Protecting People and the EnvironmentUNITED STATES NUCLEAR REGULATORY COMMISSION
GL80091
UNITED STATES
NUCLEAR REGULATORY COMMISSION
WASHINGTON, D.C. 20555
November 4, 1980
TO ALL HOLDERS OF CONSTRUCTION PERMITS AND OPERATING LICENSES FOR BOILING
WATER REACTORS
The use of the ODYN code to calculate pressurization transients has been
reviewed extensively by the staff and discussed with the General Electric
Company. We have found that ODYN provides acceptable best estimate
calculation predictions of the core responses to pressurization transients.
A safety evaluation describing the basis for this conclusion will be mailed
to you in the very near future. This letter is for the purpose of advising
you as early as possible of our requirements for implementation of ODYN for
licensing basis calculations performed by the General Electric Company.
These requirements are applicable to license applications and all proposed
license amendments, including core reloads for which analyses are provided
by General Electric.
Transient analyses performed by General Electric supporting reload
submittals received prior to February 1, 1981, will be reviewed taking into
account the results of recent generic transient analyses with ODYN.
Appropriate CPR penalties will be applied on a case by case basis. Transient
analyses performed by General Electric supporting reload submittals received
after February 1, 1981, must contain appropriate ODYN analyses in place of
those previously performed with REDY for the limiting transients. Generally,
these will include generator load rejection/turbine trip without bypass
(whichever is limiting), feedwater controller failure - maximum demand, and
main steamline isolation valve closure (to satisfy ASME code pressure
requirements). After January 1982, all operating BWRs with General Electric
analyses must have the limiting transients recalculated with the ODYN code,
even if no reload submittal has been received. The transients analyzed with
ODYN must be justified to be the limiting transients.
General Electric has provided an ODYN analysis for the two most limiting
events for BWR 3 and BWR 4 plant types and has committed to provide analyses
for a BWR 2 plant type by November 1, 1980. Any
.
- 2 - November 4, 1980
penalties resulting from our review of the analyses for any plant type will
be applied to all plants of that type until plant-specific calculations have
been performed with ODYN for the two most limiting transients.
Sincerely,
Darrell G. Eisenhut, Director
Division of Licensing
cc: Service List
