The use of performance measures on individual examiners in inspection schemes

Reliability of chemotherapy preparation processes: Evaluating independent double-checking and computer-assisted gravimetric control

Background and objectives Centralized chemotherapy preparation units have established systematic strategies to avoid errors. Our work aimed to evaluate the accuracy of manual preparations associated with different control methods. Method A simulation study in an operational setting used phenylephrine and lidocaine as markers. Each operator prepared syringes that were controlled using a different method during each of three sessions (no control, visual double-checking, and gravimetric control). Eight reconstitutions and dilutions were prepared in each session, with variable doses and volumes, using different concentrations of stock solutions. Results were analyzed according to qualitative (choice of stock solution) and quantitative criteria (accurate, <5% deviation from the target concentration; weakly accurate, 5%-10%; inaccurate, 10%-30%; wrong, >30% deviation). Results Eleven operators carried out 19 sessions. No final preparation (n = 438) contained a wrong drug. The protocol involving no control failed to detect 1 of 3 dose errors made and double-checking failed to detect 3 of 7 dose errors. The gravimetric control method detected all 5 out of 5 dose errors. The accuracy of the doses measured was equivalent across the control methods ( p = 0.63 Kruskal-Wallis). The final preparations ranged from 58% to 60% accurate, 25% to 27% weakly accurate, 14% to 17% inaccurate and 0.9% wrong. A high variability was observed between operators. Discussion Gravimetric control was the only method able to detect all dose errors, but it did not improve dose accuracy. A dose accuracy with <5% deviation cannot always be guaranteed using manual production. Automation should be considered in the future.

Visual Inspection Reliability for Precision Manufactured Parts

OBJECTIVE

Sandia National Laboratories conducted an experiment for the National Nuclear Security Administration to determine the reliability of visual inspection of precision manufactured parts used in nuclear weapons.

BACKGROUND

Visual inspection has been extensively researched since the early 20th century; however, the reliability of visual inspection for nuclear weapons parts has not been addressed. In addition, the efficacy of using inspector confidence ratings to guide multiple inspections in an effort to improve overall performance accuracy is unknown. Further, the workload associated with inspection has not been documented, and newer measures of stress have not been applied.

METHOD

Eighty-two inspectors in the U.S. Nuclear Security Enterprise inspected 140 parts for eight different defects.

RESULTS

Inspectors correctly rejected 85% of defective items and incorrectly rejected 35% of acceptable parts. Use of a phased inspection approach based on inspector confidence ratings was not an effective or efficient technique to improve the overall accuracy of the process. Results did verify that inspection is a workload-intensive task, dominated by mental demand and effort.

CONCLUSION

Hits for Nuclear Security Enterprise inspection were not vastly superior to the industry average of 80%, and they were achieved at the expense of a high scrap rate not typically observed during visual inspection tasks.

APPLICATION

This study provides the first empirical data to address the reliability of visual inspection for precision manufactured parts used in nuclear weapons. Results enhance current understanding of the process of visual inspection and can be applied to improve reliability for precision manufactured parts.

Aging and pretraining in industrial inspection

Learning-to-learn skills were hypothesized as reasons for poorer learning performance by older workers. To test this on a complex, simulated industrial inspection task, 84 subjects in three age groups were trained for the task. Half received restraining on organization of memory material and on size discrimination using tasks not directly related to the inspection task. Inspection speed decreased with age while errors increased. Pretraining reduced size discrimination errors and decision errors, having a larger effect than the age decrement and a consistent effect across age groups. There was no interaction between pretraining and the type (active or passive) of task training scheme used to train for the inspection task. It is concluded that intervention by pretraining and by the use of active training can improve the employability of older workers by removing the perceived barrier of their trainability.

Approaches to training for industrial inspection

This paper reviews the techniques available for detection and recognition training, and their application to industrial inspection. Systematic procedures are described for using these techniques as part of an integrated training scheme. Approaches to task analysis for inspector training are also discussed.