ML19224A867
| ML19224A867 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 05/22/1979 |
| From: | Ross D Office of Nuclear Reactor Regulation |
| To: | Nechodom W SIEMENS POWER CORP. (FORMERLY SIEMENS NUCLEAR POWER |
| References | |
| NUDOCS 7906070062 | |
| Download: ML19224A867 (3) | |
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UNITED STATES
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NUCLEAR REGULATORY COMMISSION n
C WASHINGTON, D. C. 20555 oh MAY ? 21979 Mr. Warren Nechodom Manager, Licensing & Compliance Exxon Nuclear Company, Inc.
2101 Horn Rapids Road Richland, Washington 99352
Dear Mr. Nechodom:
SUBJECT:
ACRS RECOMENDATIONS RELATING TO TMI-2 ACCIDENT As you know, the Advisory Comittee on Reactor Safeguards (ACRS) has written three separate letters to the Commission relating to the TMI-2 accident. These letters were issued on April 7, April 18, and April 20, 1979. Each of these letters contains specific recommendations which must be addressed. The ACRS has discussed these recommendations with the staff and industry at recent ACRS subcomittee and full committee meetings. We anticipate that this dialogue will continue in the forth-coming ACRS st hcomittee meeting on TMI-2 (May 31-June 1).
For this reason, we are requesting that you provide the staff with a concise discussion and position on each of the ACRS recommendations relating to TMI-2. For your convenience, we have provided in the enclo-sure a list which contains each ACRS recommendation of which we are aware.
We request that you provide your response to each of these ACRS recommenda-tions to be received by the staff no later than May 29, 1979.
If you require any clarification of the matters discussed herein, please contact C. J. Heltemes, Jr.
Mr. Heltemes' phone number is (301) 492-7745.
Sincerely, 1
/
. R as,ieputy Director Division of Project Management Office of Nuclear Reactor Regulation
Enclosure:
As stated
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l' ENCLOSURE ACRS RECOMMENDATIONS _
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Letter, M. Carbon to Chairman Hendrie, dated April 7,1979 A.
l Recommendation 1 - Perfom further analyses of small break transients and accidents.
l Recommendation 2 - Provide operator additional infomation and means to follow the course of an accident; as a minimum, consider expeditiously:
j (a) unambiguous RV level indication (b) remotely controlled vent for RCS high points i
I Recommendation 3 - Item 4b of Bulletin 79-05A considered unduly pre-scriptive in view of uncertainties in predicting course of anomalous small break transients / accidents.
B.
Letter, R. Fraley to Corr.issioners, dated April 18, 1979 l5 Recommendation 1 - Natural Circulation-related Items Detailed analyses of natural circulatica mode, I
a.
supported as required by experiment, by licensees and NSSS vendors.
I b.
Develop procedures for initiating natural circulation.
Provide operator means for assurance that natural c.
circulation has been established, e.g., by install-ation of instructions to indicate flow at low velocities.
1 d.
Expeditiously survey operating PWR's to determine 1
whether suitable arrangements of PZR heaters and reliable on-site power distribution can be provided to assure this vital aspect of natural circulation capability.
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Operator should be adequately informed concerning RCS e.
J conditions which affect natural circulation capa-bility, e.g.,
(1) indication that RCS is approaching saturation condition by suitable display to operator of T &T and PZR pressure in conjunction with h
sfeamtables (2) use of flow exit temperature indicator by fuel i
i assembly thermoccuples, where available.
J 169 059 t,
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Enclosure - page 2 I
l ACRS Recomendations Recomendation 2 - Thermocouples used to measure 'uel assembly exit temperatures to determine core performance should be used, where currently available, to guide operator j
concerning core status (full range capability).
Recommendation 3 - Operating reactors should be given priority regarding definition and implementation of. instrumentation to diagnose and follow the course of a serious accident.
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including (a) improved sampling procedures under accident t
conditions (b) improved techniques to provide guidance to
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offsite authorities.
F Recomendation 4 - Reiterates previous recommendations that high priority l
be given to "research to improve reactor safety" n
6 (a) research on behavior of LWR's during anomalous transients L
(b) NRC to develop capability to simulate wide rang-l of postulated transients and accident conditions.
Recomendation 5 - Consideration should be given to additional monitoring of ESF equipment status, and to supporting services, to help j;-
assure availability at all times.
C.
Letter, M. Carbon to Acting Chairman Gilinsky dated April 20, 1979 Recomendation 1 - Initiate immediately a survey of operating procedures
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for achieving natural circulation, including:
(a) event involving loss of offsite power (b) consideration of role of PZR heaters.
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j' 169 060
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