minute (gpm) to 310.5 gpm and the safety injection pump line flow rate sum from 442.5 gpm to 423.4 gpm, and (3) the requirements of surveillance 4.5.2.h are being modified to increase the required individual safety injection pump total flow rate for Pump A from 670 gpm to 675 gpm and for Pump B frca 650 gpm to 675 gpm.
3.1 TS 4.1.2.3.1. 4.1.2.4.1. 4.5.2.f. 4.6.2.1.b. and 4.6.2.2.b (Differential Pressure)
These TS currently require that the recirculation spray, quench spray, residual heat removal, centrifugal charging, and safety injection pumps be.
demonstrated operable by verifying that a differential pressure across the pump of greater than or equal to a specific value is developed when tested pursuant to TS 4.0.5.
In the "B16624, Application for Amend to License NPF-49,proposing Changes That Will Affect Nominal Trip Setpoints & Allowable Values. Proprietary Rev 5 to WCAP-10991 & non-proprietary Rev 5 to WCAP-10992,encl.Proprietary Rept Withheld,Per [[CFR" contains a listed "[" character as part of the property label and has therefore been classified as invalid..790|October 15, 1997, letter]], the licensee stated that the numerical surveillance acceptance criteria for these pumps is being removed from the TS and is being replaced with a statement that the test be conducted in accordance with the IST Program. The licensee further stated thht the acceptance criteria used in the IST Program will still, at a minimum, provide assurance that the assumptions in the design basis analysis are valid.
Periodic surveillance testing of emergency core cooling system (ECCS) pumps to detect gross degradation caused by impeller structural dan. age or other hydraulic component problems is required by Section XI of the ASME Code. This type of testing may be accomplished by measuring the pump developed head at only one point of the pump characteristic curve.
This verifies both that the measured performance is within an acceptable tolerance of the original pump baseline performance and that the performance at the test flow is greater than or equal to the perfermance assumed in the plant safety analysis.
Surveillance require'nents are specified in the IST Program, which encompassesSection XI of the ASME Code.
Section XI of the ASME Code provides the activities :nd frequencies necessary to satisfy the requirements.
The NRC staff has reviewed the change and finds the reference to the IST Program acceptable in that the surveillance will continue to provide assurance that the pumps will operate consistent with system evaluations, design basis assumptions, and it will provide assurance that the pumps will perform their intended safety function. Consistent with 10 CFR 50.36(c)(3), the reference to the IST Program is sufficient to assure maintenance of the necessary quality of plant systems and components and that the limiting conditions of operation will be met. The-staff also notes that the change to reference the Millstone Unit 3 IST Program is consistent with the Westinghouse Standard Mechnical Specifications (NUREG-1431).
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- The changelin the referenced units-from differential pressure across'the pump t
to developed head is editiorial-~ and -allows the licensee'to; account ~ for'the
- effect of water density _on pump performance during_each test._ The NRCistaff finds the change acceptable..
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3.2 TS-4.5.2.h (Line Flow Rate Sum)
The TS currently. require, in part, that the ECCS system be determined cXrable i
by performing a flow balance test following com>1etion of modifications to the ECCS subsystems that alter the subsystem flow ciaracteristics and verifying-that: (1) for the: charging pump linas, with-a single pump _ running, that the i;
sum of the injection line flow rates, excluding the highest flow rate, is:
greater than or equal to 339 gpm, and (2) for the safety injection pump lines,
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F with a single pump running, that the sum of the injection line flow rates, excluding the highest flow rate, is greater than or equal to 442.5 gpm.
By letter dated October. 15, 1997,-the licensee proposed-that the charging. pump injection line flow rate sum be reduced to 310.5 gpm and that the-safety injection pop line flow rate sum be reduced to 423.4 gpm.
4 The licensee-stated that the changes to. decrease the required surveillance minimum flow rates for the centrifugal charging and safety injection pumps are F
consistent with the current Final Safety Analysis Report (FSAR) licensing basis analyses for Millstone Unit 3.- Specifically, the new minimum flows are
. consistent with the minimum safeguards flow data that is used in the FSAR Chapter 15 accident analysis. The minimum flow requirements are established i
by the injection phase of a loss-of-coolant accident (LOCA) when the pump r'
-suction. source is the refueling water storage tank (RWST).
The.NRC-staff finds the change in minimum flow rate for the centrifugal charging and. safety injection pumps acceptable in that the change reflects the flows' that.are presently used in thi design analyses, the surveillance continues to provide the necessary assurance that the pumps will function consistent with the flows used in the accident analyses, and surveillance
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continues to provide assurance that the pumps will perform their intended L
safety function.
I 3.3
'TS 4.5.2.h -(Total Flow Rate)
- The TS currently require, in part, that the ECCS-system be determined operable by performing a flow balance test following completion of modifications to the ECCS. subsystems that alter the subsystem flow characteristics and verifying that for_the safety injection pump lines, with a single pump running,_the total pump flow rate is less than or equal to 670 gpm~for the A pump and 650 g >m.for the B pump : By. "B16624, Application for Amend to License NPF-49,proposing Changes That Will Affect Nominal Trip Setpoints & Allowable Values. Proprietary Rev 5 to WCAP-10991 & non-proprietary Rev 5 to WCAP-10992,encl.Proprietary Rept Withheld,Per [[CFR" contains a listed "[" character as part of the property label and has therefore been classified as invalid..790|letter dated October 15, 1997]], the licensee proposed.
t1at;the individual-safety injection pump total flow rate-for both. pumps A and
-B oe increased to 675 gpm.
.The_ licensee stated that-the maximum flow requirements are established during
=the-recirculation phase:of.a LOCA_when the suction source of the pumps is the
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recirculation spray-pumps that provide =a head boost to the safety injection pumps. - This increase in flow between maximum and minimum requirements caused E
by widening.the band will incree:e the design window, thereby, allowing for-t
? adequate' pump performance margin, which had been limited because the original design di_d-:'not: adequately eval _uate the head boost.
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_4, The licensee stated that the maximum flow for the safety injection pump is consistent with the runout limitations established by the pump vendor.
Safety injection pump operation at a higher allowed maximum flow requires a larger pump net positive suction head (NPSH). The higher NPSH required is below the minimum NPSH available both during injection when the suction source is the RWST and during recirculation when the suction source is the recirculation spray pumps.
The licensee also noted that the safety injection pumps are disabled so that they cannot be an injection source when the cold overpressure system is required to be operable which means that the increase in maximum flow does not affect the cold overpressure accident analysis.
The NRC staff finds the change in maximum total flow rate for the safety injection pumps acceptable in t, hat the change is consistent with the flows
- that are presently used in tne design analyses, the surveillance continues to provide the necessary assurance that the pumps will function consistent with the flows used in the accident analyses, the flow rate is consistent with vendor recommendations, and the surveillance continues to provide assurance that the pumps will perform their intended safety function.
4.0 STATE CONSVLTATION in accordance with the Commission's regulations, the Connecticut State official was notified of the proposed issuance of the amendment.
The State official had no comments.
5.0 ENVIRONMENTAL CONSIDERATION
The amendment 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 effluents 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 (62 FR 59918). Accordingly, the amendmer+ 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: J. Andersen Date:
December 24, 1997
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