Case study: SAT application for maintenance qualification (India)

This case study is an example of a typical SAT-based application in Indian NPP's for the qualification of its maintenance personnel. This case study is organised on the following logic:

(1) What are to be achieved ? (NPP targets)

(2) What need to be done, where and by whom (job tasks) (3) Target equipment, specific task and

Target personnel (competency structure) (4) Knowledge & ability/skills statements (design)

The systematic approach to training methodology (SAT) adopted for qualifying maintenance personnel is based on identification of competencies that directly contribute to the NPP performance indicators. This positive contribution simply means reducing the frequency of events connected with equipment failures and maintenance — elated causes.

Job Tasks

To achieve such a goal, the objectives of maintenance qualification have to necessarily focus on maintenance quality. Such a quality assurance in turn, calls for tasks of good maintenance planning, good maintenance execution and good maintenance feed back. To explain further :

• Good planning means that all aspects of the maintenance work have been understood and arranged in a systematic manner. All deviations experienced in the past during similar executions have been used for improvement of plans and procedures.

• Good execution implies performing exactly as per above plans and procedures and keeping good feed back is analysis of above performance data, establishing root causes of failures and implementing corrective actions.

In order now, to convert above program into day-to-day maintenance tasks, the following criteria for shortlisting were used.

SURVEILLANCE to demonstrate reactor safety at all times PREVENTIVE MAINTENANCE (INSPECTION, to prevent abnormal equipment conditions TESTING, CALIBRATION, REPLACEMENT

OVERHAUL)

PREDICTIVE MAINTENANCE to reduce frequency of forced outages or spurious actuations

TROUBLE SHOOTING & REPAIR prompt response to equipment problems

• POST MAINTENANCE TESTING to avoid negative results due to faulty planning or execution

• ROOT CAUSE ANALYSIS/RECORDS Target Equipment

Even though the above title applies to all plant equipment, as a practice, performance of only certain specific safety - related class of equipment are periodically reported in NPP performance reports Accordingly only such equipment were short listed for purpose of maintenance qualification.

Such equipment meet the following criteria

• mitigate transients or accidents

• used in emergency operating procedures

• whose failure fail critical safety equipment

• whose failure cause plant trips or set back

Equipment so identified were grouped according to the NPP systems they belong for qualification purposes

Typical Tasks

Specific tasks for such equipment now need to be shortlisted for defining the needs of qualification. It is because it is neither necessary nor feasible to qualify personnel for all tasks, for the following reasons

• Many tasks are generic support tasks that are common to equipment regardless of whether they are safety related or otherwise.

• Many tasks do not require formal certification as personnel who work on safety related equipment are already trained formally in class room as well as on job, on all duty areas of other systems.

• Resources needed including time frames for an exhaustive task listing are prohibitive and not justified as NPP systems and organisational aspects keep changing to meet new challenges.

A desirable approach evolved by us then was as below:

• List all preventive, predictive and analytical tasks done during, and, 3 months preceding successful operations of the NPP. Call this set T-l.

• List all corrective tasks done during last three years in the above NPP including analysis of root causes. Call this T-2

• List all corrective tasks as at (11) in other sister NPP's in the county Call this T-3

Set T-l are frequent tasks that must be done to keep the NPP operating. Set T-2 revealed deficiencies in the NPP for which readiness (plans) must exist to promptly diagnose and repair Set

T-3 are generic, common mode, culture specific deficiencies for which detailed pro-active capability must exist. All these tasks were reported in the monthly performance reports of the NPP. This led to easy shortlisting and segregating of typical tasks for qualification.

Target Personnel

Maintenance personnel in this context, are organised in four disciplines at five levels of designations. The disciplines are :

Mechanical Electrical

Instrumention & cntrol

(On-power) refuelling systems.

The broad criteria for allocation of duties and tasks are given below in Table-I.

TABLE-I. DUTIES OF QUALIFIED MAINTENANCE STAFF Qualification

l.Level-I 2. Level-II

3. Level-in 4. Level-IV 5. Level- V

Position

Senior Maintenance Engineer

Maintenance Engineer

Assistant Maintenance Engineer

Senior Maintainer Maintainer

Duties & Capability Overall administration and quality management in his discipline

Planning, Supervision and QA checks, Analysis for 100% target equipment Planning, Supervision and QA checks, Analysis for 50%

target equipment.

Conduct or Execution for 50% target equipment.

Conduct or Execution for 25% target equipment

Maintenance engineers work as planners and evaluators for the identified equipment. They are specifically responsible to ensure the following:

• The equipment must fulfil the system function under all (normal, abnormal or emergency) modes of operation.

• Its design intent must be retained through its economical service life.

• Reported deficiencies are eliminated including root cause corrections.

• No new deficiencies as a result of the maintenance done, should get added.

They facilitate the execution of maintenance by providing up-to-date procedures, qualified human resources, spares and know-how, in their area of responsibility. These form bases for design of their training and qualification. Maintainers need to be knowledgeable and skilled for the execution of work as per approved safety and maintenance procedures including work control, diagnosis and recording.

Final job specific competencies (KSA's) structure

Based on all above logic, job specific KSA's (competencies) for the typical tasks of the target equipment for each position has been developed Table-2 is a typical example for mechanical maintenance

DESIGN & DEVELOPMENT

Based on such analysis as m Table-II, detailed syllabi and test items for knowledge checks and on-job training check sheets for skills and attitude checks have been developed Only those who are already trained on the preparatory program through the nuclear training centres and have adequate and certified field expenence at least m the routine maintenance tasks of the NPP are admitted to the maintenance qualification program described here. The entry level requirements are completion of training and adequate expenence in

• Science fundamentals

• NPP technology

• NPP Systems and layout

• Radiation protection and safety rules

• Tools & equipment skills

• Advanced equipment skills

The candidates admitted must clear skills checklist on job. The last section is an extract from

"test questions and skills checks" for mechanical maintenance engineers. The candidates wnte and must pass such ten wntten examinations on the maintenance specifics, plant walk through and final assessment interviews before obtaining the qualification for the maintenance position This system has been recently implemented at our Kakrapar Atomic Power Station.

SAMPLE TEST QUESTIONS

This section is a set of sample test questions and skills checks for mechanical maintenance engineers The candidates wnte and must pass such ten wntten examinations on the maintenance specifics, plant walk through and final assessment interviews before obtaining the qualification for the maintenance position This system has been recently implemented at our Kakrapar Atomic Power Station.

MECHANICAL MAINTENANCE

GROUP MODERATOR SYSTEM & REACTIVITY MECHANISM(CODE - M-l) SUBSYSTEM MODERATOR MAIN SYSTEM (M-l/1)

01 List functional requirements of moderator pumps including dunng (i) normal operation

(11) reactor shutdown (m) class W power failure (iv) class III power failure (v) air supply failures

(vi) LOCA and such accidents

TABLE-II. TYPICAL JOB SPECIFIC KSA's (Mechanical Maintenance Engineers) requirements & bases and procedure

(* indicates critical pumps, valves, heat exchangers already identified in the list approved)

02 List functional specifications of Moderator Pump

03 List protections provided to the Moderator Pump and their bases 04 Explain construction of Moderator Pumps including of

(i) Impeller arrangement (n) Wearing ring locking (in) Air Labyrinth

(iv) Coupling (v) Bearing

(vi) Temperature limits (vii) Lubrication

05 Explain maintenance procedure.for moderator pumps including (i) Seal replacement

(n) Wearing nng replacement (m) Checking pump lifts (iv) Overhauling (v) Spares requirement

06 Discuss the major inspection and measurements on a new or suspect Moderator pump topping on overload frequently as well as showing high vibration time to time for analysis of causes including

(i) Pump shaft critical dimensions, TIR value, coaxiahty of key ways (n) Impeller accuracy

(in) Wear nng clearances (iv) shaft sleeve

(v) coupling

07 Inspect and clean suction strainer of moderator pump 3211 - P-l during planned shut down as per procedure Conduct functional test to ensure no leakage and delta-P as per plant requirements

08 Attend weld joint leak in moderator heat exchanger #1 inlet PT/PG-108 tapping and perform integrity checks as per code requirement

09 Crack has developed at socket weld joint of PG line (No-3211-4) in moderator system Repair the crack weld and perform integrity checks as per code requirement

10 Given that the moderator pump 3211-P-3 bearing indicator is in red zone, perform pump bearing inspection

11 Perform overhauling of 321 l-P-3 moderator pump to bnng downs its vibration level from 40 micron to acceptable (30 micron) levels Perform vibration analysis of 3211-P#1

12 Given the symptom that 321 l-MV-#8 is passing, rectify by stroke adjustment

13 Inspect and clean suction strainer of moderator pump necessary post maintenance check and functional tests

ANNEX B. ANALYSIS

B.I. COMPETENCE PROFILE AND SOFT SKILLS NEEDS ANALYSIS TOOL FOR