ML20207P991

Proposed Tech Specs,Requiring Both evaporator-economizer Superheater Sections & Both Reheater Sections to Be Available During Operation at Power as Min Number of HXs

ML20207P991
Person / Time
Site:	Fort Saint Vrain
Issue date:	01/15/1987
From:	PUBLIC SERVICE CO. OF COLORADO
To:
Shared Package
ML20207P988	List: ML20207P987 ML20207P989 ML20207P991 ML20207P993
References
TAC-63576, NUDOCS 8701210011
Download: ML20207P991 (7)

Text

.

Fort St. Vrain

. Technical Specificadons Amendment #

Page 4.3-1 4.3 SECONDARY REACTOR COOLANT SYSTEM - LIMITING CONDITIONS FOR OPERATION Applicability Appites to the minimum configuration and characteristics of the secondary (steam) reactor coolant system, including the steam generators and turbine plant.

Objective i

To ensure the capability of this system to cool the core and prevent a safety limit from being exceeded by defining the minimum operable equipment and characteristics of the secondary reactor coolant system.

Soecification LCO 4.3.1 - Steam Generators. Limiting Conditions for Operation The reactor shall not be operated at power unless both the reheater section and the economizer-evaporator-superheater (EES)

I section of both steam generators are operable for the removal of decay heat.

l The EES sections shall be capable of receiving water from both j

the emergency condensate header and the emergency feedwater I

header.

The reheater sections shall be capable of receiving water from the emergency condensate header.

Basis for LCO 4.3.1 The steam generators provide the means for shutdown heat removal i

from the primary coolant.

The EES section of one steam l

genera tor is capable of fulfilling this purpose for Safe l

Shutdown Cooling (refer to FSAR Sections 10.3.9 and 14.4.2.2),

l as well as providing cooling for other abnormal events. The I

reheater sections are capable of providing cooling for other l

abnormal events, but are not relied upon to provide Safe l

Shutdown Cooling. The reheater section can be supplied water l

from the emergency condensate header and the EES section can be l

supplied water from either the emergency condensate header or l

the emergency feedwater header.

8701210011 870115 PDR ADOCK 05000267 p

PDR-

N Fort St. Vrain Technical Specifications

/bnendment #

Page 5.3-19 of one' (or more) safety valve (s) of similar type and operating conditions several times during the interval will provide additional confidence in safety valve

' reliability and adequate overpressure protection.

Specification SR 5.3.10 - Secondary Coolant System Instrumentation Surveillance 4

The secondary coolant reheat steam instrumentation used a) for control and indication of emergency condensate l

flow to the reheaters and reheater backpressure, b) to automatically open the reheater discharge bypass on -

high pressure, and c) to monitor reheater discharge bypass temperature, and 4

reheater inlet temperature, shall be functionally tested and calibrated annually, or at the next scheduled plant shutdown if such surveillance was not performed during the previous year.

SR 5.3.10 shall be implemented per-ISI Criterion B.

4 s

r b

a r

n

<n-

,---.-,r--

Fort St.. Vrain

_ Technical Sp:cifications Amendment #

f

.Page 5.3-20.

Basis for Specification SR 5.3.10 The frequency. Spectfled for surveillance of the above instrumentation will assure that they perform their expected automatic actions, and that the operator will be

~

l provided with accurate information which he can use to

. avoid abnormal equipment operation.

Specification 5.3.11 - Steam Generator Bimetallic Welds Surveillance

-The accessible portions of steam generator bimetallic welds shall be volumetrically examined for indications of subsurface defects as follows:

a) The main steam ring header collector to main steam piping weld for one steam generator module in each loop at five calendar year intervals.

b) The main steam ring header collector to collector drain piping weld for one steam generator module in each loop at five calendar year intervals, c) The same two stehm generator modules initially selected shall be re-examined at e'ach interval, d) The bimetallic welds described in a) and b) shall also be inspected for two other steam generator modules in each loop during the initial examination.

b i

4 ATTACHMENT 3 SIGNIFICANT HAZARDS CONSIDERATION

q ATTACHMENT 3 TO P-87002 SIGNIFICANT HAZARDS CONSIDERATIONS (10 CFR 50.92)

I.

EVALUATION PSC has proposed changes to LC0 4.3.1 to require both evaporator-economizer-superheater (EES) sections and both reheater sections be available during operation at power as the minimum number of operable heat exchangers.

The FSV Technical Specifications currently require both the reheater section and the EES section of one steam generator and either the reheater section or the EES section of the other steam generator be operable for tTie removal of decay heat.

Each EES section provides adequate capability for Safe Shutdown Cooling (as described in FSAR Sections 10.3.9 and 14.4.2.2) from power levels up to 87.5 percent.

However, a reheater section does not provide adequate capability for Safe Shutdown Cooling at power levels above 39 percent, and therefore PSC will no longer rely on reheaters for Safe Shutdown Cooling from any power level. The Basis for LC0 4.3.1 will be revised to state that the reheater sections are capable of providing cooling for other abnormal events, but are not relied upon to provide Safe Shutdown Cooling.

A second proposed change to LC0 4.3.1 is that the EES sections shall be capable of receiving water from both the Emergency Condensate Header and the Emergency Feedwater IIeader instead of the former minimum aTT6wable of only one of these emergency headers.

Although the EES sections can be supplied water from both the Emergency Condensate Header and the Emergency Feedwater Header, only one of the two headers is needed to supply the required cooling water for Safe Shutdown Cooling. The reheaters can-be supplied with water from the Emergency Condensate Header, but not from the Emergency Feedwater Header.

Recent analyses of Safe Shutdown Cooling with an EES as summarized in the safety analysis report * (Attachment 4) have shown that maximum fuel temperatures remain well below a level where significant fuel damage could occur, the primary coolant pressure boundary remains intact, and the PCRV safety valves remain seated.

Thus the consequences of the. Safe Shutdown Cooling accident previously evaluated will not be increased by the LC0 4.3.1 Basis change that omits reliance on the reheaters for Safe Chetdown Cooling.

Safety Analysis Report for Technical Specification LC0 4.3.1 Change Permitting Safe Shutdown Cooling With Evaporator-Economizer-Superheater, Fort St.

Vrain Nuclear Generating Station, Docket 50-267, Public Service Company of Colorado.

(Attachment 4 to PSC Letter P-87002).

to P-87002 Page 2 The EES sections can be supplied by water from either the Emergency Condensate Header or the Emergency Feedwater Header, while the reheater sections cannot be supplied by the Emergency Feedwater Header. This is a safety advantage in favor of relying upon the EES.

This advantage is reinforced by the proposed LC0 change requiring that both EES sections be capable of receiving water from both emergency headers during power operation, instead of the former minimum allowable of one header. The new requirement for two EES

' sections (plus two reheater sections) to be operable during power operation is superior to the previously permitted minimum combinations of heat exchangers that could have allowed only one EES (and two reheaters) to be operable during power operation.

For these

reasons, it is considered that this proposed change does not involve an in<

ase in the probability or consequences of an accident previt

?y evaluated (i.e.,

the probability of a Permanent Loss of Forced irculation Accident is not significantly increased, and may actually be decreased).

The revision to LC0 4.3.1 will not create a new or different kind of accident. The accident descriptions for Safe Shutdown Cooling with a firepump and other Safe Shutdown List equipment in the FSAR (Sections 10.3.9, 14.4.2.1, and 14.4.2.2) will remain essent.lly as written.

Minor editorial changes will be made to incorporate the most recent analyses of temperature transients (Reference 5 of Attachment 4*).

Only the~ single failure discussion of Section 10.3.10 will be slightly altered by the omission of the mention of reheaters for Safe Shutdown Cooling.

However, sufficient redundancy remains in Safe Shutdown Cooling heat exchangers (i.e., both EES sections) such that the option of Safe Shutdown Cooling with a reheater may be removed from the Basis for LC0 4.3.1 and Fort St. Vrain will continue to meet the NRC's single failure requirements, as is discussed in the safety analysis report * (Attachment 4).

FSV continues to meet the General Design Criteria commitments in Appendix C of the FSAR without relying on the reheaters for Safe Shutdown Cooling.

The revision of LC0 4.3.1 to require the EES sections and the reheater sections of both steam generators to be operable (instead of both the reheater section and the EES section of one steam generator and either the reheater section or the EES section of the other steam generator) assures that both EE sec.tions, rather than a minimum of only one EES, are operable. Requiring use of an EES section as the heat exchanger for Safe Shutdown Cooling, rather than a reheater, provides a much larger heat transfer capability, thereby assuring' a greater m3rgin of safety. The revision of LC0 4.3.1 requiring both EES sections to be capable of receiving water from both the Emergency Feedwater Header and the Emergency Condensate Header dces not decrease the margin of safety over the former minimum requirement of capability of receiving water from only one of these headers. The reheaters can only be supplied by the Emergency Condensate Header.

p

q..

o

- Attachment.3 to P-87002

'Page 3

.II.' CONCLUSION iBased -on the above evaluation, it is concluded that operation of Fort St. Vrain in accordance with the proposed LCO. changes will not (1). involve ~ a significant increase in'the

' consequences of an accident previously evaluated,-(probability or

2) create the possibility. of a new oor different kind of accident from any accident previously evaluated, or.'(3) involve a significant reduction in any margin of safety. Therefore, this change will not create an undue risk to the. health and safety of the public

'nor does it involve'any significant hazards consideration.

J I

A F

.-~

~.....

-. - -