ML20133B867
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NUCLEAR REGULATORY COMMISSION o
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- l. 25 1984
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SUBJECT:
GRAND GULF DIESEL $0RDER.,.
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A ' technical basis' and co'n' tent. portion of an order might be financed along the following roughly sketched lines:
Station blackout, an accident sequence entailing a loss of offsite power and a failure of onsite electrical power supplies, together with failures of non-AC powered core cooling system; is thought to be among the moredmportant contributors.to offsite nuclear risk at LWR plants.
At Grand'. Gulf}thsidliability(of the onsite power supply has been called into questforijby; evidence of design problems with Transamerica Delaval Inc..diesellgenerators. MP&L has brought in gas turbine
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generators"as Aconipensatory' measure.
The staff 1
h complete tear down and inspection of the TDI EDG's withyeplacement%ariytparts found to be flawed [ details to be supplie'd] to bsMe'c'e~siaiy in order for the TDI diesels to be considered fully operable ~ forcthe purposes of full power generation.
In addition, th'e'lodihal : structure of Grand Gulf's vulnerability to station blackout - induced ac'idents should be. reflected in tech specs for full c
power operation.;
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For interruption'.of.offsite. power lasting for a few hours, any one of the following systems'can w.ygysustain core 2 cooling and avert a radiological accident:
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HPCS f
3.
TDI Diesel Generator "A" and its associated load groups 4.
TDI Diesel Generator "B" and its associated load groups
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5.
Thegasturbines' rigged (withinxminutes)toenergizeeither essential,switchgear bus or Redundancy in offs'ite power souices'al'so helps to reduce the likelihood of radiological accidents. associated with loss of offsite power.
t 8507200389 850515 PDR FDIA
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[ April 25, 1984 To reflect these considerations in LCO's, we order the following technical specifications in place of current specs on the AC power supplies:
Operability Condition List 1.
RCIC 2.
HPCS and auxiliaries needed for the sustained function of HPCS 3.
EDG 4.
EDG 5.
Gas turbines and associated equipment and procedures such that either essential switchgear bus or can be provided with power sufficient to bear one train of loads including transient decay heat removal.
6.
Redundancy of operable offsite power supplies-Situation LCO
- 1) Two of the above list operation at power levels above 5%
not met may be sustained for no more than 72 hr.
- 2) Three of the above list-comence controlled shutdown not met immediately (12 hr. to hot shutdown, 24 hr. to cold shutdown)
For the TDI diesels to be considered operable, the one with the most service hours must be stripped & inspected.
It may be considered operable following replacement of [ suspect] parts and a requalification operability test [to be defined).
In the event that this teardown reveals no flawed components, the TDI diesel with the lesser service hours may be considered operable for full power. Otherwise, it, too, must be stripped, inspected and repaired as above.
g Frank Rowsome cc:
C. Berlinger L. Rubenstein A. Thadant A. Busiik
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