40 © The Containment of Underground Nuclear Explosions Considerationsof cost, schedules, and test objectives shall not enter into the review of the technical adequacy of any test from the viewpoint of containment.!8 Along with their judgments on containment, each panel member evaluates the probability of contain- ment using the following four categories:'9 1. Category A: Considering all containmentfeatures and appropriate historical, empirical, and analytical data, the best judgment of the member indicates a high confidence in successful containment as defined in VIILF. below. 2. Category B: Considering all containment features and appropriate historical, empirical, and analytical data, the best judgment of the member indicates a less, but still adequate, degree of confidence in successful containment as defined in VIILF. below. 3. Category C: Considering all containment features and appropriate historical, empirical, and analytical data, the best judgment of the memberindicates some doubt that successful containment, as described in VIILF. below, will be achieved. 4, Unable to Categorize Successful containmentis defined for the CEP as: ... no radioactivity detectable off-site as measured by normal monitoring equipment and no unanticipated release of activity on-site. The Containment Evaluation Panel does not have the direct authority to prevent a test from being conducted. Their judgment, both as individuals and as summarized by the Chairman,is presented to the Manager. The Manager makes the decision as to whether a Detonation Authority Request will be made. The statements and categorization from each CEP memberare included as part of the permanent Detonation Authority Request. Although the panel only advises the Manager,it would be unlikely for the Manager to request detonationif the request included a judgment bythe CEP that the explosion might not be contained. The record indicates the influence of the CEP. Since formation of the panel in 1970, there has never been a Detonation Authority Request submitted for approval with a containmentplan that received a "°C" (‘some doubt’) categorization from even one member.”° 2! The Containment Evaluation Panel serves an additional role in improving containment as a consequence of their meetings. The discussions of the CEP provide an ongoing forum for technical discussions of containment concepts andpractices. As aconsequence, general improvements to containment design have evolved through the panel discussions and debate. CONTAINING VERTICAL SHAFT TESTS Once a hole has been selected and reviewed, a stemming plan is made forthe individual hole. The stemming plan is usually formulated by adapting previously successful stemmingplansto the particularities of a given hole. The objective of the plan is to prevent the emplacementhole from being the path of least resistance for the flow of radioactive material. In doing so, the stemming plan must take into accountthe possibility of only a partial collapse: if the chimney collapse extends only half way to the surface, the stemming above the collapse must remain intact. Lowering the nuclear device with the diagnostics down the emplacement hole can take up to 5 days. A typical test will have between 50 and 250 diagnostic cables with diameters as great as 1°/s inches packaged in bundles through the stemming column. After the nuclear device is lowered into the emplacementhole, the stemmingis installed. Figure 3-4 shows a typical stemming plan for a Lawrence 18Contaimment Evaluation Panel Charter, June 1, 1986, Section IIE.D. '9Containment Evaluation Panel Charter, June 1, 1986, Secuon VII. 2°The grading system for containment plans has evolved since the early 1970's. Prior to April, 1977, the Containment Evaluation Panel categonzed tests using the Roman numerals(1-IV) where I-l1] had about the same meaning as A-C and IV was a D which eventually was dropped as a letter and just became ‘‘unable to categonze.”’ 21 However, one shot (Mundo) was submitted with an ‘‘unable to categonze’’ categorization. Mundo was a joint US-UK lest conducted on May t. 1984,