Looking beyond the containment licensing issue to the certification of the commercial MHTGR plant under 10CFR52, the NRC Staff and the ACRS apparently agree that a full scale demonstration plant will be required. Because of the technical uncertainties associated with a new reactor design and the lack of operating experience, this Utility Review Team concludes that a confinement structure providing enhanced and diverse fission product retention should be required for the First of a Kind (FOAK) plant to demonstrate the MHTGR technology. This confinement structure might not need to be a conventional unvented, high pressure, low leakage containment, but might be a confinement system/structure that provides a more robust external barrier than is currently proposed. The Utility Review Team also concludes that the eventual containment requirements of the Commercial MHTGR Replica Plant will depend on the outcome of the current TDNS and the operating experience gained from the FOAK demonstration plant. To provide additional confidence to the utility industry, the FOAK plant should be built and operated on a utility grid in a commercial environment.

The present refueling plan for the MHTGR is to replace one-half of the core and one-sixth of the reflectors every 20 months. A single refueling outage involves removing and replacing 1064 elements. This process, when compared to current LWR design, appears significantly more complicated to accomplish while maintaining inventories of the fuel blocks and assuring proper fuel management. The current design concept incorporates many years of equipment and procedure evolution, and takes full advantage of state-of-the-art robotics technology to provide a highly automated process; however, an average element will be handled six times during refueling. Due to this extremely large amount of element handling, the ability of the fuel handling equipment to perform as required would have to be thoroughly demonstrated for utility acceptance. The level of complexity in refueling the MHTGR is of concern since a single failure at any point in the refueling process has a potential to delay the refueling schedule and poses a potential impact on reactor availability. The Utility Review Team recommends that the MHTGR Participants evaluate the incremental costs to provide redundant fuel handling equipment and associated plant conceptual changes to minimize the possibility of delays and to allow for concurrent refueling operations.

The present spent fuel storage capacity is based on the assumption that DOE will take possession of the spent fuel at the reactor site within one year of the time it was removed from the reactor under the provisions of the Nuclear Waste Policy Act of 1982. The one year storage capacity was

also specified as a design objective by the GCRA Utility/User Requirements. With the federal government's

inability to make visible progress toward either the permanent geologic repository or the Monitored Retrievable Storage facility, utilities have had to make provisions for onsite storage or face plant closure. It would be prudent, for a utility building a plant under current circumstances, to provide spent fuel storage for the expected useful life of the plant anticipating that newer plants would be the last to ship spent fuel to a government site. The Utility Review Team concludes that a utility choosing to build an MHTGR would not be prudent, nor likely, to incorporate only a one year spent fuel storage capacity.

The MHTGR concept incorporates many inherenț passive safety features and offers a plant that potentially requires neither operator action nor reliance on backup AC power to accomplish safety functions. The same features offer the prospects of simplified plant operations, a slow, stable response of the reactor to mismatches in heat generation and removal, and the potential for fewer active safety systems. The MHTGR design is a radiologically cleaner plant than current LWRs with minimum contamination of the primary system resulting in the potential for lower plant contamination levels, easier plant maintenance, lower personal exposures, and lower radwaste volumes to be disposed. The MHTGR Participants have capitalized on these potentials for simplified operations and projected a plant staffing of 303 personnel for the replica MHTGR Commercial Plant. The Utility Review Team recognizes that the MHTGR projections are based on a more simple design than current LWRS, and that the MHTGR Participants are anticipating a more relaxed regulatory environment at the time of deployment. The MHTGR Program Participants are to be commended for aggressively pursuing ways to minimize staffing requirements. The yardstick of utility experience is with LWRS, and therefore, the Utility Review Team concludes that the current staffing projections are based on overly optimistic assumptions regarding workscope definitions, workforce utilization roles, and regulatory requirements. The Utility Review Team recommends that the staffing needs also be evaluated using the current regulatory environment and INPO guidelines. More consideration should also be given toward additional personnel in regard to investment protection. This additional evaluation should be performed as a follow up to the current nonconservative staffing assumptions to bracket the possible range of O&M and capital costs. The Utility Review Team supports the concept of an MHTGR Central Support Organization. The Review Team believes this concept should be developed and implemented in parallel with the MHTGR design and certification program. Specific attention should be directed at clarifying the charter, structure and functional scope for this organization.

One design objective of the MHTGR program is to maintain an economic advantage of at least 10 percent in the levelized busbar cost of electricity relative to a comparably sized, state-of-the-art, coal plant alternative. In literature published to date, the MHTGR generating costs have been favorably compared to comparably sized coal plants (pulverized and atmospheric fluidized bed) and PWRS using data from the Department of Energy Economic Database (EEDB). The Utility Review Team compared the MHTGR total generating costs, based on a commercial operation date of 2010, with a 550 MWe pulverized coal plant and the Westinghouse 600 MWe AP-600 Advanced Light Water Reactor Plant (ALWR) as two alternatives, reasonably representative of the marketplace in which the MHTGR will have to compete. The Utility Review Team recognizes that the published cost data used in this study may contain relatively large uncertainties due to the early stage of MHTGR and AP-600 design and to probable increases in environmental regulation affecting the pulverized coal plant. Based on the published data, and understanding that uncertainties exist, the Utility Review Team concludes that the MHTGR is competitive with (or slightly better than) the pulverized coal alternative and is not currently competitive with the AP-600 alternative. If a conventional, unvented, high pressure, low leakage containment structure is required for the MHTGR the economic competitiveness with the pulverized coal plant will be diminished, or lost entirely. Likewise the MHTGR would become even less competitive with the AP-600 alternative. less costly containment alternative could probably be accommodated without affecting the economic competitiveness. The Department of Energy has recently initiated a MHTGR cost reduction study. The Utility Review Team agrees with the need for this study and endorses its timely completion. A reduction in base construction costs of 20-25 percent is a reasonable target.

A

The deployment of future nuclear electric generation options is driven by the need of the utility industry to provide safe, economic, and reliable power due to load growth and economic development, and eventual retirement of older generating capacity. As confirmed by recent experience, future nuclear plants must have a predictable cost, schedule, and reliability in order to provide a realistic option for commercial electric generation. Based on the conceptual design and preapplication licensing review, the MHTGR offers a viable application of an advanced nuclear concept with many inherent passive safety features and simplified operational requirements. Until the Fuel Technology Development Needs have progressed further, the containment issue has been resolved, and the FOAK plant has been built and demonstrated, there are considerable uncertainties regarding the time period when the MHTGR would be available for commercial deployment. Based on industry

1.4

reports, the Utility Review Team concludes that an optimum
date for the MHTGR FOAK deployment is near the turn of the
century. A period of time will be required to prove the
principles and accumulate enough operating history to
determine if the MHTGR can actually perform to expectations
and provide safe, economic, reliable power with a
predictable cost, schedule, and reliability. The Utility
Review Team optimistically predicts the time frame for
replica deployment to be in the years 2005 to 2010. In that
time frame, the MHTGR must be economically competitive with
state-of-the-art coal plants and LWRS with which the utility
industry has much experience and for which there exists a
worldwide support system. Industry reports estimate that
Advanced LWR designs will be certified in the mid-1990s,
without prototype testing, and could, therefore, have a one
to two decade additional advantage of operating experience
over the MHTGR. The LWR design will likely remain the
dominant nuclear power technology and MHTGR's chief
competitor for the next several decades. Utility acceptance
and the competitiveness of the MHTGR design in that time
frame will be measured as it is today; in terms of safety,
economics, reliability, and predictable investment risks.
Research and Development Recommendations

The Fuel/Fission Product Technology Development plans,
identified in Table 2.4-1, are comprehensive and appear to
address most of the identified needs. The Utility Review
Team recommends that certain areas be reexamined and
priorities increased to strengthen the MHTGR technology
base. Increased emphasis should be placed on development of
the Quality Control process. The MHTGR fuel test range
should be changed to 1200 - 2200 °C to clarify the high
temperature fuel integrity limits. Increased emphasis
should be placed on hydrolysis tests for depressurized core
conduction cooldown conditions. Fuel performance tests
should include power increases and decreases to simulate the
extra fuel duty from the 150 load following events per core.
The fission product transport R&D tasks should be reviewed
to determine whether they will yield sufficient accuracy for
and applicability to the MHTGR safety analyses.

Since key technology development tasks are scheduled to run
in parallel, suitable fallback positions should be
identified in case a key R&D task yields an unexpected
result. Finally, a Licensing Analysis Plan should be
developed that codifies how the future R&D results, together
with residual uncertainties, will be used in the MHTGR
safety analyses and licensing process.

The Utility Review Team concludes that the program scope for
the Fuel Handling Equipment Research and Development (Design
Data Needs (DDNs) M.34.13.01 through M.34.13.05) is
adequate. The Review Team recommends that the selected

1.5

design approach for each DDN be followed and completed on schedule. Use of the alternatives identified in Section 2 of each DDN should not be considered due to the potential impact on the schedule from unforseen problems.

Conclusion

In conclusion, the Utility Review Team recognizes that the MHTGR conceptual design offers a viable, potential nuclear option to the power industry for the next century and deserves continuing development. This endorsement is consistent with previous opinions expressed by the utility industry and more recently with the endorsement by the Advanced Reactor Corporation in the January 10, 1990 report by the Corporation's Ad Hoc Committee on DOE's Advanced Reactor Development Plan.