This report was .prepared as an account of work sponsored by an agency of t h e United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, make any warranty, express or implied, or assumes a n y legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by t h e United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of t h e United States Government or any agency thereof. DISCLAIMER Portions of this document may be illegible in electronic image products. Images are produced from the best available original document.

This report evaluates both the positive and negative consequences of adding water to a degraded reactor core during a severe accident. The evaluation discusses the earliest possible stage at which an accident can be terminated ar,d how plant personnel can best respond to undesired results. Specifically discussed are (a) the potential for plant personnel to add water for a range of severe accidents, (b) the time available for plant personnel to act, (c) possible plant responses to water added during the various stages of core degradation, (d) plant instrumentation available to understand the core condition and (e) the expected response of the instrumentation during the various stages of severe accidents.

No abstract

SECY-88-147, dated May 25, 1988, presented the NRC staff's program pian to evaluate generic severe accident containment vulnerabilities via the Containment Perfonn_ce Improvement Program (CPIP). This effort was predicated on the presumption that there are generic severe accident challenges for each light water reactor (LWR) containment type that should be addressed _odetermine whether ad.. ditional regulatory guid,'mce or requirements concerning needed containment features are warranted, and to coxffirm the adequency of the existing Commission policy. These challenges should be addressed to determine the possible need for additional regulatory guidance or requirements related to contaimnent features. The ability of contairtments to successfully survive some severe accident challenges is uncertain, as indicated in Draft NUREG-1150. The CPI effort is intended to focus on evaluation of hardware and procedural issues related to generic containment challenges. This report documents the results of NRC-sponsored research related to severe accident challenges and potential enhancements that could improve contaimnent performance. The purpose of this report is to provide PWR Ice Condenser owners with information they may find useful in assessing their plants as part of their Individual Plant Examination (IPE) program. No requirements are contained in this report and it is being provided tbr information only. Specific guidance to the industry on the use of this report, and similar reports has been given in Generic Letter 88-20, Supplement 3, dated

This document contains new concepts or the author(s) interpretation of new calculations and/or measurements; accordingly, EG&G Idaho, Inc. is required by the Un,ted States Government to include the following disclaimer: DISCLAIMER This reportwas preparedas an accountof work sponsoredby an agency of the UnitedStatesGovernment.Neitherthe UnitedStatesGovernmentnor any agency thereof, nor any of their employees, makes any warranty,express or implied, or assumesany legal liabilityor responsibilityfor the accuracy, completeness,or ,, usefulnoss of any information,apparatus, product or process disclosed, or representsthatitsusewould notinfringeprivatelyowned rights.Referencesherein to any specificcommercialproduct,process,or servicebytrade name, trademark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement, recommendation,orfavoringbythe UnitedStatesGovernmentorany agency thereof. The views and opinionsof authors expressed herein do not necessarilystate or reflect those of the UnitedStates Governmentor any agency thereof.°