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o POWER AUTHORITY OF THE STATE OF NEW YORK JAMES A. FITzPATRICK NUCLEAR POWER Pt. A NT
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JOHN o. LEONARD. JR.
P.o. Box 41 Resident Manager g
j Lycoming. New York 130!
JAF 78-145 ass-342.sa4o Mr. Boyce H. Grier, Director United States Nuclear Regulatory Commission Region 1 631 Park Avenue King of Prussia, Pennsylvania 19406
Reference:
Docket #50-333 IE Bulletin No. 78-03
Dear Mr. Grier:
The following is our written response to IE Bulletin No. 78-03:
QUESTION 1.
Review the operations and maintenance procedures related to the offgas system to assure proper operation in accordance with all design parameters, include in this review measures you have taken or will take to prevent Inadvertent actions (such as are strikes) which might cause Ignition of the mixture of gases contained in the offgas piping.
ANSWER 1.
The offgas systern operating procedure was reviewed by members of the plant staff.
The procedure for recombiner shutdown was changed to leave dilution steam in service for a minimum of one hour after the offgas control switch is placed in the "off" position.
5 Existing plant instructions and procedures are reviewed and fellowed by members of the clant staff prior to and during maintenance of the offgas system.
Systems containing combustible gases are tested in accordance wlth Instructions contained in the Niagara Mohawk Accident Prevention Rules Book. The plant staff is also developing a welding program which, when completed, will include the necessary safety.re-quirements to prevent inadvertent actions such as arc strikes.
QUESTION 2.
Review the adequacy of the ventilation of spaces and areas through which of fgas system piping containing explosive mixture of gases pass.
The review should consider ventilation losses and off-normal
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offgas system operation, such as lack of dilution steam, lost loop-seals, blown rupture discs, bypassing recombiners, and leakage of
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offgas into isolated
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v Response to IE Bulletin No. 78-03 Page 2 of 3 March 25, 1978 %
ANSWER
-2.
Adequate ventilation of spaces and areas through which the offgas system piping containing explosive mixture of gases pass presently
, exists due to-redundant ventilation systems whose major components are physically separated.
A rupture of.any portion of the.offgas system while in operation will result-in high activity levels into the affected areas.
This increase in activity will be noted by the existing radiation monitors.
Due to the redundant components associated with the ventilation
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system, a total loss of the ventilation system;is extremely remote.
A loss or reduction of dilution steam to the offgas system will result in a trip of the recombiner due to low gas flow to the recombiner or loss of steam flow to the 1st or 2nd stage air ejector jets.
Loss of loop seals does not apply.
See answer to Question #4 for details.
Blown rupture disc 'does not apply as none are installed.
Bypassing the recombiner results in potentially explosive gas mix-ture flowing to the stack.,However, two 6000 SCFM dilution fans, located.in the stack, should preclude any explosive build-up.
Leakage of offgas into isolated portions of the system is extremely remote due to double valve isolation between the combustible mix-tures and isolable portions of the system.
QUESTION 3.
For those spaces and areas identified, describe what action you have taken or plan to take to assure that explosive mixtures cannot i
accummulate, that monitoring equipment will warn of such an accumu-lation, and that disposal' of such mixtures will be controlled without resulting in a damaging explosion.
ANSWER 3.
1 The rupture discs and loop seals have been removed thus minimizing the chance for explosive mixtures to accumulate in the spaces and areas through which the offgas system piping passes.
Previous plant experience has shown that the radiation monitors in the turbine and reactor building ventilation systems are adequate to detect leakage i
by noting an increase in the activity levels proportional to the leakage. The normal operation of the stack dilution fans will preclude the buildup of an explosive mixture.
QUESTION 4.
Loop seals are potential offgas leakage paths following a pressure transient in the offgas system piping.
Describe your design features to minimize and detect the loss of liquid from loop seals and describe operating procedures which assure prompt detection and reseal of the blown loop seals.-
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Response to IE Bulletin No.:78-03
.Page 3 of.3 March 25, 1978:
ANSWER-4.-
During the 1977 refueling outage all -loop seals were removed from the offgas system.. System drainage was collected by drip pots and returned to the main condenser through a closed ' piping system.
QUESTION
'5.
Review operating and emergency procedures to assure 'that your operating staff has adequate guidance to respond properly to offgas system explosions.
ANSWER.
'5.
The operations staff reviewed the emergency operating procedures
" Explosion in the Air Ejector Discharge Piping" (EOP-5) and
" Combustion' (fire) in the Steam Jet Air Ejector Af ter Condenser Piping" (EOP-5A) and note that the procedures reflect the plant operating experience with offgas.
Very truly yours, a
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Le'onar, J<r.
JDL/SLP:alh CC:
USNRC Director, Office of Inspection & Enforcement (3 copies)
USNRC Director, Office of Management Information & Program Control (3 copie Internal Power Authority Distribution f
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