ML20245E864
| ML20245E864 | |
| Person / Time | |
|---|---|
| Issue date: | 07/27/1989 |
| From: | Houston R NRC OFFICE OF NUCLEAR REGULATORY RESEARCH (RES) |
| To: | Rasin W NUCLEAR ENERGY INSTITUTE (FORMERLY NUCLEAR MGMT & |
| Shared Package | |
| ML20245E867 | List: |
| References | |
| REF-GTECI-128, REF-GTECI-A-30, REF-GTECI-EL, REF-GTECI-NI, TASK-128, TASK-A-30, TASK-OR NUDOCS 8908140030 | |
| Download: ML20245E864 (6) | |
Text
-_ - -
M 0.,,
' UNITED STATES
$. j' g
NUCLEAR REGULATORY COMMISSION
- i
<j W ASHINGTON, D. C. 20555 1,,
- o. + g/
1 JUL 2 1989 Mr. William Rasin, Director Technical Division Nuclear Management and Resources Council 1776 Eye Street N.W.
Suite 300 Washington, D.C. 20006-2496 Deer Mr. Rasin:
As you are aware..the NRC staff is in the final phase of resolving Generic Issue A-30 (G1 A-30), Adequacy of Safety-Related DC Power Supplies.
The staff is planning to issue a ger.eric letter on A-30 that contains a number of questions which seek information on de systems at all plants. The informa-tion is intended to allow the staff to verify that all licensees have addressed recommendations made by various organizations including NRC, IEEE and INPO.
Since the stnf talieves that many etilities have already addressed a large numLcr rf these recommendations, the effort involved on the part of the licensees is not expected to cause a major expenditure of resources to respond to the questions.
To help achieve a common understanding of the information sought and to facilitate the responses to the proposed generic letter on Generic Issue A-30, Mr. R. Bell of your organization has suggested a meeting. We welcome your cooperation'in obtaining this information. Therefore, we are enclosing a draft copy of the A-30 generic letter and attached questions and the INEL report for your use in preparing for the meeting. We are scheduled to issue this letter by October. Therefore, the meeting should be held relatively soon so as not to delay issuance.
Please contact Dale Thatcher of my staff to set up a mutually convenient date for a meeting.
/
o.
/ R. Wayne Houston', Director L'" Division of Safety Issue Resolution Office of Nuclear Regulatory Research
Enclosures:
Proposed Generic Letter INEL report EGG-NTA-8197 cciJPDR E..>
]
OfDI R. Haroldsen, INEL R. Bell, NUMARC 1
i F. Rosa i
8905140030 890727 PDR REVGP ERGNUMRC PDC
u u
p Enclosure i
.. DRAFT GENERIC' LETTER
- 4...
.x ALL HOLDERS OF OPERATING LICENSES T0:
RESOLUTION OF GENERIC ISSUE GI A-30 " ADEQUACY OF SAFETY-
SUBJECT:
RELATED DC POWER SUPPLIES" The NRC staff has completed the evaluation of Generic issue A-30, which focuses provides a on safety-related de systems. Attachment 1 to this Generic LetterAdditional det' ails are pr brief description and history of this Gl.As a result of its evaluation, the Staff believ the reference.
maintenance', surveillance and monitoring provisions are appropriate for safety-The Staff believes that most plants have already implemented related dc systems.
a major portion of these provisions because of a number of actions taken by the Details of these actions are provided in the reference.
Staf f and industry.
In order to determine whether any further Staff actions are necessary at your plant, we require, pursuant to 10 CFR 50.54(f) and Section 182 of the Atomic Energy Act, that you provide the NRC with a response to the questions in theThis infor attachment within 180 days of the date of this letter.
(
be submitted to NP.C signed under oath and-affirmation.
It should be noted that the NRC has recognized that an " Individual Plant Examination (IPE) For Severe Accident Vulnerabilities" could provide a vehicle for addressing Unresolved Safety / Generic Safety Issues as outlined in Generic Therefore, the attachment to this letter gives the option of Letter 88-20.
providing certain supporting information as part of the IPE instead of supplying it in response to this letter.
This request is covered by Office of Management and Budget Clearance Number 3150-0011, which expires December 31, 1989. The estimated average burden hours is 100 man-hours per licensee response, including assessment of the questions, searching data sources, gathering and analyzing the data, and preparing the Comments on the accuracy of this estimate and suggestions to required reports.
reduce the burden may be directed to the Office of Management and Budget, Room 3208, New Executive Office Building, Washington, D.C. 20503, and to the U. S.
Nuclear Regulatory Comission, Records and Reports Management Branch, Office o Administration and Resources Management, Washington, D. C. 20555 If you have any questions, please contact your project manager.
Sincerely, 10 CFR 50.54(f) Request - GI A-30 " Adequacy of Safety-Related dc
Attachment:
Power."
EGG-NTA-8197, Revision 1. "Tec.inical Findings for Generic Issue 128 (Issue A-30), " Adequacy of Safety Related DC Power Supplies"
Reference:
4 t
ATTACHMENT
. g )0 CFR 50.54(f) REQUEST - GI A-30 " ADEQUACY,"OF S AFET Y-REL AT E D. DC" POWER 'TSUPPL I ES" P
===.
Background===
The specific area of concern of Generic Issue A-30 is the adequacy of the safety-i related de power in operating nuclear power plants, particularly with regard to multiple and common cause failures.
Risk analysis and past plant experience
{
support conclusions that failure of the de power supplies could represent a Analysis significant contribution to the unreliability o.f shutdown' cooling.
l indicates that inadequate maintenance and surveillance and failure to detect battery unavailability are the prime contributors to failure of the dc power systems.
i During the development of plans to resolve Generic Issue A-30, it was observed t
that several previously issued notices, bulletins and letters submitted to licensees include recommendations similar to those that have been identified to resolve Issue A-30.
More specifically, it has been determined that recommenda-tions contained in notifications IEN 85-74, IEB 79-27, the Institute of Nuclear Power Operations' Significant Operating Experience Report (50ER) 83-5, and separate actions being taken to resolve Generic Issue 49 include the elements necessary to resolve Generic Issue A-30.
It is therefore concluded that licensees that have implemented these recommendations and actions will have The response to the questions that follow is resolved Generic Issue A-30.
necessary to provide the staff with information to determine whether any further action is required for your facility.
Questions The following information is to be provided for each unit at each site with two possible exceptions:
For questions involving supporting type information Exceptions:
(question numbers 5 and 8) instead of developing and supplying the information in response to this letter, you may commit to further evaluate the need for such provisions during the performance of your IpE. If you select this option, you are required to:
(1) So state in response to these questions, and (2) Commit to explicitly address questions 5 and 8 in your IPE submittal.
1.
Unit The number of independent redundant divisions of Class 1E or safety-2.
a.
related dc power for this plant is
. (Include any separate Class IE or safety related oc, such as any dc dedicated to the diesel generators.)
i 4
)
e 2
~
'~l The number' of functional safety-related divisions of de p'ow'er" b '.
necessary to attain safe shutdown for this unit is Does the control room at this unit have the following separate, independently annunciated alarms and indications for each division of de power?
3.
l a.
alarms Battery disconnect or circuit breaker open?
1.
Battery charger disconnect or circuit breaker open (both input 2.
ac and output dc)?
3.
de system ground?
4.
dc bus undervoltage?
l 5.
dc has overvoltage?
6.
Battery charger failure?
7.
Battery discharge?
b.
Indications 1.
Battery float charge current?
2.
Battery circuit cutput current?
3.
Battery discharge?
4.
Bus voltage?
Does the unit have written procedures for response to the above alarms c.
and indications?
Does this unit have indication of bypassed and inoperable status of circuit breakers or other devices that can be used to disconnect the 4.
battery charger from its ac power source during maintenance or testing?
If the answer to any part of question 3 or 4 is no, then provide information justifying the existing design features of the facility's safety-related 5.
de systems.
Have you conducted a review of maintenance and testing activities (1) to minimize the potential for human error causing more than one dc 6.
a.
and (2) do plant procedures division to be unavailable?
prohibit maintenance or testing on redundant dc divisions at the same time?
a
o 4
3
"~' '*
-b, Do maintenance and test ' procedures "for this plant include provisions for rotation of qualified personnel and systematic verifica-tion of activities completed by other qualified personnel for mainten-ance and testing of the safety-related dc systems?
NOTE:
If this facility has the provisions equivalent to those found in the Westinghouse and Combustion Engineering Standard Technical Specifications for maintenance and surveillance, then questions 7 and 8 may be skipped and a
. statement to that effect may be inserted here.
7.
Are maintenance, surveillance and test procedures regarding station batteries conducted routinely at this plant? Specifically:
At least once per 7 days are the following verified to be within a.
acceptable limits:
1.
Pilot cell electrolyte level?
2.
Specific gravity or charging current?
3.
4.
Total bus voltage on float charge?
5.
Physical condition of all cells?
b.
At least once per 92 days, or within 7 days efter a battery discharge, overcharge, or if the pilot cell readings are outside the 7-day surveillance requirements are the following verified to be within acceptable limits:
1.
Electrolyte level of each cell?
2.
The average specific gravity of all cells?
3.
The specific gravity of each cell?
4.
The average electrolyte temperature of a representative number of cells?
5.
The float voltage of each cell?
6.
Visually inspect or measure resistance of terminals and connectors (including the connectors at the dc bus)?
At least every 18 months are the following verified:
c.
1.
Low resistance of each connection (by test)?
i
.e i'
4
' 7 '*.
~ ' '
2.
Physic'al conditTon of 'the battery?
a 3.
Battery charger capability to deliver rated ampere output to the dc bus?
4.
The capability of the battery to deliver its design duty l
cycle to the dc bus?
5.
Each individual cell voltage is within acceptable limits during the service test?
d.
At least every 60 months, is capacity of each battery verified by performance of a discharge test?
e.
At least annually, is the battery capacity verified by performance discharge test, if the battery shows signs of degradation or has reached 85% of the expected service life?
8.
If the answer to any part of question 6 or 7 is no, then provide your basis for not performing the maintenance, surveillance and test procedures described.
9.
Does this plant have operational features such that following loss of one safety-related dc power supply or bus:
Capability is maintained for ensuring continued and adege'te a.
reactor cooling?
b.
RCS integrity and isolation capability are maintained?
Operating procedures, instrumentation (including indicators and c.
annunciators), and control functions are tdequate to initiate systems as required to maintain adequate core cooling?
i