Document ID: EPA-HQ-OAR-2008-0708-0285
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2010-02-19T05:00Z

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  |"Crockett, Steven" <Steven.Crockett@nrc.gov>                                                                                              
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  |"Higgins, Cortney" <Cortney_Higgins@omb.eop.gov>, RobertJ 
Wayland/RTP/USEPA/US@EPA, Melanie King/RTP/USEPA/US@EPA, Michael                
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  |Horowitz/DC/USEPA/US@EPA                                                                                                                  
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  |"Grahame, Thomas" <Thomas.Grahame@HQ.DOE.GOV>, "Wolfgang, Robert" 
<Robert.Wolfgang@nrc.gov>, "Lombard, Mark" <Mark.Lombard@nrc.gov>,      |
  |"Imboden, Andy" <Andy.Imboden@nrc.gov>, "Droggitis, Spiros" 
<Spiros.Droggitis@nrc.gov>                                                    
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  |02/05/2010 01:25 PM                                                                                                                       
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  |NRC standards on maintenance and testing                                                                                                  
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You've asked for some description of the NRC's maintenance and testing 
standards on emergency diesels that fall within its jurisdiction. Below, I 
briefly describe the program and provide links to the key documents.
There may be a further comment later today, or perhaps further documentation, 
but I hope that what's below contains the core of our response. At least it 
will move the discussion along.

Let me first make a general comment about our stance towards EPA's draft final 
rule. As we did in the case of EPA's Spill Prevention, Control, and 
Countermeasures rule, we're taking no position on whether the rule should 
apply to the diesels in the NRC's jurisdiction -- and EPA tells us that's not 
really an open question anyway. We're not fans of having two regulators 
overseeing the same machine for different purposes, but we recognize EPA's 
Clean Air Act jurisdiction here, and this is not a case like the cases 
involvling radionuclide emissions, where we and EPA were seeking to regulate 
the same thing for the same purpose (e.g., Yucca Mountain, decommissioning, 
radionuclide emissions to air). We're aiming mainly at providing information 
about our program, and at understanding, as best we can in the short time 
allotted, whether there's anything in the rule's approach to maintenance and 
testing that might raise a nuclear safety concern. These diesels are critical 
to ensuring safety in emergency conditions; so of course the maintence and 
testing of these diesels is critically important to us. And that's so whether 
we're talking existing diesels or new ones; the fact that the rule imposes no 
retrofits on existing emergency diesels doesn't eliminate the possibility that 
the rule might raise a nuclear safety concern.

However, to the extent that we understand this complicated rule -- necessarily 
complicated because of its great scope -- we don't think it raises a nuclear 
safety issue, at least not as a general matter, though details matter (and we 
note one below). Our principal standard on maintenance, 10 CFR 50.65, is a 
"performance-based" rule, and so leaves scope for variation in maintenance 
practices. Annually changing the very large quantity of oil in a huge diesel 
engine designed to provide emergency power to an operating nuclear power 
reactor is no light matter, but, in and of itself, it needn't pose an 
unacceptable risk.
Similarly, we have testing guidance (listed below), but EPA's rule appears to 
leave room for its application.

What can matter though are detailed prescriptions. The reliability of EDGs can 
be one of the main factors affecting the risk of core damage from a station 
blackout. Changes of any kind in a safety-related system or component – 
including imposition of prescriptive maintenance procedures or maintenance 
schedules – could impact the prevention or mitigation of the consequences of 
accidents at nuclear reactors, because changes to the established maintenance 
procedures for an emergency diesel could impact its reliability or 
availability.  Excessive maintenance could negatively impact the availability 
of the system or component, and excessive testing could negatively impact its 
reliability. For these reasons, we're concerned about one aspect of EPA’s 
prescriptive schedule for performing management practice
requirements: EPA appears to allow delays in maintenance only when the diesel 
is operating in response to an ongoing emergency. See page 163, footnote 4. 
The NRC’s approach, on the other hand, is designed to minimize overall risk. 
10 CFR 50.65(a)(4) states, “before performing maintenance activities … the 
licensee shall assess and manage the increase in risk that may result from the 
proposed maintenance activities.” This applies to emergency diesels, with the 
result that the NRC rule might allow a delay in maintenance when the EPA rule 
would not.
Could the footnote be expanded somehow to incorporate a judgment about overall 
risk? Could it say, for example, the following? "If an emergency engine is 
operating during an emergency and it is not possible to shut down the engine 
in order to perform the management practice requirements on the schedule 
required in the final rule, or if shutting the engine down would otherwise 
pose an unacceptable risk under federal, state, or local law, the management 
practice can be delayed until the emergency is over.  The management practice 
should be performed as soon as practicable after the emergency has ended, or 
the unacceptable risk has abated."

We're less concerned about the rule's testing requirements, even though we've 
taken great care in the area of testing (see below), in order to avoid the 
extremes of too much testing (and therefore unnecessary wear and tear), or too 
little (and therefore inadequate demonstration of reliability). We're less 
concerned about the rule's requirements here, because they appear to leave 
room for the appropriate application of other federal, state, or local 
standards (see pages 148-49), and that would include the NRC's important 
guidance on the subject.

I hope that, in the future, when EPA is engaged in rulemaking that might apply 
to the NRC's licensee, the two agencies will be able to consult earlier than 
they were able to this time. Earlier consultation proved useful in the cases 
of EPA rulemaking on water intake structures and underground diesel fuel 
tanks. We keep an eye out for EPA rulemakings, but we sometimes miss them. I 
hope that the little consultation we've had these past few days has been 
useful to both agencies, and I hope too that we'll continue the consultation 
if unexpected issues should arise in the course of implementing the rule.

NRC DOCUMENTS ON MAINTENANCE AND TESTING OF EMERGENCY DIESEL GENERATORS AT 
NUCLEAR POWER PLANTS.

- 10 CFR 50.63, Loss of all alternating current power.

- 10 CFR 50.65, Requirements for monitoring the effectiveness of maintenance 
at nuclear power plants.

- Regulatory Guide 1.160, “Monitoring the Effectiveness of Maintenance at 
Nuclear Power Plants”, esp. pages 4-5.
http://adamswebsearch2.nrc.gov/idmws/doccontent.dll?library=PU_ADAMS^PBNTAD01&
ID=003970364

- Regulatory Guide 1.155, "Station Blackout."
http://adamswebsearch2.nrc.gov/idmws/doccontent.dll?library=PU_ADAMS^PBNTAD01&
ID=003957121

- Regulatory Guide 1.9, "Application and Testing of Safety-Related Diesel 
Generators in Nuclear Power Plants."
http://www.nrc.gov/reading-rm/doc-collections/reg-guides/power-
reactors/active/01-009/01-009.pdf

- American Society of Mechanical Engineers document ASME OM-S/G 2007, 
"Standards and Guides for Operation and Maintenance of Nuclear Power Plants," 
is also in use at nuclear power plants. Part 16 of this document applies to 
emergency diesel generators. This document has not been formally approved by 
the NRC, but NRC staff participated in its development.