ML20084F388

Responds to Request for Clarification of Several Issues Addressed in Re Standby Diesel Generators. Complete Disassembly & Insp Should Be Performed on Engine Operating Most Hours

ML20084F388
Person / Time
Site:	Grand Gulf
Issue date:	04/17/1984
From:	Laity W Battelle Memorial Institute, PACIFIC NORTHWEST NATION
To:	Berlinger C Office of Nuclear Reactor Regulation
Shared Package
ML20084F372	List: ML20084F381 ML20084F388
References
NUDOCS 8405040112
Download: ML20084F388 (3)

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ENCLOSURE 4

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1 OBattelle

. p.o.ses m ApM1 17, 1984 mcm.nd, w wnsion u.s.a. ms2 r e (emi 375-2780 Teles 15 2BN Mr. Carl Berlinger Division of Licensing Office of Nuclear Reactor Regulation -

U.S. Nuclear Regulatory Comunission Washington, D.C. 20555

SUBJECT:

GRAND GULF NUCLEAR POWER STATION STANDBY DIESEL GENERATORS This letter is in response to your request for claMfication of several issues addressed in PNL's letter of ApM 1 16, same subject. -

1. Question: What is the rationale for rolling over the engine once per hour (with the indicator cocks open) duMng the furst four hours after shutdown? Would it be acceptable to roll the engine after four-to-eight hours, and then once a day?

Response: Rolling the engine once per hour in the first four hours after shutdown would provide additional assurance that the engine is ready for an emergency start. If a crack formed in a cylinder head during engine operation and pmvided a path for water to enter a cylinder after shut-down, that water could damage the engine in an emergency start (and possibly prevent the engine from starting). It would be desirable to detect such leakage early.

As an engine cools down and metal contracts in the vicinity of a flaw, the likelihood of water leaking through the flaw increases. It is acceptable from the standpoint of the engine to n211 it over four-to-eight hours after shutdown to detect leakage, followed by a rollover ones per day. The increased frequency during the first four hours is a suggestion only, to provide the additional assurance referred to above.

2. (Luestion: What is the basis for the coment (in response to question 3 of the enclosure to the PNL letter of April 16) that random checks be perfomed of certain components?

Answer: Our response regarding random checks assumes that no engine is completely disassembled and inspected. It is not the reconsnended ap-preach. Our consultants agree unaminously that one engine should be completely torn down and inspected. Action on the second would be contingent on findings in the first. 1 l

l Enoine Recomended for Teardown: In our letter of April 16, we overlooked j 8405040112 840425 PDR ADOCK 05000416 S PDR

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. 1 Mr. Carl Berlinger OBaHelle April 17,1984 Page 2 documenting our reconstendation that the complete disassembly and inspection be perfomed on the engine that has been operated the most hours.

3. Question: Are the instrumentation monitors, and alarms listed in response to question 4 (PNL letter of April 16) in place in nuclear plants, and if not are they absolutely necessary?

Response: The time in which we have prepared this responsa has not pemitted us to detemine the instrumentation actually in place for these engines. However, it is customary for engines of this size in <

non-nuclear applications to be instrueented and monitored for the l pressures and temperatures discussed in our letter of April 16. Auto- ,

matic monitoring accompanied by appropriate alarms will notify the 1 operator of engine distress, so that timely action can be taken to shut down the engine during a test or transfer its load to another standby engine during an amargency. -

Accelerometers might not be installed on main bearings, for bearing temperature rather than bearing vibration is normally monitored in large diesel engines. The accelerometers are not considered to be a necessity. If they are installed, they shouTThe monitored. -

We believe that surveillance of the type we have suggested is necessary, but details of how this surveillance can best be accomplished in a

} nuclear power plant are negotiable.

4. Question: What is the rationale for the additional preoperational tests outlined in response to question 5 (PNL letter of April 16)?

Response: The twelve starts (10 " modified" starts plus two " quick" starts), and the 24-hour run, are suggested as one way to provide confidence that an engine will perfom its mission following reassembly.

The start tests are suggested in the light of the emphasis placed on engines in nuclear service to start reliably. A continuous run for

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some appropriate time is necessary to detech abnomal temperatures and/or temperature excursions that might indicate engine distress.

If the post-assembly tests reconmended by the manufacturer provide appropriate coverage of these considerations, they should take prec-odence.

5. Question: Is the assumption of operating with emergency loads only (approximately 68% of full load) during the period to first refueling an important consideration in the coments provided by PNL? (Would these connents change if the engine were allowed to operate with ad-ditional, non-essential loads that would increase overall engine load toward10057)

Response: There are several key components in question that are s'

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D4?'G,'ns"" OBanelle Page 3 to stresses in direct proportion to engine load. Accordingly, restMeting the engines to emergency loads only provides greater confidence that the engines will meet emergency requirecents. We believe it would be prudent to invoke this restM etion.

Please do not hesitate to call if you have any questions on- this letter.

Since mly, j n 1 -/ f Traxx Walter W. Laity W PNL Project Manager WWL:wl cc: M. Plahuta. DOE-RL i

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