ML18052B427

Application for Amend to License DPR-20,revising Tech Specs to Lower Relief Valve Setting & to Provide Low Temp Overpressure Protection Up to Temp Where Pressurizer Safety Valves Provide Protection Against Brittle Fracture.Fee Paid

ML18052B427
Person / Time
Site:	Palisades
Issue date:	12/22/1987
From:	Berry K CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.)
To:	NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM)
Shared Package
ML18052B428	List: ML18052B427 ML18052B429
References
NUDOCS 8712290283
Download: ML18052B427 (7)

Text

...

consumers Power Kenneth W Berry POWERINli Director ll/llCHlliAN'S PROliRESS Nuclear licensing General Offices: 1945 West Parnall Road, Jackson, Ml 49201 * (517) 788-1636 December 22, 1987 Nuclear Regulatory Connnission Document Control Desk Washington, DC 20555 DOCKET 50-255 - LICENSE DPR-20 -*PALISADES PLANT -

TECHNICAL SPECIFICATION CHANGE REQUEST - LOW TEMPERATURE OVERPRESSURE PROTECTION (LTOP)

The attached proposed change to the Palisades Technical Specifications is necessary to update the Low Temperature Overpressure Protection (LTOP) requirements. As the reactor vessel is exposed to fast neutrons, the ability of the material at the reactor heltline to resist brittle fracture at low temperatures is decreased. Periodically, the upper pressure limit at given temperatures must be lowered to keep the pressure/temperature relationship within the ductile range of the beltline material .

..

• Specifically, this proposed Technical Specification Change lowers the relief valve setting over the temperature range presently addressed in the Technical Specifications, provides LTOP protection up to the temperature where the pressurizer safety valves provide protection* against brittle fracture, and adds precautionary measures during heatup and cooldown.

• • ,,: ~.. The proposed changes to the Technical Specifications are more restrictive than existing Technical Specifications. Consumers Power Company commits to operate

• the Palisades Plant in accordance with the proposed changes to the Technical Specifications until they are approved as a license amendment.

. -- l A check, for $150.00 as r~quired by* 10CFR170.21 is included.

G>"

.~,:_...

. PDR 87.'12290283~71222-*".*:

A. DOC

.. '?. -~

'5000'*25 ...*" .I *

• 1

~-* .~*::", ' .. *; ~>*.O :.* ' . 5 ..;.:.l* .. I I

~-..::;~-)

Kenneth W Berry Director, Nuclear Licensing CC Administrator, Region III, NRC NRC Resident Inspector - Palisades Attachment OC1287-0234-NL04

(

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. Revise section 3.1.lh to read:

"h. During initial primary coolant pump starts (i.e., initiation of forced circulation), secondary system temp~rature in the steam generators shall be < the PCS cold leg temperature unless the PCS cold leg temperature is > 450°F."

B. Revise the last sentence of the last paragraph in the Basis for section 3.1 to read:

"The requirement that the steam generator temperature be < the PCS temperature when forced circulation is initiated ensures that an energy addition caused by heat transferred from the secondary system to the PCS will not occur. This requirement applies only to the initiation of forced circulation (the start of the first primary coolant pump) when the PCS cold leg temperature us < 450°F. At or above 450°F, the PCS safety valves prevent the PCS pressure from exceeding 10CFRSO Appendix G limits .n C. Section 3.l.2a has been revised to restrict heatup rate limitations at low temperatures.

D. Proposed Section 3.l.2b has been revised to restrict cooldown rates at low temperatures.

E. Section 3.l.2c has been revised to include the heatup and cooldown rate restrictions as proposed in Section 3.l.2a and b.

F. Section 3.l.2d has been revised to restrict the pressurizer heatup rate. ,

G. Revise the last sentence of the first partagraph in Basis for Section 3.1.2 to read:

"A plant heatup and cooldown limit of 100°F per hour is consistent with the design ny,~er of cycles and satisfies stress limits for cyclic operation. "

OC1287-0234-NL04

2 H. The following two paragraphs have been proposed at the end of the Basis for Section 3.1.2.

II 1 The restriction of average heatup and cooldown rates to 100°F/h when all PCS cold legs are ~ 450°F and the maintenance of a pressure~.temperature relationship under the heatup, cooldown and inservice test curves of Figures 3-1, 3-2 and 3-3, respectively, ensures that the requirements of References 6, 7, 8 and 9 are met.

The core operational limit applies only when the reactor is critical.

• The heatup and cooldown rate restrictions applicable when the temperature of one or more of the PCS cold legs is less than 450°F are consistent with the analyses performed for low temperature overpressure protection (LTOP) (References 13 and 14). At 450°F or above, the PCS safety valves provide overpressure protection for heatup or cooldown rates_:: 100°F/hr."

I. Section 3.1.8 is completely revised to change PORV setpoints and increase the temperature range where LTOP is applicable.

J. Section 3.3.2g is revised to read:

"g. The control fuses for the high pressure safety injection pump (P-66A and P-66B) motors shall be removed when the temperature of one or more of the primary system cold legs is < 430°F unless the reactor head is removed.

K. The last paragraph of the Basis for section 3.3 is revised to read:

II Removal of the control fuses for the HPSI pumps eliminates excessive PCS mass additions due to inadvertent pump starts.

HPSI pump starts in conjunction with a charging/letdown imbalance may cause 10CFRSO Appendix G limits to be exceeded when the PCS temperature is < 430°F. When the PCS temperature is > 430°F, the pressurizer safety valves ensure that *the PCS pressure will not exceed 10CFRSO Appendix G limits when one or both HPSI pumps are started."

L. Section 4.1.lc has been added to provide a surveillance requirement when open PORV pilot valves are used as an alternative to venting the PCS.

M. Sections 4.6.la and b have been combined as Section 4.6~1a and Section 4.6.lc has been designated Section 4.6.lb and revised to read:

"Both high pressure safety injection pumps shall be demonstrated inoperable at least once per 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> whenever the temperature of one or more of the PCS cold legs is < 430°F by verifying that the control system fuses and their .fuse holders for the HPSI pump

'breakers (P66A, P66B) have been removed from the circuit."

OC1287-0234-NL04

3 N. The paragraph below has been added to the basis of Section 4.6 to give the basis for the surveillance requirement to verify that both HPSI control fuses are removed when the PCS temperature is < 430°F.

"Unless the reactor head is removed, the control fuses for both HPSI pump breakers are removed from the circuit when the PCS temperature is < 430°.F to prevent a mass addition and the accompanying PCS pressure increase which would result if a HPSI pump were started.

That resultant pressure increase could cause the pressure limits required by 10CFR50 Appendix G to be exceeded."

II. Discussion The above proposed Technical Specifications changes will provide Low Temperature Overpressure Protection (LTOP) and prevent the 10CFR50.

Appendix G heatup and cooldown pressure limits from being exceeded.

Above 430°F, the pressurizer safety valves prqvide overpressure protection. Three conditions are recognized which could cause the primary coolant system (PCS) pressure to exceed the 10CFRSO Appendix G limits. They are:

1. A mass addition caused by the start of a high pressure safety injection (HPSI) pump,

2. A mass addition resulting from a charging/letdown imbalance,

3. An energy addition caused by the initiation of -forced circulation when the steam generator temperature is greater than the cold leg temperature of the PCS.

A mass addition by a HPSI pump and the concurrent pressure increase is prevented in proposed section 3.3.2g by the requirement for both HPSI pump motor control fuses to be removed when the PCS temperature is below 430°F unless the reactor head is removed.

The setpoints of the Power Operated Relief Valves (PORVs) as required by proposed Sections 3.l.8a and 3.1.Bb have been shown by analysis (Reference 1) to be low enough to prevent the pressure increase resulting from the maximum possible charging/letdown imbalance (three charging pumps operating and letdown isolated) from causing the PCS pressure to exceed the 10CFRSO Appendix G heatup and cooldown pressure limits.*

Analysis (Reference 2) has been completed which shows that the maximum possible charging/letdown imbalance will not cause the 10CFRSO Appendix G pressure limits to be exceeded when the PCS temperature is greater than 385°F, a bubble is formed in the pressurizer and the actual pressurizer liquid level is less than 60%. Proposed section 3.1.Bc allows the PORVs to be inoperable when these conditions exist. Forming a bubble of appropriate size and rendering the PORVs inoperable facilitates operation by increasing the size of the operating pressure/

temperature window.

OC1287-0234-NL04

4 ACTION steps "a" and "b" are similar to the Standard Technical Specifications except the option of opening the pilot valves and block valves for both PORVs has.been added. Analysis (Reference 1) has been completed which shows that if a single PORV is open at 310 psia, a charging/letdown imbalance will not cause the 10CFRSO Appendix G pressure lim~.ts to be exceeded.

The proposed requirement in Section 3.1.lh for the steam generator temperature to be less than or equal to the PCS cold leg temperature before a primary coolant pump is started to initiate forced circulation unless the PCS cold leg temperature is more than 450°F eliminates the possibility of an energy addition caused by the initiation of forced circulation. Above 450°F, an energy addition to the PCS resulting from the initiation of forced circulation will not cause the 10CFRSO Appendix G pressure limits to be exceeded because the PCS safety valves provide adequate overpressure protection.

• Proposed Sections 3.l.2a, b, and c. are necessary to restrict heatup and cooldown rates at low temperatures to rates for which the pressure limits of 10CFRSO Appendix G, as illustrated in Figures 3-1, 3-2 and 3-3 of Section 3.1.2, are above the maximum pressures which could result from a possible transient. Proposed Section 3.l.2d restricts the pressurizer heatup rate to maintain the PCS within the analyzed conditions (Reference 2).

The proposed changes in Sections 4.1.lc, 4.6.lc and the basis for

~Section 4.6 align the Surveillance Requirements with the proposed Limiting Conditions for Operation.

Therefore, through a combination of PORV setpoints, equipment inoperability requirements, and restrictions on the primary/secondary temperature relationship when initiating forced circulation in the PCS, the proposed Technical Specifications prevent the pressure limits of the 10CFRSO Appendix G curves from being exceeded.

References

1. Analysis for E-PAL-87-lOlG "Calculation of PCS Pressure Increase From Adding 133 gpm (3 charging pumps) Before the PORVs Open,"

November 4, 1987.

• 2. Analysis for E-PAL-87-lOlG " Palisades Heatup and Cooldown Curves",

November 4, 1987.

III. 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 10CFRS0.92(c) is justified. The following evaluation supports that finding.

OC1287-0234-NL04

5 Evaluation

1. Involve a significant increase in the probability or consequences an accident previously evaluated LTOP prevents the PCS pressure from exceeding 10CFRSO. Appendix G pressure/temperature limits. Three recognized conditions could cause those limits to be exceeded. Two involve mass additions i.e.,

HPSI pump start and a charging/letdown imbalance. The third involves an energy addition - i.e., the initiation of force~ PCS circulation when the steam generator temperature is greater than the PCS temperature.

This proposed Technical Specification change prevents those conditions from occurring by:

1. Requiring the HPSI pump control fuses to be removed below 430°F,

2. Requiring the PORVs to be* operable (unless T ' > 385 °F and a PZR bubble > 40% is formed) up to 430°F, andpcs

3. Requiring the steam generator temperature to be equal to or less than the PCS temperature when forced PCS circulation is initiated unless the PCS temperature is high enough to allow the PCS safety valves to provide overpressure protection.

Therefore, the probability of exceeding allowable pressures is decreased. The consequences of an accident (rupturing the pressure barrier) remain the same.

2. Create the possibility of a new or different kind of accident from any accident previously evaluated The proposed changes only lower the pressure relief setting over the temperature range previously protected by LTOP, extend LTOP to higher temperatures, and add precautionary measures during heatup and cooldown. Thus, they do not create the possibility of a new or different kind of accident *.

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 could fail and the stress permitted by 10CFR50 Appendix G. This change ensures that the stress permitted by 10CFR50 Appendix G is not exceeded. Therefore, it does not

• involve a reduction in a margin of safety.

IV. 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 also been reviewed OC1287-0234-NL04

6 under the cognizance of the Nuclear Safety Board. A copy of this Technical Specification Change Reguest has be~n sent to the State of Michigan official designated to receive such Amendments to the Operating License.

CONSUMERS POWER COMPANY By Sworn and subscribed to before me this 22nd day of December 1987.

~*t~

Elaine E Buehrer, Notary Public Jackson County, Michigan My commission expires October 31, 1989 OC1287-0234-NL04