ML17332A765

Proposed Tech Specs,Modifying TS 3.7.1.1,Table 3.7-1 & Associated Bases

ML17332A765
Person / Time
Site:	Cook
Issue date:	05/19/1995
From:	INDIANA MICHIGAN POWER CO. (FORMERLY INDIANA & MICHIG
To:
Shared Package
ML17332A764	List: ML17332A763 ML17332A765
References
NUDOCS 9505240168
Download: ML17332A765 (26)

Text

ATTACHMENT 2 TO AEP:NRC:1213 EXISTING TECHNICAL SPECIFICATION PAGES MARKED TO REFLECT PROPOSED CHANGES 9505240168 950519 PDR ADOt K 05000315 P PDR

3 4.7 SYS EMS 3 4.7.1 TURBINE CYCLE SAFETY VALVES IM T NG CONDI ION FOR OPERAT ON 3.7.1.1 All main steam line code safety valves associated with each steam generator shall be OPERABLE.

~CT ON:

mots iZ2: Vo.lu~b> a~

a. 4 With 4 reactor coolant loops and associate steam generators with one or more main steam 1 ne code safety valves operation, in'peration~and inoperable, ma proceed provide~that within 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />, either the inoperable restored to OPERABLE sta~ or the Power Range Neutron Flux High Setpoint trip is reduced per Table 3.7-1; otherwise, be in AMeee HOT STANDBY within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and .comply b.

4)~ ~~ i51+4~+ 4o (Wit 3 reactor coolant loops and associated steam generators in peration~and with one or more main steam line code safety valves associated with an operating loop inoperable, operation 4a-KGB~

may proceed- providedg that within 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />, either the inoperable vie-ks.restored to OPERABLE status~ or the reactor trip breakers are opened; otherwise, be in~ Hog SHUTDOWN within the next 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />.

c. The provisions of Specification 3.0.4 are not applicable.

SURVEILLANCE RE UIREMENTS 4.7.1.1 Each main steam line code safety valve shall be demonstrated OPERABLE in accordance with Specification 4.0,5 and with lift settings as shown in Table 4.7-1. The safety valve shall be reset to the nominal value ~1Xwhenever found.

outside the +1X tolerance.

COOK NUCLEAR PLANT - UNlT 1 3/4 7-1 AHENDmVr NO.

'TABLE 3.7-l I E S F~SII MAXiMUM ALLOWABLE POWER RAHGE HEUTAOH FLUX I

IIIGII SETPOlHT MITll IHOPERABLE STEAM IRlp IpETlflllli Maximum AIIoeable Power Range

~

Haxioem Humber of Inoperable Safety= Heutron Flux lligh Setpoint Valves on An 0 eratin Steam Generator Percent of RATED THERMAL POllER 65 2 43-.4 28. G

/4 7

/4 7 M+$ 1 \' tC V V<

The OPERABILITY of the main steam line code safety valves ensures that the secondary system pressure will be limited to within its design pressure of 1085 psig during the most severe anticipated system opera-tional transient. The maximum relieving capacity is assoc'ated with a turbine trip from 100% RATED THER~ POVER coincident with an assumed loss of condenser heat sink (i.e., no steam bypass to the condenser).

The specified valve lift settings and relieving capacities are in accordance with the requirements of Section III of the ASME Boiler and Pressure Code, .1971 Edition. The total relieving capacity for all valves on all of the 'steam lines fs 17,153,800'bs/hr which is approximately 121 percent of the total secondary steam flow of 14,120,000 lbs/hr at 100%

RATED THERMAL POWER. A minimum of 2 OPERABLE safety valves per operable steam generator ensures that sufficient relieving capacity is available for the allowable THER'. POPE restriction in Table 3.7-1.

STARTUP and/or POVER OPERATION is allo~able wi th sa fe ty valves inoperable within the limitations of the ACTION requirements on the basis of the reduction in secondary system steam flow and THER'fAL POVER required by the reduced reactor trip settings of the Power Range Neutron Flux channels. The reactor trip setpoint reductions are derived on the following bases:

For 4 loop operation

+plaza 4ABL SP a.Bad&

'X.

'4here:

SP reduced react trip setpoin an percent of RATED THERMAL POVER V maximum number of'n able safety valves per steam line 1,2or3.

X - Total reliev ng capacity of al safety valves per steam line 4 8,450 lbs/hour.

Y Max'm relieving capacity of any one s ety valve 57,690 lbs/hour.

(10 - Po~er Range Neutron Flux-High Trip Setpoint for loop operation.

D. C. COOK - UNIT 1 B 3/4 7-1 AMENDMENT NO. 120

Re lacement text for 3/4.7.1.1 Bases (4wpg Hi 4 ~(100IQ)

K where:

Hi 4 = Safety Analysis power range high neutron flux setpoint in percent Q = Nominal NSSS power rating of the plant (including reactor coolant pump heat) in Mwt Conversion factor, 947.82 ~Bloinec

'Mwt w2 Minimum total steam flow rate capability of the operable MSSVs on any one steam generator at the highest MSSV opening pressure including tolerance and accumulation, as appropriate, in lb/sec. For example, if the maximum number. of inoperable MSSVs on any one steam generator is one, then w, should be a summation of the capacity of the operable MSSVs at the highest operable MSSV operating pressure, excluding the highest capacity MSSV. Ifthe maximum number of inoperable MSSVs per steam generator is three, then w, should be a summation of the capacity of the operable MSSVs at the highest operable MSSV operating pressure, excluding the three highest capacity MSSVs.

h= Heat of vaporization for steam at the highest MSSV opening pressure including tolerance and accumulation, as appropriate in Btu/ibm 4 = Number of loops in plant The values calculated from this algorithm are then adjusted lower for use in Technical Specification 3.7.1.1 to account for instrument and channel uncertainties by 9%. This reduces the maximum plant operating power level so that it is lower than the reactor protection system setpoint by an appropriate operating margin.

3 4 . 7 PLANT SYSTEMS 3 4.7. URSINE CYCLE S F Y VA VES NG COND 0 FOR OPERATION 3.7.1.1 All cain acean line cede saZecy valves associated sich each acean generator shall be OPERABLE.

~CT ON: ~~

glooms d.82: Va[VCS~

a. With 4 reaceor coolant loops and associaee steam generaeors in operaeion and with one or more main steam 1 ne code safety valves inoperabli, operation ma proceed providedg that within 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />, either the inoperable restored to OPERABLE status> or che Power Range Neueron Flux High Trip Setpointis reduced per Table 3.7-1; otherwise, be in ae-4eeee HOT STANDBY within the uj~ ash~ ~~~

next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and b.

b. 4Wi 3 reaceor coolant loops and associated steam generators in

. comply operation~and with one or more main seeam line code safety valves associated with an operaeing loop inoperable, operacion may proceed providedg that within 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />, either ehe inoperable

~8~

441~)4W ~o-ka restored eo OPERABLE status/or che reactor trip breakers are opened; otherwise, be in QGKB SHUTDOWN within che next 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />.

HaT'.

The provisions'f Specification 3.0.4 are not applicable.

SURVEILLANCE RE REMENTS 4.7.1.1 Each main steam line code safety valve shall be demonstrated OPERABLE in accordance with Specification 4.0e5 and with life settings as shown in Table 4.7-1. The safety valve shall be resee to the nominal value pl%whenever found outside the +1X eolerance.

COOK NUCLEAR PLANT - UNIT.2 3/4 7-1 AMENDMENT NO. 88, 367

TABLE 3 I ALLOWABLE POWER RANGE NEUTRON FLUX HIGH SETPOINT WITH INOPERABLE ST LINE SAFETY VALVES DURING 4 LOOP OPERAT 0 Maximum Allowable Power Range Maximum Number of Inoperable Safety Neutron Flux High Setpoint Valves on n 0 cretin Steam Generator Percent of RA ED THERMAL OWE COOK NUCLEAR PLANT - UNIT 2 3/4 7-2

3 4.7 PLANT SYSTEMS BASES 3 4.7.1 TURBINE CYCLE 3 4.7.1.1 SAFETY VALVES The OPERABILITY of the main steam line code safety valves ensures that the secondary system pressure vi11 be limited to vithin 110% of its design pressure of 1085 psig during the most severe anticipated system operational transient. The maximum relieving capacity is associated vith a turbine trip from 100% RATED THERMAL POVER coincident vith an assumed loss of condenser heat sink (i.e., no steam bypass to the condenser).

The specified valve lift settings and relieving capacities are in accordance vith the requirements of Section III of the ASME Boiler and Pressure Code, 1971 Edition. The total relieving capacity of all safety valves on all of the steam lines is 17,153,800 lbs/hr vhich is at least 105 percent of the maximum secondary steam flov rate at 100% RATED THERMAL POWER. h minimum. of 2 OPERABLE safety valves per steam generator ensures that sufficient relieving capacity is available for the allovable THERMAL POVER restriction in Table 3.7-1.

STARTUP and/or POVER OPERATION is allovable vith safety valves inoperable vithin the limitations of the ACTION requirements on the basis of the reduction in secondary system steam ilov and THERMAL POVER required by the reduced reactor trip settings of the Pover Range Neutron Flux channels. The reactor trip setpoint reductions are derived on the folloving bases:

For 4 loop operation Rq4,ca, Mhere: Acth a.~%ah SP reduced reac trip setpoint in per nt of RATED THERMAL POQER V maximum number of inope e safety valves per steam line X~ total relievin capacity of all s ty valves per steam line in lb ours 4,288,450 Y max relieving capacity of any one safe alve lbs./hour 857,690 9 Pover Range Neutron Flux-High Trip Setpoint for 4 loop operation COOK NUCLEAR PLANT - UNIT 2 B 3/4 7 1 AMENDMENT NO. Hl, 134

Re lacement text for 3/4.7.1.1 Bases (4wp<p Hi 4 =(100/Q)

K where:

Hi 4 = Safety Analysis power range high neutron flux setpoint in percent Q = Nominal NSSS power rating of the plant (including reactor coolant pump heat) in Mwt Conversion factor, 947.82 ~Btni8ec Mwt W8 Minimum total steam flow rate capability of the operable MSSVs on any one steam generator at the highest MSSV opening pressure including tolerance and accumulation, as appropriate, in lb/sec. For example, if the maximum number. of inoperable MSSVs on any one steam generator is one, then w, should be a summation of the capacity of the operable MSSVs at the highest operable MSSV operating pressure, excluding the highest capacity MSSV. If the maximum number of inoperable MSSVs per steam generator is three, then w, should be a summation of the capacity of the operable MSSVs at the highest operable MSSV operating pressure, excluding the three highest capacity MSSVs.

h<< = Heat of vaporization for steam at the highest MSSV opening pressure including tolerance and accumulation, as appropriate in Btu/ibm 4 = Number of loops in plant The values calculated from this algorithm are then adjusted lower for use in Technical Specification 3.7.1.1 to account for instrument and channel uncertainties by 9%. This reduces the maximum plant operating power level so that it is lower than the reactor protection system setpoint by an appropriate operating margin.

ATTACHMENT 3 TO AEP:NRC:1213 PROPOSED REVISED TECHNICAL SPECIFICATION PAGES

3/4 LIMITINGCONDITIONS FOR OPERATION AND SURVEILLANCEREQUIREMENTS 3/4.7 PLANT SYSTEMS 3/4.7.1 TURBINE CYCLE SAFETY VALVES LIMITINGCONDITION FOR OPERATION 3.7.1.1 All main steam line code safety valves associated with each steam generator shall be OPERABLE.

APPLICABILITY: MODES 1, 2 and 3.

ACTION:

MODES 1 & 2: With 4 reactor coolant loops and associated steam generators in operation, and with one or more main steam line code safety valves inoperable, operation may proceed provided that within 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />, either the inoperable valve(s) are restored to OPERABLE status, or the Power Range Neutron Flux High Setpoint trip is reduced per Table 3.7-1; otherwise, be in HOT STANDBY within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and comply with actiori statement b.

b. MODE 3: With a minimum of 3 reactor coolant loops and associated steam generators in operation, and with one or more main steam line code safety valves associated with an operating loop inoperable, operation may proceed provided that within 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />, either the inoperable valve(s) are restored to OPERABLE status, or the reactor trip breakers are opened; otherwise, be in HOT SHUTDOWN within the next 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />.

c. The provisions of Specification 3.0.4 are not applicable.

SURVEILLANCE RE UIREMENTS 4.7.1.1 Each main steam line code safety valve shall be demonstrated OPERABLE in accordance with Specification 4.0.5 and with liftsettings as shown in Table 4.7-1. The safety valve shall be reset to the nominal value +1% whenever found outside the J1% tolerance.

COOK NUCLEAR PLANT-UNIT 1 Page 3/4 7-1 AMENDMENT ~, 4', 4Q

3/4 LIMFI'INGCONDITIONS I<'OR OPERATION AND SURVEILLANCE REQUIREMENTS 3/4.7 PLANT SYSTEMS TABLE 3.7-1 MAXIMUMALLOWABLEPOWER RANGE NEUTRON FLUX HIGH SETPOINT WITH INOPERABLE STEAM LINE SAFETY VALVES DURING 4 LOOP OPERATION Maximum Number of Inoperable Safety Valves on Maximum Allowable Power Range Neutron Flux Any Operating Steam Generator High Setpoint (Percent of RATED THERMAL POWER) 65.1 46.5 28.0 COOK NUCLEAR PLANT<<UNIT 1 Page 3/4 7-2

s 3/4 BASES 3/4.7 PLANT SYSTEMS 3/4.7.1 TURBINE CYCLE 3/4.7.1.1 SAFETY VALVES The OPERABILITY of the main steam line code safety valves ensures that the secondary system pressure will be limited to within 110% of its design pressure of 1085 psig during the most severe anticipated system operational transient. The maximum relieving capacity is associated with a turbine trip from 100% RATED THERMAL POWER coincident with an assumed loss of condenser heat sink (i.e., no steam bypass to the condenser).

The specified valve lift settings and relieving capacities are in accordance with the requirements of Section III of the ASME Boiler and Pressure Code, 1971 Edition. The safety valve is OPERABLE with a lift setting of J3%

about the nominal value. However, the safety valve shall be reset to the nominal value J 1% whenever found outside the J1% tolerance. The total relieving capacity for all valves on all of the steam lines is 17,153,800 lbs/hr which is approximately 121 percent of the total secondary steam flow of 14,120,000 lbs/hr at 100% RATED THERMAL POWER. A minimum of 2 OPERABLE safety valves per operable steam generator ensures that sufficient relieving capacity is available for the allowable THERMAL POWER restriction in Table 3.7-1.

STARTUP and/or POWER OPERATION is allowable with safety valves inoperable within the limitations of the ACTION requirements on the basis of the reduction in secondary system steam flow and THERMAL POWER required by the reduced reactor trip settings of the Power Range Neutron Flux channels. The reactor trip setpoint reductions are derived on the following bases:

(4wJ1 )

Hi C =(100/Q)

K where:

Hi4 = Safety Analysis power range high neutron flux setpoint in percent Q = Nominal NSSS power rating of the plant (including reactor coolant pump heat) in Mwt Conversion factor, 947.82 ~Btn/Sec Mwt ws = Minimum total steam flow rate capability of the operable MSSVs on any one steam generator at the highest MSSV opening pressure including tolerance and accumulation, as appropriate, in lb/sec. For example, if the maximum number of inoperable MSSVs on any one steam generator is one, then w, should be a summation of the capacity of the operable MSSVs at the highest operable MSSV operating pressure, excluding the highest capacity MSSV. If the maximum number of inoperable MSSVs per steam generator is three, then w, should be a summation of the capacity of the operable MSSVs at the highest operable MSSV operating pressure, excluding the three highest capacity MSSVs.

Heat of vaporization for steam at the highest MSSV opening pressure including tolerance and accumulation, as appropriate in Btu/ibm 4 = Number of loops in plant The values calculated from this algorithm are then adjusted lower for use in Technical Specification 3.7.1.1 to account for instrument and channel uncertainties by 9%. This reduces the maximum plant operating power level so that it is lower than the reactor protection system setpoint by an appropriate operating margin.

COOK NUCLEAR PLANT>>UNIT 1 Page B 3/4 7-1 AMENDMENT480

3/4 LIMITINGCONDITIONS FOR OPERATION AND SURVEILLANCEREQUIREMENTS 3/4.7 PLANT SYSTEMS 3/4.7.1 TURBINE CYCLE SAFETY VALVES LIMITINGCONDITION FOR OPERATION 3.7.1.1 All main steam line code safety valves associated with each steam generator shall be OPERABLE.

APPLICABILITY: MODES 1, 2 and 3.

ACTION:

MODES 1 & 2: With 4 reactor coolant loops and associated steam generators in operation, and with one or more main steam line code safety valves inoperable, operation may proceed provided that within 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />, either the inoperable valve(s) are restored to OPERABLE status, or the Power Range Neutron Flux High Setpoint trip is reduced per Table 3.7-1; otherwisc, be in HOT STANDBY within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and comply with action statement b.

b. MODE 3: With a minimum of 3 reactor coolant loops and associated steam generators in operation, and with one or more main steam line code safety valves associated with an operating loop inoperable, operation may proceed provided that within 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />, either the inoperable valve(s) are restored to OPERABLE status, or the reactor trip breakers are opened; otherwise, be in HOT SHUTDOWN within the next 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />.

c. The provisions of Specification 3.0.4 are not applicable.

SURVEILLANCE RE UIREMENTS 4.7.1.1 Each main steam line code safety valve shall be demonstrated OPERABLE in accordance with Specification 4.0.5 and with liftsettings as shown in Table 4.7-1. The safety valve shall be reset to the nominal value J1% whenever found outside the +1% tolreance.

COOK NUCLEAR PLANT-UNIT2 Page 3/4 7-1 AMENDMENT82, 447.

3/4 LIMITINGCONDITIONS FOR OPERATION AND SURVEILLANCEREQUIREMENTS 3/4.7 PLANT SYSTEMS TABLE 3.7-1 MAXIMUMALLOWABLEPOWER RANGE NEUTRON FLUX HIGH SETPOINT WITH INOPERABLE STEAM LINE SAFETY VALVES DURING 4 LOOP OPERATION Maximum Allowable Power Range Maximum Number of Inoperable Safety Neutron Flux High Setpoint Valves on Any Operating Steam Generator (Percent of RATED THERMAL POWER) 61.6 43.9 26.2 COOK NUCLEAR PLANT-UNIT2 Page 3/4 7-2

s 3/4 BASES 3/4.7 PLANT SYSTEMS 3/4.7.1 TURBINE CYCLE 3/4.7.1.1 SAFETY VALVES The OPERABILITY of the main steam line code safety valves ensures that the secondary system pressure will be limited to within 110% of its design pressure of 1085 psig during the most severe anticipated system operational transient. The maximum relieving capacity is associated with a turbine trip from 100% RATED THERMAL POWER coincident with an assumed loss of condenser heat sink (i.e., no steam bypass to the condenser).

The specified valve lift settings and relieving capacities are in accordance with the requirements of Section III of the ASME Boiler and Pressure Code, 1971 Edition. The safety valve is OPERABLE with a lift setting of +3%

about the nominal value. However, the safety valve shall be reset to the nominal value ~1% whenever found outside the +1% tolerance. The total relieving capacity of all safety valves on all of the steam lines is 17,153,800 lbs/hr which is at least 105 percent of the maximum secondary steam flow rate at 100% RATED THERMAL POWER. A minimum of 2 OPERABLE safety valves per steam generator ensures that sufficient relieving capacity is available for the allowable THERMAL POWER restriction in Table 3.7-1.

STARTUP and/or POWER OPERATION is allowable with safety valves inoperable within the limitations of the ACTION requirements on the basis of the reduction in secondary system steam flow and THERMAL POWER required by the reduced reactor trip settings of the Power Range Neutron Flux channels. The reactor trip setpoint reductions are derived on the following bases:

(4wh )

Hi@=(100/Q)

K where:

Hi 4 = Safety Analysis power range high neutron flux setpoint in percent Q = Nominal NSSS power rating of the plant (including reactor coolant pump heat) in Mwt K ='onversion factor, 947.82 ~Bto/Sec Mwt w, = Minimum total steam flow rate capability of the operable MSSVs on any one steam generator at the highest MSSV opening pressure including tolerance and accumulation, as appropriate, in Ib/sec. For example, if the maximum number of inoperable MSSVs on any one steam generator is one, then w, should be a summation of the capacity of the operable MSSVs at the highest operable MSSV operating pressure, excluding the highest capacity MSSV. Ifthe maximum number of inoperable MSSVs per steam generator is three, then w, should be a summation of the capacity of the operable MSSVs at the highest operable MSSV operating pressure, excluding the three highest capacity MSSVs.

h= Heat of vaporization for steam at the highest MSSV opening pressure including tolerance and accumulation, as appropriate in Btu/ibm 4 = Number of loops in plant The values calculated from this algorithm are then adjusted lower for use in Technical Specification 3.7.1.1 to account for instrument and channel uncertainties by 9%. This reduces the maximum plant operating power level so that it is lower than the reactor protection system setpoint by an appropriate operating margin.

COOK NUCLEAR PLANT-UNIT2 Page B 3/4 7-1

ATTACHMENT 4 TO AEP:NRC:1213 WESTINGHOUSE NSAL 94-001 "OPERATION AT REDUCED POWER LEVELS WITH INOPERABLE MSSV'S"

Westinghouse 0

Energy NUCLEAR SAFETY ADVISORY LETTER Systems business Unit

'HIS IS A NOTIFICATION OF A RECENTLY IDENTIFIED POTENTIAL SAFETY ISSUE PERTAINING TO BASIC BY WESTINGHOUSE. THIS INFORMATIONIS BEING PROVIDED TO YOU SO THAT A REVIEW OF THIS ISSUE CAN BE COMPONENTS'UPPLIED CONDUCTED BY YOU TO DETERMINE IF ANY ACTION IS REQUIRED.

P. O. Box 355, Pittsburgh, PA 152304355

Subject:

Operation at Reduced Power Levels with Inoperablc MSSVs Number: NSAL-94401 Basic Component: Loss of Load/I'urbiac Trip Analysis for Plant Liceasing Basis Dates OI/20/94 Planta Sec Eaclosed List Subsiaaiial Safety Hazaid or Failure io Comply Pursuant to 10 CFR 21.21(a) Ycs0 No 8 Transfer of Information Pursuant to 10 CFR 21.21(b) Yes 0 Advisory Iafoimation Pursuant io 10 CFR 21.21(c)(2) Yes 0

SUMMARY

Westinghouse has identified a potential'safety issue regarding plant operation within Technical Specification Table 3.7-1. This issue does not represent a substantial safety hazard for your plant pursuant to 10 CFR 21. However, this issue does represent a condition which may impact your plant's licensing basis.

Table 3.7-1 allows plants to operate with a reduced number of operable MSSVs at a reduced power level, as deteanined by the high neutron fiux trip setpoint. The FSAR loss of load/turbine trip (LOIJIT) analysis from full power bounds the case where all MSSVs are openble. The FSAR (LOLfFQ event may not be bounding for the allowable operating configurations of Table 3.7-1 since tbe high neutron fiux trip setpoint, which is identiTied in Table 3.7-1 for a corresponding number of inoperable MSSVs, may not be low enough to preclude a secondary side oveipressurization condition. As a result, the basis for Table 3.7-1 may not be suIIicient to preclude overptessurization of the secondary side of the steam generator.

Therefore, it is recommended that you review the enclosed infoanation to detemune the applicability of this issue to your phnt.

The enclosed information contains a more detailed description of the issue and identifies solutions that you may wish to pursue to address this issue. These solutions include, but are not limited to, a reevaluation of the LOIJIT analysis and/or a change to Technical Specification Table 3.7-1.

P Additional infoimation, ifrequired, may be obtained from the originator. Telephone 412-3744460.

Odgiaatoc

. W. Fasnacht K A. Sepp, Manager, Strategic Licensing Issues Strategic Licensing Issues t.'i0418.wpf: Ib412094

Plants Affected D. C. Cook I &2 J. M. Parley I & 2 Byron1 &2 Braidwood I & 2 V. C. Summer I Zion1 &2 Shearon Haais I W. B. McGuire I & 2 Catawba I & 2 Beaver Valley I & 2 Turkey Point 3 & 4 Vogtle I &2 indian Point 2 & 3 Seabrook I Millstone 3 Diablo Canyon I &2 Wolf Creek Callaway I Comanche Peak I & 2 South Texas I & 2 Sequoyah I & 2 North Anna I & 2 Watts Bar I &2 Sizewell B Kori 1,2,3 &4 Yonggwang I &2 Salem I &2 a%418.vrpf:tb411994

Issue Descri tion Westinghouse has identified a deficiency in the basis for Technical Specification 3.7.1.1. This Technical Specification aHows the plant to operate at a reduced power level with a reduced number of operable Main Steam Safety Valves (MSSVs). The deficiency is in the assumption that the maximum allowable initial power level is a linear function of the available MSSV relief capacity. The linear function is identified in the Bases Section for Technical Specification 3/4.7.1.1 and is provided as follows:

SP (X) (Y)P) ~

(109)

X SP = Reduced reactor trip setpoint in 9o of RATED THERMALPOWER V = Maximum number of inoperable safety valves per steam line X = Total relieving capacity of all safety valves per steam line in ibm/hour Y = Maximum relieving capacity of any one safety valve in ibm/hour (109) = Power range neutron flux-high trip setpoint for all loops in operation Under certain conditions and with typical safety analysis assumptions, a Loss of Load/'turbine Trip transient from part-power conditions may result in overpressurization of the main steam system when operating in accordance with this Technical Specification. 'Ihe following discussion describes the issue in more detail and provides recommended alternatives for addressing the issue.

Technical Evaluation The Loss of Load/Turbine Trip (LOIJIT) event is analyzed in the FSAR to show that core protection margins are maintained (DNBR), the RCS will not overpressurize, and the main steam system will not overpressuiize. The analysis assumes an immediate loss of steam relieving capability through the turbine and coincident loss of all main feedwater. No credit is taken for the direct reactor trip on turbine trip, since this trip would not be actuated for the case of a loss of steam load. Rather, the transient is terminated by a reactor trip on high pressurizer pressure, overtempeiature dT, or low steam generator water level. Secondary side overpressure protection is provided by actuation of the Main Steam Safety Valves (MSSVs), which are designed to relieve at least full power nominal steam flow.

'Ihe analysis verifies that the MSSV capacity is sufficient to prevent secondary side pressure fiom .

exceeding 110 percent of the design pressure.

a%418.wpf: tb41 1994

The FSAR only analyzes the LQIJIT transient Qom the full power initial condition, with cases examining the effects of assuming primary side pressure control and different reactivity feedback conditions. Vfith fully operational MSSVs, it can be demonstrated that overpressure protection is provided for all initial power levels. However, for most plants, Technical Specification 3.7.1.1 allows operation with a reduced number of operable MSSVs at a reduced power level as determined by resetting the power range high neutron flux setpoint. 'Ihis Technical Specification is not based on a detailed analysis, but rather on the assumption that the maximum allowable initial power level is a linear function of the available MSSV relief capacity. Recently, it has been determined that this assumption is not valid.

The problem is that if main feedwater is lost, a reactor trip is necessary to prevent secondary side overpressurization for all postulated core conditions. At high initial power levels a reactor trip is actuated early in the transient as, a result of either high pressurizer pressure or overtemperature hT.

The reactor trip terminates the transient and the MSSVs maintain steam pressure below 110% of the design value.

At lower initial power levels a reactor trip may not be actuated early in the transient. An overtemperatum hT trip isn't generated since the core thermal margins are increased at lower power levels. A high pressurizer pressure trip isn't generated ifthe primary pressure control systems function normally. Mis results in a longer time during which primary heat is transferred to the secondary side.

The reactor eventually, trips on low steam generator water level, but this may not occur before steam pressure exceeds 110% of the design value if one or more MSSVs are inoperable in accordance with the Technical Specification.

Due to the-wide variety of plant design features that are important to the LOIJIT analysis, it is difficult to perform a generic evaluation to show that the issue does not apply to certain plants. 'Ihe following key parameters have a significant effect on the secondary side pressure transient:

MSSV relief capacity Moderator Temperature Coefficient (hflC)

Margin between the MSSV set pressures (including tolerance) and the overpressure limit Low-low steam generator water level reactor trip setpoint Safet Si nificance The Technical Specifications for most plants allow operation at a reduced power level with inoperable MSSVs. From a licensing basis perspective, this condition may result in secondary side overpressurization in the event of a LOIJIT transient. 'Ihe Hcensing basis for anticipated operational occurrences (ANS Condition II events) typically requires that the secondary side pressure remain below 110% of the design value.

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Westinghouse has determined that this issue does not represent a substantial safety hazard. There are several mitigating factors which provide assurance that there is no loss of safety function to the extent that there is a major reduction in the degree of protection provided to the public health and safety.

These include, but are not limited to, the following:

1. Adequate overpressure protection is provided at all power levels ifall of the MSSVs are operable.

2. Ifa reactor trip does not occur but main feedwater flow is maintained, operation in accordance with the Technical Specification Table 3.7-1 will not result in an overpressure condition.

3. In any LOIJIT transient, the abnospheric steam dump valves and/or condenser steam dump valves actuate to relieve energy 6'om the steam generators prior to the opening of the MSSVs, and continue to relieve steam if the MSSVs do open. Since it is not a safety-grade function. steam dump is not assumed to operate in the safety analysis; however, in reality it is the first line of defense in protecting the secondary system against overpressurization. It is very improbable that all these components would be inoperable coincident with inoperable MSSVs.

4. Even near the beginning of core life with a positive or ~ro MTC, the primary coolant heatup resulting from the transient would tend to drive the MTC negative, which would .

reduce the core power and heat input to the coolant. This would result in'a lower required MSSV capacity to prevent secondary overpressurization. The safety analysis does not credit the reduction of MTC during the transient.

NRC Awareness / Re ortabilit Westinghouse has not notified the NRC of this issue, based upon the determination that it does not represent a substantial safety hazatd pursuant to 10 CFR 21. However, Westinghouse wiH send a copy of this letter to the NRC since this issue impacts information contained in NUREG-1431, "Standard Technical Specifications, Westinghouse Plants".

Recommendations To address this issue, the following actions may be considered:

(I) Modify Technical Specification 3.7.1.1 (or equivalent) and the associated basis such that the maximum power level allowed for operation with inoperable MSSVs is below the heat removing capability of the operable MSSVs. A conservative way to do this is to set the power range high neutron flux setpoint to this power level, thus ensuring that the actual power level cannot exceed c%418wpf: tb41 1994

this value. To calculate this setpoint, the governing equation is the relationship q = m hh, where q is the heat input Rom the primary side, m is the steam flow rate and hh is the heat of vaporization at the steam relief pressure (assuming no subcooled feedwater). Thus, an algorithm for use in defining the revised Technical Specification table setpoint values would be:

(w,h, N)

H y = (lOO/Q)

K where:

-

Hi fI2 = Safety Analysis power range high neutron flux setpoint, percent Q = Nominal NSSS power rating of the plant (including reactor coolant pump heat), Mwt K = Conversion factor, 947.82 (B toft co)

Mwt Wn Minimum total steam flow rate capability of the operable MSSVs on any one steam generator at the highest MSSV opening pressure including tolerance and accumulation, as appropriate, in lb/sec. For example, ifthe maximum number of inoperable MSSVs on any one steam generator is one, then w, should be a summation of the capacity of the operable MSSVs at the highest operable MSSV operating pressure, excluding the highest capacity MSSV. Ifthe maximum number of inoperable MSSVs per steam generator is three then w, should be a summation of the capacity of the operable MSSVs at the highest operable MSSV operating pressure, excluding the three highest capacity MSSVs.

heat of vaporization for steam at the highest MSSV opening pressure including tolerance and accumulation, as appropriate, Btu/ibm N = Number ofloopsin plant

'Ihe values calculated from this algorithm must then be adjusted lower for use in Technical Specification 3.7.1.1 to account for instrument and channel uncertainties (typically 99o power).

The maximum plant operating power level would then be lower than the reactor piotection system setpoint by an appropriate operating margin.

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~

~

~ I It should be noted that the use of this equation will resolve the issue identified in this letter by enabling you to reticulate your Technical Specification 3.7.1.1 setpoints without further modifications to the structure of the Technical Specification. The re-calculated setpoints are likely to be lower than those currently allowed by the Technical Specification. However, you should be aware of at least two conservatisms with the equation. You may wish to review these conservatisms to evaluate the use of the equation relative to your plant specific operating objectives. It is possible to relax some of these conservatisms for use in the Technical Specification. However, relaxation of the conservatisms are likely to result in more significant changes to the structure of the Technical Specification.

First, the above equation (and the existing Technical Specification 3.7.1.1) is conservative since it is based on the maximum number of inoperable MSSVs per loop. For example, a representative four loop plant, in accordance with the current Technical Specifiication. should reduce the neutron flux setpoint to 87% ifit has up to one inoperable MSSV on each loop.

This means that the plant should use this setpoint whether there are one, two, three or four inoperable MSSVs, as long as there is only one inoperable MSSV per loop. 'Ihus, the existing Technical Specification and the above equation are conservative and bounding. However, any relaxation of this conservatism must be interpreted with care. Ihe reason is that the steam generators must be protected Rom an overpressurization condition during a loss of load transient. There are several events that could lead to a loss of load, including the inadvertent closure of one or all MSIVs. The affected steam generator must have a sufficient number of if operable MSSVs to protect it from an overpressurization condition, the MSIV (or MSIVs) was inadvertently closed.

Another conservatism in the above equation (and the existing Technical Specification 3.7.1.1) is in ws, which is the minimum total steam flow rate capability of the operable MSSVs on any one steam generator. This value is conservative since it assumes that ifone or more MSSVs are inoperable per loop, the inoperable MSSVs are the largest capacity MSSVs, regardless of whether the largest capacity MSSVs or the smaller capacity MSSVs are inoperable. The assumption has been made so that the above equation is consistent with the current structure of Technical Specification 3.7.1.1.

As an alternative, plant-specific LOIJIT analyses could be performed to maximize the allowable power. level for a given number of inoperable MSSVs. Depending on key specific plant parameters, these analyses may be able to justify the continued validity of the current Technical Specification.

(3) Consider modifying, as required, the Bases Section for Technical Specification 3/4.7.1.1 so that it is consistent with the plant safety analysis. 'Ilie safety analysis criterion for preventing overpressurization of the secondary side is that the pressure does not exceed 110% of the design pressure for anticipated transients. However, in reviewing several plant technical specifications,

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it was noted that the bases for some plants state that the safety valves insure that the secondary system pressure will be limited to within 105 or even 100% of design pressure. This is not consistent with the safety analysis basis and should be revised to indicate 1109o.

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