ML18064A508

Proposed Tech Specs,Adding Third High Thermal Performance DNB Correlation to Safety Limit 2.1

ML18064A508
Person / Time
Site:	Palisades
Issue date:	12/13/1994
From:	CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.)
To:
Shared Package
ML18064A507	List: ML18064A506 ML18064A508
References
NUDOCS 9412220068
Download: ML18064A508 (6)

Text

ATTACHMENT 1 Consumers Power Company Palisades Plant Docket 50-255 PROPOSED HTP CORRELATION TECHNICAL SPECIFICATIONS PROPOSED PAGES 2 Pages 9412220068 941213 PDR ADOCK 05000255 p PnR

2:0 SAFETY LIMIT~ND LIMITING SAFETY SYSTEM SETT~S 2.1 Safety Limit - Reactor Core The Minimum DNBR of the reactor core shall be maintained greater than or equal to the DNB correlation safety limit.

Correlation Safety Limit XNB 1.17 ANFP 1.154 HTP 1.141 Applicability Safety Limit 2.1 is applicable in HOT STANDBY and POWER OPERATION.

Action 2.1.1 If a Safety Limit is exceeded, comply with the requirements of Specification 6.7 2.2 Safety Limit - Primary Coolant System Pressure (PCS)

The PCS Pressure shall not exceed 2750 psia.

App 1 i cabil i ty Safety Limit 2.2 is applicable when there is fuel in the reactor.

Action 2.2.1 If a Safety Limit is exceeded, comply with the requirements of Specification 6.7 2.3 Limiting Safety System Settings - Reactor Protective System (RPS)

The RPS trip setting limits shall be as stated in Table 2.3.1.

Applicability Limiting Safety System Settings of Table 2.3.1 are applicable when the associated RPS channels are required to be OPERABLE by Specification 3.17.1.

Action 2.3.1 If an RPS instrument setting is not within the allowable settings of Table 2.3.1, immediately declare the instrument inoperable and complete corrective action as directed by Specification 3.17.1.

Amendment No. 3-!, S, 43-, -l+S, -l-3-7, W, 2-1

2.0 BASIS - Safety Li~s and Limiting Safety System S~inqs 2.1 Basis - Reactor Core Safety limit To maintain the integrity of the fuel cladding and prevent fission product release, it is necessary to prevent overheating of the cladding under normal operating conditions. This is accomplished by operating within the nucleate boiling regime of heat transfer, wherein the heat transfer coefficient is large enough so that the clad surface temperature is only slightly greater than the coolant temperature. The upper boundary of the nucleate boiling regime is termed "departure from nucleate boiling" (DNB). At this point, there is a sharp reduction of the heat transfer coefficient, which would result in high-cladding temperatures and the possibility of cladding failure.

Although DNB is not an observable parameter during reactor operation, the observable parameters of thermal power, primary coolant flow, temperature and pressure, can be related to DNB through the use of a DNB Correlation. DNB Correlations have been developed to predict DNB and the location of DNB for axially uniform and nonuniform heat flux distributions. The local DNB ratio (DNBR), defined as the ratio of the heat flux that would cause DNB at a particular core location to the actual heat flux, is indicative of the margin to DNB. The minimum value of the DNBR, during steady-state operation, normal operational transients, and anticipated transients is limited to DNB correlation safety limit. A DNBR equal to the DNB correlation safety limit corresponds to a 95% probability at a 95% confidence level that DNB will not occur which is considered an appropriate margin to DNB for all operating conditions.

The reactor protective system is designed to prevent any anticipated combination of transient conditions for primary coolant system temperature, pressure and thermal power level that would result in a DNBR of less than the DNB correlation safety limit. The Palisades safety analyses uses three DNB correlations. The XNB correlation discussed in References 1 and 2 determines the safety limit for those fuel assemblies initially loaded prior to Cycle 9.

Fuel assemblies, initially loaded in cycle 9 and later, utilize a high thermal performance (HTP) design which is different than the fuel design used for cycle 8 and earlier reloads. The ANFP correlation discussed in References 4 and 5 and the HTP correlation discussed in Reference 7 determine the safety limit for those fuel assemblies initially loaded in cycle 9 and later. The ANFP correlation was developed for the HTP fuel design; the HTP correlation is an extension of the ANFP correlation and reflects the results of additional DNB testing of HTP fuel. The HTP correlation is restricted to the operating conditions specified in Reference 7, outside of which. the ANFP correlation is used. In the presence of a mixed core consisting of both HTP and non-HTP fuel assemblies, situated such that the non-HTP fuel assemblies affect the flow distribution, the minimum DNBR analyses are in accordance with Reference 6.

References (1) XN-NF-62l(P)(A), Rev 1 (2) XN-NF-709 (3) Updated FSAR, Section 14.1.

(4) ANF-1224 (P)(A), May 1989 (5) ANF-89-192(P), January 1990 (6) XN-NF-82-2l(A), Revision 1 - _____(7)_ _EML-92-~~(PJ_(~)_ i!_nd__ ~_l!PPl!m~n~_ ~!_t:!_ar5h __l?~~:___________________________

Amendment No. 1-, ~, -H-8, 7-, tw, ~,

B 2-1

ATTACHMENT 2 Consumers Power Company Palisades Plant Docket 50-255 PROPOSED HTP CORRELATION TECHNICAL SPECIFICATIONS EXISTING PAGES WITH PROPOSED CHANGES MARKED

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2:0 SAFETY LIMI~AND LIMITING SAFETY SYSTEM SET~S 2.1 Safety Limit - Reactor Core The Minimum DNBR of the reactor core shall be maintained greater than or equal to the DNB correlation safety limit.

Correlation Safety Limit XNB 1.17 1 :1: :;[I: :I: : : : : : : : : : : : : :mrn: :n: :i: : :i: : rn:t,: f: :~:i:i:

Applicability Safety Limit 2.1 is applicable in HOT STANDBY and POWER OPERATION.

Action 2.1.1 If a Safety Limit is exceeded, comply with the requirements of Specification 6.7 2.2 Safety Limit - Primary Coolant System Pressure (PCS)

The PCS Pressure shall not exceed 2750 psia.

Applicability Safety Limit 2.2 is applicable when there is fuel in the reactor.

Action 2.2.1 If a Safety Limit is exceeded, comply with the requirements of Specification 6.7 2.3 Limiting Safety System Settings - Reactor Protective System (RPS)

The RPS trip setting limits shall be as stated in Table 2.3.1.

Applicability Limiting Safety System Settings of Table 2.3.l are applicable when the associated RPS channels are required to be OPERABLE by Specification 3.17.1.

Action 2.3.l If an RPS instrument setting is not within the allowable settings of Table 2.3.1, immediately declare the instrument inoperable and complete corrective action as directed by Specification 3.17.1.

Amendment No-. '/JJ, J.~, -~:J, JJ.~, _J.'/Jl, _.f-W _

July 15, 1992 2-1

2.0 BASIS - Safety~mits and Limiting Safety Syste~ettinqs 2.1 Reactor Core Safety limit T.o*maintain the inte9rity of the fuel cladding and prevent fission

_ product release, it is necessary to Qrevent overheating of the cladding under normal operating conditions. This is accomplished by operating within the nucleate boiling regime of heat transfer, wherein the heat transfer coefficient is large enough so that the clad surface temperature is only slightly greater than the coolant temperature. The upper boundary of the nucleate boiling regime is termed "aeparture from nucleate boiling" (DNB). At this point, there is a sharp reduction of the heat transfer coefficient, which would result in high-cladding temperatures and the possibility of cladding failure. Although DNB is not an observable parameter during reactor operation, the observable parameters of thermal power, primary coolant flow, temperature and g ressure, can be related to DNB through the use of a DNB Correlation.

NB Correlations have been developed to predict DNB and the location of DNB for axially uniform and nonuniform heat flux distributions. The local DNB ratio (DNBR)i defined as the ratio of the heat flux that would cause DNB at a particu ar core location to the actual heat flux, is indicative of the margin to DNB. The minimum value of the DNBR, during steady-state operation, normal operational transients, and anticipated transients is limited to DNB correlation safety limit. A DNBR equal to the DNB correlation safety limit corresponds to a 95% probability at a 95% confidence level that DNB will not occur which is considered an appropriate margin to DNB for all operating conditions.

The reactor protective system is designed to prevent any anticipated combination of transient conditions for primary coolant system temperature, pressure and thermal power level that would result in a DNBR of less than the DNB. . . c.o.r.relation safety limit. The Palisades safety analyses uses twe t.:b.Jtel DNB correlations. The XNB correlation discussed in References l"""arfcf"""2 determines the safety limit for those fuel assemblies initially loaded prior to Cycle 9. The ANFP correlatioR discussed iR RefereRces 4 aRd S determiRes the safety limit for those fuel assemblies iRitially loaded iR Cycle 9 aRd later. Fuel assemblies iRitially loaded prior to Cycle 9 are of a differeRt coRstructioR thaR The miRimum DNBR aRalyses are iR accordaRce with RefereRce 6.

References XN-NF-62l(P)(A), Rev 1 2 XN-NF-709 3 Updated FSAR, Section 14.1.

4 ANF-1224 (P)(A), May 1989 5 ANF-89-192f PA January 1990

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Amendment No. 3-1-, 43-, H-8, 3-7, §G, §.e, Jw=ie 16, 1993 B 2-1