ML18054A974

Application for Amend to License DPR-20,revising Tech Specs to Permit Use of Variable PORV Setpoint for Low Temp Overpressure Protection to Increase Operating Margin During Plant Heatup & Cooldown

ML18054A974
Person / Time
Site:	Palisades
Issue date:	09/12/1989
From:	Berry K CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.)
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML18054A976	List: ML18054A974 ML18054A979
References
TAC-72889, NUDOCS 8909190013
Download: ML18054A974 (5)

Text

1,j consumers Power Kenneth V! Berry Director POWEIUNli Nuclear licensing llllUllliAll"'S l'ROliRESS General Offices: 1945 West Parnell Road, Jackson, Ml 49201 * (517) 788-1636 September 12, 1989 Nuclear* Regulatory Conmlission Document .Control Desk Washington,*DC 20555 DOCKET 50-255 - LICENSE DPR PALISADES PLANT -

TECHNICAL SPECIFICATION CHANGE REQUEST - LOW TEMPERATURE OVERPRESSURE PROTECTION (LTOP) - VARIABLE SETPOINT (TAC NO. 72889)

The attached proposed change to the Palisades Technical Specifications is necessary to permit use of a variable Power Operated Relief Valve (PORV) setpoint for Low Temperature Overpressure Protection (LTOP) and thus increase the operating margin during plant heatup and cooldown.

An ancillary improvement is increasing the temperature range in which the HPSI system is available to inject cooling water in the event of a loss. of primary system integrity. We plan to install the variable LTOP (VLTOP) control during the imminent fall 1989 maintenance outage and, at the same time, install larger PORVs and Block Valves. The larger valves increase the flow capacity to enhance once-through-cooling capability and allow HPSI operability at lower

• temperatures.

The Palisades Fall 1989 Maintenan~e Outage is planned to begin on October 1, 1989 and end on November 15, 1989. We plan to restore the Primary Coolant System pressure boundary on or about November 1, 1989. Therefore we request that approval of this Change Request be issued before November 1, 1989. If for some unforeseen reason this project must be delayed until the next outage of sufficient duration, we request the effective date of this change coincide with the plant startup following the installation outage.

Attachment I contains proposed Techntcal Specification pages as they will appear when this request is approved. Attachment II contains the existing Technical Specification pages marked up to refl~ct the proposed changes *

. . Qs;. 52Js

. (} A Kenneth W Berry Q' Director, Nuclear Licensing CC Administrator, Region III, NRC NRC Resident Inspector - Palisades*

Attachment E:90919001:3 OC0889-0101-MD01-NL04 PDR ADOCI<

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1 CONSUMERS POWER COMPANY

-Docket 50-255 Request for Change to the Technical Specifications License DPR-20 For the reasons hereinafter set forth, it is requested that the Technical Specifications contained in the Provisional Operating License DPR-20, Docket 50-255, issued to Consumers Power Company on October 16, 1972, for the Palisades Plant be changed as described in Section I below:

I. Changes A. Section 3.1.1.h is changed to specify the necessary precautions to be taken prior to initiating forced circulatio~ when the secondary temperature is higher than the PCS temperature.

B. The Basis for Section 3.1 has_been changed to explain the new requirements of Section 3.1.1.h.

C. The heatup and cooldown limits in Section 3.1.2 have Qeen changed in accordance with the new limits of Figures 3-l and 3-2. The same rates for heatup or cooldown with .shutdown cooling isolated are specified to simplify operational requirements. The heating rate with shutdown cooling MOV3015 and MOV3016 OPEN is limited to ensure not ex~eeding the capacity of the shutdown cooling system relief valves. The maximum pressurizer heatup rate has been changed to 200°F per hour with shutdown cooling isolated, and 60°F per hour with shutdown cooling MOV3015 and MOV 3016 OPEN.

D. Figures 3-1, 3-2, and 3-3 have been revised by using refined calculation methods defined in Regulatory Gui9e 1.99 Revision 2 to allow higher pressures at a given temperature.

E. The Basis for Section 3.1.2 has been changed to describe the method of calculation used for Figures 3-1, 3-2 and 3-3.

- F. An explanation of the method for calculating the hourly average cooldown rate has been added to the Basis of Section 3.1.2.

G. Section 3.1.8 has been changed and Figure 3-4 ad9ed to allow the use of a variabl~ PORV setpoint for LTOP. Section 3.1.8 has also been changed to reflect protection of the primary coolant system only.

Pr_ot_ectioJl :for t'he_ s_hutdown cooling system is afforded by --its_

installed relief valves,_and by the limitations of sections 3.1.1.h, 3.1.2.a & c, and 3.3.2 g.

H. Section 3.1.8.c has been deleted since a dedicated operator is not required with a variable PORV setpoint.

I. Sections a and b of the action requirement of Section 3.1.8 have been changed to reflect the operation of the new PORV. (The valve, not only the valve pilot as with the existing valves, can be electrically held OPEN.)

OC0889-0101-MD01-NL04

2 J. A paragraph which explain$ the curve in Figure 3-4_has been added to the Basi-s for Section 3.1.8. fo addition~ a method of opening the PORVs to provide a vent path is explained.

K. Section 3.3.2.g has been completely revised to take advantage of the higher pressure limits allowed by the new PORV setpoints specified in proposed Section 3.1.8 (see page changes).

L. The Basis of $e~tion 3.3 has been changed to reflect the changes to Section 3.3.2.g. The paragraph explaining the need for a dedicated operator has been deleted.

M. Section 4.1.1.c has been changed to delete the word "pilot" because the new PORVs can be held open electrically.

N. Section 4.6.1.b has been changed_to coincide with the changes to Section 3.1.8 (see page changes).

O. The last paragraph of the Basis for Section 4.6 has been changed_to conform with the conditions required by the proposed Section 3.1.8.

II. Discussion Installing a variable PORV setpoint control for the Palisades Plant is a major goal in accomplishing the objective of providing a larger operating margin during heatup and cooldown. Concurrent with this effort, other programs to increase reactor vessel (RV) life, comply.with the block valve criteria of NUREG-0737, and decrease the probability of core melt risk outliers have resulted in actions which have resulted in less fluence for certain areas of the RV (using twice burned fuel and metallic rods in the fuel adjacent to longitudinal welds), installation of new PORV block valves, and installation of larger block valves and PORVs.

Recognizing the appropriate fluence accumulation rates for longitudinal and circumferential welds, new low leakage fuel management, and using refined calculational methods have resulted in new pressure/temperature limits showri in Figures 3-1, 3-2, and 3-3. Changes to the calculation method involved:

t -

(1) Using Regulatory Guide 1.99 Revision 2 instead of Regulatory Guide 1.99 Draft Revision 2 resulted in calculating the 6RTNDT temperature shift at 1/4 t and 3/4 t by using the fluence attenuat1on at 1/4 t and 3/4 t instead of using the 6RTNDT surface attenuation at 1/4 t and 3/4 t. _

(2) The stress intensity factor-coefficients were reevaluated using the vessel radii at 1/4 t and 3/4 t.

(3) Temperature and pressure measurement inaccuracy was not included.

Installation of larger PORVs and block valves will reduce the pressure overshoot when postulating inadvertent mass injection by the charging and HPSI systems and the overall result will be (1) to permit HPSI operability down to 230°F, (2) permit initiation of forced PCS OC0889-0101-MD01-NL04

3 circulation under limited conditions when the steam g~nerator tempera-

-ture is higher than the :Pcs cold leg temperature, and (3) provide ample once-through-cooling when one PORV is inoperable.

The existing LTOP limits of Section 3.1.8 result from limitations set by the pressure limit of the $hutdown Cooling System and existing instrumentation capability. Protection for the Shutdown Cooling (SDC)

System by the new PORVs will not be requtred, since limits proposed for sections 3.1.1 h, 3.1.2 a and c, and 3.3.2 g. will ensure that challenges to the SDC System pressure boundary are within the capacity of the SDC System Relief valves. The setpoints of the SDC System relief valves will be adjusted as necessary to provide the neces$ary overpressure protection without reliance on the new PORVS. New instrumentation which can be programmed to open the PORVs at a large number of pressure/temperature combinations will Qe installed to permit the higher PORV setpoints in proposed Section 3.1.8. Simultaneous installation of the new variable LTOP instrumentation and the larger PORV flowpath will result in a consolidated training module for operating personnel.

Figure 3-4 in Sectiog 3.1.8 shows the maximum PORV pressure setpoint at various temperatures. The values on that curve are the 10CFR50 Appendix G values minus analyzed pressure overshoot. The. actual PORV s~tpoints will be below and to the right of the curve to allow for instrument inaccuracy, setpoint error and measurement error.

Proposed Section 3.3.2.g retains requirements that recognize the limitations of the Shutdown Cooling (SDC) System pressure boundary.

When the SDC system is not isolated from the PCS, HPSI operability is not allowed. However when the SDC system is isolated, full RPS!

operability is allowed doWIJ. to 230°F and both RPS! trains are required to be operable above 325°F.

Analysis of*No Significant Hazards Consideration Consumers Power Company finds that.activities associated with this Change Request involve no significant hazards, and, accordingly, a no significant hazards determination per 10CFR50.92(c) is justified. The following evaluation supports that finding.

Evaluation

1. Involve a significant increase inthe probability-or consequences of** an accident previously* evaluated.

There are three previously evaluated conditions which Gould result in the 10CFR50 Appendix G limits being ~xceeded. They are mass injection by the charging and/or RPS! systems or a heat injection by initiating forced circulation when the steam generator temperature is higher than the PCS cold leg tempera-ture. These conditions have been postulated and analyzed under the conditions proposed by this Change Req~est and under no conditions will the Appendix G limits (Fig. 3-1, 3-2, and 3-3) be exceeded. Therefore the consequences of an accident previously evaluated are not in~reased. The RPS! operability OC0889-0101-MD01-NL04

4 range has been increased to provide ~dditional low temperature -

ECCS availability. If inadvertent HPSI pump operation would occur, Appendix G limits would not be violated. Therefore there is no increase in th~ probability or consequences of an accident previously evaluated.

2. Create the possibility of a new or different kind of accident from any accident previously evaluated.

This proposed change only increases allowable PCS pressure/

temperature relationships in specified temperature ranges and allows HPSI operability over a larger temperature range.

Therefore it does not create the possibility of a new or different kind of ~ccident.

3. Involve a significant reduction in a margin of safety.

The margin of safety is the difference between the stress at which the PCS pressure boundary would fail and the stress permitted by 10CFR50 Appendix G. This proposed specification change does not change the stress allowed by 10CFR50 Appendix G and ensures that the stress allowed by 10CFR50 Appendix G will not be exceeded"' Therefore, it does not involve a reduction in the margin of safety.

III. Conclusion The Palisades Plant Review Committee has reviewed this Technical Specification Change Request and has determined that this change does not involve an unreviewed safety question and therefore involves no significant hazards consideration. This change has been reviewed by the Nuclear Safety Services Department. A copy of this Technical Specification Change Request has been sent to the State of Michigan official designated to receive such Amendments to the Operating License.

CONSUMERS POWER COMPANY To the best of my knowledge, inform~tion and belief, the contents of this submittal are truthful and complete.

By~David Sworn and subscribed to before me this 12th day of October 1989.

• ~~.~

Elaine E Buehrer, Notary Public Jackson County, Michigan My commission expires October 31, 1989 OC0889-0101-MD01-NL04