ML17312A745
| ML17312A745 | |
| Person / Time | |
|---|---|
| Site: | Palo Verde  |
| Issue date: | 04/30/1996 |
| From: | NRC (Affiliation Not Assigned) |
| To: | |
| Shared Package | |
| ML17312A744 | List: |
| References | |
| NUDOCS 9605090245 | |
| Download: ML17312A745 (12) | |
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UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, O.C. 2055&0001, b
S F
VA U 0
Y T OFF C
UC R
R AC GU AT ON.
NT 0.
106 0
N 98 TO'A G'
C NS NO.
NPF-41'G L C NS 0
NPF-51 M
NO. "8 TO F
C 0
TING C
UB IC PA ET A PA 0 VERDE UCL AR GENERATING STATION UNIT NOS.
1 2
AND 3 DOCKE OS.
STN 50-528 S
N 50-529 AND STN 50-530
- 1. 0 JIITIUCl By application dated February 1,
1996, the Arizona Public Service Company (APS or the l.icensee) requested changes to the Technical Specifications (TS)'Appendix A to Facility Operating License Nos.
NPF-41, NPF-51, and NPF-74, respectively) for the Palo Verde Nuclear Generating Station (PVNGS), Units 1, 2,
and 3.
APS submitted this request on behalf of itself, the Salt River Project Agricultural Improvement and Power District, Southern California
-Edison
- Company, El Paso Electric Company, Public Service Company of New
- Mexico, Los Angeles Department of Water and Power, and Southern California Public Power Authority.
These amendments would (1) revise TS Sections 3/4.1.1.1, 6.9.1.9, and 6.9.1.10 to relocate the shutdown margin (reactor trip.breakers open). to the Core Operating Limits Report (COLR); (2) revise TS 3/4.3.2 (Tables 3.3-3 and 3.3-4) to specify an additional restriction for the allowed low-pressurizer-pressure trip setpoint when reducing reactor coolant system (RCS) pressure in Mode 3; (3) revise TS Section 2.2.1 (Table 2.2-1) to make it consistent with the footnote in TS Tables 3.3-3 and 3.3-4; and (4) revise TS Sections 3/4.5.2 and 3/4.5.3 to require two emergency core cooling, system (ECCS) subsystems to be operable in Mode, 3. whenever.
the RCS cold-leg temperature
.is:equal to"or above 485 F.
The Table of Contents and the Bases would also be revised to reflect these changes.
2.0 U T The licensee's proposed changes would result in TS requirements that reflect the more conservative assumptions of the updated
.PVNGS Mode 3 safety analysis, as described in Licensee Event Report (LER) 95-002-01, which the licensee submi.tted to the U.S.,Nuclear-Regulatory Commission'NRC)'n August 25, 1995.
-As described in the LER, the l:icensee has administrative controls in place to ensure plant operation within the safety analysis, assumptions.
The changes requested by the licensee are as follows.
9605090245
'760430 PDR ADQCK 05000528 P
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Rev'se T
3
. l. 1.
.9 nd TS 6.9. 1. 10 to relocate the "shutdown margin reactor trip.breakers open" to the COLR.
The revision of TS 3/4.1. 1.1 relocates the "shutdown margin reactor trip breakers open" to. the..COLR.,
This revision also, ensures.
a-minimum shutdown:
margin that is sufficient to avoid unacceptable accident consequences to the fuel or the reactor coolant system (RCS) as a result of a design-basis accident or an anticipated operational occurrence when the reactor trip breakers are open.
TS 6.9. 1,.9 lists the core operati'ng limits that must be established and documented in the COLR.
TS 6.9'. 1. 10 lists the analytical methods used to determine the core operating limits that are listed-in TS 6.9. 1.9.
TS 6.9. 1.9 and 6.9. 1. 10 would also be revised to add this shutdown margin limit to the list of limits required in the COLR and to specify the analytical method used to determine this limit.-
Following relocation to the COLR, the '"shutdown margin - reactor trip breakers open" would be updated to reflect the more restrictive limit identified in the updated Mode 3 steamline break analysis.
This analysis was performed using the NRC-approved analytical method listed in TS 6.9. 1. 10.b, "The ROCS and DIT Computer Codes for Nuclear Design,"
CENPD-266-P-A, April 1983.
This change would also allow the licensee to revise this shutdown margin to reflect future cycle-specifi'c limits determined using NRC-approved methods without the need for a license amendment.
Also, the shutdown margin requirement-of-TS 3. 1. 1.2 was relocated to the COLR in TS Amendments 69, 55, and 42 for PVNGS Units 1, 2,
and 3, respectively, dated December 30, 1992.
Generic Letter (GL) 88-16 identified the shutdown margin as one of the cycle-specific parameters that would be appropriately relocated to the COLR.
GL 88-16 stated that if these limits are developed using an NRC-approved methodology, it would ensure that the values of cycle-specific parameters are determined consistent with plant safety analyses and design basis and provide for safe operation.
The staff has reviewed the licensee's'proposed changes to TS Sections TS 3/4. l.l. 1, TS 6.9. 1.9, and TS 6.9. 1. 10, relocating the "shutdown margin reactor trip breakers open" to, the
Rev'se the f otnote in T 4.3.
Tables 3.3-3 and 3.3-4 to add a new requirement that the "pressurizer pressure - low"trip setpoint" must be maintained higher than 140 psi above the saturation pressure corresponding to the RCS cold-leg temperature, when the cold-leg temperature is equal to or above 485'F while pressurizer pressure is reduced in Modes 3 and 4.
TS 3/4.3.2, Table 3.3-3, specifies the engineered safety features actuation system
.(ESFAS) instrumentation required by TS 3.3.2 to protect against violating core design limits and RCS pressure boundary during. anticipated operational occurrences and to limit consequences during accidents.
TS 3/4.3.2, Table 3.3-4, specifies the trip setpoint values for the
- ESFAS, instrumentation listed in Table 3.3-3.
(gi
Footnote a of Table 3.3-3 and footnote I of Table 3.3-4 (the footnotes are identical) permit the "pressurizer pressure low setpoint value" to be decreased manually as the RCS,is depressurized in Modes 3 and 4 to allow for control.led depressurization of=the RCS without...causing-.an unnecessary reactor
- trip, a containment isolation"actuation signal (CIAS), or,a. safety injection, actuation signal.
The footnotes also require the setpoint to be automatically increased when repressurizing to ensure protection is appropriately restored.
These identical footnotes apply to the low-pressurizer-pressure
- setpoint, which provides the trip signals for the reactor protective system, safety injection actuation, and containment isolation actuation.
Specifically, the proposed changes would add to these footnotes a restriction that requires the low-pressurizer-pressure trip setpoint be at least 140 psi greater than the saturation pressure corresponding to the RCS cold-leg temperature, when the RCS cold-leg temperature is greater than or equal to 485'F.
The Bases for these TS sections would also be revised to describe the basis'for the new restriction.
In Unit I TS, footnote I of Table 3.3-4 should be changed from "In Modes 3-6..." to "In Modes 3-4..."
This change will correct a
typographical error to make this footnote consistent with related footnotes in Unit I TS and the same footnote in the TS of the other units.
These changes impose additional, more restrictive requirements to ensure that safety injection will be actuated before the RCS pressure drops to the reactor vessel upper head saturation pressure during RCS depressurization following a steamline
- break, as credited in the Mode 3 steamline break safety analysis.
This requirement is necessary to protect the core and the RCS by ensuring that negative reactivity is added to, the core by safety injection to counter the positive reactivity being added as a result of the cooling of the RCS during a
steamline break.
A steamline break in'ode 3 when the RCS cold-leg temperature is less than 485 F would not require the insertion of negative reactivity from safety injection, since the positive reactivity added as a
result of cooldown in this situation would not be enough to overcome the shutdown margin and would have unacceptable consequences.
The "pressurizer pressure low trip signal" also initiates CIAS (the revised footnotes are referenced by the CIAS ESFAS instrumentation in TS Tables 3.3-3 and 3.3-4).
The additional restriction to keep the trip setpoint higher than 140 psi above the'saturation pressure corresponding to the cold-leg temperature will not"prevent the initiation of CIAS when needed. according to the safety analyses and will. not. cause an.ini.tiation of CIAS..that would be contrary to the safety analyses.
The 485 F lower threshold for the proposed requirement is an indicated value that accounts for a 15 F instrumentation uncertainty.
The 140-psi requirement is also an indicated value that accounts for uncertainties in both pressure and temperature instrumentation.
This change is required to reflect the Mode 3 safety analysis'ssumption that safety injection would be actuated at a pressure above the reactor vessel upper head saturation pressure during RCS depressurization following a steam-line break.
This actuation is necessary because if a steamline break occurred
in Mode 3 and the RCS depressurized below the RCS cold-leg, saturation temperature before initiation of safety injection, a steam void could form in the reactor
- vessel, upper head region.
This steam void could act-.to keep the RCS pressurized above"the safety injection setpoint,.
even though the RCS coolant would continue to be cooled.
The RCS cool.ing would add positive reactivity as a result of the..negative.moderator temperature coeffici'ent.
This situation could result in potentially unacceptable consequences if. safety injection was not actuated to provide negative reactivity.
The staff has reviewed the proposed changes to the footnote in TS 3/4.3.2, Tables 3.3-3 and 3.3-4, and on the basis of its evaluation finds the changes acceptable.
,, the "pressurizer pressure - low" footnote, to make it consistent with the revised footnotes in TS Tables 3.3-3 and 3.3-4.
TS Table 2.2-1 specifies the reactor protective instrumentation trip setpoint limits required by TS 2.2. 1 to protect against violating core design limits and the RCS pressure boundary during anticipated operational occurrences and to assist the engineered safety features systems in mitigating accidents.
Specifically, footnote 2 of this table permits the "pressurizer pressure - low setpoint value" to be decreased as the RCS is depressurized in Modes 3 and 4.
This process allows for controlled depressurization of the, RCS whi.le still maintaining an active trip setpoint until the trip signal, is no longer needed to protect the plant.
The footnote also requires the setpoint to be automatically increased when repressurizing to ensure protection is appropriately restored.
The "pressurizer pressure low trip signal" also
.actuates safety injection and'ontainment isolation.
The "pressurizer pressure low trip signal" also initiates a reactor trip from the reactor protection system.
The additional restriction to keep the trip setpoint higher than 140 psi above the saturation pressure corresponding to the cold-leg temperature will not prevent a reactor trip when needed according to the safety analyses and will not cause a reactor trip that would be contrary to the safety analyses.
This change is required to make this footnote consistent with the footnotes on the ESFAS Instrumentation Tables.
The source of the "pressurizer pressure-low trip signal" for the reactor protective instrumentation is the same as that for the ESFAS instrumentation, and any operational requirements should be the same.
The staff has reviewed this. proposedchange and finds it acceptable.
v' 4.
TS 3 4.5. 'ootnotes for applicability and add the requirement that two ECCS subsystems must be operable in Mode 3 when the RCS cold-leg temperature is greater than or equal to 485'F.
These changes are required so that the TS titles more accurately reflect the TS applicability.
TS 3/4.5.2 is applicable in Modes 1 and 2 at al.l'imes and in Mode 3 when the pressurizer"pressure is greater than or"equal,.to; 1837 psia and when the RCS cold-leg temperature is greater than or equal to 485 F.
Since th'e applicability of these two TS is split at 1837 psia in Mode 3 and 485 F, the 350 F statement in the TS titles is not appropriate and is
4
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inconsistent with its applications.
The terms "operating" and "shutdown,"
as requested for the new titles, will. increase clarity and are consistent with the titles specified for those sections in NUREG-1432,. "Standard Technical Speci,fications-Combustion
.Engineering Plants;-"
These changes are more restrictive and will ensure that if one high-pressure safety injection (HPSI) pump should fail during a steamline break in Mode 3 when the RCS is,less than 1837 psia and greater than 485'F, one'PSI pump would still be available for safety injection.
The Mode 3 safety analysis credits one HPSI pump to provide negative reactivity insertion to protect. the core and the RCS following a steamline break.
These changes will also reflect bounding analysis parameters used in the Mode 3 steamline break analysis.
The Mode 3 safety analysis credits one HPSI pump to provide negative reactivity insertion to protect the core and the RCS following a steamline break when the RCS cold-leg temperature is 485 F or greater.
Requiring two ECCS subsystems to be operable will ensure that one HPSI pump is available, assuming a single failure of the other HPSI pump.
The staff has reviewed the proposed changes to TS 3/4.5.2 and TS 3/4.5.3
- and, on the basis of its evaluation, finds them acceptable.
'4 5
3 5.3 Additionally, the title of TS 3/4.5.2 would be revised to "ECCS Subsystems-Operating,"
and the title of TS 3/4.5.3 would be revised to "ECCS Subsystems-Shutdown."
These editorial changes clarify.the titles of the TS and have no effect on the operation of the plant or on any plant structures,
- systems, or components.
The licensee will revise the Bases for these TS sections to reflect the new restrictions.
Also, footnote ** would be deleted from Section 3.5.2 of the Unit 2 TS.
This footnote has expired.
These changes are administrati've in nature, thus not affecting the health. and safety of the public.
The staff has reviewed the proposed changes.
and finds them.
acceptable.
3.0 S
S In accordance with the Commission's regul'ations, the Arizona State official was notified of the proposed issuance of the amendments.
The State, official had no comments.
4.0 TO The amendments change 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 change surveil,lance requirements.
The NRC staff has determined that the amendments involve 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 amendments involve no significant hazards
I~
consideration, and there has been no public comment on such finding (61 FR 13522).
Accordingly, the amendments meet the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9).
The amendments also involve changes in recordkeeping, reporting or administrative procedures. or requirements.
Accordingly, with respect to.these items,. the amendments meet the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(10).
Pursuant to 10 CFR 51.22(b) no environmental impact statement or environmental assessment need be prepared in connection with the issuance of the amendments.
5.0 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 amendments will not be inimical to the common defense and security or to the health and safety of the public.
Principal Contributor:
C.
Thomas Date:
April 30, 1996
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