ML18039A220

Application for Amends to Licenses DPR-33,DPR-52 & DPR-68, Consisting of TS Change 395,removing non-conservatism Associated W/Lco 3.5.C, RHR Svc Water & Eecw.

ML18039A220
Person / Time
Site:	Browns Ferry
Issue date:	12/30/1997
From:	Abney T TENNESSEE VALLEY AUTHORITY
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML18039A221	List: ML18039A220 ML18039A222
References
TVA-BFN-TS-395, NUDOCS 9801090085
Download: ML18039A220 (36)

Text

ENCLOSURE 1 TENNESSEE VALLEY AUTHORITY BROWNS FERRY NUCLEAR PLANT (BFN)

Units. 1, 2, and 3 DOCKET NOS 259, 260, and 296 PROPOSED TECHNICAL SPECIFICATION (TS) CHANGE TS-395 DESCRIPTION AND EVALUATION OF THE PROPOSED CHANGE I. DESCRIPTION OF THE PROPOSED CHANGE TVA is revising Units 1, 2, and 3 current TS Table 3.5-1, Minimum Residual Heat Removal Service Water (RHRSW) and Emergency Equipment Cooling Water (EECW) Pump Assignment, to identify the number of pumps required to be operable for RHRSW alignment for unrestricted operation under the one, two and three unit fueled conditions. The additional pump will not be required if the .operable pumps are supplied from separate 4KV shutdown boards. Clarifying notes were added to Table 3.5-1.

Specifically, Note "C" is added to the '7-day action time requirements for the one unit fueled condition for compatibility with the corresponding 7-day LCO for RHR heat exchanger operability requirements contained in TS 3.5.B.3. Note "D"

. ~ allows the minimum RHRSW pump requirements to be reduced by one pump for each unit when in cold shutdown condition for more than 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.

A change to the proposed'onversion to Improved Technical Specifications (ITS) format (TS-262 submitted September 6, 1996) is also requested to increase the number of operable RHRSW pumps for multi-unit operation. The specific changes are described below.

1. Current TS Table 3.5-1 and note on page 3.5/4.5-11 for Units 1, 2, and 3.

Table 3.5-1 and note reads:

Minimum RHRSW and EECW Pump Assignment 1 Unit Fueled 2 Units Fueled 3 Units Fueled Time (2 Units (1 Unit Limit Defueled) Defueled)

RHRSW EECW(A) RHRSW EECW(A) RHRSW EECW(A)

None 4 and 3 5 and 3 7 and 3 30 Days 3 and 2 5 and 2 7 and 2 (or) (or) 4 and 3 6 and 3 7 Days 2 and 2 4 and 2 6 and 2 Note:

(A) At least one OPERABLE pump must be assigned to each header. Only automatically starting pumps may be assigned to EECW header service.

Proposed Table 3.5-.1 and notes:

Minimum RHRSW and EECW Pump Assignment 1 Unit Fueled 2"Units Fueled 3 Units Fueled Time (2 Units (1 Unit Limit Defueled) Defueled)

RHRSW EECW(A) RHRSW EECW(A) RHRSW EECW(A) 5 (B) (D) and 3 8 (D) and 3 None 4 (D) and 3 (or) 6 (D) and 3 5 and 2 7 and 2

.30 Days 3 and 2 (or) (or) 4 and 3 6 and 3 7 Days 2(C) and 2 4 and' and 2 Notes:

(A) At least one OPERABLE pump must be assigned to each header. Only automatically starting pumps may be assigned to EECW header service.

(B) When each pump is aligned to a separate 4-kv shutdown board.

(C) This condition is satisfied with 2 RHRSW pumps when each pump is assigned to a separate RHRSW. header.

(D) For units with fuel loaded, the minimum RHRSW pump requirements may be reduced by one pump for each unit that has been in the COLD SHUTDOWN condition for more than 24 hours.

2. Current Bases 3'.5, second paragraph 3.5/4.5-29 for Unit TS 1, on page 3.5/4.5-27 for'niton2, page and on page 3.5/4.5-30 for Unit 3 is revised to read as follows (additional material is indicated by bo2d italics):

There are four RHR heat exchanger headers (A, B, C,

& D) with one RHR heat exchanger from each unit on each header. There are two RHRSW pumps on each header; one normally assigned to each header (A2, B2, C2, or D2) and one on alternate assignment (A1, B1, C1, or D1). 'One RHR heat exchanger header can

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adequately deliver the flow supplied by both RHRSW pumps to any two of the three RHR heat exchangers on the header. One RHRSW pump can supply the full flow requirement of one RHR heat exchanger. Two RHR heat exchangers can more than adequately handle the cooling requirements of one unit in any abnormal or post accident situation. When the decay heat level has decreased sufficiently following shutdown, the entire shutdown cooling load can be adequately handled by one RHR heat exchanger.

Current TS Bases 3.5, third paragraph on page 3.5/4.5-29 for Unit 1, on page 3.5/4.5-27 for Unit 2, and on page 3.5/4.5-30 for Unit 3 is revised as follows:

"The RHRSW Service Water System was designed as a shared system for three units. The specification, as written, is conservative when consideration is given to particular pumps being out of service and to possible valving arrangements. The minimum number pumps which are required to be operable by this of'EKSW specification ensure that the RHRSW system will satisfy its safety functions for all three units following a design basis event on one unit and a postulated single active failure. This includes a single failure of diesel generator A or B which would result in the loss. of two RHRSW pumps. If unusual operating conditions arise such that more pumps are out of service than allowed by this specification, a special case request may be made to the NRC to allow continued operation if the actual system cooling requirements can be assured."

ITS Notes 1. and 2. opposite LCO 3.7.1 and on page 3.7-1 for Units 1, 2, and 3 is deleted in its entirety and replaced with the following Note:

The number of required RHRSW pumps may be reduced by one for each fueled unit that has been in MODE 4 or 5 for 2 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.

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5. ITS LCO 3.7.1 and on page 3.7-1 for Units 1, 2, and 3 is deleted in its entirety and replaced with the following:

Four RHRSW subsystems shall be OPERABLE with the number of OPERABLE pumps as listed below:

1. 1 unit fueled four OPERABLE RHRSW pumps.

2. 2 units fueled six OPERABLE RHRSW pumps.

3. 3 units fueled eight OPERABLE RHRSW pumps.

6. ITS 3.7.1 The NOTE and ACTIONS on pages 3.7-1 through 3.7-3 for Units 1, 2, and 3 are deleted in their entirety and replaced with the following:

CONDITION REQUIRED ACTION COMPLETION TIME One required A 1 -------Notes------

RHRSW pump inoperable.

1. Only applicable for the 2 units fueled condition.

2. Only four RHRSW pumps powered from a separate 4kV shutdown board are required to be OPERABLE if the other fueled unit has been in MODE 4 or 5 for 2 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.

Verify 5 RHRSW Immediately pumps powered from separate 4kV shutdown boards are OPERABLE.

OR A.2 Restore required 30 days RHRSW pump to OPERABLE status.

7. ITS 3.7.1 NOTE and ACTIONS, continued:

CONDITION REQUIRED ACTION COMPLETION TIME B. One RHRSW B.1 ------Note-------

subsystem Enter applicable inoperable. Conditions and Required Actions of LCO 3.4.7, "Residual Heat Removal (RHR)

Shutdown Cooling Hot Shutdown,"

for RHR shutdown cooling made inoperable by the RHRSW system.

Restore RHRSW 30 days subsystem to OPERABLE status.

C. Two required C.1 Restore one 7 days RHRSW pumps inoperable RHRSW inoperable. pump to OPERABLE status D. Two RHRSW D.1 -------Note ----

subsystems Enter applicable inoperable. conditions and Required actions of LCO 3.4.7 for RHR shutdown cooling made inoperable by the RHRSW System.

Restore one RHRSW 7 days subsystem to OPERABLE status.

E. Three or more E.1 Restore one RHRSW 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> required RHRSW pump to OPERABLE pumps status.

inoperable

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8. ITS 3.7.1 NOTE and ACTIONS, continued:

CONDITION REQUIRED ACTION COMPLETION TIME F. Three or more F 1 ------Note-----

RHRSW Enter subsystems applicable inoperable. Conditions and Required Actions of LCO 3.4.7 for RHR shutdown cooling made inoperable by the RHRSW system.

Restore one 8 hours RHRSW subsystem to OPERABLE status.

G. Required G.1 Be in MODE 3. 12 hours Action and associated AND Completion Time not met. G.2 Be in MODE 4. 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />

9. ITS Bases 3.7.1, Background. The proposed change revises the second paragraph on page B3.7-1 for Units 1, 2, 3 as follows. (Deleted and added text is indicated by strikeouts and bold italics, respectively):

The RHRSW System is common to the three BFN units and consists of four independent and .redundant loops, each of which feeds one RHR heat exchanger in each unit. Each loop is made up of a header, two 4500 gpm pumps, a suction source, valves, piping, and associated instrumentation. One loop with one pump operating is capable of providing 50% of the required cooling capacity to maintain safe shutdown conditions

.for one unit.

As such, a subsystem consists of a loop with one or two OPERABLE pumps, a heat exchanger, a suction source, and associated valves, piping and instrumentation

The RHRSW System is designed with sufficient redundancy so that no single active component failure can prevent it from achieving its design function. The RHRSW System is described in the FSAR, Section 10.9 (Ref. 1);

ITS Bases 3.7.1, Background. The fourth paragraph on page B3.7-1 for Units 1, 2, 3 is revised as follows:

The system is initiated manually from each of the three units control rooms. If operating during a loss of coolant accident (LOCA), the system is automatically tripped on degraded bus voltage to allow the diesel generators to automatically power only that equipment necessary to reflood the core.

The system can be manually started any time the degraded bus voltage signal clears, and is assumed to be manually started within 10 minutes after the LOCA.

ITS Bases 3.7.1, Applicable Safety Analyses. A change is proposed to correct the analytical RHRSW flow assumption when two pumps are aligned to the same header. The third from the last sentence of the second paragraph on page B3.7.-2 is revised to read as follows for all three units:

The RHRSW flow assumed in the analyses is 4509 4000 gpm per pump with two pumps operating in one loop.

ITS Bases 3.7.1, Applicable Safety Analyses. The last sentence of the second paragraph on page B3.7-2 which currently reads "This is also below the 200'F limit imposed by design criteria BFN-50-7064A (Ref.

5) for all plant transients involving SRV operations." is deleted in its entirety for all three units.

ITS Bases 3.7.1, LCO. The Bases for the LCO on page B3.7-3 is revised as follows for all three units:

Four RHRSW subsystems are required to be OPERABLE to provide the required redundancy to ensure that the system functions to remove post accident heat loads, assuming the worst case single active failure occurs coincident with the loss of offsite power Additionally, since the RHRGH'umps are shared between 0he three BFN units, the number of OPERABLE pumps required is also dependent on the number of units fueled.

An OPERABLE RHRSW subsystem consists of an OPERABLE

flow path capab2e of taking suction from the intake structure and transferring the water to the required RHR heat exchangers at the assumed flow rate with at 2,east one OPERABLE RHRSH'ump in the f2.ow path.

In addition to the required number of OPERABLE subsystems, there must be an adequate number of'umps OPERABLE to provide cooling for the fueled non-accident units. The number of required OPERABLE RHRSF

.pumps required is modified by a Note which specifies that the number of required RHRSW pumps may be reduced by one for each fueled unit that has been in MODE 4 or 5 for over 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. This Note acknowledges the fact that decay heat removal requirements are substantially reduced for fueled units in Mode 4 or 5 for over 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.

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14. ITS Bases 3.7.1, Actions. The existing Bases for

.the TS 3.7.1 ACTIONS on pages B 3.7-3 through B 3.7-5 are deleted in their entirety for all three units and replaced with the following:

A.l and A.2 Required Action A.l requires immediate verification that five RHRSW pumps powered from separate 4kV shutdown boards are OPERABLE. The Required Action is modified by two notes. Note 1 indicates that the required action is applicable only when two units are fueled. In the two unit fueled condition a single failure (loss of a 4kV shutdown board) could result in inadequate RHRSW pumps if two pumps are powered from the same. power supply. This corresponds to the LCO requirement of six OPERABLE pumps when two units are fueled, which still provides the minimum required four RHRSW pumps with the worst case single failure.

If five RHRSW pumps are powered from separate 4kV shutdown boards, then no postulated single active failure could occur to prevent the RHRSW system from performing its design function. This is equivalent to any six RHRSW pumps operable with a maximum of two sets of two pumps allowed to be powered from the same power supply. Operation can continue indefinitely Required action A.l is met.

if Note 2 requires only four RHRSW pumps powered from separate 4KV shutdown boards to be OPERABLE other fueled unit has been in mode 4, or 5 greater if the than twenty-four hours. This acknowledges the fact that decay heat removal requirements are substantially reduced for fueled units in mode 4, or 5 for greater than twenty-four hours.

If Required action A.1 cannot be met, then Required Action A.2 must be complied with. With one RHRSW pump inoperable, the inoperable RHRSW pump must be restored to OPERABLE status within 30 days. With the unit in this, condition, the remaining OPERABLE RHRSW pumps are adequate to perform the RHRSW heat removal function. However, the overall reliability is reduced because a single failure could result in reduced primary containment cooling capability. The 30 day Completion Time is based on the availability of equipment in excess of normal redundancy requirements and, the low probability of an event occurring requiring RHRSW during this period.

i B.1 With one RHRSW subsystem inoperable, the inoperable RHRSW subsystem must be restored to OPERABLE status within 30 days. With the unit in this condition, the remaining OPERABLE RHRSW subsystems are adequate to perform the RHRSW heat removal function. However, the overall reliability is reduced because a single failure could result in reduced primary containment cooling capability. The 30 day Completion Time is based on the availability of equipment in excess of normal redundancy requirements and the low probability of an event occurring requiring RHRSW during this period.

The Required action is modified by a Note indicating that the applicable Conditions of LCO 3.4.7 be entered and Required Actions taken if the inoperable RHRSW subsystem results in inoperable RHR shutdown cooling. This, is an exception to LCO 3.0.6 and ensures the proper actions are taken for these components.

C.1 With two required RHRSW pumps inoperable the remaining RHRSW pumps are adequate to perform the RHRSW heat removal function. However, the overall reliability is reduced because a single failure of the OPERABLE RHRSW pumps could result in a loss of RHRSW function. The seven day Completion Time is based on the redundant RHRSW capabilities afforded by the OPERABLE RHRSW pumps and the low probability of an event occurring during this period.

D.1 With two RHRSW subsystems inoperable, the remaining OPERABLE RHRSW subsystems are adequate to perform the RHRSW heat removal function. However, the overall reliability is reduced because a single failure could result in reduced primary containment cooling capability. .The seven day Completion Time is based on the availability of equipment in excess of normal redundancy requirements and the low probability of an event occurring requiring RHRSW during this period.

The Required action is modified by a Note indicating that the applicable Conditions of LCO 3.4.7 be entered and Required Actions taken if the inoperable RHRSW subsystem results in inoperable RHR shutdown cooling. This is an exception to LCO 3.0.6 'and

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ensures the proper actions are taken for these components.

E.1 With three or more required RHRSW pumps inoperable, the RHRSW System is not capable of performing its intended function. The requisite number of pumps must be restored to OPERABLE status within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />. The 8 hour9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> Completion Time is based on the Completion Times provided for the RHR suppression pool cooling and spray functions.

F.1 With three or more required RHRSW subsystems inoperable, the RHRSW System is not capable of performing its intended function. The requisite number of subsystems must be restored to OPERABLE status within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />. The 8 hour9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> Completion Time is based on the Completion Times provided for the RHR suppression pool cooling and spray functions.

The Required action is modified by a Note indicating that the applicable Conditions of LCO 3.4.7 be entered and Required Actions taken if the inoperable RHRSW subsystem results in inoperable RHR shutdown cooling. This is an exception to LCO 3.0.6 and ensures the proper actions are taken for these components.

G.l and G.2 If the RHRSW subsystems cannot be restored to .

OPERABLE status within the associated Completion Times, the unit must be placed in a MODE in which the LCO does not apply. To achieve this status, the unit must be placed in at least MODE 3 within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> and in MODE 4 within 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />. The allowed Completion Times are reasonable, based on operating experience, to reach the required unit conditions from full power conditions in an orderly manner and without challenging unit systems.

II. REASON FOR THE PROPOSED CHANGE The normal configuration of the electrical supplies for the eight RHRSW pumps normally assigned to the RHR service water system (Refer to the s'stem description below) includes four 0 pumps (B1, B2, D1, and D2) each supplied from separate 4KV shutdown boards (3EC, C, 3ED, and D, respectively). The emergency power supply configuration includes four corresponding separate diesel generators (3C, C, 3D, and D). Two pairs of

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)ec 38 st aneoy cocrant Hx 3C seyeey (1 FCV tt sy) +c Reactor etcty Reactcr tncy Wall Wall TO TO EECW EECW TO T T TO EECW PT ey EECW 524 eT eT 544 563 :0-I HCV FCV FCV 67-88 67-89 67-49 67-48 TO RIVER TO RIVER A) Al At e) el et Ct Cl C) ot CCW PIT CCW PIT CCW PIT CCW PIT CCW PIT CCW PIT 1B 1C 2B 2C 3B 3C

RHRSW pumps (A1, A2, and C1, C2) share common 4KV shutdown boards (A and B) and diesel generators (A and B), respectively.

The RHRSW pump power supplies are shown on Figure 1. The current technical specification allows RHRSW pump alignments to be selected which could result in the loss of two RHRSW pumps assuming a single failure of diesel generator A or B. The loss of two RHRSW pumps, depending upon the number of operating units, could result in less than the number of operable RHRSW pumps required to support the RHR cooling function.

The proposed change ensures that the RHRSW system is operated in a manner which increases 0he power supply diversity of the system by requiring an additional pump be operable unless each pump selected to satisfy the operability requirements of Specification 3.5.C is supplied from a separate 4KV shutdown board. The practical effect of the proposed change is to require an additional operable pump whenever RHRSW pumps A1 and A2 or C1 and C2 are selected.

The addition of note (C) to the Table 3.5-1 is proposed as an aid to ensure that the selected operable RHRSW pumps are consistent with the 7-day LCO 3.5.B.3 requirements for RHR heat exchanger operability. In order to satisfy the TS 3.5.B.3 requirement for two operable RHR heat exchangers, the RHRSW pumps must always be associated with separate RHRSW headers.

The addition of note (D) to the Table 3.5-1 is proposed to allow the minimum RHRSW pump requirements to be reduced by one pump for each unit when in .the cold shutdown condition for more than 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. This change ensures a sufficient number of pumps are available to remove the reduced heat load resulting from core decay while increasing the plant's ability to perform outage activities without LCO entries.

SAFETY ANALYSIS S stem Descri tion The RHRSW System, a plant-shared system, is operated from each of the three unit control rooms to pump screened raw river water from the ultimate heat sink (Wheeler Reservoir) via the intake station to the RHR heat exchangers to remove reactor core heat and to the EECW (Emergency Equipment Cooling Water) system to serve safety-related loads following a DBE. The EECW system provides cooling water for t:he removal of heat from equipment such as the diesel generators, residual heat removal pump coolers, and room coolers for other emergency core cooling system equipment required for safe reactor shutdown following a design basis accident or transient. The RHRSW system operates remote-manually from the main control room to supply raw water to the RHR heat exchangers. The RHRSW System operates automatically to supply water to the EECW System. Cooling water is returned to the ultimate heat sink via a yard drainage system. The RHRSW system also provides standby core cooling by

supplying direct makeup to the reactor coolant system in the event of a failure of the safety-related redundant emergency core cooling systems.

The RHRSW system is a twelve-pump, four-header system with four pairs of pumps (A1, A2, Bl, B2, C1, C2, Dl, D2) normally assigned to the RHR System and four additional pumps (A3, B3, C3, D3) normally assigned to the EECW System. The RHRSW system is shown on Figure 2. Each of the pairs (assigned to the RHRSW System) feeds one independent RHR service water header which, in turn, feeds one RHR heat exchanger in each unit. The four pumps assigned to the EECW are also paired, one pair serving each of the two EECW headers. If necessary, one of each pair of pumps normally assigned to the RHRSW (Al, B1, C1, D1) can be manually realigned to the EECW. These pumps are termed "swing pumps."

The entire system is seismic Class I. On a per-unit and per-plant basis, the system provides several ways to supply water to the required heat loads. Each RHR service water and EECW header is physically, mechanically, and electrically independent of the alternate headers performing the same function.

Nuclear Safet Functions The RHRSW system provides a nuclear safety function of supporting RHR cooling by providing cooling water flow through the RHR system heat exchangers to cool the suppression pool water after a design basis event (DBE) and to cool suppression pool water sprayed into the primary containment for pressure control.

RHRSW pumps assigned to service the EECW system supply screened raw river water to the EECW distribution headers for cooling of safety-related equipment serviced by that system during a DBE.

TS 3.5.C ensures that sufficient RHRSW pumps are available to serve the RHR and EECW cooling functions for a single unit following a design basis accident and the safe shutdown of the other operating unit(s). As stated in FSAR Chapter 10.9 and Appendix F, section 7.16, two RHRSW pumps and two heat exchangers per unit are required to remove core decay heat under accident conditions.

Two additional RHRSW pumps are required to supply the EECW heat loads for all three units post-accident. Thus a total of four, six and eight RHRSW pumps are required to service the accident unit and non-accident unit heat loads for one, two, and three operating units, respectively.

Safet Anal sis of the Pro osed Chan e Compliance with the revised LCO requirements can be accomplished with the present system design. No physical plant changes are required which could introduce new failure modes.

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Figure 2 RHRSW/EECW POWER SUPPLY DEPENDENCIES DGA DGB DGC DGD DG 3EA DG 3EB DG 3EC DG 3ED 4KV Shutdown 4KV Shutdown 4KV Shutdown 4KV Shutdown 4KV Shutdown 4KV Shutdown 4KV Shutdown 4KV Shutdown Board A Board B Board C Board D Board 3EA Board 3EB Board 3EC Board 3ED RHRSW A2 C2 B2 D2 I

I I

I RHRSW/EECW Cl I B3 D3 A3 C3 (881 (DD1 I

EECW Only I

The additional pump operability requirements do not place an additional burden on the plant operations staff. The system is manually initiated following an event involving a loss of offsite power, and 0he requirement for an additional operable RHRSW pump increases the assured cooling capacity available to the operators.

The addition of one operable RHRSW pump to support the RHR cooling safety function does not reduce the total number of pumps required to support the EECW safety function. Therefore, the EECW safety function will not be degraded by the proposed change.

TVA's analysis demonstrates that the minimum RHRSW pump requirements can be reduced by one for each unit that has been in the cold shutdown condition for more than 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. The analysis conservatively models the performance of the RHR heat exchangers in shutdown cooling mode and demonstrates the heat removal capacity is greater than the decay heat. The analysis assumed that no heat is removed from the RCS by the RWCU system or any other systems except the RHR after initiation of shutdown cooling mode. The assumption conservatively maximizes the heat load on the RHR system. In addition, the analysis did not establish any operational requirements or limiting conditions for operation'. The analysis considered a non-accident unit shutdown with one RHR heat exchanger loop available for shutdown cooling, maximum river temperature of 95 degrees F. Rapid cooldown (100degree F/hour) was postulated to minimize the time to initiation of shutdown cooling mode of RHR.

The analysis utilized a decay heat curve for the power uprate level based on ANSI/ANS-5.1-1979 decay heat standard with two sigma of uncertainty added. The curve was based on the following fuel cycle assumption:

~ Fuel Type GE 9

~ Bundle Average Enrichment 3.8 percent

~ EOC Core Average Exposure 30,000 Mwd/STU

~ Core Average Time at Power 4.0 years The core average exposure was chosen to correspond with the average exposure for a twenty-four month, five percent uprate GE-13 equilibrium cycle.

The decay heat removal requirement for a unit in cold shutdown greater than twenty-four hours could be reduced from two heat exchangers (and associated RHRSW pumps) to one heat exchanger (and associated RHRSW pump) to sufficiently remove the decay heat. However, the proposed change ensures that two RHRSW pumps are required to be operable for any unit which has been in cold shutdown (or Mode four or five for ITS) for more than 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.

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4 The proposed changes are acceptable from a nuclear safety standpoint since they ensure the RHRSW system's ability to perform its safety functions with a single failure under the worst case pump alignment conditions, and do not place any additional burdens on the operators. TVA's proposed TS change assures the minimum number of RHRSW pumps for both the accident and non-accident unit(s) are available considering the worst case single failure.

IV. NO SIGNIFICANT HAZARDS CONSIDERATION DETERMINATION TVA has concluded that operation of Browns Ferry Nuclear Plant (BFN) Units 1, 2, and 3 in accordance with the proposed change to the technical specifications does not involve a significant hazards consideration. TVA's conclusion is based on its evaluation, in accordance with 10 CFR 50.91(a)(1), of the three standards set forth in 10 CFR 50.92(c).

A. The ro osed amendment does not involve a si nificant increase in the robabilit or conse ences of an accident reviousl evaluated.

The RHRSW system serves as a support system to ensure that reactor core and emergency equipment heat loads are rejected to the ultimate heat sink for mitigation of a design basis accident. There are no known event initiators associated with the RHRSW syst: em nor is the operation of the RHRSW system a precursor to any accident or malfunction analyzed in the SAR.

Since no plant modifications are involved with the proposed amendment, the RHRSW system's secondary containment penetrations which are designed to confine radioactive materi'als to the reactor building are not a'ffected by this amendment. Similarly, the function of the flow control valves downstream of the RHR heat exchangers which are used to limit radioactive releases to the ultimate heat sink following a postulated RHR heat exchanger leak are not impacted.

Therefore the proposed amendment does not involve a significant increase in the probability or consequences of an accident previously evaluated.

B. The ro osed amendment does not create the ossibilit of a new or different kind of accident from an accident reviousl evaluated.

The proposed amendment does not add any new equipment or require any existing equipment to be operated in a manner different from the present design. The proposed requirements for RHRSW pump operability are consistent with the SAR analysis for design basis accidents. No operation outside of the existing design basis is introduced by the proposed amendment.

Therefore, the proposed amendment does not create the possibility of a new or different kind of accident from any accident previously evaluated.

C. The ro osed amendment does not involve a si nificant reduction in a mar in of safet The proposed amendment increases the diversity of the power supplies associated with the performance of the RHR cooling safety function which improves conformance to the single failure criterion. In the event of a loss of offsite power followed by the loss of a diesel generator supplying two RHRSW pumps, a sufficient number of pumps will remain available to accomplish the RHR cooling safety function. The amendments are consistent with the BFN FSAR accident analysis. The amendments do not physically modify any equipment, setpoints, or equipment initiation sequences.

For these reasons, the proposed amendment does not involve a significant reduction in the margin of safety.

V. ENVIRONMENTAL IMPACT CONSIDERATION The proposed amendment, does not involve a significant hazards consideration, a significant change in the types of or significant increase in the amounts of any effluents that may be released offsite, or a significant increase in individual or cumulative occupational radiation exposure. Therefore, the proposed amendment meets the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c) (9) .

Therefore, pursuant to 10 CFR 51.22(b), an environmental assessment of the proposed amendment is not required.