23 quantitative information on the types of For PWR's with "large, dry" and "subatmospheric" containment designs [like The above comments demonstrate that there are no ready answers to questions regarding containment failure. If the NRC is unable to supply any hard numbers and is reduced to citing analytical uncertainties and studies in progess, it is difficult to understand how in three short months PL&G could accomplish an analysis sufficiently well-grounded to warrant a change in emergency planning regulations for the Seabrook plant. POTENTIAL TECHNICAL PROBLEMS WITH THE UTILITY'S CLAIMS The utility's consultant has asserted that the pressure at which the containment would fail is significantly higher than for most other similar large dry containment pressurized water reactors. They attribute this greater strength to several factors, including a larger than average containment volume and more steel used in the construction of the containment. The Subcommittee staff questions whether PL&G has failed to consider adequately a number of significant phenomena and possible reactor accident scenarios, several of which could possibly result in outcomes very different from those cited by PL&G. A few examples of these technical questions may be summarized briefly as follows. (a). The conclusions of the PL&G report depend crucially on the assumption that the containment failure pressure is roughly 225 psig. This value is much higher than the estimated containment failure pressures for other plants, and may not be adequately supported. In addition, containment failures generally may be assumed to occur at points of structural discontinuity (e.g., where piping enters or exits the containment). Even if the shell of the containment is stronger than average, one does not expect a shell rupture to be the first failure point of the containment. (b). PL&G examined only one containment bypass scenario; however, other bypass scenarios may well be relevant and could produce releases greater than those estimated in the PL&G study. (c). PL&G has argued that if noble gases are released from the containment after an accident, the containment will hold them long enough to permit decay to levels low enough to warrant a reduction of the EPZ. However, emergency planning as currently conceived assumes that off-site dose-response relationships must be examined without any protective actions. It appears that if noble gases are released without a significant delay, under various realistic worst-case weather scenarios, the acceptable off-site dose levels might well be exceeded at 10 miles. (d). Assumptions about the radioactive inventory released under high pressure melt ejection scenarios may not be consistent with recent analyses conducted by Sandia National Laboratory on these phenomena. (e). The report may not adequately consider the prospects that accident recovery actions could cause steam de-inerting by condensation, leading to hydrogen burns or detonation within the containment. (f). In examining earthquakes as a contributor to radioactive release scenarios, the report may not adequately consider after-shocks while the containment is pressurized, which adds an impulse pressure load. (g). The report's conclusions on radioactive releases as a consequence of steam generator tube ruptures may not be consistent with recent analyses conducted by Battelle Columbus Laboratory on steam generator tube rupture scenarios. In summary, it appears that PL&G may have been selective about their assumptions; if one made other, equally reasonable assumptions, the outcome might be much different. CHRONOLOGY OF KEY MEETINGS/DISCUSSIONS INVOLVING July 30, 1985 September 9, 1985 October 10, 1985 October 11, 1985 October 22, 1985 November 26, 1985 11 NRC/PSNH meeting discussion of SSPSA submittal according to NRC this included "the regulatory process including the reassessment of emergency preparedness requirements" NRC/PSNH staff and counsel conference call -- PSNH counsel, and NRC legal staff discussion ... Discussion that "once technical analysis is done - NRC/PSNH staff conference call NRC staff notes that feedback about the approach Seabrook was taking on demonstrating the ability to reduce the EPZ appeared to be different from what he understood in an earlier discussion (with PSNH staff) (NRC staff) noted that what he explained to (PSNH staff) in previous discussion was that the approach Seabrook will need to take is to compare the risk of Seabrook to the risk of typical reactor (WASH 1400) used as a basis for the regulation. (NRC staff) suggested Seabrook review NUREG-0396 the comparison it would be good to compare feature by feature" in "(NRC staff) said Seabrook should not be developing FEMA staff notes that Brookhaven is reviewing the containment and time-to-failure aspects of the PRA Discussion of the size of the EPZ and legal Seabrook coordination meeting with FEMA, NHY, NH December 1985 February 1986 April 1986 July 9, 1986 July 21, 1986 July 25, 1986 July 29, 1986 CHRONOLOGY 2 and MA state civil defense staffs Further "Seabrook Station Risk Management and Emergency Planning Study," Pickard, Lowe, and Garrick NUREG/CR-4540, "A Review of the Seabrook Station "Seabrook Station Emergency Planning Sensitivity NRC, PSNH, PL &G meeting to discuss PSA program 11 NRC staff meeting "(PSNH staff) says before they go for it give them a reading by October what are the merits of this piece of work -- does it provide some basis to go forth with exemption" NRC staff notes "What do we [Emphasis added] have to justify to change EPZ? ... need to consider technical and legal" (emphasis in original) PSNH requests that NRC expedite the technical "A future submittal, depending on the results of the technical review, may request a change to the emergency response plan process for Seabrook Station. We cannot, at this time, specify what action such a future request may seek, but it is important that we address as soon as possible what options are available to us relative to full power licensing. This is important in light of the apparent strategy of the State of Massachusetts to delay the process." (emphasis added) - July 18 or 29, 1986 NRC staff meeting "(NHY) wants to know if this could serve as a technical argument. If not, he won't file. Point out which technical arguments are good vs. no" "Seabrook has thrown away containment failure" "Did they include any real data vs. generic May have to go back and tidy up PRA, but probably not" August 5, 1986 August 6, 1986 August 6, 1986 August 11, 1986 August 13, 1986 August 14, 1986 August 27, 1986 NRC Staff and PSNH meeting "NRC is beginning an expedited review of the study to assess the technical adequacy of PSNH's analysis to support the study's conclusions." Brookhaven National Laboratories (BNL) compiles project description for Review of the Emergency Planning Sensitivity Study for Seabrook NRC Staff, BNL, and PSNH onsite walk through - Internal NRC staff memorandum "It is important to decide what direction NRC is going to take on this issue before a detailed technical review can start. A decision chart set up in the form of three questions is attached for your consideration" NRC staff notes -- PSNH request - "NRC will give them top priority preliminary review in months normally takes "Sense of urgency ... out of ordinary" no discussion of it holding up "There are so many options get rid of Mass. so they don't have to submit" (emph. added) Meeting at BNL with NRC staff and PSNH NRC staff notes "Do review in short period of time to get positive response or questions needed to get there" NRC staff - "Unique features of Seabrook containment Let's try to make it more unique show it's better than average" (emphasis added) - NRC staff and PSNH meeting "Review group to (NRC ... 88 "What are possibilities 3 mile EPZ with plume? "Shrinking of planning zone vs. evacuation zone may be able to reduce evacuation zone but not planning zone" (emphasis in original) ... |