ML19309D564
| ML19309D564 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 10/25/1979 |
| From: | Harold Denton Office of Nuclear Reactor Regulation |
| To: | Gilinsky V, Hendrie J, Kennedy R NRC COMMISSION (OCM) |
| Shared Package | |
| ML19309D561 | List: |
| References | |
| ACRS-1684, NUDOCS 8004100519 | |
| Download: ML19309D564 (2) | |
Text
g w,
- A ~
.~
c W 76.
/ "%q 4
UNITED STATES j
NUCLEAR REGULATORY COMMISSION
[','
wAsusmorom. o. c. 2 cess
/
v W
OCT 2 51973 ME50RDANUM FOR:
Chairman Hendrie Comissioner Gilinsky i
(
Comissioner Kennedy Comissioner Bradford Comissioner Ahearne THRU:
' Executive Director for Operations s
FROM:
Harold R. Denton, Director, NRR
SUBJECT:
INTERIM REPORT ON SENSITIVITY STUDIES OF THE B&W REACTOR DESIGN The sensitivity of B&W reactor designs to transients and accidents has been discussed previously with the Comission. Some preliminary findings and con-clusions were presented in an April 25, 1979 NRR report (Ref. 1) which served in part as the basis for confirmatory shutdown orders for operating plants
'with B&W reactors (Ref. 2-7). A more complete exposition on this subject is in the staff report NUREG-0560 (Ref. 8).
The NRR staff has reviewed the responses to the short-term portions of the confirmatory orders and is in the process of reviewing compliance with the long-term order provisions. Scme of the design changes already accoaplished have reduced the sensitivity aspect of the B&W design, in particular the ad,dition of anticipatory trips from abnormal conditions in either. the feed-water or steam flow paths of the steam generator.
However, our review of the sensitivity of the B&W design has continued, and we are not yet fully satisfied on this question. Recently we and the Office of l
Research have initiated a detailed study of the risk, on a relative basis, of a B&W design. We have selected the Crystal River plant for this purpose.
Further details are provided in Ref. 9 (which is also attached here as EnclosureA).
l As the reliability study may take 3-6 months, and conversion to licensing strategy would take further time, we are also considering whether it is necessary to halt pgg of the construction of B&W pisnts, pending the outcome of the reliaot nty assessment. As a preliminary consideration, we have identified those systems and components that may be impacted by possible design changes as a result of this study. A survey was made of the status 8004100 %
Multiple Addressees -
of these systems and components for B&W plants under construction. Enclosure B indicates that in general, the design, procurement and fabrication of these it'ms are essentially complete. The construction (or installation) status of e
these items varies from zero to 100 percent complete, with an estimated over-all average of about 50 percent complete, except for the North Anna units, which are about 10 percent complete.
I have today notified holders of cps with B&W designs of this ongoing study and under the authority of 10 CFR 50.54(f), requested them to provide infor-mation to allow us to determine whether it is necessary to halt all or portions of the construction of B&W plants. Enclosure C is a copy of my letter to one of the utilities.
I intend to direct the utilities to respond by December 3,1979 and expect our evaluation to be completed by December 15, 1979.
Th'e long-term program for B&W operating reactors already addresses several of the concerns of the Crystal River study. As the results from the Crystal River study becomes available, they will be applied to operating reactors as appropriate.
AYb Harold R. Denton, Director Office of Nuclear Reactor Regulation
Enclosures:
As Stated cc:
SECY OGC OPE e
m.*
e W M 4
-