Resolution of Generic Safety Issues: Task II.H: TMI-2 Cleanup and Examination (Rev. 3) ( NUREG-0933, Main Report with Supplements 1–34 )
The objectives of this task were to: (1) maintain safety and minimize environmental impact of post-accident operation and cleanup of TMI-2; and (2) obtain and factor into regulatory programs safety-related and environmental information from the TMI-2 cleanup.
ITEM II.H.1: MAINTAIN SAFETY OF TMI-2 AND MINIMIZE ENVIRONMENTAL IMPACT
This TMI Action Plan48 item covered the efforts by NRC to monitor, review, and assess the safety and environmental impact of the post-accident operation, cleanup, and possible recovery operations at TMI-2 to ensure that: (1) reactor safety and reactor building integrity was maintained; (2) environmental impacts were minimized and radiation exposure to workers, the public, and the environment was within regulatory limits and was as low as reasonably achievable (ALARA); and (3) storage and/or disposal of radioactive wastes from cleanup operations were safe. The TMI Program Office (TMIPO) within NRR directed the NRC activities under this task.
NUREG-0698,198 Rev. 1, was issued in February 1982 and provided an updated chronology of TMI-2 cleanup activity, major milestones, and accomplishments summarized as follows:
(1) In March 1981, the NRC issued NUREG-0683,199 a Final Programmatic Environmental Impact Statement (PEIS) related to the decontamination and disposal of radioactive wastes resulting from the accident.
(2) In conjunction with the issuance of the PEIS, the NRC also issued a Policy Statement211 in April 1981 which stated that the cleanup should be expedited consistent with maintaining public health and safety.
(3) In July 1981, a Memorandum of Understanding (Appendix A to NUREG-0698198) concerning the removal and disposition of radioactive solid wastes from the cleanup operations was signed by representatives of NRC and DOE.
(4) Cleanup operations were implemented according to the plan. Decontamination of accident-generated water in the auxiliary and fuel handling buildings was completed by mid-1981. Decontamination of accident water located in the reactor building sump and reactor coolant system was initiated in September 1981. Visual examination of the top of the damaged reactor core was performed with the use of a remote miniature TV introduced through control rod drive housing.
This issue was identified in NUREG-0885210 as one of NRC's highest safety priorities.
The cleanup operation was implemented377 and the issue was programmatically RESOLVED with appropriate management resources and priorities assigned; no new requirements were established. In NUREG/CR-5382,1563 it was concluded that consideration of a 20-year license renewal period did not affect the resolution.
ITEM II.H.2: OBTAIN TECHNICAL DATA ON THE CONDITIONS INSIDE THE TMI-2 CONTAINMENT STRUCTURE
Pertinent technical information was to be obtained on the conditions of the TMI-2 facility as cleanup operations proceeded. The information to be gathered and disseminated (Item II.H.3) was divided into two distinct categories: (1) data to be obtained prior to gaining access to the primary system; and (2) data to be obtained after access to the primary system. In the first category, information was to be obtained on: (1) instrumentation and electrical equipment survivability under the accident conditions; (2) environmental conditions in the containment and auxiliary buildings; (3) fission-product release, transport, and deposition; (4) decontamination, dose reduction, and waste handling; and (5) debris in the containment building, in particular the containment sump.
After access to the primary system was obtained, the primary system pressure boundary was to be characterized including the steam generators, pumps, and other mechanical and structural components. Techniques were to be developed for a non-destructive assay of fuel distribution in the primary system for assessing criticality control during examination and cleanup operations and for fuel removal, packaging, shipment, and disposal. Detailed pre-access reactor and core damage assessments were to be made followed by careful in situ and away-from-site fuel and reactor internals examinations.
The societal risk from the operation of nuclear power plants would not be reduced by just obtaining, preserving, and disseminating information as outlined above. However, the potential for risk reduction due to proper use of increased knowledge obtained by studying the TMI-2 facility cannot be denied. The information that could be obtained through this item was to be used in the pursuance of other safety issues such as:
A-45 Shutdown Decay Heat Removal Requirements
A-48 Hydrogen Control Measures and Effects of Hydrogen Burns on Safety Equipment
II.B.5 Research on Phenomena Associated with Core Degradation on Fuel Melting
II.B.7 Analysis of Hydrogen Control
II.B.8 Rulemaking Proceedings on Degraded Core Accidents
II.E.3.4 Alternate Decay Heat Removal Concepts
Insights gained from the above TMI-2 information were assumed in a qualitative sense in the development of the potential risk reduction for the 6 issues outlined above. The total risk reduction estimated for the resolution of these 6 issues was 610,000 man-rem of public exposure and 650,000 man-rem of occupational exposure; to include further potential risk reduction under Item II.H.2 (and II.H.3) would result in double-counting.
At the time this issue was evaluated, it was assumed that the TMI-2 cleanup was about 40% complete, about 60% of the $1.2 Billion licensee estimated cost remained to be expended, and about 10% of the licensee's costs was consumed in the preservation and recording of technical data. It was estimated that there was $72M of licensee funding yet to be expended on this effort. Using the TMI Action Plan48 cost and manpower estimates and extrapolating through FY-1985, it was determined that the NRC cost would be about $36M, of which, about 60% or $22M had not yet been expended. It was also assumed that a DOE commitment of approximately $22M had yet to be expended. This resulted in a total future cost of about $116M for the completion of Items II.H.2 and II.H.3.
Table II.H.2-1 shows the estimated risk reduction, cost, and recommended priority for each of the above 6 issues. The total future costs estimated for all 6 issues was approximately $2 Billion. The total future cost for completion of Items II.H.2 and II.H.3, although large ($116M), was a reasonably small portion (~6%) of total future costs expected for the resolution of those safety issues that will utilize information obtained from the TMI-2 facility. If the cost associated with these items was compared only with the estimated total cost for resolving Issues A-45 and A-48, the cost of the TMI information retrieval program would represent only about 15% of the cost of these two issues. Compared to Items II.B.5 and II.B.8, the cost of the TMI information retrieval program represented less than 10% of the estimated cost for the completion and implementation of Items II.H.2 and II.H.3.
|Issue||Recommended Priority||Risk Reduction (Man-Rem)||Total Cost
|A-45*||High||4.7 x 105||500|
|A-48*||High||5.2 x 105||208|
|II.B.5||High||2.2 x 105||1,300|
|II.B.7||(Subsumed in A-48)||-||-|
|II.B.8||(Subsumed in II.B.5)||-||-|
|II.E.3.4||(Subsumed in A-45)||-||-|
|TOTAL||1.2 X 106||2,008|
* Unreleased Draft Analyses
This issue addressed the collection (Item II.H.2) and dissemination (Item II.H.3) of information that was to be used in the completion of other specific safety issues and thus was not analyzed separately. However, examination of the recommended priority for those issues that depended in part on input from the TMI information to be obtained via this issue indicated that this issue supported other high priority issues. Thus, this issue was given a high priority (See Appendix C).
Core examinations indicated that a large flow of molten material (about 19 metric tons) relocated into the lower plenum after the accident had been in progress for about 225 minutes. All vessel steel, nozzle, and guide tube samples extracted from TMI-2 were tested and analyses of the potential reactor vessel failure modes were conducted. The staff's findings were forwarded to the Commission in SECY-93-119.1539 Thus, this issue was RESOLVED with no new requirements.1540 Consideration of a 20-year license renewal period would not affect this resolution.
ITEM II.H 3: EVALUATE AND FEEDBACK INFORMATION OBTAINED FROM TMI-2
This TMI Action Plan48 item involved the analysis of data obtained during the examination of systems inside the containment building at TMI-2, the subsequent decontamination and restoration of the facility, and the feedback of the information obtained into other appropriate regulatory programs. Item II.H.2 was devoted to the efforts necessary to acquire and record information during the cleanup of the TMI-2 facility.
Since the acquisition of the TMI-2 data had to be accomplished before the data could be evaluated, no changes in requirements could be ascertained until those data were evaluated. Therefore, Items II.H.2 and II.H.3 were inextricable and were combined and evaluated together under Item II.H.2.
ITEM II.H.4: DETERMINE IMPACT OF TMI ON SOCIOECONOMIC AND REAL PROPERTY VALUES
Studies were to be conducted on: (1) the effect of the TMI accident on the value of real property in the Harrisburg, Pennsylvania, area; and (2) the socioeconomic impact of the TMI accident on the region in south-central Pennsylvania which surrounds TMI. This item was initiated to increase the NRC knowledge in assessing levels of safety and, therefore, was considered a Licensing Issue.
A Pennsylvania State University study313 of the effects of the accident on property values in the vicinity of the TMI-2 site was accepted by the staff and published in March 1981. A study of the socioeconomic effects of the accident in the region surrounding the plants was performed by Mountain West Research Incorporated. This report314 was accepted by the staff and published in July 1982. Thus, this Licensing Issue was resolved.