ML16340C676
| ML16340C676 | |
| Person / Time | |
|---|---|
| Site: | Mcguire, Diablo Canyon, McGuire, 05000000 |
| Issue date: | 06/25/1982 |
| From: | Eisenhut D Office of Nuclear Reactor Regulation |
| To: | Ahearne J, Gilinsky V, Palladino N NRC COMMISSION (OCM) |
| References | |
| TASK-AS, TASK-BN-82-59 AS-BN-82-59, BN--82-59, BN-82-59, NUDOCS 8207120020 | |
| Download: ML16340C676 (10) | |
Text
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0 UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D. C. 20555 JUNE 2 5 1982 MEMORANDUM FOR:
Chairman Palladino Commissioner Gilinsky Comissioner Ahearne Commissi oner Roberts Comissioner Asselstine FROM:
SUB JECT'arrell G. Eisenhut, Director Division of Licensing Office of Nuclear Reactor Regulation INFORMATION ITEM -
RECENT INFORMATION WITH REGARD TO STEAM GENERATOR TUBE RUPTURE-DIABLO CANYON NUCLEAR POWER PLANT, UNITS 1
& 2 WILLIAMB.
McGUIRE NUCLEAR STATION, UNITS 1
& 2 (Board Notification No. 82-59)
In accordance with present NRC procedures regarding Board Notifications, the enclosed information is being provided for your information as constituting new information relevant and material to safety issues.
This information is generic and may have applicability to all dockets with pressurized water reactors.
During the review of the recent Ginna Steam generator tube rupture accident, it was determined that certain of the assumptions usually made in the staff's design basis accident calculations of off-site doses were non-conservative, at least for part of the accident.
Notwithstanding the potentially non-conservative
- factors, the overall accident at Ginna resulted in off-site consequences that were extremely small fractions of the staff's calculated values.
One reason for this was the low level of activity in the coolant at the time of the accident and the absence of an increase in radio-iodine concentration resulting from the accident (that is there was no pre-existing iodine spike nor was one caused by the rupture event).
- However, the emergency operating procedures followed by the operators resulted in overfilling of the steam generators which caused large carry-over of contaminated water in the steam released to the environment.
Delays in equalizing the primary and secondary pressures resulted in larger steam-water emissions from the secondary side than would have been experienced with a quicker reduction of the primary pressure to the set point pressure of the secondary relief valves.
Therefore, the staff has required reduced radioiodine limiting conditions for operation for the Ginna primary coolant activity.
These lower limits will remain in effect until the questions of overfilling and delays in equalizing pressure are resolved.
Furthermore, the staff is reviewing the overfilling and pressure equalization questions relative to other plants and may consider reduced limits for them also.
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The'ompission JUNE 3 5 Igg'ince the specific issues discussed above are not the only issues raised in the reviews of steam generator tube rupture accidents, the entire Ginna restart Safety Evaluation Report is attached for your information.
Until the staff, licensees, vendors and contractors have completed reviews of emergency operating procedures, plant designs, and coolant activity limits, no final staff position can be formulated.
However, it is the staff's judgment that this does not represent a compelling safety issue.
This judgment, is based not only on the experience of the Ginna tube rupture accident and the three others in U.S. plants. but also on the apparent implausibility of having all factors at their worst case'evels at the same time.
These factors include those determined by unrelated conditions in the plant (such as pre-existing high'radioiodine levels in the primary system), plant design, and emergency operating procedures.
He are continuing to pursue this issue and will keep you informed.
Enclosure:
R.
E. Ginna Safety Evaluation Report (NUREG-0916) cc:
SECY OPE OGC Original signed by Darrell G. Zisenhn5 Darrell G. Eisenhut, Director Division of Licensing Office of Nuclear Reactor Regulation DISTRIBUTION See Attached Listing OFFICfI SURNAMf)
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RCM 0240 OFFICIAL RE ORD COPY 0 USGFO: 198~29.824
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DISTRIBUTION OF BOARD NOTIFICATION Diablo Canyon Units 1&2 (Comm)
Docket Nos. 50-275/323 Ms. Elizabeth Apfelberg Andrew Baldwin, Esq.
Leonard Bickwit, Esq.
Mr. Richard E. Blankenburg Mr. Glenn 0. Bright Mr. Herbert H. Brown Mr. Samuel J. Chilk Philip A. Crane, Jr.,
Esq.
Mr. Frederick Eissler David S. Fleischaker, Esq.
Mrs.
Raye Fleming Arthur C. Gehr, Esq.
Mr. Byron S.
Georgiou Mr. Mark Gottlieb Mr. Richard B. Hubbard Dr.
W.
Reed Johnson Janice E. Kerr, Esq.
Dr. Jerry Kline Mr. John Marrs Thomas S. Moore, Esq.
Bruce Norton, Esq.
Joel R. 'Reynolds, Esq.
Mr. James
- 0. Schuyler Mr. Gordon Silver Paul C. Valentine, Esq.
Harry M. Willis John F. Wolf, Esq Dr. John H. Buck Atomic Safety and Licensing Board Panel Atomic Safety and Licensing Appeal Panel Docketing and Service Section Document Management Branch McGuire Units 1&2 (Comm)
Docket Nos.
50-369/370 Dr. John M. Barry Shelly Blume, Esq.
Diane B. Cohn, Esq.
Dr. Richard F. Cole Christine N. Kohl, Esq.
Robert M. Lazo, Esq.
Dr.
Emmeth A. Luebke J.
Michael McGarry, III, Esq.
William L. Porter, Esq.
Mr. Jesse L. Riley Alan S. Rosenthal, Esq.
Mr. David E. Smith
, ACRS MEMBERS Dr. Robert C. Axtmann Mr. Myer Bender Dr. Max W. Carbon Mr. Jesse C. Ebersole Mr. Harold Etherington Dr. William Kerr Dr. Harold W. Lewis Dr. J.
Carson Mark Mr. William M. Mathis Dr. Dade W. Moeller Dr. David Okrent Dr. Milton S. Plesset Mr. Jeremiah J.
Ray Dr. Paul G.
Shewmon Dr. Chester P. Siess Mr. David A. Ward
0
Board Notification 82-59 Steam Generator Tube Rupture Diablo Canyon 1
8 2
McGuire 1
& 2 Date:
JUNE
?
$ Qg Distribution Document Control (50-275/323; 50-369/370)
NRC PDR L PDR PRC System NS I C Branch Reading (LB83; LB')
F. Miraglia B. Buckley/H. Schierling J.
Lee E. Adensam R. Birkel M. Duncan R. Tedesco/J.
Kerrigan D. Eisenhut/R.
Purple M. Williams H. Denton/E.
Case PPAS R. Vollmer H. Thompson R. Mattson S. Hanauer
- Attorney, OELD I&E Regi,onal Administrator (II; V)
Resident Inspector W. Dircks (3}
A. Bennett (3)
E. Christenbury, OELD J. Scinto, OELD Board Service List
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Document fla ment Branch Document Control Desk Room 016, Phillips'Building JUttE 3
5 t982 tREtSRANDUH FOR:
Chairman Pall adino Commissioner Gilinsky Comiss ioner Ahearne Commissioner Roberts Coomissioner Asselstine FROI I:
SUBJECT:
Darrell G. Eisenhut, Director Division of Licensing Office of Nuclear Reactor Regulation INFORtOTION TTEtl -
RECENT INFORtOTION WITH REGARD TO STEAN GENERATOR TUBE RUPTURE-DIABLO CANYON NUCLEAR POWER PLANT, UNITS 1
8 2
WILLIAttB.
NcGUIRE NUCLEAR STATION, UNITS 1
8 2
(Board Notification No. 82-59)
In accordance with present NRC procedures regarding Board Notifications, the enclosed information is being provided for your information as constituting new information relevant and material to safety issues.
This information is generic and may have applicability to all dockets with pressurized water reactors.
During the review of the recent Ginna Steam generator tube rupture accident, it was determined that certain of the assumptions usually made in the staff's design basis accident calculations of off-site doses were non-conservative, at least for part of the accident.
Notwithstanding the potentially non-conservative
- factors, the overall accident at Ginna resulted in off-site consequences that were extremely small fractions of the staff's calculated values.
One reason for this was the low level of activity in the coolant at the time of the accident and the absence of an increase in radio-iodine concentration resulting from the accident (that is there was no pre-existing iodine spike nor was one caused by the rupture event).
- However, the emergency operating procedures followed by the operators resulted in overfilling of the steam generators which caused large carry-over of contaminated water in the steam released to the environment.
Delays in equalizing the primary and secondary pressures resulted in larger steam-water emissions from the secondary side than would have been experienced with a quicker reduction of the primary pressure to the set point pressure of the secondary relief valves. Therefore
, the staff has required reduced radioiodine limiting conditions for operation for the Ginna primary coolant activity.
These lower limits will remain in effect until the questions of overfilling and delays in equalizing pressure are resolved.
Furthermore, the staff is reviewing the overfilling and pressure equalization questions relative to other giants and may consider reduced limits for them also.
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OFFICIAL RECORD COPY 4 USGPO: 19~29.824
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