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SAN ONOFRE NUCLEAR GENERATING STATION | 3 Months Ended
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Mar. 31, 2018
Regulated Operations [Abstract] |
San Onofre Nuclear Generating Station (SONGS) | REGULATORY MATTERS We discuss regulatory matters in Note 14 of the Notes to Consolidated Financial Statements in the Annual Report, and provide updates to those discussions and information about new regulatory matters below. REGULATORY ASSETS AND LIABILITIES We show the details of regulatory assets and liabilities in the following table.
REGULATORY ASSETS (LIABILITIES)
(Dollars in millions)
| March 31, 2018 |  | December 31, 2017
SDG&E: |  |  |
Fixed-price contracts and other derivatives | $ | 103 |  |  | $ | 96 |
Deferred income taxes refundable in rates | (305 | ) |  | (281 | )
Pension and other postretirement benefit plan obligations | 170 |  |  | 153 |
Removal obligations | (1,827 | ) |  | (1,846 | )
Unamortized loss on reacquired debt | 8 |  |  | 9 |
Environmental costs | 29 |  |  | 29 |
Sunrise Powerlink fire mitigation | 120 |  |  | 119 |
Regulatory balancing accounts(1) |  |  |
Commodity – electric | 112 |  |  | 82 |
Gas transportation | 19 |  |  | 22 |
Safety and reliability | 52 |  |  | 48 |
Public purpose programs | (83 | ) |  | (70 | )
Other balancing accounts | 149 |  |  | 233 |
Other regulatory liabilities | (89 | ) |  | (70 | )
Total SDG&E | (1,542 | ) |  | (1,476 | )
SoCalGas: |  |  |  |  |
Pension and other postretirement benefit plan obligations | 529 |  |  | 513 |
Employee benefit costs | 45 |  |  | 45 |
Removal obligations | (910 | ) |  | (924 | )
Deferred income taxes refundable in rates | (395 | ) |  | (437 | )
Unamortized loss on reacquired debt | 7 |  |  | 8 |
Environmental costs | 21 |  |  | 22 |
Workers’ compensation | 12 |  |  | 12 |
Regulatory balancing accounts(1) |  |  |
Commodity – gas, including transportation | 168 |  |  | 151 |
Safety and reliability | 275 |  |  | 266 |
Public purpose programs | (353 | ) |  | (274 | )
Other balancing accounts | (149 | ) |  | (114 | )
Other regulatory liabilities | (85 | ) |  | (64 | )
Total SoCalGas | (835 | ) |  | (796 | )
Sempra Mexico: |  |  |
Deferred income taxes recoverable in rates | 83 |  |  | 83 |
Total Sempra Energy Consolidated | $ | (2,294 | ) |  | $ | (2,189 | )
(1) | At March 31, 2018 and December 31, 2017, the noncurrent portion of regulatory balancing accounts – net undercollected for SDG&E was $72 million and $63 million, respectively. At March 31, 2018 and December 31, 2017, the noncurrent portion of regulatory balancing accounts – net undercollected for SoCalGas was $141 million and $118 million, respectively.
CALIFORNIA UTILITIES MATTERS CPUC General Rate Case The CPUC uses a GRC proceeding to set sufficient rates to allow the California Utilities to recover their reasonable cost of O&M and to provide the opportunity to realize their authorized rates of return on their investment. 2019 General Rate Case On October 6, 2017, SDG&E and SoCalGas filed their 2019 GRC applications requesting CPUC approval of test year revenue requirements for 2019 and attrition year adjustments for 2020 through 2022. SDG&E and SoCalGas requested revenue requirements for 2019 of $2.199 billion and $2.989 billion, respectively, which is an increase of $217 million and $533 million over their respective 2018 revenue requirements (the 2018 revenue requirements reflect the impact of updated testimony filed in January 2018). The California Utilities are proposing post-test year revenue requirement changes using various adjustment factors which are estimated to result in annual increases of approximately 5 percent to 7 percent at SDG&E and approximately 6 percent to 8 percent at SoCalGas. Our 2019 GRC applications do not reflect the impact of the TCJA, which we discuss in “2016 General Rate Case” below, in Note 1 above and in Note 6 of the Notes to Consolidated Financial Statements in the Annual Report. In April 2018, SDG&E and SoCalGas updated their applications to reflect the impact of the TCJA and filed a joint proposal to address the impacts. The TCJA impact to SDG&E is a reduction of approximately $58 million to its 2019 test year revenue requirement; however, SDG&E’s 2019 requested revenue requirement is unchanged as we evaluate potentially higher costs associated with mitigating wildfire risks. The TCJA impact to SoCalGas’ 2019 requested revenue requirement is a reduction of approximately $58 million to $2.931 billion. In April 2018, ORA filed testimony in SDG&E’s and SoCalGas’ 2019 GRC recommending a 2019 revenue requirement of $1.918 billion and $2.695 billion, respectively, which is a net decrease of $64 million and an increase of $239 million compared to the respective 2018 revenue requirements. ORA’s proposal reduces the three-year annual attrition percentages to 4 percent for SDG&E and a range of 4 percent to 5 percent for SoCalGas. ORA recommends addressing SDG&E’s potential ownership of OMEC in a separate proceeding. As a result, ORA’s proposed 2019 revenue requirement does not include the estimated $68 million associated with owning and operating the generating facility. SDG&E’s acquisition of OMEC is subject to a CPUC-approved agreement under which the current owner of the facility can exercise a put option at a designated price on or before October 3, 2019, as we discuss in Note 1. As part of the 2019 GRC, the CPUC will review the California Utilities’ interim accountability reports, which compare the authorized and actual spending for certain safety-related activities for 2014 through 2016. In June 2017, SDG&E and SoCalGas filed their first interim accountability reports comparing authorized and actual spending in 2014 and 2015 for certain safety-related activities. Similar data for 2016 was provided with the 2019 GRC application filings in a second interim accountability report. The stated purpose of the interim accountability reports is to provide data and metrics for key safety and risk mitigation areas that will be considered in the 2019 GRC. The results of the rate case may materially and adversely differ from what is contained in the GRC applications. Risk Assessment Mitigation Phase Reporting and Impact on the 2019 GRC Application Filings In December 2014, the CPUC issued a decision incorporating a risk-based decision-making framework into all future GRC application filings for major natural gas and electric utilities in California. The framework is intended to assist in assessing safety risks and the utilities’ plans to help ensure that such risks are adequately addressed. In advance of filing the California Utilities’ 2019 GRC applications discussed above, two proceedings occurred: the Safety Model Assessment Proceeding and the RAMP. In the Safety Model Assessment Proceeding, the California Utilities demonstrated the models used to prioritize and mitigate risks in order for the CPUC to establish guidelines and standards for these models. In November 2016, as part of the new framework, SDG&E and SoCalGas filed their first RAMP report presenting a comprehensive assessment of their key safety risks and proposed activities for mitigating such risks. The report details these key safety risks, which include critical operational issues such as natural gas pipeline safety and wildfire safety, and addresses their classification, scoring, mitigation, alternatives, safety culture, quantitative analysis, data collection and lessons learned. In March 2017, the CPUC’s Safety and Enforcement Division issued its evaluation report providing generally favorable feedback on the California Utilities’ RAMP report, but recommending more detailed analysis of the risks the California Utilities presented in the report. The new GRC framework does not require the CPUC to adopt the RAMP report. However, SDG&E and SoCalGas included funding requests in their respective 2019 GRC filings for proposed projects or activities outlined in their RAMP reports. In April 2018, the CPUC granted SDG&E’s and SoCalGas’ motion to close the proceeding, as all RAMP procedures have been completed. Senate Bill 549. In September 2017, SB 549 was signed into law, requiring that SDG&E and SoCalGas (as electric and gas corporations) annually notify the CPUC when revenue authorized by the CPUC for maintenance, safety or reliability is redirected to other purposes. This requirement is effective beginning January 1, 2018. The form of this reporting is not yet defined by the CPUC, though it could be incorporated into an ongoing proceeding or report otherwise required to be submitted to the CPUC. 2016 General Rate Case As we discuss in Notes 6 and 14 of the Notes to Consolidated Financial Statements in the Annual Report, the 2016 GRC FD issued by the CPUC in June 2016 required SDG&E and SoCalGas to each establish a two-way income tax expense memorandum account to track certain revenue variances resulting from certain differences between the income tax expense forecasted in the GRC and the income tax expense incurred from 2016 through 2018. The tracking accounts will remain open until the CPUC decides to close the accounts, which we expect will be reviewed in the 2019 GRC proceedings. At March 31, 2018, the recorded regulatory liability associated with these tracked amounts totaled $67 million and $77 million for SDG&E and SoCalGas, respectively. The recorded liability is primarily related to lower income tax expense incurred than was forecasted in the GRC relating to tax repairs deductions, self-developed software deductions and certain book-over-tax depreciation. Impacts of the TCJA. As we discuss in Note 1, in the fourth quarter of 2017, we recorded the effect of the remeasurement of our deferred income tax balances at the new federal statutory income tax rate enacted by the TCJA. The remeasurement of deferred income tax balances at SDG&E and SoCalGas resulted in excess deferred income taxes from amounts previously collected from ratepayers at the higher rate. These excess deferred income taxes have been recorded as regulatory liabilities and will be refunded to ratepayers in accordance with the IRC’s normalization provisions and as determined by the CPUC and the FERC. The income tax effects from the TCJA that we recorded in 2017 were provisional. We may adjust our provisional estimates in future reporting periods throughout 2018, and these adjustments may affect regulatory liabilities, the tracking accounts and/or earnings. The 2016 GRC FD revenue requirement was authorized using a federal income tax rate of 35 percent. As a result of the TCJA, the federal income tax rate became 21 percent effective January 1, 2018. Since SDG&E and SoCalGas continue to collect 2018 authorized revenues based on a 35 percent tax rate, SDG&E and SoCalGas are recording revenue deferrals, aligned with authorized seasonality factors, that reflect the estimated reduction in the 2018 revenue requirement. As of March 31, 2018, SDG&E and SoCalGas recorded regulatory liabilities of $18 million and $19 million, respectively, in anticipation of amounts that will benefit customers in future rates. SDG&E also recorded a $15 million regulatory liability at March 31, 2018 for its FERC jurisdiction in anticipation of amounts that will benefit customers in future rates for the decrease in the federal income tax rate. CPUC Cost of Capital In October 2017, the CPUC approved the embedded cost of debt presented in the filed advice letters, resulting in a revised return on rate base for SDG&E of 7.55 percent and for SoCalGas of 7.34 percent, effective January 1, 2018, as depicted in the table below:
AUTHORIZED COST OF CAPITAL AND RATE STRUCTURE – CPUC
SDG&E |  | SoCalGas
Authorized weighting | Return on rate base | Weighted return on rate base |  | Authorized weighting | Return on rate base | Weighted return on rate base
45.25 | % | 4.59 | % | 2.08 | % | Long-Term Debt | 45.60 | % | 4.33 | % | 1.97 | %
2.75 |  | 6.22 |  | 0.17 |  | Preferred Stock | 2.40 |  | 6.00 |  | 0.14 |
52.00 |  | 10.20 |  | 5.30 |  | Common Equity | 52.00 |  | 10.05 |  | 5.23 |
100.00 | % |  |  | 7.55 | % |  | 100.00 | % |  |  | 7.34 | %
As a result of the updates included in the filed advice letters, the impact of the changes to the embedded cost of debt and return on rate base is summarized below:
IMPACT OF THE EMBEDDED COST OF DEBT |
| SDG&E |  | SoCalGas
| Cost of debt | Return on rate base |  | Cost of debt | Return on rate base
Previously | 5.00 |  | % | 7.79 |  | % |  | 5.77 |  | % | 8.02 |  | %
Authorized, effective January 1, 2018 | 4.59 |  | % | 7.55 |  | % |  | 4.33 |  | % | 7.34 |  | %
Differences | (41 | ) | bps | (24 | ) | bps |  | (144 | ) | bps | (68 | ) | bps
The automatic CCM will be in effect to adjust 2019 cost of capital, if necessary. Unless changed by the operation of the CCM, the updated costs of long-term debt and the new ROEs will remain in effect through December 31, 2019. The cost of capital changes will also apply to capital expenditures in 2018 and 2019 for incremental projects not funded through the GRC revenue requirement.SAN ONOFRE NUCLEAR GENERATING STATION We provide below updates to ongoing matters related to SONGS, a nuclear generating facility near San Clemente, California that ceased operations in June 2013, and in which SDG&E has a 20-percent ownership interest. We discuss SONGS further in Note 13 of the Notes to Consolidated Financial Statements in the Annual Report. SONGS STEAM GENERATOR REPLACEMENT PROJECT As part of the SGRP, the steam generators were replaced in SONGS Units 2 and 3, and the Units returned to service in 2010 and 2011, respectively. Both Units were shut down in early 2012 after a water leak occurred in the Unit 3 steam generator. Edison concluded that the leak was due to unexpected wear from tube-to-tube contact. At the time the leak was identified, Edison also inspected and tested Unit 2 and subsequently found unexpected tube wear in Unit 2’s steam generator. These issues with the steam generators ultimately resulted in Edison’s decision to permanently retire SONGS. The replacement steam generators were designed and provided by MHI. In 2013, Edison instituted arbitration proceedings against MHI seeking recovery of damages. The other SONGS co-owners, SDG&E and the City of Riverside, participated as claimants and respondents. On March 13, 2017, the International Chamber of Commerce International Court of Arbitration Tribunal (the Tribunal) overseeing the arbitration found MHI liable for breach of contract, subject to a contractual limitation of liability, and rejected the claimants’ other claims. The Tribunal awarded $118 million in damages to the SONGS co-owners, but determined that MHI was the prevailing party and awarded it 95 percent of its arbitration costs. The damage award was offset by these costs, resulting in a net award of approximately $60 million in favor of the SONGS co-owners. SDG&E’s specific allocation of the damage award was $24 million reduced by costs awarded to MHI of approximately $12 million, resulting in a net damage award of $12 million, which was paid by MHI to SDG&E in March 2017. In accordance with the Amended Settlement Agreement discussed below, SDG&E recorded the proceeds from the MHI arbitration by reducing Operation and Maintenance for previously incurred legal costs of $11 million, and shared the remaining $1 million equally between ratepayers and shareholders. SETTLEMENT AGREEMENT TO RESOLVE THE CPUC’S ORDER INSTITUTING INVESTIGATION INTO THE SONGS OUTAGE In 2012, in response to the SONGS outage, the CPUC issued the SONGS OII, which was intended to determine the ultimate recovery of the investment in SONGS and the costs incurred since the commencement of this outage. In November 2014, the CPUC issued a final decision approving an Amended Settlement Agreement in the SONGS OII proceeding. We describe the terms and provisions of the Amended Settlement Agreement in Note 13 of the Notes to Consolidated Financial Statements in the Annual Report. In May 2016, following the filing of petitions for modification by various parties, the CPUC issued a procedural ruling reopening the record of the OII to address the issue of whether the Amended Settlement Agreement is reasonable and in the public interest. In December 2016, the CPUC issued another procedural ruling directing parties to the SONGS OII to determine whether an agreement could be reached to modify the Amended Settlement Agreement previously approved by the CPUC, to resolve allegations that unreported ex parte communications between Edison and the CPUC resulted in an unfair advantage at the time the settlement agreement was negotiated. On January 30, 2018, SDG&E, Edison, ORA, TURN and other intervenors entered into a settlement agreement (the Revised Settlement Agreement). On the same date, a Joint Motion for Adoption of the Settlement Agreement was filed with the CPUC. If approved by the CPUC, the Revised Settlement Agreement will resolve all issues under consideration in the SONGS OII and will modify the Amended Settlement Agreement. The Revised Settlement Agreement was the result of multiple mediation sessions in 2017 and January 2018 and was signed following a settlement conference in the SONGS OII, as required under CPUC rules. In February 2018, the parties filed a motion to stay the proceedings in the OII pending the CPUC’s consideration of the Revised Settlement Agreement. In February and March of 2018, the CPUC granted the parties’ request and established a procedural schedule for 2018 that includes additional testimony, a status conference and briefing, and public participation and evidentiary hearings in April through July. The Revised Settlement Agreement is subject to CPUC approval. The parties to the Revised Settlement Agreement have agreed to exercise their best efforts to obtain CPUC approval. In the event that the CPUC fails to approve the Revised Settlement Agreement, the proceeding will remain open and subject to previous rulings in the SONGS OII, and the Amended Settlement Agreement will remain in effect, unless it is modified or set aside by the CPUC as a result of the OII proceeding. In connection with the Revised Settlement Agreement, and in exchange for the release of certain SONGS-related claims, SDG&E and Edison entered into the Utility Shareholder Agreement, described below, in which Edison has agreed to pay for the amounts that SDG&E would have received in rates under the Amended Settlement Agreement but would not receive upon implementation of the Revised Settlement Agreement. The Utility Shareholder Agreement is not subject to the approval of the CPUC. However, it is not effective unless and until the CPUC approves the Revised Settlement Agreement. The timing of a ruling by the CPUC on the Joint Motion for Adoption of the Settlement Agreement is unclear. There is no assurance that the Revised Settlement Agreement will be adopted or that the Amended Settlement Agreement will not be modified or set aside as a result of the OII proceeding, which could result in a substantial reduction in our expected recovery or in no recovery and payments to customers. These outcomes could have a material adverse effect on Sempra Energy’s and SDG&E’s results of operations, financial condition and cash flows. Disallowances, Refunds and Recoveries If the Revised Settlement Agreement is approved by the CPUC, SDG&E and Edison will cease rate recovery of SONGS costs as authorized under the Amended Settlement Agreement as of the date their combined remaining SONGS regulatory assets equal $775 million (the Cessation Date). Currently, the estimated Cessation Date is December 19, 2017. The Cessation Date is partly dependent on the outcome of Edison’s pending request to the CPUC, in a separate proceeding, for approval to apply certain proceeds received from the DOE to reduce Edison’s SONGS regulatory asset. If this request is rejected by the CPUC, then the estimated Cessation Date will be April 21, 2018. In either case, under the Utility Shareholder Agreement, Edison is obligated to pay SDG&E the full amount of SDG&E’s revenue requirement not recovered from ratepayers, as described below. SDG&E and Edison will refund to customers SONGS-related amounts recovered in rates after the Cessation Date. In the event that the CPUC takes an action that has the effect of invalidating the Utility Shareholder Agreement, SDG&E may, in its discretion, withdraw from the Revised Settlement Agreement, in which case Edison shall remain a party to the Revised Settlement Agreement, but the Revised Settlement Agreement shall be terminated as to SDG&E. In such a scenario, SDG&E would return to its litigation position before the CPUC in the SONGS OII that existed prior to the Revised Settlement Agreement. Pursuant to the CPUC’s rules, no settlement becomes binding unless the CPUC approves the settlement based on a finding that it is reasonable in light of the whole record, consistent with law, and in the public interest. The CPUC has discretion to approve or disapprove a settlement, or to condition its approval on changes to the settlement, which the parties may accept or reject, negotiating in good faith to seek a resolution acceptable to all parties. CPUC rules do not provide for any fixed time period for the CPUC to act on proposed settlements. Utility Shareholder Agreement On January 10, 2018, SDG&E and Edison entered into the Utility Shareholder Agreement. Under the terms of the Utility Shareholder Agreement, Edison has an obligation to compensate SDG&E for the revenue requirement amounts that SDG&E would no longer recover because of the Revised Settlement Agreement. In exchange for Edison’s reimbursement, the parties will mutually release each other from the “SONGS Issues,” a defined term that consists of 18 broad categories. The effect of the agreement is that the parties will release each other from any and all claims that each party had or could have asserted related to the steam generator replacement failure and its aftermath. The Utility Shareholder Agreement becomes effective only upon CPUC approval of the Revised Settlement Agreement. Edison’s payment obligation commences 30 days after the first fiscal quarter in which the CPUC approves the Revised Settlement Agreement, and amounts are due to SDG&E quarterly thereafter until April 2022, which approximates the amounts and timing of amounts of what would have been SDG&E’s recoveries from ratepayers contemplated under the Amended Settlement Agreement. Accounting and Financial Impacts As a result of the Revised Settlement Agreement by the settling parties and the Utility Shareholder Agreement, at March 31, 2018, SDG&E has a receivable from Edison totaling $153 million, $42 million classified as current and $111 million classified as noncurrent. This receivable reflects amounts Edison is obligated to pay to SDG&E in lieu of amounts SDG&E would have collected from ratepayers associated with the SONGS regulatory asset, which SDG&E believes is now no longer probable of recovery. Assuming the Revised Settlement Agreement is approved, SDG&E and Sempra Energy do not expect that implementation of the Revised Settlement Agreement in combination with the Utility Shareholder Agreement will have a material adverse impact on either company. However, until the CPUC approves the Revised Settlement Agreement as proposed, there can be no assurance that the SONGS OII proceeding will conclude as contemplated by SDG&E in accordance with the Revised Settlement Agreement and the Utility Shareholder Agreement, or that the CPUC will not order refunds to customers above those contemplated by the Amended Settlement Agreement, or take other action that may be adverse to SDG&E and Sempra Energy. Such alternative outcomes could have a material adverse effect on SDG&E’s and Sempra Energy’s results of operations, financial condition and cash flows. NUCLEAR DECOMMISSIONING AND FUNDING As a result of Edison’s decision to permanently retire SONGS Units 2 and 3, Edison began the decommissioning phase of the plant. Decommissioning of Unit 1, removed from service in 1992, is largely complete. The remaining work for Unit 1 will be done once Units 2 and 3 are dismantled. Edison contracted with a joint venture of AECOM and EnergySolutions (known as SONGS Decommissioning Solutions) as the general contractor to complete the dismantlement of SONGS. The majority of the dismantlement work is expected to take 10 years. SDG&E is responsible for approximately 20 percent of the total contract price. In accordance with state and federal requirements and regulations, SDG&E has assets held in the NDT to fund its share of decommissioning costs for SONGS Units 1, 2 and 3. The amounts collected in rates for SONGS’ decommissioning are invested in the NDT, which is comprised of externally managed trust funds. Amounts held by the NDT are invested in accordance with CPUC regulations. The NDT assets are presented on the Sempra Energy and SDG&E Condensed Consolidated Balance Sheets at fair value with the offsetting credits recorded in noncurrent Regulatory Liabilities. In March 2018, SDG&E and Edison jointly filed an application requesting CPUC approval of revised remaining decommissioning cost estimates (for costs estimated to be incurred in 2018 and beyond) for SONGS Unit 1 of $207 million (in 2014 dollars), of which SDG&E’s share is $41 million, and SONGS Units 2 and 3 of $3.2 billion (in 2014 dollars), of which SDG&E’s share is $638 million. In addition, SDG&E has estimated internal decommissioning costs of $3 million (in 2014 dollars) for SONGS Unit 1 and $43 million (in 2014 dollars) for SONGS Units 2 and 3. We expect a ruling by the CPUC on the joint application in 2019. Except for the use of funds for the planning of decommissioning activities or NDT administrative costs, CPUC approval is required for SDG&E to access the NDT assets to fund SONGS decommissioning costs for Units 2 and 3. SDG&E has received authorization from the CPUC to access NDT funds of up to $362 million for 2013 through 2018 (2018 forecasted) SONGS decommissioning costs. This includes up to $60 million authorized by the CPUC in January 2018 to be withdrawn from the NDT for forecasted 2018 SONGS Units 2 and 3 costs as decommissioning costs are incurred. In December 2016, the IRS and the U.S. Department of the Treasury issued proposed regulations that clarify the definition of “nuclear decommissioning costs,” which are costs that may be paid for or reimbursed from a qualified trust fund. The proposed regulations state that costs related to the construction and maintenance of independent spent fuel management installations are included in the definition of “nuclear decommissioning costs.” The proposed regulations will be effective prospectively once they are finalized; however, the IRS has stated that it will not challenge taxpayer positions consistent with the proposed regulations for taxable years ending on or after the date the proposed regulations were issued. SDG&E is awaiting the adoption of, or additional refinement to, the proposed regulations before determining whether the proposed regulations will allow SDG&E to access the NDT funds for reimbursement or payment of the spent fuel management costs incurred in 2016 and subsequent years. Further clarification of the proposed regulations could enable SDG&E to access the NDT to recover spent fuel management costs before Edison reaches final settlement with the DOE regarding the DOE’s reimbursement of these costs. Historically, the DOE’s reimbursements of spent fuel storage costs have not resulted in timely or complete recovery of these costs. We discuss the DOE’s responsibility for spent nuclear fuel below. The IRS held public hearings on the proposed regulations in October 2017. It is unclear when clarification of the proposed regulations might be provided or when the proposed regulations will be finalized. The following table shows the fair values and gross unrealized gains and losses for the securities held in the NDT. We provide additional fair value disclosures for the NDT in Note 9.
NUCLEAR DECOMMISSIONING TRUSTS
(Dollars in millions)
| Cost |  | Gross unrealized gains |  | Gross unrealized losses |  | Estimated fair value
At March 31, 2018: |  |  |  |  |  |  |
Debt securities: |  |  |  |  |  |  |
Debt securities issued by the U.S. Treasury and other |  |  |  |  |  |  |
U.S. government corporations and agencies(1) | $ | 44 |  |  | $ | — |  |  | $ | — |  |  | $ | 44 |
Municipal bonds(1) | 245 |  |  | 4 |  |  | (2 | ) |  | 247 |
Other securities(2) | 217 |  |  | 2 |  |  | (3 | ) |  | 216 |
Total debt securities | 506 |  |  | 6 |  |  | (5 | ) |  | 507 |
Equity securities | 172 |  |  | 321 |  |  | (2 | ) |  | 491 |
Cash and cash equivalents | 19 |  |  | — |  |  | — |  |  | 19 |
Total | $ | 697 |  |  | $ | 327 |  |  | $ | (7 | ) |  | $ | 1,017 |
At December 31, 2017: |  |  |  |  |  |  |
Debt securities: |  |  |  |  |  |  |
Debt securities issued by the U.S. Treasury and other |  |  |  |  |  |  |
U.S. government corporations and agencies | $ | 54 |  |  | $ | — |  |  | $ | — |  |  | $ | 54 |
Municipal bonds | 245 |  |  | 7 |  |  | (2 | ) |  | 250 |
Other securities | 215 |  |  | 3 |  |  | (1 | ) |  | 217 |
Total debt securities | 514 |  |  | 10 |  |  | (3 | ) |  | 521 |
Equity securities | 171 |  |  | 326 |  |  | (1 | ) |  | 496 |
Cash and cash equivalents | 16 |  |  | — |  |  | — |  |  | 16 |
Total | $ | 701 |  |  | $ | 336 |  |  | $ | (4 | ) |  | $ | 1,033 |
(1) | Maturity dates are 2018-2048.
(2) | Maturity dates are 2018-2064.
The following table shows the proceeds from sales of securities in the NDT and gross realized gains and losses on those sales:
SALES OF SECURITIES IN THE NDT
(Dollars in millions)
| Three months ended March 31,
| 2018 |  | 2017
Proceeds from sales(1) | $ | 210 |  |  | $ | 357 |
Gross realized gains | 4 |  |  | 45 |
Gross realized losses | (3 | ) |  | (5 | )
(1) | Excludes securities that are held to maturity.
Net unrealized gains and losses, as well as realized gains and losses that are reinvested in the NDT, are included in noncurrent Regulatory Liabilities on Sempra Energy’s and SDG&E’s Condensed Consolidated Balance Sheets. We determine the cost of securities in the trusts on the basis of specific identification. U.S. DEPARTMENT OF ENERGY NUCLEAR FUEL DISPOSAL Spent nuclear fuel from SONGS is currently stored on-site in an ISFSI licensed by the NRC or temporarily in spent fuel pools. In October 2015, the California Coastal Commission approved Edison’s application for the proposed expansion of the ISFSI at SONGS. The ISFSI expansion began construction in 2016 and is expected to be fully loaded with spent fuel by 2019 and to operate until 2049, when it is assumed that the DOE will have taken custody of all the SONGS spent fuel. The ISFSI would then be decommissioned, and the site restored to its original environmental state. Until then, SONGS owners are responsible for interim storage of spent nuclear fuel at SONGS. The Nuclear Waste Policy Act of 1982 made the DOE responsible for accepting, transporting, and disposing of spent nuclear fuel. However, it is uncertain when the DOE will begin accepting spent nuclear fuel from SONGS. This delay will lead to increased costs for spent fuel storage. SDG&E will continue to support Edison in its pursuit of claims on behalf of the SONGS co-owners against the DOE for its failure to timely accept the spent nuclear fuel. In April 2016, Edison executed a spent fuel settlement agreement with the DOE for $162 million covering damages incurred from 2006 through 2013. In May 2016, Edison refunded SDG&E $32 million for its respective share of the damage award paid. In applying this refund, SDG&E recorded a $23 million reduction to the SONGS regulatory asset, an $8 million reduction of its nuclear decommissioning balancing account and a $1 million reduction in its SONGS O&M cost balancing account. In September 2016, Edison filed claims with the DOE for $56 million in spent fuel management costs incurred in 2014 and 2015 on behalf of the SONGS co-owners under the terms of the 2016 spent fuel settlement agreement. In February 2017, the DOE reduced the request to approximately $43 million primarily due to reductions to the claimed fuel canister costs. SDG&E received its $9 million respective share of the claim from Edison in May 2017 and recorded the proceeds in balancing accounts or as reductions to regulatory assets for the benefit of ratepayers. In October 2017, Edison filed claims with the DOE for $58 million in spent fuel management costs incurred in 2016 on behalf of the SONGS co-owners under the terms of the 2016 spent fuel settlement agreement. SDG&E’s respective share of the claim is $12 million. In March 2018, the DOE issued its determination of allowable costs for the claim as $44 million with SDG&E’s respective share as $9 million. In April 2018, Edison requested reconsideration from the DOE of $1 million of the DOE’s deductions from the claimed amount. We expect the request for reconsideration to extend the claims process by a minimum of two months. It is unclear whether the DOE will approve the request and how much of the disputed amount will be recovered, if any. The 2016 spent fuel settlement agreement governs the submission of claims for costs incurred through December 31, 2016. It is unclear whether Edison will enter into a new settlement with the DOE or pursue litigation claims for spent fuel management costs incurred on or after January 1, 2017. NUCLEAR INSURANCE Edison requested and was granted approval in January 2018 by the NRC to reduce the nuclear liability and property damage insurance requirement. However, these changes in SONGS nuclear insurance levels require approval from all SONGS owners, as described below. SDG&E and the other owners of SONGS have insurance to cover claims from nuclear liability incidents arising at SONGS. Currently, this insurance provides $450 million in coverage limits, the maximum amount available, including coverage for acts of terrorism. In addition, the Price-Anderson Act provides an additional $110 million of coverage. If a nuclear liability loss occurs at SONGS and exceeds the $450 million insurance limit, this additional coverage would be available to provide a total of $560 million in coverage limits per incident. The SFP is a program that provides additional insurance. If a nuclear liability loss occurs at any U.S. licensed/commercial reactor and exceeds the $450 million insurance, all SFP participants would be required to contribute to the SFP. Effective January 5, 2018, the NRC approved Edison’s request to reduce the nuclear liability insurance requirement from $450 million to $100 million and withdraw from participation in the SFP for SONGS. On April 5, 2018, the SONGS co-owners approved withdrawing from participation in the SFP for SONGS, but maintaining the nuclear liability insurance coverage at current levels ($450 million). Confirmation of SONGS’ withdrawal from the SFP has been received and is effective January 5, 2018. The SONGS owners, including SDG&E, also maintain nuclear property damage insurance that exceeds the minimum federal requirements of $1.06 billion. This insurance coverage is provided through NEIL. The NEIL policies have specific exclusions and limitations that can result in reduced or eliminated coverage. Insured members as a group are subject to retrospective premium assessments to cover losses sustained by NEIL under all issued policies. SDG&E could be assessed up to $10.4 million of retrospective premiums based on overall member claims. All of SONGS’ insurance claims arising out of the failures of the MHI replacement steam generators have been settled with NEIL. Effective January 10, 2018, the NRC approved Edison’s request to reduce its minimum property damage insurance requirement for SONGS from $1.06 billion to $50 million. However, on April 5, 2018, the SONGS co-owners approved maintaining its current property damage insurance at $1.5 billion, but with a new $500 million property damage sublimit on the ISFSI. The nuclear property insurance program includes an industry aggregate loss limit for non-certified acts of terrorism (as defined by the Terrorism Risk Insurance Act) of $3.24 billion. This is the maximum amount that will be paid to insured members who suffer losses or damages from these non-certified terrorist acts.

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