ML18051B246
| ML18051B246 | |
| Person / Time | |
|---|---|
| Site: | Palisades  |
| Issue date: | 01/31/1985 |
| From: | Johnson B CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| To: | Office of Nuclear Reactor Regulation |
| References | |
| TASK-15-02, TASK-15-2, TASK-RR NUDOCS 8502050162 | |
| Download: ML18051B246 (2) | |
Text
consumers Power company General Offices: 1945 West Parnell Road, Jackson, Ml 49201 *:1517) 1aa-osso January 31, 1985
- Director, Nuclear Reactor Regulation US Nuclear Regulatory Commission Washington, DC 20555 DOCKET 50-255 - LICENSE DPR PALISADES PLANT -
SEP TOPIC XV-2 "SPECTRUM OF STEAM PIPING FAILURES INSIDE AND OUTSIDE CONTAINMENT (PWR)"
Consumers Power Company letter dated August 21, 1984 and entitled SEP Topic XV-2 "Spectrum of Steam Piping.Failures Inside and Outside Containmerit (PWR) - Commitments for Evaluation and Modification," committed to submit by February 1, 1985 a final Probabilistic Risk Assessment (PRA) and Cost-Benefit Analysis on the actual safety significance of the two-steam-generator-blowdown event as well as the most cost-effective modification (if modification is.
required) to reduce the likelihood of this event.
Recently, Consumers Power Company has discovered an error in the software that is being used to perform sequence quantification.
Sequence quantification has progressed to the point that derivation of cutsets and failure probabilities for support systems to major system headings in the main steam line break event tree is complete.
However in quantifying the major system headings, combinations of failures which should result in system failure are not, in some cases, being produced as part of minimal cutsets.
The code authors have been contacted for assistance in correcting the error, and Consumers Power Company is attempting to expedite a quick resolution.
In addition, considera-tion is being given to using other codes which may be available for completing the sequence quantification.
This code error plus the extended outage at Palisades which required a large amount of time from the people also involved in PRA has resulted in Consumers Power Company not b~ing able to meet the February 1, 1985 commitment.
In performing this PRA evaluation, we are gaining insights to how the Palisades Plant responds to the main steam line break event.
But before proposing any alternatives to this Main Steam Isolation Valve (MSIV) backfit, we feel it is necessary to have the sequence quantification.
For this reason Consumers Power Company will need an additional extension to the time required to produce our evaluation.
OC0185-0118A-NL04
Director, Nuclear Reactor Regulation Palisades Plant SEP Topic XV-2 Ja,nu~ry 31, 1985 2
It should be noted that an extension will not result in any additional risk to the public due to operation of Palisades without an identified resolution of the main steam line break issue.
Assuming a decision is made to install backup MSIVs, they will be installed during the refueling following the next cycle.
Eighteen months are required for procurement, which would have to begin by September 1, 1985 in order to meet the early start date of the refueling outage.
An update of our progress on this issue will be submitted by February 28, 1985.
Brian D Johnson Staff Licensing Engineer CC Administrator, Region III, USNRC NRC Resident Inspector - Palisades OC0185-0118A-NL04