ML17305B416
| ML17305B416 | |
| Person / Time | |
|---|---|
| Site: | Palo Verde  |
| Issue date: | 03/26/1991 |
| From: | Conway W, James M. Levine ARIZONA PUBLIC SERVICE CO. (FORMERLY ARIZONA NUCLEAR |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| 161-03837-WFC-J, 161-3837-WFC-J, NUDOCS 9103290006 | |
| Download: ML17305B416 (9) | |
Text
A(~CELERATED D RIBUTION DEMONS.
TION SYSTEM REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS)
ACCESSION NBR:9103290006 DOC.DATE: 91/03/26 NOTARIZED:
NO DOCKET FACIL:STN-50-530 Palo Verde Nuclear Station, Unit 3, Arizona Publi 05000530 AUTH.NAME AUTHOR AFFILIATION CONWAY,W.F.
Arizona Public Service Co.
(formerly Arizona Nuclear Power LEVINE,J.M.
Arizona Public Service Co.
(formerly Arizona Nuclear Power RECIP.NAME RECIPIENT AFFILIATION Document Control Branch (Document Control Desk)
SUBJECT:
Requests temporary waiver of compliance for Table 3.4-3 of Limiting Condition for Operation 3,4.8.1. to permit RCS cooldown rate below 93 F during removal of reactor vessel head
& filling of refueling cavity.
DISTRIBUTION CODE:
AOOID COPIES RECEIVED:LTR
[
ENCLI SIZE:
TITLE: OR Submittal:
General Distribution D
S'OTES:Standardized plant.
RECIPIENT ID CODE/NAME PD5 LA TRAMMELL,C INTERNAL: ACRS NRR/DET/ESGB NRR/DST 8E2 NRR/DST/SICB 7E NUDOCS-ABSTRACT OGC/HDS1 RES/DSIR/EIB EXTERNAL: NRC PDR NOTES COPIES LTTR ENCL 1
1 2
2 6
6 1
1 1
1 1
1 1
1 1
0 1
1 1
1 RECIPIENT ID CODE/NAME PD5 PD THOMPSON,M NRR/DET/ECMB 9H NRR/DOEA/OTSB11 NRR/DST/SELB 8D NRR/DST/SRXB 8E OC/LFMB RES F;EKE~
0'1+
NSIC COPIES LTTR ENCL 1
1 2
2 1
1 1
1 1
1 1
1 1
0 1
1 05000530 A
D D
D NOTE TO ALL"RIDS" RECIPIENTS:
PLEASE HELP US TO REDUCE WASTE! CONTACT THE DOCUMENT CONTROL DESK, ROOM P 1-37 (EXT. 20079) TO ELIMINATEYOUR NAME FROM-DISTRIBUTION LISTS FOR DOCUMENTS YOU DON'T NEED!
TOTAL NUMBER OF COPIES REQUIRED:
LTTR 27 ENCL 25 A
D D
S
0 II
Arizona Public Service Company P.O. BOX 53999
~
PHOENIX. ARIZONA85072-3999 WILLIAMF. CONWAY EXECUTIVEVICEPRESIDENT NUCLEAR 161-03837-WFC/JST March 26, 1991 Docket No.
STN 50-530 U.
S. Nuclear Regulatory Commission Attention: Document Control Desk Mail Station Pl-37 Washington, D.
C.
20555
Dear Sir:
Subj ect:
Palo Verde Nuclear Generating Station (PVNGS)
Unit 3 Request for a Temporary Waiver of Compliance for Table 3.4-3 of Limiting Condition for Operation 3.4.8.1 File:
91-056-026 Arizona Public Service (APS) respectfully requests a
temporary waiver of compliance from the requirements of Table 3.4-3 of Limiting Condition for Operation 3.4.8.1 during the time the reactor vessel head is fully detensioned in the current Unit 3, Cycle 3 refueling outage, as discussed in a conversation with Mr. J.
E.
- Dyer, NRR, on March 25, 1991.
A request for a technical specification amendment for all three Palo Verde Units to,clarify the basis and applicability of Limiting Condition for Operation 3.4.8.1 will be submitted by May 17, 1991.
Descri tion of Condition This waiver is requested to allow a cooldown below 93'F.
The current allowable cooldown rate of Table 3.4-3 is O'F per hour rate which would not allow any cooldown below 93'F.
The need to have the reactor coolant system (RCS) below this temperature occurs during the removal of the reactor vessel head and filling of the refueling cavity as well as the time period the reactor vessel is defueled and consequently no method of maintaining minimum RCS temperature is available.
Plant operations for refueling require the removal of the reactor vessel he'ad and the transfer of the contents of the refueling water tank into the reactor coolant system (RCS) to fillthe refueling cavity.
The water in the refueling water tank is approximately 70'F and its transfer will result in a gradual cooldown of the RCS to below the 93'F limit of Table 3.4-3 of Limiting Condition for Operation 3.4.8.1, but above the minimum adjusted reference temperature of 45'F.
This requirement was introduced in Amendment 24 to the Unit 3 Technical Specificat'ions which was the result of a reanalysis of the pressure-temperature (P-T) limits using the more restrictive requirements of Regulatory Guide 1.99 Revision 2 as required by Generic Letter 88-11.
The reanalysis included more restrictive cooldown tables which limited cooldown below 93'F to maintaining an isothermal condition of O'F per hour with the RCS capable of being pressurized.
Prior to this amendment, RCS cooldown was limited to 10'F per hour below 100'F.
The maximum allowable cooldown rates specified in Technical Specification 3/4.4.8 are
U.
S. Nuclear Regulatoy Commission Page 2
161-0 837-NFC/JST March 26, 1991 based upon preventing RCS pressure from exceeding the corresponding normal operation pressure-temperature limit, assuming a concurrent pressurization due to the limiting low temperature overpressurization transient.
This is not a
consideration when the vessel head is fully detensioned and the RCS cannot be pressurized.
Com ensator Actions Prior to and during the period of this waiver the RCS will be protected from the possibility of an overpressurization event by ensuring the vessel head is fully detensioned.
Fully detensioning the vessel head will prevent the RCS from exceeding its P-T limits due to'he limiting low temperature overpressurization transient.
Safet Evaluation The purpose of the maximum cooldown rates specified in Technical Specification 3/4.4.8 is to prevent the RCS pressure from exceeding the corresponding normal operation P-T limit, assuming a concurrent overpressurization due to the limiting low temperature overpressurization transient.
Consequently, the cooldown rate limits are only valid if the RCS is capable of being pressurized.
Therefore, with the vessel head detensioned, the technical specification cooldown limits are not applicable.
The waiver requested is only for the period of time the vessel head is fully detensione'd and thus the RCS cannot be pressurized above the static head of water over the vessel in the refueling pit which is negligible compared to the ASME Code Appendix G, P-T limit.
APS has performed a
No Significant Hazards Analysis and Environmental Impact Consideration Determination, Attachment A,
and concluded that this waiver of compliance with the compensatory action of fully detensioning the head willhave no adverse impact on the continued safe operation of the plant.
This wavier request has also been concurred with by the Plant Review Board and ABB Combustion Engineering, the NSSS vendor.
Pursuant to 10 CFR 50.91 (b) (1), and by copy of this letter and attachment, we have notified the Arizona Radiation Regulatory Agency of this request for a waiver of compliance.,
Sincerely, WFC/JST Attachment CC:
C.
M. Trammell J.
B. Martin J.
E. Dyer D. H.
Coe A.
C. Gehr A. H. Gutterman C.
F. Tedford (all w/attachment)
I
161-037-MFC/JST March 26,1991 Attachment A
Basis for No Significant Hazards Consideration The Commission has provided standards for determining whether a significant hazards consideration exists as stated in 10 CFR 50.92.
A proposed waiver of compliance to an operating license for a facility involves no significant hazards consideration if operation of the facility in accordance with a proposed waiver of compliance would not: (1) involve a significant increase in the probability or consequences of an accident previously evaluated; or (2) create the possibility of a new or different kind of accident from any accident previously evaluated; or (3) involve a significant reduction in a margin of safety.
A discussion of these standards as they relate to this waiver of compliance request follows:
Standard 1:
Involve a
si nificant increase in the robabilit or conse uences of an accident reviousl evaluated.
The waiving of the requirements of Table 3.4-3 of Technical Specification 3/4.4.8 while the ves'sel. head is fully detension'ed does not involve an increase in the probability or consequences of an accident previously evaluated.
I f'he Technical Specification for low temperature overpressure protection is based on the RCS heatup and cooldown rates of Table 3.4-3, as well as the operability of one of the two low temperature overpressure protection shutdown cooling relief valves.
Meeting both of these requirements ensures that the RCS will be protected from pressure transients which could exceed the limits of Appendix G to 10 CFR Part 50 when one or more of the RCS cold legs are less than or equal to 214'F during cooldown and 291 F during heatup.
Either one of the two shutdown cooling system (SCS) suction line relief valves provides relieving capacity to protect the RCS from overpressurization when the transient is limited to either (1) the start of an idle reactor coolant pump (RCP) with the secondary water temperature of the steam generator less than or equal to 100'F above the RCS cold leg temperatures or (2) the inadvertent safety injection actuation with two high pressure safety injection (HPSI) pumps injecting into a water solid RCS with full charging capacity and with letdown isolated.
These events are the most limiting energy and mass addition transients, respectively, when the RCS is at low temperatures.
Waiving Table 3.4-3 requirements when the vessel head is fully detensioned and the RCS cannot be pressurized does not affect either the probability or consequences of the limiting events.
This is so, because without the concurrent pressure
- stress, the thermal stress associated with normal refueling evolutions cannot exceed the P-T limits and therefore no structural integrity issues would exist.
Additionally, the adjusted reference temperature for the Unit 3 vessel is 45'F for up to 8
EFPY and thus sufficient margin exists for prevention of brittle fracture.
161-37-MFC/JST Mar 6,
1991 Standard 2: Create the ossibilit of a new or different kind of accident from an accident reviousl evaluated.
The waiving of Table 3.4-3 requirements when the vessel head is fully detensioned does not create the possibility of a new or different kind of accident from any previously evaluated.
The change does not affect operation of the plant except to waive cooldown and heatup limits when the reactor vessel cannot be pressurized.
During this time period the heatup and cooldown limits are not necessary.
Standard 3: Involve a si nificant reduction in a mar in of safet The safety function of the heatup and cooldown limitations are to ensure that the RCS pressure does not exceed the corresponding normal P-T limits, assuming a concurrent pressurization due to the limiting low temperature overpressurization transients described in Standard 1.
The waiving of these limitations during the time period the RCS cannot be pressurized does not involve a decrease in the margin of safety.
The compensatory action of fully detensioning the head willprevent overpressurization from the limiting low temperature overpressurization transients and results in no decrease in the margin of safety.
Environmental Impact Consideration Determination The proposed waiver of compliance request does not involve an unreviewed environmental question because operation of PVNGS Unit 3 in accordance with this
- change, would not:
Result in a significant increase in any adverse environmental impact previously evaluated in the Final Environmental Statement (FES) as modified by the staff's testimony to the Atomic Safety and Licensing Board; or 2.
Result in a significant change in effluents or power levels; or 3.
Result in matters not previously reviewed in the licensing basis for PVNGS which may have a significant environmental impact.
As discussed
- above, no significant reduction in safety and no new accidents are introduced by this change.
This waiver of compliance does not affect effluents, or power levels, and has no environmental impact.
t