05000361/LER-2015-002, Regarding Spent Fuel Pool Temperature Drifted Below Updated Final Safety Analysis Report (UFSAR) Value
| ML16015A409 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 01/12/2016 |
| From: | Bosch L Southern California Edison Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| LER 15-002-00 | |
| Download: ML16015A409 (4) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(ii)(B), Unanalyzed Condition 10 CFR 50.73(a)(2)(ii)(A), Seriously Degraded 10 CFR 50.73(a)(2)(viii)(B) 10 CFR 50.73(a)(2)(iv)(A), System Actuation 10 CFR 50.73(a)(2)(x) 10 CFR 50.73(a)(2)(v)(A), Loss of Safety Function - Shutdown the Reactor 10 CFR 50.73(a)(2)(v)(B), Loss of Safety Function - Remove Residual Heat 10 CFR 50.73(a)(2)(i)(A), Completion of TS Shutdown 10 CFR 50.73(a)(2)(v), Loss of Safety Function 10 CFR 50.73(a)(2)(i) |
| 3612015002R00 - NRC Website | |
text
- .., SOUTHERN CALIFORNIA A,& FDISON P'NTERNATJONAL t* Company Lou Bosch Plant Manager 10 CFR 50.73(a)(2)(ii)(B)
January 12, 2016 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, D.C. 20555-0001
Subject:
Docket Nos. 50-361, 50-362 LER 2015-002-00, Spent Fuel Pool Temperature Drifted Below Updated Final Safety Analysis Report (UFSAR) Value San Onofre Nuclear Generating Station (SONGS), Units 2 and 3
Dear Sir or Madam:
Attached is Licensee Event Report (LER) 201 5-002-00, which is being submitted in accordance with 10 CFR 50.73(a)(2)(ii)(B).
This letter does not contain any regulatory commitments. If you have any questions regarding the attached report, please call Mr. James Kay at (949) 368-7418.
Sincerely, 7 r Attachment: LER 2015-002-00 cc:
M. L. Dapas, Regional Administrator, NRC Region IV M. G. Vaaler, NRC Project Manager, San Onofre Units 2 and 3
NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY 0MB: NO. 31 50-01 04 EXPIRES: 10/31/2018 (1-05)
, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.
- 1. FACILITY NAME 2
OKTNME
.PG San Onofre Nuclear Generating Station (SONGS) Unit 2 05000 311O
- 4. TITLE Spent Fuel Pool Temperature Drifted Below Updated Final Safety Analysis Report (UFSAR) Value
- 5. EVENT DATE
- 6. LER NUMBER
- 7. REPORT DATE
- 8. OTHER FACILITIES INVOLVED lEIJ TIL RE FACILITY NAMIE DOCKET NUMBER MONTH DAY YEAR YEAR SEUENTA RV MONTH IDAY YEAR SNSUi 50 6
NUMBERN O.
SOGInt3 50 6
11 19 2015 2015 002 00 01 I12 2016 I 05000
- 9. OPERATING MODE
- 11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR §: (Check all that apply)
ND 20.2201(b)
I' 20.2203(a)(3)(ii)
D 50.73(a)(2)(ii)(A)
[]
50.73(a)(2)(viii)(B) 20.2203(a)(2)(i) 50.36(o)(1 )(i)(A)
[]
50.73(a)(2)(iv)(A) j*] 50.73(a)(2)(x)
- 10. POWER LEVEL D* 20.2203(a)(2)(ii)
D 50.36(0)(1)(ii)(A) 50.73(a)(2)(v)(A)
D* 73.71 (a)(4)
D--20.2203(a)(2)(iii)
[] 50.36(c)(2) 50.73(a)(2)(v)(B)
I-173.71 (a)(5).
N/A D
20.2203(a)(2)(v)
[--
50.73(a)(2)(i)(A)
D 50.73(a)(2)(v)(O)
D 73.77(a)(2)(i)
_____:_____________*I D
50.73(a)(2)(i)(C) i'-1OTHER specify in Abstract below or in A. REPORTABLE OCCURRENCE On November 19, 2015, a review of Operations Logs determined that the San Onofre Nuclear Generating Station (SONGS) Unit 2 Spent Fuel Pool (SFP) temperature had drifted approximately two degrees below the analyzed temperature of 68 degrees F on several previous days. This was reported as an unanalyzed condition under 10 CER 50.72(b)(3)(ii)(B) because the Updated Final Safety Analysis Report (UFSAR) and the spent fuel analysis identified 68 degrees F as the lower temperature design basis for the SEP. This 60-day report is submitted under 10 CFR 50.73(a)(2)(ii)(B), Degraded or Unanalyzed Condition.
B. INITIAL CONDITIONS Both units at SONGS were permanently shutdown (Unit 2 on January 9, 2012, Unit 3 on January 31, 2012) and defueled. The SEP Cooling systems for both units were operating normally.
C. BACKGROUND INFORMATION
Each unit at SONGS has its own SEP [EllS Code DA]. Each SFP is cooled by each unit's Component Cooling Water (CCW) system, which is cooled by the Pacific Ocean. SONGS is in the process of installing an independent SEP cooling system for each unit for Decommissioning.
When the plant was operating, the CCW system also cooled other plant loads. As a result, there was a significant difference between the SEP temperature and the ocean temperature. Currently, the SEP is the only significant heat load remaining on the CCW system. With significantly cooler fuel in each pool, the difference between the pool temperature and the ocean temperature has decreased.
D. DESCRIPTION OF OCCURRENCE While establishing test criteria for an independent SEP cooling system for each SONGS unit, Engineering personnel identified that the spent fuel criticality calculation used a lower pool temperature limit of 68 degrees F.
The SONGS UFSAR listed the 68 degrees F as the lower temperature design basis. However, there was no mention of the lower temperature limit in any other document that would have made SONGS Operations personnel aware that the pool temperature was outside of the analyzed range.
On the day of the discovery, Operations and Engineering staff noted that the pool temperature had decreased to 70 degrees F. Site staff prepared an Operations procedure revision that would allow Operations personnel to secure the SEP Cooling pumps if the pool temperature continued to drop. The ocean temperature increased shortly afterward, as did the SEP temperature, so Operations personnel did not have to implement the newly revised procedure at that time.
The initial investigation of the SEP temperature for Unit 2 revealed that there were several days in the previous months when the pool temperature drifted below the 68 degree F limit. As a result, this event was reported as an 8-hour notification to the NRC in accordance with 10 CER 50.72(b)(3)(ii)(B) on November 19, 2015.
Page 3 of 3U.S. NUCLEAR REGULATORY COMMISSION (11-2015)
LICENSEE EVENT REPORT (LER)
CONTINUATION SHEET
- 3. LER NUMBER YEAR SEQUENTIAL REV San Onofre Nuclear Generating Station 05000-361UMERNO (SONGS) Unit 2 361.
0 0
Reviews of Operations Logs and data obtained during Operator Rounds back to January 2013 identified additional incidents of the SEP temperature drifting below 68 degrees F for each unit. Based on available data, 41 days for Unit 2 and 45 days for Unit 3 were identified. The typical drift was up to 2 degrees below 68 degrees F with the lowest recorded temperature of approximately 61 degrees F one time each for Unit 2 and for Unit 3.
E. APPARENT CAUSE The SONGS Units 2 and 3 UFSAR, Section 9.1.2.3, Safety Evaluation, listed the SEP temperature range as 68 degrees F to 160 degrees F as part of the SEP design basis.
The lower design basis temperature of the SEP provided in the UFSAR had not been translated into procedures or any other site document. When the units were operating, the higher spent fuel residual heat load prevented the SEP temperature from drifting towards the lower temperature limit.
F. CORRECTIVE ACTIONS
The SONGS Units 2 and 3 spent fuel criticality calculation was updated using existing input data to establish a new low temperature limit of 50 degrees F. The results of the calculation were updated to include the new lower temhperature limit. With this update, the criticality analysis is valid for a temperature range of 50 degrees F to 160 degrees F for each unit's spent fuel pool.
The Updated Final Safety Analysis Report (UFSAR), Section 9.1.2.3, Safety Evaluation, was updated to document the spent fuel pool temperature range from 50 degrees F to 160 degrees F.
The Spent Fuel Pool Operations procedure was revised to provide actions to secure all SEP Cooling Pumps prior to the pool temperature reaching 55 degrees F.
The Daily Shift Manager Status Sheet used during Operations Shift Turnover was modified to include a notation under SEP Temperature to "Maintain above 50 degrees F."
G. SAFETY ASSESSMENT
This event did not affect facility operation or safety. There was no impact on the health and safety of plant personnel or the public. The criticality acceptance criteria specified in 10 CFR 50.68 were met at all times as determined by the analysis update.
H. ADDITIONAL INFORMATION
There have been no similar reportable events in the past three years at SONGS.