ML16342B361
| ML16342B361 | |
| Person / Time | |
|---|---|
| Site: | Diablo Canyon  |
| Issue date: | 07/23/1987 |
| From: | Knighton G Office of Nuclear Reactor Regulation |
| To: | Kirsch D NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| References | |
| TAC-63468, NUDOCS 8707280220 | |
| Download: ML16342B361 (6) | |
Text
p 3 JUQ 1987 FROM:
George W. Knighton, Director Project Directorate V
Division of Reactor Projects - III, IV, V and Special Projects, NRR MEMORANDUM FOR:
Dennis F. Kirsch, Director Division of Reactor Safety and Projects Region V
DISTRIBUTION
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NRC 8
L PDRs CTrammell JLee PDV Memo
SUBJECT:
RESPONSE
TO TECHNICAL ASSISTANCE RE(UEST - DIABLO CANYON SEISMIC EFFECTS ON PARTIALLY LOADED CORE (TAC NO. 63468)
By memorandum dated October 6,
- 1986, Region V requested NRR's technical assistance to look at seismic effects of a partially loaded reactor core.
A partially loaded core would have vacancies next to fuel assemblies that would allow fuel assemblies to tilt or tip off vertical under seismic motion.
Since fuel assemblies are held in the vertical position by their bottom nozzle, it would not take much ground motion to cause fuel assemblies to tip or fall and
" of course the question is not unique to Diablo Canyon.
Whereas we can see that a number of tilted or fallen fuel assemblies would create some handling difficulties, there have been about 30 fuel handling mis-haps in the nuclear industry over the years, including drops more severe than would result from tilting or falling, and none have resulted in any detectable release of radioactivity.
This operating experience supports the conclusion that the standard fuel handling accident described in the Diablo Canyon Updated FSAR (Section 15.5.22, page 15.5-38) is more severe than the consequences to be expected from tilted or fallen fuel assemblies as a result of a seismic event.
As for any critically concerns, the most reactive configuration of the fuel assemblies exists when they are standing on the lower core plate, adjacent to each other, with shutdown margin controlled by high boron concentration.
Any other configuration such as might result from tilted or fallen fuel assemblies would be less reactive and therefore have a greater shutdown margin.
This completes NRR action on your October 6, 1986 technical assistance request.
cc:
M. Mendonca P. Narbut J. Burdoin J. Ridgely C. Trammell George W. Knighto'n, Director Project Directorate V
Division of Reactor Projects - III IV, V, and Special Projects, NRR t
- See previous concurrence
- DRSP/PDV
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MEMORANDUM FOR:
FROM:
Dennis F. Kirsch, Director Division of Reactor Safety and Projects Region V
George W. Knighton, Director Project Directorate V
Division of Reactor Projects - III; IV, V and Special Projects, NRR DISTRIBUTION
~F NRC 5 L PDRs CTrammell JLee PDV Memo
SUBJECT:
RESPONSE
TO TECHNICAL ASSISTANCE REQUEST - DIABLO CANYON SEISMIC EFFECTS ON PARTIALLY LOADED CORE (TAC NO. 63468)
By memorandum dated October 6,
- 1986, Region V requested NRR's technical assistance to look at seismic effects of a par tially loaded reactor core.
A partially loaded core would have vacancies next to fuel assemblies that would allow fuel assemblies to tilt or tip off vertical under seismic motion.
Since fuel assemblies are held in the vertical position by their bottom nozzle, it would not take much ground motion to cause fuel assemblies to tip or fall and of course the question is not unique to Diablo Canyon.
Whereas we can see that a number of tilted or fallen fuel assemblies would create some handling difficulties, there have been about 30 fuel handling mis-haps in the nuclear industry over the years, including drops more severe than would result from tilting or falling, and none have resulted in any detectable release of radioactivity.
This operating experience supports the conclusion that the standard fuel handling accident described in the Diablo Canyon Updated FSAR (Section 15.5.22, page 15.5-38) is more severe than the consequences to be expected from tilted or fallen fuel assemblies as a result of a seismic event.
This completes NRR action on your October 6, 1986 technical assistance request.
cc:
H. Mendonca P. Narbut J. Burdoin J. Ridgely C. Trammell George W. Knighton, Director Project Directorate V
Division of Reactor Projects - III IV, V, and Special Projects, NRR PDV S
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/87
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UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D. C. 20555 July 17, 1987 50-275/323 Diablo Canyon MEMORANDUM FOR'ROM:
SUBJECT:
The Division of determined that Chief, Document Management
- Branch, TIDC Director, Division of Rules and Records, ADM REVIEW OF UTILITY EMERGENCY PLAN DOCUMENTATION Rules and Records has reviewed the attached document and has it may now be made publicly available.
gy Donnie H. Grimsley, Director Division of Rules and Records Office of Administration t
Attachment:
As stated
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