ML20137A727
| ML20137A727 | |
| Person / Time | |
|---|---|
| Site: | Calvert Cliffs  |
| Issue date: | 03/13/1997 |
| From: | Cruse C BALTIMORE GAS & ELECTRIC CO. |
| To: | NRC |
| References | |
| FRN-62FR7811, RTR-REGGD-01.134, RTR-REGGD-1.134 62FR7811-00002, 62FR7811-2, NUDOCS 9703210048 | |
| Download: ML20137A727 (6) | |
Text
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CHARLES II. CHUSE Baltimore Gas and Electric Company Vice President Calvert Cliffs Nuclear Power Plant Nuclear Energy 1650 Calvert Cliffs Parkway Lusby, Maryland 20657
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March 13,1997
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U. S. Nuclear Regulatory Commission 55 [
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b ATTENTION:
Rules Review and Directives Branch
SUBJECT:
Calvert Cliffs Nuclear Power Plant Unit Nos.1 & 2; Docket Nos. 50-317 & 50-318 Comments on Proposed Revision 3 to Regulatory Guide 1.134, Medicci Evaluation of Licensed Personnel at Nuclear Power Plants The Baltimore Gas and Electric Company is pleased to provide comments on the subject proposed regulatory guide.
This regulatory guide is being revised to endorse an updated American National Standards Institute /American Nuclear Society (ANSI /ANS)-3.4-1996, " Medical Certification and Monitoring of Personnel Requiring Operator Licenses for Nuclear Power Plants." The standard describes methods acceptable to the Nuclear Regulatory Commission (NRC) staff for determining the medical qualifications of applicants for operator licenses for nuclear power plants, and for notifying the NRC of an operator's incapacitating disability or illness. Our comments relate to two of the requirements in the ANSI /ANS standard which we feel are impractical and unnecessary. Detailed technical comments are attached.
First, we recommend against routine measurement of aerobic capacity using exercise testing, especially l
given the minimal physical requirements for sedentary workers. Given the low incidence of activity-I related (especially with minimal exertion) cardiac events in middle-age men, the uncertain benefit of restricting activity in those with abnormal test results, and the high costs of screening and follow-up, the potential benefit of exercise testing appears small. The inconvenience, expense, and potential risks of routine screening with exercise testing in asymptomatic adults might be justified if it significantly reduced the incidence of myocardial infarction and sudden cardiac death, but there is no evidence to indicate this. Programs emphasizing primary prevention, by means of lowering cholesterol levels in hypercholerstolemic patients, treating hypertension, and reducing smoking, are much more effective in preventing cardiac events, fll N.b /dhnt)O fQ[.rSp
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' Rules Review and Directives Branch March 13,1997 Page 2 Second, we recommend against routine screening with liver function tests. Given the low sensitivity and specificity of these tests and the diagnostic dilemmas, often involving costly and unyielding results, these are not effective in screening for problem drinking and other common liver abnormalities.
In summary, we feel that the proposed regulatory guide should not be issued in its current form. It should only be issued if the requirements for routine measurement of aerobic capacity using exercise testing and routine screening with liver function tests are removed. This could be done by endorsing the updated standard as an acceptable alternative to the current standard. We feel the current guidance provides an adequate basis for Medical Certification and Monitoring of Personnel Requiring Operator Licenses for Nuclear Power Plants.
Should you have questions regarding this matter, we will be pleased to discuss them with you.
Very truly yours, CHC/SJR/bjd Attachment cc:
Document Control Desk, NRC H. J. Miller, NRC D. A. Brune, Esquire Resident Inspector, NRC J. E. Silberg, Esquire R. I. McLean, DNR Director, Project Directorate I.1, NRC J. H. Walter, PSC A. W. Dromerick, NRC
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t ATTACHMENT (1) a i
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Baltimore Gas and Electric Company's Comments on Proposed Revision 3 l
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DG-1068 Medical Guide of Licensed Personnel at Nuclear Power Plants l
Calvert Cliffs Nuclear Power Plant Units 1 & 2 March 13,1997
MACHMENT (1)
Baltimore Gas and Electric Company's Comments on Proposed Revision 3 Regulatory Guide 1.134 DG-1968 Medical Guide of Licensed Personnel at Nuclear Power Plants WITH SPECIFIC REFERENCE TO:
1.
Section 5.3.6 Laboratory:
The Physician shall note test results which indicate an absence of significant abnormalities in the 4
following:
.., liver function test (alanine aminotransferase (ALT) and aspartate aminotransferase (AST) as a minimum]
2.
Section 5.3.4 Respiratory:
... A capability to perform strenuous physical exertion le emergencies and an ability to use respiratory protective equipment shall be demonstrated.
3.
Section 5.3.5 Cardiovascular:
... Stamina shall be evaluated through the use of a treadmill, bicycle ergonometer, or other valid and reliable testing method for measuring aerobic capacity. The minimum passing criterion for this requirement shall be a maximum aerobic capacity of at least 25 cm3 (cc) of oxygen per kilogram per minute. Exercise testing shall assess aerobic capacity and fitness and shall not be used specifically to determine the presence of ischemic heart disease. In marginal cases, physician judgment concerning the individual's overall physical condition may be used to supersede results showing inadequacy.
l COMMENTS:
With reference to measuring aerobic caoacity:
According to the 1996 Report of the U.S. Preventive Services Task Force, most persons with asymptomatic coronary artery disease (CAD) do not have a positive exercise electrocardiogram (EKG).
Electrocardiogram changes often do not become apparent until an atherosclerotic plaque has progressed to the point that it significantly impedes coronary blood flow. In addition, most asymptomatic persons with an abnonnal exercise EKG result do not have underlying CAD. Specifically, a 1989 meta-analysis summary of existing medical literature found considerable variability in the accuracy of exercise-induced ST depression [ segment of the EKG] for predicting CAD (sensitivity 23-100%, specificity 17-100%).
Although asymptomatic persons with a positive exercise EKG are more likely to experience an event than those with negative tests, longitudinal studies following such patients from 4-13 years have shown that only 1-11% will suffer an myocardial infarction (MI) or sudden death. Unstable angina, MI, and sudden death often result from an acute, occluding thrombus precipitated by the rupture of a mild, non-flow-limiting plaque. Among healthy men who subsequently developed symptomatic CAD after a negative screening test, 73% experienced an M1 or sudden death as their initial manifestation. In contrast, the majority of asymptomatic persons with a positive exercise EKG develop angina as their initial event. Thus, while exercise EKG may predict the presence of more severe coronary stenosis and risk of angina in asymptomatic persons, it does not accurately predict risk of acute coronary events.
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1 ATTACHMENT (1)
Baltimore Gas and Electric Company's Comments on Proposed Revisinn 3 Regulatory Guide 1.134 DG-1068 Medical Guide of Licensed Personnel at Nuclear Power Plants False-positive screening exercise EKG test results are undesirable for asymptomatic coronary disease for several reasons:
1.
Persons with abnormal results frequently undergo invasive diagnostic procedures, such as coronary angiography, with serious medical risks and tremendous costs; 2.
Abnormal test results may produce considerable and unnecessary anxiety; and 3.
An abnormal EKG tracing may disqualify some patients from job, insurance eligibility, and other opportunities.
Preliminary exercise EKG testing has also been recommended for sedentary persons planning to begin vigorous exercise programs, based on evidence that strenuous exertion may increase the risk of sudden cardiac death. The usual underlying cause of sudden cardiac death during exercise is hypertrophic cardiomyopathy or congenital coronary anomalies in young persons, and CAD in older persons. Cardiac events during exercise in persons without symptomatic heart disease is uncommon, however, and exercise EKG may not accurately predict those who are at risk. Among over 3,600 asymptomatic, hypercholesterolemic middle-aged men who underwent submaximal exercise EKG testing during the Lipid Research Clinics Coronary Prevention Trial,62 (2%) subsequently experienced an acute coronary event during moderate or strenuous physical activity during follow-up (average 7.4 years). Although men with er.ercise-induced EKG changes were at increased risk, only 11 of 62 events occurred in men with an abnormal baseline exercise test (sensitivity 18%), Moreover, few of the men with abnormal test results experienced an activity-related event during follow-up (positive predictive value 4%). Although the negative predictive value of baseline EKG was high (over 98%), it was no better than multivariate analysis based on risk factors (e.g., high blood pressure, high cholesterol, and smoking) alone.
With reference to liver function tests:
According to the 1996 Report of the U.S. Preventive Services Task Force, laboratory tests are generally insensitive and non-specific for problem drinking and many other medical conditions. Elevations in hepatocellular enzymes, such as AST, are found in less than 10% of drinkers. Serum gamma-glutamyltransferase (GGT) is more sensitive (33-60%) in various studies, but not very speci6c as elevations may be due to other causes (medications, trauma, diabetes, and heart, kidney, or biliary tract disease). Even when the prevalence of problem drinking is extremely high (10%), the predictive value of an elevated GGT has been estimated at only 56%. Given these limitations, the U.S. Preventive Services Task Force advises against such routine measurement of biochemical markers. Careful history taking, inquiring about alcohol use patterns and/or the use of standardized screening questionnaires (e.g., CAGE or AUDIT), is deemed to be helpful in identifying problem drinkers.
Furthermore, asymptomatic patients with abnormal results on liver function tests pose an ongoing diagnostic challenge to physicians. Because of the poor sensitivity and specificity (including the possibility of laboratory error) of these tests, there often results costly and time-involved laboratory testing (even to the point of referrals and even liver biopsy, without signi6 cant yield, but with medical risks), ill-denned practice standards for such follow-up which further contributes to the cost ineffectiveness, and unnecessary worry on the part of patients.
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ATTACHMENT (1)
Baltimore Gas and Electric Company's Comments on Proposed Revision 3 Regulatory Guide 1.134 DG-1068 Medical Guide of Licensed Personnel at Nuclear Power Plants CONCLUSIONS:
1.
We recommend against routine measurement of aerobic capacity using exercise testing, especially given the minimal physical requirements for sedentary workers. Given the low incidence of activity-related (especially with minimal exertion) cardiac events in middle-age men, the uncertain benefit of restricting activity in those with abnormal test results, and the high costs of screening and follow-up, the potential benefit of exercise testing appears small. The inconvenience, expense, and potential risks of routine screening with exercise testing in asymptomatic adults might be justified ifit significantly reduced the incidence of MI and sudden cardiac death, but there is no evidence to indicate this. Programs emphasizing primary prevention, by means of lowering cholesterol levels in hypercholerstolemic patients, treating hypertension, and reducing smoking, are much more effective in pieventing cardiac events.
2.
We recommend against routine screening with liver function tests. Given the low sensitivity and specificity of these tests and the diagnostic dilemmas, often involving costly and unyielding results, these are not effective in screening for problem drinking and other common liver abnormalities.
REFERENCES:
1.
Report of the U.S. Preventive Services Task Force, Guide to Clinical Preventive Services, Second Edition,1996, Williams and Wilkins, Baltimore 2.
Theal, R. M. and Scott, K., Evaluating Asymptomatic Patients with Abnormal Liver Function Test Results, American Family Physician, May 1,1996 3