ML19350E593
| ML19350E593 | |
| Person / Time | |
|---|---|
| Site: | Humboldt Bay |
| Issue date: | 04/17/1981 |
| From: | Engelken R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| To: | AFFILIATION NOT ASSIGNED |
| Shared Package | |
| ML19350E586 | List: |
| References | |
| NUDOCS 8106230316 | |
| Download: ML19350E593 (1) | |
Text
...
.i UNITED STATES 8%
i
. NUCLEAR REGULATORY COMMISSION E,
E REGION V
- o 1990 N. CALIFORNIA BOULEVARD 4
SulTE 202, WALNUT CREEK PL AZA 44,,5 WALNUT CREEK, CALIFORNIA 94596 (m)
April 17, 1981
'Tentlemen:
The enclosed Information Notice provides early notification of an event that may have safety significance. Accordingly, you should review the Information Notice for possible app'.icability to your facility.
No response is requested at this time; however, contingent on the results of further staff evaluttion, a bulletin or a circular requesting or recomending specific licensee. actions may be issued.
If you have any questions regarding this notice, please contact the Director of the appropriate NRC Regicnal Office.
Sincerely, wp R. H. Engalken Director
Enclosure:
IE Information Notice No. 81-14 s
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I 8106 23 03l(
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SSINS No.: 6835 Accession No.:
8011040292 IN 81-14 UNITED STATES NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT WASHINGTON, D.C.
20555 Apr G 17, 1981 IE Information Notice No. 81-14:
P0TENTIAL OVERSTRESS OF SHAFTS ON FISHER SERIES 9200 BUTTERFLY VALVES WITH EXPANDABLE T RINGS Description of Circumstances:
Northern States' Power Company recently informed NRC that the design-of certain butterfly valves at Monticello Nuclear Generating Station contained.a design error that shows the calculated maximum shaft stress to be underestimated.
The valves affected are Fisher Controls Company Series 9200 butterfly valves (6 to 48 inches) with expandable T rings (inflateble seals) manufactured from 1968 to 1972.
In the calculation of the shaft stress, the length between the shaft bushing and the attachment of the shaft to the valve disc used in the stress calculations was shorter than the actual length.
From discussions with the valve manufacturer, the cause of the difference in the design caicu-lation dimension and the actual dimension was that the shaft. bushings were recessed into the valve body to accommodate the pneumatic pass. ages for the inflatable seals.
Evaluation of the design error for the valves at Monticello
. indicate that the maximum shaft stress in the closed position. remains less than the minimum yield strength of the shaft material. The licensee intends to keep the affected valves closed while operating and plans to replace the shafts with ones of higher strength material.
The potential consequences of the design error is that, under accident loading conditions, there is a possibility for excessive deformation of the shaft.
Therefore, these valves when closed under the dynamic conditions of a LOCA or, if already closed, may not seal essentially leaktight.
Since these valves are used primarily in the containment purge and vent lines, a substantial safety hazard would exist if these valves could not be closed or if there was excessive leakage past these valves.
Containment integrity therefore could not be l
assured. The operability of containment purge and vent valves is item II.E.4.2 l
in the TMI Acticn Plan.
t The facilities identified that-may have the Fisher valves include Duane Arnold, Monticello, Palisades, Peach Bottom Units 2 ar.d 3, and Point Beach i
Units 1 and 2.
Discussions with the valve vendor indicate that.the reviews of the valve calculations affected shoulo be completed by mid-April.
l This inforration is provided as an early notification of a significant safety l
matter that is still under review by the NRC staff.
It is expected that license.:s will review the information for possible applicability to their plants.
If NRC evaluations so indicate, further licensee actions may be l
requested.
l
^
.g IN 81-14
' April-17, 1981 Page 2'of 2.
No written response to this information notice.is required. 'If you need
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- additional information with regard to this matter contact the Director of the appropriate NRC Regional Office.
Attachment:
Recently issued Information Notices s
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' Attachment IN 81-14 April 17,1981 RECENTLY ISSUED IE INFORMATION NOTICES
-Information Date of Notice No.
Subject Issue Issued to 81-13 Jammed Source P.ack in a 4/14/81 Specified Irradiator Gamma Irradiator licensees l81-12 Guidance on Order Issued 3/31/81 All BWR facilities January 9, 1981 Regarding with an OL or CP_-
Automatic Control Rod Insertion on Low Control Air Pressure 81-11 Alternate Rod Insertion 3/30/81 All BWR facilities for BWR Scram Represents with an OL or CP a Potential Path for Loss of Primary Coolant 81-10 Inadvertant Containment 3/25/81 All power reactor Spray Due to Personnel facilities with an Error OL or CP 81-09 Degradation of Residual 3/26/81 A1.1 power reactor Heat Removal (RHR) System facilities with an OL or CP 81-08 Repetitive Failures of 3/20/81 All power reactor Limitorque Operator SNB-4 facilities with an Motor-to-Shaft Key OL or CP 81-07 Potential Problem with 3/16/81 All power reactor Water-Soluble Purge Dam facilities with an Materials Used During OL or CP Inert Gas Welding 81-06 Failure of ITE Model 3/11/81 All power reactor K-600 Circuit Breaker facilities with an CL or CP 81-05 Degraded DC System at 3/13/81 All power reactor Palisades facilities with an OL or CP 51-04' Cracking in Main Steam 2/27/81 All power reactor Lines facilities with an OL OL = Operating Licenses CP = Construction Permits
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