ML19296B096
| ML19296B096 | |
| Person / Time | |
|---|---|
| Issue date: | 02/07/1980 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML19296B091 | List: |
| References | |
| NUDOCS 8002200055 | |
| Download: ML19296B096 (2) | |
Text
4 FEB 7 1980 b.
Additional Holst Safety Systems and Features of the X-SAM Crane System (1) An energy absorbing torque limiter (EATL) is incorporated in the hoist gear case. The EATL unit is a wet type (oil) niulti-disc spring loaded clutch which can be adjusted or calibrated to slip at a prescribed torque. The wet type clutch is preferable to a dry type friction clutch because of the repeatability of its performance without any concernable change in the coefficient of friction. The dry type clutch would be susceptible to contaminatio.1 of the friction surfaces and would have difficulty dissipating the heat energy if required to operate for more than a short time; the torque setting of the dry clutch thus would be affected and would introduce uncertainty about the margin of safety for the hoisting system components.
The EATL unit has been used and tested on the LOFT Contain-ment Building Polar Crane. The tests simulated a "two blocking" accident and were conducted at several hoisting speeds, including 1697. motor speed. All the tests showed that the EATL could effectively orevent damaging overloading of the wire ropes and other affected components in the hoisting systems.
The staff finds the application and perforrrance of an oil-wetted torque clutch an acceptable method of preventing failures in the reeving system components due to overloading because this type of clutch has been proven to be a reliable type as evidenced in the automotive and industrial applications and also in the tests performed on the LOFT crane (ref. Safety System Tests, para. 0.1).
(2) The Emergency Drum Brake System typically consists of either disc or band type brakes that are applied directly to the wire rope drum (s). These 80022 00 $5
11 7E9 7 1980
=
the integrity of the wire rope by limiting the stress in the rope.
EDERER also sizes the wire rope to limit stresses in it during a seismic event to not exceed 907. of the yield strength of the wire rope with a 15*.' margin for degradation, which results in a margin of 1.5 for overload conditions (see page 13) and a minimum of 1.1 for peak seismic overload. The staff finds the use of MCL minus degradaticn allowance an acceptable approach for X-SMi cranes when equipped with the HIPS systems because the margin on safety is consistently higher than that obtainable with a conventional non-slip overload sensing
- system, b.
Existing Cranes:
In the case of alteration or conversion of an existing crane to a crane having single-failure-proof features, it is an objective to evaluate the acceptability of the components and structures that are not replaced.
Because an enumeration of changes or limitations to conformance with the regulatory guide cannot be determined until the existing crane has been surveilled and evaluated, the EDERER report must of necessity refer to the applicant for compliance for those structures and component that are not replaced. The staff concurs with the conclusion that the structures and components not replaced by a conversion effort should be evaluated separately for conformance to the regulatory guide positions.
In addition, information identified in Appendix C (pages C.4 and C.5) related to regulatory positions C.1.c, C.1.d, C.1.e, C.1.f, C.S.a and C.S.b should be addressed in the Safety Analysis Report by the applicant or owner of the crane.