ML20235J174
| ML20235J174 | |
| Person / Time | |
|---|---|
| Site: | Byron, Braidwood, 05000000 |
| Issue date: | 07/08/1987 |
| From: | Ainger K COMMONWEALTH EDISON CO. |
| To: | NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM) |
| References | |
| 3286K, NUDOCS 8707150430 | |
| Download: ML20235J174 (4) | |
Text
.
4+,
.;/
Commonwealth Edison j
- d, <' One First Nuional Plaza, Chicago, Illinois Address Reply to: Post Office Box 767 1
Chicago, Illinois 60600 0767 p
July 8,-1987, U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555
Subject:
Byron Station Units 1 & 2 Braidwood Station Units 1 & 2 Emergency Diesel Generator Missile Effects NRC Docket Nos. 50-454/455 & 50-456/457 Reference (a): March 17, 1987 letter from K.A. Ainger to H.R. Denton Gentlemen:
Reference (a) provided the results of a re-evaluation of the effects of missiles generated from a potential failure of an' emergency diesel generator engine at Byron and Braidwood Stations..This analysis acknowledged that missiles were possible, but due to the arrangement of systems at Byron and Braidwoood, would not result in loss of safety function beyond the diesel.
Enclosed with this letter is.an advance copy of FSAR changes that describe the conclusions from this re-evaluation of diesel generator missiles. These changes will be included in a future FSAR amendment.
please direct any questions regarding this matter to this office.
3 Very truly yours, K. A. Ainger Nuclear Licensing Administrator Enclosure cc: NRC Region III Office Byron Resident Inspector Braidwood Resident Inspector J. Gavula g7150430870708*
p ADOCK 05000454 PDR 3286K D
B/B-FSAR AMENDMENT 43 SEPTEMBER 1983 3.5 MISSILE PROTECTION 3.5.1 Missile Selection and Description The systems located both inside and outside containment have been examined to identify and classify potential missiles.
The basic approach is to assure design adequacy against generation of missiles, rather than allow missile formation and try to contain their effects.
3.5.1.1 Internally Generated Missiles (Outside Containment)
The principal design bases are that missiles generated outside of containment but internal to the plant site shall not cause loss of function of any design feature provided for either continued safe operation or shutdown during operating conditions, operational transients, and postulated accident conditions associated with the effects of missile formation.
The seismic category and quality group classifications for these systems are identified in Section 3.2.
Equipment has been evaluated for potential missile sources.
As a result of this review, the following information concerning potential missile sources and systems which require protection from internally generated missiles outside containment is proviana-(ihSEILT l)
There are no internally. generated missiles postulated outside the containment, other than the ain turbine missiles described in Subsection 3.5.1.3.
The following items suggested as potential missiles re not credible for the reasons stated:
diesel generador MI55ile6 and Og,,
a.
Valve stems--All valve stems are either back-seated or have plugs, both of which would absorb the kinetic energy of a stem being thrown by impact with the bonnet gland, without exceeding the ultimate strength of retaining components.
b.
Valve bonnets--Failure of bonnet flange bolts in such a way that the bonnet can become a missile is not credible since both the flanges and bolts / studs are designed to the safety factors inherent in Section III and the relatively higher potential failure mechanisms are such that missiles will not be generated.
c.
Instrument wells--All instrument wells forming part of the process piping pressure boundary are connected by a welded construction having a minimum of three times the structural strength required by the Code.
3.5-1 i
i l
l i
INSERT 1 Failure of an emergency diesel generator may result in generation of internal missiles within the engine itself. Under a limited range of specific conditions, these missiles could penetrate the engine block and strike objects external to the engine. An assessment of these postulated l
missiles demonstrated that the missiles would not leave the diesel room and would not strike any components within the room which would adversely affect the operability of redundant systems or impair the capability to safely shut down the plant. This assessment was described in a March 17, 1987 letter from K.A. Ainger to H.R. Denton.
1 j
i i
l l
l
B/B-FSAR AMENDMENT 22 SEPTEMBER 1979 QUESTION 010.15 "You indicate that you have not postulated potential internally generated missile sources such as valve bonnets, instrument wells, and pump impellers outside of containment.
It is our position that you perform an analysis and evaluation for all areas of the plant housing safety related equipment assuming potential internal missiles generated from the above mentioned sources.
This eval--
uation should verify that no damage to safety related equipment will result which would prevent a safe shutdown."
3 1
l
RESPONSE
Each manufacturer has evaluated his equipment from the stand-point of potential failures that would result in missiles i
being generated.
The main turbine missiles are described j
in Subsection 3.5.1.3.J Other components which are considered to have a potential for missile generation are discussed in Subsection 3.5.1.2.1.
No other internally generated mis-i siles were postulated in safety-related buildings because the manufacturers have determined that missiles will not be generated by their components.
l Subsection 3.5.1 has been revised to further describe the potential missiles which were considered.
I-The eMec4s of Wssiles resu l+iap [roa failure o[ an e.84c3ency dieseJ y.ne color are ageyssed in E bsu f;,n 3.s.l.l.
J t
l Q10.15-1
- _ _ _ _ _ _ _ _ - _ _ _ _ _ _ _ _ _ _ - _ - _ _