Before an old radiochemical（放射化学的）/reidiəu'kemikəl/ laboratory could be cleared, safety chemist Imani Vale found that its inventory marked the twenty jars in question（所涉及的）/ɪn ˈkwestʃən/ as plutonium（钚）/pluː'təʊnɪəm/ or strontium（锶）/'strɒntɪəm; 'strɒnʃ(ɪ)əm/ waste. A detector beside the sealed teaching reactor（反应堆）/rɪ'æktə/ also reported radioactivity（放射性）/,reɪdɪəʊæk'tɪvɪtɪ/. In light of（鉴于）/ɪn laɪt əv/ that alarm, Imani closed the room rather than（而不是）/ˈrɑːðə ðæn/ accept the faded labels. The team had to decide whether the material was radioactive, chemically hazardous, or both before further handling（在进一步接触处理之前）/bɪˈfɔː ˈfɜːðə ˈhændlɪŋ/.

The detector failed its first calibration. Its anode（阳极）/'ænəʊd/ and cathode（阴极）/'kæθəʊd/ fed a diode（二极管）/'daɪəʊd/ circuit, but the ammeter（电流表）/'æmɪtə/ showed unstable current. An electroscope（验电器）/ɪ'lektrəskəʊp/ responded to electrostatic（静电的）/ɪ,lektrə(ʊ)'stætɪk/ charge from nearby packaging, while electromagnetic induction（电磁感应）/ɪn'dʌkʃ(ə)n/ from an electromagnet（电磁铁）/ɪ,lektrə(ʊ)'mægnɪt/ introduced noise into an unshielded cable. A cracked core changed magnetic reluctance（磁阻）/rɪ'lʌkt(ə)ns/ and amplified the measurement error. A technician had allowed the backup cell to undercharge（充电不足）/ʌndə'tʃɑːdʒ/, and the switchboard（配电盘）/'swɪtʃbɔːd/ had hidden the low voltage. None of these faults proved that a jar emitted radiation or identified a radioactive source.

A second team checked atomic（原子的）/ə'tɒmɪk/ signatures. A plasma（等离子体）/'plæzmə/ source excited each sample, and helium（氦气）/'hiːlɪəm/ carried the emission（发射光谱）/ɪ'mɪʃ(ə)n/ through the instrument's optics（光学系统）/'ɒptɪks/. The method uses quantum（量子的）/'kwɒntəm/ transitions around an atomic nucleus（原子核）/'njuːklɪəs/ to identify elements. One fluorescent（荧光的）/flʊə'res(ə)nt; flɔː-/ marker produced visible radiance（辐射光）/'reɪdɪəns/, while a radiant（辐射式的）/'reɪdɪənt/ heater affected the baseline. Once those effects were removed, no plutonium line appeared. The remaining signal was measurable（可测量的）/'meʒ(ə)rəb(ə)l/ but in line with（与……一致）/ɪn laɪn wɪð/ background radiation.

Chemical tests then helped account for（解释）/əˈkaʊnt fɔː/ the labels. In one beaker（烧杯）/'biːkə/, hydrochloric（盐酸的）/,haɪdrəʊ'klɒrɪk/ residue met an alkali（碱性物质）/'ælkəlaɪ/ and formed a hydroxide（氢氧化物）/haɪ'drɒksaɪd/ precipitate（沉淀物）/prɪ'sɪpɪteɪt/. Each ion（离子）/'aɪən/ was traced to soluble（可溶的）/'sɒljʊb(ə)l/ iodide（碘化物）/'aɪədaɪd/, magnesium（镁）/mæg'niːzɪəm/, nitrate（硝酸盐）/'naɪtreɪt/, or sulphate（硫酸盐）/'sʌlfeɪt/ in saline（盐水的）/'seɪlaɪn/ liquid. Selenium（硒）/sɪ'liːnɪəm/ and silica（二氧化硅）/'sɪlɪkə/ remained in a heterogeneous（非均质的）/,het(ə)rə(ʊ)'dʒiːnɪəs; -'dʒen-/ solid with low purity（纯度）/'pjʊərɪtɪ/. These mixtures explained most catalogue terms, but not the claim of radiochemical contamination. Imani chose instead to set aside（暂时搁置）/set əˈsaɪd/ the radiation classification and continued the hazard review.

Several jars still required controlled disposal. A hydrocarbon（碳氢化合物）/,haɪdrə(ʊ)'kɑːb(ə)n/ had enough volatility（挥发性）/,vɒlə'tɪlətɪ/ to vaporize（汽化）/'veɪpəraɪz/ if heated; a sulphurous（含硫的）/'sʌlfjʊərəs/ odour seemed to emanate（散发）/'eməneɪt/ from another jar containing sulphur（硫）/'sʌlfə/. Staff did not let either liquid seethe（沸腾）/siːð/ on the hotplate（电热板）/'hɑtplet/. A platinum（铂）/'plætɪnəm/ catalyst（催化剂）/'kæt(ə)lɪst/ could promote a reaction, while an inert（惰性的）/ɪ'nɜːt/ gas limited it. Notes described catalyst regeneration（再生处理）/rɪdʒenə'reɪʃn/ and a bath used to electroplate（电镀）/ɪ'lektrə(ʊ)pleɪt; ɪ,lektrə(ʊ)'pleɪt/ metal. A thermocouple（热电偶）/'θɜːməʊkʌp(ə)l/ recorded heat for a thermodynamics（热力学）/,θɜːmə(ʊ)daɪ'næmɪks/ study, and an ultrasonic（超声波的）/ʌltrə'sɒnɪk/ cleaner produced ultrasound（超声波）/'ʌltrəsaʊnd/. None of those processes created nuclear waste.

Imani told the clearance manager, “We can reject the radiation label, but we cannot call these jars harmless.” On that basis（据此）/ɒn ðæt ˈbeɪsɪs/, Imani's team separated flammable, corrosive, and ordinary laboratory waste and began to carry out（实施）/ˈkæri aʊt/ disposal under the correct rules. The corrected list named no radioactive material and preserved every chemical warning. The result was concrete: all twenty jars entered verified waste streams, so the laboratory passed clearance two days ahead of schedule（提前完成进度）/əˈhed əv ˈʃedjuːl/.