United States Nuclear Regulatory Commission - Protecting People and the Environment

BWR Feedwater Nozzle and Control Rod Drive Return Line Nozzle Cracking (NUREG-0619) (Generic Letter 81-11)



                                UNITED STATES
                        NUCLEAR REGULATORY COMMISSION
                           WASHINGTON, D.C. 20555

                              February 29, 1981

ALL POWER REACTOR LICENSEES AND LICENSE APPLICANTS (Generic Letter 81-11) 

By letter dated November 13, 1980 you were forwarded a copy of NUREG-0619, 
"BWR Feedwater Nozzle and Control Rod Driven Return Line Nozzle Cracking" 
(November 1980). An error has been found in footnote 2 to Table 2 on page 18
of NUREG-0619. Because of the deltion of leak-testing requirments, footnote 
2 should now read :  "To be performed even if UT results are satisfactory." 
Please make the change in your copy of the NUREG. 

Also, comments received from GE and others since the publication of NUREG-
0619 note the difficulty in meeting the requiremtns for a low flow 
controller as described in Section 3.4.4.3 of the GE report NEDE-21821-A 
(BWR Feedwater Nozzle/Sparger Final Report, February 1980). They note that 
an exisiting controller may not meet the six charactieristics, yet the 
feedwater system may in fact meet the criterion of the crack growth analysis 
from which the characteristics were derived (assurance of crack growth to no 
greater than one inch in forty years). 

They also note that strict adherence to the defined characteristics culd 
obviate the beneficial aspects of another recommended change, reactor water 
cleanup (RWCU) system rerouting to all feedwater lines, by increasing 
reactor vessel water level to the extent that discharging of the relatively 
hot RWCU water is necessary. 

We concur in the assessment and will accept continued use of an existinf 
controller (or a controller modified to meet the basis stated above but not 
possessing all six characterisitics of NEDE-21821-A) based upon a plant-
specific fracture mechanics analysis or application of the analysis already 
exisitng in NEDE-21821-A Section 4. In order to be considered acceptable, 
this analysis must show that stresses from conservative controller 
temperature and flow profiles, when added to those resulting from the other 
crack growth phenomena, such as startup and shutdown cycles, do not result 
in the growth of a crack to greater than one inch during the forty year life
of the plant. The analysis should be submitted as part of the reports 
required by NUREG-0619. 
.

                                  - 2 -                  February 29, 1981 

Licensees or applicants not desiring to perform such ananalysis must meet 
the state requirments of Section 4.2 of NUREG-0619, i.e., the installation 
of a low flow controller having the six charateritstics stated in 
NEDE-21821-A. 

In answer to a question that has been raised, NUREG-0619 was forwarded to 
PWR licensees and applicants for their information only, in consideration of 
the fact that the PWR steam generator feedwater line cracking has been 
attributed to the same phenomenon of thermal fatigue as existed in the BWR 
feedwater nozzles. No response from PWR licensees and applicants is 
required. 

                                   Sincerely, 


                                   Darrell G. Eisenhut, Director 
                                   Division of Licensing 
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