This report establishes standard unit costs and scaling rules for estimating costs of material, equipment, land, and labor components used in magnetic confinement fusion reactor plant construction and operation. Use of the standard unit costs and scaling rules will add uniformity to cost estimates, and thus allow valid comparison of the economic characteristics of various reactor concepts .

Neutron activation of materials in a compact tokamak fusion reactor has been investigated. Results of activation product inventory, dose rate, and decay heat calculations in the blanket and injectors are presented for a reactor design with stainless steel structures. Routine transport of activated materials into the plasma and vacuum systems ;s discussed. Accidental release of radioactive materials as a result of liquid lithium spills is also considered .

SUMMARYThe transport and deposition of neutron activation products in a helium cooled tokamak fusion power plant are investigated. Stainless steel is used as coolant channel material for a helium/steam system. The important gamma emitting nuclides 56Mn , 54Mn , 57Co , 58co , 60Co , 51 Cr , and 99Mo are considered. The dominant release mechanism identified is direct daughter recoil emission from (n,x) type reactions. Corrosion and evaporation are discussed. The radionuclide inventory released by these mechanisms is predicted to exceed 1 x 10 4 Ci for a reference reactor design after only several days of operation, and approach 3.5 x 10 4 Ci in equilibrium. A mass transport model is then used to predict the deposition pattern of this inventory in the reactor cooling system.The results indicate that the blanket regions of the reactor can be designed to promote deposition within the reactor itself, reducing radiation hazards in the outer portions of the cooling loop. The design as given predicts 17% deposition in the blanket, 8% in the hot pipe runs, and 75% in the steam generators. Predicted contact dose rates range from 10 R/hr on pipes directly out of the reactor to 100 mR/hr on the steam generators. Internal shielding and the assumed shell thickness reduce doses on the steam generator substantially.The predicted inventory of 56Mn entrained in the coolant (0.8 Ci) may provide hazards in loss of coolant type accidents. This is considered an onsite occupational problem rather than an environmental hazard, as the released activation products are expected to plate out readily on surfaces in the containment building. However, deposition rates and the impact on containment filtering and atmosphere spray systems should still be assessed.iii CONTENTS

This issue is concerned with the high pump seals in pressurized water reactors. loss of coolant accident (LOCA). rate of failures of reactor cool ant Such an event can create a small Following are descriptions of typical reactor coolant pump seals (Makay and Adams 1979). • BYRON-JACKSON supplies primary coolant pumps for the C-E and B&W reactor systems in the USA. For a B&W system they introduced a three-stage, mechanical-type face seal equally staged, while for a C-E system they supply the pumps with four seal stages. Three stages are equally staged and the fourth stage is used as a vapor seal at the top of the arrangement. The rotating face is titanium carbide, while the stationary face is carbon in both cases.

This supplemental report is the fourth in a series that document and use methods developed by the Pacific Northwest Laboratory to calculate, for prioritization purposes, the risk, dose and cost impacts of implementing resolutions to reactor safety issues. The initial report in this series was published by Andrews et al. in 1983 as NUREG/CR-2800. This supplement consists of two parts describing separate research efforts: (1) an alternative human factors methodology approach and (2) a prioritization of the NRC's Human Factors Program Plan. The alternative human factors methodology approach may be used in specific future cases in which the methods identified in the initial report (NUREG/CR-2800) may not adequately assess the proper impact for resolution of new safety issues. The alternative methodology included in this supplement is entitled Methodology for Estimating the Public Risk Reduction Affected by Human factors Improvement. The prioritization section of this report is entitled Prioritization of the U.S. Nuclear Regulatory Commission Human Factors Program Plan. iii PREFACE This report was prepared by the Pacific Northwest Laboratory CPNL) to communicate results of the Prioritization of Safety Issues (PSI) Project. An objective of the project is to develop a methodology for use in quantifying risk, dose and cost impacts of resolutions to reactor safety issues and to apply this methodology issues of interest to the NRC. Results of this project will be used by the NRC to support, in part, decisions on resource allocations to resolve specific issues. Prioritization decisions by the NRC are documented in NUREG-0933, A Prioritization of Generjc Safety Issues. This is the fourth in a series of reports from the PSI project. The first report, the initial NUREG/CR-2800, contains a description of the methodology and three example issue analyses. The second report (Supplement 1) contains results in 15 additional issues. The third (Supplement 2) contains results of analyses for 31 more issues. xi ACKNOWLEDGMENTS The results contained in this supplement are the product of efforts of the authors, review team and support personnel. Participants in these activities are as toll ows: AUTHORS