Value/impact analysis of Generic Issue 94, /open quotes/Additional Low Temperature Overpressure Protection for Light Water Reactors/close quotes/

Technical Report · Tue Nov 01 04:00:00 EST 1988

OSTI ID:6766634

Gore, B F; Vo, T V; Colburn, A J; Eschbach, E J; Harris, M S

This document presents a value/impact analysis of the expected risk reduction and associated costs for seven regulatory alternatives which have been proposed to resolve the generic issue of low temperature overpressure (LTOP) transients. It also presents an analysis of the reduction of public risk which was accomplished by the 1979 imposition of requirements for LTOP transient protection, when LTOP had previously been designated as a generic issue. The alternatives evaluated were: no action, prohibit operations with the reactor cooling system (RCS) ''water solid'' except when it is depressurized and vented, and require all operating reactors to maintain a bubble of steam or noncondensible gas (N/sub 2/) in the pressurizer when the RCS is not vented; prohibit operation of the RCS in a water-solid condition when either train of the overpressure mitigation system (OMS) is out of service; prohibit operation with the RCS in a water-solid condition when a high pressure safety injection pump is in service; prohibit restart of a reactor coolant pump when the RCS is in a water-solid condition; require that the pressure setpoint for automatic isolation of the residual heat removal system be raised above the setpoint for residual heat removal safety relief valve opening to maintain this relief path as backup to the OMS; and require the OMS to be safety grade. The risk analysis of each alternative estimated the public risk from the operation of the 63 presently operating pressurized water reactors summed over the period from the present to end of licensing. 20 refs., 7 figs., 45 tabs.

• Research Organization: Nuclear Regulatory Commission, Washington, DC (USA). Office of Nuclear Regulatory Research; Pacific Northwest Lab., Richland, WA (USA)
• OSTI ID: 6766634
• Report Number(s): NUREG/CR-5186; PNL-6589; ON: TI89006324
• Country of Publication: United States
• Language: English

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